Electrophotography – Image formation – Development
Reexamination Certificate
2001-12-11
2004-07-20
Brase, Sandra L (Department: 2852)
Electrophotography
Image formation
Development
C399S119000, C399S254000, C399S260000
Reexamination Certificate
active
06766132
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a developing device mounted on an image forming apparatus such as a copier or a laser beam printer adopting the electrophotographic process.
2. Description of Related Art
In an electrophotographic image forming apparatus using the electrophotographic image forming process, there has heretofore been adopted a process cartridge system in which an electrophotographic photosensitive drum and process means for acting on the electrophotographic photosensitive drum are integrally made into a cartridge which is detachably mountable on the main body of the image forming apparatus. According to this process cartridge system, a user himself can effect the maintenance of the apparatus without resort to a serviceman and therefore, operability could be markedly improved. So, this process cartridge system is widely used in electrophotographic image forming apparatuses.
A process cartridge comprises at least developing means and a photosensitive drum integrally made into a cartridge detachably mountable on the main body of an image forming apparatus, and there is also a process cartridge further comprising a developer container, charging means, cleaning means, etc. constructed integrally with one another.
FIG. 16
of the accompanying drawings illustrates an image forming apparatus according to the prior art. In
FIG. 16
, a process cartridge
100
comprises a photosensitive drum
101
which is an image bearing member, a developing device
103
, a cleaning device
105
, a charging member
106
and a toner container
109
which is a developer container, all being constructed integrally with each other. The image forming apparatus also has an exposing device
102
, a transferring device
104
, a fixing device
107
and a feeding device
108
.
The exposing device
102
applies a laser beam L conforming to image information to the surface of the photosensitive drum
101
charged to predetermined potential by the charging member
106
, and eliminates charges therefrom to thereby form an electrostatic latent image on the photosensitive drum
101
.
An agitating member
110
is provided in the toner container
109
, and prevents the coagulation of a developer (hereinafter referred to as the toner) and also carries the toner to the developing device
103
. The developing device
103
develops the electrostatic latent image on the photosensitive drum
101
by a developing sleeve
111
to thereby form a toner image. The formed toner image is transferred to the surface of a transferring material fed by the feeding device
108
, and is heated and pressurized by the fixing device
107
, whereby it is permanently fixed, and the transferring material is discharged out of the apparatus. On the other hand, any toner, paper dust, etc. residual on the photosensitive drum
101
after the transfer are removed by the cleaning device
105
.
Now, with the higher speed of the image forming apparatus in recent years, the higher-speed countermeasure and higher durability of the process cartridge
100
have been required and therefore, the amount of toner filling a process cartridge
100
has become great and the toner container
109
itself also has become large. However, the increase in the amount of filling toner gives rise to the problem that in the conventional container construction, the rising time of the toner (reaching a predetermined charging amount necessary for development) becomes long, that is, much time is required until a proper amount of development is reached.
As shown in
FIG. 17
of the accompanying drawings, the toner in the toner container
109
is charged by contacting with the developing sleeve
111
, and any toner which has not been used for development returns into the toner container
109
. When the amount of filling toner becomes great, the occasion on which the toner in the toner container
109
contacts with the developing sleeve
111
decreases and therefore, much time is required until all the toner in the toner container
109
reaches a predetermined charging amount.
FIG. 18
of the accompanying drawings shows the relationship between the number of formed images and the amount of toner used for development (the amount of development per unit time: M/S: mass/sheet, unit mg/cm
2
) when the toner container is filled with 1500 g of toner to ensure, for example, recording of 30,000 sheets. As shown, when the conventional construction of the toner container
109
was filled with 1500 g of toner, 15,000 sheets of image formation were required until a proper amount of development was reached. At this time, the toner in the process cartridge
100
circulates greatly in the toner container
109
, as shown in FIG.
17
.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-noted problems and an object thereof is to provide a developing device which is stable in its developing characteristic from the initial stage of use.
Another object of the present invention is to provide a developing device of large capacity which is excellent in its developing characteristic.
Still another object of the present invention is to provide a developing device comprising:
a developer bearing member; and
a developer container for containing a developer therein, the developer container having a plurality of developer containing rooms (chambers) provided with developer conveyers for conveying the developer toward the developer bearing member;
wherein the rotational speed of the developer conveyer in the room (chamber) nearest to the developer bearing member is higher than that of the developer conveyers in the other rooms (chambers).
Yet still another object of the present invention is to provide a developing device comprising:
a developer bearing member; and
a developer container for containing a developer therein, the developer container having a plurality of developer containing rooms (chambers) provided with developer conveyers for conveying the developer toward the developer bearing member;
wherein the volume of the room (chamber) nearest to the developer bearing member is smaller than that of the other rooms (chambers).
a further object of the present invention is to provide a developing device comprising:
a developer bearing member; and
a developer container for containing a developer therein, the developer container having a plurality of developer containing rooms (chambers) provided with sheet-shaped developer conveyers for conveying the developer toward the developer bearing member;
wherein the thickness of the developer conveyer in the room (chamber) nearest to the developer bearing member is smaller than that of the developer conveyers in the other rooms (chambers).
Still a further object of the present invention is to provide a developing device comprising:
a developer bearing member; and
a developer container containing a developer therein, the developer container having a plurality of developer containing rooms (chambers) provided with sheet-shaped developer conveyers for conveying the developer toward the developer bearing member;
wherein the Young's modulus of the developer conveyer in the room (chamber) nearest to the developer bearing member is smaller than that of the developer conveyers in the other rooms (chambers).
Further objects of the present invention will become apparent from the following detailed description when read with reference to the accompanying drawings.
REFERENCES:
patent: 5077583 (1991-12-01), Bhagat
patent: 5287151 (1994-02-01), Sugiyama
patent: 5495320 (1996-02-01), Araki et al.
patent: 5857134 (1999-01-01), Ahn
patent: 5943537 (1999-08-01), Ahn
patent: 6336022 (2002-01-01), Ichikawa et al.
patent: 3-172873 (1991-07-01), None
patent: 4-115268 (1992-04-01), None
patent: 04-115269 (1992-04-01), None
patent: 08-0629958 (1996-03-01), None
Kawamura Takeshi
Sakai Hiroaki
Brase Sandra L
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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