Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2001-11-06
2003-08-05
Royer, William J. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S120000, C399S262000
Reexamination Certificate
active
06603940
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a detachable process cartridge for use in image forming apparatuses, such as copying machines, printers and facsimile machines, and also relates to image forming apparatuses using this process cartridge.
2. Description of the Prior Art
Image forming apparatuses, such as copying machines, printers and facsimile machines, form an image through an exposure process of forming an electrostatic latent image by exposure of the surface of a photoreceptor, such as a photosensitive drum and a photosensitive belt, to light; a development process of visualizing the formed electrostatic latent image by deposition of toner; a transfer process of transferring a toner image formed on the photoreceptor surface by development to a predetermined sheet; and a fixing process of fixing the toner image transferred to the sheet by application of heat. The above exposure, development and transfer processes are sequentially carried out at an exposure section, a development section and a transfer section, respectively, which are provided on the periphery of the photoreceptor. Moreover, a cleaning section for removing toner remaining on the photoreceptor surface after the transfer process and a charging section for uniformly charging the surface before exposure are provided on the periphery of the photoreceptor.
Image forming apparatuses of this type are mainly classified into two kinds of structures according to the maintenance methods. The first structure is a CRU (Customer Replaceable Unit) structure whose maintenance is performed mostly by the user. The second structure is an SRU (Serviceman Replaceable Unit) structure whose principal maintenance is carried out by a special serviceman.
In an image forming apparatus of the CRU structure, many of the process means, such as the above-mentioned development section, charging section and cleaning section, for performing the respective processes with respect to the photoreceptor are constructed as cartridges (process cartridges) which are attachable and detachable to/from the periphery of the photoreceptor in the main body of the apparatus. When some troubles occur in the processes, corresponding process cartridges are detached. Minor troubles are solved by making simple adjustments. On the other hand, when a severe trouble occurs, a corresponding cartridge as a unit is replaced.
In recent years, composite type image forming apparatuses having all the functions as a copying machine, printer and facsimile machine rather than an exclusive function of such an individual device have been put into practical application. This type of image forming apparatus is an apparatus for personal use designed for use by a person or a small number of people. Further, in order to improve the usability related to maintenance, this type of image forming apparatus often adopts the CRU structure.
Here, the development section for the development process is constructed by a development roller that is adjoined the surface of the photoreceptor to face the photoreceptor and rotates about an axis parallel to the surface, and agitating means provided on the side opposite to the development roller. The development roller is a magnet roller incorporating a magnet. Toner for use in development is mixed with a carrier made of a magnetic powder and agitated by the action of the agitating means, and the resultant mixture is used as a developer. The toner is deposited on the entire surface of the development roller and transferred to a section opposing the photoreceptor. The toner is attracted and moved to an electrostatic latent image formed on the surface of the photoreceptor, thereby forming a toner image.
In the above-described image forming apparatus of the CRU structure, the process cartridge of the development section is constructed by integrating a development unit comprising the development roller and agitating means and a toner unit including a container for containing toner for development and toner supply means as disclosed in Japanese Patent Application Laid-Open Nos. 5-197227/1993 and 2-141777/1990. When the toner is run out by repetition of the development process, the toner is readily replaceable by replacing the cartridge as a unit.
On the other hand, in an image forming apparatus of the SRU structure, many of process means including the development section are highly accurately positioned and fixed on the periphery of the photoreceptor in the main body of the apparatus. This structure has been widely adopted by image forming apparatuses, such as apparatuses serving as copying machines exclusively, which are designed to meet a demand for supply of a large volume of good quality printed matter at a low unit cost. Besides, image forming apparatuses of the SRU structure can handle various kinds of troubles by adjustments and replacement of the respective process means which are carried out by periodical maintenance work of special servicemen, thereby keeping good image quality for a long time.
Note that, even in such an image forming apparatus of the SRU structure, replacement of toner in the development section is necessary. In this case, toner replacement is performed by detaching the fixed toner unit comprising the toner containing space and the toner supply means from the development section.
By the way, in order to shorten the development period and rationalize the design aspect, attempts to share major process means between the above-described image forming apparatuses of the CRU structure and image forming apparatuses of the SRU structure have been conventionally made. Various types of sharable process means have been prepared for each process means so that they are selected according to the applications and purposes and combined for use.
However, regarding the development section for the development process, if the process means is to be shared between the apparatuses of the CRU structure in which the development unit and the toner unit are coupled as an integrated device as described above and the apparatuses of the SRU structure in which these units need to be separated, then the structure relating to the separation/coupling becomes complicated. Moreover, there are problems that complicated manufacturing processes and an increase in the manufacturing cost would result from problems associated with accuracy.
Furthermore, in image forming apparatuses of the SRU structure, a complicated attachment/detachment structure of the toner unit with respect to the fixed development unit is unavoidable, resulting in a problem that the user is forced to carry out complicated processes to replace the toner.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made with the aim of solving the problems. An object of the present invention is to provide a process cartridge capable of certainly achieving separation/coupling of a development unit and a toner unit with a simple structure and realizing sharing of a development section between the CRU structure and the SRU structure with high accuracy without making the manufacturing processes complicated or increasing the manufacturing costs. It is also an object of the present invention to provide an image forming apparatus implemented using this process cartridge.
A process cartridge according to the present invention comprises: a toner unit including a toner containing space and a toner supply section; a development unit including a developing device; and a holding frame including a fixture section for the development unit and an accepting section for the toner unit, and is characterized in that the process cartridge is constructed selectively in a first arrangement in which the toner unit is fixed in a predetermined position in the accepting section of the holding frame or in a second arrangement in which the toner unit is detachably installed in the predetermined position.
In this invention, the development unit is fixed, the holding frame having an accepting section for the toner unit is provided, and the toner unit is fixed in the acceptin
Funayama Naotaka
Kimura Takahiko
Nagata Tsutomu
Sanada Yoshiaki
Yamaguchi Jun
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