Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2002-08-15
2004-11-09
Goodrow, John L (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S062000, C430S063000, C399S159000
Reexamination Certificate
active
06815134
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Patent Application No. 2002-6305, filed Feb. 4, 2002, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photoconductive drum in an image forming apparatus, which is adapted for use in an office machine, such as a color copier, color printer and the like, having a plurality of developing devices using electrophotography, and more particularly, to a photoconductive drum in an image forming apparatus and a method of forming the same, the photoconductive drum having an elastic layer formed between a cylindrical base body of the photoconductive drum and a photosensitive layer thereon to protect the cylindrical base body and the photosensitive layer, thereby to maintain a stable image quality and extend a life span of the photoconductive drum.
2. Description of the Related Art
Generally, an electrophotographic image forming apparatus used in an office machine, such as a color copier, color printer and the like, is provided with an organic photoconductive or photosensitive drum
11
which is rotated in one direction by a drum-driving source (not shown), as shown in FIG.
1
. Around a circumferential surface of the photoconductive drum
11
, a first charging device
12
, a laser scanning unit (LSU)
20
, four developing devices
31
,
32
,
33
,
34
containing developers of yellow, magenta, cyan, and black, respectively, an image-transferring part
60
, an optical discharging or quenching lamp
87
, and a cleaning-discharging part
80
are disposed in respective given positions along the rotating direction of the photoconductive drum
11
.
The first charging device
12
, such as a cyclotron-charging device, electrifies the photoconductive drum
11
, and the LSU
20
photo-exposes the photoconductive drum
11
in line shapes along an axial direction thereof through a light source, such as a semiconductor laser source.
Each of the developing devices
31
,
32
,
33
,
34
includes a development roller
13
, a developer reservoir
16
, a developer-supplying roller
15
, a developer layer-regulating member
51
regulating a thickness of a developer layer which is attached on the development roller
13
, and a regulating roller
61
,
62
,
63
, or
64
concentrically disposed on both ends of the development roller
13
. The components of each developing device
31
,
32
,
33
, or
34
are driven to be rotated by a developing device-driving source (not shown). The developer is supplied to the development roller
13
through the developer-supplying roller
15
, and at the development roller
13
, regulated in a thin film by the developer layer-regulating member
51
. The regulating roller
61
,
62
,
63
, or
64
is disposed to be in contact with the photoconductive drum
11
and to protrude slightly from an outer surface of a developer layer of the development roller
13
such that in a developing process, a given space is formed between the development roller
13
and the photoconductive drum
11
.
Also, each of the developing devices
31
,
32
,
33
,
34
is supported to be reciprocally movable by a member (not shown) guiding the developing devices
31
,
32
,
33
,
34
. The developing devices
31
,
32
,
33
,
34
are moved toward the photoconductive drum
11
against corresponding releasing springs
74
when eccentric cams
35
,
36
,
37
,
38
rotatably fixed on shafts
56
rotate to push corresponding developing devices
31
,
32
,
33
,
34
toward the photoconductive drum
11
. The rotation of shafts
56
is controlled by electronic clutches (not shown). Also, in the developing process, a bias voltage is supplied to the development roller
13
. When a negative-positive reversal process is performed in the development roller
13
, the bias voltage has the same polarity as the outer surface of the photoconductive drum
11
.
The image-transferring part
60
electrostatically transfers a colored visual image formed on the photoconductive drum
11
onto a sheet of printing paper, and the cleaning-discharging part
80
removes the developers remaining on the photoconductive drum
11
.
An operation of the image forming apparatus
10
will now be explained.
First, when a printing command is issued, a photoconductive drum
11
is continuously rotated by the drum-driving source, and at the same time, a surface of the photoconductive drum
11
is uniformly electrified by the first charging device
12
. When an electrified region (surface) of the photoconductive drum
11
reaches a color developing position, for example, a yellow developing position “d” of a yellow developing device
31
, an electronic clutch of the yellow developing device
31
is operated to rotate the eccentric cam
36
to move the yellow developing device
31
toward the photoconductive drum
11
in a yellow developing state.
The surface of the photoconductive drum
11
is photo-exposed by the LSU
20
to form an electrostatic latent image of yellow. When the surface of the photoconductive drum
11
is positioned at the yellow developing position “d” according to the rotation of the photoconductive drum
11
, the electrostatic latent image of yellow is developed from a front end to a rear end thereof to form a continuous yellow image.
After the continuous yellow image is formed and the rear end of thereof is passed through the yellow developing position “d”, the eccentric cam
35
is rotated to separate the yellow developing device
31
from the photoconductive drum
11
.
After that, when the front end of the yellow image reaches another color position, for example, a magenta developing position “e” of the magenta developing device
32
, an electronic clutch of the magenta developing device
32
is operated to rotate the eccentric cam
36
to move the magenta developing device
32
toward the photoconductive drum
11
in a magenta developing state.
At this time, the yellow image formed on the photoconductive drum
11
is passed by the image-transferring part
60
, the quenching lamp
87
, and the cleaning-discharging part
80
which are in a non-operating state, and then the front end of the photoconductive drum
11
is disposed again below the first charging device
12
. Particularly, the image-transferring part
60
and the cleaning-discharging part
80
are maintained in a non-contact state with the photoconductive drum
11
except in a printing operation so that the yellow image to be passed do not come to be dim or muddy. Below the first charging device
12
, the photoconductive drum
11
on which the yellow image is formed is again uniformly electrified and then photo-exposed by the LSU
20
to form an electrostatic latent image of magenta overlappingly on the yellow image.
As the overlappingly formed electrostatic latent image of magenta is positioned at the magenta developing position “e” according to the rotation of the photoconductive drum
11
, it is developed into a continuous yellow•magenta-overlapped image. After the yellow•magenta-overlapped image is formed and a rear end thereof is passed through the magenta developing position “e”, the eccentric cam
36
is rotated and thereby the magenta developing device
32
is separated from the photoconductive drum
11
.
Thereafter, when the front end of the yellow•magenta-overlapped image reaches another color position, for example, a cyan developing position “f” of cyan developing device
33
, an electronic clutch of the cyan developing device
33
is operated to rotate the eccentric cam
37
to move the cyan developing device
33
toward the photoconductive drum
11
in a cyan developing state.
At this time, the yellow•magenta-overlapped image formed on the photoconductive drum
11
is positioned again below the first charging device
12
after passing by the image-transferring part
60
, the quenching lamp
87
, and the cleaning-discharging part
80
which are in the non-operating state. Below the first charging
Goodrow John L
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
LandOfFree
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