JP2013112444A - Sheet conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device capable of suitably correcting a position in a width direction of a sheet relative to an image to be transferred.SOLUTION: The sheet conveying device includes a control roller 1 which nips a sheet 30 and shifts it in the width direction thereof, a reference sensor 5A which detects a position of one of the side edges of the sheet 30, a reference sensor 5B which detects a position of the other of the side edges of the sheet 30, the reference sensors 5A, 5B being disposed with a predetermined gap therebetween in the width direction of the sheet 30, and a lateral registration correction controller 3 which controls a shift of each sheet 30 by the control roller 1. The lateral registration correction controller 3 corrects a position of the sheet 30 in the width direction thereof by shifting the control roller 1 so that the center of the sheet 30 in the width direction thereof coincides with a predetermined target position according to the gap between the reference sensors 5A, 5B and the timing of detecting the sheet 30 by each of the reference sensors 5A, 5B upon causing the sheet 30 to shift in the width direction thereof.

Description

  The present invention relates to a sheet conveying apparatus, and more particularly to a technique for correcting a sheet width direction position of a sheet with respect to an image formed in an image forming apparatus.

  For image forming apparatuses such as copiers and printers, control for adjusting the sheet width direction position (horizontal registration position) of a sheet being conveyed to a predetermined position for the purpose of aligning with an image and ordering a bundle of sheets after paper discharge Is required. In response to such a request, the side edge position of the sheet is detected by the line sensor, and the roller holding the sheet is shifted in a direction orthogonal to the sheet conveying direction by a difference in distance from the target position. A control method has been proposed (see, for example, Patent Document 1).

JP 2008-189395 A

  In recent years, further improvement in accuracy has been demanded for correcting the position of the conveyed sheet in the sheet width direction, and the conventional control method cannot meet such a requirement.

  For example, in the above-described control method, one side edge position of the sheet (one position of a side substantially parallel to the sheet conveyance direction on the sheet) is adjusted to a predetermined target position. Therefore, the actual sheet width (width in the direction perpendicular to the sheet conveying direction and parallel to the sheet surface) is deviated from the standard value due to the sheet cutting accuracy and the contraction of the sheet after the fixing process. In this case, the center of the image in the width direction transferred to the sheet is shifted from the center of the sheet. If the sheet is shifted from an appropriate position with respect to the image to be transferred in this way, there arises a problem that the printed matter is not good-looking.

  An object of the present invention is to provide a sheet conveying apparatus capable of appropriately correcting the sheet width direction position of a sheet with respect to an image to be transferred and the sheet width direction position of each sheet when a plurality of sheets are bundled. .

  The sheet conveying apparatus according to the present invention corrects the position of the conveyed sheet in the sheet width direction by shifting the conveyed sheet in a sheet width direction parallel to the sheet surface and orthogonal to the sheet conveying direction. A shift unit that shifts the conveyed sheet in the sheet width direction; and one side edge position in the sheet width direction of the conveyed sheet that is disposed at a different position in the sheet width direction. A first detecting means for detecting; a second detecting means for detecting the other side edge position of the conveyed sheet in the sheet width direction; and between the first detecting means and the second detecting means. And the detection timing of the one side edge position by the first detection means when the conveyed sheet is shifted in the sheet width direction And the center of the conveyed sheet in the sheet width direction matches a predetermined target position based on the detection timing of the other side edge position by the second detection means and a predetermined standard width. Control means for driving the shift means as described above.

  According to the present invention, it is possible to accurately detect a deviation from a standard value and a subtle variation in the width of a sheet that is a correction target of the position in the sheet width direction. By correcting the sheet width direction position of the sheet based on the information thus detected, the sheet width direction position of the sheet with respect to the image formed by the image forming unit and the sheet width direction position of each sheet when a plurality of sheets are bundled Can be corrected appropriately.

1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet conveying device according to an embodiment. FIG. 5 is a diagram illustrating a detailed configuration of a lateral registration correction unit included in the sheet conveying apparatus and image forming apparatus according to the embodiment. FIG. 3 is a diagram schematically illustrating a process of correcting lateral registration of an A4 size sheet by the lateral registration correcting unit in FIG. 2. FIG. 4 is a diagram showing a positional relationship between a sheet and a reference sensor when the sheet width is deviated from a standard width of A4 size in comparison with the state of FIG. FIG. 4 is a diagram showing a state in which a lateral registration correction is performed on a sheet when the sheet width deviates from a standard width of A4 size, in contrast to the state of FIG. FIG. 3 is a diagram schematically illustrating a process of correcting lateral registration of a B5 size sheet by the lateral registration correcting unit of FIG. 2. FIG. 4 is a diagram showing a positional relationship between a sheet and a reference sensor when the sheet width is deviated from a standard width of B5 size in comparison with the state of FIG. FIG. 4 is a diagram showing a state in which the lateral registration correction is performed on the sheet when the sheet width is deviated from the standard width of the B5 size, in comparison with the state of FIG. 3 is a timing chart showing pulse output control in the lateral registration correction control unit of FIG. 2. 3 is a first flowchart of lateral registration correction control by a lateral registration correction control unit of FIG. 2. 6 is a second flowchart of lateral registration correction control by the lateral registration correction control unit of FIG. 2. 10 is a third flowchart of the lateral registration correction control by the lateral registration correction control unit of FIG. 2.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The sheet conveying apparatus according to the present invention performs, for example, sheet width direction position correction (hereinafter referred to as “lateral registration correction”) of an image transferred to a sheet in an image forming apparatus. Therefore, in this embodiment, an image forming apparatus including the sheet conveying device according to the present invention will be described.

<Schematic structure of image forming apparatus>
FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus including a sheet conveying device according to the present embodiment. The image forming apparatus includes an image forming unit 300 that forms an image on the sheet 30 and a sheet feeding unit 301 that feeds the sheet 30 to the image forming unit 300.

  The image forming unit 300 includes the photosensitive drum 16, the laser scanner 4, the charger 20, the developing device 22, and the cleaner 26. The photosensitive drum 16 as an image carrier is rotationally driven in the direction of arrow B (counterclockwise) shown in FIG. 1 by a motor (not shown). The laser scanner 4 irradiates the photosensitive drum 16 with laser light based on the image information, and forms an electrostatic latent image on the photosensitive drum 16.

  The charger 20 charges the photosensitive drum 16 uniformly. The charger 20 is provided upstream of the laser beam irradiation position by the laser scanner 4 in the rotation direction of the photosensitive drum 16. The developing device 22 develops the electrostatic latent image formed on the photosensitive drum 16 with toner to form a toner image. The developing device 22 is arranged on the downstream side of the laser light irradiation position in the rotation direction of the photosensitive drum 16. The cleaner 26 collects toner remaining on the photosensitive drum 16 without being transferred from the photosensitive drum 16 to the transfer belt 14 by a primary transfer charger 24 described later.

  The image forming unit 300 includes a transfer belt 14, a primary transfer charger 24, and a secondary transfer roller 28. The transfer belt 14 is endless and is wound around the roller 12, and rotates in the direction of arrow A shown in FIG. 1 as the roller 12 rotates. The primary transfer charger 24 is disposed at a position facing the photosensitive drum 16 with the transfer belt 14 interposed therebetween. The primary transfer charger 24 transfers the toner image 31 formed on the photosensitive drum 16 to the transfer belt 14. The secondary transfer roller 28 transfers the toner image 31 transferred to the transfer belt 14 to the sheet 30.

  The sheet feeding unit 301 includes a cassette 50 and a sheet conveying device 302. The cassette 50 is detachable from a main body (not shown) of the image forming apparatus and accommodates the sheet 30. Specific examples of the sheet 30 include recording paper and an OHP sheet. The sheet 30 is fed from the cassette 50 toward the image forming unit 300 by the paper feed roller 51.

  The sheet conveying device 302 is provided between the sheet feeding unit 301 and the image forming unit 300. The sheet 30 taken out from the cassette 50 by the paper feed roller 51 is sent to the skew feeding correction unit 303 by the transport roller 52 and the pre-registration roller 53.

  The skew correction unit 303 that performs the skew correction of the sheet 30 includes a skew correction control unit 9, a pair of skew correction rollers 2, and a pair of leading edge detection sensors 6. In the present embodiment, the leading edge detection sensor 6 is arranged at a predetermined interval in the width direction of the sheet 30 (a direction orthogonal to the sheet conveyance direction and parallel to the sheet surface), and the sheet on the leading edge side of the sheet 30 Detects the inclination with respect to the width direction.

  The skew correction controller 9 calculates the inclination of the sheet 30 based on the signal from the leading edge detection sensor 6 and outputs a control pulse of the skew correction roller 2 to a driver (not shown) of the skew correction roller 2. Each of the skew correction rollers 2 is arranged at a predetermined interval in the sheet width direction. The driver independently controls the rotational speed of the skew feeding correction roller 2 in accordance with the received control pulse. As a result, the skew of the sheet 30 is corrected.

  The sheet 30 is conveyed from the skew correction unit 303 to the lateral registration correction unit 304. In the lateral registration correction unit 304, lateral registration correction of the sheet 30 is performed. The lateral registration correction unit 304 includes a lateral registration control roller (hereinafter “control roller”) 1, a pair of lateral registration reference sensors (hereinafter “reference sensor”) 5, a lateral registration correction timing sensor (hereinafter “timing sensor”) 10, and a lateral registration correction roller 304. A registration correction control unit 3 is provided.

  The sheet width direction position of the sheet (hereinafter referred to as “horizontal registration position”) is corrected by shifting the control roller 1 holding the sheet 30 in the sheet width direction. The timing sensor 10 is a leading end detection unit that detects the leading end of the conveyed sheet 30. Based on the detection signal of the sheet 30 by the timing sensor 10, the lateral registration correction control unit 3 determines the timing for starting the lateral registration correction. Although details will be described later, based on the detection signal of the sheet 30 by the reference sensor 5, the lateral registration correction control unit 3 obtains the shift distance of the control roller 1 for correcting the lateral registration position of the sheet 30, and controls the control roller 1. Controls the shift operation.

  The lateral registration correction control unit 3 outputs a drive pulse for controlling the shift operation of the control roller 1 to a driver (not shown) of the control roller 1 based on signals from the reference sensor 5 and the timing sensor 10. The driver drives a shaft (not shown) of the control roller 1 in accordance with the received drive pulse. As a result, the lateral registration of the sheet 30 is corrected.

  By such skew correction and lateral registration correction, the accuracy of the posture and position of the sheet 30 with respect to the toner image 31 on the transfer belt 14 is improved. The detailed mode of the lateral registration correction of the sheet 30 in the lateral registration correction unit 304 will be described later.

  The sheet 30 is conveyed from the lateral registration correction unit 304 between the secondary transfer roller 28 and the transfer belt 14, where the toner image on the transfer belt 14 is transferred to the sheet.

  The image control unit 7 receives the laser light detection signal from the laser scanner 4 and transmits an image pulse corresponding to the image data to the laser scanner 4 in synchronization with the received laser light detection signal. The laser light detection signal is generated when laser light reflected by a polygon mirror that deflects laser light built in the laser scanner 4 is detected by a laser light detection sensor (not shown). The controller 8 temporarily stores image data transmitted from a PC or a reader (not shown), and transmits the image data to the image control unit 7 based on the image request signal and the horizontal synchronization signal from the image control unit 7. To do.

  The image controller 7 generates a horizontal synchronization signal based on the laser light detection signal. Further, the image control unit 7 receives, for example, a trigger signal from a CPU (not shown) that performs a sequence of the entire apparatus, and generates an image request signal. The controller 8 counts a predetermined number of horizontal synchronization signals based on the image request signal, and then transmits the image data to the image control unit 7 every predetermined number of lines in synchronization with the horizontal synchronization signal. The image data is converted into an image pulse having a pulse width corresponding to the data level in the image control unit 7.

<Image Forming Operation in Image Forming Apparatus>
When receiving a trigger signal indicating that image formation is to be performed from a CPU (not shown), the image control unit 7 outputs an image request signal to the controller 8. Based on the image request signal, the controller 8 transmits image data to the image control unit 7 in synchronization with the horizontal synchronization signal. The image control unit 7 transmits an image pulse corresponding to the received image data to the laser scanner 4.

  The laser scanner 4 rotates laser light corresponding to the received image pulse or laser light modulated based on image data corresponding to data from an image memory (not shown) in the direction of arrow B shown in FIG. Irradiate onto the photosensitive drum 16. At this time, the photosensitive drum 16 is uniformly charged by the charger 20 in advance. Therefore, an electrostatic latent image is formed on the photosensitive drum 16 by irradiation with laser light.

  The electrostatic latent image is developed by the developing device 22 to form a toner image. The toner image formed on the photosensitive drum 16 is transferred onto the transfer belt 14 by the action of the primary transfer bias voltage applied by the primary transfer charger 24.

  On the other hand, in synchronization with a trigger signal issued from the CPU, the sheet 30 is sent from the cassette 50 to the image forming unit 300 by the paper feed roller 51. This trigger signal is generated at a timing at which the position of the sheet 30 properly matches the toner image 31 during the secondary transfer. The sheet 30 is conveyed to the pre-registration roller 53 through the conveyance rollers 52 arranged at two places. Sensors (not shown) for detecting the sheet 30 are arranged in the vicinity of each of the conveyance rollers 52. The CPU drives the conveying roller 52 through a drive control unit (not shown) based on the sheet passage detection signals from these sensors.

  The sheet 30 is conveyed to the skew feeding correction unit 303 by the pre-registration roller 53. The skew of the sheet 30 is corrected when passing through the skew correction unit 303. In the skew correction unit 303, the skew correction control unit 9 calculates the time difference of the leading edge detection sensor 6 that detects the leading edge of the sheet 30 as the skew feeding amount. The skew correction control unit 9 performs skew correction by decelerating the preceding roller of the pair of skew correction rollers 2 arranged at regular intervals in the sheet width direction. The skew correction control unit 9 calculates the deceleration target speed so that the integral value of the speed difference between the constant speed and the deceleration target speed in the deceleration time region becomes the skew amount.

  The sheet 30 subjected to the skew correction in the skew correction unit 303 is conveyed to the lateral registration correction unit 304. A lateral registration correction unit 304 performs lateral registration correction on the sheet 30. The configuration of the lateral registration correction unit 304 and the lateral registration correction control will be described in detail later.

  The sheet 30 that has passed through the lateral registration correction unit 304 is further conveyed while being sandwiched between the transfer belt 14 and the secondary transfer roller 28, and at this time, the toner image 31 on the transfer belt 14 is transferred by the secondary transfer roller 28. Transferred to the sheet 30. Thereafter, the sheet 30 is conveyed to a fixing unit (not shown). In the fixing unit, the toner image 31 is fixed to the sheet 30 by heating and pressing.

<Configuration and operation of horizontal registration correction unit>
FIG. 2 is a diagram illustrating a detailed configuration of the lateral registration correction unit 304. A portion surrounded by a broken line in FIG. 2 is the lateral registration correction control unit 3 shown in FIG. FIG. 9 is a timing chart showing pulse output control in the lateral registration correction control unit 3. In the following description regarding FIG. 2, FIG. 9 will be referred to as appropriate.

  The pair of reference sensors 5 shown in FIG. 1 are shown in FIG. 2 as a reference sensor 5A as a first detection means and a reference sensor 5B as a second detection means. In this embodiment, the arrangement interval between the reference sensors 5A and 5B is set to 275 mm. This '275 mm' is a substantially intermediate value between the A4 size width '297 mm' and the B5 size width '257 mm'.

  In the skew correction unit 303, the leading edge of the sheet 30 subjected to skew correction is detected by the timing sensor 10 while being conveyed by the control roller 1. Each of the reference sensors 5A and 5B and the timing sensor 10 outputs a signal “1” when the sheet 30 is detected and outputs a signal “0” when the sheet 30 is not detected.

  In a preliminary shift operation and a lateral registration correction operation described later, the reference sensor 5A is positioned on one side edge (side edge) of the sheet 30, that is, a side on the reference sensor 5A side that is substantially parallel to the sheet conveyance direction in the sheet 30. Is detected to switch between the ON state and the OFF state. Similarly, the reference sensor 5B switches between the ON state and the OFF state by detecting the other side edge of the sheet 30 (side on the reference sensor 5B side substantially parallel to the sheet conveyance direction in the sheet 30).

  In the lateral registration correction control unit 3, when the trigger generation unit 100 receives the signal “1” from the timing sensor 10, it determines each state of the reference sensors 5 </ b> A and 5 </ b> B. In FIG. 2, when the sheet 30 is in the state (1), the reference sensor 5A is in an OFF state and the reference sensor 5B is in an ON state. At this time, a signal of “0” is input to the trigger generation unit 100 via the inverter 200 and the AND gate 201.

  When the trigger generation unit 100 receives the signal “1” from the timing sensor 10 and determines that the signal from the AND gate 201 is “0”, the trigger generation unit 100 transmits a preliminary shift start signal to the pulse generation unit 101 (FIG. 9 at time t1). The preliminary shift start signal is a signal for causing the control roller 1 to perform a preliminary shift operation for shifting the sheet 30 in the state (1) in FIG. The preliminary shift operation is an operation of shifting the control roller 1 holding the sheet 30 in the arrow R direction so that the reference sensor 5A is ON and the reference sensor 5B is OFF as shown in (2) of FIG. is there.

  Upon receipt of the preliminary shift start signal, the pulse generator 101 drives the motor 41 that shifts the control roller 1 with a drive pulse and “0” as a CW (forward rotation) / CCW (reverse rotation) signal. Output to. At this time, the pulse generation unit 101 generates drive pulses for the motor 41 so that the pulse rate per second transitions from 'P0' to 'P1' (time t1 to t2 in FIG. 9). The CW / CCW signal is a signal that controls driving of the motor 41.

  The driver 40 receives the pulse and the CW / CCW signal “0” and rotates the motor 41. Here, the shaft of the control roller 1 is connected to the belt 42 by the connecting member 44, and the belt 42 is stretched between the shaft of the motor 41 and the hanging shaft 43. When the motor 41 is rotated, the belt 42 is rotated, and the shaft of the control roller 1 is slid in the length direction. That is, the shift operation of the control roller 1 in the sheet width direction is realized by converting the rotational displacement of the shaft of the motor 41 into the linear displacement of the control roller 1. In the preliminary shift operation, the control roller 1 is shifted in the arrow R direction according to the rotation of the motor 41.

  The preliminary shift operation is performed until the reference sensor 5A is turned on and the reference sensor 5B is turned off. When the reference sensor 5A is in the ON state and the reference sensor 5B is in the OFF state, the output from the AND gate 201 is “1”. The trigger generation unit 100 receives the output “1” from the AND gate 201 and transmits a preliminary shift stop signal to the pulse generation unit 101 (time t3 in FIG. 9).

  Upon receiving the preliminary shift stop signal, the pulse generation unit 101 generates a drive pulse for the motor 41 so that the pulse rate per second transitions from 'P1' to 'P0' (time t3 in FIG. 9). t4). Thus, the preliminary shift operation is completed. As a result of the preliminary shift operation, the seat 30 is in the state (2) in FIG. 2, that is, the side edge on the reference sensor 5A side of the seat 30 is always in the state of being advanced in the direction of arrow R beyond the reference sensor 5A. .

  After completion of the preliminary shift operation, a lateral registration correction operation is performed to correct the lateral registration position of the sheet 30 by shifting the control roller 1 by a certain distance in the direction opposite to the shift direction of the sheet 30 in the preliminary shift operation. The trigger generation unit 100 transmits a horizontal registration shift start signal instructing the start of the horizontal registration correction operation to the pulse generation unit 101. In response to the lateral registration shift start signal, the pulse generator 101 outputs a pulse and the CW / CCW signal “1” (time t5 in FIG. 9).

  At this time, the pulse generation unit 101 generates drive pulses for the motor 41 so that the pulse rate per second transitions from ‘P0’ to ‘P2’ (time t5 to t6 in FIG. 9). As a result, the drive transmission mechanism related to the shift driving of the control roller 1 described above operates, so that the sheet 30 is shifted in the arrow L direction (lateral registration shift direction) together with the control roller 1.

  In the present embodiment, the side edge of the sheet 30 on the side of the reference sensor 5A passes through the reference sensor 5A so that the pulse rate reaches 'P2' before the reference sensor 5A is turned off. Make the shift speed reach a constant speed.

  The lateral registration correction of the sheet 30 after time t6 differs depending on the relationship between the width of the sheet 30 and the interval between the reference sensors 5A and 5B, and will be described separately for each case. However, in any case, the center of the toner image 31 and the center of the sheet 30 in the width direction on the transfer belt 14 are aligned. In this embodiment, shift control of the control roller 1 is performed such that a position 180 mm away from the reference sensor 5 </ b> A in the sheet width direction is a horizontal registration target position, and the center in the width direction of the sheet 30 is at this horizontal registration target position. .

<A4 size sheet lateral registration correction>
The case where the sheet 30 is A4 size will be further described with reference to FIG. First, a case where the size of the sheet 30 matches the standard value of the A4 size will be described.

  FIG. 3 is a diagram schematically showing a process for correcting the lateral registration of the A4 size sheet 30. As shown in FIG. The sheet width of the A4 size is 297 mm, which is longer than the interval 275 mm between the reference sensors 5A and 5B. Therefore, as shown in FIG. 3A, when the reference sensor 5B detects the side edge of the sheet 30 during the shift of the sheet 30 in the arrow L direction (lateral registration shift direction), the reference sensor 5A It remains detected.

  When the outputs from the reference sensors 5A and 5B are both "1", the output from the AND gate 202 is "1". On the other hand, as shown in FIG. 2, the lateral registration shift start signal output from the trigger generation unit 100 is also input to the ON / ON counter 102. The ON / ON counter 102 is in a standby state by the input of a lateral registration shift start signal. The ON / ON counter 102 starts counting pulses using the output ‘1’ from the AND gate 202 as an enable signal.

  Thereafter, when the shift of the sheet 30 proceeds and the state shown in FIG. 3B is reached, the output from the reference sensor 5A becomes “0” at the detection timing of the sheet edge when the reference sensor 5A changes from the ON state to the OFF state. As a result, the output from the AND gate 202 becomes “0”. The ON / ON counter 102 receives the output “0” from the AND gate 202 and stops counting pulses.

  As shown in FIG. 3B, if the width of the sheet 30 matches 297 mm which is the standard value of the A4 size, the distance from the reference sensor 5B to the side edge on the reference sensor 5B side of the sheet 30 is 22 mm. It becomes. Therefore, the count value of the ON / ON counter 102 is a value obtained by dividing 22 mm by the shift distance of the sheet 30 per pulse. For example, if the shift distance of the sheet 30 per pulse is 0.05 mm, the count value is 440 (= 22 / 0.05). Thus, in this embodiment, the distance to shift the control roller 1 (the distance to shift the sheet 30) in the lateral registration correction operation is the shift distance of the control roller 1 per pulse and the number of pulses for driving the motor 41. Is defined by the count value.

  The ON / ON counter 102 uses the count value indicating the distance (detection distance) at which both of the reference sensors 5A and 5B are ON during the lateral registration correction operation as the ON / ON pulse number to the shift pulse number adjusting unit 105. Output. The shift pulse number adjusting unit 105 receives the ON / ON pulse number from the ON / ON counter 102 and outputs the adjusted horizontal registration shift pulse number to the pulse generating unit 101 as follows.

  That is, the ON / ON standard pulse number and the OFF / OFF standard pulse number are distributed from the controller 8 to the shift pulse number adjusting unit 105 according to the size of the sheet to be conveyed.

  The number of ON / ON standard pulses is the number of pulses during a period in which both of the reference sensors 5A and 5B are ON during the lateral registration correction operation when a sheet of a certain size is conveyed. Since the sheet shift distance per pulse is constant, the number of ON / ON standard pulses indicates the distance (standard detection distance) at which both the reference sensors 5A and 5B are ON during the lateral registration correction operation.

  Similarly, the number of OFF / OFF standard pulses is the number of pulses during a period in which both the reference sensors 5A and 5B are OFF during the lateral registration correction operation when a sheet of a certain size is conveyed. It is. Since the shift distance of the sheet per pulse is constant, the OFF / OFF standard pulse number indicates a distance (standard non-detection distance) at which both the reference sensors 5A and 5B are turned off during the lateral registration correction operation.

  Therefore, when an A4 size sheet is conveyed, the above-mentioned “440” is delivered to the shift pulse number adjustment unit 105 as the ON / ON standard pulse number and “0” as the OFF / OFF standard pulse number. .

  On the other hand, the number of lateral registration shift pulses is distributed from the controller 8 to the shift pulse number adjusting unit 105. The number of lateral registration shift pulses represents a shift distance (standard shift distance) corresponding to the sheet size from the reference sensor 5A when a sheet matching the standard width is shifted.

  Under such circumstances, when the shift pulse number adjusting unit 105 receives the ON / ON pulse number from the ON / ON counter 102, the shift pulse number adjusting unit 105 compares it with the ON / ON standard pulse number (that is, the detection distance and the standard detection distance). Compare). When these pulse numbers match, the shift pulse number adjusting unit 105 determines that the sheet width during the lateral registration correction operation matches the standard width. Here, since the ON / ON pulse number ‘440’ and the ON / ON standard pulse number ‘440’ are the same, it is determined that the width of the sheet 30 matches the standard width of the A4 size.

  When the width of the sheet 30 matches the standard width of the A4 size, as shown in FIG. 3C, the center of the toner image in the width direction is at a position 180 mm away from the reference sensor 5A. Therefore, in order to match the center of the A4 size sheet 30 with the center of the toner image in the width direction, the side edge on the reference sensor 5A side of the sheet 30 is positioned 31.5 mm (standard shift distance) from the reference sensor 5A. To match.

  Therefore, “630 (= 31.5 mm / 0.05 mm)” is set as the number of lateral registration shift pulses. When the width of the sheet 30 matches the standard width of the A4 size, the shift pulse number adjusting unit 105 does not adjust the horizontal registration shift pulse number, and “630” is set as the adjusted horizontal registration shift pulse number. Send to.

  After starting the lateral registration correction of the sheet 30, the pulse generation unit 101 outputs a pulse output by itself with reference to a signal of “0” indicating that the reference sensor 5A transmitted through the inverter 206 is in an OFF state. Has started counting. The pulse generation unit 101 latches the number of adjusted lateral registration shift pulses at the timing of receiving the signal “1” output from the AND gate 207 (time t7 in FIG. 9). At time t7 in FIG. 9, a signal “1” is output from the AND gate 207 at the detection timing when the reference sensor 5A is OFF (the reference sensor 5B is in the ON state).

  Thereafter, the pulse generator 101 lowers the shift speed of the sheet 30 (control roller 1) by lowering the pulse rate of the pulse from 'P2' as shown in FIG. The pulse output is stopped when the number of pulses being counted matches the adjusted horizontal registration shift pulse number ‘630’ (time t <b> 8 in FIG. 9). The hatched portion S shown in the timing chart of the pulse rate in FIG. 9 corresponds to the number of pulses '630' after the side edge of the sheet 30 on the reference sensor 5A side passes through the reference sensor 5A. The value obtained by multiplying the number of pulses '630' by the distance per pulse (0.05 mm) is 31.5 mm. In this way, the state shown in FIG. 3C is realized, and the lateral registration correction operation of the sheet 30 is completed.

  Next, a case where the actual width of the sheet 30 deviates from the standard width due to a cutting error, shrinkage after fixing, or the like, that is, a case where the actual sheet width of the sheet 30 does not match the standard width will be described. Note that when forming an image on the second side when forming images on both sides of the sheet 30, the width of the sheet 30 may not match the standard width due to shrinkage due to the fixing process.

  FIG. 4 is a diagram showing the positional relationship between the sheet 30 and the reference sensor 5B when the width of the A4 size sheet 30 does not match the standard width of the A4 size, in comparison with the state of FIG. is there. FIG. 5 compares the state in which the lateral registration correction is performed on the sheet 30 when the width of the A4 size sheet 30 does not match the standard width of the A4 size with the state of FIG. FIG. 4 shows only the vicinity of the reference sensor 5B, and FIG. 5 shows only the vicinity of the reference sensor 5A.

  Although not shown in the state of FIG. 4, the side edge of the sheet 30 on the side of the reference sensor 5A matches the reference sensor 5A (see FIG. 3B). When the width of the sheet 30 is shorter than the standard value by ΔD1 mm, the number of ON / ON pulses output from the ON / ON counter 102 is reduced by “ΔD1 / 0.05” than the above-mentioned “440”. This ON / ON pulse number ‘440−ΔD1 / 0.05’ is transmitted to the shift pulse number adjusting unit 105.

  The shift pulse number adjusting unit 105 compares the ON / ON pulse number “440−ΔD1 / 0.05” with the ON / ON standard pulse number “440”, and as a result, the width direction length of the sheet 30 is the standard value. It is judged that it is shorter. In this case, since the necessary shift distance is 31.5 mm + ΔD1 / 2 mm, the number of adjusted lateral registration pulses is transmitted to the pulse generator 101 by “(ΔD1 / 2) /0.05” larger than “630”. .

  Accordingly, as shown in FIG. 5, the sheet edge on the reference sensor 5A side is adjusted to a position of 31.5 mm + ΔD1 / 2 mm from the reference sensor 5A. Thus, as in the case where the width of the sheet 30 is the standard value, the center of the toner image and the center of the sheet 30 coincide with each other at a position 180 mm away from the reference sensor 5A.

  On the other hand, as shown in FIG. 4, when the width of the sheet 30 is longer than the standard value by ΔD2 mm, the number of ON / ON pulses output by the ON / ON counter 102 is “ΔD2 // than the above-mentioned“ 440 ”pulse. Increase by 0.05 '. This pulse number “440 + ΔD2 / 0.05” is transmitted to the shift pulse number adjusting unit 105. The shift pulse number adjusting unit 105 compares the ON / ON pulse number “440 + ΔD2 / 0.05” with the ON / ON standard pulse number “440”.

  The shift pulse number adjusting unit 105 determines that the length in the width direction of the sheet 30 is longer than the standard value, and the number of adjusted lateral registration pulses is smaller than “630” by (ΔD2 / 2) /0.05. The number is transmitted to the pulse generator 101. Accordingly, as shown in FIG. 5, the sheet edge on the reference sensor 5A side is adjusted to a position of 31.5 mm−ΔD2 / 2 mm from the reference sensor 5A. Thus, as in the case where the width of the sheet 30 matches the standard value, the center of the toner image and the center of the sheet 30 in the width direction match at a position 180 mm away from the reference sensor 5A.

《B-5 size sheet lateral registration correction》
The case where the sheet 30 is B5 size will be described with reference to FIG. FIG. 6 is a diagram schematically illustrating a process for correcting lateral registration of the B5 size sheet 30. As illustrated in FIG. The width of the B5 size sheet 30 is 257 mm, which is shorter than the interval 275 mm between the reference sensors 5A and 5B. In this case, as shown in FIG. 6A, at the moment when the reference sensor 5A is turned off during the lateral registration correction operation of the sheet 30, the reference sensor 5B remains in the OFF state.

  The lateral registration shift start signal output from the trigger generation unit 100 is also input to the OFF / OFF counter 103 (see FIG. 2). Further, the OFF / OFF counter 103 is in a standby state by the input of a lateral registration shift start signal.

  When the outputs from the reference sensors 5A and 5B are both “0”, the output from the AND gate 205 via the inverters 203 and 204 is “1”. The OFF / OFF counter 103 starts counting pulses using the output “1” from the AND gate 205 as an enable signal.

  Thereafter, the shift of the sheet 30 proceeds, and as shown in FIG. 6B, when the reference sensor 5B is turned ON, the output from the AND gate 205 becomes “0”. The OFF / OFF counter 103 receives the output “0” from the AND gate 205 and stops counting pulses.

  As shown in FIG. 6B, if the width of the sheet 30 matches the standard value 257 mm of the B5 size, the distance from the reference sensor 5A to the sheet edge on the reference sensor 5A side of the sheet 30 is 18 mm (non- Detection standard distance). Therefore, the count value of the OFF / OFF counter 103 is a value obtained by dividing 18 mm by the moving distance of the sheet 30 per pulse. As described above, since the moving distance of the sheet 30 per pulse is 0.05 mm as described above, the count value output by the OFF / OFF counter 103 is “360 (= 18 / 0.05)”.

  The OFF / OFF counter 103 uses this count value indicating the distance (non-detection distance) at which both of the reference sensors 5A and 5B are OFF during the lateral registration correction operation as the OFF / OFF pulse number to the shift pulse number adjusting unit 105. Output. The shift pulse number adjusting unit 105 receives the OFF / OFF pulse number and outputs the adjusted horizontal registration shift pulse number to the pulse generating unit 101 as follows.

  When a B5 size sheet is conveyed, the shift pulse number adjusting unit 105 receives “360” as the OFF / OFF standard pulse number and “0” as the ON / ON standard pulse number from the CPU (not shown). Has been delivered. When receiving the number of OFF / OFF pulses from the OFF / OFF counter 103, the shift pulse number adjusting unit 105 compares the OFF / OFF standard pulse number (that is, compares the non-detection distance with the standard non-detection distance). . When these pulse numbers match, the shift pulse number adjusting unit 105 determines that the sheet width during the lateral registration correction operation matches the standard width. Here, since the OFF / OFF pulse number ‘360’ and the OFF / OFF standard pulse number ‘360’ are the same, it is determined that the sheet 30 matches the standard width of the B5 size.

  As shown in FIG. 6C, the center of the toner image in the width direction is at a position 180 mm away from the reference sensor 5A. Therefore, in order to make the center of the B5 size sheet 30 and the center of the toner image coincide with each other in the width direction, the side edge of the sheet 30 on the reference sensor 5A side can be adjusted to 51.5 [mm] from the reference sensor 5A. That's fine.

  Therefore, '1030 (= 51.5 / 0.05)' is set as the number of lateral registration shift pulses. When the width of the B5 size sheet 30 matches the standard width of the B5 size, the shift pulse number adjusting unit 105 does not adjust the horizontal registration shift pulse number, and pulses “1030” as the adjusted horizontal registration shift pulse number. The data is transmitted to the generation unit 101.

  The pulse generator 101 outputs a pulse output by itself with reference to a signal of level “0” indicating that the reference sensor 5A transmitted through the inverter 206 is in the OFF state after the lateral registration shift of the sheet 30 is started. Has started counting. The pulse generation unit 101 latches the number of adjusted lateral registration shift pulses at the timing of receiving the signal “1” output from the AND gate 207 (time t7 in FIG. 9).

  Thereafter, the pulse generator 101 lowers the pulse rate of the pulse from 'P2' as shown in FIG. 9, and when the number of pulses being counted matches the number of adjusted lateral registration shift pulses '1030' (FIG. 9). The pulse output is stopped at time t8). In FIG. 9, the hatched portion S shown in the pulse rate timing chart corresponds to the number of pulses '1030' after the edge of the sheet 30 on the reference sensor 5A side passes through the reference sensor 5A. A value obtained by multiplying the number of pulses '1030' by the distance per pulse is 51.5 mm. Thus, the state shown in FIG. 6C is realized, and the lateral registration correction operation of the sheet 30 is completed.

  Next, a case where the width of the sheet 30 deviates from the standard width due to a cutting error, shrinkage after fixing, or the like, that is, a case where the sheet width and the standard width do not match will be described. FIG. 7 is a diagram showing the positional relationship between the sheet 30 and the reference sensor 5A when the width of the B5 size sheet 30 does not match the standard width of the B5 size, in comparison with the state of FIG. 6B. is there. 8 compares the state in which the lateral registration correction is performed on the sheet 30 when the width of the B5 size sheet 30 does not match the standard width of the B5 size with the state of FIG. FIG. 7 and 8 show only the vicinity of the reference sensor 5A.

  In the state of FIG. 7, although not shown, the side edge of the sheet 30 on the side of the reference sensor 5B matches the reference sensor 5A (see FIG. 6B). At this time, if the width of the sheet 30 is longer than the standard value by ΔD3 mm, the number of OFF / OFF pulses output by the OFF / OFF counter 103 is smaller by “ΔD3 / 0.05” than the above-mentioned “360”. . This OFF / OFF pulse number ‘360−ΔD3 / 0.05’ is transmitted to the shift pulse number adjusting unit 105. The shift pulse number adjusting unit 105 compares the OFF / OFF pulse number “360−ΔD3 / 0.05” with the OFF / OFF standard pulse number “360”.

  The shift pulse number adjusting unit 105 determines that the width direction length of the sheet 30 is longer than the standard value, and the adjusted horizontal registration pulse number is smaller than “1030” by (ΔD3 / 2) /0.05. The number of pulses is transmitted to the pulse generator 101. Thereby, as shown in FIG. 8, the sheet edge on the reference sensor 5A side is adjusted to a position of 51.5 mm−ΔD3 / 2 mm from the reference sensor 5A. Thus, as in the case where the width of the sheet 30 matches the standard value, the center of the toner image and the center of the sheet 30 in the width direction match at a position 180 mm away from the reference sensor 5A.

  On the other hand, as shown in FIG. 7, when the width of the sheet 30 is shorter than the standard value by ΔD4 mm, the number of OFF / OFF pulses output by the OFF / OFF counter 103 is “ΔD4 / Increase by 0.05 '. This OFF / OFF pulse number ‘360 + ΔD4 / 0.05’ is transmitted to the shift pulse number adjusting unit 105. The shift pulse number adjusting unit 105 compares the OFF / OFF pulse number “360 + ΔD4 / 0.05” with the ON / ON standard pulse number “440”.

  The shift pulse number adjustment unit 105 determines that the length in the width direction of the sheet 30 is shorter than the standard value, and the adjustment horizontal registration pulse number is larger than “1030” by (ΔD4 / 2) /0.05. The number of pulses is transmitted to the pulse generator 101. Thereby, as shown in FIG. 8, the sheet edge on the reference sensor 5A side is adjusted to a position of 51.5 mm + ΔD4 / 2 mm from the reference sensor 5A. Thus, as in the case where the width of the sheet 30 matches the standard value, the center of the toner image and the center of the sheet 30 in the width direction match at a position 180 mm away from the reference sensor 5A.

<Horizontal registration correction control flow>
A control flow of the lateral registration correction described above by the lateral registration correction control unit 3 will be described again with reference to a flowchart. 10, 11, and 12 are flowcharts of the lateral registration correction control described above by the lateral registration correction control unit 3. Here, the above-described lateral registration correction control is generalized and described, and therefore the sheet width is handled as a variable.

  First, description of the control flow will be started with reference to FIG. 10 (first flowchart). The trigger generation unit 100 determines whether or not the timing sensor 10 has detected the skew-corrected sheet conveyed from the skew correction unit 303 (step S1). If “NO” in the step S1, the trigger generating unit 100 repeats the step S1. If “YES” in the step S1, the trigger generation unit 100 determines whether or not the reference sensor 5A is ON and the reference sensor 5B is OFF (step S2).

  If “NO” in the step S 2, the trigger generation unit 100 transmits a preliminary shift start signal to the pulse generation unit 101. In response to the preliminary shift start signal, the pulse generator 101 performs preliminary shift operation control (step S3). If “YES” in the step S 2, the trigger generating unit 100 transmits a lateral registration shift start signal to the pulse generating unit 101. In response to the lateral registration shift start signal, the pulse generator 101 starts lateral registration shift operation control (step S4).

  The lateral registration correction control unit 3 determines whether the reference sensor 5B is turned on (step S5). The subsequent processing in the case of “NO” in step S5 will be described later with reference to FIG. If “YES” in the step S5, the pulse output is controlled as follows according to the ON / OFF timing relationship of the reference sensors 5A and 5B.

  The lateral registration correction control unit 3 determines whether the reference sensor 5A is turned off at the same time when the reference sensor 5B is turned on (step S7). If “YES” in the step S7, the pulse generating unit 101 starts a pulse count (step S8). Then, the shift pulse number adjusting unit 105 checks whether the ON / ON standard pulse number is “0” (step S9).

  Here, when the standard width of the size of the conveyed sheet is longer than the interval between the reference sensors 5A and 5B, the difference between the standard width of the sheet and the interval between the reference sensors 5A and 5B is set to 'δ'. Further, the distance that the shaft of the motor 41 is rotationally driven and the control roller 1 is shifted when the pulse generating unit 101 outputs one pulse is denoted by ‘γ’. Then, the number of ON / ON standard pulses is represented by 'δ / γ'.

  Therefore, for example, it is assumed that the shift distance of the control roller 1 in one pulse is 0.25 mm and the number of ON / ON standard pulses is 10. In this case, the standard width of the sheet is longer than the interval between the reference sensors 5A and 5B by 2.5 mm. Therefore, during the lateral registration shift of the sheet, both the reference sensors 5A and 5B are in the ON state while the pulse is output ten times.

  If it is determined in step S7 that the reference sensor 5B is turned on and the reference sensor 5A is turned off simultaneously during the lateral registration shift of the sheet, the distance between the reference sensors 5A and 5B and the sheet width are equal. If “NO” is set in step S9, that is, if a certain value is set as the number of ON / ON standard pulses, the sheet width is smaller than the standard width ((the control roller 1 when one pulse is applied to the motor 41). Shift distance) × (number of ON / ON standard pulses) ′. Therefore, the shift pulse number adjusting unit 105 adds “(ON / ON standard pulse number) / 2” to “horizontal registration shift pulse number” and adds the number of pulses to the pulse generation unit 101 as the adjusted horizontal registration shift pulse number. Transmit (step S11).

  The pulse generation unit 101 determines whether the received number of adjusted lateral registration shift pulses matches the count value of the pulse generation unit 101 (step S12). If “NO” in the step S12, the determination in the step S12 is repeated. When “YES” is determined in the step S12, the lateral registration shift is ended. In this way, the center of the toner image and the center of the sheet in the width direction match.

  If “YES” in the step S9, that is, if the ON / ON standard pulse number is “0”, the shift pulse number adjusting unit 105 checks whether the OFF / OFF standard pulse number is “0” (step S9). S10). If “NO” in the step S10, the standard width of the sheet is “(shift distance of the control roller 1 when one pulse is applied to the motor 41) × (OFF / OFF standard pulse number)”. It is shorter than the interval of 5B.

  Here, the width of the sheet is equal to the interval between the reference sensors 5A and 5B. Therefore, the shift pulse number adjusting unit 105 determines that the sheet width is longer than the standard width by “(shift distance of the control roller 1 when one pulse is applied to the motor 41) × (OFF / OFF standard pulse number)”. to decide. The shift pulse number adjusting unit 105 transmits a pulse number obtained by subtracting “(OFF / OFF standard pulse number) / 2” from “horizontal registration shift pulse number” to the pulse generating unit 101 as an adjusted horizontal registration shift pulse number ( Step S13).

  If “YES” in the step S10, that is, if the number of OFF / OFF standard pulses is 0, the standard width of the sheet is equal to the interval between the reference sensors 5A and 5B. In this case, the shift pulse number adjusting unit 105 determines that the sheet width matches the standard width. Then, the shift pulse number adjusting unit 105 reflects the set number of horizontal registration shift pulses as it is in the control as it is without adjusting the set number of horizontal registration shift pulses (step S14).

  After steps S13 and S14, the process proceeds to step S12. Since the process of step S12 has already been described, a description thereof will be omitted.

  Next, the control flow in the case of “NO” in step S7 will be described with reference to FIG. 11 (second flowchart). If “NO” in the step S7 (when the sensors of the reference sensors 5A and 5B are both turned on during the sheet shift), the ON / ON counter 102 starts counting pulses (step S15). Then, the ON / ON counter 102 determines whether the reference sensor 5A has been turned off (step S16).

  If “NO” in the step S16, the ON / ON counter 102 continues the pulse count until the reference sensor 5A is turned off. If “YES” in the step S16, the ON / ON counter 102 stops the pulse count and transmits the count value to the shift pulse number adjusting unit 105 as the ON / ON pulse number, and at the same time, the pulse generating unit 101 Starts the pulse count (step S17).

  Subsequently, the shift pulse number adjustment unit 105 checks whether the ON / ON standard pulse number is “0” (step S18). If “NO” in step S18, the standard width of the sheet is greater than the distance between the reference sensors 5A and 5B (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × (ON / ON standard pulse). Number) 'will be long. Therefore, the shift pulse number adjusting unit 105 determines whether the ON / ON pulse number is smaller than the ON / ON standard pulse number (step S19).

  If “YES” in the step S19, the sheet width is larger than the standard width (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × [(ON / ON standard pulse number) − (ON / The number of ON pulses)] 'is shorter. Therefore, the shift pulse number adjustment unit 105 calculates the number of pulses obtained by adding “[(ON / 0N standard pulse number) − (ON / ON pulse number)] / 2” to “horizontal registration shift pulse number”. The number of shift pulses is determined (step S20).

  If “NO” in the step S19, the sheet width is larger than the standard width (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × [(ON / ON pulse number) − (ON / ON The number of standard pulses)] 'will be longer. Therefore, the shift pulse number adjusting unit 105 calculates the number of pulses obtained by subtracting “[(ON / ON pulse number) − (ON / ON standard pulse number)] / 2” from “horizontal registration shift pulse number”. The number of shift pulses is determined (step S21).

  The adjusted lateral registration shift pulse numbers determined in steps S20 and S21 are transmitted to the pulse generation unit 101, and then the process proceeds to step S12. Since the process of step S12 has already been described, a description thereof will be omitted.

  If “YES” in the step S18, the shift pulse number adjusting unit 105 confirms whether the OFF / OFF standard pulse number is “0” (step S32). If “NO” in the step S32, the sheet width is larger than the standard width (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × [(ON / ON pulse number) + (OFF / OFF The number of standard pulses)] 'will be longer.

  Therefore, the shift pulse number adjusting unit 105 calculates the number of pulses obtained by subtracting “[(ON / ON pulse number) + (OFF / OFF standard pulse number)] / 2” from “horizontal registration shift pulse number”. The number of shift pulses is determined (step S33).

  If “YES” in the step S32, both the ON / ON standard pulse number and the OFF / OFF standard pulse number are “0”. In this case, the width of the sheet is longer than the standard width by “(shift distance of the control roller 1 when one pulse is applied to the motor 41) × (number of ON / ON pulses)”. Therefore, the shift pulse number adjusting unit 105 determines the number of pulses obtained by subtracting “(ON / ON pulse number) / 2” from the “horizontal registration shift pulse number” as the adjusted horizontal registration shift pulse number (step S34).

  The adjusted lateral registration shift pulse numbers determined in steps S33 and S34 are transmitted to the pulse generator 101, and then the process proceeds to step S12. Since the process of step S12 has already been described, a description thereof will be omitted.

  Next, the control flow in the case of “NO” in step S5 will be described with reference to FIG. 12 (third flowchart). The lateral registration correction control unit 3 determines whether the reference sensor 5A is turned off (step S6). If “NO” in the step S6, the lateral registration correction control unit 3 returns the control to the step S5. If “YES” in the step S6, the pulse generator 101 starts the pulse count, and the OFF / OFF counter 103 also starts the pulse count (step S22).

  Subsequently, the OFF / OFF counter 103 determines whether the reference sensor 5B is turned on (step S23). If “NO” in the step S23, the OFF / OFF counter 103 repeats the step S23. If “YES” in the step S23, the OFF / OFF counter 103 stops the pulse count and transmits the count value to the shift pulse number adjusting unit 105 as the OFF / OFF pulse number (step S24).

  The shift pulse number adjusting unit 105 checks whether the OFF / OFF standard pulse number is “0” (step S25). If “NO” in the step S25, the shift pulse number adjusting unit 105 determines whether the OFF / OFF standard pulse number is larger than the OFF / OFF pulse (step S26).

  If “YES” in the step S26, the sheet width is larger than the standard width (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × [(OFF / 0FF standard pulse number) − (OFF / The number of OFF pulses)] 'is longer. Therefore, the shift pulse number adjusting unit 105 calculates the pulse number obtained by subtracting “[(OFF / 0FF standard pulse number) − (OFF / OFF pulse number)] / 2” from “horizontal registration shift pulse number”. The number of shift pulses is determined (step S27).

  If “NO” in the step S 26, the sheet width is larger than the standard width (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × [(OFF / 0FF pulse number) − (OFF / OFF The number of standard pulses))] 'will be shorter. Therefore, the shift pulse number adjustment unit 105 calculates the number of pulses obtained by adding “[(OFF / 0FF pulse number) − (OFF / OFF standard pulse number)] / 2” to “horizontal registration shift pulse number”. The number of shift pulses is determined (step S28).

  The adjusted lateral registration shift pulse numbers determined in steps S27 and S28 are transmitted to the pulse generator 101, and then the process proceeds to step S12. Since the process of step S12 has already been described, a description thereof will be omitted.

  If “YES” in the step S25, the shift pulse number adjusting unit 105 confirms whether the ON / ON standard pulse number is “0” (step S29). If “NO” in the step S29, the sheet width is larger than the standard width (the shift distance of the control roller 1 when one pulse is applied to the motor 41) × [(ON / ON standard pulse number) + (OFF / 0FF pulse number)] '. Therefore, the shift pulse number adjusting unit 105 adjusts the number of pulses obtained by adding “[(ON / ON standard pulse number) + (OFF / 0FF pulse number)] / 2” to “horizontal registration shift pulse number”. It is determined as a number (step S30).

  If “YES” in the step S29, the sheet width is shorter than the standard width by “(shift distance of the control roller 1 when one pulse is applied to the motor 41) × (OFF / 0FF pulse number)”. . Therefore, the shift pulse number adjusting unit 105 determines the number of pulses obtained by adding ‘(OFF / OFF pulse number) / 2’ to the ‘horizontal registration shift pulse number’ as the adjusted horizontal registration pulse number (step S <b> 31).

  The adjusted lateral registration shift pulse numbers determined in steps S30 and S31 are transmitted to the pulse generation unit 101, and then the process proceeds to step S12. Since the process of step S12 has already been described, a description thereof will be omitted.

  As described above, according to the present embodiment, even when the sheet has a deviation from the standard width due to a cutting error, shrinkage after fixing, or the like, the sheet with respect to the image formed in the image forming unit It is possible to correct the lateral registration position to an appropriate position. Even when the width of the sheet is the standard width, needless to say, the lateral registration position of the sheet with respect to the image formed by the image forming unit is corrected to an appropriate position.

<Other embodiments>
Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

  For example, in the above embodiment, the reference sensors 5A and 5B are fixed, but a distance changing unit is provided so that the interval between the reference sensors 5A and 5B can be changed according to the standard width of the conveyed sheet. It is good also as a structure. For example, if at least one of the reference sensors 5A and 5B is moved so that the interval between the reference sensors 5A and 5B matches the standard width of the conveyed sheet, the difference between the actual sheet width and the standard width is detected. The algorithm for doing so can be simplified. Further, the interval between the reference sensors 5A and 5B may be made wider or narrower than the standard width of the conveyed sheet. That is, if the size relationship between the interval between the reference sensors 5A and 5B and the standard width of the conveyed sheet is fixed, the algorithm for detecting the difference regardless of the sheet size can be simplified.

  In the above embodiment, the position of the side edge of the sheet is detected using a pair of reference sensors 5A and 5B. However, a plurality of pairs of reference sensors 5A and 5B having different intervals may be arranged. In this case, the reference sensor to be used may be selected so that the relationship between the distance between the reference sensors 5A and 5B and the standard width of the conveyed sheet is a predetermined relationship.

  Furthermore, in the above embodiment, the pair of reference sensors 5A and 5B are used as side edge detecting means for detecting the side edge position of the sheet, and as difference detecting means for detecting the difference between the actual sheet width and the standard width. Using. However, the present invention is not limited to this, and a configuration may be adopted in which side edge detection means for detecting the side edge position of at least one sheet and difference detection means for detecting the difference between the actual sheet width and the standard width are separately provided. In this case, the sheet can be shifted to a predetermined target position in the sheet width direction based on the detection timing of the side edge position of the sheet by the side edge detection unit and the difference detected by the difference detection unit.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program code. It is a process to be executed. In this case, the program and the storage medium storing the program constitute the present invention.

DESCRIPTION OF SYMBOLS 1 Control roller 3 Horizontal registration correction | amendment control part 5A, 5B Reference | standard sensor 10 Timing sensor 30 Sheet | seat 41 Motor (stepping motor)
DESCRIPTION OF SYMBOLS 100 Trigger generation part 101 Pulse generation part 102 ON / ON counter 103 OFF / OFF counter 105 Shift pulse number adjustment part

Claims (10)

A sheet conveying apparatus that corrects the position of the conveyed sheet in the sheet width direction by shifting the conveyed sheet in a sheet width direction parallel to the sheet surface and orthogonal to the sheet conveying direction,
Shift means for shifting the conveyed sheet in the sheet width direction;
First detection means that is arranged at a different position in the sheet width direction and detects one side edge position in the sheet width direction of the conveyed sheet, and the other side in the sheet width direction of the conveyed sheet Second detection means for detecting edge positions;
The distance between the first detection means and the second detection means, and the position of the one side edge by the first detection means when the conveyed sheet is shifted in the sheet width direction. Based on the detection timing, the detection timing of the other side edge position by the second detection means, and a predetermined standard width, the center of the conveyed sheet in the sheet width direction is set to a predetermined target position. And a control means for driving the shift means so as to coincide with each other. The control means includes
Detection timing of the one side edge position by the first detection means and detection timing of the other side edge position by the second detection means when the conveyed sheet is shifted in the sheet width direction; Based on the standard width, the difference between the standard width and the actual sheet width of the conveyed sheet is obtained,
The center in the width direction of the conveyed sheet and the target position are matched from the standard shift distance and the difference for shifting the standard width sheet so that the center in the width direction and the target position are matched. Find the shift distance needed to
The sheet conveying apparatus according to claim 1, wherein the conveyed sheet is shifted by the shift distance. A leading edge detecting means for detecting a leading edge of the conveyed sheet;
The control means includes
When the leading edge detecting means detects the leading edge of the conveyed sheet, the second detecting means detects the conveyed sheet, but the first detecting means detects the conveyed sheet. When not detected, the second detecting means does not detect the conveyed sheet, and the first detecting means detects the conveyed sheet. , Performing a preliminary shift to shift the conveyed sheet in the sheet width direction,
After completion of the preliminary shift, the sheet conveyed in the direction opposite to the shift direction of the conveyed sheet in the preliminary shift so that the center in the width direction of the conveyed sheet coincides with the target position. The sheet conveying apparatus according to claim 2, wherein the sheet conveying device is shifted. The shift unit includes a drive unit that shifts in the sheet width direction a control roller that sandwiches the conveyed sheet and conveys the sheet in the sheet conveyance direction.
4. The standard shift distance and the shift distance are respectively defined by a distance that the control roller shifts by one pulse that drives the motor and a pulse number that drives the motor. Sheet transport device. The control means includes
The first detection means detects the conveyed sheet and then shifts it by a predetermined distance to stop the conveyed sheet, thereby terminating the preliminary shift, and then conveying the sheet. When shifting the conveyed sheet in a direction opposite to the shift direction of the conveyed sheet in the preliminary shift so that the center in the width direction of the sheet matches the target position, the first detection unit Before the one side edge position of the conveyed sheet is detected, a shift speed for shifting the conveyed sheet is made to reach a constant speed, and the first detecting means is configured to move the one of the conveyed sheets. 4. The shift speed is controlled so that the conveyed sheet is shifted by the shift distance after detecting the side edge position. Over door transport device. The control means includes
After the first detection means detects the one side edge position of the conveyed sheet, the first shift is shifted by a predetermined distance to stop the conveyed sheet, thereby terminating the preliminary shift. After that, both the first detection means and the second detection means obtain a detection distance for detecting the conveyed sheet or a non-detection distance for not detecting the conveyed sheet, and the detection distance or the When shifting the non-detection distance and the standard width sheet in the sheet width direction so that the center in the width direction matches the target position, both the first detection unit and the second detection unit are 4. The sheet conveying apparatus according to claim 3, wherein the shift distance is obtained from a standard detection distance for detecting a standard width sheet or a standard non-detection distance for not detecting the standard width sheet. The shift unit includes a drive unit that shifts in the sheet width direction a control roller that sandwiches the conveyed sheet and conveys the sheet in the sheet conveyance direction.
The standard shift distance, the shift distance, the detection distance, the non-detection distance, the standard detection distance, and the standard non-detection distance are respectively the distance that the control roller shifts by one pulse that drives the motor and the motor. The sheet conveying apparatus according to claim 6, which is defined by the number of pulses to be driven.   The sheet conveying apparatus according to claim 2, further comprising a distance changing unit that changes an interval between the first detecting unit and the second detecting unit.   A plurality of pairs of the first detection means and the second detection means having different intervals arranged in the sheet width direction are provided with the first detection means and the second detection means as a pair. The sheet conveying apparatus according to claim 2, wherein A sheet conveying apparatus that corrects the position of the conveyed sheet in the sheet width direction by shifting the conveyed sheet in a sheet width direction parallel to the sheet surface and orthogonal to the sheet conveying direction,
Shift means for shifting the conveyed sheet in the sheet width direction;
Side edge detecting means for detecting a side edge position in the sheet width direction of the conveyed sheet;
A difference detecting means for detecting a difference between an actual sheet width and a predetermined standard width in the sheet width direction of the conveyed sheet;
Based on the side edge position of the sheet detected by the side edge detection means and the difference detected by the difference detection means, the sheet to be conveyed is shifted to a predetermined target position in the sheet width direction. And a control means for driving the shift means.

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