JP5343735B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Conventionally, as an electrophotographic image forming apparatus, a photosensitive unit having a photosensitive drum and a developing unit having a developing roller are configured to be separable, and the image forming apparatus main body or the developing unit attached to the image forming apparatus main body There is also provided a device to which a photosensitive unit is mounted. (Patent Document 1)

  In such an image forming apparatus, a certain gap (development gap) must be ensured between the photosensitive drum and the developing roller in a state where the photosensitive unit is mounted on the developing unit or the image forming unit.

  However, when a pressing force is applied to the photosensitive unit in order to position the photosensitive unit at an appropriate position with respect to the developing unit or the image forming unit, the pressing unit deforms the housing of the photosensitive unit (for example, distortion or deflection). ) May occur, resulting in a change in the development gap.

JP 2001-134032 A

Accordingly, the present invention is less likely to occur the housing to deformation of the photosensitive member unit when fixing the photoreceptor unit for the current image unit, thus providing an image forming apparatus capable of maintaining a developing gap to the desired value For the purpose.

In order to achieve this object, an image forming apparatus according to the present invention includes:
A developing unit having a developing roller; and a photosensitive unit having a photosensitive drum. The photosensitive unit is mounted in the image forming apparatus main body from the direction parallel to or substantially parallel to the central axis of the developing roller. the body unit an image forming apparatus that assembled by mounting the above developing unit,
The developing unit includes a contacted portion that faces the mounting direction of the photosensitive member unit,
The photosensitive member unit has a abutment portion abutting on the abutted portion when mounting the photosensitive unit to the developing unit,
The developing unit is the developing unit to preparative state in which the photoconductor unit is attached, the contact portion and the abutted portion when viewed from the parallel or substantially parallel to the central axis of the developing roller There in the vicinity of the abutting region, and having a pressing mechanism for pressing the photosensitive member unit to the developing unit in the direction in which the contact portion approaches to the contacted portion.

  According to the image forming apparatus of the present invention, the photosensitive unit is pressed against the developing unit in the vicinity of the contact area between the photosensitive unit and the developing unit. Therefore, the photosensitive unit is not distorted or bent, and therefore a constant gap can be maintained between the photosensitive drum and the developing roller.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to the present invention. The top view of an image forming unit. The perspective view of a photoconductor unit. The perspective view of a developing unit. FIG. 3 is a perspective view showing a front side end portion of the photoreceptor unit. The perspective view which shows the near side edge part of a image development unit. The side view which looked at the image development unit and the press mechanism (release position) from the near side. The side view which looked at the image forming unit from the near side. FIG. 3 is a plan view showing the front side of the image forming unit.

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

1. Image forming apparatus

  FIG. 1 shows an image forming apparatus 1. The image forming apparatus 1 is an electrophotographic copying machine, a printer, a facsimile, or a complex machine having a combination of these functions, and image information or image formation received from a computer via a communication line (not shown). A full-color or monochrome image read by an image reading unit provided in the apparatus 1 is transferred to a recording medium (a sheet such as paper). Therefore, the housing (hereinafter referred to as “image forming apparatus main body”) 2 of the image forming apparatus 1 has four color components (yellow, magenta, cyan) and black corresponding to black necessary for forming a full color image. An image forming unit 3 is accommodated. However, the present invention is not limited to an image forming apparatus that creates a full-color image, but can also be applied to an image forming apparatus that forms a monochrome image.

  The image forming unit 3 is disposed in the vicinity of the lower belt portion of the endless intermediate transfer belt 6 supported by the rollers 4 and 5 disposed on the left and right in FIG. 1, and yellow, magenta are used during image formation. , Cyan and black developer images (toner images) are formed, transferred onto the outer peripheral surface of the intermediate transfer belt 6 rotating in the counterclockwise direction of FIG. 1, and superimposed to form a full-color developer image. The full-color developer image is transferred onto a recording medium conveyed between an intermediate transfer belt portion supported by a roller 5 disposed on the right side of FIG. 1 and a transfer device 7 disposed opposite thereto. . The full color developer image transferred to the recording medium is heated by the fixing device 8 and fixed on the recording medium, and then discharged to the discharge tray 9.

2. Image forming unit

  Each image forming unit 3 includes first and second subunits 11 and 12. The first subunit 11 includes a cylindrical drum-shaped photoreceptor (hereinafter referred to as “photoreceptor drum”). In addition, the first subunit includes a charging device that charges the outer peripheral surface of the photosensitive drum, a cleaning device that cleans the outer peripheral surface of the photosensitive drum, and a static eliminator that removes charges from the outer peripheral surface of the photosensitive drum. May be. Hereinafter, the first subunit is referred to as a “photoreceptor unit”. The second subunit 12 is a unit that forms a visible image by electrostatically attaching a developer (toner) to an electrostatic latent image formed on the outer peripheral surface of the photosensitive drum by electrophotography. A developing roller that is opposed in parallel with a minute gap (development gap) therebetween, and a mechanism for supplying the developer to the developing roller. Hereinafter, the second subunit is referred to as a “development unit”.

  In describing the image forming unit 3 and the photosensitive unit 11 and the developing unit 12 constituting the image forming unit 3, the meaning of terms will be clarified. FIG. 1 is a diagram viewed from the operation side of a user who handles the image forming apparatus 10. In the following description, the operation side of the image forming apparatus is described in order to explain the configuration and operation of the photosensitive unit 11 and the developing unit 12. This is called the “front side” and the opposite side is called the “back side”.

  For example, FIG. 2 is a view of an image forming unit in which the photosensitive unit 11 and the developing unit 12 are combined as viewed from above, and the right side of the drawing is the “front side” and the left side of the drawing is the “back side”. FIG. 3 is a view of the photosensitive unit 11 as viewed obliquely from above. The right side of the drawing is the “front side” and the left side of the drawing is the “back side”. 4 is a diagram of the developing unit 12 as viewed obliquely from above. The right side of the drawing is the “back side” and the left side of the drawing is the “front side”.

  In describing the image forming apparatus 1 and various configurations included in the image forming apparatus 1, the left side (the side facing the developing unit 12) of the photoconductor unit 11 shown in FIG. The right side of the developing unit 12 (side facing the photoconductor unit 11) is referred to as “front portion”. Further, in the following description, terms such as “right side”, “left side”, “upper part”, “lower part”, “upper part”, “lower part” and the like will be used as appropriate, which facilitates understanding of the invention with reference to the drawings. Therefore, the technical scope of the invention should not be limited by these terms.

3. Photoconductor unit

  Referring to FIG. 3, the photoconductor unit 11 has a photoconductor housing 13 made of synthetic resin. As shown in the drawing, an elongated semi-cylindrical concave portion (photosensitive drum housing portion) 14 is formed on the upper portion of the photosensitive member housing 13 from the front side to the inner side of the photosensitive member housing 13, and the photosensitive member housing 13 has a photosensitive portion. A body drum 15 is accommodated. The photosensitive drum 15 is rotatably supported on the front side wall 16 and the rear side wall 17 of the photosensitive member housing 13 via a bearing (not shown).

  As will be described in detail later, the photosensitive unit 11 starts from the front side of the image forming apparatus main body 2 with respect to the developing unit 12 mounted on the image forming apparatus main body 2 with the rear end of the photosensitive unit 11 at the top. Then, it is mounted in the direction of the arrow X shown in FIG. For this purpose, a rear side positioning protrusion 19 that protrudes toward the back side is provided on the outer surface lower portion 18 of the back side wall 17 of the photoconductor housing. The back side positioning projection 19 may be formed integrally with the photoconductor housing back side wall 17 or may be a separate member.

  Referring to FIG. 5, a front upper wall 20 and a front lower wall 21 projecting upward and downward are formed on the upper and lower sides of the front side wall 16 of the photosensitive member housing, respectively, and an inner surface (front side) of the front side upper wall 20 is formed. A positioning upper hole (engagement portion) 23 is formed in the contact portion) 22, and a positioning lower hole (engagement portion) 25 is formed in the inner surface (front side contact portion) 24 of the near side lower wall 21.

  The front upper positioning portion (particularly the upper hole 23) and the front lower positioning portion (particularly the lower hole 25) are formed on the photosensitive drum 15 when the photosensitive unit 11 is viewed from the front side toward the rear side. It is preferable that the center axis (not shown) is positioned above and below the center axis (not shown) and disposed on or near a line orthogonal to the center axis.

  A guided surface 26 is formed along the arc centered on the central axis of the photosensitive drum 15 at the rear portion (developing unit facing portion) of the front side wall 16 of the photosensitive member housing.

  As shown in FIGS. 3 and 5, in the photoconductor unit 11 of this embodiment, a handle portion 27 protruding from the front side wall 16 toward the front side (operator side) is integrally formed. Further, the photoconductor unit 11 of the embodiment accommodates a charging device (not shown) in the lower part of the photoconductor housing 13, and a cleaning member 28 of the charging device projects from the front side wall 16 toward the front side. is there.

  Further, a predetermined gap (development gap) is formed between the photosensitive drum 15 and the developing roller at the front end portion of the photosensitive drum 15 with the photosensitive unit 11 mounted on the developing unit 12. Further, an adjustment member 29 is attached coaxially with the central axis of the photosensitive drum 15.

4). Development unit

  Referring to FIG. 4, the developing unit 12 has a developing housing 31 formed of synthetic resin. As shown in the drawing, an elongated semi-cylindrical recess (photosensitive drum housing portion) 32 is formed in the upper portion of the developing housing 31 from the near side to the far side. An elongated opening 33 extending from the labor side to the back side is formed at the bottom of the recess 32, and the developing roller 34 is accommodated in the opening 33. The developing roller 34 is rotatably supported by the developing housing 31 via bearings 35 provided on the near side and the far side. Although not shown, the bearing 35 is supported by one or a plurality of springs so that the developing roller 34 can move slightly in the direction facing the photosensitive drum 15 accommodated in the recess 32. is there.

  As described above, the photosensitive unit 11 is mounted on the developing unit 12 mounted on the image forming apparatus main body 2 from the direction indicated by the arrow X in FIG. And a structure for properly positioning the photosensitive unit 11 with respect to the developing unit 12.

  Specifically, the back side wall 36 of the developing housing 31 has a back side lower wall 37 extending downward, and a positioning hole 39 is formed in the inner surface (back side contacted part) 38 of the back side lower wall 37. Yes.

  4 and 6, the front side wall 40 of the developing housing 31 has a front upper positioning wall (a front upper positioning portion, a front contacted portion) 41 that protrudes upward. The front side upper positioning wall 41 is formed with a front side positioning upper hole (front side upper positioning part) 42 extending in a direction parallel to the central axis of the developing roller 34. In addition, a front side positioning lower protrusion (front side lower positioning portion) 44 that protrudes toward the front side is provided at a lower portion of the outer surface (front side contacted portion) 43 of the front side wall 40. The near-side positioning lower protrusion 44 may be formed integrally with the developing housing front side wall 40 or may be a separate member.

  Further, in the middle stage of the developing housing 31 (between the front upper positioning portion and the front lower positioning portion), the photosensitive drum unit 11 is mounted on the developing unit 12 and the central axis of the photosensitive drum 15 is the center. A guide surface 45 is formed along the arc surface.

5. Pressing mechanism

  The developing unit 12 has a pressing mechanism for fixing the photosensitive unit 11 mounted on the image forming apparatus main body 2. Referring to FIGS. 7 to 9, the pressing mechanism 50 has a lever 51. The lever 51 can swing around an axis (not shown) extending in a direction parallel to the central axis of the photosensitive drum 15 and the developing roller 34 (can swing in the direction indicated by the arrow 52 in FIGS. 7 and 8). It is attached to the front side wall 40 of the developing unit 12 so that it can reciprocate between the position shown in FIG. 7 (release position) and the position shown in FIGS. 8 and 9 (pressing position). Further, as shown in FIG. 9, the lever 51 includes a pressure contact portion 54 formed of a protrusion protruding from the near side to the far side, and the photoconductor unit 11 is mounted on the image forming apparatus main body 2. When the lever 51 is moved from the release position to the pressing position, the pressure contact portion 54 comes into pressure contact with a front outer surface portion (hereinafter referred to as “pressure contact portion”) 53 of the front side wall 16 of the photosensitive unit. For this purpose, the pressure contact portion 53 forms a part of a plane that obliquely intersects with the axis in a direction parallel to the central axis of the photosensitive drum 15 and the developing roller 34, and thereby the pressure contact portion 54. The first area where the inner surface 22 of the near side upper wall and the near side upper positioning wall 41 are in contact with each other and the area where the inner surface 24 and the near side inner surface 43 of the near side lower wall are in contact with each other. And a third region which is a region sandwiched between the first region and the second region.

6: Mounting of photoconductor unit

  In the above configuration, the developing unit 12 is first attached and fixed to the image forming apparatus main body 2. At this time, the pin 56 (see FIG. 8) fixed to the image forming apparatus main body 2 is inserted into the front upper positioning hole 40 of the front side wall 40 of the developing housing, and the developing unit 12 is positioned to the image forming apparatus main body 2. . In this state, the photoconductor unit 11 is attached to the image forming apparatus main body 2 and the developing unit 12 with the front door provided in the image forming apparatus main body 2 opened, with the back side of the photoconductor unit 11 at the top. . The photosensitive drum 15 is accommodated in the concave portion 33 of the developing unit 12, and the photosensitive drum 15 is disposed in parallel with the developing roller 34.

  At this time, the front guided surface 26 of the photosensitive unit 11 is guided by the guide surface 45 of the developing unit 12. Then, on the back side of the image forming apparatus, the back side contact portion (the outer surface lower portion 18 of the back side wall) of the photoconductor unit 11 contacts the back side contacted portion (the inner surface 38 of the back side lower wall) of the developing unit 12. At the same time, the back side positioning portion (back side positioning projection 19) of the photoconductor unit 11 is engaged with the back side positioning portion (positioning hole 39) of the developing unit 12.

  On the front side of the photoconductor unit 11 of the image forming apparatus, the front side upper contact portion (the inner surface 22 of the front side upper wall) and the front side lower contact portion (the inner surface of the front side lower wall) on the front side of the photoconductor unit 11 24) abut on the front upper abutted portion (front upper positioning wall 41) and the front lower abutted portion (front inner surface 43) of the developing unit 12, respectively. Further, the front lower positioning portion (front positioning lower hole 25) of the photoconductor unit 11 engages with the front lower positioning portion (front positioning lower protrusion 44) of the developing unit 12.

  Next, holding the handle 27 of the photoconductor unit 11, the photoconductor unit 11 is urged clockwise. As a result, the adjusting member 29 of the photosensitive unit 11 is pressed against the bearing 35 of the developing unit 12, and the interval (developing gap) between the photosensitive drum 15 and the developing roller 34 is set to a target value. Subsequently, the front upper positioning portion (front positioning upper hole 23) of the photoconductor unit 11 is made to coincide with the 42 front upper positioning portion (front positioning upper hole 42) of the developing unit 12, and the fixing pin 56 ( 8) and the photosensitive unit 11 is positioned with respect to the developing unit 12.

  Finally, the lever 51 of the pressing mechanism 50 is moved from the release position (FIG. 5) to the pressing position (FIG. 8). At this time, the pressure contact portion 54 of the lever 51 comes into pressure contact with the pressure contact portion 53 of the front side wall 16 of the photoconductor housing, whereby the contact portion of the photoconductor unit 11 is brought into close contact with the contact portion of the developing unit 12. The photosensitive unit 11 is positioned and fixed with respect to the forming apparatus main body 2 and the developing unit 12.

  At this time, the position where the pressure contact portion 54 presses the pressure contact portion 53 is the contact portion (front side upper contact) of the photoconductor unit 11 when the image forming apparatus 1 is viewed from the front side toward the back side. Portion 22 and front lower contact portion 24) are in contact with the contacted portions (front upper contacted portion 41 and front lower contacted portion 43) of the developing unit 12, respectively, in the vicinity thereof, or in the vicinity thereof. It is determined to be located between the contact areas (areas where the contact part and the contacted part contact). Therefore, the photoconductor housing 13 is not distorted or bent by the force applied to the photoconductor housing 13 via the pressure contact portion 54 of the pressing mechanism 50. As a result, the gap (development gap) between the photosensitive drum 15 and the developing roller 34 is kept constant.

  Further, in the above description, the lever of the pressing mechanism is attached to the developing unit 12, but it may be attached to the image forming apparatus main body 2.

  The image forming apparatus of the present invention described above can be variously modified. For example, an example in which the present invention is applied to a full-color image forming apparatus having a plurality of image forming units has been shown. However, the present invention can also be applied to a monochrome image forming apparatus having only one image forming unit. is there. Further, a mechanism for holding the lever 51 of the pressing mechanism 50 at the pressing position may be provided. Furthermore, the shape of the tip of the pressure contact portion 54 in the pressing mechanism 50 (the portion that contacts the pressure contact portion) is not particularly limited.

1: Image forming apparatus 2: Image forming apparatus main body (housing)
3: Image forming unit 11: Photosensitive unit (first subunit)
12: Development unit (second subunit)
13: Photoconductor housing 14: Concave portion (photosensitive drum accommodating portion)
15: Photoreceptor drum 16: Front side wall 17: Back side wall 18: Lower outer surface of the rear side wall 19: Back side positioning protrusion 20: Front side upper wall 21: Front side lower wall 22: Inner surface of the front side upper wall (upper side upper side) Contact part)
23: Front side positioning upper hole (front side upper positioning part)
24: The inner surface of the lower wall on the near side (the lower contact portion on the near side)
25: Front positioning lower hole (front lower positioning part)
31: Development housing 34: Development roller 36: Back side wall 37: Back side lower wall 38: Inner surface of the back side lower wall (back side positioning portion)
39: Positioning hole (back side positioning part)
40: Front side wall 41: Front side upper positioning wall (front side upper positioning part, front side upper contacted part)
42: Front positioning upper hole (front upper positioning part)
43: Front side inner surface (front side lower positioning part, front side lower contacted part)
44: Front side positioning lower protrusion (front side lower positioning part)
50: Pressing mechanism 51: Lever 53: Pressure contact part (outer surface part)
54: Press contact part

Claims (5)

A developing unit having a developing roller; and a photosensitive unit having a photosensitive drum. The photosensitive unit is mounted in the image forming apparatus main body from the direction parallel to or substantially parallel to the central axis of the developing roller. the body unit an image forming apparatus that assembled by mounting the above developing unit,
The developing unit includes a contacted portion that faces the mounting direction of the photosensitive member unit,
The photosensitive member unit has a abutment portion abutting on the abutted portion when mounting the photosensitive unit to the developing unit,
The developing unit is the developing unit to preparative state in which the photoconductor unit is attached, the contact portion and the abutted portion when viewed from the parallel or substantially parallel to the central axis of the developing roller There in the vicinity of the abutting region, the image forming apparatus characterized by having a pressing mechanism which the contact portion presses said photoreceptor unit to the developing unit in a direction approaching to the abutted portion. A developing unit having a developing roller; and a photosensitive unit having a photosensitive drum. The photosensitive unit is mounted in the image forming apparatus main body from the direction parallel to or substantially parallel to the central axis of the developing roller. the body unit an image forming apparatus that assembled by mounting the above developing unit,
The developing unit has a first and second abutted portion opposite the mounting direction of the photosensitive member unit,
The photosensitive member unit has a first and second abutting portions which abut respectively on the first and second abutted portion when mounting the photosensitive unit to the developing unit,
The developing unit in a state where the above-mentioned development unit said photosensitive member unit is attached, said first and second contact portion with the first second pressing mechanism respectively pressed against the contacted portion Have
The first area where the first abutted part and the first abutting part abut, and the second area where the second abutted part and the second abutting part abut are that the photosensitive member unit is disposed so as to be positioned on both sides of the central axis of the photosensitive drum when viewed from the central axis direction of the photosensitive drum in a state of being attached to the developing unit The image forming apparatus according to claim 1 , wherein: In a state in which the above developing unit is the photosensitive member unit is attached, the image according to claim 2 said first and second regions, characterized in that located on a line passing through the central axis of the photosensitive drum Forming equipment. The pressing mechanism includes an axis extending in a direction parallel or substantially parallel to the central axis of the developing roller;
A rotating member supported rotatably between the release position and the pressing position so as to be rotatable about the axis;
The rotating member the shaft and obliquely along a plane intersecting the said photoreceptor unit to form an oblique surface engaging with the direction mounting the photosensitive unit by rotating to the pressing position from the release position the image forming apparatus according to any one of claims 3 to have a engagement surface for pushing the preceding claims, characterized in. The photoconductor unit has an adjustment member attached coaxially to the central axis of the photoconductor drum, and the adjustment member is pressed against the development unit when the photoconductor unit is mounted on the development unit and assembled. 5. The image forming apparatus according to claim 1, wherein an interval between the developing roller and the photosensitive drum is formed.

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