JP2018004762A - Roller, cartridge and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roller capable of suppressing deterioration of cylindricity and total runout. SOLUTION: The roller is provided in a device main body of an image forming apparatus or a cartridge that can be attached to and detached from the device main body, and has a tubular shaft having a seam in which a pair of ends face or abut in the circumferential direction, and a tubular shaft. It comprises a tubular coating layer that covers the outer periphery of the tubular shaft, the seams are provided with concave-convex shaped portions, and the seams are formed from one end to the other end of the tubular shaft in the axial direction of the tubular shaft, and the device body or cartridge. In the roller in which the respective axes are in contact with each other in a non-parallel manner with respect to the photosensitive drum provided in the above, the tubular shaft is a facing surface that faces or abuts against each other forming the concave-convex shape portion of the seam. It has a facing surface that extends in a direction that is not parallel to the axial direction, the facing surface is inclined at a predetermined engagement angle with respect to the circumferential direction, and the generatrix of the peripheral surface of the coating layer is relative to the generatrix of the peripheral surface of the photosensitive drum. Cross at an intersection angle smaller than the engagement angle. [Selection diagram] Fig. 1

Description

  The present invention relates to a roller provided in an electrophotographic image forming apparatus.

  Various types of rollers are provided in electrophotographic image forming apparatuses (hereinafter, image forming apparatuses) such as copying machines, printers (LED printers, laser beam printers, etc.), facsimile machines, word processors, and the like. For example, in an image forming apparatus provided with a roller charging type voltage applying device, a conductive elastic roller (charging roller) is used as a charging member. In the roller charging method, the surface of the photosensitive drum is charged by biasing and contacting a conductive elastic roller to the photosensitive drum (image carrier) and applying a voltage thereto. The charging roller generally has a form in which the entire length of the peripheral surface of the metal shaft other than both ends is covered with an elastic layer (FIG. 2 (a) of Patent Document 1, paragraph 0022). In addition, there is a metal shaft of the charging roller in which a hollow metal shaft is provided with a concave and convex joint, and a predetermined engagement angle is formed on the side surface in the longitudinal direction of the joint (FIG. 21A of Patent Document 2). , Paragraph 0091). In addition, the charging roller may be disposed with a predetermined crossing angle with respect to the photosensitive drum in order to make the contact pressure to the photosensitive drum uniform and position in the longitudinal direction (FIG. 10, Patent Document 3). Paragraph 0008).

JP 2013-109209 A JP 2010-230748 A JP 2002-304103 A

  However, in a hollow metal shaft provided with an uneven joint, if the crossing angle between the charging roller and the photosensitive drum is larger than the engagement angle of the joint, the load due to contact with the photosensitive drum is non-parallel. It may be in a state of being concentrated on one end side of the part. In such a state, the cylindricity and total runout of the charging roller (the degree of runout of the entire roller peripheral surface when the charging roller is rotated) may be deteriorated.

  An object of the present invention is to provide a roller capable of suppressing deterioration of cylindricity and total runout.

In order to achieve the above object, the roller of the present invention comprises:
A roller provided in an apparatus main body of an image forming apparatus or a cartridge detachable from the apparatus main body,
A cylindrical shaft having a seam in which a pair of ends face or contact each other in the circumferential direction;
A cylindrical covering layer covering the outer periphery of the cylindrical shaft;
With
The seam includes an uneven portion, and the seam is formed from one end to the other end of the cylindrical shaft with respect to the axial direction of the cylindrical shaft, and is connected to the photosensitive drum provided in the apparatus main body or the cartridge. In the rollers where the respective axes are in contact with each other non-parallel,
The cylindrical shaft is an opposing surface that constitutes the concave-convex shape portion of the joint, and is opposed to or in contact with each other, and includes an opposing surface that extends in a direction not parallel to the axial direction, and the opposing surface is in a circumferential direction Inclined at a predetermined engagement angle,
The generatrix of the peripheral surface of the coating layer intersects the generatrix of the peripheral surface of the photosensitive drum at an intersection angle smaller than the engagement angle.
In order to achieve the above object, the cartridge of the present invention is
A cartridge that can be attached to and detached from the main body of the image forming apparatus,
The above-mentioned roller is provided.
In order to achieve the above object, the image forming apparatus of the present invention includes:
The above-mentioned roller is provided.

  According to the present invention, deterioration of cylindricity and total runout can be suppressed.

Explanatory drawing which shows the structure of the roller (charging roller) which concerns on Example 1 of this invention. Cross section of image forming apparatus Cross section of process cartridge Perspective view of image forming apparatus main body and process cartridge with open / close door open The perspective view explaining the structure of a process cartridge The perspective view explaining the structure of a cleaning unit The figure explaining the composition of a cleaning unit Explanatory drawing of the processing process of the roller which concerns on Example 1 of this invention. The front view of the joint part of the axial part of the roller which concerns on Example 1 of this invention

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. That is, it is not intended to limit the scope of the present invention to the following embodiments.

[Example 1]
The roller to which the present invention can be applied is, for example, a conductive roller for applying a voltage to an object to be charged such as an electrophotographic photosensitive member or a dielectric. The conductive roller is provided in a voltage applying device, a developing device, a developing cartridge, a process cartridge, and the like provided in the image forming apparatus. Another roller to which the present invention can be applied is, for example, a transport / discharge roller for transporting a recording medium (recording material) that is an image forming target.

  Here, the voltage application device is a device that has a conductive roller and applies a voltage to an object to be charged such as an electrophotographic photosensitive member or a dielectric by the conductive roller. The developing device is a device that has a developing roller and visualizes an electrostatic latent image (electrostatic image) formed on the electrophotographic photosensitive member (photosensitive drum) by the developing roller using a developer. is there. The developing cartridge is a cartridge in which the developing device is integrally formed and is detachably attached to the main body of the electrophotographic image forming apparatus. The process cartridge is a cartridge in which a photosensitive drum and a developing device acting on the photosensitive drum are integrally formed, and is detachably mounted on the image forming apparatus main body. The image forming apparatus forms an image on a recording material using an electrophotographic image forming system. Examples of the image forming apparatus include a copying machine, a printer (LED printer, laser beam printer, etc.), a facsimile machine, a word processor, and a multifunction machine (multifunction printer) thereof.

In the following description, the rotational axis direction of the photosensitive drum is the longitudinal direction. In the longitudinal direction, the side on which the photosensitive drum receives the driving force from the image forming apparatus main body is defined as a driving side (the driving force receiving portion 63a side in FIG. 6), and the opposite side is defined as the non-driving side.

  The overall configuration of the image forming apparatus and the image forming process will be described with reference to FIGS. FIG. 2 is a schematic cross-sectional view of an apparatus main body (hereinafter referred to as apparatus main body A) and a process cartridge (hereinafter referred to as cartridge B) of the image forming apparatus. FIG. 3 is a schematic cross-sectional view of the cartridge B. Here, the apparatus main body A of the image forming apparatus is an image forming apparatus portion excluding the cartridge B. FIG. 4 is a perspective view of the apparatus main body A and the process cartridge B. FIG.

(Overall configuration of image forming apparatus)
2 and 4, the electrophotographic image forming apparatus is a laser beam printer using an electrophotographic technique in which a cartridge B is detachable (detachable) from the apparatus main body A. FIG. 4 is a perspective view showing how the cartridge B is attached to and detached from the apparatus main body A, and shows a state where the open / close door 13 of the apparatus main body A is opened in order to attach and detach the cartridge B. An opening / closing door 13 is rotatably attached to the apparatus main body A. When the open / close door 13 is opened, a guide rail 12 is provided, and the cartridge B can be mounted in the apparatus main body A along the guide rail 12. Then, the drive shaft 14 driven by a motor (not shown) of the apparatus main body A engages with a driving force receiving portion 63a (FIG. 6) provided in the cartridge B. As a result, the drum 62 coupled to the driving force receiving portion 63a rotates by receiving the rotational driving force from the apparatus main body A. Further, the charging roller 66 and the developing roller 32 are supplied with power from a power supply unit (not shown) of the apparatus main body A.

  An exposure device 3 (laser scanner unit) is arranged above the cartridge B mounted on the apparatus main body A. Further, a sheet tray 4 that accommodates a recording medium (hereinafter referred to as a sheet material P) that is an image forming target is disposed below the cartridge B. Further, the apparatus main body A includes a pickup roller 5a, a feeding roller pair 5b, a conveyance roller pair 5c, a transfer guide 6, a transfer roller 7, a conveyance guide 8, a fixing device 9, along the conveyance direction D of the sheet material P. A pair of discharge rollers 10, a discharge tray 11, and the like are sequentially arranged. The fixing device 9 includes a heating roller 9a and a pressure roller 9b.

(Image formation process)
Next, an outline of the image forming process will be described. Based on the print start signal, the electrophotographic photosensitive drum (hereinafter referred to as drum 62) is rotationally driven in the direction of arrow R with a predetermined peripheral speed (process speed). The charging roller 66 to which the bias voltage is applied contacts the outer peripheral surface of the drum 62 and uniformly charges the outer peripheral surface of the drum 62. The exposure device 3 outputs a laser beam L corresponding to the image information. The laser beam L passes through the exposure window 74 on the upper surface of the cartridge B and scans and exposes the outer peripheral surface of the drum 62. As a result, an electrostatic latent image corresponding to the image information is formed on the outer peripheral surface of the drum 62.

  On the other hand, as shown in FIG. 3, in the developing device unit 20 as a developing device, the toner T in the toner chamber 29 is agitated and conveyed by the rotation of the conveying member 43 and sent out to the toner supply chamber 28. The toner T is carried on the surface of the developing roller 32 by the magnetic force of the magnet roller 34 (fixed magnet). While the toner T is frictionally charged by the developing blade 42, the layer thickness of the circumferential surface of the developing roller (developing sleeve) 32 is regulated. The toner T is transferred to the drum 62 in accordance with the electrostatic latent image, and is visualized as a toner image.

Further, as shown in FIG. 2, the sheet material P stored in the lower part of the apparatus main body A is moved to the sheet tray by the pickup roller 5a, the feeding roller pair 5b, and the conveying roller pair 5c in accordance with the output timing of the laser beam L. 4 is fed. Then, the sheet material P is supplied to the transfer position between the drum 62 and the transfer roller 7 via the transfer guide 6. At this transfer position, the toner image is transferred from the drum 62 to the sheet material P.

  The sheet material P to which the toner image has been transferred is separated from the drum 62 and conveyed to the fixing device 9 along the conveyance guide 8. The sheet material P passes through the nip portion between the heating roller 9a and the pressure roller 9b constituting the fixing device 9. A pressure / heat fixing process is performed in the nip portion, and the toner image is fixed on the sheet material P. The sheet material P that has undergone the toner image fixing process is conveyed to the discharge roller pair 10 and discharged to the discharge tray 11.

On the other hand, as shown in FIG. 3, the drum 62 after the transfer is used again in the image forming process after the residual toner on the outer peripheral surface is removed by the cleaning blade 77. The toner removed from the drum 62 is stored in the waste toner chamber 71 b of the cleaning unit 60.
In the above, the charging roller 66, the developing roller 32, and the cleaning blade 77 are process means that act on the drum 62.

(Configuration of the entire cartridge)
The overall configuration of the cartridge B will be described with reference to FIGS. FIG. 5 is an exploded perspective view illustrating the configuration of the cartridge B. FIG. The cartridge B is configured by combining the cleaning unit 60 and the developing device unit 20. The cleaning unit 60 includes a cleaning frame 71, a drum 62, a charging roller 66, a cleaning blade 77, and the like. On the other hand, the developing device unit 20 includes a bottom member 22, a developing container 23, a first side member 26L, a second side member 26R, a developing blade 42, a developing roller 32, a magnet roller 34, a conveying member 43, toner T, and an urging member. 46 etc. Here, the direction of the axis of rotation of the drum 62 or the developing roller 32 (the direction perpendicular to the paper surface in FIG. 3) is the longitudinal direction.

  The cleaning unit 60 and the developing device unit 20 are coupled to each other by a coupling member 75 so that the cartridge B can be rotated. Specifically, the developing roller 32 is provided at the ends of the arm portions 26aL and 26aR formed on the first side member 26L and the second side member 26R at both ends in the longitudinal direction of the developing device unit 20 (the axial direction of the developing roller 32). Rotation holes 26bL and 26bR are provided in parallel with each other. In addition, insertion holes 71 a for inserting the coupling members 75 are formed at both longitudinal ends of the cleaning frame 71. Then, the arm members 26aL and 26aR are aligned with predetermined positions of the cleaning frame 71, and the coupling member 75 is inserted into the rotation holes 26bL and 26bR and the fitting holes 71a. Thereby, the cleaning unit 60 and the developing device unit 20 are coupled so as to be rotatable around the coupling member 75.

  At this time, the urging member 46 attached to the base of the arm portions 26aL and 26aR hits the cleaning frame 71, and urges the developing device unit 20 to the cleaning unit 60 with the coupling member 75 as the rotation center. As a result, the developing roller 32 is reliably pressed in the direction of the drum 62. The developing roller 32 is held from the drum 62 at a predetermined interval by a spacing holding member (not shown) attached to both ends of the developing roller 32.

(Configuration of cleaning unit)
The configuration of the cleaning unit 60 will be described with reference to FIGS. FIG. 6 is a perspective view illustrating the configuration of the cleaning unit 60. FIG. 7A is a front view illustrating the configuration of the cleaning unit 60. FIG. 7B is a view taken along the arrow H of the support portion of the charging roller 66.

The cleaning blade 77 includes a support member 77a made of sheet metal and an elastic member 77b made of an elastic material such as urethane rubber. The both ends of the support member 77a are fixed with screws 91, so that the cleaning blade 77 has a predetermined position with respect to the cleaning frame 71. Placed in. The elastic member 77b is the drum 62.
The residual toner is removed from the outer peripheral surface of the drum 62. The removed toner is stored in a waste toner chamber 71b (FIG. 3) of the cleaning unit 60.

  The first seal member 82 (FIG. 3), the second seal member 83, the third seal member 84, and the fourth seal member 85 are fixed to predetermined positions of the cleaning frame 71 with double-sided tape or the like. The first seal member 82 (FIG. 3) is provided in the longitudinal direction and prevents waste toner from leaking from the back side of the support member 77a of the cleaning blade 77. The second seal member 83 prevents waste toner from leaking from the longitudinal ends of the elastic member 77 b of the cleaning blade 77. The third seal member 84 wipes off deposits such as toner on the drum 62 while preventing waste toner from leaking from both longitudinal ends of the elastic member 77b of the cleaning blade 77. The fourth seal member 85 is provided in contact with the drum 62 in the longitudinal direction, and prevents waste toner from leaking from the upstream side in the rotation direction of the drum 62 with respect to the cleaning blade 77.

  The electrode plate 81, the urging member 68, and the charging roller bearings 67L and 67R are attached to the cleaning frame 71. A metal shaft of the charging roller 66 (hereinafter referred to as a shaft portion 66a) is fitted into the charging roller bearings 67L and 67R. The charging roller 66 is urged against the drum 62 by an urging member 68 and is rotatably supported by charging roller bearings 67L and 67R. Then, driven rotation is performed as the drum 62 rotates.

  The charging roller 66 is configured by covering the entire length of the outer peripheral surface of the hollow shaft portion 66a other than both ends with a conductive elastic layer 66b as a coating layer of an elastic body. The elastic layer 66b and the shaft portion 66a are joined by an adhesive. The shaft portion 66a is formed by pressing a conductive metal sheet such as a stainless steel plate or a galvanized steel plate into a cylindrical shape by pressing. Here, the hollow press-worked shaft portion 66a is used to reduce the weight and cost of the cartridge and the image forming apparatus.

  The electrode plate 81, the urging member 68, the charging roller bearing 67L, and the shaft portion 66a are conductive. The electrode plate 81 is in contact with a power feeding unit (not shown) of the apparatus main body A. Power is supplied to the charging roller 66 using these as power supply paths.

  The drum 62 is integrally coupled with the flange 64 and the flange 63 to form an electrophotographic photosensitive drum unit (hereinafter referred to as a drum unit 61). This bonding method uses caulking, adhesion, welding, or the like. A ground contact or the like (not shown) is coupled to the flange 64. Further, the flange 63 includes a driving force receiving portion 63 a that receives a driving force from the apparatus main body A and a flange gear portion 63 b that transmits driving to the developing roller 32.

  The bearing member 76 is integrally fixed to the driving side of the cleaning frame 71 by screws 90, and the drum shaft 78 is press-fitted and fixed to the non-driving side of the cleaning frame 71. The bearing member 76 is fitted with the flange 63, and the drum shaft 78 is fitted with the hole 64 a of the flange 64. Thereby, the drum unit 61 is rotatably supported by the cleaning frame 71.

  The protection member 79 is rotatably supported by the cleaning frame 71 so that the drum 62 can be protected (light-shielded) and exposed. The urging member 80 is attached to the shaft portion 79 a R on the drive side of the protection member 79 and urges the protection member 79 in a direction to protect the drum 62. The shaft portion 79aL on the non-driving side and the shaft portion 79aR on the driving side of the protection member 79 are fitted to the bearing portions 71cL and 71cR of the cleaning frame 71.

(Charging roller configuration)
The configuration of the charging roller 66 will be described with reference to FIGS. 1, 8, and 9. FIG. 1 is an explanatory diagram of the charging roller 66 in this embodiment. FIG. 1A is a schematic top view for explaining a contact state between the charging roller 66 and the drum 62 in the present embodiment. FIG. 1B is a partial detail view showing the load distribution of the sheet metal joint 66c of the shaft portion 66a. FIG. 1C is a partial detail view showing the load distribution of the sheet metal joint 66c of the shaft portion 66a in the comparative example. FIG. 8 is a schematic cross-sectional view showing a process of processing the shaft portion 66a from the sheet metal into a cylindrical form in the present embodiment. 8 is a cross-sectional view of the metal sheet metal 66a1 when viewed in the direction (axial direction) C in which the axis line CL of the shaft portion 66a of the charging roller 66 shown in FIG. 9 extends. FIG. 9 is a front view of the sheet metal joint 66c of the shaft portion 66a in the present embodiment.

  As shown in FIG. 1A, the charging roller 66 in this embodiment is inclined with respect to the drum 62 so that the crossing angle θ is formed between the axis 66L and the axis 62L of the drum 62. It is arranged in contact with. Here, since the axis 66L of the charging roller 66 and the axis 62L of the drum 62 are in a torsional positional relationship, they do not actually intersect. In the description of the present embodiment, when the charging roller 66 and the drum 62 are viewed simultaneously from above the charging roller 66 as shown in FIG. 1A, the apparent crossing angle formed by the axis 66L and the axis 62L is the crossing angle. Let θ. This crossing angle θ can be regarded as the same as the crossing angle of the generatrix on each peripheral surface passing through the contact point between the charging roller 66 and the drum 62. Accordingly, in the following description, the crossing angle θ between the axes 66L and 62L will be referred to as the bus crossing angle θ as appropriate.

  By providing the crossing angle θ as described above, the contact pressure of the charging roller 66 with respect to the drum 62 is made uniform, and the charging roller 66 is aligned in the longitudinal direction. If the crossing angle θ is too large, the contact state between the charging roller 66 and the drum 62 becomes unstable. Therefore, it is preferable to set the crossing angle θ to 0.05 to 2.5 °. When the drum 62 rotates in the direction of arrow R, the charging roller 66 is driven to rotate in the direction of arrow S by receiving a driving force Q having an inclination of the crossing angle θ from the bus of the drum 62 via the bus of the charging roller 66. .

  As shown in FIG. 8, the shaft portion 66a (cylindrical shaft) of the charging roller 66 is a press-formed product. That is, the shaft portion 66a is formed by bending a metal plate (stainless steel plate, SUM22 + Ni plating, etc.) 66a1 having conductivity into a cylindrical body by pressing to reduce the weight and cost of the cartridge B and the apparatus main body A. Molded. When the metal sheet metal 66a1 is pressed, the sheet metal joint 66c of the metal sheet metal extends from one end (one end) to the other end (the other end) in the axial direction C in the axial direction of the shaft portion 66a. It is formed to exist (FIG. 9). That is, the shaft portion 66a has a substantially C-shaped cross section perpendicular to the axial direction C, and has a pair of end portions (end surfaces) that face or abut each other in the circumferential direction. A pair of ends facing each other in the circumferential direction form a seam 66c (sometimes referred to as a joint). Since the shaft portion 66a can be regarded as a configuration in which the cylindrical shape is separated by the joint 66c, the joint 66c may be referred to as a separation portion.

  Here, in this embodiment, the outer diameter of the shaft portion 66a is φ6 mm, and the total length in the axial direction C is 252.5 mm. However, the outer diameter and the total length necessary for the function may be appropriately selected.

  As shown in FIG. 9, in this embodiment, the seam 66c is not a shape that simply extends linearly in the axial direction C, but a shape in which a plurality of concave and convex portions 66c1 that mesh with each other in the circumferential direction are provided. An uneven portion extending in the axial direction is formed on each of the one end and the other end of the joint 66c of the shaft portion 66a, and the uneven portion is engaged with each other, so that the shaft portion 66a has a desired shape. Of strength. The greater the number of irregularities, the better the strength of the shaft portion 66a. However, the strength necessary for manufacturing and product functions may be selected as appropriate.

The concavo-convex portion 66c1 forming the concavo-convex portion at each of the one end and the other end of the joint 66c of the shaft portion 66a includes a plurality of corner portions 66c2, a plurality of recess bottoms 66c41, and a plurality of protrusion tips. The portion 66c42 and a plurality of side portions 66c5 are configured. The concave bottom 66c41 and the convex tip 66c42 are parallel portions that extend substantially parallel to the axial direction C, and the side surface 66c5 is a non-parallel portion that is not parallel to the axial direction C. The convex tip end portion 66c42 and the side surface portion 66c5 that are adjacent to each other, and the side surface portion 66c5 and the concave portion bottom portion 66c41 are connected by the corner portion 66c2. For example, in the axial direction C, the concave bottom 66c41, the corner corner 66c2, the side surface 66c5, the convex tip 66c42, the corner corner 66c2, the side surface 66c5, and the corner corner 66c2 are repeatedly arranged in this order, so that A portion 66c1 is formed.

  That is, the concave portion and the convex portion in the concavo-convex portion 66c1 share one side surface portion 66c5 and are alternately formed in the axial direction C. That is, the configuration formed by one recess bottom 66c41, two corners 66c2 at both ends thereof, and two side surfaces 66c5 connected to them can be regarded as a recess in the recess 66c1. In addition, the configuration formed by one convex portion distal end portion 66c42, two corner portions 66c2 at both ends thereof, and two side surface portions 66c5 connected to them can be regarded as the convex portion in the concave and convex portion 66c1.

  The concave-convex portion 66c1 has a symmetrical configuration in which the arrangement of the concave bottom portion 66c41 and the convex tip end portion 66c42 is changed in the axial direction C at one end and the other end of the joint 66c of the shaft 66a. . Thereby, in the joint 66c, the convex part of one end part engages with the concave part of the other end part, and the convex part of the other end part engages with the concave part of the one end part. That is, the convex tip end portion 66c42 constituting the convex portion at one end faces the concave portion bottom 66c41 constituting the concave portion at the other end in the circumferential direction. Similarly, the recess bottom 66c41 that forms the recess at one end faces the protrusion tip 66c42 that forms the protrusion at the other end in the circumferential direction.

  In addition, the side surface portion 66c5 of the concave portion at one end facing each other and the side surface portion 66c5 at the other end are opposed to each other in the circumferential direction and the direction inclined with respect to the axial direction C, as will be described in detail later. Each has a facing surface that extends (extends in a direction not parallel to the axial direction). The pair of side surface portions 66c5 forming the concave portion in the concave and convex portion 66c1 are inclined so that the opposed width in the axial direction C becomes narrower as the concave portion bottom portion 66c41 is closer. In addition, the pair of side surface portions 66c5 that form the convex portion in the concavo-convex portion 66c1 is inclined so that the opposing width in the axial direction C becomes narrower as it is closer to the convex portion tip end portion 66c42.

  In addition, linear portions 66c3 are provided up to the end in the axial direction C on both sides of the concavo-convex portion 66c1 in each of the one end and the other end of the joint 66c.

  In the axial direction C of the charging roller 66, the longitudinal width 66h of the linear portion 66c3 is a shaft support portion rotatably supported by the charging roller bearings 67L and 67R (FIG. 6). It is preferable from the viewpoint of preventing wear of the charging roller bearings 67L and 67R (FIG. 6) that the shaft support portion does not include the side surface portion 66c5 and the corner corner portion 66c2. For this reason, the longitudinal width 66h is provided longer than the longitudinal width 66g of the recessed portion leading end portion 66c41 or the protruding portion leading end portion 66c42, thereby securing the engaging width in the longitudinal direction of the shaft support portion. In this embodiment, the longitudinal width 66h of the straight line portion 66c3 is 16 mm, and the longitudinal width 66g of the recess tip portion 66c41 and the projection tip portion 66c42 is 10.5 mm. The specific dimension setting is not limited to this, and the longitudinal width 66h of the linear portion 66c3 is 4 to 30 mm, and the longitudinal width 66g of the concave portion tip portion 66c41 and the convex portion tip portion 66c42 is the longitudinal length of the linear portion 66c3. A desired dimension smaller than the width 66h may be set as appropriate.

The outer diameter of the shaft 66a is 6 mm and the inner diameter is 4.8 mm, but the outer diameter is 3 to 15 mm, and the inner diameter is appropriately set to a desired dimension obtained by subtracting the thickness (0.3 to 2 mm) of the metal plate 66a1 from the outer diameter. You can do it. Note that the inner diameter shape of the shaft portion 66a may not be circular if it is not necessary for the product function or manufacture. In addition, the engagement of the concavo-convex portion 66c1 of the sheet metal joint 66c is preferably formed without a gap from the viewpoint of strength, but a gap may be partially generated.

  As shown in FIG. 1B, a direction D (shaft portion 66c) perpendicular to the axial direction C of the shaft portion 66a is provided between the recess tip portion 66c41 or the protrusion tip portion 66c42 and the side surface portion 66c5 connected thereto. An engagement angle F that is inclined at a predetermined angle with respect to the circumferential direction of the outer periphery is provided. As shown in FIG. 1B, the engagement angle F is configured to satisfy the relationship of crossing angle θ <engagement angle F. In this embodiment, the engagement angle F is 3 °. In other words, the charging roller 66 according to the present embodiment is configured so that the bus bar on the circumferential surface of the elastic layer 66b intersects with the bus bar on the drum 62 circumferential surface at a crossing angle θ smaller than the engagement angle F. Are placed in contact with each other.

  By disposing the charging roller 66 in this manner, the load U (arrow in FIG. 1B) when the charging roller 66 receives the driving force Q when the drum 62 rotates is the bottom of the concave portion 66c41 or the convex portion of the joint 66c. Dispersed in the front end portion 66c42 and the side surface portions 66c5 on both sides thereof. Since the load U is distributed in this way, there is no influence caused by the concentration of the load locally, for example, the concentration of the load only on one of the side surfaces 66c5 (FIG. 1C). Deterioration of the cylindricity and total runout of the portion 66a is suppressed. As a result, the rotation unevenness of the charging roller 66 due to the rotation period of the shaft portion 66a can be reduced, and the charging unevenness and the like can be suppressed to ensure good image quality.

  On the other hand, as a comparative example in which the present invention is not carried out, a configuration satisfying the relationship of crossing angle θ ≧ engagement angle F is shown in FIG. In the configuration shown in FIG. 1C, the load of the shaft portion 66a that has received the driving force Q is concentrated on one side surface portion 66c5 of one concave portion or convex portion, and is long in one concave portion or convex portion. A non-uniform stress distribution may occur in the direction. As a result of the stress acting in a non-uniform manner in this way, the roundness of the peripheral surface of the shaft portion 66a is reduced, the cylindricality and the total runout of the charging roller 66 (the entire roller peripheral surface when the charging roller 66 is rotated). The degree of shake) will worsen. As a result, uneven rotation of the charging roller 66 and uneven charging due to the rotation period of the shaft portion 66a occur, which contributes to image defects.

  As described above, it is possible to provide a conductive roller capable of suppressing deterioration of cylindricity and total deflection, a process cartridge using the conductive roller, and an image forming apparatus by the configuration of this embodiment. In this embodiment, the conductive roller of the present invention is applied to the charging roller of the cartridge. However, the present invention is not limited to this and may be applied to the developing roller. When applied to the developing roller, the developing roller 32 can be stably rotated. Further, if the development is performed in a state where the developing roller 32 is in contact with the drum 62, a stable contact state can be maintained. Therefore, stable development can be performed and image defects can be suppressed. Further, it may be incorporated in an image forming apparatus main body that does not employ a cartridge system, and may be configured to be detachable from the cartridge or the apparatus main body in a minimum unit of only a conductive roller.

  62 ... Drum (electrophotographic photosensitive drum), 66 ... Charging roller, 66a ... Shaft (cylindrical shaft), 66b ... Elastic layer (covering layer), 66c ... Joint, 66c1 ... Uneven portion, 66c2 ... Corner corner, 66c3 ... straight line portion, 66c41 ... concave bottom portion (parallel portion), 66c42 ... convex tip end portion (parallel portion), 66c5 ... side surface portion (non-parallel portion), A ... image forming apparatus main body (apparatus main body), B ... process cartridge (Cartridge), C ... Charging roller axial direction

Claims (11)

A roller provided in an apparatus main body of an image forming apparatus or a cartridge detachable from the apparatus main body,
A cylindrical shaft having a seam in which a pair of ends face or contact each other in the circumferential direction;
A cylindrical covering layer covering the outer periphery of the cylindrical shaft;
With
The seam includes an uneven portion, and the seam is formed from one end to the other end of the cylindrical shaft with respect to the axial direction of the cylindrical shaft, and is connected to the photosensitive drum provided in the apparatus main body or the cartridge. In the rollers where the respective axes are in contact with each other non-parallel,
The cylindrical shaft is an opposing surface that constitutes the concave-convex shape portion of the joint, and is opposed to or in contact with each other, and includes an opposing surface that extends in a direction not parallel to the axial direction, and the opposing surface is in a circumferential direction Inclined at a predetermined engagement angle,
A roller characterized in that a generatrix of the peripheral surface of the coating layer intersects a generatrix of the peripheral surface of the photosensitive drum at an intersection angle smaller than the engagement angle.   The roller according to claim 1, wherein the crossing angle is 2.5 ° or less. The convex portion and the concave portion constituting the concave and convex portion are each composed of a parallel portion that is parallel to the axial direction and a non-parallel portion that is not parallel.
The said opposing surface is an opposing surface in which the said non-parallel part of the convex part of one edge part which mutually respond | corresponds, and the said non-parallel part of the recessed part of the other edge part oppose. Roller as described in. As for the said convex part, the width | variety of the said axial direction becomes narrow, so that it goes to the front-end | tip in the circumferential direction,
The roller according to claim 1, wherein the concave portion has a width in the axial direction that becomes narrower toward a bottom in a circumferential direction.   The roller according to claim 1, wherein the cylindrical shaft is made of metal.   The roller according to claim 1, wherein the cylindrical shaft is a press-formed molded body.   The roller according to claim 1, wherein the coating layer is an elastic body.   The roller according to claim 1, wherein the roller is a roller for charging the photosensitive drum.   The roller according to claim 1, wherein the roller is a roller for developing an electrostatic latent image formed on the photosensitive drum. A cartridge that can be attached to and detached from the main body of the image forming apparatus,
A cartridge comprising the roller according to claim 1.   An image forming apparatus comprising the roller according to claim 1.

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