MEDIA CONVEYING APPARATUS, MEDIA CONVEYING METHOD, AND NON-TRANSITORY RECORDING MEDIUM

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is based on and claims priority pursuant to 35 U.S.C. §119(a) to Japanese Patent Application No. 2023-026104, filed on Feb. 22, 2023, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND
Technical Field

Embodiments of the present disclosure relate to a media conveying apparatus, a media conveying method, and a non-transitory recording medium.

Related Art

In a media conveying apparatus such as a scanner, a medium may be skewed while being conveyed to be read. Such a skew may cause a failure in imaging the entire medium or cause the medium to collide with the sidewall of a conveyance passage, resulting in a jam of the medium (e.g., paper jam).

A media conveying apparatus is known that includes a plurality of feed rollers disposed at intervals in a direction orthogonal to a direction in which media are conveyed, to rotate independently to feed the media. When a skew of a medium is detected, the media conveying apparatus corrects the skew of the medium with the feed rollers having different circumferential speeds from each other.

SUMMARY

According to an embodiment of the present disclosure, a media conveying apparatus includes a first roller, a second roller, a first sensor, a second sensor, and circuitry. The first roller and the second roller are spaced apart in a direction orthogonal to a medium conveyance direction in which a medium is conveyed, to rotate independently to convey the medium. The first sensor is disposed downstream from the first roller in the medium conveyance direction. The second sensor is disposed downstream from the second roller in the medium conveyance direction. The circuitry sets a circumferential speed of the first roller to a first speed and a circumferential speed of the second roller to a second speed higher than the first speed to correct a skew of the medium when the first sensor detects the medium before the second sensor detects the medium. The first sensor and the second sensor are disposed in a same position when viewed in the direction orthogonal to the medium conveyance direction. The position of the first sensor in the direction orthogonal to the medium conveyance direction being the same as a rotational center position of the medium that rotates at a speed ratio of the second speed to the first speed.

According to an embodiment of the present disclosure, a media conveyance method includes conveying and setting. The conveying is conveying a medium with a first roller and a second roller spaced apart in a direction orthogonal to a medium conveyance direction, in which the medium is conveyed, to rotate independently to convey the medium. The setting is setting a circumferential speed of the first roller to a first speed and a circumferential speed of the second roller to a second speed higher than the first speed to correct a skew of the medium when a first sensor disposed downstream from the first roller in the medium conveyance direction detects the medium before a second sensor disposed downstream from the second roller in the medium conveyance direction detects the medium. The first sensor and the second sensor are disposed in a same position when viewed in a direction orthogonal to the medium conveyance direction. The position of the first sensor in the direction orthogonal to the medium conveyance direction is the same as a rotational center position of the medium that rotates at a speed ratio of the second speed to the first speed.

According to an embodiment of the present disclosure, a non-transitory recording medium stores a plurality of instructions which, when executed by one or more processors, causes the one or more processors to perform a method for controlling a media conveying apparatus. The method includes setting a circumferential speed of a first roller to a first speed and a circumferential speed of a second roller to a second speed higher than the first speed to correct a skew of a medium when a first sensor detects the medium before a second sensor detects the medium. The first roller and the second roller are spaced apart in the media conveying apparatus in a direction orthogonal to a medium conveyance direction in which the medium is conveyed, to rotate independently to convey the medium. The first sensor is disposed downstream from the first roller in the medium conveyance direction in the media conveying apparatus. The second sensor is disposed downstream from the second roller in the medium conveyance direction in the media conveying apparatus. The first sensor and the second sensor are disposed in a same position when viewed in the direction orthogonal to the medium conveyance direction. The position of the first sensor in the direction orthogonal to the medium conveyance direction is the same as a rotational center position of the medium that rotates at a speed ratio of the second speed to the first speed.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a media conveying apparatus according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating a conveyance passage inside the media conveying apparatus of FIG. 1;

FIG. 3 is a schematic diagram illustrating sensors according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram illustrating a pick roller and surrounding components in the media conveying apparatus of FIG. 1;

FIG. 5 is a schematic block diagram illustrating a configuration of the media conveying apparatus of FIG. 1;

FIG. 6 is a schematic block diagram illustrating a configuration of a storage device and a processing circuit of the media conveying apparatus of FIG. 1;

FIG. 7 is a flowchart of a medium reading process according to an embodiment of the present disclosure;

FIG. 8 is a flowchart of a skew determination process according to an embodiment of the present disclosure;

FIG. 9 is a continuation of the flowchart of FIG. 8;

FIG. 10 is a continuation of the flowchart of FIG. 8;

FIG. 11A is a schematic diagram illustrating a medium according to a first example;

FIG. 11B is a schematic diagram illustrating media according to a second example;

FIG. 12A is a schematic diagram illustrating a medium that is inclined to some extent;

FIG. 12B is a schematic diagram illustrating the medium of FIG. 12A after insufficient skew correction;

FIG. 13 is a schematic diagram illustrating a medium after excessive skew correction;

FIG. 14 is a graph illustrating an inclination of a medium according to an embodiment of the present disclosure;

FIGS. 15A to 15C are schematic diagrams illustrating the feeding of media according to an embodiment of the present disclosure;

FIG. 16A is a schematic diagram illustrating a medium according to an embodiment of the present disclosure;

FIG. 16B is a schematic diagram illustrating the medium of FIG. 16A inclined in the opposite direction;

FIG. 17 is a schematic diagram illustrating media according to an embodiment of the present disclosure; and

FIG. 18 is a schematic diagram illustrating a configuration of a processing circuit according to another embodiment of the present disclosure.

The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.

DETAILED DESCRIPTION

In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.

Referring to the drawings, embodiments of the present disclosure are described below.

As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

For the sake of simplicity, like reference signs denote like elements such as parts and materials having the same functions, and redundant descriptions thereof are omitted unless otherwise required.

As used herein, the term “connected/coupled” includes both direct connections and connections in which there are one or more intermediate connecting elements.

FIG. 1 is a perspective view of a media conveying apparatus 100, which is an image scanner according to the present embodiment.

The media conveying apparatus 100 conveys and images media, which are documents. The media are, for example, sheets of plain paper, sheets of thick paper, or cards. Alternatively, the media conveying apparatus 100 may be, for example, a facsimile machine, a copier, or a multifunction peripheral (MFP). The media to be conveyed may be, for example, printing material (e.g., paper sheets) instead of documents. In this case, the media conveying apparatus 100 may be, for example, a printer.

In FIG. 1, arrow A1 indicates a substantially vertical direction (height direction). Arrow A2 indicates a media conveyance direction in which media are conveyed. Arrow A3 indicates a media ejection direction in which media are ejected. Arrow A4 indicates a width direction orthogonal to the media conveyance direction indicated by arrow A2 or the media ejection direction indicated by arrow A3. In the following description, the height direction indicated by arrow A1, the media conveyance direction indicated by arrow A2, the media ejection direction indicated by arrow A3, and the width direction indicated by arrow A4 may be referred to as a height direction A1, a media conveyance direction A2, a media ejection direction A3, and a width direction A4, respectively. In the following description, “upstream” refers to “upstream” in the media conveyance direction A2 or the media ejection direction A3, whereas “downstream” refers to “downstream” in the media conveyance direction A2 or the media ejection direction A3.

The media conveying apparatus 100 includes, for example, a first housing 101, a second housing 102, a receptacle 103, an output receptacle 104, an operation device 105, and a display device 106.

The second housing 102 is disposed inside the first housing 101 and is rotatably engaged with the first housing 101 with a hinge such that the second housing 102 can be opened and closed to, for example, remove a jammed medium or clean the inside of the media conveying apparatus 100.

The receptacle 103 is engaged with the first housing 101 such that the media to be conveyed can be placed on the receptacle 103. The receptacle 103 is movable in the height direction A1 on a medium-supply side of the first housing 101. The medium-supply side of the first housing 101 is a side from which the media are supplied into the first housing 101. When no medium is conveyed, the receptacle 103 is positioned at the lower end in the movable range of the receptacle 103 to facilitate the placement of media on the receptacle 103. When a medium is conveyed, the receptacle 103 is raised to a position so that an uppermost medium of the media placed on the receptacle 103 comes into contact with a pick roller described later.

The output receptacle 104 is formed on the second housing 102. The output receptacle 104 receives the medium ejected from a common discharge port of the first housing 101 and the second housing 102.

The operation device 105 includes an input device such as keys and an interface circuit that acquires signals from the input device. The operation device 105 receives an input operation performed by a user and outputs an operation signal corresponding to the input operation performed by the user. The display device 106 includes a display and an interface circuit that outputs image data to the display, to display the image data on the display. Examples of the display include, but are not limited to, a liquid crystal and an organic electro-luminescence (EL). The display device 106 may be a liquid crystal display with a touch panel function. In this case, the operation device 105 includes an interface circuit that acquires input signals from the touch panel.

FIG. 2 is a diagram illustrating a conveyance passage inside the media conveying apparatus 100 according to the present embodiment.

For example, the media conveying apparatus 100 includes, along a conveyance passage, a receptacle sensor 111, a pick roller 112, a feed roller 113, a separation roller 114, a rotation sensor 115, a separation sensor 116, a pick sensor 117, a first skew sensor 118, a second skew sensor 119, first to sixth conveyance rollers 120a to 120f, first to sixth driven rollers 121a to 121f, a feed sensor 122, and an imaging device 123.

The pick roller 112, the feed roller 113, the separation roller 114, the first to sixth conveyance rollers 120a to 120f, and/or the first to sixth driven rollers 121a to 121f according to the present embodiment serve as rollers or conveyance rollers that convey media. The number of each of the pick roller 112, the feed roller 113, the separation roller 114, the first to sixth conveyance rollers 120a to 120f, and the first to sixth driven rollers 121a to 121f is not limited to one but may be two or more. When the number of each of the pick roller 112, the feed roller 113, the separation roller 114, the first to sixth conveyance rollers 120a to 120f, and the first to sixth driven rollers 121a to 121f is two or more, the feed rollers 113, the separation rollers 114, the first to sixth conveyance rollers 120a to 120f, and the first to sixth driven rollers 121a to 121f are separately aligned at intervals in the width direction A4 orthogonal to the media conveyance direction A2.

The second housing 102 faces the first housing 101 across a media conveyance passage through which media are conveyed. The first housing 101 has a face that faces the second housing 102. The face of the first housing 101 serves a first guide 101a of the media conveyance passage. The second housing 102 has a face that faces the first housing 101. The face of the second housing 102 serves a second guide 102a of the media conveyance passage. The first guide 101a and the second guide 102a define a so-called U-turn path.

The receptacle sensor 111 is disposed on the receptacle 103, that is, upstream from the feed roller 113 and the separation roller 114 in the media conveyance direction A2, to detect how the medium is placed on the receptacle 103. The receptacle sensor 111 determines whether a medium is placed on the receptacle 103, with a contact sensor that causes a predetermined current to flow when a medium is in contact with the contact sensor or when no medium is in contact with the contact sensor. The receptacle sensor 111 generates and outputs a receptacle signal whose signal value changes between when a medium is placed on the receptacle 103 and when no medium is placed on the receptacle 103. The receptacle sensor 111 is not limited to the contact sensor but may be any other sensor that can detect the presence of a medium such as an optical sensor.

The pick roller 112 is disposed upstream from the feed roller 113 and the separation roller 114 in the media conveyance direction A2 in the second housing 102. The pick roller 112 contacts the uppermost medium of the media placed on the receptacle 103 that has been raised to substantially the same height as the height of the media conveyance passage, and feeds (conveys) the medium downstream in the media conveyance direction A2.

The feed roller 113 is disposed downstream from the pick roller 112 in the media conveyance direction A2 in the second housing 102 to further feed (convey) the medium fed (conveyed) from the receptacle 103 by the pick roller 112 downstream in the media conveyance direction A2. When multiple feed rollers 113 are disposed, the feed rollers 113 are rotated independently from each other by separate motors. The feed rollers 113 according to the present embodiment serve as a first roller and a second roller. Alternatively, the feed rollers 113 may be rotated together by a common motor.

The separation roller 114 is disposed facing the feed roller 113 in the first housing 101. The separation roller 114 is a so-called brake roller or retard roller. The separation roller 114 is stoppable or rotatable in an opposite media-feeding direction A13, which is a direction opposite to a media feeding direction in which media are fed. The feed roller 113 and the separation roller 114 function as separators that perform a separation operation of media. Specifically, the feed roller 113 and the separation roller 114 separate the media to feed the media one by one. The feed roller 113 is disposed above the separation roller 114. The media conveying apparatus 100 adopts the method of feeding media from the top.

The media conveying apparatus 100 further includes a torque limiter, which is disposed between the separation roller 114 and a motor that applies a driving force to the separation roller 114. The torque limiter defines the limit value of the torque applied to the separation roller 114. The limit value of the torque limiter is set to prevent the rotational force from being transmitted through the torque limiter when a single medium is conveyed, and to transmit the rotational force through the torque limiter when multiple media are conveyed. Accordingly, when a single medium is conveyed, the separation roller 114 is rotated by the feed roller 113, without being rotated by the driving force from the motor. By contrast, when multiple media are conveyed, the separation roller 114 rotates in the opposite media-feeding direction A13 and separates the medium in contact with the feed roller 113 from the other media to prevent the occurrence of multiple feeding. At this time, alternatively, the outer circumferential surface of the separation roller 114 that is stopped without rotating in the opposite media-feeding direction A13 may apply a force in the opposite media-feeding direction A13 to the media.

The separation roller 114 is supported by the first housing 101 through an arm 114c. The arm 114c has an end to which the separation roller 114 is attached and another end attached to the first housing 101. The arm 114c is rotatable (swingable) relative to the first housing 101. A biasing member such as a spring or a rubber member applies a biasing force to the arm 114c upward, that is, in a direction in which the separation roller 114 moves toward the feed roller 113. The arm 114c applies, to the separation roller 114, a pressing force that presses the separation roller 114 toward the feed roller 113. In addition, a rotational force that rotates (swings) the arm 114c is applied to the arm 114c when the driving force is applied by the motor described later. The media conveying apparatus 100 rotates (swings) the arm 114c to adjust the pressing force with which the separation roller 114 presses the feed roller 113.

The rotation sensor 115 such as an encoder is disposed on a rotary shaft of the separation roller 114 to detect the rotation of the separation roller 114. The rotation sensor 115 includes a disk, a light emitter, and a light receiver. The disk has a large number of slits (light transmission holes) and rotates in accordance with the rotation of the separation roller 114. The light emitter and the light receiver face each other with the disk interposed therebetween. The light emitter is, for example, a light emitting diode (LED) and emits light toward the disk (the light receiver). The light receiver is, for example, a photodiode and receives, through the disk, the light emitted by the light emitter. The light receiver detects the number of changes within a predetermined period from a state where the slit is present between the light emitter and the light receiver to a state where the slit is absent between the light emitter and the light receiver and the light is blocked by the disk. The light receiver multiplies the detected number of changes by the distance traveled by the outer circumferential surface of the separation roller 114 while the disk rotates by the distance between the two adjacent slits. In this way, the light receiver detects, as movement distance, the distance traveled by the outer circumferential surface of the separation roller 114. A fixed slit is formed between the light emitter and the light receiver to convert the pulse signal into two phases. The light receiver detects the rotational direction of the disk, based on the rising timing of the pulse signal of each phase. The rotation sensor 115 generates and outputs a rotation signal indicating the detected movement distance and the rotational direction of the disk such as stop, forward direction, or reverse direction.

The rotation sensor 115 is not limited to an optical encoder but may be any encoder such as a mechanical encoder, a magnetic encoder, or an electromagnetic induction encoder.

The first to sixth conveyance rollers 120a to 120f and the first to sixth driven rollers 121a to 121f are disposed downstream from the pick roller 112, the feed roller 113, and the separation roller 114 in the media conveyance direction A2 such that the first to sixth conveyance rollers 120a to 120f face the first to sixth conveyance rollers 120a to 120f, respectively. The first to sixth conveyance rollers 120a to 120f and the first to sixth driven rollers 121a to 121f convey the medium, that has been fed by the feed roller 113 and the separation roller 114, downstream in the media conveyance direction A2 or the media ejection direction A3. The sixth conveyance roller 120f and the sixth driven roller 121f eject the medium to the output receptacle 104.

The imaging device 123 is disposed downstream from the first and second conveyance rollers 120a and 120b in the media conveyance direction A2 to image the medium conveyed by the first and second conveyance rollers 120a and 120b and the first and second driven rollers 121a and 121b. The imaging device 123 includes a first imaging device 123a and a second imaging device 123b facing each other across the media conveyance passage. The first imaging device 123a is disposed in the second housing 102, whereas the second imaging device 123b is disposed in the first housing 101.

The first imaging device 123a includes, as a line sensor, a contact image sensor (CIS) employing an equal-magnification optical system and including, as imaging elements, complementary metal oxide semiconductors (CMOSs) aligned linearly in the main-scanning direction. The first imaging device 123a further includes a lens that forms an image on the imaging elements and an analog-to-digital (A/D) converter. The A/D converter amplifies the electric signals output from the imaging elements and performs analog-to-digital (A/D) conversion. The first imaging device 123a images the front side of the medium being conveyed, generates an input image, and outputs the input image.

Similarly, the second imaging device 123b includes, as a line sensor, a CIS employing the equal-magnification optical system and including, as imaging elements, CMOSs aligned linearly in the main-scanning direction. The second imaging device 123b further includes a lens that forms an image on the imaging elements and an A/D converter. The A/D converter amplifies the electric signals output from the imaging elements and performs A/D conversion. The second imaging device 123b images the back side of the medium being conveyed, generates an input image, and outputs the input image.

Alternatively, the media conveying apparatus 100 may include either the first imaging device 123a or the second imaging device 123b to read only one side of the medium. The line sensor may be, instead of the CIS employing the equal-magnification optical system and including CMOSs as imaging elements, a CIS employing the equal-magnification optical system and including charge-coupled devices (CCDs) as imaging elements. Alternatively, a line sensor employing a reduction optical system and including, as imaging elements, CMOSs or CCDs may be used.

As the pick roller 112 and the feed roller 113 rotate in media feeding directions All and A12, respectively, the medium is conveyed from the receptacle 103 in the media conveyance direction A2 between the first guide 101a and the second guide 102a. The media conveying apparatus 100 has two feeding modes: a separation mode in which media are fed while being separated and a non-separation mode in which media are fed without being separated. The feeding mode is set by a user using the operation device 105 or an information processing device connected to the media conveying apparatus 100 for communication. When the feeding mode is set to the separation mode, the separation roller 114 stops or rotates in the direction indicated by arrow A13 opposite to the media feeding direction. This operation prevents the feeding of a medium other than the separated medium. In short, the multiple feeding is prevented. By contrast, when the feeding mode is set to the non-separation mode, the separation roller 114 rotates in the media feeding direction opposite to the direction indicated by arrow A13.

As the first and second conveyance rollers 120a and 120b rotate in the directions indicated by arrows A14 and A15, respectively, the medium is fed to the imaging position in the imaging device 123 while being guided by the first guide 101a and the second guide 102a. At the imaging portion, the imaging device 123 images the medium. As the third to sixth conveyance rollers 120c to 120f rotate in the directions indicated by arrows A16 to A19, respectively, the medium is ejected onto the output receptacle 104.

FIG. 3 is a schematic diagram illustrating sensors according to the present embodiment. Specifically, FIG. 3 is a top view (from where the second housing 102 is present) around a media conveyance port.

In the example illustrated in FIG. 3, the feed rollers 113 include a first feed roller 113a and a second feed roller 113b, whereas the separation rollers 114 include a first separation roller 114a and a second separation roller 114b. The first feed roller 113a and the first separation roller 114a are disposed to the left (left side in FIG. 3) of a center position in the width direction A4 when viewed in the direction opposite to the media conveyance direction A2. The second feed roller 113b and the second separation roller 114b are disposed to the right (right side in FIG. 3) of the center position in the width direction A4 when viewed in the direction opposite to the media conveyance direction A2. The first feed roller 113a and the second feed roller 113b according to the present embodiment serve as the first roller and the second roller, respectively.

The separation sensor 116 is disposed downstream from a nip N1 between the feed roller 113 and the separation roller 114 and upstream from a nip N2 between the first conveyance roller 120a and the first driven roller 121a in the media conveyance direction A2. In particular, the separation sensor 116 is disposed near the feed roller 113 and the separation roller 114. The separation sensor 116 is disposed upstream from the pick sensor 117, the first skew sensor 118, and the second skew sensor 119 in the media conveyance direction A2. The separation sensor 116 is disposed at the center, particularly between the first feed roller 113a and the second feed roller 113b (between the first separation roller 114a and the second separation roller 114b) in the width direction A4. The separation sensor 116 is disposed between the first skew sensor 118 and the second skew sensor 119 in the width direction A4.

The separation sensor 116 includes a light emitter, a light receiver, and a light guide tube. The light emitter and the light receiver are disposed on one side of the media conveyance passage. The light guide tube faces the light emitter and the light receiver across the media conveyance passage. The light emitter is, for example, an LED and emits light toward the media conveyance passage. By contrast, the light receiver is, for example, a photodiode and receives light that is emitted by the light emitter and guided by the light guide tube. Based on the intensity of the light received by the light receiver, the separation sensor 116 generates and outputs a separation signal whose signal value changes between when a medium is present at the position of the separation sensor 116 and when a medium is absent at the position of the separation sensor 116. Thus, the separation sensor 116 detects the medium conveyed to the position of the separation sensor 116.

The pick sensor 117 is disposed downstream from the nip N1 between the feed roller 113 and the separation roller 114 and upstream from the nip N2 between the first conveyance roller 120a and the first driven roller 121a in the media conveyance direction A2. In particular, the pick sensor 117 is disposed downstream from the separation sensor 116 and upstream from the first skew sensor 118 and the second skew sensor 119 in the media conveyance direction A2. Alternatively, the pick sensor 117 may be disposed in the same position as the first skew sensor 118 and the second skew sensor 119 in the media conveyance direction A2 or downstream from the first skew sensor 118 and the second skew sensor 119 in the media conveyance direction A2. The pick sensor 117 is disposed at the center, particularly between the first feed roller 113a and the second feed roller 113b (between the first separation roller 114a and the second separation roller 114b) in the width direction A4. The pick sensor 117 is disposed between the first skew sensor 118 and the second skew sensor 119 in the width direction A4.

The pick sensor 117 includes a light emitter, a light receiver, and a light guide tube. The light emitter and the light receiver are disposed on one side of the media conveyance passage. The light guide tube faces the light emitter and the light receiver across the media conveyance passage. The light emitter is, for example, an LED and emits light toward the media conveyance passage. By contrast, the light receiver is, for example, a photodiode and receives light that is emitted by the light emitter and guided by the light guide tube. Based on the intensity of the light received by the light receiver, the pick sensor 117 generates and outputs a pick signal whose signal value changes between when a medium is present at the position of the pick sensor 117 and when a medium is absent at the position of the pick sensor 117. Thus, the pick sensor 117 detects the medium conveyed to the position of the pick sensor 117.

The first skew sensor 118 and the second skew sensor 119 according to the present embodiment serve as a first sensor and a second sensor, respectively, or a plurality of sensors. The first skew sensor 118 and the second skew sensor 119 are disposed downstream from the nip N1 between the feed roller 113 and the separation roller 114 and upstream from the nip N2 between the first conveyance roller 120a and the first driven roller 121a in the media conveyance direction A2. In particular, the first skew sensor 118 and the second skew sensor 119 are disposed downstream from the separation sensor 116 and the pick sensor 117 in the media conveyance direction A2. Alternatively, the first skew sensor 118 and the second skew sensor 119 may be disposed in the same position as the pick sensor 117 in the media conveyance direction A2 or upstream from the pick sensor 117 in the media conveyance direction A2. The first skew sensor 118 and the second skew sensor 119 are aligned and spaced apart in the width direction A4 orthogonal to the media conveyance direction A2, in the same position when viewed in the width direction A4, that is, in the same position relative to each other in the media conveyance direction A2.

The first skew sensor 118 is disposed downstream from the first feed roller 113a in the media conveyance direction A2. The second skew sensor 119 is disposed downstream from the second feed roller 113b in the media conveyance direction A2. The first skew sensor 118 is disposed to the left (left side in FIG. 3) of the center position in the width direction A4 when viewed in the direction opposite to the media conveyance direction A2. In other words, the first skew sensor 118 is closer to the first feed roller 113a and the first separation roller 114a than to the second feed roller 113b and the second separation roller 114b. The second skew sensor 119 is disposed on the right (right side in FIG. 3) of the center position in the width direction A4 when viewed in the direction opposite to the media conveyance direction A2. In other words, the second skew sensor 119 is closer to the second feed roller 113b and the second separation roller 114b than to the first feed roller 113a and the first separation roller 114a.

The first skew sensor 118 includes a light emitter, a light receiver, and a light guide tube. The light emitter and the light receiver are disposed on one side of the media conveyance passage. The light guide tube faces the light emitter and the light receiver across the media conveyance passage. The light emitter is, for example, an LED and emits light toward the media conveyance passage. By contrast, the light receiver is, for example, a photodiode and receives light that is emitted by the light emitter and guided by the light guide tube. Based on the intensity of the light received by the light receiver, the first skew sensor 118 generates and outputs a first skew signal whose signal value changes between when a medium is present at the position of the first skew sensor 118 and when a medium is absent at the position of the first skew sensor 118. Thus, the first skew sensor 118 detects the medium conveyed to the position of the first skew sensor 118. The first skew signal according to the present embodiment serves as an output signal from the first skew sensor 118.

The second skew sensor 119 includes a light emitter, a light receiver, and a light guide tube. The light emitter and the light receiver are disposed on one side of the media conveyance passage. The light guide tube faces the light emitter and the light receiver across the media conveyance passage. The light emitter is, for example, an LED and emits light toward the media conveyance passage. By contrast, the light receiver is, for example, a photodiode and receives light that is emitted by the light emitter and guided by the light guide tube. Based on the intensity of the light received by the light receiver, the second skew sensor 119 generates and outputs a second skew signal whose signal value changes between when a medium is present at the position of the second skew sensor 119 and when a medium is absent at the position of the second skew sensor 119. Thus, the second skew sensor 119 detects the medium conveyed to the position of the second skew sensor 119. The second skew signal according to the present embodiment serves as an output signal from the second skew sensor 119.

When the first skew sensor 118 detects a medium before the second skew sensor 119 detects the medium, the media conveying apparatus 100 sets the circumferential speed of the first feed roller 113a to a first speed V1 and the circumferential speed of the second feed roller 113b to a second speed V2 higher than the first speed V1. Similarly, when the second skew sensor 119 detects a medium before the first skew sensor 118 detects the medium, the media conveying apparatus 100 sets the circumferential speed of the second feed roller 113b to the first speed V1 and the circumferential speed of the first feed roller 113a to the second speed V2. In this way, the media conveying apparatus 100 corrects the skew of the medium. The positions of the first skew sensor 118 and the second skew sensor 119 in the width direction A4 orthogonal to the media conveyance direction A2 are set to be the same as a rotational center position C of the medium that rotates at a speed ratio α of the second speed V2 to the first speed V1. The speed ratio α of the second speed V2 to the first speed V1 is set to a value larger than 1.

When the first skew sensor 118 detects a medium before the second skew sensor 119 detects the medium, the medium is conveyed faster at the side closer to the first skew sensor 118 than at the side closer to the second skew sensor 119. In this case, the circumferential speed of the first feed roller 113a is set to the first speed V1, whereas the circumferential speed of the second feed roller 113b is set to the second speed V2 (=α·V1). Following Formulas (1) and (2) are satisfied for a rotation angle θa at which the medium rotates in a predetermined period T at the rotational center position C:

tan θa=(V1·T)/L (1)

and

tan θa=(V2·T)/(L+D)=(α·V1·T)/(L+D), (2)

- where L represents the distance between the rotational center position C and the center position of the first feed roller 113a in the width direction A4 and D represents the distance between the center position of the first feed roller 113a and the center position of the second feed roller 113b in the width direction A4.

Following Formula (3) is satisfied based on Formulas (1) and (2).

L=D/(α−1) (3)

The first skew sensor 118 is disposed within a predetermined range from a position outside the first feed roller 113a in the width direction A4 orthogonal to the media conveyance direction A2 by the distance L calculated by Formula (3). The predetermined range is set to a range in consideration of, for example, manufacturing errors of the media conveying apparatus 100. Specifically, for example, the predetermined range is set to a range within 10 mm from the position. Similarly, the second skew sensor 119 is disposed within a predetermined range from a position outside the second feed roller 113b in the width direction A4 orthogonal to the media conveyance direction A2 by the distance L calculated by Formula (3). In this case, L represents the distance between the rotational center position C and the center position of the second feed roller 113b in the width direction A4.

As the speed ratio α increases, the time taken for the skew correction of the medium decreases. However, as the speed ratio α increases, the load on the medium during the skew correction increases. As indicated by Formula (3), as the speed ratio α increases, the distance L decreases. In other words, the size of the medium for which the media conveying apparatus 100 can detect a skew decreases. The speed ratio α is set in consideration of the time taken for the skew correction of the medium and the thickness (strength) and size of the medium supported by the media conveying apparatus 100.

Thus, when a leading end E1 of an obliquely conveyed medium passes the first skew sensor 118, the leading end E1 of the medium rotates about the rotational center position C with the speed ratio α of the second feed roller 113b to the first feed roller 113a.

Accordingly, the skew of the medium is corrected until another sensor such as the second skew sensor 119 arranged side by side with the first skew sensor 118 in the width direction A4 detects the leading end E1 of the medium. As a result, the skew of the medium is eliminated at the position of the first skew sensor 118. Similarly, when the leading end E1 of an obliquely conveyed medium passes the second skew sensor 119, the leading end E1 of the medium rotates about a position that is line-symmetrical to the rotational center position C with respect to the center position in the width direction A4, with the speed ratio α of the first feed roller 113a to the second feed roller 113b. Accordingly, the skew of the medium is corrected until another sensor such as the first skew sensor 118 arranged side by side with the second skew sensor 119 in the width direction A4 detects the leading end E1 of the medium. As a result, the skew of the medium is eliminated at the position of the second skew sensor 119.

Thus, the media conveying apparatus 100 corrects the skew of the medium easily and appropriately without adjusting the circumferential speeds of the feed rollers 113 based on the inclination of the medium. By eliminating the need for calculation of the inclination of the medium to correct the skew of the medium, the media conveying apparatus 100 reduces a processing load on the skew correction of the medium.

Alternatively, the first skew sensor 118 may be disposed within a predetermined range from a position outside the left or right end position of the nip N1 between the first feed roller 113a and the first separation roller 114a in the width direction A4 by the distance L calculated by Formula (3). In this case, L in Formula (3) represents the distance between the rotational center position C and the left or right end position of the nip N1 between the first feed roller 113a and the first separation roller 114a in the width direction A4. Similarly, the second skew sensor 119 may be disposed within a predetermined range from a position outside the left or right end position of the nip N1 between the second feed roller 113b and the second separation roller 114b in the width direction A4 by the distance L calculated by Formula (3). In this case, L in Formula (3) represents the distance between the rotational center position C and the left or right end position of the nip N1 between the second feed roller 113b and the second separation roller 114b in the width direction A4.

The media conveying apparatus 100 can start the skew correction of a medium with the feed rollers 113 when the first skew sensor 118 and the second skew sensor 119 detect the leading end of the medium that has passed the positions of the two feed rollers 113. To achieve this situation, the first skew sensor 118 and the second skew sensor 119 are disposed downstream from the center position of the first feed roller 113a and the center position of the second feed roller 113b, respectively, in the media conveyance direction A2 by a distance A that satisfies following In equation (4).

A≥(L+D)·tan θb, (4)

- where θb represents the maximum angle of inclination of the medium for which the media conveying apparatus 100 supports skew correction.

Thus, even when the medium is conveyed while being inclined at the maximum angle at which the skew correction is supported, the media conveying apparatus 100 corrects the skew of the medium easily and appropriately without adjusting the circumferential speeds of the feed rollers 113 based on the calculated inclination of the medium. Accordingly, the media conveying apparatus 100 appropriately corrects the skew of the medium while reducing the processing load on the skew correction of the medium.

Alternatively, each of the first skew sensor 118 and the second skew sensor 119 may be disposed downstream from the downstream or upstream end position of the nip N1 between the corresponding feed roller 113 and the corresponding separation roller 114 in the media conveyance direction A2 by the distance A that satisfies In equation (4) above.

The feed sensor 122 is disposed downstream from the nip N2 between the first conveyance roller 120a and the first driven roller 121a and upstream from a nip N3 between the second conveyance roller 120b and the second driven roller 121b in the media conveyance direction A2. Alternatively, the feed sensor 122 may be disposed downstream from the second conveyance roller 120b and the second driven roller 121b and upstream from the imaging device 123 in the media conveyance direction A2. The feed sensor 122 is disposed at the center, particularly, between the first feed roller 113a and the second feed roller 113b (between the first separation roller 114a and the second separation roller 114b) in the width direction A4. The feed sensor 122 is disposed between the first skew sensor 118 and the second skew sensor 119 in the width direction A4.

The feed sensor 122 includes a light emitter, a light receiver, and a light guide tube. The light emitter and the light receiver are disposed on one side of the media conveyance passage. The light guide tube faces the light emitter and the light receiver across the media conveyance passage. The light emitter is, for example, an LED and emits light toward the media conveyance passage. By contrast, the light receiver is, for example, a photodiode and receives light that is emitted by the light emitter and guided by the light guide tube. Based on the intensity of the light received by the light receiver, the feed sensor 122 generates and outputs a feed signal whose signal value changes between when a medium is present at the position of the feed sensor 122 and when a medium is absent at the position of the feed sensor 122. Thus, the feed sensor 122 detects the medium conveyed to the position of the feed sensor 122.

In the separation sensor 116, the pick sensor 117, the first skew sensor 118, the second skew sensor 119, and/or the feed sensor 122, a reflector such as a mirror may be used instead of the light guide tube. In each of the aforementioned sensors, the light emitter and the light receiver may face each other across the media conveyance passage. Each of the aforementioned sensors may detect the presence of the medium with a contact sensor that causes a predetermined current to flow when a medium is in contact with the contact sensor or when no medium is in contact with the contact sensor.

FIG. 4 is a schematic diagram illustrating the pick roller 112 and surrounding components in the media conveying apparatus 100 according to the present embodiment.

As illustrated in FIG. 4, the media conveying apparatus 100 includes an arm 131 supporting the pick roller 112. The arm 131 extends in the media conveyance direction A2 and is rotatable (swingable) about a downstream end 131a in the second housing 102. The pick roller 112 is attached to an upstream end 131b of the arm 131. A biasing member 131c is attached to the upper portion of the arm 131. The biasing member 131c is, for example, a spring such as a torsion coil spring or a rubber member. The biasing member 131c applies a biasing force to the arm 131 to direct the arm 131 downward. When the biasing member 131c is omitted, the weight of the arm 131 may direct the arm 131 downward. The arm 131 biased downward allows the pick roller 112 to appropriately convey a medium while pressing down the medium placed on the receptacle 103.

Further, a rotational force that swings (rotates) the arm 131 upward is applied to the arm 131 when the driving force is applied by the motor. The media conveying apparatus 100 rotates (swings) the arm 131 to move the pick roller 112 between a first position at which the pick roller 112 contacts the medium placed on the receptacle 103 and a second position at which the pick roller 112 is separated from the medium placed on the receptacle 103. In this way, the pick roller 112 is movable between the first position and the second position. FIG. 5 is a schematic block diagram illustrating a configuration of the media conveying apparatus 100 according to the present embodiment.

The media conveying apparatus 100 further includes, for example, a motor 141, an interface device 142, a storage device 150, and a processing circuit 160, in addition to the configuration described above.

The motor 141 includes one or more motors. The motor 141 generates driving forces for rotating the pick roller 112, the feed roller 113, the separation roller 114, and the first to sixth conveyance rollers 120a to 120f in response to control signals from the processing circuit 160 to feed and convey media. When the multiple feed rollers 113 are disposed, each of the feed rollers 113 is provided with a separate motor so that the feed rollers 113 are rotated independently from each other. Alternatively, the feed rollers 113 may be rotated together by a common motor. The first to sixth driven rollers 121a to 121f may be rotated by the driving force from the motor 141, instead of rotating in accordance with the rotation of the first to sixth conveyance rollers 120a to 120f.

Each motor included in the motor 141 moves the receptacle 103, moves the pick roller 112, or swings the separation roller 114, in response to a control signal from the processing circuit 160. The arm 131 supporting the pick roller 112, the biasing member 131c, and/or the motor for moving the pick roller 112 according to the present embodiment serves as a moving mechanism for moving the pick roller 112. The arm 114c supporting the separation roller 114 and/or the motor for swinging the arm 114c according to the present embodiment serves as an applying mechanism for applying, to the separation roller 114, the pressing force that presses the separation roller 114 toward the feed roller 113.

The interface device 142 includes an interface circuit in compliance with a serial bus such as a universal serial bus (USB) and is electrically connected to an information processing device (for example, a personal computer or a mobile information processing terminal) to transmit and receive an input image and various kinds of information to and from the information processing device. The interface device 142 may be substituted by a communication unit including an antenna to transmit and receive radio signals and a wireless communication interface circuit to transmit and receive the signals through a wireless communication line according to a predetermined communication protocol. The predetermined communication protocol is, for example, a wireless local area network (LAN) communication protocol. The communication unit may include a wired communication interface circuit to transmit and receive signals through a wired communication line according to, for example, a wired LAN communication protocol.

The storage device 150 includes memories such as a random-access memory (RAM) and a read-only memory (ROM); a fixed disk device such as a hard disk; or a portable memory such as a flexible disk or an optical disk. The storage device 150 stores, for example, computer programs, databases, and tables used for various processes performed by the media conveying apparatus 100. The computer programs may be installed in the storage device 150 from a computer-readable portable recording medium using, for example, a known setup program. The portable recording medium is, for example, a compact disc read-only memory (CD-ROM) or a digital versatile disc read-only memory (DVD-ROM). The storage device 150 stores, as data, state information indicating the state of skew correction of a medium.

The processing circuit 160 operates according to a program stored in the storage device 150 in advance. The processing circuit 160 is, for example, a central processing unit (CPU). Alternatively, as the processing circuit 160, for example, a digital signal processor (DSP), a large scale integration (LSI), an application-specific integrated circuit (ASIC), or a field-programmable gate array (FPGA) may be used.

The processing circuit 160 is connected to, for example, the operation device 105, the display device 106, the receptacle sensor 111, the rotation sensor 115, the separation sensor 116, the pick sensor 117, the first skew sensor 118, the second skew sensor 119, the feed sensor 122, the imaging device 123, the motor 141, the interface device 142, and the storage device 150, and controls these components. The processing circuit 160 controls, for example, the driving of the motor 141 and the imaging by the imaging device 123, according to the signals received from the sensors described above. The processing circuit 160 acquires an input image from the imaging device 123 and transmits the input image to the information processing device via the interface device 142.

FIG. 6 is a schematic block diagram illustrating a configuration of the storage device 150 and the processing circuit 160 according to the present embodiment.

As illustrated in FIG. 6, the storage device 150 stores, for example, a reception program 151, a control program 152, an acquisition program 153, and a determination program 154. These programs are functional modules implemented by software operating on the processor. The processing circuit 160 reads the programs from the storage device 150 and operates according to the read programs. Thus, the processing circuit 160 functions as a reception unit 161, a control unit 162, an acquisition unit 163, and a determination unit 164. FIG. 7 is a flowchart of a medium reading process performed by the media conveying apparatus 100 according to the present embodiment.

A description is given below of the medium reading process performed by the media conveying apparatus 100, with reference to the flowchart of FIG. 7. The operation process described below is executed, for example, by the processing circuit 160 in cooperation with the components of the media conveying apparatus 100 based on the program prestored in the storage device 150. A description is given below of a case where the feeding mode is set to the separation mode, with reference to the flowchart of FIG. 7.

In step S101, the reception unit 161 determines whether the setting on the media conveying apparatus 100 is input by a user through the operation device 105 or the information processing device and the setting on the media conveying apparatus 100 is received from the user. Specifically, in response to a setting signal instructing the setting on the media conveying apparatus 100 from the operation device 105 or from the information processing device via the interface device 142, the reception unit 161 determines that the setting on the media conveying apparatus 100 is received from the user. The setting on the media conveying apparatus 100 includes the setting related to the circumferential speeds of the feed rollers 113 for correction of the skew of the medium. Examples of the setting related to the circumferential speeds of the feed rollers 113 include, but are not limited to, the circumferential speeds of the feed rollers 113, the number of rotations per minute (RPM) of each of the feed rollers 113, and the number of rotations per minute (RPM) of the motor that drives the feed rollers 113. The setting related to the circumferential speeds of the feed rollers 113 may be, for example, a ratio or difference with respect to a reference (initial) circumferential speed of the feed rollers 113. The setting on the media conveying apparatus 100 may include the setting as to whether to execute the skew correction of a medium.

The media conveying apparatus 100 corrects the skew of a medium by rotating each of the feed rollers 113 at a speed suitable for the thickness or material of the medium to be conveyed, based on the setting received from the user, that is, the setting related to the circumferential speeds of the feed rollers 113 for correction of the skew of the medium. In short, the media conveying apparatus 100 corrects the skew of the medium as appropriate for various types of media. When the reception unit 161 receives no setting on the media conveying apparatus 100 (NO in step S101), the reception unit 161 proceeds to step S103.

By contrast, when the reception unit 161 receives the setting on the media conveying apparatus 100 (YES in step S101), in step S102, the reception unit 161 stores the received setting in the storage device 150.

In step S103, the control unit 162 determines whether an instruction to read a medium is input by a user through the operation device 105 or the information processing device and the instruction to read a medium is received from the user. Specifically, in response to the operation signal instructing the reading of a medium from the operation device 105 or from the information processing apparatus via the interface device 142, the control unit 162 determines that the instruction to read a medium is received from the user. When the control unit 162 receives no instruction to read a medium (NO in step S103), the control unit 162 returns to step S101.

By contrast, when the control unit 162 receives the instruction to read a medium (YES in step S103), in step S104, the control unit 162 acquires the receptacle signal from the receptacle sensor 111 and determines whether a medium is placed on the receptacle 103, based on the acquired receptacle signal. When no medium is placed on the receptacle 103 (NO in step S104), the control unit 162 returns to step S101.

By contrast, when a medium is placed on the receptacle 103 (YES in step S104), the control unit 162 drives the motor 141 to move the receptacle 103 to the position where the medium can be fed and move the pick roller 112 to the first position. In step S105, the control unit 162 drives the motor 141 to rotate the pick roller 112, the feed roller 113, the separation roller 114, and/or the first to sixth conveyance rollers 120a to 120f, to feed and convey the medium from the receptacle 103. At this time, the control unit 162 sets the circumferential speed of the first feed roller 113a and the circumferential speed of the second feed roller 113b to the same reference speed. The control unit 162 also controls the motor 141 so that the pressing force that presses the separation roller 114 toward the feed roller 113 becomes a reference value (initial value).

In step S106, the control unit 162 sets (initializes) the state information indicating the state of skew correction of a medium to a not-started state indicating that the skew correction of the medium has not been started.

In step S107, the acquisition unit 163 waits until the leading end of the medium passes the position of the pick sensor 117. The acquisition unit 163 periodically acquires the pick signal from the pick sensor 117. When the signal value of the pick signal changes from a value indicating that a medium is absent to a value indicating that a medium is present, the acquisition unit 163 determines that the leading end of the medium has passed the position of the pick sensor 117 and the pick sensor 117 has detected the leading end of the medium.

In step S108, the acquisition unit 163 calculates the degree of slip between the feed rollers 113 (i.e., the first feed roller 113a and the second feed roller 113b) and the medium fed (conveyed) by the feed rollers 113 (i.e., the first feed roller 113a and the second feed roller 113b). The degree of slip indicates the degree to which the medium slips on the outer circumferential surface of the feed roller 113 and the medium does not move despite the rotation of the feed roller 113. The acquisition unit 163 calculates the degree of slip, based on the driving amount of the motor 141 and the distance traveled by the medium fed (conveyed) by the feed roller 113.

The acquisition unit 163 periodically acquires the separation signal from the separation sensor 116 after the feeding of the medium is started. When the signal value of the separation signal changes from a value indicating that a medium is absent to a value indicating that a medium is present, the acquisition unit 163 determines that the leading end of the medium has passed the position of the separation sensor 116 and the separation sensor 116 has detected the leading end of the medium. The acquisition unit 163 monitors the driving amount of the motor 141 driven for rotating the feed roller 113 during a period from when the leading end of the medium passes the position of the separation sensor 116 to when the leading end of the medium passes the position of the pick sensor 117. The acquisition unit 163 multiplies the driving amount (the number of pulses) of the motor 141 in the above period by the distance traveled by the outer circumferential surface of the feed roller 113 per pulse. In this way, the acquisition unit 163 calculates the distance traveled by the outer circumferential surface of the feed roller 113. The acquisition unit 163 specifies the distance between the separation sensor 116 and the pick sensor 117 in the media conveyance direction A2 as the distance traveled by the medium fed during the above period.

The acquisition unit 163 calculates the degree of slip according to the following Formula (5), based on the distance traveled by the outer circumferential surface of the feed roller 113 and the distance traveled by the medium fed. The acquisition unit 163 then stores the calculated degree of slip in the storage device 150.

( degree of slip)=1−(distance traveled by the medium fed)/(distance traveled by the outer circumferential surface of the feed rollers 113) (5)

In step S109, the control unit 162 waits until the trailing end of the media passes the imaging position in the imaging device 123. The control unit 162 periodically acquires the feed signal from the feed sensor 122. When the signal value of the feed signal changes from a value indicating that a medium is present to a value indicating that a medium is absent, the control unit 162 determines that the trailing end of the medium has passed the position of the feed sensor 122 and the feed sensor 122 has detected the trailing end of the medium. The control unit 162 determines that the trailing end of the medium has passed the imaging position in the imaging device 123 when a first time has elapsed after the trailing end of the medium passes the position of the feed sensor 122. The first time is set to the time taken for a medium to move from the position of the feed sensor 122 to the imaging position in the imaging device 123.

In step S110, the control unit 162 acquires an input image from the imaging device 123 and transmits (i.e., outputs) the acquired input image to the information processing device via the interface device 142. The control unit 162 causes the imaging device 123 to start imaging before the leading end of the medium reaches the imaging position in the imaging device 123, for example, at the time when the leading end of the medium passes the position of the feed sensor 122. The control unit 162 causes the imaging device 123 to finish imaging after the trailing end of the medium passes the imaging position in the imaging device 123, for example, at the time when the first time has elapsed after the detection of the trailing end of the medium by the feed sensor 122. The control unit 162 then acquires the input image from the imaging device 123.

In step S111, the control unit 162 determines whether a medium remains on the receptacle 103, based on the receptacle signal received from the receptacle sensor 111. When a medium remains on the receptacle 103 (YES in step S111), the control unit 162 returns to step S106 and repeats the operations from step S106 onward.

By contrast, when no medium remains on the receptacle 103 (NO in step S111), in step S112, the control unit 162 controls the motor 141 to stop the pick roller 112, the feed roller 113, the separation roller 114, and/or the first to sixth conveyance rollers 120a to 120f. Thus, the series of steps ends.

FIG. 8 is a flowchart of a skew determination process performed by the media conveying apparatus 100 according to the present embodiment. FIGS. 9 and 10 are continuations of the flowchart of FIG. 8.

A description is given below of the skew determination process performed by the media conveying apparatus 100, with reference to the flowchart of FIGS. 8, 9, and 10. The operation process described below is executed, for example, by the processing circuit 160 in cooperation with the components of the media conveying apparatus 100 based on the program prestored in the storage device 150. The operation process illustrated in FIGS. 8, 9, and 10 is executed during conveyance of a medium. The skew determination process may be executed only when the setting received by the reception unit 161 in step S101 of FIG. 7 indicates that the skew correction of a medium is to be executed.

In step S201, the determination unit 164 receives the rotation signal, the separation signal, the pick signal, the first skew signal, and the second skew signal from the rotation sensor 115, the separation sensor 116, the pick sensor 117, the first skew sensor 118, and the second skew sensor 119, respectively. The determination unit 164 stores the received signals in the storage device 150.

In step S202, the determination unit 164 determines whether a skew condition is satisfied. The determination unit 164 determines whether the leading end of the medium has reached the position of each of the first skew sensor 118 and the second skew sensor 119. When the signal value of the first skew signal changes from a value indicating that a medium is absent to a value indicating that a medium is present, the determination unit 164 determines that the leading end of the medium has reached the position of the first skew sensor 118 and the first skew sensor 118 has detected the leading end of the medium. When the signal value of the second skew signal changes from a value indicating that a medium is absent to a value indicating that a medium is present, the determination unit 164 determines that the leading end of the medium has reached the position of the second skew sensor 119 and the second skew sensor 119 has detected the leading end of the medium.

The determination unit 164 determines that the skew condition is satisfied when the leading end of the medium does not reach one of the position of the first skew sensor 118 and the position of the second skew sensor 119 within a second time after the leading end of the medium reaches the other one of the position of the first skew sensor 118 and the position of the second skew sensor 119. In other words, the determination unit 164 determines that the skew condition is satisfied when one of the first skew sensor 118 and the second skew sensor 119 does not detect the leading end of the medium within the second time after the other one of the first skew sensor 118 and the second skew sensor 119 detects the leading end of the medium. The second time is set to, for example, a mean value, a median value, a minimum value, or a maximum value of a difference between times at which the medium passes the skew sensors when the medium is jammed or when a lack of the medium occurs in the input image in preliminary experiments in which media are conveyed in an inclined position. When the skew condition is not satisfied (NO in step S202), in step S203, the determination unit 164 determines that the medium is not skewed and proceeds to step S212.

By contrast, when the skew condition is satisfied (YES in step S202), in step S204, the determination unit 164 determines that the medium is skewed. In this way, the determination unit 164 determines whether the medium is skewed, based on the first skew signal output from the first skew sensor 118 and the second skew signal output from the second skew sensor 119. In other words, the determination unit 164 determines whether the medium is skewed, based on the result of detection of the medium by the first skew sensor 118 or the second skew sensor 119. In particular, the determination unit 164 determines whether the medium is skewed, based on the time when each of the first skew sensor 118 and the second skew sensor 119 detects the leading end of the medium.

In step S205, the acquisition unit 163 acquires the degree of slip. Specifically, the acquisition unit 163 reads, from the storage device 150, the degree of slip calculated in step S108 of FIG. 7 for the medium conveyed immediately before. In this way, the acquisition unit 163 to acquire the degree of slip. In other words, the acquisition unit 163 calculates the degree of slip of the medium conveyed immediately before to acquire the degree of slip. The degree of slip may not be calculated yet for the medium currently conveyed. The acquisition unit 163 reads the degree of slip of the medium conveyed immediately before to reliably acquire the latest degree of slip as desired.

Alternatively, the acquisition unit 163 may calculate a statistical value (a mean value, a median value, a maximum value, or a minimum value) of the degrees of slip calculated most recently for a predetermined number of media, to acquire the degree of slip. Thus, the acquisition unit 163 calculates the degree of slip with an enhanced accuracy. Alternatively, the acquisition unit 163 may read, from the storage device 150, the degree of slip calculated in step S108 of FIG. 7 for the medium currently conveyed, to acquire the degree of slip. Thus, the acquisition unit 163 acquires the degree of slip corresponding to the material of the medium currently conveyed. Alternatively, the media conveying apparatus 100 may calculate the degree of slip in an unused product and store the degree of slip in the storage device 150 in advance. In this case, the operation in step S108 in FIG. 7 is omitted. The acquisition unit 163 reads the degree of slip stored in advance in the storage device 150, to acquire the degree of slip. Thus, the acquisition unit 163 acquires the degree of slip at a decreased load.

When the medium is skewed, in step S206, the control unit 162 determines whether a condition for prohibiting the skew correction (i.e., prohibition condition) is satisfied. When the condition for prohibiting the skew correction is satisfied (YES in step S206), the control unit 162 prohibits the skew correction of the medium and does not correct the skew of the medium in a step described later.

For example, when the pick sensor 117 detects the leading end of the medium before the first skew sensor 118 and the second skew sensor 119 detect the leading end of the medium, the control unit 162 determines that the condition for prohibiting the skew correction is satisfied and does not correct the skew of the medium.

FIG. 11A is a schematic diagram illustrating a medium M1 detected by the pick sensor 117 before being detected by the first skew sensor 118 and the second skew sensor 119.

In the example illustrated in FIG. 11A, the medium M1 is conveyed in a slightly inclined position and is detected by the pick sensor 117 before being detected by the first skew sensor 118 and the second skew sensor 119. In this case, when the medium M1 continues to be conveyed in the inclined position, the medium M1 may be imaged as appropriate by the imaging device 123 and may not collide with the sidewall of the conveyance passage. The media conveying apparatus 100 does not correct the skew of the medium when the pick sensor 117 detects the medium before the first skew sensor 118 and the second skew sensor 119 detect the medium, to prevent an increase in the total time for conveying the medium and an increase in the processing time for the medium reading process. In addition, the media conveying apparatus 100 determines whether to prohibit the skew correction at a decreased load, based on the time when each of the first skew sensor 118, the second skew sensor 119, and the pick sensor 117 detects the medium.

Alternatively, when the pick sensor 117 detects the leading end of a medium before an elapse of a third time from the detection of the leading end of the medium by the first skew sensor 118 and the second skew sensor 119, the control unit 162 may determine that the condition for prohibiting the skew correction is satisfied. The third time is set to a sufficiently short time (for example, 1 second). In this case, the inclination of the medium may be sufficiently small. The control unit 162 does not correct the skew of the medium to prevent an increase in the total time for conveying the medium and an increase in the processing time for the medium reading process.

When the first skew sensor 118 or the second skew sensor 119 detects the leading end of the medium before the separation sensor 116 detects the leading end of the medium, the control unit 162 determines that the condition for prohibiting the skew correction is satisfied and does not correct the skew of the medium.

FIG. 11B is a schematic diagram illustrating a medium M2 detected by the first skew sensor 118 and the second skew sensor 119 before being detected by the separation sensor 116.

In the example illustrated in FIG. 11B, the medium M2 and a medium M3 are placed on the receptacle 103 without aligning the leading ends of the medium M2 and the medium M3. As illustrated in FIG. 11B, the left part of the leading end of the medium M2 that is to be fed after the medium M3 proceeds downstream from the feed roller 113 in the media conveyance direction A2 and is detected by the first skew sensor 118. In this way, the medium that is detected by the first skew sensor 118 or the second skew sensor 119 before being detected by the separation sensor 116 may not be the medium to be fed but may be the medium placed in an inclined position on the receptacle 103. The medium that is not to be fed is then pushed back to the receptacle 103 by the separation roller 114. When the skew correction is tried under this condition, the medium M3 to be fed may rotate in an erroneous direction. When the first skew sensor 118 or the second skew sensor 119 detects the leading end of the medium before the separation sensor 116 detects the leading end of the medium, the media conveying apparatus 100 does not correct the skew of the medium to prevent the medium to be fed from rotating in an erroneous direction.

FIG. 12A is a schematic diagram illustrating a medium M4 that is inclined to some extent.

In the example illustrated in FIG. 12A, the inclined medium M4 is detected by the separation sensor 116, the first skew sensor 118, and the pick sensor 117 in this order. In this case, the media conveying apparatus 100 corrects the skew of the medium to prevent the entire medium from not being imaged by the imaging device 123 and the medium from colliding with the sidewall of the conveyance passage.

Alternatively, the control unit 162 may determine whether the condition for prohibiting the skew correction is satisfied based on the degree of slip acquired in step S205 of FIG. 8. When the degree of slip exceeds an upper limit threshold, the control unit 162 determines that the condition for prohibiting the skew correction is satisfied. By contrast, when the degree of slip is equal to or less than the upper limit threshold, the control unit 162 determines that the condition for prohibiting the skew correction is not satisfied. The upper limit threshold is set to a value between the degree of slip calculated when the skew of the medium is favorably corrected and the degree of slip calculated when the skew of the medium fails to be corrected as appropriate in preliminary experiments in which media are conveyed with the feed rollers 113 in various states.

In this way, the control unit 162 prohibits the skew correction of the medium, based on the degree of slip. Accordingly, the media conveying apparatus 100 prevents the load on the medium due to an inappropriate skew correction or prevents an increase in the processing time for the medium reading process.

Alternatively, when a past skew correction of a medium is insufficient, the control unit 162 may determine that the condition for prohibiting the skew correction is satisfied and prohibit the skew correction of media to be conveyed thereafter. In a step described later, the control unit 162 determines whether the skew correction of the medium is insufficient. For example, when one of the first skew sensor 118 and the second skew sensor 119 detects the leading end of the medium prior to the other one and then detects the trailing end of the medium before the separation sensor 116 detects the trailing end of the medium, the control unit 162 determines that the correction is insufficient.

FIG. 12B is a schematic diagram illustrating a medium after insufficient skew correction.

Specifically, FIG. 12B illustrates the medium M4 of FIG. 12A after being subjected to a skew correction. In the example illustrated in FIG. 12B, the skew of medium M4 is not eliminated. The trailing end of medium M4 is detected by first skew sensor 118 before being detected by the separation sensor 116. In this case, the skew of the medium M4 has failed to be corrected as appropriate for some reason. The skew of media to be conveyed thereafter may fail to be corrected as appropriate.

Alternatively, when a past skew correction of a medium is excessive, the control unit 162 may determine that the condition for prohibiting the skew correction is satisfied and prohibit the skew correction of media that are to be conveyed thereafter. In a step described later, the control unit 162 determines whether the skew correction of the medium is excessive. For example, when the order in which the first skew sensor 118 and the second skew sensor 119 detect the trailing end of the medium is changed from the order in which the first skew sensor 118 and the second skew sensor 119 detect the leading end of the medium, the control unit 162 determines that the correction is excessive.

FIG. 13 is a schematic diagram illustrating a medium after excessive skew correction.

Specifically, FIG. 13B illustrates the medium M4 of FIG. 12A after being subjected to a skew correction. In the example illustrated in FIG. 13, the direction in which the medium M4 is inclined is opposite to the direction in which the medium M4 is inclined before the correction illustrated in FIG. 12A. The trailing end of medium M4 is detected by the second skew sensor 119 before being detected by the first skew sensor 118. In this case, the skew of the medium M4 has failed to be corrected as appropriate for some reason. The skew of media to be conveyed thereafter may fail to be corrected as appropriate.

In this way, the control unit 162 prohibits the skew correction of media to be conveyed thereafter, based on the time when each of the first skew sensor 118 and the second skew sensor 119 detects the trailing end of the medium subjected to the skew correction. Accordingly, the media conveying apparatus 100 prevents the load on the medium due to an inappropriate skew correction or prevents an increase in the processing time for the medium reading process.

When the control unit 162 determines that the correction is insufficient or excessive and stops the skew correction of the medium, the control unit 162 may determine that the condition for prohibiting the skew correction is satisfied until the conveyance of all the media placed on the receptacle 103 is completed and may not restart the skew correction of the medium. Since all the media placed on the receptacle 103 may be placed collectively, all the media may be placed while being inclined in the same direction. When a large number of media are placed while being inclined in the same direction, the large number of media may enter the nip between one of the feed rollers 113 and the corresponding separation roller 114, resulting in a difference in separation force (back load) between the two pairs of the feed roller 113 and the separation roller 114. In this case, correcting the skew of the medium may increase the inclination of the medium. When the correction is insufficient or excessive, the media conveying apparatus 100 by prohibits the skew correction until the conveyance of all the media placed on the receptacle 103 is completed, to prevent an increase in the inclination of the medium.

Alternatively, when the control unit 162 determines that the correction is insufficient or excessive and stops the skew correction of the medium, the control unit 162 may not restart the skew correction of the medium until the rotation sensor 115 detects the separation roller 114 rotating in accordance with the rotation of the feed roller 113. When the separation roller 114 rotates in accordance with the feed roller 113, multiple media are absent at the nip between the feed roller 113 and the separation roller 114 and the entry of a large number of media into the nip may have been eliminated. When the correction is insufficient or excessive, the media conveying apparatus 100 prohibits the skew correction until the separation roller 114 rotates in accordance with the feed rollers 113, to prevent an increase in the inclination of the medium and appropriately correct the inclination of the medium in a correctable state.

Referring back to FIG. 8, when the condition for prohibiting the skew correction is satisfied (YES in step S206), in step S207, the control unit 162 prohibits the skew correction of the medium and does not correct the skew of the medium. The control unit 162 then proceeds to step S212.

By contrast, when the condition for prohibiting the skew correction is not satisfied (NO in step S206), in step S208, the control unit 162 determines whether the skew correction of the medium has been started. When the state information is set to the not-started state, the control unit 162 determines that the skew correction of the medium has not been started yet. By contrast, when the state information is set to a state other than the not-started state, the control unit 162 determines that the skew correction of the medium has been started. When the skew correction of the medium has already been started (YES in step S208), the control unit 162 proceeds to step S212.

By contrast, when the skew correction of the medium has not been started yet (NO in step S208), in step S209, the control unit 162 controls the motor 141 to increase the pressing force that presses the separation roller 114 toward the feed roller 113 from the reference value. In this way, the control unit 162 controls the motor 141 and the arm 114c supporting the separation roller 114 to generate different pressing forces between when the skew of the medium is corrected and when the skew of the medium is not corrected. Thus, the media conveying apparatus 100 increases the frictional force generated between the fed medium and the pair of the feed roller 113 and the separation roller 114 to correct the skew of the medium more favorably.

In step S210, the control unit 162 controls the motor 141 to move the pick roller 112 from the first position to the second position. Specifically, when the medium is skewed, the control unit 162 controls the arm 131 supporting the pick roller 112, the biasing member 131c, and the motor 141 to move the pick roller 112 from the first position to the second position. In this case, the pick roller 112 is separated from the medium and does not hinder the movement of the medium in the width direction A4. Accordingly, the media conveying apparatus 100 corrects the skew of the medium more favorably.

In step S211, the control unit 162 sets the state information to a start standby state indicating standby until the skew correction of the medium can be started.

In step S212, the control unit 162 determines whether a condition for starting the skew correction (i.e., start condition) is satisfied. When the condition for starting the skew correction is satisfied, the control unit 162 starts the skew correction of the medium in a step described later.

The control unit 162 determines that the condition for starting the skew correction is satisfied when a fourth time has elapsed after the setting of the state information to the start standby state. In other words, the control unit 162 determines that the condition for starting the skew correction is satisfied when the fourth time has elapsed after the start of control of the motor 141 to increase the pressing force that presses the separation roller 114 toward the feed roller 113. The control unit 162 determines that the condition for starting the skew correction is satisfied when the fourth time has elapsed after the start of control of the moving mechanism to move the pick roller 112 to the second position. The fourth time is one example of a predetermined time as a first predetermined time. The fourth time is set to the time taken from when the control of the motor 141 is started to when the pressing force of the separation roller 114 is changed or to when the pick roller 112 is moved to the second position in actual. By contrast, when the state information is set to a state other than the start standby state or when the fourth time has not elapsed after the setting of the state information to the start standby state, the control unit 162 determines that the condition for starting the skew correction is not satisfied.

In this way, the control unit 162 starts the skew correction of the medium after an elapse of the fourth time from the start of control of the motor 141 to increase the pressing force that presses the separation roller 114 toward the feed roller 113. As a result, the media conveying apparatus 100 corrects the skew of the medium while reliably increasing the pressing force that presses the separation roller 114 toward the feed roller 113. Thus, the media conveying apparatus 100 prevents the slip of the medium and corrects the skew of the medium more favorably. The control unit 162 starts the skew correction of the medium after an elapse of the fourth time from the start of control of the moving mechanism to move the pick roller 112 from the first position to the second position. As a result, the media conveying apparatus 100 corrects the skew of the medium while reliably separating the pick roller 112 from the medium. Thus, the media conveying apparatus 100 prevents the movement of the medium in the width direction A4 from being hindered by the pick roller 112 and corrects the skew of the media more favorably.

When the condition for starting the skew correction is not satisfied (NO in step S212), the control unit 162 proceeds to step S218.

By contrast, when the condition for starting the skew correction is satisfied (YES in step S212), in step S213, the control unit 162 sets the circumferential speed of the feed roller 113. When the first skew sensor 118 detects the medium before the second skew sensor 119 detects the medium, the control unit 162 sets the circumferential speed of the first feed roller 113a to the first speed V1 and the circumferential speed of the second feed roller 113b to the second speed V2 higher than the first speed V1. By contrast, when the second skew sensor 119 detects the medium before the first skew sensor 118 detects the medium, the control unit 162 sets the circumferential speed of the second feed roller 113b to the first speed V1 and the circumferential speed of the first feed roller 113a to the second speed V2. The control unit 162 sets the circumferential speeds of the feed rollers 113 to achieve the speed ratio α of the second speed V2 to the first speed VI expressed in Formula (3) above.

When the reception unit 161 has received the setting related to the circumferential speeds of the feed rollers 113 in step S102 of FIG. 7, the control unit 162 sets the circumferential speeds of the feed rollers 113 to the first speed V1 and the second speed V2, based on the received setting. By contrast, when the reception unit 161 has not received the setting related to the circumferential speeds of the feed rollers 113, the control unit 162 sets the circumferential speeds of the feed rollers 113 to a predetermined first speed VI and a predetermined second speed V2.

In step S214, the control unit 162 determines whether a condition for correcting the circumferential speeds of the feed rollers 113 (i.e., correction condition) is satisfied. When the condition for correcting the circumferential speeds of the feed rollers 113 is satisfied, the control unit 162 corrects the circumferential speeds of the feed rollers 113 in a step described later.

For example, the control unit 162 determines whether the correction condition is satisfied, based on the degree of slip acquired in step S205. When the degree of slip is greater than a slip threshold, the control unit 162 determines that the correction condition is satisfied. By contrast, when the degree of slip is equal to or less than the slip threshold, the control unit 162 determines that the correction condition is not satisfied. The slip threshold is set in advance to, for example, a value between the degree of slip when the skew of the medium is corrected and the degree of slip when the skew of the medium is not corrected in previous experiments in which the feed rollers 113 have different circumferential speeds to attain the speed ratio α.

Alternatively, when a past skew correction of a medium is insufficient, particularly, when a preceding skew correction of a medium is insufficient, the control unit 162 may determine that the correction condition is satisfied. When the inclination of the medium M4 is not eliminated at the time when the trailing end of the medium M4 passes the separation sensor 116, the first skew sensor 118, or the second skew sensor 119 as illustrated in FIG. 12B, the amount of skew correction may be insufficient.

Alternatively, when a past skew correction of a medium is excessive, particularly, when a preceding skew correction of a medium is excessive, the control unit 162 may determine that the correction condition is satisfied. When the direction in which the medium M4 is inclined is opposite to that before the correction is started as illustrated in FIG. 13, the amount of skew correction may be excessive.

When the condition for correcting the circumferential speeds of the feed rollers 113 is not satisfied (NO in step 214), the control unit 162 proceeds to step S216.

By contrast, when the condition for correcting the circumferential speeds of the feed rollers 113 is satisfied (YES in step S214), in step S215, the control unit 162 corrects the circumferential speed of the first feed roller 113a and the circumferential speed of the second feed roller 113b. In a step described later, the control unit 162 corrects the skew of the medium by rotating the feed rollers 113 at the circumferential speeds set in step S213 or the circumferential speeds corrected in step S215.

For example, when the degree of slip is larger than the slip threshold, the control unit 162 corrects the circumferential speeds of the feed rollers 113 to achieve a greater speed ratio of the circumferential speeds of the feed rollers 113 than the speed ratio α expressed in Formula (3) above. The control unit 162 may correct the circumferential speeds of the feed rollers 113 to increase the difference between the circumferential speed of the first feed roller 113a and the circumferential speed of the second feed roller 113b as the degree of slip increases. A larger degree of slip may hamper the transmission of the feeding force from the feed rollers 113 to the medium and decrease the degree of skew correction. When the degree of slip is relatively large, the media conveying apparatus 100 increases the difference in the circumferential speed between the feed rollers 113 to correct the inclination of the medium more appropriately.

In this way, the control unit 162 sets, based on the degree of slip, the circumferential speed of the first feed roller 113a and the circumferential speed of the second feed roller 113b for correction of the skew of the medium. Accordingly, the media conveying apparatus 100 more appropriately corrects the skew of the medium.

When a past skew correction of a medium is insufficient, the control unit 162 sets the speed ratio of the circumferential speeds of the feed rollers 113 to be greater than the speed ratio set for the medium subjected to the insufficient skew correction. As described above, when the correction is insufficient, the amount of skew correction of the medium may be insufficient. When a past skew correction of a medium is insufficient, the media conveying apparatus 100 increases the difference in the circumferential speed between the feed rollers 113 to more appropriately correct the inclination of the medium currently conveyed.

By contrast, when a past skew correction of a medium is excessive, the control unit 162 sets the speed ratio of the circumferential speeds of the feed rollers 113 to be smaller than the speed ratio set for the medium subjected to the excessive skew correction. As described above, when the correction is excessive, the amount of skew correction of the medium may be excessive. When a past skew correction of a medium is excessive, the media conveying apparatus 100 decreases the difference in the circumferential speed between the feed rollers 113 to more appropriately correct the inclination of the medium currently conveyed.

In this way, the control unit 162 corrects the circumferential speeds of the first feed roller 113a and the second feed roller 113b, based on the time when each of the first skew sensor 118 and the second skew sensor 119 detects the trailing end of the medium subjected to the skew correction. Since the media conveying apparatus 100 corrects the skew of the medium with the amount of correction suitable for the latest state of the media conveying apparatus 100, the media conveying apparatus 100 more appropriately corrects the skew of the medium.

In step S216, the control unit 162 starts the skew correction of the medium by rotating, at the set speed, the motor for rotating the feed rollers 113. In this way, the control unit 162 starts the skew correction of the medium when one of the first skew sensor 118 and the second skew sensor 119 detects the medium.

In particular, when the medium is skewed, the control unit 162 corrects the skew of the medium with the feed rollers 113. When the medium is skewed, the control unit 162 corrects the skew of the medium with the first feed roller 113a and the second feed roller 113b having different circumferential speeds from each other. In other words, the control unit 162 corrects the skew of the medium by setting the circumferential speed of one of the feed rollers 113 to be higher than the circumferential speed of another one of the feed rollers 113. Accordingly, the control unit 162 corrects the skew of the medium as appropriate. FIG. 14 is a graph illustrating the inclination of a medium.

In FIG. 14, the horizontal axis represents the inclination (degree) of a medium relative to the width direction A4 before the medium is subjected to the skew correction, whereas the vertical axis represents the inclination (degree) of the medium relative to the width direction A4 after the medium is subjected to the skew correction. G1 indicates the inclination of a medium when the feed rollers 113, the first skew sensor 118, and the second skew sensor 119 are disposed as described above and the speed ratio of the circumferential speeds of the feed rollers 113 is the speed ratio α expressed in Formula (3). As indicated by G1, as the inclination of the medium before the skew correction increases, the inclination of the medium after the skew correction increases. However, the inclination of the medium after the skew correction is sufficiently smaller than the inclination of the medium before the skew correction.

In this way, the media conveying apparatus 100 appropriately corrects the skew of the medium while fixing the speed ratio of the feed rollers 113, with each of the first skew sensor 118 and the second skew sensor 119 disposed, in the width direction A4, at the rotational center position of the medium rotated for the skew correction. Since the media conveying apparatus 100 corrects the skew of the medium easily and appropriately without adjusting the circumferential speeds of the feed rollers 113 based on the inclination of the medium, the media conveying apparatus 100 reduces the processing load on the skew correction of the medium.

G2 illustrated in FIG. 14 indicates the inclination of the medium when the skew of the medium is corrected with the feed rollers 113 having a certain degree of slip. When the skew of the medium is corrected with the feed rollers 113 having a certain degree of slip, the speed ratio of the speeds at which the medium is actually moved by the feed rollers 113 is smaller than the speed ratio of the circumferential speeds of the feed rollers 113. For this reason, as indicated by G2, the inclination of the medium after the skew correction may not be insufficiently small. As described above, the media conveying apparatus 100 corrects, based on the degree of slip, the circumferential speeds of the feed rollers 113 for correction of the skew of the medium. Thus, the media conveying apparatus 100 corrects the skew of the medium so that the inclination of the medium after the correction is closer to 0.

In step S217, the control unit 162 sets the state information to a correction-in-progress state indicating that the skew correction of the medium is in progress.

In step S218, the control unit 162 determines whether the skew correction of the medium is currently in progress and the separation roller 114 is reversed or stopped after the forward rotation. The control unit 162 determines whether the skew correction of the medium is currently in progress, based on whether the state information is set to the correction-in-progress state.

Based on the rotational direction indicated by the signal value of the rotation signal, the control unit 162 determines whether the separation roller 114 is rotated forward (i.e., rotated in the media feeding direction) or the separation roller 114 is reversed (i.e., rotated in the opposite media-feeding direction A13) or stopped. When the signal value of the received rotation signal indicates a distance traveled by the outer circumferential surface of the separation roller 114 equal to or greater than a predetermined distance, the control unit 162 may further determine that the separation roller 114 is reversed. In this case, when the signal value of the rotation signal indicates a total distance traveled by the reversed separation roller 114 equal to or greater than a predetermined distance, the control unit 162 determines that the separation roller 114 is reversed. Thus, the control unit 162 prevents erroneous determination that the separation roller 114 is reversed though a slight slip occurs.

FIGS. 15A to 15C are schematic diagrams illustrating the feeding of media that are placed on the receptacle 103 without aligning the leading ends of the media. Specifically, FIGS. 15A to 15C illustrate an example in which multiple media are placed on the receptacle 103 such that the leading end of a medium M6 is positioned downstream from the leading end of a medium M5 in the media conveyance direction A2. The medium M5 is the uppermost medium of the media placed on the receptacle 103, whereas the medium M6 is a medium below the medium M5.

FIG. 15A illustrates the state of rollers immediately after the start of feeding of the media. As illustrated in FIG. 15A, immediately after the start of feeding of the media, the pick roller 112 and the feed roller 113 are driven by the motor 141 to rotate in the media feeding directions All and A12, respectively, whereas the separation roller 114 is driven by the motor 141 to rotate in the opposite media-feeding direction A13. When more than one medium have not reached the separators (i.e., the feed roller 113 and the separation roller 114) as illustrated in FIG. 15A, the separation roller 114 rotates in a media feeding direction A13′ in accordance with the rotation of the feed roller 113 by the action of the torque limiter for the separation roller 114.

FIG. 15B illustrates the leading end of the medium M6 below the medium M5 passing between the separators. As illustrated in FIG. 15B, when the medium M6 below the medium M5, instead of the medium M5 that is to be fed, contacts the feed roller 113, the medium M6 is fed downstream in the media conveyance direction A2 by the feed roller 113. In this case, the torque limiter for the separation roller 114 stops the driving force from the motor 141. As a result, without being rotated by the driving force from the motor 141, the separation roller 114 rotates in the media feeding direction A13′ in accordance with the rotation of the feed roller 113.

FIG. 15C illustrates the media of which the feeding is continued from the state illustrated in FIG. 15B. As illustrated in FIG. 15C, after the medium M6 below the medium M5 passes between the separators prior to the medium M5, the uppermost medium M5 is fed by the pick roller 112 and the feed roller 113 (together with the media between the medium M5 and the medium M6) and passes between the separators. When the uppermost medium M5 passes between the separators, more than one medium are present between the feed roller 113 and the separation roller 114. When the driving force is transmitted from the motor 141 to the separation roller 114, the separation roller 114 is reversed (i.e., rotated in the opposite media-feeding direction A13) or stopped. As a result, the medium M6 in contact with the separation roller 114 is pushed back upstream in the media conveyance direction A2.

When the separation roller 114 is reversed or stopped after the forward rotation as described above, media may have been placed on the receptacle 103 without aligning the leading ends of the media and more than one medium may be temporarily conveyed downstream from the separation roller 114 in the media conveyance direction A2. When the leading end of the medium temporarily conveyed downstream from the separation roller 114 in the media conveyance direction A2 is detected by the separation sensor 116, the pick sensor 117, the first skew sensor 118, or the second skew sensor 119, the skew state of the medium may be erroneously determined.

When the skew correction of the medium is not currently in progress, or when the separation roller 114 has been neither reversed nor stopped after the forward rotation (NO in step S218), the control unit 162 proceeds to step S221.

By contrast, when the skew correction of the medium is currently in progress and the separation roller 114 is reversed or stopped after the forward rotation (YES in step S218), in step S219, the control unit 162 starts the reverse skew correction of the medium. The control unit 162 executes the reverse correction to apply the force to the medium in a direction opposite to the direction of the skew correction started in step S216 in the width direction A4. For example, the control unit 162 sets the circumferential speed set for the first feed roller 113a as the circumferential speed of the second feed roller 113b, whereas the control unit 162 sets the circumferential speed set for the second feed roller 113b as the circumferential speed of the first feed roller 113a. The control unit 162 then rotates the feed rollers 113 at the set speeds for the same time as the elapsed time from the start of skew correction in step S216 to the current time.

In this way, the control unit 162 corrects the skew of the medium by setting the circumferential speed of a first one of the feed rollers 113 to be higher than the circumferential speed of a second one of the feed rollers 113. When the rotation sensor 115 detects the reverse rotation or stop of the separation roller 114 after detecting the forward rotation of the separation roller 114 during the skew correction of the medium, the control unit 162 sets the circumferential speed of the first one of the feed rollers 113 to be lower than the circumferential speed of the second one of the feed rollers 113. Thus, the media conveying apparatus 100 returns the direction of the medium when the skew of the medium is erroneously detected and the medium is rotated in an erroneous direction. Accordingly, the media conveying apparatus 100 prevents the medium from being jammed due to the rotation of the medium in an inappropriate direction.

In step S220, the control unit 162 sets the state information to a reverse-correction-in-progress state indicating that the reverse skew correction of the medium is in progress.

In step S221, the control unit 162 determines whether a condition for completing the skew correction of the medium (i.e., completion condition) or a condition for stopping the skew correction of the medium (i.e., stop condition) is satisfied. When the condition for completing the skew correction of the medium or the condition for stopping the skew correction of the medium is satisfied, the control unit 162 stops the skew correction of the medium in a step described later.

The control unit 162 determines that the condition for completing the skew correction of the medium is satisfied when the sensor that has not detected the leading end of the medium in step S202, of the first skew sensor 118 and the second skew sensor 119, detects the leading end of the medium. As described above, the medium rotates about the position of the sensor that has detected the leading end of the medium, of the first skew sensor 118 and the second skew sensor 119, during the skew correction. By stopping the skew correction when the sensor that has not detected the leading end of the medium detects the leading end of the medium, the media conveying apparatus 100 aligns the leading end of the medium with the width direction A4 and favorably eliminates the skew of the medium.

When the pick sensor 117 is disposed in the same position as the first skew sensor 118 and the second skew sensor 119 in the media conveyance direction A2, the control unit 162 may stop the skew correction of the medium, based on the result of detection of the medium by the pick sensor 117. For example, the control unit 162 determines that the condition for completing the skew correction of the medium is satisfied when the pick sensor 117 detects the leading end of the medium.

Alternatively, when a fifth time has elapsed after the skew sensor that has not detected the leading end of a medium or the pick sensor 117 detects the leading end of the medium, the control unit 162 may determine that the condition for completing the skew correction of the medium is satisfied. The fifth time is one example of the predetermined time. The fifth time is set to, for example, a mean value of the time taken from when the sensors detect the leading end of the medium to when the inclination of the medium becomes 0 (i.e., the leading end of the medium becomes parallel to the width direction A4) in preliminary experiments.

In this way, the control unit 162 stops the skew correction of the medium when the fifth time has elapsed after the skew sensor that has not detected the leading end of the medium or the pick sensor 117 detects the leading end of the medium. Accordingly, the media conveying apparatus 100 more appropriately corrects the skew of the medium.

The fifth time may be set based on the degree of slip acquired in step S205. For example, the fifth time is set to be longer as the degree of slip is larger, and to be shorter as the degree of slip is smaller. When the degree of slip is relatively large, the medium rotates while slipping during the skew correction. The rotational center position of the medium is shifted downstream from the position of the skew sensor (or the pick sensor 117) in the media conveyance direction A2. The media conveying apparatus 100 stops the skew correction of the medium based on the degree of slip to appropriately correct the skew of the medium in consideration of the slip of the medium caused by the feed rollers 113.

G3 illustrated in FIG. 14 indicates the inclination of a medium when the skew correction of the medium with the feed rollers 113 having the characteristic indicated by G2 is stopped when the fifth time has elapsed after the pick sensor 117 detects the leading end of the medium. As indicated by G3, an increased time for the skew correction in consideration of the slip of the medium further decreases the inclination of the medium after the skew correction.

The control unit 162 determines that the condition for stopping the skew correction of the medium is satisfied when the reverse skew correction of the medium is currently in progress and the time taken to execute the reverse skew correction of the medium is equal to or greater than the time taken to execute the skew correction of the medium. The control unit 162 rotates the medium in the reverse direction for the same duration as the duration of rotation of the medium in an erroneous direction due to an erroneous detection of the skew of the medium.

In this way, when the rotation sensor 115 detects the reverse rotation or stop of the separation roller 114 after detecting the forward rotation of the separation roller 114, the control unit 162 stops the skew correction of the medium. Thus, when media are placed on the receptacle 103 without aligning the leading ends of the media and more than one medium are temporarily conveyed downstream from the separation roller 114 in the media conveyance direction A2, the media conveying apparatus 100 prevents the medium from rotating in an erroneous direction. When a user collectively sets multiple media on the receptacle 103, the user does not need to carefully align the media. Thus, the media conveying apparatus 100 enhances the user-friendliness.

The control unit 162 determines that the condition for stopping the skew correction of the medium is satisfied when the sensor that has detected the leading end of the medium in step S202, of the first skew sensor 118 and the second skew sensor 119, stops detecting the leading end of the medium. When the signal value of the skew signal changes from a value indicating that a medium is absent to a value indicating that a medium is present and then further changes to a value indicating that a medium is absent, the control unit 162 determines that the leading end of the medium has returned upstream from the corresponding skew sensor in the media conveyance direction A2. The control unit 162 then determines that the skew sensor stops detecting the leading end of the medium.

FIG. 16A is a schematic diagram illustrating the medium M4 returning upstream in the media conveyance direction A2.

In the example illustrated in FIG. 16A, the leading end of the medium M4 that has been detected by the first skew sensor 118 illustrated in FIG. 12A returns upstream from the first skew sensor 118 in the media conveyance direction A2 and is no longer detected by the first skew sensor 118. In this case, the medium M4, which is not the medium to be fed, may have moved downstream from the separation roller 114 in the media conveyance direction A2 prior to a medium M7, which is the medium to be fed, and then returned upstream in the media conveyance direction A2 by the separation force of the separation roller 114 when the medium M7 to be fed have passed the separation roller 114.

The control unit 162 stops the skew correction of the medium when the sensor that has detected the leading end of the medium, of the first skew sensor 118 and the second skew sensor 119, stops detecting the leading end of the medium. Thus, the media conveying apparatus 100 prevents the medium M7 that is to be fed from rotating in an erroneous direction.

Alternatively, when the sensor that has detected the leading end of a medium, of the first skew sensor 118 and the second skew sensor 119, stops detecting the leading end of the medium continuously for a sixth time, the control unit 162 may determine that the condition for stopping the skew correction of the medium is satisfied and stop the skew correction of the medium. The sixth time is set to the time taken for a medium to move by the size of a typical punched hole. The medium to be fed may have, for example, a punched hole. With a grace period until the control unit 162 determines that the condition for stopping the skew correction of the medium is satisfied, the control unit 162 prevents erroneous stop of the skew correction of the medium when the punched hole of the medium passes the positions of the skew sensors.

Alternatively, when the sensor that has detected the leading end of the medium in step S202, of the first skew sensor 118 and the second skew sensor 119, stops detecting the leading end of the medium and the other sensor that has not detected the leading end of the medium in step S202 detects the leading end of the medium, the control unit 162 may determine that the condition for stopping the skew correction of the medium is satisfied. Alternatively, when the sensor that has detected the leading end of the medium in step S202, of the first skew sensor 118 and the second skew sensor 119, stops detecting the leading end of the medium and the pick sensor 117 detects the leading end of the medium, the control unit 162 may determine that the condition for stopping the skew correction of the medium is satisfied. In these cases, the control unit 162 may immediately determine that the condition for stopping the skew correction of the medium is satisfied, without waiting for the sixth time to elapse.

FIG. 16B is a schematic diagram illustrating the medium M4 inclined in the opposite direction.

In the example illustrated in FIG. 16B, the medium M4 that has been detected by the first skew sensor 118 illustrated in FIG. 12A is no longer detected by the first skew sensor 118 and is detected by the second skew sensor 119 and the pick sensor 117. In this case, the medium M4 may be inclined in the opposite direction due to an excessive skew correction. When the skew sensor that has detected the leading end of the medium stops detecting the medium and the other skew sensor or the pick sensor 117 detects the medium, the media conveying apparatus 100 stops the skew correction of the medium to prevent the excessive skew correction.

Alternatively, when the pick sensor 117 does not detect the leading end of a medium and each of the first skew sensor 118 and the second skew sensor 119 detects the leading end of a medium, the control unit 162 may determine that the condition for stopping the skew correction of the medium is satisfied and stop the skew correction of a medium.

FIG. 17 is a schematic diagram illustrating a medium M8 and a medium M9 that are not detected by the pick sensor 117 but are detected by the first skew sensor 118 and the second skew sensor 119, respectively.

In the example illustrated in FIG. 17, the medium M8 and the medium M9 are placed on the receptacle 103 without aligning the leading ends of the medium M8 and the medium M9. As illustrated in FIG. 17, the left part of the leading end of the medium M8 proceeds downstream from the feed roller 113 in the media conveyance direction A2 and is detected by the first skew sensor 118, whereas the right part of the leading end of the medium M9 proceeds downstream from the feed roller 113 in the media conveyance direction A2 and is detected by the second skew sensor 119. Such media that are not detected by the pick sensor 117 but are detected by the first skew sensor 118 and the second skew sensor 119 may be separate media that have been placed on the receptacle 103 without being aligned. When the pick sensor 117 does not detect the leading end of a medium and each of the first skew sensor 118 and the second skew sensor 119 detects the leading end of a medium, the media conveying apparatus 100 stops the skew correction of a medium to prevent a skew correction in an erroneous direction.

Alternatively, when the pick sensor 117 detects no medium before an elapse of a seventh time from the start of the skew correction of a medium, the control unit 162 may determine that the condition for stopping the skew correction of the medium is satisfied and stop the skew correction of the medium. The seventh time is one example of the predetermined time. The seventh time is set to, for example, a maximum value of the time taken from when the skew correction of the medium, which is not jammed, is started to when the pick sensor 117 detects the medium in preliminary experiments. When the pick sensor 117 detects no medium before an elapse of the seventh time from the start of the skew correction of a medium, the control unit 162 determines that the medium is jammed or is likely to be jammed and stops the skew correction of the medium. Accordingly, the media conveying apparatus 100 prevents damage to the jammed medium due to the load on the jammed medium.

Referring back to FIG. 10, when neither the condition for completing the skew correction nor the condition for stopping the skew correction is satisfied (NO in step S221), the control unit 162 proceeds to step S228.

By contrast, when the condition for completing the skew correction or the condition for stopping the skew correction is satisfied (YES in step S221), in step S222, the control unit 162 controls the motor 141 to temporarily stop the pick roller 112, the feed roller 113, the separation roller 114, and/or the first to sixth conveyance rollers 120a to 120f.

In step S223, the control unit 162 controls the motor 141 to return the pressing force that presses the separation roller 114 toward the feed roller 113 and that has been increased in step S209 to the reference value. Thus, when the skew of the medium is not corrected, the media conveying apparatus 100 sets the frictional force generated between the fed medium and the feed roller 113 to an appropriate value and favorably feeds the medium.

In step S224, the control unit 162 controls the motor 141 to move the pick roller 112 from the second position to the first position. Specifically, when stopping the skew correction of the medium, the control unit 162 controls the arm 131 supporting the pick roller 112, the biasing member 131c, and the motor 141 to move the pick roller 112 from the second position to the first position. Accordingly, the pick roller 112 contacts the medium placed on the receptacle 103 and feeds and conveys the medium as appropriate.

In step S225, the control unit 162 sets the state information to an end standby state indicating standby until the skew correction of the medium is ended.

In step S226, the control unit 162 determines whether the condition for stopping the skew correction (i.e., stop condition) has been satisfied in step S221. When the stop condition is not satisfied (NO in step S226), the control unit 162 proceeds to step S228. By contrast, when the stop condition is satisfied (YES in step S226), in step S227, the control unit 162 displays a message on the display device 106 or transmits data to the information processor via the interface device 142 to notify the user that the skew correction of the medium is to be stopped (canceled). The control unit 162 may further notify the user of the reason for stopping (canceling) the skew correction of the medium.

In step S228, the control unit 162 determines whether a condition for ending the skew correction (i.e., end condition) is satisfied. When the condition for ending the skew correction is satisfied, the control unit 162 stops the skew correction of the medium and restarts conveying the medium in a step described later.

The control unit 162 determines that the condition for ending the skew correction is satisfied when an eighth time has elapsed after the setting of the state information to the end standby state. In other words, the control unit 162 determines that the condition for ending the skew correction is satisfied when the eighth time has elapsed after the start of control of the motor 141 to return the pressing force that presses the separation roller 114 toward the feed roller 113. The control unit 162 determines that the condition for ending the skew correction is satisfied when the eighth time has elapsed after the start of control of the moving mechanism to move the pick roller 112 to the first position. The eighth time is one example of a second predetermined time. The eighth time is set to the time taken from when the control of the motor 141 is started to when the pressing force of the separation roller 114 is changed or to when the pick roller 112 is moved to the first position in actual. By contrast, when the state information is set to a state other than the end standby state, or when the eighth time has not elapsed after the setting of the state information to the end standby state, the control unit 162 determines that the condition for ending the skew correction is not satisfied.

In this way, the control unit 162 stops the skew correction of the medium after an elapse of the eighth time from the start of control of the motor 141 to return the pressing force that presses the separation roller 114 toward the feed roller 113. As a result, the media conveying apparatus 100 restarts conveying the medium while reliably returning the pressing force that presses the separation roller 114 toward the feed roller 113. Thus, the media conveying apparatus 100 more appropriately conveys the medium. When the skew correction of the medium is completed, the control unit 162 controls the moving mechanism to move the pick roller 112 from the second position to the first position. The control unit 162 stops conveying the medium until the eighth time elapses after the start of control of the moving mechanism to move the pick roller 112 from the second position to the first position. If the medium is started to be fed and conveyed before the pick roller 112 contacts the medium, the medium may be skewed. The media conveying apparatus 100 stops conveying the medium until the pick roller 112 reliably contacts the medium, to prevent the medium from being skewed.

When the condition for ending the skew correction is not satisfied (NO in step S228), the control unit 162 proceeds to step S231.

By contrast, when the condition for ending the skew correction is satisfied (YES in step S228), in step S229, the control unit 162 stops the skew correction of the medium by returning the circumferential speed of the first feed roller 113a and the circumferential speed of the second feed roller 113b to the same reference speed.

In step S230, the control unit 162 drives the motor 141 to rotate the pick roller 112, the feed roller 113, the separation roller 114, and/or the first to sixth conveyance rollers 120a to 120f again.

In step S231, the control unit 162 determines whether the skew correction has been executed for the medium currently conveyed. When the skew correction has not been executed for the medium currently conveyed (NO in step S231), the control unit 162 proceeds to step S234.

By contrast, when the skew correction has been executed for the medium currently conveyed (YES in step S231), in step S232, the control unit 162 determines whether the skew correction of the medium is insufficient. As described above, for example, when one of the first skew sensor 118 and the second skew sensor 119 detects the leading end of the medium prior to the other one and then detects the trailing end of the medium before the separation sensor 116 detects the trailing end of the medium, the control unit 162 determines that the correction is insufficient.

When the signal value of the first skew signal changes from a value indicating that a medium is present to a value indicating that a medium is absent, the control unit 162 determines that the trailing end of the medium has passed the position of the first skew sensor 118 and the first skew sensor 118 has detected the trailing end of the medium. When the signal value of the second skew signal changes from a value indicating that a medium is present to a value indicating that a medium is absent, the control unit 162 determines that the trailing end of the medium has passed the position of the second skew sensor 119 and the second skew sensor 119 has detected the trailing end of the medium. When the signal value of the separation signal changes from a value indicating that a medium is present to a value indicating that a medium is absent, the control unit 162 determines that the trailing end of the medium has passed the position of the separation sensor 116 and the separation sensor 116 has detected the trailing end of the medium. When the control unit 162 determines that the correction is insufficient (YES in step S232), in step S236, the control unit 162 stores, in the storage device 150, information indicating that the correction is insufficient. Then, the control unit 162 proceeds to step S234. By contrast, when the control unit 162 determines that the correction is not insufficient (NO in step S232), the control unit 162 proceeds to step S233.

In step S233, the control unit 162 determines whether the skew correction of the medium is excessive. As described above, for example, when the order in which the first skew sensor 118 and the second skew sensor 119 detect the trailing end of the medium is changed from the order in which the first skew sensor 118 and the second skew sensor 119 detect the leading end of the medium, the control unit 162 determines that the correction is excessive. When the control unit 162 determines that the correction is excessive (YES in step S233), in step S237, the control unit 162 stores, in the storage device 150, information indicating that the correction is excessive. Then, the control unit 162 proceeds to step S234. By contrast, when the control unit 162 determines that the correction is not excessive (NO in step S233), the control unit 162 proceeds to step S234.

In step S234, the control unit 162 determines whether an error in the skew correction (i.e., correction error) has occurred. For example, when neither the condition for completing the skew correction of the medium nor the condition for stopping the skew correction of the medium is satisfied within a predetermined time from the start of the skew correction of the medium, the control unit 162 determines that an error in the skew correction has occurred. When no error in the skew correction has occurred (NO in step S234), the control unit 162 returns to step S201 and repeats the operations from step S201 onward.

By contrast, when an error in the skew correction has occurred (YES in step S234), in step S235, the control unit 162 executes an error operation. As the error operation, the control unit 162 controls the motor 141 to stop the pick roller 112, the feed roller 113, the separation roller 114 and/or the first to sixth conveyance rollers 120a to 120f. Then, as the error operation, the control unit 162 displays a message on the display device 106 or transmits data to the information processor via the interface device 142 to notify the user that an error in the skew correction has occurred. Thus, the media conveying apparatus 100 prevents a medium from being jammed and damaged. The control unit 162 then returns to step S201 and repeats the operations from step S201 onward.

The operations in steps S101 and S102 of FIG. 7 may be omitted. In this case, in step S213 of FIG. 9, the control unit 162 sets the circumferential speeds of the feed rollers 113 to the predetermined first speed VI and the predetermined second speed V2.

The operation in step S108 of FIG. 7 and the operation in step S205 of FIG. 8 may be omitted. In this case, in step S206 of FIG. 8, the control unit 162 does not determine, based on the degree of slip, whether the condition for prohibiting the skew correction is satisfied. In step S214 of FIG. 9, the control unit 162 does not determine, based on the degree of slip, whether the condition for correcting the circumferential speeds of the feed rollers 113 is satisfied. In step S215 of FIG. 9, the control unit 162 does not correct, based on the degree of slip, the circumferential speed of the feed roller 113. In step S221 of FIG. 10, the control unit 162 does not determine, based on the degree of slip, whether the condition for stopping the skew correction of the medium is satisfied.

The operations in steps S202 to S204 of FIG. 8 may be omitted. In this case, the control unit 162 starts the skew correction of the medium when the leading end of the medium passes one of the first skew sensor 118 and the second skew sensor 119, without determining whether the medium is skewed.

The operations in steps S206 and S207 of FIG. 8 may be omitted. In step S206 of FIG. 8, the control unit 162 may determine that the condition for prohibiting the skew correction is satisfied when the separation roller 114 is reversed or stopped after the forward rotation, like the operation in step S218 of FIG. 9.

The operation in step S209 of FIG. 8 and/or the operation in step S223 of FIG. 10 may be omitted. Instead of the operation in step S223 of FIG. 10, the control unit 162 may return the pressure that presses the separation roller 114 toward the feed roller 113 under the automatic torque control. The operation in step S210 of FIG. 8 and the operation in step S224 of FIG. 10 may be omitted. In step S212 of FIG. 9, the control unit 162 may determine that the condition for starting the skew correction is satisfied immediately after starting the control of the motor 141 to increase the pressing force that presses the separation roller 114 toward the feed roller 113. Alternatively, in step S212 of FIG. 9, the control unit 162 may determine that the condition for starting the skew correction is satisfied immediately after starting the control of the moving mechanism to move the pick roller 112 to the second position. Similarly, in step S228 of FIG. 10, the control unit 162 may determine that the condition for ending the skew correction is satisfied immediately after starting the control of the motor 141 to return the pressing force that presses the separation roller 114 toward the feed roller 113. Similarly, in step S228 of FIG. 10, the control unit 162 may determine that condition for ending the skew correction is satisfied immediately after starting the control of the moving mechanism to move the pick roller 112 to the first position.

The operations in steps S214 and S215 of FIG. 9 may be omitted.

The operations in steps S218 to S220 of FIG. 9 may be omitted. In this case, in step S221 of FIG. 10, the control unit 162 may determine that condition for stopping the skew correction is satisfied immediately after the separation roller 114 is reversed or stopped after the forward rotation. When the control unit 162 determines, in step S221, that the condition for stopping the skew correction of the medium is satisfied because the separation roller 114 is reversed or stopped after the forward rotation, the control unit 162 may re-determine the skew of the medium after stopping the skew correction. In this case, the control unit 162 sets (initializes) the state information to the not-started state after stopping the skew correction in step S229 of FIG. 10. As a result, the skew of the medium is corrected again. Thus, the media conveying apparatus 100 enhances an appropriate skew correction of the medium.

In step S221 of FIG. 10, the control unit 162 may not determine whether the condition for stopping the skew correction of the medium is satisfied. When the control unit 162 determines, in step S221, that the condition for stopping the skew correction of the medium is satisfied because the skew sensor that has detected the leading end of the medium stops detecting the leading end of the medium, the control unit 162 may re-determine the skew of the medium after stopping the skew correction. In this case, the control unit 162 sets (initializes) the state information to the not-started state after stopping the skew correction in step S229 of FIG. 10. As a result, the skew of the medium is corrected again. Thus, the media conveying apparatus 100 enhances an appropriate skew correction of the medium.

The operations in steps S222 and S230 of FIG. 10 may be omitted.

The operations in steps S226 and S227 of FIG. 10 may be omitted.

The operation in step S232 of FIG. 10 may be omitted. In this case, in step S206 of FIG. 8, the control unit 162 does not determine, based on the insufficient correction, whether the condition for prohibiting the skew correction is satisfied. In step S214 of FIG. 9, the control unit 162 does not determine, based on the insufficient correction, whether the condition for correcting the circumferential speeds of the feed rollers 113 is satisfied. Similarly, the operation in step S233 of FIG. 10 may be omitted. In this case, in step S206 of FIG. 8, the control unit 162 does not determine, based on the excessive correction, whether the condition for prohibiting the skew correction is satisfied. In step S214 of FIG. 9, the control unit 162 does not determine, based on the excessive correction, whether the condition for correcting the circumferential speeds of the feed rollers 113 is satisfied.

Examples of the condition for prohibiting the skew correction, the condition for correcting the circumferential speeds of the feed rollers 113, and the condition for completing or stopping the skew correction of the medium are not limited to aforementioned examples and may include at least one of the aforementioned examples.

As described above, the media conveying apparatus 100 sets the positions, in the width direction A4, of the skew sensors for starting the skew correction of a medium to coincide with the rotational center position of the medium during the skew correction, based on the speed ratio of the feed rollers 113 during the skew correction. Thus, the media conveying apparatus 100 rotates each of the feed rollers 113 at a predetermined speed regardless of the inclination of the skewed medium to correct the skew of the medium as appropriate. In short, the media conveying apparatus 100 corrects the skew of the medium more easily and appropriately without calculating the amount of inclination of the medium. Accordingly, the media conveying apparatus 100 reduces the processing time and the processing load of the medium reading process and the power consumption.

Since the media conveying apparatus 100 does not need to calculate the amount of inclination of the medium, the media conveying apparatus 100 can start the skew correction of the medium before the leading end of the medium passes both the first skew sensor 118 and the second skew sensor 119. As a result, the media conveying apparatus 100 can correct the skew of the medium before the leading end of the skewed medium contacts the conveyance rollers downstream from the first skew sensor 118 and second skew sensor 119 in the media conveyance direction A2. Thus, the media conveying apparatus 100 favorably corrects the skew of the medium. In addition, since the conveyance rollers do not need to be sufficiently away from the feed rollers 113 in the media conveyance direction A2, the media conveying apparatus 100 can support conveyance of small-sized media and can be downsized.

FIG. 18 is a schematic diagram illustrating a configuration of a processing circuit 260 of a media conveying apparatus according to another embodiment of the present disclosure.

The processing circuit 260 is used instead of the processing circuit 160 of the media conveying apparatus 100. The processing circuit 260 executes, for example, the medium reading process and the skew determination process, instead of the processing circuit 160. The processing circuit 260 includes, for example, a reception circuit 261, a control circuit 262, an acquisition circuit 263, and a determination circuit 264. These circuits may be, for example, independent integrated circuits, microprocessors, or firmware.

The reception circuit 261 is one example of a reception unit and functions like the reception unit 161. The reception circuit 261 receives the setting signal from the operation device 105 or the interface device 142. The reception circuit 261 receives the setting designated by the received setting signal and stores the setting in the storage device 150.

The control circuit 262 is one example of a control unit and functions like the control unit 162. The control circuit 262 receives the operation signal from the operation device 105 or the interface device 142. The control circuit 262 also receives the receptacle signal, the rotation signal, the separation signal, the pick signal, and the feed signal from the receptacle sensor 111, the rotation sensor 115, the separation sensor 116, the pick sensor 117, and the feed sensor 122, respectively. The control circuit 262 reads the degree of slip and the determination result of the skew from the storage device 150. The control circuit 262 controls the motor 141 based on the received signals and/or the read information, acquires an input image from the imaging device 123, and outputs the input image to the interface device 142.

The acquisition circuit 263 is one example of an acquisition unit and functions like the acquisition unit 163. The acquisition circuit 263 receives the separation signal and the pick signal from the separation sensor 116 and the pick sensor 117, respectively, and calculates the degree of slip based on the received signals. Alternatively, the acquisition circuit 263 reads the degree of slip from the storage device 150. The acquisition circuit 263 stores the calculated or read degree of slip in the storage device 150.

The determination circuit 264 is one example of a determination unit and functions like the determination unit 164. The determination circuit 264 receives the first skew signal and the second skew signal from the first skew sensor 118 and the second skew sensor 119, respectively. The determination circuit 264 determines whether the medium is skewed, based on the received signals, and stores the determination result in the storage device 150.

As described above, the media conveying apparatus can correct the skew of the medium more easily and appropriately with the processing circuit 260.

Although the preferred embodiments have been described above, the embodiments are not limited thereto. For example, the first skew sensor 118 and/or the second skew sensor 119 may be disposed at a position different from the rotational center position of the medium in the width direction A4. The first skew sensor 118 and/or the second skew sensor 119 may be disposed at a position shifted outward or inward from the rotational center position in the width direction A4, based on the degree of slip in the media conveying apparatus 100 in an unused state (at the time of shipment). The first skew sensor 118 and/or the second skew sensor 119 may be disposed upstream from the position at the distance A that satisfies In equation (4) above in the media conveyance direction A2.

The media conveying apparatus may correct the skew of media with any of the first to sixth conveyance rollers 120a to 120f instead of the feed rollers 113. In this case, the conveyance rollers for correcting the skew of media include a plurality of rollers that are disposed at intervals in the width direction A4 and rotate independently to convey the media. Sensors like the separation sensor 116, the pick sensor 117, the first skew sensor 118, and the second skew sensor 119 are disposed downstream from the conveyance rollers for correcting the skew of media in the media conveyance direction A2. Such sensors are disposed such that relative positions between the conveyance rollers and the sensors are substantially the same as the relative positions between the feed rollers 113 and the separation sensor 116, the pick sensor 117, the first skew sensor 118, and the second skew sensor 119. Each of the conveyance rollers or each of the driven rollers facing the conveyance rollers is provided with an applying mechanism like the applying mechanism for applying the pressing force to the separation roller 114. The control unit 162 determines whether a medium is skewed, based on the output signals from the sensors. When the medium is skewed, the control unit 162 corrects the skew of the medium with the conveyance rollers having different circumferential speeds from each other. The control unit 162 controls the conveyance rollers for correcting the skew of media instead of the feed roller 113, according to the above-described processes, based on the output signals from the sensors.

The media conveying apparatus may use another sensor instead of the rotation sensor 115 to detect the multiple feeding of media. The media conveying apparatus detects the multiple feeding of media with, for example, an optical sensor. In this case, the optical sensor is disposed to image, from below, a nip-overlapping area of a medium that is fed.

The nip-overlapping area is an area overlapping with the nip N1 between the feed roller 113 and the separation roller 114 when viewed in the width direction A4. The optical sensor includes a light emitter and a light receiver disposed on the same side of the media conveyance passage, which is a passage through which media are conveyed. The optical sensor detects the movement of media in the media conveyance direction A2 and the width direction A4. The light emitter is, for example, an LED and emits light toward the media conveyance passage. The light receiver captures images corresponding to the light received at regular intervals. The light receiver detects a common portion from the latest image and the immediately preceding image. The light receiver calculates the moving direction and moving speed of the medium conveyed, based on the changes in the position within the common image detected. The light receiver then generates and outputs a movement signal indicating the calculated moving direction and moving speed. The regular interval is, for example, a period corresponding to 100 operation pulses of the motor 141. In step S218, the control unit 162 receives the movement signal from the optical sensor and identifies the moving direction of the medium based on the signal value of the received movement signal. Based on the identified moving direction, the control unit 162 determines whether the separation roller 114 is rotated forward, rotated backward (i.e., reversed), or stopped.

The media conveying apparatus may include a so-called straight path to feed and convey the media placed on the receptacle from bottom to top. In this case, the feed roller is disposed below the separation roller so as to face the separation roller.

A description is given below of several aspects of the above embodiments of the present disclosure.

According to a first aspect, a media conveying apparatus includes a first roller, a second roller, a determination unit, a control unit, and a reception unit. The first roller and the second roller are spaced apart in a direction orthogonal to a direction in which a medium is conveyed, to rotate independently to convey the medium. The determination unit determines whether the medium is skewed. When the medium is skewed, the control unit corrects the skew of the medium with the first feed roller and the second feed roller having different circumferential speeds from each other. The reception unit receives, from a user, a setting related to the circumferential speed of the first roller or the circumferential speed of the second roller for correction of the skew of the medium.

According to a second aspect, a media conveying apparatus includes a roller, a first sensor, a second sensor, a pick sensor, a determination unit, and a control unit. The roller conveys a medium. The first sensor and the second sensor are spaced apart in a direction orthogonal to a medium conveyance direction in which the medium is conveyed, to detect the medium. The pick sensor is disposed upstream from the first sensor and the second sensor in the medium conveyance direction and between the first sensor and the second sensor in the direction orthogonal to the medium conveyance direction, to detect the medium. The determination unit determines whether the medium is skewed, based on a detection result from the first sensor or the second sensor. The control unit corrects a skew of the medium when the medium is skewed. When the pick sensor detects the medium before the first sensor and the second sensor detect the medium, the control unit does not correct the skew of the medium.

According to a third aspect, a media conveying apparatus includes a roller, a first sensor, a second sensor, a separation sensor, a determination unit, and a control unit. The roller conveys a medium. The first sensor and the second sensor are spaced apart in a direction orthogonal to a medium conveyance direction in which the medium is conveyed, to detect the medium. The separation sensor is disposed upstream from the first sensor and the second sensor in the medium conveyance direction and between the first sensor and the second sensor in the direction orthogonal to the medium conveyance direction, to detect the medium. The determination unit determines whether the medium is skewed, based on a detection result from the first sensor or the second sensor. The control unit corrects a skew of the medium when the medium is skewed. When the first sensor or the second sensor detects the medium before the separation sensor detects the medium, the control unit does not correct the skew of the medium.

According to a fourth aspect, a media conveying apparatus includes a feed roller, a separation roller, a rotation sensor, a plurality of skew sensors, a determination unit, and a control unit. The feed roller feeds a medium. The separation roller faces the feed roller. The rotation sensor detects the rotation of the separation roller. The skew sensors are spaced apart in a direction orthogonal to a direction in which the medium is conveyed, to detect the medium. The determination unit determines whether the medium is skewed, based on output signals from the skew sensors. The control unit corrects a skew of the medium when the medium is skewed. When the rotation sensor detects a reverse rotation or stop of the separation roller after detecting a forward rotation of the separation roller, the control unit stops correcting the skew of the medium.

According to a fifth aspect, the media conveying apparatus of the fourth aspect further includes a plurality of feed rollers including the feed roller. The control unit sets a circumferential speed of a first one of the feed rollers to be higher than a circumferential speed of a second one of the feed rollers to correct the skew of the medium. When the rotation sensor detects the reverse rotation or stop of the separation roller after detecting the forward rotation of the separation roller during the correction of the skew of the medium, the controller sets the circumferential speed of the first one of the feed rollers to be lower than the circumferential speed of the second one of the feed rollers.

According to a sixth aspect, a media conveying apparatus includes a feed roller, a separation roller, an applying mechanism, a determination unit, and a control unit. The feed roller feeds a medium. The separation roller faces the feed roller. The applying mechanism applies, to the separation roller, a pressing force that presses the separation roller toward the feed roller. The determination unit determines whether the medium is skewed. The control unit corrects a skew of the medium with the feed roller when the medium is skewed. The control unit controls the applying mechanism to generate different pressing forces between when the skew of the medium is corrected and when the skew of the medium is not corrected.

According to a seventh aspect, a media conveying apparatus includes a pick roller, a moving mechanism, a conveyance roller, a determination unit, and a control unit. The pick roller conveys a medium. The moving mechanism moves the pick roller between a first position at which the pick roller contacts the medium and a second position at which the pick roller is separated from the medium. The conveyance roller is disposed downstream from the pick roller in a direction in which the medium is conveyed, to convey the medium. The determination unit determines whether the medium is skewed. When the medium is skewed, the control unit controls the moving mechanism to move the pick roller to the second position and corrects a skew of the medium with the conveyance roller. The control unit starts correcting the skew of the medium after an elapse of a predetermined time from the start of control of the moving mechanism to move the pick roller to the second position.

According to an eighth aspect, in the media conveying apparatus of the seventh aspect, when the correction of the skew of the medium is completed, the control unit controls the moving mechanism to move the pick roller to the first position and stops conveying the medium until a second time elapses after the start of control of the moving mechanism to move the pick roller to the first position.

According to a ninth aspect, a media conveying apparatus includes a first roller, a second roller, a determination unit, a control unit, and an acquisition unit. The first roller and the second roller are spaced apart in a direction orthogonal to a direction in which a medium is conveyed, to rotate independently to convey the medium. The determination unit determines whether the medium is skewed. When the medium is skewed, the control unit corrects the skew of the medium with the first feed roller and the second feed roller having different circumferential speeds from each other. The acquisition unit acquires a degree of slip between the first and second rollers and the medium conveyed by the first and second rollers. The control unit sets, based on the degree of slip, the circumferential speed of the first feed roller and the circumferential speed of the second feed roller for correction of the skew of the medium.

According to a tenth aspect, the media conveying apparatus of the ninth aspect further includes a memory that stores the degree of slip in advance. The acquisition unit reads the degree of slip stored in advance in the memory to acquire the degree of slip. According to an eleventh aspect, in the media conveying apparatus of the ninth aspect, the acquisition unit calculates the degree of slip of the medium conveyed immediately before to acquire the degree of slip.

According to a twelfth aspect, a media conveying apparatus includes a first roller, a second roller, a plurality of sensors, a determination unit, and a control unit. The first roller and the second roller are spaced apart in a direction orthogonal to a medium conveyance direction in which a medium is conveyed, to rotate independently to convey the medium. The skew sensors are spaced apart in the direction orthogonal to the medium conveyance direction. The determination unit determines whether the medium is skewed, based on a time when each of the skew sensors detects a leading end of the medium. When the medium is skewed, the control unit corrects the skew of the medium with the first feed roller and the second feed roller having different circumferential speeds from each other. The control unit corrects the circumferential speed of the first roller or the circumferential speed of the second roller, based on a time when each of the skew sensors detects a trailing end of the medium of which the skew is corrected.

According to a thirteenth aspect, a media conveying apparatus includes a roller, a plurality of sensors, and a control unit. The roller conveys a medium. The skew sensors are spaced apart in a direction orthogonal to a direction in which the medium is conveyed. When a sensor of the skew sensors detects the medium, the control unit starts correcting a skew of the medium. When the sensor that has detected the medium stops detecting the medium, the control unit stops correcting the skew of the medium.

According to a fourteenth aspect, in the media conveying apparatus of the thirteenth aspect, the control unit stops correcting the skew of the medium when one of the sensors that has detected the medium stops detecting the medium continuously for a predetermined time.

According to a fifteenth aspect, a media conveying apparatus includes a roller, a first sensor, a second sensor, a pick sensor, and a control unit. The roller conveys a medium. The first sensor and the second sensor are spaced apart in a direction orthogonal to a medium conveyance direction in which the medium is conveyed. The pick sensor is disposed between the first sensor and the second sensor in the direction orthogonal to the medium conveyance direction. When one of the first skew sensor and the second skew sensor detects the medium, the control unit starts correcting a skew of the medium. When the pick sensor does not detect the medium and both the first sensor and the second sensor detect the medium, the control unit stops correcting the skew of the medium.

According to a sixteenth aspect, a media conveying apparatus includes a roller, a first sensor, a second sensor, a pick sensor, and a control unit. The roller conveys a medium. The first sensor and the second sensor are spaced apart in a direction orthogonal to a medium conveyance direction in which the medium is conveyed. The pick sensor is disposed between the first sensor and the second sensor in the direction orthogonal to the medium conveyance direction. When one of the first skew sensor and the second skew sensor detects the medium, the control unit starts correcting a skew of the medium. When a predetermined time has elapsed after the pick sensor detects the medium, the control unit stops correcting the skew of the medium.

According to a seventeen aspect, a media conveying apparatus includes a roller, a first sensor, a second sensor, a pick sensor, and a control unit. The roller conveys a medium. The first sensor and the second sensor are spaced apart in a direction orthogonal to a medium conveyance direction in which the medium is conveyed. The pick sensor is disposed between the first sensor and the second sensor in the direction orthogonal to the medium conveyance direction. When one of the first skew sensor and the second skew sensor detects the medium, the control unit starts correcting a skew of the medium. When the pick sensor does not detect the medium before an elapse of a predetermined time from the start of correction of the skew of the medium, the control unit stops correcting the skew of the medium.

According to an eighteenth aspect, a media conveying apparatus includes a roller, an acquisition unit, a determination unit, and a control unit. The roller conveys a medium. The acquisition unit acquires a degree of slip between the roller and the medium conveyed by the roller. The determination unit determines whether the medium is skewed. The control unit corrects a skew of the medium when the medium is skewed. The control unit prohibits correction of the skew of the medium, based on the degree of slip.

According to a nineteenth aspect, a media conveying apparatus includes a roller, a plurality of sensors, a determination unit, and a control unit. The roller conveys a medium. The skew sensors are spaced apart in a direction orthogonal to a direction in which the medium is conveyed. The determination unit determines whether the medium is skewed, based on a time when each of the skew sensors detects a leading end of the medium. The control unit corrects a skew of the medium when the medium is skewed. The control unit prohibits correction of a skew of a medium to be conveyed, based on a time when each of the skew sensors detects a trailing end of the medium of which the skew is corrected.

According to a twelfth aspect, the media conveying apparatus of the nineteenth aspect further includes a receptacle. When the control unit stops correcting the skew of the medium, the control unit does not restart correcting the skew of the medium until conveyance of all media placed on the receptacle is completed.

According to a twenty-first aspect, the media conveying apparatus of the nineteenth aspect further includes a separation roller and a rotation sensor. The separation roller faces the roller. The rotation sensor detects the rotation of the separation roller. When the control unit stops correcting the skew of the medium, the control unit does not restart correcting the skew of the medium until the rotation sensor detects the separation roller rotating in accordance with the rotation of the roller.

According to one or more aspects of the present disclosure, the skew of media can be corrected more easily and appropriately with the media conveying apparatus, the media conveying method, and the control program described above.

The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and/or features of different illustrative embodiments may be combined with each other and/or substituted for each other within the scope of the present invention.

Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.

The functionality of the elements disclosed herein may be implemented using circuitry or processing circuitry which includes general purpose processors, special purpose processors, integrated circuits, application specific integrated circuits (ASICs), digital signal processors (DSPs), field programmable gate arrays (FPGAs), conventional circuitry and/or combinations thereof which are configured or programmed to perform the disclosed functionality. Processors are considered processing circuitry or circuitry as they include transistors and other circuitry therein. In the disclosure, the circuitry, units, or means are hardware that carry out or are programmed to perform the recited functionality. The hardware may be any hardware disclosed herein or otherwise known which is programmed or configured to carry out the recited functionality. When the hardware is a processor which may be considered a type of circuitry, the circuitry, means, or units are a combination of hardware and software, the software being used to configure the hardware and/or processor.

MEDIA CONVEYING APPARATUS, MEDIA CONVEYING METHOD, AND NON-TRANSITORY RECORDING MEDIUM

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CPC

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Priority Claims (1)