Sheet conveyance device

Abstract

To reduce the reduction of the contact area between the shaft of a roller and a bearing and to reduce wear of the bearing in a sheet conveyance device having a bearing.SOLUTION: The sheet conveyance device clamps and conveys a sheet by means of a first roller and a second roller urged towards the first roller by an energizing member. The sheet conveyance device is held in a frame and has a bearing that slidably holds the roller shaft of the first roller and is deformable. When viewed in the direction of the axis of rotation of the roller shaft, a direction in which the second roller is energized by the energizing member is assumed to be a first direction, a direction perpendicular to the first direction is assumed to be a second direction and an area in which the roller shaft is present with respect to the second direction is assumed to be a first area. In the downstream side from the center of rotation of the roller shaft with respect to the first direction, the frame holds the bearing so that the frame and the bearing do not come into contact in the first area.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a sheet transport device that transports a sheet. [Background technology]

[0002] In a sheet conveying device and an image forming apparatus such as an electrophotographic type having the sheet conveying device, a method is known in which a pair of opposing rollers are rotated to sandwich and convey a recording material (sheet). Here, as in Patent Document 1, a method is known in which a roller shaft on which a roller is attached is slidably held by a bearing.

[0003] One possible configuration of the roller shaft and bearing is a cylindrical bearing with a hole formed therein that holds a cylindrical roller shaft with the same diameter as the hole. In this case, taking into account dimensional tolerances, etc., the diameter of the bearing hole is larger than the diameter of the roller shaft, and a gap exists between the bearing and the roller shaft. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-132544 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a sheet conveying device, the bearings may wear out at the sliding portions where the bearings hold the roller shafts.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to suppress a decrease in the contact area between a roller shaft and a bearing in a sheet transport device having a bearing, and to suppress wear of the bearing. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides A sheet conveying device, A frame, A first roller for conveying a sheet; A roller shaft that holds the first roller; a second roller that faces the first roller and conveys a sheet by nipping the sheet together with the first roller; a biasing member that biases the second roller toward the first roller in a direction intersecting a rotational axis direction of the roller shaft; a bearing that slidably holds the roller shaft and is held by the frame and is deformable; having When viewed in the rotational axis direction of the roller shaft, a direction in which the biasing member biases the second roller is defined as a first direction, a direction perpendicular to the first direction is defined as a second direction, and a region in which the roller shaft exists in the second direction is defined as a first region, the frame holds the bearing so that the frame and the bearing do not come into contact with each other in the first region downstream of the rotation center of the roller shaft in the first direction. It is characterized by:

[0008] Further, the present invention relates to A sheet conveying device, A frame, A first roller for conveying a sheet; A roller shaft that holds the first roller; a second roller that faces the first roller and conveys a sheet by nipping the sheet together with the first roller; a biasing member that biases the second roller toward the first roller in a direction intersecting a rotational axis direction of the roller shaft; a bearing that slidably holds the roller shaft and is held by the frame and is deformable, the bearing having a receiving portion that holds the roller shaft, and a bottom portion that is located downstream of the receiving portion in the first direction and in the first region, where, as viewed in the direction of the rotation axis of the roller shaft, a direction in which the biasing member biases the second roller is defined as a first direction, a direction perpendicular to the first direction is defined as a second direction, and a region in which the roller shaft exists in the second direction is defined as a first region, the bottom portion abutting against the frame; having The bearing includes a hole disposed between the receiving portion and the bottom portion such that the receiving portion and the bottom portion do not contact each other in the first region. It is characterized by: Effect of the Invention

[0009] In a sheet transport device having a bearing, it is possible to suppress a reduction in the contact area between the roller shaft and the bearing, and to suppress wear of the bearing. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an image forming apparatus having a sheet conveying device according to a first embodiment. [Diagram 2] FIG. 1 is a perspective view showing a conveying roller unit according to a first embodiment; [Diagram 3] FIG. 1 is a perspective view showing a bearing according to a first embodiment; [Figure 4] FIG. 1 is a perspective view showing a frame according to a first embodiment; [Diagram 5] FIG. 3 is a schematic view of the bearing according to the first embodiment, viewed from the direction A in FIG. [Figure 6] FIG. 3 is a cross-sectional view of the bearing according to the first embodiment, taken along the direction in which the drive roller shaft extends. [Figure 7] FIG. 1 shows a bearing according to a second embodiment. [Figure 8] FIG. 11 is a diagram showing a bearing according to a third embodiment. [Figure 9] FIG. 13 is a diagram showing a bearing according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0012] A sheet conveying device according to a first embodiment will be described with reference to FIGS.

[0013] 1 is a cross-sectional view showing an image forming apparatus 100 having a sheet conveying device according to the embodiment 1. The image forming apparatus 100 forms an image on a sheet S by an electrophotographic method. FIG.

[0014] The image forming apparatus 100 includes a sheet feed cassette 104 as a sheet storage means. The sheet feed cassette 104 is configured to be detachable from an apparatus body 101 of the image forming apparatus 100. In response to a print start signal, the sheets S stacked in the sheet feed cassette 104 are conveyed one by one toward the downstream side of the image forming apparatus 100 in the sheet conveying direction.

[0015] In the image forming apparatus 100, a portion having a function related to the conveyance of the sheet S can be called a sheet conveying device. The sheet conveying device in the first embodiment includes a conveying roller unit 102. The conveying roller unit 102 includes a driving roller 200a as a first roller and a driven roller 201a as a second roller. The driving roller 200a is held by a driving roller shaft (first roller shaft, roller shaft) 200b, and the driven roller 201a is held by a driven roller shaft 201b (second roller shaft). The driving roller 200a and the driving roller shaft 200b are parts of the driving roller unit 200, and the driven roller 201a and the driven roller shaft 201b are parts of the driven roller unit 201.

[0016] 2, a spring receiving portion 300 is attached to the end of the driven roller shaft 201b, and a spring 301 serving as a biasing member is stretched across the spring receiving portion 300. In a direction intersecting (preferably perpendicular to) the rotational axis direction of the drive roller shaft 200b, the spring 301 biases the driven roller 201a toward the drive roller 200a via the spring receiving portion 300 and the driven roller shaft 201b. When viewed in the rotational axis direction of the drive roller shaft 200b, the direction in which the spring 301 biases the driven roller 201a is referred to as a first direction.

[0017] The driven roller 201a is biased toward the driving roller 200a by a spring 301, and comes into contact with the driving roller 200a to form a nip between the driving roller 200a and the driving roller 200a. The rotational axis direction of the driving roller shaft 200b is parallel to the rotational axis direction of the driven roller shaft 201b.

[0018] The driving roller 200a is driven to rotate by a driving force transmitted from a driving source (not shown). When a sheet S is supplied from the paper feed cassette 104, the sheet S is sandwiched between the driving roller 200a and the driven roller 201a, and is conveyed toward a nip portion (image forming portion) between a transfer roller 106 and a photosensitive drum 103a (described later) by the driving roller 200a being driven to rotate.

[0019] More specifically, the drive roller 200a and the driven roller shaft 201a are located upstream of the image forming unit in the transport path of the sheet S, and form a registration roller pair that corrects skew of the sheet S. The image forming apparatus 100 includes a process cartridge 103 that is detachable from the image forming apparatus 100. The process cartridge 103 includes a photosensitive drum 103a as an image carrier, a charging roller 103b as a charging means, a developing roller 103c as a toner image developing means, and the like.

[0020] The transfer roller 106 is biased toward the photosensitive drum 103a and rotates in response to the rotation of the photosensitive drum 103a. The photosensitive drum 103a on which the toner image is developed and the transfer roller 106 hold the sheet S conveyed from the paper feed cassette 104 between them, and transfer the toner image onto the sheet S.

[0021] The sheet S onto which the toner image has been transferred is transported to a fixing unit 108. The fixing unit 108 heats and presses the sheet S to fix the transferred toner image onto the sheet S. The sheet S onto which the toner image has been fixed passes through a sheet transport path 109 and is discharged by a pair of discharge rollers 111 provided at a sheet discharge port 110. The discharged sheet S is stacked on a discharge tray 112 serving as a sheet stacking means.

[0022] The driving roller shaft 200b is held at both ends by deformable bearings 500. The bearing 500 and its mounting configuration in the first embodiment will be described with reference to Figs. 3 to 6. Fig. 3 is a perspective view showing the bearing 500. Figs. 3(a) and 3(b) show the bearing 500 from different angles. In the first embodiment, the bearing 500 is made of a slidable resin material, but is not limited to this.

[0023] The cylindrical portion (receiving portion) 500a is a part of the bearing 500, and is a portion that holds the driving roller shaft 200b, and is capable of elastic deformation. The material of the bearing 500 is preferably resin. The bearing 500 has an arm 500e formed so as to extend from the cylindrical portion 500a, and a slit 500b is formed in the arm 500e. The slit 500b engages with a frame 600, which will be described later, thereby holding the bearing 500 in the frame 600. The slit 500b is located approximately in the center of the cylindrical portion 500a in the direction of the rotation axis of the driving roller shaft 200b. The center position of the cylindrical portion 500a in the direction of the rotation axis of the driving roller shaft 200b overlaps with the position of the slit 500b.

[0024] The bearing 500 has a first surface 500b1 that forms the slit 500b, a second surface 500b2 that faces the first surface 500b1, and a third surface 500b3 that extends in a direction intersecting (preferably perpendicular) to the first direction. The third surface 500b3 contacts the frame 600 so that the bearing 500 is positioned in the frame 600 in the first direction. When the bearing 500 is positioned in the frame 600, the first surface 500b1 and the second surface 500b2 face each other so as to sandwich the frame 600 therebetween.

[0025] The first surface 500b1 restricts the bearing 500 from being displaced relative to the frame 600 in the direction from the drive roller 200a toward the frame 600 in the rotational axis direction of the drive roller shaft 200b. The second surface 500b2 restricts the bearing 500 from being displaced relative to the frame 600 in the direction from the frame 600 toward the drive roller 200a in the rotational axis direction of the drive roller shaft 200b.

[0026] The first surface 500b1 and the second surface 500b2 are disposed downstream of the third surface 500b3 in the first direction. A hole 500c is provided at the center of the cylindrical portion 500a, and the driving roller shaft 200b is inserted into the hole 500c. As a result, the bearing 500 supports the driving roller shaft 200b.

[0027] Fig. 4 is a perspective view showing a frame 600 that holds a bearing 500. Fig. 4(a) shows the frame 600, and Fig. 4(b) shows the frame 600 and the bearing 500 held by the frame 600. The engagement portion 600a is configured to engage with a slit 500b of the bearing 500 for positioning. Specifically, the engagement portion 600a is engaged between a first surface 500b1 and a second surface 500b2 of the bearing 500 so as to sandwich the engagement portion 600a. The space portion 600b is a space that is intentionally provided when the frame 600 and the bearing 500 are engaged, and its effect will be described later.

[0028] Next, a configuration for increasing the contact area between the drive roller shaft 200b and the bearing 500 in the longitudinal direction of the drive roller shaft 200b will be described with reference to Fig. 5. Fig. 5 is a schematic diagram of the vicinity of the bearing 500 as viewed in the direction A in Fig. 2 (a direction perpendicular to the rotational axis direction of the drive roller shaft 200b), with Fig. 5(a) showing an arrow view and a cross-sectional view when the bearing 500 is not tilted, and Fig. 5(b) showing an arrow view and a cross-sectional view when the bearing 500 is tilted.

[0029] The driving roller shaft 200b receives a force from the spring 301 from the driven roller 201a. This causes the driving roller shaft 200b to curve. When the driving roller shaft 200b curves, the contact area between the inside of the hole 500c and the driving roller shaft 200b becomes smaller in the longitudinal direction of the driving roller shaft 200b, and the contact portion of the hole 500c with the driving roller shaft 200b becomes more susceptible to wear. In this situation, in the first embodiment, the bearing 500 is configured to tilt in accordance with the curvature of the driving roller shaft 200b. The configuration in which the bearing 500 tilts is described below.

[0030] The relationship between the first surface 500b1 and the second surface 500b2 and the engagement portion 600a will be described in more detail. In the first embodiment, when one of the first surface 500b1 and the second surface 500b2 is in contact with the frame 600, a gap is generated between the other of the first surface 500b1 and the second surface 500b2 and the frame 600. In other words, the gap of the slit 500b (the distance between the first surface 500b1 and the second surface 500b2) is larger than the thickness of the frame 600. This allows the bearing 500 to tilt as shown in Figures 5(a) and 5(b) while being engaged and held by the frame 600.

[0031] Specifically, if the bearing 500 is configured to be able to tilt from 1° to 15° with respect to the frame 600, the contact area between the drive roller shaft 200b and the bearing 500 increases, making it easier to obtain the effect. In addition, in the first embodiment, the slit 500b is provided only on one side with respect to the biasing direction of the spring 301 so that the bearing 500 can easily tilt. More specifically, the third surface 500b3 that positions the bearing 500 on the frame 600 is provided so as to face the downstream side with respect to the first direction.

[0032] On the upstream side of the third surface 500b3 in the first direction, displacement of the bearing 500 relative to the frame 600 in the direction of the rotation axis of the drive roller shaft 200b is not restricted. Therefore, as shown in Fig. 5(b), when the driven roller 201a is biased by the spring 301 and the drive roller shaft 200b is bent, on the upstream side of the third surface 500b3 in the first direction, a part of the bearing 500 is allowed to displace relative to the frame 600 in the direction from the frame 600 toward the drive roller 200a.

[0033] When the bearing 500 tilts when the drive roller shaft 200b is curved in this way, the contact area between the drive roller shaft 200b and the bearing 500 increases compared to when the bearing 500 is not tilted relative to the longitudinal direction of the drive roller shaft 200b, making the bearing 500 less susceptible to wear and temperature rise.

[0034] Next, a configuration for increasing the contact area between the drive roller shaft 200b and the bearing 500 in the circumferential direction of the drive roller shaft 200b will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view of the vicinity of the bearing 500 as seen in the direction of the rotation axis of the drive roller shaft 200b, with Fig. 6(a) showing the bearing 500 in an undeformed state and Fig. 6(b) showing the bearing 500 in a deformed state.

[0035] The diameter of the drive roller shaft 200b is smaller than the diameter of the hole 500c of the bearing 500, and a gap is formed between the drive roller shaft 200b and the hole 500c. This is because the drive roller shaft 200b is intentionally made with some margin so that the drive roller shaft 200b does not become unable to pass through the hole 500c due to tolerances, etc. However, this difference in diameter reduces the contact area between the drive roller shaft 200b and the hole 500c in the circumferential direction of the drive roller shaft 200b, and it is considered that the bearing 500 will wear out at the sliding part. In this embodiment, the bearing 500 is configured to deform and the contact area with the drive roller shaft 200b becomes large. The configuration in which the bearing 500 deforms will be described below.

[0036] As described above, the frame 600 is provided with the space 600b. This space is provided to make it easier for the bearing 500 to deform. The hole 500c has a larger diameter than the driving roller shaft 200b, and the contact area between the cylindrical portion 500a and the driving roller shaft 200b is reduced due to the gap (FIG. 6(a)). When the cylindrical portion 500a is pressed against the driven roller shaft 201b, the cylindrical portion 500a elastically deforms toward the space 600b. As the cylindrical portion 500a deforms toward the space 600b, the contact surface of the cylindrical portion 500a with the driving roller shaft 200b conforms to the circumferential surface of the driving roller shaft 200b. As a result, the contact area of ​​the cylindrical portion 500a with the driving roller shaft 200b increases compared to when the driving roller shaft 200b is not deformed (FIG. 6(b)).

[0037] The space 600b will be further described. As described above, when viewed in the direction of the rotation axis of the drive roller shaft 200b, the direction in which the spring 301 urges the driven roller 201a is the first direction. The direction perpendicular to the first direction is the second direction, and the region in which the drive roller shaft 200b exists in the second direction is the first region 10. The space 600b is provided so that the frame 600 and the bearing 500 do not come into contact with each other in the first region 10 downstream of the center of rotation of the drive roller shaft 200b in the urging direction when the urging force of the spring 301 is applied from the drive roller shaft 200b to the bearing 500.

[0038] That is, the space 600b is provided so that the bearing 500 and the frame 600 do not come into contact with each other in the first region 10 when the hole 500c deforms to fit along the drive roller shaft 200b. In other words, the space 600b is provided so that the cylindrical portion 500a of the bearing 500 and the frame 600 do not come into contact with each other in the first region 10 when the hole 500c deforms to fit along the drive roller shaft 200b. By deforming the cylindrical portion 500a in this way, the reduction in the contact area between the drive roller shaft 200b and the bearing 500 in the circumferential direction of the drive roller shaft 200b is suppressed, and the bearing 500 becomes less likely to wear out. Also, the temperature does not easily rise.

[0039] Here are specific values ​​for this configuration. It is effective to appropriately select the thickness and width of the cylindrical portion 500a according to the shaft diameter of the driving roller shaft 200b and the contact force acting on the bearing 500. For example, in the shape shown in Fig. 6, if the bearing material is POM (polyacetal), the shaft diameter is φ6, and the contact force against the bearing 500 is 2 kgf, a good contact pressure reduction effect can be obtained by setting the thickness of the cylindrical portion 500a to 1.2 mm and the width (length in the direction of the rotation axis of the driving roller shaft 200b) to about 10 mm.

[0040] In this embodiment, the force acting on the bearing 500 is 1.5 kgf to 2.5 kgf, and the cylindrical portion 500a has a thickness of 1.1 to 1.3 mm and a width of 9 to 11 mm.

[0041] In this embodiment, the drive roller shaft 200b is biased by the spring 301, but if the drive roller shaft 200b is stretched by a belt or in some other configuration where a contact force is generated, a sliding bearing that is resistant to wear and temperature rise can be realized. Also, the present invention can be applied to any configuration of a pair of rollers that transports a sheet.

[0042] As described above, when the drive roller shaft 200b is bent, it is possible to prevent the contact area between the drive roller shaft 200b and the cylindrical portion 500a from decreasing. EXAMPLES

[0043] In the second embodiment, Fig. 7 shows an example of a bearing having a different shape that can obtain the same effect as in the first embodiment. The same reference numerals are used to designate parts that are the same as those in the first embodiment, and the description thereof will be omitted. Fig. 7 shows a bearing 2500 according to the second embodiment. Fig. 7(a) is a cross-sectional view seen in the direction of the rotation axis of the drive roller shaft 200b, and Fig. 7(b) is a side view.

[0044] In Example 2, a bearing 2500 corresponding to the bearing 500 in Example 1 is used. The bearing 2500 has a cylindrical portion 2500a, a slit 2500b, and a hole 2500c corresponding to the cylindrical portion 500a, the slit 500b, and the hole 500c in Example 1. In this shape, the slit 2500b is disposed directly below the region of the cylindrical portion 2500a in the biasing direction.

[0045] The bearing 2500 in this embodiment has a bottom portion 2500d located on the downstream side of the cylindrical portion 2500a in the first direction and in the first region 10. The bottom portion 2500d abuts against the frame 600 in the first region 10.

[0046] The bearing 2500 includes a hole 2500f disposed between the cylindrical portion 2500a and the bottom portion 2500d. As in the first embodiment, the slit 2500b is disposed near the center of the cylindrical portion 2500a in the direction of the rotation axis of the drive roller shaft 200b. The center position of the cylindrical portion 2500a and the position of the slit 2500b overlap with respect to the direction of the rotation axis of the drive roller shaft 200b. The position of the hole 2500f and the position of the slit 2500b overlap with respect to the direction of the rotation axis of the drive roller shaft 200b. As in the first embodiment, the bearing 2500 can be tilted with respect to the frame 600 as shown in FIG. 5(b).

[0047] Furthermore, when a biasing force is applied from the driving roller shaft 200b to the cylindrical portion 2500a, the cylindrical portion 2500a is deformed toward the hole 2500f. At this time, since the hole 2500f is formed, the cylindrical portion 2500a and the bottom portion 2500d are not in contact with each other in the first direction. Therefore, the cylindrical portion 2500a is easily deformed.

[0048] With the above configuration, in the second embodiment, it is possible to suppress a decrease in the contact area between the driving roller shaft 200b and the cylindrical portion 2500a when the driving roller shaft 200b is bent, similar to the configuration in the first embodiment. By adopting the shape shown in the second embodiment, it is possible to obtain the same effect as the first embodiment, even under conditions where the space on both sides of the bearing is greatly restricted. EXAMPLES

[0049] In the third embodiment, Fig. 8 shows an example of a bearing with a different shape that can obtain the same effect as in the first embodiment. The same reference numerals are used for parts that are the same as those in the first embodiment, and the description thereof will be omitted. Fig. 8 shows a bearing 3500 according to the third embodiment. Fig. 8(a) is a cross-sectional view seen in the direction of the rotation axis of the drive roller shaft 200b, and Fig. 8(b) is a side view.

[0050] In the third embodiment, a bearing 3500 corresponding to the bearing 500 in the first embodiment is used. The bearing 2500 has a receiving portion 3500a, a slit 3500b, and a hole 3500c corresponding to the cylindrical portion 500a, the slit 500b, and the hole 500c in the first embodiment.

[0051] In this shape example, the receiving portion 3500a is configured to have a thin U-shape. Accordingly, the slit 3500b is disposed upstream of the biasing direction (first direction) with respect to the center of the inner diameter of the bearing 3500. The slit 3500b is disposed near the center of the receiving portion 3500a in the rotational axis direction of the drive roller shaft 200b. The center position of the receiving portion 3500a and the position of the slit 3500b overlap with respect to the rotational axis direction of the drive roller shaft 200b.

[0052] When a contact force acts from the drive roller shaft 200b to the receiving portion 3500a of the bearing 3500, the entire thin U-shape elastically deforms, and at the same time, the receiving portion 3500a elastically deforms toward the space portion 600b. As a result, a reduction in the contact area of ​​the receiving portion 3500a with the drive roller shaft 200b is suppressed. The effect of the entire U-shape elastically deforming can be obtained even under conditions of a smaller contact force, compared to the shape examples of the first and second embodiments. EXAMPLES

[0053] In the fourth embodiment, an example of a bearing having a different shape that can obtain the same effect as in the first embodiment is shown using Fig. 9. Note that the same reference numerals are used to designate parts that are the same as those in the first embodiment, and the description thereof will be omitted. Fig. 9 is a diagram showing a bearing 4500 according to the fourth embodiment. Fig. 9(a) is a cross-sectional view seen in the direction of the rotation axis of the drive roller shaft 200b, and Fig. 9(b) is a side view.

[0054] In the fourth embodiment, a bearing 4500 corresponding to the bearing 500 in the first embodiment is used. The bearing 4500 has a receiving portion 4500a and a slit 4500b corresponding to the cylindrical portion 500a, the slit 500b, and the hole 500c of the first embodiment.

[0055] In this shape example, a notch 4500d is provided on the upstream side of receiving portion 4500a in the first direction, and holding portion 4500b is disposed downstream in the first direction with respect to the center of the inner diameter of bearing 4500. Also, slit 4500b is disposed near the center of bearing 4500 in the rotational axis direction of drive roller shaft 200b. The center position of receiving portion 4500a in the rotational axis direction of drive roller shaft 200b overlaps with the position of slit 4500b.

[0056] When a contact force is applied from the drive roller shaft 200b to the receiving portion 4500a, the receiving portion 4500a is deformed so that the width of the notch 4500d becomes narrower. By adopting the configuration as shown in Fig. 9, it is possible to obtain the same effect as in Example 1 even under conditions where the contact force is smaller than those in the shapes of Examples 1 to 3.

[0057] In this way, appropriate effects can be obtained by selecting the bearing shape according to design constraints and device specifications. [Explanation of symbols]

[0058] 100 Image forming device 102 Conveyor roller section 103 Process cartridge 104 Paper feed cassette 106 Transfer roller 109 Sheet transport path 110 Sheet outlet 111 Paper ejection roller 112 Output tray 200a Drive roller 201a Driven roller 301 Spring 500 Bearings 500a sliding part 500b Support part 500d cutout 600 frames

Claims

1. A sheet conveying device, The frame and a first roller for conveying a sheet; a roller shaft that holds the first roller; a second roller that faces the first roller and pinches the sheet together with the first roller; a biasing member that biases the second roller toward the first roller in a direction intersecting with the rotational axis direction of the roller shaft; a bearing having a holding portion that slidably holds the roller shaft and is held by the frame, the holding portion being deformable; and When viewed in the rotation axis direction of the roller shaft, a direction in which the biasing member biases the second roller is defined as a first direction, a direction perpendicular to the first direction is defined as a second direction, and a region in which the roller shaft exists in the second direction is defined as a first region, the frame holds the bearing so that the frame and the holding portion do not come into contact with each other in the first region downstream of the rotation center of the roller shaft in the first direction. A sheet conveying device characterized by:

2. 2. The sheet transport device according to claim 1, wherein the bearing has an arm formed with a slit that engages with the frame, the slit extending in the first direction.

3. 3. The sheet conveying device according to claim 2, wherein the bearing has a first surface and a second surface that form the frame, the first surface and the second surface facing each other across the frame, and the first surface and the second surface are arranged so that when one of the first surface and the second surface is in contact with the frame, a gap is created between the other of the first surface and the second surface and the frame.

4. 4. The sheet transport device according to claim 3, wherein the bearing has a third surface that forms the slit, and the third surface abuts against the frame so that the bearing is positioned relative to the frame in the first direction.

5. The sheet conveying device according to claim 4, wherein the holding portion is allowed to displace relative to the frame in a direction from the frame toward the first roller, upstream of the third surface in the first direction.

6. The sheet conveying device according to any one of claims 1 to 5, characterized in that the first roller and the second roller are located upstream of an image forming unit that forms an image on the sheet in the sheet conveying path, and form a registration roller pair that corrects skew of the sheet.

7. A sheet conveying device, The frame and a first roller for conveying a sheet; a roller shaft that holds the first roller; a second roller that faces the first roller and pinches the sheet together with the first roller; a biasing member that biases the second roller toward the first roller; a bearing having a holding portion that slidably holds the roller shaft and a bottom portion that abuts against the frame, the bearing being held by the frame, the holding portion being deformable; and When viewed in the rotational axis direction of the roller shaft, a direction in which the biasing member biases the second roller is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction. When a region in which the roller shaft exists in the second direction is defined as a first region, the bottom portion is located downstream of the receiving portion in the first direction and in the first region, The bearing includes a hole disposed between the retaining portion and the bottom portion such that the retaining portion and the bottom portion do not come into contact with each other in the first region. A sheet conveying device characterized by:

8. 8. The sheet transport device according to claim 7, wherein the bearing has an arm formed with a slit that engages with the frame, the slit extending in the first direction.

9. The sheet conveying device of claim 8, wherein the bearing has a first surface and a second surface that form the slit, the first surface and the second surface are opposed to each other across the frame, and are arranged so that when one of the first surface and the second surface is in contact with the frame, a gap is created between the other of the first surface and the second surface and the frame.

10. 10. The sheet transport device according to claim 9, wherein the bearing has a third surface that forms the slit, and the third surface abuts against the frame so that the bearing is positioned relative to the frame in the first direction.

11. The sheet conveying device according to claim 10, wherein the holding portion is allowed to be displaced relative to the frame in a direction from the frame toward the first roller, on the upstream side of the third surface in the first direction.

12. The sheet conveying device according to any one of claims 7 to 11, characterized in that the first roller and the second roller are located upstream of an image forming unit that forms an image on the sheet in the sheet conveying path, and form a registration roller pair that corrects skew of the sheet.

Images