Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2000-05-25
2001-08-28
Grimley, Arthur T. (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S061000
Reexamination Certificate
active
06282384
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus which forms an electrostatic latent image on an electrophotographic photosensitive member through an electrophotographic process and visualizes the electrostatic latent image with a developer contained in a developing device, and more particularly to an electrophotographic image forming apparatus having developer amount detecting means capable of sequentially detecting the remaining amount of developer contained in a developer container, a process cartridge and a developing device,.
The electrophotographic image forming apparatus is directed to, for example, an electrophotographic copying machine, an electrophotographic printer such as an LED printer or a laser beam printer, an electrophotographic facsimile machine and an electrophotographic word processor.
The process cartridge makes at least one of charging means, developing means and cleaning means and an electrophotographic photosensitive member integrally into a cartridge which is detachably mountable to a main body of the electrophotographic image forming apparatus, or makes at least the developing means and the electrophotographic photosensitive member integrally into a cartridge which is detachably mountable to a main body of the electrophotographic image forming apparatus.
2. Related Background Art
Up to now, in an image forming apparatus using an electrophotographic image forming process, there has been applied a process cartridge system which makes the electrophotographic photosensitive member and process means that acts on the electrophotographic photosensitive member integrally into a cartridge which is detachably mountable to a main body of the electrophotographic image forming apparatus. The process cartridge system can remarkably improve the operability since the maintenance of the apparatus can be conducted by a user per se not depending on a service man. For that reason, the process cartridge system has been widely employed in the electrophotographic image forming apparatus.
In one type of the electrophotographic image forming apparatuses of the above process cartridge system, a user per se can exchange the cartridge. Therefore, there includes one having means for informing the user of a fact that the developer has been consumed, that is, a developer amount (presence and absence) detecting device.
The details will be further described.
FIG. 14
shows an example of an image forming apparatus A to which a conventional process cartridge B is mounted. A developing device
10
which constitutes developing means by the process cartridge B includes a developer container
11
having a developing portion
13
which supplies a developer T to a latent image formed on a photosensitive drum
1
serving as an image bearing member to visualize the latent image and a hopper portion
14
provided for the purpose of reserving and storing the developer T. Then, the developer T within the hopper portion
14
is fed to the developing portion
13
from the interior of the hopper portion
14
through the gravity and an agitating device
15
or other developer feeding means.
In the developing portion
13
, a developing roller
12
that serves as a developer bearing member for feeding the developer T up to a developing position opposite to the photosensitive drum
1
is disposed in the vicinity of the photosensitive drum
1
. The developer T is stuck and borne on the surface of the developing roller
12
, and the developer T is fed up to the developing position opposite to the photosensitive drum
1
due to the rotation of the developing roller
12
.
The amount and height of the developer T are regulated and uniformly coated on the developing roller
12
by developer regulating means
17
such as a doctor blade while the developer T is being fed. The developer T is rubbed by the developing roller
12
, the developer regulating means
17
or the developer T per se so as to be charged during a process where the developer T is fed onto the developing roller
12
.
Then, the developer T fed to a portion of the developing roller
12
opposite to the photosensitive drum
1
by the developing roller
12
, that is, to a developing position in which the developer T is transferred onto the photosensitive drum
1
due to an appropriate developing bias voltage applied between the photosensitive drum
1
and the developing roller
12
by a developing bias power supply
12
A which serves as bias applying means, and an electrostatic latent image on the photosensitive drum
1
is then developed to form a toner image.
The developer T which has not been used for development is fed while it remains on the developing roller
12
, and then again contained in the developing portion
13
.
On the other hand, a recording medium P set in a sheet feeding cassette
20
is conveyed to a transfer position by a pickup roller
21
and conveying means
22
having a conveying roller pair, a registration roller (not shown) and so on in synchronism with the formation of the toner image. A transfer roller
4
is disposed as transfer means at the transfer position, and the toner image on the photosensitive drum
1
is transferred onto the recording medium P by application of a voltage.
The recording medium P to which the toner image has been transferred is conveyed to fixing means
5
by a conveying guide
23
. The fixing means
5
includes a driving roller
5
c
and a fixing roller
5
a
having a heater
5
b
therein which applies heat and pressure to the recording medium P which is passing through the fixing means
5
to fix the transferred toner image onto the recording medium P. Thereafter, the recording medium P is discharged to the external of the apparatus.
The photosensitive drum
1
after the toner image thereon has been transferred onto the recording medium P by the transfer roller
4
, is subjected to a succeeding image forming process after the developer remaining on the photosensitive drum
1
has been removed by cleaning means
6
. The cleaning means
6
scrapes off the residual developer on the photosensitive drum
1
by an elastic cleaning blade
7
disposed so as to be abutted against the photosensitive drum
1
and collects the residual developer into a waste developer reservoir
8
.
As described above, in the developing device
10
, because the developer T is consumed every time the developing operation is repeated, it is necessary to monitor the presence and absence of the developer T in the developing portion
13
at any time so as to prevent the shortage of the developer T.
Since the developer T is contained within the developer container
11
of the developing device
10
, the user cannot recognize the residual amount of developer T from the outside using his eyes.
Under the above circumstances, the conventional developing device
10
includes a developer amount detecting device as near-end detection means for detecting the residual amount of the developer, and the developer amount detecting device includes a bar-shaped antenna electrode
18
for detection of the residual amount of the developer which is disposed horizontally in the interior of the developing portion
13
in order to detect the residual amount of the developer T.
As described above, there has been applied a system in which an alternate (a.c.) bias voltage from the developing bias power supply
12
A is applied to the developing roller
12
when the image is formed, and in this situation, the developer amount detecting device detects an electric current that flows in the antenna electrode
18
by the a.c. bias voltage. That is, the detection of the developer residual amount utilizes a change in the capacitance due to the amount of developer that is interposed between the developing roller
12
and the antenna electrode
18
.
That is, the current that flows in the antenna electrode
18
gradually changes as the developer T contained in the developer container
11
is gradually consumed every time an image is formed. Therefore, when its value reaches a
Saito Seiji
Sakai Hiroaki
Shimura Masaru
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Grimley Arthur T.
Ngo Hoang
LandOfFree
Developing device, process cartridge and electrophotographic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Developing device, process cartridge and electrophotographic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Developing device, process cartridge and electrophotographic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2530621