JP5003671B2 - Process unit and image forming apparatus - Google Patents

Description

  The present invention relates to a process unit and an image forming apparatus.

  Generally, as a process unit used in an image forming apparatus such as a laser printer, a photosensitive unit having a photosensitive drum and a developing unit having a developing roller and detachably attached to the photosensitive unit are provided. Is known. In such a process unit, for example, as shown in Patent Document 1, the developing roller and the photosensitive drum are inserted by inserting the developing unit (shaft of the developing roller) into a slit provided in a frame that supports the photosensitive drum. Are held in parallel.

Japanese Patent Laid-Open No. 7-271141 (FIG. 4)

  By the way, with the configuration in which the shaft of the developing roller is simply inserted into the slit of the frame that supports the photosensitive drum, the developing roller slightly moves when the developing roller is driven to rotate, and the developing roller and the photosensitive drum cannot be held in parallel. There was a problem. If the developing roller and the photosensitive drum cannot be held in parallel, the pressing force between the developing roller and the photosensitive drum cannot be made uniform with respect to the axial direction. Therefore, the toner is applied to the electrostatic latent image formed on the photosensitive drum from the developing roller. It becomes difficult to supply the image uniformly, resulting in a problem that the image quality is deteriorated.

  SUMMARY An advantage of some aspects of the invention is that it provides a process unit and an image forming apparatus capable of holding a developing roller and a photosensitive member in parallel.

In order to achieve the above object, the process unit of the present invention has a photosensitive unit having a photosensitive member supported by a photosensitive frame and a developing roller supported by the developing frame, and is detachable from the photosensitive unit. A development unit attached to the image forming apparatus, and a process unit detachably attached to the main body of the image forming apparatus, wherein the photoconductor unit is a side on which the photoconductor is arranged in the attaching / detaching direction of the process unit. provided on the opposite side to the a conveying roller for conveying the recording sheet, rotatably supporting said transport rollers and having a movable roller support member in the axial direction of the conveying roller, the roller The support member is provided with a locking portion that extends inward in the axial direction of the transport roller and that can be engaged with a locked portion provided in the developing frame. When the roller support member is moved inward in the axial direction of the transport roller when positioned on the forming apparatus main body, the engagement portion presses the developing unit against the photoconductor unit. It is characterized by engaging with a stop.

  The image forming apparatus of the present invention includes an apparatus main body, a photosensitive unit having a photosensitive member supported by the photosensitive frame, and a developing roller supported by the developing frame, and is detachable from the photosensitive unit. A development unit that is mounted, a process unit that is detachably mounted to the apparatus main body, and a pair of main body frames that are positioned on both sides of the process unit mounted on the apparatus main body. In the forming apparatus, the photosensitive unit includes a conveyance roller that conveys a recording sheet, and a roller support member that rotatably supports the conveyance roller and is movable in an axial direction of the conveyance roller. The roller support member is provided with a locking portion that extends inward in the axial direction of the transport roller and that can be engaged with a locked portion provided in the developing frame, The pair of main body frames guides the shaft of the developing roller when the process unit is mounted and guides the roller support member when the process unit is mounted, and a developing roller positioning groove for determining the position of the developing roller with respect to the apparatus main body. And a conveyance roller positioning groove that determines the position of the conveyance roller with respect to the apparatus main body, and extends from the opening end side along the mounting direction of the process unit at the groove bottoms of the pair of conveyance roller positioning grooves. A first guide part, a second guide part that inclines toward the inner side in the axial direction of the transport roller, and a positioning part that determines the position of the transport roller with respect to the apparatus main body are continuously provided. And urging the roller support member in a direction in which the locking portion engaged with the locked portion is pressed against the locked portion. When the process unit is mounted on the apparatus main body, a roller urging member is provided, and the roller support member is moved inward in the axial direction of the transport roller by the second guide portion, so that the locking portion is When the roller supporting member reaches the positioning portion, the engaging portion is pressed against the locked portion by the roller urging member, and the developing unit is brought into contact with the photosensitive unit. It is characterized by pressing.

  According to the present invention configured as described above, when the process unit is mounted on the image forming apparatus main body and positioned (when reaching the positioning unit), the locking unit presses the developing unit against the photosensitive unit. Therefore, the developing unit can be firmly fixed to the photosensitive unit (image forming apparatus main body). Thereby, since the fine movement of the developing roller when the developing roller is rotationally driven can be suppressed, the developing roller and the photosensitive member can be held in parallel.

  According to the present invention, when the process unit is mounted and positioned on the image forming apparatus main body, the locking portion engages with the locked portion so as to press the developing unit against the photosensitive unit. The photosensitive member can be held in parallel.

<Schematic configuration of laser printer>
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a sectional view showing a schematic configuration of a laser printer as an example of an image forming apparatus. In the following description, the direction will be described with reference to the user who uses the laser printer. That is, the left side in FIG. 1 is “front”, the right side is “rear”, the front side is “right”, and the back side is “left”. Also, the vertical direction in FIG.

  As shown in FIG. 1, a laser printer 1 includes a paper feed unit 3 that supplies a sheet P as an example of a recording sheet, an exposure device 4, and a sheet P The image forming apparatus mainly includes a process unit 5 for transferring the toner image to the toner image and a fixing device 6 for thermally fixing the toner image transferred onto the paper P. A detailed configuration of the main body housing 2 will be described later.

  The paper feed unit 3 is provided in the lower part of the main body housing 2, and includes a paper feed tray 31 that accommodates the paper P, a paper pressing plate 32 that lifts the front side of the paper P, a lift lever 33, a pickup roller 34, A paper roller 35, a paper feed pad 36, and a registration roller 37 are mainly provided. The paper P in the paper feed tray 31 is brought to the pickup roller 34 by the lift lever 33 and the paper pressing plate 32 and is sent out by the pickup roller 34. The fed paper P is separated one by one by the paper feed roller 35 and the paper feed pad 36, passes through the registration roller 37, and is conveyed toward the photosensitive drum 51 and the transfer roller 53.

  The exposure apparatus 4 is provided at an upper portion in the main body housing 2 and mainly includes a laser light emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42 and 43, and reflecting mirrors 44 and 45. The laser light (refer to the chain line) based on the image data emitted from the laser emission unit is reflected or passed through the polygon mirror 41, the lens 42, the reflecting mirror 44, the lens 43, and the reflecting mirror 45 in this order, and the surface of the photosensitive drum 51. Irradiated at high speed.

  The process unit 5 is disposed below the exposure apparatus 4 and is configured to be detachably attached to the main body housing 2 through an opening formed when the front cover 21 provided on the main body housing 2 is opened. Yes. The process unit 5 includes a photoconductor unit 100 and a developing unit 200 that is detachably attached to the photoconductor unit 100.

  The photoconductor unit 100 mainly includes a photoconductor drum 51 as an example of a photoconductor, a charger 52, and a transfer roller 53 in a photoconductor frame 110. Further, the developing unit 200 mainly includes a developing roller 54, a supply roller 55, a layer thickness regulating blade 56, an agitator 57, and a toner container 58 in the developing frame 210. The detailed configuration of the process unit 5 will be described later.

  In the process unit 5, the surface of the photosensitive drum 51 is uniformly charged by the charger 52 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby image data is transferred onto the photosensitive drum 51. An electrostatic latent image based on is formed. The toner in the toner container 58 is supplied to the developing roller 54 via the supply roller 55 and enters between the developing roller 54 and the layer thickness regulating blade 56 to form a thin layer having a constant thickness. Supported on.

  The toner carried on the developing roller 54 is supplied from the developing roller 54 to the electrostatic latent image formed on the photosensitive drum 51. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 51. Thereafter, the sheet P is conveyed between the photosensitive drum 51 and the transfer roller 53, whereby the toner image on the photosensitive drum 51 is transferred onto the sheet P.

  The fixing device 6 is provided behind the process unit 5, and mainly includes a heating roller 61 and a pressure roller 62 that sandwiches the paper P between the heating roller 61. The toner image transferred onto the paper P is thermally fixed by the paper P being conveyed between the heating roller 61 and the pressure roller 62. The sheet P on which the toner image is thermally fixed is conveyed from the fixing device 6 to the discharge path 23 and is discharged from the discharge path 23 onto the discharge tray 22 by the discharge roller 24.

Next, the detailed configuration of the process unit 5 and the main body housing 2 will be described focusing on the features of the present invention.
<Detailed configuration of process unit>
2 is a side view showing the configuration of the process unit 5 according to the present embodiment, FIG. 3 is a sectional view taken along the line III-III of FIG. 2, and FIG. 4 is a perspective view showing the configuration around the pinch roller.

  In the following description, the configuration on the one end side of the pinch roller (conveying roller) will be described in detail. However, in the present embodiment, the same configuration is provided on the other end side, although it is symmetrical with the one end side. Yes. In the following description, the axially inner side (left side in FIG. 3) of the developing roller and the pinch roller is simply referred to as “inside”, and the axially outer side (right side in FIG. 3) is simply referred to as “outer side”.

  As shown in FIG. 2, the process unit 5 includes a photoconductor unit 100 and a developing unit 200 that is detachably attached to the photoconductor unit 100 (photoconductor frame 110).

[Configuration of photoconductor unit]
The photoconductor unit 100 includes a photoconductor frame 110 that constitutes a frame of the photoconductor unit 100 and supports the photoconductor drum 51 (drum shaft 51A), a pinch roller 120 as an example of a transport roller, and a roller support member. And a bearing member 130 as an example.

  The pinch roller 120 is provided in front of the lower surface of the photoconductor frame 110. The pinch roller 120 comes into contact with the registration roller 37 from above when the process unit 5 is mounted on the main body housing 2, and is rotated by the driving force of the registration roller 37 that is driven to rotate together with the registration roller 37. The paper P is conveyed (see FIG. 1).

  As shown in FIG. 3, the bearing member 130 is provided at both left and right ends of the pinch roller 120, and receives a cylindrical bearing portion 131 that rotatably receives the roller shaft 121 of the pinch roller 120, and an inner end portion of the bearing portion 131. The extending portion 132 extends upward, and the engaging portion 133 extends inward from the upper end of the extending portion 132.

  The bearing member 130 (bearing portion 131) is disposed in a recess 111 provided at a lower portion near the front side of the side surface of the photoconductor frame 110. As shown in FIG. 4, the bearing member 130 is supported by a pair of protruding portions 132 </ b> A provided before and after the extending portion 132 by a pair of regulating portions 112 provided on the photoconductor frame 110. The falling off from the photoconductor frame 110 is prevented. Further, the bearing member 130 is prevented from rotating with respect to the photoconductor frame 110 by the extension portion 132 being sandwiched between the pair of restriction portions 112. With such a configuration, the bearing member 130 is supported by the photoconductor frame 110 and supports the pinch roller 120 rotatably with respect to the photoconductor frame 110.

  The bearing member 130 can move in the axial direction (left-right direction) of the pinch roller 120 with respect to the photosensitive member frame 110. The outward movement is restricted by the extension part 132 coming into contact with the photoconductor frame 110, and the inner movement is brought into contact with an urging member 220 described later (the developing unit 200 is mounted). If not, the bearing 131 is in contact with the roller main body 122 of the pinch roller 120), so that the bearing member 130 and the pinch roller 120 do not come out of the photoreceptor frame 110.

  Further, the bearing member 130 is supported in a state having play in the vertical direction (the engagement direction between a locking portion 133 and a locked portion 212 described later) with respect to the photoreceptor frame 110 (see FIG. 2). ). Specifically, the bearing member 130 is movable in the vertical direction from the lowest position where the convex portion 132 </ b> A contacts the upper surface of the restricting portion 112 to the uppermost position where the bearing portion 131 contacts the upper surface of the concave portion 111. Yes.

[Development unit configuration]
As shown in FIG. 2, the developing unit 200 constitutes a frame of the developing unit 200 to support the developing roller 54 (roller shaft 54A) and the like, and also includes a developing frame 210 that forms a toner containing portion 58, a main body housing, and the like. A biasing member 220 that releases the engagement between the locking portion 133 and the locked portion 212 when the process unit 5 is detached from the body 2 is provided.

  As shown in FIG. 3, on the left and right side surfaces of the developing frame 210, a cylinder for accommodating the urging member 220 at a position facing the engaging portion 133 when the developing unit 200 is mounted on the photosensitive unit 100. A shaped accommodating portion 211 is provided. Of the inner peripheral surface of the housing portion 211, the lower surface is a locked portion 212 that can engage with the locking portion 133 in the vertical direction.

  The urging member 220 is disposed in the accommodating portion 211 and has an abutting portion 221 that can abut on the locking portion 133, one end at the abutting portion 221, and the other end at the developing frame 210 (the bottom surface of the accommodating portion 211). And a coil spring 222 attached to each.

  In the state where the process unit 5 is detached from the main body housing 2 (the state shown in FIG. 3), the biasing member 220 has the tip of the contact portion 221 positioned outside the end of the locked portion 212. ing. As shown in FIG. 4, at the tip of the contact portion 221, the front side in the mounting direction of the developing unit 200 with respect to the photoconductor unit 100 (in this embodiment, the rear and lower portions of the tip) is obliquely left rearward (inside). An inclined surface 221A that is inclined toward the left side and an inclined surface 221B that is inclined toward the lower left side (inner side) are formed. In the present embodiment, an inclined surface 133 </ b> A that is inclined obliquely toward the lower left (inner side) is formed at the top of the tip of the locking portion 133.

  By providing such inclined surfaces 221A, 221B, and 133A, it is possible to prevent the locking portion 133 and the contact portion 221 from being caught with each other when the developing unit 200 is attached to the photosensitive unit 100. Specifically, when the developing unit 200 is mounted, the inclined surfaces 221A and 221B of the contact portion 221 and the inclined surface 133A of the locking portion 133 are in sliding contact with each other, so that at least the locking portion 133 (bearing member 130) is outside. Since it pushes (releases) toward, it can suppress that the latching | locking part 133 and the contact part 221 are caught. Thereby, since the developing unit 200 can be smoothly mounted on the photosensitive unit 100, the operability when the developing unit 200 is mounted can be improved.

<Detailed configuration of main unit casing>
Fig.5 (a) is a figure which shows the structure of a main body frame, (b) is BB sectional drawing of (a). In FIG. 5A, in order to show the positional relationship between each positioning groove and each roller of the process unit 5 mounted on the main body housing 2, the photosensitive drum 51, the developing roller 54, the pinch roller 120, and the like are shown. Shown with a chain line.

As shown in FIG. 5A, the main body housing 2 includes a pair of main body frames 25 located on both the left and right sides of the process unit 5 attached to the main body housing 2 (only one is shown in FIG. 5). .
The main body frame 25 has an upper positioning groove 300 as an example of a developing roller positioning groove and a lower positioning groove as an example of a conveying roller positioning groove that extend obliquely downward from the front (in the direction in which the process unit 5 is mounted). 400 is provided.

  The upper positioning groove 300 is a groove that guides the inserted drum shaft 51A and roller shaft 54A when the process unit 5 is mounted, and determines the positions of the photosensitive drum 51 and the developing roller 54 with respect to the main body housing 2. The upper positioning groove 300 fixes the position of the photosensitive drum 51 by urging the drum shaft 51 </ b> A toward the rear end of the upper positioning groove 300 when the process unit 5 is mounted in the main body housing 2. A spring 301 and a spring 302 that fixes the position of the developing roller 54 by urging the roller shaft 54A toward the drum shaft 51A are provided.

  The lower positioning groove 400 guides the inserted bearing member 130 when the process unit 5 is mounted, and determines the position of the pinch roller 120 relative to the main body housing 2 by determining the position of the bearing member 130 relative to the main body housing 2. It is a groove that decides. The lower positioning groove 400 includes a first guide part 410, a second guide part 420, and a positioning part 430 that continuously extend from the opening end side (front side).

  Each first guide portion 410 provided in each of the pair of body frames 25 extends such that the mutual groove bottom portions 401 (surfaces facing in the left-right direction) are substantially parallel to each other. Further, the groove side portion 402 on the lower side of the first guide portion is provided with a mountain-shaped protruding portion 411 that protrudes upward (backward obliquely upward).

  The 2nd guide part 420 is continuously extended from the 1st guide part 410, and it inclines toward the inner side as the groove bottom part 401 goes back from the front (refer FIG.5 (b)). Thereby, each 2nd guide part 420 each provided in a pair of main body frame 25 is gradually narrowed as the space | interval of a mutual groove bottom part 401 goes back from the front.

  Each positioning portion 430 provided in each of the pair of main body frames 25 extends so that the groove bottom portions 401 are substantially parallel to each other. However, since it extends continuously from the rear end of the second guide portion 420, the groove bottom portion 401 of each positioning portion 430 has a smaller interval than the first guide portion 410. When the bearing member 130 reaches the positioning portion 430, the position of the bearing member 130 (pinch roller 120) with respect to the main body housing 2 is determined.

  A torsion spring 431 as an example of a roller urging member is provided above the positioning portion 430. The torsion spring 431 urges the bearing member 130 that has reached the positioning portion 430 downward, thereby pressing the locking portion 133 engaged with the locked portion 212 toward the locked portion 212. Then, the pinch roller 120 is pressed toward the registration roller 37 (see FIG. 9).

<Effects of laser printer>
The operational effects of the laser printer 1 configured as described above will be described. FIG. 6 is a diagram illustrating a state in which the bearing member is inserted into the lower positioning groove, FIG. 7 is a diagram illustrating a state in which the bearing member is lifted by the protruding portion of the first guide portion, and FIG. It is a figure which shows a mode that it moves inside by the groove bottom part of a 2nd guide part, FIG. 9 is a figure which shows a mode that a bearing member is urged | biased by the torsion spring of a positioning part. In each figure, (a) is a view of the main body casing and the process unit as viewed from the inside, (b) is a cross-sectional view taken along the line BB of (a), and (c) is a state around the pinch roller. FIG.

  As shown in FIGS. 6A to 6C, when the process unit 5 is mounted on the main body housing 2, the drum shaft 51A and the roller shaft 54A are inserted into the upper positioning groove 300 and the bearing portion of the bearing member 130 is inserted. 131 is inserted into the lower positioning groove 400 and the process unit 5 is pushed backward. When the bearing member 130 is inserted into the lower positioning groove 400 (first guide portion 410), the lower end of the locking portion 133 is at the same position as the locked portion 212 in the vertical direction. Hereinafter, the operation of the bearing member 130 will be described in detail.

  As shown in FIGS. 7A to 7C, the bearing member 130 that moves rearward and obliquely downward along the lower positioning groove 400 is moved upward by the protruding portion 411 (the locking portion 133 is engaged in the locking direction). And moved upward in the recess 111 of the photoconductor frame 110. Thereby, behind the protrusion part 411, the lower end of the latching | locking part 133 can be made into the state which exists above the to-be-latched part 212. FIG.

  As shown in FIGS. 8A to 8C, the bearing member 130 in which the lower end of the locking portion 133 is lifted above the locked portion 212 is provided at the groove bottom portion 401 of the second guide portion 420. It moves toward the inside by the tilt. Thereby, the latching | locking part 133 pushes the contact part 221 inside.

  9A to 9C, when the bearing member 130 reaches the positioning portion 430, the bearing member 130 is urged downward by the torsion spring 431, so that the locking portion 133 is pressed. Is pressed and engaged with the locked portion 212. Thereby, the bearing member 130 (pinch roller 120) is positioned and fixed with respect to the main body frame 25 (main body housing 2). In the present embodiment, since the lower end of the locking portion 133 is above the locked portion 212 due to the action of the protruding portion 411 provided in the first guide portion 410, the locking portion 133 that moves inwardly. Can be reliably engaged with the locked portion 212.

  The drum shaft 51A (photosensitive drum 51) and the roller shaft 54A (developing roller 54) also reach the rear end of the upper positioning groove 300 and are biased by the springs 301 and 302, so It is positioned and fixed with respect to it. As described above, the process unit 5 is mounted on the main housing 2 and positioned and fixed.

  In the present embodiment, the developing unit 200 (developing frame 210) can be pressed downward toward the photosensitive unit 100 by pressing the locking part 133 against the locked part 212. Therefore, the developing unit 200 can be firmly fixed to the photoconductor unit 100 and the main body housing 2 to which the photoconductor unit 100 is fixed.

  As a result, compared with a configuration in which the shaft of the developing roller is simply inserted into the positioning groove (slit), it is possible to suppress the fine movement of the developing roller 54 when the developing roller 54 is driven to rotate. The photosensitive drum 51 can be held in parallel. As a result, toner can be uniformly supplied from the developing roller 54 to the electrostatic latent image on the photosensitive drum 51, so that the image quality in the laser printer 1 can be improved.

  When the process unit 5 is mounted on the main housing 2, the contact portion 221 is pushed inward by the locking portion 133, so that the coil spring 222 is in a compressed state (see FIG. 9). . Therefore, when the process unit 5 is detached from the main body housing 2 (when the bearing member 130 is detached from the positioning portion 430), the coil spring 222 causes the locking portion 133 to face outward via the contact portion 221. By pushing, the engagement between the locking portion 133 and the locked portion 212 can be automatically released.

  Thus, when the developing unit 200 is detached from the photosensitive unit 100, the engagement between the locking portion 133 and the locked portion 212 is released, so that the developing unit 200 is used as it is. Can be disengaged from. In other words, when the developing unit 200 is detached, it is possible to save the user himself from performing an operation of releasing the engagement between the locking portion 133 and the locked portion 212. As a result, the operability when the developing unit 200 is detached can be improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the embodiment, the bearing member 130 that rotatably receives the roller shaft 121 provided on the pinch roller 120 is illustrated as the roller support member, but the present invention is not limited to this. For example, a configuration may be adopted in which a shaft is provided on the roller support member side and the shaft is supported by inserting the shaft into a hole provided at an end of the transport roller.

  In the above embodiment, the configuration in which both the abutting portion 221 and the locking portion 133 of the biasing member 220 have the inclined surfaces 221A, 221B, and 133A is shown, but the present invention is not limited to this. Only one of the part and the locking part may have an inclined surface.

  In the above-described embodiment, the urging member 220 including the contact portion 221 and the coil spring 222 is illustrated as the urging member provided in the developing unit. However, the present invention is not limited to this. For example, you may employ | adopt the leaf | plate spring which makes | forms the cross-sectional view substantially S shape arrange | positioned in the accommodating part 211 like the biasing member 230 shown in FIG. According to this, compared with the case where a biasing member is comprised combining two or more members, cost reduction can be aimed at, or the workability | operativity at the time of an assembly can be improved.

  In the above embodiment, the developing unit is provided with the urging member that releases the engagement between the locking portion and the locked portion when the process unit is detached from the apparatus main body. However, the biasing member may be provided in the photosensitive unit.

  For example, as shown in FIG. 11, the urging member 140 provided in the photosensitive unit 100 is a coil spring and is fitted on the roller shaft 121 of the pinch roller 120, and is interposed between the roller body 122 and the bearing member 130. Has been placed. When the process unit 5 is mounted on the main body housing 2, the biasing member 140 is compressed by the bearing member 130 moved inward to bias the bearing member 130 (bearing portion 131) outward. . When the process unit 5 is detached from the main body housing 2, the urging member 140 can release the engagement between the locking portion 133 and the locked portion 213 by pushing the bearing member 130 outward. it can.

  The locked portion 213 is provided in place of the above-described locked portion 212 (accommodating portion 211), and is formed in a rib shape extending outward from the left and right side surfaces of the developing frame 210. Yes. Since the operation of the locking portion 133 and the locked portion 213 is the same as that of the locking portion 133 and the locked portion 212 described above, the description thereof is omitted.

  The urging member 140 (coil spring) may be in contact with the photoconductor frame 110 instead of the roller body 122 at the inner end. For example, as shown in FIG. 12, the bearing member 130 is provided with an abutting wall portion 134 that extends downward from the side surface of the bearing portion 131 (outside the photoreceptor frame 110), and the urging member 140 is disposed on the photoreceptor frame 110 and the abutting wall. You may arrange | position between the parts 134. FIG. According to this, since the urging member 140 does not directly press the pinch roller 120 (roller body 122), the pinch roller 120 can be smoothly rotated.

  Further, as shown in FIG. 13, the bearing member 130 is provided with an abutting wall portion 135 extending outward from the entire side surface of the bearing portion 131, and the urging member 140 is fitted to the bearing member 130, so that the photoconductor frame 110 is provided. And the abutting wall portion 135 may be disposed. Further, as shown in FIG. 14, the photoreceptor frame 110 is provided with a contact wall portion 113 positioned between the roller body 122 and the bearing member 130 (bearing portion 131), and the urging member 140 is fitted to the roller shaft 121. In this state, it may be disposed between the abutting wall portion 113 and the bearing member 130. According to these, since the urging member 140 is arranged coaxially with the roller shaft 121, the pinch roller 120 can be rotated more smoothly.

In the above-described embodiment, the torsion spring 431 is exemplified as the roller urging member. However, the present invention is not limited to this, and may be a leaf spring, for example.
In the above embodiment, the photosensitive drum 51 is exemplified as the photosensitive member, but the present invention is not limited to this, and for example, a photosensitive belt or the like may be adopted.

In the above embodiment, the laser printer 1 is exemplified as the image forming apparatus. However, the present invention is not limited to this, and may be, for example, a copying machine or a multifunction machine.
In the above-described embodiment, the paper P such as so-called plain paper or postcard is exemplified as the recording sheet. However, the present invention is not limited to this, and may be, for example, an OHP sheet.

1 is a cross-sectional view illustrating a schematic configuration of a laser printer as an example of an image forming apparatus. It is a side view which shows the structure of the process unit 5 which concerns on embodiment of this invention. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is a perspective view which shows the structure around a pinch roller. (A) is a figure which shows the structure of a main body frame, (b) is BB sectional drawing of (a). It is a figure which shows a mode that the bearing member was inserted in the lower positioning groove, (a) is the figure which looked at the main body housing | casing and the process unit from the inside, (b) is BB sectional drawing of (a). (C) is a diagram showing a state around the pinch roller. It is a figure which shows a mode that a bearing member is lifted by the protrusion part of a 1st guide part, (a) is the figure which looked at the main body housing | casing and the process unit from the inner side, (b) is BB of (a). It is sectional drawing, (c) is a figure which shows the mode around a pinch roller. It is a figure which shows a mode that a bearing member moves inside by the groove bottom part of a 2nd guide part, (a) is the figure which looked at the main body housing | casing and the process unit from the inside, (b) is B of (a). It is -B sectional drawing, (c) is a figure which shows the mode around a pinch roller. It is a figure which shows a mode that a bearing member is urged | biased by the torsion spring of a positioning part, (a) is the figure which looked at the main body housing | casing and the process unit from the inner side, (b) is BB of (a). It is sectional drawing, (c) is a figure which shows the mode around a pinch roller. It is a figure which shows the modification of the urging | biasing member provided in a developing unit. FIG. 6 is a cross-sectional view showing a configuration around a pinch roller of a process unit in which a biasing member is provided in a photosensitive unit. It is a figure which shows the modification of FIG. It is a figure which shows the other modification of FIG. It is a figure which shows another modification of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Main body housing | casing 5 Process unit 25 Main body frame 51 Photoconductor drum 54 Developing roller 54A Roller shaft 100 Photoconductor unit 110 Photoconductor frame 120 Pinch roller 121 Roller shaft 130 Bearing member 133 Locking part 133A Inclined surface 200 Developing unit 210 Developing frame 212 Locked portion 220 Energizing member 221 Abutting portion 221A Inclined surface 221B Inclined surface 222 Coil spring 300 Upper positioning groove 400 Lower positioning groove 401 Groove bottom portion 402 Groove side portion 410 First guide portion 411 Protruding portion 420 First 2 Guide part 430 Positioning part 431 Torsion spring P Paper

Claims (7)

The image forming apparatus main body includes a photosensitive unit having a photosensitive member supported by the photosensitive frame, and a developing unit having a developing roller supported by the developing frame and detachably attached to the photosensitive unit. A process unit that is detachably attached to the unit,
The photosensitive member unit, said the side on which the photoconductor is arranged in the detachable direction of the process unit provided on the opposite side, a conveying roller for conveying the recording sheet, and rotatably supporting the conveyance roller, and A roller support member movable in the axial direction of the transport roller,
The roller support member is provided with a locking portion that extends inward in the axial direction of the transport roller and can be engaged with a locked portion provided in the developing frame,
When the roller support member is moved inward in the axial direction of the transport roller when the image forming apparatus main body is mounted and positioned, the locking portion presses the developing unit against the photosensitive unit. A process unit that engages with a locked portion.   The developing unit is configured such that when the process unit is detached from the main body of the image forming apparatus, the engaging portion is disposed on the outer side in the axial direction of the conveying roller in order to release the engagement between the engaging portion and the locked portion. The process unit according to claim 1, further comprising an urging member that is pushed toward the surface. The biasing member has a contact portion that can contact the locking portion,
At least one of the contact portion and the locking portion is an inclined surface that slides against the other and pushes the roller support member toward the outside in the axial direction of the transport roller when the developing unit is mounted on the photosensitive unit. The process unit according to claim 2, comprising:   The process unit according to claim 1, wherein the photoconductor unit includes a biasing member that biases the roller support member toward an outer side in the axial direction of the transport roller.   The process unit according to claim 4, wherein the biasing member has an end on the inner side in the axial direction of the transport roller in contact with the photoconductor frame. The device body;
A photosensitive unit having a photosensitive member supported by the photosensitive frame; and a developing unit having a developing roller supported by the developing frame and detachably attached to the photosensitive unit; A process unit that is detachably mounted,
An image forming apparatus comprising a pair of main body frames located on both sides of the process unit mounted on the apparatus main body,
The photosensitive unit includes a conveyance roller that conveys a recording sheet, and a roller support member that rotatably supports the conveyance roller and is movable in the axial direction of the conveyance roller,
The roller support member is provided with a locking portion that extends inward in the axial direction of the transport roller and can be engaged with a locked portion provided in the developing frame,
The pair of body frames guides the shaft of the developing roller when the process unit is mounted and determines a position of the developing roller with respect to the apparatus body, and the roller support member when the process unit is mounted. A conveyance roller positioning groove for guiding and determining a position of the conveyance roller with respect to the apparatus main body,
A first guide portion extending from the opening end side along the mounting direction of the process unit and a second guide portion inclined toward the inner side in the axial direction of the transport roller at the groove bottom portions of the pair of transport roller positioning grooves And a positioning portion for determining the position of the transport roller with respect to the apparatus main body,
The positioning portion is provided with a roller urging member that urges the roller support member in a direction in which the locking portion engaged with the locked portion is pressed against the locked portion.
When the process unit is mounted to the apparatus main body, the roller support member is moved inward in the axial direction of the transport roller by the second guide portion, and the locking portion engages with the locked portion. When the roller support member reaches the positioning portion, the roller urging member presses the locking portion against the locked portion to press the developing unit against the photosensitive unit. apparatus. The roller support member is supported in a state having play in the engaging direction of the locking portion and the locked portion with respect to the photoconductor frame,
The groove side part below the first guide part is provided with a protruding part for lifting the roller support member in a direction in which the locking part moves away from the locked part in the locking direction. The image forming apparatus according to claim 6.

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