Image formation device

Abstract

To improve the handleability of a transfer roller in replacement work.SOLUTION: An image formation device 100 comprises: a roller 200 including a grip part 203 provided at an outer end of a shaft 202 in a rotation axis direction; a support part 302 rotatably supporting the shaft 202 inside the roller 200 in rotation axis direction from the grip part 203; and a holding member 301 supporting the support part 302, and including a side wall surface 311 adjacent to the grip part 203 outside the roller 200 in the rotation axis direction from the support part 302. The roller 200 is attachable and detachable to and from the support part 302, and in the rotation axis direction of the roller 200, the side wall surface 311 of the holding member 301 is positioned inward of the outer end face of the support part 302.SELECTED DRAWING: Figure 13

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] 2. Description of the Related Art Conventionally, in image forming apparatuses, some rollers are replaced before the end of the life of the image forming apparatus body due to deterioration of the roller's functionality, such as its ability to transport recording materials, caused by wear on the roller surface or adhesion of paper dust.

[0003] One example is a transfer roller that can be detachably attached to the image forming apparatus. In image forming apparatuses, such as electrophotographic copiers, a toner image formed on an image carrier, such as a photoreceptor or intermediate transfer member, is transferred to a recording material by applying a transfer bias to the transfer roller. This transfer roller typically includes an elastic layer with an ionic conductive agent dispersed therein to provide electrical conductivity. When power is supplied to such a transfer roller from its shaft, the flow of electricity is unidirectional, from the center of the shaft to the outer periphery of the roller. Repeated energization can result in uneven distribution of the ionic conductive agent, increasing the transfer roller's electrical resistance. In this case, to obtain the desired transfer current, the voltage applied to the transfer roller is increased as the transfer roller's electrical resistance increases. However, it may be necessary to replace the transfer roller with a new one before the applied voltage reaches the upper limit determined by the capacity of the high-voltage substrate.

[0004] The replacement of the transfer roller has generally been performed by a specialized service technician who is familiar with the task, and is rarely performed by general users who are unfamiliar with the procedure. Therefore, the ease of handling the transfer roller during the replacement process has not been emphasized. However, in recent years, there has been a trend toward making the transfer roller replaceable by general users in order to reduce costs, etc. Therefore, there is a need to improve the ease of the replacement process so that even general users can properly and easily replace the transfer roller.

[0005] Patent Document 1 discloses the following configuration that enables replacement of the secondary transfer roller. An attachment part with a pair of gripping parts is attached to the end of the secondary transfer roller in the direction of its rotation axis. When the pair of gripping parts are gripped, a flexible part on the attachment part bends, thereby disengaging a protrusion on the attachment part from a claw part on the maintenance door. In this state, the secondary transfer roller can be lifted upward to remove it from the maintenance door. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-200399 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the configuration of the above-mentioned prior art is relatively complicated, and in order to improve the ease of attachment and detachment, the grip portion needs to be large, which may result in an increase in the size of the image forming apparatus.

[0008] In order to make it possible to attach and detach the transfer roller with a relatively simple configuration, it is conceivable to configure the transfer roller to be attached and detached by operating the shaft portion at the end of the transfer roller in the direction of the rotation axis. However, in the past, the configuration around the shaft portion at the end of the transfer roller in the direction of the rotation axis was not configured with an emphasis on ease of handling the transfer roller during replacement work.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the ease of handling of a transfer roller during replacement work with a simple configuration. [Means for solving the problem]

[0010] The above object can be achieved by the image forming apparatus according to the present invention. In summary, the present invention provides an image forming apparatus comprising: a rotatable roller for conveying a sheet, the roller having a shaft portion at an end in the direction of a rotation axis of the roller that protrudes outward in the direction of the rotation axis of the roller, and a gripping portion at an outer end of the shaft portion in the direction of the rotation axis of the roller, a support portion that rotatably supports the shaft portion on an inner side of the gripping portion in the direction of the rotation axis of the roller, and a holding member that holds the support portion, the holding member having a side wall surface that is adjacent to the gripping portion and on an outer side of the support portion in the direction of the rotation axis of the roller, the roller being detachable from the support portion, and the side wall surface of the holding member being located on an inner side of the outer end surface of the support portion in the direction of the rotation axis of the roller. [Effects of the Invention]

[0011] According to the present invention, the handling of the transfer roller during replacement can be improved with a simple configuration. [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. [Figure 5] FIG. [Figure 6] FIG. 2 is a perspective view of the secondary transfer unit with the outer secondary transfer roller removed. [Figure 7] FIG. 4 is a cross-sectional view showing a configuration in the vicinity of an end portion of the outer secondary transfer roller. [Figure 8] FIG. [Figure 9] FIG. 2 is a perspective view showing a configuration in the vicinity of a support member. [Figure 10] FIG. 2 is a top view showing the configuration in the vicinity of the support member. [Figure 11] FIG. 4 is a cross-sectional view showing a configuration in the vicinity of a support member. [Figure 12] FIG. 2 is a side view showing the configuration in the vicinity of the grip portion. [Figure 13] 10 is a cross-sectional view showing the vicinity of a grip portion when the outer secondary transfer roller is replaced; FIG. 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" refer to up and down in the direction of gravity (vertical direction), but do not mean only directly above and directly below, but also include above and below a horizontal plane passing through a reference position or element.

[0017] Photosensitive drum 1, a drum-type (cylindrical) 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 uniformly charged 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 tension rollers 72-74 and each primary transfer roller 5, except for the inner secondary transfer roller 71, are driven to rotate with the rotation of the intermediate transfer belt 7. At the primary transfer portion T1, the toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the rotating intermediate transfer belt 7 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 a full-color image is formed, the toner images of the respective colors YMCK formed on the respective photosensitive drums 1 are sequentially transferred onto the intermediate transfer belt 7 at the respective primary transfer portions T1 so as to be superimposed on 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 inner secondary transfer roller 71 serving as an opposing roller. The outer secondary transfer roller 200 is pressed against the inner secondary transfer 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 outer secondary transfer roller 200. In other words, the inner secondary transfer roller 71 and the outer secondary transfer roller 200 sandwich the intermediate transfer belt 7 therebetween, thereby forming the secondary transfer portion T2. ​​In this embodiment, the outer secondary transfer roller 200 is rotated in response to the rotation of the intermediate transfer belt 7. However, the outer secondary transfer roller 200 may be configured to be driven to rotate by a driving force transmitted from a driving source. The toner image formed on the intermediate transfer belt 7 is transferred (secondary transfer) onto the recording material S, which is being conveyed while being sandwiched between the intermediate transfer belt 7 and the outer secondary transfer roller 200, at the secondary transfer portion T2 by the action of the pressure and electric bias applied by the outer secondary transfer roller 200. 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 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 jams of the recording material S that occur 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 sides, 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 rotation axis direction (axial direction) of the outer secondary transfer roller 200 is approximately parallel to the front-to-rear direction.

[0028] 3. Secondary transfer outer roller Next, the configuration of the outer secondary transfer roller 200 as a roller member to be replaced (replacement roller member) in this embodiment will be described.

[0029] FIG. 4 is an external perspective view showing the outer secondary transfer roller 200 in this embodiment. 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) made of NBR rubber, EPDM rubber, or the like that contains a conductive agent such as a metal complex or carbon. In this embodiment, the shaft portion 202 is made of a cylindrical member having a substantially circular cross section that is substantially perpendicular to its axial direction (longitudinal direction). In this embodiment, the shaft portion 202 is made of metal. The shaft portion 202 protrudes outward from the roller portion 201 at both ends of the outer secondary transfer roller 200 in the rotational axis direction. In addition, the outer secondary transfer roller 200 has gripping portions 203 at each end of the shaft portion 202 at both ends. As an example, the outer secondary transfer roller 200 is formed so that the outer diameter of the roller portion 201 is 24 mm, the thickness of the elastic layer (roller portion 201) is 6 mm, and the outer diameter of the portion of the shaft portion 202 around which the roller portion 201 is formed is 12 mm. However, the roller diameter, the thickness of the elastic layer, etc. are not limited to these.

[0030] FIG. 5 is a front view showing the outer secondary transfer roller 200 of this embodiment (the outer secondary transfer roller 200 is shown with its rotational axis aligned horizontally). The shaft portions 202 at both ends of the outer secondary transfer roller 200 are each composed of a first shaft portion 202a, a second shaft portion 202b, and a third shaft portion 202c. The first shaft portion 202a is a portion having an outer diameter substantially equal to the outer diameter of the portion of the shaft portion 202 around which the roller portion 201 is formed (the inner diameter of the roller portion 201). The second shaft portion 202b is a portion located adjacent to the outside of the first shaft portion 202a in the direction of the rotational axis of the outer secondary transfer roller 200, and has an outer diameter smaller than that of the first shaft portion 202a. The third shaft portion 202c is located adjacent to the outside of the second shaft portion 202b in the direction of the rotation axis of the outer secondary transfer roller 200, and has an outer diameter smaller than that of the second shaft portion 202b. In this embodiment, the second shaft portion 202b of the outer secondary transfer roller 200 contacts a bearing portion 321 of a support member 302 (described later), and the outer secondary transfer roller 200 is rotatably supported by a secondary transfer guide 301 (described later) via the support member 302. The second shaft portion 202b is manufactured with high precision, with a surface roughness of approximately Ra 0.8 μm, to enhance slidability.

[0031] The gripping portion 203 has a generally cylindrical (or columnar) shape that is generally symmetrical with respect to a cross section passing through the rotation axis of the outer secondary transfer roller 200. That is, the gripping portion 203 has a generally cylindrical (or columnar) shape that is generally concentric with the shaft portion 202. The gripping portion 203 may be formed integrally with the shaft portion 202 or may be separate from the shaft portion 202. When the gripping portion 203 is separate from the shaft portion 202, the gripping portion 203 is formed of, for example, resin and fixed to the outer end of the shaft portion third portion 202c in the direction of the rotation axis of the outer secondary transfer roller 200. In this case, the gripping portion 203 is fixed by, for example, lightly press-fitting the shaft portion third portion 202c from the outside. However, the method is not limited thereto, and the gripping portion 203 can be fixed to the shaft portion 202 by any fixing means such as adhesive, welding, or engagement (a combination of different means may be used).

[0032] In this embodiment, the diameter (maximum outer diameter) of the gripping portion 203 is larger than the diameter (outer diameter) of the shaft third portion 202c. In this embodiment, the diameter (outer diameter) of the gripping portion 203 is larger than the diameter (outer diameter) of the shaft second portion 202b and is equal to (substantially the same as, or slightly larger or smaller than) the diameter (outer diameter) of the shaft first portion 202a. By making the outer dimensions of the gripping portions 203 located at both ends of the outer secondary transfer roller 200 in the rotational axis direction relatively large, an operator can easily grasp the gripping portions 203 during replacement of the outer secondary transfer roller 200. This improves the ease of handling of the outer secondary transfer roller 200 during replacement. However, according to this embodiment, as will be described later, the gripping portions 203 can be easily grasped by an operator without being too large. In addition, a knurled shape (for example, multiple grooves extending along the rotational axis of the secondary transfer outer roller 200 formed at intervals along the circumferential direction of the gripping portion 203) may be formed on the outer peripheral surface of the gripping portion 203 in order to improve the handleability of the secondary transfer outer roller 200.

[0033] Furthermore, in this embodiment, the grip portion 203 is colored in a designated color (for example, orange) that indicates the part that the worker will operate, making it easy for the worker to identify at a glance which part of the outer secondary transfer roller 200 the grip portion 203 is. This prevents the worker from accidentally holding and operating another part of the outer secondary transfer roller 200. In other words, it is expected to have the effect of preventing a decrease in the conveyance performance of the outer secondary transfer roller 200 for the recording material S and a deterioration in print quality, which are caused by dirt such as oil from the worker's hands adhering to the surface of the roller portion 201.

[0034] 4. Secondary transfer unit Next, the configuration of the secondary transfer unit 220 in this embodiment will be described. FIG. 6 is an external perspective view showing the secondary transfer unit 220 in this embodiment. FIG. 6 shows the secondary transfer unit 220 (i.e., the secondary transfer unit main body 210) with the outer secondary transfer roller 200 removed. Also, in FIG. 6, the rear side of the secondary transfer unit 220 is shown on the left side of the drawing, and the front side is shown on the right side of the drawing. Regarding the secondary transfer unit 220 and its components, the direction of the rotation axis of the outer secondary transfer roller 200 is defined as the A1 direction, the direction of attachment / detachment (insertion / removal direction) of the outer secondary transfer roller 200 is defined as the A2 direction, and the direction perpendicular to the A1 and A2 directions is defined as the A3 direction. Regarding the A2 direction, the attachment direction of the outer secondary transfer roller 200 is defined as the + (plus) direction, and the removal direction of the outer secondary transfer roller 200 is defined as the - (minus) direction.

[0035] First, referring to FIG. 6, a schematic configuration of the secondary transfer unit 220 will be described. In this embodiment, the secondary transfer unit 220 includes a secondary transfer outer roller 200 and a secondary transfer unit main body 210 as a mounting portion to which the secondary transfer outer roller 200 is attached. The secondary transfer unit main body 210 includes a secondary transfer guide 301 as a holding member (frame), a support member 302 as a support portion that rotatably supports the secondary transfer outer roller 200, and a pressure member 303 that presses the support member 302. The support members (roller engagement portions) 302 are provided on both end sides in the A1 direction. Similarly, the pressure members 303 are provided on both end sides in the A1 direction. The support member 302 and the pressure member 303 are each held by the secondary transfer guide 301.

[0036] The secondary transfer guide 301 has a sheet guide portion 316 that guides the recording material (sheet) S conveyed from the upstream side of the conveyance path. The secondary transfer guide 301 is integrally formed of resin. The secondary transfer guide 301 also has holding portions 317 at both ends in the A1 direction that slidably hold the support members 302. Between the two holding portions 317 provided at both ends in the A1 direction, a storage portion 318 is formed to store the outer secondary transfer roller 200 supported by the support members 302. The area of ​​the gap X1 between the two support members 302 in the A1 direction constitutes the storage portion 318. The bearing portions 321 of the support members 302 fit into the ends of the second shaft portions 202b of the outer secondary transfer roller 200, respectively. This positions the outer secondary transfer roller 200 (in the A1 and A3 directions) and rotatably supports the outer secondary transfer roller 200 (in the A2 direction).

[0037] Next, the support configuration of the outer secondary transfer roller 200 by the support member 302 will be further described with reference to FIGS. 6 to 11. FIG. 7 is a cross-sectional view showing the configuration in the vicinity of one end (e.g., the front side) of the outer secondary transfer roller 200 in the A1 direction when the cover 10 is open (showing a cross section substantially perpendicular to the rotational axis direction of the outer secondary transfer roller 200). FIG. 8 is a perspective view of the support member 302 in the A1 direction (e.g., the front side). FIG. 9 is a perspective view showing the configuration in the vicinity of the front support member 302. FIG. 10 is a side view (top view) of the configuration in the vicinity of the front support member 302 as seen from above along the A2 direction. FIG. 11 is a cross-sectional view of the configuration in the vicinity of the front support member 302 as seen along the A3 direction (showing a cross section substantially parallel to the A2 direction passing through the rotational axis of the outer secondary transfer roller 200). In this embodiment, the support configuration of the outer secondary transfer roller 200 by the support members 302 on both end sides in the rotational axis direction of the outer secondary transfer roller 200 is similar (substantially symmetrical with respect to a plane passing through the center of the outer secondary transfer roller 200 in the rotational axis direction and approximately perpendicular to the rotational axis direction). Therefore, the following description will focus on the support configuration on one end side (mainly the front side).

[0038] As described above, the outer secondary transfer roller 200 is rotatably supported by support members 302 at both ends in the A1 direction. The support members 302 are integrally formed of resin. The support member 302 is held by the secondary transfer guide 301 so as to be slidable along a predetermined direction. This predetermined direction is the direction toward the intermediate transfer belt 7 (inner secondary transfer roller 71) serving as an opposing member during operation of the image forming apparatus 100, and the direction opposite thereto. The support member 302 is pressed by a pressure member 303 (FIG. 11) along the predetermined direction toward the intermediate transfer belt 7 (inner secondary transfer roller 71) serving as an opposing member during operation of the image forming apparatus 100. In this embodiment, the pressure member 303 is formed of a compression coil spring. The pressure member 303 is disposed between a receiving portion 326 (FIG. 11) provided on the support member 302 and a seat surface 319 (FIG. 11) provided on the secondary transfer guide 301.

[0039] 6 and 8, the support member 302 is provided with a bearing 321, and an end of the second shaft portion 202b of the outer secondary transfer roller 200 is attached to this bearing 321 from above. The attachment direction (attachment / detachment direction) of the outer secondary transfer roller 200 is a direction substantially perpendicular to the direction of the rotation axis of the outer secondary transfer roller 200 when the outer secondary transfer roller 200 is supported by the support member 302, and is a direction along the pressure direction of the pressure member 303. The bearing 321 is provided with an opening 321a that opens upward, i.e., on the upstream side in the attachment direction (+A2 direction) of the outer secondary transfer roller 200, so that the second shaft portion 202b can be received in the attachment direction.

[0040] Also, as shown in FIGS. 7 and 8, the support member 302 is provided with a roller retaining portion 322. The roller retaining portion 322 is provided on both sides of a plane substantially parallel to the A2 direction passing through the center of the shaft portion 202 of the secondary transfer outer roller 200 when viewed along the A1 direction, so as to face the third portion 202c of the shaft portion. The roller retaining portions 322 on both sides are flexible so that they can bend away from the above-mentioned plane. Further, a retaining opening 323 is provided between the roller retaining portions 322 on both sides, opening upward, that is, on the upstream side in the mounting direction (+A2 direction) of the secondary transfer outer roller 200. As shown in FIG. 7, regarding the A3 direction, if the width of the retaining opening 323 between the roller retaining portions 322 on both sides is X2 and the diameter (outer diameter) of the third portion 202c of the shaft portion is D1, the relationship is X2 < D1. That is, the secondary transfer outer roller 200 is configured not to move in the -A2 direction and come off the support member 302 unless the roller retaining portions 322 on both sides bend outward away from each other along the A3 direction under a predetermined load. Thus, the support member 302 has a roller retaining portion 322 provided outside the bearing portion 321 in the A1 direction, which restricts the shaft portion 202 from moving in the direction of coming off the support member 302 along the attachment / detachment direction of the secondary transfer outer roller 200. Thereby, the secondary transfer outer roller 200 attached to the secondary transfer unit main body 210 is suppressed from coming off the secondary transfer unit main body 210.

[0041] Furthermore, as shown in FIG. 8, the support member 302 is provided with a support member retaining portion 325. The secondary transfer unit 220 is configured to press the outer secondary transfer roller 200 against the intermediate transfer belt 7 (inner secondary transfer roller 71). That is, as shown in FIG. 11, a pressing force in the -A2 direction is generated by the pressure member 303 on the support member 302 that supports the outer secondary transfer roller 200. Therefore, when the cover 10 is open, the force of the pressure member 303 causes the support member 302 to tend to protrude from the secondary transfer guide 301. However, when the support member 302 is at a predetermined position relative to the secondary transfer guide 301, the support member retaining portion 325 engages with a locking portion (locking claw) 315 (FIG. 11) provided on the secondary transfer guide 301 and is locked by this locking claw 315. Therefore, the support member 302 does not protrude (fall off) from the secondary transfer guide 301.

[0042] The secondary transfer unit 220 is configured so that, when the secondary transfer outer roller 200 is supported by the support member 302, power is supplied to the shaft portion 202 of the secondary transfer outer roller 200 from a power supply portion provided in the device main body 110.

[0043] Next, the positional relationship between the support member 302 and the secondary transfer guide 301 will be described. As shown in FIGS. 9 to 11, the secondary transfer guide 301, which houses the support member 302, has an outer side wall surface 311 near the gripping portion 203 of the outer secondary transfer roller 200. The outer side wall surface 311 is formed of a plane that intersects with the A1 direction (substantially perpendicular in this embodiment) and is located near the gripping portion 203 of the outer secondary transfer roller 200. In this embodiment, this side wall surface 311 is located mainly below the gripping portion 203, i.e., downstream in the mounting direction (+A2 direction) of the outer secondary transfer roller 200, and a portion of it also extends to one side of the gripping portion 203 in the A3 direction (see FIG. 12). In this embodiment, the side wall surface 311 of the secondary transfer guide 301 is located inward in the A1 direction (toward the center in the direction of the rotation axis of the outer secondary transfer roller 200) by a distance X3 from an outer end surface 327 (the end surface located outwardly) of the support member 302. In this embodiment, the outer end surface 327 of the support member 302 in the A1 direction is formed by the outer side surface of the roller retaining portion 322 in the A1 direction. From the viewpoint of improving the ease with which an operator can grip the grip portion 203 with their fingers, it is desirable that the distance X3 be 2.5 mm or more. In other words, it is desirable that the side wall surface 311 be positioned 2.5 mm or more inward from the outer end surface of the support member 302 in the A1 direction. However, it is desirable that the distance X3 be 15 mm or less, and more desirably 10 mm or less. This is because it is undesirable to increase the size of the secondary transfer unit 200 by, for example, extending the shaft portion 202 toward the outside of the outer secondary transfer roller 200 in the A1 direction in order to ensure an unnecessarily large distance X3.

[0044] FIG. 12 is a side view of the configuration near the front gripping portion 203 as viewed from the front side along the A1 direction. As described above, the side wall surface 311 of the secondary transfer guide 301 near the gripping portion 203 is located inward in the A1 direction by a distance X3 from the outer end surface 327 of the support member 302. The range C1 (also referred to here as the "operation area") in which the side wall surface 311 of the secondary transfer guide 301 is located inward by the distance X is preferably as follows when viewed along the A1 direction (from the front side in FIG. 12): In the A3 direction, the distances between the gripping portion 203 and the ends of the operation area C1 on both sides of the gripping portion 203 are defined as distances X4 and X5, respectively. In this embodiment, distances X4 and X5 are the distances between the outer diameter of the gripping portion 203 and wall surfaces 312 and 313 extending outward in the A1 direction of the secondary transfer guide 301, respectively. Furthermore, in the A2 direction, the distance between the gripping portion 203 and the lower side of the gripping portion 203, i.e., the end of the operation area C1 downstream in the mounting direction (+A2 direction) of the outer secondary transfer roller 200, is defined as X6. In this embodiment, the distance X6 is the distance between the outer diameter of the gripping portion 203 and the wall surface 314 extending outward along the A1 direction of the secondary transfer guide 301. In this case, from the viewpoint of improving ease of gripping the gripping portion 203 when an operator grips it with their fingers, it is desirable that the distances X4 and X5 are each 8 mm or more. Similarly, from the viewpoint of improving ease of gripping the gripping portion 203 when an operator grips it with their fingers, it is desirable that the distance X6 be 10 mm or more. To improve the ease of operation when gripping the gripping portion 203 to attach or detach the outer secondary transfer roller 200, it is more important to improve the ease with which an operator can place their fingers on the gripping portion 203 in the attachment / detachment directions (+A2 direction, −A2 direction) of the outer secondary transfer roller 200. Therefore, it is preferable that the distance X6 be equal to or greater than the distance X4, and more preferably equal to or greater than the distance X5. From the viewpoint of improving the ease with which an operator can place their fingers when gripping the gripping portion 203, there are no particular upper limits to the distances X4, X5, and X6, but 30 mm or less is often sufficient for each, and typically 20 mm or less.In this embodiment, operation area C1, which is defined by distances X4, X5, and X6, is a substantially rectangular shape surrounded by straight lines (walls 312 and 313 extending substantially parallel to the A2 direction and wall 314 extending substantially perpendicular to the A2 direction). However, this is not limited to this, and operation area C1 may have a shape surrounded by a curve, as shown by dotted line D1 connecting three points whose maximum distances are distances X4, X5, and X6, respectively.

[0045] 8 and 11, in this embodiment, the support member 302 has a bottom 328 at a position facing the retaining opening 323 in the installation direction of the outer secondary transfer roller 200, across the area where the third shaft portion 202c is disposed. In this embodiment, in the A1 direction, an outer end face (the outermost end face) 324 of the bottom 328 is located inward (closer to the center in the rotational axis direction of the outer secondary transfer roller 200) from an outer end face (the outer end face of the roller retaining portion 322) 327 of the support member 302 by a distance X7. That is, in the A1 direction, the outer end face 324 of the bottom 328 between the two roller retaining portions 322 has a concave shape that is more recessed than the outer end faces 327 of the two roller retaining portions 322. From the viewpoint of improving the ease with which an operator can place their fingers when gripping the grip portion 203, it is desirable that the distance X7 be approximately the same as the distance X3. However, in consideration of the stability of the shape of the roller retaining portion 322, the distance X7 may be set to be smaller than the distance X3. For example, the distance X7 is set to be 2.0 mm or greater. Furthermore, the width in the A1 direction of the base portion 323a, which is the end portion of the roller retaining portion 322 that protrudes upward from the bottom portion 328 on the bottom portion 328 side, is set to be width X8. In this case, the distance X7 is preferably 50% or less of the distance X8, and more preferably 45% or less. For example, the outer end surface 327 of the support member 302, the outer end surface 324 of the bottom portion 328, and the side wall surface 311 of the secondary transfer guide 301 can be positioned inward in the A1 direction in this order.

[0046] 5.Replacing the outer secondary transfer roller Next, we will explain the procedure for replacing the outer secondary transfer roller 200. Figure 13 is a cross-sectional view of the vicinity of the front support member 302 as seen along the A3 direction, showing how an operator operates the grip portion 203 of the outer secondary transfer roller 200 (showing a cross section approximately parallel to the A2 direction passing through the rotation axis of the outer secondary transfer roller 200).

[0047] When replacing the outer secondary transfer roller 200, the worker first opens the cover 10 to expose the secondary transfer unit 220 upward, as shown in Fig. 3. At this time, the support member 302 is maintained in a state where it is held by the secondary transfer guide 221, as described above.

[0048] The worker grasps the gripping portion 203 of the outer secondary transfer roller 200 with fingers 401 and 402 and lifts it in the direction of removal of the outer secondary transfer roller 200 (the -A2 direction). At this time, typically, the worker applies force to the gripping portion 203 in the direction of removal of the outer secondary transfer roller 200 (the -A2 direction) with the lower finger 402 while pressing the upper end of the roller retaining portion 322 with the upper finger 401. This causes the third shaft portion 202c of the outer secondary transfer roller 200 to bend the roller retaining portion 322 of the support member 302, thereby releasing the outer secondary transfer roller 200 from the secondary transfer unit main body 210 (support member 302). In this way, the operation of removing the outer secondary transfer roller 200 from the device main body 110 (the secondary transfer unit main body 210) is completed.

[0049] Next, a replacement outer secondary transfer roller 200, which is typically a new outer secondary transfer roller 200, is attached to the secondary transfer unit main body 210 (support member 302) by reversing the procedure of the removal operation described above. While gripping the gripping portion 203 of the replacement outer secondary transfer roller 200, the worker presses the outer secondary transfer roller 200 against the support member 302 so that the second shaft portion 202b fits into the bearing portion 321 of the support member 302. This causes the third shaft portion 202c of the outer secondary transfer roller 200 to bend the roller retaining portion 322 of the support member 302, thereby attaching the outer secondary transfer roller 200 to the secondary transfer unit main body 210 (support member 302). That is, in this embodiment, the outer secondary transfer roller 200 can be attached to and detached from the support member 302 by translational movement along its attachment / detachment direction (substantially only by this translational movement).

[0050] Finally, the worker closes the cover 10, thereby completing the replacement of the outer secondary transfer roller 200.

[0051] Thus, according to this embodiment, when replacing the outer secondary transfer roller 200, the worker's fingers, particularly the lower finger 402, can reach deep into the gripping portion 203 of the outer secondary transfer roller 200 (toward the center in the direction of the rotation axis of the outer secondary transfer roller 200). This allows the worker to grip the gripping portion 203 with the pads of the fingers, and force can be firmly transmitted to the outer secondary transfer roller 200 in the attachment / detachment directions (+A2 direction, −A2 direction). As a result, the outer secondary transfer roller 200 can be attached and detached more easily than when the gripping portion 203 is gripped with the fingertips, improving the workability of replacing the outer secondary transfer roller 200. Furthermore, according to this embodiment, the gripping portion 203 can be easily gripped with a simple configuration, for example, without extending the shaft portion 202 toward the outside of the outer secondary transfer roller 200 in the A1 direction or enlarging the gripping portion 203. This prevents the secondary transfer unit 220 (image forming apparatus 100) from becoming larger.

[0052] As described above, in this embodiment, the image forming apparatus 100 includes a roller (secondary transfer outer roller) 200 that is a rotatable roller for conveying a sheet S, and that includes a shaft portion 202 that protrudes outward in the direction of the rotation axis of the roller at an end in the direction of the rotation axis of the roller, and a gripping portion 203 that is provided at an outer end of the shaft portion 202 in the direction of the rotation axis of the roller, and a roller (secondary transfer outer roller) 200 that is rotatable with respect to the gripping portion 203 in the direction of the rotation axis of the roller 200. The roller 200 has a support portion (support member) 302 that supports the roller 200, and a holding member (secondary transfer guide) 301 that holds the support portion 302 and has a side wall surface 311 that is adjacent to the grip portion 203 and is on the outer side of the support portion 302 in the rotational axis direction of the roller 200, the roller 200 is detachable from the support portion 302, and the side wall surface 311 of the holding member 301 is located on the inner side of the outer end surface 327 of the support portion 302 in the rotational axis direction of the roller 200. Here, it is preferable that the side wall surface 311 of the holding member 301 is located 2.5 mm or more on the inner side of the outer end surface 327 of the support portion 302 in the rotational axis direction of the roller 200. In this embodiment, the support portion 302 is a bearing portion that rotatably supports the shaft portion 202 and includes a bearing portion 321 that is provided with an opening 321a that receives the shaft portion 202 along the attachment / detachment direction A2 that intersects with the rotational axis direction of the roller 200, and the roller 200 can be attached to and detached from the support portion 302 by translational movement along the attachment / detachment direction A2. Here, it is preferable that the side wall surface 311 in a range that is 10 mm or more away from the gripping portion 203 in the attachment / detachment direction A2 is located more inward than the outer end surface 327 of the support portion 302 in the rotational axis direction of the roller 200. It is also preferable that the side wall surface 311 in a range that is 8 mm or more away from the gripping portion 203 in a direction approximately perpendicular to the attachment / detachment direction A2 is located more inward than the outer end surface 327 of the support portion 302 in the rotational axis direction of the roller 200.In this embodiment, the support portion 302 is a roller retaining portion that is provided outward of the bearing portion 321 in the rotational axis direction of the roller 200 and that restricts movement of the shaft portion 202 in a direction away from the support portion 302 along the attachment / detachment direction A2. The roller retaining portion 322 has a retaining opening 323 that receives the shaft portion 202 along the attachment / detachment direction A2, and a bottom portion 328 that is provided at a position facing the retaining opening 323 in the attachment / detachment direction. In this embodiment, an outer end face 324 of the bottom portion 328 is located inside an outer end face 327 of the roller retaining portion 322 in the rotational axis direction of the roller 200. Here, in this embodiment, the outer end face 327 of the roller retaining portion 322 in the rotational axis direction of the roller 200 constitutes the outer end face of the support portion 302 in the rotational axis direction of the roller 200. In this embodiment, the roller 200 rotates while being pressed against a rotatable opposing member (intermediate transfer belt) 7. In addition, in this embodiment, roller 200 is a transfer roller (secondary transfer outer roller) that sandwiches sheet S between itself and an image carrier (intermediate transfer belt) 7 that carries a toner image as the opposing member, and transfers the toner image from image carrier 7 to sheet S.

[0053] According to this embodiment, the outer secondary transfer roller 200 can be easily handled during replacement with a simple configuration.

[0054] [others] Although the present invention has been specifically described above with reference to the examples, the present invention is not limited to the above examples.

[0055] In the above-described embodiment, the roller member to be replaced is the secondary outer transfer roller 200, but this is not limited to this, and the roller member to be replaced may also be another conveying roller that conveys the recording material (sheet) S in the image forming device 100.

[0056] Furthermore, in the above-described embodiment, the roller member to be replaced was a driven roller, but this is not limited to this, and the roller member to be replaced may be a driven roller or a driven roller.

[0057] In the above-described embodiment, the outer secondary transfer roller 200 is rotatably supported by the sliding bearing of the support member 302, but this is not limiting. The roller member to be replaced may have its shaft portion rotatably supported by a support portion via a bearing (typically a rolling bearing such as a ball bearing or a roller bearing). [Explanation of symbols]

[0058] 100 Image forming device 200 Secondary transfer outer roller 201 Roller Section 202 Shaft 203 Gripping part 210 Secondary transfer unit body 220 Secondary transfer unit 301 Secondary Transfer Guide 302 Support member 303 Pressure Member 311 Side wall 321 Bearing section 322 Roller retaining part 327 Outer end face of support

Claims

1. a rotatable roller for conveying a sheet, the roller having a shaft portion at an end in a rotational axis direction of the roller that protrudes outward in the rotational axis direction of the roller, and a grip portion provided at an outer end of the shaft portion in the rotational axis direction of the roller; a support portion that rotatably supports the shaft portion on an inner side of the grip portion in the rotation axis direction of the roller; a holding member for holding the support portion, the holding member including a side wall surface adjacent to the grip portion and located outside the support portion in the rotation axis direction of the roller; and the roller is detachable from the support portion, 10. An image forming apparatus according to claim 9, wherein the side wall surface of the holding member is located more inward than the outer end surface of the support portion in the direction of the rotation axis of the roller.

2. 2. The image forming apparatus according to claim 1, wherein the side wall surface of the holding member is positioned 2.5 mm or more inward from the outer end surface of the support portion in the direction of the rotation axis of the roller.

3. the support portion is a bearing portion that rotatably supports the shaft portion, and has a bearing portion that is provided with an opening that receives the shaft portion along an attachment / detachment direction that intersects with the rotation axis direction of the roller, 2. The image forming apparatus according to claim 1, wherein the roller is detachable from the support portion by translational movement along the attachment / detachment direction.

4. 4. The image forming apparatus according to claim 3, wherein the side wall surface in the range of 10 mm or more away from the gripping portion in the attachment / detachment direction is located inside the outer end surface of the support portion in the direction of the rotation axis of the roller.

5. 4. The image forming apparatus according to claim 3, wherein the side wall surface in the range of 8 mm or more away from the gripping portion in a direction substantially perpendicular to the attachment / detachment direction is located inside the outer end surface of the support portion in the direction of the rotation axis of the roller.

6. the support portion is a roller retaining portion that is provided outward of the bearing portion in the direction of the rotation axis of the roller and that restricts movement of the shaft portion in a direction away from the support portion along the attachment / detachment direction, the roller retaining portion having a retaining opening that receives the shaft portion along the attachment / detachment direction, and a bottom portion that is provided at a position facing the retaining opening in the attachment / detachment direction, 4. The image forming apparatus according to claim 3, wherein an outer end face of the bottom portion is located more inward than an outer end face of the roller slip-off prevention portion in the direction of the rotation axis of the roller.

7. 7. The image forming apparatus according to claim 6, wherein an outer end surface of the roller retaining portion in the direction of the rotation axis of the roller constitutes an outer end surface of the support portion in the direction of the rotation axis of the roller.

8. 8. The image forming apparatus according to claim 1, wherein the roller rotates while being pressed against a rotatable opposing member.

9. 9. The image forming apparatus according to claim 8, wherein the roller is a transfer roller that sandwiches a sheet between itself and an image carrier that carries a toner image as the opposing member, and transfers the toner image from the image carrier to the sheet.

Images