Patent Grant
8205878
This patent application claims priority under 35 U.S.C. §119 upon Japanese patent application, No. 2006-204797 filed in the Japan Patent Office on Jul. 27, 2006, the entire contents of which are incorporated by reference herein.
1. Field of Invention
Exemplary aspects of the present invention relate to an apparatus for image forming, and more particularly, to a multifunctional image forming apparatus having at least two functions amongst the following, a printer, a digital copier, and a facsimile.
2. Description of the Related Art
Image forming apparatus such as printers, digital copiers, facsimiles and multifunctional peripherals (capable of serving at least two of the following functions, printer, copier and facsimile), generally include a sheet feeding device, a sheet conveyance device and an image output unit. The sheet feeding device feeds a transfer sheet to a sheet conveyance path. The sheet conveyance device conveys the transfer sheet along the sheet conveyance path. The image output unit outputs an image on the transfer sheet. The sheet conveyance path of the sheet conveyance device includes a plurality of conveyance rollers thereon. The conveyance rollers are rotationally driven by drive sources such as motors to convey the transfer sheet.
Such image forming apparatuses can register the sheet position and image position in a direction (hereafter referred to as a side direction) perpendicular to a sheet conveyance direction. The sheet position in the side direction needs to be corrected at an upstream side from a position in which the image is output on the transfer sheet so that the image can be formed on an accurate position of the transfer sheet in the side direction. This correction of position is hereinafter referred to as a side registration adjustment, which will be described with reference to
The related art image forming apparatus includes a contact image sensor 210, a control unit 230, a shift unit 250, a pinion gear 280, a shift motor 290, and an eccentricity cam 300. The shift unit 250 includes a driving motor 320, a side plate 330, rotation axis 340, registration rollers 180, a spring 310, and a registration roller gear 270. As shown in
The side plate 330 is movably installed in the related art image forming apparatus so as to move in the side direction by a bias applied by the spring 310. For example, the spring 310 applies a bias towards an apparatus frame 260 (i.e., a direction XX2). The side plate 330 is held at a position where the side plate 330 contacts the eccentricity cam 300 that is rotated by the shift motor 290. Therefore, the side plate 330 moves in the directions XX1 and XX2 when the eccentricity cam 300 is rotated. The registration rollers 180 and the driving motor 320 also move in the directions XX1 and XX2 when the eccentricity cam 300 is rotated. The control unit 230 controls the driving of the driving motor 320 and the shift motor 290.
The registration rollers 180 register a transfer sheet 200 conveyed in a direction YY, indicated by an arrow in
One example attempts to control the movement distance of a transfer sheet by using a memory mechanism. The movement distance of the transfer sheet determined by a shift unit and information on the transfer sheet such as thickness, quality and type are correlated and stored in the memory mechanism beforehand. Thereby, the movement distance of the transfer sheet is controlled based on the information stored in the memory mechanism.
However, when the transfer sheet is shifted in the side direction in a relatively large amount, the movement distance of the transfer sheet increases. In a successive printing operation, the shift unit moving to move the transfer sheet in the side direction has to return to an initial position before a next transfer sheet is conveyed thereto. In other words, when the movement distance is relatively large, the movement speed of the shift unit needs to be increased by using a high power motor. However, such a high power motor is costly.
In attempting to solve such a cost problem, a technique in that the side position of a transfer sheet is adjusted by adjusting the position of a sheet feeding unit is proposed. However, it is difficult to adjust the sheet feeding unit such as a sheet feeding cassette and a sheet hopper such that a side position of the transfer sheet matches with the reference position in the side direction.
An embodiment of the present invention provides an image forming apparatus that includes: a sheet conveyance path in which a sheet is conveyed; at least one sheet feeding mechanism to supply the sheet to the sheet conveyance path; a sheet conveyance mechanism to convey the sheet in a sheet conveyance direction; a detection mechanism to detect a position of a side of the sheet parallel to the sheet conveyance direction; a movement mechanism to move the sheet in a direction perpendicular to the sheet conveyance direction; a memory to store reference position information specific to the at least one sheet feeding mechanism, respectively; and a movement control mechanism to control a movement distance of the movement mechanism based on the detected position and the reference position information specific to a selected one of the at least one sheet feeding mechanism.
An embodiment of the present invention provides a method of controlling paper movement in such an image forming apparatus.
Additional features and advantages of the present invention will be more fully apparent from the following detailed description of example embodiments, the accompanying drawings and the associated claims.
A more complete appreciation of the example aspects of the invention and many of the attendant advantage thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
It will be understood that if an element or layer is referred to as being “on”, “against”, “connected to” or “coupled to” another element or layer, then it can be directly on, against, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, if an element is referred to as being “directly on”, “directly connected to” or “directly coupled to” another element or layer, then there are no intervening elements or layers present. Like numbers referred to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, term such as “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors herein interpreted accordingly.
Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, it should be understood that these elements, components, regions, layer and/or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. 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. It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
In describing example embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent 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 operate in a similar manner.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, example embodiments of the present patent invention are described.
Referring to
The tandem laser printer 1 (also referred to as the image forming apparatus 1) includes an operation panel 3 (e.g., a touch screen, or a display device and an input terminal (not depicted)), an ejection tray 4, a first sheet hopper 5, a second sheet hopper 6, a correction mechanism 9, four laser scanning units 10, four charging devices 11, four photoconductor drums 12, four development devices 13, four primary transfer rollers 14, a secondary transfer roller 15, an intermediate transfer belt 16, a fixing unit 17, a pair of registration rollers 18, a sheet conveyance path 19, a transfer sheet 20 and a contact image sensor 21. The image forming apparatus 1 includes an additional sheet feeding unit 2 connected thereto.
The operation panel 3 is a panel used as an interface by which operation of the tandem laser printer 1 can be exchanged with a user who is physically proximal thereto. The ejection tray 4 is a tray on which the transfer sheet 20 is ejected. The first and second sheet hoppers 5 and 6 store the transfer sheets 20 therein. The correction mechanism 9 corrects a position of the transfer sheet 20.
The four laser scanning units 10 emit laser beams to expose surfaces of respective photoconductor drums 12. The four charging devices 11 uniformly charge respective photoconductor drums 12. The photoconductor drums 12 form electrostatic latent images thereon by the laser beams emitted from respective laser scanning units 10. The four development devices 13 develop the electrostatic latent images on respective photoconductor drums 12 to form the toner images. The four primary transfer rollers 14 primarily transfer the toner images on respective photoconductor drums 12 onto the intermediate transfer belt 16.
The secondary transfer roller 15 secondarily transfers the toner image on the intermediate transfer belt 16 onto the transfer sheet 20. The intermediate transfer belt 16 is an intermediate transfer member on which the toner image is transferred. The fixing unit 17 fixes the toner image on the transfer sheet 20. The pair of registration rollers 18 registers the transfer sheet 20 to convey in the sheet conveyance direction.
The sheet conveyance path 19 is a path in which the transfer sheet 20 is conveyed. The transfer sheet 20 is a sheet, for example, a sheet of paper and a sheet of resin film, on which the toner image is formed. The contact image sensor 21 detects a position of the transfer sheet 20 in a side direction.
Since the image forming apparatus 1 is the tandem laser printer, four image forming units for four toner colors (black, magenta, cyan, and yellow) are disposed. Each image forming unit includes a plurality of image forming elements. For example, the image forming unit for the black color includes the laser scanning unit 10K, the charging device 11K, the photoconductor drum 12K, the development device 13K, and the primary transfer roller 14K. As the four image forming units are substantially similar to one another except for the color of the toner, one of the image forming units is explained as representative of the four image forming units as necessary. The color abbreviations K, M, C and Y for black, magenta, cyan and yellow are omitted as necessary.
As illustrated in
Upon initiation of the printing operation, the photoconductor drum 12 is rotationally driven in a direction, indicated by an arrow shown in
The four photoconductor drums 12K, 12M, 12C, and 12Y are used to form a color image. In a color image forming process, for example, toner images of black, magenta, cyan and yellow on the respective photoconductor drums 12 are transferred onto the intermediate transfer belt 16 while overlaid.
The image forming apparatus 1 includes the first sheet hopper 5 and the second sheet hopper 6 in a lower portion thereof and the additional sheet feeding unit 2 connected thereto. The additional sheet feeding unit 2 includes a third sheet hopper 7 and a fourth sheet hopper 8 storing the transfer sheet 20 therein. For example, a user uses the operation panel 3 and an input terminal (not shown) such as personal computers to select at least one of the sheet hoppers 5, 6, 7 and 8 so that the transfer sheet 20 is fed from the selected transfer hopper to the conveyance path 19.
The transfer sheet 20 is fed towards the registration rollers 18, and a leading edge thereof abuts on the registration rollers 18 being at a half. The registration rollers 18 register the transfer sheet 20 so as to feed towards a secondary transfer area including the secondary transfer roller 15 at a desired timing to the toner image on the intermediate transfer belt 16.
The secondary transfer roller 15 secondarily transfers the toner image on the intermediate transfer belt 16 onto the transfer sheet 20, and feeds the transfer sheet 20 towards the fixing device 17. The toner image on the transfer sheet 20 is fixed by the fixing device 17 and is ejected on the ejection tray 4. The surface of the intermediate transfer belt 16 is cleaned by a belt cleaner (not shown) to remove a residual toner thereon.
According to the image forming apparatus 1 of the example embodiment, the correction mechanism 9 is disposed at an upstream side in a sheet conveyance direction of the secondary transfer roller 15 so as to correct the position of the transfer sheet 20 in the side direction. This position correction of the transfer sheet 20 by the correction mechanism 9 can be referred as a side registration adjustment. The correction mechanism 9 will be explained below referring to the diagram of
The transfer sheet 20 is conveyed from the upstream side of the sheet conveyance path 19 and is sandwiched between the pair of the registration rollers 18 so as to be conveyed in a direction Y by the driving force applied by the driving motor 32. When the transfer sheet 20 is positioned in a solid line in
The transfer sheet 20 is preferably conveyed along the reference position S in the side direction. However, the transfer sheet 20 can be shifted from the reference position S due to various events such as mechanical inaccuracy of the sheet conveyance path 19, unbalanced diameter of a conveyance roller (not shown), a skid of the conveyance roller, and position inaccuracy of the sheet hoppers 5, 6, 7 and 8 in the side direction.
For example, when the transfer sheet 20 is shifted in the side direction from the reference position S caused by the position inaccuracy of one of the sheet hoppers 5, 6, 7 and 8, each transfer sheet 20 withdrawn from a given sheet hopper will be shifted by substantially the same amount. In other words, the shift of the transfer sheet 20 caused by the position inaccuracy of one of the sheet hoppers 5, 6, 7 and 8 in the side direction is unlikely to fluctuate in a short time period. Therefore, the reference position S in the side direction is determined beforehand with respect to each of the sheet hoppers 5, 6, 7 and 8, respectively, so that the movement distance ΔX can be reduced. The determination of the reference position S will be described later. The nonvolatile memory 24 stores reference position information used to determine the reference position S in the side direction. The reference position calculation mechanism 23a will be described with reference to
Referring to
The determination of the reference position S in the side direction is now explained by using an example situation as follows. An operator uses the operation panel 3 to execute a reference position setting mode when the image forming apparatus 1 is shipped from a factory and is connected to the additional sheet feeding unit 2. The reference position setting mode for the side direction will be described later with respect to the flowchart of
The operator activates the reference position setting mode for the side direction from the operation panel 3 and follows an instruction displayed on the operation panel 3 to load a specified size of the transfer sheet 20 into at least one of the sheet hoppers 5, 6, 7 and 8 to be selected (where, e.g., sheet orientation is automatically determined once the sheet 20 has been loaded into the given hopper). The operator manipulates the operation panel 3 to start the setting mode when the transfer sheet 20 is loaded. The reference position calculation mechanism 23a of the control unit 23 automatically executes subsequent processes of the setting mode which will be described below referring to the flowchart of
According to the example procedure of
Therefore, the reference position S in the side direction for one of the sheet profiles, for example, A4LEF (A4 size, long-edge-feed orientation) in the first sheet hopper 5 can be determined. The reference position S for other sheet profiles such as A5LEF, A5SEF (short-edge-feed orientation) and A3LEF in the first sheet hopper 5 can be determined by a similar manner; however, it can consume time.
The A4LEF sheet profile in the sheet hopper 5, for example, can be used as a reference outer dimension to calculate the reference positions S for other sheet profiles such as A5LEF, A5SEF and A3LEF in the sheet hopper 5 based on outer dimension differences, thereby reducing the determination time. The nonvolatile memory 24 stores, for example, the reference position information in the side direction as shown in
Therefore, each reference position S in the side direction for each profile of the transfer sheet 20 in the first, second, third and fourth sheet hoppers 5, 6, 7 and 8 is determined. In other words, the reference position S in the side direction is arranged with respect to each sheet profile in the first, second, third and fourth sheet hoppers 5, 6, 7 and 8 in the example embodiment. The determined reference position S in the side direction can fluctuate over time with variation in the sheet conveyance line due to abrasion of the conveyance roller, position shift of the sheet hopper and so forth. Thereby, the reference position S in the side direction can be updated in the course of the normal printing operation by calculating the average side position of the transfer sheet 20 prior to the side registration adjustment. The reference position S can also be updated when opening and closing the first, second, third and fourth sheet hoppers 5, 6, 7 and 8 to supply the transfer sheet 20.
Referring to
According to the example procedure of
At step S202, the control unit 23 reads the reference position information “c” of
When each transfer sheet 20 reaches the contact image sensor 21, the side direction position thereof is measured (Step S204). The movement distance (also referred to as a correction amount) of the registration rollers 18 is determined based on the side direction position and the reference position S in the side direction of the transfer sheet 20 (Step S205). Upon reaching the registration rollers 18, the transfer sheet 20 is sandwiched by the registration rollers 18 so as to be moved to the reference position S in the side direction based on the position information “c” (Step S206).
As the side edge of the transfer sheet 20, for example, the A4LEF sheet profile in the first sheet hopper 5, is conveyed along the reference position S determined beforehand, the movement distance in the side direction can be zero or relatively small. Therefore, the shift unit 25 can reduce a movement force thereof, and the side registration can be corrected without using a high torque motor for the shift motor 29.
The registration rollers 18 are returned to the initial position thereof when the transfer sheet 20 has passed therebetween (Step S207). The movement distance of the registration rollers 18 returning to the initial position is relatively small in the example embodiment, thereby applicable to a high speed sheet feeding printer. When the sheet profile and the sheet hopper are not changed (No in Step S208), flow proceeds back to step S204. When the sheet profile and the sheet hopper are changed (Yes in Step S208), flow proceeds back to step S202.
In the example embodiment, the reference position S in the side direction is arranged with respect to each sheet profile of the transfer sheet 20 in the sheet hopper. Thereby, the shift unit 25 can move easily in the course of the side registration adjustment, and can be mechanically simplified.
This state in which the reference position S is arranged with respect to each sheet profile controls a writing position in the image output unit 22. In other words, the writing position is controlled with respect to each arranged reference position S.
Referring to
The output unit 22 includes a line memory 40, a laser drive mechanism 41, a laser diode 42, a polygon mirror 43, a Fθ lens 44, a laser detection mechanism 45 and a line memory controller 46.
The line memory 40 temporarily stores the image data transmitted from an upper-level device (not shown). The line memory controller 46 controls the reading and writing of the image data from and to the line memory 40. The laser drive mechanism 41 drives the laser diode 42 to emit the laser beam based on the image data transmitted from the line memory 40. A driving mechanism (not shown) rotates the polygon mirror 43 at a constant speed. The polygon mirror 43 reflects the laser beam emitted from the laser diode 42 so that the reflected laser beam passes through the Fθ lens 44. Subsequently, the leaser beam scans the surface of the photoconductor drum 12 at a constant speed, thereby forming the electrostatic latent image on the photoconductor drum 12. The laser drive mechanism 41 emits the laser beam immediately before a direction of the laser beam passes the laser detection mechanism 45, thereby performing a laser detection.
Upon receiving the laser beam, the laser detection mechanism 45 transmits a laser detection signal to the laser drive mechanism 41 and the line memory controller 46. The laser drive mechanism 41 determines a next timing of the laser detection based on the laser detection signal as a reference, thereby executing the laser detection for every scanning. The line memory controller 46 determines a timing at which the image data is read from the line memory 40 with respect to the image position information received from the control unit 23 based on the laser detection signal as the reference.
The image position information can be considered as a distance L between a position A and a position A′ in
Since the image writing position A′ can be matched with the position information of the control unit 23, the reference position S in the side direction can be arranged with respect to each sheet profile in the selected sheet hopper.
In the example embodiment, the first, second, third, and fourth sheet hoppers 5, 6, 7 and 8 are used. However, a sheet cassette, for example, can be used as a sheet feeding mechanism. The Shift unit 25 is disposed in the vicinity of the registration rollers 18. However, the shift unit 25 can be disposed in an optional position as long as the shift unit 25 is positioned at an upstream side of the image output unit 22 on the sheet conveyance path 19.
Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the disclosure of this patent specification may be practiced otherwise than as specifically described herein.
Further, elements and/or features of different example embodiments may be combined with each other and/or substituted for each other within the scope of this disclosure and appended claims.
Still further, any one of the above-described and other example features of the present invention may be embodied in the form of an apparatus, method, system, computer program and computer program product. For example, the aforementioned methods may be embodied in the form of a system or device, including, but not limited to, any of the structure for performing the methodology illustrated in the drawings.
Even further, any of the aforementioned methods may be embodied in the form of a program. The program may be stored on a computer readable medium and is adapted to perform any one of the aforementioned methods when run on a computer device (a device including a processor). Thus, the storage medium or computer readable medium is adapted to store information and is adapted to interact with a data processing facility or computer device to perform the method of any of the above mentioned embodiments.
The storage medium may be a built-in medium installed inside a computer device main body or a removable medium arranged so that it can be separated from the computer device main body. Examples of the built-in medium include, but are not limited to, rewriteable non-volatile memories, such as ROMs and flash memories, and hard disks. Examples of the removable medium include, but are not limited to, optical storage media such as CD-ROMs and DVDs; magneto-optical storage media, such as MOs; magnetic storage media, including but not limited to floppy disks (trademark), cassette tapes, and removable hard disks; media with a built-in rewriteable non-volatile memory, including but not limited to memory cards; and media with a built-in ROM, including but not limited to ROM cassettes, etc. Furthermore, various information regarding stored images, for example, property information, may be stored in any other form, or provided in other ways.
Example embodiments being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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