JP4783036B2 - Positioning mechanism for photoreceptor and developing roller and image forming apparatus provided with the same - Google Patents

Description

  The present invention relates to a photoconductor and developing roller positioning mechanism useful for an image forming apparatus such as a copying machine, a printer, and a facsimile machine that forms an image by an electrophotographic process, and an image forming apparatus including the same.

  This type of image forming apparatus includes an image forming unit in which a charger, an exposure unit, a developing device, a transfer roller, and the like are arranged around the photoreceptor along the rotation direction of the photoreceptor on which a toner image is formed. .

  In this image forming apparatus, after the surface of the photoconductor is uniformly charged by a charger, the photoconductor is exposed by an exposure unit according to image data, and an electrostatic latent image is formed on the photoconductor.

  The electrostatic latent image formed on the photoreceptor is developed with toner supplied from the developing device to become a toner image.

  The toner image formed on the photoconductor is transferred by the transfer roller onto the recording paper conveyed to the nip portion between the photoconductor and the transfer roller.

  Then, the recording paper onto which the toner image has been transferred is conveyed to the fixing unit, where the toner image (transfer image) is fixed by the fixing unit, and then discharged onto the paper discharge tray.

  A developing roller of a developing device in this type of image forming apparatus generally forms a uniform thin layer of toner on a developing sleeve containing a fixed magnet roller, and the thin layered toner formed on the developing sleeve is used as a photoreceptor. Development is performed by adhering to the electrostatic latent image formed thereon.

  Here, in order to maintain a desired high image quality, it is necessary to hold the developing roller and the photosensitive member with high accuracy with a predetermined gap.

  In addition, a photoreceptor or a developing device in this type of image forming apparatus needs to be configured to be detachable from the apparatus main body in order to perform regular maintenance or replacement.

  As an image forming apparatus that meets such demands, there has heretofore been an integrated cartridge (process cartridge) in which a photoreceptor and a developing device are integrated, and the process cartridge is configured to be detachable from the apparatus main body.

  In an image forming apparatus using such a process cartridge, the photosensitive member, the developing device, and the like can be replaced very simply by simply attaching and detaching the process cartridge to and from the apparatus main body.

  However, the life of the developing device and the life of the photosensitive member in this type of image forming apparatus are often not always the same.

  For this reason, in an image forming apparatus using a process cartridge, for example, when the life of the developing device is longer than the life of the photosensitive member, the developing device that is still usable can be used by replacing the process cartridge due to the life of the photosensitive member. It is discarded with the body. This is not only a wasteful consumption of resources, but is also undesirable for the global environment.

  For this reason, the photosensitive member and the developing device in the image forming apparatus are configured as separate units, and the photosensitive member and the developing device can be individually replaced with respect to the image forming unit. It is desirable to do.

  However, in this image forming apparatus, in order to maintain a desired image quality, a predetermined gap is set between the developing roller of the developing device and the photosensitive member when the photosensitive member or the developing device is mounted on the image forming unit. It is necessary to configure so as to be held with high accuracy.

  Conventionally, as a positioning mechanism between the photosensitive member and the developing roller for keeping the gap between the photosensitive member and the developing roller constant, a gap roller is arranged on the rotating shaft of the developing roller, and the gap roller is arranged on the raw tube portions at both ends of the photosensitive member. There is one in which the photosensitive member and the developing roller are maintained at a predetermined interval by being pressed against the surface (for example, see Patent Document 1).

  In the positioning mechanism of the photosensitive member and the developing roller described in Patent Document 1, as shown in FIG. 14, in order to keep the gap G between the photosensitive member 10 and the developing roller 20 constant, a gap is formed on the rotating shaft 21 of the developing roller 20. A roller 22 is arranged.

  In this positioning mechanism, the gap roller 22 is pressed against the surface of the raw tube portion 10a at both ends of the photoconductor 10, so that the photoconductor 10 and the developing roller 20 are maintained at a predetermined interval.

  As another positioning mechanism for the photosensitive member and the developing roller, a gap arm is disposed on the rotating shaft of the photosensitive member, and this gap arm is pressed against the bearing of the rotating shaft of the developing roller having a smaller diameter than the developing roller. There is one in which the body and the developing roller are maintained at a predetermined interval (for example, see Patent Document 2).

  In the positioning mechanism between the photoconductor and the developing roller described in Patent Document 2, as shown in FIG. 15, in order to keep the gap G between the photoconductor 10 and the developing roller 20 constant, the rotating shafts 11 on both sides of the photoconductor 10. The gap arms 12 are arranged respectively.

In this positioning mechanism, the gap arm 12 is pressed against the bearing 23 of the rotating shaft 21 of the developing roller 20 having a diameter smaller than that of the developing roller 20 to maintain the photosensitive member 10 and the developing roller 20 at a predetermined interval. Like to do.
JP-A-3-23475 Japanese Utility Model Publication No. 4-20061

  However, the conventional photoconductor and developing roller positioning mechanism has the following problems.

  In the positioning mechanism described in Patent Document 1, for example, when the developing device is replaced, the gap roller 22 is not pressed against the surface of the element tube portion 10a of the photosensitive member 10 and is directly parallel to the rotating shaft 11 of the photosensitive member 10. The developing device can be attached and detached in any direction, and the developing device can be replaced relatively easily.

  However, in the positioning mechanism described in Patent Document 1, the gap roller 22 disposed on the rotation shaft 21 of the developing roller 20 is pressed against the surface of the raw tube portion 10a at both ends of the photoconductor 10, so There is a problem that extra space is required at both ends, and the image forming unit becomes large.

  In this positioning mechanism, the gap G between the photosensitive member 10 and the developing roller 20 can be maintained at a specified interval immediately after the new developing device is mounted. The scattered toner or the like tends to adhere to the surface of the tube portion 10a.

  Therefore, in this positioning mechanism, the gap G between the photoconductor 10 and the developing roller 20 is changed by the scattered toner or the like adhering between the gap roller 22 and the surface of the photoconductor 10 during printing, and the gap G is defined. There was a problem that it was difficult to maintain the interval accurately.

  On the other hand, in the positioning mechanism described in Patent Document 2, for example, after a new developing device is mounted, the front end portion of the gap arm 12 is pressed against the bearing 23 of the rotating shaft 21 of the developing roller 20, so The gap G with 20 is maintained at a specified interval.

  In this positioning mechanism, even during printing, there is little possibility that the toner scattered on the surface of the photosensitive member 10 adheres between the gap arm 12 and the bearing 23 of the rotating shaft 21 of the developing roller 20, and the photosensitive member 10 and the developing roller 20. It is easy to maintain the gap G at a predetermined interval with high accuracy.

  However, in this positioning mechanism, the tip end portion of the gap arm 12 disposed on the rotating shaft 11 on both sides of the photoreceptor 10 is pressed against the bearing 23 having a diameter smaller than the diameter of the developing roller 20.

  For this reason, in this positioning mechanism, for example, when the photoreceptor 10 is replaced, after the tip of the gap arm 12 is released from the bearing 23 of the rotating shaft 21 of the developing roller 20, the tip of the gap arm 12 is further developed. The photoreceptor 10 cannot be attached or detached in a direction parallel to the rotating shaft 11 unless it is moved to a position retracted larger than the outer diameter of the roller 20.

  Therefore, in this positioning mechanism, a large retreat space is required to open the tip of the gap arm 12 from the bearing 23 of the rotating shaft 21 of the developing roller 20, so that the image forming unit is increased in size, and the photosensitive member 10 and There was a problem that workability at the time of replacement of the developing device was not good.

  The present invention has been made in view of the above points, and can easily attach and detach the photosensitive member or the developing device while reducing the size of the image forming unit, and can position the photosensitive member and the developing roller with high accuracy. An object of the present invention is to provide a positioning mechanism between a photosensitive member and a developing roller, and an image forming apparatus including the same.

In order to solve this problem, the photoconductor / developing roller positioning mechanism of the present invention includes a photoconductor on which an electrostatic latent image is formed and a developing device including a developing roller for developing the electrostatic latent image. The photosensitive member is detachably disposed in a direction parallel to the developing roller with respect to the unit, and the photosensitive member is attached to the developing roller in a predetermined state with the photosensitive member attached to the image forming unit. A positioning mechanism for a photosensitive member and a developing roller that are positioned in parallel across a gap, the photosensitive member including a photosensitive member shaft having shaft portions extending on both sides of the photosensitive member, and a rear side of the photosensitive member shaft. A back side photoreceptor bearing that rotatably supports a shaft part, a front side photoreceptor bearing that rotatably supports a shaft part on the front side of the photoreceptor shaft, and the gap attached to the front side photoreceptor bearing. a front positioning member defining The developing device includes: a developing roller shaft having shaft portions extending on both sides of the developing roller; a back side developing roller bearing that rotatably supports a shaft portion on the back side of the developing roller shaft; A front side developing roller bearing that rotatably supports a shaft portion on the near side of the developing roller shaft; and a back side positioning member that defines the gap attached to the back side developing roller bearing; The outer diameter of the body bearing is equal to or smaller than the outer diameter of the photosensitive member, the outer diameter of the front developing roller bearing is equal to or smaller than the outer diameter of the developing roller, and the front positioning member is brought into contact with the front developing roller bearing. The back side positioning member is brought into contact with the back side photoreceptor bearing.

  According to the present invention, it is possible to easily attach and detach the photoconductor or the developing device while reducing the size of the image forming unit, and to position the photoconductor and the developing roller with high accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the component and equivalent part which have the same structure or function, and the description is not repeated.

  FIG. 1 is a schematic configuration diagram showing an overall configuration of an image forming apparatus suitable for using a positioning mechanism for a photoconductor and a developing roller according to an embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus 100 includes image forming units 110Y, 110M, 110C, and 110K, a laser scan unit (LSU) 120, an intermediate transfer unit 130, a toner replenishing unit 140, a fixing device 150, and a paper feeding unit 160. Etc.

  The image forming unit 110Y includes a photoreceptor 111Y, a charging roller 112Y, a developing device 113Y, a primary transfer roller 114Y, and a photoreceptor cleaner 115Y, and forms a yellow (Y) toner image on the photoreceptor 111Y.

  The image forming unit 110M includes a photoreceptor 111M, a charging roller 112M, a developing device 113M, a primary transfer roller 114M, and a photoreceptor cleaner 115M, and forms a magenta (M) color toner image on the photoreceptor 111M.

  The image forming unit 110C includes a photoreceptor 111C, a charging roller 112C, a developing device 113C, a primary transfer roller 114C, and a photoreceptor cleaner 115C, and forms a cyan (C) toner image on the photoreceptor 111C.

  The image forming unit 110K includes a photosensitive member 111K, a charging roller 112K, a developing device 113K, a primary transfer roller 114K, and a photosensitive member cleaner 115K, and forms a black (K) toner image on the photosensitive member 111K.

  The laser scanning unit 120 passes each laser beam LY, LM, LC, LK separated into four colors through a polygon mirror, an f-θ lens, a reflection mirror, an imaging lens, etc. (not shown) to each image forming unit 110Y, Irradiate 110M, 110C, and 110K photoconductors 111Y, 111M, 111C, and 111K.

  The intermediate transfer unit 130 includes an intermediate transfer belt 131, a driving roller 132, a driven roller 133, a tension roller 134, and a belt cleaner 135.

  The intermediate transfer belt 131 is rotatably suspended by a driving roller 132 and a driven roller 133, is given a predetermined tension by a tension roller 134, and is driven by the driving roller 132 to rotate in the direction of the arrow.

  The belt cleaner 135 removes residual toner and the like on the image transfer surface of the intermediate transfer belt 131 as the intermediate transfer belt 131 rotates.

  The toner replenishment unit 140 includes toner bottles 141Y, 141M, 141C, and 141K in which toners of respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are individually stored.

  The toner replenishing unit 140 is disposed on the upper portion of the apparatus main body 101, and in accordance with a toner replenishing command, the toner contained in the toner bottles 141Y, 141M, 141C, and 141K is transferred to each image through a toner replenishing tube (not shown). The developing devices 113Y, 113M, 113C, and 113K of the forming units 110Y, 110M, 110C, and 110K are replenished in a timely manner.

  Each developing device 113Y, 113M, 113C, 113K includes a developing roller 116 and a stirring screw 117.

  The fixing device 150 includes an exciting coil 151, a heating belt 152, a fixing roller 153, a pressure roller 154, and the like. The heating belt 152 is heated by electromagnetic induction by the exciting coil 151. The fixing roller 153 and the pressure roller 154 are pressed against each other to form a nip with the heating belt 152 interposed therebetween.

  The sheet feeding unit 160 is disposed in the lower part of the apparatus main body 101, and the image forming apparatus 100 of this example includes a sheet cassette 161 that accommodates small-size paper P1 and a paper cassette that accommodates large-size paper P2. 162.

  Small size paper P1 stacked and accommodated in the paper cassette 161 is separated and fed from the paper cassette 161 one by one by the pickup roller 163 and the separation roller 164.

  Large-size sheets P2 stacked and accommodated in the sheet cassette 162 are separated and fed one by one from the sheet cassette 162 by the pickup roller 165 and the separation roller 166.

  In FIG. 1, photosensitive members 111Y, 111M, 111C, and 111K of the image forming units 110Y, 110M, 110C, and 110K are rotated in a predetermined direction by a driving system (not shown) at a predetermined timing, and charging rollers 112Y, 112M, 112C, The surface is sequentially charged to a predetermined potential by 112K.

  The surfaces of the charged photoconductors 111Y, 111M, 111C, and 111K are sequentially exposed to the laser beams LY, LM, LC, and LK emitted from the laser scan unit 120. Thereby, electrostatic latent images of the respective colors are formed on the surfaces of the photoreceptors 111Y, 111M, 111C, and 111K.

  The electrostatic latent images of the respective colors formed on the surfaces of the photoreceptors 111Y, 111M, 111C, and 111K are agitated by the agitating screws 117 of the developing devices 113Y, 113M, 113C, and 113K and supplied by the developing roller 116. The four color toners of yellow, magenta, cyan, and black are sequentially developed to be visualized as four color toner images.

  The four color toner images formed on the surfaces of the photoreceptors 111Y, 111M, 111C, and 111K are transferred onto the image transfer surface (outer peripheral surface) of the rotating intermediate transfer belt 131 on the primary transfer rollers 114Y, 114M, 114C, and 114K. Are sequentially superimposed and primary transferred. As a result, a full color image is formed on the image transfer surface of the intermediate transfer belt 131.

  The full-color image primarily transferred onto the intermediate transfer belt 131 is fed by the secondary transfer roller 104 onto the paper P1 or the paper P2 fed from the paper feed unit 160 and conveyed by the paper feed guide roller 102 and the registration roller 103. Batch transfer (secondary transfer) is performed.

  The sheet P1 or sheet P2 onto which the full-color image has been secondarily transferred is fixed by the nip of the fixing device 150 and then conveyed by the sheet discharge guide roller 105 and is provided on the upper portion of the apparatus main body 101 by the sheet discharge roller 106. The paper is discharged onto the paper discharge tray 107.

(Embodiment 1)
Next, the positioning mechanism between the photoconductor and the developing roller according to Embodiment 1 of the present invention will be described.

  First, the configuration of the image forming units 110Y, 110M, 110C, and 110K in the image forming apparatus 100 of this example will be described. Each of the image forming units 110Y, 110M, 110C, and 110K has the same configuration except that the toner colors to be used are different. Therefore, hereinafter, Y, M, C, and K at the end of the sign representing the toner color are used. The symbol of is omitted.

  FIG. 2 is a schematic perspective view showing the external appearance of an image forming unit on which the positioning mechanism for the photoconductor and the developing roller according to Embodiment 1 of the present invention is mounted.

  As shown in FIG. 2, the image forming unit 110 includes a photoreceptor 111, a charging roller 112, a developing device 113, and the like.

  The charging roller 112 is disposed so as to contact the photosensitive member 111 or face the photosensitive member 111 with a predetermined gap. The charging roller 112 is provided with a cleaning roller 118 for removing toner, dust, and the like attached to the surface.

  The photoconductor 111 is detachably disposed on a support plate (not shown) of the image forming unit 110, and is detached from the image forming unit 110 by pulling in the direction of arrow A in FIG. It is configured to be attached to the image forming unit 110 by pushing in the direction.

  Further, the charging roller 112 and the developing device 113 are configured to be separated (retracted) from the surface of the photosensitive member 111 when the photosensitive member 111 is attached to and detached from the image forming unit 110. For example, the developing device 113 is moved by a release lever (not shown) around a boss 119 a provided on a housing 119 as a toner container so that the developing roller 116 contacts and separates from the photosensitive member 111. Is configured to do.

  As described above, in the image forming unit 110 in which the photosensitive member 111 is detachably disposed, when the photosensitive member 111 is mounted on the image forming unit 110, the developing roller 116 and the photosensitive member 111 of the developing device 113 are previously connected. It is necessary to position the photosensitive member 111 and the developing roller 116 so as to be accurately held across the defined gap G.

  However, when the photosensitive member 111 and the developing roller 116 are positioned using the conventional photosensitive member and developing roller positioning mechanism, as described above, the image forming unit 110 becomes larger or the photosensitive member 111 is replaced. There arises a problem that workability at the time is lowered.

  Therefore, in the image forming unit 110 of this example, the positioning between the photosensitive member 111 and the developing roller 116 is performed using the positioning mechanism shown in FIG.

  FIG. 3 is a cross-sectional view showing the configuration of the positioning mechanism for the photoconductor and the developing roller according to Embodiment 1 of the present invention.

As shown in FIG. 3, the positioning mechanism of this example is configured such that the photosensitive member 111 is detachably disposed in a direction parallel to the developing roller 116, and the photosensitive member 111 is attached to the image forming unit 110 as shown in FIG. In the mounted state, the photosensitive member 111 is adjusted to be positioned parallel to the developing roller 116 with a predetermined gap G shown in FIG .

  3, the photoconductor 111 includes a photoconductor shaft 121, a back side photoconductor bearing 122, a front side photoconductor bearing 123, and a front side positioning member 124 which is a gap arm.

  A shaft portion of the photoconductor shaft 121 extends on both sides of the photoconductor 111.

  The back side photoconductor bearing 122 supports the shaft portion on the back side of the photoconductor shaft 121 in a rotatable manner.

  The front-side photoconductor bearing 123 supports the shaft portion on the front side of the photoconductor shaft 121 in a rotatable manner.

A near-side positioning member 124 that is a near-side gap arm is attached to the near-side photoreceptor bearing 123.

  On the other hand, the developing roller 116 includes a developing roller shaft 125, a back side developing roller bearing 126, a front side developing roller bearing 127, and a back side positioning member 128 that is a gap arm.

  The developing roller shaft 125 has shaft portions extending on both sides of the developing roller 116.

  The back side developing roller bearing 126 rotatably supports a shaft portion of the developing roller shaft 125 that faces the back side photoreceptor bearing 122.

  The near-side developing roller bearing 127 rotatably supports the shaft portion of the developing roller shaft 125 that faces the near-side photoconductor bearing 123.

A back side positioning member 128, which is a back side gap arm, is attached to the back side developing roller bearing 126, and together with the near side positioning member 124, defines a gap G between the developing roller 116 and the photoreceptor 111 as shown in FIG.

  Further, in the positioning mechanism of this example, the outer diameter of the back side photoconductor bearing 122 is formed to be equal to or smaller than the outer diameter of the photoconductor 111, and the outer diameter of the front side developing roller bearing 127 is outside the developing roller 116. It is formed to have a diameter or less. Thereby, in the positioning mechanism of this example, an inexpensive and small general-purpose type bearing can be used as the back side photoreceptor bearing 122 and the front side developing roller bearing 127, and space saving and cost reduction can be realized. Can do.

  Further, the front side positioning member 124 is in contact with the front side developing roller bearing 127, and the back side positioning member 128 is in contact with the back side photoreceptor bearing 122.

  Next, the state transition of the image forming unit 110 when the photoreceptor 111 is detached from the image forming unit 110 will be described.

  FIG. 4 is a schematic plan view showing a state of the image forming unit before the photoreceptor is detached from the image forming unit in the first embodiment of the present invention.

  As shown in FIG. 4, in the state where the photoconductor 111 is mounted on the image forming unit 110, the near side positioning member 124 disposed on the photoconductor 111 side is placed on the near side developing roller bearing 127 of the developing roller 116. A back side positioning member 128 that is in contact with the developing roller 116 and is in contact with the back side photoconductor bearing 122 of the photoconductor 111.

  As a result, the photosensitive member 111 is held so as to face the developing roller 116 of the developing device 113 with a predetermined gap G therebetween.

  When removing the photosensitive member 111 from the image forming unit 110, first, as shown in FIG. 5, the housing 119 of the developing device 113 is moved in the direction of the arrow C to separate the developing roller 116 from the photosensitive member 111. Let Here, the casing 119 of the developing device 113 is swayed in the direction of arrow C, but the photosensitive member 111 may be displaced in a direction away from the developing roller 116.

  As a result, the front side positioning member 124 disposed on the photosensitive member 111 side is separated from the front side developing roller bearing 127 of the developing roller 116, and the rear side positioning member 128 disposed on the developing roller 116 side is The photoconductor 111 is separated from the inner photoconductor bearing 122.

  Next, in the state where the photoconductor 111 is separated from the developing roller 116 as shown in FIG. 5, the photoconductor 111 is pulled out from the image forming unit 110 in the direction of arrow A as shown in FIGS.

  As a result, as shown in FIG. 8, the developing device 113 remains in the image forming unit 110 and the photosensitive member 111 is completely detached from the image forming unit 110.

  As described above, in the positioning mechanism of this example, the front side positioning member 124 is disposed on the photosensitive member 111 side, and the outer diameter of the front side developing roller bearing 127 with which the front side positioning member 124 abuts is equal to that of the developing roller 116. Since it is smaller than the outer diameter, the front positioning member 124 and the front developing roller bearing 127 do not interfere with other members when the photosensitive member 111 is attached or detached.

  Further, in the positioning mechanism of the present example, the outer diameter of the rear photosensitive member bearing 122 on which the rear positioning member 128 is disposed on the developing roller 116 side and the rear positioning member 128 abuts is equal to the outer diameter of the photosensitive member 111. Therefore, when the photoconductor 111 is attached or detached, the back side positioning member 128 and the back side photoconductor bearing 122 do not interfere with other members.

  Therefore, in the positioning mechanism of this example, the image forming unit is not moved to the position where the tip end of the gap arm 12 is retracted larger than the outer diameter of the developing roller 20 unlike the conventional positioning mechanism shown in FIG. The photosensitive member 111 can be pulled out from 110.

  As a result, in the positioning mechanism of this example, the photosensitive member 111 can be easily attached and detached while the image forming unit 110 is reduced in size, and the photosensitive member 111 is positioned with respect to the developing roller 116 with high accuracy. be able to.

  In the positioning mechanism of this example, the developing device 113 can be detached from the image forming unit 110 after the photosensitive member 111 is completely detached from the image forming unit 110.

(Embodiment 2)
Next, a positioning mechanism for the photoreceptor and the developing roller according to the second embodiment of the present invention will be described.

  FIG. 9 is a schematic plan view showing the configuration of the positioning mechanism for the photoconductor and the developing roller according to Embodiment 2 of the present invention.

The positioning mechanism of this example is such that the developing device 113 is detachably arranged in a direction parallel to the photosensitive member 111. As shown in FIG. 9, the developing device 113 is attached to the photosensitive member 111 with the developing device 113 attached. The developing roller 116 of the developing device 113 is adjusted to be positioned in parallel with a predetermined gap G therebetween.

  In FIG. 9, the developing roller 116 includes a developing roller shaft 125, a rear developing roller bearing 126, a front developing roller bearing 127, and a front positioning member 124 that is a gap arm.

  The developing roller shaft 125 has shaft portions extending on both sides of the developing roller 116.

  The back side developing roller bearing 126 rotatably supports the shaft portion of the developing roller shaft 125 facing the back side photoreceptor bearing 122.

  The near-side developing roller bearing 127 rotatably supports the shaft portion of the developing roller shaft 125 that faces the near-side photoconductor bearing 123.

A near-side positioning member 124 that is a near-side gap arm is attached to the near-side developing roller bearing 127.

  On the other hand, the photoconductor 111 includes a photoconductor shaft 121, a back side photoconductor bearing 122, a front side photoconductor bearing 123, and a back side positioning member 128 that is a gap arm.

  A shaft portion of the photoconductor shaft 121 extends on both sides of the photoconductor 111.

  The back side photoconductor bearing 122 supports the shaft portion on the back side of the photoconductor shaft 121 in a rotatable manner.

  The front-side photoconductor bearing 123 supports the shaft portion on the front side of the photoconductor shaft 121 in a rotatable manner.

A back side positioning member 128, which is a back side gap arm, is attached to the back side photoconductor bearing 122, and together with the front side positioning member 124, defines a gap G between the developing roller 116 and the photoconductor 111 as shown in FIG.

  Further, in the positioning mechanism of this example, the outer diameter of the rear developing roller bearing 126 is formed to be equal to or smaller than the outer diameter of the developing roller 116, and the outer diameter of the front photosensitive member bearing 123 is the outer diameter of the photosensitive member 111. It is formed to be as follows. Thereby, in the positioning mechanism of this example, an inexpensive and small general-purpose type bearing can be used as the back side developing roller bearing 126 and the front side photoreceptor bearing 123, and space saving and cost reduction can be realized. Can do.

  Further, the front side positioning member 124 is in contact with the front side photoconductor bearing 123, and the back side positioning member 128 is in contact with the back side developing roller bearing 126.

  Next, the state transition of the image forming unit 110 when the developing device 113 is detached from the image forming unit 110 will be described.

  FIG. 9 shows a state of the image forming unit before the developing device is detached from the image forming unit.

  As shown in FIG. 9, in the state where the developing device 113 is mounted on the image forming unit 110, the near side positioning member 124 disposed on the developing roller 116 side is brought into contact with the near side photoreceptor bearing 123, A back side positioning member 128 disposed on the photoconductor 111 side is in contact with the back side developing roller bearing 126.

  Accordingly, the developing roller 116 of the developing device 113 is held so as to face the photosensitive member 111 with a predetermined gap G therebetween.

  When the developing device 113 is detached from the image forming unit 110, first, as shown in FIG. 10, the housing 119 of the developing device 113 is moved in the direction of arrow C to separate the developing roller 116 from the photosensitive member 111. Let Here, the casing 119 of the developing device 113 is swayed in the direction of arrow C, but the photosensitive member 111 may be displaced in a direction away from the developing roller 116.

  As a result, the near-side positioning member 124 disposed on the developing roller 116 side is separated from the near-side photoreceptor bearing 123 of the photoreceptor 111 and the back-side positioning member 128 disposed on the photoreceptor 111 side. The developing roller 116 is separated from the rear developing roller bearing 126.

  Next, with the developing roller 116 of the developing device 113 separated from the photoconductor 111 as shown in FIG. 10, the developing device 113 is pulled out from the image forming unit 110 in the direction of arrow A as shown in FIGS.

  As a result, as shown in FIG. 13, the developing device 113 is completely detached from the image forming unit 110, leaving the photosensitive member 111 in the image forming unit 110.

  As described above, in the positioning mechanism of this example, the front-side positioning member 124 is disposed on the developing device 113 side, and the outer diameter of the front-side photoconductor bearing 123 with which the front-side positioning member 124 abuts is equal to that of the photoconductor 111. Since it is smaller than the outer diameter, the front side positioning member 124 and the front side photoreceptor bearing 123 do not interfere with other members when the developing device 113 is attached or detached.

  Further, in the positioning mechanism of the present example, the outer diameter of the developing roller bearing 126 is arranged on the photosensitive member 111 side and the outer diameter of the developing roller bearing 126 with which the inner positioning member 128 abuts is the outer diameter of the developing roller 116. Therefore, when the developing device 113 is attached or detached, the back side positioning member 128 and the back side developing roller bearing 126 do not interfere with other members.

  Therefore, in the positioning mechanism of this example, the image forming unit is not moved to the position where the tip end of the gap arm 12 is retracted larger than the outer diameter of the developing roller 20 unlike the conventional positioning mechanism shown in FIG. The developing device 113 can be pulled out from 110.

  Thus, in the positioning mechanism of this example, the developing device 113 can be easily attached and detached while the image forming unit 110 is reduced in size, and the developing roller 116 is positioned with high accuracy with respect to the photoreceptor 111. be able to.

  In the positioning mechanism of the present example, the photosensitive member 111 can be detached from the image forming unit 110 after the developing device 113 is completely detached from the image forming unit 110.

The positioning mechanism between the photosensitive member and the developing roller according to the first aspect of the present invention includes an image forming unit including a photosensitive member on which an electrostatic latent image is formed and a developing device including a developing roller that develops the electrostatic latent image. The photosensitive member is detachably disposed in a direction parallel to the developing roller, and the photosensitive member is attached to the developing roller in a predetermined gap with the photosensitive member mounted on the image forming unit. A photosensitive member and a developing roller positioning mechanism that are positioned in parallel with each other, wherein the photosensitive member includes a photosensitive member shaft having shaft portions extending on both sides of the photosensitive member, and a rear shaft of the photosensitive member shaft. The back side photoreceptor bearing that rotatably supports the front part, the front side photoreceptor bearing that rotatably supports the shaft part on the front side of the photoreceptor axis, and the gap attached to the front side photoreceptor bearing are defined. has a front side positioning member, the, The developing device includes: a developing roller shaft having shaft portions extending on both sides of the developing roller; a rear developing roller bearing that rotatably supports the inner shaft portion of the developing roller shaft; A front side developing roller bearing that rotatably supports a shaft portion on the front side; and a back side positioning member that defines the gap attached to the back side developing roller bearing; The outer diameter of the photosensitive member is equal to or smaller than the outer diameter of the photoconductor, the outer diameter of the front developing roller bearing is equal to or smaller than the outer diameter of the developing roller, the front positioning member is brought into contact with the front developing roller bearing, and the rear side A configuration is adopted in which the positioning member is brought into contact with the back side photoreceptor bearing.

  According to this configuration, since the back side positioning member is in contact with the back side photoconductor bearing having an outer diameter of the photoconductor or less, the back side positioning member and the back side photoconductor bearing are disposed on the photoconductor. There is no obstacle to the detaching operation. Therefore, according to this configuration, the contact of the front positioning member to the front development roller bearing and the contact of the back positioning member to the back photoconductor bearing are slightly opened. The photoconductor can be attached to and detached from the image forming unit very easily, and the image forming unit is not increased in size. Further, according to this configuration, since the near-side positioning member is in contact with the near-side developing roller bearing, and the back-side positioning member is in contact with the back-side photoconductor bearing, it is scattered at these contact portions. The toner and the like are less likely to enter, and the positioning of the photoreceptor and the developing roller can be maintained with high accuracy.

  According to a second aspect of the present invention, there is provided a positioning mechanism for a photosensitive member and a developing roller in the first aspect, wherein the developing member is separated from the image forming unit in a state where the photosensitive member is detached from the image forming unit. The device is configured to be detachable.

  According to this configuration, after the photosensitive member is detached from the image forming unit, the developing device can be easily attached to and detached from the image forming unit.

An image forming unit having a photosensitive member and a developing roller positioning mechanism according to a third aspect of the present invention includes a photosensitive member on which an electrostatic latent image is formed and a developing device including a developing roller for developing the electrostatic latent image. On the other hand, the developing device is detachably disposed in a direction parallel to the photosensitive member, and the developing roller is attached to the photosensitive member with a predetermined gap in a state where the developing device is mounted on the image forming unit. The developing device includes a developing roller shaft having shaft portions extending on both sides of the developing roller, and a shaft on the back side of the developing roller shaft. The rear developing roller bearing that rotatably supports the portion, the front developing roller bearing that rotatably supports the shaft portion on the front side of the developing roller shaft, and the gap attached to the front developing roller bearing are defined. make A front side positioning member, and the photoconductor includes a photoconductor shaft with shaft portions extending on both sides of the photoconductor, and a back side photoconductor that rotatably supports a shaft portion on the back side of the photoconductor shaft. A body-side bearing, a front-side photoreceptor bearing that rotatably supports a shaft portion on the near side of the photoreceptor shaft, and a back-side positioning member that defines the gap attached to the back-side photoreceptor bearing. The outer diameter of the rear developing roller bearing is equal to or smaller than the outer diameter of the developing roller, the outer diameter of the front photosensitive member bearing is equal to or smaller than the outer diameter of the photosensitive member, and the rear positioning member is the rear developing roller. A configuration is adopted in which the front positioning member is brought into contact with the bearing and the front positioning member is brought into contact with the front photoreceptor bearing.

  According to this configuration, since the back side positioning member is in contact with the back side development roller bearing having an outer diameter of the developing roller or less, the back side positioning member and the back side developing roller bearing are connected to the developing device. There is no obstacle to the detaching operation. Therefore, according to this configuration, the contact of the near-side positioning member to the near-side photoconductor bearing and the contact of the back-side positioning member to the back-side developing roller bearing are slightly opened. The developing device can be attached to and detached from the image forming unit very easily, and the image forming unit does not increase in size. Further, according to this configuration, since the near side positioning member is in contact with the near side photoconductor bearing and the back side positioning member is in contact with the back side developing roller bearing, the front side positioning member is scattered at these contact portions. The toner and the like are less likely to enter, and the positioning of the photoreceptor and the developing roller can be maintained with high accuracy.

  According to a fourth aspect of the present invention, there is provided a positioning mechanism for a photosensitive member and a developing roller, wherein, in the third aspect, the photosensitive member and the developing roller are positioned with respect to the image forming unit in a state where the developing device is detached from the image forming unit. The structure which made the body detachable is taken.

  According to this configuration, the photoconductor can be easily attached to and detached from the image forming unit after the developing device is detached from the image forming unit.

  An image forming apparatus according to a fifth aspect of the present invention employs a configuration including the photoconductor and the developing roller positioning mechanism according to any one of the first to fourth aspects.

  According to this configuration, since the photoconductor or the developing device can be easily attached and detached, maintenance and replacement of the photoconductor and the developing device can be easily performed.

  The positioning mechanism between the photosensitive member and the developing roller according to the present invention can easily attach and detach the photosensitive member or the developing device while reducing the size of the image forming unit, and positions the photosensitive member and the developing roller with high accuracy. Therefore, it is useful as a positioning mechanism for a photosensitive member and a developing roller of an image forming apparatus such as a copying machine, a printer, or a facsimile machine that forms an image by an electrophotographic process.

1 is a schematic configuration diagram showing an overall configuration of an image forming apparatus suitable for using a positioning mechanism for a photoconductor and a developing roller according to an embodiment of the present invention. 1 is a schematic perspective view showing an appearance of an image forming unit on which a positioning mechanism for a photoconductor and a developing roller according to Embodiment 1 of the present invention is mounted. Sectional drawing which shows the structure of the positioning mechanism of the photoconductor and developing roller which concerns on Embodiment 1 of this invention 1 is a schematic plan view showing a state of an image forming unit before a photoreceptor is detached from the image forming unit in Embodiment 1 of the present invention. 1 is a schematic plan view showing a state in which a photoconductor is separated from a developing roller of a developing device in Embodiment 1 of the present invention. 1 is a schematic plan view showing a state in which a photoconductor is pulled out from an image forming unit after the photoconductor is separated from a developing roller of a developing device in Embodiment 1 of the present invention. 1 is a schematic plan view showing a state in which a photoconductor is further pulled out from an image forming unit in Embodiment 1 of the present invention. 1 is a schematic plan view showing a state in which a photoreceptor is detached from an image forming unit in Embodiment 1 of the present invention. Schematic plan view showing a configuration of a positioning mechanism for a photosensitive member and a developing roller according to Embodiment 2 of the present invention. In Embodiment 2 of this invention, the schematic plan view which shows the state from which the developing roller of the developing device was spaced apart from the photoreceptor. 7 is a schematic plan view showing a state in which the developing device is pulled out from the image forming unit after the developing roller of the developing device is separated from the photosensitive member in Embodiment 2 of the present invention. FIG. 7 is a schematic plan view showing a state in which the developing device is further pulled out from the image forming unit in Embodiment 2 of the present invention. FIG. 7 is a schematic plan view showing a state in which the developing device is detached from the image forming unit in the second embodiment of the present invention. Schematic configuration diagram showing a configuration of a positioning mechanism for a photoconductor and a developing roller described in Patent Document 1. Schematic configuration diagram showing a configuration of a positioning mechanism for a photoconductor and a developing roller described in Patent Document 2

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Main body 110 Image forming unit 111 Photoreceptor 113 Developing device 119 Housing 119a Boss 116 Developing roller 121 Photoreceptor shaft 122 Back side photoreceptor bearing 123 Front side photoreceptor bearing 124 Front side positioning member (gap arm)
125 Developing roller shaft 126 Back side developing roller bearing 127 Front side developing roller bearing 128 Back side positioning member (gap arm)
G gap

Claims (5)

The photosensitive member can be attached to and detached from an image forming unit having a photosensitive member on which an electrostatic latent image is formed and a developing device having a developing roller for developing the electrostatic latent image in a direction parallel to the developing roller. A positioning mechanism for a photosensitive member and a developing roller that is disposed and positions the photosensitive member in parallel with a predetermined gap with respect to the developing roller in a state where the photosensitive member is mounted on the image forming unit;
The photoconductor includes a photoconductor shaft with shaft portions extending on both sides of the photoconductor, a back photoconductor bearing that rotatably supports a shaft portion on the back side of the photoconductor shaft, and the photoconductor shaft. A front side photoreceptor bearing that rotatably supports a shaft portion on the front side, and a front side positioning member that defines the gap attached to the front side photoreceptor bearing,
The developing device includes: a developing roller shaft having shaft portions extending on both sides of the developing roller; a rear developing roller bearing that rotatably supports a shaft portion on the inner side of the developing roller shaft; A front side developing roller bearing that rotatably supports a shaft portion on the near side, and a back side positioning member that defines the gap attached to the back side developing roller bearing,
The outer diameter of the back-side photoconductor bearing is set to be equal to or smaller than the outer diameter of the photoconductor, the outer diameter of the front-side developing roller bearing is set to be equal to or smaller than the outer diameter of the developing roller, and the front-side positioning member is set to the front-side developing roller bearing And a developing roller positioning mechanism in which the back side positioning member is in contact with the back side photoconductor bearing.   2. The photosensitive member and developing roller positioning mechanism according to claim 1, wherein the developing device is detachable from the image forming unit in a state where the photosensitive member is detached from the image forming unit. The developing device can be attached to and detached from an image forming unit having a photosensitive member on which an electrostatic latent image is formed and a developing device having a developing roller for developing the electrostatic latent image in a direction parallel to the photosensitive member. A positioning mechanism for a photosensitive member and a developing roller that is disposed and positions the developing roller in parallel with a predetermined gap with respect to the photosensitive member in a state where the developing device is mounted on the image forming unit;
The developing device includes: a developing roller shaft having shaft portions extending on both sides of the developing roller; a rear developing roller bearing that rotatably supports a shaft portion on the inner side of the developing roller shaft; A near-side developing roller bearing that rotatably supports a shaft portion on the near side, and a near-side positioning member that defines the gap attached to the near-side developing roller bearing,
The photoconductor includes a photoconductor shaft with shaft portions extending on both sides of the photoconductor, a back photoconductor bearing that rotatably supports a shaft portion on the back side of the photoconductor shaft, and the photoconductor shaft. A front side photoreceptor bearing that rotatably supports a shaft part on the front side, and a back side positioning member that defines the gap attached to the back side photoreceptor bearing,
The outer diameter of the rear developing roller bearing is equal to or smaller than the outer diameter of the developing roller, the outer diameter of the front photosensitive member bearing is equal to or smaller than the outer diameter of the photosensitive member, and the rear positioning member is the rear developing roller bearing. And a developing roller positioning mechanism in which the near-side positioning member abuts on the near-side photoreceptor bearing.   The positioning mechanism for a photoconductor and a developing roller according to claim 3, wherein the photoconductor can be attached to and detached from the image forming unit in a state where the developing device is detached from the image forming unit.   An image forming apparatus comprising the photosensitive member and the developing roller positioning mechanism according to claim 1.

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