JP5595116B2 - Sheet processing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet processing apparatus and an image forming apparatus, and more particularly to a configuration of a bending portion that bends a sheet.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, a facsimile machine, or a combination of these, an image forming unit that forms a toner image on a sheet and a toner image formed on the sheet are fixed. And a fixing unit to be provided. Further, some image forming apparatuses are provided with a sheet processing apparatus that performs a bookbinding process or the like on a sheet on which a toner image is fixed.

  Here, in the conventional sheet processing apparatus, in the bookbinding process, after a predetermined number of sheets are stacked to form a sheet bundle, the center portion of the sheet bundle is bound with a thread, staple, adhesive, or the like, and then bound. It is generally known that a sheet bundle is formed into a booklet by folding the part in half. Such a conventional sheet processing apparatus includes a veneer and a pair of folding rollers in order to perform bookbinding (see Patent Document 1). When the sheet is folded in half, the binding portion is folded in half by pushing the binding portion of the sheet bundle into the nip portion of the pair of folding rollers by the thrust plate.

JP-A-11-193175

  By the way, some of such conventional sheet processing apparatuses have a so-called one-side drive transmission system in which a drive transmission unit for driving the pair of folding rollers is provided on one side of the rotation shaft of the pair of folding rollers. Such a drive transmission unit employs a mechanism that transmits the drive from a drive source such as a motor to the pair of folding rollers via a plurality of gears. Thus, by transmitting the drive between the gears, a force in the direction of increasing the nip pressure is generated at the end of the folding roller pair on the side of the drive transmission unit. For this reason, an unbalance of the nip pressure occurs between the drive transmission unit side of the folding roller pair and the opposite side of the drive transmission unit side.

  Further, in such a one-side driven folding roller pair, the conveyance efficiency on the side of the drive transmission unit having a high nip pressure is higher than that on the side opposite to the drive transmission unit having a low nip pressure. When the sheet bundle is conveyed while being folded in half by such a pair of folding rollers, the conveyed sheet bundle is advanced on the side of the drive transmission unit having higher conveyance efficiency and is skewed.

  Therefore, the present invention has been made in view of such a current situation, and provides a sheet processing apparatus and an image forming apparatus that can be conveyed while being folded in a good manner without skewing a sheet bundle. It is intended.

The present invention provides a sheet processing apparatus for folding a sheet bundle in half, a sheet stacking means for sequentially stacking conveyed sheets, a pair of folding rollers for transporting the sheet bundle while folding in half, and the sheet stacking means stacked on the sheet stacking means. A pushing member that pushes the bundle of sheets into the nip portion of the pair of folding rollers, a driving unit that drives the pair of folding rollers, and one side end in the width direction perpendicular to the sheet bundle conveyance direction of the pair of folding rollers. And driving from the drive unit while generating a force in a direction in which the first folding roller and the second folding roller are pressed against each of the first folding roller and the second folding roller constituting the pair of folding rollers. the provided a drive transmission portion which heat is reached, the previous SL of the pair of folding rollers above the widthwise side end portion opposite to the drive transmission portion of the sheet bundle stacked on the sheet stacking means Stevenage The pushing end of the thrust member is inclined so that the opposite side to the drive transmission part side is located on the downstream side in the push direction with respect to the drive transmission part side so as to be pushed into the part. is there.

  As in the present invention, the sheet bundle is skewed by being pushed into the nip portion of the folding roller pair first from the width direction end of the sheet bundle opposite to the drive transmission portion side of the folding roller pair. And can be conveyed while being folded in two.

1 is a diagram illustrating a configuration of an image forming apparatus including a sheet processing apparatus according to an embodiment of the present invention. The figure explaining the structure of the finisher which is the said sheet processing apparatus. The figure explaining the saddle stitch bookbinding operation | movement of the saddle stitch bookbinding apparatus provided in the said finisher. FIG. 3 is a control block diagram of the image forming apparatus and the finisher. The control block diagram of the finisher control part which controls the said finisher. FIG. 4 is a diagram illustrating an image forming operation in a saddle mode of the image forming apparatus. The figure which showed the structure of the 1st folding roller provided in the said saddle stitch binding apparatus. The figure which looked at the said 1st folding roller from the paper discharge outlet direction. The figure explaining the structure of the drive transmission part of the veneer which comprises the folding part provided in the said saddle stitch bookbinding apparatus. The 1st figure explaining folding operation | movement of the said folding part. Sectional drawing which shows a mode that the sheet | seat bundle is guide | induced to the nip part of a folding roller, being folded. The 2nd figure explaining folding operation | movement of the said folding part.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a sheet processing apparatus according to an embodiment of the present invention. In FIG. 1, 900 is an image forming apparatus, and 900A is an image forming apparatus main body (hereinafter referred to as apparatus main body). The apparatus main body 900A is provided with an image reader (image reading apparatus) 951 including a scanner unit 955 and an image sensor 954, an image forming unit 902 that forms an image on a sheet, a double-sided device 953, and the like. A document feeder 950 for feeding a document to a platen glass (not shown) is provided on the upper surface of the apparatus main body 900A.

  The image forming unit 902 includes a cylindrical photosensitive drum 906, a charger 907, a developing unit 909, a cleaning device 913, and the like. Further, on the downstream side of the image forming unit 902, a fixing device 912, a discharge roller, and the like. A pair 914 and the like are provided. Further, the finisher 100, which is a sheet processing apparatus that processes an image-formed sheet to be discharged after image formation from the apparatus main body 900A, is connected to the apparatus main body 900A. A CPU circuit unit 206 is a control unit that controls the apparatus main body 900 </ b> A and the finisher 100.

  Next, an image forming operation of the apparatus main body 900A having such a configuration will be described. When an image forming signal is output from the CPU circuit unit 206, the document is first placed on the platen glass by the document feeder 950, and the image of the document is read by the image reader 951. The read digital data is exposed. Input to means 908. Then, the exposure unit 908 irradiates the photosensitive drum 906 with light corresponding to the digital data. At this time, the surface of the photosensitive drum 906 is uniformly charged by the charger 907. When light is irradiated in this manner, an electrostatic latent image is formed on the surface of the photosensitive drum. Is developed by the developing device 909, whereby a toner image is formed on the surface of the photosensitive drum.

  On the other hand, when a paper feed signal is output from the CPU circuit unit 206, first, the sheets P set in the cassettes 902a to 902d and the paper feed deck 902e are fed to the registration rollers 910 by the paper feed rollers 903a to 903e and the transport roller pair 904. Be transported. Next, the sheet P is conveyed by a registration roller 910 to a transfer unit including a transfer charger 905 at a timing such that the leading edge of the sheet and the leading edge of the toner image on the photosensitive drum are aligned. In this transfer portion, a transfer bias is applied to the sheet P by the transfer charger 905, whereby the toner image on the photosensitive drum is transferred to the sheet side.

  Next, the sheet P to which the toner image has been transferred is conveyed to the fixing device 912 by the conveying belt 911, and when passing through the fixing device 912, the toner image is thermally fixed. At this time, foreign matters such as residual toner adhering to the photosensitive drum without being transferred to the sheet P are scraped off by the cleaning device 913. As a result, the surface of the photosensitive drum 906 becomes clear, and the next It can prepare for image formation.

  Next, the sheet on which the toner image has been thermally fixed by the fixing device 912 is conveyed to the finisher 100 as it is by the discharge roller pair 914. When images are formed on both sides of the sheet P, after the toner image is thermally fixed, the sheet P is conveyed to the double-sided device 953 by the switching member 915, and the image formation surface is reversed again by reversing the surface on which the image is formed. The image is formed on the back surface toward the portion 902. Thereafter, the sheet is conveyed to the finisher 100 by the discharge roller pair 914.

  The finisher 100 sequentially takes in the sheets discharged from the apparatus main body 900A, aligns a plurality of fetched sheets and bundles them into one bundle, and performs a punching process in which a hole is formed near the rear end of the fetched sheets. ing. Further, the finisher 100 performs processing such as stapling processing and bookbinding processing for stapling the trailing end side of the sheet bundle. As shown in FIG. 2, the stapler 700 for stapling the sheet and the sheet bundle are folded in two. A saddle stitch bookbinding section 800 for bookbinding.

  The finisher 100 includes an inlet roller pair 102 for taking the sheet into the apparatus, and the sheet discharged from the apparatus main body 900 </ b> A is delivered to the inlet roller pair 102. At this time, the sheet delivery timing is also detected by the entrance sensor 101 at the same time.

  Thereafter, the sheet conveyed by the inlet roller pair 102 passes through the conveyance path 103 and the edge position of the sheet is detected by the lateral registration detection sensor 104, and how much is the center (center) position of the finisher 100, It is detected whether a deviation in the width direction has occurred. In addition, after such a shift in the width direction (hereinafter referred to as a lateral registration error) is detected, a shift unit (not shown) moves forward or backward while the sheet is being conveyed to the shift roller pair 105, 106. The sheet is shifted by a predetermined amount in the direction.

  Next, the sheet is conveyed by the conveying roller pair 110 and reaches the buffer roller pair 115. Thereafter, when the sheet is discharged to the upper tray 136, the upper path switching member 118 is brought into a broken line state in the figure by a driving means such as a solenoid (not shown). As a result, the sheet is guided to the upper path conveyance path 117 and discharged to the upper tray 136 by the upper discharge roller 120.

  When the sheet is not discharged to the upper tray 136, the sheet conveyed by the buffer roller pair 115 is guided to the bundle conveying path 121 by the upper path switching member 118 in the state indicated by the solid line, and thereafter, the conveying roller 122 and the bundle conveying roller pair 124 sequentially passes through the transport path. Next, when the conveyed sheet is discharged to the lower stacking tray 137, the sheet is first conveyed to the lower path 126 by the saddle path switching member 125 in the state indicated by the solid line, and then the lower discharge roller pair 128. Thus, the sheet is discharged to the intermediate processing tray 138.

  Then, the discharged sheets are aligned while being sequentially stacked by the return means such as the paddle 131 and the belt roller 129, thereby performing an intermediate process as a sheet stacking unit for performing processing on the aligned and stacked sheet bundle. A predetermined number of sheets are aligned on the tray. Next, the sheet bundle thus aligned on the intermediate processing tray is subjected to a binding process by the stapler 132 as necessary, and then discharged to the lower stacking tray 137 by the bundle discharge roller pair 130. The

  On the other hand, when the sheet is subjected to saddle (saddle stitching) processing, the saddle path switching member 125 is moved to a position indicated by a broken line by driving means such as a solenoid (not shown). As a result, the sheet is conveyed to the saddle path 133 and guided to the saddle stitch bookbinding section 800 by the saddle entrance roller pair 134.

  Next, as shown in FIG. 3A, the sheet is loaded into a processing tray 155 serving as a sheet stacking unit with a loading port selected by a switching member 125b operated by a solenoid according to the size. Here, the sheet discharged from the saddle inlet roller pair 134 in this way is discharged into the open space of the processing tray 155, whereby the leading edge of the sheet or sheet bundle is conveyed to the leading edge stopper 147, and the leading edge in the sheet conveying direction. Position alignment is performed. Further, the sheet discharged to the open space is fed to the leading end stopper 147 by the feed roller 144 as necessary. Here, the front end stopper 147 waits downward from the position of the stapler center C at a distance that is half of the length in the sheet conveyance direction to be conveyed according to the sheet size (the length in the sheet conveyance direction). For this reason, the sheets stacked on the processing tray 155 are arranged such that the center of the sheet matches the staple position.

  When the storage of the first sheet is completed, the second sheet is discharged to the processing tray 155. Here, as shown in FIG. 3B, the second sheet S discharged in this way is conveyed to the processing tray 155 by the switching member 125a positioned above the switching member 125b. In addition, by switching the path in which the sheet P is conveyed to the processing tray 155 by the switching members 125a and 125b in this way, it is possible to prevent the rear end of the already stacked sheets and the front end of the conveyed sheet from colliding with each other. . In this way, the number of sheets to be bound is conveyed to the processing tray 155, and the stacking of the sheet bundle is completed.

  In the middle of the processing tray 155, a stapler 142 is provided as a binding unit that is disposed so as to face the processing tray 155 and binds the central portion in the transport direction of a bundle of a plurality of sheets stored in the processing tray 155. Yes. When the storage of the sheet is completed, the stapler 142 staples the central portion in the conveyance direction of the sheet bundle made of the sheet.

  On the downstream side of the stapler 142, first to third folding roller pairs 148 to 150 that constitute a folding portion that folds the sheet bundle stored in the processing tray 155 in the central portion in the conveyance direction, and a thrust plate 146 are disposed on the processing plate. The trays 155 are provided so as to face each other. The pushing plate 146 protrudes toward the center of the sheet bundle stored in the processing tray 155 in the conveyance direction.

  When folding the bound sheet bundle, after the stapling process is finished, the leading end stopper 147 is lowered so that the staple position of the sheet bundle (the center in the sheet bundle conveyance direction) is the nip position of the first folding roller pair 148. Next, the sheet bundle at the staple position is moved. Thereafter, by pushing out the thrust plate 146 as a thrust member in the direction of the arrow shown in FIG. 3, the sheet bundle can be folded in two at the center while pushing the sheet bundle into the nip portion of the first folding roller pair 148. it can. When the sheet bundle is folded without performing the binding process, the sheet bundle is moved so that the central portion in the conveyance direction of the sheet bundle stored in the processing tray 155 is the nip position of the first folding roller pair 148. Thereafter, the thrust plate 146 is projected. Next, the sheet bundle folded in half by the first folding roller pair 148 is crushed by the second folding roller pair 149 and the third folding roller pair 150, and is shown in FIG. A saddle tray 153 is stacked by a saddle discharge roller pair 152.

  FIG. 4 is a control block diagram for controlling the image forming apparatus 600 and the finisher 100. As shown in FIG. 4, the CPU circuit unit 206 includes a CPU, a ROM 207, and a RAM 208 (not shown). A CPU circuit unit 206 controls a DF (document feeder) control unit 202, an image reader control unit 203, an image signal control unit 204, a printer control unit 205, a finisher control unit 210, and an external interface 201. Note that the CPU circuit unit 206 performs control according to the program stored in the ROM 207 and the setting of the operation unit 209.

  A DF (document feeder) control unit 202 controls the document feeder 950, and an image reader controller 203 controls the image reader. The printer control unit 205 controls the apparatus main body 900A, and the finisher control unit 210 controls the finisher 100 (the staple unit 700 and the saddle stitch bookbinding unit 800). In the present embodiment, a configuration in which the finisher control unit 210 is mounted on the finisher 100 will be described. However, the present invention is not limited to this, and the finisher control unit 210 may be provided integrally with the CPU circuit unit 206 in the apparatus main body 900A to control the finisher 100 from the apparatus main body 900A side.

  The RAM 208 is used as an area for temporarily storing control data and a work area for operations associated with control. An external interface 201 is an interface from a computer (PC) 200, which develops print data into an image and outputs the image to the image signal control unit 204. An image read by the image sensor is output from the image reader control unit 203 to the image signal control unit 204, and an image output from the image signal control unit 204 to the printer control unit 205 is input to the exposure control unit.

  The finisher control unit 210 is mounted on the finisher 100 and performs drive control of the entire finisher by exchanging information with the CPU circuit unit 206. Here, the finisher control unit 210 that controls the driving of the finisher 100 includes a CPU 810, a ROM 801, a RAM 802, and the like as shown in FIG. The finisher control unit 210 communicates with the CPU circuit unit 206 via the communication IC 804 to exchange data, and executes various programs stored in the ROM 801 based on instructions from the CPU circuit unit 206 to control driving of the finisher 100. I do.

  When performing drive control, detection signals from various sensors are taken into the finisher control unit 210. As these various sensors, there are an inlet sensor 101, a photo sensor 301, a photo sensor 311, and an HP sensor 319 described later. Further, a driver 803 is connected to the finisher control unit 210, and the driver 803 drives the folding motor 300, the thrust motor 310, the stapler 142, and the like based on a signal from the finisher control unit 210.

  Next, an image forming operation in the saddle mode for bookbinding of sheets will be described with reference to FIG. When the saddle mode is designated, the original set on the original feeder 950 is read in order from the first page, the read original images are sequentially stored in the hard disk, and the number of read originals is counted simultaneously.

When the reading of the original is completed, the read original image is classified by the following equation (1), and the image forming order and the image forming position are determined.
M = n × 4-k (1)
M: number of documents, n: an integer greater than or equal to n: number of sheets, k: any one of 0, 1, 2, 3

  The image formation in the saddle mode will be described with an example in which the number of read originals is eight. As shown in FIG. 6A, original image data (R1 to R8) for eight pages is stored in the hard disk. Stored in the order of reading. The image formation order and image formation position are determined for each image data (R1 to R8). As a result, as shown in FIG. 6B, on the first surface (front surface) of the sheet P1 of the first page, an R4 image is formed on the left half and an R5 image is formed on the right half. Guided to the duplexer 953. Then, the sheet P1 is fed again to the transfer unit, and an R6 image is formed on the left half of the second surface (back surface), and an R3 image is formed on the right half.

  The sheet P1 having images formed on both sides in this way is thereafter conveyed to the finisher 100 by the inlet roller pair 102 and conveyed to the processing tray 155 by the saddle inlet roller pair 134. Similarly, an R2 image is formed on the left half and an R7 image is formed on the right half of the first surface (front surface) of the sheet P2 of the second page, and this sheet P2 is guided to the duplex device 953. The sheet P2 is fed again to the transfer unit, and an R8 image is formed on the left half of the second surface (back surface), and an R1 image is formed on the right half. The sheet P2 is conveyed to the finisher 100 by the inlet roller pair 102 and is conveyed to the processing tray 155 by the saddle inlet roller pair 134 in the same manner as the sheet P1.

  At this time, as shown in FIG. 6C, the second surface on which the R8 image and the R1 image are formed faces upward and the R8 image is at the head, and is conveyed in the direction of the arrow in the figure. The sheets P1 and P2 on which images have been formed in this manner are stacked on the processing tray 155 so that the center position in the sheet conveying direction becomes the position C in FIG. 2 in the state as shown in FIG.

  Thereafter, after staple processing is performed on the sheet bundle by the stapler 142, the leading end stopper 147 is lowered by a predetermined amount until the center of the sheet bundle matches the folding position. Thereafter, the pushing plate 146 is pushed out, the sheet bundle is guided to the nip portion of the first folding roller pair 148, and the sheet bundle is folded. The sheets folded by the first folding roller pair 148 in this way are sequentially conveyed while being creased by the second folding roller pair 149 and the third folding roller pair 150, and eventually the saddle is discharged by the saddle discharge roller pair 152. The paper is discharged to the tray 153.

  FIG. 7 is a diagram showing the configuration of the first folding roller pair 148. In FIG. 7, reference numeral 300 denotes a folding motor, and 301 is a photosensor for monitoring the speed when the motor 300 rotates. The conveyance speed control of the folding motor 300 is performed based on a signal from the photosensor 301. Here, the driving of the folding motor 300 serving as a driving unit is driven by the gear 302, the gear 320, the gear 304, and the shaft 148a of the upper folding roller 148A that constitute the driving transmission unit from the driving belt 302a. It is transmitted to the folding roller 148A. The upper folding roller 148A and the gear 305 are supported by a cam 303 so as to be swingable about the rotation center A of the gear 304.

  The driving of the folding motor 300 is transmitted to the lower folding roller 148B via a gear 302, a gear 320, and a gear 306 provided on the shaft 148b of the lower folding roller 148B constituting the drive transmission unit. The downward folding roller 148B and the gear 306 are supported by a cam 308 so as to be swingable about the rotation center B of the gear 320. When the folding motor 300 is driven counterclockwise, the upper folding roller 148A rotates in the F direction and the lower folding roller 148B rotates in the G direction. Here, when the upper folding roller 148A and the lower folding roller 148B rotate, the drive transmission is transmitted between the gear 304 and the gear 305 supported by the cam 303 so that the end of the upper folding roller 148A has an E side. Directional force is generated. Further, by transmitting the drive between the gear 320 supported by the cam 308 and the gear 306, a force in the direction D is generated at the end of the lower folding roller 148B on the side of the drive transmission unit.

  FIG. 8 is a view of the first folding roller pair 148 as viewed from the sheet discharge outlet. The upper folding roller 148A and the lower folding roller 148B are pressed against each other by a spring (not shown) or the like to apply an appropriate nip pressure to the sheet bundle. At this time, a radial load of H is applied to both ends of the upper folding roller 148A and the lower folding roller 148B by a spring or the like as shown in FIG. When the folding motor 300 is driven in this state, as shown in FIG. 8B, radial loads of E and D are generated at the ends of the upper folding roller 148A and the lower folding roller 148B on the side of the drive transmission unit. .

  That is, when the folding motor 300 is driven, loads of H + E and H + D are applied from the top and bottom to the end portion on the side of the drive transmission unit to which the driving of each roller of the first folding roller pair 148 is input, and the first folding roller A load of H is applied from above and below to the end of the pair 148 opposite to the end of the drive transmission unit. For this reason, the load at both ends of the first folding roller pair 148 becomes unbalanced, and when the load becomes unbalanced in this way, the first folding roller pair 148 has a large inter-axis distance on the side opposite to the drive transmission side end. The conveyance efficiency by the open and opened folding roller pair 148 is lowered.

  FIG. 9 is a diagram illustrating the configuration of the drive transmission unit of the thrust plate 146 that constitutes the folding unit. In FIG. 9, reference numeral 310 denotes a thrust motor. When the thrust motor 310 is driven, the gear 312 is rotated by the drive belt 312a, and the rotating shaft 314 to which the gear 312 is fixed is rotated. Here, the rotation shaft 314 is provided with a gear 315 on the opposite side to the gear 312. When the rotation shaft 314 rotates, the link 317 is driven by the gear 315 and the gear 316, and the thrust plate 146 is driven. .

  The thrust plate 146 is linearly driven in the direction of the nip portion of the first folding roller pair 148 by guides 323 and 324 provided on the frames 321 and 322 of the thrust unit 146A. Reference numeral 311 denotes a photosensor for controlling the rotational speed of the thrust motor 310.

  FIG. 10 is a view of the folded portion as viewed from above. FIG. 10 shows a state in which the sheet bundle PA has been moved to the folding position after the stapling process. In FIG. 10, reference numeral 319 denotes an HP sensor that detects the HP position of the veneer 146.

  As shown in FIG. 10A, against the nip line of the folding roller pair 148 extending in the width direction orthogonal to the sheet bundle pushing direction, the thrust plate 146 has a tilt of θ to the thrust drive frame 318. It is supported. In other words, the pushing plate 146 has a downstream end (pushing end) in the pushing direction, and a portion of the pushing plate 146 opposite to the drive transmission portion side of the nip portion of the first folding roller pair 148 is driven by the nip portion. It is supported by being inclined so as to be located on the downstream side in the pushing direction with respect to the transmission side portion. When the thrust motor 310 is driven by supporting the thrust plate 146 in this manner, the thrust plate 146 is firstly referred to as the drive transmission portion side of the nip portion of the first folding roller pair 148 of the sheet bundle PA. Abut on the opposite side. 10 and FIG. 12, which will be described later, show a state in which the thrust plate 146 is inclined more than the actual one for easy understanding.

  Thereafter, as shown in FIG. 10 (b), the sheet bundle PA is inclined following the tip of the abutting plate 146, and the width direction side end portion of the sheet bundle PA opposite to the drive transmission portion side is the first. It is guided to the L point of the nip portion of the one-fold roller pair 148. Thereafter, when the first folding roller pair 148 rotates, the folded portion of the sheet bundle PA moves from the L point on the opposite side to the drive transmission portion side to the M point on the drive transmission portion side in the direction of arrow K. However, it is folded in half.

  FIG. 11 is a cross-sectional view showing a state in which the sheet bundle PA is guided to the nip portion of the first folding roller pair 148 while being folded, and the thrust plate 146 reaches a position beyond the nip portion of the first folding roller pair 148. The sheet bundle PA is pushed in. Thereby, the sheet bundle PA can be reliably folded. Moreover, in this Embodiment, as shown in FIG. 10, the front-end | tip part of the thrust board 146 has a comb-tooth shape. Therefore, the first folding roller pair 148 is a stepped roller so that the sheet bundle PA can be pushed to a position beyond the nip portion of the first folding roller pair 148.

  When the sheet bundle PA is pushed into the nip portion of the first folding roller pair 148 by the pushing plate 146, the driving means for driving the pushing plate 146 and the first folding roller pair 148 is large when the number of sheets of the sheet bundle PA increases. A load is added. For this reason, in order to drive the thrust plate 146 and the first folding roller pair 148, a driving unit (driving source) such as a large motor is required, and the apparatus becomes large. Further, when the nip pressure of the first folding roller pair 148 is constant, the folding property of the sheet bundle is lowered when the number of sheets is increased and the rigidity of the sheets is increased. Therefore, in order to ensure the folding property of the sheet bundle, it is necessary to enlarge a driving unit such as a motor for driving the pair of folding rollers, but in this case, the apparatus becomes large.

  Here, by folding the folding portion of the sheet bundle PA while moving in the direction of the arrow K, in other words, by performing the folding process while folding the sheet bundle PA from one side, The load on the fold is a point load. In this way, by making the load on the folded portion of the sheet bundle PA by the first folding roller pair 148 a point load, the folding performance is improved even with the same folding pressure.

  When the sheet bundle PA is conveyed by the first folding roller pair 148, the sheet bundle PA is then moved to the N side (drive transmission unit side) from the difference in conveyance efficiency due to the difference in radial load, as shown in FIG. Is sent more than the opposite O side (the side opposite to the drive transmission unit side). For this reason, the inclination of the leading edge of the sheet bundle PA pushed into the nip portion of the first folding roller pair 148 with the leading edge inclined at the angle θ by the inclination of the thrust plate 146 changes from θ to θ ′ after a predetermined amount of conveyance. Decrease.

  As a result, when the sheet bundle PA is conveyed as it is, the leading end of the sheet bundle PA is substantially parallel to the folding roller nip line as shown in FIG. Thereafter, the sheet is conveyed by the second folding roller pair 149, the third folding roller pair 150, and the saddle discharge roller pair 152 and then stacked on the saddle tray 153.

  As described above, in the present embodiment, the thrust plate 146 is disposed in a state inclined with respect to the nip line of the first folding roller pair 148, and the sheet bundle PA is inclined with respect to the sheet bundle. The folding process is performed. Thereby, the load with respect to the folding part of sheet bundle PA can be made into a point load, and even if it is the same folding pressure, the folding property of sheet bundle PA improves.

  That is, the sheet bundle PA is pushed into the nip portion of the folding roller pair 148 from the end in the width direction opposite to the drive transmission portion side of the nip portion of the first folding roller pair 148. The foldability of the bundle PA can be ensured. In addition, with this configuration, it is possible to reduce the driving force necessary for driving the first folding roller pair 148 and the thrust plate 146, and it is possible to reduce power consumption and noise during driving. .

  In the present embodiment, the configuration in which the sheet bundle is folded by the three pairs of folding rollers of the first to third folding roller pairs 148 to 150 has been described. The folding operation of the sheet bundle may be performed by the folding roller.

DESCRIPTION OF SYMBOLS 100 ... Finisher, 146 ... Thrust board, 148-150 ... 1st-3rd folding roller pair, 310 ... Thrust motor, 800 ... Saddle stitch bookbinding part, 900 ... Image forming apparatus, 900A ... Image forming apparatus main body, 902 image formation Part, PA ... sheet bundle

Claims (4)

In a sheet processing apparatus that folds a sheet bundle in half,
Sheet stacking means for sequentially stacking conveyed sheets;
A pair of folding rollers for conveying the sheet bundle while folding it in half;
A projecting member that pushes the sheet bundle stacked on the sheet stacking unit into the nip portion of the pair of folding rollers;
A drive unit for driving the pair of folding rollers;
The first folding roller is provided on one side end side in the width direction orthogonal to the sheet bundle conveying direction of the folding roller pair, and each of the first folding roller and the second folding roller constituting the folding roller pair. and and a drive transmission unit for heat reaching the drive from the drive unit while generating a force to the direction in which the second folding roller is pressed against,
The pushing end of the thrust member is pushed into the nip portion of the pair of folding rollers first from the width direction side end opposite to the drive transmission portion side of the sheet bundle loaded on the sheet stacking means, A sheet processing apparatus, wherein the sheet processing apparatus is inclined so that the side opposite to the drive transmission unit side is located downstream of the drive transmission unit in the pushing direction. The drive transmission unit includes a first gear attached to the first folding roller, a second gear attached to the second folding roller, and the first folding roller to the second folding roller with respect to the first gear. A first gear train that transmits the drive from the drive unit while generating a force in a direction in which the second folding roller is pressed against the first folding roller, and a force in the direction in which the second folding roller is pressed against the first folding roller. The sheet processing apparatus according to claim 1, further comprising: a second gear train that transmits the drive from the drive unit while generating the second gear to rotate the second gear in a direction opposite to the first gear. The pushing member, the sheet processing apparatus according to claim 1 or 2, wherein pressing the sheet bundle to a position beyond the nip of the folding roller pair.   An image forming unit that forms an image on a sheet, and the sheet processing apparatus according to claim 1 that processes the sheet on which an image is formed by the image forming unit. Image forming apparatus.

Images