JP2010002737A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device for adjusting a clearance between a photosensitive member drum and a developing roller by a simple structure. <P>SOLUTION: This image forming device is constituted by arranging a roller 211 in either 210 (200) of a photosensitive member side member 200 and a developing device side member 210 and arranging a roller receiving part 202 for receiving the roller 211 to advance and retract when either 210 (200) of them is shifted and joined with the other 200 (210) of them in the other of them. The roller 202 includes a plurality of circular-arc face parts 211A, 211B, 211C formed by dividing the roller 202 around its shaft and being different in diameter from each other. A roller applying face 401 coming into contact with one circular-arc face part 211A (211B), (211C) selected from among the circular-arc face parts 211A, 211B, 211C is formed in the roller receiving part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus to which an electrophotographic system such as a copying machine, a fax machine, a printer, or the like is applied, and more particularly to a technique for adjusting a gap (distance) between a photosensitive drum and a developing roller. .

  The imaging unit, which is also the main part of the image forming apparatus, is configured so that the photosensitive member side member incorporating the photosensitive drum and the developing device side member incorporating the developing roller are detachably joined for the sake of manufacturing and maintenance. It has become.

  On the other hand, when forming an image, the image quality cannot be stabilized unless the gap between the photosensitive drum and the developing roller is constant. For this reason, the image unit is devised in various ways to keep the gap between the photosensitive drum and the developing roller constant.

  As a conventional imaging unit, for example, as shown in FIG. 6, a roller 601 is mounted on a rotating shaft 604 of a developing roller (not shown), while a roller 700 having a U-shaped side view is mounted on a member 700 in which a photosensitive drum 701 is incorporated. In some cases, a groove 602 is provided, and a gap adjusting member 603 such as a PET sheet is sandwiched between the inner surfaces of the groove 602 in order to adjust the gap between the photosensitive drum 701 and the developing roller.

  In addition, as a means for adjusting and managing the gap between the photosensitive drum and the developing roller, a positioning member for adjusting the gap is slidably disposed on the supporting member of the photosensitive drum, and a long hole formed in the positioning member is inserted. There has been proposed a configuration in which a slide position of the positioning member can be adjusted with a screw screwed to a support member (see, for example, Patent Document 1).

Further, by disposing conical rollers between the photosensitive drum and the developing roller and on both ends in the axial direction, respectively, and changing both the conical shapes in the axial direction of the developing roller, A technique for adjusting the gap between the photosensitive drum and the developing roller is disclosed (for example, see Patent Document 2).
JP 2005-43486 A JP 2003-156915 A

  However, the conventional structure shown in FIG. 6 is configured such that the gap adjusting member 603 is sandwiched between the inner surfaces of the groove portions 602 on the photoconductor side member 700 side that receives the roller 601 on the developing roller side. While replacing the adjustment member 603, one optimum gap adjustment member must be selected, which requires time and effort for the gap adjustment work.

  Further, in the technique of Patent Document 1, a special positioning member must be slidably attached, and the structure and the like are inevitable.

  Furthermore, in the technique of Patent Document 2, the conical rollers at both ends in the axial direction are held so as to be movable in the axial direction, and the two rollers must be displaced by the same amount, thereby complicating the structure. Invite.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus that can easily adjust the gap between the photosensitive drum and the developing roller with a simple structure.

  The above problem is solved by the following means.

[1] In an image forming apparatus in which a photoconductor side member in which a photoconductor drum is incorporated and a developing device side member in which a developing roller is incorporated are detachably arranged.
Either one of the photosensitive member side member and the developing device side member is provided with a positioning roller, and the other is provided with a roller receiving portion that receives the roller so that the roller can be moved forward and backward when the one is joined. And
The roller is rotatably supported around the axis of the photosensitive drum or the developing roller, and is provided with a plurality of arcuate surface portions that are divided around the axis and have different diameters.
The roller receiving portion has an arc convex surface centered on the axis of the photosensitive drum or the developing roller, and is formed with a roller contact surface that contacts any one of the plurality of arc surface portions of the roller. An image forming apparatus.

[2] The roller receiving portion is formed in a substantially U shape in a side view in which the roller receiving side is opened,
The image forming apparatus according to [1], wherein the roller receiving portion is provided with a facing surface that substantially faces the roller contact surface and comes into contact with another arc surface portion of the roller.

  [3] The roller contact surface and the facing surface are provided with an inclination to feed the roller to the back side of the roller receiving portion by the weight of the photosensitive member side member or the developer side member when the roller enters the roller receiving portion. The image forming apparatus according to [2].

  According to the invention described in [1], when the developing device side member and the photosensitive member side member are joined, the roller on one side is received by the roller receiving portion on the other side. By selecting one arc surface portion to be brought into contact with the roller contact surface from among the arc surface portions, the gap between the developing roller of the developing device side member and the photosensitive drum of the photoconductor side member can be easily adjusted.

  According to the invention described in [2] above, when one arc surface portion of the roller contacts the roller contact surface, another arc surface portion of the roller contacts the surface substantially opposite to the roller contact surface. When the member and the photosensitive member side member are joined, the roller receiving state becomes firm.

  According to the invention described in the preceding item [3], the roller contact surface and the opposite surface are inclined so that the roller is fed to the back side of the roller receiving portion by the weight of the photosensitive member side member or the developing device side member. In a state where the roller enters the roller receiving portion, the gap adjustment state between the photosensitive drum and the developing roller can be stably maintained.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, the image forming apparatus 1 includes an image reading unit 100, an image forming unit 110, and a paper feeding unit 120.

  The image reading unit 100 reads an original image and generates image data for each of the magenta (M), cyan (C), yellow (Y), and black (K) color components.

  The paper feed unit 120 includes a paper feed cassette 121, a pickup roller 122, and a registration roller 123.

  The paper feed cassette 121 stores recording sheets (paper) for image formation. The pickup roller 122 feeds the recording sheet from the paper feed cassette 121, and the registration roller 123 takes the timing to send the recording sheet to the image forming unit 110.

  The image forming unit 110 includes a transfer belt 111 and four photosensitive drums 112M, 112C, 112Y, and 112K corresponding to the four colors of magenta (M), cyan (C), yellow (Y), and black (K). Charging chargers 113M, 113C, 113Y, 113K, developing devices 114M, 114C, 114Y, 114K, transfer chargers 115M, 115C, 115Y, 115K, exposure scanning units 116M, 116C, 116Y, 116K, and a fixing device 117. A paper discharge tray 118 and a front door 119.

  The transfer belt 111 conveys the recording sheet sent from the paper feeding unit 120 to the fixing device 117. The charging chargers 113M to 113K uniformly charge the photosensitive drums 112M to 112K, respectively.

  The exposure scanning units 116 </ b> M to 116 </ b> K each emit laser light with a laser diode based on the image data generated by the image reading unit 100. The laser light is polarized by a polygon mirror, and then the uniformly charged photosensitive drums 112M to 112K are exposed and scanned. As a result, electrostatic latent images are formed on the surfaces of the photosensitive drums 112M to 112K, respectively.

  The developing units 114M to 114K develop electrostatic latent images on the photosensitive drums 112M to 112K, respectively, to form toner images.

  The transfer chargers 115M to 115K transfer the toner images formed on the photosensitive drums 112M to 112K, respectively, onto a recording sheet.

  The fixing unit 117 fuses toner particles to the surface of the recording sheet by pressurizing the toner image transferred onto the recording sheet with high heat. The recording sheet on which the toner image is fixed is discharged onto the paper discharge tray 118.

  The photosensitive drums 112M to 112K, the charging chargers 113M to 113K, the developing devices 114M to 114K, and the transfer chargers 115M to 115K are unitized and housed in one casing so that maintenance can be easily performed. This is called an imaging unit. The imaging unit is detachably stored in the image forming apparatus 1.

  Further, a front door 119 that can be opened and closed is provided on the front surface portion of the image forming unit 110. When the front door 119 is opened forward, a jam occurs when a paper jam occurs in the paper transport system. Maintenance such as removal of paper or replacement of consumables such as an imaging unit or supply of toner can be performed.

  FIG. 2 is a side view showing the configuration of the imaging unit 2 in the image forming apparatus 1.

  In FIG. 2, the imaging unit 2 includes a photosensitive member side member 200 and a developing device side member 210.

  One of the photosensitive member side member 200 and the developing device side member 210, for example, the developing device side member 210 is relative to the photosensitive member side member 200 along the vertical plane with the pivot 214 located at the lower end thereof as a center. 2 are joined so as to be capable of rotational displacement and contact / separation. At the rotational displacement position of FIG.

  A photosensitive drum 201 is incorporated into the other of the photosensitive member side member 200 and the developing device side member 210, that is, the photosensitive member side member 200 via a supporting base 201A, and the developing device side member in the supporting base 201A. A roller receiving portion 202 is formed at an end portion (a right end portion in FIG. 2) facing 210. Here, the photosensitive drum 201 is a concept equivalent to or equivalent to the photosensitive drums 112M to 112K in FIG.

  The developing device side member 210 includes a developing roller (not shown), and includes a roller 211, an idle gear 212 positioned below the roller 211, and a drive input gear 213 positioned below the idle gear 212. ing. The developing roller here is the same as the developing units 114M to 114K in FIG.

  The roller 211 is attached to a rotating shaft 510 of the developing roller, and is supported so as to be rotatable around the axis of the developing roller.

  The drive input gear 213 is rotationally driven by an external force to rotationally drive the idle gear 212. The idle gear 212 rotationally drives the developing roller.

  The roller receiving portion 202 is configured as a groove portion formed in a U shape in a side view at a portion facing the roller 211 in the support base 201A, and the lower opening end portion of the roller receiving portion 202 is the roller receiving portion. It is configured as a roller entry guide wall 202a when entering the 202.

  As shown in FIGS. 4 and 5, a roller contact surface 401 and a facing surface 402 that faces the roller contact surface 401 are formed on the upper and lower inner surfaces of the roller receiving portion 202, respectively.

  The distance between the roller contact surface 401 and the opposing surface 402 gradually decreases from the entrance to the back of the roller receiving portion 202 so that the clamping force by the roller contact surface 401 and the opposing surface 402 increases with respect to the roller 211. Is set.

  The roller contact surface 401 is a circular arc convex surface located on a virtual circle centered on the axis of the photosensitive drum 201, and the roller 211 comes into contact with the roller contact surface 401, so that the photosensitive drum 201 and the developing roller are in contact with each other. It is set so that the gap between them is properly maintained.

  Further, the facing surface 402 that forms the lower surface of the roller receiving portion 202 is inclined downward toward the back of the roller receiving portion 202 in the joined state of the photosensitive member side member 200 and the developing device side member 210, that is, vertical as it reaches the back. It is formed to be inclined so that the height in the direction is low. The inclination angle of the roller receiving surface 402 with respect to the horizontal plane is set to 15 degrees, for example.

  On the other hand, as shown in FIG. 5, for example, the roller 211 in the developer-side member 210 includes a plurality of, for example, three arcuate surface portions 211A, 211B, 211C divided around the axis (circumferential direction), and these arcuate surface portions 211A. , 211B, 211C, and a cylindrical base 212 that supports the rotating shaft 510.

  These arcuate surface portions 211A, 211B, and 211C are integrally formed on the outer peripheral side of the cylindrical base portion 212 in a state where the diameters Ra, Rb, and Rc are different (Ra <Rb <Rc).

  The three arcuate surface portions 211A, 211B, and 211C are selected so as to come into contact with the roller contact surface 401 in accordance with the gap to be formed between the photosensitive drum 201 and the developing roller.

  In other words, the gap between the photosensitive drum 201 and the developing roller can be adjusted by selecting any one of the three arcuate surface portions 211A, 211B, and 211C with respect to the roller contact surface 401.

  Next, in the imaging unit 2 configured as described above, a procedure for adjusting the gap between the photosensitive drum 201 of the photosensitive member side member 200 and the developing roller of the developing device side member 210 will be described.

  Now, as shown in FIG. 3, it is assumed that the developing device side member 210 is separated from the photoconductor side member 200.

  If the developing device side member 210 is rotated counterclockwise about the pivot 214 from this separated state, the roller 211 on the developing device side member 210 is lowered by the roller entrance guide wall 202a on the photoconductor side member 200. It is guided into the roller receiving portion 202 while being supported from above.

  Then, if the developing device side member 210 is further rotated and rotated in the counterclockwise direction, the roller 211 enters the roller receiving portion 202, and the developing device side member 210 is shown in FIG. The joint position is set.

  When the roller 211 enters the roller receiving portion 202, as shown in FIG. 5, one of the three arc surface portions 211A, 211B, 211C in the roller 211, for example, the outer periphery of the arc surface portion 211A having the minimum diameter (Ra) The surface contacts the roller contact surface 401, and the outer peripheral surface of another arcuate surface portion 211 </ b> C contacts the facing surface 402.

  That is, the distance from the contact point between the arc surface portion 211A of the roller 211 and the roller contact surface 401 to the axial center of the roller 211 (the length of the diameter of the arc surface portion 211A) and the photosensitive drum 201 of the photoconductor side member 200 The gap between the developing device side member 210 and the developing roller can be adjusted.

  When it is desired to set the gap between the photosensitive drum 201 and the developing roller to be the smallest, the outer peripheral surface of the arc surface portion 211A having the smallest diameter among the three arc surface portions 211A, 211B, 211C becomes the roller contact surface 401. The roller 211 only needs to be rotationally shifted so as to abut, and conversely, when it is desired to set the gap between the photosensitive drum 201 and the developing roller to be the largest, the three arcuate surface portions 211A, 211B, 211C Of these, the roller 211 may be rotationally shifted so that the outer periphery of the arc surface portion 211 </ b> C having the largest diameter contacts the roller receiving surface 402.

  Also, if the developer-side member 210 in the joined state of FIG. 2 is rotated and shifted clockwise about the pivot 214, the roller 211 is retracted from the roller receiving portion 202. As shown in FIG. The developing device side member 210 can be easily set at a position separated from the photoconductor side member 200. Of course, the number of the arcuate surface portions 211A, 211B, 211C is not limited to three and can be arbitrarily increased or decreased.

  In this way, any one of the three circular arc surface portions 211A, 211B, 211C provided on the roller 211 so as to be equally distributed around the axis is selected and brought into contact with the roller contact surface 401 of the roller receiving portion 202. With this simple configuration, the gap between the photosensitive drum 201 and the developing roller can be adjusted. In addition, since the arc surface portions 211A, 211B, and 211C that contact the roller contact surface 401 can be selected, it is possible to easily cope with the adjustment of the gap with high accuracy.

  In addition, when one arc surface portion 211A of the roller 211 comes into contact with the roller contact surface 401, another arc surface portion 211C of the roller 211 comes into contact with the surface 402 substantially opposite to the roller contact surface 401. The receiving state of the roller 211 becomes firm at the time of joining with the photoconductor side member 200.

  Furthermore, the opposing surface 402 of the roller receiving portion 202 is formed so as to be inclined so that the height in the vertical direction decreases from the entrance to the back of the roller receiving portion 202. 211 receives the force which feeds on the roller receiving surface 402 from the entrance of the roller receiving part 202 to the back side by gravity. As a result, the roller 211 is pressed against the roller contact surface 401, and the gap between the photosensitive drum 201 and the developing roller is more stably secured.

  Of course, the inclination angle of the roller receiving surface 402 is not limited to 15 °, and can be selected and set to any angle as long as the inclination angle with respect to the horizontal plane is greater than 0 degree and less than 90 degrees.

  In this embodiment, the case where the imaging unit 2 is detachable from the image forming apparatus 1 has been described. However, the present invention is not limited to this, and the imaging unit 2 is detachable from the image forming apparatus 1. There may be.

  In this embodiment, the developing device side member 210 is configured to rotate and change with respect to the photoconductor side member 200. However, the rotating and changing side may be opposite to the above. A configuration in which the roller receiving portion 202 is provided on the developing device side member 210 is also possible.

  Further, in the above embodiment, the roller 211 is sent to the back side by the inclination of the facing surface 402 with the facing surface 402 of the roller receiving surface 401 and the facing surface 402 of the roller receiving portion 202 as the lower side. The roller 211 may be sent to the back side by the inclination provided on the roller contact surface 401 with the contact surface 401 facing down.

  Moreover, in the said embodiment, although comprised so that the roller 211 may be substantially inserted from the upper side with respect to the roller receiving part 202, conversely, the roller receiving part is mounted so that the roller receiving part covers the roller from above. You may comprise so that a roller may be inserted in.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. Similarly, in the image forming apparatus, the imaging unit is a side view showing a bonding state of the photosensitive member side member and the developing device side member. FIG. 5 is a side view showing the imaging unit in a separated state of the photosensitive member side member and the developing device side member. It is a side view which similarly shows the roller receiving part in a photoreceptor side member. FIG. 6 is a side view showing a state in which the roller of the developing device side member enters the roller receiving portion of the photoconductor side member. It is explanatory drawing of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 200 ... Photosensitive member side member 201 ... Photosensitive drum 202 ... Roller receiving part 210 ... Developing device side member 211 ... Roller 211A, 211B, 211C ... Arc surface part of roller 401 ... Roller contact surface 402 ... Opposing surface (inclined surface)
510: Roller axis Ra, Rb, Rc: Diameter of the arcuate surface

Claims (3)

In the image forming apparatus in which the photosensitive member side member in which the photosensitive drum is incorporated and the developing device side member in which the developing roller is incorporated are detachably arranged.
Either one of the photosensitive member side member and the developing device side member is provided with a positioning roller, and the other is provided with a roller receiving portion that receives the roller so that the roller can be moved forward and backward when the one is joined. And
The roller is rotatably supported around the axis of the photosensitive drum or the developing roller, and is provided with a plurality of arcuate surface portions that are divided around the axis and have different diameters.
The roller receiving portion has an arc convex surface centered on the axis of the photosensitive drum or the developing roller, and is formed with a roller contact surface that contacts any one of the plurality of arc surface portions of the roller. An image forming apparatus. The roller receiving portion is formed in a substantially U shape in a side view in which the receiving side of the roller is opened,
The image forming apparatus according to claim 1, wherein the roller receiving portion is provided with a facing surface that substantially faces the roller contact surface and contacts another arc surface portion of the roller.   The roller contact surface and the facing surface are provided with an inclination to feed the roller to the back side of the roller receiving portion by the weight of the photosensitive member side member or the developing device side member when the roller enters the roller receiving portion. Item 3. The image forming apparatus according to Item 2.

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