Electrophotography – Cleaning of imaging surface – Blade
Reexamination Certificate
1999-06-30
2001-09-04
Royer, William J. (Department: 2852)
Electrophotography
Cleaning of imaging surface
Blade
C399S351000
Reexamination Certificate
active
06285851
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a cleaning apparatus employed by an image forming apparatus based on an electrophotographic system or an electrostatic recording system. It also relates to a process cartridge removably installable in an image forming apparatus.
An image forming apparatus, such as a printer, records an image on an image bearing member through the following steps: uniformly charging an image bearing member by a charging device; forming a latent image on the uniformly charged image bearing member by selectively exposing the image bearing member; developing the latent image into a visible image with the use of a developing device and developer, and transferring the developed (visual) image onto a piece of recording medium. After the image transfer, the developer which remains on the image bearing member is removed and collected into a cleaning means container by a cleaning blade, so that the following image formation cycle is carried out with the use of the same image bearing member with a clean surface.
In recent years, the maintenance for an image forming apparatus has been simplified with the employment of a cartridge system, according to which the aforementioned image bearing member, charging device, developer, cleaning means, waste developer bin, and the like are integrated in the form of a cartridge, which can be removably installed in the main assembly of an image forming apparatus so that the developer, or components such as the image bearing member, can be easily replaced by replacing the cartridge in the main assembly with a new cartridge. Further, as the service life of an image bearing member has become longer, that is, as the number of copies producable during the service life of a single image bearing member has increased, a cartridge such as the one described above has been separated into two independent units: a development means cartridge, and a drum cartridge, which can both be removably installed into the main assembly of an image forming apparatus as can the aforementioned process cartridge, so that the image forming apparatus can be easily maintained, and the main components can be replaced in accordance with the individual lengths of their service lives. The developing means cartridge is limited in terms of developer supply. The drum cartridge integrally comprises an image bearing member, and image processing means, that is, a charging means and a cleaning means. The waste developer, which is generated as the image bearing member is cleaned in the drum cartridge, is collected in a part of a cleaning means container (housing), the waste toner capacity of which is large enough to match the length of the service life of the image bearing member. Thus, the waste toner is removed from the main assembly as the drum cartridge is replaced with a fresh cartridge.
The cleaning means generally comprises a blade for removing the waste developer. The blade consists of a support portion formed of metallic plate, and an edge portion, that is, a contact portion formed of elastic material such as rubber. In order to clean the peripheral surface of the image bearing member, the blade is placed in contact with the peripheral surface of an image bearing member in such a manner that the blade hypothetically invades the peripheral surface of the image bearing member by a predetermined depth. If this depth in the hypothetical invasion is improper, the cleaning blade fails to properly clean the image bearing member, or is bent backward. Therefore, the depth of the hypothetical invasion must be very accurately maintained.
However, any change in the internal ambience of an image forming apparatus creates problems. For example, as the internal temperature of the apparatus fluctuates, the aforementioned hypothetical depth also fluctuates since the material of the housing in which the cleaning section is disposed expands or shrinks in response to the temperature fluctuation. This problem is more apparent if the housing is formed of resin. Further, this fluctuation in the depth of the hypothetical blade invasion also occurs due to the difference in coefficient of linear thermal expansion between the material (resin) of the housing and the material (metallic plate) of the cleaning blade. Further, the fluctuation in the depth of the hypothetical blade invasion sometimes occurs due to the microscopic deformation (for example, twisting) caused by external physical force, such as the force effected by the other members (for example, development sleeve or development roller) which also make contact with the image bearing member.
In order to prevent the occurrence of such change in the depth of the hypothetical blade invasion into the image bearing member, various attempts have been made. For example, material other than resin was used as the material for the housing, and/or the rigidity of the housing was increased by increasing the thickness of the housing wall or by the addition of ribs to the wall.
On the other hand, the trend has been to reduce the particle size of toner, that is, developer, to an extremely small size, in order to produce an extremely precise image. In order to remove such toner that is extremely small in particle diameter, with the same degree of efficiency as the efficiency with which toner of a conventional size is removed, the fluctuation of the aforementioned depth of hypothetical invasion of the cleaning blade must be reduced to a much lower level than the level in the past. In a situation such as this, the reduction in the fluctuation of the depth of the hypothetical invasion of the cleaning blade, which can be accomplished simply by increasing the rigidity of the cleaning means housing itself, is not enough to remove the recent toner composed of extremely small particles, as efficiently as the conventional toner can be removed.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide an image forming apparatus which employs a cleaning apparatus or a process cartridge in which the positional accuracy of the cleaning member relative to the cleaning means housing is prevented from fluctuating due to temperature fluctuation and/or external physical force.
Another object of the present invention is to provide a cleaning apparatus which comprises: a cleaning member for removing the residual toner on the image bearing member; a supporting portion to which said cleaning member is attached to be supported; and a reinforcement member, wherein said cleaning member supporting portion is formed of material different from the material of said cleaning member, and said reinforcement member is positioned so that the base portion of said cleaning member is sandwiched between said reinforcement member and said cleaning member supporting portion of the cleaning means housing.
Another object of the present invention is to provide a process cartridge which comprises: an image bearing member; a cleaning member for removing the residual toner on the image bearing member; a supporting portion to which said cleaning member is attached to be supported; and a reinforcement member, wherein said cleaning member supporting portion is formed of material different from the material of said cleaning member, and said reinforcement member is positioned so that the base portion of said cleaning member is sandwiched between said reinforcement member and said cleaning member supporting portion of the cleaning means housing.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4803752 (1989-02-01), Kasama
patent: 4969015 (1990-11-01), Sanpe
patent: 5363182 (1994-11-01), Kuribayashi et al.
patent: 5479250 (1995-12-01), Michlin
patent: 5517294 (1996-05-01), Ogiri et al.
patent: 0 703 511A2 (1996-03-01), None
patent: 62-9382 (1987-01-01), None
patent: 8-185098 (1996-07-01), None
Patent Abstracts of Japan
Kojima Hisayoshi
Mori Tomonori
Murayama Kazunari
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Royer William J.
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