Process cartridge and image forming system

Abstract: A process cartridge (31) detachably mountable within an image forming system, comprises an image bearing member (5), action means for acting on the image bearing member, a housing for supporting the image bearing member and the action means, and a cover shiftable (8) between a protecting position where the image bearing member (5) is protected and a retard position where the cover is retarded from the protecting position. Cover (8) is spaced apart from the housing at least in the retard position. An image forming system comprises mounting means for mounting such process cartridge, air flow generating means (15) for generating an air flow passing through between the housing and the cover, transfer means (18) for transferring a developed image formed on the image bearing member onto a recording medium, and conveying means for conveying the recording medium.

Description: This invention relates to an image forming apparatus for use with a process cartridge, and to a combination of such an apparatus and cartridge. The image forming apparatus may take the form of an electrophotographic copying machine, a laser beam printer, a facsimile system, a word processor or the like. From JP-A-59-61865 a process cartridge is known in which a cover acts in its open position as protection from heat generated in a fixing device. A first aspect of the invention relates in particular to a combination of an image forming apparatus and a process cartridge; the apparatus having a main body having a cavity to receive the cartridge, and a fan for generating a flow of air in the apparatus; the cartridge having a casing containing a photosensitive drum and a process means actable on the drum, and a shutter moveable between a closed position in which it protects the drum and an open position in which it reveals the drum; and the combination comprising means for removably mounting the cartridge in the cavity in an operative position and means for opening the shutter when the cartridge is inserted into the cavity. Such a combination is known from patent document GB-A-2101933. The fan is provided to keep the inside of the apparatus cool and prevent components of the apparatus from the thermal effects of, for example, a fixing device. The shutter is provided to prevent the drum from physical damage when it is being handled by a user and to protect the drum from ambient light when the cartridge is outside the apparatus. The drum and process means are provided in a cartridge which is removably mounted in the apparatus so that when the cartridge is used up or becomes damaged, it can be replaced by a user of the apparatus without requiring the services of a skilled technician. In the cartridge described in GB-A-2101933, when the shutter is in its open position, part of the shutter is disposed inside the casing, and the shutter touches or is very closely spaced from the casing. The combination of the first aspect of the invention is characterised in that when the cartridge is in the operative position and the shutter is open, the shutter is disposed outside the casing and is spaced from the casing and engages a portion of the main body to deflect the flow of air along a path between the shutter and the casing. Accordingly the shutter not only serves the traditional function of preventing the drum from physical damage and from light when the cartridge is outside the apparatus, but also participates in the cooling system of the combination when the cartridge is in the operative position in the apparatus so that there is a flow of air between the casing and the shutter which can help to keep the casing cool. Preferably, the portion of the main body with which the shutter engages is provided by a guide member which projects into the cavity. In accordance with a second aspect of the invention, there is provided an image forming apparatus per se for use with a cartridge as described above, the apparatus having a main body having a cavity to receive the cartridge, a fan for generating a flow of air in the apparatus, means for removably mounting the cartridge in the cavity, and means for opening the shutter when the cartridge is inserted into the cavity; characterised by: an air-guide member which projects inside the cavity for engaging the shutter when the cartridge is mounted in the cavity in the operative position and the shutter is open so that the flow of air can be deflected along a path between the shutter and the air-guide member on the one hand and the casing on the other hand. Other preferred features of the invention are defined in the appended subsidiary claims. A specific embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is an elevational sectional view of a laser beam printer to which an embodiment of the present invention is applied; Fig. 2A is a plan view of a regulating member; Fig. 2B is an end view of the regulating member of Fig. 2A; Fig. 3A is a perspective view showing a relation between a process cartridge and a regulating member of a machine to which the embodiment of the present invention is applied, in a condition that a drum protection member is closed; Fig. 3B is an end view showing a relation between the process cartridge of Fig. 3A and the regulating member of the machine; Fig. 4A is a perspective view showing a condition that the drum protection member is opened; and Fig. 4B is an end view showing the condition that the drum protection member is opened. Referring to the drawings, when a process cartridge 302 is inserted into a laser beam printer 300 (from a direction shown by the arrow V in Fig. 3B), a protection member 309 for protecting an image bearing member 5 of the process cartridge 302 from light, external force, smudge and the like is shifted from a protecting position (closed position) to a retard position (open position). The detailed description of the conveying path of recording medium P from inlet tray 104 to transfer roller 135, fixing device 14 to outlet tray 27 is omitted, since it is conventional prior art. Incidentally, an opening/closing mechanism for the protection member 309 will be explained later. In this case, the process cartridge 302 can be correctly mounted in a predetermined position, because an upper surface 302b of the cartridge is abutted against a position regulating member 308 disposed at an upper part of a cartridge mounting position, thus regulating a position of the cartridge in an upward direction. Further, in this case, a rear end 309d of the protection member 309 is abutted against a flow rectifying plate 308b pivotally provided on the position regulating member 308 along the transversal direction of the printer to lift this flow rectifying plate 308b, thus maintaining this plate in a slightly downwardly inclined position. Incidentally, the flow rectifying plate 308b is made from flexible material such as resin and the like and has an attachment portion 308b2 and a flow rectifying portion 308bl pivotable with respect to the attachment portion 308b2. Further, the flow rectifying portion 308b1 is obliquely formed with respect to the attachment portion 308b2 and is apt to be pivoted due to the presence of notches 308b3. In this condition, when a copy button (not shown) is turned ON, a fan 15 is rotated to suck the air through an air introduction opening 300a formed in a side wall of the printer 300 at its upper part and from a sheet supply portion, thus generating air flows (W 1 - W 9 ) flowing around the process cartridge 302 and directing toward the fan 15. Now, the air flow W 3 flowing along the upper surface of the process cartridge 302 impinges against and blocked by a wall 308b of the position regulating member 308, with the result that this air flow passes through a clearance between a housing 302a of the process cartridge 302 and an inner surface of the protection member 309 (air flow W 4 ). This air flow W 4 impinges against a sheet conveying surface (guide 25) and changes its flow direction between the sheet conveying surface 25 and the protection member 309 to be directed upwardly (air flow W 6 ), and then flows toward the fan 15 as the air flows W 7 , W 8 toward the fan 15 from which they are ejected out of the printer (air flow W 9 ). Next, the movements of the protection member 309 and the position regulating member 308 in mounting the process cartridge 302 within the printer 300 will be explained with reference to Figs. 3A, 3B and 4A, 4B. Figs. 3A and 3B show a condition that the process cartridge 302 starts to be mounted on a predetermined position within the printer 300. From this condition, when the housing 302a of the process cartridge 302 is inserted toward the direction V, first of all, a cover moving link 309b for opening a cover 309a of the protection member 309 is abutted against a protrusion 310 of the printer. When the housing 302a of the process cartridge is further inserted, the cover moving link 309b is rotated around a pivot pin 309bl, with the result that the cover 309a of the protection member attached to a pivot pin 309b2 positioned on the other end of the link 309b (opposite to an end which is abutted against the protrusion 310 with respect to the pivot pin 309bl) is gradually opened while being guided by a movable link 309c. When the housing 302a of the process cartridge is completely inserted, the cover 309a of the protection member is abutted against the flow rectifying plate 308b of the position regulating member 308 as mentioned above, thus rotating the flow rectifying portion 308bl around a pivot portion (reduced thickness portion) 308b4 of the flow rectifying plate. In the condition that the housing 302a of the process cartridge 302 is completely mounted within the printer 300 (Figs. 1, 4A and 4B), the air flows in the printer 300 as air flows W 1 - W 9 . Particularly, as shown by the air flow W 4 , the air flow passing between the housing 302a of the process cartridge 302 and a plate 312 of the printer impinges against a wall 308a (attachment portion 308b2) of the position regulating member 308 for the process cartridge 302. Then, this air flow passes through between the housing 302a and the flow rectifying plate 308b and between the housing 302a and the cover 309a of the protection member. Thus, the housing 302a of the process cartridge 302 is hard to be receive the heat from the fixing device 14, thus suppressing the increase in the temperature in the cartridge 302. Incidentally, in the illustrated embodiment, while the clearance between the housing 302a and the cover 309a of the protection member was selected to have a value of about 5 mm - 10 mm, the clearance is not limited to this value. Incidentally, in the above embodiment, while an example that a heat fixing device is used as the fixing device was explained, the present invention is not limited to this example. For example, a pressure fixing device may be used. Further, other than the heat fixing device, although motors, exposure lamp and the like also generate the heat in the image forming system, the present invention is also effective to the generation of heat from such elements. Further, the clearance (distance) between the housing of the process cartridge and the cover can be appropriately selected in accordance with the designs of the process cartridge and the image forming system; however, such clearance may be about 2 mm - 50 mm, and preferably 3 mm - 40 mm, and most preferably 5 mm - 20 mm. If the clearance is smaller than about 2 mm, the sufficient cooling ability cannot sometimes be obtained (However, even if the clearance is about 1 mm, some cooling ability can be obtained in comparison with the case where there is no clearance); whereas, if the clearance is greater than about 50 mm, the image forming system will become large-sized. Incidentally, the above-mentioned process cartridge incorporates therein an image bearing member (for example, electrophotographic photosensitive member and the like), and at least one of a charger means, developing means and cleaning means (action means) as a unit which can removably mounted within an image forming system. More specifically, the process cartridge incorporates therein a charger means 22, developing means 23 or cleaning means 28, and an electrophotographic photosensitive member 5 as a unit which can be removably mounted within an image forming system (for example, a copying machine, laser beam printer or the like); or incorporates therein at least one of a charger means, developing means and cleaning means, and an electrophotographic photosensitive member as a unit which can be removably mounted within an image forming system (for example, a copying machine, laser beam printer or the like); or incorporates therein at least a developing means and an electrophotographic photosensitive member as a unit which can be removably mounted within an image forming system (for example, a copying machine, laser beam printer or the like). As mentioned above, according to the present invention, it is possible to provide a process cartridge and an image forming system which can remarkably enhance the cooling ability for the process cartridge by air flows.

Claims: A combination of an image forming apparatus and a process cartridge; the apparatus having a main body having a cavity to receive the cartridge, and a fan (15) for generating a flow of air in the apparatus; the cartridge (302) having a casing (302a) containing a photosensitive drum (5) and a process means (22,23,28) actable on the drum, and a shutter (309) moveable between a closed position in which it protects the drum and an open position in which it reveals the drum; and the combination comprising means for removably mounting the cartridge in the cavity in an operative position and means (309b,310) for opening the shutter when the cartridge is inserted into the cavity; characterised in that: when the cartridge is in the operative position and the shutter is open, the shutter is disposed outside the casing and is spaced from the casing and engages a portion of the main body to deflect the flow of air (W4) along a path between the shutter and the casing. A combination according to claim 1, wherein the spacing between the shutter and said casing when said shutter is in its open position is between 2 mm to 50 mm. A combination according to claim 2, wherein the spacing is between 3 mm and 40 mm. A combination according to claim 3, wherein the spacing is between 5 mm and 20 mm. A combination as claimed in any preceding claim, further comprising means for transporting a recording medium past the drum and past a heating device (14) for fixing a toner image on the recording medium (P); and wherein, when the cartridge is in the operative position and the shutter is open, the shutter (309) is disposed between the cartridge and the heating device. A combination as claimed in any preceding claim, wherein the portion of the main body with which the shutter engages is provided by a guide member which projects into the cavity. An image forming apparatus for use with a process cartridge (302) having a casing (302a) containing a photosensitive drum (5) and process means (22,23,28) actable on the drum, and a drum shutter moveable between a closed position in which it protects the drum and an open position in which it reveals the drum and is disposed outside the casing, the apparatus having a main body having a cavity to receive the cartridge, a fan (15) for generating a flow of air in the apparatus, means for removably mounting the cartridge in the cavity, and means (309b,310) for opening the shutter when the cartridge is inserted into the cavity; characterised by: an air-guide member (308b) which projects inside the cavity for engaging the shutter (309) when the cartridge is mounted in the cavity in the operative position and the shutter is open so that the flow of air can be deflected along a path between the shutter and the air-guide member on the one hand and the casing on the other hand. A combination as claimed in any of claims 1 to 6, or an apparatus as claimed in claim 7, wherein the air-guide member is movably mounted in the cavity and is arranged to be moved when engaged by the shutter.

Inventors: IKEMORI IKUO, KOMATSU TERUO, SHIRAI HIROYUKI, TSUDA TADAYUKI, WATANABE KAZUSHI, IKEMORI, IKUO, KOMATSU, TERUO, SHIRAI, HIROYUKI, TSUDA, TADAYUKI, WATANABE, KAZUSHI, Ikemori, Ikuo, c/o Canon Kabushiki Kaisha, Komatsu, Teruo, c/o Canon Kabushiki Kaisha, SHIRAI, HIROYUKI, C/O CANON KABUSHIKI KAISHA, TSUDA, TADAYUKI, C/O CANON KABUSHIKI KAISHA, WATANABE, KAZUSHI, C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1992
Main classification: G03G15
IPC codes: B41J29, G03G21, G03G15