JP2006308867A - Process cartridge and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge and an image forming apparatus capable of smoothly attaching and detaching a developing cartridge and positioning a photosensitive drum and a developing roller more accurately.
A positioning rib 132a4 is erected on the bottom of a developing cartridge case 132a constituting a casing and a frame of the developing cartridge 132. An engaging portion 131f that engages with the positioning rib 132a4 by accommodating the positioning rib 132a4 is formed at the bottom of the process case 131 in which the developing cartridge 132 is configured to be detachable. Then, the positioning rib 132a4 is engaged with the engaging portion 131f in a state where the developing cartridge 132 is mounted on the process case 131, so that the positioning of the process case 131 and the developing cartridge case 132a in the paper width direction is surely and accurately performed. Often done.
[Selection] Figure 5

Description

  The present invention relates to an image forming apparatus configured to form an image by developing an electrostatic latent image with a developer. The present invention also relates to a process cartridge that can be easily attached to and detached from the above-described image forming apparatus and used for an image forming process in the image forming apparatus.

As this type of image forming apparatus and process cartridge, one having a drum cartridge for accommodating a photosensitive drum and a developing cartridge (toner cartridge) detachably attached to the drum cartridge is known ( For example, see Patent Document 1 below). The developing cartridge is provided with a developing roller carrying toner for developing the electrostatic latent image formed on the photosensitive drum.
JP 2000-267547 A

  In this type of image forming apparatus and process cartridge, in order to perform an image forming operation satisfactorily, for example, to form an image without disturbance at a desired position on a recording medium (paper), the developing cartridge is a drum cartridge. It is necessary that the positioning of the drum cartridge and the developing cartridge (that is, the positioning of the photosensitive drum and the developing roller) is surely performed when mounted on the printer.

  However, in this type of conventional image forming apparatus and process cartridge, the drum cartridge and the developing cartridge are usually brought into contact with a pair of inner side surfaces of the developing cartridge housing portion of the drum cartridge and the outer side surface of the developing cartridge. Positioning was performed. In such a positioning structure, an error in the outer dimension of the drum cartridge (an error in the dimension between a pair of opposing inner surfaces in the developing cartridge housing portion), an error in the outer dimension of the developing cartridge, and the photosensitive member in each cartridge The addition of many errors, such as errors in the mounting positions of the drum and developing roller, has resulted in very poor positioning accuracy between the photosensitive drum and the developing roller.

  In particular, the dimension between the pair of inner side surfaces (hereinafter referred to as the accommodating part width) in the developing cartridge accommodating part, and the dimension between the pair of outer side surfaces in the developing cartridge (hereinafter referred to as developing cartridge width) are: Since it is larger than the maximum usable paper size in the image forming apparatus, the dimensional tolerance increases. Therefore, for example, the clearance between the inner side surface of the developing cartridge housing portion and the outer side surface of the developing cartridge is increased, so that the backlash in the sheet width direction of the developing cartridge in the drum cartridge may be increased. there were. On the other hand, when trying to reduce the clearance by reducing the clearance, it may be difficult to smoothly attach and detach the developing cartridge to and from the developing cartridge housing portion.

Means for Solving the Problems and Effects of the Invention

(1-1) A process cartridge according to the present invention includes a drum frame and a developing frame. The drum frame is configured to rotatably support a cylindrical photosensitive drum configured to form an electrostatic latent image. The developing frame rotatably supports the developing roller and is detachably attached to the drum frame. The developing roller is configured to be able to carry a developer for developing the electrostatic latent image on a peripheral surface thereof, and is disposed in parallel to the photosensitive drum so as to face the photosensitive drum. Yes.

  The present invention is characterized in that one of the drum frame and the developing frame is positioned on the drum frame and the developing frame in a direction parallel to the rotation center axis of the photosensitive drum (paper width direction). A rib that is different from the one of the drum frame and the developing frame, and engages with the rib for positioning the drum frame and the developing frame in the paper width direction. The department is equipped.

  In such a configuration, the drum frame and the developing frame are positioned by engaging the rib and the engaging portion.

  Here, a dimension from a position where the rib or the engaging portion is formed to a predetermined reference surface in the drum frame or the developing frame is smaller than the accommodating portion width or the developing cartridge width (the accommodating portion). Or less than half the width of the developing cartridge or the width of the developing cartridge). Therefore, the dimension from the position where the rib or the engaging portion is formed to the reference surface can be set with a small dimensional tolerance.

  Further, the dimensions of the rib and the engaging portion are extremely smaller than the accommodating portion width and the developing cartridge width. Therefore, the rib and the engaging portion can be formed so that the backlash when the rib is engaged with the engaging portion is reduced.

  Therefore, according to the present invention, the drum frame and the developing frame are set to have a relatively large clearance in the paper width direction so that the developing frame can be smoothly attached to and detached from the drum frame. Accurate positioning of the frame and the developing frame can be performed.

(1-2) The developing frame in the configuration (1-1) may be configured to store the developing roller and the developer, and may be stored detachably with respect to the drum frame.

  In this configuration, from the position where the rib or the engaging portion is formed, the reference surface (for example, one outer surface of the developing frame or one of the housing portions for housing the developing frame in the drum frame). Dimensional tolerances up to the inner surface) can be set small.

(1-3) In the configuration (1-1), the image forming apparatus further includes a process case and a developing cartridge, and the developing cartridge includes a developing cartridge case that forms a casing of the developing cartridge, and the process case includes the drum The developing cartridge case may be constituted by the developing frame. Here, the process case is configured to accommodate the photosensitive drum and is a member constituting a casing of the process cartridge. The developing cartridge is configured to accommodate the developing roller and the developer, and is detachably attached to the process case. That is, the rib is provided in one of the process case and the developing cartridge case, and the engaging portion is provided in the other different from the one.

  In such a configuration, the rib and the engaging portion are engaged by attaching the developing cartridge case to the process case. As a result, the process case that accommodates the photosensitive drum and the developing frame that accommodates the developing roller are positioned.

  Therefore, according to the present invention, the developing cartridge can be smoothly attached to and detached from the process cartridge, and positioning of the developing cartridge case and the process case (positioning of the photosensitive drum and the developing roller) is performed. It can be performed with higher accuracy.

(1-4) In the configurations (1-1) to (1-3), the rib or the engaging portion formed on the developing frame is disposed in the vicinity of the rotation center axis of the developing roller. Also good.

  In this configuration, the rib for positioning the drum frame and the developing frame when the developing frame supporting the developing roller is attached to the drum frame supporting the photosensitive drum. The engaging portion is provided in the vicinity of the rotation center axis of the developing roller disposed to face the photosensitive drum. Therefore, the positioning of the photosensitive drum and the developing roller can be performed with higher accuracy.

(1-5) In the configurations (1-1) to (1-4), the rib or the engaging portion formed on the developing frame is formed on the photosensitive drum in the longitudinal direction of the developing roller. It may be formed outside an area (effective image forming area) that can face the electrostatic latent image. This effective image forming area is formed to have substantially the same width or slightly wider than the area (effective latent image forming area) where the electrostatic latent image can be formed on the photosensitive drum.

  According to this configuration, the rib and the engaging portion can be formed at the end of the developing frame or the drum frame in the paper width direction. Therefore, the rib and the engaging portion can be formed in the vicinity of the reference surface. Therefore, positioning of the developing frame and the drum frame (positioning of the photosensitive drum and the developing roller) can be performed with higher accuracy.

  Further, the rib and the engaging portion may be formed in the vicinity of a drive gear disposed at an end portion of the photosensitive drum or the like for rotationally driving the photosensitive drum or the developing roller. Accordingly, it is possible to suppress the relative movement of the developing frame and the drum frame from being vibrated due to the rolling that may be vibrated in the driving gear due to the transmission of the rotational driving force to the driving gear.

(1-6) In the configuration (1-5), the image forming apparatus further includes a driving force transmitting portion for transmitting a rotational driving force to the developing roller, and the rib or the engagement formed on the developing frame. The joint portion may be disposed in the vicinity of the driving force transmission portion. Here, the driving force transmission unit is constituted by, for example, a concave portion or a convex portion formed at an end portion of the developing frame in order to transmit a rotational driving force from the main body frame side of the image forming apparatus to the developing frame. It may be. Alternatively, the driving force transmission portion is disposed at the end portion of the developing roller so as to mesh with a drum gear disposed at the end portion of the photosensitive drum that is rotationally driven by the rotational driving force transmitted from the main body frame side. You may be comprised from the other gear.

  In this configuration, a rotational driving force is transmitted to the developing roller by the driving force transmitting portion, so that the longitudinal direction (parallel to the paper width direction) with respect to the developing roller (and the developing frame). The external force may be applied in a vibrational manner along the other direction. In this respect, according to the present invention, the rib and the engaging portion engage with each other in the vicinity of the driving force transmitting portion, thereby positioning the developing frame and the drum frame in the paper width direction ( Fixed). Therefore, according to the present invention, even when the external force as described above is applied to the developing roller (and the developing frame), the rib and the engaging portion are worn or damaged as much as possible. The development frame can be stably attached to the drum frame.

(2-1) An image forming apparatus as an object of the present invention includes a main body frame on which the drum frame is detachably mounted in addition to the drum frame and the developing frame.

  A feature of the present invention is that the main body frame and the drum frame are provided with a positioning mechanism for positioning the main body frame and the drum frame in a direction parallel to the rotation center axis of the photosensitive drum (paper width direction). The one of the drum frame and the developing frame is provided with the rib similar to the configuration (1-1), and the other of the drum frame and the developing frame is different from the one, The engagement portion similar to the configuration (1-1) is provided.

  In this configuration, the main body frame and the drum frame are positioned in the paper width direction by the positioning mechanism. Then, the drum frame and the developing frame are positioned by the engagement of the rib and the engaging portion.

  According to the present invention, as in the configuration (1-1), the development frame can be smoothly attached to and detached from the drum frame, and the precision of the main body frame, the drum frame, and the development frame is improved. Good positioning can be performed.

(2-2) The developing frame in the configuration (2-1) may be configured to store the developing roller and the developer, and may be stored so as to be detachable from the drum frame.

(2-3) In the configuration (2-1), the apparatus further includes a process case and a developing cartridge, and the developing cartridge includes a developing cartridge case that constitutes a casing of the developing cartridge, and the process case includes the drum The developing cartridge case may be constituted by the developing frame. Here, the process case is configured to accommodate the photosensitive drum and is a member constituting a casing of the process cartridge. The developing cartridge is configured to accommodate the developing roller and the developer, and is detachably attached to the process case.

(2-4) The rib or the engaging portion formed on the developing frame in the configurations (2-1) to (2-3) may be disposed near the rotation center axis of the developing roller. Good.

(2-5) The rib or the engaging portion formed on the developing frame in the configurations (2-1) to (2-4) is formed on the photosensitive drum in the longitudinal direction of the developing roller. Further, it may be formed outside the region that can face the electrostatic latent image.

(2-6) In the configuration (2-5), the image forming apparatus further includes a driving force transmitting portion for transmitting a rotational driving force to the developing roller, and the rib or the engagement formed on the developing frame. The joint portion may be disposed in the vicinity of the driving force transmission portion.

(2-7) The rib or the engaging portion formed on the drum frame in (2-1) to (2-6) may be disposed in the vicinity of the positioning mechanism.

  According to such a configuration, the main frame, the drum frame, and the development frame can be positioned with higher accuracy.

  Hereinafter, embodiments of the present invention (embodiments that the applicant considers best at the time of filing of the present application) will be described with reference to the drawings.

<Overall configuration of laser printer>
FIG. 1 is a side sectional view of a laser printer 100 which is an embodiment of the image forming apparatus of the present invention.

  The laser printer 100 includes a main body 110 and a feeder unit 120 for supplying a recording medium (paper) to the main body 110. A process cartridge 130 for forming an image of a developer (toner) on a sheet is detachably mounted in the main body 110. Further, a scanner unit 140 that irradiates the photosensitive drum 133 provided in the process cartridge 130 with a laser beam is disposed in the main body 110. Further, in the main body 110, a paper feeding unit 150 for supplying paper toward the process cartridge 130, and a fixing unit for fixing an image formed by toner formed on the paper by the process cartridge 130 on the paper. 160 and a paper discharge unit 170 that discharges the paper that has passed through the fixing unit 160 to the outside of the laser printer 100.

<Terminology of “paper transport direction”, “paper width direction”, “front” and “back”>
The laser printer 100 is configured such that a sheet is conveyed along a sheet conveyance path PP (paper path: indicated by a two-dot chain line in the drawing). Therefore, in the following description, a direction from the feeder unit 120 toward the paper discharge unit 170 along the paper transport path PP in FIG. 1 is referred to as a “paper transport direction”.

  The right end of the laser printer 100 in the drawing is referred to as the “front surface” of the laser printer 100, and the left end of the laser printer 100 in the drawing is referred to as the “rear face” of the laser printer 100. The horizontal direction in FIG. 1 is the length direction of the laser printer 100.

  Further, a direction perpendicular to the horizontal direction (the length direction of the laser printer 100) and the vertical direction (the height direction of the laser printer 100) in FIG. 1 (that is, the normal direction of the paper surface of FIG. 1: the width direction of the laser printer 100). Is referred to as “paper width direction”.

<Configuration of casing of main body>
The outer cover 111 is a substantially rectangular parallelepiped member that constitutes the casing of the main body 110, and is integrally formed of a synthetic resin plate. The outer cover 111 is provided so as to cover a main body frame 112 for supporting various members accommodated in the main body 110. A paper discharge tray 111 b is formed on the upper surface 111 a of the outer cover 111. The paper discharge tray 111b is composed of a slope formed so as to extend obliquely downward from the front side to the back side of the upper surface 111a. That is, the paper discharge tray 111b is composed of a recess formed in the upper surface 111a. A paper discharge port 111c having an opening is formed above the outer cover 111 and above the lower end of the paper discharge tray 111b. The paper discharge tray 111b is configured to receive the paper discharged from the paper discharge port 111c.

  An opening is formed on the front surface side of the outer cover 111, and a plate-like front cover 113 is mounted so as to close the opening. At the lower end of the front cover 113, a hole 113a that forms the rotation center of the front cover 113 is formed. A pair of front cover support pins 113 b are erected along the paper width direction at the opening of the outer cover 111. By inserting the front cover support pin 113b into the hole 113a of the front cover 113, the front cover 113 is supported so as to be openable and closable along the paper transport direction with the front cover support pin 113b as a center.

  The laser printer 100 according to the present embodiment is configured such that the process cartridge 130 can be attached and detached from the front side of the laser printer 100 by opening the front cover 113 to the front side (right side in the drawing).

<Configuration of feeder unit>
A feeder case 121 constituting the casing of the feeder unit 120 is configured to accommodate a large number of sheet-like sheets in a stacked state. In the feeder case 121, a paper pressing plate 123 and a separation pad 125 are arranged.

  The paper pressing plate 123 is supported so as to be swingable around an end portion on the back side (the far side from the separation pad 125 in FIG. 1). The end of the sheet pressing plate 123 on the front side (the side closer to the separation pad 125 in FIG. 1) is urged upward by a spring (not shown). The separation pad 125 is disposed in the vicinity of the front end portion of the feeder case 121 and on the downstream side of the paper pressing plate 123 in the paper transport direction, and is biased upward by a spring (not shown) from below. . The upper surface of the separation pad 125 is made of a material having a higher friction coefficient than paper, such as rubber.

<Configuration of process cartridge>
A developing cartridge 132 is detachably attached to a process case 131 constituting a casing and a frame of the process cartridge 130. The developing cartridge 132 is disposed on the side (back side) of the photosensitive drum 133 housed in the process case 131. The photosensitive drum 133 is a cylindrical member having a photosensitive layer formed on the outer periphery thereof. The photosensitive drum 133 is supported by the process case 131 so that it can be rotated clockwise in the drawing in synchronism with the conveyance of the paper during image formation. Further, the photosensitive drum 133 is arranged so that the rotation center axis thereof is parallel to the paper width direction. The developing cartridge 132 supplies toner to the peripheral surface 133a of the photosensitive drum 133 on which the electrostatic latent image is formed, thereby supporting the toner while arranging the toner on the peripheral surface 133a in an image form (the electrostatic latent image). An image is developed with toner).

<< Developer Cartridge Configuration >>
The developing cartridge case 132a constituting the casing of the developing cartridge 132 includes a developing cartridge case bottom plate 132a1, a developing cartridge case side plate 132a2, and a developing cartridge case upper plate 132a3. The developing cartridge case side plate 132a2 is provided so as to be joined to both ends of the developing cartridge case bottom plate 132a1 in the paper width direction. The developing cartridge case bottom plate 132a1 and the developing cartridge case side plate 132a2 are integrally formed by injection molding synthetic resin. A space surrounded by the developing cartridge case bottom plate 132a1 and the pair of developing cartridge case side plates 132a2 is opened at the upper end and the rear side of the developing cartridge case bottom plate 132a1 and the developing cartridge case side plate 132a2, and the opening at the upper end is The developing cartridge case upper plate 132a3 is closed. In addition, a developing roller 132b, a supply roller 132c, and a blade 132d are disposed in the opening on the back side facing the photosensitive drum 133.

  The developing roller 132b is supported by a pair of developing cartridge case side plates 132a2 so as to be able to rotate counterclockwise in the drawing. The developing roller 132b is configured by forming a semiconductive rubber layer in which carbon black is mixed with synthetic rubber on the outer periphery of a metal rotation center shaft. The length of the developing roller 132b in which the rubber layer is formed in the paper width direction is such that the photosensitive layer is well formed on the outer periphery of the photosensitive drum 133 and the electrostatic latent image is formed well. The dimension is set to be sufficiently longer than the effective latent image forming area (see the effective latent image forming area 133d4 in FIG. 6). Further, the developing roller 132b is supported by the pair of developing cartridge case side plates 132a2 so that the developing roller 132b is arranged in parallel with the photosensitive drum 133 with the developing cartridge 132 mounted on the process case 131. . Further, the peripheral surface of the developing roller 132b exposed to the outside of the developing cartridge case 132a faces the photosensitive drum 133, and the developing is performed through a thin layer of toner carried on the peripheral surface of the developing roller 132b. The developing roller 132b is supported so that the peripheral surface of the roller 132b and the peripheral surface 133a of the photosensitive drum 133 are in contact with each other.

  That is, in the present embodiment, the process case 131 (drum frame) that rotatably supports the cylindrical photosensitive drum 133 configured to form an electrostatic latent image is attached to and detached from the main body frame 112. It is installed as possible. Further, a developing roller 132b that is configured to be able to carry toner on the peripheral surface and is arranged in parallel to the photosensitive drum 133 so as to face the photosensitive drum 133 is formed by a developing cartridge case 132a (developing frame). It is rotatably supported. The developing cartridge case 132a is detachably attached to the process case 131.

  A supply roller 132c is rotatably supported by a pair of developing cartridge case side plates 132a2 on the front side of the developing roller 132b (that is, a position closer to the inside of the developing cartridge case 132a). The supply roller 132c is configured by forming a sponge layer on the outer peripheral portion of a metal rotation center shaft. The supply roller 132c is disposed so as to be in contact with the peripheral surface of the developing roller 132b, and is rotated counterclockwise in the drawing at the time of image formation, so that charged toner is transferred onto the peripheral surface of the developing roller 132b. It can be made to carry on.

  The blade 132d is fixed to the developing cartridge case upper plate 132a3 on the back side (outside) from the contact portion between the developing roller 132b and the supply roller 132c. The blade 132d is arranged such that the tip thereof is in contact with the peripheral surface of the developing roller 132b, so that the density and charge amount of toner on the peripheral surface of the developing roller 132b can be adjusted. An area (effective image forming area) on the peripheral surface of the developing roller 132b on which toner of a predetermined density and charge amount is carried by the contact of the blade 132d is the effective latent image forming area on the photosensitive drum 133 described above. The length of the blade 132d in the paper width direction is set so that the blade 132d is slightly wider (a few millimeters).

  An agitator 132e is rotatably supported in the space inside the developing cartridge case 132a and on the front side of the supply roller 132c. A projecting wall 132a1 ′ projecting upward from the developing cartridge case bottom plate 132a1 is disposed between the agitator 132e and the supply roller 132c. The electrostatic wall 132a1 ′ is disposed above the projecting wall 132a1 ′ in the space on the front side. A toner as a developer for developing the latent image is accommodated. By rotating the agitator 132e clockwise in the drawing, the toner is agitated in the space, and the toner can be sent toward the supply roller 132c beyond the protruding wall 132a1 ′. The agitator 132e is configured.

<< Configuration and arrangement of other members in process case >>
A charger 134 for uniformly charging the peripheral surface 133a of the photosensitive drum 133 is disposed above the photosensitive drum 133. The charger 134 is supported by a process case 131. In the upper part of the process case 131, a laser irradiation opening 131t that is a path of the laser beam for irradiating the peripheral surface 133a of the photosensitive drum 133 with the laser beam is formed. That is, the peripheral surface 133a of the photosensitive drum 133 is irradiated with a laser beam modulated according to image information through the laser irradiation opening 131t to the peripheral surface 133a of the uniformly charged photosensitive drum 133. The laser irradiation opening 131t is formed so that an electrostatic latent image can be formed thereon.

  In the process case 131, a transfer roller 135 for transferring the toner carried on the peripheral surface of the photosensitive drum 133 onto a sheet is accommodated. The transfer roller 135 is disposed below the photosensitive drum 133 and at the bottom of the process cartridge 130 such that the upper portion of the peripheral surface thereof faces the photosensitive drum 133. The transfer roller 135 is supported by the process case 131 so as to rotate counterclockwise in the drawing in synchronism with the clockwise rotation of the photosensitive drum 133 in the drawing at the time of image formation.

  The transfer roller 135 is covered with a process case bottom plate 131 a that forms the bottom of the process case 131. In the process case bottom plate 131a, on the upstream side of the transfer roller 135 in the sheet conveyance direction, the sheet is introduced into the process case 131 (transfer position which is a contact portion between the photosensitive drum 133 and the transfer roller 135). A paper inlet opening 131b, which is an opening, is formed. Further, on the downstream side of the process case bottom plate 131a in the paper transport direction from the transfer roller 135, a paper outlet opening 131c, which is an opening for discharging the paper from the process case 131, is formed.

  In the process case 131, a cleaning unit 136 for cleaning the peripheral surface of the photosensitive drum 133 is disposed. The cleaning unit 136 is in contact with the peripheral surface of the photosensitive drum 133 on the downstream side in the rotation direction of the photosensitive drum 133 with respect to a position facing the transfer roller 135 across the paper transport path PP with a predetermined pressure. Has been placed.

  On the outer side of the process case bottom plate 131a and upstream of the sheet inlet opening 131b in the sheet conveyance direction, an upper registration roller 137 for adjusting the direction and conveyance timing of the sheet is rotatably supported.

<< Positioning configuration of process case and developer cartridge in front / rear / up / down direction >>
2A is an enlarged side sectional view of the process case 131, and FIG. 2B is a side sectional view showing a state in which the developing cartridge 132 is mounted on the process case 131. As shown in FIG.

  As shown in FIG. 2A, a developing cartridge housing portion 131 d is formed in the space inside the process case 131 and on the side of the photosensitive drum 133. The developing cartridge housing portion 131d is configured by a space surrounded by a process case bottom plate 131a and a pair of process case side plates 131d1 erected at both ends of the process case bottom plate 131a in the sheet width direction. As shown in FIG. 2B, the peripheral surface 132b1 of the developing roller 132b and the peripheral surface 133a of the photosensitive drum 133 are made of toner carried on the peripheral surface 132b1 of the developing roller 132b. The developing cartridge housing portion 131d is configured so that the developing cartridge 132 can be housed while being in contact with each other through a thin layer.

  As shown in FIG. 2A, the process case side plate 131d1 is arranged so as to surround not only the developing cartridge housing portion 131d but also the photosensitive drum 133 and the sheet outlet opening 131c. It is a member which comprises a side plate.

  A positioning opening 131e is formed in the process case side plate 131d1. The positioning opening 131e is formed so as to extend toward the rotation shaft 133b of the photosensitive drum 133. As shown in FIG. 2B, when the developing cartridge 132 is attached to the process case 131, the positioning opening 131e is arranged so that the rotating shaft 132b2 of the developing roller 132b is accommodated in the positioning opening 131e. Is formed. In this case, the positioning opening 131e and the positioning shaft 131b2 are in contact with the positioning end surface 131e1, which is the end surface of the positioning drum 131 facing the rotation shaft 133b of the photosensitive drum 133. A positioning end surface 131e1 is formed. Further, in this state, the positioning opening 131e and the positioning end surface 131e1 are formed so that the photosensitive drum 133 and the developing roller 132b are positioned in the front-rear / up-down direction (left-right / up-down direction in the drawing). Yes.

<< Positioning configuration of developing cartridge case and developing roller in sheet width direction >>
Referring to FIG. 2B, a pin 132b3 is erected at the end of the rotation shaft 132b2 of the developing roller 132b. This pin 132b3 is one of the pair of developing cartridge case side plates 132a2 (the one facing the process case side plate 131d1 adjacent to the engaging portion 131f (see FIG. 3) formed on the process case bottom plate 131a described later). The developing cartridge case 132a and the developing roller 132b are arranged at a predetermined position at the end of the rotating shaft 132b2 of the developing roller 132b so that the developing cartridge case 132a and the developing roller 132b can be positioned in the paper width direction by contacting the side surface.

<< Positioning Configuration of Process Case and Developer Cartridge in the Paper Width Direction >>
FIG. 3 is a perspective view of the process case 131. FIG. 4 is a perspective view of the developing cartridge 132 as viewed from the bottom side. FIG. 5 is a perspective view showing a part of the configuration for positioning the process case 131 and the developing cartridge 132 in the paper width direction in a state where the developing cartridge 132 is mounted on the process case 131. FIG.

  As shown in FIG. 3, an engaging portion 131f is formed at the end of the process case bottom plate 131a in the paper width direction. The engaging portion 131f is composed of an engaging portion forming rib 131f1 and an engaging portion forming rib 131f2 that are erected upward from the process case bottom plate 131a so as to be substantially parallel to the process case side plate 131d1. A gap 131f3 having a predetermined width is formed between the engaging portion forming rib 131f1 and the engaging portion forming rib 131f2.

  As shown in FIG. 4, a positioning rib 132a4 is formed at the end of the developing cartridge case bottom plate 132a1 in the paper width direction. The positioning rib 132a4 is provided in the vicinity of the side cover 132a5 disposed outside the developing cartridge case side plate 132a2 in the paper width direction. The side cover 132a5 is provided with a coupling member 132a6 configured so that an input shaft (not shown) provided on the main body frame 112 (see FIG. 1) can be inserted. When the input shaft is inserted into the coupling member 132a6, a developing roller 132b (see FIG. 1) is provided from a motor (not shown) provided on the main body frame 112 (see FIG. 1) via the input shaft and the coupling member 132a6. 2) and the like is transmitted to the developing cartridge 132. The positioning rib 132a4 described above is formed in the vicinity of the coupling member 132a6.

  Referring to FIG. 5, the engagement portion 131f is configured such that the positioning rib 132a4 is fitted to the gap 131f3 between the engagement portion formation rib 131f1 and the engagement portion formation rib 131f2 with a predetermined fit tolerance. The interval in the sheet width direction between the forming rib 131f1 and the engaging portion forming rib 131f2 and the thickness in the sheet width direction of the positioning rib 132a4 are set. Then, with the developing cartridge 132 mounted in the process case 131, the positioning rib 132a4 is engaged with the engaging portion 131f, so that the process case 131 and the developing cartridge case 132a are positioned in the paper width direction. It has become.

  That is, the positioning rib 132a4 formed in the developing cartridge case 132a constitutes the rib of the present invention for positioning the process case 131 (drum frame) and the developing cartridge case 132a (developing frame) in the paper width direction. ing. Further, the engaging portion 131f formed in the process case 131 engages with the positioning rib 132a4 for positioning the process case 131 (drum frame) and the developing cartridge case 132a (developing frame) in the paper width direction. The engaging portion of the present invention is configured.

  As shown in FIG. 5, the engaging portion 131f and the positioning rib 132a4 are disposed almost directly below the developing roller 132b (that is, near the rotation center axis of the developing roller 132b).

<< Positioning configuration between process case and photosensitive drum >>
6 is a cross-sectional plan view showing a state in which the process case 131 shown in FIG. 2 is attached to the main body frame 122 shown in FIG. In FIG. 6, it is assumed that the developing cartridge 132 (see FIG. 1) mounted in the developing cartridge housing portion 131d is omitted.

  As shown in FIG. 6, a drum gear 133 c is provided at one end of the photosensitive drum 133 housed in the process case 131. An extension tube portion 133c1 is formed on one side surface of the drum gear 133c. The extension tube portion 133c1 is inserted into the end portion of the drum main body 133d made of a metal cylinder having a photoreceptor layer formed on the outer surface with a predetermined fitting tolerance, so that the drum gear 133c is inserted into the drum main body 133d. At one end, it is fixed so that it cannot rotate relative to the drum body 133d. The drum gear 133c is attached to the drum main body 133d so that the one side surface of the drum gear 133c is in contact with the drum end surface 133d1, which is one end surface of the drum main body 133d. The drum gear 133c is gear-coupled to a main body drive gear (not shown) provided on the main body frame 122, and a rotational driving force is transmitted to the photosensitive drum 133 via the drum gear 133c.

  The drum gear end surface 133c2, which is the other side surface of the drum gear 133c, is formed to have a predetermined good flatness. At one of the pair of process case side plates 131d1, a protruding portion 131d2 is formed at a position facing the drum gear end surface 133c2. The protruding portion end surface 131d3 that is the end surface of the protruding portion 131d2 that faces the drum gear 133c is also formed to have a predetermined good flatness. A flange portion 133e is attached to the other end portion of the drum main body 133d so as to be in contact with the drum end surface 133d2 which is the other end surface of the drum main body 133d.

  A spacer 133g is disposed outside the flange portion 133e in the paper width direction (left and right direction in the figure) so as to be sandwiched between two felt members 133f. The felt member 133f is sandwiched between the other process case side plate 131d1, the flange 133e, and the spacer 133g while being elastically compressed and deformed along the paper width direction. The drum body 133d and the drum gear 133c are urged to the left in the drawing by a spring (not shown), so that the protruding portion end surface 131d3 that is the end surface facing the drum gear 133c in the protruding portion 131d2 and the above-described drum gear end surface 133c2 The photosensitive drum 133 is disposed in the process case 131 so as to be in contact with each other. Then, the contact between the protrusion end surface 131d3 and the drum gear end surface 133c2 described above positions the photosensitive drum 133 in the paper width direction with respect to the process case 131. That is, the effective latent image forming area 133d4, which is an area inside the effective area boundary 133d3 at both ends of the photoconductor drum 133 and in which the photoconductor layer is satisfactorily formed, is formed by the protrusion 131d2. The protrusion 131d2 is formed so as to have a predetermined positional relationship with the inner surface of the formed one process case side plate 131d1. The “predetermined positional relationship” means that when the developing cartridge 132 (see FIG. 4) is housed in the developing cartridge housing portion 131d of the process case 131, the peripheral surface 132b1 (see FIG. 2B) of the developing roller 132b. The positional relationship in which the effective area boundary 133d3 is positioned inside the both ends of the effective image forming area in FIG.

<< Configuration of positioning mechanism between main body frame and process case >>
As shown in FIG. 6, a first side frame 114 and a second side frame 115 are fixed to the inner side surfaces of the pair of main body frames 112.

  An upper portion of the first side frame 114 disposed to face the one process case side plate 131d1 side where the protruding portion 131d2 is formed, and on the inner side in the paper width direction, the front side (lower side in the figure) A rectangular guide groove 114a is formed along the paper transport direction (vertical direction in the figure). An introduction surface 114a1, which is a vertical surface parallel to the sheet conveyance direction, is formed on the front side of the side surfaces of the guide groove 114a. An inclined surface 114a2 is formed at the end of the introduction surface 114a1 on the back side (upper side in the drawing) so as to protrude inward in the paper width direction. A concave portion 114b that accommodates the rotating shaft 133b of the photosensitive drum 133 is formed at the end of the inclined surface 114a2 on the back side.

  An end on the back side of the guide groove 114a is constituted by a rear end 114b1 which is an end on the back side of the recess 114b. Then, the outer peripheral surface of the rotating shaft 133b of the photosensitive drum 133 is brought into contact with the rear end 114b1, thereby positioning the process case 131 and the photosensitive drum 133 in the paper transport direction with respect to the main body frame 112. It has come to be.

  Further, the side end surface 114b2 that is the outer end surface of the recess 114b in the paper width direction is formed with a predetermined good flatness. Then, the rotation end 133b1 which is one end of the rotation shaft 133b of the photosensitive drum 133 is brought into contact with the side end surface 114b2, so that the process case 131 and the photosensitive drum 133 are in the sheet width direction with respect to the main body frame 112. Positioning about is performed. That is, from the first side frame 114 provided with the recess 114b and the one process case side plate 131d1 provided with the protrusion 131d2, the main body frame 112 and the process in the paper width direction parallel to the rotation center axis of the photosensitive drum 133 are processed. The positioning mechanism of the present invention for positioning with the case 131 (drum frame) is configured.

  Further, in the paper width direction, the engaging portion 131f and the positioning rib 132a4 (see FIG. 6) are positioned between the effective area boundary 133d3 on the side close to the one process case side plate 131d1 (left side in FIG. 6) and the drum gear 133c. 3 to 5) are arranged. That is, the engaging portion 131f and the positioning rib 132a4 (see FIGS. 3 to 5) are outside the effective latent image forming area 133d4 on the photosensitive drum 133 (and are in contact with the entire width of the effective latent image forming area 133d4). The developing roller 132b is disposed outside the effective image forming area on the peripheral surface 132b1 (see FIG. 2B). The engaging portion 131f and the positioning rib 132a4 (see FIGS. 3 to 5) are arranged in the vicinity of the first side frame 114 and the one process case side plate 131d1 constituting the positioning mechanism of the present invention. Has been.

  A rectangular guide groove 115a when viewed from the front side is formed on the upper side of the second side frame 115 disposed opposite to the other process case side plate 131d1 side and inward in the paper width direction. It is formed along the transport direction. The inner surface of the guide groove 115a is constituted by a vertical surface parallel to the sheet conveying direction up to the rear end surface 115b that is the end surface on the back side of the guide groove 115a (that is, the guide groove 115a includes The portion corresponding to the slope 114a2, the concave portion 114b or the like in the guide groove 114a is not formed). A leaf spring 116 is arranged at the end of the guide groove 115a on the back side. The leaf spring 116 urges the rotating shaft 133b of the photosensitive drum 133 inward in the paper width direction (left side in the figure) so that the rotating shaft end 133b1 can be brought into contact with the side end surface 114b2. It is configured. Further, the drum main body 133d is electrically connected to the grounded second side frame 115 and the main body frame 112 through the leaf spring 116 and the rotating shaft 133b.

  A flat guide groove bottom plate 114c is erected on the first side frame 114 below the guide groove 114a so as to extend inward in the paper width direction. Further, a flat guide groove bottom plate 115c is erected on the second side frame 115 below the guide groove 115a so as to extend inward in the paper width direction. That is, the guide groove bottom plates 114c and 115c are arranged to face each other at the same height. By moving the process case 131 from the front side toward the back side while placing the outer peripheral surface of the rotating shaft 133b of the photosensitive drum 133 on the upper surfaces of the guide groove bottom plates 114c and 115c, The guide groove bottom plates 114 c and 115 c are configured so that the process case 131 can be attached to the frame 112. The rotating shaft 133b of the photosensitive drum 133 is in contact with the rear end 114b1 of the guide groove 114a of the first side frame 114 and the rear end surface 115b of the guide groove 115a of the second side frame 115. By positioning 133b on the guide groove bottom plates 114c and 115c, the process case 131 and the photosensitive drum 133 are positioned with respect to the main body frame 112 in the height direction.

<Configuration of scanner unit>
Referring to FIG. 1 again, the scanner unit 140 is disposed above the process case 131. The scanner unit 140 includes a scanner case 141, a polygon mirror 142, and reflecting mirrors 143, 144, and 145.

  The polygon mirror 142 is supported by a rotation drive shaft of a motor (not shown) fixed to the scanner case 141 so that the polygon mirror 142 can be driven to rotate at a predetermined rotation speed. The polygon mirror 142 can scan the laser beam along the paper width direction by reflecting the laser beam generated based on the image data by a laser light emitting unit (not shown) while being rotated by the motor. It is configured as follows. The reflecting mirrors 143, 144, and 145 allow the laser beam reflected by the polygon mirror 142 (indicated by the alternate long and short dash line in the figure) to pass through the laser irradiation opening 131t formed in the process case 131 and to the photosensitive drum 133. It is supported in the scanner case 141 so that it can irradiate the peripheral surface.

<Configuration of paper feed unit>
The paper feed unit 150 includes a paper feed roller 151, a paper dust removing roller 152, a paper feed roller outer side paper guide 153, a process upstream side paper guide 154, a lower registration roller 155, and a process downstream side paper guide 156. It is composed of

  The paper feed roller 151 is rotatably supported by the main body frame 112 of the main body 110. The paper feed roller 151 is disposed to face the separation pad 125 so that the peripheral surface thereof is in contact with the separation pad 125 with a predetermined pressure.

  The paper dust removing roller 152 is rotatably supported by the main body frame 112 on the front side of the separation pad 125 (on the downstream side in the rotation direction of the paper feeding roller 151 during paper feeding). The paper dust removing roller 152 is arranged so that its peripheral surface is in contact with the paper feeding roller 151.

  The paper feed roller outer paper guide 153 is disposed so as to surround the paper feed roller 151. The sheet guide 153 outside the sheet feed roller conveys one sheet picked up by the sheet feed roller 151 along the sheet conveyance path PP while being folded from the front side toward the back side by the sheet feed roller 151. It is a member for guiding the paper so that it can be obtained.

  The process upstream sheet guide 154 lowers the sheet between the downstream end of the sheet feed roller outer sheet guide 153 in the sheet conveyance direction and the above-described upper registration roller 137 disposed on the process cartridge 130 side. It is arranged so that it can be supported from the side. The process upstream side paper guide 154 is a member for guiding the paper so that the paper having passed through the paper supply roller 151 can be conveyed toward the process cartridge 130 along the paper conveyance path PP.

  The lower registration roller 155 is a roller for adjusting the sheet orientation and conveyance timing by cooperating with the above-described upper registration roller 137, and the photosensitive drum 133 is in contact with the upper registration roller 137. And the transfer roller 135 are disposed on the upstream side in the paper transport direction from the position where the roller and the transfer roller 135 face each other.

  The process downstream side paper guide 156 is disposed between the paper exit opening 131c and the fixing unit 160 so as to support the paper from below.

<Configuration of fixing unit>
The fixing unit 160 is disposed on the downstream side in the paper transport direction from the position where the photosensitive drum 133 and the transfer roller 135 face each other. The fixing unit 160 includes a fixing unit cover 161, a heat roller 162, and a pressure roller 163.

  The fixing unit cover 161 is a member interposed between the process cartridge 130 and the heat roller 162 and the pressure roller 163 so that the process cartridge 130 is not heated as much as possible. The heat roller 162 contains a halogen lamp in a metal cylinder whose surface has been released from the mold, and the fixing unit cover 161 can be rotated in the direction of the arrow (clockwise) by a motor (not shown). It is supported so that it can rotate inside. The pressure roller 163 is a roller made of silicon rubber, and can be rotated in the arrow direction (counterclockwise) in the drawing by being driven by the heat roller 162 while being pressed with a predetermined pressure against the heat roller 162. The fixing unit cover 161 is rotatably supported.

<Configuration of paper discharge unit>
The paper discharge unit 170 includes a paper conveyance roller 171, a paper discharge roller 172, and a paper guide 173. The paper transport roller 171 is a pair of rollers that are rotationally driven by a motor (not shown), and is disposed in the vicinity of the exit of the fixing unit 160. The paper discharge roller 172 is a pair of rollers that are rotationally driven by a motor (not shown), and is disposed in the vicinity of the paper discharge port 111c. The paper guide 173 is a member for guiding paper from the paper transport roller 171 to the paper discharge roller 172 along the paper transport path PP.

<Outline of image forming operation by laser printer>
Hereinafter, an outline of an image forming operation by the laser printer 100 having the above-described configuration will be described with reference to FIG.

<< Paper feeding action >>
The paper stacked on the paper pressing plate 123 is urged upward by the paper pressing plate 123 toward the paper feed roller 151, and the uppermost paper contacts the peripheral surface of the paper feed roller 151. When the paper feed roller 151 is driven to rotate counterclockwise in the figure, the leading edge of the paper moves to the upper right in the figure and is sandwiched between the paper feed roller 151 and the separation pad 125. Then, only the uppermost sheet is conveyed toward the paper dust removing roller 152 as the sheet feeding roller 151 rotates.

  The paper conveyed toward the paper dust removing roller 152 is guided by the paper roller outer paper guide 153 and the process upstream side paper guide 154 after the paper dust on the paper is removed by the paper dust removing roller 152. At the same time, it is conveyed to a contact portion (registration portion) between the upper registration roller 137 and the lower registration roller 155. After the leading edge of the sheet is abutted against the registration portion, the lower registration roller 155 is rotationally driven at a predetermined timing, and the upper registration roller 137 rotates so as to rotate with the rotation of the lower registration roller 155. The sheet is conveyed toward the transfer position where the photosensitive drum 133 and the transfer roller 135 face each other. As a result, the skew feeding correction and the conveyance timing adjustment of the sheet are performed.

<< Carrying of toner image on peripheral surface of photosensitive drum >>
Referring again to FIG. 1, while the sheet is being conveyed toward the transfer position as described above, an image made of toner is carried on the peripheral surface 133a of the photosensitive drum 133 as follows.

  First, the peripheral surface 133 a of the photosensitive drum 133 is uniformly charged by the charger 134. The peripheral surface 133a of the photosensitive drum 133 charged by the charger 134 rotates clockwise in the drawing and reaches below the laser irradiation opening 131t. Below the laser irradiation opening 131t, the laser beam scanned along the paper width direction by the scanner unit 140 is irradiated onto the circumferential surface 133a of the photosensitive drum 133 uniformly charged as described above. As described above, this laser beam is generated based on the image data. That is, the light emission state (ON / OFF pulse shape) of the laser beam is modulated according to the image data. The laser beam thus modulated is scanned on the peripheral surface 133a of the photosensitive drum 133, whereby an electrostatic latent image is formed on the peripheral surface 133a. The peripheral surface 133a of the photosensitive drum 133 on which the electrostatic latent image is formed rotates clockwise in the drawing, and contacts or approaches the peripheral surface of the developing roller 132b. On the peripheral surface of the developing roller 132b, charged toner is carried almost uniformly as follows.

  As the supply roller 132c rotates counterclockwise in the figure, the toner adheres to the peripheral surface of the developing roller 132b. Thus, the peripheral surface of the developing roller 132b to which the toner is adhered by the supply roller 132c rotates counterclockwise in the drawing and reaches the contact position with the blade 132d. The blade 132d adjusts the toner adhesion amount and charge amount on the peripheral surface. The peripheral surface in which the toner adhesion amount and the charge amount are adjusted in this way reaches a position facing the photosensitive drum 133 by rotating counterclockwise in the drawing.

  The peripheral surface 133a of the photosensitive drum 133 is brought into contact with or close to the peripheral surface 133a of the photosensitive drum 133 on which the electrostatic latent image is formed and the peripheral surface of the developing roller 132b carrying the charged toner. The toner adheres on the peripheral surface 133a in a pattern corresponding to the electrostatic latent image formed thereon. That is, the electrostatic latent image on the peripheral surface 133a of the photosensitive drum 133 is developed with toner, and the toner image is carried on the peripheral surface 133a.

<< Transfer of Toner Image from Photosensitive Drum Surface to Paper >>
The toner image carried on the peripheral surface 133a of the photosensitive drum 133 as described above is conveyed toward the transfer position as the peripheral surface 133a rotates clockwise in the drawing. At this transfer position, the toner image is transferred from the peripheral surface 133a of the photosensitive drum 133 onto the paper.

  The peripheral surface 133a of the photosensitive drum 133 that has passed the above-described transfer position reaches the cleaning unit 136 by rotating clockwise in the drawing. The cleaning unit 136 removes foreign matters such as toner remaining on the peripheral surface 133a and dust attached to the peripheral surface 133a. The peripheral surface 133a thus cleaned is repeatedly used for image formation such as being uniformly charged again by the charger 134.

<< Fixing / Ejecting >>
The sheet on which the toner image is transferred is sent to the fixing unit 160 along the sheet conveyance path PP, and is heated while being pressed by being sandwiched between the heat roller 162 and the pressure roller 163. As a result, the toner image is fixed on the surface of the paper. Thereafter, the sheet is sent to the sheet discharge port 111c through the sheet discharge unit 170, and is discharged onto the sheet discharge tray 111b through the sheet discharge port 111c.

<Operation / Effects of Configuration of Embodiment>
Next, operations and effects of the configuration of the above-described embodiment will be described below with reference to the drawings.

  According to the configuration of the present embodiment, as shown in FIG. 5, the positioning rib 132a4 is engaged with the engaging portion 131f, thereby positioning the process case 131 and the developing cartridge case 132a in the paper width direction. Simple and reliable.

  In the present embodiment, as shown in FIGS. 3 and 4, the engaging portion 131f and the positioning rib 132a4 are formed at the ends of the process case 131 and the developing cartridge case 132a in the paper width direction. According to such a configuration, the dimensions from a predetermined reference surface (for example, the inner wall surface of the process case side plate 131d1 and the developing cartridge case side plate 132a2 adjacent to the engaging portion 131f and the positioning rib 132a4) to the engaging portion 131f and the positioning rib 132a4. Is small, the tolerance of the dimension can be set small. Therefore, accurate positioning between the process case 131 and the developing cartridge case 132a can be performed.

  In the present embodiment, as shown in FIG. 5, the engaging portion 131f is composed of a pair of engaging portion forming ribs 131f1 and 131f2 that face each other across a narrow gap 131f3. According to this configuration, the developing cartridge 132 is placed in the process case so that the fitting tolerance between the gap 131f3 and the positioning rib 132a4 is reduced and the process case 131 and the developing cartridge case 132a do not move relative to each other in the paper width direction. 131 can be securely attached. Accordingly, the outer dimensions of the process case 131 and the developing cartridge case 132a in the paper width direction are set so that the clearance in the paper width direction between the process case side plate 131d1 (see FIG. 3) and the developing cartridge case side plate 132a2 becomes relatively large. As a result, the developing cartridge 132 can be securely attached to the process case 131 with accurate positioning while allowing the developing cartridge 132 to be smoothly attached to and detached from the process case 131.

  In the present embodiment, the engaging portion 131f and the positioning rib 132a4 (see FIG. 5) are located near the first side frame 114 and the one process case side plate 131d1 (see FIG. 6) constituting the positioning mechanism of the present invention. ) To position the process case 131 and the developing cartridge case 132a. The positioning rib 132a4 is engaged with (engaged with) the engaging portion 131f in the vicinity of the coupling member 132a6 (see FIG. 4) and the drum gear 133c (see FIG. 6) to which the rotational driving force is transmitted. This is done. Further, the positioning rib 132a4 (see FIG. 5) is disposed in the vicinity of the rotation center axis of the developing roller 132b.

  Thus, the roll that may occur in the developing cartridge case 132a when the rotational driving force is transmitted is suppressed, and the developing cartridge 132 can be stably attached to the process case 131. Further, wear and damage of the engaging portion 131f and the positioning rib 132a4 can be suppressed. Further, accurate positioning of the main body frame 112, the process case 131, and the developing cartridge case 132a can be performed.

  In the present embodiment, the effective latent image forming area 133d4 (see FIG. 6) on the photoconductive drum 133 and the effective image forming area on the peripheral surface 132b1 (see FIG. 2B) of the developing roller 132b are the paper width. The photosensitive drum 133 and the developing roller 132b are positioned in the paper width direction so as to substantially match the direction. As a result, the toner carried on the peripheral surface 132b1 of the developing roller 132b with a predetermined density and charge amount over the entire width in the paper width direction of the electrostatic latent image formed on the peripheral surface of the photosensitive drum 133 is ensured. To be supplied. Therefore, the electrostatic latent image can be favorably developed with toner.

  In the present embodiment, the engaging portion 131f (see FIG. 3) and the positioning rib 132a4 (see FIG. 4) are formed outside the above-described effective latent image forming region 133d4 (see FIG. 6) and the effective image forming region. Yes. Thereby, the engaging portion 131f and the positioning rib 132a4 can be reliably arranged at the end portions in the paper width direction of the process case 131 and the developing cartridge case 132a. Therefore, the above-described positioning in the sheet width direction can be performed reliably while configuring the sheet conveyance path so that the sheet can be smoothly conveyed inside the effective latent image forming area and the effective image forming area.

<Suggestion of modification>
Note that, as described above, the above-described embodiment is merely an example of the embodiment of the present invention that the applicant considered to be the best at the time of filing of the present application, and the present invention is not limited to the above-described embodiment. The present invention is not limited to the embodiments, and various modifications can be made without departing from the essential part of the present invention. Hereinafter, some modifications will be exemplified. Needless to say, the modifications are not limited to the following.

(I) The image forming apparatus to which the present invention is applied is not limited to a laser printer. Further, the process case 131 may be configured to accommodate and support only the photosensitive drum 133. Further, the developing cartridge 132 may be configured to be attachable to and detachable from the main body frame 112 so that the process case 131 that accommodates and supports the photosensitive drum 133 forms a part of the main body frame 112.

(Ii) Referring to FIG. 3, in the above-described embodiment, the engaging portion 131 f is composed of a plurality of engaging portion forming ribs 131 f 1 and 131 f 2. However, the present invention is not limited to this configuration. For example, the engaging portion 131f may be constituted by a recess or a through hole formed in the process case bottom plate 131a.

(Iii) Referring to FIG. 5, an engaging portion that engages with an engaging portion forming rib 131f1 or 131f2 formed on the process case 131 side may be formed on the developing cartridge case 132a side. The engaging portion in this case can also be constituted by a recess, a through hole, a plurality of ribs, and the like.

(Iv) The position of the engaging portion and the rib that engages with the engaging portion is not limited to the end portion in the paper width direction as in the above-described embodiment.

(V) In the above-described embodiment, the process case 131 and the developing cartridge case 132a are positioned in the paper width direction by the engaging portion and the rib that engages with the engaging portion. Positioning with the developing roller 132b in the paper width direction has been performed. However, the present invention can also be applied to the case where the process case 131 and the developing cartridge case 132a are simply positioned in the paper width direction.

(Vi) In addition, in the elements constituting the means for solving the problems of the present invention, the elements expressed functionally and functionally are the specific structures disclosed in the above-described embodiments and modifications. In addition, any structure capable of realizing the action / function is included.

1 is a side sectional view showing a schematic configuration of a laser printer according to an embodiment of the present invention. 2A is an enlarged side cross-sectional view of the process case shown in FIG. 1, and FIG. 2B is a side cross-sectional view showing a state where the developing cartridge is attached to the process case. It is a perspective view which shows the external appearance of the process case shown in FIG. FIG. 3 is a perspective view of the developing cartridge shown in FIG. 2 as viewed from the bottom side. FIG. 5 is a perspective view showing the periphery of the configuration for positioning the process case and the developing cartridge in the paper width direction shown in FIGS. 3 and 4 with a part of the developing cartridge attached to the process case. . FIG. 3 is a plan sectional view showing a state in which the process case shown in FIG. 2 is attached to the main body frame shown in FIG. 1.

Explanation of symbols

100 ... Laser printer 110 ... Main body part 112 ... Main body frame,
114: first side frame, 114a: guide groove, 114b: recess,
114b1 ... rear end, 114b2 ... side end surface, 115 ... second side frame,
115a ... guide groove, 115b ... rear end surface, 116 ... leaf spring,
130 ... Process cartridge, 131 ... Process case,
131a ... process case bottom plate, 131d ... developing cartridge housing,
131d1 ... process case side plate, 131d2 ... projection, 131d3 ... projection end surface,
131e ... positioning opening, 131e1 ... positioning end face, 131f ... engagement part,
131f1 ... engaging portion forming ribs, 131f2 ... engaging portion forming ribs, 131f3 ... gaps,
132: developing cartridge, 132a: developing cartridge case,
132a1 ... developing cartridge bottom plate, 132a2 ... developing cartridge side plate,
132a4 ... positioning ribs, 132b ... developing roller, 132b1 ... peripheral surface,
132b2 ... rotating shaft, 132b3 ... pin, 132d ... blade,
133 ... photosensitive drum, 133a ... circumferential surface, 133b ... rotary shaft,
133b1 ... rotation shaft end, 133d ... drum body, 133d3 ... effective area boundary,
133d4 ... Effective latent image forming region, 133e ... Flange, 133f ... Felt member,
133g ... Spacer

Claims (8)

In a process cartridge that is detachable from an image forming apparatus,
A drum frame that rotatably supports a cylindrical photosensitive drum configured to form an electrostatic latent image;
A developing roller, which is configured to be able to carry a developer for developing the electrostatic latent image on its peripheral surface and is disposed in parallel to the photosensitive drum so as to face the photosensitive drum, is rotatable. And a developing frame that is detachably attached to the drum frame,
With
One of the drum frame and the developing frame includes a rib for positioning the drum frame and the developing frame in a direction parallel to the rotation center axis of the photosensitive drum,
The other of the drum frame and the developing frame, which is different from the one, includes an engaging portion that engages with the rib for positioning the drum frame and the developing frame in the direction. To
Process cartridge. The process cartridge according to claim 1,
2. The process cartridge according to claim 1, wherein the developing frame is configured to receive the developing roller and the developer and is detachably received from the drum frame. The process cartridge according to claim 1,
A process case configured to accommodate the photosensitive drum and constituting a casing of the process cartridge;
A developing cartridge configured to contain the developing roller and the developer and detachably attached to the process case;
Further comprising
The developing cartridge includes a developing cartridge case constituting a casing of the developing cartridge,
The process case is composed of the drum frame,
The process cartridge is characterized in that the developing cartridge case comprises the developing frame. The process cartridge according to any one of claims 1 to 3,
The process cartridge according to claim 1, wherein the rib or the engaging portion formed on the developing frame is disposed in the vicinity of a rotation center axis of the developing roller. A process cartridge according to any one of claims 1 to 4,
The rib or the engaging portion formed on the developing frame is formed outside the region that can face the electrostatic latent image formed on the photosensitive drum in the longitudinal direction of the developing roller. A process cartridge characterized by that. The process cartridge according to claim 5,
A driving force transmitting portion for transmitting a rotational driving force to the developing roller;
The process cartridge according to claim 1, wherein the rib or the engaging portion formed on the developing frame is disposed in the vicinity of the driving force transmitting portion. In an image forming apparatus configured to form an image by developing an electrostatic latent image with a developer,
A drum frame that rotatably supports a cylindrical photosensitive drum configured to form an electrostatic latent image;
A developing roller, which is configured to be able to carry a developer for developing the electrostatic latent image on its peripheral surface and is disposed in parallel to the photosensitive drum so as to face the photosensitive drum, is rotatable. And a developing frame that is detachably attached to the drum frame,
A body frame on which the drum frame is detachably mounted;
With
The main body frame and the drum frame include a positioning mechanism for positioning the main body frame and the drum frame in a direction parallel to a rotation center axis of the photosensitive drum,
One of the drum frame and the development frame includes a rib for positioning the drum frame and the development frame in the direction,
The other of the drum frame and the developing frame, which is different from the one, includes an engaging portion that engages with the rib for positioning the drum frame and the developing frame in the direction. To
Image forming apparatus. The image forming apparatus according to claim 7,
The image forming apparatus, wherein the rib or the engaging portion formed on the drum frame is disposed in the vicinity of the positioning mechanism.

Images