JP2005314011A - Sheet conveying device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device and an image forming device capable of changing the sheet conveying direction of conveying roller pairs by a desired quantity even when the adjustment in a visually recognizing manner is difficult. <P>SOLUTION: The sheet conveying direction of conveying roller pairs constituted of a driving roller and driven rollers 67A, 67B is changed by a changing means (a turning frame 70), and the change of the sheet conveying direction by the changing means is adjusted by operating an adjustment means 76 from a side face of a device body. The sheet conveying direction of the conveying roller pairs is changed by a desired quantity without visually recognizing the conveying roller pairs by allowing the operational quantity of the adjustment means 76 to be proportional to the change of the sheet conveying direction of the changing means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus, and more particularly to a configuration for changing the sheet conveying direction of a pair of conveying rollers for nipping and conveying a sheet.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a fax machine, a copier, or a printing machine, an image is formed by an electrophotographic system, an offset printing system, an ink jet system, or the like. As an example of such an image forming apparatus, there is a color image forming apparatus that forms a color image by an electrophotographic method, and such a color image forming apparatus mainly includes an image forming unit that forms a plurality of images. The toner image is transferred directly from the photosensitive member to the sheet as a transfer method, and a tandem method in which the plurality of image forming units are arranged side by side, a rotary method in which the plurality of image forming units are arranged in a cylindrical shape, and a transfer method. It is classified into a direct transfer method and an intermediate transfer method in which the image is once transferred to an intermediate transfer member and then transferred to a sheet.

  Here, for example, in the case of an intermediate transfer tandem type image forming apparatus in which four color image forming sections are arranged side by side on an intermediate transfer belt, an apparatus targeting the printing market with a small number of copies is provided by taking advantage of not making a plate. It is coming. However, in order to be accepted in such a light printing market, it is necessary to achieve high image quality, high productivity, and long life, and as a means to increase the reliability of each part necessary for this purpose There is a way to increase the size.

  For example, since the life of the photosensitive drum depends on the travel distance, in order to extend the life, the outer diameter can be increased to extend the life without technically difficult and costly material development. However, when the photosensitive drum is increased in size in this way, the entire apparatus or unit is increased in size, so that the conveyance path for conveying the sheet becomes longer, and the direction orthogonal to the conveyance direction due to skew during sheet conveyance (hereinafter referred to as the width). It is also necessary to take into account sheet misalignment in the direction).

  In general, a sheet is conveyed by a sheet conveying apparatus having a plurality of conveying roller pairs for nipping and conveying the sheet. However, when the conveying path is long, the sheet conveying apparatus requires a large number of conveying roller pairs. . At this time, a minute skew caused by a minute alignment of each pair of conveying rollers, a roller diameter error, and a guide mounting error is piled up. In such a case, the sheet jams.

  In particular, in the case of performing image formation on both sides with one image forming unit, when performing image formation on the second side, after reversing the sheet on which the image is formed on one side, the sheet is passed through the duplex conveying unit, and then Since the sheet must be conveyed again to the image forming unit, the conveyance distance is further increased.

  When an image is formed on the second surface of the sheet, as in the case of the first surface, skew correction and synchronization with the image must be performed by the registration unit before the sheet is conveyed to the image transfer unit. If the size is increased, the skew amount may exceed the amount that can be corrected by the registration unit. In this case, the skew correction is incomplete, the position of the sheet S and the image may be misaligned, or a jam or a crease in the sheet S may occur.

By the way, as a method of skew correction in such a registration unit,
(1) A pair of registration rollers is arranged upstream of the transfer unit, and the leading edge of the conveyed sheet is abutted against the stopped registration roller to form a loop to correct skew feeding. A method of performing skew correction and image alignment in the transport direction by restarting the registration rollers in synchronization.
(2) A retractable shutter is arranged upstream of the transfer unit, and the skew correction is performed by forming a loop formation by abutting the leading edge of the conveyed sheet against the closed shutter, and then synchronizing with the image. Then, the shutter is opened and the conveying roller is restarted to perform skew correction and image alignment in the conveying direction.
(3) A side regulating plate and detection means are arranged upstream of the transfer section, and the skew feeding is corrected by conveying the sheet while abutting the sheet against the side regulating plate by a skew feeding roller, and based on detection of the leading edge of the sheet by the detecting means. Image alignment in the conveyance direction by controlling the sheet conveyance speed
(4) A means for detecting skew feeding upstream of the transfer section and two independently drivable rollers are arranged at both ends in the width direction of the sheet, and the speed of each driving roller is changed according to the skew feeding amount. There is a method to correct skew.

In addition, as a method of aligning the image in the width direction in the resist unit,
A The user or serviceman adjusts the position of the paper feed cassette. B Detects the displacement in the width direction of the sheet during conveyance and moves the position of the image written on the photosensitive drum. C Deviation in the width direction of the sheet during conveyance. There is a method of detecting the error and moving the conveying means such as a registration roller to return the sheet to a normal position.

  The conventional registration unit performs skew correction and image alignment by combining (1) to (4) and A to C.

  However, when the skew of the second sheet is large as described above, the skew correction cannot be sufficiently performed by the methods (1) and (2). In addition, in the method (3), not only sufficient skew correction cannot be performed, but when the deviation in the width direction is large, a sheet collides with the upstream end of the side regulating plate in the sheet conveying direction, and a jam occurs. Further, the skew feeding roller cannot pinch the sheet and jam occurs. In the method (4), skew correction can be performed. However, since it takes time for the correction operation, large skew causes a decrease in productivity.

  Also, in the alignment of the images in the width direction, if the displacement in the width direction is large, the method B deviates from the image forming range of the image forming unit and the image is cut off. Note that if the image forming unit is created in anticipation of the amount of deviation, the apparatus will be further increased in size. Further, in the method C, the amount of movement of the conveying means becomes large, so that the movement time needs to be doubled in the reciprocation, which causes a decrease in productivity.

  Here, the skew and the deviation in the width direction are largely caused by the alignment error of the roller and the guide. For example, in an apparatus that forms an image on both sides, by adjusting the alignment error of the roller in the double-sided conveyance unit The deviation in the sheet conveyance direction can be adjusted (corrected) so as to be within a certain range.

  In addition, since it is difficult to take out and maintain a double-sided conveyance part if a double-sided conveyance part becomes large, there exists what made it adjustable from the front on an apparatus main body, without taking out a double-sided conveyance part.

  And as an example of correcting the alignment error of the roller from the front side in this way, in order to adjust the registration roller parallel to the photosensitive drum, the position of the transport unit where the registration roller is arranged can be adjusted from the front side. There is. Specifically, the transport unit is spring-biased against the frame that supports the photosensitive drum, and the position of the abutting member is adjusted and fixed while looking at the position of the unit fixing screw with respect to the elongated hole from the front. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 06-183607

  However, in the conventional sheet conveying apparatus and image forming apparatus in which the alignment error of the conveying roller pair is corrected by adjusting the screws as described above, the image forming apparatus is small, for example, as described in Patent Document 1. In addition, when the reference photosensitive drum can be opened upward, the moving amount of the transport unit can be visually confirmed.

  For this reason, it is possible to adjust the alignment error of the transport roller pair while confirming the mounting screw for the elongated hole. However, if the image forming apparatus is large, the transport unit is also located in the back, Adjustment while visually recognizing the unit (conveying roller pair) is very difficult.

  Therefore, the present invention has been made in view of such a current situation, and a sheet conveying apparatus capable of changing a sheet conveying direction of a pair of conveying rollers by a desired amount even when adjustment while visually recognizing is difficult, and An object is to provide an image forming apparatus.

  The present invention provides a sheet conveying apparatus for nipping and conveying a sheet by a conveying roller pair constituted by a driving roller and a driven roller pressed against the driving roller, and changing means for changing the sheet conveying direction of the conveying roller pair; Adjusting means for adjusting the change amount of the sheet conveying direction by the changing means by an operation from the side of the apparatus main body, and the operation amount and the change of the adjusting means for changing the sheet conveying direction of the pair of conveying rollers The change amount of the sheet conveyance direction by the means is proportional.

  According to the present invention, by adjusting the operation amount of the adjusting unit and the sheet conveying direction change amount of the changing unit that changes the sheet conveying direction of the pair of conveying rollers, it is easy even when adjustment while visually recognizing is difficult. The sheet conveying direction of the conveying roller pair can be changed by a desired amount.

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

  FIG. 1 is a diagram showing a schematic configuration of a color image forming apparatus which is an example of an image forming apparatus provided with a sheet conveying apparatus according to the first embodiment of the present invention.

  In FIG. 1, reference numeral 50 denotes a color image forming apparatus, and 50A denotes a color image forming apparatus main body (hereinafter referred to as an apparatus main body). The apparatus main body 50A includes an image forming unit 513 and a sheet feeding unit that conveys a sheet S. 50B and a transfer unit 50C that transfers the toner image formed by the image forming unit 513 to the sheet S fed by the sheet feeding unit 50B.

  Here, the image forming unit 513 includes a photoconductor 508, an exposure device 511, a developing device 510, a primary transfer device 507, a photoconductor cleaner 509, and the like, and includes yellow (Y), magenta (M), cyan ( C) and black (Bk) image forming units. That is, the color image forming apparatus according to the present embodiment is of an intermediate transfer tandem system in which four color image forming units are arranged side by side on an intermediate transfer belt described later as an image forming unit. Note that the colors formed by each image forming unit are not limited to these four colors, and the color arrangement order is not limited to this.

  The sheet feeding unit 50B includes a sheet storage unit 51 that stores the sheets S in a form of being stacked on the lift-up device 52, and a sheet feeding unit 53 that sends out the sheets S stored in the sheet storage unit 51. It has. Examples of the sheet feeding unit 53 include a method using frictional separation by a paper feed roller and the like, a method using air separation and adsorption, and the like. In the present embodiment, a paper feeding method using air is used. An example is given.

  The transfer unit 50C includes an intermediate transfer belt 506 that is stretched by rollers such as a driving roller 504, a tension roller 505, and a secondary transfer inner roller 503, and is conveyed and driven in the direction of arrow B in the drawing. .

  Here, the intermediate transfer belt 506 transfers a toner image formed on the photosensitive member by a predetermined pressure and an electrostatic load bias given by the primary transfer device 507, and also a substantially opposite secondary transfer. An unfixed image is attracted to the sheet S by applying a predetermined pressure and an electrostatic load bias in the secondary transfer portion formed by the inner roller 503 and the secondary transfer outer roller 56.

  In the color image forming apparatus 50 having such a configuration, when an image is formed, first, a photosensitive member whose surface is uniformly charged in advance by a charging unit (not shown) and rotates in the direction of arrow A in the figure. The exposure apparatus 511 emits light based on the transmitted image information signal 508, and a latent image is formed by irradiating the light appropriately through the reflecting means 512 and the like. Note that the transfer residual toner slightly remaining on the photoconductor 508 is collected by the photoconductor cleaner 509 and is again prepared for the next image formation.

  Next, toner development is performed by the developing device 510 on the electrostatic latent image formed on the photoconductor 508 in this manner, and a toner image is formed on the photoconductor. Thereafter, a predetermined pressure and an electrostatic load bias are applied by the primary transfer device 507, and the toner image is transferred onto the intermediate transfer belt 506.

  Note that image formation by the Y, M, C, and Bk image forming units of the image forming unit 513 is performed at the timing of superimposing on the upstream toner image primarily transferred onto the intermediate transfer belt. As a result, a full-color toner image is finally formed on the intermediate transfer belt 506.

  Further, the sheet S is sent out by the sheet feeding unit 53 in accordance with the image forming timing of the image forming unit 513, and thereafter, the sheet S passes through the transport path 1 and is transported to the registration unit 55. In the registration unit 55, skew correction and timing correction are performed by the registration roller 551, and then, the registration unit 55 is transported to a secondary transfer portion formed by the secondary transfer inner roller 503 and the secondary transfer outer roller 56, and the secondary transfer portion. A full color toner image is secondarily transferred onto the sheet S in the transfer portion.

  Next, the sheet S on which the toner image has been secondarily transferred in this way is conveyed to the fixing device 58 by the pre-fixing conveyance unit 57. In the fixing device 58, the toner is melted and fixed on the sheet S by applying a predetermined pressing force by a substantially opposed roller or belt and generally a heating effect by a heat source such as a heater.

  Next, the sheet S having the fixed image obtained in this manner is discharged as it is onto the discharge tray 500 by the branch conveyance device 59. When images are formed on both sides of the sheet S, the sheet is conveyed to the reverse conveying device 501 by switching a switching flapper (not shown).

  Here, when the sheet S is conveyed to the reversal conveying device 501 in this way, the sheet S is switched back and back, and is conveyed to the reconveying path R provided in the double-sided conveying device 502. Thereafter, the sheet is fed from the sheet re-feeding path 2 included in the sheet conveying device 54 in synchronism with the sheet of the subsequent job conveyed from the sheet feeding unit 50B, and similarly sent to the secondary transfer unit. Since the image forming process is the same as that of the first side, it is omitted.

  In this embodiment, the sheet conveying device 54 includes a registration unit 55, a pre-fixing conveying portion 57, a branch conveying device 59, a reverse conveying device 501, a duplex conveying device 502, and the like.

  By the way, in the present embodiment, the duplex conveying device 502 is divided into an upstream duplex conveying portion 502A and a downstream duplex conveying portion 502B and attached to the apparatus main body 50A as shown in FIG. FIG. 2 is a view of such an upstream double-sided conveyance unit 502A viewed obliquely from behind. The downstream duplex conveyance unit 502B has the same configuration as the upstream duplex conveyance unit 502A.

  In FIG. 2, 62 is an upper guide, and 63 is a lower guide. The upper guide 62 and the lower guide 63 form a double-sided conveyance path R. Reference numeral 60 denotes a positioning pin provided on the back surface of the upper guide 62, and the double-sided conveyance unit 502 has the positioning pin 60 fitted to a rear plate (not shown) of the apparatus main body 50A and a front mounting hole 61. The front plate (not shown) of the apparatus main body 50A is fastened with screws to be attached to the apparatus main body 50A.

  Further, the lower guide 63 can be rotated (opened) downward with a support shaft 64 provided at the rear portion of the upper guide 62 as a fulcrum, so that the lower guide 63 can be moved from the front side during jam processing. By rotating downward, the double-sided conveyance path R can be opened and the jammed sheet can be accessed. During normal use, the lower guide 63 is held by a locking means (not shown) in a state where the gap with the upper guide 62 is kept constant.

  Incidentally, the lower guide 63 rotatably supports drive rollers 65 (see FIG. 1) driven by drive motors controlled by a controller (not shown) of the main body, and each drive roller 65 is supported on the upper guide 62. The idle roller 67 and the alignment adjustment rollers 67A and 67B, which are driven rollers constituting a pair of conveyance rollers together with the driving roller 65, are rotatably supported.

  A bearing is provided in the idle roller 67 for the purpose of improving durability, and sliding with the pressure shaft 68 is performed by the bearing. The surface layer material of the driving roller 65 is silicon rubber, and the idle roller 67 and the alignment adjusting rollers 67A and 67B are made of POM which is resin.

  Here, in the present embodiment, the idle roller 67 is rotatably supported on the upper guide 62 via the pressure shaft 68 and urged by the spring 69, and the alignment adjustment rollers 67A and 67B are As shown in FIG. 3, a sheet conveyance direction of a conveyance roller pair (hereinafter referred to as an alignment adjustment conveyance roller pair) constituted by a drive roller 65 and alignment adjustment rollers 67A and 67B via a bearing and a pressure shaft 68A (not shown). It is rotatably supported by the rotation frame 70 which is a roller support part which comprises the change means for changing.

  As shown in FIG. 3, the rotational frame 70 has a plurality of axially provided axial positions, and in this embodiment, the center of gravity of the roller unit including the two alignment adjusting rollers 67A and 67B and the pressure shaft 68A. The upper guide 62 is inserted into a swinging central hole 72 provided at a position facing substantially the center in the axial direction of the pressure shaft 68A (positions equidistant from the alignment adjustment rollers 67A and 67B along the pressure shaft 68A). By fitting the provided boss 72a, the boss 72a is swung as a fulcrum.

  Here, the pressing shaft 68 </ b> A can be moved up and down by being inserted into a vertical slit 70 </ b> A formed in the rotating frame 70, and is driven by springs 71 provided at both ends of the rotating frame 70. The alignment adjustment rollers 67 </ b> A and 67 </ b> B are pressed against the driving roller 65 by being biased toward the roller 65. Further, the rotation frame 70 is controlled to move in the vertical direction by inserting pins 73 fixed to the upper guide 62 into the elongated holes 70B provided symmetrically to the rotation frame 70, respectively. It has become.

  Further, the rotating frame 70 is urged clockwise by a spring 74 with the boss 72a as a fulcrum, and one side of the rotating frame 70 that is substantially symmetric with the mounting portion of the spring 74 of the rotating frame 70 by the urging force of the spring 74. Positioning is performed by abutting the end portion against the abutment block 75.

  Here, the abutting block 75, which is an abutting member that abuts against (abuts) the rotating frame 70, rotates the screw 76 constituting the adjusting means together with the abutting block 75 clockwise or counterclockwise. As shown in FIG. 4, the slide frame 75 is slidable in the direction of arrow C. When the slide block 75 is pushed backward by turning the screw 76, for example, as shown in FIG. It is pressed by the abutting surface 75a, which is a contact surface, and swings counterclockwise along the abutting surface 75a.

  When the rotation frame 70 swings and changes its position in this way, the alignment adjustment rollers 67A and 67B move integrally with the rotation frame 70, and thereby the alignment adjustment rollers 67A and 67B with respect to the drive roller 65. Can be adjusted, and the sheet conveyance direction of the alignment adjustment conveyance roller pair can be changed.

  In the present embodiment, the abutment surface 75a of the slide block 75 has a 45 ° taper shape, so that the rotation frame 70 moves by an amount equivalent to the pushing amount (operation amount) of the slide block 75. It is supposed to be. Further, an M3 screw is used for the screw 76. Therefore, if the screw 76 is rotated once, the slide block 75 can be pushed in by 1 mm, and accordingly the rotating frame 70 is moved in the 1 mm sheet conveying direction ( Rocking).

  Further, in the present embodiment, the movement amount of the slide block 75 is set to ± 2 mm at the maximum, whereby the rotation frame 70 moves ± 4 mm at both ends, and the positions of the alignment adjustment rollers 67A and 67B are accordingly changed to the sheet. Deviation is ± 4 mm in the transport direction.

  Here, when the registration roller 551 (see FIG. 1) is used as a reference (start), the deviation of the conveyance roller pair on the apparatus main body in the sheet conveyance direction (hereinafter referred to as misalignment) is estimated to be 0.3 mm per one. Since there are a total of 11 conveying roller pairs up to the alignment adjustment rollers 67A and 67B (see FIG. 1), a misalignment of max 3.3 mm is counted.

  However, as described above, in the present embodiment, since the misalignment of ± 4 mm can be adjusted in the upstream double-sided conveyance unit 502A, the downstream double-sided conveyance unit 502B is also a unit having the same configuration. Then, it is possible to adjust the misalignment of the alignment adjustment conveying roller pair up to ± 8 mm in total. Therefore, with this configuration, it is possible to reliably correct the skew of the sheet before the sheet is conveyed again to the image forming unit 513.

  Incidentally, the rotation frame 70 and the adjustment screw 76 are provided inside the front plate 62B of the upper guide 62 as shown in FIG. For this reason, when the adjustment screw 76 is rotated, a screwdriver is inserted through the insertion hole 62A provided in the front plate 62B, and the adjustment screw 76 is rotated.

  Here, the inclination of the alignment adjustment rollers 67A and 67B in the axial direction cannot be adjusted while confirming the movement of the alignment adjustment rollers 67A and 67B itself, but as described above, one rotation of the adjustment screw 76 and the rotation frame. Since the amount of movement 70 is proportional, if the amount of rotation (operation amount) of the adjustment screw 76 is known, the sheet conveyance direction of the alignment adjustment conveyance roller pair can be accurately determined without visually recognizing the movement amount of the alignment adjustment rollers 67A and 67B. It can be changed by the desired amount.

  Thus, by making the amount of operation of the adjustment screw 76 and the amount of movement of the rotation frame 70 proportional, the apparatus main body 50A (double-sided conveyance) can be obtained without lowering or pulling out the unit even in a large apparatus. The inclination of the alignment adjusting rollers 67A and 67B in the axial direction can be adjusted only by operating the adjusting screw 76 from the side surface of the apparatus main body. Thereby, even when adjustment while visually recognizing is difficult, the sheet conveyance direction of the alignment adjustment conveyance roller pair can be changed by a desired amount.

  In this embodiment, only the service person or an operator who is familiar with the entire apparatus changes the sheet conveyance direction of the alignment adjustment conveyance roller pair, that is, it is not touched by general users. As shown in FIG. 1, the adjusting screw 76 is provided in the back of the front side plate 62B. However, when priority is given to workability over the risk of being touched by a general user, the adjustment screw 76 may be penetrated from the front side plate 62B and protrude to the front.

  In this embodiment, the example in which only the driven roller (alignment adjustment rollers 67A and 67B) is adjusted has been described. However, the drive roller 65 or both of the rollers 65, 67A and 67B are changed in the axial inclination. You may do it. Further, although the slide block 75 and the adjustment screw 76 are used as the adjusting means, a cam or a link may be used.

  By the way, in the description so far, the case where the sheet conveying direction is changed by changing the axial inclination of at least one of the driving roller 65 and the driven rollers (alignment adjusting rollers 67A and 67B) has been described. However, the present invention is not limited to this, and the sheet conveying direction of the conveying roller pair can be changed by adjusting the balance of the pressure contact pressure in the axial direction of the conveying roller pair.

  Next, a second embodiment of the present invention in which the sheet conveyance direction of the conveyance roller pair is changed by adjusting the balance of the pressure contact pressure of the conveyance roller pair will be described.

  FIG. 6 is a top view of the upstream double-sided conveyance unit 502A of the double-sided conveyance device 502 constituting the sheet conveyance device according to the present embodiment. In FIG. 6, the same reference numerals as those in FIG. 4 denote the same or corresponding parts.

  In FIG. 6, reference numeral 78 denotes a feed screw that is an adjustment means that is rotatably supported by a feed screw support portion 77 provided on the upper guide 62, and a range indicated by a symbol L at a tip portion of the feed screw 78. Is threaded. Reference numeral 79 denotes a pressure table that presses the pressure shaft 68A and presses the alignment adjustment rollers 67A and 67B against the drive roller 65 via the pressure shaft 68A. The pressure table 79 is a screw of the feed screw 78. As shown in FIG. 7, a bush 80 that is movable toward the center of the pressure shaft 68A and a spring 81 that presses the bush 80 against the pressure shaft 68A are provided.

  Thus, when the feed screw 78 is rotated, in the present embodiment, the pressing means that constitutes a changing means that changes the pressure contact pressure in the axial direction of the driving roller 65 and the alignment adjusting rollers 67A and 67B to change the sheet conveying direction. A certain pressure table 79 moves in parallel with the pressure shaft 68A while pressing the alignment adjusting rollers 67A and 67B via the pressure shaft 68A in conjunction with the rotation amount and direction of the feed screw 78. ing.

  In FIG. 7, reference numeral 79A denotes a slider that is provided on the bottom surface of the pressurizing table 79 and also serves as a rotation stopper for the pressurizing table 79. When the pressurizing table 79 moves, the slider 79A moves to the upper surface of the upper guide 62. It comes to slide. In FIG. 6, reference numeral 82 denotes a stopper, and the movement of the pressure base 79 in the width direction is restricted by the stopper 82.

  By the way, when the pressure table 79 is installed at the center of the alignment adjustment rollers 67A and 67B, that is, when the pressure table 79 presses the center of the pressure shaft 68A between the alignment adjustment rollers 67A and 67B. The pressure contact pressure between the alignment adjusting rollers 67A and 67B and the driving roller 65 is equal. Therefore, when it is assumed that the alignment adjustment rollers 67A and 67B and the driving roller 65 are not changed in outer shape due to wear or the like, the sheet S is conveyed straight.

  On the other hand, as shown by the broken line in FIG. 6, for example, when the sheet S is sent while being inclined as shown by a dotted line, it is necessary to turn the sheet S in the direction of arrow E in order to correct skew. In this case, the feed screw 78 is turned to move the pressurizing base 79 in the direction of arrow F (dotted line) on the front side of the apparatus. Here, when the pressure table 79 moves to the near side in this way, the distance in the axial direction between the pressure table 79 and each of the alignment adjustment rollers 67A and 67B changes, and each alignment adjustment roller 67A according to the difference in this distance. , 67B and the driving roller 65 change. In this case, the pressure contact pressure between the front alignment adjusting roller 67B and the driving roller 65 is increased.

  Since the sheet S is stronger in pressure contact, in other words, the conveyance speed is faster when the clamping nip is wider, the sheet S rotates counterclockwise as indicated by the arrow when the pressure table 79 moves in this way. Thus, the skew is corrected.

  Here, since the amount of movement of the pressurization table 79 is proportional to the amount of rotation of the feed screw 78, the adjustment can be performed accurately without visually recognizing the position of the pressurization table 79. If the current absolute position of the pressurizing table 79 is not known, the absolute position can be grasped by making adjustments after contacting the stopper 82 whose position is already known.

  In this way, by making the operation amount of the feed screw 78 and the movement amount of the pressurization table 79 proportional to each other, the apparatus main body 50A (double-sided conveyance) can be obtained without lowering or pulling out the unit even in a large apparatus. The inclination of the alignment adjusting rollers 67A and 67B in the axial direction can be adjusted only by operating the feed screw 78 from the side surface of the apparatus main body. Thereby, even when adjustment while visually recognizing is difficult, the sheet conveyance direction of the alignment adjustment conveyance roller pair can be changed by a desired amount.

  In this embodiment, the balance of the pressure contact pressure of the conveying roller pair is adjusted by moving the pressure position of the pressure table 79 in the axial direction, but pressure is applied to both ends of the pressure shaft 68A to The pressure may be adjusted independently. Further, although the feed screw 78 is used as the adjusting means, a cam or a link may be used.

  Furthermore, the configuration for adjusting the alignment of the conveying roller pair according to the first embodiment described above and the configuration for adjusting the balance of the pressure contact pressure of the conveying roller pair according to the present embodiment may be used in combination.

  Further, in the above description, the present invention is applied to an image forming apparatus that includes a double-sided conveyance device and capable of double-sided image formation. However, the present invention is not limited thereto, and, for example, processes a sheet after image formation. The present invention may be applied when the apparatus is large, that is, when the conveyance path is long, such as an image forming apparatus to which a plurality of sheet processing apparatuses are connected.

1 is a diagram illustrating a schematic configuration of a color image forming apparatus that is an example of an image forming apparatus including a sheet conveying device according to a first embodiment of the present invention. The figure which looked at the upstream double-sided conveyance part which comprises the said sheet conveying apparatus from diagonally behind. The principal part expansion perspective view of the said upstream double-sided conveyance part. The 1st figure explaining the operation | movement which changes the inclination of the axial direction of the alignment adjustment roller in the said upstream double-sided conveyance part. The 2nd figure explaining the operation | movement which changes the axial inclination of the alignment adjustment roller in the said upstream double-sided conveyance part. FIG. 6 is a top view of an upstream double-sided conveyance unit that constitutes a sheet conveyance apparatus according to a second embodiment of the present invention. The principal part side view of the said upstream double-sided conveyance part.

Explanation of symbols

50 Color image forming apparatus 54 Sheet conveying apparatus 65 Drive rollers 67A and 67B
Alignment adjustment roller 68A Pressure shaft 70 Rotating frame 72 Oscillation center hole 72a Boss 75 Abutting block 75a Abutting surface 76 Screw 78 Feed screw 79 Pressurization table 502 Double-sided conveyance device 502A Upstream double-sided conveyance unit 502B Downstream double-sided conveyance unit 513 Image forming unit S sheet

Claims (9)

In a sheet conveying apparatus for nipping and conveying a sheet by a pair of conveying rollers constituted by a driving roller and a driven roller pressed against the driving roller,
Changing means for changing the sheet conveying direction of the conveying roller pair;
An adjusting means for adjusting a change amount of the sheet conveying direction by the changing means by an operation from a side surface of the apparatus main body;
With
A sheet conveying apparatus characterized in that an operation amount of the adjusting unit for changing a sheet conveying direction of the conveying roller pair is proportional to a change amount of the sheet conveying direction by the changing unit.   The changing means changes the sheet conveying direction by changing an axial inclination of at least one of the driving roller and the driven roller, and rotatably holds the at least one roller. The sheet conveying apparatus according to claim 1, further comprising a roller support portion that is swingably held by the apparatus main body.   The said roller support part hold | maintains the axis | shaft which supports the several roller part provided in the axial direction, and rock | fluctuates by using the gravity center position of the axial direction of the said several roller part as a fulcrum. Sheet conveying device.   The adjusting means includes a screw and an abutting member that moves in an axial direction in conjunction with a rotation operation of the screw, and the abutting member abuts on the roller support and swings. Item 4. The sheet conveying apparatus according to Item 2 or 3.   The sheet conveying apparatus according to claim 4, wherein a contact surface of the contact member with the roller support portion is tapered.   The changing means changes the sheet conveying direction by changing the axial pressure of the driving roller and the driven roller, and changes the shaft of at least one of the driving roller and the driven roller. 2. The sheet conveying apparatus according to claim 1, further comprising pressing means that presses and moves in the axial direction in conjunction with an operation of the adjusting means to change a pressing portion of the shaft.   The sheet conveying apparatus according to claim 6, wherein the adjusting unit is a screw, and the pressing unit is moved in an axial direction by a rotation operation.   An image forming apparatus comprising: an image forming unit that forms an image on a sheet; and the sheet conveying device according to claim 1 that conveys the sheet to the image forming unit. . The image forming apparatus according to claim 8, wherein the changing unit is provided upstream of the image forming unit in a sheet conveying direction.

Images