JP2012113214A - Shaft bearing retainer and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shaft bearing retainer that can highly-accurately position a rotor such as a photoreceptor drum and also is excellent in an attaching/detaching workability to a bearing member of a rotary shaft of the rotor.SOLUTION: A shaft bearing retainer 200 has a cylindrical shape hollow from one end to the other. The shaft bearing retainer 200 is also provided with a bearing member 210, recesses 220A to D, and protrusions 230A to D. The bearing member 210 is disposed on an inner surface of the shaft bearing retainer 200 to pivotally support a photoreceptor drum rotary shaft 12. The recesses 220A to D are formed on an outer surface of the shaft bearing retainer 200 along the circumferential direction. The protrusions 230A to D are formed between the respective recesses 220A to D.

Description

  The present invention relates to a bearing cage in which a bearing is disposed on an inner surface and an image forming apparatus including the bearing cage.

  In an image forming apparatus such as a copying machine or a printer, a static electricity is charged around a photosensitive drum using a charger that charges the photosensitive drum and a laser beam based on image information supplied from an image reading system. An exposure unit that forms an electrostatic latent image, a developing unit that forms a visible image by attaching toner to the electrostatic latent image formed on the photosensitive drum by the laser scanning device, and a toner image on the photosensitive drum A transfer unit for transferring the toner, a separation device for separating the photosensitive drum and the sheet, a cleaner unit for cleaning the photosensitive drum, a static elimination device for eliminating the residual charge on the photosensitive drum, and the like. .

  Both ends of the rotation shaft of the photosensitive drum are pivotally supported by bearing members provided on the main body frame of the image forming apparatus. Then, both ends of the rotating shaft of the photosensitive drum are detachably inserted into corresponding bearing members in order to make the photosensitive drum detachable from the main body frame.

  In such an image forming apparatus, for example, the gap between the photosensitive drum and the developing device greatly affects the image quality, and it is important to suppress the gap deviation within a predetermined range. For this reason, the photosensitive drum needs to be positioned with high accuracy with respect to various devices around the photosensitive drum.

  Accordingly, a roller bearing is disclosed that can position the bearing body in the thrust direction and prevent the bearing body from moving in the thrust direction without providing any special fixing means (see, for example, Patent Document 1). .

JP 2008-232278 A

  In the electrophotographic image forming apparatus, a slight clearance is provided between the end of the rotating shaft of the photosensitive drum and the bearing member so as to be detachably inserted into the bearing member. Therefore, the photosensitive drum may be displaced in the thrust direction after the image forming apparatus is assembled. In a so-called tandem type color image forming apparatus, when transferring a toner image, it is important that images of respective colors are accurately transferred onto a sheet. However, if the photosensitive drum is displaced in the thrust direction, Overlap shifts and color shift occurs in the formed color image. Further, the deviation in parallelism between the plurality of photosensitive drums is also related to the color deviation.

  If the clearance between the end of the rotating shaft of the photosensitive drum and the bearing member is made more than necessary, the smoothness of the rotating photosensitive drum is reduced. In addition, since the end of the rotating shaft of the photosensitive drum is configured to penetrate the bearing member, there is a problem in that the workability of attaching / detaching the rotating shaft of the photosensitive drum from the bearing member is reduced when the photosensitive drum is replaced. was there. This problem cannot be solved by Patent Document 1.

  In view of the above problems, an object of the present invention is to provide a bearing cage that can position a rotating body such as a photosensitive drum with high accuracy and has excellent workability for attaching and detaching a rotating shaft to a bearing member. It is in.

  The bearing cage of the present invention has a cylindrical shape penetrating from one end to the other end. The bearing cage of the present invention includes a bearing member, a plurality of concave portions, and a plurality of convex portions.

  The bearing member is disposed on the inner surface of the bearing cage body and pivotally supports the rotating shaft of the rotating body. The plurality of recesses are formed along the circumferential direction on the outer peripheral surface of the bearing cage body. The plurality of convex portions are formed between the respective concave portions.

  The bearing cage in this configuration is useful when used for the photosensitive drum rotating shaft. That is, when the user attaches / detaches the photosensitive drum rotation shaft to / from the photosensitive drum rotation shaft and when the user attaches / detaches the photosensitive drum rotation shaft to / from the bearing cage, the entire bearing cage is formed by the recess of the bearing cage. Is easier to grasp. Therefore, workability at the time of attaching / detaching each member is improved and safety at the time of attaching / detaching each member is also improved.

  Further, the bearing cage is firmly held with respect to the main body frame of the image forming apparatus by the convex portion of the bearing cage. Accordingly, the bearing cage is prevented from rotating or moving in the thrust direction caused by the rotation of the photosensitive drum rotating shaft, so that the photosensitive drum rotating shaft can be supported at a predetermined position.

  The bearing cage in the present invention can position a rotating body such as a photosensitive drum with high accuracy, and is excellent in detachable workability of the rotating body with respect to the bearing member.

It is a figure which shows the structure of an image forming apparatus provided with the bearing holder which concerns on embodiment of this invention. It is a figure which shows the state in which the bearing holder which concerns on embodiment of this invention is attached to the edge part of the photoreceptor drum rotating shaft. It is a perspective view which shows the structure of the bearing cage which concerns on embodiment of this invention. It is a perspective view which shows the structure of the bearing cage which concerns on embodiment of this invention. It is a perspective view showing the state where the bearing retainer concerning the embodiment of the present invention is inserted in the main part frame. It is sectional drawing which shows the structure of the bearing cage which concerns on embodiment of this invention. It is a perspective view which shows the state by which the embossing is given to the recessed part in the bearing holder which concerns on embodiment of this invention. It is a perspective view which shows the state in which the knurling process is given to the recessed part in the bearing holder which concerns on embodiment of this invention.

  Hereinafter, a bearing retainer according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 100 including a bearing cage 200 according to an embodiment of the present invention.

  The image forming apparatus 100 forms a multi-color or single-color image on a predetermined sheet (recording paper) in accordance with image data transmitted from the outside. The image forming apparatus 100 includes a document processing device 120, a paper feeding unit 80, an image forming unit 110, and a paper discharge unit 90.

  The document processing device 120 includes a document placement table 121, a document transport device 122, and a document reading unit 123. The document placing table 121 is made of transparent glass and is configured to be able to place a document. The document transport device 122 transports the documents stacked on the document tray one by one. Further, the document conveying device 122 is configured to be rotatable in the direction of the arrow 124, and the document can be placed on the document placing table 121 by opening the document placing table 121. The document reading unit 123 reads a document being transported by the document transport device 122 or a document placed on the document placing table 122.

  The paper feed unit 80 is provided with a paper feed cassette 81, a manual paper feed cassette 82, a pickup roller 83, and a pickup roller 84. The paper feed cassette 81 is a tray for storing regular sheets. The manual paper feed cassette 82 is a tray on which an irregular sheet can be placed. The pickup roller 83 is provided near the end of the paper feed cassette 81, picks up sheets one by one from the paper feed cassette 81, and supplies them to the paper transport path 101. Similarly, the pickup roller 84 is provided in the vicinity of the end of the manual paper feed cassette 82, picks up sheets one by one from the manual paper feed cassette 82, and supplies them to the paper transport path 101.

  The image forming unit 110 includes image forming stations 31, 32, 33, 34, an exposure unit 30, an intermediate transfer belt unit 50, and a fixing unit 70. Each of the image forming stations 31, 32, 33, and 34 is provided with a photosensitive drum 10, a charger 20, a developing device 40, and a cleaner unit 60. Black (K), cyan (C), magenta (M), and magenta (M) are provided. This corresponds to a color image using each color of yellow (Y). In the present embodiment, the image forming station 31 will be described.

  The photoconductor drum 10 is rotated when an image is formed and carries a developer image. A bearing cage 200 is attached to the end of the rotating shaft 12 of the photosensitive drum 10. The bearing cage 200 will be described with reference to FIG. Around the photosensitive drum 10, the charger 20, the exposure unit 30, the developing device 40, the intermediate transfer belt unit 50, and the cleaner unit 60 are arranged in this order from the upstream in the rotation direction. The fixing unit 70 is positioned on the most downstream side of the image forming unit 110 on the conveyance path 101.

  The charger 20 is a charging means for uniformly charging the surface of the photosensitive drum 10 to a predetermined potential. In addition to the charger type as shown in FIG. 1, a contact type roller type or brush type charger is used. Sometimes used.

  The exposure unit 30 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 10 according to the input image data. The exposure unit 30 is configured as a laser scanning unit (LSU) provided with a laser emitting portion, a reflection mirror, and the like. The exposure unit 30 includes a polygon mirror that scans the laser beam and optical elements such as a lens and a mirror that guide the laser beam reflected by the polygon mirror to the photosensitive drum 10. As the exposure unit 30, for example, a method using an EL or LED writing head in which other light emitting elements are arranged in an array can also be adopted.

  The developing device 40 visualizes the electrostatic latent image formed on the photosensitive drum 10 with toner.

  The intermediate transfer belt unit 50 includes an intermediate transfer belt 51, an intermediate transfer belt drive roller 52, an intermediate transfer belt driven roller 53, an intermediate transfer roller 54, and an intermediate transfer belt cleaning unit 55.

  The intermediate transfer belt driving roller 52, the intermediate transfer belt driven roller 53, and the intermediate transfer roller 54 are driven to rotate while the intermediate transfer belt 51 is stretched. Further, the intermediate transfer roller 54 gives a transfer bias for transferring the toner image on the photosensitive drum 10 onto the intermediate transfer belt 51.

  The intermediate transfer belt 51 is provided in contact with the photosensitive drum 10. The toner image formed on the photosensitive drum 10 is transferred to the intermediate transfer belt 51, thereby forming a toner image on the intermediate transfer belt 51. The intermediate transfer belt 51 is formed in an endless shape using, for example, a film having a thickness of about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 10 to the intermediate transfer belt 51 is performed by an intermediate transfer roller 54 that is in contact with the back side of the intermediate transfer belt 51. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 54 in order to transfer the toner image. The intermediate transfer roller 54 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 mm to 10 mm, and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 51. In this embodiment, a roller shape is used as the transfer electrode, but a brush or the like can also be used.

  The electrostatic latent images visualized on the photosensitive drum 10 as described above are stacked on the intermediate transfer belt 51. The image information stacked in this way is transferred onto the sheet by the transfer roller 56 disposed at the contact position between the sheet and the intermediate transfer belt 51 as the intermediate transfer belt 51 rotates.

  At this time, the intermediate transfer belt 51 and the transfer roller 56 are pressed against each other at a predetermined nip, and a voltage for transferring the toner onto the paper is applied to the transfer roller 56 (the polarity opposite to the toner charging polarity (−)). (+) High voltage). Further, in order to obtain the nip constantly, the transfer roller 56 uses either the transfer roller 56 or the intermediate transfer belt drive roller 52 as a hard material (metal or the like) and the other as a soft material such as an elastic roller (elastic rubber roller). Or a foaming resin roller or the like.

  Further, as described above, the toner adhered to the intermediate transfer belt 51 by contacting the photosensitive drum 10 or the toner remaining on the intermediate transfer belt 51 without being transferred onto the sheet by the transfer roller 56 is transferred to the intermediate transfer belt 51. It is set to be removed and collected by the cleaning unit 55. The intermediate transfer belt cleaning unit 55 is provided with, for example, a cleaning blade that contacts the intermediate transfer belt 51 as a cleaning member. The intermediate transfer belt 51 that contacts the cleaning blade is supported by an intermediate transfer belt driven roller 53 from the back side. ing.

  The cleaner unit 60 removes and collects toner remaining on the surface of the photosensitive drum 10 after development and image transfer.

  The fixing unit 70 includes a heating roller 71 and a pressure roller 72, and the heating roller 71 and the pressure roller 72 rotate with the sheet interposed therebetween. The heating roller 71 is set so as to reach a predetermined fixing temperature by a control unit based on a signal from a temperature detector (not shown), and the toner is thermocompression bonded to the sheet together with the pressure roller 72. It has a function of fusing, mixing, and pressing the transferred toner image and thermally fixing the sheet. An external heating belt 73 for heating the heating roller 71 from the outside is provided.

  The paper discharge unit 90 includes a paper discharge tray 91 and a paper discharge roller 92. The sheet that has passed through the fixing unit 70 is discharged to a discharge tray 91 via a discharge roller 92. The paper discharge tray 91 is a tray for collecting printed sheets.

  When a double-sided printing request is made, when the single-sided printing is completed and the trailing edge of the sheet that has passed through the fixing unit 70 is gripped by the paper discharging roller 92 as described above, the paper discharging roller 92 rotates in the reverse direction. The sheet is guided to the conveyance rollers 102 and 103. Then, after printing is performed on the back side of the sheet through the registration roller 104, the sheet is discharged to the discharge tray 91.

  FIG. 2 is a view showing a state in which the bearing cage 200 according to the embodiment of the present invention is attached to the end portion of the photosensitive drum rotating shaft 12.

  In FIG. 2, the photosensitive drum 10 is omitted to show a state in which the bearing cage 200 is attached to the end of the photosensitive drum rotating shaft 12. The members related to the photosensitive drum 10 correspond to the photosensitive drum rotating shaft 12, the drive transmission gear 14, and the bearing holder 200.

  The photosensitive drum rotating shaft 12 has a screw hole 16. The screw hole 16 is a hole provided to fix the photosensitive drum 10 to the photosensitive drum rotating shaft 12. A screw hole is provided at the end of the photosensitive drum 10, and the photosensitive drum 10 is fixed to the photosensitive drum rotating shaft 12 by connecting the screw hole of the photosensitive drum 10 and the screw hole 16 with a screw. To do. When the screw hole between the screw hole of the photosensitive drum 10 and the screw hole 16 is released, the photosensitive drum 10 can be detached from the photosensitive drum rotating shaft 12.

  The photosensitive drum rotating shaft 12 is inserted into the photosensitive drum 10 and has a function of rotating the photosensitive drum 10. The drive transmission gear 14 is a gear for transmitting a driving force from a driving motor (not shown) to the photosensitive drum rotating shaft 12. The bearing cage 200 has a cylindrical shape penetrating from one end to the other end. Further, the bearing holders 200 are respectively attached to both ends of the photosensitive drum rotating shaft 12 and inserted into fixed positions of the main body frame 130 to have a function of positioning the photosensitive drum rotating shaft 12.

  3 and 4 are perspective views showing the configuration of the bearing cage 200 according to the embodiment of the present invention.

  The bearing cage 200 includes a bearing member 210, concave portions 220A to 220D, convex portions 230A to D, stoppers 240A and B, and shaft support members 250A and 250B.

  The bearing member 210 is disposed on the inner surface of the bearing cage 200 and supports the photosensitive drum rotating shaft 12. The photosensitive drum 10 corresponds to a rotating body of the present invention. Recesses 220 </ b> A to 220 </ b> D are formed along the circumferential direction on the outer peripheral surface of bearing cage 200. The convex portions 230A to 230D are formed between the respective concave portions (for example, the concave portion 220A and the concave portion 220B). The stoppers 240 </ b> A and B have a function of preventing the bearing holder 200 from being inserted into the main body frame 130 when the bearing holder 200 is inserted into the main body frame 130. The shaft support members 250 </ b> A and 250 </ b> B have a function of supporting the photosensitive drum rotating shaft 12 that is pivotally supported by the bearing member 210.

  In this configuration, when the user attaches / detaches the photosensitive drum 10 to / from the photosensitive drum rotating shaft 12 and when the user attaches / detaches the photosensitive drum rotating shaft 12 to / from the bearing holder 200, the bearing holder 200. The recesses 220 </ b> A to 220 </ b> D make it easy to grip the entire bearing cage 200. Therefore, workability at the time of attaching / detaching each member is improved and safety at the time of attaching / detaching each member is also improved.

  In the present embodiment, the photosensitive drum 10 is described as an example of the rotating body of the present invention, but the present invention is not limited to this. Other examples of the rotating body include a heating roller 71 and a pressure roller 72, for example.

  FIG. 5 is a perspective view showing a state in which the bearing cage 200 according to the embodiment of the present invention is inserted into the main body frame 130.

  Since the bearing cage 200 includes the recesses 220A to D on the outer peripheral surface, if the bearing cage 200 is inserted into the hole 132 as it is without the projections 230A to D, the bearing cage 200 is related to the recesses 220A to D. There is a difference between the outer diameter and the diameter of the hole 132. Therefore, by providing the protrusions 230A to 230D, the diameter of the hole 132 and the outer diameter of the protrusions 230A to 230D can be made substantially the same, so that the bearing cage 200 rattles the hole 132. Can be prevented.

  Further, the bearing holder 200 is firmly held with respect to the main body frame 130 of the image forming apparatus 100 by the convex portions 230 </ b> A to 230 </ b> D of the bearing holder 200. Accordingly, the rotation of the photosensitive drum rotating shaft 12 prevents the bearing holder 200 from being rotated and moved in the thrust direction, so that the photosensitive drum rotating shaft 12 can be supported at a predetermined position.

  FIG. 6 is a cross-sectional view showing the configuration of the bearing cage 200 according to the embodiment of the present invention.

  As long as the recesses 220 </ b> A to 220 </ b> D are formed in the circumferential direction on the outer peripheral surface of the bearing cage 200, the circumferential length and the arrangement interval in the bearing cage 200 may be in any form. However, as shown in FIG. 6, it is preferable that the recesses 220 </ b> A to 220 </ b> D have the same circumferential length in the bearing cage 200 and are arranged at equal intervals.

  In this configuration, when the user attaches / detaches the photosensitive drum 10 to / from the photosensitive drum rotating shaft 12 and when the user attaches / detaches the photosensitive drum rotating shaft 12 to / from the bearing holder 200, the bearing holder 200. The recesses 220A to 220D make it easier to grip the entire bearing cage 200. Therefore, the workability when attaching / detaching each member is further improved, and the safety when attaching / detaching each member is further improved.

  Further, the convex portions (230A to D in the present embodiment) may be any number of locations as long as they are two or more on the outer peripheral surface of the bearing cage 200, as shown in FIG. As described above, when the concave portions 220A to D are arranged at equal intervals in addition to the circumferential lengths of the bearing cage 200 being all equal and equally spaced, the concave portions 220A to D are arranged at four locations. preferable.

  In this configuration, since the convex portions 230A to 230D are arranged at intervals of 90 degrees in the circumferential direction on the outer peripheral surface of the bearing cage 200, the balance with respect to the holes 132 in the main body frame 130 of the image forming apparatus 100 is good. The bearing cage 200 is held more firmly with respect to the main body frame 130. Accordingly, the rotation of the bearing drum 200 caused by the rotation of the photosensitive drum rotating shaft 12 is effectively prevented from being rotated or moved in the thrust direction, so that the photosensitive drum rotating shaft 12 can be supported at a predetermined position.

  Further, the recesses 220A to 220D may have any length in the circumferential direction of the bearing cage 200, but as shown in FIG. 6, the recesses 220A to D are formed of the protrusions 230A to 230D. It is preferable that it is formed longer than the length.

  In this configuration, when the user attaches / detaches the photosensitive drum 10 to / from the photosensitive drum rotating shaft 12 and when the user attaches / detaches the photosensitive drum rotating shaft 12 to / from the bearing holder 200, the bearing holder 200. The recesses 220A to 220D make it easier to grip the entire bearing cage 200. Therefore, the workability when attaching / detaching each member is further improved, and the safety when attaching / detaching each member is further improved.

  FIG. 7 is a perspective view showing a state in which the concave portions 220A to 220D in the bearing retainer 200 according to the embodiment of the present invention are subjected to embossing.

  As long as the recesses 220A to 220D are formed along the circumferential direction on the outer peripheral surface of the bearing cage 200, there is no essential condition. However, as shown in FIG. It is preferable that processing is performed.

  In this configuration, when the user attaches / detaches the photosensitive drum 10 to / from the photosensitive drum rotating shaft 12 and when the user attaches / detaches the photosensitive drum rotating shaft 12 to / from the bearing holder 200, the bearing holder 200. The hand becomes difficult to slip due to the texture processing in the recesses 220A to 220D. Therefore, the workability when attaching / detaching each member is further improved, and the safety when attaching / detaching each member is further improved.

  FIG. 8 is a perspective view showing a state in which knurling is performed on the recesses 220A to 220D in the bearing cage 200 according to the embodiment of the present invention.

  If the recesses 220A to 220D are formed along the circumferential direction on the outer peripheral surface of the bearing cage 200, there is no essential condition in addition thereto, but the recesses 220A to 220D are knurled as shown in FIG. It is preferable that processing is performed.

  In this configuration, when the user attaches / detaches the photosensitive drum 10 to / from the photosensitive drum rotating shaft 12 and when the user attaches / detaches the photosensitive drum rotating shaft 12 to / from the bearing holder 200, the bearing holder 200. The knurling in the recesses 220A to 220D makes it difficult for the hand to slip. Therefore, the workability when attaching / detaching each member is further improved, and the safety when attaching / detaching each member is further improved.

  Moreover, the bearing member 210 may be comprised from a slide bearing, may be comprised from a ball bearing, and may be comprised from a roller bearing. As described above, the bearing member 210 used in the present embodiment is not limited in the type of bearing, and therefore, the type of bearing can be arbitrarily selected according to the application.

  Finally, the description of the above-described embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 10-Photoconductor drum 12-Photoconductor drum rotating shaft 100-Image forming apparatus 110-Image forming part 200-Bearing holder 210-Bearing member 220A-Concave part 220B-Concave part 220C-Concave part 220D-Concave part 230A-Convex part 230B-Convex part Part 230C-convex part 230D-convex part

Claims (10)

A cylindrical bearing retainer penetrating from one end to the other end,
A bearing member that is disposed on the inner surface of the bearing cage body and supports the rotating shaft of the rotating body;
A plurality of recesses formed along the circumferential direction on the outer peripheral surface of the bearing cage body;
A plurality of convex portions formed between the respective concave portions;
Bearing retainer. The bearing retainer according to claim 1, wherein the recesses are all equal in circumferential length in the bearing retainer main body and are arranged at equal intervals. The bearing holder according to claim 2, wherein the convex portions are arranged at four locations. The bearing retainer according to any one of claims 1 to 3, wherein the concave portion is formed such that a circumferential length of the bearing retainer body is longer than a length of the convex portion. The bearing retainer according to any one of claims 1 to 4, wherein the concave portion is textured. The bearing retainer according to claim 1, wherein the concave portion is knurled. The bearing retainer according to any one of claims 1 to 6, wherein the bearing member includes a plain bearing. The bearing retainer according to any one of claims 1 to 6, wherein the bearing member includes a ball bearing. The bearing retainer according to any one of claims 1 to 6, wherein the bearing member includes a roller bearing. An image forming unit that forms an image on a sheet;
The bearing cage according to any one of claims 1 to 9, which supports a rotating shaft of a photosensitive drum included in the image forming unit.
An image forming apparatus comprising:

Images