JP2020040819A - Sheet transport device and image formation device - Google Patents

Abstract

To provide a sheet transport device and an image formation device that are capable of reducing impact noise made when a sheet collides with the rollers.SOLUTION: A sheet transport device includes: a driving roller 3; a following roller 4 that forms a nip part N with the driving roller 3 for transporting a sheet; a sliding member 21 that is slidable so as to contact or separate from the driving roller 3 in an integrated manner with the following roller 4; a spring 26 that energizes the sliding member 21 against the driving roller 3; a first guiding face 25a that is provided on the upstream of the nip part N in the sheet transport direction and guides the sheet to the nip part N; and a second guide face 21a that is provided on the sliding member 21 and guides the sheet to the nip part N. As viewed from the axial direction of the following roller 4, the first guide face 25a and an outer periphery surface 4b of the following roller 4 cross each other at a first intersection 34, and the second guide face 21a guides the sheet received from the first guide face 25a to the nip part N without guiding it to the first intersection 34.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a sheet conveying device for conveying a sheet and an image forming apparatus including the same.

  2. Description of the Related Art Conventionally, there has been proposed a medium printing apparatus that includes a driving roller and a pinch roller that rotates following the driving roller, and that conveys a sheet to a medium conveying path formed by a pair of guide plates (Japanese Patent Application Laid-Open No. H10-157210). 1). The pinch roller is rotatably supported by a pinch roller support, and the pinch roller support is rotatably supported about a fulcrum axis. A guide portion protruding into the medium transport path is formed in the pinch roller support portion, and a sheet guided by a pair of guide plates is guided by a guide portion to a nip formed by a driving roller and a pinch roller. Is done.

JP 2005-88216 A

  However, the pinch roller support described in Patent Literature 1 rotates about a fulcrum shaft in accordance with the thickness of the sheet, wear of the roller, and the like, and the pinch roller support rotates. Relative position changes. In particular, when viewed in the axial direction of the pinch roller, the angle formed between the guide portion and the guide plate changes.

  In general, as the angle between the guide portion and the guide plate is closer to 180 degrees, the conveyance resistance of the sheet is smaller, and the leading end of the sheet is smoothly guided to the nip portion. When the angle between the guide portion and the guide plate is reduced by the rotation of the pinch roller support portion, the impact at the time of collision between the leading end of the sheet and the guide portion increases, and a large impact noise may be generated. is there.

  Therefore, an object of the present invention is to provide a sheet conveying device and an image forming apparatus that provide a second guide surface on a slide member that slides integrally with a second rotating body and solve the above-described problems.

  According to the present invention, in a sheet conveying apparatus, a first rotatable rotatable member, and a second rotator that forms a nip portion that conveys a sheet together with the first rotator and that is driven to rotate with respect to the first rotator. A sliding member slidably movable toward and away from the first rotating body integrally with the second rotating body, and an urging member for urging the sliding member toward the first rotating body; A first guide surface disposed upstream of the nip portion in the sheet conveyance direction and guiding the sheet toward the nip portion; and a second guide surface provided on the slide member and guiding the sheet toward the nip portion. Wherein the first guide surface and the outer peripheral surface of the second rotator intersect at a first intersection when viewed in the axial direction of the second rotator, and wherein the second guide surface is The sheet delivered from the surface Without guiding the one-intersection to guide the nip, characterized in that.

  According to the present invention, it is possible to reduce the impact sound when the front end of the sheet collides with the outer peripheral surface of the driven roller.

FIG. 1 is an overall schematic diagram illustrating a printer according to a first embodiment. FIG. 3 is a perspective view showing a skew correction device. FIG. 4 is a side view showing a shutter cam and a shutter member. The perspective view showing a slide member. Sectional drawing which shows a slide member. 9A and 9B are side views illustrating the skew feeding correction device according to Comparative Example 1, in which FIG. 9A illustrates a state where the guide arm is at a normal position, and FIG. (A) is a side view showing the skew correction device according to Comparative Example 2, and (b) is a side view showing the skew correction device according to the present embodiment. 9A is a cross-sectional view illustrating a skew feeding correction device according to Comparative Example 2, in which FIG. 10A illustrates a state in which the leading end of a sheet abuts a driven roller to form a loop, and FIG. 10B illustrates a state in which the sheet loop is released. Is shown. FIG. 5 is a side view showing the arrangement of the second guide surface of the slide member according to the first embodiment. 7 is a graph showing an impact sound in Comparative Example 2 and the first embodiment. FIG. 9 is a perspective view illustrating a sheet conveying device according to a second embodiment. FIG. 9 is a side view showing the arrangement of the second guide surface of the slider member. FIG. 13 is a perspective view showing a slider member according to a third embodiment.

  Hereinafter, an image forming apparatus according to the present disclosure will be described with reference to the drawings. The image forming apparatus includes a printer, a copier, a facsimile, and a multifunction peripheral, and forms an image on a sheet used as a recording medium based on image information input from an external PC or image information read from a document. Sheets used as recording media include paper such as paper and envelopes, plastic films for overhead projectors, and fabrics.

<First embodiment>
〔overall structure〕
First, a first embodiment of the present invention will be described. The printer 100 as an image forming apparatus according to the first embodiment is an electrophotographic full-color laser beam printer. As illustrated in FIG. 1, the printer 100 includes a feeding unit 200 that feeds a sheet, a skew correction device 300 that transports the sheet fed by the feeding unit 200, and an image forming apparatus that forms an image on a sheet. Unit 400. Further, the printer 100 includes a fixing device 12 for fixing an image formed by the image forming unit 400 to a sheet, and a discharge roller pair 11 for discharging the sheet outside the apparatus. A document reading device for reading a document image may be optionally provided above the printer 100.

  When an instruction to form an image is output to printer 100, an image forming process by image forming section 400 is started based on image information input from a document reading device or an external computer connected to printer 100. The image forming unit 400 includes a scanner unit 2 and four process cartridges 7Y, 7M, 7C, and 7Bk that form images of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). , Is provided. The four process cartridges 7Y, 7M, 7C, and 7Bk have the same configuration except that the colors of the images to be formed are different. Only the image forming process of the process cartridge 7Y will be described, and the process cartridges 7M, 7C, and 7Bk will be described. Description is omitted.

  The scanner unit 2 irradiates a laser beam toward the photosensitive drum 1 of the process cartridge 7Y based on the input image information. At this time, the photosensitive drum 1 is charged in advance by a charging roller (not shown), and an electrostatic latent image is formed on the photosensitive drum 1 by irradiating the laser light L from the scanner unit 2. Thereafter, the electrostatic latent image is developed by a developing roller (not shown), and a yellow (Y) toner image is formed on the photosensitive drum 1.

  Similarly, magenta (M), cyan (C), and black (Bk) toner images are formed on the photosensitive drums of the process cartridges 7M, 7C, and 7Bk. The toner images of each color formed on each photosensitive drum are transferred to the intermediate transfer belt 9 by the primary transfer rollers 5Y, 5M, 5C, and 5Bk, and are transferred by the intermediate transfer belt 9 rotated by the belt drive roller 8. Transported to The image forming process of each color is performed at a timing of superimposing the image on the upstream toner image primarily transferred onto the intermediate transfer belt 9.

  The sheet S is fed by the feeding unit 200 in parallel with the above-described image forming process. The feeding unit 200 includes a cassette 10 that can be pulled out and mounted to the printer main body 100A, and an intermediate plate 22 that is supported by the cassette 10 so as to be able to move up and down and stacks sheets S. The sheets S stacked on the intermediate plate 22 are fed by the pickup roller 15 and separated one by one by the feed roller 16 and the separation roller 17. A torque limiter (not shown) is connected to the separation roller 17. The torque limiter applies a rotational load to the separation roller 17 so that the sheets can be separated one by one.

  The sheet S fed by the feeding unit 200 is conveyed toward the skew feeding correction device 300 by the conveying roller pair 18 as an upstream rotating body pair. The skew of the sheet S is corrected by the leading edge of the sheet abutting by the skew correction device 300 as a sheet conveying device. Then, the sheet S is conveyed at a timing at which the sheet S is aligned with the toner image on the intermediate transfer belt 9 by the skew feeding correction device 300.

  The full-color toner image on the intermediate transfer belt 9 is transferred to the sheet S by the secondary transfer roller 6. The sheet S to which the toner image has been transferred is given a predetermined heat and pressure by the fixing device 12, and the toner is melted and fixed. The sheet S that has passed through the fixing device 12 is discharged by a discharge roller pair 11 to a discharge tray 13 formed on the upper surface of the printer 100.

[Skew Correction Device]
Next, the skew feeding correction device 300 will be described in detail. As shown in FIG. 2, the skew feeding correction device 300 includes a drive shaft 3a that rotatably supports a plurality of (five in the present embodiment) drive rollers 3, a shutter shaft 27 extending in parallel with the drive shaft 3a. ,have. A driving force from a motor (not shown) is input to the driving shaft 3a, and the plurality of driving rollers 3 are driven by the driving force of the motor. The skew feeding correcting device 300 has a plurality of driven rollers 4 in the same number as the plurality of driving rollers 3, and each driven roller 4 forms a nip portion N that conveys a sheet together with each driving roller 3, 3 is driven to rotate. The driving roller 3 as the first rotating body and the driven roller 4 as the second rotating body constitute a registration roller pair 23.

  A plurality of (four in the present embodiment) shutter members 24 are fixed to the shutter shaft 27 in the same phase as each other. These shutter members 24 are two adjacent driven rollers in the axial direction of the shutter shaft 27. 4 are arranged. A shutter cam 28 is fixed to one end of the shutter shaft 27 in the axial direction, and the shutter shaft 27, the shutter member 24, and the shutter cam 28 rotate integrally.

  As shown in FIG. 3, the shutter member 24 has three abutting surfaces 24a, and the shutter cam 28 has three concave portions 28a. The skew feeding correcting device 300 has a pressing member 29 that can swing about a swing shaft 29a, and a cam follower 31 is rotatably supported at the tip of the pressing member 29. The pressing member 29 is urged by a shutter spring 30 in a direction in which the cam follower 31 approaches the shutter cam 28.

  The shutter cam 28 is held in a state where the cam follower 31 is pressed against any of the concave portions 28a, and at this time, any one of the three abutting surfaces 24a protrudes into the transport path through which the sheet passes. The abutting surface 24a protruding into the transport path is located upstream of the nip portion N in the sheet transport direction.

  Therefore, before the sheet S conveyed by the conveying roller pair 18 enters the nip portion N of the registration roller pair 23, the sheet S abuts against the abutting surface 24a of the shutter member 24 protruding into the conveying path. The skew of the sheet S is corrected by the leading ends of the sheets S abutting against the abutting surfaces 24a of the plurality of shutter members 24. The rotation of the shutter member 24 is regulated by the urging force of the shutter spring 30, and the sheet S forms a loop with the leading end abutting against the abutting surface 24a. When the sheet S is further conveyed by the conveying roller pair 18, the pressing force of the sheet S exceeds the urging force of the shutter spring 30, and the shutter member 24 rotates.

  The sheet S enters the nip portion N of the registration roller pair 23 in a state where the skew is corrected, and the registration roller pair 23 conveys the sheet S at a timing when the sheet S is aligned with the toner image on the intermediate transfer belt 9. I do. The shutter member 24 stands by in contact with the surface of the sheet S being conveyed. When the trailing end of the sheet S passes through the shutter member 24, the cam follower 31 enters the next concave portion 28a and stops rotating. In this state, the next abutment surface 24a of the shutter member 24 protrudes into the transport path, and prepares for the subsequent sheet. Thus, the shutter member 24 and the shutter cam 28 rotate by 120 degrees each time one sheet S passes.

[Peripheral configuration of driven roller]
As shown in FIGS. 4 and 5, the driven roller 4 has a hollow shaft portion 4a through which the shutter shaft 27 passes. The shaft portion 4a protrudes outward in the axial direction from the outer peripheral surface 4b of the driven roller 4 that contacts the sheet S. A feeding frame 25 as a frame member is fixed to the printer main body 100A (see FIG. 1). The feeding frame 25 is provided with a curved first guide surface 25a for guiding the sheet S and a guide groove 25b for slidably supporting the shaft 4a of the driven roller 4. The driven roller 4 extends in a direction in which a straight line connecting the drive shaft 3a and the shutter shaft 27 extends in the axial direction (in a direction indicated by an arrow CD in FIG. 5), that is, a direction in which the driven roller 4 moves toward and away from the drive roller 3 by the guide groove 25b. Can be slid.

  Further, the skew feeding correcting device 300 has the same number of slide members 21 as bearing members that rotatably support the shaft portion 4a of the driven roller, and the slide member 21 slides in the guide groove 25b. It has a slide portion 21b movably supported. That is, the drive roller 3, the driven roller 4, and the slide member 21 are arranged in parallel in the axial direction. A spring 26 as an urging member is stretched between the slide member 21 and the feeding frame 25, and the driven roller 4 is driven by the urging force of the spring 26 via the slide member 21. It is biased toward 3. In this manner, the slide member 21 is slidable in the direction of the arrow CD with respect to the drive roller 3 integrally with the driven roller 4.

  The driven roller 4 slides in the direction of arrow CD due to the thickness of the sheet S passing through the nip N and the wear of the registration roller pair 23. At this time, a sufficient clearance is secured between the shaft portion 4a of the driven roller 4 having the hollow portion and the shutter shaft 27, and the biasing force of the spring 26 acts on the shutter shaft 27 from the driven roller 4. Never. Thus, the urging force of the spring 26 does not hinder the rotation operation of the plurality of shutter members 24 fixed integrally with the shutter shaft 27. Further, the slide member 21 has a second guide surface 21a described later.

[Comparative Example 1]
Here, a skew feeding correction device 300A according to Comparative Example 1 will be described with reference to FIG. As shown in FIGS. 6A and 6B, the skew feeding correction device 300 </ b> A includes a conveyance guide 61 having a first guide surface 61 a for guiding a sheet, and a rotation about the rotation shaft 62 b with respect to the conveyance guide 61. And a guide arm 62 movably supported. Further, the skew feeding correcting device 300A has a registration roller pair 65 including a driving roller 63 and a driven roller 64, and the driven roller 64 is rotatably supported by the guide arm 62. The guide arm 62 is urged by a torsion spring 66 screwed to the rotation shaft 62b so that the driven roller 64 comes into contact with the drive roller 63. The driving roller 63 and the driven roller 64 form a nip portion 65a for nipping and conveying the sheet.

  The guide arm 62 has a second guide surface 62a for guiding the sheet guided by the first guide surface 61a to the nip portion 65a. As shown in FIG. 6A, the angle θ1 is an angle formed between the first guide surface 61a and the second guide surface 62a. On the other hand, when the axis of the driving roller 63 is bent upward due to the pressing of the driving roller 63 by the driven roller 64, for example, as shown in FIG. It rotates upward compared to a). Therefore, the angle θ2 between the first guide surface 61a and the second guide surface 62a is smaller than the angle θ1 (θ2 <θ1).

  Generally, as the angle between the first guide surface 61a and the second guide surface 62a is closer to 180 degrees, the sheet conveyance resistance on the second guide surface 62a is smaller, and the leading end of the sheet is smoothly guided to the nip portion 65a. . When the angle between the first guide surface 61a and the second guide surface 62a decreases, the impact when the front end of the sheet collides with the second guide surface 62a increases, and an impact sound is generated, The posture is easily disturbed. In particular, the tendency is strong in a cardboard having high rigidity. In addition, the components of the skew feeding correcting device 300A tend to be smaller from the viewpoint of a demand for miniaturization of the device and cost reduction, and the smaller the turning radius of the guide arm 62, the larger the amount of change from the angle θ1 to the angle θ2. Become.

[Comparative Example 2]
Next, a skew feeding correction device 300B according to Comparative Example 2 will be described with reference to FIGS. As shown in FIG. 7A, the skew feeding correcting device 300B according to the comparative example 2 has a slide member 121 that slides integrally with the driven roller 4, and the slide member 121 is provided in the present embodiment. It does not have the second guide surface 21a as shown in FIG. 7 (b). The skew feeding correction device 300B according to Comparative Example 2 differs from the skew feeding correction device 300 according to the present embodiment only in the shape of the slide member 121, and therefore, illustrations of the same configurations as those in the present embodiment are omitted. , Or the drawings are denoted by the same reference numerals.

  As shown in FIG. 7A, when viewed in the axial direction of the driven roller 4, the first guide surface 25 a and the outer peripheral surface 4 b of the driven roller 4 intersect at a first intersection 34. The nip line L1 at the nip portion 18a of the pair of conveying rollers 18 intersects the first guide surface 25a upstream of a later-described second intersection 41 in the sheet conveying direction. Therefore, the leading end of the sheet S conveyed by the conveying roller pair 18 contacts the first guide surface 25a and is guided to the first intersection 34 while sliding on the first guide surface 25a.

  Then, as shown in FIG. 8A, the leading end of the sheet S collides with the outer peripheral surface 4b of the driven roller 4 at the first intersection 34. At this time, a loud impact sound is first generated. For a very short time after the front end of the sheet S collides with the outer peripheral surface 4b, the sheet S forms a small loop with the front end of the sheet S abutting on the outer peripheral surface 4b. Then, as shown in FIG. 8B, at the moment when the loop is released, the energy stored in the loop may cause the leading end of the sheet S to vigorously collide with the abutting surface 24a of the shutter member 24. As a result, a loud impact sound may be generated or the posture of the sheet S may be disturbed.

[Arrangement of second guide surface]
Therefore, in the present embodiment, the front end of the sheet S is smoothly guided to the nip portion N of the registration roller pair 23 by the second guide surface 21a provided on the slide member 21 so as to reduce the above-described impact sound and to reduce the impact sound. The disturbance of the posture of S is suppressed. As shown in FIG. 7B, at least a part of the second guide surface 21 a in the present embodiment has a first intersection 34 with respect to the rotation center 32 of the driven roller 4 when viewed in the axial direction of the driven roller 4. It is located at a farther position.

  More specifically, as shown in FIG. 9, when viewed in the axial direction of the driven roller 4, the first guide surface 25 a and the second guide surface 21 a intersect at the second intersection 41, and follow the second guide surface 21 a. The outer peripheral surface 4b of the roller 4 intersects at a third intersection 42. In the sheet conveyance direction, the second intersection 41 is located upstream of the first intersection 34, and the third intersection 42 is located downstream of the first intersection 34. As described above, the second guide surface 21 a is located between the second intersection 41 and the third intersection 42 and is transported between the transport roller pair 18 and the nip portion N of the registration roller pair 23 more than the first intersection 34. It protrudes toward the road CP. Accordingly, the second guide surface 21a can guide the sheet S delivered from the first guide surface 25a to the nip N without guiding to the first intersection 34.

  Further, at the second intersection 41, the angle θ3 formed by the first guide surface 25a and the second guide surface 21a is larger than the angle θ4 formed by the first guide surface 25a and the outer peripheral surface 4b of the driven roller 4 at the first intersection 34. Is also big. For this reason, the leading end of the sheet S is not caught by the outer peripheral surface 4b of the driven roller 4 as described in Comparative Example 2, but is scooped up by the second guide surface 21a and smoothly guided to the nip portion N. Accordingly, it is possible to prevent the sheet S from generating a loud impact sound in the vicinity of the driven roller 4 and reduce the disturbance of the posture of the sheet S.

  As shown in FIG. 4, the second guide surface 21a of the slide member 21 includes a first guide portion 51 disposed on one side of the outer peripheral surface 4b of the driven roller 4 in the axial direction, and another side of the outer peripheral surface 4b. And a second guide portion 52 disposed at the second position. The shaft 4a of the driven roller 4 partially overlaps the first guide 51 and the second guide 52 in the axial direction. As described above, since the first guide portion 51 and the second guide portion 52 are arranged on both sides in the axial direction of the outer peripheral surface 4b, the sheet S is stably nipped by the first guide portion 51 and the second guide portion 52. It can be guided to the section N.

  In the present embodiment, unlike the comparative example 1, the slide member 21 having the second guide surface 21a is configured to be slidable integrally with the driven roller 4. As a result, the following effects can be obtained.

  First, it is possible to reduce the variation in the amount of protrusion d1 of the outer peripheral surface 4b of the driven roller 4 from the second guide surface 21a. That is, the slide member 21 is constantly urged by the spring 26 to press the shaft portion 4 a of the driven roller 4 at the slide portion 45. For this reason, the dimensional tolerance of the dimension d2 from the sliding portion 45 to the second guide surface 21a can be minimized, and the variation in the protrusion amount d1 can be controlled to a small value.

  Second, even when the registration roller pair 23 moves, the angle θ3 can be kept constant. For example, when the drive shaft 3a is bent by the urging force of the spring 26, the registration roller pair 23 moves to the left in FIG. In this case, since the slide member 21 also slides to the left along with the registration roller pair 23, the protrusion amount d1 does not change. For this reason, at the intersection 42, the front end of the sheet S does not hit the outer peripheral surface 4b, and the impact noise does not increase.

  Further, as the slide member 21 moves, the relative positional relationship of the first guide surface 25a with respect to the slide member 21 becomes as shown by a two-dot chain line in FIG. Since the slide member 21 slides linearly by the guide groove 25b (see FIG. 5) of the feeding frame 25, the angle θ3 hardly changes even if the slide member 21 moves. On the other hand, when the guide arm 62 swings with the movement of the driven roller 64 as in Comparative Example 1 described with reference to FIG. 6, the angle θ1 changes to the angle θ2 (<θ1). Then, the impact at the time of collision between the leading end of the sheet and the second guide surface 62a becomes large, so that an impulsive sound is generated or the posture of the sheet is easily disturbed. In contrast, in the present embodiment, since the angle θ3 does not change regardless of the position of the driven roller 4, it is possible to reduce the impact noise and the disturbance of the seat posture.

  FIG. 10 is a graph showing the magnitude of the impact sound near the nip N in the present embodiment and Comparative Example 2. In FIG. 10, the solid line indicates the magnitude of the impact sound in Comparative Example 2 without the second guide surface 21a, and the dashed line indicates the magnitude of the impact sound in the present embodiment with the second guide surface 21a. The horizontal axis in FIG. 10 indicates the elapsed time [ms] from the start of feeding of the sheet S, and the vertical axis indicates the sound pressure level [dB]. At the elapsed time t1, the leading end of the sheet S abuts on the outer peripheral surface 4b of the driven roller 4 at the first intersection 34. At the elapsed time t2, the leading end of the sheet S abuts against the abutting surface 24a of the shutter member 24.

  In the case of Comparative Example 2 (shown by a solid line), a loud impact sound is generated from the elapsed time t1, that is, from the moment when the leading end of the sheet S enters the driven roller 4 at the first intersection point 34. On the other hand, in the case of the present embodiment (indicated by a broken line), no impulsive sound is generated at the same timing as that of Comparative Example 2, and the second intersection 41 smoothly generates the impulsive sound without generating a loud impulsive sound. It can be seen that the leading end is transferred to the second guide surface 21a. Then, at the timing when the leading end of the sheet S abuts against the abutting surface 24a of the shutter member 24, that is, at the elapsed time t2, a slight impact sound is generated. That is, it can be seen that the impact noise generated near the driven roller 4 is reduced.

  When there is no second guide surface 21a as in Comparative Example 2, the loop formed on the sheet S is released, so that the impact sound when colliding with the abutting surface 24a of the shutter member 24 is increased. Become. In FIG. 10, since the impact sound generated at the first intersection 34 also occurs on the abutting surface 24 a before the impact sound is completely attenuated, the impact sound at the timing when the leading end of the sheet S reaches the abutting surface 24 a is obtained. The size is larger in Comparative Example 2 than in the present embodiment.

<Second embodiment>
Next, a second embodiment of the present invention will be described. In the second embodiment, the same slide member as in the first embodiment can be slid integrally with the driven roller 36 of the transport roller pair 18. It is provided so that Therefore, configurations similar to those of the first embodiment will be described by omitting illustration or by attaching the same reference numerals to the drawings.

  The sheet conveying apparatus 600 according to the second embodiment includes a conveying roller pair 18 and a slide member 221 as shown in FIGS. The slide member 221 rotatably supports the shaft portion 36 a of the driven roller 36 of the transport roller pair 18, and is urged by a spring 226 as an urging member so that the driven roller 36 presses the drive roller 35. ing. The slide member 221 has a slide portion 221b that is slidably supported in a guide groove (not shown) of the transport frame 37. In this manner, the slide member 221 is slidable in the direction of the arrow with respect to the drive roller 35 integrally with the driven roller 36.

[Arrangement of second guide surface]
In the present embodiment, the second guide surface 221a provided on the slide member 221 smoothly guides the leading end of the sheet S to the nip portion 18a of the pair of conveying rollers 18, thereby reducing the impact sound and changing the posture of the sheet S. The disturbance is suppressed.

  As shown in FIG. 12, when viewed in the axial direction of the driven roller 36, a first guide surface 37 a of the transport frame 37 as a frame member and an outer peripheral surface 36 b of the driven roller 36 intersect at a first intersection 234. When viewed in the axial direction of the driven roller 36, the first guide surface 37 a and the second guide surface 221 a intersect at a second intersection 241, and the second guide surface 221 a and the outer peripheral surface 36 b of the driven roller 36 form a third intersection 242 Intersect at In the sheet conveyance direction, the second intersection 241 is located upstream of the first intersection 234, and the third intersection 242 is located downstream of the first intersection 234. As described above, the second guide surface 221a protrudes toward the transport path CP from the first intersection 234 between the second intersection 241 and the third intersection 242. Thereby, the second guide surface 221a can guide the sheet S delivered from the first guide surface 37a to the nip portion 18a without guiding to the first intersection 234.

  Further, at the second intersection 241, the angle θ5 formed by the first guide surface 37 a and the second guide surface 221 a is larger than the angle θ6 formed by the first guide surface 37 a and the outer peripheral surface 36 b of the driven roller 36 at the first intersection 234. Is also big. Therefore, the leading end of the sheet S is not caught by the outer peripheral surface 36b of the driven roller 36, but is scooped up by the second guide surface 221a and smoothly guided to the nip portion 18a. Accordingly, it is possible to prevent the sheet S from generating a loud impact sound in the vicinity of the driven roller 36 and reduce the disturbance of the posture of the sheet S. The other effects of the second guide surface 221a of the slide member 221 are the same as those of the first embodiment, and the description is omitted.

<Third embodiment>
Next, a third embodiment of the present invention will be described. In the third embodiment, the slide member of the first embodiment has a different shape. Therefore, configurations similar to those of the first embodiment will be described by omitting illustration or by attaching the same reference numerals to the drawings.

  As shown in FIG. 13, the slide member 321 slidable integrally with the driven roller 4 has a second guide surface 321a for guiding the sheet S toward the nip N. The second guide surface 321a includes the first guide portion 51 and the second guide portion 52 described above, and the third guide portion 53 disposed between the first guide portion 51 and the second guide portion 52 in the axial direction. Have. The third guide portion 53 is disposed upstream of the outer peripheral surface 4b of the driven roller 4 in the sheet conveying direction. The third guide portion 53 can reliably guide the leading end of the sheet S even if the leading end of the sheet S is bent so as to undulate, for example, and the leading end of the sheet S abuts on the outer peripheral surface 4 b of the driven roller 4. Has been prevented. Thereby, the impact noise can be reduced. Note that a plurality of third guide portions 53 may be provided between the first guide portion 51 and the second guide portion 52.

  In any of the above-described embodiments, the first guide surface and the second guide surface do not need to intersect when viewed in the axial direction of the driven roller. For example, in the first embodiment, when viewed in the axial direction, the first guide surface 25a and the second guide surface 21a do not need to intersect at the second intersection 41, and the first guide surface 25a and the second guide surface 21a may be provided with a space. Similarly, the second guide surface does not have to intersect with the outer peripheral surface of the driven roller. In any case, the sheet may be transferred from the first guide surface 25a to the second guide surface 21a, and the leading edge of the sheet may be guided to the nip N without being guided to the first intersection 34.

  Although the third embodiment is configured by modifying the first embodiment, the third embodiment and the second embodiment may be combined. Further, the present invention may be applied to any sheet conveying device including a pair of rollers in the printer 100.

  In each of the above-described embodiments, the description has been made using the electrophotographic printer 100, but the present invention is not limited to this. For example, the present invention can be applied to an ink jet type image forming apparatus that forms an image on a sheet by discharging ink liquid from a nozzle.

  3, 35: first rotating body (drive roller) / 4, 36: second rotating body (driven roller) / 4b, 36b: outer peripheral surface / 18: upstream rotating body pair (transport roller pair) / 18a, N: nip Part / 21, 221: slide member / 21a, 221a: second guide surface / 25, 37: frame member (feeding frame, transport frame) / 25a, 37a: first guide surface / 26, 226: urging member ( Springs) / 34, 234: first intersection / 41, 241: second intersection / 42, 242: third intersection / 51: first guide portion / 52: second guide portion / 53: third guide portion / 100: Image forming apparatus (printer) / 300, 600: sheet conveying apparatus (skew correction apparatus) / 400: image forming section / CP: conveying path / L1: nip line / θ3, θ4, θ5, θ6: angle

Claims (11)

A rotatable first rotating body,
A second rotator that forms a nip portion that conveys a sheet together with the first rotator, and that is driven to rotate with respect to the first rotator;
A slide member slidably movable so as to come into contact with and separate from the first rotator integrally with the second rotator;
An urging member for urging the slide member toward the first rotating body;
A first guide surface disposed upstream of the nip in the sheet conveyance direction and guiding a sheet toward the nip;
A second guide surface provided on the slide member for guiding a sheet toward the nip portion;
When viewed in the axial direction of the second rotating body, the first guide surface and the outer peripheral surface of the second rotating body intersect at a first intersection,
The second guide surface guides the sheet delivered from the first guide surface to the nip portion without guiding the sheet to the first intersection.
A sheet conveying device, characterized in that: When viewed in the axial direction, the first guide surface and the second guide surface intersect at a second intersection,
The second intersection is located upstream of the first intersection in the sheet conveyance direction.
The sheet conveying device according to claim 1, wherein: When viewed in the axial direction, the second guide surface and the outer peripheral surface of the second rotating body intersect at a third intersection,
The second guide surface protrudes between the second intersection and the third intersection on the side of the conveyance path through which a sheet passes, relative to the first intersection.
The sheet conveying device according to claim 2, wherein: An angle formed between the first guide surface and the second guide surface at the second intersection is larger than an angle formed between the first guide surface and the outer peripheral surface of the second rotating body at the first intersection.
The sheet conveying device according to claim 2, wherein An upstream rotating body pair that is disposed upstream of the first guide surface in the sheet transport direction and transports the sheet;
The first guide surface is curved, and intersects a nip line of the upstream rotating body pair upstream of the second intersection in the sheet conveyance direction.
The sheet conveying device according to any one of claims 2 to 4, wherein: Further comprising a frame member that slidably supports the second rotating body and the slide member, respectively.
The sheet conveying device according to any one of claims 1 to 5, wherein: The second guide surface is provided on a first guide portion disposed on one side of the outer peripheral surface of the second rotating body in the axial direction, and on a second side of the outer peripheral surface of the second rotating body in the axial direction. A second guide portion to be arranged,
The sheet conveying device according to any one of claims 1 to 6, wherein: A third guide surface disposed between the first guide portion and the second guide portion in the axial direction, and a third guide surface disposed upstream of the outer peripheral surface of the second rotating body in the sheet conveyance direction; Having a guide portion,
The sheet conveying device according to claim 7, wherein: A plurality of the first rotator, the second rotator, and the slide member are juxtaposed in the axial direction;
The sheet conveying device according to claim 1, wherein Correct the skew of the sheet by hitting the leading edge of the sheet,
The sheet conveying device according to claim 1, wherein: A sheet conveying device according to claim 1,
An image forming unit that forms an image on a sheet,
An image forming apparatus comprising:

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