Electrophotography – Image formation – Transfer
Reexamination Certificate
2002-11-19
2004-11-16
Grimley, Arthur T. (Department: 2852)
Electrophotography
Image formation
Transfer
C399S302000
Reexamination Certificate
active
06819903
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 2002-7027, filed Feb. 7, 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 wet color image forming apparatus and a method of forming an image using the same, and more particularly, to a wet color image forming apparatus to transfer a color image using electrostatic force and pressure which is capable of increasing efficiency when transferring the image from a transfer belt to a paper, and a method of forming an image using the same.
2. Description of the Related Art
A wet color image forming apparatus using a developing solution, e.g., a printer, can obtain a high quality image because efficiency when transferring an image from a transfer belt to a paper is high, as compared to a dry image forming apparatus using toner.
FIG. 1
is a cross-sectional view of a wet color image forming apparatus according to the related art. Referring to
FIG. 1
, the wet color image forming apparatus includes a photosensitive body portion P
1
, a developing apparatus portion P
2
, and a transfer portion P
3
. Paper supplying and paper discharging portions are further included, and a developing cartridge (not shown) to supply a developing solution to the developing apparatus portion P
2
is further included under the developing apparatus portion P
2
.
The photosensitive body portion P
1
includes first through fourth photosensitive bodies
40
,
42
,
44
, and
46
that are spaced apart from each other. The first through fourth photosensitive bodies
40
,
42
,
44
, and
46
are black (BK), cyan (C), magenta (M), and yellow (Y), respectively, on which latent electrostatic images of different colors are formed. A latent electrostatic image corresponding to a black image is formed on the black (BK) photosensitive body
40
. A latent electrostatic image corresponding to a cyan image is formed on the cyan (C) photosensitive body
42
. A latent electrostatic image corresponding to a magenta image is formed on the magenta (M) photosensitive body
44
. A latent electrostatic image corresponding to a yellow image is formed on the yellow (Y) photosensitive body
46
. Reference numerals
50
,
52
,
54
, and
56
are first through fourth cleaning blades, which contact and clean the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
, respectively. Erasers, chargers, and light scanning units (not shown) are further installed around the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
. The erasers neutralize the photosensitive bodies
40
,
42
,
44
, and
46
which are charged after developed latent electrostatic images are transferred. The chargers re-charge the neutralized surfaces of the photosensitive bodies
40
,
42
,
44
, and
46
before latent electrostatic images are formed. The laser scanning units radiate light onto the re-charged surfaces of the photosensitive bodies
40
,
42
,
44
, and
46
to form the latent electrostatic images.
The developing apparatus portion P
2
under the photosensitive body portion P
1
includes first through fourth developer units
60
,
62
,
64
, and
66
which are opposite the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
, respectively, and supply color developing solutions, i.e., ink, necessary to develop the latent electrostatic images formed on the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
. Reference numerals
60
a
,
62
a
,
64
a
, and
66
a
are first through fourth developer rollers which contact and supply the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
with color developing solutions, respectively.
The transfer portion P
3
includes a transfer belt
70
to which a predetermined color image is transferred. The predetermined color image is formed by overlapping resultant materials developed on the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
on a predetermined portion of the transfer belt. The transfer belt
70
is formed of polyimide and has a hardness of 70 (Shore A) or more. The transfer belt
70
has first, second, fourth, fifth, sixth and seventh rollers
72
,
74
,
78
,
80
,
82
, and
84
therein. A third roller
76
is prepared outside the transfer belt
70
opposite the first roller
72
. Except for the third roller
76
, the first, second, fourth, fifth, sixth and seventh rollers
72
,
74
,
78
,
80
,
82
, and
84
maintain the transfer belt
70
in a form suitable for the image transfer. The third roller
76
is grounded and is a paper transfer roller which transfers the color image on the transfer belt
70
to a paper P. The third roller
76
has a hardness of about 30 (Shore A) and causes a cushioning effect. The first roller
72
is a paper transfer backup roller to back up the third roller
76
and is formed of a rubber material having a hardness of about 50 (Shore A). A fifth power supply S
5
applies a voltage to generate an electrostatic force to the first roller
72
when starting the image transfer. The fourth through seventh rollers
78
,
80
,
82
, and
84
are first through fourth transfer backup rollers, respectively, which are used to transfer images on the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
to the transfer belt
70
. Since the images on the first through fourth photosensitive bodies
40
,
42
,
44
, and
46
are charged, the fourth through seventh rollers
78
,
80
,
82
, and
84
must be charged in a charge state, which is opposite to the charge state of the images . This is done to transfer the images to the transfer belt
70
. First through fourth power supplies S
1
, S
2
, S
3
, and S
4
supply the charge to the fourth through seventh rollers
78
,
80
,
82
, and
84
, respectively. The second roller
74
is a driver roller to drive the transfer belt
70
to form the color image by overlapping the resultant materials developed on the photosensitive bodies
40
,
42
,
44
, and
46
accurately and to transfer the color image from the transfer belt
70
accurately to the paper P.
In the wet color image forming apparatus, the color image on the transfer belt
70
is transferred to the paper P by a pressure between the third roller
76
and the transfer belt
70
and an electrostatic force generated by the voltage applied to the first roller
72
. The force applied to the entire contact surface between the third roller
76
and the transfer belt
70
is about 3 kg. Since such a low pressure is used, the transfer is achieved only by the electrostatic force. In this case, a large amount of the developing solution is not transferred and remains on the transfer belt
70
after the transfer. This remaining developing solution is thrown away, which increases the amount of unnecessarily consumed developing solution. This problem is solved by reducing the amount of developing solution supplied to the transfer belt
70
during the development. However, in this case, the density of the color image transferred from the transfer belt
70
to the paper P is degraded. As a result, there has been suggested a wet color image forming apparatus which applies a force of 70 Kg or more between the third roller
76
and the first roller
72
to hot-press the paper P so that the color image is transferred to the paper P. If this wet color image forming apparatus is used, the total amount of unused developing solution is reduced as compared to the wet color image forming apparatus using only electrostatic force. However, it is difficult to clean the developing solution. Thus, after cleaning the developing solution, the developing solution remains on the surface of the transfer belt, which shortens the usable period of the transfer belt.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a wet color image forming apparatus which is capable of increasing efficiency when transferring a color
Gleitz Ryan
Grimley Arthur T.
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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