HK1181471B - Process cartridge and electrophotographic image forming apparatus - Google Patents

Description

Process cartridge and electrophotographic image forming apparatus

The present application is a divisional application of an invention patent application entitled "process cartridge and electrophotographic image forming apparatus", having an international application date of 30/6/2008, international application number of PCT/JP2008/062251, national application number of 200880021696.9.

Technical Field

The present invention relates to a process cartridge composed of an electrophotographic photosensitive drum and a developing roller (which processes the photosensitive drum), and particularly to a process cartridge whose electrophotographic photosensitive drum and developing roller can be disposed in contact with each other or separated from each other. The present invention also relates to an electrophotographic image forming apparatus employing the above process cartridge.

Background

In recent years, a process cartridge system has come to be widely used in the technical field of image forming apparatuses using an electrophotographic image forming method. The process cartridge system is one of electrophotographic image forming systems. It uses a cartridge in which an electrophotographic photosensitive drum and a developing roller (i.e., a roller for processing the electrophotographic photosensitive drum) are integrally provided so that they can be removably mounted in the main assembly of an image forming apparatus. Thus, the use of the process cartridge system makes it possible for a user to maintain the electrophotographic image forming apparatus without relying on a service person. This is also the reason why the process cartridge system has started to be widely used in the electrophotographic image forming apparatus technical field.

The process cartridge is structured such that its developing roller is kept pressed against its electrophotographic photosensitive drum by applying a preset amount of pressure to keep the developing roller in contact with the photosensitive drum at the time of image formation. In a so-called contact development method (i.e., a development method in which a development roller is placed in contact with a photosensitive drum to develop a latent image on the photosensitive drum), an elastic layer of the development roller is kept pressed against the peripheral surface of the photosensitive drum, thereby maintaining a preset amount of contact pressure between the peripheral surface of the development roller and the peripheral surface of the photosensitive drum.

Therefore, if the process cartridge is left unused for a long time in the main assembly of the image forming apparatus, the elastic layer of the developing roller is sometimes deformed. Thus, if the image forming apparatus is used for the first time after the process cartridge has been left unused for a long time, there is a possibility that the latent image will be developed unevenly. Further, in the case of a so-called contact development method, the developing roller contacts the photosensitive drum during development. Therefore, the developer is sometimes transferred from the developing roller to the position of the peripheral surface of the photosensitive drum (the developer should not adhere thereto). Further, the photosensitive drum and the developing roller rotate in contact with each other not only during development but also during other processes other than development. Therefore, the so-called contact development method exacerbates the deterioration of the photosensitive drum, the developing roller, and the developer.

One solution to the above problem is proposed in japanese laid-open patent application No. 2003-167499. According to this patent application, an image forming apparatus is provided with a mechanism for acting on a process cartridge to separate an electrophotographic photosensitive drum and a developing roller from each other when an image is not actually formed (patent document 1).

In the case of the image forming apparatus proposed in patent document 1, the structure of its main assembly is such that four process cartridges are removably mountable in the main assembly. Each cartridge is composed of a photosensitive member unit and a developing unit. The photosensitive member unit has a photosensitive member. The developing unit supports the developing roller and is connected to the photosensitive member unit such that it is rotationally movable relative to the photosensitive member unit. Further, the main assembly of the image forming apparatus is provided with a separation sheet, and the process cartridge is provided with a force receiving portion. As the separation sheet moves, the force receiving portion receives a force from the separation sheet, causing the developing unit to move relative to the photosensitive member unit. As a result, the developing roller in contact with the photosensitive drum is separated from the photosensitive drum.

According to the related art, a force receiving portion (i.e., a portion that receives a force for separating the developing roller and the photosensitive member from each other) remains protruding from an outer contour of the developing unit. Therefore, the force receiving portion is easily damaged when the process cartridge is operated by a user or when the process cartridge is carried separately. Further, the presence of the above-described force receiving portion has been one of the main problems to be faced when there is an effort to reduce the size of a process cartridge having a structure in which an electrophotographic photosensitive member and a developing roller can be placed in contact with or separated from each other, and to reduce the size of an image forming apparatus main assembly in which such a process cartridge can be removably mounted.

Disclosure of Invention

A primary object of the present invention is to provide a process cartridge, of which an electrophotographic photosensitive drum and a developing roller can be disposed in contact with or separated from each other, and which is significantly smaller in size than the process cartridge according to the related art; and to provide an electrophotographic image forming apparatus in which a process cartridge according to the present invention is removably mountable.

Another object of the present invention is to provide a process cartridge of which the force receiving portion is significantly less likely to be damaged when the process cartridge is transported alone, as compared with the process cartridge of the related art.

According to one aspect of the present invention, there is provided a process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum; a drum frame supporting the electrophotographic photosensitive drum; a developing frame supporting the developing roller, the developing roller being movable relative to the drum frame between a contact position in which the developing roller is in contact with the electrophotographic photosensitive drum and a spaced position in which the developing roller is spaced from the electrophotographic photosensitive drum; a force receiving member movably provided with respect to the developing frame for receiving an external force, wherein the force receiving member is capable of being in an operating position for moving the developing frame from a contact position to a spaced position by receiving the external force and a stand-by position retracted from the operating position; a pressing portion for pressing the force receiving member from the stand-by position toward the operating position; and an engaging portion for engaging with the force receiving member to hold the force receiving member in a standby position against an urging force of the urging portion.

According to another aspect of the present invention, there is provided an electrophotographic image forming apparatus for forming an image on a recording material, the apparatus comprising:

(i) a movable force application member;

(ii) a mounting device;

(iii) a process cartridge detachably mountable to said mounting device, said process cartridge comprising: an electrophotographic photosensitive drum; a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum; a drum frame supporting the electrophotographic photosensitive drum; a developing frame supporting the developing roller, the developing roller being movable relative to the drum frame between a contact position in which the developing roller is in contact with the electrophotographic photosensitive drum and a spaced position in which the developing roller is spaced from the electrophotographic photosensitive drum; a force receiving member movably provided with respect to the developing frame for receiving an external force when the force applying member is moved, wherein the force receiving member is capable of being in an operating position for moving the developing frame from the contact position to the spaced position and a stand-by position retracted from the operating position by receiving the external force; an urging portion for urging the force receiving member from the stand-by position toward the operating position; and an engaging portion for engaging with the force receiving member to hold the force receiving member in the stand-by position against an urging force of the urging portion, an

(vi) Feeding means for feeding the recording material.

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

Drawings

Fig. 1 is a schematic sectional view of an electrophotographic image forming apparatus in a first embodiment of the present invention, showing the general structure of the apparatus.

Fig. 2 is a schematic sectional view of a process cartridge in a first embodiment of the present invention.

Fig. 3 is a schematic sectional view of an electrophotographic image forming apparatus in the first embodiment of the present invention, showing the general structure of the apparatus.

Fig. 4 is another schematic cross-sectional view of an electrophotographic image forming apparatus in the first embodiment of the present invention, showing how a process cartridge in the apparatus is replaced.

Fig. 5 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a first embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 6 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a first embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 7 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a first embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 8 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a first embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 9 is a perspective view of the process cartridge in the first embodiment of the present invention, which is viewed from the side where the cartridge is driven.

Fig. 10 is a perspective view of the process cartridge in the first embodiment of the present invention, which is taken from the side from which the cartridge is driven.

Fig. 11 is a perspective view of the process cartridge in the first embodiment of the present invention, as viewed from the side opposite to the side on which the cartridge is driven.

Fig. 12 is a perspective view of the process cartridge in the first embodiment of the present invention, as seen from the side opposite to the side on which the cartridge is driven.

Fig. 13 is a perspective view of the force receiving member and the release member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 14 is another perspective view of the force receiving member and the release member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 15 (a) and 15 (b) are detailed schematic views of the force receiving member and the releasing member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 16 (a) and 16 (b) are detailed schematic views of the force receiving member and the releasing member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 17 is another detailed schematic view of the force receiving member and the release member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 18 is a further detailed schematic view of the force receiving member and the release member in the first embodiment of the invention, showing in detail the mechanical mechanism thereof.

Fig. 19 is a detailed schematic view of the force receiving member and the release member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 20 is another detailed schematic view of the force receiving member and the release member in the first embodiment of the present invention, showing the mechanical mechanism thereof in detail.

Fig. 21 is a detailed schematic view of the force receiving member in the first embodiment of the present invention, showing its mechanical mechanism in detail.

Fig. 22 is another detailed schematic view of the force receiving member in the first embodiment of the present invention, showing its mechanical mechanism in detail.

Fig. 23 is a schematic sectional view of an electrophotographic image forming apparatus in the first embodiment of the present invention, showing the general structure of the apparatus.

Fig. 24 is a schematic sectional view of an electrophotographic image forming apparatus in the first embodiment of the present invention, showing the general structure of the apparatus.

Fig. 25 is a schematic sectional view of an electrophotographic image forming apparatus in the first embodiment of the present invention, showing the general structure of the apparatus.

Fig. 26 is a schematic view of a guide hole of an electrophotographic image forming apparatus according to the first and second embodiments of the present invention.

Fig. 27 is a schematic view of the first force application member in the first embodiment of the invention, showing the operation of the force application member.

Fig. 28 is a schematic view of the first force application member in the first embodiment of the invention, showing the operation of the first force application member.

Fig. 29 is a perspective view of an electrophotographic image forming apparatus in the first embodiment of the present invention.

Fig. 30 is a partially cut-away perspective view of an electrophotographic image forming apparatus in a first embodiment of the present invention.

Fig. 31 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a second embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 32 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a second embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 33 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a second embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 34 is a schematic sectional view of one process cartridge and its vicinity structure in an electrophotographic image forming apparatus in a second embodiment of the present invention on a plane perpendicular to the axis of a photosensitive drum.

Fig. 35 is a schematic perspective view of the second force application member and the force receiving member in the second embodiment of the invention, showing the operation thereof.

Fig. 36 is a schematic perspective view of the second force application member and the force receiving member in the second embodiment of the invention, showing the operation thereof.

Fig. 37 is a schematic sectional view of an electrophotographic image forming apparatus in a second embodiment of the present invention, showing the general structure thereof.

Fig. 38 is a schematic sectional view of an electrophotographic image forming apparatus in a second embodiment of the present invention, showing the general structure thereof.

Fig. 39 is another schematic sectional view of an electrophotographic image forming apparatus in a second embodiment of the present invention, showing the general structure thereof.

Fig. 40 is a schematic sectional view of an electrophotographic image forming apparatus in a second embodiment of the present invention, showing how to replace a process cartridge therein.

Fig. 41 is a schematic view of a second force application member in the second embodiment of the invention, showing the operation of the second force application member.

Fig. 42 is a partially cut-away perspective view of an electrophotographic image forming apparatus in a second embodiment of the present invention.

Fig. 43 is a schematic view of the first force application member in the second embodiment of the invention, showing the operation of the first force application member.

Fig. 44 is a schematic view of the first force application member in the second embodiment of the invention, showing the operation of the first force application member.

Detailed Description

(example 1)

The process cartridge and the electrophotographic image forming apparatus in this preferred embodiment of the present invention will be described below with reference to fig. 1 to 4.

Fig. 1 is a schematic sectional view of an electrophotographic image forming apparatus 100 (which will be hereinafter simply referred to as apparatus main assembly) in which a plurality of (four) process cartridges 50y, 50m, 50c, 50k (which may hereinafter be simply referred to as cartridges 50) have been removably mounted. The plurality of (four) cartridges 50 store yellow, magenta, cyan, and black toners (developers), one for each cartridge. Figure 2 is a schematic cross-sectional view of the cartridge itself. Fig. 3 and 4 are schematic cross-sectional views of the electrophotographic image forming apparatus in this embodiment, for illustrating how any one or more cartridges 50 are removed from the main assembly of the image forming apparatus.

(general construction of electrophotographic image Forming apparatus)

The electrophotographic image forming apparatus in this embodiment is structured to perform the following image forming operation. Referring to fig. 1, first, uniformly charged areas of the peripheral surfaces of the respective electrophotographic photosensitive drums (which will be hereinafter simply referred to as photosensitive drums) 30y, 30m, 30c, and 30k are scanned by a laser beam 11, which laser beam 11 is emitted from a laser scanner 10 provided to the apparatus main assembly 100 while being modulated in accordance with a pattern signal. As a result, an electrostatic latent image is formed on the outer peripheral surface of each photosensitive drum 30. The electrostatic latent image is developed into a visible image by the developing roller 42; a toner (developer) image is formed on the peripheral surface of the photosensitive drum 30. In other words, yellow, magenta, cyan, and black toner images are formed on the photosensitive drums 30y, 30m, 30c, and 30k, respectively. Then, these toner images are sequentially transferred onto the transfer belt 19 supported and stretched by the rollers 20 to 22 by the voltages applied to the transfer rollers 18y, 18m, 18c, and 18 k. Thereafter, the toner image on the transfer belt 19 is transferred onto the sheet of the recording medium P conveyed by the recording medium conveying roller 1 as a recording medium conveying device by the transfer roller 3. Then, the recording medium P is conveyed to a fixing unit 6, and the fixing unit 6 is composed of a driving roller and a fixing roller having an internal heater. In the fixing unit 6, heat and pressure are applied to the recording medium P and the toner image thereon. As a result, the toner image on the recording medium P is fixed to the recording medium P. Then, the recording medium P is discharged onto the conveyance tray 9 by the pair of discharge rollers 7.

(general construction of Process Cartridge)

Next, the cartridge 50 (50 y, 50m, 50c, and 50 k) in this embodiment will be explained with reference to fig. 1, 2, 5 to 8, 29, and 30. In this embodiment, the plurality of (four) cartridges 50 are identical in structure although the colors of the stored toners T are different. Therefore, the structure of the cartridge 50 will be explained with reference to the cartridge 50 y.

Referring to fig. 2, the cartridge 50y is provided with the photosensitive drum 30 and a process device that processes the photosensitive drum 30. The process devices in this embodiment are a charging roller 32, a developing roller 42, a blade 33, and the like, the charging roller 32 is a charging device for charging the photosensitive drum 30, the developing roller 42 is a developing device for developing the latent image formed on the photosensitive drum 30, and the blade 33 is a cleaning device for removing residual toner remaining on the peripheral surface of the photosensitive drum 30. The cartridge 50y is composed of the drum unit 31 and the developing unit 41.

(construction of Drum Unit)

Referring to fig. 2, 4, 9-12, and 30, the drum unit 31 includes the above-described photosensitive drum 30, a charging roller 32, and a blade 33. The drum unit 31 further includes a waste toner storage portion 35, a drum unit main frame 34, and side covers 36 and 37 (which will be simply referred to as covers hereinafter). Referring to fig. 9, 10 (a) and 10 (b), one of the lengthwise-direction ends of the photosensitive drum 30 is rotatably supported by the supporting portion 36b of the cover 36, and the other lengthwise-direction end of the photosensitive drum 30 is rotatably supported by the supporting portion 37b of the cover 37, as shown in fig. 11 and 12. The covers 36 and 37 are firmly attached to the lengthwise ends of the drum unit main frame 34 (one-to-one correspondence). Next, referring to fig. 9, 10 (a) and 10 (b), the lengthwise end of the photosensitive drum 30 is provided with a coupling member 30a for transmitting the driving force to the photosensitive drum 30. When the cartridge 50y is mounted into the apparatus main assembly 100, the coupling member 30a engages a first coupling member 105 (shown in fig. 4 and 30) of the apparatus main assembly 100. In this way, as the driving force is transmitted from the motor (not shown) carried by the apparatus main assembly 100 to the coupling member 30a, the photosensitive drum 30 rotates in the direction indicated by the arrow mark u in fig. 2. The charging roller 32 is supported by the drum unit main frame 34 such that the charging roller 32 rotates in contact with the photosensitive drum 30 by the rotation of the photosensitive drum 30. The blade 33 is also supported by the drum unit main frame 34 such that the blade 33 is kept in contact with the outer peripheral surface of the photosensitive drum 30 when a preset amount of pressure exists between the blade 33 and the outer peripheral surface of the photosensitive drum 30. The covers 36 and 37 are provided with holes 36a and 37a for supporting the developing unit 41 in such a manner that the developing unit 42 is movable in a rotational manner with respect to the drum unit 31.

(Structure of developing unit)

Referring to fig. 2, 10 (a) and 10 (b), the developing unit 41 has the above-described developing roller 42. The developing unit 41 also has a developing blade 43, a developing unit main frame 48, a supporting unit 45, and a pair of side covers 46. The developing unit main frame 48 has a toner storage portion 49, and stores toner to be supplied to the developing roller 42 in the toner storage portion 49. The developing unit main frame 48 supports a developing blade 43 that adjusts the coverage thickness of the toner on the outer peripheral surface of the developing roller 42. Referring to fig. 10 (a) and 10 (b), the supporting unit 45 is fixedly attached to one lengthwise end of the developing unit main frame 48. The bearing unit 45 rotatably supports the developing roller 42, and one lengthwise end of the developing roller 42 has a developing roller gear 69. Further, the supporting unit 45 is provided with an intermediate gear 68, and the intermediate gear 68 transmits the driving force from the coupling member 67 to the developing roller gear 69. The cover 46 is firmly attached to the outside of the support unit 45 (in terms of the length direction of the support unit 45) in such a manner as to cover the coupling member 67 and the intermediate gear 68. Further, the cover 46 is provided with a cylindrical portion 46b protruding outward from the outer surface of the cover 46. The coupling member 67 is exposed through the hollow portion of the cylindrical portion 46 b. The apparatus main assembly 100 and the process cartridge 50y are structured such that: when the process cartridge 50y is mounted into the apparatus main assembly 100, the coupling portion 67a of the coupling member 67 engages a second coupling member 106 (which is shown in fig. 30) of the apparatus main assembly 100, thereby transmitting the driving force from a motor (not shown) carried by the apparatus main assembly 100 to the process cartridge 50 y.

(connection of developing Unit to Drum Unit)

Referring to fig. 10 (a) and 10 (b), the developing unit 41 and the drum unit 31 are connected in the following manner: first, at one end of the process cartridge 50y, the cylindrical portion 46b is fitted into the support hole 36 a. At the other end, a protrusion 48b protruding from the developing unit main frame 48 is fitted into the support hole 37 a. As a result, the developing unit 41 is connected to the drum unit 31 in such a manner that the developing unit 41 is rotationally movable relative to the drum unit. Next, referring to fig. 9 and 11, the developing unit 41 is kept pressed in the direction to be rotated around the cylindrical portion 46b and the projection 48 by the action of the compression spring 95 (which is an elastic member), so that the developing roller 42 is kept in contact with the photosensitive drum 30. That is, the developing unit 41 is kept pressed in the direction indicated by the arrow mark G by the elastic force of the compression spring 95, generating the moment H acting in the direction of rotating the developing unit 41 around the cylindrical portion 46b and the projection 48 b. Thus, the developing roller 42 is kept in contact with the photosensitive drum 30 and there is a contact pressure between the developing roller 42 and the photosensitive drum 30 by a preset amount. The position at which the developing unit 41 is located when it is held in contact with the photosensitive drum 30 is referred to as a "contact position".

Referring to fig. 9 and 11, the compression spring 95 is located on the other side opposite to one of the lengthwise direction ends where the coupling member 30a of the photosensitive drum 30 and the coupling member 67 of the developing roller 42 are located in this embodiment. This is because of the following reasons: when the coupling member 67 of the developing roller 42 receives the driving force from the coupling member 106 of the apparatus main assembly 100, as shown in fig. 2, a moment H is generated in the direction of rotating the developing unit 41 about the cylindrical portion 46 b. Thus, at this lengthwise end of the cartridge 50y, the developing roller 42 is pressed against the photosensitive drum 30, thereby generating a preset amount of contact pressure between the developing roller 42 and the photosensitive drum 30, while at the other lengthwise end, the developing roller 42 is kept pressed against the photosensitive drum 30 by the compression spring 95. (force receiving Member)

Referring to fig. 5 to 8, the cartridge 50y is provided with a force receiving member 70 for bringing the developing roller 42 and the photosensitive drum 30 in the apparatus main assembly 100 into contact with each other or separating them. Next, referring to fig. 10 (a), 10 (b), 13 and 14, the force receiving member 70 has a hook portion 70 a. As shown in fig. 13 and 14, a hook portion 70a is connected to one end of the spring 21 for keeping the force receiving member 70 pressed, and the other end of the spring 21 is connected to the hook portion 48a of the developing unit frame 48.

Referring to fig. 10 (b), the force receiving member 70 is attached to the support unit 45 by engaging a rotary shaft 70g, which is a part of the force receiving member 70, with a guide portion of the support unit 45. After the force receiving member 70 is attached, the cover 46 is attached to the developing unit frame 45 in such a manner that the cover covers the supporting unit 45 from a direction parallel to the axis of the developing roller 42. The details of the operation of the force receiving member 70 will be described later.

(Cartridge tray of main assembly of electrophotographic image forming apparatus)

Next, the tray 13 in the form of a drawer will be explained.

Referring to fig. 4, the cartridge tray 13 is attached to the apparatus main assembly 100 in such a manner that: in implementation, it is horizontally and linearly movable relative to the apparatus main assembly 100. That is, the tray 13 is movable (pushed into or pulled out of the apparatus main assembly 100) in a direction indicated by an arrow mark D1 or D2 (which is actually a horizontal direction), respectively. The apparatus main assembly 100 is structured such that: the cartridge tray 13 can be locked at an innermost position (image forming position in the apparatus main assembly 100 shown in fig. 1) and at an outermost position (cartridge replacement position shown in fig. 4, i.e., cartridge mounting or removing position, which is a farthest position at which the cartridge tray 13 can be pulled out). As shown in fig. 4, the cartridge 50 is mounted into the cartridge tray 13 by the operator in a direction indicated by an arrow mark C, which is substantially parallel to the direction of gravity. The cartridge tray 13 is structured such that: when these cartridges 50 are mounted into the cartridge tray 13, the cartridges 50 are arranged in tandem in a direction parallel to the movable direction of the cartridge tray 13, and the length direction of the cartridges 50 (which is parallel to the axes of the photosensitive drum 30 and the developing roller 42) is perpendicular to the movable direction of the cartridge tray 13. When the cartridge tray 13 is pushed into the apparatus main assembly 100, the cartridges 50 in the cartridge tray 13 enter the apparatus main assembly 100, and there is a preset amount of gap f2 (fig. 5) between the photosensitive drum 30 in each cartridge 50 and the intermediate transfer belt 19 located below the cartridge path in the apparatus main assembly 100. Then, when the cartridge tray 13 is moved to its innermost position in the apparatus main assembly 100, each cartridge 50 is correctly positioned in the apparatus main assembly 100 by the cartridge positioning portion 101a provided in the apparatus main assembly 100 (fig. 5 and 30). The cartridge positioning operation will be described in detail later. The user closes the door 12 after pushing the tray 13 all the way into the apparatus main assembly 100. Closing the door 12 ensures that each cartridge 50 is properly mounted in the apparatus main assembly 100. Therefore, such structural arrangement of the apparatus main assembly 100 and the cartridge 50 is superior in operability to that of the related art electrophotographic image forming apparatus in which the user is required to mount the cartridge 50 to the apparatus main assembly 100 separately.

Next, referring to fig. 23 to 26, the operation of the cartridge tray 13 will be described below. Fig. 23-26 do not show the cartridge 50 in order to make it easier to understand the operation of the cartridge tray 13.

The cartridge tray 13 is supported by a pair of tray support members 14 in the following manner: the cartridge tray 13 can be pulled out of the apparatus main assembly 100 while being held supported by the tray supporting member 14. The tray support member 14 is moved by the movement of the door 12, and the door 12 can be opened or closed by an operator (user). The door 12 is attached to the apparatus main assembly 100 such that it is rotatably movable about its rotational axis 12 a. The door 12 is rotatably movable between a position (closed position) to completely cover the opening 80 as shown in fig. 23 and a position (open position) to completely expose the opening 80 as shown in fig. 24.

When it is necessary to take out any one or more cartridges 50 in the apparatus main assembly 100, the door 12 is rotationally moved from the closed position to the open position. When the door 12 is rotationally moved, the pair of projections 15 (connecting pins) carried by the door 12 are moved clockwise about the rotational axis 12a while moving in the pair of elongated holes 14c carried by the tray supporting member 14 (one-to-one correspondence), moving from the bottom ends 14c2 of the elongated holes 14c toward the top ends 14c1 of the elongated holes 14c, as shown in fig. 24. As a result, the tray supporting member 14 is moved in the direction indicated by the arrow mark z1 by the projection 15. As shown in fig. 25, when the tray supporting members 14 are moved in the above-described direction z1, the projections 14d1 and 14d2 projecting from each tray supporting member 14 are guided by the guide holes 107 carried by the apparatus main assembly 100. Referring to fig. 26, each guide hole 107 has three sections, i.e., two horizontal sections 107a1 and 107a3, and one inclined section 107a 2. The inclined segment 107a2 extends obliquely upward from the horizontal segment 107a1 to the horizontal segment 107a 3. Therefore, when the door 12 moves from the closed position to the open position as shown in fig. 24, the projections 14d1 and 14d2 are guided by the guide hole 107, passing through the horizontal section 107a1, the inclined section 107a2, and the horizontal section 107a3 in this order. In this way, the tray supporting member 14 is first moved in the direction indicated by the arrow mark z1, and then moved in the direction indicated by the arrow mark y1 (fig. 24) (i.e., the direction away from the transfer belt 19). When the tray supporting member 14 moves all the way in the direction indicated by the arrow mark y1, the cartridge tray 13 can be pulled out of the apparatus main assembly 100 through the opening 80 in the direction indicated by the arrow mark D2, as shown in fig. 25. Fig. 30 is a partially cutaway view of the image forming apparatus after the cartridge tray 13 has been pulled out from the apparatus main assembly 100 to its outermost position.

Next, a case where any one cartridge or a plurality of cartridges 50 is mounted into the apparatus main assembly 100 will be described. Referring to fig. 25, with the door 12 held at the open position, the cartridge tray 13 is pushed into the apparatus main assembly 100 through the opening 80 in the direction of arrow mark D1. Then, the door 12 is moved to the closed position as shown in fig. 23. When the door 12 moves, each protrusion 15 of the door 12 moves in the counterclockwise direction about the rotation axis 12a while moving toward the bottom end 14c2 of the elongated hole 14c in the corresponding elongated hole 14c of the tray support member 14 as shown in fig. 23. Thus, the tray supporting member 14 is moved in the direction indicated by the arrow mark z2 (fig. 23) by the pair of projections 15. Therefore, when the door 12 is moved to the closed position as shown in fig. 23, the projections 14d1 and 14d2 are guided by the horizontal section 107a1, the inclined section 107a2, and the horizontal section 107a3 in the listed order, as shown in fig. 23. Therefore, the tray supporting member 14 is first moved in the direction of arrow mark z2 (fig. 23) and then moved in the direction of arrow mark y2 (fig. 23) (i.e., the direction of moving closer to the transfer belt 19).

(positioning of Process Cartridge with respect to the Main Assembly of the electrophotographic image Forming apparatus)

Next, referring to fig. 5 to 8, fig. 23 to 25, and fig. 30, the positioning of the cartridge 50 in the image forming apparatus main assembly 100 will be described. Referring to fig. 5 and 30, the apparatus main assembly 100 is provided with a plurality of pairs (four pairs in this embodiment) of cartridge positioning portions 101a for positioning the cartridge 50 relative to the apparatus main assembly 100. That is, in a direction parallel to the lengthwise direction of the cartridges 50, each cartridge magazine of the cartridge tray 13 is provided with a pair of cartridge positioning portions 101a, the cartridge positioning portions 101a being located at lengthwise direction ends of the respective cartridge magazines in one-to-one correspondence, and the transfer belt 19 being located between these two cartridge positioning portions 101 a. Referring next to fig. 6 and 23, when the door 12 is moved from the open position to the closed position, the cartridge tray 13 and the cartridge 50 are moved in the direction indicated by arrow mark y2 (fig. 23), causing the drum unit positioning portions 31b carried by the drum unit 31 to contact the corresponding cartridge positioning portions 101a of the apparatus main assembly 100. As a result, the cartridge 50y is positioned relative to the apparatus main assembly 100.

The releasing member 75 moved by the movement of the door 12 will now be described. Referring to fig. 23-25, as the door 12 moves from the open position to the closed position, the tray support member 14 moves in the direction indicated by arrow mark y2 (fig. 23). This movement of the tray supporting member 14 causes the projection 31b carried by the drum unit frame 34 to be correctly positioned by the positioning portion 101a of the apparatus main assembly 100, as shown in fig. 6.

Referring to fig. 5 and 6, when the tray supporting member 14 and the cartridge are moved in the direction indicated by the arrow mark y2, the releasing member pusher 102 fixedly attached to the apparatus main assembly 100 pushes up the releasing member 75 carried by the cartridge 50. The release mechanism of the release member 75 will be described in detail later.

(developing roller separating mechanism of main assembly of electrophotographic image forming apparatus)

The mechanism for moving the force receiving member 70 carried by the cartridge 50y will be described next with reference to fig. 5 to 8, 10, 13, and 14. Fig. 5 to 8 are schematic sectional views of the cartridge 50y in the apparatus main assembly 100 on a plane perpendicular to the axis of the photosensitive drum 30, and fig. 10 (a) is a detailed perspective view of the cartridge 50y as viewed from the driven side of the cartridge 50 y. Fig. 13 and 14 are detailed perspective views of the developing unit 41.

As described above, when the door 12 is moved from the open position to the closed position, the drum frame projection 31a of the cartridge 50y is moved in the direction indicated by the arrow mark y2 (fig. 6), thereby being positioned by the positioning portion 101a of the apparatus main assembly 100. During this movement of the drum frame protrusion 31a, the bottom end portion 75d (contact portion) of the release member 75 contacts the release member pusher 102. Thus, the release member 75 is pushed in the direction opposite to the direction indicated by the arrow mark y2, thereby being pushed upward. That is, when the door 12 is closed, the releasing member 75 receives an external force (second external force) from the releasing member pusher 102. Next, referring to fig. 5 and 13, initially, the release member 75 contacts the force receiving member 70. However, as the release member 75 is pushed upward, it separates from the force receiving member 70. As a result, the force receiving member 70 rotates about the rotational shaft 70g carried by the force receiving member 70 in such a manner as to rotate from its standby position (shown in fig. 5) toward the outside of the developing unit 41, that is, in a direction moving away from the rotational axis 46b of the developing unit 41, as shown in fig. 6 and 14.

Next, the operation of the first force application member 60 will be explained.

Referring to fig. 1 and 3, in terms of the vertical direction of the apparatus main assembly 100, the first force application member 60 is positioned such that: after each cartridge 50 is properly positioned in the apparatus main assembly 100, the first force application member 60 is located above the cartridge 50. In the direction parallel to the axis of the photosensitive drum 30, the first force application member 60 is positioned such that: which can contact the force receiving portions 70a of the force receiving members 70 at the respective lengthwise ends of the cartridge 50.

Referring to fig. 27 and 28, the driving force is transmitted from a motor 110 (mechanical power source) provided to the main assembly of the apparatus to a gear 112 through a gear 111. When the driving force is transmitted to the gear 112, the gear 112 rotates in the direction indicated by the arrow mark L, thereby rotating the cam portion 112a integral with the gear 112 in the direction indicated by the arrow mark L. The cam portion 112a contacts the moving force receiving portion 60b carried by the first force application member 60. Therefore, when the cam portion 112a rotates, the first force application member 60 moves in the direction indicated by the arrow mark E or B.

Fig. 27 shows the first force application member 60 that has been moved in the direction indicated by the arrow mark E. When the first force application member 60 is in the state shown in fig. 27, the developing roller 42 and the photosensitive drum 30 are still in contact with each other (fig. 7). Fig. 28 shows the first force application member 60 that has been moved in the direction indicated by the arrow mark B. When the first force application member 60 is in the state shown in fig. 28, the force receiving member 70 contacts the rib 60y, so it receives force from the first force application member 60. When the force receiving member 70 receives the force from the first force application member 60, the force receiving member 70 rotates the developing unit 41 about the rotation axis 46b, causing the developing roller 42 to separate from the photosensitive drum 30 (fig. 8). This position of the developing unit 41 shown in fig. 28 will be referred to as a separation position of the developing unit 41.

The urging member 70 of the cartridge 50 is held in the standby position (fig. 5) while each cartridge 50 is moved into the apparatus main assembly 100. Therefore, the first force application member 60 can be positioned significantly closer to the cartridge path of the apparatus main assembly than the force application member of the related art image forming apparatus, and the first force application member 60 and the cartridge 50 are not caused to interfere with each other during mounting of the cartridge 50, and therefore the wasted space can be minimized, and thus it is made possible to significantly reduce the vertical dimension of the apparatus main assembly 100.

(instructions for mounting the process cartridge to the main assembly of the electrophotographic image forming apparatus and the force receiving member)

Next, the operation sequence from the mounting of the cartridge 50 to the apparatus main assembly 100 until the separation of the developing roller 42 from the photosensitive drum 30 will be described.

Referring to fig. 4, after the cartridge tray 13 is pulled out from the apparatus main assembly 100 to its outermost position, each cartridge 50 is mountable to or removable from the cartridge tray 13 in the vertical direction indicated by an arrow mark C.

After the cartridge 50 is mounted into the cartridge tray 13, the cartridge tray 13 will be moved into the apparatus main assembly 100 through the opening 80 in the direction indicated by the arrow D1. That is, in this embodiment, each cartridge 50 is horizontally moved into the apparatus main assembly 100 in a direction intersecting (substantially perpendicular to) the axis of the photosensitive drum 30.

Referring to fig. 3, the cartridge 50y is mounted most downstream of the cartridge tray 13 in terms of the direction in which the cartridge tray 13 is moved (mounted) into the apparatus main assembly 100. That is, the cartridge 50y moves from upstream to downstream below the ribs 60k, 60c, and 60m of the first force application member 60.

Also in terms of the direction in which the cartridge tray 13 moves into the apparatus main assembly 100, the cartridge 50m is mounted in the second cartridge bay from the downstream end of the cartridge tray 13. In this way, when the cartridge tray 13 is mounted into the apparatus main assembly 100, the cartridge 50m is moved from upstream to downstream under the ribs 60k and 60c of the first force application member 60 (which act on the cartridges 50k and 50 c).

Still in terms of the direction in which the cartridge tray 13 moves into the apparatus main assembly 100, the cartridge 50c is mounted in the third cartridge bay from the downstream end of the cartridge tray 13. In this way, when the cartridge tray 13 is mounted into the apparatus main assembly 100, the cartridge 50c is moved from upstream to downstream under the rib 60k of the first force application member 60 (which acts on the cartridge 50 k).

Further, in terms of the direction in which the cartridge tray 13 is moved into the apparatus main assembly 100, the cartridge 50k is mounted in the most upstream cartridge bay from the downstream end of the cartridge tray 13. In this way, when the cartridge tray 13 is mounted into the apparatus main assembly 100, the cartridge 50k is moved deep enough into the apparatus main assembly 100 to move the force receiving member 70 from upstream to downstream under the force applying portion 60k of the first force applying member 60 (which acts on the cartridge 50 k).

If the cartridge 50 is designed such that the force receiving member 70 of the cartridge 50 remains projected when the cartridge 50 is moved into the apparatus main assembly 100, the first force application member 60 will have to be positioned higher than it is in this embodiment to prevent the force receiving member 70 and the first force application member 60 from interfering with each other. However, in this embodiment, the cartridge 50 is designed such that the force receiving member 70 is held in its standby position, i.e., a position where it does not protrude from the cartridge 50. Therefore, the first force application member 60 can be positioned closer to the cartridge path because the distance by which the force receiving member 70 protrudes does not need to be considered. In other words, designing the cartridge 50 so that the force receiving members 70 thereof are in the standby position with each other when the cartridge 50 is mounted into the apparatus main assembly 100 makes it possible to reduce the vertical dimension of the apparatus main assembly 100.

In this way, in this embodiment, as shown in fig. 5, when the cartridge tray 13 holding the cartridges 50 is moved into the apparatus main assembly 100, there is a gap f1 between the first force application member 60 and the force receiving member 70, and a gap f2 between the photosensitive drum 30 and the transfer belt 19, thereby preventing the respective cartridges 50 and the apparatus main assembly 100 from interfering with each other when the cartridges 50 are mounted into the apparatus main assembly 100.

Referring to fig. 23 to 25, after the cartridge tray 13 is pushed all the way into the apparatus main assembly 100, the door 12 is moved to the closed position. When the door 12 is moved to the closed position, the tray support member 14 is moved toward the transfer belt 19 (the direction indicated by an arrow mark y 2). Hereinafter, the vertical component of the movement of the tray support member 14 in the direction indicated by the arrow mark y2 will be referred to as the distance f 2. When the tray supporting member 14 moves in the direction indicated by the arrow mark y2, the cartridges 50 move toward the transfer belt 19 with the movement of the tray supporting member 14, thereby causing the outer peripheral surfaces of the photosensitive drums 30 in the respective cartridges 50 to start to contact the surface of the transfer belt 19 as shown in fig. 6. In this way, by the time the outer peripheral surface of the photosensitive drum 30 starts to contact the surface of the transfer belt 9, the distance f1 between the force receiving device 70 and the first force application member 60 widens to the sum of the gaps f1 and f 2.

Further, referring to fig. 6, when the door 12 is moved to the closed position, the cartridge positioning portions 31b of the respective cartridges 50 come into contact with the corresponding cartridge positioning portions 101a with which the apparatus main assembly 100 is provided, thereby correctly positioning the cartridges 50 relative to the apparatus main assembly 100.

As described above, the restriction of the movement of the force receiving member 70 by the releasing member 75 is removed by the function of the releasing member pusher 102 carried by the apparatus main assembly 100. In this way, when the restriction of the releasing member 75 acting on the force receiving member 70 is removed, the force receiving member 70 starts rotating from its standby position in such a direction that its force receiving portion 70a moves to the outside of the developing unit 41 of the cartridge 50y (protrudes from the developing unit 41), i.e., moves away from the direction of the rotational axis 46b of the developing unit 41 as shown in fig. 6.

However, when the force receiving member 70 is rotated as described above, the top surface of the force receiving member 70 contacts the bottom surface of the rib 60y of the first force application member 60. As a result, the movement of the force receiving member 70 is regulated by the rib 60y (the state shown in fig. 6). This position of the force receiving member 70 will be referred to as the neutral position.

In this embodiment, the position of the first force application member 60 corresponding to the above-described intermediate position of the force receiving member 70 is the original position of the first force application member 60. This is because of the following reason. That is, when the image forming apparatus is not used for image formation after the cartridges 50 are mounted, each cartridge 50 is kept in the state shown in fig. 8, that is, the following state: the first force application member 60 has moved in the direction indicated by the arrow mark B, and the force receiving member 70 has contacted the rib 60y, thereby preventing further movement thereof. In this state, the photosensitive drum 30 and the developing roller 42 are kept separated from each other. That is, as shown in fig. 8, in this state (in which the photosensitive drum 30 and the developing roller 42 are kept separated from each other), the cartridge 50 is removed from the apparatus main assembly 100. In this way, when the cartridge 50 is mounted into the apparatus main assembly 100 next time, since the first force application member 60 is at the position shown in fig. 8, the force receiving member 70 contacts the rib 60 y. Therefore, when the force receiving member 70 is rotated away from its standby position, the force receiving member 70 comes into contact with the bottom surface of the rib 60y, as shown in fig. 6.

Incidentally, the force receiving member 70 receives the external force (first external force) from the surface of the first force application member 60 toward the direction in which each cartridge 50 is mounted into the apparatus main assembly 100. Having the external force receiving surface of the force receiving member 70 face the above-described direction ensures that: when the force receiving member 70 receives the force from the first force application member 60, the developing unit 41 is effectively moved relative to the photosensitive drum 30, and it is ensured that the photosensitive drum 30 and the developing roller 42 are kept separated from each other.

When the first force application member 60 moves in the direction indicated by the arrow mark E from the position shown in fig. 6 to the position shown in fig. 7, the force receiving portion of the force receiving member 70 further rotates toward the outside of the cartridge 50y, thereby entering the path of the rib 60 y. This position of the force receiving member 70 (i.e., the position where the force receiving portion of the force receiving member 70 has moved into the path of the rib 60 y) will be referred to as a protruding position (an acting position). That is, it is apparent that the force receiving member 70 protrudes more from the cartridge 50y when the force receiving member 70 is in its protruding position than when the force receiving member 70 is in its standby position or intermediate position. In order for the force receiving member 70 to contact the first force application member 60 when the cartridge 50 is moved into the apparatus main assembly 100, the projecting distance of the force receiving member 70 in the projecting position needs to be larger than the sum of the gaps f1 and f 2. Further, the first force application member 60 is started to operate after each cartridge 50 is mounted into the apparatus main assembly 100 and immediately before the next image forming operation is started.

Next, the force application member 60 is moved in the direction indicated by the arrow mark B as shown in fig. 8. When the first force application member 60 moves, the side surface 70e of the force receiving member 70 (i.e., the first force application member contact surface of the force receiving member 70 in the path of the first force application member 60) receives an external force (first external force) from the rib 60y of the first force application member 60. As a result, the developing unit 41 is rotationally moved about its rotational axis 46b (shaft), causing the developing roller 42 to be separated from the photosensitive drum 30 by a distance α

In this way, when the image forming operation is performed next time, the first force application member 60 will move in the direction indicated by the arrow mark E to set the developing roller 42 in contact with the photosensitive drum 30. As shown in fig. 7, when the first force application member 60 is moved in the direction indicated by the arrow mark E, the force receiving member 70 is separated from the first force application member 60, thereby stopping receiving the force from the rib 60 y. As a result, the developing roller 42 is brought into contact with the photosensitive drum 30 by the elastic force of the compression spring 95 provided between the developing unit 41 and the drum unit 31, whereby the process cartridge 50 can be prepared for image formation. It should be noted herein that the photosensitive drum 30 starts to rotate before the developing roller 42 comes into contact with the photosensitive drum 30. Further, the developing roller 42 also starts to rotate by receiving the driving force from the apparatus main assembly 100 via the coupling portion 67a before the developing roller 42 comes into contact with the photosensitive drum 30 for the following reason. That is, both the developing roller 42 and the photosensitive drum 30 start to rotate before the developing roller 42 comes into contact with the photosensitive drum 30, so that the difference in circumferential speed between the photosensitive drum 30 and the developing roller 42 is significantly smaller than otherwise. Therefore, the cartridge 50 in this embodiment generates an amount of abrasion on the photosensitive drum 30 and the developing roller 42 when they contact each other, which is significantly smaller than other process cartridge structures. It is to be noted herein that timing with respect to the start of rotation of the photosensitive drum 30 and the developing roller 42 is feasible because, in order to ensure that the coupling portion 67a does not change position even after the developing unit 41 rotationally moves around the cylindrical portion 46b, the cartridge 50 is structured such that the axis of the cylindrical portion 46b coincides with the axis of the coupling portion 67 a. After the image formation is completed, the developing roller 42 is separated from the photosensitive drum 30 by moving the first force application member 60 in the direction indicated by the arrow mark B as described above. After the developing roller 42 is separated from the photosensitive drum 30, the developing roller 42 and the photosensitive drum 30 stop rotating. Therefore, the cartridge 50 in this embodiment is significantly smaller in the difference in circumferential speed between the photosensitive drum 30 and the developing roller 42 when the developing roller 42 is separated from the photosensitive drum 30 than the process cartridges of other structures, and is therefore significantly smaller in the abrasion when the developing roller 42 is separated from the photosensitive drum 30 than the process cartridges of other structures. As a result, the electrophotographic image forming apparatus in this embodiment is significantly superior to a comparable image forming apparatus according to the related art.

(relationship between force receiving Member and Release Member)

The relationship between the force receiving member 70 and the releasing member 75 will be described next with reference to fig. 5 to 6, and fig. 13 to 15 (b). Fig. 15 (a) and 15 (b) are detailed schematic views of the force receiving member and the releasing member 75, showing a mechanical mechanism for releasing the force receiving member 70.

Referring to fig. 2, the cartridge 50y is provided with a force receiving member 70, and the force receiving member 70 is used to set the developing roller 42 and the photosensitive drum 30 in contact with or separated from each other in the apparatus main assembly 100. Referring next to fig. 13 and 15 (a), the force receiving member 70 is provided with a hook portion 70a, and one of the lengthwise ends of the tension spring 21 as a tension generating member is attached to the hook portion 70 a. The other end of the tension spring 21 is attached to the hook portion 48a of the developing unit frame 48. In this way, the force receiving member 70 is held under the tension of the tension spring 21, and the tension spring 21 works in a direction of pulling the force receiving member 70 from the stand-by position to the protruding position. Referring to fig. 13 and 15 (a), the force receiving member 70 is provided with a force receiving portion 70e (fig. 7 and 8) and a contact portion 70 b. The force receiving portion 70e is a portion of the force receiving member 70 via which the external force is received from the first force application member 60. The contact portion 70b is a portion of the force receiving member 70 that contacts the release member 75. When the contact portion 70b comes into contact with the contact portion 75b carried by the release member 75, the force receiving member 70 is prevented from being rotationally moved from the stand-by position to the protruding position.

Still referring to fig. 13 and 15 (a), the releasing member 75 is provided with a hook portion 75c, and one of the lengthwise ends of the second tension spring 22 is attached to the hook portion 75 c. The other end of the tension spring 22 is attached to a hook portion 48a carried by the developing unit frame 48. In this way, the release member 75 is held in tension in the direction indicated by arrow y3 (fig. 3). Further, the developing unit frame 48 is provided with a releasing member regulating portion 48b for regulating the movement of the releasing member 75 held in tension in the direction indicated by an arrow mark y 3.

Next, the movement of the force receiving member 70 from its standby position to its protruding position will be described.

Referring to fig. 5, 6 and 13-15 (b), when the cartridge 50 is correctly positioned relative to the apparatus main assembly 100 by the cartridge positioning portion 101a of the apparatus main assembly 100, the releasing member pusher 102 fixedly attached to the main frame of the image forming apparatus comes into contact with the contact portion 75d of the releasing member 75 and is pressed against the contact portion 75 d. This moves the release member 75 in the direction indicated by the arrow mark y4 (fig. 14), causing the contact portion 75b thereof to separate from the contact portion 70b of the force receiving member 70. As a result, the force receiving member 70 is rotationally moved from its standby position to the protruding position by the elastic force (tension) of the tension spring 21.

In the following mathematical expressions, f3, f4, f5 and g respectively denote the magnitude of the elastic force of the tension spring 21, the magnitude of the elastic force of the tension spring 22, the magnitude of the force (or positioning force) with which the cartridge 50 is urged (positioned) on the cartridge positioning portion 101a of the main assembly frame, and the own weight of the cartridge 50. In this embodiment, in order to prevent the release member 75 from releasing the force receiving member 70, the relationship between the above forces is set as follows: f3 is set to be larger than f4 (f 3> f 4). The magnitude of the upward force received by the cartridge 50 when the releasing member pusher 102, which is firmly fixed to the main assembly frame, pushes the releasing member 75 is f4, while the magnitude of the downward force received by the cartridge 50 when the releasing member pusher 102 pushes the releasing member 75 is equal to the sum of f3, f5 and g, i.e., equal to (f 3+ f5+ g). In this way, the force receiving member 70, the releasing member 75, the spring 21, and the spring 22 are designed to satisfy the following inequality: f4< f3+ f5+ g. Therefore, there is no case where the releasing member 75 releases the force receiving member 70 when the cartridge 50 is not in the apparatus main assembly 100, nor is there a case where the cartridge 50 is lifted from the cartridge positioning portion 101a of the apparatus main assembly 100 after being correctly positioned in the apparatus main assembly 100.

In this embodiment, the releasing member 75 is provided with a contact portion 75b as a part of a mechanism for releasing the contact portion 70b of the force receiving member 70. However, instead of providing the release member 75 with the contact portion 75b, the drum unit 31 or the developing unit 41 may be provided with a member such as the contact portion 775b shown in fig. 17 and 18. In the case of the force receiving member release mechanism shown in fig. 17 and 18, the drum unit frame 34 as one structural component of the drum unit 31 or the developing unit frame 48 as one structural component of the developing unit 41 is provided with the contact portion 775 b. In this case, when the cartridge 50 is mounted into the apparatus main assembly 100, the releasing member pusher 102 fixedly secured to the apparatus main assembly 100 urges the contact portion 775b in the direction indicated by the arrow mark in fig. 18. More specifically, the contact portion 775b receives an external force (second external force) from the release member pusher 102. Accordingly, the contact portion 775b moves in the direction indicated by the arrow mark H (fig. 18), thereby disengaging the contact portion 70b of the force receiving member 70. That is, the releasing member 775 is provided with an elastic connecting portion 775e, and the releasing member 775 is attached to the drum unit frame 34 or the developing unit frame 48 through the elastic connecting portion 775 e. Therefore, when the release member pusher 102 pushes the force receiving portion 775d of the release member 75, the connecting portion 75e is deformed by the force received by the force receiving portion 775 d. As a result, the contact portion 775d moves away from the contact portion 70b of the force receiving member 70, thereby allowing the contact portion 70b to rotationally move as described above. In this case, the drum unit frame 34 or the developing unit frame 48 is provided with the releasing portion 775. However, the releasing portion 775 may be provided to a structural member other than the drum unit frame 34 or the developing unit frame 48. Further, in this embodiment, the releasing member pushers 102 of the apparatus main assembly 100 are positioned below the respective cartridge bays. However, the releasing member pusher 102 may be positioned at any position as long as it is positioned so that the releasing member pusher 102 can push the releasing member when the cartridge 50 is in the apparatus main assembly. Further, the release member pusher 102 may be any shape as long as the shape enables the release member pusher 102 to move the release member 70 by contacting the release member 70. For example, it may be U-shaped in cross-section rather than in the form of a protrusion as in the embodiments.

Further, as shown in fig. 16 (16 (a) and 16 (b)), by extending the hook portion 70a of the force receiving member 70 so that the hook portion 70a itself can be elastically deformed and can directly engage the hook portion 48a of the developing unit frame 48, the tension spring 21 can be omitted.

Further, referring to fig. 19 and 20, the releasing member 75 may be replaced by, for example, a releasing member 875 which is movable by utilizing a driving force received from the apparatus main assembly 100 by the coupling member 67 of the developing unit 41. More specifically, the cartridge 50 is provided with a gear 123, and the gear 123 has a projection 123a (pin) for pushing the release member pusher 875 in the direction indicated by an arrow mark y 4. Further, the release member 875 is provided with a contact portion 875e that is in contact with the above-described protrusion 123a (pin). Thus, when the gear 123 rotates in the direction indicated by the arrow mark G by the above-described driving force, the protrusion 123a pushes up the contact portion 875a of the release member 875. As a result, the contact portion 875b of the release member 875 disengages from the contact portion 70b of the force receiving member 70, thereby allowing the force receiving member 70 to rotationally move to its protruding position. When the projection 123a of the gear 123 disengages from the contact portion of the release member 875, the release member 875 is pushed downward (in the direction indicated by the arrow mark y 5) by the elastic force of the tension spring 22. Thereafter, the gear 123 continues to rotate as long as the driving force is transmitted to the cartridge 50, but the protrusion 123a of the gear 123 and the contact portion 875e of the release member 875 do not contact each other. (removal of Process Cartridge from the Main Assembly of the electrophotographic image Forming apparatus)

Next, an operation for removing the cartridge 50 from the apparatus main assembly 100 will be explained.

Referring to fig. 24, when the door 12 is to be moved from its closed position to the open position, the tray supporting member 14 is moved upward as shown in fig. 24, i.e., in a direction away from the transfer belt 19 (the direction indicated by an arrow mark y 1). As a result, each cartridge 50 moves upward with the cartridge tray 13, so that the photosensitive drum 30 in each cartridge 50 is separated from the transfer belt 19.

Further, when the tray 13 is moved in the pulled-out direction (the direction indicated by the arrow mark z1 in fig. 24), the cartridge 50 is transitioned from the state shown in fig. 8 to the state shown in fig. 7. That is, the force receiving member 70 no longer remains pressed by the first force application member 60. When the cartridge 50 is in this state (i.e., the state shown in fig. 7), as shown in fig. 7 and 14, the force receiving member 70 is held in the protruding position by the tension of the tension spring 21. Referring to fig. 21 and 22, the force receiving member 70 is provided with a contact portion 70c having an inclined surface, the contact portion 70c being on the other side of the force receiving member 70 opposite to the side surface 70e (fig. 8) that receives the force from the first force application member 60.

When the tray supporting member 14 is pulled in the direction indicated by the arrow mark z1 (fig. 24), the contact portion 70c contacts the force receiving member returning portion 60zm (which also has an inclined surface) of the first force application member 60. In this way, when the tray supporting member 14 is further pulled, the force receiving member 70 at the projecting position is pushed down in the direction indicated by the arrow mark K (fig. 22) by the force receiving member returning portion 60mz, thereby allowing the force receiving member 70 to move below the rib 60m, thereby allowing the cartridge 50 to move toward the outside of the apparatus main assembly 100. Then, the cartridge 50 moves under the ribs 60c and 60k, and moves out of the apparatus main assembly 100 through the opening 80.

When the cartridge 50 is mounted into the image forming apparatus main assembly 100 again after being moved out of the image forming apparatus main assembly 100, the force receiving member 70 in the protruding position can be returned to the standby position by depressing the force receiving member 70. The operation of pressing the force receiving member 70 back to its standby position can be easily performed by the user because the releasing member 75 and the second tension spring 22 connected to the releasing member 75 are elastic.

In the case of the release member 875 that must be moved by the aforementioned driving force, the gear 123 must be rotated back to the preset position before the release member 875 can be returned to the standby position. The release member 875 can be rotated back to the pre-set position by manually rotating a gear connected to the gear 123 or using a tool (screwdriver or similar tool).

As described above, the electrophotographic image forming apparatus in this embodiment is structured such that: when the door 12 is moved to its closed position after the cartridge 50 is mounted into the apparatus main assembly, the force receiving member 70 for moving the developing unit 41 is rotated in a direction such that the contact portion 70 thereof projects outwardly from the developing unit 41.

Therefore, the cartridge 50 in this embodiment is significantly smaller than the cartridge according to the related art (hereinafter simply referred to as a conventional cartridge). Further, when the cartridge 50 is mounted into the apparatus main assembly 100, the force receiving member 70 is held in its standby position. Therefore, the apparatus main assembly 100 in this embodiment can be manufactured to be significantly smaller than that of the conventional electrophotographic image forming apparatus in the vertical dimension of the cartridge path. Accordingly, the openings 80 can be made significantly smaller than corresponding openings of conventional electrophotographic imaging apparatuses. Further, the first force application member 60 can be placed significantly closer to the cartridge path than the corresponding components of the conventional electrophotographic image forming apparatus. Therefore, the apparatus main assembly 100 can be significantly reduced in size in the vertical direction as compared with the apparatus main assembly of the conventional electrophotographic image forming apparatus.

Further, before the cartridge 50 is mounted into the apparatus main assembly 100, the force receiving member 70 is in its standby position. Therefore, when the cartridge 50 is operated by a user or it is separately transported, it is not easy to occur that the force receiving portion 70 is damaged.

(example 2)

In the first embodiment, the releasing member 75 is disengaged by the projection 102 (releasing member pusher) fixedly attached to the main assembly frame. However, in this embodiment, the structure of the cartridge is such that: the releasing member is moved by receiving a force from a movable second urging member carried by the apparatus main assembly.

Also, this embodiment will be described in connection with a cartridge (more specifically, a cartridge 950y that stores a yellow developer). Incidentally, the description of this embodiment will be made around structural features of the electrophotographic image forming apparatus in this embodiment which are different from those of the first embodiment.

(Cartridge tray of main assembly of electrophotographic image forming apparatus)

Next, the operation of the tray 13 in this embodiment will be described with reference to fig. 37 to 39.

The cartridge 50 is not shown in fig. 37-39 in order to make it easier to understand the operation of the cartridge tray 13.

The cartridge tray 13 is supported by a pair of tray support members 14 in the following manner: the cartridge tray 13 can be pulled out of the apparatus main assembly 100 while being held supported by the tray supporting member 14. The tray support member 14 is carried by the movement of the door 12, and the door 12 can be opened or closed by an operator (user). The door 12 is attached to the apparatus main assembly 900 so that it can be rotationally moved about its rotational axis 12a (a shaft by which the door 12 is held to the apparatus main assembly 100). The door 12 is rotatably movable between a position (closed position) to completely cover the opening 80 as shown in fig. 27 and a position (open position) to completely expose the opening 80 as shown in fig. 28.

When it is necessary to take out any one cartridge or a plurality of cartridges in the apparatus main assembly 900, the door 12 is rotationally moved from the closed position to the open position. When the door 12 is rotationally moved, the pair of projections 15 (connecting pins) carried by the door 12 are moved clockwise about the rotational axis 12a while moving in the pair of elongated holes 14c carried by the tray supporting member 14 (one-to-one correspondence), as shown in fig. 38, from the bottom end 14c2 of the elongated hole 14c toward the top end 14c1 of the elongated hole 14 c. As a result, the tray supporting member 14 is moved in the direction indicated by the arrow mark z1 by the projection 15. When the tray supporting members 14 are moved in the above-described direction, the projections 14d1 and 14d2 projecting from each tray supporting member 14 are guided by the guide holes 107 carried by the apparatus main assembly 900. Referring to fig. 26, each guide hole 107 has three sections, i.e., two horizontal sections 107a1 and 107a3, and one inclined section 107a 2. The inclined segment 107a2 extends obliquely upward from the horizontal segment 107a1 to the horizontal segment 107a 3. Therefore, when the door 12 is moved to the open position, as shown in fig. 38, the protrusions 14d1 and 14d2 are guided by the guide hole 107, sequentially passing through the horizontal section 107a1, the inclined section 107a2, and the horizontal section 107a 3. Thus, the tray supporting member 14 is first moved in the direction indicated by the arrow mark z1, and then moved in the direction indicated by the arrow mark y1 (i.e., the direction moving away from the transfer belt 19). As the tray supporting member 14 moves all the way in the direction indicated by the arrow mark y1, as shown in fig. 39, the cartridge tray 13 can be pulled out of the apparatus main assembly 900 through the opening 80 in the direction indicated by the arrow mark D2. Fig. 42 is a partially cutaway view of the image forming apparatus after the cartridge tray 13 has been pulled out from the apparatus main assembly 900 to its outermost position.

Next, a case where any cartridge or cartridges is/are mounted into the apparatus main assembly 900 will be described. Referring to fig. 39, the tray 13 is pushed into the apparatus main assembly 900 through the opening 80 in the direction of the arrow mark D2, and the door 12 is held at the open position. Then, the door 12 is moved to the closed position as shown in fig. 37. When the door 12 moves, each protrusion 15 of the door 12 moves in the counterclockwise direction about the rotation axis 12a while moving toward the bottom end 14c2 of the elongated hole 14c in the corresponding elongated hole 14c of the tray supporting member 14 as shown in fig. 37. Thus, the tray supporting member 14 is moved in the direction of the arrow mark z2 by the pair of projections 15. Thus, when the door 12 is moved to the closed position as shown in fig. 37, the projections 14d1 and 14d2 are guided by the guide hole 107, i.e., the horizontal section 107a3, the inclined section 107a2, and the horizontal section 107a1 in this order. Therefore, the tray supporting member 14 is first moved in the direction of arrow mark z2, and then moved in the direction of arrow mark y2 (i.e., the direction of moving closer to the transfer belt 19).

(positioning of Process Cartridge with respect to the Main Assembly of the electrophotographic image Forming apparatus)

Next, the positioning of the cartridges 950 (950 y, 950m, 950c, and 950 k) in the apparatus main assembly 900 will be explained with reference to fig. 31, 35, 36, 41, and 42. Referring to fig. 42, the apparatus main assembly 900 is provided with a plurality of pairs (four pairs in this embodiment) of cartridge positioning portions 901a for positioning the cartridge 950 relative to the apparatus main assembly 900. That is, in a direction parallel to the lengthwise direction of the cartridges 950, each cartridge magazine of the cartridge tray 13 is provided with a pair of cartridge positioning portions 901a, the pair of cartridge positioning portions 901a being located at lengthwise direction ends of the respective cartridge magazines (one-to-one correspondence), and the transfer belt 19 being located between the two cartridge positioning portions. Referring next to fig. 41 (a) and 41 (b), the main assembly 900 is further provided with a second force application member 61, the second force application member 61 being located above the tray supporting member 14. Each of the second force application members 61 is provided with a hole 61d, and the second force application member support shaft 55, which is carried by the apparatus main assembly 900, passes through the hole 61d to rotatably support the second force application member 61.

A mechanism for moving the second force application member 61 by using the movement of the door 12 will now be described. The second force application member 61 is connected to the connection member 62, and the connection member 62 is used to move the second force application member 61 by utilizing the movement of the door 12. The linking member 62 is provided with a hole in which the support shaft 55 is fitted, and a support pin 62b that is fitted in an elongated hole 14b (fig. 41 (b)) of the tray supporting member 14. Referring to fig. 41, when the door 12 is moved from the open position to the closed position, the tray supporting member 14 is moved in the direction indicated by an arrow mark y2 (fig. 41), thereby forcing the supporting pin 62b in the elongated hole 14b to also move in the direction indicated by an arrow mark y 2. As a result, the linking member 62 rotationally moves about the support pin 62b in the elongated hole 14b in the direction indicated by the arrow mark Z (fig. 41).

This movement of the connecting member 62 associated with the second force application member 61 causes the pressing portion 62e carried by the connecting member 62 to be pressed against the force receiving surface 31a, which is a part of the top surface of the drum unit frame 34. Thus, the cartridge 950 is moved in the direction (downward) indicated by the arrow mark y2 shown in fig. 41 (b), causing the cartridge positioning portion 931b (fig. 7) carried by the drum unit 931y to contact the cartridge positioning portion 901a carried by the apparatus main assembly 900. As a result, the cartridge 950y is correctly positioned with respect to the apparatus main assembly 900 (fig. 6).

The other cartridges 950m, 950c, and 950k are also correctly positioned with respect to the apparatus main assembly 900 in the same manner as the above-described positioning of the cartridge 950 y.

Referring to fig. 35 and 36, the cartridge 950y is provided with a spring 66, the spring 66 being interposed between the second force application member 61 and the connecting member 62. The spring 66 is supported by the support shaft 55, and is in contact with the pressing portion 61e of the connecting member 62 and the protruding portion 61e of the second force application member 61. Incidentally, the apparatus main assembly 900 may be structured such that: the spring 66 is directly pressed against the force receiving surface of the drum unit frame.

(operation of urging member)

Next, the operation of the first force application member 60 will be explained with reference to fig. 43 and 44.

As in the first embodiment, the driving force is transmitted from the motor 110 (mechanical power source) carried by the apparatus main assembly 900 to the gear 112 through the gear 111. When the driving force is transmitted to the gear 112, the gear 112 rotates in the direction indicated by the arrow mark L, thereby also rotating the cam portion 112a integral with the gear 112 in the direction indicated by the arrow mark L. The cam portion 112a contacts the moving force receiving portion 60b carried by the first force application member 60. Therefore, when the cam portion 112a rotates, the first force application member 60 moves in the direction indicated by the arrow mark E or B.

Fig. 43 shows a case in which the first force application member 60 has been moved farthest in the direction indicated by the arrow mark E. In this case, the developing roller 42 and the photosensitive drum 30 are still in contact with each other (fig. 33). Fig. 44 shows a case in which the first force application member 60 has been moved farthest in the direction indicated by the arrow mark B. In this case, the force receiving member 70 is under the pressure of the rib 60 y. When the force receiving member 70 is pressed by the rib 60y, the developing unit 941 is caused to rotationally move about the rotation axis 946b (shaft), thereby causing the developing roller 42 to separate from the photosensitive drum 30 (fig. 34). This position of the developing unit 41 will be referred to as a "separation position".

When the cartridge 950 is moved into the apparatus main assembly 900, the force receiving member 970 is held in its standby position (fig. 31). Therefore, the first force application member 60 and the second force application member 61 can be positioned significantly closer to the cartridge path of the apparatus main assembly than the corresponding members of the conventional image forming apparatus, and they and the cartridge 50 are not caused to interfere with each other during mounting of the cartridge 50, so that the wasted space can be minimized, thereby making it possible to significantly reduce the vertical dimension of the apparatus main assembly 900.

(description of mounting of Process Cartridge to the Main Assembly of the electrophotographic image Forming apparatus and operation of force receiving device)

Next, the operation sequence from the mounting of the cartridge 950 to the apparatus main assembly 100 until the separation of the developing roller 42 from the photosensitive drum 30 will be described.

Referring to fig. 40, after the cartridge tray 13 is pulled out from the apparatus main assembly 900 to its outermost position, each cartridge 950 is mountable to or removable from the cartridge tray 13 in the vertical direction indicated by an arrow mark C.

After the cartridge 950 is mounted into the cartridge tray 13, the cartridge tray 13 will be moved into the apparatus main assembly 900 through the opening 80 in the direction indicated by the arrow D1. That is, in this embodiment, each cartridge 950 is horizontally moved into the apparatus main assembly 100 in a direction intersecting (substantially perpendicular to) the axis of the photosensitive drum 30.

Referring to fig. 40, the cartridge 50y is mounted most downstream in the cartridge tray 13 in terms of the direction in which the cartridge tray 13 moves into the apparatus main assembly 900. That is, when the cartridge tray 13 is pushed into the apparatus main assembly 900, the cartridge 950y moves from upstream to downstream below the second force application members 61k, 61c and 61m to be respectively applied to the other cartridges (i.e., the cartridges 950m, 950c and 950 k), and also moves below the ribs 60k, 60c and 60m of the first force application member 60.

Also, in terms of the direction in which the cartridge tray 13 is moved into the apparatus main assembly 900, mounted second from the downstream end of the cartridge tray 13 is the cartridge 950 m. In this way, when the cartridge tray 13 is pushed into the apparatus main assembly 900, the cartridge 950m moves from upstream to downstream under the second force application members 61k and 61c (fig. 39) to be respectively applied to the other cartridges (i.e., the cartridges 950c and 950 k), and also moves under the ribs 60k and 60c of the first force application member 60.

Still in terms of the direction in which the cartridge tray 13 is moved into the apparatus main assembly 900, the cartridge 950c moves from upstream to downstream below the second force application member 61k (fig. 39) to be acted on the cartridge 950k, and also moves below the rib 60k of the first force application member 60.

Further, the cartridge 950k is mounted most upstream in terms of the direction in which the cartridge tray 13 moves into the apparatus main assembly 900. In this way, when the cartridge tray 13 is mounted into the apparatus main assembly 900, the cartridge 950k moves deep enough into the apparatus main assembly 900 to move the force receiving member 970 from upstream to downstream under the first force application member 60 to be applied to the cartridge 950 k.

The other cartridges (i.e., cartridges 950y, 950m, and 950 c) are the same as the cartridge 950k in terms of the movement of the force receiving member 970 from upstream to downstream under the second force application member 61.

That is, if the cartridge 950 is designed such that its force receiving member 970 remains projecting when the cartridge 950 is mounted into the apparatus main assembly 900, the second force application member 61 and the first force application member 60 will have to be positioned higher than in this embodiment in order to prevent the force receiving member 970 from interfering with the second force application member 61 and the first force application member 60. However, in this embodiment, the cartridge 950 is designed such that the force receiving member 970 is held in the standby position (i.e., the position where it does not protrude), and the second force application member 61 and the first force application member 60 can be positioned closer to the cartridge path, because the distance by which the force receiving member 970 protrudes need not be considered. In other words, designing the cartridge 950 such that the force receiving member 970 thereof is held in its standby position when the cartridge 950 is mounted into the apparatus main assembly 900 makes it possible to reduce the vertical dimension of the apparatus main assembly 900. Further, referring to fig. 31 and 32, in this embodiment, the force receiving member 970, the second force application member 61, and the first force application member 60 overlap in a direction parallel to the axis of the photosensitive drum 30, significantly reducing the size of the cartridge 950 in a direction perpendicular to the lengthwise direction thereof.

Further, referring to fig. 31, 32, 35, and 36, when the contact portion is at the first position (fig. 31 and 35), the pressing portion 61e of the second force application member 61 is in contact with the contact portion 975b (fig. 32 and 36), and presses the contact portion 975 b. That is, when the contact portion 975b is at the first position, the contact portion 975b receives an external force (second external force). When the pressing portion 61e presses on the contact portion 975b, the release member 975 is disengaged from the force receiving member 970, and the release member 975 moves to the second position (fig. 32 and 36). The second force application member 61 in this embodiment corresponds to the release member pusher 102 in the first embodiment.

When the release member 975 is disengaged from the force receiving member 970, the force receiving member 970 rotates about the force receiving member support shaft, away from its standby position, that is, such that the contact portion 970b of the force receiving member 970 protrudes from the developing unit 941, that is, in a direction in which the contact portion 970b is away from the rotation axis 946b of the developing unit 41 (activated position). The image forming operation performed thereafter is the same as in the first embodiment, and therefore will not be described here.

Next, an operation for removing the cartridge 950 from the apparatus main assembly 900 will be explained.

When the door 12 is moved from the closed position to the open position, the second force application member 61 is rotated from the position shown in fig. 32 and 36 to the position shown in fig. 31 and 35. By this movement of the second force application member 61, the pressure held on the release member 975 by the second force application member 61 is removed. However, the force receiving member 970 is held in the protruding position by the elastic force of the spring 921, as shown in fig. 33. Referring to fig. 36, the force receiving member 970 is provided with a contact portion 970c having an inclined surface at the other side opposite to the side surface of the force receiving member 970 receiving the force from the first force application member 60. In this way, when the cartridge tray 13 is pulled out in the direction indicated by the arrow mark D2 in fig. 39, the force receiving member 970 (in the protruding position as with the force receiving member 70 in the first embodiment) contacts the force receiving member returning members 60zm, 60zcy, and 60zk carried by the first force application member 60 and is urged downward so as to be allowed to pass the ribs 60m, 60c, and 60k, thereby enabling the cartridge 950y to move out of the apparatus main assembly 900 through the opening 80.

As described above, the cartridge 950 is structured such that: when the door 12 is moved to the closed position after the cartridge 950 is mounted into the apparatus main assembly 100, the contact portion 970b of the force receiving member 970 for moving the developing unit 941 protrudes outward from the developing unit 941. Thus, the cassette 950 is significantly smaller in vertical dimension than conventional cassettes. Further, when the cartridge 950 is mounted into the apparatus main assembly 900, the force receiving member 970 is held at the standby position. Therefore, the cartridge path in the apparatus main assembly can be smaller in vertical dimension than that of the conventional electrophotographic image forming apparatus, and the vertical dimension of the opening 80 is smaller than that of the apparatus main assembly of the conventional electrophotographic image forming apparatus. Further, the first force application member 60 can be positioned closer to the cartridge path, so that the vertical dimension of the apparatus main assembly 900 can be reduced.

Further, when the cartridge 950 is out of the apparatus main assembly 900, the force receiving member 970 is held at the standby position. Therefore, the force receiving member 970 is not easily damaged when the cartridge 950 is operated by a user or is separately transported.

(Industrial Applicability)

According to the present invention, it is possible to reduce the size of a process cartridge whose electrophotographic photosensitive drum and developing roller can be disposed in contact with or separated from each other, and also to reduce the size of an electrophotographic image forming apparatus employing the above process cartridge. Further, the above-described process cartridge may be structured such that: when the cartridge is transported separately, its force receiving member for separating the developing roller from the electrophotographic photosensitive drum is not easily damaged.

While the invention has been described in connection with 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.

Claims (25)

1. A main assembly mountable to and dismountable from an electrophotographic image forming apparatus, said main assembly having a force applying member and a returning portion, said process cartridge comprising:

(1) an electrophotographic photosensitive drum;

(2) a developing roller movable between a contact position where the developing roller is in contact with the electrophotographic photosensitive drum to develop an electrostatic latent image formed on the electrophotographic photosensitive drum and a spaced position where the developing roller is spaced apart from the electrophotographic photosensitive drum;

(3) a drum frame supporting the electrophotographic photosensitive drum;

(4) a developing frame supporting the developing roller; and

(5) a force receiving member movable relative to the developing frame so as to move between a protruding position in which the force receiving member protrudes outward from the developing frame and a standby position in which the force receiving member is retracted from the protruding position toward an inside of the developing frame, the force receiving member including:

(5-1) a force receiving portion for receiving a force from the force applying member to move the developing roller from the contact position to the spaced position in a state where the process cartridge is mounted to the main assembly and the force receiving member is located at the projecting position; and

(5-2) a contact portion for contacting the return portion to move the force receiving member toward the standby position when the process cartridge is dismounted in the state in which the force receiving member is located at the projected position.

2. A process cartridge according to claim 1, wherein said process cartridge is passable through an opening provided at said main assembly in an entering direction to enter said main assembly,

the force receiving portion is located on an opposite side of the contact portion with respect to the entering direction.

3. A process cartridge according to claim 1 or 2, wherein said force receiving member is provided at said developing frame.

4. A process cartridge according to claim 1 or 2, further comprising:

a spring for urging the force receiving member toward the protruding position; and

an engaging portion movable between an engaging position where it engages with the force receiving member so as to position the force receiving member in the standby position against the urging force of the spring, and a releasing position where it is released from the force receiving member to project the force receiving member.

5. A process cartridge according to claim 4, wherein said engaging portion is provided on said developing frame.

6. A process cartridge according to claim 4, wherein said engaging portion is provided on said drum frame.

7. A process cartridge according to claim 4, wherein said engaging portion is disengaged from said force receiving member by a releasing force from a releasing portion provided in said main assembly.

8. A process cartridge according to claim 7, further comprising a releasing member moved by a releasing force received from a releasing portion provided in said main assembly to release said force receiving member from said engaging portion.

9. A process cartridge according to claim 8, wherein said engaging portion and said releasing member are integral with each other.

10. A process cartridge according to claim 8, wherein said releasing member is movably provided on said developing frame.

11. A process cartridge according to claim 9, wherein said releasing member is movably provided on said developing frame.

12. A process cartridge according to claim 4, further comprising a gear for rotating by a driving force received from said main assembly in a state in which said process cartridge is mounted to said main assembly, thereby moving said engaging portion to release said engaging portion from said force receiving member.

13. A process cartridge according to claim 4, wherein said engaging portion is urged in a direction of engaging with said force receiving member to hold said force receiving member at said standby position.

14. A process cartridge according to claim 1 or 2, wherein said developing frame is rotatable relative to said drum frame about a rotation axis, and when said force receiving member is moved from said standby position to said projecting position, said force receiving member projects away from said rotation axis.

15. A process cartridge according to claim 14, wherein said developing frame is rotatable relative to said drum frame for moving said developing roller from said contact position to said spaced position when said force receiving portion receives the force.

16. An electrophotographic image forming apparatus comprising:

a main assembly having a force applying member and a return portion; and

a process cartridge mountable to and dismountable from the main assembly, the process cartridge having:

(1) an electrophotographic photosensitive drum;

(2) a developing roller movable between a contact position where the developing roller is in contact with the electrophotographic photosensitive drum to develop an electrostatic latent image formed on the electrophotographic photosensitive drum and a spaced position where the developing roller is spaced apart from the electrophotographic photosensitive drum;

(3) a drum frame supporting the electrophotographic photosensitive drum;

(4) a developing frame supporting the developing roller; and

(5) a force receiving member movable relative to the developing frame so as to move between a protruding position in which the force receiving member protrudes outward from the developing frame and a standby position in which the force receiving member is retracted from the protruding position toward an inside of the developing frame, the force receiving member including:

(5-1) a force receiving portion for receiving a force from the force applying member to move the developing roller from the contact position to the spaced position in a state where the process cartridge is mounted to the main assembly and the force receiving member is located at the projecting position; and

(5-2) a contact portion for contacting with a return portion to move the force receiving member toward the standby position when the process cartridge is detached in a state in which the force receiving member is located at the projecting position.

17. An apparatus according to claim 16, wherein said process cartridge is capable of passing through an opening provided at said main assembly in an entering direction to enter said main assembly,

the force receiving portion is located on an opposite side of the contact portion with respect to the entering direction.

18. The electrophotographic image forming apparatus according to claim 16 or 17, further comprising:

a spring for urging the force receiving member toward the protruding position; and

an engaging portion movable between an engaging position where it engages with the force receiving member so as to position the force receiving member in the standby position against the urging force of the spring, and a releasing position where it is released from the force receiving member to project the force receiving member.

19. An apparatus according to claim 16 or 17, wherein said force receiving member is provided at said developing frame.

20. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, the main assembly having a force applying member and a returning portion, said process cartridge comprising:

(1) an electrophotographic photosensitive drum;

(2) a developing roller movable between a contact position where the developing roller is in contact with the electrophotographic photosensitive drum to develop an electrostatic latent image formed on the electrophotographic photosensitive drum and a spaced position where the developing roller is spaced apart from the electrophotographic photosensitive drum;

(3) a drum frame supporting the electrophotographic photosensitive drum;

(4) a developing frame supporting the developing roller; and

(5) a force receiving member movable relative to the developing frame between an active position in which the force receiving member is contactable with the force applying member and a standby position in which the force receiving member is not contactable with the force applying member, the force receiving member including:

(5-1) a force receiving portion capable of receiving a force from the force applying member to move the developing roller from the contact position to the spaced position in a state where the force receiving portion is located at a working position; and

(5-2) a contact portion contactable with the return portion to move the force receiving portion toward the stand-by position.

21. A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, the main assembly having a force applying member and a returning portion, said process cartridge comprising:

(1) an electrophotographic photosensitive drum;

(2) a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum;

(3) a drum frame supporting the electrophotographic photosensitive drum;

(4) a developing frame supporting the developing roller, the developing frame being rotatable relative to the drum frame about a rotation axis to move between a contact position where the developing roller is in contact with the electrophotographic photosensitive drum and a spaced position where the developing roller is spaced apart from the electrophotographic photosensitive drum; and

(5) a force receiving member, the force receiving member comprising:

(5-1) a force receiving portion movable relative to the developing frame to move between a protruding position and a standby position closer to the rotation axis than the protruding position, the force receiving portion being capable of receiving a force from the force applying member to move the developing frame from the contact position to the spaced position in a state in which the force receiving portion is located at the protruding position; and

(5-2) a contact portion contactable with the return portion to move the force receiving portion toward the stand-by position.

22. A process cartridge according to claim 20 or 21, wherein said force receiving member is provided at said developing frame.

23. An electrophotographic image forming apparatus comprising:

a main assembly having a force applying member and a return portion; and

a process cartridge detachably mountable to said main assembly, said process cartridge comprising:

(1) an electrophotographic photosensitive drum;

(2) a developing roller movable between a contact position where the developing roller is in contact with the electrophotographic photosensitive drum to develop an electrostatic latent image formed on the electrophotographic photosensitive drum and a spaced position where the developing roller is spaced apart from the electrophotographic photosensitive drum;

(3) a drum frame supporting the electrophotographic photosensitive drum;

(4) a developing frame supporting the developing roller; and

(5) a force receiving member, the force receiving member comprising:

(5-1) a force receiving portion movable relative to the developing frame to move between a protruding position and a standby position in which the force receiving portion is retracted from the protruding position toward an inside of the developing frame, the force receiving portion being capable of receiving a force from the force applying member to move the developing roller from the contact position to the spaced position in a state in which the force receiving portion is located at the protruding position; and

(5-2) a contact portion contactable with the return portion to move the force receiving portion toward the stand-by position.

24. An electrophotographic image forming apparatus comprising:

a main assembly having a force applying member and a return portion; and

a process cartridge detachably mountable to said main assembly, said process cartridge comprising:

(1) an electrophotographic photosensitive drum;

(2) a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum;

(3) a drum frame supporting the electrophotographic photosensitive drum;

(4) a developing frame supporting the developing roller, the developing frame being rotatable relative to the drum frame about a rotation axis to move between a contact position where the developing roller is in contact with the electrophotographic photosensitive drum and a spaced position where the developing roller is spaced apart from the electrophotographic photosensitive drum; and

(5) a force receiving member movable relative to the developing frame between an active position in which the force receiving member is contactable with the force applying member and a standby position in which the force receiving member is not contactable with the force applying member, the force receiving member including:

(5-1) a force receiving portion capable of receiving a force from the force applying member to move the developing frame from the contact position to the spaced position in a state where the force receiving portion is located at a working position; and

(5-2) a contact portion contactable with the return portion to move the force receiving portion toward the stand-by position.

25. An apparatus according to claim 23 or 24, wherein said force receiving member is provided at said developing frame.