JP2011191694A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device allowing fully reducing wear of a fixing means and improving the life of the fixing means. <P>SOLUTION: A mechanism for laterally moving a paper feed base 105 holding paper sheets 8 is provided in a paper feed tray 104. A control part controls driving of a motor 117 every time a predetermined number of paper sheets 8 are fed from the paper feed tray 104 and laterally moves the paper feed base 105 to change the lateral position of the paper sheets 8 fed from the paper sheet tray 104. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile machine, and a multifunction machine.

  An electrophotographic image forming apparatus transfers a toner image onto a fed recording medium, heat-melts the transferred toner image, fixes the toner image on the recording medium, and outputs the printed matter. In such an image forming apparatus, when the recording medium fed from the paper feed tray is transported to the transfer position of the toner image, the toner on the recording medium is misaligned in the lateral direction perpendicular to the transport direction. The transfer position of the image is shifted, leading to a decrease in image quality. In view of such problems, a shift mechanism that shifts the recording medium in the lateral direction is provided in front of the toner image transfer position, and a technology for correcting a lateral position shift of the recording medium that occurs in the conveyance process by this shift mechanism. It has been proposed (see Patent Document 1).

  In the technique described in Patent Document 1, the shift of the lateral position of the recording medium conveyed to the transfer position is corrected by the shift mechanism, so that the recording medium conveyance line at the subsequent stage of the transfer position is kept constant. . In this case, when the toner image transferred to the recording medium is fixed to the recording medium by a fixing unit such as a fixing belt, the lateral edge of the recording medium repeatedly passes through the same portion of the fixing unit. There is a concern that the same portion of the fixing unit is intensively worn by the edge of the recording medium, leading to a reduction in the life of the fixing unit. Therefore, when correcting the shift of the lateral position of the recording medium conveyed to the transfer position by the above shift mechanism, the lateral position (reference position) of the recording medium targeted for correction is periodically shifted, so that the recording is performed. Attempts have also been made to reduce the wear of the fixing means by dispersing the positions on the fixing means through which the edge of the medium passes (see Patent Document 2).

  However, in the technique described in Patent Document 2, the range in which the lateral position of the recording medium can be shifted is limited to reduce wear of the fixing unit due to mechanical restrictions of the shift mechanism. Specifically, in the shift mechanism described in Patent Document 2, the range in which the recording medium can be moved in the lateral direction is set to ± 5 mm, and of these, the correction of the lateral position deviation, which is the original function, is ± 4 mm is secured, and the reference position serving as the correction target position is periodically shifted in the remaining range of ± 1 mm. Therefore, the range in which the position of the fixing unit through which the edge of the recording medium passes can be dispersed is limited to a very small range, and it is difficult to sufficiently reduce the wear of the fixing unit.

  The present invention has been made in view of the above, and an object of the present invention is to provide an image forming apparatus capable of sufficiently reducing the wear of the fixing unit and improving the life of the fixing unit.

  In order to solve the above-described problems and achieve the object, an image forming apparatus according to the present invention includes a paper feed tray that holds a recording medium, a recording medium that is held by the paper feed tray, and a conveyance direction of the recording medium. A lateral movement means for moving in a transverse direction orthogonal to the image; a transfer means for transferring a toner image onto a recording medium fed and conveyed from the paper feed tray; and a toner image transferred onto the recording medium by the transfer means. A fixing unit that heats and melts the toner and fixes the recording medium on the recording medium, and a lateral position that is a horizontal position of the recording medium fed from the sheet feeding tray is changed by operating the lateral movement unit at a predetermined timing. And a control means.

  In addition, an image forming apparatus according to the present invention includes a paper feed tray that holds a recording medium, and a recording medium that is held by the paper feed tray in a lateral direction perpendicular to the conveyance direction of the recording medium in response to a user operation. A lateral movement means for moving; a transfer means for transferring a toner image onto a recording medium fed from the paper feed tray and conveyed; and a toner image transferred onto the recording medium by the transfer means is heated and melted. Fixing means for fixing to a recording medium; and presenting means for presenting to the user timing for changing the lateral position, which is the lateral position of the recording medium fed from the paper feed tray by operating the lateral movement means. It is characterized by providing.

  In addition, the image forming apparatus according to the present invention includes a plurality of paper feed trays that hold a recording medium of the same size so that lateral positions that are lateral positions orthogonal to the conveyance direction of the recording medium are different from each other; Paper feeding means for sequentially taking out and feeding recording media from a plurality of paper feeding trays, transfer means for transferring a toner image onto a recording medium fed and conveyed by the paper feeding means, and recording by the transfer means And a fixing unit that heats and melts the toner image transferred onto the medium and fixes the toner image on the recording medium.

  According to the present invention, the position of the fixing unit through which the edge of the recording medium passes can be dispersed over a wide range by changing the lateral position of the recording medium fed from the paper feed tray. There is an effect that the wear can be sufficiently reduced and the life of the fixing means can be improved.

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus. FIG. 2 is a schematic configuration diagram of a registration unit shift device provided in the paper conveyance path. FIG. 3 is a schematic diagram showing the configuration and operation of the shift unit. FIG. 4 is a diagram illustrating an example of a shift pattern by the shift unit. FIG. 5 is a diagram for explaining another example of the shift pattern by the shift unit. FIG. 6 is a diagram for explaining another example of the shift pattern by the shift unit. FIG. 7 is a diagram illustrating a specific example of a lateral movement mechanism of the paper feed tray provided in the image forming apparatus according to the first embodiment. FIG. 8 is a block diagram showing the configuration of a control system that drives and controls the lateral movement mechanism of the paper feed tray. FIG. 9 is a flowchart illustrating a flow of a series of processes executed by the control unit of the image forming apparatus according to the first embodiment. FIG. 10 is a diagram for explaining the optimum value of the lateral position change amount of paper fed from the paper feed tray. FIG. 11 is a diagram illustrating a specific example of a paper feed lateral movement mechanism included in the image forming apparatus according to the second embodiment. FIG. 12 is a block diagram showing a configuration of a control system for presenting to the user the timing for changing the lateral position of the paper fed from the paper feed tray. FIG. 13 is a flowchart illustrating a flow of a series of processes executed by the control unit of the image forming apparatus according to the second embodiment. FIG. 14 is a schematic configuration diagram of a paper feeding device provided in the image forming apparatus according to the third embodiment. FIG. 15 is a schematic diagram illustrating a state in which a sheet is held by a plurality of sheet feeding trays of the sheet feeding device as viewed in the sheet conveyance direction.

  Exemplary embodiments of an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the first embodiment. The image forming apparatus according to the present embodiment forms four-color full-color images. As shown in FIG. 1, the image forming apparatus includes four pieces arranged along the running direction of the transfer belt 10 (the direction of arrow A in the figure). Image forming units 1a, 1b, 1c, and 1d are provided.

  The image forming unit 1a includes a photosensitive drum 2a as an image carrier, a drum charger 3a, an exposure device 4a, a developing device 5a, a transfer device 6a, and a cleaning device 7a. Similarly to the image forming unit 1a, the image forming units 1b to 1d are also photosensitive drums 2b to 2d, drum chargers 3b to 3d, exposure devices 4b to 4d, developing devices 5b to 5d, transfer devices 6b to 6d, and a cleaning device 7b. To 7d. The image forming units 1a to 1d form images of different colors, for example, the image forming unit 1a is yellow, the image forming unit 1b is magenta, the image forming unit 1c is cyan, and the image forming unit 1d is black.

  The photosensitive drum 2a starts to rotate in the direction of arrow B in the figure at the time of image formation, and continues to rotate until the image forming operation is completed. When the photosensitive drum 2a starts rotating, a high voltage is applied to the drum charger 3a, and negative charges are uniformly charged on the surface of the photosensitive drum 2a. Thereafter, the surface of the charged photosensitive drum 2a is irradiated with laser light according to the image data from the exposure device 4a, and an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 2a. When the portion where the electrostatic latent image is formed by the rotation of the photosensitive drum 2a reaches a position facing the developing device 5a, the negatively charged toner is attracted from the developing device 5a to the electrostatic latent image, thereby The electrostatic latent image is developed with toner to form a toner image on the photosensitive drum 2a.

  When the toner image formed on the photosensitive drum 2a reaches a position facing the transfer device 6a across the transfer belt 10, the toner image is attracted to the transfer belt 10 side by the action of a high voltage applied to the transfer device 6a. Transfer (primary transfer) is performed on the transfer belt 10 moving in the middle arrow A direction. The toner remaining on the photosensitive drum 2a without being transferred to the transfer belt 10 is cleaned by the cleaning device 7a.

  An image forming operation is performed in the same manner in the image forming unit 1b following the image forming unit 1a, and the toner image formed on the photosensitive drum 2b is applied on the transfer belt 10 by the action of a high voltage applied to the transfer device 6b. Transferred (primary transfer). At this time, the timing at which the toner image formed on the photosensitive drum 2b reaches the position facing the transfer device 6b is the same as the transfer of the toner image transferred from the photosensitive drum 2a onto the transfer belt 10 by the transfer belt 10. The toner image transferred from the photosensitive drum 2a and the toner image transferred from the photosensitive drum 2b are superimposed on the transfer belt 10 by being controlled so as to match the timing of reaching the position 6b.

  Similarly, the toner image formed on the photosensitive drum 2c of the image forming unit 1c and the toner image formed on the photosensitive drum 2d of the image forming unit 1d are sequentially transferred onto the transfer belt 10, thereby transferring the transfer belt. A full-color toner image is formed on 10.

  On the other hand, in the image forming apparatus according to the present embodiment, a paper feed tray 104 that holds the paper 8, a registration unit paper shift device (not shown in FIG. 1), A paper transfer device 9 and a fixing device 11 are provided.

  The paper 8 fed from the paper feed tray 104 is conveyed in the direction of arrow C in the figure, and is temporarily put on standby by the registration unit paper shift device. Then, at the timing when the full-color toner image formed on the transfer belt 10 reaches the position facing the paper transfer unit 9 due to the movement of the transfer belt 10, the paper 8 once waiting in the registration unit paper shift device is transferred to the paper. The full color toner image formed on the transfer belt 10 is transferred (secondary transfer) onto the paper 8 by the action of the high voltage applied to the paper transfer device 9 by being sent to the position of the device 9. The toner remaining on the transfer belt 10 without being transferred to the paper 8 is cleaned by the belt cleaning mechanism 12.

  The sheet 8 on which the full color toner image is transferred is conveyed to the fixing device 11. The fixing device 11 includes a pressure roller 11a, a fixing roller 11b, a fixing belt 11c, and a heating roller 11d, and draws the paper 8 into a nip portion formed between the pressure roller 11a and the fixing roller 11b. The toner image on the paper 8 is heated and melted by the heat transmitted from the heating roller 11 d to the fixing belt 11 c and is fixed to the paper 8 in the process of being conveyed while being pressurized. The paper 8 on which the toner image has been fixed by the fixing device 11 is discharged as a printed matter onto a paper discharge tray (not shown).

  2A and 2B are diagrams showing a schematic configuration of the registration unit shift device provided in the conveyance path of the paper 8, wherein FIG. 2A is a side view of the registration unit shift device and its peripheral mechanism, and FIG. It is a top view of the peripheral mechanism. The registration unit paper shift device includes a gate unit 13 for positioning the leading end of the paper 8 fed from the paper feed tray 104 and conveyed, and a conveyance roller pair 15 arranged on the upstream side of the gate unit 13 in the paper conveyance path. And a registration roller pair 16, a lateral position detection sensor 17, a timing roller 18, and a conveyance belt 19 disposed on the downstream side of the gate means 13 in the sheet conveyance path. Here, the gate unit 13 and the registration roller pair 16 are arranged in a shift unit 40 which is a lateral deviation correction unit, and the registration roller pair 16 can move along a lateral direction 26 which is a direction orthogonal to the sheet conveyance direction. It is configured.

  The gate means 13 is driven to an open position where the conveyed paper 8 is passed and a closed position where the paper 8 is positioned by interfering with the front end of the paper 8. Further, the registration roller pair 16 and the conveyance roller pair 15 are configured such that two roller members can be rotated and contacted / separated (separated, abutted or pressed) by driving means (not shown). That is, the two roller members are arranged so as to sandwich the paper 8 on the transport path in the thickness direction, and are driven to a contact position for transporting the paper 8 and a separation position for separating the paper 8. The gate means 13 is configured to close when the registration roller pair 16 is separated.

  The lateral position detection sensor 17 is disposed between the gate unit 13 and the sheet transfer unit 9 in the sheet conveyance path. The lateral position detection sensor 17 detects the position of the lateral edge of the paper 8 conveyed to the paper transfer unit 9. The shift unit 40 moves the sheet 8 in the lateral direction 26 in order to correct the deviation of the position of the lateral edge of the sheet 8 detected by the lateral position detection sensor 17 from the reference position 24.

  The paper 8 fed from the paper feed tray 104 is conveyed in the direction of arrow C in the figure at a prescribed speed V1 toward the gate means 13 by the conveying roller pair 15 and the like. Since the conveyed paper 8 has its leading end abutted against the gate means 13 and the rear end side of the paper 8 is sent to the downstream side by the conveying roller pair 15 from the abutted state (overfeed), the paper 8 is bent. . The oblique shift of the paper 8 is corrected by the excessive feeding in the state of being abutted against the gate means 13. In this state, by closing the registration roller pair 16 and pressing the paper, the leading edge of the paper 8 is positioned at the position of the gate means 13.

  Subsequently, the gate means 13 moves to the open position so as to retract from the conveyance path of the paper 8. Further, as the conveying roller pair 15 is separated from the paper 8, the paper 8 returns to a straight state. That is, the sheet position deviation on the upstream side of the registration roller pair 16 is also corrected.

  From this state, the registration roller pair 16 is set to a predetermined timing, that is, the front end of the toner image on the transfer belt 10 in the belt rotation direction and the conveyance direction of the paper 8 in accordance with the timing of the toner image conveyed by the movement of the transfer belt 10. The sheet 8 is conveyed at a specified speed in the direction of arrow C in the figure at a timing when the predetermined position of the leading end coincides. At this time, the registration roller pair 16 attached to the shift unit 40 is moved in the lateral direction 26, and the sheet 8 is moved in the lateral direction 26 so that the lateral edge of the sheet 8 coincides with the reference position 24. The sheet 8 moved to the reference position 24 is conveyed by the conveying belt 19 to the fixing device 11 through a traveling line D indicated by a broken line in the drawing.

  Note that, in the image forming apparatus according to the present embodiment, as will be described later, in order to reduce local wear of the fixing belt 11c of the fixing device 11, a reference serving as a target position after the correction of the paper 8 by the shift unit 40 is performed. By periodically shifting the position 24, the travel line D of the paper 8 is displaced in the lateral direction 26, and the positions where the lateral edge of the paper 8 enters the nip portion of the fixing device 11 are dispersed. .

  FIG. 3 is a schematic diagram illustrating the configuration and operation of the shift unit 40. The shift unit 40 includes a substrate 41 on which the registration roller pair 16 is disposed, a cam 42 that is rotationally driven under the control of a shift control unit (not shown), and a spring 43 that presses the substrate 41 against the cam 42. A cam position detector 44 that detects the rotational position of the cam 42, and a position detection plate member 45 that is formed with a notch for detecting the position of the cam position detector 44 and rotates integrally with the cam 42. .

  In the shift unit 40, the cam 42 is controlled in the CW direction in the figure under the control of the shift control unit in accordance with the amount of deviation of the lateral edge position of the paper 8 from the reference position 24 detected by the lateral position detection sensor 17. (See FIG. 3C) or in the CCW direction (see FIG. 3B) in the figure. As a result, the substrate 41 is moved from the home position 46, and the paper 8 is moved in the lateral direction 26 to the operator side and the counter operator side (the OP side and the counter OP side in the figure).

  In the image forming apparatus according to the present embodiment, the shift unit 40 rotates the cam 42 based on the signal from the lateral position detection sensor 17 to move the paper 8 in the lateral direction 26, and the lateral edge position of the paper 8. In addition to correcting the deviation amount of the fixing device 11 relative to the reference position 24, the reference position 24, which is the corrected target position, is periodically shifted in the lateral direction 26 in order to reduce local wear of the fixing belt 11c of the fixing device 11. Then, the lateral position of the corrected paper 8 is shifted periodically. Note that the lateral position of the sheet 8 passing through the position of the sheet transfer unit 9 is periodically shifted by the periodic shift of the reference position 24, but according to the periodic shift of the reference position 24. A shift command is also input to an exposure control unit (not shown) that controls the above-described exposure apparatuses 4a to 4d, and the exposure apparatuses 4a to 4d have the photosensitive drum 2a corresponding to the shift amount of the lateral position of the paper 8. Since the exposure position to 2d is moved in the horizontal direction, the full color toner image formed on the transfer belt 10 and the horizontal position of the paper 8 passing through the position of the paper transfer unit 9 can be matched.

  Here, a specific example of a shift pattern for shifting the reference position 24 will be described. 4 to 6 illustrate specific examples of shift patterns. (A) in each figure is a schematic diagram showing the shift pattern, and (b) is assumed when the shift pattern in (a) is adopted. FIG. 6 is a schematic diagram illustrating a state where the fixing belt 11c is worn.

  In the first example, as shown in FIG. 4A, the reference position 24 is shifted in accordance with a shift pattern in which the shift width decreases for a while to a predetermined width. In this case, since the positions in the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes are dispersed according to the shift pattern of FIG. 4A, the wear location 101 on the surface 100 of the fixing belt 11c is illustrated in FIG. It becomes a substantially trapezoid as shown in 4 (b). Therefore, in this example, the boundary becomes inconspicuous at the boundary between the wear point 101 and the point where no wear occurs, and the wear of the narrow side portion of the wear point 101 forming the trapezoid does not increase, and further, between the oblique side and the narrow side. There is no difference in level. For this reason, the occurrence of fixing unevenness can be extremely effectively prevented.

  In the second example, as shown in FIG. 5A, the reference position 24 is shifted according to a shift pattern in which the shift width decreases for a while. In this case, since the positions in the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes are distributed according to the shift pattern of FIG. 5A, the wear portion 102 on the surface 100 of the fixing belt 11c is illustrated in FIG. As shown in 5 (b), it becomes a substantially triangular shape. Therefore, in this example, the boundary becomes inconspicuous at the boundary between the wear location 102 and the location where no wear occurs, but the portion near the apex of the wear location 102 forming a triangle has a relatively high number of passes through the edge of the paper 8. Wear increases.

  In the third example, as shown in FIG. 6A, the reference position 24 is shifted a plurality of times with a shift pattern having the same width. In this case, since the positions in the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes are distributed according to the shift pattern of FIG. 6A, the wear portion 103 on the surface 100 of the fixing belt 11c is illustrated in FIG. As shown in FIG. Therefore, in this example, although the amount of wear is suppressed as a whole, a step is generated at the boundary between the wear portion 103 and a portion where no wear occurs.

  By the way, the range in which the paper 8 can be moved in the lateral direction by the shift unit 40 as described above is the movable range of the substrate 41 by the action of the cam 42. Here, in the shift unit 40 used in the present embodiment, the movable range of the substrate 41 due to the action of the cam 42, that is, the range in which the paper 8 can be moved in the lateral direction is, for example, ± 5 mm. ± 4 mm is used for correcting the lateral position deviation, and the reference position 24 (the lateral position of the corrected paper 8) is periodically shifted within the remaining ± 1 mm. For this reason, the range in which the position in the nip portion of the fixing device 11 through which the lateral edge of the sheet 8 passes is limited to a very small range, and only the periodic shift of the reference position 24 by the shift unit 40 is performed. Then, it is difficult to sufficiently reduce the wear of the fixing belt 11c of the fixing device 11.

  Therefore, in the image forming apparatus according to the present embodiment, the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes is changed by changing the lateral position of the paper 8 when it is fed from the paper feed tray 104. Can be dispersed over a wide range so that the wear of the fixing belt 11c of the fixing device 11 can be sufficiently reduced and the life of the fixing belt 11c can be improved. In particular, in the present embodiment, a lateral movement mechanism for moving the paper 8 held in the paper feed tray 104 in the horizontal direction is provided in the paper feed tray 104, and at a predetermined timing, specifically, for example, a predetermined number of sheets from the paper feed tray 104. Each time the paper 8 is fed, the lateral movement mechanism is operated to change the lateral position of the paper 8 fed from the paper feed tray 104.

  Note that, by changing the horizontal position of the paper 8 fed from the paper feed tray 104, the horizontal position of the paper 8 passing through the position of the paper transfer unit 9 changes. When the horizontal position of the paper 8 is changed, information on the paper horizontal position is input to an exposure control unit (not shown) that controls the above-described exposure devices 4a to 4d. In order to move the exposure position on the photosensitive drums 2a to 2d laterally by an amount corresponding to the amount of change in position, a full-color toner image formed on the transfer belt 10 and a sheet passing through the position of the sheet transfer unit 9 are used. The horizontal position of each of 8 can be matched.

  FIG. 7 is a diagram illustrating a specific example of the lateral movement mechanism of the paper feed tray 104. The paper feed tray 104 includes a paper feed tray 105 that holds the paper 8. The paper feed tray 105 is provided with a paper feed bottom plate 106 on which the paper 8 is stacked, a side guide plate 115 that is erected substantially perpendicular to the paper feed bottom plate 106 and aligns both lateral ends of the paper 8. The sheet feeding base plate 105 a and 105 b for supporting the paper bottom plate 106 and the paper feeding base plate 116 are configured. In the sheet feed table 105, the sheet feed table side plates 105 a and 105 b are inserted into a guide shaft 114 provided between the side plates 104 a and 104 b of the sheet feed tray 104, and the sheet 8 is conveyed along the guide shaft 114. Is supported so as to be slidable in a lateral direction 26 orthogonal to the horizontal direction.

  A motor 117 is disposed on the sheet feeding table bottom plate 116 of the sheet feeding table 105. One end of a ball screw 120 coaxial with the motor shaft 118 is connected to the motor shaft 118 of the motor 117 via a joint portion 119. A slit disk 128 is provided at the other end of the ball screw 120 so as to rotate integrally with the ball screw 120. Both ends of the ball screw 120 are supported by a U-shaped support plate 127 fixed on the sheet feed base plate 116.

  A substantially L-shaped bracket 129 having one surface fixed to the stationary bottom plate of the paper feed tray 104 is screwed to the thread portion of the ball screw 120. Therefore, when the ball screw 120 is rotated with respect to the stationary bracket 129 by driving the motor 117, the paper feed base 105 moves in the lateral direction 26 along the guide shaft 114, and the paper 8 held on the paper feed base 105 is laterally moved. Move in direction 26. Thereby, the lateral position of the paper 8 fed from the paper feed tray 104 can be changed.

  The slit disk 128 is provided with a plurality of slits (not shown) radially at equal intervals. A slit sensor 130 for counting the number of slits is disposed at a position facing the slits of the slit disk 128. The slit sensor 130 outputs a pulse corresponding to the counted number of slits. Therefore, based on the output pulse from the slit sensor 130, the position of the paper feed tray 105 in the lateral direction 26 (the lateral position of the paper 8) can be detected. When a stepping motor is used as the motor 117, the position of the paper feed tray 105 in the lateral direction 26 can be detected without providing the slit disk 128 or the slit sensor 130.

  A paper feed base reference position indicating plate 107 for confirming the position of the paper feed stand 105 in the lateral direction 26 is provided on the lower surface of the paper feed base bottom plate 116. A paper feed base reference position sensor 108 is provided at a position on the bottom plate of the paper tray 104. A position where the paper feed base reference position indicating plate 107 and the paper feed base reference position sensor 108 overlap is set as a home position of the paper feed base 105. When the paper feed tray 105 is at the home position, the paper 8 is fed to the center of the transport path.

  FIG. 8 is a block diagram illustrating a configuration of a control system that drives and controls the lateral movement mechanism of the paper feed tray 104. The control system includes a control unit 200, a nonvolatile memory 201, a paper detection sensor 202, a motor 117, and a slit sensor 130. The control unit 200 is connected to the exposure control unit 203 that controls the above-described exposure apparatuses 4a to 4d and the shift control unit 204 that controls the operation of the shift unit 40 of the registration unit shift device. The control unit 200 is configured using, for example, a microcomputer, and the CPU controls the drive of the lateral movement mechanism of the paper feed tray 104 by executing a control program stored in the ROM using the RAM as a work area. To do.

The nonvolatile memory 201 stores setting information for controlling driving of the lateral movement mechanism of the paper feed tray 104. Here, the setting information includes an initial position of the paper feed tray 105, a post-movement position, and a movement cycle. Specifically, for example, the following information is stored in the nonvolatile memory 201 as setting information.
・ Paper feed initial position: Home position ・ First movement position: Position moved 2 mm laterally from the home position to the non-operator side (-2 mm)
-Second position of movement: Position moved 2 mm laterally from the home position to the operator side (+2 mm)
Paper feed table movement cycle: every 500 sheets fed Note that these setting information may be set in advance as predetermined values and stored in the non-volatile memory 201 or operated by a user using the image forming apparatus. The setting information input by the user may be stored in the non-volatile memory 201 by using an input unit such as a panel.

  The paper detection sensor 202 detects the passage of the paper 8 fed from the paper feed tray 104 and transported through the transport path, and outputs a detection signal to the control unit 200. It is installed in the position. Note that the lateral position detection sensor 17 of the registration unit shift device described above may be used as the paper detection sensor 202 and the detection signal of the lateral position detection sensor 17 may be input to the control unit 200.

  Prior to the start of a print job by the image forming apparatus, the control unit 200 reads the setting information from the non-volatile memory 201, and sets the initial position of the paper feed tray 105, the position after movement (the position and movement of the first movement). (Second position), the movement cycle of the paper feed tray 105 is set. When the print job is started, the number of sheets 8 fed from the sheet feed tray 104 is counted based on the detection signal of the sheet detection sensor 202, and the number of sheets fed from the sheet feed tray 104 is counted as a sheet feed table. Each time the predetermined number of sheets (for example, 500 sheets) set as the moving cycle 105 is reached, the sheet feeding from the sheet feeding tray 104 is temporarily stopped. Then, by driving and controlling the motor 117 according to the output pulse from the slit sensor 130, the paper feed tray 105 of the paper feed tray 104 is moved to the position set as the moved position.

  Specifically, for example, when the position of the first movement is set to -2 mm and the position of the second movement is set to +2 mm, the control unit 200 moves the paper feed tray 105 from the home position to the counter operator in the first movement. The paper feed table 105 is moved laterally from the home position to the 2 mm position from the home position to the operator side, and the third movement returns the paper feed platform 105 to the home position. After that, every time a predetermined number of sheets are fed, the lateral movement of the sheet feeding table 105 is repeated. As a result, the lateral position of the sheet 8 fed from the sheet feed tray 104 changes every time a predetermined number of sheets are fed.

  Further, when the control unit 200 moves the paper feed tray 105 laterally to change the lateral position of the paper 8 fed from the paper feed tray 104, the paper according to the moved position of the paper feed tray 105 is obtained. 8 is output to the exposure control unit 203 and the shift control unit 204. As a result, the exposure devices 4a to 4d move the exposure positions on the photosensitive drums 2a to 2d in the horizontal direction by an amount corresponding to the change amount of the horizontal position of the paper 8 in accordance with the control of the exposure control unit 203, so The full-color toner image formed on the sheet can be aligned with the lateral position of the sheet passing through the position of the sheet transfer unit 9. In the shift unit 40, the shift control unit 204 sets the reference position 24 at a position moved in the horizontal direction by an amount corresponding to the amount of change in the horizontal position of the paper 8. The shift unit 40 sets the reference position 24 to the reference position 24. A lateral edge correction and a periodic shift of the reference position 24 are performed.

  FIG. 9 is a flowchart illustrating a flow of a series of processes executed by the control unit 200 when executing a print job in the image forming apparatus according to the present embodiment. The operation will be described below with reference to the flowchart of FIG.

  When the flow of FIG. 9 is started, the control unit 200 first reads setting information from the nonvolatile memory 201, and sets the initial position of the paper feed tray 105, the position after movement, and the movement cycle of the paper feed tray 105. (Step S101). Then, the control unit 200 drives and controls the motor 117 to move the paper feed tray 105 to the set initial position (step S102).

  Next, the control unit 200 outputs information on the lateral position of the paper 8 according to the current position of the paper feed tray 105 to the exposure control unit 203 and the shift control unit 204 (step S103). Then, the control unit 200 starts feeding the paper 8 from the paper feed tray 104 (step S104). At the start of paper feeding, toner images are formed by the image forming units 1a to 1d, the position of the paper 8 is adjusted by the shift unit 40 of the registration unit shift device, the toner image is transferred to the paper 8 by the paper transfer unit 9, and the fixing device 11 is used. A series of printing operations such as fixing of the toner image in the printer and discharging the printed matter to the discharge tray are performed. At this time, information on the lateral position of the paper 8 fed from the paper feed tray 104 is transmitted to the exposure control unit 203 and the shift control unit 204. For this reason, the alignment of the toner image on the paper 8, the positional deviation correction of the lateral edge of the paper 8 in the shift unit 40, and the periodic shift of the reference position 24 are performed on the paper fed from the paper feed tray 104. Therefore, it is appropriately implemented in accordance with the horizontal position of 8.

  When the sheet 8 is fed from the sheet feed tray 104, the control unit 200 counts the number of sheets fed from the sheet feed tray 104 based on the detection signal of the sheet detection sensor 202 (step S105). Then, until the printing is completed (step S106: No), the control unit 200 determines whether the number of fed sheets counted in step S105 has reached the predetermined number set as the movement cycle of the sheet feeding table 105 in step S101. Whether or not (step S107) and the number of fed sheets has not reached the predetermined number (step S107: No), the process returns to step S104 to continue feeding from the sheet feeding tray 104 and counting the number of fed sheets.

  On the other hand, when the number of fed sheets reaches the predetermined number (step S107: Yes), the control unit 200 temporarily stops feeding the sheet 8 from the sheet feeding tray 104 (step S108), and from the slit sensor 130. In response to the output pulse, the motor 117 is driven to move the paper feed tray 105 to the post-movement position set in step S101 (step S109), and the lateral position of the paper 8 held on the paper feed tray 105 is adjusted. Change. Then, the control unit 200 resets the value of the counter that counts the number of sheets fed (step S110), returns to step S103, and exposes the information on the lateral position of the sheet 8 according to the position of the sheet feed tray 105 after the movement. The output to the control unit 203 and the shift control unit 204 is resumed, and the paper supply from the paper supply tray 104 is resumed (step S104).

  Thereafter, the control unit 200 repeats the above-described process until the printing is completed (step S106: No), and ends the series of processes when the printing is completed (step S106: Yes).

  As described above, in the image forming apparatus according to this embodiment, the nip of the fixing device 11 through which the lateral edge of the paper 8 passes by changing the horizontal position of the paper 8 fed from the paper feed tray 104. The positions of the fixing portions 11 are dispersed over a wide range so that the wear of the fixing belt 11c of the fixing device 11 can be sufficiently reduced. Here, the lateral position change amount of the paper 8 fed from the paper feed tray 104 is in balance with the lateral position shift amount of the paper 8 by the shift unit 40, and the alignment of the printed matter discharged to the paper discharge tray is the highest. It is desirable to set it to a good value. In the image forming apparatus according to the present embodiment, as described above, the lateral position of the paper 8 fed from the paper feed tray 104 is changed and, for example, ± 1 mm (= 2 mm) by the shift unit 40 of the registration unit shift device. In this range, the lateral position of the paper 8 is periodically shifted to reduce wear of the fixing belt 11c. The lateral position change amount of the paper 8 fed from the paper feed tray 104 is preferably set to 2 mm in accordance with the lateral position shift amount of the paper 8 by the shift unit 40.

  FIG. 10 is a diagram for explaining the optimum value of the lateral position change amount of the paper 8 fed from the paper feed tray 104. FIG. 10A shows the lateral position of the paper 8 when the number of fed paper reaches a predetermined number. Shows the wear state of the fixing belt 11c when the sheet is moved 4 mm from the initial position, and (b) is the fixing when the lateral position of the sheet 8 is moved 2 mm from the initial position when the number of fed sheets reaches a predetermined number. The worn state of the belt 11c is shown. The shift unit 40 periodically shifts the lateral position of the paper within a range of ± 1 mm (= 2 mm) with the lateral position of the paper 8 fed from the paper feed tray 104 as the center.

  When the wear state of the fixing belt 11c shown in FIG. 10A is compared with the wear state of the fixing belt 11c shown in FIG. 10B, the wear amount of the fixing belt 11c is the same. Lifespan is the same. However, in FIG. 10A, the wear portion of the fixing belt 11c due to the passage of the lateral edge of the paper 8 spreads to a range of 6 mm at the maximum, whereas in FIG. The wear portion of the fixing belt 11c due to the passage of the direction end edge is suppressed to a range of 4 mm at the maximum. The smaller the range of the worn portion of the fixing belt 11c, that is, the range through which the lateral edge of the paper 8 passes, the better the alignment of printed matter discharged to the paper discharge tray. For this reason, when the periodic shift amount of the paper lateral position by the shift unit 40 is ± 1 mm (= 2 mm), as shown in the example of FIG. The optimum value of the position change amount is 2 mm. In other words, by making the lateral position change amount of the paper 8 fed from the paper feed tray 104 substantially equal to the periodic shift amount of the paper lateral position by the shift unit 40, while extending the life of the fixing belt 11c, It is possible to minimize a decrease in the alignment of printed materials discharged to the paper discharge tray.

  As described above in detail with specific examples, the image forming apparatus according to the present embodiment is provided with a mechanism for moving the paper feed table 105 holding the paper 8 in the lateral direction in the paper feed tray 104. The control unit 200 drives and controls the motor 117 each time a predetermined number of sheets 8 are fed from the sheet feed tray 104 to move the sheet feed tray 105 in the horizontal direction, and the sheets fed from the sheet feed tray 104. The horizontal position of 8 is changed. Therefore, according to this image forming apparatus, the position in the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes can be dispersed over a wide range, and the wear of the fixing belt 11c of the fixing device 11 can be sufficiently reduced. Thus, the life of the fixing belt 11c can be improved.

  In addition, the image forming apparatus according to the present embodiment changes the lateral position of the paper 8 fed from the paper feed tray 104, and uses the shift unit 40 of the registration unit shift device to adjust the lateral width of the paper 8 within a range of ± 1 mm, for example. By periodically shifting the position, the wear of the fixing belt 11c is reduced, so that the wear of the fixing belt 11c of the fixing device 11 can be extremely effectively reduced.

  Further, the image forming apparatus according to the present embodiment makes the lateral position change amount of the paper 8 fed from the paper feed tray 104 substantially equal to the periodic shift amount of the paper lateral position by the shift unit 40. While extending the life of the fixing belt 11c, it is possible to minimize a decrease in the alignment of printed matter discharged to the discharge tray.

  In the above-described embodiment, a predetermined number of sheets (for example, 500 sheets) that are set in advance as the sheet feeding table moving cycle is used as the timing at which the lateral position of the sheet 8 fed from the sheet feeding tray 104 is changed. It's a good timing. On the other hand, the timing for changing the lateral position of the paper 8 fed from the paper feed tray 104 may be determined according to the number of pages of the print job to be executed. That is, each time the number of pages of the print job to be executed is divided by the total number of the initial position and the moved position of the paper feed tray 105, the paper feed tray 105 is moved in the horizontal direction. The horizontal position of the paper 8 fed from the paper feed tray 104 is changed. For example, in the above example, since the total number of the initial position and the moved position of the paper feed tray 105 is 3 (initial position, first movement position, second movement position), the number of pages of the print job is 30 sheets. If the number of sheets fed from the sheet feed tray 104 reaches 10, the sheet feed tray 105 is moved in the horizontal direction to change the lateral position of the sheet 8 fed from the sheet feed tray 104. . As a result, the wear amount of the fixing belt 11c can be made uniform without being affected by the difference in the number of pages for each print job.

  In the above-described embodiment, when the print job is executed, the control for changing the lateral position of the paper 8 fed from the paper feed tray 104 at a predetermined timing is always performed. However, if the control for changing the lateral position of the paper 8 fed from the paper feed tray 104 is performed, the alignment of the printed matter discharged to the paper discharge tray is somewhat deteriorated. Here, if the print job to be executed includes post-processing such as punch punching processing or stapling processing after printing, if the alignment of the printed material discharged to the paper discharge tray has deteriorated, before the post-processing is performed. It becomes necessary to perform processing for aligning the printed materials, which is complicated. Therefore, it is determined whether the print job to be executed is a job including post-processing. If the print job is a job including post-processing, the horizontal position of the paper 8 fed from the paper feed tray 104 is fixed and executed. Only when the print job to be performed does not include post-processing, control for changing the lateral position of the paper 8 fed from the paper feed tray 104 at a predetermined timing may be performed. As a result, while reducing the wear of the fixing belt 11c, when post-processing is necessary, it is possible to improve the alignment of the printed material discharged to the paper discharge tray and eliminate the need for processing for aligning the printed material.

  In addition, a mode for controlling the lateral position of the paper 8 fed from the paper feed tray 104 at a predetermined timing (fixing portion wear reduction priority mode), and a mode for controlling the paper 8 fed from the paper feed tray 104 are described. A mode in which the horizontal position is fixed (paper discharge alignment priority mode) may be determined in advance as an operation mode of the image forming apparatus so that the user can select one of these two operation modes. Specifically, for example, a screen for setting the operation mode is displayed on the operation panel of the image forming apparatus, and the user can select either the fixing unit wear reduction priority mode or the discharge alignment priority mode on this screen. Like that. Then, when the user performs an operation input for selecting either the fixing unit wear reduction priority mode or the paper discharge alignment priority mode on the operation panel screen, the operation input is accepted and the operation is performed according to the user operation. Set the mode. When the fixing portion wear reduction priority mode is set, control is performed to change the lateral position of the paper 8 fed from the paper feed tray 104 at a predetermined timing. When the paper discharge alignment priority mode is set, the horizontal position of the paper 8 fed from the paper feed tray 104 is fixed. As a result, the operation mode is set according to the user's intention, and in the case of printing in which the alignment of the printed matter is important, the alignment is improved, and in the case of printing in which the alignment of the printed matter is not particularly problematic, the wear of the fixing belt 11c. Reduction can be achieved and the life of the fixing belt 11c can be extended.

(Second Embodiment)
Next, an image forming apparatus according to the second embodiment will be described. In the present embodiment, it is assumed that the horizontal position of the paper 8 fed from the paper feed tray 104 is changed by the user's operation, and the timing for changing the horizontal position of the paper 8 is presented to the user. It is. Since the basic configuration of the image forming apparatus is the same as that of the first embodiment, the same parts as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. Only the characteristic features of this embodiment will be described.

  FIG. 11 is a diagram illustrating a specific example of a lateral movement mechanism of the paper feed tray 104 provided in the image forming apparatus according to the present embodiment. The paper feed tray 104 includes a paper feed tray 105 that holds the paper 8. The paper feed tray 105 is provided with a paper feed bottom plate 106 on which the paper 8 is stacked, a side guide plate 115 that is erected substantially perpendicular to the paper feed bottom plate 106 and aligns both lateral ends of the paper 8. The sheet feeding base plate 105 a and 105 b for supporting the paper bottom plate 106 and the paper feeding base plate 116 are configured. In the sheet feed table 105, the sheet feed table side plates 105 a and 105 b are inserted into a guide shaft 114 provided between the side plates 104 a and 104 b of the sheet feed tray 104, and the sheet 8 is conveyed along the guide shaft 114. Is supported so as to be slidable in a lateral direction 26 orthogonal to the horizontal direction.

  A knob 140 that can be operated by the user from the outside of the paper feed tray 104 is disposed on the paper feed tray bottom plate 116 of the paper feed tray 105. One end of a ball screw 120 coaxial with the shaft portion 140 a is connected to the shaft portion 140 a of the knob 140 via a joint portion 119. A slit disk 128 is provided at the other end of the ball screw 120 so as to rotate integrally with the ball screw 120. Both ends of the ball screw 120 are supported by a U-shaped support plate 127 fixed on the sheet feed base plate 116.

  A substantially L-shaped bracket 129 having one surface fixed to the stationary bottom plate of the paper feed tray 104 is screwed to the thread portion of the ball screw 120. Therefore, when the user rotates the knob 140 and the ball screw 120 rotates with respect to the stationary bracket 129, the paper feed base 105 moves in the lateral direction 26 along the guide shaft 114 and is held by the paper feed base 105. The paper 8 moves in the horizontal direction 26. Thereby, the lateral position of the paper 8 fed from the paper feed tray 104 can be changed.

  The slit disk 128 is provided with a plurality of slits (not shown) radially at equal intervals. A slit sensor 130 for counting the number of slits is disposed at a position facing the slits of the slit disk 128. The slit sensor 130 outputs a pulse corresponding to the counted number of slits. Therefore, based on the output pulse from the slit sensor 130, the position of the paper feed tray 105 in the lateral direction 26 (the lateral position of the paper 8) can be detected.

  FIG. 12 is a block diagram showing a configuration of a control system for presenting to the user the timing for changing the lateral position of the paper 8 fed from the paper feed tray 104. This control system includes a control unit 300, a nonvolatile memory 301, a sheet detection sensor 202, and an operation panel 302. The control unit 300 is connected to the exposure control unit 203 that controls the exposure apparatuses 4a to 4d described above and the shift control unit 204 that controls the operation of the shift unit 40 of the registration unit shift apparatus.

  The nonvolatile memory 301 stores the current position information of the paper feed tray 105, that is, information on the current horizontal position of the paper 8 fed from the paper feed tray 104, and the cumulative total at the time when the previous print job is completed. Information on the number of fed sheets is stored.

  Prior to the start of the print job by the image forming apparatus, the control unit 300 reads the current position information of the paper feed tray 105 from the non-volatile memory 301, and the horizontal direction of the paper 8 according to the current position of the paper feed tray 105. The position information is output to the exposure control unit 203 and the shift control unit 204. As a result, the exposure devices 4a to 4d move the exposure positions on the photosensitive drums 2a to 2d in the horizontal direction by an amount corresponding to the change amount of the horizontal position of the paper 8 in accordance with the control of the exposure control unit 203, so The full-color toner image formed on the sheet can be aligned with the lateral position of the sheet passing through the position of the sheet transfer unit 9. In the shift unit 40, the shift control unit 204 sets the reference position 24 at a position moved in the horizontal direction by an amount corresponding to the amount of change in the horizontal position of the paper 8. The shift unit 40 sets the reference position 24 to the reference position 24. A lateral edge correction and a periodic shift of the reference position 24 are performed.

  In addition, the control unit 300 reads the information on the total number of fed sheets at the time when the previous print job is completed from the non-volatile memory 301, and the value of the total number of fed sheets at the time when the previous print job is completed. Is set on the counter. When the print job is started, the number of sheets 8 fed from the sheet feed tray 104 is counted based on the detection signal of the sheet detection sensor 202, and the total number of sheets fed is updated. When the total number of sheets fed at the stage when the print job is completed is equal to or more than a predetermined number (for example, 32,000 sheets), the paper feed tray 104 is operated by operating the knob 140 of the lateral movement mechanism described above. Information that prompts the user to change the position of the table 105, that is, the lateral position of the paper 8 fed from the paper feed tray 104 is displayed on the operation panel 302. At this time, similarly to the above-described first embodiment, the position after the movement of the sheet feed table 105 is set in advance, and the control unit 300 causes the sheet feed table 105 to move to the set position. Information that guides the user's operation may be displayed on the operation panel 302. In addition, the presentation of information to the user is not limited to the display on the operation panel 302, and may be performed by other methods such as audio output from a speaker.

  FIG. 13 is a flowchart illustrating a flow of a series of processes executed by the control unit 300 when executing a print job in the image forming apparatus according to the present embodiment. The operation will be described below with reference to the flowchart of FIG.

  When the flow of FIG. 13 is started, the control unit 300 firstly stores information on the current position of the paper feed tray 105 from the nonvolatile memory 301 and information on the total number of fed sheets at the time when the previous print job is completed. Are read out (step S201). Then, the control unit 300 outputs the information on the lateral position of the paper 8 according to the current position of the paper feed tray 105 to the exposure control unit 203 and the shift control unit 204 (step S202), and the cumulative supply is performed. The number of sheets is set in the counter (step S203).

  Next, the control unit 300 starts feeding paper 8 from the paper feed tray 104 (step S204). At the start of paper feeding, toner images are formed by the image forming units 1a to 1d, the position of the paper 8 is adjusted by the shift unit 40 of the registration unit shift device, the toner image is transferred to the paper 8 by the paper transfer unit 9, and the fixing device 11 is used. A series of printing operations such as fixing of the toner image at the paper and discharging of the printed matter to the paper discharge tray are performed. Information on the lateral position of the paper 8 fed from the paper feed tray 104 is used as the exposure control unit 203 and the shift control unit. 204, the alignment of the toner image on the paper 8, the correction of the positional deviation of the lateral edge of the paper 8 in the shift unit 40, and the periodic shift of the reference position 24 are performed from the paper feed tray 104. This is appropriately performed according to the lateral position of the paper 8 to be fed.

  When the paper 8 is fed from the paper feed tray 104, the control unit 300 feeds the paper from the paper feed tray 104 based on the detection signal of the paper detection sensor 202 until the printing is completed (step S206: No). The number of sheets 8 that have been printed is counted (step S205), and the total number of sheets fed is updated. Then, the control unit 300 checks the counter value when printing is completed (step S206: Yes), and determines whether or not the cumulative number of sheets fed is greater than or equal to a predetermined number (for example, 32,000) (step S207). ).

  If the cumulative number of fed sheets is less than the predetermined number (step S207: No), the control unit 300 writes the cumulative number of fed sheets counted by the counter in the nonvolatile memory 301 (step S208). Then, a series of processing is completed. On the other hand, if the cumulative number of sheets fed is greater than or equal to the predetermined number (step S207: Yes), the knob 140 of the lateral movement mechanism of the sheet feed tray 104 is operated to move the position of the sheet feed tray 105 (from the sheet feed tray 104). Information prompting the user to change the lateral position of the fed paper 8 is displayed on the operation panel 302 (step S209). At this time, the control unit 300 causes the operation panel 302 to display information for guiding the user's operation so that the paper feed table 105 moves to a position set in advance as the position after the movement of the paper feed table 105. You may do it.

  After displaying the above information on the operation panel 302, the control unit 300 monitors whether or not a user operation for changing the position of the paper feed tray 105 is performed (step S210). (Step S210: Yes), the value of the total number of fed sheets is cleared, and the position information of the moved sheet feed tray 105 is written in the nonvolatile memory 301 (Step S211), and the series of processing ends. Note that the position of the paper feed tray 105 after the movement can be confirmed by the output from the slit sensor 130 described above.

  As described above in detail with reference to specific examples, the image forming apparatus according to the present embodiment supplies a mechanism for moving the paper feed tray 105 holding the paper 8 in the horizontal direction in response to a user operation. When the cumulative number of paper sheets provided in the paper tray 104 exceeds a predetermined number, the control unit 300 operates the knob 140 of the lateral movement mechanism of the paper tray 104 to control the position of the paper feed tray 105 (paper feed). Information for prompting the user to change the horizontal position of the paper 8 fed from the tray 104 is displayed on the operation panel 302. Therefore, according to this image forming apparatus, the lateral position of the paper 8 fed from the paper feed tray 104 is changed by a user operation, and the position at the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes. Can be dispersed over a wide range, wear of the fixing belt 11c of the fixing device 11 can be sufficiently reduced, and the life of the fixing belt 11c can be improved.

  In addition, the image forming apparatus according to the present embodiment changes the lateral position of the paper 8 fed from the paper feed tray 104 as well as the registration unit shift device, as in the image forming apparatus according to the first embodiment. Since the shift unit 40 periodically shifts the lateral position of the paper 8 within a range of ± 1 mm, for example, the wear of the fixing belt 11c is reduced, so that the wear of the fixing belt 11c of the fixing device 11 is extremely effective. Can be reduced.

  In the image forming apparatus according to the present embodiment, for example, when the control unit 300 guides the user operation, the lateral position change amount of the paper 8 fed from the paper feed tray 104 is changed by the shift unit 40. By moving the paper feed table 105 so as to be substantially equal to the periodic shift amount of the image, the deterioration of the alignment of the printed matter discharged to the paper discharge tray is minimized while extending the life of the fixing belt 11c. Can do.

(Third embodiment)
Next, an image forming apparatus according to a third embodiment will be described. This embodiment has a plurality of paper feed trays 104 that hold paper 8 of the same size, and includes a paper feed device that sequentially takes out and feeds paper 8 from the plurality of paper feed trays 104. This is an example in which the paper 8 is held so that the paper feed trays 104 have different lateral positions. Since the basic configuration of the image forming apparatus is the same as that of the first embodiment and the second embodiment, the same parts as those of the first embodiment and the second embodiment are the same below. The description which overlaps and abbreviate | omits the description is abbreviate | omitted, and only the characteristic part of this embodiment is demonstrated.

  FIG. 14 is a diagram illustrating a schematic configuration of a paper feeding device 400 included in the image forming apparatus according to the present embodiment. FIG. 15 illustrates how the paper 8 is held by a plurality of paper feeding trays 104a to 104c. It is a schematic diagram which shows a mode that it looked along the direction. 14 and 15 exemplify the case where the number of paper feed trays 14 is three, the number of paper feed trays 104 can be any number greater than or equal to two.

  As shown in FIG. 14, the paper feeding device 400 included in the image forming apparatus according to the present embodiment corresponds to three paper feeding trays 104 a to 104 c that hold paper 8 of the same size and each of the paper feeding trays 104 a to 104 c. Pickup rollers 401a to 401c and paper feed roller pairs 402a to 402c corresponding to the respective paper feed trays 104a to 104c. The sheet feeding device 400 is configured to sequentially take out and feed the sheets 8 of the same size held in the three sheet feeding trays 104a to 104c.

  Specifically, among the three paper feed trays 104a to 104c, while the paper 8 is held in the uppermost paper feed tray 104a, the pickup roller 401a corresponding to the paper feed tray 104a and Only the feed roller pair 402a operates. In this state, the paper 8 taken out from the paper feed tray 104a by the pickup roller 401a is fed by the paper feed roller pair 402a and conveyed to the toner image transfer position. Thereafter, when all the paper 8 held in the paper feed tray 104a is fed, the operations of the pickup roller 401a and the paper feed roller pair 402a are stopped, and the pickup roller 401b and the paper feed roller corresponding to the paper feed tray 104b are stopped. The operation of the pair 402b is started. In this state, the paper 8 taken out from the paper feed tray 104b by the pickup roller 401b is fed by the paper feed roller pair 402b and conveyed to the toner image transfer position. Further, when all the paper 8 held in the paper feed tray 104b is fed, the operations of the pickup roller 401b and the paper feed roller pair 402b are stopped, and the pickup roller 401c and the paper feed roller corresponding to the paper feed tray 104c are stopped. The operation of the pair 402c is started. In this state, the paper 8 taken out from the paper feed tray 104b by the pickup roller 401c is fed by the paper feed roller pair 402c and conveyed to the toner image transfer position.

  As shown in FIG. 15, the three paper feed trays 104 a to 104 c are erected substantially perpendicular to the bottom plates 411 a to 411 c on which the paper 8 is stacked, and the bottom plates 411 a to 411 c, A pair of side guide plates 412a to 412c that align both ends of each are provided. In these three paper feed trays 104a to 104c, the positions of the side guide plates 412a to 412c are different from one another for each paper feed tray, so that the lateral position of the paper 8 is different for each paper feed tray. It is in a different position. Specifically, the horizontal position P2 of the paper 8 held by the paper feed tray 104b is shifted to the left side in the figure with respect to the horizontal position P1 of the paper 8 held by the paper feed tray 104a. The horizontal position P3 of the paper 8 held by the paper feed tray 104c is shifted to the right side in the figure.

  In the image forming apparatus according to the present embodiment, by including the paper feeding device 400 as described above, the horizontal position of the paper 8 fed by the paper feeding device 400 is set to the paper held by each of the paper feeding trays 104a to 104c. It will change every time the number of sheets of 8 are fed. The lateral position of the paper 8 fed by the paper feeding device 400 can be specified by determining which pickup roller is operating among the pickup rollers 401a to 401c, for example. It is also possible to specify the lateral position of the paper 8 fed by the paper feeding device 400 from the detection signal of the lateral position detection sensor 17 provided in the registration unit shift device. As in the first and second embodiments, the horizontal position information of the paper 8 fed by the paper feeding device 400 is output to the exposure control unit 203 and the shift control unit 204, thereby transferring the image. The lateral positions of the full-color toner image formed on the belt 10 and the sheet passing through the position of the sheet transfer unit 9 can be matched. In the shift unit 40, the sheet fed by the sheet feeding device 400 With the horizontal position of 8 as the reference position 24, it is possible to correct the positional deviation of the lateral edge of the paper 8 relative to the reference position 24 and to periodically shift the reference position 24.

  As described above in detail with reference to specific examples, in the image forming apparatus according to the present embodiment, the plurality of paper feed trays 104a to 104c of the paper feed device 400 have the same size of the paper 8 placed in the horizontal position. The paper 8 is held differently, and the paper 8 is sequentially taken out from the plurality of paper feed trays 104a to 104c and fed. Therefore, according to this image forming apparatus, the lateral position of the paper 8 fed from the paper feeding device 400 is changed every time the number of paper 8 held by the paper feed trays 104a to 104c is fed. Thus, the position in the nip portion of the fixing device 11 through which the lateral edge of the paper 8 passes can be dispersed over a wide range, and the wear of the fixing belt 11c of the fixing device 11 can be sufficiently reduced, and the life of the fixing belt 11c can be reduced. Can be improved.

  Further, the image forming apparatus according to the present embodiment changes the lateral position of the paper 8 fed from the paper feed tray 104 as in the case of the image forming apparatus according to the first embodiment or the second embodiment. Since the lateral position of the paper 8 is periodically shifted by the shift unit 40 of the registration unit shift device within a range of, for example, ± 1 mm, the wear of the fixing belt 11c is reduced. The wear of 11c can be reduced extremely effectively.

  Further, the image forming apparatus according to the present embodiment periodically shifts the lateral position of the sheet 8 by the shift unit 40 using the difference in the lateral position of the sheet 8 held in each of the sheet feed trays 104 a to 104 c of the sheet feeding device 400. By making it substantially equal to the amount, it is possible to minimize the deterioration of the alignment of the printed matter discharged to the discharge tray while extending the life of the fixing belt 11c.

  As described above, the first to third embodiments have been described as specific embodiments of the present invention. However, the present invention is not limited to the above-described embodiments as they are, and does not depart from the spirit of the present invention in the implementation stage. It can be embodied with various modifications and changes. For example, the above embodiment is an example in which the present invention is applied to a tandem image forming apparatus that forms a full-color image of four colors. However, the present invention transfers a toner image onto a recording medium to be conveyed. The present invention can be effectively applied to any image forming apparatus that fixes a toner image with the fixing device 11. In the above embodiment, the image forming apparatus including the belt fixing type fixing device 11 is exemplified. However, the present invention is also effective for an image forming apparatus including another type of fixing device such as a roller fixing type. Applicable.

DESCRIPTION OF SYMBOLS 1a-1d Image formation unit 8 Paper 9 Paper transfer device 10 Transfer belt 11 Fixing device 11c Fixing belt 40 Shift unit 104 (104a-104c) Paper feed tray 105 Paper feed stand 117 Motor 140 Knob 200 Control part 201 Non-volatile memory 202 Paper Detection sensor 300 Control unit 301 Non-volatile memory 302 Operation panel 400 Paper feed device 412a to 412c Side guide plate

JP 2008-24507 A JP 2010-2653 A

Claims (18)

A paper feed tray for holding a recording medium;
A lateral movement means for moving the recording medium held by the paper feed tray in a lateral direction perpendicular to the conveyance direction of the recording medium;
Transfer means for transferring a toner image onto a recording medium fed from the paper feed tray and conveyed;
Fixing means for heating and melting the toner image transferred onto the recording medium by the transfer means to fix it on the recording medium;
Image forming apparatus, comprising: a control unit configured to operate the lateral movement unit at a predetermined timing to change a lateral position that is a lateral position of the recording medium fed from the sheet feeding tray. apparatus. At least storage means for storing information on the initial position of the lateral position of the recording medium fed from the paper feed tray and the position after movement by the moving means;
The image forming apparatus according to claim 1, wherein the control unit sequentially changes the horizontal position of the recording medium fed from the paper feed tray to a position stored in the storage unit.   2. The control unit according to claim 1, wherein the horizontal position of the recording medium fed from the paper feed tray is changed each time a predetermined number of recording media are fed from the paper feed tray. The image forming apparatus according to 2.   4. The image forming apparatus according to claim 3, wherein the predetermined number of sheets is a number obtained by dividing the number of pages of a job to be executed by the number of the horizontal positions movable by the horizontal movement unit.   The control unit determines whether or not the job to be executed is a job including post-processing after image formation. If the job to be executed includes post-processing, the recording medium is fed from the paper feed tray. The horizontal position of the recording medium is fixed, and when the job to be executed does not include post-processing, the horizontal position of the recording medium fed from the paper feed tray is changed at a predetermined timing. The image forming apparatus as described in any one of -4. A first operation mode for changing the lateral position of the recording medium fed from the paper feed tray at a predetermined timing, and a second operation for fixing the lateral position of the recording medium fed from the paper feed tray. A receiving means for receiving an operation input for selecting one of the modes;
The control means changes the lateral position of the recording medium fed from the paper feed tray at a predetermined timing when the first operation mode is selected, and when the second operation mode is selected. The image forming apparatus according to claim 1, wherein the horizontal position of the recording medium fed from the paper feed tray is fixed.   The image forming apparatus according to claim 1, further comprising a lateral deviation correction unit that corrects a deviation of the lateral position of the recording medium at a transfer position of the toner image by the transfer unit.   The image forming apparatus according to claim 7, wherein the lateral deviation correcting unit periodically moves the lateral position after correction of the recording medium at the transfer position within a specified range.   The image forming apparatus according to claim 8, wherein an amount of movement of the recording medium in the horizontal direction by the lateral movement unit is substantially equal to an amount of movement by the lateral deviation correction unit. A paper feed tray for holding a recording medium;
A lateral movement means for moving a recording medium held by the paper feed tray in a lateral direction perpendicular to a conveyance direction of the recording medium in accordance with a user operation;
Transfer means for transferring a toner image onto a recording medium fed from the paper feed tray and conveyed;
Fixing means for heating and melting the toner image transferred onto the recording medium by the transfer means to fix it on the recording medium;
The present invention further comprises presentation means for presenting a timing for changing the lateral position, which is the lateral position of the recording medium fed from the paper feed tray, by operating the lateral movement means. Forming equipment.   The presenting means changes the horizontal position of the recording medium fed from the paper feed tray when a predetermined number of recording media are fed from the paper feed tray after the horizontal movement means is operated. The image forming apparatus according to claim 10, wherein information prompting the user to do so is presented.   The image forming apparatus according to claim 10, further comprising a lateral deviation correction unit that corrects a deviation of the lateral position of the recording medium at a transfer position of the toner image by the transfer unit.   The image forming apparatus according to claim 12, wherein the lateral deviation correcting unit periodically moves the lateral position after correction of the recording medium at the transfer position within a specified range.   The image forming apparatus according to claim 13, wherein an amount of movement of the recording medium in the horizontal direction by the lateral movement unit is substantially equal to an amount of movement by the lateral deviation correction unit. A plurality of paper feed trays for holding recording media of the same size so that lateral positions which are lateral positions orthogonal to the conveyance direction of the recording medium are different from each other;
Paper feeding means for sequentially taking out and feeding recording media from the plurality of paper feeding trays;
Transfer means for transferring a toner image onto a recording medium fed and conveyed by the paper feed means;
An image forming apparatus comprising: a fixing unit that heats and melts the toner image transferred onto the recording medium by the transfer unit and fixes the toner image on the recording medium.   The image forming apparatus according to claim 15, further comprising a lateral deviation correction unit that corrects a deviation of the lateral position of the recording medium at a transfer position of the toner image by the transfer unit.   The image forming apparatus according to claim 16, wherein the lateral deviation correcting unit periodically moves the lateral position after correction of the recording medium at the transfer position within a specified range.   18. The image forming apparatus according to claim 17, wherein the difference between the horizontal positions of the recording media held in the plurality of paper feed trays is substantially equal to a movement amount by the lateral deviation correction unit.

Images