JP5093272B2 - Process cartridge and image forming apparatus - Google Patents

Description

  The present invention relates to a configuration of a process cartridge used in an electrophotographic image forming apparatus in a multifunction machine, a facsimile machine, a laser printer, or the like.

  2. Description of the Related Art Conventionally, there are some image forming apparatuses such as electrophotographic printers in which a process cartridge is detachably mounted. The process cartridge is configured such that a developing cartridge having a developing roller is detachable from a photosensitive cartridge having a photosensitive member. The photosensitive cartridge has a developing cartridge storage portion that detachably stores the developing cartridge and opens upward. The guide groove that guides the developing roller toward the photosensitive member when the developing cartridge is mounted on the photosensitive cartridge is formed in an arc shape downward from the developing cartridge housing portion.

  When the developing cartridge is mounted from above the photoconductor cartridge, the developing roller is guided to a position facing the photoconductor while having both ends of the developing roller run along arcuate guide grooves. When the developing cartridge is stored in the developing cartridge storage portion, the developing cartridge is pressed toward the photoconductor by the pressing portion provided in the photoconductor cartridge.

  In the process of mounting the developing cartridge, both ends of the developing roller shaft receive a force guided in the direction of the photosensitive member on the guide groove by gravity when the guide groove has an arc shape. Therefore, the developing roller can be brought close to the photosensitive member before the developing cartridge is pressed by the pressing portion. Therefore, when the developing roller is pressed against the photoconductor, the burden on the photoconductor can be reduced.

JP 2000-250310 A

  On the other hand, image forming apparatuses are required to be miniaturized while realizing multiple functions. In recent years, there is a strong demand for the apparatus to have a double-sided printing function, and the height of the apparatus body tends to increase. Therefore, special consideration is required for the height of the apparatus, and it has become necessary to make the process cartridge thinner in order to suppress the height of the apparatus body. For this purpose, it is conceivable to reduce the thickness of the conventional guide portion formed in an arc shape toward the lower side as a linear shape extending along the direction in which the photosensitive member and the accommodating portion are adjacent to each other.

  However, if the guide portion is a straight line extending in the direction in which the photosensitive member and the developing cartridge housing portion are adjacent to each other, when the developing cartridge is mounted on the photosensitive member cartridge from above, the photosensitive roller and the developing cartridge housing portion are exposed to the photosensitive roller at both ends. Forces in the body direction become difficult to work. Therefore, it is difficult for the developing roller to be guided toward the photoconductor. Accordingly, the developing cartridge is pressed by the pressing portion in a state where the developing roller is not sufficiently close to the photoreceptor. Then, there is a problem that the developing roller is pressed with a momentum with respect to the photoconductor, and a load is applied to the photoconductor, as compared with the case where the guide groove has an arc shape.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a process cartridge and an image forming apparatus capable of mounting a developing cartridge with less burden on the photosensitive member while realizing a reduction in thickness.

In order to achieve the above object, the process cartridge according to claim 1 has a developing roller shaft, and includes a developing roller that carries a developer, and a first housing that supports the developing roller, A developing cartridge extended so that both end portions of the developing roller shaft protrude outward from the first housing; a photosensitive drum on which an electrostatic latent image is formed; A photosensitive cartridge having a second housing for detachably housing the cartridge, wherein the second housing is provided adjacent to the drum support portion for supporting the photosensitive drum, and the drum support portion. And a cartridge housing part that detachably accommodates the developing cartridge, and the second housing supports both ends of the photosensitive drum, and forms the drum support part and the cartridge housing part. A support side wall, and a pressing portion that is provided in the cartridge housing portion and presses the developing cartridge toward the photosensitive drum, and the support side wall has the developer cartridge housed in the cartridge housing portion. Forming a first guide portion for guiding both end portions of the developing roller shaft so as to guide the developing roller to a position facing the photosensitive drum, and the first guide portion includes the drum support portion and the drum supporting portion. The cartridge housing portion is formed in a linear shape extending along the direction adjacent to the cartridge housing portion, the first housing includes a pressed portion that is pressed by the pressing portion, and the second housing includes the developing roller shaft. A second guide for guiding the developing cartridge toward the photosensitive drum before the pressed portion is pressed by the pressing portion. Have a, the second guide portion, wherein disposed between the in the direction orthogonal to the rotation axis direction of the photosensitive drum and the first guide portion and the pressing portion and said Rukoto.

  If the first guide portion is a straight line extending along the direction in which the drum support portion and the cartridge housing portion are adjacent to each other, the force acting on the developing cartridge by gravity when both end portions of the developing roller shaft are guided to the first guide portion. Among these components, the component in the direction toward the photosensitive drum is reduced on the first guide portion. For this reason, the developing roller cannot be brought sufficiently close to the photosensitive member before the developing roller is pressed against the photosensitive member.

  According to the process cartridge of the first aspect, when the both end portions of the developing roller shaft are guided to the guide portion, the developing cartridge and the second housing are provided before the pressing portion and the pressed portion come into contact with each other. The second guide portion contacts and guides the developing cartridge toward the photosensitive drum.

  As a result, even if the guide portion is linear, the developing roller can be brought close to the photosensitive member before the developing roller is pressed against the photosensitive member, and then pressed against the photosensitive member. Therefore, it is possible to mount the developing cartridge with less burden on the photosensitive drum.

Further , the cartridge can be miniaturized by arranging the second guide portion between the first guide portion and the pressing portion in a direction perpendicular to the axial direction of the photosensitive drum.

It is sectional drawing on the left side of a laser printer. It is a perspective view from the left front of the photosensitive member cartridge. FIG. 6 is a left side view of the photoreceptor cartridge. It is a perspective view of a bearing body and an upper conveyance roller. FIG. 3 is a perspective view of the developing cartridge from the left front. FIG. 6 is a left side view of the developing cartridge. FIG. 5 is a cross-sectional view taken near the first guide portion of the present application, showing a process of mounting the developing cartridge to the photosensitive cartridge (at the initial stage of mounting). FIG. 6 is a cross-sectional view taken near the first guide portion of the present application showing a process of mounting the developing cartridge to the photosensitive cartridge (during mounting). FIG. 6 is a cross-sectional view taken near the first guide portion of the present application showing a mounting process of the developing cartridge with respect to the photosensitive cartridge (when mounting is completed).

<Configuration of entire image forming apparatus>
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

  FIG. 1 is a left sectional view of a laser printer 1 as an example of an image forming apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the laser printer 1 includes a feeder unit 3 for feeding paper P into a main body casing 2, an image forming unit 4 for forming an image on the fed paper P, and the like. ing.

  A rear cover (not shown) that can be opened and closed is provided on the rear surface of the main casing 2 (in the following description, described using the vertical direction and the front-rear direction in FIG. 1). A process cartridge 30, which will be described later, is detachable from the opening.

  The feeder unit 3 includes a paper feed tray 11 that is detachably attached to the main casing 2 and a paper feed mechanism 15 that transports the paper P from the paper feed tray 11 to the image forming unit 4. The paper feed mechanism 15 has a known paper feed roller, separation roller, separation pad, and the like (reference numerals omitted).

  Further, the laser printer 1 includes transport roller pairs 17a and 17b on the downstream side of the paper transport mechanism 15 in the paper transport direction. The transport roller pairs 17a and 17b are roller pairs for transporting the paper P supplied from the feeder unit 3 to a pressure contact portion between a photosensitive drum 33 and a transfer roller 35, which will be described later. In the present embodiment, the upper transport roller 17a as an example of the transport roller is attached to the process cartridge 30 side described later.

  In the laser printer 1 described above, the paper P is separated from the paper P in the paper feed tray 11 one by one by the paper transport mechanism 15 of the feeder unit 3 and is transferred to the image forming unit 4 via the pair of transport rollers 17a and 17b. Be transported.

<Configuration of image forming unit>
The image forming unit 4 includes a scanner unit 20, a process cartridge 30, a fixing unit 80, and the like.

<Configuration of scanner unit>
The scanner unit 20 is provided at an upper portion in the main body casing 2 and includes a laser light emitting unit (not shown), a polygon mirror that is driven to rotate, a lens, a reflecting mirror, and the like. A laser beam based on image data emitted from the laser light emitting unit is irradiated onto the surface of the photosensitive drum 33 supported by the process cartridge 30 through a path L indicated by a chain line.

<Configuration of process cartridge>
The process cartridge 30 is disposed below the scanner unit 20 and is configured to be detachably attached to the main body casing 2. The process cartridge 30 includes a photosensitive cartridge 31 that supports a photosensitive drum 33 and a developer cartridge 60 that contains toner as an example of a developer therein.

  The photoconductor cartridge 31 mainly includes a photoconductor casing 32 as an example of a second casing constituting an outer frame, a photoconductive drum 33 provided in the photoconductor casing 32, a scorotron charger 34, and a transfer roller 35. ing.

  The developing cartridge 60 includes a developing roller 63, a supply roller 64, a layer thickness regulating blade 65, and an agitator 66 in a developer case 62 as a first housing that forms a developer storage chamber 61 that stores the developer. . Among these, the developing roller 63, the supply roller 64, and the agitator 66 are rotatably supported by the developer case 62. The toner stored in the developer storage chamber 61 is stirred by the agitator 66. The toner is conveyed to the supply roller 64 by the rotation of the agitator 66. The toner conveyed to the supply roller 64 by the agitator 66 is supplied to the development roller 63 and carried on the development roller 63 by the rotation of the supply roller 64. Thereafter, the thickness of the toner is regulated by the layer thickness regulating blade 65.

  The photosensitive drum 33 is rotatably supported by the photosensitive member casing 32 that is coupled to the developing cartridge 60. The photosensitive drum 33 has a drum main body grounded and a surface portion formed of a positively chargeable photosensitive layer.

  The scorotron charger 34 is disposed above the photosensitive drum 33 so as to face the photosensitive drum 33 at a predetermined interval. The scorotron charger 34 is a positively charged scorotron charger that generates corona discharge from a charging wire, and is configured to uniformly charge the surface of the photosensitive drum 33 to a positive polarity.

The transfer roller 35 is disposed below the photosensitive drum 33 so as to face and contact the photosensitive drum 33, and is rotatably supported by the photosensitive member casing 32. The transfer roller 35 is configured by covering a metal roller shaft with a conductive rubber material.

The surface of the photosensitive drum 33 is uniformly positively charged by the scorotron charger 34 and then exposed by scanning with a laser beam from the scanner unit 20. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed. Next, when the developing roller 63 rotates, the developer carried on the developing roller 63 is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 33 when it contacts the photosensitive drum 33. And a visible image is formed.

  Thereafter, the photosensitive drum 33 and the transfer roller 35 are rotationally driven so as to sandwich and convey the sheet P, and the sheet P is conveyed between the photosensitive drum 33 and the transfer roller 35, thereby causing the photosensitive drum 33 to move. The toner image carried on the surface is transferred onto the paper P.

<Configuration of fixing unit>
The fixing unit 80 is disposed on the downstream side of the process cartridge 30 in the sheet conveying direction, and includes a heating roller 81 and a pressure roller 82 that is disposed opposite to the heating roller 81 and sandwiches the sheet P between the heating roller 81. ing. In the fixing unit 80 configured as described above, the developer transferred onto the paper P is thermally fixed while the paper P passes between the heating roller 81 and the pressure roller 82. Thereafter, the paper P that has passed through the fixing unit 80 is discharged onto a paper discharge tray 86 by a paper discharge roller 85 disposed on the downstream side of the fixing unit 80 in the paper conveyance direction.

<Details of process cartridge structure>
Hereinafter, the embodiments will be described using directions defined in the drawing (front-rear direction, left-right direction, up-down direction).

(1) Photosensitive cartridge First, the structure of the photosensitive cartridge 31 will be described in detail with reference to the drawings as appropriate.

  FIG. 2 is a perspective view of the photosensitive cartridge 31 from the left front direction. FIG. 3 is a left side view of the photoconductor cartridge 31.

  As shown in FIG. 2, the photoconductor cartridge 31 includes a photoconductor casing 32. The photoreceptor casing 31 includes a drum support portion 40 that supports the photosensitive drum 33 in the front, and a cartridge storage portion 41 that detachably stores the developing cartridge 60 behind the drum support portion 40.

  The photoconductor casing 32 integrally includes a bottom wall 42 positioned on the bottom surface of the photoconductor casing 32 and a pair of support side walls 43 erected from both ends of the bottom wall 42 in the photoconductor axial direction. The upper ends on the front side of the pair of support side walls 43 are connected by an upper wall 44 extending in the axial direction of the photosensitive drum 33.

  The drum support portion 40 surrounded by the support side wall 43, the upper wall 44, and the bottom wall 42 accommodates the photosensitive drum 33, and the shaft A of the photosensitive drum 33 is rotatably supported by the left and right support side walls 43. The left and right support side walls 43 and the bottom wall 42 extend rearward from the place where the photosensitive drum 33 is disposed. The lower side of the transfer roller 35 disposed below the photosensitive drum 33 is covered with the bottom wall 42 of the photosensitive member casing 32.

A scorotron charger 34 is attached along the axial direction of the photosensitive drum 33 to the upper wall 44 that covers the upper side of the photosensitive drum 33 in the photosensitive member casing 32 and connects the left and right support side walls 43.
Further, the rear side of the drum support portion 40 is surrounded by a bottom wall 42 and left and right support side walls 43, and the upper portion is open. A cartridge storage portion 41 is formed so that the developing cartridge 50 can be attached and detached from the obliquely upper side. Yes. The cartridge housing portion 41 is disposed adjacent to the drum support portion 40 in the front-rear direction.

  As shown in FIG. 3, an example of a first guide portion that guides a shaft end portion of a developing roller shaft B, which will be described later, on the upper end surfaces of the left and right support side walls 43 of the photosensitive member casing 32 when the developing cartridge 60 is attached and detached. A roller shaft guide portion 45 is provided. In front of the roller shaft guide portion 45, a roller bearing insertion portion 54 that is continuously provided in front of the roller shaft guide portion 45 is formed. The roller bearing insertion portion 54 receives both ends of the developing roller shaft B guided by the roller shaft guide portion 45.

  The roller shaft guide portion 45 is formed in a straight line from the position adjacent to the rear side of the axis A of the photosensitive drum 33 along the direction in which the drum support portion 40 and the cartridge housing portion 41 are adjacent to each other. Specifically, the roller shaft guide portion 45 is located behind the axis A of the photosensitive drum 33 and below the axis A of the photosensitive drum 33 in the vertical direction. The roller shaft guide portion 45 extends in the front-rear direction while maintaining a substantially constant distance from the bottom wall 42 in the up-down direction. The rear end of the roller shaft guide 45 is positioned in front of the upper transport roller 17a in the front-rear direction.

  The roller bearing insertion portion 54 includes a first extending portion 54a extending upward from the front end portion of the roller shaft guide portion 45, and a second extending portion 54b extending rearward from the upper end portion of the first extending portion 54a. Is provided. The roller bearing insertion portion 54 is formed in a substantially rectangular shape in a side view by the front side of the roller shaft guide portion 45, the first extending portion 54a, and the second extending portion 54b.

  As described above, the drum support portion 40 and the cartridge housing portion 41 of the photosensitive cartridge 31 are adjacent to each other in the front-rear direction, and the roller shaft guide portion 45 is provided along the direction. Further, the roller shaft guide portion 45 is provided below the axis A of the photosensitive drum 33 in the vertical direction. With this configuration, it is possible to suppress the dimension in the height direction (vertical direction in the drawing) of the support side wall 43 corresponding to the portion where the roller shaft guide portion 45 is provided, and the process cartridge can be thinned. Become.

  By forming the roller shaft guide portion 45 in a straight line along the direction in which the drum support portion 40 and the cartridge housing portion 41 are adjacent to each other, the dimension of the process cartridge 30 in the height direction (upward direction in the figure) can be suppressed. This makes it possible to reduce the thickness of the process cartridge.

  The upper end surfaces of the left and right support side walls 43 connected to the rear from the end of the roller shaft guide 45 away from the photosensitive drum 33 are stepped so that the width from the bottom wall 43 increases as it goes rearward. 46 is formed. In the present embodiment, the staircase portion 46 has a first step surface 46 a, a second step surface 46 b, and a third step surface 46 c that form the steps of the staircase portion 46. The upper end of the first step surface 46a and the lower end of the second step surface 46b are connected by a first connecting portion 46d, and the upper end of the second step surface 46b and the third step surface 46c. Is connected at the second connection portion 46e. And from the upper end part of the 3rd level | step difference surface 46c, the 3rd connection part 46f is extended toward back. The first connection portion 46d and the second connection portion 46e are formed in a straight line so that the width from the bottom wall 42 increases toward the rear.

  By forming the stepped portion 46 on the upper end surface of the support side wall 43, a wide portion 49 is formed between the stepped portion 46 formed by the stepped surface and the connecting portion described above and the bottom wall 42. A circular through hole 50 through which the sensor light from the laser printer 1 can pass is provided below the second connection portion 46 e of the wide portion 49 so as to penetrate the wide portion 49 in the direction of the rotation axis of the photosensitive drum 33. It has been. Since the support side wall 43 has a stepped shape and the area of the side wall is increased, the through hole 50 can be provided in the wide portion 49 while maintaining the required strength of the photoconductor cartridge 31.

  The rear side of the bottom wall 42 in the photosensitive member casing 32 and both ends in the left-right direction are in contact with a pressed portion 72 provided in the developing cartridge 60 described later to press the developing cartridge 60 toward the photosensitive drum 33. A pair of pressing parts 51 is provided. The pressing portion 51 has a first contact surface 51a and a second contact surface 51b that contact the pressed portion 72 of the developing cartridge 60 (see FIG. 7).

  The pressing portion 51 is pivotally supported with respect to the photosensitive member casing 32 so as to be rotatable. Furthermore. The pressing portion 51 is urged from the rear to the front of the photoreceptor cartridge 31 by a spring (not shown). The first contact surface 51a and the second contact surface 51b are continuous in the vertical direction, and the first contact surface 51A is formed to be inclined rearward. The second contact surface 51 b is formed toward the photosensitive drum 33.

  Further, at the part where the support side wall 43 and the bottom wall 42 are connected, the left and right support side walls 43 where the later-described upper transport roller 17a is located are cut out in a substantially circular arc shape so that the upper transport roller 17a can move up and down. 53 is provided.

  Next, the bearing body 52 as an example of the second guide portion that pivotally supports the upper transport roller 17a will be described with reference to FIG. FIG. 4 is a perspective view showing a state in which the upper conveyance roller 17a is held on the bearing body 52. FIG.

  As shown in FIG. 4, the bearing body 52 includes a cylindrical portion 52b in which an insertion hole for inserting an end portion of the upper conveying roller 17a is formed, a support portion 52d in which the protruding portion 52a is formed, and a protruding portion 52a. A central protrusion 52f provided therebetween is a member formed integrally.

  A gap 52e is formed in the support portion 52d of the bearing body 52, and the support portion 52d is easily bent toward the central protrusion 52f.

  Further, as shown in FIG. 4, an inclined surface 52g is formed on the protrusion 52a of the support portion 52d. In a state where the conveyance roller 48 is attached to the photosensitive member cartridge 31, the inclined surface 52g located on the photosensitive drum 33 side is inclined toward the photosensitive drum 33 and toward the bottom wall 42 (see FIG. 7). .

  In addition, the bottom wall 42 of the photosensitive member casing 32 is provided with an opening 55 extending along the rotation axis direction of the photosensitive drum 33 (see FIG. 7). An upper transport roller 17 a is attached to the opening 55. When the bearing body 52 is attached to the photosensitive member casing 32, the supporting portion 52d is provided in the bottom wall 42 of the photosensitive member cartridge 31 in the opening 55 (see FIG. 7) provided along the rotation axis direction of the photosensitive drum 33. insert. At this time, since the support portion 52d is easily bent, it can be easily attached to the opening portion 55. The support portion 52 d protrudes the protruding portion 52 a from the opening portion 55 in a state where the support portion 52 d is attached to the photoconductor casing 32. The inclined surface 52g faces the roller shaft guide portion 45 side.

  Further, the upper conveying roller 17a has a protrusion 52a of a bearing body 52 attached to both ends of the upper conveying roller 17a and a bearing body support 56 formed integrally with the photosensitive body casing 32 of the photosensitive body cartridge 31. The upper conveying roller 17a is attached so as to be movable up and down.

That is, the upper conveying roller 17A is suspended from the photosensitive member casing 32 by the support portion 52d coming into contact with the peripheral edge of the opening 55 of the photosensitive member casing 32. by this,
The bearing body 52 is disposed at a first position where a bearing body support portion 56 and a projection 52a of the bearing body 52 described later contact each other. Moreover, the bearing body 52 is arrange | positioned in the position C where the cylindrical part 52a and the notch part 53 contact by receiving the force from the downward direction (refer FIG. 3). That is, the bearing body 52 is movable between the first position and the second position C.

  Thus, by allowing the upper conveyance roller 17a to move up and down, the upper conveyance roller 17a is not positioned with respect to the lower conveyance roller 17b on the image forming apparatus main body side. Accordingly, even when the process cartridge is replaced with a new process cartridge, the upper transport roller 17a is positioned only by the positioning condition of the positioning means provided on the image forming apparatus main body side. Accordingly, as shown in FIG. 1, the upper transport roller 17a is pressed against the lower transport roller 17b with a constant pressing force.

(2) Developing Cartridge Next, the structure of the developing cartridge will be described in detail using appropriate drawings.

  FIG. 5 is a perspective view of the developing cartridge 60 from the left front side. FIG. 6 is a left side view of the developing cartridge 60.

  As shown in FIG. 5, the developing cartridge 60 has a developing case 62. The developing case 62 is formed in a box shape whose front side is opened.

  The developing roller 63 is disposed so as to be exposed forward from the developing case 62, and is rotatably supported by a right side wall 67 of the developing case 62 and a gear holder 68 as a covering member described later. Specifically, the developing roller 63 has a developing roller shaft B at the rotation shaft center. The developing roller shaft B protrudes outward from the developing case 62 at both ends of the shaft. A developing bearing member 69 as an example of a protective member is provided on the right side wall 67 of the developing case 62 and the front end portion of the gear holder 68 as a cylindrical bearing member protruding outward. The developing bearing member 69 covers the peripheral surface of the developing roller shaft B. The developing roller shaft B of the developing roller 63 is rotatably supported by the developing bearing member. Thus, by covering the peripheral surface of the developing roller shaft B, the developing roller shaft B does not directly contact the roller bearing insertion portion 54. That is, it is possible to suppress the wear of the developing bearing insertion portion 54 due to the rotation of the developing roller shaft B at the contact point between the developing roller shaft B and the developing bearing insertion portion 54.

  Further, as shown in FIG. 5, a driving input portion 71 to which a driving force such as the developing roller 63 is input is provided on the left side wall 70 of the developing case 62 in front of the developing bearing member 69. The drive input unit 71 transmits the rotational driving force from the power source of the image forming apparatus main body to the gear mechanism unit provided on the left side wall 70 to rotate the developing roller 63, the supply path roller 64, and the agitator 66. FIG. 5 shows only the development drive gear 74 as drive force transmission means in the gear mechanism.

  The gear mechanism is covered with a gear holder 68 shown in FIG. The gear holder 68 has a substantially box shape and covers the upper side, the lower side, the left side, and the rear side of the gear mechanism portion.

  As shown in FIG. 6, the gear holder 68 has a holder bottom surface 68 a that covers the lower side of the development drive gear 74. The holder bottom surface 68 a is provided at a position facing the bottom wall 42 when the developing cartridge 60 is mounted on the photosensitive cartridge 31. The holder bottom surface 68a is a surface substantially parallel to a portion of the bottom wall 42 that faces the holder bottom surface 68a when the developing cartridge 60 is mounted on the photosensitive cartridge 31. Furthermore, from the rear end of the holder bottom surface 68a, there is a holder inclined surface 68b extending rearward and obliquely upward.

  As shown in FIG. 6, the developing cartridge 60 is pressed by the pressing portion 51 in the state where the developing cartridge 60 is attached to the photosensitive cartridge 31 at the rear portion of the left and right side walls of the developing case 62, so that the developing cartridge 60 is moved to the photosensitive drum. A cylindrical member 72 to be pressed in the 33 direction is provided. The pressed portion 72 protrudes in the direction of the developing roller shaft B and is formed integrally with the developing case 62.

  On the left and right side walls of the developing case 62 are provided window portions 73 that transmit laser light for detecting the remaining amount of toner emitted from the laser printer 1. In a state where the developing cartridge 60 is attached to the photosensitive cartridge 31, the window portion 73 faces the through hole 50 of the photosensitive cartridge 31 in the axial direction of the developing roller 63.

(3) Mounting of Development Cartridge on Photosensitive Cartridge Next, mounting of the developing cartridge 60 on the photosensitive cartridge 31 will be described with reference to FIGS. FIGS. 7 to 9 are cross-sectional views taken near the first guide portion showing the process of mounting the developing cartridge 60 on the photosensitive cartridge 31. FIG. The photoconductor cartridge 31 in FIGS. 7 to 9 is in a state where the photoconductor cartridge 31 is placed on a desk or the like, and an imaginary line F representing a grounding surface that contacts the bottom wall 40 of the photoconductor cartridge 31 at that time is described. In this state, the lower portion of the bearing body 52 is in contact with the imaginary line F, and the upper conveyance roller 17a is located above the first position where the support portion 56 and the protrusion 52a are in contact.

  The developing cartridge 60 is attached to the photosensitive cartridge 31 from above the photosensitive drum 33. When mounting, first, the developing bearing member 69 protruding from the right side wall 67 of the developing case 62 and the gear holder 68 is fitted into the roller shaft guide portion 45, respectively.

  When the developing cartridge 60 is pushed forward, the developing cartridge 60 moves forward while the developing bearing member 69 is guided by the roller shaft guide portion 45. During this movement, when the rear end of the developing cartridge 60 is pushed down toward the bottom wall 42 of the photosensitive cartridge 30, the holder inclined surface 68 b of the gear holder 68 of the developing cartridge 60 and the leading end 52 a of the bearing body 52 come into contact with each other. FIG. 7 shows the positional relationship between the photosensitive cartridge 31 and the developing cartridge 60 at this time. When the bearing body 52 and the holder inclined surface 68b come into contact with each other, the bearing body 52 bends backward due to the weight of the developing cartridge 60 and the force by which the developing cartridge 60 is pushed down. A force D in the direction toward the photosensitive drum 33 is applied to the gear holder 68 by a restoring force (repulsive force) generated by the bending of the bearing body 52. When the holder inclined surface 68 b and the bearing body 52 come into contact with each other, the developing cartridge 60 is guided in the direction toward the photosensitive drum 33 by the component force of gravity G acting on the developing cartridge 60. In other words, the developing cartridge 60 is guided toward the photosensitive drum 33 by the force pushed down and the force received from the bearing body 52.

  Thereafter, as shown in FIG. 8, the pressed member 72 provided in the developing case 62 and the first contact surface 51 a of the pressing member 51 come into contact with each other. In this state, the developing cartridge 60 is guided toward the photosensitive drum 33 by the bearing body 52, and the developing roller 63 is in a position sufficiently close to the photosensitive drum 33. More specifically, when the pressed member 72 is in contact with the first contact surface 51a, the developing roller 63 is substantially opposed to and not in contact with the photosensitive drum 33 (separated state).

  Then, when the rear end portion of the developing cartridge 60 is pushed downward against the pressing force of the pressing member 51, the pressing portion 51 rotates in the clockwise direction. The pressed member 72 moves downward along the pressing portion 51 and the first contact surface 51a and contacts the second contact surface 51b. In this state, the developing roller 63 faces the photosensitive drum 33 and is pressed against the photosensitive drum 33 by the pressing force of the pressing member 51, whereby the mounting of the developing cartridge 60 to the photosensitive cartridge 31 is completed.

  As shown in FIG. 9, when the mounting is completed, the pressing portion 51 is disposed on the broken line P connecting the shaft center of the photosensitive drum shaft A and the shaft center of the developing roller shaft B, and the broken line P and the roller shaft are arranged. The guide part 45 is substantially parallel. Moreover, in the mounting completion state, the protrusion 52a of the bearing body 52 is in a state separated from the holder inclined surface 68b of the gear holder.

  As described above, when the developing cartridge 60 is mounted on the photosensitive cartridge 30, when the developing bearing portion 69 is guided by the roller shaft guide portion 45, before the pressed portion 72 is pressed by the pressing portion 51, the upper side The process cartridge 30 is configured such that the bearing body 52 of the transport roller 17a and the gear holder 68 come into contact with each other. Then, when the bearing body 52 and the gear holder 68 come into contact with each other, a force in the direction of the photosensitive drum acts on the developing cartridge 30 due to gravity, and the developing roller 63 can be brought close to the photosensitive drum 33. Therefore, since the developing roller 63 can be pressed against the photosensitive drum 33 in a state where the developing roller 63 is sufficiently close to the photosensitive drum 33, it is possible to mount the developing cartridge 60 with less burden on the photosensitive drum 33.

  Further, by arranging the bearing body 52 between the roller shaft guide portion 45 and the pressing portion 51 in the direction perpendicular to the axial direction of the photosensitive drum 33, the second guide portion can be provided inside the photosensitive member cartridge 31. Therefore, the process cartridge 30 can be downsized.

  In this embodiment, the developing cartridge 60 is guided toward the photosensitive drum 33 when the gear holder 68 and the bearing body 52 come into contact with each other. Therefore, it is not necessary to newly provide a member for bringing the developing cartridge 60 into contact with the bearing body 52, and the configuration of the developing cartridge 60 can be simplified. Further, by covering the gear mechanism portion with the gear holder 68, it is possible to suppress damage to the gear mechanism portion due to contact between the gear mechanism portion and the photosensitive cartridge 31 when the developing cartridge 60 is attached to the photosensitive cartridge 31. .

  Further, in a state where the developing cartridge 60 is mounted on the photosensitive cartridge 31, the pressing portion 51 is disposed on the broken line P that connects the shaft center of the developing roller 63 and the shaft center of the photosensitive drum 33, and the broken line P and the roller shaft guide portion. The extending direction of 45 is configured in parallel. The pressing portion 51 is arranged in the pressing direction of the developing roller 63 against the photosensitive drum 33, and the direction of the broken line P and the roller shaft guide portion 45 is made parallel, so that the developing roller 63 is reliably pressed against the photosensitive drum 33. I can do it.

  Further, the support side wall 43 is provided continuously with the roller shaft guide portion 45, is located on the opposite side of the roller shaft guide portion 45 from the photosensitive drum 33, and has a width from the bottom wall 42 as the distance from the photosensitive drum 33 increases. A staircase 46 is formed as described above. When the developing cartridge 60 is mounted on the photosensitive cartridge 31, the developing cartridge 60 is mounted along the upper end surface of the support side wall 43 without positioning both ends of the developing roller shaft B on the roller shaft guide portion 45. At this time, both end portions of the developing roller shaft B are located away from the roller shaft guide portion 45 with respect to the photosensitive drum 33. Even in such a case, since the support side wall 43 has a stepped shape, the burden on the developing cartridge 60 is suppressed by guiding in stages, and both end portions of the developing roller shaft B are connected to the roller shaft guiding portion 45. Can lead to.

  Further, by using the bearing body 52 as the second guide portion, it is not necessary to newly provide a member as the second guide portion in the photoconductor cartridge 31, and the configuration of the photoconductor cartridge 31 can be simplified. it can.

  In addition, an inclined surface 52 g is provided at the tip 52 a of the bearing body 52. The inclined surface 52g is inclined in a direction toward the photosensitive drum and toward the bottom wall 42 in a state where the upper conveyance roller 17a is mounted on the photosensitive cartridge 31. Accordingly, since the gear holder 68 and the bearing body 52 are in smooth contact, the developing cartridge 60 can be mounted smoothly.

  Further, as described above, the bearing body 52 is attached to the photosensitive cartridge 31 so as to be movable up and down. When the developing cartridge 60 is mounted, the bearing body 52 and the gear holder 68 are in contact with each other in a state where the bearing body 52 is in a position in contact with the virtual line F shown in FIGS. Therefore, even if the bearing body 52 is attached to the photosensitive cartridge 31 so as to be movable up and down, the developing cartridge 60 is mounted on the photosensitive drum 33 with less burden on the photosensitive cartridge 31 on a desk or the like. I can do it.

  Further, both end portions of the developing roller shaft B are covered with a developing bearing member 69. Accordingly, when both end portions of the developing roller shaft B are guided by the roller shaft guide portion 45, damage to the developing roller shaft B can be suppressed. Further, by covering the peripheral surface of the developing roller shaft B, the developing roller shaft B does not directly contact the roller bearing insertion portion 54. That is, it is possible to suppress the wear of the developing bearing insertion portion 54 due to the rotation of the developing roller shaft B at the contact point between the developing roller shaft B and the developing bearing insertion portion 54.

  Further, by using the thinned process cartridge 30 in the laser printer 1, the apparatus main body can be thinned.

  Further, the present invention is not limited to the embodiments described with reference to the above description and drawings, and includes the following embodiments, for example.

  In the present embodiment, the bearing body 52 is used as an example of the second guide portion. However, the second guide portion may be provided integrally with the bottom wall 42.

  In the present embodiment, the bearing body 52 and the gear holder 68 are in contact with each other when the developing cartridge 60 is attached to the photosensitive cartridge 31, but may be configured to be in contact with the bottom surface of the developing cartridge 60.

  In this embodiment, the upper transport roller 17 a can be moved up and down, but the upper transport roller 17 a may be fixed to the photosensitive cartridge 31.

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Main body casing 17a Upper registration roller (cartridge side conveyance roller)
30 process cartridge 31 photoconductor cartridge 32 photoconductor casing 33 photoconductor drum 40 drum support portion 41 cartridge housing portion 45 roller shaft guide portion 46 step portion 49 wide portion 50 through hole 51 pressing portion 52 bearing member 60 developing cartridge 63 developing roller 68 gear holder 69 Development bearing member 71 Development drive gear 72 Pressed portion

Claims (10)

A developing roller having a developing roller shaft and carrying a developer; and a first housing supporting the developing roller, wherein both end portions of the developing roller shaft protrude outward from the first housing. A developing cartridge extended to
A photosensitive drum having a photosensitive drum on which an electrostatic latent image is formed, and a second housing that supports the photosensitive drum and detachably accommodates the developing cartridge;
The second housing includes a drum support portion that supports the photosensitive drum, and a cartridge housing portion that is provided adjacent to the drum support portion and removably houses the developer cartridge,
The second housing supports both end portions of the photosensitive drum, is provided in the cartridge housing portion, a support side wall that forms the drum support portion and the cartridge housing portion, and the developing cartridge faces the photosensitive drum. And a pressing part that presses
The support side wall is a first guide portion that guides both end portions of the developing roller shaft so as to guide the developing roller to a position facing the photosensitive drum when the developing cartridge is housed in the cartridge housing portion. Form the
The first guide portion is formed in a linear shape extending along a direction in which the drum support portion and the cartridge housing portion are adjacent to each other,
The first housing has a pressed part that is pressed by the pressing part,
When the both ends of the developing roller shaft are guided by the first guide portion, the second housing faces the developing cartridge toward the photosensitive drum before the pressed portion is pressed by the pressing portion. have a second guide portion for guiding Te,
The second guide portion, said process cartridge, wherein Rukoto disposed between in the direction orthogonal to the rotation axis direction of the photosensitive drum and the first guide portion and the pressing portion. In a state where the developing cartridge is mounted to the photosensitive member cartridge,
2. The process according to claim 1, wherein the pressing portion is disposed on a straight line connecting a rotating shaft of the photosensitive drum and the developing roller shaft, and the straight line and the first guide portion are parallel to each other. cartridge. The cartridge housing portion has a bottom wall located on the bottom surface of the cartridge housing portion,
The support side wall is provided continuously with the first guide part, and has a stepped part located on the opposite side of the photosensitive drum with respect to the first guide part,
The stepped portion, the process cartridge according to claim 1 or claim 2, characterized in that it is formed to have a width from said bottom wall as the distance from the photosensitive drum. The process according to claim 3 , wherein a through-hole penetrating in the axial direction of the photosensitive drum is provided in a wide portion between the stepped portion formed on the support side wall and the bottom wall. cartridge. The photosensitive cartridge has a conveyance roller for conveying a recording medium toward the photosensitive drum,
The process cartridge according to claim 1, wherein the second guide portion is a bearing body that pivotally supports the transport roller. The first housing includes a driving force transmitting means for transmitting a driving force to the developing roller at one end in the axial direction of the developing roller,
The drive transmission means is covered with a covering member that covers the drive transmission means,
The process cartridge according to claim 5 , wherein the bearing body guides the developing cartridge by contacting the covering member. The contact surface of the bearing body with the covering member is an inclined surface, and the inclined surface is formed so that the downstream side in the mounting direction of the developing cartridge with respect to the photosensitive cartridge is directed toward the bottom wall and the photosensitive drum. The process cartridge according to claim 6 , wherein the process cartridge is provided. In the process cartridge removable from the image forming apparatus main body,
When the process cartridge is not attached to the main body of the image forming apparatus, the bearing body is movably attached to the photosensitive cartridge,
When the lower portion of the bearing body is in a position in contact with the ground contact surface in contact with the bottom wall, the contact surface and the covering member are in contact with each other when the developing cartridge is attached to the photosensitive cartridge. The process cartridge according to claim 7 . The part which contacts said 1st guide part in the both ends of the said developing roller axis | shaft is covered with the protection member which protects the said both ends, The one of Claim 1-8 characterized by the above-mentioned. Process cartridge. An image forming apparatus characterized by comprising a process cartridge according to any one of claims 1 to claim 9.

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