Sheet transport device and image forming apparatus

Abstract

The present invention provides a sheet conveying device and an image forming apparatus that can reliably bring the conveying rollers into contact with the frame. [Solution] A sheet conveying device comprising: a conveying roller for conveying a sheet; a conductive bearing that rotatably supports the rotation axis of the conveying roller; a grounded frame that supports the conveying roller; and a bearing holder supported by the frame and holding the bearing, wherein the bearing holder comprises a first member made of a non-conductive resin and a second member made of a conductive resin, and the second member is in contact with the bearing and the frame.

Description

Technical Field

[0001] The present invention relates to a sheet conveying device for conveying a sheet and an image forming device for forming an image on the sheet.

Background Art

[0002] In a sheet conveying device, static electricity is generated due to friction caused by rotation of a conveying roller. Since the generated static electricity causes malfunction of the machine and image defects, it is necessary to ground (earth) the conveying roller in order to remove the static electricity. In Cited Document 1, the conveying roller is grounded by bringing a conductive bearing into contact with a grounded metal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when attaching a conveying roller with a bearing attached to a frame, it may be attached using a bearing holder formed of a non-conductive resin. In such a case, since the conveying roller cannot be grounded, there is a risk of malfunction of the machine and image defects due to static electricity. Therefore, an object of the present invention is to provide a sheet conveying device and an image forming device capable of reliably grounding a conveying roller to a frame.

Means for Solving the Problems

[0005] According to the present invention, a conveying device comprises a conveying roller for conveying a sheet, a conductive bearing that rotatably supports the rotation axis of the conveying roller, a grounded frame that supports the conveying roller, and a bearing holder supported by the frame and holding the bearing, wherein the bearing holder comprises a first member made of a non-conductive resin and a second member made of a conductive resin, and the second member is in contact with the bearing and the frame. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a sheet conveying device and an image forming device that can reliably bring the conveying rollers into contact with the frame. [Brief explanation of the drawing]

[0007] [Figure 1] Cross-sectional view of an image forming system. [Figure 2] Perspective view of the transport unit. [Figure 3] Cross-sectional view of the transport unit. [Figure 4] Perspective view of the conveyor roller configuration. [Figure 5] Schematic diagram of a bearing holder. [Figure 6] Detailed diagram of the bearing holder. [Figure 7] Perspective view of the upper transport unit. [Figure 8] Diagram illustrating the installation of the conveyor roller. [Figure 9] Diagram illustrating the installation of the bearing holder. [Figure 10] Diagram illustrating the installation of the bearing holder. [Modes for carrying out the invention]

[0008] The following description of this embodiment will be illustrated with reference to the figures. While the embodiments described below are preferred embodiments of the present invention and therefore subject to various technically advantageous limitations, the scope of the present invention is not unduly limited by the following description. Furthermore, not all of the configurations described in this embodiment are essential components of the present invention.

[0009] <First Embodiment> <Image forming apparatus> This embodiment describes a case where an image forming system is applied to an inkjet recording system 1. Figure 1 is a schematic diagram showing an example of the general configuration of the inkjet recording system 1. This inkjet recording system 1 is a sheet-fed inkjet recording system that uses two liquids, a reaction solution and ink, to produce a recording material in which an ink image is formed on a sheet.

[0010] The inkjet recording system 1 of this embodiment consists of an image forming apparatus and a plurality of sheet transport devices. Here, a device that is self-supporting and independently housing-like, supported by undercarriage components such as casters or adjusters, will be referred to as a module.

[0011] The inkjet recording system 1 consists of a paper feed module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, a reversing module 6000, and a paper discharge and stacking module 7000. Cut sheets supplied from the paper feed module 1000 are transported along the transport path, processed in each module, and discharged to the paper discharge and stacking module 7000, which acts as a sheet discharge device.

[0012] A paper feeding module 1000, which is an example of a sheet feeding device, has storage compartments 1100a, 1100b, and 1100c for storing sheets. The storage compartments 1100a, 1100b, and 1100c are configured to be pull-out from the front of the device. Sheets are fed one by one from each storage compartment 1100a, 1100b, and 1100c by a separation belt and transport roller (not shown) and transported to the print module 2000. Note that the storage compartments 1100a, 1100b, and 1100c are not limited to three, but may be one, two, or four or more.

[0013] The print module 2000 includes a pre-image registration correction unit (not shown), a print belt unit 2200, and a recording unit 2300. Sheets transported from the paper feed module 1000 are corrected for tilt and position by the pre-image registration correction unit and then transported to the print belt unit 2200. The recording unit 2300 is positioned opposite the print belt unit 2200 across the transport path. The recording unit 2300 is a sheet processing unit that forms an image by performing a recording process (printing) on ​​the transported sheet from above using a recording head. Multiple recording heads are arranged along the transport direction. In this embodiment, in addition to the four colors Y (yellow), M (magenta), C (cyan), and Bk (black), there are a total of five line-type recording heads corresponding to the reaction solution. Note that the number of colors and recording heads are not limited to five.

[0014] The inkjet method can adopt methods such as a method using a heating element, a method using a piezo element, a method using an electrostatic element, a method using a MEMS element, etc. Each color ink is supplied from an ink tank (not shown) to the recording head through an ink tube. The sheet printed by the recording unit 2300 is adsorbed and conveyed by the print belt unit 2200, and is conveyed while ensuring a clearance from the recording head. The sheet printed by the recording unit 2300 is detected for misalignment and color density of the image formed on the sheet by an in-line scanner (not shown) arranged on the downstream side in the conveyance direction of the recording unit 2300. The detection result is used for correcting the printed image. In the present embodiment, the recording unit 2300 is an example of an image forming unit.

[0015] The drying module 3000 has a decoupling unit 3200, a drying belt unit 3300, and a hot air blowing unit 3400. The drying module 3000 reduces the liquid component contained in the ink applied on the sheet by the recording unit 2300 of the print module 2000, and enhances the fixing property between the sheet and the ink. The sheet printed by the recording unit 2300 of the print module 2000 is conveyed to the decoupling unit 3200 arranged inside the drying module 3000. In the decoupling unit 3200, the sheet can be conveyed by the air pressure from above and the friction of the belt, and by weakly holding and conveying the sheet on the belt, the misalignment of the sheet on the print belt unit 2200 forming the ink image is prevented. The drying belt unit 3300 is arranged below the conveyed sheet, and the hot air blowing unit 3400 is arranged above the conveyed sheet, and they are arranged opposite to each other with the belt in between.

[0016] The sheet conveyed from the decoupling unit 3200 is adsorbed and conveyed by the drying belt unit 3300, and at the same time, receives hot air from the hot air blowing unit 3400 to dry the ink application surface. In addition to the method of applying hot air, the drying method may be configured by combining a method of irradiating the sheet surface with electromagnetic waves (such as ultraviolet rays and infrared rays) or a conduction heat transfer method by contact with a heating element.

[0017] The fixing module 4000 has a fixing belt unit 4100. The fixing belt unit 4100 has an upper belt unit and a lower belt unit, and can fix the ink on the sheet by passing the sheet conveyed from the drying module 3000 between the heated upper belt unit and the lower belt unit.

[0018] The cooling module 5000 has a plurality of cooling parts 5001, and cools the high-temperature sheet conveyed from the fixing module 4000. The cooling part 5001 is configured to cool the sheet by taking in outside air into the cooling box with a fan, increasing the pressure in the cooling box, and blowing the air ejected from the nozzles formed in the conveying guide against the sheet. The cooling parts 5001 are arranged on both the upper side and the lower side with respect to the conveying path, and cool the sheet from both sides.

[0019] Also, the cooling module 5000 has a conveying path switching part 5200, and can switch the conveying path of the sheet according to whether the sheet is conveyed to the reversing module 6000 or to the double-sided conveying path used during double-sided printing. During double-sided printing, the sheet is conveyed to the conveying path below the cooling module 5000. In this case, the sheet is further conveyed along the double-sided conveying path of the fixing module 4000, the drying module 3000, the printing module 2000, and the paper feeding module 1000 from the cooling module 5000. Then, it is conveyed to the pre-image registration correction part, the printing belt unit 2200, and the recording part 2300 of the printing module 2000 again, and is printed by the recording part 2300. Incidentally, a first reversing part 4200 for reversing the front and back of the sheet is provided in the double-sided conveying part of the fixing module 4000.

[0020] The reversing module 6000 has a second reversing part 6400, can reverse the front and back of the conveyed sheet, and can freely change the front and back orientation of the discharged sheet.

[0021] The paper discharge stacking module 7000 has a top tray 7200 and a stacking part 7500, and aligns and stacks the sheets conveyed from the reversing module 6000.

[0022] The control unit 10 includes a CPU, RAM, and ROM, and controls each part of the inkjet recording system 1. Based on detection signals input from various sensors and information stored in ROM, the CPU outputs output signals to each electrical component to operate it at the desired timing and with the required control amount. ROM and RAM store information data necessary for controlling each part, and the CPU reads data from the information stored in ROM and writes data to RAM. In this embodiment, the control unit 10 may also control an external computer connected to the inkjet recording system 1.

[0023] <Conveyor Unit Configuration> Figure 2 is a perspective view showing the configuration of the transport unit 100. Figure 3 is a cross-sectional view of the transport unit 100 from the upstream side in the sheet transport direction, perpendicular to the sheet transport direction. As shown in Figure 1, the transport unit 100 is located on the double-sided transport path below the fixing module 4000. However, since the transport rollers 200 are used in various locations for sheet transport within the image forming system, the transport unit 100 will be described as an example.

[0024] The conveying unit 100 includes an upper conveying unit 101 equipped with a plurality of conveying rollers 200 and a lower conveying unit 102 equipped with a plurality of driven rollers 300. The conveying rollers 200 and driven rollers 300 form a conveying roller pair, and the sheet is nipped by the conveying rollers 200 and driven rollers 300 and conveyed.

[0025] The conveying unit 100 is configured so that the sheet conveying path can be opened to allow the user to remove jammed sheets if the conveyed sheets become jammed. The lower conveying unit 102 is fixed to the frame of the main body of the device, and the upper conveying unit 101 is rotatable upward relative to the lower conveying unit 102 around a rotation axis at the rear of the device. In this embodiment, the front side is the side on which the user stands when processing jammed sheets when the conveying unit 100 is mounted on the main body of the device, and the rear side is the side opposite to the side on which the user stands when processing jammed sheets.

[0026] When the upper transport unit 101 is closed, a latch located on the front side locks it in place to prevent it from opening. As a result, as shown in Figure 3, the transport roller 200 and the driven roller 300 come into contact, and the driven roller 300 is pushed in, causing the transport spring 301 located on the driven roller side to compress, generating nip pressure on the transport roller 200. In this embodiment, since the transport roller 200 is located on the upper transport unit 101 and the driven roller 300 is located on the lower transport unit 102, a roller pressure F is applied upward from the driven roller 300 toward the transport roller 200.

[0027] In this embodiment, the transport roller 200 is positioned on the upper side and the driven roller 300 is positioned on the lower side, but this is not limited to this configuration. The driven roller 300 may be positioned on the upper side and the transport roller 200 on the lower side.

[0028] Figure 4 is a perspective view of the conveyor roller 200. The conveyor roller 200 has a roller shaft 201, rollers 202, and conductive bearings 203. Conductive bearings 203 are positioned at both ends of the roller shaft 201, and multiple rollers 202 are positioned between the bearings 203 positioned at both ends of the roller shaft 201. The two conductive bearings 203 are bearings that rotatably support the roller shaft 201. The rollers 202 and conductive bearings 203 are press-fitted onto the roller shaft 201. By press-fitting the conductive bearings 203 onto the roller shaft 201, slippage between the roller shaft 201 and the conductive bearings 203 is eliminated, and wear on the roller shaft that occurs as the durability of the roller shaft 201 increases can be suppressed. In other words, by press-fitting the conductive bearings 203 onto the roller shaft 201, a highly durable product can be realized. Note that in this embodiment, the conductive bearings 203 are an example of bearings.

[0029] <Bearing holder configuration> In sheet conveying devices, static electricity is generated by friction caused by rotation of the conveying rollers. This generated static electricity can cause machine malfunctions and image defects, so it is necessary to ground the conveying rollers to remove the static electricity.

[0030] As shown in Figure 4, when the conductive bearing 203 is press-fitted onto the roller shaft 201 and the integrated transport roller 200 is attached to the frame of the transport unit, it is necessary to restrict the movement of the thrust position of the transport roller 200. For this purpose, the bearing holder is fixed to the frame while holding the conductive bearing 203. If the bearing holder is made only of a general non-conductive resin, the side of the transport roller 200 on which the bearing holder is attached cannot be grounded. Therefore, in this embodiment, the bearing holder 400 is composed of two types of members: a first member 401 made of non-conductive resin and a second member 402 made of conductive resin.

[0031] Figure 5 shows a schematic diagram of the bearing holder 400. Figure 6 shows a detailed view of the bearing holder 400. Specifically, Figure 6(a) shows a cross-sectional view of the bearing holder 400. Figures 6(b) and 6(c) are enlarged views of the bearing holder 400 from different angles. The bearing holder 400 holds the bearing 203 of the conveyor roller 200 and restricts the thrust position of the conveyor roller 200.

[0032] The bearing holder 400 is composed of two parts: a first member 401 molded from a general resin by two-color molding, and a second member 402 molded from a conductive resin. The general resin is a non-conductive resin with high electrical resistance, meaning it does not conduct electricity easily. In other words, the bearing holder 400 is composed of a first member made of a non-conductive resin and a second member made of a conductive resin. In this embodiment, the conductive resin preferably has a resistance of 100 kΩ or less. In this embodiment, the bearing holder 400 is based on the first member 401, with the second member 402 positioned in a portion of it. In other words, the bearing holder 400 is composed of a larger proportion of the first member 401 than of the second member 402. Specifically, the ratio of the surface area of ​​the first member 401 to the surface area of ​​the bearing holder 400 is greater than the ratio of the surface area of ​​the second member 402 to the surface area of ​​the bearing holder 400. This is not limited to this example; the ratio of the volume of the first member 401 to the volume of the bearing holder 400 may be greater than the ratio of the volume of the second member 402 to the volume of the bearing holder 400.

[0033] Generally, conductive resins are more brittle than ordinary resins. Therefore, if the bearing holder 400 is made solely of conductive resin, there is a concern about a decrease in overall durability and the breakage of the snap-fit ​​403, which holds the conductive bearing 203 (described later). Furthermore, if the length of the arms of the snap-fit ​​403 is increased to account for the breakage of the snap-fit ​​403 made of conductive resin, problems arise such as the increased size of the part and a decrease in the holding force that holds the conductive bearing 203. For this reason, it is preferable to use general resin for the elastically deformable snap-fit ​​403. This reduces the breakage of the snap-fit ​​403. In this embodiment, the bearing holder 400 is excellent in durability and conductivity by using a first member 401 molded from general resin and a second member 402 molded from conductive resin.

[0034] The first member 401 has a circular portion 408 that faces the circumferential surface of the conductive bearing 203 when the bearing holder 400 is mounted on the conductive bearing 203. Furthermore, the first member 401 has a flange portion 406 that protrudes radially outward from the conductive bearing 203 and an inner restricting portion 409 that protrudes radially inward from the conductive bearing 203. Furthermore, the first member 401 has a snap-fit ​​403 for holding the conductive bearing 203, a thrust position restricting portion 404 that prevents the bearing holder itself from coming off, a rotation restricting portion 405 that restricts the rotation of the bearing holder 400, and a handle portion 407. The thrust position restricting portion 404 protrudes radially outward from the circular portion 408. The rotation restricting portion 405 is positioned on the handle portion 407 and protrudes in the thrust direction when the conductive bearing 203 is mounted. Because the conductive bearing 203 is held in place by the snap-fit ​​403, the bearing holder 400 can be easily attached and detached. Therefore, in the event of accidental failure or periodic replacement, the conveyor roller 200 can be easily replaced.

[0035] A second member 402 is positioned in the circular portion 408 of the bearing holder 400 that holds the conductive bearing 203. The second member 402 needs to actively contact the conductive bearing 203 in order to establish electrical contact with the conductive bearing 203, which is held by the snap-fit ​​403. Therefore, in this embodiment, the inner diameter of the second member 402 is smaller than the inner diameter of the first member 401. Also, in order to actively contact and establish electrical contact with the frame on which the bearing holder 400 is supported, the outer diameter of the second member 402 is larger than the outer diameter of the first member 401. Note that the inner and outer diameters of the first member 401 correspond to the inner and outer diameters of the circular portion 408 of the first member.

[0036] Specifically, when mounted on the conductive bearing 203, the distance from the rotation center O of the conductive bearing 203 to the inner diameter portion 402a of the second member 402 is smaller than the distance from the rotation center O to the inner diameter portion 401a of the first member 401. Also, when mounted on the conductive bearing 203, the distance from the rotation center O of the conductive bearing 203 to the outer diameter portion 402b of the second member 402 is larger than the distance from the rotation center O to the outer diameter portion 401b of the first member 401. In other words, the inner diameter portion 402a of the second member 402 is positioned to actively contact the conductive bearing 203, and the outer diameter portion 402b is positioned to actively contact the grounded frame.

[0037] Furthermore, the inner diameter portion 402a and outer diameter portion 402b of the second member are positioned between the conductive bearing 203 and the frame in the radial direction of the conductive bearing 203 when the conductive bearing 203 is mounted on the frame. In addition, the inner diameter portion 401a and outer diameter portion 401b of the first member are positioned between the conductive bearing 203 and the frame in the radial direction of the conductive bearing 203 when the bearing holder 400 and the conductive bearing 203 are mounted on the frame.

[0038] In this embodiment, the second members 402 are arranged at four locations on the circumference of the bearing holder 400. Since the transport rollers 200 are used in various units that transport sheets within the image forming apparatus, the angle at which the bearing holder 400 is mounted on the frame varies for various reasons, such as the design location, available space, and the arrangement of other components. Therefore, the second members 402 are arranged at four locations on the circumference of the bearing holder 400 so that the roller pressure F is applied to the second members 402 and the conductors are reliably connected, regardless of the angle at which the bearing holder 400 is mounted. In this embodiment, two second members 402 are arranged between two snap-fits 403 in the circumferential direction of the bearing holder 400. In other words, when the bearing holder 400 is mounted on the conductive bearing 203, the second members 402 are positioned symmetrically with respect to a straight line passing through the rotation center O of the conductive bearing 203 and the snap-fit ​​403.

[0039] Electrical conductivity can be achieved if the second member 402 is positioned at a location where the roller pressure F of the conveyor roller 200 is applied. Therefore, it is sufficient for the second member 402 to be positioned at one or more locations on the semicircular side where the conveyor roller 200 receives roller pressure when conveying a sheet. That is, it is preferable that the second member 402 is positioned on the opposite side of the nip portion of the conveyor roller 200 with respect to the rotation center of the roller shaft 201, when viewed from the direction of the rotation axis of the conveyor roller 200. In this embodiment, since the conveyor roller 200 is subjected to roller pressure F from below, it is necessary for the second member 402 to be positioned at at least one location on the upper semicircular side of the bearing holder when the bearing holder 400 is installed. However, the arrangement, number, and size of the second member 402 can be determined as appropriate.

[0040] <Configuration of the transport unit> Figure 7 shows a perspective view of the upper transport unit 101. The upper transport unit 101, which supports the transport rollers 200, includes a front support plate 501, a rear support plate 502, a support plate 503 that spans the front support plate 501 and the rear support plate 502, the transport rollers 200, and a bearing holder 400. The front support plate 501, the rear support plate 502, and the support plate 503 are examples of frames, made of sheet metal, and in contact with a grounded structure. In other words, the frames are grounded. In this embodiment, the rear support plate 502 is an example of a side plate.

[0041] The conductive bearing 203 on the front side of the conveyor roller 200 is supported by a front support plate 501. The conductive bearing 203 on the rear side of the conveyor roller 200 is supported by a rear support plate 502 via a bearing holder 400. The conveyor roller 200 can rotate freely as the conductive bearings 203 located on both sides rotate.

[0042] In this embodiment, a bearing holder 400 is attached to the conductive bearing 203 on the rear side of the conveyor roller 200, but a bearing holder 400 is not attached to the conductive bearing 203 on the front side of the conveyor roller 200. In other words, a bearing holder 400 is attached to the conductive bearing 203 located at one end of the conveyor roller 200, but a bearing holder 400 is not attached to the conductive bearing 203 located at the other end of the conveyor roller 200. The conductive bearing 203 on the front side is grounded even without a bearing holder 400 because it contacts the front support plate 501 due to the nip pressure F from the driven roller 300. That is, in this embodiment, the conveyor roller 200 is grounded at two locations, the rear side and the front side. Specifically, the conductive bearing 203 on the front side is grounded by the front support plate 501 due to the nip pressure, and the conductive bearing 203 on the rear side is grounded by the rear support plate 502 via the second member 402 made of conductive resin of the bearing holder 400. In this configuration, the number of parts can be reduced by placing the conductive bearing 203 only on one end of the conveyor roller 200.

[0043] However, the conductive bearing 203 on the far side of the conveyor roller 200 may not have a bearing holder 400 installed, while the conductive bearing 203 on the near side of the conveyor roller 200 may have a bearing holder 400 installed. However, the conductive bearing 203 on both the near side and the far side of the conveyor roller 200 may have bearing holders 400 installed. However, the bearing holder 400 must be installed on at least one side of the conveyor roller 200 in order to regulate the thrust position of the conveyor roller 200, as will be described later.

[0044] Figure 8 is an explanatory diagram for attaching the conveyor roller 200 to the upper conveyor unit 101. Figures 9 and 10 are explanatory diagrams for attaching the bearing holder 400. Figure 9(a) shows the state before attaching the bearing holder 400 to the conductive bearing 203. Figure 9(b) shows the state after attaching the bearing holder 400 to the conductive bearing 203. Figure 10(a) shows the conveyor roller mounting portion 504 of the rear support plate 502. Figure 10(b) shows the bearing holder 400 being inserted into the conveyor roller mounting portion 504. Figure 10(c) shows the bearing holder 400 after it has been attached.

[0045] Figure 8 is a view of the upper transport unit 101 from the rear. The front support plate 501 has an opening 505. The rear support plate 502 has a transport roller mounting section 504, which is an opening. After the transport roller 200 is attached to the frame, the bearing 203 on the front side of the transport roller 200 is positioned so that it overlaps with the front support plate 501 when viewed from the sheet transport direction. Also, after the transport roller 200 is attached to the frame, the bearing 203 and bearing holder 400 on the rear side of the transport roller 200 are positioned so that they overlap with the rear support plate 502 when viewed from the sheet transport direction. However, since the transport roller mounting section 504 has a bearing holder 400 in addition to the conductive bearing 203, the size of the transport roller mounting section 504 is larger than the size of the opening 505.

[0046] As shown in Figure 8, when installing the conveyor roller 200, the conveyor roller 200 is placed on the mounting portion 504 of the front support plate 501 and the rear support plate 502, and the bearing holder 400 is attached to the bearing 203 on the rear side (arrow in Figure 8). At that time, as shown in Figure 9, the bearing holder 400 is fitted from the rear side toward the conductive bearing 203, and the conductive bearing 203 is held by the snap fit 403 of the bearing holder 400. In this embodiment, since the conductive bearing 203 is held by the snap fit 403 of the bearing holder 400, the bearing holder 400 and the conductive bearing 203 can be easily attached and detached without the need for tools such as a screwdriver. In this embodiment, the conductive bearing 203 is a flangeless conductive bearing. When the bearing holder 400 is attached to the conductive bearing 203, the inner restricting portion 409 abuts against the side surface of the conductive bearing 203. As a result, the conductive bearing 203 is held without penetrating the bearing holder 400 (Figure 5).

[0047] Figure 10 is a view of the transport roller mounting section 504 from the rear side of the upper transport unit 101 (arrow in Figure 8). As shown in Figure 10(a), the transport roller mounting section 504 has a circular section 504a into which the circular section 408 of the bearing holder 400 is inserted, an opening 504b into which the thrust position restricting section 404 is inserted, and a positioning section 504c into which the rotation restricting section 405 is inserted. As shown in Figure 10(b), after attaching the bearing holder 400 to the conductive bearing 203, the thrust position restricting section 404 of the bearing holder 400 is aligned with the position of the opening 504b, and the bearing holder 400 is inserted into the rear support plate 50. Then, as shown in Figure 10(c), the bearing holder 400 is rotated and the rotation restricting section 405 is fitted into the positioning section 504c. As a result, the thrust position restricting part 404 and the rotation restricting part 405 catch on the rear support plate 502, preventing the bearing holder 400 from coming off the rear support plate 502, thereby determining the thrust position of the conveyor roller 200. The rotation restricting part 405 is positioned in the center of the ring-shaped handle part 407 that extends from the flange part 406, making it easy for the user to insert the rotation restricting part 405 into the rear support plate 502. When replacing or removing the conveyor roller 200, the conveyor roller can be easily replaced by performing the reverse of the above operation.

[0048] Furthermore, the flange portion 406 of the bearing holder 400 protrudes radially from the bearing holder 400, and the outer diameter of the flange portion 406 is larger than the circular portion 504a of the conveyor roller mounting portion 504. Furthermore, the thrust position restricting portion 404 of the bearing holder 400 is smaller than the shape of the opening 504b of the conveyor roller mounting portion 504. In this embodiment, the circular portion 504a is an example of a first opening, and the opening 504b is an example of a second opening. Furthermore, after the thrust position of the bearing holder 400 has been positioned (Figure 10(c)), the thrust position restricting portion 404 is located inside the rear support plate 502, and the flange portion 406 is located outside the rear support plate 502. In other words, the thrust position restricting portion 404 and the flange portion 406 of the bearing holder 400 sandwich the rear support plate 502, thereby restricting the axial position of the conveyor roller 200. In this embodiment, the thrust position restricting portion 404 is an example of a first protrusion, and the flange portion 406 is an example of a second protrusion.

[0049] By adopting the configuration described above, the transport roller 200 can be reliably and stably grounded to the front support plate 501 and the rear support plate 502 through the conductive bearing 203 and the bearing holder 400. Furthermore, the front support plate 501 and the rear support plate 502 are grounded. This suppresses malfunctions caused by static electricity generated by the rotational friction of the transport roller 200, making it possible to provide a transport roller configuration with excellent durability and serviceability.

[0050] In the embodiments described above, the case in which the image forming system is applied to an inkjet recording system 1 is described, but it is not limited to this and may also be applied to an electrophotographic image forming system. [Explanation of Symbols]

[0051] 200 Conveyor Rollers 203 Conductive bearing 400 Bearing Holder 401 First component (general resin) 402 Second component (conductive resin) 403 Snap-Fit 404 Thrust Position Restriction 405 RPM limit 501 Front support plate 502 Rear support plate

Claims

1. A conveyor roller for transporting the sheet, A conductive bearing that rotatably supports the rotating shaft of the conveying roller, A frame that supports the aforementioned conveyor roller and is grounded, A bearing holder supported by the frame and holding the bearing, It has, The bearing holder comprises a first member made of a non-conductive resin and a second member made of a conductive resin. The second member contacts the bearing and the frame. A sheet conveying device characterized by the following features.

2. The inner diameter of the second member that contacts the outer diameter of the bearing is smaller than the inner diameter of the first member, and the outer diameter of the second member that contacts the frame is larger than the outer diameter of the first member. The sheet conveying device according to feature 1.

3. The ratio of the surface area of ​​the first member to the surface area of ​​the bearing holder is greater when the ratio of the surface area of ​​the second member to the surface area of ​​the bearing holder is greater. The sheet conveying device according to feature 1.

4. The conveying roller to which the bearing holder is attached forms a nip section with a roller positioned opposite to the conveying roller, and conveys the sheet. The second member is positioned on the opposite side of the nip portion from the center of rotation of the rotation axis when viewed from the direction of the rotation axis of the conveyor roller. The sheet conveying device according to feature 1.

5. The bearing holder comprises a plurality of the second members. The sheet conveying device according to feature 1.

6. The bearings are positioned at both ends of the rotating shaft, The bearing located at one end of the conveying roller is fitted with the bearing holder. The bearing located at the other end of the conveying roller does not have the bearing holder attached. The sheet conveying device according to feature 1.

7. The bearing holder has a snap fit for holding the bearing, The snap fit is composed of the first member. The sheet conveying device according to feature 1.

8. The bearing holder has a first projection and a second projection that protrude radially from the bearing holder and are positioned at different locations in the thrust direction. The first and second protrusions sandwich the frame, thereby restricting the axial position of the conveying roller. The sheet conveying device according to feature 1.

9. The bearing holder has a rotation restricting part that restricts the rotation of the bearing holder, The rotation restricting portion is fixed in a position where the first protrusion has been rotated from the position in which it was inserted into the opening of the frame. The sheet conveying device according to feature 8.

10. The bearing is press-fitted into the conveyor roller. The sheet conveying device according to feature 1.

11. A sheet conveying device according to claim 1, An image forming unit that forms an image on a sheet, An image forming apparatus characterized by having the following features.

Images