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, printer, facsimile machine, or multifunction machine having a plurality of functions of these machines, which uses an electrophotographic system or an electrostatic recording system. [Background technology]

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

[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 photosensitive member or an intermediate transfer member, is transferred to a recording material by applying a transfer bias to the transfer roller. The transfer roller is typically an elastic roller equipped with an elastic layer in which an ionic conductive material or the like is dispersed to provide electrical conductivity. Such a transfer roller may experience an increase in electrical resistance due to uneven distribution of the ionic conductive material when energized. Depending on factors such as the capacity of the high-voltage substrate, a transfer roller with such increased electrical resistance may need to be replaced with a new one.

[0004] This transfer roller replacement work is generally performed by specialized service personnel who are familiar with the work, and is rarely performed by general users who are unfamiliar with the work. Therefore, the ease of handling the transfer roller during the replacement work has not been given much importance.

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

[0006] Patent Document 1 proposes a transfer roller equipped with a bearing and a retaining member on the shaft. 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] Japanese Patent Application Laid-Open No. 2016-197204 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the above-mentioned conventional roller unit configuration, the bearings and retaining members are attached and fitted to the shaft, so they can move axially when force is applied. As a result, when attaching or detaching the roller unit, parts may fall off the shaft or become misaligned relative to the support member, reducing replaceability.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to enable roller replacement in an image forming apparatus to be carried out appropriately and easily. [Means for solving the problem]

[0010] The above object is achieved by the image forming apparatus according to the present invention. According to one aspect ofan 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 direction of the rotation axis of the roller and that can abut against 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, wherein the first bearing and the second bearing are each press-fitted and fixed to the shaft portion, and the first support member and the second support member have support portions that have openings that receive the first bearing and the second bearing, respectively, along a predetermined direction that is approximately perpendicular to the direction of the rotation axis of the roller when the roller is supported by the first support member and the second support member. a retaining portion that restricts movement of the roller in a direction in which the first bearing and the second bearing are disengaged from the support portion along the predetermined direction; 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. is provided . According to another aspect of the present invention, an image forming apparatus includes 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 that can abut against 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, wherein the first bearing and the second bearing are each press-fitted and fixed to the shaft portion, and the first support member and the second support member are configured such that the roller is supported by the first support member and the second support member. and a support portion having openings for respectively receiving the first bearing and the second bearing along a predetermined direction substantially perpendicular to the rotational axis direction of the roller when the roller is rotated, the roller is configured to be assemblable 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 can be received in the support portions of the first support member and the second support member, respectively, the support portion of the first support member being fitted with the first bearing in the rotational axis direction of the roller, and the support portion of the second support member having play with respect to the second bearing in the rotational axis direction of the roller. [Effects of the Invention]

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

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

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

[0014] [Example 1] 1. Overall configuration and operation of image forming apparatus First, the overall configuration and operation of the image forming apparatus of this embodiment will be described. Figure 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 laser beam printer that employs an intermediate transfer system 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 system.

[0015] Image forming apparatus 100 has four image forming stations PY, PM, PC, and PK that form images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. The four image forming stations PY, PM, PC, and PK are arranged side by side along the conveyance direction of the image transfer surface of intermediate transfer belt 7, which will be described later. Note that elements having the same or corresponding functions or configurations and provided for each color may be generally described by omitting the Y, M, C, or K suffixes to the reference numerals indicating that the element is provided for one of the colors. Figure 2 is a schematic cross-sectional view showing an enlarged view of the configuration of image forming station P. In this embodiment, the image forming station 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 a single unit that exposes the photosensitive drums 1Y, 1M, 1C, 1K of the four image forming stations PY, PM, PC, PK, but may be provided independently for each image forming station 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 face side)" and the back side of the paper in Fig. 1 is referred to as the "back side (rear face side)." The front-to-back direction (direction perpendicular to the paper in Fig. 1) connecting the front side and the back side is assumed to be approximately parallel to the rotation axis direction of the photosensitive drum 1 and the tension roller of the intermediate transfer belt 7. Furthermore, 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] Photosensitive drum 1, a drum-type photosensitive member (electrophotographic photosensitive member) serving as a first image carrier, is rotated in the direction of arrow R1 (clockwise) in the figure. The surface of the rotating photosensitive drum 1 is charged approximately uniformly to a predetermined potential of a predetermined polarity (negative in this embodiment) by a charging roller 2, a roller-type charging member serving as charging means. The charged surface of photosensitive drum 1 is scanned and exposed by an exposure device (laser scanner) 3 serving as 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 photosensitive drum 1. The electrostatic latent image formed on photosensitive drum 1 is developed (visualized) by a developing device 4 serving as developing means, which supplies toner as a developer, and a toner image (toner image, developer image) is formed on photosensitive drum 1.

[0018] An intermediate transfer belt 7, which is an intermediate transfer body formed of an endless belt and serves as a second image carrier, is disposed facing the four photosensitive drums 1Y, 1M, 1C, and 1K. The intermediate transfer belt 7 is stretched over and stretched with a predetermined tension around a plurality of tension rollers, including a secondary transfer inner roller 71, a tension roller 72, a primary transfer pre-roller 73, and a secondary transfer pre-roller 74. The intermediate transfer belt 7 rotates (circulates) in the direction of arrow R2 (counterclockwise) in the figure by the rotation of the secondary transfer inner roller 71, which also serves as a drive roller. Primary transfer rollers 5Y, 5M, 5C, and 5K, which are roller-type primary transfer members serving as primary transfer means, are disposed on the inner circumferential surface of the intermediate transfer belt 7, corresponding to 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) at the contact point 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 and an electrical bias applied by the primary transfer roller 5. During primary transfer, a primary transfer voltage (primary transfer bias) of a polarity opposite to the normal charging polarity of the toner during development (positive polarity in this embodiment) is applied to the primary transfer roller 5. For example, when forming a full-color image, the toner images of the YMCK colors formed on each photosensitive drum 1 are sequentially transferred onto the intermediate transfer belt 7 at each primary transfer portion T1 so as to be superimposed on top of each other.

[0019] On the outer peripheral surface 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. In other words, 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. At the secondary transfer portion T2, 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 and electrical bias applied by the secondary transfer outer roller 200. During 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 outer secondary transfer roller 200. The inner secondary transfer 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 inner secondary transfer roller 71, and the outer secondary transfer 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 member such as a feeding roller 12, and are conveyed to a conveying member such as a registration roller 13. 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 serving as a fixing means. The fixing device 14 applies heat and pressure to the recording material S bearing 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 serving as a conveying member. The recording materials S discharged from the device main body 110 are 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 step (primary transfer residual toner) is removed from the photosensitive drum 1 and collected by a drum cleaning device 6 serving as photosensitive body cleaning means. Furthermore, a belt cleaning device 75 serving as intermediate transfer body cleaning means is disposed on the outer circumferential surface side of the intermediate transfer belt 7 at a position facing the tension roller 72. Adherents such as toner remaining on the intermediate transfer belt 7 after the secondary transfer step (secondary transfer residual toner) are removed from the intermediate transfer belt 7 by the belt cleaning device 75 and collected.

[0023] In this embodiment, in each image forming station 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 mounted to the apparatus main body 110 as a unit.

[0024] The intermediate transfer belt 7, the plurality of tension rollers 71 to 74 that tension the intermediate transfer belt 7, 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 the apparatus main body 110 as a whole. The apparatus main body 110 of the image forming apparatus 100 is 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 The image forming apparatus 100 of this embodiment is provided with a cover 10 as an openable / closable member on the right side when viewed from the front. This is for clearing a jam of the recording material S that occurs in the conveyance 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 the 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) that connects the frame of the image forming apparatus 100 and the cover 10, and is designed to stop at a predetermined position when opened. The cover 10 can be opened and closed by a user, service technician, or other worker (operator) operating a handle (not shown) provided on the cover 10.

[0027] In this embodiment, a secondary transfer unit 220 serving as a support device for supporting the outer secondary transfer roller 200 is attached to the cover 10. As shown in FIG. 1, when the cover 10 is closed, the secondary transfer unit 220 is sandwiched between the cover 10 and members inside the device main body 110 and positioned at a predetermined position. In this embodiment, the secondary transfer unit 220 is positioned at a predetermined position by being positioned by members inside the device main body 110. In this state, the outer secondary transfer roller 200 is pressed against the surface (outer peripheral surface) of the intermediate transfer belt 7, which is a second image carrier and serves as a contact member wrapped around the inner secondary transfer roller 71, and becomes operable (capable of forming an image). Then, as shown in FIG. 3, when the cover 10 is opened, the secondary transfer unit 220 (outer secondary transfer roller 200) moves together with the cover 10 in a direction away from the intermediate transfer belt 7 (inner secondary transfer roller 71), allowing an operator to access the secondary transfer unit 220. 3, when the cover 10 is open, the secondary transfer unit 220 exposes the outer secondary transfer roller 200 upward and exposes at least a portion of each of its side surfaces in the front-to-rear direction to the front and rear, respectively. Note that when the outer secondary transfer roller 200 is supported by the secondary transfer unit 220 and attached to the cover 10, the rotational axis direction (rotational axis direction) of the outer secondary transfer roller 200 is approximately parallel to the front-to-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 fixed thereto, which will be described later) in this embodiment.

[0029] The outer secondary transfer roller 200 has a roller portion 201 formed of an elastic material that forms an elastic layer (a foamed elastic layer in this embodiment), and a shaft portion 202 that forms a core metal portion. In this embodiment, the roller portion 201 is made of a sponge (foamed elastic material) formed of NBR rubber or EPDM rubber containing a conductive agent such as a metal complex or carbon. In this embodiment, the shaft portion 202 is made of metal. The shaft portion 202 protrudes from the roller portion 201 at both ends in the rotational axis direction of the outer secondary transfer roller 200. In this embodiment, the outer secondary transfer roller 200 is formed so that the outer diameter of the roller portion 201 is 24 mm, and the thickness of the roller portion 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 portions 202 at both ends of the outer secondary transfer roller 200 in the axial direction. In this embodiment, ball bearings are used as the bearings 203. However, this is not limiting, and for example, ball bearings and roller bearings, which are typically rolling bearings, can be preferably used. The bearings 203 may have a general structure, including an outer ring, an inner ring, and rolling elements (balls in this embodiment) disposed between them (and may further include a cage that holds the rolling elements between the outer and inner rings). The bearings 203 have sufficient conductivity to contact a pressing member (moving member) 216, which functions as an electrical connection portion (described later), and connect the outer secondary transfer roller 200 to a power supply path (current path). In this embodiment, the outer ring, inner ring, and balls of the bearing 203 are each made of metal and have sufficient conductivity. In this embodiment, the bearings 200 at both ends of the outer secondary transfer roller 200 in the axial direction have substantially the same configuration.

[0031] Here, the bearing 203 is press-fitted and fixed onto the shaft portion 202. Before the bearing 203 is press-fitted, the outer diameter of the shaft portion 202 is slightly larger than the inner diameter of the inner ring of the bearing 203. This 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 the 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 and power supply configuration of the outer secondary transfer roller 200 in this embodiment will be described. FIG. 5 is a perspective view of the outer secondary transfer roller unit 210 in this embodiment. In FIG. 5, the rear side of the outer secondary transfer roller 200 in the rotational axis direction is shown on the left side of the page. FIG. 6 is a perspective view showing the pressure and power supply configuration of the outer secondary transfer roller 200 in this embodiment. FIG. 6 shows the pressure and power supply configuration provided at the rear end of the outer secondary transfer roller 200 in the rotational axis direction, and the outer secondary transfer roller 200 is not shown. FIG. 7 is a cross-sectional view (showing a cross section substantially parallel to the rotational axis direction of the outer secondary transfer roller 200) showing the pressure and power supply configuration of the outer secondary transfer roller 200 at the rear end of the outer secondary transfer roller 200 in the rotational axis direction. FIG. 8 is a cross-sectional view (showing a cross section substantially parallel to the rotational axis direction of the outer secondary transfer roller 200) showing the pressure configuration of the outer secondary transfer roller 200 at the front end of the outer secondary transfer 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 from an electrically insulating resin. In this embodiment, the outer secondary transfer roller 200 (and the bearing 203 fixed thereto), the support member R211 (and a pressing member 216 held thereon, described later), and the support member F212 constitute a outer secondary transfer roller unit 210.

[0034] In this embodiment, the support members R211 and F212 are similar except for the differences described below (substantially oriented relative to a plane that passes through the center of the outer secondary transfer roller 200 in the direction of the rotation axis and is approximately perpendicular to the direction of the rotation axis of the outer secondary transfer roller 200). name As will be described later, the support member R211 and the support member F212 differ mainly in the configuration based on whether or not a pressing member 216 is provided, and the configuration for positioning the bearing 203.

[0035] First, referring to FIGS. 6 and 7, the pressure and power supply structure of the outer secondary transfer roller 200 at the rear end in the rotation axis direction of the outer secondary transfer roller 200 is shown. (power supply mechanism) The support member R211 is held by a secondary transfer guide 221 (FIG. 9) serving as a holding member, which will be described later, so as to be slidable along a predetermined direction. This predetermined direction is a direction toward the intermediate transfer belt 7 (secondary inner transfer roller 71) when the image forming apparatus 100 is in operation, and a direction opposite thereto. The support member R211 is pressed by a pressure member 217 along the predetermined direction in a direction toward the intermediate transfer belt 7 (secondary inner transfer roller 71) when the image forming apparatus 100 is in operation. In this embodiment, the pressure member 217 is configured as a compression coil spring made of 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] The support member R211 is provided with a support portion 213, and a bearing 203, which is press-fitted and fixed onto 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 approximately perpendicular to the rotational 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 has an opening 213a that opens upward in Fig. 6 so that the bearing 203 can be received in the 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 direction in which the pressure member 217 applies pressure to the outer secondary transfer roller 200. The pressing member 216 is slidably housed 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, which 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 of the support member R211, which can come into contact with the outer periphery of the bearing 203. The bearing abutment portion 211b of the support member R211 and the bearing abutment portion 216b of the pressing member 216 may each be flat, curved (arc-shaped or U-shaped) along the outer periphery of the bearing 203, ribbed, 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 also be made of other conductive materials such as metal. The pressing member 216 is pressed by the pressing member 217 that presses the support member R211 described above. The pressing direction is the direction along the sliding direction of the support member R211, as described above, and is the direction toward the bearing 203 arranged in the support portion 213. That is, as described above, 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, 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 and presses the support member R211, and also contacts and presses the pressing member 216 toward the bearing 203, thereby contacting and pressing the pressing member 216 against the bearing 203. In this embodiment, as shown in FIG. 5, a power supply member 218 is provided in contact with the pressure member 217, and is supplied with a transfer current (transfer voltage) from a high-voltage power supply provided in the image forming apparatus 100. 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] When the cover 10 is open, that is, when the outer secondary transfer roller 200 is separated from the intermediate transfer belt 7, the pressing member 216 pressed by the pressing member 217 is locked by the support member R211. That is, the support 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. When 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 in the pressure direction of the pressing member 217 more than the bearing abutting portion 211b of the support member R211. In this state, at least a portion of the bearing abutting portion 216b of the pressing member 216 protrudes toward the bearing 203 by a protrusion amount W1 beyond the bearing abutting portion 211b of the support 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 until it is approximately 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 pressure application by 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 abuts against the intermediate transfer belt 7, the bearing 203 and the pressing member 216 can be brought into contact with each other more reliably. This ensures a more reliable electrical connection between the bearing 203 and the pressing member 216. Furthermore, the support member R211, which can be more robustly constructed than the pressing member 216 made of conductive resin, applies the pressing force of the pressing member 217 to the bearing 203, and the pressing force of the pressing member 217 can be used to press the pressing member 216 against the bearing 203. This makes it possible to more reliably achieve an electrical connection between the bearing 203 and the pressing member 216 with a simple configuration, and to more reliably apply a pressing force to the bearing 203 by the pressing member 217. Furthermore, with this configuration, the pressing member 216 is disposed within a region defined by the projection of the bearing 203 along the pressure 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 will touch the electrical connection portion for the secondary transfer outer roller 200 with the cover 10 open, causing the connection portion to become dirty or be damaged.

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

[0041] In this embodiment, the outer secondary transfer roller 200 is assembled to the support members R211 and F212 by translating the roller 200 in a predetermined direction so that the bearings 203 at both ends in the direction of the rotation axis are received by the support portions 213 of the support members R211 and F212 (substantially by this translational movement alone), thereby determining the position of the outer secondary transfer roller 200 in the direction of the rotation axis. In this embodiment, the support portions 213 of the support member R211 are configured to fit with the bearings 203 in the direction of the rotation axis of the outer secondary transfer roller 200. Meanwhile, the support portions 213 of the support member F are configured to have play with respect to the bearings 203 in the direction of the rotation axis of the outer secondary transfer 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 rotational axis direction of the outer secondary transfer roller 200 is set to be approximately the same as the width W3 of the bearing 203, creating a fit-fit relationship. This determines the position of the outer secondary transfer roller 200 in the rotational axis direction, to which the bearing 203 is fixed, 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 rotational axis direction of the outer secondary transfer roller 200 is set to be larger than the width W3 of the bearing 203, creating a relationship with play. This allows the outer secondary transfer roller 200 to be assembled to the support members R211 and F212 even if there is variation in the length of the outer secondary transfer roller 200 in the rotational axis direction (the length between the pair of bearings 203). 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] As described above, 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 of the outer secondary transfer roller 200 in the direction of its rotation axis, and is pressed toward the secondary transfer belt 7. In addition, 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, which constitutes an electrical contact point for 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, wear on the pressing member 216 made of conductive resin can be reduced (substantially eliminated) compared to a configuration in which a bearing made of conductive resin directly contacts the roller shaft.

[0043] The support members R211 and F212 are further provided with roller stoppers 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 of the outer secondary transfer roller 200 in the rotational axis direction is shown on the left side of the page. FIG. 10 is a front view of the secondary transfer unit 220 at one end side of the outer secondary transfer roller 200. FIG. 10 shows the vicinity of the front end of the outer secondary transfer roller 200 in the rotational axis direction, and the secondary transfer guide 221 is not shown. Here, as shown in FIGS. 9 and 10, the rotational axis direction of the outer secondary transfer roller 200 is the A1 direction, the insertion / removal direction of the outer secondary transfer roller 200 in the secondary transfer unit 220 is the A2 direction (the installation direction is the + (plus) direction), and the direction perpendicular to the A1 and A2 directions 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 slidably hold the support member R211 and the support member F212, respectively. Between the support member holding portions 221b, 221b at both ends, an accommodation portion 221c is formed to accommodate the secondary transfer outer roller 200 supported by the support member R211 and the support member F212. In the A1 direction, a gap X1 between the support portions 213 of the support member R211 and the support member F212 corresponds to the area of ​​the accommodation portion 222b. Furthermore, bearings 203 press-fitted and fixed to the secondary transfer outer roller 200 are attached to the support portions 213 of the support member R211 and the support member F212, thereby positioning the secondary transfer outer roller 200 in the A1 direction. The outer secondary transfer roller 200 is also positioned in the A3 direction by the fitting relationship between the bearing 203 and the support portions 213 of the support members R211 and F212.

[0048] 10, roller retaining portions 214 are formed integrally with the support member R211 and the support member F212. The roller retaining portions 214 are provided on both sides of a plane that is approximately 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 on both sides (1st part, 2nd part)214 is flexible so that it can bend away from the above-mentioned surface. Also, between the roller retaining portions 214 on both sides, an opening 214a is provided above 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, with respect to 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 does not 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 bend outward along the A3 direction away from each other 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 each 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 operator grips the shaft portion 202 of the secondary transfer outer roller 200 and lifts the secondary transfer outer roller 200 (and the bearing 203 fixed thereto) along the insertion / removal direction of the secondary transfer outer roller 200 (-A2 direction). Then, the shaft portion 202 of the secondary transfer outer roller 200 bends the roller retaining portion 214, and the secondary transfer outer roller 200 comes off the secondary transfer unit 220. In this way, the operation of removing the secondary transfer outer roller 200 from the apparatus main body 110 (secondary transfer unit 200) is completed.

[0051] Next, in the reverse order of the removal procedure described above, a replacement outer secondary transfer roller 200 (and the bearing 203 fixed thereto), which is usually a new outer secondary transfer roller 200, is attached to the secondary transfer unit 220. While gripping the shaft portion 202 of the outer secondary transfer roller 200, the worker presses the outer secondary transfer roller 200 for replacement so that the bearing 203 fits into the support portion 213 of the secondary transfer unit 220, thereby bending the roller retaining portion 214. In this way, the outer secondary transfer 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, 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] As described above, according to the configuration of this embodiment, the bearing 203 is press-fitted into the shaft portion 202 and therefore does not move or fall off when replacing the outer secondary transfer roller 200. This reduces the risk of parts becoming difficult to place in their predetermined positions or falling off during the replacement of the outer secondary transfer roller 200, improving the workability of replacing the outer secondary transfer roller 200. Also, in this embodiment, the function of the roller retaining portion 214 is provided on the support member R211 and the support member F212, i.e., on the device main body 110 (secondary transfer unit 200) side. This allows the configuration of the outer secondary transfer roller 200 to be replaced to be minimized, thereby reducing 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 any other roller that is replaced in the image forming apparatus. Furthermore, the roller may be a roller that is driven to rotate, or a roller that is driven to rotate.

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

[0056] In this embodiment, the pressure member 217 constitutes the power supply path to the pressing member 216. This allows, as described above, 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. 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 has an image carrier (intermediate transfer belt) 7 that carries a toner image, a rotatable roller 200 that has a shaft portion 202 protruding from one end and the other end in the direction of its rotation axis and that can abut against the image carrier 7 (secondary transfer outer roller), a first bearing 203 attached to the shaft portion 202 at the one end, a second bearing 203 attached to the shaft 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 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 predetermined direction. In this embodiment, the support portion 213 of the first support member 211 is fitted 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 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 itself and the image carrier 7 and transfers toner from the image carrier 7 to the recording material S.

[0058] Furthermore, according to this embodiment, the parts attached to the rollers do not move in the axial direction, so that rollers can be replaced appropriately and easily. [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 Member 218 Power supply member 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 the 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 rotational axis direction of the roller when the roller is supported by the first support member and the second support member, and retaining portions that restrict movement of the roller in a direction in which the first bearing and the second bearing, respectively, come off the support portions along the predetermined direction, 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. An image forming apparatus as described in Claim 1, characterized in that the anti-slip portion of the first support member is formed integrally with the first support member, and the anti-slip portion of the second support member is formed integrally with the second support member.

3. The image forming device described in Claim 1, characterized in that the anti-slip portion has a first portion and a second portion each arranged opposite the shaft portion so that an opening is formed upstream in the mounting direction of the roller, the width of the opening is narrower than the diameter of the shaft portion, and the first portion and the second portion are each configured to be able to deflect when the roller is mounted.

4. An image forming apparatus as described in Claim 1, characterized in that the anti-slip portion of the first support member is positioned outward from the first bearing in the direction of the rotational axis of the roller, and the anti-slip portion of the second support member is positioned outward from the second bearing in the direction of the rotational axis of the roller.

5. An image carrier that carries a toner image; a rotatable roller having a shaft portion protruding from one end and the other end in the 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 rotational 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, the support portion of the first support member engages with the first bearing in the direction of the rotation axis of the roller, and the support portion of the second support member has play with respect to the second bearing in the direction of the rotation axis of the roller.

6. An image forming apparatus as described in claim 5, further comprising a power supply mechanism for supplying power to the roller, the power supply mechanism being configured to supply power only from one end side of the roller in the direction of the rotation axis of the roller, the power supply mechanism comprising a pressing member that is pressurized toward the first bearing and abuts against the first bearing to form a power supply path to the roller, and the first support member comprising a holding portion that movably holds the pressing member.

7. An image forming apparatus as described in Claim 6, characterized in that the pressing member is configured to be able to protrude and retract toward the first bearing from an opening provided in the first support member.

8. An image forming apparatus as described in Claim 6, characterized in that the pressing member and the first support member are each made of resin, the pressing member being formed of a conductive first resin, and the first support member being formed of a second resin different from the first resin.

9. 9. The image forming apparatus according to claim 1, wherein the roller rotates while being pressed against the image carrier.

10. 9. The image forming apparatus according to claim 1, wherein the roller constitutes a current path for the image carrier.

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

Images