Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2003-03-24
2004-12-14
Chen, Sophia S. (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S090000
Reexamination Certificate
active
06832057
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a developing device, a process cartridge, and an electrophotographic image forming apparatus, which include developer-amount detecting means capable of successive detection of the residual amount of a developer.
In this specification, the term “electrophotographic image forming apparatus” refers to a structure that uses an electrophotographic image-forming system to form an image on a recording medium. Examples of the electrophotographic image forming apparatus include electrophotographic copying machines, electrophotographic printers (such as laser beam printers and LED printers), facsimile machines, and word processors.
Also, the term “process cartridge” refers to a cartridge into which at least one of charging means, developing means, and cleaning means and an electrophotographic photosensitive drum are integrally formed and which is detachably mountable to an electrophotographic image forming apparatus main body. In particular, the term “process cartridge” also refers to a cartridge into which at least the developing means and the electrophotographic photosensitive drum are integrally formed and which is detachably mountable to the electrophotographic image forming apparatus main body.
2. Related Background Art
Up to now, an electrophotographic image forming apparatus using an electrophotographic image forming process has adopted a process-cartridge system in which an electrophotographic photosensitive member and process means for acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge is detachably mountable to an electrophotographic image forming apparatus main body. The process-cartridge system enables a user per se to perform the maintenance of the apparatus without relying on a service person, thereby making it possible to improve the operability remarkably. For that reason, the process-cartridge system is widely employed in electrophotographic image forming apparatuses.
Also, in such an electrophotographic image forming apparatus of the process-cartridge system, it is necessary that the user per se exchange the cartridges. Therefore, in order to inform the user that a developer is consumed, some of the electrophotographic image forming apparatuses are equipped with developer-amount detecting means. Examples of the developer-amount detecting means include one using a system in which a change in capacitance among plural electrodes arranged within the process cartridge is detected, to thereby detect the developer amount.
Some structures of the electrodes have plural electrode plates arranged so as to be opposed to each other in positions to which a developer can be admitted.
FIG. 2
is a cross sectional view showing an example of the conventional process cartridge having the developer-amount detecting means. Developing means
52
of a process cartridge
51
is provided with a first electrode
53
and a second electrode
54
which serve to detect the developer amount. The first electrode
53
and the second electrode
54
are arranged in a position to which toner as the developer can be admitted, and the capacitance between the electrodes is detected to thereby detect a toner amount successively.
FIG. 3
is a side view of the process cartridge
51
. On a side surface of the process cartridge
51
, an input contact
55
and an output contact
56
are provided. The input contact
55
is electrically connected to the first electrode
53
and serves to receive an input voltage from the image forming apparatus main body. The output contact
56
is electrically connected to the second electrode
54
and serves to send an output voltage corresponding to the toner amount to the image forming apparatus main body.
FIG. 4
shows an electrical circuit of the developer-amount detecting means.
A developer-amount detecting circuit
60
is composed of a detecting portion
64
, a developing-bias circuit
61
, a control circuit
62
, and an amplifying circuit
63
. The detecting portion
64
is composed of the first electrode
53
, the second electrode
54
, and a developing sleeve
57
, and induces a capacitance in order to detect the toner amount. The detecting portion
64
is provided to the process cartridge
51
.
On the other hand, the developing-bias circuit
61
, the control circuit
62
, and the amplifying circuit
63
are provided to the image forming apparatus main body.
The process cartridge
51
includes a developing-bias electrode
57
a
electrically connected to the developing sleeve
57
. The image forming apparatus includes an electrical contact
65
electrically connected to the developing-bias circuit
61
. When the process cartridge
51
is mounted to the image forming apparatus, the developing-bias electrode
57
a
and the electrical contact
65
that is provided to the image forming apparatus are electrically connected to each other, and a developing-bias voltage is applied to the developing sleeve
57
from the developing-bias circuit
61
of the image forming apparatus via the electrical contact
65
and the developing-bias electrode
57
a.
Also, provided on a side surface of a frame of the process cartridge
51
are the external input contact
55
and the external output contact
56
, which are to be electrically connected to the image forming apparatus. When the process cartridge
51
is mounted to the image forming apparatus main body, the external input contact
55
and the external output contact
56
contact an electrical contact
58
and an electrical contact
59
which are provided to the image forming apparatus, respectively.
The detecting portion
64
functions as an impedance element. The first electrode
53
, serving as an input side electrode that is one electrode of the detecting portion
64
is connected to the developing bias circuit
61
functioning as developing-bias application means via the developing-bias electrode
57
a.
The second electrode
54
, serving as an output-side electrode that is the other electrode of the detecting portion
64
, is connected to the control circuit
62
. In the above structure, the first electrode
53
is connected to the developing-bias circuit
61
via the external input contact
55
and the electrical contact
58
of the apparatus main body, and the second electrode
54
is connected to the control circuit
62
via the external output contact
56
and the electrical contact
59
of the apparatus main body.
As described above, the process cartridge and a developing device, which include the developer-amount detecting means are provided with an external input contact and an external output contact. The external input contact serves to receive an input voltage to be applied to developer-amount detecting electrodes from the image forming apparatus main body. The external output contact serves to send an output voltage corresponding to the capacitance between the detecting electrodes to the image forming apparatus main body. On the other hand, the image forming apparatus main body is provided with electrical contacts which are electrically connected to the above-discussed external contacts when the process cartridge or the developing device is mounted to the image forming apparatus main body.
As described above, it is necessary to provide the process cartridge or the developing device and the image forming apparatus main body with the external input contact and the external output contact. Thus, there is a fear that the contacts have complicated structures resulting in obstacles to the downsizing of the apparatus and the reduction in costs. Further, during the progress in downsizing the apparatus, there is also a fear that the degree of freedom in the arrangement of the contacts is reduced in order to achieve the complicated structures of the contacts.
SUMMARY OF THE INVENTION
The present invention has been made in order to solve the above-mentioned problem.
An object of the present invention is to provide a developing device, a process cartridge, an electrophotographic ima
Kikuchi Ken
Oguma Toru
Canon Kabushiki Kaisha
Chen Sophia S.
Fitzpatrick ,Cella, Harper & Scinto
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