Image forming device

Abstract

To enable properly and easily changing rollers in an image forming device.SOLUTION: A first bearing 203 and a second bearing 203 are respectively pressed in and secured to a shank 202. A first support member 211 and a second support member 212 include support parts 213 equipped with openings 213a that respectively receive the first bearing 203 and the second bearing 203 along a prescribed direction almost orthogonal to the direction of the revolving shaft of the roller 200 when the roller 200 is supported to the first support member 211 and the second support member 212. The roller 200 is constituted such that the first bearing 203 and the second bearing 203 secured to the roller 200 respectively are moved in parallel in a prescribed direction so as to be received by the support parts 213 of the first support member 211 and the second support member 212 and are assembled to the first support member 211 and the second support member 212.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of functions of these machines, which uses an electrophotographic or electrostatic recording system. [Background technology]

[0002] Conventionally, in image forming devices such as copying machines using an electrophotographic system, there are rollers that are replaced before the end of the life of the main body of the image forming device due to functional degradation such as reduced transportability caused by wear on the roller surface or adhesion of paper powder.

[0003] One example is a transfer roller that is detachable from the main body of an image forming apparatus. In an image forming apparatus, a toner image formed on an image carrier such as a photoreceptor or an intermediate transfer body is transferred to a recording material by applying a transfer bias to the transfer roller. As the transfer roller, for example, an elastic roller having an elastic layer in which an ion conductive agent or the like is dispersed to give electrical conductivity is used. In such a transfer roller, the electrical resistance may increase due to uneven distribution of the ion conductive agent when electricity is applied. Then, in relation to the capacity of the high-voltage substrate, it may be necessary to replace the transfer roller with a new one when the electrical resistance has increased.

[0004] The replacement of the transfer roller is generally performed by a specialized service technician who is familiar with the task, and is rarely performed by general users who are unfamiliar with the task, so the ease of handling the transfer roller during the replacement task has not been given much importance.

[0005] However, in recent years, there has been an increase in opportunities for general users to replace replacement parts such as transfer rollers in image forming apparatuses in order to reduce costs, etc. Therefore, it is desirable to improve the ease of replacement so that even general users can properly and easily replace transfer rollers.

[0006] Patent Document 1 proposes a transfer roller equipped with a bearing and a retaining member on the shaft portion. After the roller unit is assembled to a support member and mounted in a housing, the retaining member is rotated around the shaft to prevent the roller from coming off. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-197204 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the above conventional roller unit configuration, the bearings and retaining members are attached and fitted to the shaft, and can move in the axial direction when force is applied. This means that parts can fall off the shaft when the roller unit is attached or detached, or can become misaligned relative to the support member, reducing replaceability.

[0009] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to enable proper and easy replacement of rollers in an image forming apparatus. [Means for solving the problem]

[0010] The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to an image forming apparatus having an image carrier that carries a toner image, a rotatable roller that has a shaft portion protruding from one end and the other end in the rotation axis direction of the roller and is capable of contacting the image carrier, a first bearing attached to the shaft portion at the one end, a second bearing attached to the shaft portion at the other end, a first support member that supports the roller via the first bearing, and a second support member that supports the roller via the second bearing, the first bearing and the second bearing are each press-fitted and fixed to the shaft portion, The image forming apparatus is characterized in that the first support member and the second support member have support portions with openings that respectively receive the first bearing and the second bearing along a predetermined direction that is approximately perpendicular to the rotational axis direction of the roller when the roller is supported by the first support member and the second support member, and the roller is configured to be assembled to the first support member and the second support member by being translated along the predetermined direction so that the first bearing and the second bearing fixed to the roller are received in the support portions of the first support member and the second support member, respectively. Effect of the Invention

[0011] According to the present invention, it is possible to appropriately and easily replace a roller in an image forming apparatus. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic cross-sectional view of the image forming apparatus (with the cover closed). [Diagram 2] FIG. 2 is a schematic cross-sectional view of an image forming unit. [Diagram 3] FIG. 2 is a schematic cross-sectional view of the image forming apparatus (with the cover open). [Figure 4] FIG. 4 is a perspective view of an outer secondary transfer roller and a bearing. [Diagram 5] FIG. 4 is a perspective view of a secondary transfer outer roller unit. [Figure 6] FIG. 4 is a perspective view of a pressure / power supply portion of the outer secondary transfer roller. [Figure 7] FIG. 4 is a cross-sectional view of a pressure / power supply portion of the outer secondary transfer roller. [Figure 8] 4 is a cross-sectional view of a pressing portion of the outer secondary transfer roller. [Figure 9] FIG. 2 is a perspective view of a secondary transfer unit. [Figure 10] 13 is a front view of the outer secondary transfer roller unit on one end side of the outer secondary transfer roller. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[0014] [Example 1] 1. Overall configuration and operation of the image forming apparatus First, the overall configuration and operation of the image forming apparatus of this embodiment will be described. Fig. 1 is a schematic cross-sectional view of the image forming apparatus 100 of this embodiment. The image forming apparatus 100 of this embodiment is a tandem type laser beam printer that employs an intermediate transfer method and is capable of forming a full-color image on a sheet-like recording material S such as paper or a plastic sheet using an electrophotographic method.

[0015] The image forming apparatus 100 has four image forming units PY, PM, PC, and PK as a plurality of image forming units (stations) that form images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. The four image forming units PY, PM, PC, and PK are arranged in a line along the conveying direction of the image transfer surface of the intermediate transfer belt 7, which will be described later. Note that elements having the same or corresponding functions or configurations provided for each color may be generally described by omitting the suffixes Y, M, C, and K of the reference numerals indicating that the elements are provided for any one of the colors. FIG. 2 is a schematic cross-sectional view showing an enlarged configuration of the image forming unit P. In this embodiment, the image forming portion P is composed of photosensitive drums 1 (1Y, 1M, 1C, 1K), charging rollers 2 (2Y, 2M, 2C, 2K), an exposure device 3, developing devices 4 (4Y, 4M, 4C, 4K), primary transfer rollers 5 (5Y, 5M, 5C, 5K), drum cleaning devices 6 (6Y, 6M, 6C, 6K), etc. In this embodiment, the exposure device 3 is configured as one unit that exposes the photosensitive drums 1Y, 1M, 1C, 1K of the four image forming portions PY, PM, PC, PK, but may be provided independently for each image forming portion P.

[0016] Here, with regard to the image forming apparatus 100 and its elements, the front side of the paper in Fig. 1 is referred to as the "front side (front side)" and the rear side of the paper in Fig. 1 is referred to as the "rear side (rear side)". The front-rear direction (direction perpendicular to the paper in Fig. 1) connecting the front side and the rear side is assumed to be approximately parallel to the rotation axis direction of the tension roller of the photosensitive drum 1 and the intermediate transfer belt 7. Also, with regard to the image forming apparatus 100 and its elements, up and down refers to up and down in the direction of gravity (vertical direction), but does not mean only directly above and directly below, but also includes above and below a horizontal plane passing through a reference position or element.

[0017] The photosensitive drum 1, which is a drum-type photosensitive member (electrophotographic photosensitive member) serving as a first image carrier, is rotated in the direction of the arrow R1 in the figure (clockwise direction). The surface of the rotating photosensitive drum 1 is charged approximately uniformly to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charging roller 2, which is a roller-type charging member serving as a charging means. The surface of the charged photosensitive drum 1 is scanned and exposed by an exposure device (laser scanner) 3 serving as an exposure means in accordance with an image signal (image information), and an electrostatic latent image (electrostatic image) corresponding to the image signal is formed on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is developed (visualized) by a developing device 4 serving as a developing means, which supplies toner as a developer, and a toner image (toner image, developer image) is formed on the photosensitive drum 1.

[0018] An intermediate transfer belt 7, which is an intermediate transfer body formed of an endless belt as a second image carrier, is arranged to face the four photosensitive drums 1Y, 1M, 1C, and 1K. The intermediate transfer belt 7 is stretched around a secondary transfer inner roller 71, a tension roller 72, a primary transfer pre-roller 73, and a secondary transfer pre-roller 74 as a plurality of tension rollers and stretched with a predetermined tension. The intermediate transfer belt 7 rotates (moves around) in the direction of arrow R2 (counterclockwise direction) in the figure by transmitting a driving force when the secondary transfer inner roller 71, which also serves as a drive roller, is rotated. Primary transfer rollers 5Y, 5M, 5C, and 5K, which are roller-type primary transfer members as primary transfer means, are arranged on the inner peripheral surface side of the intermediate transfer belt 7 in correspondence with the four photosensitive drums 1Y, 1M, 1C, and 1K, respectively. The primary transfer roller 5 presses the intermediate transfer belt 7 toward the photosensitive drum 1, forming a primary transfer portion (primary transfer nip) T1 (T1Y, T1M, T1C, T1K) which is a contact portion between the photosensitive drum 1 and the intermediate transfer belt 7. That is, the primary transfer portion T1 is formed by sandwiching the intermediate transfer belt 7 between the primary transfer roller 5 and the photosensitive drum 1. The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the rotating intermediate transfer belt 7 at the primary transfer portion T1 by the action of a predetermined pressure force and an electric bias applied by the primary transfer roller 5. During the primary transfer, a primary transfer voltage (primary transfer bias) of a polarity opposite to the normal charging polarity (positive polarity in this embodiment) which is the charging polarity of the toner during development is applied to the primary transfer roller 5. For example, when a full-color image is formed, the toner images of each color of YMCK formed on each photosensitive drum 1 are transferred sequentially to the intermediate transfer belt 7 so as to be superimposed on each other at each primary transfer portion T1.

[0019] On the outer peripheral surface side of the intermediate transfer belt 7, a secondary transfer outer roller 200, which is a roller-type secondary transfer member (transfer roller) serving as a secondary transfer means, is disposed at a position facing the secondary transfer inner roller 71 serving as an opposing roller. The secondary transfer outer roller 200 is pressed against the secondary transfer inner roller 71 via the intermediate transfer belt 7, forming a secondary transfer portion (secondary transfer nip) T2, which is a contact portion between the intermediate transfer belt 7 and the secondary transfer outer roller 200. That is, the secondary transfer portion T2 is formed by sandwiching the intermediate transfer belt 7 between the secondary transfer inner roller 71 and the secondary transfer outer roller 200. The toner image formed on the intermediate transfer belt 7 is transferred (secondarily transferred) onto the recording material S, which is being conveyed while being sandwiched between the intermediate transfer belt 7 and the secondary transfer outer roller 200, by the action of the pressure force and the electric bias applied by the secondary transfer outer roller 200 in the secondary transfer portion T2. During the secondary transfer, a secondary transfer voltage (secondary transfer bias) of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the secondary transfer outer roller 200. The secondary transfer inner roller 71 is electrically grounded. Alternatively, a secondary transfer voltage of the same polarity as the normal charging polarity of the toner may be applied to the secondary transfer inner roller 71, and the secondary transfer outer roller 200 may be electrically grounded.

[0020] Recording materials (transfer materials, recording media, sheets) are stacked and stored in a recording material storage 11. The recording materials S are fed one by one by a feeding roller 12 as a feeding member, and are conveyed to a registration roller 13 as a conveying member. Then, the skew of the recording materials S is corrected by the registration roller 13, and the recording materials S are sent to the secondary transfer section T2 at an appropriate timing.

[0021] The recording material S onto which the toner image has been transferred is sent to a fixing device 14 as a fixing means. The fixing device 14 applies heat and pressure to the recording material S carrying the unfixed toner image to fix (melt and adhere) the toner image onto the recording material S. The recording material S onto which the toner image has been fixed is discharged (output) to the outside (outside the machine) of the device main body 110 of the image forming apparatus 100 by a pair of discharge rollers 15 as a conveying member. The recording material S discharged from the device main body 110 is sequentially stacked on a stack unit 16 provided outside the device main body 110.

[0022] Furthermore, toner remaining on the photosensitive drum 1 after the primary transfer process (primary transfer residual toner) is removed from the photosensitive drum 1 and collected by a drum cleaning device 6 serving as a photosensitive body cleaning means. Furthermore, a belt cleaning device 75 serving as an intermediate transfer body cleaning means is disposed at a position facing the tension roller 72 on the outer circumferential surface side of the intermediate transfer belt 7. Adherents such as toner remaining on the intermediate transfer belt 7 after the secondary transfer process (secondary transfer residual toner) are removed from the intermediate transfer belt 7 and collected by the belt cleaning device 75.

[0023] In this embodiment, in each image forming portion P, the photosensitive drum 1, the charging roller 2 acting on the photosensitive drum 1 as a process means, the developing device 4, and the drum cleaning device 6 constitute a process cartridge 8. The process cartridge 8 is detachably attached to the apparatus main body 110 as a whole.

[0024] The intermediate transfer belt 7, the multiple tension rollers 71-74 around which the intermediate transfer belt 7 is tensioned, the primary transfer rollers 5, the belt cleaning device 75, etc., constitute an intermediate transfer unit 9. The intermediate transfer unit 9 is detachably attached to an apparatus main body 110 as a whole. The apparatus main body 110 of the image forming apparatus 100 refers to the portion of the image forming apparatus 100 excluding the process cartridges 8 and the intermediate transfer unit 9.

[0025] 2. Opening and closing the cover In the image forming apparatus 100 of this embodiment, a cover 10 is provided as an openable / closable member on the right side when viewed from the front. This is for removing a jam of the recording material S that occurs in the conveying path 17 of the recording material S, or for replacing parts such as the outer secondary transfer roller 200 and the intermediate transfer unit 9.

[0026] The cover 10 is provided with a cover rotation shaft 18. The cover 10 is supported to be rotatable about a rotation axis extending substantially horizontally in the front-rear direction by engaging the cover rotation shaft 18 with a frame (not shown) constituting the housing 120 of the image forming apparatus 100. FIG. 3 is a schematic cross-sectional view showing a state in which the cover 10 of the image forming apparatus 100 of this embodiment is opened. As shown in FIG. 3, the cover 10 is supported by a link mechanism (not shown) provided to connect the frame of the image forming apparatus 100 and the cover 10, and is stopped at a predetermined position when opened. The cover 10 can be opened and closed by an operator such as a user or a service person operating a handle (not shown) provided on the cover 10.

[0027] In this embodiment, the secondary transfer unit 220 as a support device for supporting the secondary transfer outer roller 200 is attached to the cover 10. When the cover 10 is closed as shown in FIG. 1, the secondary transfer unit 220 is sandwiched between the member in the device body 110 and the cover 10 and arranged at a predetermined position. In this embodiment, the secondary transfer unit 220 is arranged at a predetermined position by being positioned by the member in the device body 110. In this state, the secondary transfer outer roller 200 is pressed against the surface (outer peripheral surface) of the intermediate transfer belt 7, which is a second image carrier as a contact member wrapped around the secondary transfer inner roller 71, and becomes operable (image forming possible). Then, as shown in FIG. 3, when the cover 10 is opened, the secondary transfer unit 220 (secondary transfer outer roller 200) moves together with the cover 10 in a direction away from the intermediate transfer belt 7 (secondary transfer inner roller 71), and the operator can access the secondary transfer unit 220. 3, in a state where the cover 10 is open, the secondary transfer unit 220 exposes the secondary transfer outer roller 200 upward and exposes at least a part of both side surfaces in the front-rear direction to the front and rear sides, respectively. Note that, in a state where the secondary transfer outer roller 200 is supported by the secondary transfer unit 220 and attached to the cover 10, the rotation axis direction (rotation axis direction) of the secondary transfer outer roller 200 is approximately parallel to the front-rear direction.

[0028] 3. Secondary transfer unit 3-1. Secondary transfer outer roller Next, a description will be given of the configuration of the outer secondary transfer roller 200 as a replacement roller member in this embodiment. Fig. 4 is an external perspective view showing the outer secondary transfer roller 200 (and a bearing 203, described later, fixed thereto) in this embodiment.

[0029] The secondary transfer outer roller 200 has a roller part 201 formed of an elastic body constituting an elastic layer (in this embodiment, a foamed elastic layer), and a shaft part 202 constituting a core metal part. In this embodiment, the roller part 201 is made of a sponge (foamed elastic body) formed of NBR rubber or EPDM rubber containing a conductive agent such as a metal complex or carbon. In this embodiment, the shaft part 202 is made of metal. At both ends of the secondary transfer outer roller 200 in the rotation axis direction, the shaft part 202 protrudes from the roller part 201. In this embodiment, the secondary transfer outer roller 200 is formed so that the outer diameter of the roller part 201 is 24 mm, and the thickness of the roller part 201 (sponge layer) is 6 mm. However, the roller diameter and the thickness of the elastic layer are not limited to these.

[0030] A pair of bearings 203 are attached to the shaft portion 202 at both ends of the secondary transfer outer roller 200 in the direction of the rotation axis. In this embodiment, a ball bearing is used as the bearing 203. However, the present invention is not limited to this, and for example, a ball bearing or a roller bearing, which is typically a rolling bearing, can be preferably used. The bearing 203 may have a general structure, and has an outer ring, an inner ring, and a rolling element (ball in this embodiment) arranged between them (and may further have a retainer that holds the rolling element between the outer and inner rings). The bearing 203 has sufficient conductivity to contact a pressing member (moving member) 216 that functions as an electrical connection portion described later and connect the secondary transfer outer roller 200 to a power supply path (current path). In this embodiment, the outer ring, inner ring, and ball of the bearing 203 are each made of metal, and have sufficient conductivity. In this embodiment, the bearings 200 at both ends of the secondary transfer outer roller 200 in the direction of the rotation axis have substantially the same configuration.

[0031] Here, the bearing 203 is press-fitted and fixed onto the shaft portion 202. The outer diameter of the shaft portion 202 before the bearing 203 is press-fitted is slightly larger than the inner diameter of the inner ring of the bearing 203. The difference in diameter is the press-fit allowance. As a result, after the bearing 203 is press-fitted onto the shaft portion 202, it will not move on the shaft portion 202 in the direction of the rotation axis of the outer secondary transfer roller 200 or come off the shaft portion 202 due to normal forces applied during replacement work of the outer secondary transfer roller 200, which will be described later.

[0032] 3-2. Secondary transfer outer roller unit Next, the pressure application and power supply configuration of the secondary transfer outer roller 200 in this embodiment will be described. FIG. 5 is a perspective view of the secondary transfer outer roller unit 210 in this embodiment. In FIG. 5, the rear side of the secondary transfer outer roller 200 in the rotation axis direction is shown on the left side of the paper. Also, FIG. 6 is a perspective view showing the pressure application and power supply configuration of the secondary transfer outer roller 200 in this embodiment. In FIG. 6, the pressure application and power supply configuration provided at the rear end of the secondary transfer outer roller 200 in the rotation axis direction is shown, and the secondary transfer outer roller 200 is omitted. Also, FIG. 7 is a cross-sectional view showing the pressure application and power supply configuration of the secondary transfer outer roller 200 at the rear end of the secondary transfer outer roller 200 in the rotation axis direction (showing a cross section approximately parallel to the rotation axis direction of the secondary transfer outer roller 200). Also, FIG. 8 is a cross-sectional view showing the pressure application configuration of the secondary transfer outer roller 200 at the front end of the secondary transfer outer roller 200 (showing a cross section approximately parallel to the rotation axis direction of the secondary transfer outer roller 200).

[0033] As shown in Fig. 5, the outer secondary transfer roller 200 is supported at both ends in the direction of its rotation axis by a support member R (rear support member, first support member) 211 and a support member F (front support member, second support member) 212 via bearings 203. In this embodiment, the support members R211 and F212 are each integrally formed of an electrically insulating resin. In this embodiment, the outer secondary transfer roller unit 210 is configured by the outer secondary transfer roller 200 (and the bearing 203 fixed thereto), the support member R211 (and a pressing member 216 held by it, described later), and the support member F212.

[0034] In this embodiment, the support members R211 and F212 have the same configuration (substantially symmetrical with respect to a plane that passes through the center of the outer secondary transfer roller 200 in the rotational axis direction and is approximately perpendicular to the rotational axis direction of the outer secondary transfer roller 200) except for differences that will be described later. As will be described later, the support members R211 and F212 differ mainly in the configuration based on the presence or absence of a pressing member 216 and the positioning configuration of the bearing 203.

[0035] First, referring to FIG. 6 and FIG. 7, the pressure application and power supply configuration of the secondary transfer outer roller 200 at the end on the inner side in the rotation axis direction of the secondary transfer outer roller 200 will be described. The support member R211 is held by a secondary transfer guide 221 (FIG. 9) as a holding member described later so as to be slidable along a predetermined direction. This predetermined direction is a direction toward the intermediate transfer belt 7 (secondary transfer inner roller 71) during operation of the image forming apparatus 100 and a direction opposite thereto. The support member R211 is pressed by a pressure member 217 along the above-mentioned predetermined direction in a direction toward the intermediate transfer belt 7 (secondary transfer inner roller 71) during operation of the image forming apparatus 100. In this embodiment, the pressure member 217 is composed of a compression coil spring made of a conductive metal. The pressure member 217 is disposed between a receiving portion 211a provided on the support member R211 and a seat surface 221a (see FIG. 6) provided on the secondary transfer guide 221.

[0036] Further, the support member R211 is provided with a support portion 213, and the bearing 203, which is press-fitted and fixed to the shaft portion 202 of the outer secondary transfer roller 200, is attached to this support portion 213 from above in Fig. 6. The attachment direction (insertion / removal direction) of this bearing 203 is a direction that is approximately perpendicular to the rotation axis direction of the outer secondary transfer roller 200 when the outer secondary transfer roller 200 is supported by the support members R211 and F212, and is a direction along the pressure direction of the pressure member 217. The support portion 213 is provided with an opening 213a that opens upward in Fig. 6 so that the bearing 203 can be received along this attachment direction.

[0037] Furthermore, the support member R211 holds a pressing member 216, which is a movable member, so as to be movable relative to the support member R211 in the pressure direction of the secondary transfer outer roller 200 by the pressure member 217. The pressing member 216 is slidably accommodated in a pressing member holding portion 211d provided on the support member R211. The pressing member 216 is exposed to an opening 213a of the support portion 213 so as to be able to come into contact with the bearing 203. A bearing abutment portion (abutment surface in this embodiment) 216b of the pressing member 216 that can come into contact with the outer periphery of the bearing 203 is disposed adjacent to a bearing abutment portion (abutment surface in this embodiment) 211b that can come into contact with the outer periphery of the bearing 203 of the support member R211. The bearing abutment portion 211b of the support member R211 and the bearing abutment portion 216b of the pressing member 216 may each be a flat surface, a curved surface (arc-shaped or U-shaped) along the outer periphery of the bearing 203, a rib shape, or the like. The pressing member 216 is made of a conductive material, particularly a conductive resin in this embodiment. The pressing member 216 may be made of other conductive materials such as metal. The pressing member 216 is pressed by a pressing member 217 that presses the support member R211 described above. The pressing direction is a direction along the sliding direction of the support member R211 as described above, and is a direction toward the bearing 203 arranged in the support portion 213. That is, the pressure member 217 is disposed between the receiving portion 211a of the support member R211 and the seat surface 221a of the secondary transfer guide 221 as described above, and is also disposed between the receiving portion 216a provided on the pressing member 216 and the seat surface 221a of the secondary transfer guide 221. As a result, the pressure member 217 contacts the support member R211 to press it, and contacts the pressing member 216 to press it toward the bearing 203, and the pressing member 216 contacts the bearing 203 to press it. In this embodiment, as shown in FIG. 5, a power supply member 218 to which a transfer current (transfer voltage) is supplied from a high-voltage power source provided in the image forming apparatus 100 is provided so as to contact the pressure member 217. In this embodiment, the power supply member 218 is configured of a conductive spring.As a result, in this embodiment, a power supply path (current path) from a high voltage power source is connected to the outer secondary transfer roller 200 through the power supply member 218, the pressure member 217, the pressing member 216, and the bearing 203.

[0038] In a state where the cover 10 is opened, that is, in a state where the secondary transfer outer roller 200 is separated from the intermediate transfer belt 7, the pressing member 216 pressed by the pressing member 217 is locked by the supporting member R211. That is, the supporting member R211 is provided with a locking portion 211c, and the pressing member 217 is provided with a locked portion 216c that engages with the locking portion 211c. Then, in a state where the locking portion 211c and the locked portion 216c are engaged with each other, the bearing abutting portion 216b of the pressing member 216 protrudes toward the bearing 203 side in the pressing direction of the pressing member 217 more than the bearing abutting portion 211b of the supporting member R211. In this state, at least a part of the bearing abutting portion 216b of the pressing member 216 protrudes toward the bearing 203 side by a protrusion amount W1 more than the bearing abutting portion 211b of the supporting member R211. When the outer secondary transfer roller 200 comes into contact with the intermediate transfer belt 7, the pressure from the pressure member 217 is applied to the bearing 203 via the bearing abutment portion 211b of the support member R211. At this time, the bearing abutment portion 216b of the pressing member 216 is retracted to a position substantially flush with the bearing abutment portion 211b of the support member R211 while applying the pressure from the pressure member 217 to the bearing 203. From the viewpoint of stability of the pressure of the outer secondary transfer roller 200, the protrusion amount W1 is preferably about 0.1 mm or more and 1 mm or less, and is about 0.3 mm in this embodiment.

[0039] With this configuration, when the outer secondary transfer roller 200 comes into contact with the intermediate transfer belt 7, the bearing 203 and the pressing member 216 can be brought into contact with each other more reliably. This allows the bearing 203 and the pressing member 216 to be electrically connected to each other more reliably. In addition, the pressing force of the pressing member 217 can be applied to the bearing 203 by the support member R211, which is easier to configure more robustly than the pressing member 216 made of conductive resin, and the pressing force of the pressing member 217 can be used to press the pressing member 216 and the bearing 203. With this simple configuration, the bearing 203 and the pressing member 216 can be electrically connected to each other more reliably, and the pressing force of the pressing member 217 can be applied to the bearing 203 more reliably. With this configuration, the pressing member 216 is disposed within a region in which the bearing 203 is projected along the pressing direction of the pressing member 217. That is, when viewed from the secondary transfer outer roller 200 side along the pressure direction of the pressure member 217, the pressure member 216 is hidden behind the bearing 203. This reduces the possibility that an operator touches the electrical connection portion for the secondary transfer outer roller 200 with the cover 10 open, causing the electrical connection portion to become dirty or to be damaged.

[0040] Next, the pressing configuration of the secondary transfer outer roller 200 at the front end of the secondary transfer outer roller 200 in the rotation axis direction will be described with reference to FIG. 8. As described above, in this embodiment, the support member F212 has the same configuration as the support member R211. However, in this embodiment, as shown in FIG. 8, the support member F212 does not have the above-mentioned pressing member 216 provided on the support member R211. The support member F212 receives the pressing force of the pressing member 217 at the receiving portion 212a and supports the bearing 203 at the bearing abutment portion 212b. As with the support member R211, the support member F212 is provided with a support portion 213, and the bearing 203, which is pressed and fixed to the shaft portion 202 of the secondary transfer outer roller 200, is attached to this support portion 213 from above in FIG. 8.

[0041] At this time, in this embodiment, the secondary transfer outer roller 200 is assembled to the support members R211 and F212 by translating the secondary transfer outer roller 200 along a predetermined direction (substantially only by this translational motion) so that the bearings 203 at both ends in the rotation axis direction are received by the support portions 213 of the support members R211 and F212, respectively, and the position of the secondary transfer outer roller 200 in the rotation axis direction can be determined. In this embodiment, the support portions 213 of the support member R211 are configured to fit with the bearings 203 in the rotation axis direction of the secondary transfer outer roller 200. Meanwhile, the support portions 213 of the support member F are configured to have a play with respect to the bearings 203 in the rotation axis direction of the secondary transfer outer roller 200. Specifically, as shown in FIG. 7, in the support member R211, the width W2 between the side walls 211e, 211e of the support portion 213 facing both sides of the bearing 203 in the rotation axis direction of the secondary transfer outer roller 200 is set to be substantially the same as the width W3 of the bearing 203, so that they are fitted together. As a result, the position of the secondary transfer outer roller 200 in the rotation axis direction to which the bearing 203 is fixed is determined in the support member R211. On the other hand, as shown in FIG. 8, in the support member F212, the width W4 between the side walls 212c, 212c of the support portion 213 facing both sides of the bearing 203 in the rotation axis direction of the secondary transfer outer roller 200 is set to be larger than the width W3 of the bearing 203, so that they have a play. As a result, even if there is variation in the length of the secondary transfer outer roller 200 in the rotation axis direction (the length between the pair of bearings 203), the secondary transfer outer roller 200 can be assembled to the support member R211 and the support member F212. In order to ensure a more reliable contact between the pressing member 216 and the bearing 203 that constitute the electrical connection portion, it is preferable to determine the position of the bearing 203 (secondary transfer outer roller 200) on the support member R211 that is the power supply side.

[0042] Thus, in this embodiment, the outer secondary transfer roller 200 is supported by the support members R211 and F212 via a pair of bearings 203 fixed to both ends in the rotation axis direction of the outer secondary transfer roller 200, and is pressed toward the secondary transfer belt 7. In this embodiment, the pressure of the pressure member 217 that presses the support member R211 is also used to press the pressing member 216 that constitutes an electrical contact with the outer secondary transfer roller 200 against the bearing 203. Here, since the outer ring of the bearing 203 does not rotate when the outer secondary transfer roller 200 rotates, it is possible to reduce (substantially eliminate) wear of the pressing member 216 made of conductive resin compared to a configuration in which a bearing made of conductive resin directly contacts the shaft of the roller.

[0043] The support members R211 and F212 are further provided with roller slip-off prevention portions 214, which prevent the attached outer secondary transfer roller 200 from coming off (details will be described later).

[0044] 3-3. Secondary transfer guide Next, the configuration of the secondary transfer guide 221 as a holding member to which the outer secondary transfer roller unit 210 is attached, and the secondary transfer unit 220 will be described with reference to FIGS.

[0045] FIG. 9 is an external perspective view of the secondary transfer unit 220 in this embodiment. In FIG. 9, the rear side in the rotation axis direction of the secondary transfer outer roller 200 is shown on the left side of the paper. Also, FIG. 10 is a front view of the secondary transfer unit 220 on one end side of the secondary transfer outer roller 200. In FIG. 10, the vicinity of the front end in the rotation axis direction of the secondary transfer outer roller 200 is shown, and the secondary transfer guide 221 is omitted. Here, as shown in FIG. 9 and FIG. 10, the rotation axis direction of the secondary transfer outer roller 200 is the A1 direction, the insertion and removal direction of the secondary transfer outer roller 200 in the secondary transfer unit 220 is the A2 direction (the mounting direction is the + (plus) direction), and the direction perpendicular to the A1 direction and the A2 direction is the A3 direction.

[0046] In this embodiment, the secondary transfer unit 220 is configured to include a secondary transfer guide 221 equipped with a sheet guide portion 222 that guides the recording material (sheet) S transported from the upstream side of the transport path, and a secondary transfer outer roller unit 210.

[0047] The secondary transfer guide 211 has support member holding portions 221b, 221b at both ends in the A1 direction, which respectively hold the support member R211 and the support member F212 so that they can slide. Between the support member holding portions 221b, 221b at both ends, a storage portion 221c is formed in which the secondary transfer outer roller 200 supported by the support member R211 and the support member F212 is stored. In the A1 direction, a gap X1 between the support portions 213 of the support member R211 and the support member F212 is the area of ​​the storage portion 222b. And, a bearing 203 that is press-fitted and fixed to the secondary transfer outer roller 200 is mounted on the support portions 213 of the support member R211 and the support member F212, so that the secondary transfer outer roller 200 is positioned in the A1 direction. Further, the outer secondary transfer roller 200 is also positioned in the A3 direction by the bearings 203 being fitted to the support portions 213 of the support members R211 and F212.

[0048] Further, as shown in FIG. 10, the roller retaining portions 214 are integrally formed with the support member R211 and the support member F212, respectively. The roller retaining portions 214 are respectively provided on both sides of a plane substantially parallel to the A2 direction passing through the center of the shaft portion 202 when viewed in the A1 direction so as to face the shaft portion 202. The roller retaining portions 214 on both sides are flexible so that they can bend away from the above-mentioned plane. Further, an opening 214a is provided between the roller retaining portions 214 on both sides, which is open upward in FIG. 10, that is, on the upstream side in the mounting direction (+A2 direction) of the secondary transfer outer roller 200. As shown in FIG. 10, regarding the A3 direction, if the width of the opening 214a between the roller retaining portions 214 on both sides is X2 and the diameter of the shaft portion 202 is D2, the relationship X2 < D2 is satisfied. That is, the secondary transfer outer roller 200 is configured not to move in the -A2 direction and come off the support member R211 and the support member F212 unless the roller retaining portions 214 on both sides are bent outward along the A3 direction under a predetermined load.

[0049] 3-4. Procedure for replacing the secondary transfer outer roller 200 Next, the procedure for replacing the secondary transfer outer roller 200 will be described. When replacing the secondary transfer outer roller 200, first, the operator opens the cover 10 as shown in FIG. 3 to expose the secondary transfer unit 220. At this time, the support member R211 and the support member F212 respectively protrude by the force of the pressing member 217. However, the support member retaining portions 219 (FIGS. 6 and 10) provided on the support member R211 and the support member F212 are configured to be locked by an engaging portion (not shown) provided on the secondary transfer guide 221. Therefore, the support member R211 and the support member F212 stop at a predetermined position and do not pop out (come off) from the secondary transfer guide 221.

[0050] The worker grasps the shaft portion 202 of the outer secondary transfer roller 200 and lifts the outer secondary transfer roller 200 (and the bearing 203 fixed thereto) along the insertion / removal direction of the outer secondary transfer roller 200 (-A2 direction). Then, the shaft portion 202 of the outer secondary transfer roller 200 bends the roller slip-out prevention portion 214, and the outer secondary transfer roller 200 comes off the secondary transfer unit 220. In this way, the operation of removing the outer secondary transfer roller 200 from the device main body 110 (secondary transfer unit 200) is completed.

[0051] Next, in the reverse procedure to the above-mentioned removal work, a replacement secondary transfer outer roller 200 (and the bearing 203 fixed thereto), which is usually a new secondary transfer outer roller 200, is attached to the secondary transfer unit 220. While holding the shaft portion 202 of the replacement secondary transfer outer roller 200, the worker presses the bearing 203 so that it fits into the support portion 213 of the secondary transfer unit 220, thereby bending the roller slippage prevention portion 214. In this way, the secondary transfer outer roller 200 is attached to the secondary transfer unit 220. At this time, the bearing 203 comes into contact with the bearing abutment portion 211b of the support member R211 and the bearing abutment portion 216b of the pressing member 216, and the bearing abutment portion 212b of the support member F212.

[0052] Finally, the worker closes the cover 10, thereby completing the installation of the replacement outer secondary transfer roller 200.

[0053] Thus, according to the configuration of this embodiment, when replacing the secondary transfer outer roller 200, the bearing 203 is press-fitted into the shaft portion 202 and does not move or fall. This reduces the risk of parts being difficult to place in the predetermined position or parts falling off during replacement of the secondary transfer outer roller 200, improving the workability of replacing the secondary transfer outer roller 200. Also, in this embodiment, the function of the roller slip-off prevention portion 214 is provided on the support member R211 or the support member F212, that is, on the device main body 110 (secondary transfer unit 200) side. This allows the configuration of the secondary transfer outer roller 200 to be replaced to be minimized, and also makes it possible to reduce the cost of replacement.

[0054] In this embodiment, the roller to be replaced is the secondary outer transfer roller 200, but the present invention is not limited to this. It may be another roller to be replaced in the image forming apparatus. In addition, the roller may be a roller that is driven to rotate, or a roller that is driven to rotate.

[0055] In this embodiment, the support member F212 is not provided with the pressing member 216, but a configuration in which pressing members are provided on the support members on both end sides in the direction of the rotation axis of the roller may be adopted.

[0056] In this embodiment, the pressure member 217 constitutes the power supply path to the pressing member 216. This allows the support member and the pressing member to be pressed and the power supply path to the pressing member to be connected with a simple configuration, as described above. However, a power supply path to the pressing member may be provided separately from the pressure member. For example, a first pressure member that presses the support member toward the bearing and a second pressure member (conductive spring) that presses the pressing member toward the bearing may be provided separately.

[0057] 4.Effects As described above, in this embodiment, the image forming apparatus 100 includes an image carrier (intermediate transfer belt) 7 that carries a toner image, a rotatable roller 200 that has an axle portion 202 protruding from one end and the other end in the direction of the rotation axis and that can abut against the image carrier 7 (secondary transfer outer roller), a first bearing 203 attached to the axle portion 202 at the one end, a second bearing 203 attached to the axle portion 202 at the other end, a first support member (support member R) 211 that supports the roller 200 via the first bearing 203, and a second support member (support member F) 212 that supports the roller 200 via the second bearing 203. In this embodiment, the first bearing 203 and the second bearing 203 are each pressed into and fixed to the shaft portion 202, and the first support member 211 and the second support member 212 have support portions 213 with openings 213a that receive the first bearing 203 and the second bearing 203, respectively, along a predetermined direction that is approximately perpendicular to the rotational axis direction of the roller 200 when the roller 200 is supported by the first support member 211 and the second support member 212, and the roller 200 is configured to be assembled to the first support member 211 and the second support member 212 by being translated along the above-mentioned predetermined direction so that the first bearing 203 and the second bearing 203 fixed to the roller 200 are received by the support portions 213 of the first support member 211 and the second support member 211, respectively. In this embodiment, the first support member 211 and the second support member 212 each have a retaining portion 214 that restricts the movement of the roller 200 in a direction in which the first bearing 203 and the second bearing 203 come off the support portion 213 along the above-mentioned predetermined direction. In this embodiment, the support portion 213 of the first support member 211 fits with the first bearing 203 in the direction of the rotation axis of the roller 200, and the support portion 213 of the second support member 212 has a play with respect to the second bearing 203 in the direction of the rotation axis of the roller 200. In this embodiment, the roller 200 rotates while being pressed against the image carrier 7. In this embodiment, the roller 200 forms a power supply path to the image carrier 7. In this embodiment, the roller 200 is a transfer roller that sandwiches the recording material S between the image carrier 7 and the roller 200 and transfers toner from the image carrier 7 to the recording material S.

[0058] Furthermore, according to this embodiment, since the parts attached to the roller do not move in the axial direction, it is possible to properly and easily replace the roller. [Explanation of symbols]

[0059] 7 Intermediate transfer belt 10. Cover 100 Image forming device 200 Secondary transfer outer roller 201 Roller Section 202 Shaft 203 Bearing 210 Secondary transfer outer roller unit 211 Support member R 212 Support member F 216 Pressing member 217 Pressure Members 218 Power supply components 220 Secondary transfer unit 221 Secondary Transfer Guide

Claims

1. an image carrier that carries a toner image; a rotatable roller having a shaft portion protruding from one end and the other end in a rotation axis direction of the roller, the roller being capable of contacting the image carrier; a first bearing attached to the shaft portion at the one end; a second bearing attached to the shaft portion at the other end; a first support member that supports the roller via the first bearing; a second support member that supports the roller via the second bearing; In an image forming apparatus having the first bearing and the second bearing are press-fitted and fixed to the shaft portion, the first support member and the second support member have support portions with openings that receive the first bearing and the second bearing, respectively, along a predetermined direction that is substantially perpendicular to a rotation axis direction of the roller when the roller is supported by the first support member and the second support member, an image forming apparatus characterized in that the roller is configured to be assembled to the first support member and the second support member by being translated along the predetermined direction so that the first bearing and the second bearing fixed to the roller are received in the support portions of the first support member and the second support member, respectively.

2. 2. The image forming apparatus according to claim 1, wherein the first support member and the second support member each have a slip-out prevention portion that restricts movement of the roller in a direction in which the first bearing and the second bearing come off the support portion along the predetermined direction.

3. 2. The image forming apparatus according to claim 1, wherein the support portion of the first support member is engaged with the first bearing in the axial direction of the roller, and the support portion of the second support member has play relative to the second bearing in the axial direction of the roller.

4. 2. The image forming apparatus according to claim 1, wherein the roller rotates while being pressed against the image bearing member.

5. 2. The image forming apparatus according to claim 1, wherein the roller constitutes a power supply path for the image carrier.

6. 6. The image forming apparatus according to claim 1, wherein the roller is a transfer roller that holds a recording material between the roller and the image carrier and transfers toner from the image carrier to the recording material.

Images