Sheet conveying device and image forming apparatus

Abstract

To prevent conveyance failure caused by a reinforcing member.SOLUTION: A sheet conveying device includes a conveyance roller that conveys a sheet, a bearing that pivotally supports the conveyance roller, a housing that holds the conveyance roller, and a reinforcing member that reinforces strength of the housing and holds the bearing, wherein the bearing includes a guide portion that guides the sheet in a conveyance direction, and the guide portion is provided to protrude from the reinforcing member in a direction orthogonal to an axial direction of the conveyance roller.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device that conveys a sheet and an image forming apparatus including the same. [Background technology]

[0002] Conventionally, image forming devices such as copiers and facsimiles are equipped with a sheet conveying device that conveys sheets to be recorded, such as recording paper. Examples of the sheet conveying device include a sheet feeding device that feeds sheets stored in a storage section inside the device one by one to an image forming section at an appropriate timing. A known configuration of such a sheet conveying device is one in which a separation nip is formed by a feed roller and a retard roller, sheets are separated one by one at the separation nip, the separated sheets are pulled out by a conveying roller, and the separated sheets are sent further downstream (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-168503 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional configuration described above, a large pulling force is required when the conveying roller pulls the sheet out of the separation nip. The conveying roller has an end of its shaft supported by a housing. Therefore, when the conveying roller pulls out and conveys the sheet, the housing supporting the conveying roller cannot maintain its rigidity, which may cause vibration noise when the conveying roller pulls out and conveys the sheet.

[0005] Therefore, it was considered to provide a reinforcing metal plate to maintain the rigidity of the housing and use this reinforcing metal plate to hold the shaft end of the conveying roller, but there was a risk that the edge of the sheet would come into contact with the reinforcing metal plate holding the shaft end of the conveying roller, causing conveying problems.

[0006] An object of the present invention is to prevent sheet transport failure caused by a reinforcing member. [Means for solving the problem]

[0007] A typical configuration of the present invention comprises a conveying roller for conveying a sheet, a bearing for supporting the conveying roller, a housing for holding the conveying roller, and a reinforcing member for reinforcing the strength of the housing and holding the bearing, wherein the bearing has a guide portion for guiding the sheet in the conveying direction, and the guide portion is arranged to protrude beyond the reinforcing member in a direction perpendicular to the axial direction of the conveying roller. [Effects of the Invention]

[0008] According to the present invention, the edge of the sheet contacts the guide portion of the bearing and is guided in the conveying direction, so that poor sheet conveyance caused by the reinforcing member can be prevented. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus; [Figure 2] Perspective view of a feeding unit [Figure 3] Cross-sectional view of the feeding unit [Figure 4] (a) is a perspective view showing a support structure for a conveying roller, (b) is an enlarged view of a main part showing the support structure for a conveying roller, and (c) is a side view showing the support structure for a conveying roller. [Figure 5] Perspective view of bearing [Figure 6] FIG. 1 is a schematic cross-sectional view illustrating a configuration of a sheet feeding device. [Figure 7] Top view of the sheet feeding device [Figure 8] Top view of the sheet feeding device [Figure 9] Top view of the sheet feeding device [Figure 10] Cross-sectional side view of the sheet feeding device DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in the following embodiments may be changed as appropriate depending on the configuration of the device to which the present invention is applied and various conditions, and are not intended to limit the scope of the present invention to those alone.

[0011] First, a schematic configuration of an image forming apparatus including a sheet feeding device according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view showing a schematic configuration of the image forming apparatus according to this embodiment.

[0012] As shown in Fig. 1, the image forming apparatus 201 has an image forming unit 201B that forms an image on a sheet inside an image forming apparatus main body 201A. The image forming apparatus 201 is equipped with a document reading device 202. The document reading device 202 is installed approximately horizontally above the image forming apparatus main body 201A. A discharge space S for discharging sheets is formed between the document reading device 202 and the image forming apparatus main body 201A.

[0013] The image forming apparatus 201 is equipped with a plurality of sheet feeding devices 230 as sheet conveying devices that convey sheets. Each sheet feeding device 230 feeds a sheet P from a feeding cassette 1 that is a sheet storage unit. Each sheet feeding device 230 is equipped with a feeding unit 500 shown in FIGS. 2 and 3. The feeding unit 500 has a pickup roller 8 that is a feeding section, a separation section consisting of a feed roller 9 and a retard roller 10 that separates the sheet P fed by the pickup roller 8, and a pair of conveying rollers 31 and 32 that convey the separated sheet P.

[0014] Image forming unit 201B is a four-drum full-color system. Image forming unit 201B includes a laser scanner 210 and four process cartridges 211 that form toner images in four colors: yellow (Y), magenta (M), cyan (C), and black (K). Each process cartridge 211 includes a photosensitive drum 212 that serves as a photosensitive member, a charger 213 that serves as a charging unit, and a developing unit 214 that serves as a developing unit. Image forming unit 201B also includes an intermediate transfer unit 201C and a fixing unit 201E that are disposed above the process cartridges 211. A toner cartridge 215 that supplies toner to the developing unit 214 is disposed above the intermediate transfer unit 201C.

[0015] The intermediate transfer unit 201C includes an intermediate transfer belt 216 wound around a drive roller 216a and a tension roller 216b. A primary transfer roller 219 is provided inside the intermediate transfer belt 216 and contacts the intermediate transfer belt 216 at a position facing the photosensitive drum 212. The intermediate transfer belt 216 is rotated in the direction of the arrow by a drive roller 216a driven by a drive unit (not shown).

[0016] Then, the toner images of each color on the photosensitive drum are sequentially superimposed and transferred onto intermediate transfer belt 216 by primary transfer roller 219. A secondary transfer roller 217 that transfers the color image formed on the intermediate transfer belt onto sheet P is provided at a position facing drive roller 216a of intermediate transfer unit 201C. Furthermore, a fixing section 201E is disposed above secondary transfer roller 217, and a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversing section 201D are disposed above and to the left of fixing section 201E. This double-sided reversing section 201D is provided with a reversing roller pair 222 that can rotate forward and backward, a re-conveyance path R that conveys the sheet with an image formed on one side again to image forming section 201B, and the like.

[0017] The image forming apparatus 201 includes a control unit 250 that controls the image forming operation, the sheet feeding operation, and the like.

[0018] Next, the image forming operation of the image forming apparatus 201 will be described. First, image information of an original is read by the original reading device 110, and after image processing, this image information is converted into an electrical signal and transmitted to the laser scanner 210 of the image forming unit 201B. In the image forming unit 201B, the surface of the photosensitive drum 212, the surface of which is uniformly charged to a predetermined polarity and potential by the charger 213, is sequentially exposed to laser light. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drum of each process cartridge 211, respectively.

[0019] Thereafter, the electrostatic latent images are developed and visualized with toner of each color, and the toner images of each color on each photosensitive drum are transferred in order onto the intermediate transfer belt 216, superimposed on one another, by a primary transfer bias applied to the primary transfer roller 219. As a result, a toner image is formed on the intermediate transfer belt 216.

[0020] In parallel with this toner image forming operation, a sheet P is sent out by a pickup roller 8 provided in the sheet feeding device 230. The sent out sheets P are separated one by one by a separation unit consisting of a feed roller 9 and a retard roller 10 and conveyed to a pair of registration rollers 240, where skew is corrected.

[0021] After the skew is corrected, the sheet P is transported to a secondary transfer section by a pair of registration rollers 240, where the toner images are transferred all at once onto the sheet P by a secondary transfer bias applied to a secondary transfer roller 217. Next, the sheet P onto which the toner images have been transferred is transported to a fixing section 201E, where the toners of the various colors are melted and mixed by heat and pressure, and are fixed onto the sheet P as a color image.

[0022] Thereafter, the sheet P on which the image has been fixed is discharged into the discharge space S by a first discharge roller pair 225a and a second discharge roller pair 225b provided downstream of the fixing unit 201E, and is stacked on a stacking unit 223 protruding from the bottom surface of the discharge space S. When an image is formed on both sides of the sheet P, after the image is fixed on one side, the sheet P is transported to a re-conveyance path R by a reversing roller pair 222, and is transported again to the image forming unit 201B.

[0023] (sheet feeding device) Next, the configuration of the sheet feeding device 230 according to this embodiment will be described with reference to Figures 2, 3, and 6. Figure 2 is a perspective view of a feeding unit 500 in the sheet feeding device 230. Figure 3 is a cross-sectional view of the feeding unit 500 in the sheet feeding device 230. Figure 6 is a schematic cross-sectional view showing the configuration of the sheet feeding device 230.

[0024] As described above, the sheet feeding device 230 feeds sheets P from the feeding cassette 1, which is a sheet storage unit. The sheet feeding device 230 includes a feeding unit 500 shown in FIGS. 2 and 3. The feeding unit 500 includes a pickup roller 8, which is a feeding unit that feeds the sheets P stored in the feeding cassette 1, a separation unit consisting of a feed roller 9 and a retard roller 10 that separate the sheets P fed by the pickup roller 8, and a pair of conveying rollers 31 and 32 that convey the separated sheets P. The pair of conveying rollers includes a conveying roller 31 and a conveying roller 32, and is located downstream of the separation unit. The sheet feeding device 230 also includes a conveying guide 38 that guides the sheets. The conveying guide 38 is provided between the separation unit and the pair of conveying rollers 31 and 32, and guides the sheets P separated in the separation unit to the pair of conveying rollers 31 and 32.

[0025] The retard roller 10 is pressed against the feed roller 9 by a pressing member such as a spring, and forms a nip portion (separation nip) N1 in contact with the feed roller 9. The conveying roller 32 is pressed against the conveying roller 31 by a pressing member such as a spring, and forms a nip portion N2 in contact with the conveying roller 31.

[0026] Next, the sheet conveying operation of the sheet feeding device 230 will be described with reference to FIG.

[0027] The sheets P stored in the feeding cassette 1 are fed to a separation section by the pickup roller 8. A torque limiter (not shown) is provided coaxially with the retard roller 10. When only one sheet P is fed by the pickup roller 8, a load equal to or greater than a predetermined value acts on the torque limiter, causing the torque limiter to rotate freely and the retard roller 10 to rotate along with the feed roller 9. When two or more sheets P are fed by the pickup roller 8, a load less than the predetermined value acts on the torque limiter, causing the retard roller 10 to stop without rotating along with the feed roller 9. As a result, the sheets P are separated one by one at a nip portion (separation nip) N1 between the feed roller 9 and the retard roller 10, and are fed to the conveying roller pair 31, 32.

[0028] (Configuration of conveyor roller) Next, the configuration of the conveying roller 31 will be described with reference to Figures 2 and 7. Figure 7 is a top view of the sheet feeding device 230.

[0029] The sheet feeding device 230 includes bearings 34 and 52 that rotatably support the conveying roller shaft 33 of the conveying roller 31, a feeding frame 50 that serves as a housing that holds the conveying roller 31, and a reinforcing member 53 that reinforces the strength of the feeding frame 50 and holds the bearing 52.

[0030] The reinforcing member 53 is a plate-like member made of metal, and in this case is a metal plate. The reinforcing member 53 has a holding metal plate 51 which is a holding portion that holds a bearing 52 that supports the conveying roller shaft 33 of the conveying roller 31. The holding metal plate 51 is provided to protrude in a direction perpendicular to the axial direction of the conveying roller 31, and holds the bearing 52.

[0031] The conveying roller 31 has a conveying gear 39 attached to the end of the conveying roller shaft 33. The conveying roller 31 operates when rotational power output from a motor (not shown) is transmitted via the conveying gear 39 and the conveying roller shaft 33, and conveys the sheet P downstream. The conveying roller 31 has both ends of the conveying roller shaft 33 supported by bearings 34 and 52. That is, one end of the conveying roller shaft 33 of the conveying roller 31 is supported by the bearing 34, and the other end is supported by the bearing 52. The bearing 34 that supports one end of the conveying roller 31 is held by the feeding frame 50. The bearing 52 that supports the other end of the conveying roller 31 is held by a holding metal plate 51 of a reinforcing member 53.

[0032] In the sheet feeding device 230, the pickup roller 8, feed roller 9, retard roller 10, and conveying roller 32 are supported by bearings at their shafts, similar to the conveying roller 31, and are held in a feeding frame 50 as a housing.

[0033] Furthermore, the conveying roller 31 is mounted in a state where the bearing 52 is restrained in both the sheet conveying direction and the pressure direction of the pair of conveying rollers 31 and 32 by being held by a holding metal plate 51 extending from a reinforcing member 53. This configuration suppresses vibration of the conveying roller shaft 33 and the feeding unit 500, reducing the generation of abnormal noise. Specifically, during the conveying process of the sheet P, the sheet P is nipped at the nip portion N2 between the conveying roller 31 and the conveying roller 32 and the separation nip portion N1 between the feed roller 9 and the retard roller 10. When the trailing edge of the sheet P passes through the separation nip portion N1, the force acting on the conveying roller is released, causing the entire feeding unit 500 to vibrate. To prevent abnormal noise caused by this vibration, the conveying roller shaft 33 is made of a metal shaft, and the bearing 52 supporting the conveying roller shaft 33 is held by the holding metal plate 51 extending from a reinforcing member 53 that reinforces the feeding unit 500. This makes it possible to suppress vibrations of the conveying roller shaft 33 and the feeding unit 500, thereby reducing the occurrence of abnormal noise.

[0034] (bearings for conveyor rollers) Next, the bearing 52 of the conveying roller 31 will be described with reference to FIGS. 4 and 5. FIG. 4(a) is a perspective view showing the support structure of the conveying roller 31, FIG. 4(b) is an enlarged view of the main part showing the support structure of the conveying roller 31, and FIG. 4(c) is a side view showing the support structure of the conveying roller 31. FIG. 5 is a perspective view of the bearing 52.

[0035] As described above, the end of the conveying roller shaft 33 of the conveying roller 31 is pivotally supported by the bearing 52. The bearing 52 has an engaging portion 52b that is inserted axially and engaged with the holding sheet metal 51 of the reinforcing member 53. The conveying roller shaft 33 of the conveying roller 31 is configured to be pivotally supported by the engaging portion 52b of the bearing 52. Further, the holding sheet metal 51 is caulked to the reinforcing member 53 and is provided to project in a direction orthogonal to the axial direction of the conveying roller 31. Therefore, the conveying roller 31 is held by the holding sheet metal 51 by inserting and engaging the engaging portion 52b of the bearing 52 that pivotally supports the conveying roller shaft 33 axially with respect to the holding sheet metal 51.

[0036] The holding sheet metal 51 included in the reinforcing member 53 is provided within the range of the conveyance area of the sheet P by the conveying roller 31. Therefore, the bearing 52 has a guide portion 52a for guiding the sheet P. The guide portion 52a is provided to project more than the holding sheet metal 51 in a direction orthogonal to the axial direction of the conveying roller 31. Here, the guide portion 52a projects by a predetermined height Z (here, 0.4 mm, and the height Z can be any number as long as 0 < Z) in the direction perpendicular to the conveying direction from the holding sheet metal 51.

[0037] Specifically, the guide portion 52a is provided in a shape along the conveying direction and is provided from the upstream side to the downstream side of the conveying roller shaft 33 in the conveying direction. The portion of the guide portion 52a on the downstream side in the conveying direction from the conveying roller shaft 33 projects more than the holding sheet metal 51. More specifically, the guide portion 52a has a rib 52a1 that projects from the conveying surface 52a2 of the guide portion 52a in a direction orthogonal to the axial direction of the conveying roller 31. The rib 52a1 projects by a predetermined height Z more than the holding sheet metal 51 in a direction orthogonal to the axial direction of the conveying roller 31.

[0038] Next, the guide portion 52a provided on the bearing 52 of the conveying roller 31 will be described with reference to Figures 8 to 10. Figures 8 to 10 are views of the sheet feeding device 230 as seen from above. Here, the case where a sheet P1 having a curled leading end surface on the bearing 52 side of the conveying roller 31 is passed will be described as an example.

[0039] 8, in the sheet feeding device 230, a sheet P1 with a curled leading edge on the bearing 52 side of the conveying roller 31 is waiting in a feeding cassette. The leading edge of the sheet P1 on the bearing 52 side of the conveying roller 31 is curled upward (toward the conveying roller 31) from the portion indicated by the dotted line. The curled portion of the sheet P2 is indicated by curl P1a. The sheet P1 is fed by the pickup roller 8, separated by a separation unit consisting of a feed roller 9 and a retard roller 10, and fed toward the pair of conveying rollers 31 and 32.

[0040] As shown in FIG. 9, sheet P1 is conveyed to the vicinity of nip portion N2 between the pair of conveying rollers 31 and 32. At this time, if guide portion 52a of bearing 52 were not provided, curl P1a of sheet P1 would get caught on a step between the pair of conveying rollers 31 and 32 and the conveying guide 54 on the downstream side before the next sheet P2 reaches the pair of conveying rollers 31 and 32, resulting in a paper feed failure. In contrast, in the sheet feeding device 230 according to this embodiment, bearing 52 of conveying roller 31 has guide portion 52a. Therefore, as shown in FIG. 10, when sheet P1 is conveyed to the vicinity of nip portion N2 between the pair of conveying rollers 31 and 32, curl P1a comes into contact with guide portion 52a of bearing 52, sheet P1 is guided in the conveying direction, and is sent to the downstream conveying guide 54.

[0041] 4(c), the guide portion 52a of the bearing 52 protrudes by a predetermined height Z (here, 0.4 mm) from the holding metal plate 51. As a result, even if a sheet P1 with a curled leading edge is passed through, the curl P1a of the sheet P1 comes into contact with and is guided by the guide portion 52a of the bearing 52. This makes it possible to transport the sheet P1 without the curl P1a of the sheet P1 coming into direct contact with the holding metal plate 51.

[0042] As described above, according to this embodiment, the bearing 52 of the conveying roller 31 has the guide portion 52a that guides the sheet P in the conveying direction, and the guide portion 52a is provided so as to protrude beyond the holding metal plate 51 of the reinforcing member 53. As a result, the end of the sheet P abuts against the guide portion 52a of the bearing 52 and is guided in the conveying direction, thereby preventing poor sheet conveyance caused by the reinforcing member 53.

[0043] In the above-described embodiment, a copier is used as an example of an image forming apparatus. However, the present invention is not limited to this. It may also be other image forming apparatuses, such as a printer or a facsimile machine, or other image forming apparatuses, such as a multifunction peripheral that combines the functions of these. Furthermore, while the image forming apparatus uses an intermediate transfer member, sequentially transfers toner images of different colors onto the intermediate transfer member, and then transfers the toner images carried on the intermediate transfer member to a transfer material all at once, the present invention is not limited to this. It may also be an image forming apparatus using a transfer material carrier, sequentially transfers toner images of different colors onto a transfer material carried on the transfer material carrier, sequentially transferring the toner images of different colors onto the transfer material. Similar effects can be achieved by applying the present invention to a sheet feeding device used in such an image forming apparatus.

[0044] In the above-described embodiment, a sheet feeding device is integrally provided in the image forming apparatus, but the present invention is not limited to this. For example, a sheet feeding device that is detachable from the image forming apparatus may be used, and similar effects can be obtained by applying the present invention to such a sheet feeding device.

[0045] In the above-described embodiment, a sheet feeding device that feeds sheets to be recorded, such as recording paper, to an image forming unit is exemplified, but the present invention is not limited to this. For example, the same effect can be obtained when the present invention is applied to a sheet feeding device that feeds sheets to be read, such as originals, to a reading unit.

[0046] In the above-described embodiment, the sheet feeding device that feeds the sheet to the image forming unit is exemplified as the sheet conveying device that conveys the sheet, but the present invention is not limited to this.

[0047] In the above-described embodiment, the electrophotographic method is used as an example of the recording method, but the present invention is not limited to this, and other recording methods such as an inkjet method may also be used. [Explanation of symbols]

[0048] P, P1, P2 ... Sheet P1a...Carl 1... Feeding cassette 8...Pickup roller 9...Feed roller 10...Retard roller 31...Transport roller 32...Transport roller 33...Transport roller shaft 34,52 ... bearings 38...Transport guide 50...Feed frame 51...Holding plate 52a ... Guide section 52b ... engagement portion 53...Reinforcing member 201 ...Image forming device 201A...Image forming apparatus main body 201B...Image forming section 230 ...Sheet feeding device 500...feeding unit

Claims

1. a conveying roller for conveying a sheet; a bearing that supports the conveying roller; a housing for holding the conveying roller; a reinforcing member that reinforces the strength of the housing and holds the bearing, the bearing has a guide portion that guides the sheet in a conveying direction, The guide portion is provided to protrude beyond the reinforcing member in a direction perpendicular to the axial direction of the conveying roller. A sheet conveying device characterized by:

2. the reinforcing member has a holding portion that protrudes in a direction perpendicular to the axial direction of the conveying roller and holds the bearing, The guide portion is provided to protrude beyond the holding portion in a direction perpendicular to the axial direction of the conveying roller.

2. The sheet transport device according to claim 1.

3. the holding portion is provided within a range of a sheet conveyance area of ​​the conveyance roller; 3. The sheet transport device according to claim 2.

4. the guide portion is provided from the upstream side to the downstream side of the shaft of the conveying roller in the conveying direction.

2. The sheet transport device according to claim 1.

5. the guide portion has a rib protruding from the guide portion in a direction perpendicular to the axial direction of the conveying roller, The rib protrudes beyond the reinforcing member in a direction perpendicular to the axial direction of the conveying roller.

5. The sheet transport device according to claim 4.

6. One end of the conveying roller is held by the housing, and a bearing that supports the other end is held by the reinforcing member.

2. The sheet transport device according to claim 1.

7. a separation unit provided upstream of the conveyance roller in the conveyance direction and including a feed roller and a retard roller for separating the sheets; One end of each of the feed roller and the retard roller is held by the housing.

7. The sheet transport device according to claim 6.

8. The reinforcing member is a metal plate.

2. The sheet transport device according to claim 1.

9. 9. An image forming apparatus comprising an image forming section that forms an image on a sheet and a feeding section that feeds the sheet to the image forming section, wherein the feeding section comprises the sheet conveying device according to claim 1.

Images