DOCUMENT FEEDING DEVICE AND IMAGE FORMING DEVICE INCLUDING THE SAME

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Application JP2023-208382, the content to which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION
1. Field of the Invention

The disclosure relates to a document feeding device that conveys a document along a curved conveyance path and an image forming device including the document feeding device.

2. Description of the Related Art

In general, an image forming device such as a copying machine, a facsimile machine, a printer, or a multifunction peripheral includes a document feeding device that conveys a document and reads a front surface and a back surface of the document. The document feeding device conveys one or a plurality of documents placed on a document placement tray one by one and reads each document at a reader in the middle of the conveyance. By reading the document, image data of an image or the like formed on the read document is generated.

In this way, in the image forming device, copying, facsimile transmission, scanning, and the like are sequentially performed on the one or a plurality of documents. However, the document feeding device has a problem in that conveyance of a document becomes unstable during the conveyance, which causes a trouble such as the document being conveyed in an inclined state or the occurrence of a conveyance jam. In particular, a document feeding device including a curved conveyance path has a problem in that such troubles easily occur.

Thus, various techniques for preventing such troubles have been proposed. For example, a related-art sheet conveying device has a configuration in which a guide member is provided in a sheet conveyance path, and when both end portions of the guide member are screwed to a frame of the device, an intermediate portion of the guide member is forcibly deformed in a direction opposite to a sheet path surface by a stress generated when the screws are tightened, thereby guiding a sheet to a curved sheet conveyance path disposed between a supply tray and a discharge tray. According to the related-art sheet conveying device, when both end portions of the guide member are screwed to the frame of the device, the intermediate portion of the guide member is forcibly deformed in the direction opposite to the sheet path surface by the stress generated when the screws are tightened. This can prevent an upstream end portion of the guide from protruding and prevent a sheet jam in the sheet conveyance path.

SUMMARY

As described above, there have been proposed various document feeding devices (sheet conveying devices) for preventing a trouble such as a document (sheet) being fed in an inclined state or the occurrence of a conveyance jam when a document is fed in an image forming device. However, a document feeding device capable of conveying a document (sheet) more stably is demanded.

The disclosure has been made in view of the above-described circumstances, and an object thereof is to provide a document feeding device capable of stably conveying a document while suppressing a conveyance abnormality, and an image forming device including the document feeding device.

A document feeding device according to an aspect of the disclosure is a document feeding device including a document conveyance path that conveys a document to a document reading position where an image is read, the document conveyance path including a curved conveyance path, a sheet feeding roller that feeds the document to the curved conveyance path, and a large-diameter conveying roller disposed on an inner side of the curved conveyance path, the large-diameter conveying roller having a diameter larger than a diameter of the sheet feeding roller, wherein a document conveyance speed of the large-diameter conveying roller is higher than a document conveyance speed of the sheet feeding roller.

Thus, it is possible to keep a sufficient inter-sheet distance during the document conveyance and to stably convey the document. Thus, it is possible to suppress a trouble such as the document being conveyed in an inclined state or the occurrence of a conveyance jam, to make it difficult for a conveyance abnormality to occur, and to stably convey the document.

The above-described document feeding device may further include a single driven roller that is in pressure contact with the large-diameter conveying roller and is driven to rotate, wherein the document reading position may be disposed downstream of the large-diameter conveying roller, and the driven roller may be disposed between the sheet feeding roller disposed upstream of the large-diameter conveying roller and the document reading position in the document conveyance path, the driven roller being disposed closer to the document reading position than to the sheet feeding roller.

In this way, since the driven roller is disposed closer to the document reading position between the sheet feeding roller and the document reading position in the document conveyance path, it is possible to make is difficult for a document conveyance abnormality to occur and to stably convey the document.

This allows the document to be stably conveyed with a simple configuration without increase in the number of components. Thus, the manufacturing cost can be suppressed.

In the above-described document feeding device, each of the sheet feeding roller, the large-diameter conveying roller, and the sheet discharge roller may be coupled to the motor via a transmission mechanism including a gear.

This allows the document to be stably conveyed with a simple configuration without increase in the number of components. Thus, the manufacturing cost can be suppressed.

In the above-described document feeding device, in the document conveyance path, no conveying roller other than the large-diameter conveying roller may be disposed between the sheet feeding roller and the driven roller.

This allows the document to be stably conveyed with a simple configuration without increase in the number of components. Thus, the manufacturing cost can be suppressed.

In the above-described document feeding device, the driven roller may be disposed below a horizontal plane including a rotation axis of the large-diameter conveying roller. Since the driven roller is disposed below the horizontal plane including the rotation axis of the large-diameter conveying roller in this way, it is possible to make it difficult for a conveyance abnormality to occur and to stably convey the document.

The above-described document feeding device may further include a sheet discharge roller disposed downstream of the large-diameter conveying roller, the sheet discharge roller discharging the document read at the document reading position to an outside, wherein the document reading position may include a first document reading position and a second document reading position, the first document reading position being a position where one surface of the document is read, the second document reading position being a position where the other surface of the document is read, the second document reading position being located downstream of the first document reading position in the document conveyance path, and the second document reading position may be closer to the sheet discharge roller than to the first document reading position.

Thus, it is possible to stably convey the document and to smoothly read the document.

In the above-described document feeding device, during a document feeding operation, the motor does not stop except when an error occurs.

This facilitates the control of the motor and thus can reduce the burden on the overall control.

This can further simplify the configuration, reduce the number of components, and suppress the manufacturing cost.

An image forming device according to an aspect of the disclosure includes the above-described document feeding device. Thus, in the document feeding device, it is possible to keep a sufficient inter-sheet distance during the document conveyance and to stably convey the document. Thus, it is possible to suppress a trouble such as the document being conveyed in an inclined state or the occurrence of a conveyance jam, to make it difficult for a conveyance abnormality to occur, and to stably convey the document. Thus, the image can be stably formed.

According to the disclosure, it is possible to provide a document feeding device capable of stably conveying a document without occurrence of a conveyance abnormality, and an image forming device including the document feeding device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view illustrating a schematic configuration of an image forming device according to an embodiment of the disclosure in a see-through manner.

FIG. 2 is a front view illustrating a schematic configuration of a document feeding device according to the embodiment of the disclosure in a see-through manner.

FIG. 3 is a perspective view illustrating a schematic internal configuration of the document feeding device according to the embodiment of the disclosure.

FIG. 4 is an enlarged perspective view illustrating a schematic configuration of arrangement of gears for driving respective rollers of the document feeding device according to the embodiment of the disclosure.

FIG. 5 is a first state diagram illustrating a document conveyance operation of the document feeding device according to the embodiment of the disclosure.

FIG. 6 is a second state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure.

FIG. 7 is a third state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure.

FIG. 8 is a fourth state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure.

FIG. 9 is a fifth state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments according to the disclosure will be described with reference to the drawings.

First Embodiment

An image forming device according to a first embodiment of the disclosure will be described with reference to the accompanying drawings. FIG. 1 is a front view illustrating a schematic configuration of the image forming device according to the first embodiment of the disclosure in a see-through manner.

In the coordinates depicted in the following drawings, an X-axis direction indicates a left-right direction (lateral direction) when an image forming device 100 is viewed from the front, and an X-axis positive direction and an X-axis negative direction indicate a left side and a right side, respectively. A Y-axis direction indicates a depth direction (front-rear direction) orthogonal to the X-axis extending in the left-right direction, and a Y-axis positive direction and a Y-axis negative direction indicate an operation side (front side) and a rear side opposite to the operation side, respectively. A Z-axis direction indicates an up-down direction, that is, a vertical direction, and a Z-axis positive direction and a Z-axis negative direction indicate an upper side and a lower side, respectively. Note that when the image forming device 100 is not illustrated and only the constituent members of the image forming device 100 are illustrated, the coordinates in a state where the constituent members are incorporated in the image forming device 100 are illustrated.

The image forming device 100 is a multifunction peripheral having a copy function, a scanner function, a facsimile function, and a printer function, and includes an image reading device 102 and an image forming device body 101.

The image reading device 102 includes a reader 130 and a document feeding device 160 (automatic document feeding device (ADF)). The document feeding device 160 is provided above the reader 130 and supported in an openable and closable manner with respect to the reader 130.

The document feeding device 160 sequentially conveys one or a plurality of documents G one by one. The image reading device 102 reads the one or plurality of documents G conveyed one by one by the document feeding device 160.

The reader 130 includes a document table 130a on which each document G is placed and a scanning optical system 131 including a first document reader 132a. The scanning optical system 131 reads the document G.

The image reading device 102 has a placed document reading function of reading the document G placed on the document table 130a. In the image forming device 100, when the document feeding device 160 is opened, the document table 130a above the reader 130 is exposed and the document G can be manually placed on the document table 130a. The reader 130 reads the document placed on the document table 130a by scanning operation of the scanning optical system 131.

The document feeding device 160 also includes a document discharge tray 162 on which the documents G discharged to the outside are stacked, a document pickup roller 22 that pulls out the documents G stacked on a document placement tray 161 one by one, a document feeding roller 21 that conveys each document G pulled out by the document pickup roller 22, large-diameter conveying rollers 24 that conveys the document G conveyed by the document feeding roller 21, driven rollers 25 disposed so as to face the large-diameter conveying rollers 24 in a pressure contact manner, a second document reader 132b that reads a back surface (other surface) of the conveyed document G, and a pair of document discharge rollers 26 for discharging the document G to the document discharge tray 162.

Note that although the document feeding device 160 will be described in detail below, the document feeding device 160 includes a document conveyance path L (see FIG. 2) along which the document G is conveyed, a part of the document conveyance path L is a curved conveyance path La (see FIG. 2) curved in a U shape, and the curved conveyance path La is included in the document conveyance path L. In the document conveyance path L, there are a first document reading position A1 where a front surface (one surface) of the document G is read, and a second document reading position A2 where a back surface of the document G is read.

The image reading device 102 has a conveyed document reading function of reading the document G conveyed by the document feeding device 160. The document feeding device 160 conveys the document G placed on a document placement tray 161 to the first document reading position A1 where the first document reader 132a is disposed and the second document reading position A2 where the second document reader 132b is disposed. Thus, when the document G is conveyed along the document conveyance path L in the document feeding device 160, the front surface of the document G is read by the first document reader 132a at the first document reading position A1, and the back surface of the document G is read by the second document reader 132b at the second document reading position A2. The document G is conveyed along the document conveyance path L and then discharged to the document discharge tray 162 at the outside.

The image forming device body 101 includes an image transferrer 50, an optical scanning device 1, an intermediate transfer belt device 70, a secondary transfer device 11, a fixing device 12, a sheet conveyance path S, a sheet feeding cassette 18, and a sheet discharge tray 141.

The image forming device 100 handles image data corresponding to a color image composed of the colors black (K), cyan (C), magenta (M), and yellow (Y), or a monochrome image composed of a single color (black, for example).

The image transferrer 50 of the image forming device 100 includes four image stations Pa, Pb, Pc, and Pd corresponding to individual colors of black, cyan, magenta, and yellow. Each of the image stations Pa, Pb, Pc, and Pd includes a development device 2, a photoreceptor drum 3, a drum cleaning device 4, and a charger 5, whereby four types of toner images are formed by the image stations Pa, Pb, Pc, and Pd. That is, the image forming device 100 is provided with four sets of the development device 2, photoreceptor drum 3, drum cleaning device 4, and charger 5, and respective sets correspond to black, cyan, magenta, and yellow.

The optical scanning device 1 exposes the front surface of the photoreceptor drum 3 to form an electrostatic latent image. The development device 2 develops the electrostatic latent image on the front surface of the photoreceptor drum 3 to form a toner image on the front surface of the photoreceptor drum 3. The drum cleaning device 4 removes and collects residual toner on the front surface of the photoreceptor drum 3. The charger 5 uniformly charges the front surface of the photoreceptor drum 3 to a predetermined potential. With this series of operations, the toner image of each color is formed on the front surface of a corresponding photoreceptor drum 3.

The intermediate transfer belt device 70 includes intermediate transfer rollers 6, an endless intermediate transfer belt 71, an intermediate transfer driving roller 72, an intermediate transfer driven roller 73, and a cleaning device 9. The intermediate transfer belt 71 is an endless belt capable of moving in a circumvolution manner, and is wound around the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. That is, the intermediate transfer belt 71 is stretched over the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. Four intermediate transfer rollers 6 are provided on an inner side of the intermediate transfer belt 71 to form four types of toner images corresponding to the individual colors. The intermediate transfer rollers 6 transfer the toner images of the individual colors formed on the front surfaces of the photoreceptor drums 3 onto the intermediate transfer belt 71.

In the image forming device 100, the toner images of the individual colors formed on the front surfaces of the respective photoreceptor drums 3 are sequentially transferred and superimposed to form a color toner image on the surface of the intermediate transfer belt 71 stretched over the intermediate transfer driving roller 72 and the intermediate transfer driven roller 73. The toner image formed on the intermediate transfer belt 71 is transferred onto a sheet P in the secondary transfer device 11. Part of the toner image formed on the intermediate transfer belt 71 is not transferred onto the sheet P and remains on the surface of the intermediate transfer belt 71 as waste toner. The waste toner is removed and collected by the cleaning device 9.

The secondary transfer device 11 forms a transfer nip region TN between a secondary transfer roller 11a and the intermediate transfer belt 71, and conveys the sheet P having been conveyed through the sheet conveyance path S while nipping the sheet P in the transfer nip region TN. When the sheet P passes through the transfer nip region TN, the toner image on the surface of the intermediate transfer belt 71 is transferred onto the sheet P, and the sheet P is conveyed to the fixing device 12.

The fixing device 12 includes a fixing roller 31 and a pressure roller 32 that sandwich the sheet P and rotate. In the fixing device 12, the sheet P with the transferred toner image is nipped between the fixing roller 31 and the pressure roller 32 and subject to heat and pressure to fix the toner image onto the sheet P. Although not illustrated, a heater as a heat source is disposed inside the fixing roller 31, whereby the surface of the fixing roller 31 in contact with the sheet P with the transferred toner image is heated by the heat generated by the heater.

The sheet feeding cassette 18 is a cassette for storing the sheets P to be used for image formation, and is provided below the optical scanning device 1. Each sheet P is pulled out from the sheet feeding cassette 18 by pickup rollers 16 and conveyed to the sheet conveyance path S. The sheet P conveyed to the sheet conveyance path S is conveyed to discharge rollers 17 via the secondary transfer device 11 and the fixing device 12, and is discharged to the sheet discharge tray 141 at a discharge portion 140. Conveying rollers 13, registration rollers 14, and the discharge rollers 17 are disposed along the sheet conveyance path S. The conveying rollers 13 assist the conveyance of the sheet P. The registration rollers 14 temporarily stop the sheet P and align the leading end of the sheet P. Further, the registration rollers 14 convey the temporarily stopped sheet P in synchronization with the timing of a color toner image on the intermediate transfer belt 71. The color toner image on the intermediate transfer belt 71 is transferred onto the sheet P in the transfer nip region TN between the intermediate transfer belt 71 and the secondary transfer roller 11a.

Note that while FIG. 1 illustrates a configuration in which the single sheet feeding cassette 18 is provided; however, no such limitation is intended. A configuration in which a plurality of sheet feeding cassettes 18 are provided may be used, and different sheet feeding cassettes 18 may be loaded with different types of sheets P.

When the image forming device 100 forms an image on both the front surface and the back surface of the sheet P, the sheet P is conveyed in the reverse direction from the discharge rollers 17 to a sheet reverse path Sr. The image forming device 100 inverts the front and back of the sheet P conveyed in the reverse direction and guides the sheet P again to the registration rollers 14. The image forming device 100 forms an image on the back surface of the sheet P guided to the registration rollers 14 in a similar manner to when forming an image on the front surface, and discharges the sheet P to the sheet discharge tray 141.

Next, the configuration of the document feeding device 160 will be described in detail with reference to the drawings. FIG. 2 is a front view illustrating a schematic configuration of the document feeding device according to the embodiment of the disclosure in a see-through manner. FIG. 3 is a perspective view illustrating a schematic internal configuration of the document feeding device according to the embodiment of the disclosure. FIG. 4 is an enlarged perspective view illustrating a schematic configuration of arrangement of gears for driving respective rollers of the document feeding device according to the embodiment of the disclosure.

Note that FIG. 3 is a view illustrating a state in which an upper cover of the document feeding device 160 is removed and the conveyance path of the document G is exposed. FIG. 4 is an enlarged view illustrating a state in which the upper cover of the document feeding device 160 is removed and first to fourth gears H1 to H4 are exposed. Further, in FIG. 4, members such as a motor 27 are not illustrated so that the arrangement of the first to fourth gears H1 to H4 can be easily seen.

The document feeding device 160 has been described above and will be described in more detail. As illustrated in FIG. 2, the document feeding device 160 includes the document pickup roller 22, the document feeding roller 21, a second belt B2 stretched over the document feeding roller 21 and the document pickup roller 22 to couple and rotate these rollers together, a separation pad 23 disposed close to the document feeding roller 21 so as to face the document feeding roller 21, the large-diameter conveying rollers 24, the driven rollers 25 disposed close to the large-diameter conveying rollers 24 so as to face the large-diameter conveying rollers 24, the second document reader 132b for reading the back surface of the document G, and the pair of document discharge rollers 26 for discharging the document G to the outside. The pair of document discharge rollers 26 face each other in a pressure contact manner. Further, the document feeding device 160 includes the document conveyance path L along which the document G is conveyed. Specifically, the document G is discharged from the document placement tray 161 to the document discharge tray 162 via the document pickup roller 22, the document feeding roller 21, the large-diameter conveying rollers 24 (driven rollers 25), and the document discharge rollers 26 in order. Note that as illustrated in FIGS. 3 and 4, two large-diameter conveying rollers 24 are provided, and the respective driven rollers 25 are disposed at the large-diameter conveying rollers 24.

Here, each large-diameter conveying roller 24 has a diameter of, for example, 28 mm, and the document feeding roller 21 has a diameter of, for example, 14 mm. The diameter of the large-diameter conveying roller 24 is larger than that of the document feeding roller 21. The diameter of each driven roller 25 is, for example, 8 mm, and the diameter of the large-diameter conveying roller 24 is larger than that of the driven roller 25. The conveyance speed of the document G by the large-diameter conveying roller 24 is, for example, 208 mm/second, and the conveyance speed of the document G by the document feeding roller 21 is, for example, 125 mm/second.

In the document conveyance path L, the document G is fed from the document feeding roller 21 to the large-diameter conveying rollers 24. Here, the document conveyance path L includes a portion curved along the outer peripheries of the large-diameter conveying rollers 24, and this curved portion is the curved conveyance path La. That is, the large-diameter conveying rollers 24 are provided on the inner side of the curved conveyance path La and are disposed along the inner periphery of the curved conveyance path La. In other words, the curved conveyance path La is a U-shaped U-turn path.

The curved conveyance path La is a part of the document conveyance path L. When the document G conveyed along the document conveyance path L passes through the curved conveyance path La, the document G sequentially passes through the first document reading position A1 and the second document reading position A2 downstream of the curved conveyance path La, and is discharged to the document discharge tray 162 by the document discharge rollers 26. Here, the first document reading position A1 is a position where the first document reader 132a (see FIG. 1) is disposed, and the front surface of the document G is read by the first document reader 132a when the document G passes through the first document reading position A1. The second document reading position A2 is a position where the second document reader 132b is disposed, and the back surface of the document G is read by the second document reader 132b when the document G passes through the second document reading position A2. Note that the second document reading position A2 is closer to the document discharge rollers 26 (the nip of the document discharge rollers 26) than to the first document reading position A1.

A process of conveying the document G in the document conveyance path L will be described. First, the document pickup roller 22 pulls out and feeds the documents G stacked on the document placement tray 161 one by one to the document feeding roller 21. The document feeding roller 21 feeds the documents G one by one to the large-diameter conveying rollers 24. That is, the document feeding roller 21 feeds the documents G one by one to the curved conveyance path La. Note that even when a plurality of documents G are pulled out by the document pickup roller 22 and successively fed to the document feeding roller 21, feeding of the plurality of documents G at one time from the document feeding roller 21 to the large-diameter conveying rollers 24 is suppressed by providing the separation pad 23, and the documents G are fed to the large-diameter conveying roller 24 one by one.

In the curved conveyance path La, the document G is conveyed along the outer peripheries of the large-diameter conveying rollers 24. Further, at the position where the driven rollers 25 are disposed, the large-diameter conveying rollers 24 and the driven rollers 25 convey the document G in a state where the document G is sandwiched therebetween.

After passing through the curved conveyance path La, the document G passes through the first document reading position A1, further passes through the second document reading position A2, and is fed to the document discharge rollers 26. The document G is conveyed while being sandwiched between the pair of document discharge rollers 26 and is discharged to the document discharge tray 162.

The reason why the document G is conveyed along the document conveyance path L including the curved conveyance path La in this way is that the document pickup roller 22, the document feeding roller 21, the large-diameter conveying rollers 24, and the document discharge rollers 26 are rotationally driven. The document pickup roller 22, the document feeding roller 21, the large-diameter conveying rollers 24, and the document discharge rollers 26 are rotated by the same power source (single drive motor). Specifically, as illustrated in FIG. 3, the document feeding device 160 includes the motor 27. The motor 27 is operated and thus its power is transmitted to the document pickup roller 22, the document feeding roller 21, the large-diameter conveying rollers 24, and the document discharge rollers 26 via a transmission mechanism including a plurality of gears, so that these rollers are rotationally driven.

Note that the power from the motor 27 is transmitted to one roller disposed on the upper side in the document discharge rollers 26, this roller is rotationally driven, and the other roller disposed on the lower side is rotated (driven to rotate) by the rotational driving of the one roller. The driven rollers 25 are also rotated (driven to rotate) by the rotational driving of the large-diameter conveying rollers 24.

Specifically, as illustrated in FIG. 4, the document feeding device 160 includes the first gear H1, the second gear H2, the third gear H3, a gear H3a provided at the same rotary shaft as the third gear H3, and the fourth gear H4. As illustrated in FIG. 3, the document feeding device 160 also includes a fifth gear H5 and a sixth gear H6. The document feeding device 160 further includes a first belt B1 stretched over the fifth gear H5 and the sixth gear H6, and the above second belt B2 stretched over the document feeding roller 21 and the document pickup roller 22.

The first gear H1 meshes with a gear (not illustrated) provided at a rotary shaft of the motor 27, and the first gear H1 is rotationally driven by the rotational driving of the motor 27.

The second gear H2 is provided at a rotary shaft of the large-diameter conveying rollers 24. The second gear H2 meshes with a gear (not illustrated) provided at a rotary shaft of the first gear H1 and is rotationally driven by the rotational driving of the first gear H1. Note that when the second gear H2 is rotationally driven, the large-diameter conveying rollers 24 are also rotationally driven. Note that, as described above, when the large-diameter conveying rollers 24 are rotationally driven, the driven rollers 25 are also rotationally driven.

The third gear H3 meshes with a gear (not illustrated) provided at the rotary shaft of the first gear H1 and is rotationally driven by the rotational driving of the first gear H1.

The fourth gear H4 is provided at a rotary shaft of the document feeding roller 21. The fourth gear H4 meshes with the gear H3a provided at a rotary shaft of the third gear H3 and is rotationally driven by the rotational driving of the third gear H3. Note that when the fourth gear H4 is rotationally driven, the document feeding roller 21 is also rotationally driven.

Since the second belt B2 is stretched over the document feeding roller 21 and the document pickup roller 22, the rotational driving of the document feeding roller 21 causes the second belt B2 to transmit the power to the document pickup roller 22 and rotationally drives the document pickup roller 22.

The fifth gear H5 is provided at the rotary shaft of the large-diameter conveying rollers 24, and when the large-diameter conveying rollers 24 are rotationally driven, the fifth gear H5 is rotationally driven.

The sixth gear H6 is provided at a rotary shaft of the upper roller of the document discharge rollers 26. When the sixth gear H6 is rotationally driven, the document discharge rollers 26 are rotationally driven.

The first belt B1 is stretched over the fifth gear H5 and the sixth gear H6, and thus when the large-diameter conveying rollers 24 are rotationally driven, the fifth gear H5 is rotationally driven, the power is transmitted to the sixth gear H6 via the first belt B1, and the sixth gear H6 is rotationally driven. Thus, the document discharge rollers 26 are rotationally driven.

In this way, by the rotational driving of the single motor 27, the document pickup roller 22, the document feeding roller 21, the large-diameter conveying rollers 24, and the document discharge rollers 26 are rotationally driven. Note that the rotation speeds of the respective rollers do not need to be the same, and the rotation speeds of the respective rollers are adjusted by the configurations or the like of the respective gears (for example, a gear ratio or the like). Thus, the document feeding device 160 does not need to be provided with a device for switching on and off drive connection, such as a clutch solenoid, and it is possible to adjust the conveyance speed of each roller as described above. In addition, the rotation of the motor 27 is not stopped during the operation of conveying the document G except when an error occurs. This facilitates the control. This can further decrease the number of components and suppress the manufacturing cost.

Here, the rotation speeds of the document feeding roller 21 and the large-diameter conveying rollers 24 are adjusted so that the conveyance speed of the document G by the document feeding roller 21 is lower than the conveyance speed of the document G by the large-diameter conveying rollers 24. That is, the conveyance speed of the large-diameter conveying roller 24 is higher than the conveyance speed of the document feeding roller 21. Thus, when the plurality of documents G are fed, the documents G can have a sufficient inter-sheet distance therebetween. Moreover, the conveyance is assisted by the large-diameter conveying rollers 24 in the curved conveyance path La, and thus when the document G is conveyed in the document conveyance path L, it is possible to suppress a conveyance trouble such as the document being conveyed in an inclined state or the occurrence of a conveyance jam.

Note that, because there is a sufficient inter-sheet distance, it is possible to stop the document conveyance operation without waste when the document conveyance operation needs to be stopped halfway, for example, when the documents G to be supplied runs short during the document conveyance operation in the document feeding device 160.

The driven rollers 25 are disposed between the document feeding roller 21 disposed upstream of the large-diameter conveying rollers 24 and the first document reading position A1 disposed downstream of the large-diameter conveying rollers 24 in the document conveyance path L, the driven rollers 25 being closer to the first document reading position A1 than to the document feeding roller 21. As a result, when the documents G are continuously conveyed, it is possible to keep a sufficient inter-sheet distance between a first document G and a second document G. Here, since the driven rollers 25 are disposed closer to the first document reading position A1 than to the document feeding roller 21, the document G is conveyed by the document feeding roller 21 until the leading end of the document G enters the nip between the large-diameter conveying rollers 24 and the driven rollers 25, so that the document G is unstably conveyed. However, since the large-diameter conveying rollers 24 having a relatively large diameter are disposed, a rotational operation of the large-diameter conveying rollers 24 (by the conveyance guide forming the document conveyance path and the large-diameter conveying rollers 24) reduces a resistance when the document passes through the curved conveyance path La. Thus, when the document G is conveyed in the document conveyance path L, it is possible to suppress a conveyance trouble such as the document being conveyed in an inclined state or the occurrence of a conveyance jam.

Further, in the document conveyance path L of the document feeding device 160, no roller for conveying the document G other than the large-diameter conveying rollers 24 is disposed between the document feeding roller 21 and the driven rollers 25. This can decrease the number of components and suppress the manufacturing cost. Since the large-diameter conveying rollers 24 are provided, the document G can be stably conveyed even in such a configuration.

In addition, a roller for conveying the document G is preferably not disposed between the driven rollers 25 and the document discharge rollers 26 in the document conveyance path L of the document feeding device 160. This can decrease the number of components and suppress the manufacturing cost.

The configuration of the image forming device 100 according to the present embodiment has been described above. Next, an operation of conveying the document G in the document conveyance path L in the document feeding device 160 of the image forming device 100 will be described with reference to the drawings.

FIG. 5 is a first state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure. FIG. 6 is a second state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure. FIG. 7 is a third state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure. FIG. 8 is a fourth state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure. FIG. 9 is a fifth state diagram illustrating the document conveyance operation of the document feeding device according to the embodiment of the disclosure.

FIGS. 5 to 9 sequentially illustrate an operation in which two documents G (document G1 and document G2) stacked on the document placement tray 161 are conveyed along the document conveyance path L and discharged to the outside by the document discharge rollers 26.

First, as illustrated in FIG. 5, the documents G1 and G2 are stacked on the document placement tray 161. Note that, in this state, the document G1 is placed on the document G2, and the document feeding device 160 is operated from this state. Note that the document pickup roller 22 is normally located above the position illustrated in FIG. 5 and is lowered to contact the document G1 in order to perform the conveyance operation. That is, when the document feeding device 160 is operated by, for example, turning on a copy execution key, the document pickup roller 22 is lowered.

When the motor 27 is rotationally driven and its power is transmitted to the document pickup roller 22, the document pickup roller 22 is rotationally driven, and the document G1 is pulled out from the document placement tray 161 as illustrated in FIG. 6. Note that not only the document pickup roller 22 but also the document feeding roller 21, the large-diameter conveying rollers 24, and the document discharge rollers 26 are rotationally driven by the rotational driving of the motor 27.

The document G1 pulled out from the document placement tray 161 by the document pickup roller 22 is fed to the document feeding roller 21 and is further fed to the large-diameter conveying rollers 24 by the document feeding roller 21. At this time, the document G1 is conveyed along the curved conveyance path La. Note that the document G1 is conveyed by the document feeding roller 21 until the leading end of the document G1 reaches the position of the driven rollers 25, its conveyance speed is the conveyance speed of the document feeding roller 21, and the document G1 is conveyed at a conveyance speed of, for example, 125 mm/second. At this time, due to the rotation operation of the large-diameter conveying roller 24 the document G1 is stably conveyed.

As illustrated in FIG. 7, when the document G1 conveyed along the curved conveyance path La reaches the position of the driven rollers 25, the document G1 is sandwiched between and conveyed by the large-diameter conveying rollers 24 and the driven rollers 25. Thus, the document G1 is conveyed at the conveyance speed of the large-diameter conveying rollers 24, and the document G1 is conveyed at a conveyance speed of, for example, 208 mm/second. That is, the conveyance speed increases.

As illustrated in FIG. 8, the document G1 is conveyed by the large-diameter conveying rollers 24 and the driven rollers 25 and passes through the first document reading position A1 and the second document reading position A2 in the document conveyance path L. At this time, the front surface of the document G1 is read by the first document reader 132a (see FIG. 1). Further, the back surface of the document G1 is read by the second document reader 132b.

The document G2 pulled out from the document placement tray 161 by the document pickup roller 22 is also fed to the document feeding roller 21. Note that, as described above, the conveyance speed of the large-diameter conveying rollers 24 is higher than the conveyance speed of the document feeding roller 21, and thus, in this state, the conveyance speed of the document G1 is higher than the conveyance speed of the document G2, the document G1 and the document G2 has a sufficient inter-sheet distance therebetween, and the documents are stably conveyed.

As illustrated in FIG. 9, the document G1 is fed to the document discharge rollers 26 and conveyed by the document discharge rollers 26. Afterwards, the document G1 is discharged to the outside (document discharge tray 162).

In a manner similar to the document G1, the document G2 pulled out from the document placement tray 161 by the document pickup roller 22 is fed to the document feeding roller 21, further fed to the large-diameter conveying rollers 24 by the document feeding roller 21, and conveyed along the curved conveyance path La. Note that, in this case, the document G2 is conveyed by the document feeding roller 21, and the conveyance speed is that of the document feeding roller 21. Further, when reaching the position of the driven rollers 25, the document G2 is sandwiched between and conveyed by the large-diameter conveying rollers 24 and the driven rollers 25. Note that, in this case, the document G2 is conveyed by the large-diameter conveying rollers 24, and the conveyance speed is that of the large-diameter conveying rollers 24. Although not illustrated, the document G2 is also conveyed and discharged to the outside by the document discharge rollers 26 in a manner similar to the document G1. Note that although a state in which the two documents G are stacked on the document placement tray 161 has been described, the conveyance operation is similarly performed even when the number of stacked documents G is other than two. Note that, in the state illustrated in FIG. 9, the inter-sheet distance between the document G1 and the document G2 is, for example, 80 mm.

The image forming device 100 and the document feeding device 160 according to the present embodiment have been described above. As described above, according to the document feeding device 160, the conveyance speed of the document G by the large-diameter conveying rollers 24 is higher than the conveyance speed of the document G by the document feeding roller 21, and thus it is possible to keep a sufficient inter-sheet distance between the documents G. In addition, the large-diameter conveying rollers 24 having the outer periphery along the inner periphery of the curved conveyance path La is disposed on the inner side of the curved conveyance path La, which can suppress unstable conveyance of the document G in the document conveyance path L and suppress a trouble such as the document being fed in an inclined manner or the occurrence of a conveyance jam.

Other Embodiments

In the above-described embodiment, the document feeding device 160 includes the two large-diameter conveying rollers 24, but may include one large-diameter conveying roller 24. For example, the large-diameter conveying roller 24 may have a shape extending in the axial direction so as to stably convey the document G.

According to the document feeding device 160 and the image forming device 100 including the document feeding device 160 described above, it is possible to keep an inter-sheet distance between the conveyed documents G with an inexpensive configuration, and it is also possible to reduce a resistance during the conveyance in the curved conveyance path La and to stably convey the document G by the rotation operation of the large-diameter conveying rollers 24. As a result, it is possible to suppress a trouble regarding conveyance of the document G, such as the document being fed in an inclined manner or the occurrence of a conveyance jam. Further, since the number of components is small and a simple configuration can be achieved, the manufacturing cost can be suppressed.

The disclosure is not limited to the embodiments described above and can be implemented in various other forms. Thus, the above embodiments are merely examples in all respects and should not be interpreted as limiting. The scope of the disclosure is indicated by the claims and is not limited to the description. Furthermore, all modifications and changes equivalent in scope with the claims are included in the scope of the disclosure.

DOCUMENT FEEDING DEVICE AND IMAGE FORMING DEVICE INCLUDING THE SAME

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