Process cartridge and electrophotographic image forming apparatus

Abstract: The present invention provides a process cartridge which can be removably mounted on a body of an image forming apparatus, comprising an electrophotographic photosensitive drum, a process means acting on the electrophotographic photosensitive drum, a cartridge frame, and projection means for maintaining a posture of the process cartridge when the process cartridge is mounted on the body of the image forming apparatus, the projection means projecting outwardly from both side surfaces of the cartridge frame substantially in the same direction as an axis of the electrophotographic photosensitive drum and being positioned above the electrophotographic photosensitive drum when the process cartridge is mounted on the body of the image forming apparatus. The present invention further provides an electrophotographic image forming apparatus having such a process cartridge.

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a process cartridge and an electrophotographic image forming apparatus to which such a process cartridge can removably be mounted. The "electrophotographic image forming apparatus" is an image forming apparatus for forming an image on a recording medium by using an electrophotographic image forming system and may include, for example, an electrophotographic copying machine, an electrophotographic printer (such as a laser beam printer, LED printer and the like), an electrophotographic facsimile and an electrophotographic word processor. The "process cartridge" may incorporate therein an electrophotographic photosensitive member, and a charge means, a developing means or a cleaning means as a cartridge unit which can removably be mounted on an image forming apparatus, or may incorporate therein an electrophotographic photosensitive member, and at least one of a charge means, a developing means or a cleaning means as a cartridge unit which can removably be mounted on an image forming apparatus, or may incorporate therein an electrophotographic photosensitive member and at least a developing means as a cartridge unit which can removably be mounted on an image forming apparatus. Since the process cartridge can be mounted on and dismounted from the image forming apparatus by the operator himself, the maintenance of the apparatus can be facilitated. Related Background Art In image forming apparatuses using a process cartridge, it is necessary to regulate a position and a posture of a process cartridge in a body of the image forming apparatus. That is to say, a position of a photosensitive drum of the process cartridge must be correctly determined with respect to the body of the image forming apparatus. Thus, in general, cylindrical projections coaxial with a center line of the photosensitive drum are protruded from both side (end) surfaces of the process cartridge and the cylindrical projections are received in positioning grooves of guide structures formed in the body of the image forming apparatus, to thereby regulate the position of the process cartridge in the image forming apparatus. And, by abutting a regulating member provided on the body of the image forming apparatus against an upper portion of the process cartridge, the process cartridge is positioned in place (for example, see EP 520,802). This arrangement is very excellent in the point that the process cartridge can be positioned accurately with respect to the body of the image forming apparatus. A process cartridge having all the features recited in the preamble of claim 1 hereof is disclosed in each of European Patent Applications EP-A-0520802 and EP-A-0758105. As disclosed therein, projections each side of a cartridge frame provide means of regulating the posture of the cartridge while the cartridge is being mounted. These projections are located in relatively close proximity to the axis of the electrophotographic photosensitive drum carried in the cartridge. SUMMARY OF THE INVENTION An object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus in which the process cartridge can be positioned accurately with respect to the body of the image forming apparatus. Another object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus to which the process cartridge can removably be mounted, which has projecting members protruding from a cartridge frame in substantially the same direction as an axis of an electrophotographic photosensitive drum to abut against a fixed portion provided on a body of the image forming apparatus to regulate rotation of the process cartridge. The process cartridge of the present invention and which is set forth in claim 1 appended is characterised in that said projection members are positioned adjacent to a surface of the process cartridge which is an upper surface of said process cartridge when said process cartridge is mounted on said main body of the electrophotographic image forming apparatus. As set forth in claim 13 hereof there is also provided an electrophotographic image forming apparatus for forming an image on a recording medium, which apparatus comprises: an optical system responsive to image information to illuminate the electrophotographic photosensitive drum of a process cartridge; a mounting means for removably mounting the process cartridge; and a convey means for conveying the recording medium; characterised in that: said mounting means is capable of removably mounting the process cartridge of any of claims 1 to 12, and has for regulating the posture thereof respective posture regulating portions located so as to abut with the respective projection members of said process cartridge when it is mounted therein. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an elevational sectional view of an electrophotographic image forming apparatus according to an embodiment of the present invention; Fig. 2 is a perspective view of the image forming apparatus of Fig. 1; Fig. 3 is a sectional view of a process cartridge; Fig. 4 is a perspective view of the process cartridge of Fig. 3, viewed from the right upper side thereof; Fig. 5 is a right side view of the process cartridge of Fig. 3; Fig. 6 is a left side view of the process cartridge of Fig. 3; Fig. 7 is a perspective view of the process cartridge of Fig. 3, viewed from the left upper side thereof; Fig. 8 is a perspective view showing a left lower side of the process cartridge of Fig. 3; Fig. 9 is a perspective view showing a process cartridge mounting portion of the image forming apparatus; Fig. 10 is a perspective view showing a process cartridge mounting portion of the image forming apparatus, viewed from another direction; Fig. 11 is a perspective view of a cleaning unit; and Fig. 12 is a perspective view of a developing unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, an embodiment of the present invention will be explained with reference to the accompanying drawings. In the following explanation, a "width-wise direction" of a process cartridge B is referred to as a direction along which the process cartridge B is mounted on and dismounted from a body 14 of an image forming apparatus A and which coincides with a recording medium conveying direction. A "longitudinal direction" of the process cartridge B is referred to as a direction transverse to (substantially perpendicular to) the direction along which the process cartridge B is mounted on and dismounted from the body 14 of an image forming apparatus. This direction is parallel with a surface of the recording medium and is transverse to (substantially perpendicular to) the recording medium conveying direction. Further, "right" and "left" regarding the process cartridge are referred to as right and left sides of the recording medium conveying direction when the recording medium is viewed from the above. Fig. 1 is a structural view of an electrophotographic image forming apparatus (laser beam printer) to which the embodiment of the present invention is applied, Fig. 2 is a perspective view of the image forming apparatus, and Figs. 3 to 8 are views showing a process cartridge according to an embodiment of the present invention. In the following explanation, an "upper surface" of the process cartridge B is referred to as a surface facing to the above when the process cartridge B is mounted on the body 14 of the image forming apparatus, and a "lower surface" of the process cartridge is referred to as a surface facing to the below when the process cartridge is mounted on the image forming apparatus. (Electrophotographic Image Forming Apparatus and Process Cartridge B) A laser printer A shown in Figs. 1 and 2 serves to form an image on a recording medium (for example, a recording sheet, an OHP sheet, a cloth and the like) by using an electrophotographic image forming process. First of all, a toner image is formed on a drum-shaped electrophotographic photosensitive member (referred to as "photosensitive drum" hereinafter). More specifically, the photosensitive drum is charged by a charge means, then, a latent image corresponding to image information is formed on the photosensitive drum by illuminating laser light onto the photosensitive drum from an optical means in response to the image information, and then, the latent image is developed by a developing means to form a toner image. In synchronous with the formation of the toner image, the recording medium 2 is picked up from a sheet supply cassette 3a by a pick-up roller 3b, and the picked-up recording medium is conveyed by pairs of convey rollers 3c, 3d and a pair of regist rollers 3e. Then, the toner image formed on the photosensitive drum 7 of the process cartridge B is transferred onto the recording medium 2 by applying voltage to a transfer roller (transfer means) 4. The recording medium 2 to which the toner image was transferred is sent to a fixing means 5 through a convey guide 3f. The fixing means 5 comprises a drive roller 5c, and a fixing roller 5b including a heater 5a therein and serves to fix the toner image to the recording medium by applying heat and pressure. Thereafter, the recording medium 2 is conveyed through a reverse rotation path 3j by pairs of discharge rollers 3g, 3h, 3i to discharge the recording medium onto a discharge tray 6 formed on an upper surface of the body 14 of the image forming apparatus A. Incidentally, by operating a pivotal flapper 3k, the recording medium 2 can be discharged by a pair of discharge rollers 3m without passing through the reverse rotation path 3j. In the illustrated embodiment, a convey means 3 is constituted by the pick-up roller 3b, the pairs of convey rollers 3c, 3d, the pair of regist rollers 3e, the convey guide 3f, the pairs of discharge rollers 3g, 3h, 3i and the pair of discharge rollers 3m. As shown in Figs. 3 to 8, in the process cartridge B, the photosensitive drum 7 is rotated and the surface of the photosensitive drum is uniformly charged by applying voltage to a charge roller (charge means) 8. Then, laser beam light emitted from an optical system 1 in response to image information is illuminated onto the photosensitive drum 7 through an exposure opening portion 1e to form a latent image, and the latent image is developed by a developing means 9 with toner. The charge roller 8 is contacted with the photosensitive drum 7 to charge the latter and is rotatingly driven by rotation of the photosensitive drum 7. The developing means 9 supplies the toner to a developing area of the photosensitive drum 7 to develop the latent image formed on the photosensitive drum 7. The optical system 1 has an optical case 1f containing a laser diode 1a, a polygon mirror 1b, a lens 1c and a reflection mirror 1d, which optical case 1f is attached to the body 14 of the image forming apparatus. In the developing means 9, the toner contained in a toner container 11A is sent to a developing roller 9c by rotating a toner feed member 9b. The developing roller 9c having a fixed magnet therein is rotated, and a toner layer is formed on the developing roller 9c and is frictionally charged by a developing blade 9d. The toner is supplied from the toner layer to the developing area of the photosensitive drum 7, so that the latent image is visualized as the toner image by transferring the toner onto the photosensitive drum 7 in accordance with the latent image. The developing blade 9d serves to regulate a thickness of the toner layer on the developing roller 9c and apply the frictional charges to the toner. In the vicinity of the developing roller 9c, a toner agitating member 9e for circulating the toner in a developing chamber is provided. After the toner image formed on the photosensitive drum 7 is transferred to the recording medium 2 by applying voltage having polarity opposite to that of the toner image, residual toner remaining on the photosensitive drum 7 is removed by a cleaning means 10. In the cleaning means 10, the residual toner remaining on the photosensitive drum 7 is scraped from the photosensitive drum by an elastic cleaning blade 10a urged against the photosensitive drum 7, and the scraped toner is collected into a waste toner reservoir 10b. The process cartridge B includes a toner frame 11 having the toner container (toner containing portion) llA containing the toner, a developing frame 12 holding the developing means 9 including the developing roller 9c and the like, and a cleaning frame 13 to which the photosensitive drum 7, cleaning means (cleaning blade 10a and the like) and charge roller 8 are attached. These frames are joined to each other. The exposure opening portion le through which the light corresponding to the image information is illuminated on the photosensitive drum 7, and a transfer opening portion 13n through which the photosensitive drum 7 is faced to the recording medium 2 are formed in the process cartridge B. The exposure opening portion 1e is formed in the cleaning frame 13 and the transfer opening portion 13n is defined between the developing frame 12 and the cleaning frame 13. The process cartridge can be mounted on and dismounted from the body 14 of the image forming apparatus by the operator. Next, a housing structure of the process cartridge B according to the illustrated embodiment will be described. (Housing Structure of Process Cartridge B) As mentioned above, the process cartridge B includes the toner frame 11, developing frame 12 and cleaning frame 13 which are joined to each other to form a housing which will be described hereinbelow. As shown in Fig. 3, the toner feed member 9b is rotatably attached to the toner frame 11, and the developing roller 9c and the developing blade 9d are attached to the developing frame 12 and the toner agitating member 9e for circulating the toner in the developing chamber is rotatably provided in the vicinity of the developing roller 9c. An antenna rod 9h extending substantially in parallel with the developing roller 9c is provided in an opposed relation to the developing roller 9c. The toner frame 11 and the developing frame 12 are welded (by ultrasonic welding in the illustrated embodiment) to each other to form a developing unit D (Fig. 12) as a second frame. As shown in Figs. 3 and 11, the photosensitive drum 7, charge roller 8 and cleaning means 10 are attached to the cleaning frame 13 to form a cleaning unit C (Fig. 11) as a first frame. The process cartridge B is formed by rotatably interconnecting the developing unit D and the cleaning unit C by connecting members (pins) 22. Specifically, as shown in Fig. 12, circular pivot holes 20 (extending in parallel with the developing roller 9c) are formed in tip end portions 19a of arm portions 19 provided on both longitudinal ends of the developing frame 12 (along a longitudinal direction of the developing roller 9c). On the other hand, recessed portions 21 for receiving the arm portions 19 are formed in both longitudinal end portions of the cleaning frame 13 (see Fig. 11). By inserting the arm portions 19 into the recessed portions 21 and press-fitting the connection members 22 into attachment holes 13e of the cleaning frame 13 into the pivot holes 20 of the tip end portions of the arm portions 19, the developing unit D and the cleaning unit C are interconnected for pivotal movement around the connection members 22. In this case, compression coil springs 22a fitted on pins (not shown) formed on root portions of the arm portions 19 abut against upper surfaces of the recessed portions 21 of the cleaning frame 13 to bias the developing frame 12 downwardly, to thereby positively urge the developing roller 9c against the photosensitive drum 7. The upper surfaces of the recessed portions 21 of the cleaning frame 13 are inclined so that the compression coil springs 22a are gradually compressed from a non-compressed condition when the developing unit D is assembled with the cleaning unit C. Hence, as shown in Fig. 12, by providing spacer rollers 9i each having a diameter greater than that of the developing roller 9c at both longitudinal ends of the developing roller 9c, the spacer rollers 9i are urged against the photosensitive drum 7, so that the developing roller 9c is opposed to the photosensitive drum with a predetermined gap (about 300 µm) therebetween. In this way, the developing unit D and the cleaning unit C can be pivoted relative to each other around the connection members 22, and a positional relation between the peripheral surfaces of the photosensitive drum 7 and the developing roller 9c can be maintained by the compression coil springs 22a. Since the developing frame 12 has the compression coil springs 22a provided at the root portions of the arm portions 19, the spring forces of the compression coil springs 22a do not act on any portions other than the root portions. Thus, even if spring seats for the compression coil springs are not particularly reinforced (for example, by providing spring seat members at the root portions), accuracy can be ensured sufficiently because the root portions of the arm portions 19 have great strength and great rigidity. As shown in Fig. 3, a cover portion 13u extending up to over the toner frame 11 to cover a part of the toner frame 11 and an upper portion of the developing frame 12, is provided on an upper surface of the cleaning frame 13. The cover portion 13u has a longitudinal upper wall, and side walls 13ul suspended from both longitudinal ends of the upper wall in parallel with the plane of Fig. 3. A tip end of the cover portion 13u extending up to over the toner frame 11 is positioned upwardly of the photosensitive drum 7 near the developing unit D. (Drive Mechanism for Process Cartridge) The photosensitive drum 7 is provided at its both ends with drum flanges (not shown) and is rotatably supported by the cleaning frame 13 (also referred to as "drum frame" hereinafter). The photosensitive drum 7 is engaged by a drum gear 7b (Fig. 8) integrally formed with one of the drum flanges and a developing roller gear (not shown) secured to the end of the developing roller 9c. The developing roller gear is meshed with a gear (not shown) for transmitting rotation to the toner feed member 9b and the toner agitating member 9e. A coupling projection shaft 37 is integrally provided on the drum flange having the drum gear 7b, and the projecting shaft 37 is rotatably supported in a bearing integral with a right guide member 13R. A coupling projection 37a formed on a tip end of the coupling projecting shaft 37 is positioned within a cylindrical guide 13aR in a longitudinal direction. The coupling projection 37a has a triangular column shape twisted in an axial direction. There is provided a coupling recessed shaft 39b having a center same as a center of a positioning groove 16d of a guide member 16R of the apparatus body 14 shown in Fig. 10 and shiftable between a position where the coupling recessed shaft projecting into the positioning groove 16d and a position where the coupling recessed shaft is retracted from the positioning groove 16d. The coupling recessed shaft 39b is positioned at the side of the apparatus body 14 and is connected to a rotation drive source via a power transmitting member. That is to say, the coupling recessed shaft 39b is positioned in coaxial with a gear G. The coupling recessed shaft 39b is provided at its end face with a coupling recessed portion 39a having a triangular bore shape twisted in the axial direction. The coupling recessed portion 39a can be engaged with the coupling projection 37a of the process cartridge B, so that, upon engagement, these elements are pulled toward each other because these elements are twisted in the same direction. Further, since these elements 39a, 37a have substantially regular triangular shapes each having a rotational center, when they are rotated, self-centering is achieved. The process cartridge according to the illustrated embodiment has the following construction. That is to say, the process cartridge is detachably mountable to a main assembly of the image forming apparatus, wherein the main assembly includes a motor (not shown), a main assembly side gear G for receiving a driving force from the motor and a hole 39a defined by twisted surfaces, the hole being substantially coaxial with the gear G, and the process cartridge comprises an electrophotographic photosensitive drum 7, process means 8, 9, 10 actable on the photosensitive drum 7, and a twisted projection 37a engageable with the twisted surfaces, the projection being provided at a longitudinal end of the photosensitive drum 7, wherein when the main assembly side gear G rotates with the hole 39a and projection 37a engaged with each other, rotational driving force is transmitted from the gear G to the photosensitive drum 7 through engagement between the hole 39a and the projection 37a. When the process cartridge B is mounted on the body 14 of the image forming apparatus, an opening/closing member 35 is opened around a fulcrum 35a shown in Fig. 1. In this regard, there is provided an engagement/disengagement device (not shown) of shaft coupling type for cooperating the opening/closing member 35 with the coupling recessed shaft 39b. Thus, when the opening/closing member 35 is opened, the coupling recessed shaft 39b is retarded from the positioning groove 16d to disengage the coupling recessed portion (hole) 39a from the coupling projection 37a in the axial direction. Whereas, when the opening/closing member 35 is closed, the coupling recessed shaft 39b projects into the positioning groove 16d to engage the coupling recessed portion 39a with the coupling projection 37a. Accordingly, in a condition that the process cartridge B is mounted on the body 14 of the image forming apparatus, when the coupling recessed shaft 39b is driven by the drive source of the apparatus body 14 and the photosensitive drum 7 is driven through the coupling projecting shaft 37, as shown in Fig. 3, the photosensitive drum 7 is rotated in a direction shown by the arrow Y, to thereby act moment in a Z direction on the process cartridge B. In the illustrated embodiment, while an example that the photosensitive drum 7 is driven through the shaft coupling was explained, even in a case where a drive gear (not shown) connected to the drive source of the apparatus body 14 and positioned below (above in Fig. 8) the drum gear 7b of Fig. 8 is engaged by the drum gear 7b, when the driving force is applied to the photosensitive drum 7 in Fig. 3, the Z direction moment acts on the photosensitive drum. Thus, the present invention can also be applied to the case where the drive gear is engaged by the drum gear 7b. (Mounting Structure of Process Cartridge to Image Forming Apparatus) Next, a guide means for guiding the process cartridge when the process cartridge is mounted on the apparatus body 14 and a positioning means for determining position and posture of the process cartridge after the process cartridge was mounted on the apparatus body 14 will be explained. As shown in Figs. 5, 6 and 7, in the process cartridge B, the cleaning frame 13 is provided at its both outer side surfaces with cylindrical guides (positioning guide means) 13aR, 13aL for guiding the process cartridge when the process cartridge is mounted on the body 14 of the image forming apparatus, and turn hampering guides (posture holding guide means) 13bR, 13bL. Further, there are provided regulating projections (posture regulating portions) 13iR, 13jL as positioning means when the process cartridge is mounted on the body 14 of the image forming apparatus. The position of the process cartridge B is regulated by the cylindrical guides 13aR, 13aL when the process cartridge is mounted on the apparatus body 14. As shown in Fig. 5, the cylindrical guide 13aR is a cylindrical hollow member having an integral attachment flange 13aR1, and the turn hampering guide 13bR is formed integrally with the cylindrical guide 13aR and projects radially from the outer surface of the cylindrical guide. The right guide member 13 having such cylindrical guide 13aR, turn hampering guide 13bR and attachment flange 13aR1 is secured to the cleaning frame 13 by threading small screws 13aR2 into the cleaning frame through holes formed in the attachment flange 13aR1. As shown in Fig. 6, the cylindrical guide 13aL is protruded outwardly (this side of the plane of Fig. 6) from a flat flange 29 fitted on a positioning pin c protruded from the side surface of the cleaning frame 13 and secured to the cleaning frame 13 by small screws 13d. The flange 29 is provided at its inner surface with a fixed drum shaft for rotatably supporting a spur wheel 7n integrally formed with a flange fitted in the photosensitive drum 7. The cylindrical guide 13aL is positioned in coaxial with the drum shaft. As shown in Fig. 6, the elongated turn hampering guide 13bL slightly spaced apart from the cylindrical guide 13aL and extending substantially radially of the cylindrical guide 13aL is formed integrally with the cleaning frame 13 to protrude laterally from the cleaning frame. A portion of the flange 29 which interferes with the turn hampering guide 13bL is cut away, and the lateral protruding height of the flange is substantially the same as that of the turn hampering guide 13bL. The turn hampering guide 13bL extends toward a side surface of a developing roller bearing box 9v secured to the developing frame 12. In this way, the left guide member 13L has the metallic cylindrical guide 13aL and the synthetic resin turn hampering guide 13bL as different members. As shown in Figs. 4 to 7, the regulating projections 13jR, 13jL are cylindrical hollow members formed integrally with the cleaning frame 13 to protrude outwardly from the outer side surfaces of the cleaning frame in the longitudinal direction. The regulating projections 13jR, 13jL are positioned in the side walls 13ul of the cover portion. Center lines of the regulating projections 13jR, 13jL coincide with each other and are substantially parallel with the center line of the photosensitive drum 7, but are sufficiently spaced apart from the center line of the photosensitive drum. In the illustrated embodiment, a distance between the center of the photosensitive drum and the center of each regulating projection 13jR or 13jL is selected to about 75 mm. Lengths of the regulating projections 13jR, 13jL are smaller than those of the cylindrical guides 13aR, 13aL, and, thus, longitudinal free ends of the regulating projections 13jR, 13jL are protruded as the same as or smaller than those of the cylindrical guides 13aR, 13aL. Since the regulating projections 13jR, 13jL and the cylindrical guides 13aR, 13aL are provided on the cleaning frame 13 which is formed from the same material as these elements, the loads acting on the regulating projections 13jR, 13jL and the cylindrical guides 13aR, 13aL are supported by the cleaning frame 13 and do not affect an influence upon other members. The regulating projections 13jR, 13jL project from both side surfaces of the cleaning frame 13 in directions substantially parallel with the axis of the photosensitive drum 7 and are positioned above the photosensitive drum when the process cartridge is mounted on the body of the image forming apparatus. The body 14 of the image forming apparatus is provided at its inner walls with a left guide member 16L (positioned at the left regarding the inserting direction X of the process cartridge B, in Fig. 9) and a right guide member 16R (positioned at the right regarding the inserting direction X of the process cartridge B, in Fig. 10). The guide members 16L, 16R include, respectively, guide grooves 16a, 16c inclined downwardly along the inserting direction X of the process cartridge B, semicircular positioning recesses 16b, 16d contiguous to the guide grooves 16a, 16c to receive the cylindrical guides 13aL, 13aR of the process cartridge B, and posture regulating receiving portions 16e, 16f positioned above the guide grooves. Centers of the positioning recesses 16b, 16d are aligned with the centers of the cylindrical guides 13aL, 13aR of the process cartridge B and accordingly the center of the photosensitive drum 7 when the process cartridge B is mounted on the body 14 of the image forming apparatus. The posture regulating receiving portions 16e, 16f are provided in upper surfaces of upper walls defining the guide grooves 16a, 16c, and introduction portions 16el, 16fl for introducing the regulating projections 13jL, 13jR into the posture regulating receiving portions 16e, 16f are provided in front of the posture regulating receiving portions 16e, 16f. Widths of the guide grooves 16a, 16c in the inserting direction of the process cartridge B are selected such that the cylindrical guides 13aL, 13aR are loosely received. Although the turn hampering guides 13bL, 13bR having widths smaller than diameters of the cylindrical guides 13aL, 13aR are loosely fitted, rotations of the cylindrical guides 13aL, 13aR and the turn hampering guides 13bL, 13bR are regulated by the guide grooves 16a, 16c, to thereby maintain the posture of the process cartridge B within a predetermined range. When the process cartridge B is mounted, the cylindrical guides 13aL, 13aR advance through the guide grooves 16a, 16c. As the process cartridge approaches the positioning recesses 16b, 16d, the regulating projections 13iL, 13iR abut against the introduction portions 16e1, 16f1 in front of the posture regulating receiving portions 16e, 16f and rides over ridges between the introduction portions 16e1, 16f1 and the posture regulating receiving portions 16e, 16f and then contact with the posture regulating receiving portions 16e, 16f. Then, while the regulating projections 13iL, 13jR are descending along the inclined surfaces of the posture regulating receiving portions 16e, 16f, the cylindrical guides 13aL, 13aR enter into and abut against the positioning recesses 16b, 16d. That is to say, in a condition that the process cartridge B is mounted on the body 14 of the image forming apparatus, the cylindrical guides 13aL, 13aR of the process cartridge B are fitted into the positioning recesses 16b, 16d of the guide members 16L, 16R, and the regulating projections 13jL, 13jR provided on the outer surfaces of the cleaning frame 13 of the process cartridge B abut against the posture regulating receiving portions 16e, 16f of the guide members 16L, 16R of the apparatus body 14. This is the reason that, in the process cartridge B, when a center line connecting between the centers of the cylindrical guides 13aR, 13aL is maintained horizontally, regarding the cleaning unit C side and the developing unit D side on both sides of said center line, greater primary moment is generated in the developing unit D side than the cleaning unit C side. When the image forming apparats A is driven, since the photosensitive drum 7 is rotated in the direction Y in Fig. 3, the process cartridge B is subjected to the moment in the Z direction. Thus, the regulating projections 13jL, 13jR continue to abut against the posture regulating receiving portions 16e, 16f of the guide members 16L, 16R of the body 14 of the image forming apparatus, so that the posture of the process cartridge B is maintained in the same condition as that before the image forming apparatus is driven. By regulating the posture of the process cartridge B within the body 14 of the image forming apparatus in this way, since any members for regulating the posture of the process cartridge are not required to provide in the cartridge mounting space S and the process cartridge is not required to be urged against such regulating members, as shown in Fig. 1, the process cartridge B can be approached to the optical case lf, to thereby save the space accordingly. Since the regulating projections 13jR, 13jL are not longer than the cylindrical guides 13aR, 13aL of the process cartridge B in the longitudinal direction, the dimension of the apparatus body 14 is not required to be greater in the longitudinal direction. Specifically, in comparison with the conventional technique in which an upper part of the cleaning unit C is pressed by a member, since a space above the process cartridge B is not required (in the illustrated embodiment, since a space between the optical system 1 and the process cartridge B is not required (see Fig. 1), the height of the body 14 of the image forming apparatus can be reduced accordingly, to thereby make the apparatus body 14 compact. Since the regulating projections 13jL, 13jR are situated on the side walls 13ul of the cover portion 13u of the cleaning frame 13 in a sufficiently spaced relation (about 75 mm) to the center of the photosensitive drum, even if the regulating projections 13jL, 13jR and/or the posture regulating receiving portions 16e, 16f of the apparatus body 14 have positional deviation, such positional deviation does not affect a bad influence upon the posture of the process cartridge B. The distance between the center of the photosensitive drum 7 and the centers of the regulating projections 13jL, 13jR may be longer as much as possible. For example, when such distance is about 60 mm, if the positions of the regulating projections 13jL, 13jR are deviated by 1 mm in the rotational direction of the process cartridge B, the posture of the process cartridge will be changed by 1 degree. However, since the manufacturing error of the process cartridge effected by the molding operation is in the order of millimeter (0.1 mm or less), the posture of the process cartridge B is kept substantially constant. The posture regulating receiving portions 16e, 16f of the apparatus body 14 include inclined surfaces against which the regulating projections 13jL, 13jR of the process cartridge B abut, and such inclined surfaces are inclined in the same direction as the guide grooves 13a, 13c in parallel with the guide grooves 13a, 13c or with greater inclination than the guide grooves 13a, 13c. When the inclinations of the regulating projections 13jL, 13jR are greater than those of the guide grooves 13a, 13c, "click" feeling can be obtained when the process cartridge B is mounted on or dismounted from the body 14 of the image forming apparatus. Each posture regulating receiving portion 16e, 16f is defined by one surface of the illustrated corresponding V-shaped groove, i.e., by a front surface viewed from the inserting direction X of the process cartridge B. Thus, in the condition that the process cartridge B is mounted on the body 14 of the image forming apparatus, generatrices of the regulating projections 13jL, 13jR of the process cartridge B are contacted with the front surfaces (viewed from the inserting direction X of the process cartridge B) of the V-shaped grooves, and the outer peripheral surfaces of the cylindrical guides 13aL, 13aR of the process cartridge B abut against the inner peripheral surfaces of the positioning recesses 16b, 16d of the guide members 16L, 16R of the apparatus body 14. Incidentally, in the illustrated embodiment, although the posture regulating receiving portions 16e, 16f provided in the guide members 16L, 16R of the apparatus body 14 are flat, such portions may have secondary curved surfaces such as concave or convex are having a longitudinal axis. Further, the posture regulating portions of the process cartridge B are not limited to the cylindrical projections. As mentioned above, according to the illustrated embodiment, the process cartridge detachably mountable to the body of the image forming apparatus comprises the electrophotographic photosensitive member, the process means acting on the electrophotographic photosensitive member, and the cartridge frame including the electrophotographic photosensitive member and the process means therein and having the guides for detachably mounting the process cartridge to the body of the image forming apparatus. The guides include the positioning guides coaxial with the electrophotographic photosensitive member, the turn hampering guides cooperating with the positioning guides to maintain the posture of the process cartridge when the process cartridge is mounted on the body of the image forming apparatus, and the posture regulating portions for abutting against the members of the apparatus body to keep the mounting condition of the process cartridge constant by cooperation with the positioning guides in the condition that the process cartridge is mounted on the body of the image forming apparatus. The posture regulating portions have the projections protruding from both side surfaces of the cartridge frame in the same direction as the axial direction of the electrophotographic photosensitive member and disposed above the electrophotographic photosensitive member at the heavier side of the cartridge frame regarding the center of the electrophotographic photosensitive member. With this arrangement, since it is not required that any posture regulating members should not abut against the process cartridge, the space for such posture regulating members can be saved, to thereby make the apparatus compact. In the above illustrated embodiment, since the posture of the process cartridge is regulated by the projections provided on side surfaces of the frame of the process cartridge, the regulation of the posture of the process cartridge does not affect an influence upon the cleaning ability. As a result, since the rigidity of the cleaning frame 13 near the toner reservoir 10b may be not so great, the thickness of the cleaning frame can be reduced. Since the posture regulating portions are disposed above the electrophotographic photosensitive member at the position spaced apart from the electrophotographic photosensitive member by 60 mm or more, the positional accuracy of the posture regulating portions does almost not affect an influence upon the posture of the process cartridge. In the illustrated embodiment, since the cartridge frame is formed by interconnecting the plurality of frames and the posture regulating portions are provided on the frame supporting the electrophotographic photosensitive member and having the positioning guides, the positional relation between the positioning guides and the posture regulating portions can easily be determined with high accuracy. Since the posture regulating portions are formed integrally with the cartridge frame, there is no assembling error. In the illustrated embodiment, since the frame including the posture regulating portions is the cleaning frame having the electrophotographic photosensitive member, the charge means for charging the electrophotographic photosensitive member and the cleaning means for removing the residual toner remaining on the electrophotographic photosensitive member after the transferring, the posture regulating portions are not provided on other frame. Thus, since only the dimension of the cleaning frame may be controlled, the dimensions of other members may not be controlled. In the illustrated embodiment, the cleaning frame is pivotally connected to the developing frame of the developing unit formed by integrally joining the toner frame containing the toner to the developing frame supporting the developing member, and the cover portion having the spring seats for supporting, between the developing frame and the cover portion, the springs for applying the urging force between the electrophotograhic photosensitive member and the developing member extends toward the developing frame, and the posture regulating portions are provided on the tip end of the cover portion. With this arrangement, both the positioning guides and the posture regulating portions can be arranged in the same frame and the distance between the positioning guides and the posture regulating portions can be increased. Further, the loads acting on the positioning guides and the posture regulating portions can be reduced, and, since these elements are formed in the same frame, the loads do not affect an influence upon other elements. In the illustrated embodiment, since the posture regulating portions comprise the cylindrical members having the center lines parallel with the axis of the electrophotographic photosensitive member, the insertion and removal of the posture regulating portions of the process cartridge can be smoothly effected with respect to the posture regulating receiving portions of the body of the image forming apparatus. Since the posture regulating portions are shorter than the positioning guides and the turn hampering guides, the longitudinal dimension of the process cartridge can be reduced. Since the posture regulating portions are situated so that the surface thereof which abut against the body of the image forming apparatus when the process cartridge is mounted on the body of the image forming apparatus are positioned above the space in front of the turn hampering guides, the provision of the posture regulating receiving portions of the body of the image forming apparatus can be made easier. In the image forming apparatus according to the illustrated embodiment, since the mounting means for removably mounting the process cartridge comprises the groove-shaped guide portions for loosely receiving the positioning guides and the turn hampering guides, the positioning recesses provided in the ends of the guide portions and adapted to receive the positioning guides, and the posture regulating receiving portions which are formed in the upper parts of the guide portions and against which the posture regulating portions of the process cartridge abut, the posture regulating receiving portions can easily receive the posture regulating portions of the process cartridge when the process cartridge is mounted on the image forming apparatus. That is to say, merely by inserting the positioning guides and turn hampering guides of the process cartridge into the guide portions of the apparatus body, the positioning guides of the process cartridge are aligned with the positioning recesses of the apparatus body, and the posture regulating portions of the process cartridge abut against the posture regulating receiving portions of the apparatus body, to thereby facilitate the mounting and dismounting of the process cartridge with respect to the body of the image forming apparatus. In the illustrated embodiment, since the posture regulating receiving portions of the apparatus body are positioned between the entrance of the cartridge mounting portion and the positioning recesses, the member in which the posture regulating receiving portions are formed can be formed integrally with the guide members for guiding the process cartridge. Since the guide portions are inclined downwardly from the entrance of the cartridge mounting portion and the surfaces of the posture regulating receiving portions of the apparatus body with which the posture regulating portions of the cartridge frame are contacted are inclined in the same direction as the guide portions and greatly more than the guide portions, the "click" feeling can be obtained when the process cartridge is mounted on and dismounted from the body of the image forming apparatus, so that the mounting and dismounting of the process cartridge can be ascertained by the click feeling. As mentioned above, according to the present invention, the process cartridge can be mounted on the body of the image forming apparatus with high accuracy.

Claims: A process cartridge (B) removably mountable on a body (14) of an electrophotographic image forming apparatus, said process cartridge comprising: an electrophotographic photosensitive drum (7) rotatable about an axis; process means (8-10) actable on said electrophotographic photosensitive drum; a cartridge frame (11-13); cylindrical guides (13aL, 13aR), extending coaxially from opposite sides of the cartridge frame to define a rotation axis parallel to the axis of the photosensitive drum (7), the guides (13aL, 13aR) being receivable in recesses (16b, 16d) in the main assembly to support the cartridge in a mounted position relative to the main assembly; and respective projection members (13jR, 13jL) projecting outwardly from respective opposite side surfaces of said cartridge frame and substantially in the same direction as the axis of said electrophotographic photosensitive drum; which process cartridge is characterised in that : said respective projection members (13jR, 13jL) are engageable with abutment surfaces (16e, 16f) of the body (14) of the image-forming apparatus to prevent the process cartridge, when the process cartridge is in the mounted position mounted on said body of the image forming apparatus, from rotating about said rotation axis with said drum (7) when said electrophotographic photosensitive drum (7) is rotated; said projection members (13jR, 13jL) are positioned relative to said cartridge frame so as to be above said electrophotographic photosensitive drum and adjacent to an upper surface of said process cartridge when said process cartridge is in said mounted position, and said projection members (13jR, 13jL) being positioned at the heavier side of said process cartridge (B) relative to said rotation axis. A process cartridge according to claim 1, wherein said cartridge frame (11-13) is constituted by a plurality of frame portions (11,12,13) that are joined together, said projection members (13jR, 13jL) are provided on a frame portion (13) supporting said electrophotographic photosensitive drum (7), and said cartridge frame is provided with positioning guide means (13aR, 13aL). A process cartridge according to claim 2, wherein said projection members (13jR, 13jL) are integral with said frame portion (13) supporting said electrophotographic photosensitive drum (7) and are made of plastics material. A process cartridge according to claim 2, wherein said frame portion (13) on which said projection members (13jR, 13jL) are provided further supports a charge member (8) for charging said electrophotographic photosensitive drum (7) and a cleaning member (10a) for removing residual toner remaining on said electrophotographic photosensitive drum (7). A process cartridge according to claim 4, wherein said frame portion (13) on which said projection members (13jR, 13jL) are provided is joined to a developing unit (D) formed by integrally joining a toner frame (11) containing toner to a developing frame (12) supporting a developing member (9c), and a cover portion (13u) having spring seats for supporting, between said developing frame (12) and said cover portion (13u), springs (22a) for applying urging forces between said electrophotographic photosensitive drum (7) and said developing member (9c) extends toward said developing frame (12), and said projection members (13jR, 13jL) are provided each on a respective tip end (19a) of said cover portion (13u). A process cartridge according to any preceding claim, wherein said projection members (13jR, 13jL) are cylindrical members having centre lines parallel with the axis of said electrophotographic photosensitive drum (7). A process cartridge according to any preceding claim, wherein said projection members (13jR, 13jL) have outer ends positioned inwardly of outer ends of positioning guides (13aR, 13aL) and turn hampering guides (13bR, 13bL). A process cartridge according to any preceding claim, wherein said projection members (13jR, 13jL) are positioned so that their surfaces abut against the body (14) of the image forming apparatus and positioned above a space in front of said turn hampering guides (13bR, 13bL), when the process cartridge (B) is mounted on the body (14) of the image forming apparatus. A process cartridge according to claim 1, wherein said process means (8-10) comprises at least one of a charge member (8) for charging said electrophotographic photosensitive drum (7), a developing member (9) for developing a latent image formed on said electrophotographic photosensitive drum (7), and a cleaning member (10) for removing residual toner remaining on said electrophotographic photosensitive drum (7). A process cartridge according to any one of claims 1 to 9, wherein said projection members (13jR, 13jL) are aligned. A process cartridge according to any one of claims 1 to 10, wherein said projection members (13jR, 13jL) are co-axial. An electrophotographic image forming apparatus (A) for forming an image on a recording medium (2), which apparatus comprises: an optical system (1) responsive to image information to illuminate the electrophotographic photosensitive drum (7) of a process cartridge (B); a mounting means (16R, 16L) for removably mounting the process cartridge (B); and a conveyor means (3) for conveying a recording medium (2); characterised in that : said mounting means (16R, 16L) is capable of removably mounting the process cartridge (B) of any of claims 1 to 12, and has respective recesses (16b, 16d) for receiving cylindrical guides (13aR, 13aL) of the cartridge, and for regulating the posture thereof respective posture regulating portions (16f, 16e) for regulating the posture thereof located so as to abut with the respective projection members (13jR, 13jL) of said process cartridge (B) when it is mounted therein. An electrophotographic image forming apparatus (A) according to claim 12 for removably mounting the process cartridge of claim 1, and which process cartridge (B) is provided with positioning guides (13aR, 13aL) and turn hampering guides (13bR, 13bL), wherein said mounting means (16R, 16L) comprises groove-shaped guide portions (16c) for loosely receiving the positioning guides (13aR, 13aL) and the turn hampering guides (13bR, 13bL) of the process cartridge (B), and positioning recesses (16d, 16b) provided in tip ends of said guide portions (16c) to receive the positioning guides (13aR, 13aL); said respective posture regulating portions (16f, 16e) being located above said guide portions (16c) and distally spaced from said positioning recesses (16d, 16b) so as to abut with the projection members (13jR, 13jL) of the process cartridge (B) when it is removably mounted with the positioning guides (13aR, 13aL) received in said positioning recesses (16d, 16b). An electrophotographic image forming apparatus according to claim 13, wherein said posture regulating portion (16f, 16e) are positioned between the entrance of said mounting means (16) and said positioning recesses (16d, 16b). An electrophotographic image forming apparatus according to either of claims 13 or 14, wherein said guide portions (16c) are inclined downwardly from the entrance of said mounting means (16), and the surfaces of said posture regulating portions (16f, 16e) of the body (14) of the image forming apparatus (A) with which said projection members (13jR, 13jL) of the process cartridge (B) are to abut are inclined at a greater downwards inclination in the same direction as said guide portions. The combination of an electrophotographic image forming apparatus (A) according to any of claims 12 to 15, and the process cartridge (B) of any of claims 1 to 11 removably mounted therein.

Inventors: TAKASHI AKUTSU, TAKASHI, AKUTSU
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1997
Main classification: G03G21
IPC codes: G03G21