JP2005215548A - Process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge which can prevent discharge between a photoreceptor and a transfer means, while having a simple constitution and being easily assembled and which is easily recycled, and to provide an image forming apparatus equipped with the process cartridge. <P>SOLUTION: In the photoreceptor drum 27, the metallic surfaces 95 of both ends in the axis direction of a metallic pipe stock 53 are covered by the attachment of a flange member 58. In a transfer roller 30, the respective shaft ends 77 of a roller shaft 75, projecting from both ends in the axis direction of a roller part 67, are covered by the attachment of a cover member 78. Since the metallic surfaces 95 of both ends in the axial direction of the pipe stock 53 are covered with the flange member 58, and the respective shaft ends 77 are covered with the cover member 78, the discharge between the drum 27 and the roller 30 is securely prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a laser printer, and a process cartridge attached to the image forming apparatus.

  Conventionally, an image forming apparatus such as a laser printer includes a process cartridge including a photosensitive drum on which a toner image based on image data is carried, and a transfer roller that is disposed opposite to the photosensitive drum and to which a transfer bias is applied. It is attached detachably.

  The photosensitive drum includes a conductive metal tube and a photosensitive layer formed on the surface of the metal tube. Since the bearing and gear are mounted on the axial end of the metal tube, the photosensitive layer is usually exposed on the surface of the metal tube so that the axial end of the metal tube is exposed, that is, It is formed so that the axial end of the metal tube is not covered with the photosensitive layer.

  The transfer roller includes a conductive shaft extending along the axial direction of the photosensitive drum and a roller portion formed on the outer peripheral surface of the shaft. Since bearings and gears are mounted on the axial end of the shaft, the roller portion is usually exposed so that the axial end of the shaft is exposed on the outer surface of the shaft, that is, the axial end of the shaft. The part is formed so as not to be covered with the roller part.

  Then, at the time of transfer, a sheet enters between the photosensitive drum and the transfer roller, and a transfer bias is applied, whereby the toner image carried on the photosensitive drum is transferred to the sheet. During this transfer, discharge based on the transfer bias occurs between the axial end of the photosensitive drum where the metal tube is exposed and the axial end of the transfer roller where the shaft is exposed, resulting in transfer failure. There is.

For this reason, for example, it has been proposed that at least one of the photosensitive drum and the transfer roller is covered with an insulating material at the end peripheral surface to prevent leakage (see, for example, Patent Document 1).
JP-A-6-51656

  However, in the method described in Patent Document 1, since the insulating sheet is wound around both ends of the peripheral surface of the photosensitive drum and both ends of the metal shaft of the transfer roller, it takes time and assembly. There is a problem that it becomes complicated. Moreover, when an insulating sheet is wound, there is a problem that it takes time and effort to recycle.

  An object of the present invention is to provide a process cartridge capable of preventing discharge between a photosensitive member and a transfer unit with a simple configuration while being easily assembled, and also capable of being easily recycled. Another object is to provide an image forming apparatus including the process cartridge.

  In order to achieve the above object, an invention according to claim 1 is a photosensitive having a conductive substrate and a photosensitive layer formed on the conductive substrate so that a longitudinal end portion of the conductive substrate is exposed. And a process cartridge that is detachably attached to the image forming apparatus, and is attached to a longitudinal end portion of the photoconductor so as to cover a longitudinal end portion of the conductive substrate, and is formed of an insulating material. It is characterized by having a flange member.

  According to such a configuration, the longitudinal end portion of the photosensitive member from which the conductive substrate is exposed is covered by mounting the flange member formed of an insulating material. Therefore, it is possible to easily assemble with a small number of parts and prevent discharge to the conductive substrate without requiring the trouble of winding an insulating sheet. Further, if the flange member is removed from the conductive substrate, the flange member can also be recycled, and the photoreceptor, particularly the conductive substrate, can be easily recycled (reused). Further, the attachment of the flange member can improve the strength of the end portion in the longitudinal direction of the photoreceptor.

  According to a second aspect of the present invention, in the first aspect of the present invention, the conductive base is formed in a cylindrical shape, and the flange member is disposed radially inward of the conductive base. And a cover portion that is disposed on the radially outer side of the conductive substrate and sandwiches the end portion of the conductive substrate between the insertion portion and the insertion portion.

  According to such a configuration, the flange member is attached to the longitudinal end portion of the conductive substrate so that the conductive substrate is sandwiched between the insertion portion and the cover portion. Therefore, simple and reliable attachment / detachment of the flange member to / from the photoreceptor can be achieved. As a result, the assembly and recycling can be further facilitated.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the conductive substrate is formed in a cylindrical shape, and the photoconductor is along a central axis of the conductive substrate. The flange member is mounted on the conductive base member so as not to rotate relative to the conductive substrate, and is inserted through the photosensitive member shaft and supported so as to be rotatable relative to the photosensitive member shaft. It is characterized by having.

  According to such a configuration, the flange member that is mounted on the conductive base member so as not to rotate relative to the conductive base is supported on the photosensitive member shaft so as to be relatively rotatable, so that the flange member can also serve as a bearing for the photosensitive member. Therefore, it is possible to reliably support the photoconductor while reducing the number of parts and simplifying the configuration.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the conductive base is formed in a cylindrical shape, and the flange member is centered on the conductive base. It has the gear part into which the driving force for rotating around an axis line is input.

  According to such a configuration, since the flange member has the gear portion, if the flange member is attached, a driving force can be input to the gear portion to rotate the photoconductor. Therefore, the photosensitive member can be reliably driven while reducing the number of parts and simplifying the configuration.

  According to a fifth aspect of the present invention, there is provided the conductive shaft according to any one of the first to fourth aspects, wherein the conductive shaft is disposed opposite to the photoconductor and extends along a longitudinal direction of the photoconductor; A roller portion formed on the outer peripheral surface of the shaft so as to expose an axial end portion of the shaft, and transferring a developer image carried on the photosensitive layer to a transfer medium by applying a transfer bias. And a cover member mounted on the axial end portion of the shaft so as to cover the axial end portion and formed of an insulating material.

  According to such a configuration, the axial end portion of the shaft exposed from the roller portion of the transfer means is covered by mounting the cover member formed of an insulating material. Therefore, it is possible to easily assemble with a small number of parts and prevent the transfer means from discharging, without the need for winding an insulating sheet. Further, if the cover member is removed from the shaft, the transfer means can be easily recycled. Furthermore, since the conductive substrate is covered with the flange member and the shaft is covered with the cover member, it is possible to achieve more reliable prevention of discharge between the photosensitive member and the transfer means.

  The invention according to claim 6 includes a photoreceptor having a conductive substrate and a photosensitive layer formed on the conductive substrate so that a longitudinal end portion of the conductive substrate is exposed. In a process cartridge that is detachably attached to an image forming apparatus, a conductive shaft that is disposed to face the photoconductor and extends along a longitudinal direction of the photoconductor, and an axial direction of the shaft on an outer peripheral surface of the shaft A transfer section for transferring the developer image carried on the photosensitive layer to a transfer medium by applying a transfer bias, and an axial direction of the shaft. A cover member is provided on the end portion so as to cover the end portion in the axial direction, and is formed of an insulating material.

  According to such a configuration, the axial end portion of the shaft exposed from the roller portion of the transfer means is covered by mounting the cover member formed of an insulating material. Therefore, it is possible to easily assemble with a small number of parts and prevent the transfer means from discharging, without the need for winding an insulating sheet. Further, if the cover member is removed from the shaft, the transfer means can be easily recycled.

  The invention according to claim 7 is the invention according to claim 5 or 6, wherein the cover member is formed longer than a portion of the shaft exposed from the roller portion, and an axial direction of the shaft The cover member is mounted so that an end portion facing the roller portion of the cover member bites into an end surface of the roller portion facing the cover portion.

  According to such a configuration, since the end portion of the cover member that faces the roller portion is mounted so as to bite into the end surface of the roller portion that faces the cover portion, a gap is formed between the cover member and the roller portion. The shaft can be coated without causing it. Therefore, discharge can be reliably prevented with a simple configuration in which the cover member bites into the roller portion.

  The invention according to claim 8 is the invention according to claim 5 or 6, wherein the roller portion is bonded to the outer peripheral surface of the shaft so that the end portion facing the cover member is not bonded. In the axial direction of the shaft, the cover member has an end portion facing the roller portion at an end portion of the roller portion that is not bonded between the roller portion and the shaft. It is mounted so that it can be inserted.

  According to such a configuration, since the end portion of the cover member facing the roller portion is mounted so as to be inserted into the unbonded portion between the roller portion and the shaft at the end portion of the roller portion. The shaft can be covered by the cover member without causing a gap between the cover member and the roller portion. Therefore, discharge can be reliably prevented by a simple configuration in which the cover member is inserted between the roller portion and the shaft.

  The invention according to claim 9 is the invention according to any one of claims 5 to 8, wherein the cover member includes a transfer gear portion to which a driving force for rotating the shaft is input, and the shaft. In the axial direction, the cylindrical portion is located closer to the roller portion than the transfer gear portion and through which the shaft is inserted.

  According to such a configuration, when the cover member is attached to the shaft, the shaft can be rotated by inputting the driving force from the transfer gear portion while the shaft can be reliably covered by the cylindrical portion.

  The invention described in claim 10 is characterized in that, in the invention described in claim 9, the transfer gear portion and the cylindrical portion are integrally formed.

  According to such a configuration, since the transfer gear portion and the cylindrical portion are integrally formed, the number of components can be reduced and the configuration can be simplified.

  The invention according to claim 11 is the invention according to any one of claims 5 to 9, wherein the cover member includes a cylindrical portion through which the shaft is inserted, and a bearing portion that rotatably receives the shaft. It is characterized by having.

  According to such a configuration, if the cover member is attached to the shaft, the shaft can be supported while the shaft can be reliably covered by the cylindrical portion.

  The invention described in claim 12 is characterized in that, in the invention described in claim 11, the cylindrical portion and the bearing portion are integrally formed.

  According to such a configuration, since the cylindrical portion and the bearing portion are integrally formed, the number of components can be reduced and the configuration can be simplified.

  A thirteenth aspect of the present invention is the invention according to any one of the fifth to twelfth aspects, wherein the cover member has a central axis line of the shaft on an end surface facing the roller portion in the axial direction of the shaft. It is characterized in that at least one of an annular convex ridge portion and a concave ridge portion as a center is formed.

  According to such a structure, the annular | circular shaped convex part or concave part formed in the end surface of a cover member can be made to contact the end surface of a roller part. Therefore, the shaft can be covered with the cover member without generating a gap between the roller portion and the cover member while reducing the friction between the end surface of the cover member and the end surface of the roller portion. Further, creeping leakage of the transfer bias from the shaft can be reliably prevented.

  According to a fourteenth aspect of the present invention, there is provided the electrode according to any one of the fifth to thirteenth aspects, wherein an electrode for applying a transfer bias to the transfer means is in contact with the axial end surface of the shaft. The cover member is mounted so as to continuously cover the electrode and the axial end of the shaft.

  According to such a configuration, since the cover member covers the shaft and the electrode, it is possible to more reliably prevent the discharge with the photoconductor.

  The invention according to claim 15 is the invention according to any one of claims 5 to 13, further comprising an electrode for applying a transfer bias to the transfer means, wherein the cover member is an outer peripheral surface of the shaft. Is partially exposed and has a notch for contacting the electrode with the exposed portion.

  According to such a configuration, the cover member can expose the outer peripheral surface of the shaft from the notch portion while covering the shaft, and allow the outer peripheral surface to contact the electrode. Therefore, the transfer bias can be reliably applied while the shaft can be covered.

  The invention described in claim 16 is characterized in that, in the invention described in claim 15, the notch is formed at a position of the cover member not facing the photoconductor.

  According to such a configuration, the notch is formed at a position where the cover member does not face the photoconductor. Therefore, discharge between the photosensitive member and the photoreceptor can be prevented more reliably.

  According to a seventeenth aspect of the present invention, in the invention according to any one of the fifth to sixteenth aspects, in the axial direction of the shaft, the end surface of the roller portion is a recess recessed inward of the roller portion. In the axial direction of the shaft, the cover member is mounted such that an end facing the end surface of the roller portion enters the recess.

  According to such a configuration, the cover member is mounted such that the end portion of the cover member enters the concave portion of the roller portion. Therefore, the cover member can be arranged so that the shaft is not exposed from the direction facing the photoconductor. As a result, discharge between the photosensitive member and the photosensitive member can be reliably prevented with a simple configuration.

  The invention described in claim 18 is characterized in that, in the invention described in claim 17, the recess is formed so as to be recessed in a cylindrical shape around the shaft.

  According to such a configuration, since the concave portion is formed so as to be recessed in a cylindrical shape around the shaft, the cover member is covered so as to be fitted into the concave portion, and the discharge between the photosensitive member and the photoconductor is more reliably performed. Can be prevented.

  The invention according to claim 19 is the invention according to claim 17, wherein the concave portion is inclined so as to incline from the outer peripheral surface of the roller portion toward the inner peripheral surface. It is characterized by being formed as a surface.

  According to such a configuration, since the concave portion is formed as an inclined surface, the concave portion can be easily formed, but the cover member is covered with the concave portion, and discharge between the photosensitive member and the photosensitive member can be prevented. .

  The invention described in claim 20 is characterized in that, in the invention described in claim 17, the recess is formed so as to be recessed in a truncated cone shape around the shaft.

  According to such a configuration, since it is formed so as to be recessed in a truncated cone shape around the shaft, the cover member is covered so as to be fitted in the concave portion, thereby more reliably preventing discharge between the photosensitive member and the photosensitive member. be able to.

  The invention according to claim 21 is the invention according to any one of claims 5 to 16, wherein in the axial direction of the shaft, the end surface of the roller portion protrudes outward of the roller portion. The cover member has an edge cover portion that covers the convex portion so as to fit the convex portion at an end facing the roller portion in the axial direction of the shaft. It is characterized by being.

  According to such a configuration, the cover member is mounted so that the convex portion of the roller portion is covered with the edge cover portion, so that the cover member covers the shaft without causing a gap between the cover member and the roller portion. can do. As a result, it is possible to more reliably prevent discharge with the photoreceptor.

  The invention described in claim 22 is characterized in that, in the invention described in claim 21, the convex portion is formed so as to protrude in a cylindrical shape around the shaft.

  According to such a configuration, since the convex portion is formed so as to protrude in a cylindrical shape around the shaft, the convex portion of the roller portion is covered so as to be fitted by the edge cover portion, and the shaft is covered by the cover member. Can be more reliably coated.

  The invention as set forth in claim 23 is characterized in that, in the invention as set forth in claim 21, the convex portion is formed so as to protrude in a truncated cone shape around the shaft.

  According to such a configuration, since the convex portion is formed so as to protrude in a truncated cone shape around the shaft, the convex portion of the roller portion is covered so as to be fitted by the edge cover portion, and the cover member The shaft can be coated more reliably.

  According to a twenty-fourth aspect of the present invention, in the invention according to any one of the fifth to sixteenth aspects, the end surface of the roller portion in the axial direction of the shaft is directed from the outer peripheral surface of the roller portion toward the inner peripheral surface. The roller portion is formed as an inclined surface that protrudes outward.

  According to such a configuration, since the end surface of the roller portion is formed as an inclined surface, the end surface of the roller portion can be easily formed, and the shaft can be reliably covered with the cover member.

  According to a twenty-fifth aspect of the invention, there is provided an image forming apparatus comprising the process cartridge according to any one of the first to twenty-fourth aspects.

  The image forming apparatus includes a process cartridge that can be easily assembled with reduced discharge between the photosensitive member and the transfer unit. Therefore, an image with few transfer defects can be formed, and the image can be manufactured with high production efficiency.

  The invention according to claim 26 is an image forming apparatus comprising: a conductive substrate; and a photosensitive layer formed on the conductive substrate so that a longitudinal end portion of the conductive substrate is exposed. In an image forming apparatus comprising: a photosensitive member having a photosensitive member; and a developing unit that supplies a developer to the photosensitive member, the longitudinal end portion of the photosensitive member is attached to cover the longitudinal end portion of the conductive substrate. And a flange member formed of an insulating material.

  According to such a configuration, the longitudinal end portion of the photosensitive member from which the conductive substrate is exposed is covered by mounting the flange member formed of an insulating material. Therefore, it is possible to easily assemble with a small number of parts and prevent discharge to the conductive substrate without requiring the trouble of winding an insulating sheet. Further, if the flange member is removed from the conductive substrate, the flange member can also be recycled, and the photoreceptor, particularly the conductive substrate, can be easily recycled (reused). Further, the attachment of the flange member can improve the strength of the end portion in the longitudinal direction of the photoreceptor.

  According to a twenty-seventh aspect of the invention, in the twenty-sixth aspect of the invention, a conductive shaft that is disposed to face the photoconductor and extends along a longitudinal direction of the photoconductor, and an outer peripheral surface of the shaft. And a transfer means for transferring the developer image carried on the photosensitive layer to a transfer medium by applying a transfer bias. And a cover member attached to the axial end portion of the shaft so as to cover the axial end portion and formed of an insulating material.

  According to such a configuration, the axial end portion of the shaft exposed from the roller portion of the transfer means is covered by mounting the cover member formed of an insulating material. Therefore, it is possible to easily assemble with a small number of parts and prevent the transfer means from discharging, without the need for winding an insulating sheet. Further, if the cover member is removed from the shaft, the transfer means can be easily recycled. Furthermore, since the conductive substrate is covered with the flange member and the shaft is covered with the cover member, it is possible to achieve more reliable prevention of discharge between the photosensitive member and the transfer means.

  According to the first aspect of the present invention, it is possible to easily assemble with a small number of parts and prevent discharge to the conductive substrate. Further, the flange member and the photoreceptor can be easily recycled. Furthermore, the strength of the end portion in the longitudinal direction of the photoreceptor can be improved.

  According to the second aspect of the present invention, it is possible to further facilitate the assembly and recycling.

  According to the third aspect of the present invention, it is possible to reliably support the photosensitive member while reducing the number of parts and simplifying the configuration.

  According to the fourth aspect of the present invention, it is possible to reliably drive the photosensitive member while reducing the number of parts and simplifying the configuration.

  According to the fifth aspect of the present invention, it is possible to easily assemble with a small number of parts and prevent discharge of the transfer means. Further, the transfer means can be easily recycled. Furthermore, it is possible to achieve more reliable prevention of discharge between the photoconductor and the transfer means.

  According to the sixth aspect of the present invention, it is possible to easily assemble with a small number of parts and prevent discharge of the transfer means. In addition, the photoconductor can be easily recycled.

  According to the seventh aspect of the present invention, it is possible to reliably prevent electric discharge with a simple configuration in which the cover member bites into the roller portion.

  According to the eighth aspect of the present invention, discharge can be reliably prevented by a simple configuration in which the cover member is inserted between the roller portion and the shaft.

  According to the ninth aspect of the present invention, the shaft can be rotated by inputting the driving force from the transfer gear portion while the shaft can be reliably covered by the cylindrical portion.

  According to the tenth aspect of the present invention, the number of parts can be reduced and the configuration can be simplified.

  According to the eleventh aspect of the invention, the shaft can be supported while the shaft can be reliably covered with the cylindrical portion.

  According to the twelfth aspect of the invention, the number of parts can be reduced and the configuration can be simplified.

  According to the thirteenth aspect of the present invention, the cover can cover the shaft without reducing a gap between the cover member and the roller portion while reducing friction between the end surface of the cover member and the end surface of the roller portion. it can. Further, creeping leakage of the transfer bias from the shaft can be reliably prevented.

  According to the fourteenth aspect of the present invention, it is possible to more reliably prevent discharge with the photosensitive member.

  According to the fifteenth aspect of the present invention, the transfer bias can be reliably applied while the shaft can be covered.

  According to the sixteenth aspect of the present invention, it is possible to more reliably prevent discharge with the photosensitive member.

  According to the seventeenth aspect of the present invention, discharge between the photosensitive member and the photoconductor can be reliably prevented with a simple configuration.

  According to the eighteenth aspect of the invention, the cover member is covered so as to be fitted into the cylindrical concave portion, and discharge between the photosensitive member and the photoconductor can be prevented more reliably.

  According to the nineteenth aspect of the present invention, it is possible to prevent the discharge between the photosensitive member and the cover member by covering the cover member with the concave portion while the concave portion can be easily formed.

  According to the twentieth aspect of the present invention, the cover member is covered so as to be fitted into the truncated cone-shaped concave portion, so that discharge between the photosensitive member and the photoconductor can be prevented more reliably.

  According to the twenty-first aspect of the present invention, the cover member can cover the shaft without generating a gap with the roller portion, and more reliably prevent discharge between the photosensitive member and the photosensitive member. Can do.

  According to the invention described in claim 22, it is possible to cover the shaft more reliably by the cover member by covering the protruding portion protruding in a cylindrical shape with the edge cover portion.

  According to the twenty-third aspect of the present invention, the convex portion protruding in the shape of the truncated cone is covered by the edge cover portion, and the shaft can be covered more reliably by the cover member.

  According to the twenty-fourth aspect of the present invention, the end surface of the roller portion can be easily formed while the shaft can be reliably covered with the cover member.

  According to the invention of claim 25, an image with few transfer defects can be formed, and the image can be produced with high production efficiency.

  According to the twenty-sixth aspect of the present invention, it is possible to easily assemble with a small number of parts and prevent discharge to the conductive substrate. Further, the flange member and the photoreceptor can be easily recycled. Furthermore, the strength of the end portion in the longitudinal direction of the photoreceptor can be improved.

  According to the twenty-seventh aspect of the present invention, it is possible to easily assemble with a small number of parts and prevent discharge of the transfer means. Further, the transfer means can be easily recycled. Furthermore, it is possible to achieve more reliable prevention of discharge between the photoconductor and the transfer means.

  FIG. 1 is a cross-sectional side view of a main part showing an embodiment of a laser printer as an image forming apparatus of the present invention. In FIG. 1, a laser printer 1 includes a feeder unit 4 for feeding a sheet 3 as a transfer medium in a main body casing 2, an image forming unit 5 for forming an image on the fed sheet 3, and the like. It has.

  The feeder unit 4 includes a paper feed tray 6 that is detachably attached to the bottom of the main body casing 2, a paper pressing plate 7 provided in the paper feed tray 6, and an upper end of one end side of the paper feed tray 6. A paper feed roller 8 and a paper feed pad 9, paper dust removing rollers 10 and 11 provided on the downstream side of the paper feeding direction with respect to the paper feeding roller 8, and paper 3 for the paper dust removing rollers 10 and 11. And a registration roller 12 provided on the downstream side in the transport direction (hereinafter, the downstream side or upstream side in the transport direction of the paper 3 may be simply referred to as downstream side or upstream side).

  The sheet pressing plate 7 can stack the sheets 3 in a laminated form, and is supported so as to be swingable at the end far from the sheet feeding roller 8, so that the near end moves up and down. It is made possible, and is biased upward by a spring (not shown) from the back side. Therefore, the sheet pressing plate 7 is swung downward against the urging force of the spring, with the end far from the sheet feeding roller 8 as a fulcrum as the amount of stacked sheets 3 increases. The paper feed roller 8 and the paper feed pad 9 are arranged to face each other, and the paper feed pad 9 is pressed toward the paper feed roller 8 by a spring 13 provided on the back side of the paper feed pad 9.

  The uppermost sheet 3 on the sheet pressing plate 7 is pressed toward the sheet feeding roller 8 by a spring (not shown) from the back side of the sheet pressing plate 7, and the sheet feeding roller 8 and the sheet feeding are rotated by the rotation of the sheet feeding roller 8. After being sandwiched between the pads 9, the sheets are fed one by one.

  The fed paper 3 is conveyed to the registration roller 12 after the paper dust is removed by the paper dust removing rollers 10 and 11. The registration roller 12 includes a pair of rollers facing each other, and sends the paper 3 to the image forming position after registration. Note that the image forming position is a transfer position at which the toner image on the photosensitive drum 27 is transferred to the paper 3, and is a contact position between the photosensitive drum 27 and the transfer roller 30 in this embodiment.

  The feeder unit 4 further includes a multi-purpose tray 14, a multi-purpose side feed roller 15 and a multi-purpose side feed pad 25 for feeding the paper 3 stacked on the multi-purpose tray 14. I have. The multi-purpose-side paper feed roller 15 and the multi-purpose-side paper feed pad 25 are provided so as to face each other, and the multi-purpose-side paper feed pad 25 is multi-purposed by a spring 26 provided on the back side of the multi-purpose-side paper feed pad 25. It is pressed toward the side paper feed roller 15.

  The sheets 3 stacked on the multi-purpose tray 14 are fed one by one after being sandwiched between the multi-purpose side feed roller 15 and the multi-purpose side feed pad 25 by the rotation of the multi-purpose side feed roller 15. Paper.

  The image forming unit 5 includes a scanner unit 16, a process cartridge 17, a fixing unit 18, and the like.

  The scanner unit 16 is provided at an upper portion in the main body casing 2 and includes a laser light emitting unit (not shown), a polygon mirror 19 that is rotationally driven, lenses 20 and 21, reflecting mirrors 22, 23, and 24. . The laser beam based on the image data emitted from the laser emitting unit passes or reflects in the order of the polygon mirror 19, the lens 20, the reflecting mirrors 22 and 23, the lens 21, and the reflecting mirror 24, as indicated by the chain line, and processes. The surface of a photosensitive drum 27 (described later) of the cartridge 17 is irradiated with high-speed scanning.

  The process cartridge 17 is provided below the scanner unit 16 and is detachably attached to the main body casing 2. In the casing 51, a developing cartridge 28 as developing means and an image carrier are provided. A photosensitive drum 27, a scorotron charger 29, a transfer roller 30 as a transfer means, and a conductive brush 52.

  The developing cartridge 28 is detachably attached to the housing 51 and includes a developing roller 31, a layer thickness regulating blade 32, a supply roller 33, and a toner hopper 34.

  In the toner hopper 34, positively charged non-magnetic one-component toner is accommodated as a developer. Examples of the toner include polymerizable monomers such as styrene monomers such as styrene, and acrylic monomers such as acrylic acid, alkyl (C1 to C4) acrylate, and alkyl (C1 to C4) methacrylate. Polymerized toners obtained by copolymerization by a known polymerization method such as suspension polymerization are used. Such a polymerized toner is substantially spherical and has very good fluidity. Such a toner is blended with a colorant such as carbon black, wax, or the like, and an external additive such as silica is added to improve fluidity. The particle diameter is about 6 to 10 μm.

  Then, the toner in the toner hopper 34 is agitated by an agitator 36 supported by a rotating shaft 35 provided at the center of the toner hopper 34, and is discharged from a toner supply port 37 opened at a side portion of the toner hopper 34. Note that a toner remaining amount detection window 38 is provided on the side wall of the toner hopper 34 and is cleaned by a cleaner 39 supported by the rotating shaft 35.

  A supply roller 33 is rotatably provided at a side position of the toner supply port 37, and a developing roller 31 is rotatably provided facing the supply roller 33. The supply roller 33 and the developing roller 31 are in contact with each other in a state where they are compressed to some extent.

  The supply roller 33 has a metal roller shaft covered with a roller portion made of a conductive foam material.

  The developing roller 31 has a metal roller shaft covered with a roller portion made of a conductive rubber material. More specifically, the roller portion of the developing roller 31 has a urethane rubber or silicone rubber coating layer containing fluorine on the surface of a roller layer made of conductive urethane rubber or silicone rubber containing carbon fine particles. It is covered. A developing bias is applied to the developing roller 31 during development.

  A layer thickness regulating blade 32 is provided in the vicinity of the developing roller 31. The layer thickness regulating blade 32 includes a pressing portion 40 having a semicircular cross section made of insulating silicone rubber at the tip of a blade body made of a metal leaf spring material. 28, the pressing portion 40 is provided so as to be pressed against the developing roller 31 by the elastic force of the blade body.

  The toner discharged from the toner supply port 37 is supplied to the developing roller 31 by the rotation of the supply roller 33 in the arrow direction (counterclockwise direction). At this time, the toner is supplied between the supply roller 33 and the developing roller 31. Positively triboelectrically charged. The toner supplied onto the developing roller 31 enters between the pressing portion 40 of the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates in the arrow direction (counterclockwise). It is carried on the developing roller 31 as a thin layer having a constant thickness.

  The photosensitive drum 27 is supported by the housing 51 so as to be rotatable in the arrow direction (clockwise) in a state of facing the developing roller 31 at a side position of the developing roller 31.

  As shown in FIG. 2, the photosensitive drum 27 includes a metal base tube 53 as a conductive base, a photosensitive layer 54 formed on the surface of the metal base tube 53, and a central axis of the metal base tube 53. And a drum shaft 55 as a photosensitive member shaft.

  The metal pipe 53 has a substantially cylindrical shape and is made of a conductive metal material.

  The photosensitive layer 54 is made of polycarbonate or the like, and the axial direction of the metal base tube 53 (hereinafter referred to as the metal base tube) so that the metal surfaces 59 (see FIGS. 3 and 4) at both ends in the axial direction of the metal base tube 53 are exposed. The axial direction of 53 may be simply referred to as the axial direction.) The outer peripheral surface of the metal tube 53 is coated over the axial direction, leaving both ends.

  The drum shaft 55 is made of a metal shaft, and is arranged along the axial direction in the central axis line in the metal base tube 53, and is supported on both side walls 56 of the housing 51 through a stopper member 57 so as not to rotate. ing. A flange member 58 described below is attached to the drum shaft 55 so as to be relatively rotatable, and the metal base tube 53 is supported via the flange member 58 so as to be relatively rotatable.

  A flange member 58 is attached to the photosensitive drum 27. The flange member 58 is made of an insulating resin material, and is attached to both end portions in the axial direction of the metal base tube 53 so as not to rotate relative to the metal base tube 53.

  As shown in FIGS. 3 and 4, each flange member 58 includes a flange bearing portion 61 into which the drum shaft 55 is inserted, an insertion portion 62 to be inserted into the metal pipe 53, a flange bearing portion 61 and an insertion portion 62. And a flange 64 provided on the outer side of the radial direction of the metal base tube 53 in the insertion portion 62 (hereinafter, the radial direction of the metal base tube 53 may be simply referred to as a radial direction). And are integrally molded.

  The flange bearing portion 61 has an inner diameter that is substantially the same as the outer diameter of the drum shaft 55, and is formed in a cylindrical shape that fits the outer peripheral surface of the drum shaft 55.

  The insertion portion 62 has an outer diameter that is substantially the same as the inner diameter of the metal base tube 53, and is formed in a cylindrical shape that is inserted into the inner peripheral surface of the metal base tube 53.

  The flange connection portion 63 is formed in a ring plate shape so as to extend between the flange bearing portion 61 and the insertion portion 62 in the radial direction of the metal pipe 53.

  The flange portion 64 protrudes radially outward from the outer peripheral surface of the insertion portion 62, and bends inward in the axial direction from the free end portion of the protrusion 65 so that the metal base tube 53 is bent. The drum cover part 66 is integrally formed with a drum cover part 66 as a cover part formed so as to cover the metal surface 59.

  As shown in FIG. 3, one flange member 58 has a flange side coupling portion 71 for coupling with a drum gear portion 67 described below, and an output gear 84 for meshing with a transfer gear 83 to be described later. Are integrally formed.

  The flange-side connecting portion 71 is formed so as to protrude outward in the axial direction from the middle in the radial direction of the flange connecting portion 63.

  The output gear 84 has a cylindrical shape that extends continuously outward from the insertion portion 62 in the axial direction, and includes a plurality of external teeth that protrude outward in the radial direction and mesh with a transfer gear 83 described later.

  The one flange member 58 is provided with a drum gear portion 67 as a gear portion to which a driving force for rotating the metal base tube 53 around the central axis is input.

  The drum gear portion 67 is provided on the outer side in the axial direction of the flange member 58, and includes a gear bearing portion 68 into which the drum shaft 55 is inserted, an input gear 69 with which a drive transmission gear (not shown) is engaged, and a gear bearing portion 68. A gear connecting portion 70 that connects the input gear 69 is integrally formed.

  The gear bearing portion 68 has an inner diameter that is substantially the same as the outer diameter of the drum shaft 55, and is formed in a cylindrical shape that fits the outer peripheral surface of the drum shaft 55.

  The input gear 69 has a plurality of external teeth projecting radially outward that mesh with a drive transmission gear (not shown) and is formed in a cylindrical shape.

  The gear coupling portion 70 is formed in a ring plate shape so as to extend between the gear bearing portion 68 and the input gear 69 in the radial direction.

  In addition, the gear connecting portion 70 has a gear side coupling portion 72 that protrudes inward in the axial direction from the middle in the radial direction of the gear coupling portion 70 and is coupled to the flange side coupling portion 71. Is formed.

  The drum gear portion 67 abuts and fixes the flange side coupling portion 71 and the gear side coupling portion 72 of one flange member 58 so that the gear bearing portion 68 and the flange bearing portion 61 face each other in the axial direction. Thus, the flange member 58 is joined so as not to be relatively rotatable.

  Note that the drum gear portion 67 may be formed integrally with the flange member 58.

  One flange member 58 is inserted through one end of the drum shaft 55 in the axial direction so that the flange bearing portion 61 and the gear bearing portion 68 slide with the outer peripheral surface of the drum shaft 55. In this state, the insertion portion 62 and the drum cover portion 66 are arranged in a state where the insertion portion 62 is disposed on the radially inner side of the metal base tube 53 and the drum cover portion 66 is disposed on the radially outer side of the metal base tube 53. The metal pipe 53 is mounted so as to sandwich one end of the pipe 53 in the axial direction. Accordingly, one flange member 58 is attached to one end portion in the axial direction of the metal base tube 53 so as not to be relatively rotatable, and the metal surface 59 exposed from the photosensitive layer 54 at one end portion in the axial direction of the metal base tube 53 has a drum cover. Covered by portion 66.

  As shown in FIG. 4, the other flange member 58 has a flange bearing 61 at the other end in the axial direction of the drum shaft 55, and the inner peripheral surface thereof slides on the outer peripheral surface of the drum shaft 55. In the state where the insertion portion 62 is disposed radially inside the metal base tube 53 and the drum cover 66 is disposed radially outside the metal base tube 53, the insertion portion 62 and the drum cover portion 66 are inserted. Are attached to the metal element tube 53 so as to sandwich the other axial end of the metal element tube 53. As a result, the other flange member 58 is mounted on the other end in the axial direction of the metal base tube 53 so as not to be relatively rotatable, and the metal surface 59 exposed from the photosensitive layer 54 at the other end in the axial direction of the metal base tube 53 is Covered by the drum cover 66.

  Further, by such mounting, each flange member 58 is mounted on the both ends of the metal base tube 53 in the axial direction so as not to rotate relative to each other, and is supported so as to be rotatable relative to the drum shaft 55. The drum 27 is rotatably supported on the drum shaft 55 via the flange members 58.

  A spring receiving member 73 through which the drum shaft 55 is inserted between the other flange member 58 and a spring received by the spring receiving member 73 on the other side wall 56 to which the other flange member 58 is mounted. 74 is provided.

  The spring receiving member 73 has a substantially U-shaped cross section that is opened inward in the axial direction, and is supported inside the other side wall 56. Further, the spring 74 is provided around the drum shaft 55 and biases the other flange member 58 inward in the axial direction while being received by the spring receiving member 73. As a result, as shown in FIG. 3, the drum gear portion 67 provided on the one flange portion 58 is brought into contact with the one side wall 56, and the photosensitive drum 27 is positioned in the axial direction.

  When a driving force is transmitted from a motor (not shown) provided in the main body casing 2 to a driving transmission gear (not shown), the input gear 69 that meshes with the driving transmission gear is rotationally driven. It is rotated.

  As shown in FIG. 1, the scorotron charger 29 is opposed to the photosensitive drum 27 so as not to contact the photosensitive drum 27 above the photosensitive drum 27 and is supported by the casing 51. The scorotron charger 29 is a positively-charged scorotron charger that generates corona discharge from a charging wire such as tungsten, so that the surface of the photosensitive drum 27 can be uniformly charged positively. Is provided.

  Further, the conductive brush 52 is disposed opposite to the photosensitive drum 27 at a side position of the photosensitive drum 27 (a side position opposite to the developing roller 31). The conductive brush 52 is fixed to the casing 51 such that the tip of the brush contacts the surface of the photosensitive drum 27.

  The transfer roller 30 is disposed below the photosensitive drum 27 so as to face the photosensitive drum 27, and is supported so as to be rotatable in an arrow direction (counterclockwise direction).

  As shown in FIG. 2, the transfer roller 30 includes a roller shaft 75 and a roller portion 76 provided on the outer peripheral surface of the roller shaft 75.

  The roller shaft 75 is made of a conductive metal material, is disposed so as to extend along the axial direction of the photosensitive drum 27, and is rotatably supported by a roller bearing portion 81 described later.

  The roller portion 76 is formed of a conductive rubber material, and the axial direction of the roller shaft 75 (the axial direction of the metal base tube 53 and the axial end portion 77 of both ends in the axial direction of the roller shaft 75 are exposed). The same direction, hereinafter simply referred to as the axial direction).

  A cover member 78 that covers the shaft end portions 77 is attached to each shaft end portion 77 of the roller shaft 75 of the transfer roller 30.

  One cover member 78 is made of an insulating resin material, and includes a transfer gear portion 79, a cylindrical portion 80, and a roller bearing portion 81 as a bearing portion, as shown in FIG.

  The transfer gear portion 79 is input with a driving force for rotating the roller shaft 75, and is provided on the outer side in the axial direction, farther from the roller portion 76 than the cylindrical portion 80, at one axial end portion of the roller shaft 75. A cylindrical gear cylinder portion 82 that covers the outer peripheral surface of 75 and a transfer gear 83 that extends radially outward from the axially inner side of the gear cylinder portion 82 are integrally formed.

  The gear cylinder portion 82 is provided so as not to rotate relative to the roller shaft 75 so as to cover the tip portion of one shaft end portion 77 of the roller shaft 75. The transfer gear 83 includes a plurality of external teeth that protrude outward in the radial direction and mesh with the output gear 84.

  The cylindrical portion 80 is provided at one axial end of the roller shaft 75 on the inner side in the axial direction (between the transfer gear portion 79 and the roller portion 76), closer to the roller portion 76 than the transfer gear portion 79. It is formed in a cylindrical shape covering the outer peripheral surface of one of the shaft end portions 77. The cylinder portion 80 is provided so as not to rotate relative to the roller shaft 75.

  The roller bearing portion 81 is formed in an annular shape covering the outer peripheral surface of the cylindrical portion 80 in the middle of the cylindrical portion 80 in the axial direction, and is slidable with respect to the outer peripheral surface of the cylindrical portion 80 (relative to the cylindrical portion 80). Relative rotation). Accordingly, the roller bearing portion 81 supports the roller shaft 75 so as to be rotatable via the cylindrical portion 80.

  Further, the sum of the axial length of the gear cylinder portion 82 and the axial length of the cylinder portion 80 is formed to be longer than the axial length of one of the shaft end portions 77.

  One cover member 78 is inserted through the cylindrical portion 80 through which the roller bearing portion 81 is inserted into the one shaft end portion 77 so as not to be rotatable relative to the shaft end portion 77, and then the transfer gear portion 79 is inserted. The shaft end portion 77 is inserted into the shaft end portion 77 so as not to rotate relative to the shaft end portion 77 so as to be in contact with the cylindrical portion 80, and the axially outer end portion of the transfer gear portion 79 is brought into contact with the side wall 56. It is attached so that it may. As a result, the transfer gear portion 79 presses the cylindrical portion 80 inward in the axial direction, so that the axially inner end portion (the end portion facing the roller portion 76) of the cylindrical portion 80 is in the roller portion 76. It is mounted so as to bite into the end surface facing the tube portion 80. In FIG. 3, such a biting amount of the cylindrical portion 80 is indicated by a symbol X.

  The other cover member 78 is formed of an insulating resin material, and includes a cylindrical portion 88 and a roller bearing portion 89 as a bearing portion, as shown in FIG.

  The cylindrical portion 88 covers the outer peripheral surface of the other shaft end portion 77 of the roller shaft 75 in the axial direction at the other axial end portion of the roller shaft 75, and further, the cylindrical portion 88 of the other shaft end portion 77 of the roller shaft 75. The electrode 85 disposed outward in the axial direction is also formed in a cylindrical shape that can be continuously covered. The cylinder portion 88 is provided so as not to rotate relative to the roller shaft 75.

  That is, the electrode 85 has a pin shape having a head portion 86 and a shaft portion 87, and the shaft portion 87 is embedded in the other side wall 56 along the axial direction, so that the head portion 86 is connected to the other shaft end. On the outer side in the axial direction of the portion 77, the end surface of the shaft end portion 77 is disposed so as to face and contact in the axial direction. The electrode 85 is connected to a power source for applying a transfer bias (not shown). At the time of transfer, a transfer bias is applied from the power source to the transfer roller 30 via the electrode 85.

  A locking edge 90 that receives and locks the head 86 is formed on the outer side in the axial direction of the cylindrical portion 88. The cylindrical portion 88 covers the other axial end 77 over the entire axial direction. And receiving the head portion 86 of the electrode, locking it by the locking edge 90, and projecting the shaft portion 87 outward in the axial direction. 86 is continuously coated.

  The roller bearing portion 89 is formed in an annular shape covering the outer peripheral surface of the cylindrical portion 88 in the middle of the cylindrical portion 88 in the axial direction, and is slidable with respect to the outer peripheral surface of the cylindrical portion 88 (relative to the cylindrical portion 88). Relative rotation). As a result, the roller bearing portion 89 rotatably supports the roller shaft 75 via the cylindrical portion 88.

  The other cover part 78 has a cylinder part 88 through which the roller bearing part 89 is inserted, a head part 86 of the electrode 85, the head part 86 is locked by a locking edge part 90, and a shaft part 87 is a cylinder part. In a state of being received so as to protrude from 88, the other shaft end portion 77 is inserted so as not to rotate relative to the shaft end portion 77, and the shaft portion 87 of the electrode 85 is embedded in the side wall 56. ing.

  Note that, on both sides of the roller portion 76, the roller bearing portions 81 and 89 that rotatably support the shaft end portion 77 of the roller shaft 75 via the tube portions 80 and 88 are respectively formed as shown in FIG. When the process cartridge 17 is attached to the main casing 2, the process cartridge 17 is received toward the photosensitive drum 27 by the biasing spring 92 that is received from the opening 91 formed in the bottom wall of the casing 51 and provided in the main casing 2. It is energized. As a result, the roller portion 76 of the transfer roller 30 is pressed against the metal base tube 53 of the photosensitive drum 27.

  When the photosensitive drum 27 is rotated by a driving force from a motor (not shown) provided in the main casing 2, the output gear 84 of the flange member 58 mounted on the photosensitive drum 27 is rotated. The transfer gear 83 meshing with the gear 84 is driven to rotate, whereby the transfer roller 30 is rotated.

  As shown in FIG. 1, the surface of the photosensitive drum 27 is uniformly positively charged by a scorotron charger 29 and then exposed by high-speed scanning of a laser beam from the scanner unit 16 to obtain a static image based on image data. An electrostatic latent image is formed.

  Next, the electrostatic latent image formed on the surface of the photosensitive drum 27 when the toner carried on the developing roller 31 and positively charged comes into contact with the photosensitive drum 27 by rotation of the developing roller 31. That is, the surface of the photosensitive drum 27 that is uniformly positively charged is supplied to an exposed portion that is exposed to a laser beam and the potential is lowered, and is selectively carried to be visualized. Thus, a toner image is formed by reversal development.

  Thereafter, the photosensitive drum 27 and the transfer roller 30 are rotationally driven so as to sandwich and convey the sheet 3 therebetween, and the sheet 3 is conveyed between the photosensitive drum 27 and the transfer roller 30. A toner image carried on the surface of the photosensitive drum 27 is transferred onto the paper 3.

  It should be noted that the paper dust adhering to the surface of the photosensitive drum 27 by contact with the paper 3 after the transfer is when the surface of the photosensitive drum 27 faces the brush of the conductive brush 52 as the photosensitive drum 27 rotates. , Removed by that brush.

  The fixing unit 18 is provided on the downstream side of the process cartridge 17, is disposed to face the heating roller 41, the heating roller 41, the pressing roller 42 that presses the heating roller 41, and the heating roller 41 and the pressing roller 42. A pair of transport rollers 43 provided on the downstream side are provided.

  The heating roller 41 is made of metal and includes a halogen lamp for heating, and the sheet 3 passes between the heating roller 41 and the pressing roller 42 through the toner image transferred onto the sheet 3 in the process cartridge 17. Then, the sheet 3 is heat-fixed in between, and then the sheet 3 is conveyed to the sheet discharge path 44 by the conveying roller 43. The sheet 3 sent to the sheet discharge path 44 is conveyed to a sheet discharge roller 45 and is discharged onto the sheet discharge tray 46 by the sheet discharge roller 45.

  In the laser printer 1, the residual toner remaining on the surface of the photosensitive drum 27 after being transferred to the sheet 3 by the transfer roller 30 is recovered by the developing roller 31, so that the residual toner is recovered by a so-called cleanerless system. I have to. If the toner remaining on the photosensitive drum 27 is collected by such a cleaner-less method, a toner cleaner device and a waste toner storage unit become unnecessary, and the device configuration can be simplified.

  In addition, the laser printer 1 is provided with a reverse conveyance unit 47 in order to form images on both sides of the paper 3. The reverse conveyance unit 47 includes a paper discharge roller 45, a reverse conveyance path 48, a flapper 49, and a plurality of reverse conveyance rollers 50.

  The paper discharge roller 45 includes a pair of rollers and is configured to be able to switch between forward rotation and reverse rotation. As described above, the paper discharge roller 45 rotates in the forward direction when the paper 3 is discharged onto the paper discharge tray 46, but rotates in the reverse direction when the paper 3 is reversed.

  The reverse conveyance path 48 is provided along the vertical direction so that the paper 3 can be conveyed from the paper discharge roller 45 to a plurality of reverse conveyance rollers 50 disposed below the image forming position. The upstream end is disposed near the paper discharge roller 45, and the downstream end is disposed near the reverse conveyance roller 50.

  The flapper 49 is provided so as to be able to swing so as to face a branch portion between the paper discharge path 44 and the reverse conveyance path 48, and the paper reversed by the paper discharge roller 45 by excitation or non-excitation of a solenoid (not shown). 3 is configured to be able to be switched from the direction toward the paper discharge path 44 to the direction toward the reverse conveyance path 48.

  A plurality of reverse conveyance rollers 50 are provided in a substantially horizontal direction above the paper feed tray 6, and the most upstream reverse conveyance roller 50 is disposed near the rear end of the reverse conveyance path 48, and The most downstream reverse conveying roller 50 is provided so as to be disposed below the registration roller 12.

  When images are formed on both sides of the paper 3, the reverse conveying unit 47 is operated as follows. That is, when the sheet 3 having an image formed on one side is conveyed from the sheet discharge path 44 to the sheet discharge roller 45 by the conveyance roller 43, the sheet discharge roller 45 rotates forward with the sheet 3 interposed therebetween. When the paper 3 is once transported to the outside (the discharge tray 46 side), most of the paper 3 is sent to the outside, and the rear end of the paper 3 is sandwiched between the paper discharge rollers 45, and then rotates forward. To stop. Next, the paper discharge roller 45 rotates in the reverse direction, and the flapper 49 switches the transport direction so that the paper 3 is transported to the reverse transport path 48, and the reverse transport path 48 in the reverse direction of the paper 3. To be transported. When the conveyance of the paper 3 is completed, the flapper 49 is switched to the original state, that is, the state where the paper 3 sent from the conveyance roller 43 is sent to the paper discharge roller 45.

  Next, the sheet 3 conveyed in the reverse direction to the reverse conveyance path 48 is conveyed to the reverse conveyance roller 50, reversed from the reverse conveyance roller 50 in the upward direction, and sent to the registration roller 12. The sheet 3 conveyed to the registration roller 12 is turned upside down and again sent to the image forming position after registration, whereby an image is formed on both sides of the sheet 3.

  In the process cartridge 17 of the laser printer 1, as described above, the metal surfaces 59 at both ends in the axial direction of the metal base tube 53 on the photosensitive drum 27 are attached to the drum cover portion by mounting the flange members 58. 66. Therefore, the shaft end of the roller shaft 75 of the transfer roller 30 with respect to the metal base tube 53 can be easily assembled with a small number of parts without requiring the trouble of winding an insulating sheet around both ends of the metal base tube 53 in the axial direction. The discharge from the portion 77 can be prevented. Moreover, if each flange member 58 is removed from the metal base tube 53, each flange member 58 can also be recycled, and the photosensitive drum 27, especially the metal base tube 53 can be easily recycled (reused). Furthermore, the strength of the axial end portion of the photosensitive drum 27 can be improved by mounting each flange member 58.

  Each flange member 58 is attached to the axial end portion of the metal base tube 53 such that both end portions in the axial direction of the metal base tube 53 are sandwiched between the insertion portion 62 and the drum cover portion 66. . Therefore, simple and reliable attachment / detachment of the flange member 58 to / from the photosensitive drum 27 can be achieved. As a result, the assembly and recycling can be further facilitated.

Each flange member 58 is attached to the metal base tube 53 so as not to be relatively rotatable, and is supported by the drum shaft 55 so as to be relatively rotatable. Therefore, each flange member 58 can also serve as a bearing for the photosensitive drum 27. Therefore, it is possible to reliably support the photosensitive drum 27 while reducing the number of parts and simplifying the configuration.

Since one flange member 58 is provided with a drum gear portion 67, if one flange member 58 is attached to the metal tube 53, a driving force is input to the drum gear portion 67 to rotate the photosensitive drum. Can be made. Therefore, the photosensitive drum 27 can be reliably driven to rotate while reducing the number of parts and simplifying the configuration.

  Further, in the process cartridge 17, also in the transfer roller 30, the shaft end portion 77 of the roller shaft 75 exposed from both end portions in the axial direction of the roller portion 76 is covered by mounting each cover member 78. Therefore, it is possible to easily assemble with a small number of parts and prevent discharge from the shaft end portion 77 of the roller shaft 75 of the transfer roller 30 without requiring the trouble of winding an insulating sheet around each shaft end portion 77. Can do. Further, if each cover member 78 is removed from each shaft end portion 77, the transfer roller 30 can be easily recycled.

  In this process cartridge 17, each flange member 58 covers the metal surface 59 at both ends in the axial direction of the metal base tube 53, and each shaft end 77 is covered by each cover member 78. It is possible to achieve more reliable prevention of discharge between the transfer roller 30 and the transfer roller 30.

  In addition, since one cover member 78 includes a transfer gear portion 79 on the outer side in the axial direction of the cylindrical portion 80, if the one cover member 78 is attached to one axial end portion 77, the cylindrical portion 80 While the roller shaft 75 can be reliably covered, the roller shaft 75 can be rotated by inputting a driving force from the transfer gear portion 79.

  In the above embodiment, the transfer gear portion 79 and the cylindrical portion 80 are formed as separate bodies. However, as shown in FIG. 5, the transfer gear portion 79 and the cylindrical portion 80 are integrally formed. May be. If the transfer gear portion 79 and the cylindrical portion 80 are integrally formed, the number of parts can be reduced and the configuration can be simplified.

  Further, since each cover member 78 includes roller bearing portions 81 and 89 in the middle of the cylindrical portions 80 and 88 in the axial direction, if each cover member 78 is attached to each axial end portion 77, the cylindrical portion 80 and The roller shaft 75 can be supported while the end portions 77 of the shafts can be reliably covered by 88.

  In the above embodiment, the cylindrical portions 80 and 88 and the roller bearing portions 81 and 89 are formed as separate bodies, but as shown in FIGS. 6 (a) and 6 (b). The cylindrical portions 80 and 88 and the roller bearing portions 81 and 89 may be integrally formed. If each cylinder part 80 and 88 and each roller bearing part 81 and 89 are each formed integrally, a number of parts can be reduced and a structure can be simplified.

  Further, in the other cover member 78, the cylindrical portion 88 continuously covers not only the other shaft end portion 77 but also the head portion 86 of the electrode 85. Can be prevented more reliably.

  In the other cover member 78, for example, as shown in FIGS. 7 (a) and 7 (b), an electrode 85 made of a substantially reverse V-shaped plate spring made of a plate spring is connected to the other shaft end. A notch portion 93 is disposed below the portion 77 so as to partially expose the outer peripheral surface of the other shaft end portion 77 so that the cylindrical portion 88 faces the electrode 85. You may open it.

  If the notch 93 is formed in this way, the outer peripheral surface of the other shaft end 77 is partially exposed from the notch 93 while covering the other shaft end 77 in the cylindrical portion 88, The electrode 85 can be brought into elastic contact with the outer peripheral surface. Therefore, the transfer bias can be reliably applied while the other shaft end 77 can be covered.

  In addition, when the notch 93 is opened downward as described above, the position where the notch 93 does not face the axial end of the metal tube 53, more specifically, the metal tube 53. Since it is provided on the opposite side of the position facing the axial end, it is possible to more reliably prevent discharge with the photosensitive drum 27.

  In one cover member 78, the transfer gear portion 79 presses the cylindrical portion 80 inward in the axial direction, and the axially inner end portion of the cylindrical portion 80 is connected to the cylindrical portion 80 in the roller portion 76. It is mounted so as to bite into the opposite end face. Therefore, the roller shaft 75 can be covered with the cylindrical portion 80 without generating a gap with the roller portion 76. As a result, discharge can be reliably prevented by a simple configuration in which the cylindrical portion 80 is bitten into the roller portion 76.

  In addition, each cylinder part 80 and 88 can also be mounted | worn with the roller shaft 75 as shown, for example in FIG. In addition, although the other cylinder part 88 is illustrated in FIG. 8, one cylinder part 80 is applicable similarly.

  That is, in FIG. 8, in the transfer roller 30, the roller portion 76 is bonded to the outer peripheral surface of the roller shaft 75 so that the end facing the cylinder portion 88 is not bonded. Then, the end portion of the cylindrical portion 88 facing the roller portion 76 is inserted into an unbonded portion between the inner peripheral surface of the roller portion 76 and the outer peripheral surface of the roller shaft 75 at the end portion of the roller portion 76. Thus, the cylindrical portion 88 is attached.

  When mounted in this manner, the end portion of the cylindrical portion 88 facing the roller portion 76 is inserted into the unbonded portion between the roller portion 76 and the roller shaft 75 at the end portion of the roller portion 76. Therefore, the roller shaft 75 can be covered with the cylindrical portion 88 without generating a gap with the roller portion 76. Therefore, discharge can be reliably prevented by a simple configuration in which the cylindrical portion 88 is inserted between the roller portion 76 and the roller shaft 75.

  Moreover, each cylinder part 80 and 88 can also be mounted | worn with the roller shaft 75 as shown, for example in FIG. In addition, although the other cylinder part 88 is illustrated in FIG. 9, one cylinder part 80 is applicable similarly.

  That is, in FIG. 9, as shown in FIG. 9B, an annular ridge 94 and a concave portion centering on the central axis of the roller shaft 75 are formed on the end surface of the cylindrical portion 88 facing the roller portion 76. A plurality of strips 95 are formed. Then, as shown in FIG. 9A, the cylindrical portion 88 is mounted so that the end surface on which the convex strip portion 94 and the concave strip portion 95 are formed is pressed against the end surface of the roller portion 76.

  By mounting in this way, the annular ridge 94 and the dent 95 formed on the end surface of the cylindrical portion 88 can be brought into contact with the end surface of the roller portion 76. Therefore, the roller shaft 75 can be covered by the cylindrical portion 88 without causing a gap between the cylindrical portion 88 and the roller portion 76 while reducing friction between the end surface of the cylindrical portion 88 and the end surface of the roller portion 76. Further, creeping leakage of the transfer bias from the roller shaft 75 can be reliably prevented.

  Furthermore, in order to attach each cylindrical part 80 and 88 to the roller shaft 75 without creating a gap between the roller part 76, for example, the embodiment shown in FIGS. 10 to 14 may be illustrated. it can. In addition, although the other cylinder part 88 is illustrated by FIG. 10 thru | or 14, the one cylinder part 80 is applicable similarly.

  That is, first, in the embodiment shown in FIG. 10, the end surface of the roller portion 76 is formed with a concave portion 96 that is recessed in a cylindrical shape around the roller shaft 75 inward in the axial direction of the roller portion 76.

  The cylindrical portion 88 is mounted such that the end of the cylindrical portion 88 enters the recess 96 in the axial direction.

  When mounted in this manner, the cylindrical portion 88 is mounted so that the end portion of the cylindrical portion 88 enters the concave portion 96 of the roller portion 76. Therefore, the cylindrical portion 88 can be arranged so that the roller shaft 75 is not exposed from the direction facing the photosensitive drum 27. As a result, discharge between the photosensitive drum 27 and the photosensitive drum 27 can be reliably prevented with a simple configuration.

  Further, if the recess 96 is formed so as to be recessed in a cylindrical shape around the roller shaft 75, the cylindrical portion 88 is covered so as to be fitted into the recess 96, and the discharge between the photosensitive drum 27 is more reliably performed. Can be prevented.

  In the embodiment shown in FIG. 11, the recess 96 formed on the end surface of the roller portion 76 is formed as an inclined surface that is inclined so as to enter inward in the axial direction from the outer peripheral surface of the roller portion 76 toward the inner peripheral surface. Has been. If the concave portion 96 is formed as an inclined surface, the concave portion 96 can be easily formed, but the cylindrical portion 88 can be covered with the concave portion 96 to prevent discharge between the photosensitive drum 27 and the cylindrical portion 88.

  In the embodiment shown in FIG. 12, the recess 96 formed on the end surface of the roller portion 76 is formed so as to be recessed in a truncated cone shape around the roller shaft 75. If the recess 96 is formed so as to be recessed in the shape of a truncated cone around the roller shaft 75, the cylindrical portion 88 is covered so as to be fitted into the recess 96, and discharge between the photosensitive drum 27 can be performed more reliably. Can be prevented.

  In the embodiment shown in FIG. 13, the end surface of the roller portion 76 is formed with a convex portion 97 projecting in a cylindrical shape around the roller shaft 75 outward in the axial direction of the roller portion 76. The cylindrical portion 88 is formed with an edge cover portion 98 that bulges outward in the radial direction so as to fit the convex portion 97 and covers the convex portion 97 at the end facing the roller portion 76. ing.

  The cylindrical portion 88 is attached so that the edge cover portion 98 of the cylindrical portion 88 covers the convex portion 97 of the roller portion 76 in the axial direction.

  When mounted in this manner, the cylindrical portion 88 is mounted so as to cover the convex portion 97 of the roller portion 76 with the edge cover portion 98, so that a gap is generated between the cylindrical portion 88 and the roller portion 76. The roller shaft 75 can be covered without causing it to occur. As a result, discharge between the photosensitive drum 27 and the photosensitive drum 27 can be prevented more reliably.

  Further, if the convex portion 97 is formed so as to protrude in a cylindrical shape around the roller shaft 75, the convex portion 97 is covered so as to be fitted by the edge cover portion 98, and the roller shaft 75 is covered by the cylindrical portion 88. Can be more reliably coated.

  In the embodiment shown in FIG. 14, the convex portion 97 formed on the end surface of the roller portion 76 is formed so as to protrude in the shape of a truncated cone around the roller shaft 75. Further, the edge cover portion 98 is bulged in an umbrella shape outward in the radial direction so as to be fitted to the convex portion 97. The convex portion 97 is formed so as to protrude in the shape of a truncated cone around the roller shaft 75, and the edge cover portion 98 is bulged in an umbrella shape radially outward so as to fit the convex portion 97. If so, the convex portion 97 can be covered by the edge cover portion 98 and the roller shaft 75 can be more reliably covered by the cylindrical portion 88.

  Further, in the embodiment shown in FIG. 15, an inclined surface in which the convex portion 97 formed on the end surface of the roller portion 76 is inclined so as to protrude outward in the axial direction from the outer peripheral surface of the roller portion 76 toward the inner peripheral surface. It is formed as. The cylindrical portion 88 is mounted such that the end portion of the cylindrical portion 88 contacts the convex portion 97 of the roller portion 76.

  By mounting in this manner, the roller shaft 75 can be reliably covered with the cylindrical portion 88 while the convex portion 97 formed on the end surface of the roller portion 76 can be easily formed.

  As described above, the laser printer includes the process cartridge 17 that can reduce the discharge between the photosensitive drum 27 and the transfer roller 30 and can be easily assembled. Therefore, an image with few transfer defects can be formed, and the image can be manufactured with high production efficiency.

  In the above-described embodiment, the process cartridge 17 that is detachably attached to the main casing 2 is provided, and the developing cartridge 28, the photosensitive drum 27, the scorotron charger 29, the transfer roller 30, and the conductive film are provided in the process cartridge 17. Although various members such as the property brush 52 are provided, some of these members may be provided directly on the main body casing 2 side without being provided on the process cartridge 17 side. Instead, these various members may be provided directly on the main casing 2 side.

  In the above-described embodiment, the metal surface 59 exposed on the outer peripheral surfaces of the both ends in the axial direction of the metal base tube 53 is covered with the drum cover portion 66 of the flange member 58 in the photosensitive drum 27. In the case where the metal surface 59 is exposed in a ring shape at the end surfaces of both ends of the metal base tube 53 in the axial direction instead of the outer peripheral surfaces of both ends of the metal base tube 53 in the axial direction, the flange member 58 is at least Any shape that can cover the metal surface 59 exposed in a ring shape at the end face is acceptable, and it does not necessarily have to be a shape that can cover the outer peripheral surfaces of both ends of the metal base tube 53 in the axial direction. Further, when covering the end faces of both ends of the metal base tube 53 in the axial direction, the flange member 58 is preferably formed to have a diameter slightly larger than the outer diameter of the metal base tube 53.

1 is a side sectional view of an essential part showing an embodiment of a laser printer as an image forming apparatus of the present invention. FIG. 2 is a front sectional view of a main part of a process cartridge of the laser printer shown in FIG. 1. FIG. 3 is an enlarged front sectional view of one side of the process cartridge shown in FIG. 2. FIG. 3 is an enlarged front sectional view of the other side of the process cartridge shown in FIG. 2. In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect with which the transfer gear and the cylinder part were integrally formed) of one cover member. In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect in which the cylinder part and the roller bearing part are integrally formed), (a) is a cover of one side. Member (b) shows the cover member on the other side. FIG. 2 shows another embodiment of the process cartridge shown in FIG. 2 (an embodiment in which a notch is formed in the cylindrical portion), where (a) is a front view of the main part, and (b) is a side view. Indicates. In the process cartridge shown in FIG. 2, it is sectional drawing of other embodiment (The aspect which inserts the edge part of a cylinder part between the internal peripheral surface of a roller part, and the outer peripheral surface of a roller axis | shaft). In the process cartridge shown in FIG. 2, another embodiment of the cover member (a mode in which the end surface on which the protruding portion and the recessed portion in the cylindrical portion are formed is pressed against the end surface of the roller portion), (a) These are sectional drawings of the mounting state of a cylinder part, (b) is a perspective view of a cylinder part. In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect by which the recessed part hollow in a cylindrical shape is formed in the end surface of a roller part). In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect by which the recessed part is formed in the end surface of a roller part as an inclined surface hollow in an axial direction inside). In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect by which the recessed part recessed in a truncated cone shape is formed in the end surface of a roller part). In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect by which the convex part which protrudes cylindrically is formed in the end surface of a roller part). In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect by which the convex part which protrudes in a truncated cone shape is formed in the end surface of a roller part). In the process cartridge shown in FIG. 2, it is sectional drawing which shows other embodiment (The aspect by which the convex part is formed in the end surface of a roller part as an inclined surface which protrudes to an axial direction outward).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 3 Paper 17 Process cartridge 27 Photosensitive drum 30 Transfer roller 53 Metal elementary tube 54 Photosensitive layer 55 Drum shaft 58 Flange member 62 Insertion part 66 Drum cover part 67 Drum gear part 75 Roller shaft 76 Roller part 78 Cover member 79 Transfer gear part 80 cylindrical part 81 roller bearing part 85 electrode 88 cylindrical part 89 roller bearing part 93 notch part 94 convex part 95 concave part 96 concave part 97 convex part 98 edge cover part

Claims (27)

A process cartridge comprising: a conductive substrate; and a photosensitive member formed on the conductive substrate so that a longitudinal end portion of the conductive substrate is exposed. The process cartridge is detachably mounted on an image forming apparatus. In
A process cartridge comprising a flange member mounted on a longitudinal end portion of the photoconductor so as to cover a longitudinal end portion of the conductive substrate and formed of an insulating material. The conductive substrate is formed in a cylindrical shape,
The flange member is disposed on the radially inner side of the conductive substrate and the cover disposed on the radially outer side of the conductive substrate and sandwiches the end of the conductive substrate between the inserted member and the flange member. The process cartridge according to claim 1, wherein the process cartridge includes a portion. The conductive substrate is formed in a cylindrical shape,
The photoreceptor has a photoreceptor axis along a central axis of the conductive substrate;
The flange member is attached to the conductive base member so as not to rotate relative to the conductive substrate, and the photosensitive member shaft is inserted through the flange member and supported relative to the photosensitive member shaft. The process cartridge according to 1 or 2. The conductive substrate is formed in a cylindrical shape,
4. The process cartridge according to claim 1, wherein the flange member has a gear portion to which a driving force for rotating the conductive substrate around a central axis is input. 5. . A conductive shaft disposed opposite to the photosensitive member and extending along the longitudinal direction of the photosensitive member, and a roller portion formed on the outer peripheral surface of the shaft so that an axial end portion of the shaft is exposed. A transfer means for transferring a developer image carried on the photosensitive layer to a transfer medium by applying a transfer bias;
5. A cover member mounted on an axial end portion of the shaft so as to cover the axial end portion and formed of an insulating material. Process cartridge. A process comprising a photosensitive substrate having a conductive substrate and a photosensitive layer formed on the conductive substrate so that a longitudinal end portion of the conductive substrate is exposed, and is detachably attached to the image forming apparatus. In the cartridge,
A conductive shaft disposed opposite to the photosensitive member and extending along the longitudinal direction of the photosensitive member, and a roller portion formed on the outer peripheral surface of the shaft so that an axial end portion of the shaft is exposed. A transfer means for transferring a developer image carried on the photosensitive layer to a transfer medium by applying a transfer bias;
A process cartridge comprising: a cover member mounted on an axial end portion of the shaft so as to cover the axial end portion and formed of an insulating material.   The cover member is formed longer than a portion of the shaft exposed from the roller portion, and an end portion of the cover member facing the roller portion in the axial direction of the shaft is the cover of the roller portion. The process cartridge according to claim 5, wherein the process cartridge is mounted so as to bite into an end surface facing the portion. The roller portion is bonded to the outer peripheral surface of the shaft so that the end portion facing the cover member does not bond,
The cover member is inserted into an unbonded portion between the roller portion and the shaft at an end portion facing the roller portion in the axial direction of the shaft. The process cartridge according to claim 5, wherein the process cartridge is attached to the cartridge.   The cover member is positioned closer to the roller portion than the transfer gear portion in the axial direction of the transfer gear portion to which a driving force for rotating the shaft is input, and the shaft is inserted therethrough. 9. The process cartridge according to claim 5, further comprising a cylinder portion to be processed.   The process cartridge according to claim 9, wherein the transfer gear portion and the cylindrical portion are integrally formed.   10. The process cartridge according to claim 5, wherein the cover member has a cylindrical portion through which the shaft is inserted, and a bearing portion that rotatably receives the shaft. 11.   The process cartridge according to claim 11, wherein the cylindrical portion and the bearing portion are integrally formed.   In the cover member, in the axial direction of the shaft, at least one of an annular ridge portion and a ridge portion centering on the central axis of the shaft is formed on an end surface facing the roller portion. The process cartridge according to claim 5, wherein the process cartridge is characterized in that An electrode for applying a transfer bias to the transfer means in contact with the axial end surface of the shaft;
The process cartridge according to claim 5, wherein the cover member is mounted so as to continuously cover the electrode and the axial end of the shaft. An electrode for applying a transfer bias to the transfer means;
14. The cover member according to claim 5, wherein the cover member has a notch for partially exposing an outer peripheral surface of the shaft and contacting the electrode with the exposed portion. The process cartridge according to the above.   The process cartridge according to claim 15, wherein the cutout portion is formed at a position of the cover member that does not face the photoconductor. In the axial direction of the shaft, a recess recessed inward of the roller portion is formed on the end surface of the roller portion,
The said cover member is mounted | worn with the edge part which opposes the end surface of the said roller part so that it may enter in the said recessed part in the axial direction of the said axis | shaft. Process cartridge.   The process cartridge according to claim 17, wherein the recess is formed to be recessed in a cylindrical shape around the shaft.   The process cartridge according to claim 17, wherein the recess is formed as an inclined surface that is inclined so as to enter the inside of the roller portion from the outer peripheral surface of the roller portion toward the inner peripheral surface. .   The process cartridge according to claim 17, wherein the recess is formed to be recessed in a truncated cone shape around the shaft. In the axial direction of the shaft, a convex portion protruding outward of the roller portion is formed on the end surface of the roller portion,
In the axial direction of the shaft, the cover member has an edge cover portion that covers the convex portion so as to fit the convex portion at an end portion facing the roller portion. The process cartridge according to claim 5.   The process cartridge according to claim 21, wherein the convex portion is formed so as to protrude in a cylindrical shape around the shaft.   The process cartridge according to claim 21, wherein the convex portion is formed so as to protrude in a truncated cone shape around the shaft.   The end surface of the roller portion in the axial direction of the shaft is formed as an inclined surface that is inclined so as to protrude outward from the outer peripheral surface of the roller portion toward the inner peripheral surface. The process cartridge according to any one of claims 5 to 16.   An image forming apparatus comprising the process cartridge according to any one of claims 1 to 24. A photosensitive member having a conductive substrate, a photosensitive layer formed on the conductive substrate so that a longitudinal end portion of the conductive substrate is exposed, and a developing unit that supplies a developer to the photosensitive member. In the provided image forming apparatus,
An image forming apparatus comprising a flange member attached to a longitudinal end portion of the photosensitive member so as to cover a longitudinal end portion of the conductive substrate and formed of an insulating material. A conductive shaft that is disposed to face the photoconductor and extends along the longitudinal direction of the photoconductor, and a roller portion that is formed so that an axial end of the shaft is exposed on the outer peripheral surface of the shaft. And a transfer means for transferring the developer image carried on the photosensitive layer to a transfer medium by applying a transfer bias,
27. The image forming apparatus according to claim 26, further comprising a cover member that is attached to an axial end portion of the shaft so as to cover the axial end portion and is formed of an insulating material.

Images