Toner Accommodating Container With a Gripping Cover Feature Usable With a Process Cartridge, a Process Cartridge Using the Same, and an Apparatus Using the Process Cartridge

The present invention relates to a process cartridge, a method for assembling a process cartridge, and an image forming apparatus.

The image forming apparatus in this specification includes an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer or a laser beam printer), an electrophotographic facsimile, an electrophotographic word processor, and the like.

The process cartridge in this specification is a cartridge which is removably installable in the main assembly of an image forming apparatus, and in which a charging means, a developing means or a cleaning means, and an electrophotographic photosensitive member are integrally housed. It may integrally comprise an electrophotographic photosensitive member, and at least the charging means, the developing means, or the cleaning means, or may integrally comprise an electrophotographic photosensitive member, and at least the developing means. The charging means, the developing means, and the cleaning means are processing means which act on the electrophotographic photosensitive member.

A process cartridge system in which the aforementioned process cartridge is removably installed in the main assembly of an image forming apparatus, has been employed in an image forming apparatus based on the electrophotographic image formation process. According to this process cartridge system, users themselves can maintain the image forming apparatus; there is no need for service personnel. Therefore, this process cartridge system can remarkably improve the operational efficiency of the image forming apparatus. Consequently, the process cartridge system has been widely employed in the field of the image forming apparatus.

The present invention is a result of the further development of the aforementioned process cartridge.

Accordingly, a primary object of the present invention is to provide a process cartridge which can be assembled with improved efficiency, a method for assembling the process cartridge with improved efficiency, and an image forming apparatus compatible with such a process cartridge.

Another object of the present invention is to provide a process cartridge in which an electrophotographic photosensitive member and a developing means can be reliably disposed, a method for assembling such a process cartridge, and an image forming apparatus compatible with such a process cartridge.

Another object of the present invention is to provide a process cartridge capable of reliably keeping the electrophotographic photosensitive member and the developing means in contact with each other with a predetermined contact pressure, a method for assembling such a process cartridge, and an image forming apparatus compatible with such a process cartridge.

According to an aspect of the present invention, there is provided a toner accommodating container usable with a process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein the process cartridge contains an electrophotographic photosensitive member and process means actable on the electrophotographic photosensitive member, the container comprising: a toner accommodating portion for accommodating toner to be used for developing a latent image formed on the electrophotographic photosensitive member; a cover member provided to cover an opening of the toner accommodating portion; a grip portion provided on the cover member; a partition wall extending in the toner accommodating portion along a short side thereof with a gap between the partition wall and the cover member, and wherein the partition wall and the cover member are contactable to each other when the toner accommodating container is handled with the grip, and the cover member is deformed.

According to another aspect of the present invention, there is provided a process cartridge detachably mountable to a main assembly of an image forming apparatus, comprising: a. an electrophotographic photosensitive member; b. process means actable on the electrophotographic photosensitive member; c. a toner accommodating container, which comprises: a toner accommodating portion for accommodating toner to be used for developing a latent image formed on the electrophotographic photosensitive member; a cover member provided to cover an opening of the toner accommodating portion; a grip portion provided on the cap member; a partition wall extending in the toner accommodating portion along a short side thereof with a gap between the partition wall and the cover member, and wherein the partition wall and the cover member are contactable to each other when the toner accommodating container is handled with the grip, and the cover member is deformed.

According to a further aspect of the present invention, there is provided an electrophotographic image forming apparatus for forming an image on a recording material, wherein a process cartridge is detachably mountable to the image forming apparatus, comprising: a. an mounting means for detachably mounting a process cartridge; the process cartridge including: a. an electrophotographic photosensitive member; b.3 process means actable on the electrophotographic photosensitive member; c. a toner accommodating container, which comprises: a toner accommodating portion for accommodating toner to be used for developing a latent image formed on the electrophotographic photosensitive member; a cover member provided to cover an opening of the toner accommodating portion; a grip portion provided on the cap member; a partition wall extending in the toner accommodating portion along a short side thereof with a gap between the partition wall and the cover member, and wherein the partition wall and the cover member are contactable to each other when the toner accommodating container is handled with the grip, and the cover member is deformed; the apparatus further comprising: feeding means for feeding the recording material.

These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings.

FIG. 1 is a perspective view depicting how a development frame and a cleaning frame are joined.

FIG. 2 is a sectional view depicting the internal structure of the joint between the development frame and the cleaning frame.

FIG. 3 is a partially cutaway plan view of the joint between the development frame and the cleaning frame.

FIG. 4 is a schematic section of an electrophotographic image forming apparatus, depicting the general structure thereof.

FIG. 5 is a cross-section of a process cartridge.

FIG. 6 is an external perspective view of the process cartridge.

FIG. 7 is an explanatory drawing depicting the structure of the right-hand guide for guiding the process cartridge during the insertion or removal thereof.

FIG. 8 is an explanatory drawing depicting the structure of the left-hand guide for guiding the process cartridge during the insertion or removal thereof.

FIG. 9 is a perspective view depicting how the process cartridge is installed into the image forming apparatus.

FIG. 10 is a sectional explanatory drawing depicting the state of the process cartridge having been partially inserted into the image forming apparatus.

FIG. 11 is a sectional drawing depicting the state of the process cartridge having been further inserted into the image forming apparatus.

FIG. 12 is a sectional view depicting the state of the process cartridge having been further inserted into the image forming apparatus.

FIG. 13 is a sectional view depicting the state of the process cartridge having been further inserted into the image forming apparatus.

FIG. 14 is a sectional view depicting the state of the process cartridge having been completely installed into the image forming apparatus.

FIG. 15 is a sectional drawing depicting the image forming apparatus, the lid of which is open, and in which the process cartridge has been completely installed.

FIG. 16 is an exploded perspective view of the cartridge frame.

FIG. 17 is a perspective view depicting how the toner seal is attached to the development frame.

FIG. 18 is an external perspective view of the process cartridge.

FIG. 19 is a perspective view of the process cartridge, depicting how a linking member is attached thereto.

FIG. 20 is a perspective drawing depicting how the process cartridge is held by a hand.

FIG. 21 is a perspective view of a toner accommodating container.

FIG. 22 is a perspective view thereof when the toner is filled.

FIG. 23 is a side sectional view of a process cartridge.

FIG. 24 is a perspective view of a process cartridge of FIG. 23.

FIG. 25 is a perspective view of an inside of a toner accommodating container.

FIG. 26 is a side sectional view of a process cartridge.

Hereinafter, the preferable embodiments of the present invention will be described in detail with reference to the drawings.

First, referring to FIGS. 1-14, a process cartridge in accordance with the present invention, and an electrophotographic image forming apparatus usable with such a process cartridge will be described in detail. As for the order in which descriptions are given, the general structures of the process cartridge and the image forming apparatus employing the process cartridge will be described at first, and then, cartridge installing means, the structure for opening or closing a drum shutter, the opening or closing movement of the drum shutter, and the structure of cartridge frames will follow. Thereafter, a method for joining the aforementioned two cartridge frames will be described.

Referring to FIG. 4, in the electrophotographic image forming apparatus A (laser beam printer) in accordance with the present invention, a light beam which carries image data is projected from an optical system 1 onto an electrophotographic photosensitive member 7 in the form of a drum to form a latent image thereon, and this latent image is developed into a toner image. The electrophotographic photosensitive member is charged by a charge roller 8 before it is irradiated with the image data carrying light beam. In synchronism with the formation of the toner image, recording mediums 2 disposed in a sheet feeder cassette 3a are separated and fed into the electrophotographic image forming apparatus one by one by a pickup roller 3b and a pressing member 3c placed in contact with the pickup roller 3b to apply a predetermined pressure. The recording medium 2 is further conveyed into the apparatus by a conveying means 3 comprising a conveyer roller pair 3d, a registration roller pair 3e, and the like. As a voltage is applied to a transfer roller 4 as a transferring means, the toner image formed on the electrophotographic photosensitive member integrally disposed in a process cartridge B is transferred onto the recording medium 2. The recording medium 2 having received the toner image is delivered to a fixing means 5 by a conveyer belt 3f. The fixing means 5 comprises a driving roller 5a, and a fixing roller 5d. The fixing roller 5d contains a heater 5b and is rotatively supported by a supporting member 5c. While the recording medium 2 is passed through the fixing means 5, heat and pressure are applied to the recording medium 2, whereby the toner image having been transferred onto the recording medium is fixed to the recording medium 2. The recording medium 2 with the fixed toner image is conveyed through a reversing passage and discharged into a sheet catcher portion 6, by discharge roller pairs 3g and 3h. This image forming apparatus A also comprises a manual feeder tray 3j and a roller pair 3i so that the recording medium 2 can be manually fed.

The process cartridge B in accordance with the present invention comprises an electrophotographic photosensitive member and a minimum of one processing means. The processing means includes a charging means for charging the electrophotographic photosensitive member, a developing means for developing the latent image formed on the electrophotographic photosensitive member, a cleaning means for cleaning the toner remaining the surface of the electrophotographic photosensitive member, and the like. Referring to FIG. 5, in the process cartridge B, a photosensitive drum 7, which is a drum-shaped electrophotographic photosensitive member with a photosensitive layer, is rotated, and the surface of the rotating photosensitive drum 7 is uniformly charged by applying a voltage to the charge roller 8 which is the charging means. The surface of the photosensitive drum 7 is exposed to an optical image projected from the aforementioned optical system 1 through an opening 9, whereby a latent image is formed on the photosensitive drum 7. The latent image is developed by a developing means 10. As is evident from FIG. 5, the charge roller 8 is in contact with the photosensitive drum 7.

In the developing means 10, the toner contained in a toner holding portion 10a is sent out by a first rotary toner feeding member 10b1 and a second rotary toner feeding member 10b2, onto a development roller 10d, which is a developing member containing a fixed magnet 10c. As the development roller 10d is rotated, a layer of toner triboelectrically charged by the development blade 10e is formed on the surface of the development roller 10d. The toner particles in the toner layer are transferred onto the photosensitive drum 7 in correspondence to the aforementioned latent image, whereby the latent image is developed into a toner image, that is, a visible image.

After the toner image is transferred onto the recording medium 2 by applying to the transfer roller 4 a voltage with a polarity opposite to that of the toner image, the toner remaining on the photosensitive drum 7 is removed by a cleaning means 11 comprising a cleaning blade 11a for scraping off the residual toner, a reception sheet 11b for receiving the toner scraped from the photosensitive drum 7, and a waste toner collector 11c for collecting the waste toner. As is evident from FIG. 5, the cleaning blade 11a is in contact with the photosensitive drum 7.

The components such as the photosensitive drum 7 are integrally disposed within the frame of the process cartridge B, so that they can be removably installed within the apparatus main assembly 14. The cartridge frame is formed by joining a development frame 12 and a cleaning frame 13. The development frame 12 is formed by welding together a toner holding frame portion 12a, a development frame bottom portion 12b, and a development frame lid 12c.

The process cartridge B is installed in the apparatus main assembly 14 by opening the lid 15 as shown in the drawing. Referring to FIGS. 7 and 8, the cartridge installating means comprises a pair of guide rails 16, which are exposed as the lid 15 is rotatively opened about an axis 15a (FIG. 4). The guide rails 16 are given an upward bowing curvature (in this embodiment, substantially arc-shaped), and symmetrically located in the respective lateral walls of the apparatus main assembly 4 across the cartridge accommodating space. Above the guide rail 16, a guide member 17 is attached. On the entrance side of the guide rail 16, a first slant surface 16a, and a second slant surface 16b are provided. The second slant surface 16b has a steeper angle than the first slant surface 16a, and extends further downward from the bottom end of the first slanted surface 16a.

On the other hand, the surfaces of the left and right longitudinal ends of the process cartridge B are provided with a guide portion, wherein the two guide portions symmetrically project in the longitudinal direction from the correspondent end surfaces of the process cartridge B, and are guided by the guide rail 16. Referring to FIG. 6, the guide portion integrally comprises a boss portion 18 and a rib portion 16. The boss portion 18 and the rib portion 19 are integrally formed with the cleaning frame 13 to which the photosensitive drum 7 is attached. The boss portion 18 is in line with the imaginary extension of the rotational axis of the photosensitive drum 7, and the rib portion 19 extends backward, relative to the inserting direction of the process cartridge B, from the boss portion 18, forming a upward bowing curvature (in this embodiment, substantially arc-shaped), which matches the configuration of the guide rail 16.

Referring to FIGS. 10-15, when the process cartridge B is installed into the apparatus main assembly with the above described structure, the lid 15 is first opened, and the process cartridge B is inserted into the apparatus main assembly 14 so that the leading end of the process cartridge B is caused to dive into the space below the optical means 1. The guide rail 16 is arc-shaped, and the guide member 17 disposed above the guide rail 16 is given a configuration matching that of the guide member 17. Further, the rib 19 also is given a configuration similar to that of the guide member 17. Consequently, as the process cartridge B is inserted deeper, its orientation becomes substantially horizontal. As the cartridge B is pushed further inward, a bumping member 20 provided on the apparatus main assembly 14 comes in contact with a contact surface 21 provided on each longitudinal end of the leading end portion of the cleaning frame 13, and then, the boss portion 18 of the process cartridge drops into a recess 16c located at the deepest end of the guide rail 16. As a result, a drum gear (unillustrated) fixed to one of the longitudinal ends of the photosensitive drum 7 is caused to engage with the driving gear 22 (FIG. 8) provided on the apparatus main assembly 14 side, enabling the driving force to be transmitted to the process cartridge B.

Next, referring to FIG. 12, as the lid 15 is closed, a pressing member 24, which is axially supported on the lid 15, and is under the pressure from a torsional coil spring, makes contact with the arm portion 15a of the cleaning frame 13, pressing it with a predetermined pressure generated from the torsional coil spring being torqued by the closing movement of the lid 15. At the same time, the bumping member 20 provided on the apparatus main assembly 14 makes contact with the contact surface 21 of the process cartridge B, fixing the position of the process cartridge B.

Referring to FIG. 15, in order to take out the process cartridge B, the users open the lid 15, whereby the pressure applied through the pressing member 24 is removed. In this state, the cartridge B is pulled upward so that the boss portion 18 comes out of the recess 16c. Thereafter, the process cartridge B can be removed by pulling it as if rotating it in the counterclockwise direction of FIG. 12, with the rib portion 19 following the guide rail 16.

The bottom portion of the cartridge frame is provided with an opening O, through which the photosensitive drum 7 comes in contact with the conveyed recording medium 2. When the cartridge is not in use, the opening is covered by closing a drum shutter member 28 to protect the photosensitive drum 7. Referring to FIG. 6, the drum shutter member 28 is rotatively supported by a shutter arm 27 and a link member 29. The shutter arm 27 is rotatively mounted on an axis 26 projecting outward from the longitudinal lateral wall of the development frame 12, but the link member 29 is supported on the longitudinal lateral wall of the cartridge frame so that it can be rotated about the rotational center 29a. As the process cartridge B is inserted along the guide rail 16 as described above, a projecting portion 29b constituted of the bend portion of the link member 29 comes in contact with the first and second slant surfaces 16a and 16b of the guide rail 16, causing the shutter member 28 to open (FIGS. 11 and 12). On the contrary, as the process cartridge B is taken out, the shutter member 28 is automatically closed by the pressure from the torsional coil spring 30 (FIG. 6) fitted around the axis 26.

When the process cartridge B is inserted into or removed from the image forming apparatus A, the users pick up process cartridge B by the handhold portion 12c2 of the development frame 12. The handhold portion 12c2 comprises the slanted upward facing surface of the cartridge lid 12c. Referring to FIG. 6, this slanted portion, that is, the handhold portion 12c2, is provided with minute ridges and valleys formed by numerous ribs 12c1 (extending in the direction perpendicular to the direction in which the process cartridge B is inserted into, or removed from, the apparatus main assembly). Referring to FIG. 5, the bottom portion of the cartridge frame is provided with an R portion which bulges downward, and this R portion is provided with several ribs 12a9 extending in the same direction as the aforementioned ribs 12a1, constituting the handhold portion 12a10. In order to install the process cartridge B into the image forming apparatus A, or remove it therefrom, the users pick up the process cartridge B by grasping it by the handhold portions 12c2 and 12a10 (ribs 12c1 and ribs 12a9) as illustrated in FIG. 20, and then insert it into the apparatus main assembly, with the boss portion 18 and the rib portion 19 of the cleaning frame 13 following the guide rail 16.

When the process cartridge B is pushed into the apparatus main assembly excessively fast, the process cartridge B is liable to be subjected to a large shock, which mostly acts on the pin 41 joining the development frame 12 and the cleaning frame 13. However, the development frame 12 and the cleaning frame 13 are rotatable about the pin 41; therefore, the aforementioned shock is distributed throughout the entire cartridge frame; the shock is not concentrated on a specific portion. In other word, the shock does not concentrate on the welded joint between the toner holding frame portion 12a and the development frame bottom portion 12b. Therefore, the strength with which the toner holding frame portion 12a and the development frame bottom portion 12b are welded has only to be enough to keep the both frame portions 12a and 12b joined. Consequently, when welding the toner holding frame portion 12a and the development frame bottom portion 12b, it is unnecessary to specifically control the welding conditions, allowing the development frame 12 to be assembled without losing productivity.

Further, the means for positioning the development roller 10d, and a mounting seat for the development blade 10e, are provided on the toner holding frame portion 12a as described in the foregoing. Therefore, in spite of the fact that the toner holding frame portion 12a is provided with the arm portion 38, the development roller 10d and the development blade 10e can be precisely positioned, so that their positional relationship with the photosensitive drum 7 mounted on the cleaning frame 13 can be maintained with sufficient precision.

Referring to FIGS. 6, 18 and 19, the structure for opening or closing the aforementioned drum shutter will be described.

Referring to FIG. 6, one end of the shutter arm 27 is rotatively mounted on the axis 26 provided on the longitudinal end surface of the toner holding frame portion 12a, and to the other end, a ring portion 28a formed at one end of the shorter edge of the drum shutter member (protective cover) 28 is rotatively attached. The shutter member 28 is provided with a groove 28b, which runs adjacent to the longitudinal edge on the side opposite to the ring portion 28a, across the entire length of the edge. In this groove 28b, the shutter link member (supporting member) 29 formed by bending the metallic wire is rotatively anchored.

Referring to FIGS. 6 and 18, the end portion 29a of the link member 29 is rotatively supported by a link supporting member 36 and a gear cover 31. Referring to FIG. 19, the link supporting member 36 covers a toner filling opening 32 of the toner holding frame portion 12a. During the assembly process of the process cartridge B, toner is filled into the toner holding portion 10a through the toner filling opening 32, and the toner filling opening 32 is sealing with a cap 33. Thereafter, the link supporting member 36 is welded to the toner holding frame portion 12a, covering cap 33.

The link supporting member (link mount) 36 is provided with an axis hole 36a, which is located at a specific spot (after the welding of the link supporting member 36 to the toner holding frame portion 12a, it is located directly above the toner filling opening 32). The end portion 29a of the link member 29 is inserted into this axis hole 36a, whereby the link member 29 is rotatively supported at the end portion 29a.

Referring to FIG. 18, on the other side of the process cartridge B, a gear train comprising a drum gear 21a fixed to the longitudinal end of the photosensitive drum 7, and gears 21b-21g, are mounted on the longitudinal end surface of the toner holding frame portion 12a. This gear train transmits a driving force to the development roller 10d and the toner feeding members 10b1 and 10b2. The aforementioned gear cover 31 is attached to cover this gear train. The other end 29a of the link member 29 is inserted into an axis hole 31a provided in the gear cover 31 to rotatively support the link member 29 at the end portion 29a.

When seen from the direction indicated by an arrow mark in FIG. 6, the link member 29 forms an L-shape, and from its bend portion, a U-shaped projection 29b projects outward in the longitudinal direction of the process cartridge B. As this projection 29b is rotatively moved, the link member 29 is rotatively moved, whereby the shutter member 28 is caused to expose or cover the opening O.

The aforementioned axis 26 is provided with a torsional coil spring 30, one end of the spring 30 being anchored to the shutter arm 27 and the other end being anchored to the cleaning frame 13; therefore, the shutter member 28 remains under the constant pressure in the closing direction generated by the elasticity of the spring 30.

Next, referring to FIGS. 10-15, the opening and closing movements of the drum shutter 28 will be described. First, referring to FIG. 11, as the process cartridge B is inserted into the image forming apparatus A as described before, the projection 29b of the link member 29 comes in contact with the first slanted surface 16a of the guide rail 16. At this moment of the contact, the angle .theta. formed by the first slanted surface 16a and the link member 29 is an acute angle. As a result, the link member 29 and the first slanted surface 16a do not prop against each other, allowing the shutter member 28 to be smoothly opened, and also allowing the smooth insertion of the process cartridge B.

Next, referring to FIG. 12, as the process cartridge B is further inserted, the shutter member 28 is gradually opened backward because the projection 29b remains in contact with the first slanted surface 16a. As the process cartridge B is inserted deeper, the projection 29b moves onto the second slanted surface 16b of the guide rail 16, ending the process cartridge B insertion process, as shown in FIGS. 13 and 14. This second slanted surface 16b is given a steeper angle than the first slanted surface 16a, allowing the shutter member 28 to remain open in the same open state even after the projection 29b of the link member 29 moves onto the second slanted surface 16b due to the further insertion of the process cartridge B; therefore, the shutter member 28 does not open too far, nor does it fail to open sufficiently.

As described above, the shutter member 28 opens or closes as the link member 29 is rotatively moved. But, because the link member 29 is supported by the link supporting member 36 which covers the toner filling opening 32, the rotational center of the link member 29 can be positioned right above the toner filling opening. Therefore, more latitude can be afforded for the positioning of the rotational center of the link member 29, which otherwise is more restricted since the shutter member 28 must follow a predetermined locus within the limited internal space of the image forming apparatus A; even when the size of the toner filling opening 32 must be designed to be large to increase the toner filling efficiency, more latitude can be afforded in determining the location of the mounting point for the link member 29.

Next, the structure of the cartridge frame will be described. The cartridge frame is formed of polystyrol resin using injection molding. Referring to FIG. 16, the cartridge frame is formed by joining a first frame, which is the development frame 12, and a second frame, which is the cleaning frame 13 (drum frame). The development frame 12 is formed by welding the development frame bottom portion 12b (development roller supporting frame) to the toner holding frame portion 12a along their longitudinal edges, and then, welding the lid 12c to the top portion of the preceding two frame portions.

The toner holding frame portion 12a is provided with the toner supply opening 12a1 and the toner filling opening 12a2. The toner supply opening 12a1 extends in the longitudinal direction, and the toner filling opening 12a2 is located in one of the longitudinal end walls. Within the toner holding frame portion 12a, a number of supporting member 12a3 are provided. They stand upright, and are aligned in the longitudinal direction of the frame portion.

When the developing means is assembled, the first toner feeding member 10b1 is first assembled into the toner holding frame portion 12a, and then, the lid member 12c is welded. Next, the toner supply opening 12a1 is sealed by welding a toner seal member (film) 31 to the seal attachment seat 12a5 formed around the toner supply opening 12a1. Then, after toner is filled into the toner holding portion 10a of the toner holding frame portion 12a, the cap 32 is placed over the toner filling opening 12a2 to seal the toner holding portion 10a. Referring to FIG. 17, the toner sealing member 31 having sealed the toner supply opening 12a1 is folded back at one of the longitudinal ends of the toner supply opening 12a1, and its free end is caused to be exposed through a slit 12a8 of the toner holding frame portion 12a, so that the users can remove the toner sealing member 31 by pulling the exposed free end when the process cartridge B is initially put to use.

Next, the development frame bottom portion 12b is welded to the toner holding frame portion 12a along the longitudinal edges, and the second toner feeding member 10b2 is attached to the development frame bottom portion 12b. Then, a seal 35 formed of foamed urethane, or the like is attached below a blade mounting seat 12a4, and the development blade 10e is screwed to the blade mounting seat 12a4. Next, bearings 33a and 33b, a seal 34 formed of foamed urethane or the like, are attached, and the axis of the development roller 10d is placed in the bearings 33a and 33b. The toner holding frame portion 12a is provided with an arc-shaped portion 12a6, which is a positioning means for fixing the bearings 33a and 33b; the bearings 33a and 33b are fixed to the arc-shaped portion 12a6 of the toner holding frame portion 12a. Therefore, the development roller 10d, the axis of which is supported by the bearings 33a and 33b, is attached to the toner holding frame portion 12a with a preferable degree of precision.

The link support member 36 is attached at one of the longitudinal ends of the development frame 12, covering the aforementioned cap 32. On the other side of the development frame 12, the gear train for transmitting the driving force to the photosensitive drum 7, the development roller 10d, and the like are mounted, and the gear cover 37 is attached to cover the gear train. The gear cover 37 is provided with a positioning axis 37a; the gear cover 37 is fixed to the toner holding frame portion 12a using engagement claws, screws, or the like after its position is fixed by inserting this positioning axis 37a into the hole 33a1 of the bearing 33a, and the hole 12a7 of the toner holding frame portion 12a.

One of the longitudinal ends of the toner holding frame portion 12a is provided with an arm portion 38 as a joint portion, which is integrally formed with the toner holding frame portion 12a. Also, the gear cover 37 attached to the other longitudinal end of the toner holding frame portion 12a is provided with the arm portion 38 as the joint portion (FIG. 16).

The development frame 12, into which various components constituting the aforementioned developing means have been assembled, and the cleaning frame 13, into which the photosensitive drum 7, the charge roller 8, and various components constituting the cleaning means, have been assembled, are joined together at the arm portions 38, completing the process cartridge B.

Next, referring to FIGS. 1-3, the structure for joining the development frame 12 and the cleaning frame 13 will be described. FIG. 1 is a perspective view of both frames 12 and 13, depicting how they are joined. FIG. 2 depicts the internal structure of the joint, and FIG. 3 is a partially cutaway schematic plan view of the joint. The structures of the left and right joints at which the frames 12 and 13 are rotatively connected to each other with the arm portions 38 are the same; therefore, the structure on only one side will be described.

Referring to FIGS. 2 and 3, in order to give some elastic flexibility to the angle formed between the development frame 12 and the cleaning frame 13, the process cartridge B is provided with a compression spring 40, which is attached to a compression spring anchoring member 39 which integrally comprises a spring attachment portion 39a and a cylindrical portion 39d. The cylindrical portion 39d has a larger diameter than the diameter of the compression spring 40 attached to the spring attachment portion 39a. The head portion of the cylindrical portion is provided with a rib 39b, and the peripheral surface of the cylindrical portion 39d is provided with two flanges 39c.

The upward facing surface of the arm portion 38 of the development frame 12 is provided with a recess 38a (receiving portion). The location of the recess 38a is such that after the development frame 12 and the cleaning frame 13 are rotatively joined as will be described later, the recess 38a is located right below the attachment hole 13a of the cleaning frame 13. Further, a through hole 38b through which a pin 41 is put is provided at the tip portion of the arm portion 38. The pin 41 will be described later.

On the other hand, the cleaning frame 13 is provided with an attachment hole 13a into which the aforementioned spring anchoring member 39 is pressed. Referring to FIGS. 2 and 3, the attachment hole 13a is constituted of a cylindrical hole portion 13a1 slightly larger than the flange 39c or the cylindrical portion 39d of the spring anchoring member 39, and a cutaway portion 13a2. The external wall 13b of the cleaning frame 13 is provided with a hole 13c through which the pin 41 is put, and the internal wall 13d of the cleaning frame 13 is provided with a hole 13e into which the pin 41 is pressed. The axial lines of the holes 13c and 13e coincide with each other, and are parallel to the axial lines of the holes 13c and 13e provided on the other side, relative to the longitudinal direction, of the cleaning frame 13. Further, a rib 13f is provided on the interior surface of the cleaning frame 13, adjacent to the attachment hole 13a.

Referring to FIGS. 2 and 3, when the development frame 12 and cleaning frame 13 are joined using the above structure, first, the arm portion 38 of the development frame 12 is inserted into the joining portion 13h of the cleaning frame 13. Next, the pin 41 is put through the hole 13c of the cleaning frame 13, and the through hole 38b of the arm portion 38, in this order, and then is pressed into the hole 13e. As a result, the development frame 12 and cleaning frame 13 are joined in such a manner that they are rotatable about the pin 41. At this stage of the process cartridge B assembly, no pressure is present to press the photosensitive drum 7 and development roller 10d toward each other; therefore, assembly workers can easily examine the degree of the rotatability of both components.

Next, referring to FIG. 2, the spring anchoring member 39 to which the spring 40 has been attached is put through the attachment hole 13a; the cutaway portion 13a2 of the attachment hole 13a, and the flange 39c of the spring anchoring member 39, are aligned, with the tip of the spring 40 placed in contact with the bottom surface of the recess 38a, and the spring anchoring member 39 is pressed straight down in the compressing direction of the spring 40 until the upper surface of the flange 39c of the spring anchoring member 39 comes to be located below the rib 13f, and the cylindrical portion 39d comes to be guided by the cylindrical hole portion 13a1 of the attachment hole 13a. In this state, the spring anchoring member 39 is rotated 90.degree., and is released. Consequently, the spring anchoring member 39 is pushed up, being guided by the cylindrical hole portion 13a1, by the resiliency of the spring 40, and is stopped at a point at which the flange 39c strikes the bottom edge of the attachment hole 13a.

As a result, the development roller 10d mounted in the development frame 12 is pressed toward the photosensitive drum 7 mounted in the cleaning frame 13, coming in contact with the ring members (unillustrated) as spacers mounted at the longitudinal ends of the development roller 10d, and thereby coming to be accurately positioned relative to the photosensitive drum 7. At the same time, the drum gear fixed to the longitudinal end of the photosensitive drum 7 becomes engaged with a roller gear fixed to the longitudinal end of the development roller 10d, enabling the driving force to be transmitted.

The aforementioned process cartridge B has the following structure. The process cartridge B removably installable in the main assembly of an image forming apparatus A comprises a drum frame 13 (cleaning frame), a development frame 12, a toner frame 12a. The drum frame 13 houses electrophotographic photosensitive drum 7, a charging roller 8 for charging the electrophotographic photosensitive drum 7, a cleaning blade 11a for removing the toner remaining on the electrophotographic photosensitive drum 7, wherein the charging roller 8 is in contact with the electrophotographic photosensitive drum 7, and the cleaning blade 11a is in contact with the electrophotographic photosensitive drum 7. The development frame 12 houses a development roller 10d for developing the latent image formed on the electrophotographic photosensitive drum 7, and the toner holding frame portion 12a comprises a toner holding portion 10a for holding the toner used for the aforementioned development. The toner holding frame portion 12a is joined with the development frame 12 along their longitudinal edges, and also supports an arm portion 38. The arm portion 38 is disposed at each longitudinal end of the toner holding frame portion 12a, and projects toward the drum frame 13 in the direction perpendicular to the longitudinal direction thereof, enabling the development frame 12 and the drum frame 13 to be joined so as to be oscillatable relative to each other. Also, the toner holding frame portion 12a comprises handhold portions 12a10 and 12c2 for holding the process cartridge B. They are located on the opposite side of the toner holding frame portion 12a relative to the drum frame 13. The handhold portions 12a10 and 12c2 are partially constituted of the lid 12c of the toner holding portion 10a of the toner holding frame portion 12a; therefore, they become the part of the toner holding frame portion 12a as the lid 12c is attached to the toner holding frame portion 12a. Further, the toner holding frame portion 12a is provided with a toner filling opening 12a2 through which the toner is filled, and a toner supply opening 12a1 for supplying to the development roller 10d the toner held in the toner holding portion 10a, and a toner seal mount 12a5 on which a toner seal 31 is attached. The toner filling opening 12a2 is located at one of the longitudinal ends of the toner holding frame portion 12a, and the toner supply opening 12a1 and the toner seal mount 12a5 extend in the longitudinal direction of the toner holding frame portion 12a. The toner seal 31 unsealably seals the toner supply opening 12a1. The toner holding frame portion 12a and the development frame 12 are joined by a pin 41 placed through a hole 38b of the arm portion 38, and holes 13c and 13e of the drum frame 13, wherein the development frame 12 joined with the toner holding frame portion 12a, and the drum frame 13, are rotatable about the pin 41.

In other words, in this embodiment, after the development frame 12 and drum frame 13 are rotatively joined, and the degree of the rotatability of the photosensitive drum 7 and development roller 10d is confirmed, the photosensitive drum 7 and the development roller 10d are pressed toward each other by the spring 40 anchored by the spring anchoring member 39; therefore, the possibility of the fluctuation of the pressure applied to the photosensitive drum 7 by the development roller 10d is eliminated. Further, the spring anchoring member 39 is attached so as to keep appropriately compressed the compression spring 40 attached to the spring anchoring member 39; therefore, the compression spring 40 is not liable to buckle. Further, the spring anchoring member 39 can be replaced without removing the spring cover. In other words, the spring anchoring member 39 can be replaced, the development and drum frames 12 and 13 remaining connected, enabling the spring anchoring member 39 to be exchanged with a spring anchoring member with a spring having a proper pressure, substantially regardless of the cartridge assembling order.

Consequently, the assembly efficiency for the process cartridge B is improved. In addition, when an image is formed using the process cartridge B described above, the pressure applied by the development roller 10d does not fluctuate as described above; therefore, a high quality image can be produced.

Next, various components of the process cartridge B and the image forming apparatus in accordance with the present invention will be described.

In the preceding embodiment, one of the arm portions 38 for connecting the development frame 12 and the cleaning frame 13 was disposed on the gear cover 37, and this gear cover 37 was fixed to one of the longitudinal ends of the development frame 12, but both arm portions 38 may be directly formed on the toner holding frame portion 12a. This arrangement can also effectively disperse the shock generated during the installation of the process cartridge B.

Further, in the preceding embodiment, the link supporting member 36 was welded to the cartridge frame, but the link supporting member 36 may be screwed to the cartridge frame, or may be glued to the cartridge frame with adhesive.

Next, referring to FIGS. 21 and 22, the internal structure of the toner holding frame portion 12a will be described. As will be become clear from the following description, partition members 12a3 are provided within the toner holding frame portion 12a, wherein a gap is provided between the partition member 12a3 and the frame lid 12c. This arrangement is made so that even when the frame lid 12c is flexed as the users firmly grasp the toner holding frame portion 12a (pcB), the flexed portion of the frame lid 12c can be supported by the top surface of the partition member 12a3.

A gap is also provided between the partition member 12a3 and the toner holding portion 10a. This arrangement is made so that the toner poured into the toner holding portion 10a through the toner filling opening 12a2 can be delivered with preferable efficiency into each of the spaces partitioned by the partition members 12a3 in spite of the presence of the partition members 12a3.

Referring to FIG. 16, the slant surface on the top of the frame lid 12c is provided with several parallel ribs 12c1, constituting a handhold portion 12c2. Further, referring to FIG. 21, the bottom portion of the toner holding frame portion 12a is provided with an R portion which bulges downward. The external surface of the R portion is also provided with several parallel ribs 12a5, constituting a handhold portion 12a10. The users can easily hold the process cartridge B by grasping the handhold portions 12a10 and 12c2, so that the process cartridge B can be smoothly installed into, or removed from, the image forming apparatus A (FIG. 9).

At this time, the relationship between the partition member 12a3 provided within the toner holding portion 10a, and the frame wall surface will be described. Referring to FIG. 5, a gap S1 is provided between the rear edge of the partition member 12a3 and the internal surface of the rear wall of the toner holding frame portion 12a ("rear" relative to the direction in which the toner within the toner holding portion 10a is supplied to the development roller 10d). Also, a minute gap S2 is provided between the top end of the partition member 12a3 and the internal surface of the frame lid 12c.

The purpose of the partition member 12a3 is to minimize the deformation of the toner holding frame portion 12a and the frame lid 12c when excessive pressure is applied by the users who handle the process cartridge B by gripping the handhold portions 12c2 and 12a10. In other words, even if the users firmly grasp the process cartridge B, and consequently, the toner holding frame portion 12a and/or the frame lid 12c become deformed, the top end of the partition member 12a3 and the internal surface of the frame lid 12c come in contact with each other, regulating the amount of the deformation.

With the presence of the partition members 12a3 within the toner holding portion 10a, unless the internal air of the toner holding portion 10a is properly released while the toner is filled, the toner cannot be filled with sufficiently high density.

Thus, in this embodiment, the gap S1 is provided between the partition member 12a3 and the internal surface of the rear wall of the toner holding frame portion 12a as described above. Consequently, when the toner is filled through the toner filling opening 12a2, the internal air of the toner holding portion 10a is allowed to flow through the gap S1 and out of the toner holding portion 10a as illustrated in FIG. 22 (a black arrow mark indicates the toner flow, and a white arrow mark indicates the air flow). As a result, the toner can be smoothly filled into the toner holding portion 10a, with a sufficient density.

It should be noted here that in order to provide a proper balance between the air releasing efficiency and the effectiveness in regulating the frame deformation, the gap S1 is preferred to be 5 mm-20 mm.

Also as described before, in this embodiment, the gap S2 is provided between the top end of the partition member 12a3 and the frame lid 12c; therefore, the generation of burr is prevented. More specifically, when the frame lid 12c is attached to the toner holding frame portion 12a without providing the gap S2, the top end of the partition member 12a3 and the internal surface of the frame lid 12c sometimes make contact due to manufacturing error. If the toner holding frame portion 12a and the frame lid 12c are welded together by ultrasonic welding when the partition member 12a3 and the frame lid 12c are in contact with each other, the burr may be generated between the top end of the partition member 12a3 and the internal wall of the frame lid 12c, and when generated, the burr is liable to drop into the toner holding portion 10a, and mix with the toner, forming a toner nucleus, during the transportation of the process cartridge B, or in the like situation. But, according to the present invention, the generation of the burr can be prevented.

On the other hand, when the gap S2 is too large, the internal pressure of the toner holding portion 10a is liable to increase. This is because when the handhold portion formed on the frame lid 12c welded to the toner holding frame portion 12a using ultrasonic welding is firmly gripped, the presence of an excessive gap is liable to allow both frame portions to deform. Thus, the size of the gap S2 is preferred to be set within a range of 0.0-0.5 mm so that when the handhold portions are firmly gripped, the deformation of the toner holding frame portion 12a and the frame lid 12c can be minimized. In this embodiment, the gap S2 is set at 0.2 mm.

As is evident from the above descriptions, not only does the provision of the gaps S1 and S2 between the partition member 12a3 and the internal surface of the frame allow the toner to be filled with high density, but also, prevents the burr from mixing into the toner, and minimizes the frame deformation.

A process cartridge B is detachably mountable to a main assembly of an image forming apparatus, and comprises: a. an electrophotographic photosensitive drum 7; b. a developing roller 10d for developing a latent image formed on the electrophotographic photosensitive drum 7, the developing roller supplying toner to the electrophotographic photosensitive drum 7 by rotation thereof; c. a charging roller 8 for charging the electrophotographic photosensitive drum 7, the charging roller 8 being contacted to the electrophotographic photosensitive drum 7; d. a cleaning blade 11a for removing residual toner from the electrophotographic photosensitive drum 7; e. a toner accommodating container 12a, including: a toner accommodating portion 10a for accommodating toner usable for developing a latent image formed on the electrophotographic photosensitive drum 7, wherein the toner accommodating portion 10a is provided with a toner supply opening 12a1 for supplying the toner to the electrophotographic photosensitive drum 7 from the toner accommodating portion 10a; a partition wall 12a3 extending in the toner accommodating portion in a direction along a short side of the toner accommodating portion to define a plurality of space therein, wherein the toner accommodating portion has a bottom surface slanted down toward the toner supply opening, and the partition is provided on the slanted surface; a toner filling opening 12a2, at a longitudinal end of the toner accommodating portion, for permitting toner to be filled into the toner accommodating portion; and a through-passage S1 extending from one longitudinal end to the other longitudinal end along a length of the toner accommodating portion so as to permit the toner to be supplied into the spaces, the through-passage being formed between a wall surface of the toner accommodating portion and the partition wall, wherein the through-passage S1 is provided between a rear wall surface opposed to the toner supply opening and the partition wall.

Also, a process cartridge B is detachably mountable to a main assembly of an image forming apparatus, and comprises: a. an electrophotographic photosensitive drum 7; b. a developing roller 10d for developing a latent image formed on the electrophotographic photosensitive drum 7, the developing roller supplying toner to the electrophotographic photosensitive drum 7 by rotation thereof; c. a charging roller 8 for charging the electrophotographic photosensitive drum 7, the charging roller 8 being contacted to the electrophotographic photosensitive drum 7; d. a cleaning blade 11a for removing residual toner from the electrophotographic photosensitive drum 7; e. a toner accommodating container 12a, including: a toner accommodating portion 10a for accommodating toner usable for developing a latent image formed on the electrophotographic photosensitive drum 7, wherein the toner accommodating portion 10a is provided with a toner supply opening 12a1 for supplying the toner to the electrophotographic photosensitive drum 7 from the toner accommodating portion 10a; a cover member 12c for covering an opening other than the toner supply opening 12a1, wherein the cover member 12c covers the opening provided at an upper portion of the toner accommodating portion 10a, which portion takes an upper position when the process cartridge is mounted on the main assembly of the image forming apparatus; a handle portion 12c2 on the cover member 12c for facilitating handling of the toner accommodating container, wherein the handle portion 12c2 has a plurality of ribs 12c1. The outer surface of the toner accommodating container has a plurality of ribs 12a9. When the container 12a is handled, the rib of the cover and the rib of the container 10a.

In order to fill the toner into the portion 10a, there are provided a toner filling opening 12a2 at one longitudinal end of the accommodating portion, the partition wall 12a3 for partitioning the inside space of the portion 10a. A gap S2 is formed between the cover member 12c and the partition wall 12a3. When the cover bends upon gripping the toner accommodating container, the partition wall 12a3 and the cover 12c are contactable. The gap S2 between the partition wall 12a3 and the cover 12c is not more than approx. 0.5 mm. The toner accommodating portion 10a and the cover 12c are welded.

Next, referring to FIGS. 23-26, another embodiment of the process cartridge will be described. Also in this embodiment, a gap X is provided between the bottom end 111e1 of a partition member 111e1, and the frame lid 111b. FIG. 23 is a cross section of the process cartridge B; FIG. 24, an external perspective view thereof; and FIG. 25 is an internal perspective view of the toner holding frame portion 111. This process cartridge B is also removably installable in the main assembly of the image forming apparatus (laser beam printer) illustrated in FIGS. 4 and 9.

Referring to FIGS. 23 and 24, in this process cartridge B, a photosensitive drum 107 with a photosensitive layer is rotated, and the surface of the rotating photosensitive drum 107 is uniformly charged by applying a voltage to the charge roller 108 which is the charging means. The charged surface of the photosensitive drum 107 is exposed to an optical image projected from an optical means 1 through an exposure opening 126, whereby a latent image is formed on the photosensitive drum 107. The latent image is developed by a developing means 109, that is, a developing apparatus.

In the developing means 109, the toner contained in a toner holding portion 109a is sent out by a toner feeding member 109b onto a development roller 109c containing a fixed magnet. As the development roller 109c is rotated, a layer of toner triboelectrically charged by the development blade 109d is formed on the surface of the development roller 109c. The toner particles in the toner layer are transferred onto the photosensitive drum 107 in correspondence to the aforementioned latent image, whereby the latent image is developed into a toner image, that is, a visible image.

After the toner image is transferred onto the recording medium 2 by applying a voltage with a polarity opposite to that of the toner image, to the transfer roller 4 provided in the main assembly of the image forming apparatus A, the toner remaining on the photosensitive drum 107 is removed by a cleaning means 110 comprising a cleaning blade 110a for scraping off the residual toner, and a waste toner collector 110b for collecting the waste toner.

The components such as the photosensitive drum 107 are integrally disposed within a housing in the form of a cartridge, that is, the process cartridge B, which is formed by joining the toner holding frame portion 111 and the development frame portion 112, and then joining the cleaning frame 113 with the combination of the preceding two. The thus formed process cartridge B is removably installed into the cartridge accommodating means provided within the main apparatus of the image forming apparatus A.

The surface of both longitudinal ends of the process cartridge B are provided with a dowel 113a, a long guide 112a, and a short guide 113b, which are guided by a guide portion provided on the main assembly of the image forming apparatus A.

Referring to FIGS. 23 and 24, the process cartridge B is provided with handhold portions 117 and ribs 123 and 124 so that the process cartridge B can be easily held. Further, the process cartridge B is provided with a drum shutter 118 (FIG. 23), the opening or closing movement of which is linked to the movement of the process cartridge B in the inserting or removing direction relative to the image forming apparatus A, so that when the process cartridge B is out of the image forming apparatus A, the shutter 118 remains closed to protect the photosensitive drum 107.

The process cartridge B in accordance with the present invention comprises a housing formed by joining the toner holding frame portion 111, the development frame 112, and the cleaning frame 113. Next, the structure of this housing will be described.

Referring to FIG. 23, the toner holding frame portion 111 comprises the toner holding portion 109a, and the toner feeding member 109b is attached to the toner holding frame portion 111. The development roller 109c and the development blade 109d are mounted within the development frame 112, and a stirring member 109e for circulating the toner within the development chamber is rotatively mounted adjacent to the development roller 109c. The toner holding frame portion 111 and the development frame 112 are united by welding, forming a development unit as a second frame (FIG. 24). The structure of the toner holding frame portion 111 will be described later in detail.

The photosensitive drum 107, the charge roller 108, and the cleaning means 110 are mounted in the cleaning frame 113, and thereafter, the drum shutter 118 which covers and protects the photosensitive drum 107 when the process cartridge B is out of the apparatus main assembly, is also attached to the cleaning frame 113, forming a cleaning unit as a first frame (FIG. 24).

Lastly, the development unit and the cleaning unit are joined using a joining member 122, completing the process cartridge B. A reference numeral 113c in FIG. 24 designates a positioning portion which comes in contact with a positioning seat provided within the main assembly of the image forming apparatus A.

Next, the structure of the toner holding frame portion 111 will be described more concretely. Referring to FIG. 23, the toner holding frame portion 111 is formed by welding together a main portion 111a, which is the top portion, and a lid portion 111b, which is the bottom portion.

Referring to FIG. 25, the main portion 111a of the toner holding frame portion 111 is provided with two handhold portions 117, which are constituted of a recess extending in the longitudinal direction of the process cartridge B. Further, within the main portion 111a, a deformation prevention rib 111e as a partition member is erected at three locations, being aligned in the longitudinal direction of the process cartridge B. These deformation prevention ribs 111e are provided to counter the pressure applied to the toner holding frame portion 111 as the users grip the toner holding frame portion 111 to insert or remove the process cartridge B.

For example, when the users hold the process cartridge B with hands, gripping the both handhold portions 117 of the toner holding frame portion 111, the thumbs contact the bottom surface of the toner holding frame portion 111, and the fingers bend into the handhold portions 117. In this state, the toner holding frame portion 111 is subjected to the forces indicated by arrow marks a and b. When the longitudinally center portion of the toner holding frame portion 111 is gripped by a hand, the thumb contacts the top surface of the toner holding frame portion 111, and the fingers contact the bottom surface of the toner holding frame portion 111. In this case, the toner holding frame portion 111 is subjected to forces indicated by arrow marks a and c. However, in the aforementioned toner holding frame portion 111, the deformation prevention rib 111e is erected at three locations, in alignment in the longitudinal direction of the toner holding frame portion 111, in order to counter the aforementioned pressures (in the directions of the arrow marks a, b and c); therefore, the deformation of the toner holding frame portion 111 caused by the aforementioned pressures can be minimized, preventing thereby the toner from being blown out due to the pressure change within the toner holding frame portion 111.

Further, the toner holding frame portion 111 is provided with an opening 111d for filling the toner, wherein the deformation prevention ribs 111e are positioned so as avoid the opening 111d. Therefore, the toner can be smoothly filled through the opening 111d, into the toner holding frame portion 111 with no interference from the deformation prevention ribs 111e.

Further, the locations at which the deformation prevention ribs 111e are positioned are determined in consideration of their positional relationship with the handhold portions 117; they are positioned corresponding to the specific areas of the toner holding frame portion 111, that is, the areas where the aforementioned pressures are applied, in other words, the areas by which the users grip the process cartridge B (in particular, the area where the thumb contacts). Therefore, the deformation of the toner holding frame portion 111 can reliably prevented.

Further, a minute gap X (FIG. 23) is provided between the end portion of the deformation prevention rib 111e and the lid portion 111b, so that when the main portion 111a of the toner holding frame portion 111, in which the deformation prevention ribs 111e are erected, and the lid portion 111b, are welded together, the deformation prevention ribs 111e are prevented from interfering with the welding operation. However, this gap X is rendered as small as possible in order to prevent the toner blow out, which is caused by the internal pressure change of the toner holding frame portion 111, which is caused by the deformation of the toner holding frame portion 111. In this embodiment, the size of the gap X is set within a range of 0.1-1.0 mm. With this arrangement, the deformation prevention ribs 111e do not interfere with the operation for welding together the lid portion 111b and the main portion 111a, and at the same time, the deformation of the toner holding frame portion 111 is minimized during the cartridge installation or removal. As a result, the toner blow out which is caused by the pressure change within the toner holding frame portion 111 can be prevented.

According to the present invention, only the deformation prevention ribs 111e are provided as the means for preventing the deformation of the toner holding frame portion 111. Moreover, the deformation prevention ribs 111e are integrally formed with the lid portion 111b; therefore, the above effects can be obtained with low cost.

In the preceding embodiment, the structure, in which the deformation prevention ribs 111e were erected within the toner holding frame portion 111, at three different locations, in alignment in the longitudinal direction of the toner holding frame portion 111, was described. But, the present invention is not limited by this structure. For example, referring to FIG. 26, a deformation prevention rib 111f which extends in the longitudinal direction may be erected in the toner holding frame portion 111. This structure can also minimize the deformation of the toner holding frame portion 111 caused by the pressure applied to the toner holding frame portion 111 when the process cartridge B is gripped by the handhold portions 117 of the toner holding frame portion 111, and therefore, the same effects as those described in the preceding embodiment can be obtained. In this case, the deformation prevention rib 111f is provided with a number of openings 111f1 across its length so that the space above (referring to FIG. 26) the deformation prevention rib 111f can also be utilized as the toner holding space.

Further, in the preceding embodiment, the structure, in which the deformation prevention rib is erected as the partition member at three locations, in alignment in the longitudinal direction of the toner holding frame portion, was described. But, the present invention is not limited by this structure. For example, the deformation prevention rib may be erected at two locations, or three or more. The number of the deformation prevention ribs is optional; it may be selected depending on the cartridge size or the cartridge strength. Obviously, such modifications can also provide the same effects as those described in the preceding embodiment.

As described above, the partition members are effected within the developer holding portion in such a manner that they can counter the pressure applied to the developer holding portion during the installation or removal of the cartridge; therefore, the deformation of the developer holding portion, which is caused as the developer holding portion is gripped during the installation or removal of the cartridge, can be minimized. As a result, the developer blowout resultant from the deformation of the developer holding portion can be prevented with low cost.

Further, the developer holding portion is provided with an opening for filling the developer, but the partition members are located so as to avoid the opening; therefore, the developer can be smoothly filled through the opening into the developer holding portion, with no interference from the partition members.

Further, the developer holding portion is provided with the handhold portions for the installation or removal of the cartridge, wherein the partition members are erected corresponding to where the pressure is applied when the handhold portion is gripped; therefore, the deformation of the developer holding portion can be more reliably prevented. As a result, it is possible to prevent the toner blowout caused by the pressure change within the developer holding portion.

Further, the developer holding portion is formed by joining a top frame portion and a bottom frame portion, wherein the top frame portion is provided with the partition members, and a minute gap is provided between the bottom edge of the partition member and the bottom frame portion; therefore, the partition member does not interfere with the operation for uniting the top and bottom frame portions, and at the same time, the deformation of the developer holding portion can be minimized during the installation or removal of the cartridge. As a result, the developer blowout caused by the air pressure change within the developer holding portion can be prevented.

Further, the aforementioned process cartridge B was of a type for forming a monochromatic image. However, not only is the present invention preferably applicable to the process cartridge which forms a monochromatic image, but also to a cartridge which comprises two or more developing means, and forms a multi-color image (for example, a two-color image, a three-color image, a full-color image, and the like).

As for the developing method, various known development methods such as the magnetic brush development method employing two component toner, the cascade development method, the touchdown development method, or cloud development method may be employed.

The electrophotographic photosensitive member is not limited to the photosensitive drum. For example, the following may be included.

First, as the photosensitive material, photoconductive material such as amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, or organic photoconductor (OPC) may be included. As for the shape of the base member on which the photosensitive material is placed, a rotary member such as a drum or a member in the form of a sheet such as an endless belt, are included. Generally, a member in the form of a drum or a belt is employed. For example, a photosensitive drum comprises a cylinder of aluminum alloy or the like, and photoconductive material deposited or coated thereon.

The structure of the charging means described in the preceding embodiment was of the so-called contact type, but it is obvious that other conventional structures may be employed, for example, a structure in which a tungsten wire is surrounded on three sides by a shield of metallic material such as aluminum, and positive or negative ions generated by applying a high voltage to the tungsten wire are transferred onto the surface of the photosensitive drum to uniformly charge the drum surface.

As for the charging means, a charging means of the blade type (charging blade), the pad type, the block type, the rod type, the wire type, or the like may be employed in addition to the roller type charging means described in the preceding embodiment.

Regarding the method for cleaning the toner remaining on the photosensitive drum, the cleaning means may comprise a blade, a fur brush, a magnetic brush, or the like.

The process cartridge in accordance with the present invention comprises at least an electrophotographic photosensitive member and a developing means. Typically, a combination of a developing means, an electrophotographic photosensitive member, a charging means, and a cleaning means, a combination of a developing means, an electrophotographic photosensitive member, and a charging means or a cleaning means, a combination of a developing means and an electrophotographic photosensitive member, or the like combination is integrated in the form of a cartridge so that it can be removably installed into the main assembly of an apparatus.

Further, in the preceding embodiment, the image forming apparatus was represented by a laser beam printer, but the present invention is not limited by the preceding embodiment. Obviously, the present invention is also applicable to other image forming apparatuses such as an electrophotographic copying machine, a facsimile apparatus, or a word processor.

As described in the foregoing according to the present invention, a partition wall is provided in the developer accommodating portion, which function as a reinforcing member against urging force imparted thereto. Therefore, the deformation of the developer accommodating portion is minimized when the process cartridge is handled, so that the possible blowing-out of the toner can be prevented at low cost.

The developer accommodating portion has an opening for filling the developer, and the partition is extended so as not the reach the opening, so that when the developer is filled into the developer accommodating portion, the partition does not obstruct the filling operation.

The developer accommodating portion has a grip of handle for facilitating mounting and demounting operation of the process cartridge. The partition is provided at such a position as is influenced by the gripping force during the handling, thus minimizing the deformation so that the blowing-out of the toner can be minimized.

The developer accommodating portion is formed by coupling an upper frame and a lower frame, and the partitions provided in the upper frame with a small gap between the partition member and the lower frame, and therefore, the coupling of the upper and lower framed are not influence. Additionally, the deformation of the developer accommodating portion is minimized during the mounting and demounting of the process cartridge, can be minimized so that the blowing out of the toner can be avoided.

While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.