JP5268545B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of forming an image without causing carrying failure and misregistration. <P>SOLUTION: A side end position in the width direction of sheets S respectively carried from paper feeding cassettes 100 and 100' stored in a device body by dislocating a position in the width direction orthogonal to the sheet carrying direction, is detected by a lateral registration detecting sensor 35, and a misregistration quantity in the width direction of the paper feeding cassettes 100 and 100' is arithmetically operated based on sheet side end position information from the lateral registration detecting sensor 35. When the size of the arithmetically operated misregistration quantity exceeds a predetermined size, the misregistration quantity is displayed. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to a configuration for correcting a storage position of a sheet storage unit that is detachably stored in an image forming apparatus main body.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, or a facsimile, a sheet feeding cassette as a sheet storage unit is detachably attached to an image forming apparatus main body. At the time of image formation, the sheet stored in the sheet feeding cassette is sent out by a sheet feeding roller and then transported to an image forming unit by a sheet transporting device. Here, the sheet conveying apparatus includes a sheet skew and a deviation in a direction perpendicular to the sheet conveying direction (hereinafter referred to as a width direction) in order to match the posture and position of the sheet before the sheet is conveyed to the image forming unit. Some have a skew correction unit for correcting the above.

  In recent years, various sheets such as coated paper, embossed paper, ultra-thick paper, and ultra-thin paper have been used in image forming apparatuses. For this reason, in the image forming apparatus, not only high productivity but also high speed and high accuracy of skew correction are desired so as to be compatible with all types of sheets used.

  Therefore, in order to increase the speed and accuracy of such skew correction, there has been proposed a skew correction unit of an active skew correction method that corrects skew while transporting a sheet without stopping (Patent Document). 1).

  FIG. 12 is a diagram showing a configuration of a skew correction unit of such a conventional active skew correction method. In FIG. 12, reference numerals 21 and 22 denote a pair of skew correction rollers, and the pair of skew correction rollers 21 and 22 includes skew correction drive rollers 21a and 22a having a shape in which a part of the peripheral surface is notched. ing. Reference numeral 30 denotes a registration roller pair. The registration roller pair 30 is movable in the width direction and includes a registration driving roller 30a having a shape in which a part of the peripheral surface is cut out.

  27a and 27b are provided upstream of the skew correction roller pair 21 and 22 in the sheet conveyance direction, and are activation sensors for detecting the skew of the sheet. 28a and 28b are downstream of the skew correction roller pair 21 and 22 in the sheet conveyance direction. It is a skew detection sensor provided in. A registration sensor 131 is provided downstream of the registration roller pair 30 in the sheet conveyance direction and detects the leading edge of the sheet, 35 is a lateral registration detection sensor that detects a side edge position in the width direction of the sheet, and 32 is a registration HP sensor. Is a registration shift HP sensor.

  In the skew correction section having such a configuration, when the start sensors 27a and 27b and the skew detection sensors 28a and 28b detect the leading edge of the sheet, the skew correction motors 23 and 24 are started to be driven according to the detection timing. To do. As a result, as shown in FIG. 13A, the skew correction roller pair 21 and 22 rotate, and the skew correction of the sheet S is performed while the sheet S is being conveyed. Next, as shown in FIG. 13B, the skew feeding correction driving rollers 21a and 22a are positioned so that the notches face the sheet S, and the clamping of the sheet S by the skew feeding correction roller pairs 21 and 22 is released. In this state, the registration roller pair 30 performs leading edge registration and lateral edge registration correction.

  That is, when the registration sensor 131 detects the leading edge of the sheet S, the registration motor 31 is driven so that the image position on the photosensitive drum (not shown) and the leading edge position of the sheet S coincide with each other, and the rotation control of the registration roller pair 30 is performed. Do. Further, the lateral registration motor 33 is driven based on the detection signal from the lateral registration detection sensor 35, and the registration roller pair 30 is moved laterally so that the image position on the photosensitive drum coincides with the sheet S in the width direction. Thereby, the position of the sheet S with respect to the image on the photosensitive drum can be accurately corrected, and thereafter, the sheet can be conveyed repeatedly.

  By the way, in the case of the skew correction unit configured as described above, high-speed and high-accuracy position correction can be performed corresponding to all types of sheets, but as a result, at the downstream of the skew correction unit, the same position is repeated. The sheet is conveyed at high speed. For this reason, in particular, when a sheet having a large burr and high rigidity, which has never been seen before, is continuously passed for a long time, the sheet is conveyed to the same position of the photosensitive drum located downstream of the skew feeding correction unit, and the photosensitive drum surface layer There is a problem that scrapes off.

  Further, after passing through the photosensitive drum, the sheet is similarly conveyed to the same position of the fixing roller of the fixing unit that fixes the toner image formed on the photosensitive drum to the sheet. Here, since the surface layer of the fixing roller is soft so as to correspond to a sheet such as embossed paper, if the sheet is conveyed to the same position, the surface layer of the fixing roller is damaged and the life is extremely shortened. Will cause problems.

  Therefore, conventionally, for example, the image formed on the photosensitive drum is shifted by a predetermined amount, the sheet cassette setting position (storage position) is shifted, and the sheet correction position in the width direction by the registration roller pair 30 is shifted by a predetermined amount. To be transported. This prevents the sheet from being conveyed to the same location and the roller surface layer from being damaged. In this case, it is preferable to make the shift amount of the correction position of the sheet sufficiently large in order to sufficiently extend the life due to scratches on the roller surface layer.

  Here, there is a case where the setting position of the sheet feeding cassette is shifted, and when the amount of deviation of the setting position is large, the amount of deviation of the sheet conveyed to the skew feeding correction unit becomes large. If the amount of deviation of the sheet conveyed to the skew feeding correction portion increases as described above, the amount of displacement increases when the sheet correction position is shifted to prevent the life of the roller surface layer.

  However, when the correction position of the sheet is largely shifted, the sheet may not be moved to a predetermined correction position by the registration roller pair 30 before the sheet reaches the photosensitive drum. Misalignment may occur. For this reason, conventionally, by providing a paper position detection sensor for each paper feed cassette, the paper feed cassette position, that is, the position in the width direction of the sheet is accurately detected, and the cassette position is adjusted (Patent Document). 2).

JP 61-233752 A JP 2001-39546 A

  However, in such a conventional image forming apparatus, even when a paper position detection sensor is provided for each paper feed cassette, the sheet position is shifted due to the distortion of the conveyance path from each paper feed cassette to the skew feeding correction unit. May end up. In particular, in recent image forming apparatuses, the sheet feeding deck is mounted on the upstream side in the sheet conveying direction and the size of the sheet feeding deck is increased, so that the conveyance path becomes long, and the deviation of the sheet conveyed from the sheet feeding cassette to the skew feeding correction unit is increased. The amount further increases.

  In other words, if the transport path is distorted or the transport path becomes long, the sheet position will be greatly displaced until the skew correction unit is reached even if the sheet position is accurately detected by the paper edge detection sensor. End up. If the sheet position is greatly deviated as described above, the skew correction unit cannot move the sheet to the predetermined sheet correction position if the shift amount of the sheet correction position is increased to prevent the fixing roller surface layer life. There is. In this case, there is a problem that a conveyance failure or an image position deviation is likely to occur.

  On the other hand, in the case of an image forming apparatus provided with a sheet processing apparatus that performs stapling, alignment, bookbinding, etc. on the sheet, if the shift amount of the sheet correction position is increased, the sheet is discharged when the sheet is discharged to the sheet processing apparatus. Is discharged to the sheet processing apparatus in a state of being largely deviated. In this case, in the sheet processing apparatus, there is a problem that misalignment or a conveyance defect such as a jam easily occurs.

  Accordingly, the present invention has been made in view of such a current situation, and an object of the present invention is to provide an image forming apparatus capable of forming an image without causing a conveyance failure or a positional deviation. .

The present invention includes an image forming unit, an image forming apparatus having a sheet conveying portion for conveying the sheet to the image forming section, it is disposed in the apparatus main body, a plurality of sheet storage portion for storing sheets, a plurality A detection unit that detects a side end position in a width direction orthogonal to the sheet conveyance direction of each sheet conveyed from the sheet storage unit, and a plurality of sheet storage units based on sheet side end position information from the detection unit. A calculation unit that calculates a positional deviation amount in the width direction from the sheet conveyance reference, and a correction that is provided on the downstream side of the detection unit in the sheet conveyance direction and moves the sheets conveyed from the plurality of sheet storage units in the width direction. comprising a part, a counter for counting the number of sheets conveyed from each of the plurality of sheet storage portion, and a control unit that controls the correction unit so as to correct the side edge position of the sheet, the Wherein the control unit if: correction that is possible size of the side end position of the seat position deviation amount in the size of the sheet storage portion that is calculated is by the correction unit by the computing unit, computing by the arithmetic unit the have been side end position in the width direction of the sheet in accordance with the positional deviation amount and controls the correction unit so as to correct the correction amount set, computed by the arithmetic unit count number of the counter the The correction amount by the correction unit is changed according to the positional deviation amount of a plurality of sheet storage units .

  As in the present invention, when the amount of misalignment of a plurality of sheet storage units stored with their positions shifted exceeds a predetermined size, the misalignment amount is displayed, so that conveyance failure or image misregistration is displayed. It is possible to form an image without generating any. In addition, when the amount of misregistration calculated by the calculation unit is equal to or smaller than a predetermined size, the sheet side edge position is corrected in accordance with the calculated misregistration amount, thereby causing a conveyance failure or image position. An image can be formed without causing a shift.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a printer which is an example of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, reference numeral 1000 denotes a printer, and the printer 1000 includes a printer main body 1001 that is an apparatus main body and a scanner 2000 disposed on the upper surface of the printer main body 1001.

  Here, the scanner 2000 that reads a document includes a scanning optical system light source 201, a platen glass 202, and a document pressure plate 203 that opens and closes. An image reading unit 2001 including a lens 204, a light receiving element (photoelectric conversion element) 205, an image processing unit 206, a memory unit 208 for storing image processing signals processed by the image processing unit 206, and the like. I have.

  When reading the original, the original (not shown) placed on the platen glass 202 is read by irradiating light with the scanning optical system light source 201. Then, the read document image is processed by the image processing unit 206, converted into an electrically encoded electric signal 207, and transmitted to the laser scanner 111 as an image forming unit. Note that the image information processed and encoded by the image processing unit 206 may be temporarily stored in the memory unit 208 and transmitted to the laser scanner 111 as necessary by a signal from the controller 120.

  The printer main body 1001 includes a sheet feeding device 1002, a sheet conveying device 1004 that conveys the sheet S fed by the sheet feeding device 1002 to the image forming unit 1003, and a controller 120 that is a control unit for controlling the printer 1000. Etc. A sheet processing apparatus 500 that processes the sheet S discharged from the printer main body 1001 is provided on one side of the printer main body 1001.

  Here, the sheet feeding apparatus 1002 includes a separation unit including two (a plurality of) sheet feeding cassettes 100 and 100 ′, a pickup roller 101, a feed roller 102, and a retard roller 103. The sheets S in the sheet cassettes 100 and 100 ′, which are sheet storage units, are separated and fed one by one by the action of the pickup roller 101 that moves up and down / rotates at a predetermined timing and the separation unit. Yes. In the present embodiment, the two sheet feeding cassettes 100 and 100 ′ are set (stored) in the printer main body 1001 while shifting the position in the width direction perpendicular to the sheet conveying direction.

  A sheet conveying device 1004 constituting the sheet conveying unit includes a vertical path roller pair 105 (105a, 105b), an assist roller pair 10, and a skew correction unit 1 having a skew correction roller unit 1A and a lateral registration correction unit 1B described later. And.

  Then, the sheet S fed from the sheet feeding device 1002 is guided to the skew correction unit 1 after passing through the sheet conveyance path 108 formed by the guide plates 106 and 107 whose upper portions are curved by the pair of vertical path rollers 105. It is burned. Thereafter, the skew correction unit 1 corrects the skew and the deviation in the width direction as will be described later, and then the sheet S is conveyed to the image forming unit 1003.

  The image forming unit 1003 is of an electrophotographic system, and includes a photosensitive drum 112 as an image carrier, a laser scanner 111 as an image writing unit, a developing device 114, a transfer charger 115, a separation charger 116, and the like. Yes.

  When forming an image, first, the laser beam from the laser scanner 111 is turned back by the mirror 113 and applied to the exposure position 112a on the photosensitive drum rotating in the clockwise direction. An image is formed. Further, the latent image formed on the photosensitive drum in this way is thereafter visualized as a toner image by the developing device 114.

  In FIG. 1, reference numeral 131 denotes a registration sensor provided downstream of the lateral registration correction unit 1B. The registration sensor 131 detects the sheet S that has passed through the lateral registration correction unit 1B. When the registration sensor 131 detects the sheet S that has passed the lateral registration correction unit 1B, based on this detection signal, the controller 120 sends a sheet leading edge signal (image destination signal) to the laser scanner 111, for example, after T seconds, as will be described later. . Thereby, irradiation of the laser beam by the laser scanner 111 is started.

Next, the toner image on the photosensitive drum thus visualized is transferred to the sheet S by the transfer charger 115 in the transfer unit 112b. The distance from the laser beam irradiating position 112a on the photosensitive drum 112 to the transfer portion 112b has a _{l 0.}

  Further, the sheet S on which the toner image is transferred in this manner is electrostatically separated from the photosensitive drum 112 by the separation charger 116 and then conveyed to the fixing device 118 by the conveyance belt 117. Then, when passing through the fixing nip between the fixing roller 118a and the pressure roller 118b provided in the fixing device 118, the transferred image is permanently fixed. The surface layer of the fixing roller 118a is soft so as to correspond to a sheet such as embossed paper.

  Thereafter, the sheet S on which the image is fixed is discharged to the sheet processing apparatus 500 by the conveyance roller 119 and the discharge roller 122. Thereafter, the sheet S discharged to the sheet processing apparatus 500 is subjected to processing such as stapling, and then discharged and stacked on a sheet stacking tray (not shown).

  When images are formed on both sides of the sheet, the sheet on which the image is formed on one side is conveyed again to the image forming unit 1003 via the reverse path 123 and the double-sided path 126, and the sheet S on which no image is formed. An image is formed on the back side. The sheet on which both front and back images are formed in this way is then discharged to the sheet processing apparatus 500 by the discharge roller 122.

  Next, the skew correction unit 1 will be described. As shown in FIG. 2, the skew correction unit 1 includes a skew correction roller unit 1A that corrects the skew of the sheet and a horizontal registration correction unit 1B that corrects a deviation in the width direction of the sheet. Here, the skew feeding correction roller portion 1A includes two skew feeding correction roller pairs 21 and 22 disposed at a predetermined interval in the width direction.

  The skew correction roller pair 21 and 22 includes a driving roller 21a and 22a, which are driving rotating bodies each having a notch on the peripheral surface, and a driven rotating body that is in pressure contact with the driving rollers 21a and 22a by a pressure spring (not shown). Are constituted by driven rollers 21b and 22b. The skew correction motors 23 and 24 are connected to the drive rollers 21a and 22a.

  Further, activation sensors 27a and 27b are provided at a predetermined interval in the width direction upstream of the skew correction roller pair 21 and 22 in the sheet conveying direction. Here, the activation sensors 27a and 27b are for detecting the amount of skew of the sheet, and the skew correction motors 23 and 24 are driven according to the timing at which the activation sensors 27a and 27b detect the leading edge of the sheet. Start. The skew feeding of the sheet can be corrected by driving the skew feeding correction motors 23 and 24 in accordance with the timing at which the start sensors 27a and 27b detect the leading edge of the sheet.

  Further, downstream of the skew correction roller pair 21 and 22 in the sheet conveyance direction, skew detection sensors 28a and 28b that detect whether the skew correction is completely corrected by the skew correction roller pair 21 and 22 are arranged in the width direction. Are provided at predetermined intervals. When the skew detection of the sheet S is detected by the skew detection sensors 28a and 28b, the skew correction is again performed by the skew correction roller pair 21 and 22. In the present embodiment, the skew of the sheet is corrected by the preceding side deceleration control that decelerates the preceding side of the leading end of the sheet.

  Further, the lateral registration correction unit 1B includes a registration driving roller 30a that is a driving rotating body having a notch on the peripheral surface, and a registration driven body that is a driven rotating body that is in pressure contact with the registration driving roller 30a by a pressure spring (not shown). A registration roller pair 30 constituted by a roller 30b is provided. The registration driving roller 30 a is connected to the registration motor 31.

  Here, the registration driving roller 30 constituting the shift roller is provided so as to be slidable in the axial direction, and the registration driving roller 30a (registration roller pair 30) is driven in the width direction by a registration shift motor 33 which is a shift driving unit. The Further, a lateral registration detection sensor 35 that constitutes a detection unit for detecting a lateral registration position that is a position in the width direction of the sheet S to be conveyed is disposed on the upstream side of the registration roller pair 30 in the sheet conveyance direction. . Further, a registration sensor 131 for detecting the leading edge of the sheet S is disposed downstream of the registration roller pair 30 in the sheet conveyance direction.

  In FIG. 2, reference numerals 25 and 26 denote skew correction HP sensors that detect the HP (home position) of the pair of skew correction rollers 21 and 22. A sheet processing roller pair 530 is provided in the sheet processing apparatus 500. The sheet processing roller pair 530 includes a sheet processing driving roller 530a and a sheet processing driven roller 530b pressed by a pressure spring (not shown). It is configured. The sheet processing driving roller 530a is driven in the sheet conveying direction by the processing sheet conveying motor 531.

  Further, the sheet processing roller pair 530 is movable in the width direction, and the sheet processing roller pair 530 is driven in the width direction by a processing sheet shift motor 533. Further, a processing sheet lateral registration detection sensor 535 for detecting the lateral registration position of the sheet S is disposed upstream of the sheet processing roller pair 530 in the transport direction.

  Further, a processing sheet leading end detection sensor 536 for detecting the leading end of the sheet S is disposed downstream of the sheet processing roller pair 530. A stacking processing device (not shown) is disposed downstream of the sheet processing device. Reference numeral 534 denotes a processing sheet shift HP sensor that detects a home position (HP) in the width direction of the sheet processing roller pair 530.

  Incidentally, in the present embodiment, the lateral registration position information (described later) of each sheet feeding cassette to which the sheet S that has been conveyed is conveyed, the sheet passing count for each sheet feeding cassette, and the shift direction of the sheet processing apparatus 500 are determined. Thus, the exposure position on the photosensitive drum is shifted. Further, the correction position of the sheet is shifted to a predetermined position among preset N0 to Nmax as shown in FIG.

  FIG. 3 is a control block diagram of the printer 1000. The CPU 120A provided in the controller 120 (see FIG. 1) includes the skew correction HP sensors 25 and 26 described above and the activation sensors 27a described above. The detection signal from 27b is input. The CPU 120A as the control unit receives detection signals from the skew detection sensors 28a and 28b, the registration HP sensor 32, the registration shift HP sensor 34, the lateral registration detection sensor 35, and the registration sensor 131. . Further, detection signals from the processing sheet shift HP sensor 534, the processing sheet leading edge detection sensor 536, and the processing sheet lateral registration detection sensor 535 are input to the CPU 120A.

  On the other hand, skew correction motors 23 and 24, registration motor 31, registration shift motor 33, laser scanner 111, processing sheet conveyance motor 531, processing sheet shift motor 533, counter (memory) 129, and operation unit 130 are connected to CPU 120A. ing. Then, the CPU 120A drives each motor based on a detection signal from each sensor and a copy or print start signal from the operation unit 130.

  In the present embodiment, the CPU 120A has a calculation unit (not shown) that calculates the amount of positional deviation of the paper feed cassettes 100 and 100 ', as will be described later. In addition, the operation unit 130 includes a display unit (not shown). If the amount of positional deviation of the paper feeding cassettes 100 and 100 ′ exceeds a predetermined size as will be described later, this operation unit 130 is not shown. The amount of displacement is displayed on the display part. The predetermined amount of the positional deviation amount is such that the registration roller pair 30 can correct the side edge position in the width direction of the sheet.

  Then, the skew correction and registration correction control operations as shown in FIG. 4 are performed by the CPU 120A (controller 120).

  That is, when a copy or print signal is input from the operation unit 130, first, lateral registration position information, which is position information in the width direction of each sheet cassette storing the conveyed sheet S, and each sheet cassette. The paper passing count and the processing shift direction of the sheet processing apparatus are determined. Then, the reciprocating position is determined from N0 to Nmax set in advance as shown in FIG. 5 based on the lateral registration position information and the like (Step 1). Thereafter, after a predetermined time, laser exposure is started according to the determined reciprocating position (Step 2).

  Next, after the reciprocation / exposure position determination process, when the start sensors 27a and 27b detect the leading edge of the sheet S conveyed to the skew correction unit 1, the detection timings of the start sensors 27a and 27b are used as references. The skew correction motors 23 and 24 are started. Further, the skew amount at the front end of the sheet is calculated from the difference in detection time between the start sensors 27a and 27b, and the correction amount is calculated. Based on the calculated correction amount, the skew correction roller pair 21, 22 whose roller nip portion has been released is rotated by the preceding-side deceleration control described above to perform the first skew correction (Step 3).

  Next, after such skew feeding correction roller activation control & first skew feeding correction control processing, the system waits for the skew detection sensors 28a and 28b to turn on (Step 4). When the skew detection sensors 28a and 28b are turned on (Y in Step 4), the skew amount at the leading end of the sheet is calculated based on the respective detection timings, and the correction amount is calculated. Thereafter, based on the calculated correction amount, the skew correction motors 23 and 24 are driven to rotate the skew correction roller pair 21 and 22 and perform the second skew correction by the preceding deceleration control described above. (Step 5).

  Next, after such second skew correction control, the registration motor 31 is started on the basis of the skew detection sensor (delayed side thereof) (Step 6: registration roller start control), whereby the roller nip portion is released. 30 is rotated and the sheet S is conveyed. Thereafter, when the sheet S is nipped by the registration roller pair 30, the skew correction motors 23 and 23 are respectively operated with the roller nip portions of the skew correction roller pairs 21 and 22 released based on the skew correction HP sensor. Stop (Step 7: skew correction roller HP stop control).

  Next, it waits for the registration sensor 131 to detect the sheet and turn it on (Step 8). When the registration sensor 131 detects the sheet and turns ON (Y in Step 8), the lateral registration detection sensor 35 detects the side edge position of the sheet S (Step 9). Next, after such leading registration lateral registration detection processing, the speed calculation of the registration motor 31 is performed by a signal from the registration sensor 131 (Step 10). Further, the registration shift motor 33 is activated in accordance with the lateral registration amount detected by the lateral registration detection sensor 35.

  Thereafter, in the present embodiment, as shown in FIG. 5, the detection signal of the lateral registration detection sensor 35 and the center Nmid of the reciprocating positions N0 to Nmax set in advance by the sheet size information. The difference is calculated and the amount of movement by the registration shift motor 33 is calculated. Also, the lateral registration amount of the paper feed cassette 100 is calculated from this difference (Step 11). In the present embodiment, the sheet conveyance reference of the printer 1000 is the center reference, and the lateral registration amount of the paper feed cassette 100 is the lateral registration amount when the center in the sheet conveyance direction is the reference.

  Then, this calculation result is fed back to Step 1 as information for next control and registered in the memory 129.

  This calculation is performed for each sheet passing, and the value of the lateral registration amount is updated at any time by moving average or the like. In particular, when the opening / closing (removal) of the paper cassette is detected and a change in sheet size or sheet type occurs, the amount of deviation may increase from the previous job. When it is flowed, it is reset once and the value of the lateral registration amount is updated.

  Further, the lateral misregistration amount of the paper feed cassette 100 is displayed on the operation unit 130. When the misalignment amount is within a preset range, the job is continued as it is, and when the misalignment amount is larger than the preset range, a service is performed. A message indicating that readjustment is necessary is displayed on a man or the like.

  Next, the shift control of the registration motor 31 is performed based on the time difference between the detection timing of the registration sensor 131 and the timing at which the photosensitive drum 112 is irradiated with the laser light, and the image position on the photosensitive drum and the leading edge of the sheet S are controlled. Match the position. Further, the registration shift motor 33 is controlled based on the detection signal of the lateral registration detection sensor 35 and the determined reciprocating position, and the image position on the photosensitive drum 112 and the lateral registration position of the sheet S are matched (Step 12).

  Next, after such front registration lateral registration correction control, when the sheet S is conveyed to the transfer section by the registration roller pair 30, the registration motor is in a state in which the roller nip portion of the registration roller pair 39 is released based on the registration HP sensor 32. 31 is stopped (Step 13). At the same time, the registration shift motor 33 is started and shifted in the direction opposite to the correction direction. When the registration shift HP sensor 34 is turned off, the registration shift motor 33 is stopped (Step 14).

  Next, after such registration roller HP stop control, the image on the drum 112 and the sheet S whose position has been corrected with high accuracy are conveyed to the fixing device 118 and then to the sheet processing device 500. Thereafter, the process sheet detection sensor 536 detects the sheet and waits to turn on (Step 15). When the process sheet detection sensor 536 is turned on (Y in Step 15), the process sheet lateral registration detection sensor 535 sets the sheet side end position. Detect (Step 16).

  Next, after such processing sheet lateral registration detection processing, the processing sheet shift motor 533 moves the processing sheet based on the detection signal of the processing sheet lateral registration detection sensor 535 and the sheet processing position information of the sheet processing apparatus 500. The amount is calculated (Step 17). As a result, the sheet processing roller pair 530 moves in the processing direction.

  When the processing sheet passes, the sheet processing shift motor 533 is activated again between the processing sheet and the next sheet, the sheet processing roller pair 530 moves in the direction opposite to the processing direction, and the sheet processing shift HP sensor 534 is activated. Is detected (Step 18).

  Next, after such processing sheet & shift HP stop control processing, the number of passing sheets is counted up for each paper feed cassette and fed back as information for next control (Step 19).

  FIG. 6 is a diagram showing the relationship between the sheet passing count (fixing roller life) and the reciprocating position. In FIG. 6, the horizontal axis indicates the sheet passing count (fixing roller life) that is the number of counted sheets per reciprocating position, and the vertical axis indicates the reciprocating position.

  Here, in the present embodiment, the sheet S from the sheet feeding cassette 100 shown in FIG. 5 has a range ΔLα between the center Nmid of the reciprocating position of the fixing device 118 and the reciprocating position Nmax as shown in FIG. To pass. Further, in the present embodiment, as shown in FIGS. 5 and 6, after the sheet S conveyed from the sheet feeding cassette 100 is reciprocally moved by the skew feeding correction unit, the sheet processing apparatus 500 performs two front and rear directions. The sort is discharged.

  When sorting and discharging are performed by the sheet processing apparatus 500 as described above, the reciprocating position is determined so that the reciprocating position direction set for the sheet feeding cassette 100 matches the sorting direction in the sheet processing apparatus 500. ing.

  That is, when the sheet processing apparatus 500 sorts and discharges the paper in the front and rear two directions, as shown in FIG. 6, the sheet conveyed from the paper feeding cassette 100 is located between the reciprocating positions Nα1 to Nα2, and the back side region a, It is divided into the front area b. That is, when sorting and discharging by the sheet processing apparatus 500, the area through which the sheets are passed is assigned to the back area a in the case of the back side sorting and to the front area b in the case of the front side sorting.

  Here, there is a case where the setting position of the sheet feeding cassette 100 is shifted. In this case, it is set in advance according to the position of the side edge of the sheet detected by the lateral registration detection sensor 35 and the setting position of the sheet feeding cassette. The position becomes different. In the present embodiment, as shown in FIG. 6, the difference ΔCα between the detection position of the lateral registration detection sensor 35 and the center Nmid of the reciprocating position set in advance according to the set position of the paper feed cassette. Is calculated (calculated) as the lateral misregistration amount of the paper feed cassette 100.

  When the difference ΔCα is generated as described above, the reciprocating position between Nα1 and Nα2 of the sheet from the sheet feeding cassette 100 is determined based on the difference ΔCα. Here, in the present embodiment, the reciprocating position is determined on the shift side of the paper feed cassette 100. As a result, even when the sheet feeding cassette 100 is displaced, the sheet movement amount is reduced, and the sheet can reach a position corresponding to the toner image formed on the photosensitive drum.

  In this embodiment, when the lateral registration amount (= ΔCα) of the paper feed cassette 100 is too large, the lateral registration amount of the paper feed cassette 100 is displayed on the operation unit or the like, and the position is corrected by a service person. Prompt. If the lateral registration amount (= ΔCα) is not sufficient, it is difficult to identify the paper cassette. In this case as well, the lateral registration amount of the paper cassette 100 is displayed on the operation unit or the like, Prompt to correct the position.

  On the other hand, FIGS. 7 and 8 show the skew correction and registration correction control operations for the sheet S conveyed from the paper feed cassette 100 ′ set at a position different from the paper feed cassette 100 in the width direction. FIG. 4 is a diagram illustrating a relationship between a sheet passing count and a reciprocating position of the printer.

  Also in this case, as shown in FIG. 8, the sheet conveyed from the sheet feeding cassette 100 'is divided into the back side a and the near side b between the reciprocating positions Nβ1 and Nβ2. That is, the sheet is assigned to the back side a in the case of the rear side sorting by the sheet processing apparatus 500, and to the front side b in the case of the front side sorting. That is, the reciprocating position is determined so that the reciprocating position direction set for the sheet feeding cassette 100 ′ matches the sorting direction in the sheet processing apparatus 500.

  In the sheet S conveyed from the paper feed cassette 100 ′, the difference ΔCβ between the detection position of the lateral registration detection sensor 35 and the center Nmid of the preset position (reciprocation position) is set as the paper feed cassette 100 ′. It is calculated as the amount of lateral registration. The reciprocating position between Nβ1 and Nβ2 of the paper feed cassette 100 'is determined based on the calculated lateral registration amount ΔCβ. In this case as well, this reciprocating position is determined on the misalignment side of the paper feed cassette 100 '.

  As described above, in this embodiment, the reciprocating position in the skew feeding correction unit 1 set for each of the sheet feeding cassettes 100 and 100 ′ based on the detection signal (sheet side end position information) of the lateral registration detection sensor 35. Are determined (changed) in the misalignment direction of each of the paper feed cassettes 100 and 100 ′. Further, the reciprocating position is determined so that the reciprocating position direction set for each of the sheet feeding cassettes 100 and 100 ′ matches the sorting direction in the sheet processing apparatus 500.

  As a result, even if the reciprocation position shift amount of the fixing roller 118a (see FIG. 2) of the fixing device 118 is sufficiently large, the sheet movement amount in the skew feeding correction unit 1 and the sheet movement amount in the sheet processing apparatus 500 are obtained. Can be reduced.

  FIG. 9 is a diagram showing transition of the reciprocal position when a sheet is conveyed from the sheet cassette 100 and the sheet cassette 100 ′ in a certain sheet passing job. In FIG. 9, the horizontal axis indicates the sheet passing count (fixing roller life) around one reciprocating position, and the vertical axis indicates the reciprocating position.

  FIG. 9A shows a state after a paper passing job is performed once using the paper feeding cassette 100 and the paper feeding cassette 100 ′, and the number of paper passing from the paper feeding cassette 100 is shown. Is large. Therefore, in this case, as shown in FIG. 9B, in the next job, the reciprocating positions Nα1 ′ to Nα2 ′, the reciprocating positions from the reciprocating positions Nα1 to Nα2 and the reciprocating distance Lα of the paper feeding cassette 100 so far. The distance is increased to Lα ′.

  On the other hand, the paper feed cassette 100 ′ is changed from the reciprocating positions Nβ1 to Nβ2 and the reciprocating distance Lβ to the reciprocating positions Nβ1 ′ to Nβ2 ′ and the reciprocating distance Lβ ′.

  Further, from the past results of paper passing, as shown in FIG. 9C, the paper feeding cassette 100 is corrected to the reciprocating positions Nα1 ″ to Nα2 ″ and the reciprocating distance Lα ″. On the other hand, the sheet feeding cassette 100 ′ is corrected to reciprocating positions Nβ1 ″ to Nβ2 ″ and a reciprocating distance Lβ ″. Then, this correction is repeatedly performed so that the number of sheets passing through the reciprocating position becomes equal. This makes it possible to maximize the life of the fixing roller.

  FIG. 10 shows a case where the paper feed cassettes 100, 100 ', and 100' 'have three stages. In FIG. 10, (1) to (9) indicate reciprocating positions in the paper passing job. The first three sheet passing jobs (1) to (3) indicate the reciprocal positions of the sheets from the respective three-stage sheet feeding cassettes 100, 100 ', 100' '.

  Further, the next three paper passing jobs (4) to (6) indicate the reciprocal positions of the sheets obtained by correcting the reciprocal positions of the sheets in the first three paper passing jobs (1) to (3). Further, the following three sheet passing jobs (7) to (9) show the sheet reciprocal positions obtained by correcting the sheet reciprocal positions in the three sheet passing jobs (4) to (6).

  Here, the sheet passing job (9) shows a case where the sheet passing count at each reciprocating position has reached the life of the fixing roller. In this case, the sheet passing is continued while moving in the direction J where the sheet passing count has not reached the fixing roller lifetime, so that the sheet passing count reaches the fixing roller lifetime at all reciprocating positions.

  Note that FIG. 10 illustrates the case where there are three paper feed cassettes, but the number of paper feed cassettes is not limited as long as the same effect can be obtained. Further, although the horizontal registration of the paper feed cassette has been described, the same effect can be obtained even when one side is a double-sided pass and the horizontal registration amount from the double-sided pass is used.

  As described above, in the present embodiment, the lateral registration detection sensor 35 detects the side edge position of each sheet conveyed from a plurality of paper feed cassettes stored while shifting the position in the width direction, and the paper feed cassette The amount of positional deviation in the width direction is calculated. Further, when the calculated amount of misalignment exceeds a predetermined size, the CPU 120A controls the display unit to display the misalignment amount. By displaying the amount of misalignment of the sheet cassettes 100 and 100 ′ in this manner, the service person can correct the position misalignment of the sheet cassettes 100 and 100 ′, thereby causing conveyance failure and image position misalignment. It is possible to form an image without generating any.

  In the present embodiment, the reciprocation position in the skew feeding correction unit set for each paper feed cassette is corrected in the misalignment direction of each paper feed cassette according to the amount of positional deviation in the width direction of the paper feed cassette. ing. Further, the reciprocating position is corrected so that the direction of the reciprocating position set for each sheet cassette matches the sorting direction in the sheet processing apparatus. As a result, even if the shift amount of the reciprocating position in the skew feeding correction unit is sufficiently large, the sheet movement amount in the skew feeding correction unit and the sheet movement amount in the sheet processing apparatus can be reduced.

  In addition, by reviewing the reciprocating position in the skew feeding correction section set for each paper feed cassette for each paper passing job, the life of the fixing roller surface layer is sufficient without causing poor transport in the upstream and downstream processes. Can be obtained.

  In the above description, the so-called active registration type skew feeding correction unit has been described as an example. However, for example, a so-called skew feeding correction is performed by abutting a sheet skewed by a pair of skew feeding rollers against a butting plate. The present invention can also be applied to a feeding correction type skew feeding correction unit.

  FIG. 11 is a diagram showing the configuration of the skew feeding correction unit of such a skew feeding registration method. In FIG. 11, 401 is a pair of skew feeding rollers that feed the sheet S obliquely, and 403 is a butting plate that is a regulating member that abuts against the sheet S that is fed obliquely by the pair of skew feeding rollers 401 and regulates the side edge position of the sheet. is there. In such a skew feeding correction unit, the skew feeding roller pair 401 driven by the skew feeding motor 402 corrects the skew feeding of the skewed sheet S against the butting plate 403.

  Here, in the case of such a skew feeding registration method, the lateral registration deviation amount of the sheet from each sheet feeding cassette is not detected as in the above-described active registration method. Each sheet feeding cassette is adjusted to a position where a predetermined lateral registration occurs, and the abutting plate 403 is moved in advance in accordance with the previously adjusted lateral registration amount. The same effect can be obtained by detecting the leading edge of the sheet shifted forward in the conveying direction by the skew feeding registration by the registration sensor 131 and then shifting the sheet S to the back in the conveying direction by the registration roller pair 30.

  In the case of the skew feeding correction unit of the skew feeding registration method, a sensor (not shown) that detects a sheet that strikes the butting plate 403 is provided. When the setting position of the paper feeding cassette 100 is shifted, a sensor (not shown) does not detect a sheet that strikes the butting plate 403 even after a predetermined time has elapsed.

  In this case, thereafter, the CPU 120A obtains the lateral registration amount of the paper feed cassette 100 based on the time until the sensor detects the sheet. If the calculated amount of misregistration is greater than or equal to a predetermined size, the lateral misregistration amount of the paper feed cassette 100 is displayed on the operation unit or the like, and a serviceman is urged to correct the position. If the calculated amount of misalignment is less than or equal to a predetermined amount, a shift mechanism (not shown) is controlled according to the calculated amount of misalignment until a predetermined time elapses. The position of the abutting plate 403 is adjusted (corrected) so that the sheet comes into contact with the abutting plate 403.

1 is a schematic configuration diagram of a printer that is an example of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a skew feeding correction unit provided in the sheet conveying device of the printer. FIG. 3 is a control block diagram of the printer. 6 is a flowchart showing skew feeding correction and registration correction control operations by the skew feeding correction unit. FIG. 5 is a first diagram illustrating a skew correction and registration correction control operation of the skew correction unit. FIG. 4 is a first diagram illustrating a relationship between a sheet passing count (fixing roller life) and a reciprocating position of the printer. FIG. 9 is a second diagram illustrating a skew correction and registration correction control operation of the skew correction unit. FIG. 9 is a second diagram showing the relationship between the sheet passing count (fixing roller life) and the reciprocating position of the printer. FIG. 6 is a diagram illustrating transition of a reciprocating position when a sheet is conveyed from two sheet feeding cassettes in a sheet passing job of the skew feeding correction unit. FIG. 6 is a diagram illustrating transition of a reciprocal position when a sheet is conveyed from three sheet feeding cassettes in a sheet passing job of the skew feeding correction unit. FIG. 10 is a diagram illustrating a skew correction and registration correction control operation of a skew correction unit according to another configuration provided in the sheet conveying apparatus of the printer. The figure which shows the structure of the skew correction part of the conventional active skew correction system. The figure explaining operation | movement of the skew correction part of the conventional active skew correction system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Skew correction | amendment part 1A Skew correction roller part 1B Horizontal registration correction | amendment parts 21 and 22 Skew correction roller pair 30 Registration roller pair 33 Registration shift motor 35 Horizontal registration detection sensor 100,100 'Paper feed cassette 112 Photoconductor drum 118 Fixing device 118a Fixing roller 120A CPU
130 Operation Unit 401 Skewed Roller Pair 403 Abutting Plate 500 Sheet Processing Device 1000 Printer 1001 Printer Main Body 1003 Image Forming Unit 1004 Sheet Conveying Device S Sheet

Claims (5)

In an image forming apparatus comprising an image forming unit and a sheet conveying unit that conveys a sheet to the image forming unit,
A plurality of sheet storage units disposed in the apparatus main body for storing sheets; and
A detection unit for detecting a side end position in a width direction orthogonal to a sheet conveyance direction of the sheet conveyed from each of the plurality of sheet storage units;
A calculation unit that calculates a positional deviation amount in the width direction from the sheet conveyance reference of the plurality of sheet storage units based on sheet side end position information from the detection unit;
A correction unit that is provided on the downstream side of the detection unit in the sheet conveyance direction, and moves a sheet conveyed from the plurality of sheet storage units in the width direction;
A counter that counts the number of sheets conveyed from each of the plurality of sheet storage units;
A control unit that controls the correction unit to correct the side edge position of the sheet,
The control unit calculates by the calculation unit when the amount of positional deviation of the sheet storage unit calculated by the calculation unit is equal to or less than a size by which the side edge position of the sheet can be corrected by the correction unit. the have been side end position in the width direction of the sheet in accordance with the positional deviation amount and controls the correction unit so as to correct the correction amount set, computed by the arithmetic unit count number of the counter the An image forming apparatus, wherein a correction amount by the correction unit is changed according to the positional deviation amount of a plurality of sheet storage units. A sheet processing apparatus provided downstream of the correction unit in the sheet conveying direction and having a sheet processing position in which the position in a direction orthogonal to at least two sheet conveying directions for processing a sheet on which an image is formed differs;
The control unit changes a correction amount in a direction orthogonal to the sheet conveyance direction of the sheet by the correction unit according to the positional deviation amount calculated by the calculation unit and the sheet processing position information of the sheet processing apparatus. the image forming apparatus according to claim 1 Symbol mounting and. The correction unit includes a skew correction roller that corrects skew of the sheet conveyed from the plurality of sheet storage units, and a shift roller that shifts the sheet whose skew is corrected by the skew correction roller in the width direction. A shift driving unit for shifting the shift roller,
3. The image according to claim 1, wherein the control unit controls the shift driving unit to shift the shift roller in a width direction in accordance with a magnitude of a positional deviation amount calculated by the calculation unit. Forming equipment. The correcting unit abuts the skew feeding roller that obliquely feeds the sheet conveyed from the plurality of sheet storage portions and the sheet obliquely fed by the skew feeding roller to regulate the side end position in the width direction of the sheet. A regulating member, and a shift mechanism for shifting the regulating member in the width direction,
3. The image formation according to claim 1, wherein the control unit controls the shift mechanism to shift the restricting member in a width direction in accordance with a magnitude of a displacement amount calculated by the calculation unit. apparatus. The sheet storage unit is configured to be capable of correcting the position in the width direction orthogonal to the sheet conveyance direction, and the amount of positional deviation of the sheet storage unit is large enough to correct the side edge position of the sheet by the correction unit. 5. The image forming apparatus according to claim 1, wherein a display requesting position adjustment of the sheet storage unit is displayed on the display unit in the case of more than that.

Images