JP2005121765A - Process cartridge and electrophotographic image forming apparatus capable of attaching/detaching process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extend the service life of a process cartridge by increasing the toner amount and waste toner amount capable of being stored in the cartridge without enlarging the size of the outer shape of the cartridge. <P>SOLUTION: The process cartridge comprises: a developing unit which includes a developing container having a developing means, and a toner container for storing toner; and a cleaning unit which has a cleaning means for supporting a photoreceptor drum so that the drum freely rotates and for scraping toner on the photoreceptor, and a waste toner container storing scraped toner. The developing unit and the cleaning unit are vertically arranged with the space of a laser optical path between them. The width of the space of the optical path in the sub-scanning direction, which is defined by the toner container and the waste toner container, includes an area that narrows as a laser reaches a light emitting position on the photoreceptor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a process cartridge and an electrophotographic image forming apparatus to which the process cartridge can be attached and detached. Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming process. For example, an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.) An electrophotographic facsimile, an electrophotographic word processor, and the like are included. Further, as the process cartridge, a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge can be attached to and detached from the image forming apparatus main body. Alternatively, at least one of the charging unit, the developing unit, and the cleaning unit and the image carrier are integrally formed into a cartridge that can be attached to and detached from the image forming apparatus main body. Further, it means that at least the developing means and the electrophotographic photosensitive member are integrated into a cartridge so as to be detachable from the image forming apparatus main body.

  In an image forming apparatus using an electrophotographic image forming process, a process in which an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge can be attached to and detached from the image forming apparatus main body. A cartridge system is adopted. The structure of a conventional process cartridge is shown in FIG. Such a process cartridge includes an electrophotographic photosensitive member 1 rotatably supported by a cleaning frame 50, a developing container 45 having developing means for developing a latent image formed on the surface of the photosensitive member, and a toner in the developing container. Developer storage unit (toner container) 41 for supplying the toner, and used developer storage unit (waste toner container) 53 for removing the toner remaining on the surface of the photoreceptor after image transfer to the recording medium and storing the toner. The developing container and the toner container are coupled by heat welding or the like. The toner container 41 and the waste toner container 53 are disposed relatively up and down across the optical path space, and the developing frame 45 constituting the toner container 41 swings relative to the cleaning frame 50 constituting the waste toner container. It is a suspended structure supported movably. The laser light L emitted from the scanner unit passes through the optical path space formed by the toner container 41 and the waste toner container 53 and is irradiated to the photosensitive member. Thereby, an electrostatic latent image is formed on the photosensitive drum, and the electrostatic latent image is developed by the developing device. Further, the developed image formed on the photosensitive drum is transferred to a recording medium.

In order to extend the life of the process cartridge having the above configuration, it is necessary to increase the toner capacity and the waste toner capacity. In order to increase the toner capacity and the waste toner capacity, the process cartridge may be enlarged. However, the enlargement of the process cartridge is not preferable because it leads to an enlargement of the main body of the image forming apparatus. As a means for increasing the toner capacity and waste toner capacity without increasing the external shape of the process cartridge, a process cartridge having a container shape having a convex portion in an area avoiding the laser light path space has been devised.
Japanese Patent Laid-Open No. 10-319820 (page 2-3, FIG. 2-24)

  An image forming apparatus using the process cartridge system can perform apparatus maintenance and process cartridge replacement by the user himself without relying on a service person. Such an image forming apparatus is required to be small in size and to reduce the number of process cartridge replacements performed by the user as much as possible. In order to reduce the size of the image forming apparatus main body, the process cartridge mounted on the image forming apparatus main body must be configured as small as possible. Further, in order to reduce the number of times the process cartridge is replaced, it is necessary to increase the toner capacity and extend the life of the process cartridge. In order to increase the toner capacity, the toner container may be enlarged, but this is contrary to the downsizing of the process cartridge.

  A color image forming apparatus whose demand is currently increasing in the market generally has toners of four colors of cyan, magenta, yellow, and black in the main body of the image forming apparatus, and one toner for each color toner. It has a toner container. The increase in the size of the toner container in the color image forming apparatus leads to a further increase in the size of the main body of the image forming apparatus as compared with the monochrome image forming apparatus.

  The shape of the container having a convex portion in the laser light path space and increasing the toner capacity is such that when the image forming operation is not performed, the convex portion of the toner container is a waste toner container in the separating operation for separating the developing roller and the photosensitive member. Therefore, there is a problem that it is difficult to secure a sufficient amount of separation.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and extend the life of a process cartridge by increasing the toner capacity and the waste toner capacity without increasing the occupied capacity of the process cartridge in the image forming apparatus main body.

  A first configuration for realizing the object of the present invention is to provide a developing container having a drum-shaped photosensitive member and a means for developing a latent image formed on the photosensitive member, and supplying toner to the developing container. A developing unit having a toner container for cleaning, a means for stripping off toner remaining on the photosensitive member, and a cleaning unit having a waste toner container for storing the stripped toner sandwich the laser light path space. In the process cartridges arranged above and below, the width of the optical path space formed by the developing unit and the cleaning unit in the sub scanning line direction has a region that becomes narrower before the laser beam reaches the drum irradiation position. Yes. In such a container shape, the volume of the toner container and the waste toner container can be increased without increasing the occupation capacity of the process cartridge in the main body of the image forming apparatus. Accordingly, since a large amount of toner and waste toner can be accommodated, the life of the process cartridge can be extended.

  A second configuration for realizing the object of the present invention is to provide a developing container having a drum-shaped photosensitive member and a means for developing a latent image formed on the photosensitive member, and supplying toner to the developing container. A developing unit having a toner container for cleaning, a means for stripping off toner remaining on the photosensitive member, and a cleaning unit having a waste toner container for storing the stripped toner sandwich the laser light path space. In the process cartridges arranged above and below, the width of the optical path space formed by the developing unit and the cleaning unit in the sub-scanning line direction is narrowed until the laser beam reaches the drum irradiation position. In such a container shape, by reducing the height of the waste toner container by an amount corresponding to the cross-sectional area of the waste toner container increased to the optical path space side, the sectional area of the entire waste toner container, that is, the waste toner capacity is changed. Therefore, the capacity of the toner container can be increased. As a result, the life of the process cartridge can be extended and the external shape can be further reduced.

  Embodiments of a process cartridge and a color electrophotographic image forming apparatus according to the present invention will be described with reference to FIGS.

(Overall configuration of image forming apparatus)
First, the overall configuration of the image forming apparatus will be described with reference to FIG. The image forming apparatus 100 shown in FIG. 2 has four process cartridge mounting portions (not shown) arranged in parallel in the vertical direction. Each of the cartridges 7 mounted on the mounting portion includes one electrophotographic photosensitive drum (1a to 1d). The photosensitive drum 1 is rotatably supported by a cleaning frame 51 serving as a first frame, and is driven to rotate counterclockwise in the drawing by a driving unit (not shown). Around the photosensitive drum 1, the following components are arranged in order according to the rotation direction. A charging unit (2a to 2d) for uniformly charging the surface of the photosensitive drum 1, a scanner unit (3a to 3d) for forming an electrostatic latent image on the photosensitive drum 1 by irradiating a laser beam based on image information, the static unit A developing unit (4a to 4d) as a second frame for developing the electrostatic latent image using toner as a developer, and an electrostatic transfer means 5 for transferring the toner image on the photosensitive drum 1 to the recording medium S. Cleaning members (6a to 6d) for removing the toner remaining on the surface of the photosensitive drum 1 after the transfer are disposed. Here, the photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 50 are integrated into a cartridge to form a process cartridge 7.

  The photosensitive drum 1 is obtained by coating an organic photoconductive layer (OPC photosensitive member) on the outer peripheral surface of an aluminum cylinder having a diameter of 30 mm, for example. Both ends of the photosensitive drum 1 are rotatably supported by support members. A driving force from a driving motor (not shown) is transmitted to one end. As a result, the photosensitive drum 1 is driven to rotate counterclockwise. As the charging means 2, a contact charging type as shown in FIG. 3 is used. The charging member is a conductive roller formed in a roller shape, and this roller is brought into contact with the surface of the photosensitive drum 1. Then, a charging bias voltage is applied to this roller. As a result, the surface of the photosensitive drum 1 is uniformly charged.

  The scanner unit 3 is arranged in a substantially horizontal direction of the photosensitive drum 1. Then, image light corresponding to an image signal is irradiated to polygon mirrors 9a to 9d rotated by a scanner motor (not shown) by a laser diode (not shown). The image light reflected by the mirror 9 selectively exposes the charged surface of the photosensitive drum 1 through the imaging lenses 10a to 10d. Thereby, an electrostatic latent image corresponding to the image signal is formed.

  As shown in FIG. 3, the developing unit 4 includes a toner container 41a containing yellow toner, a toner container 41b containing magenta toner, a toner container 41c containing cyan toner, and a black toner container. A toner container 41d containing toner and a developing frame 45 are provided. The toner is fed into the toner supply roller 43 by the toner transport mechanism 42 in the toner container 41. Then, toner is applied to the outer periphery of the developing roller 40 by the roller 43 and the developing blade 44 pressed against the outer periphery of the developing roller 40 as a developing member, and an electric charge is applied to the toner. Then, a latent image formed on the photosensitive drum 1 is developed by applying a developing bias to the developing roller 40. The developing roller 40 is disposed to face the photosensitive drum 1.

On the other hand, as shown in FIG. 2, the image forming apparatus is provided with an electrostatic transfer belt 11 that circulates and moves so as to face and contact all the photosensitive drums 1a to 1d. The transfer belt 11 is a film-like member having a volume specific resistance of 10 ¹¹ to 10 ¹⁴ Ω · cm and a thickness of about 150 μm. Then, the recording medium S is conveyed to the transfer position by the transfer belt 11 and the toner image on the photosensitive drum 1 is transferred.

  Transfer rollers 12a to 12d are arranged in parallel at positions facing the inside of the transfer belt 11 and facing the four photosensitive drums 1a to 1d. A positive charge is applied from the transfer roller 12 to the recording medium S via the transfer belt 11. As a result, the toner image on the photosensitive drum 1 is transferred to the recording medium S. The transfer belt 11 is stretched by four rollers, that is, a driving roller 13, driven rollers 14a and 14b, and a tension roller 15, and rotates (in the direction of the arrow in the figure). As a result, the transfer belt 11 circulates and the toner image is transferred while the recording medium S is conveyed from the driven roller 14a side to the drive roller 13 side.

  The feeding unit 16 feeds and transports the recording medium S to the image forming unit. A plurality of recording media S are stored in the feeding cassette 17. At the time of image formation, the feeding roller 18 and the registration roller pair 19 are driven and rotated according to the image forming operation. Thus, the recording medium S in the cassette 17 is separated and fed one by one. The leading edge of the recording medium S hits the roller pair 19 and stops temporarily. The recording medium S is fed to the transfer belt 11 by a pair of registration rollers 19 in synchronization with the rotation of the transfer belt 11 and the toner image.

  The fixing unit 20 fixes the toner images of a plurality of colors transferred to the recording medium S. The heating roller 21a rotates, and a pressure roller 21b that applies pressure and heat to the recording medium S in pressure contact therewith. That is, the recording medium S to which the toner image on the photosensitive drum 1 is transferred is conveyed by the fixing roller pair 21 when passing through the fixing unit 20. Then, heat and pressure are applied by the fixing roller pair 21. As a result, the toner images of a plurality of colors are fixed on the surface of the recording medium S.

  The image forming operation is as follows. First, the cartridges 7a to 7d are sequentially driven in accordance with the image formation timing. Then, the photosensitive drums 1a to 1d are rotationally driven according to the drive. Then, the scanner units 3 corresponding to the respective cartridges 7 are sequentially driven. By this driving, the charging unit 2 applies a uniform charge to the peripheral surface of the photosensitive drum 1. The unit 3 exposes the circumferential surface of the photosensitive drum 1 in accordance with an image signal to form an electrostatic latent image on the photosensitive drum 1. The developing roller 40 develops the electrostatic latent image.

  As described above, the toner images on the photosensitive drums 1 are sequentially transferred onto the recording medium S by the electric field formed between the photosensitive drums 1 and the transfer rollers 12. The recording medium S to which the four color toner images are transferred is separated from the transfer belt 11 by the curvature of the driving roller 13. Then, it is carried into the fixing unit 20. After the toner image is heat-fixed by the fixing unit 20, the recording medium S is discharged from the discharge unit 24 to the outside of the main body by the discharge roller pair 23.

(Process cartridge)
Next, a process cartridge embodying the present invention will be described. FIG. 3 is a main cross section of the cartridge 7 containing the toner. The cartridge 7a containing yellow toner, the cartridge 7b containing magenta toner, the cartridge 7c containing cyan toner, and the cartridge 7d containing black toner have the same configuration.

  The cartridge 7 (7a to 7d) includes a cleaning unit 50 as a first frame including the photosensitive drum 1 (1a to 1d), the charging unit 2 (2a to 2d), and the cleaning member 6 (6a to 6d). (50a to 50d) and a developing unit 4 (4a to 4d) as a second frame having developing means.

  In the cleaning unit 50, the photosensitive drum 1 is rotatably attached to the cleaning frame 51. As described above, the charging unit 2 and the cleaning member 6 are disposed on the circumference of the photosensitive drum 1. Further, the residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 is sent to the waste toner container 53 by the toner feeding mechanism 52. The waste toner container is formed integrally with the cleaning unit.

  Then, as shown in FIG. 4, the driving force of a driving motor (not shown) is transmitted to the cleaning unit 50 via the coupling member 70, so that the photosensitive drum 1 is rotationally driven according to the image forming operation. Further, the cleaning frame 51 is provided with a cartridge rotation stopper 51a as a main body positioning boss for preventing the process cartridge from rotating due to its own weight or a moment due to a driving force within the main body of the image forming apparatus. The cleaning frame 51 is provided with a shutter member 72 for protecting the photosensitive drum and a shutter receiving member 73 for opening and closing the shutter member by a link operation.

  Next, as shown in FIG. 5, the development unit 4 transmits the drive from the drive motor to the development drive gear 71 and transmits the drive to the development roller 40 through a drive train (not shown). The developing roller 40 is rotatably supported by the developing frame 45 via a bearing member. Further, as described above, the toner supply roller 43 and the developing blade 44 are arranged on the circumference of the developing roller 40. Further, in the toner container 41, a toner transport mechanism 42 for stirring the stored toner and transporting it to the roller 43 is provided.

  The developing unit 4 has a suspended structure that is rotatably supported with respect to the cleaning unit 50. That is, the developing unit 4 is provided with holes 47a and 48a which are provided in bearing members 47 and 48 attached to both ends of the unit 4, respectively. The shafts are fitted into the cleaning frame 51 in the holes. 62 and 63 are inserted, and the developing unit 4 is rotatably attached to the cleaning unit 50.

  The laser light L emitted from the scanner unit passes through the space formed between the cleaning unit and the developing unit shown in FIG. 3 and reaches the exposure surface of the photoreceptor. As shown in the figure, assuming that the scanner unit side is A and the photosensitive drum side is B in the laser light path space, the width S of the light path space has a narrowing region in the laser light path space AB. The width S of the optical path space takes into account the dimensional tolerances of the toner container and the waste toner container. Even if the outer frame of the toner container and the waste toner container is formed large within the dimensional tolerance, the container itself emits laser light. There is no blocking. The broken lines in the figure show the inner shapes of the conventional toner container and the waste toner container. By reducing the width S of the laser light path space, the cross-sectional area of the toner container and the waste toner container is increased. In the process cartridge using the shape of the present invention, the amount of toner that can be filled in the toner container and the amount of waste toner that can be stored in the waste toner container can be increased in the entire longitudinal direction of the process cartridge without increasing the external shape. . Therefore, the life of the process cartridge can be extended. Further, in the container shape as in the present embodiment, when the developing roller 40 and the photosensitive member 1 are separated from each other around the hole provided in the bearing members 47 and 48, the toner container and the waste toner container on the scanner unit side A are used. Therefore, a necessary and sufficient amount of separation can be ensured.

  Further, as means for increasing the volume of the toner container and the waste toner container on the laser optical path space side, the container shape facing the optical path space of the toner container and the waste toner container has a width S in the entire area AB. The configuration shown in FIG. 8 to be narrowed, or the configuration shown in FIG. 11 in which the container shape is substantially parallel to the light beam condensed in the sub-scan line direction of the laser light may be used. Further, in each configuration, there are also the configurations of FIGS. 7, 10, and 13 in which the capacity of only the waste toner container is increased as necessary, and the configurations of FIGS. 6, 9, and 12 in which the capacity of only the toner container is increased. Increasing the waste toner capacity is effective as an improvement measure when the waste toner container is full and the process cartridge needs to be replaced before all the toner in the toner container is consumed.

  In any configuration, the life of the process cartridge can be extended without increasing the external shape of the process cartridge.

  FIG. 14 shows a second embodiment for extending the life of the process cartridge. The same members as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The toner container 41 for supplying the toner to the developing container and the waste toner container 53 for storing the waste toner have a region in the laser light path space AB that narrows the width of the laser light path space in the sub scanning line direction. Yes. In the waste toner container 53, the height h of the waste toner container is lowered by an amount corresponding to the cross-sectional area increased toward the laser beam path space side so that the entire cross-sectional area of the waste toner container does not change. As a result, the life of the process cartridge can be extended by increasing the toner capacity, and the process cartridge can be reduced in size by suppressing the height of the waste toner container without changing the waste toner capacity.

It is sectional drawing which shows the structure of the conventional process cartridge. 1 is an overall configuration diagram of a color electrophotographic image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a cross-sectional explanatory view of a process cartridge according to the first embodiment of the present invention. 1 is a perspective view of a process cartridge according to a first embodiment of the present invention. FIG. 2 is a perspective view of a developing unit according to the first embodiment of the present invention. It is sectional explanatory drawing of the process cartridge of the 2nd Example in this invention. It is sectional explanatory drawing of the process cartridge of the 3rd Example in this invention. It is sectional explanatory drawing of the process cartridge of the 4th Example in this invention. It is sectional explanatory drawing of the process cartridge of the 5th Example in this invention. It is sectional explanatory drawing of the process cartridge of the 6th Example in this invention. It is sectional explanatory drawing of the process cartridge of the 7th Example in this invention. It is sectional explanatory drawing of the process cartridge of the 8th Example in this invention. It is sectional explanatory drawing of the process cartridge of the 9th Example in this invention. It is a figure which extends the lifetime of the process cartridge of the 2nd Example in this invention.

Explanation of symbols

C contact position S recording medium t developer 1 (1a to 1d) electrophotographic photosensitive drum 2 (2a to 2d) charging means 3 (3a to 3d) scanner unit 4 (4a to 4d) developing unit (second frame)
5 Electrostatic transfer means 6 Cleaning member 7 (7a-7d) Process cartridge 8 (8a-8d) Force applying member (separating means)
9 (9a to 9d) Polygon mirror 10 (10a to 10d) Imaging lens 11 Electrostatic transfer belt 12a to 12d Transfer roller 13 Drive roller 14 Driven roller 15 Tension roller 16 Paper feed unit 17 Feed cassette 18 Feed roller 19 Resist Roller 20 Fixing portion 21 Fixing roller 21b Pressure roller 23 Discharge roller 24 Discharge portion 40 Developing roller (developing member)
41 (41a to 41d) Toner container 41a Toner discharge port 42 Toner transport mechanism 43 Toner supply roller 44 Developing blade 45 Developing frame 45a Developing chamber 47 Bearing member (main body driving side)
47a hole 47b force receiving portion 48 bearing member (main body non-drive side)
48b Force receiving portion 49 Side cover 50 Cleaning unit (first frame)
51 Cleaning frame 52 Toner feeding mechanism 53 Waste toner chamber 64 Bearing 70 Coupling member 71 Development drive gear 72 Shutter member 73 Shutter receiving member 100 Image forming apparatus L Laser beam

Claims (8)

In a process cartridge detachable from the image forming apparatus, a drum-shaped electrophotographic photosensitive member;
A developing container having developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive member;
A developer storage section for storing a developer for supplying the developer to the developer container;
A used developer storage unit for storing the developer peeled off from the photosensitive member, and the developer storage unit and the used developer storage unit are arranged to face each other with a laser beam path therebetween. In the process cartridge
The width of the optical path space formed by the developer accommodating portion and the used developer accommodating portion in the sub-scanning line direction has a region that becomes narrow before the laser beam reaches the irradiation position on the photosensitive member. A process cartridge characterized by   2. The process cartridge according to claim 1, wherein at least one of the developer accommodating portion and the used developer accommodating portion has a region approaching a light beam in a sub-scanning line direction of laser light. .   2. The optical path space formed by the developer storage section and the used developer storage section according to claim 1, wherein the optical path space is formed substantially parallel to a light beam in a sub-scanning line direction of a laser beam irradiated on the photoconductor. Process cartridge characterized by being made.   4. The process cartridge according to claim 3, wherein at least one of the developer accommodating portion and the used developer accommodating portion is formed substantially parallel to a light beam in a sub-scanning line direction of laser light.   5. The process cartridge according to claim 1, wherein the process cartridge is a charging unit or a cleaning unit, a developing unit, and an electrophotographic photosensitive member integrated into a cartridge, and the cartridge can be attached to and detached from the image forming apparatus main body. The process cartridge according to one.   5. The process cartridge according to claim 1, wherein at least one of a charging unit and a cleaning unit, a developing unit, and an electrophotographic photosensitive member are integrally formed into a cartridge so that the process cartridge can be attached to and detached from the image forming apparatus main body. The described process cartridge.   5. The process cartridge according to claim 1, wherein the developing unit and the electrophotographic photosensitive member are integrally formed into a cartridge so that the process cartridge is removable from the main body of the image forming apparatus. 8. An electrophotographic image forming apparatus comprising: mounting means for detachably mounting the process cartridge according to claim 5; and transport means for transporting a recording medium.

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