Electrophotography – Image formation – Development
Reexamination Certificate
2003-03-05
2004-12-14
Lee, Susan (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06832063
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit of Korean Application No. 2002-35674 filed Jun. 25, 2002 in the Korean Intellectual 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 an apparatus for driving developers of a color image forming apparatus, and more particularly, to an apparatus for sequentially driving a plurality of developers separated a predetermined distance from a photosensitive body in a color image forming apparatus.
2. Description of the Related Art
In general, an electrophotographic printer such as a color laser printer includes an image forming apparatus which forms an electrostatic latent image on a photosensitive body and develops the electrostatic latent image with toner. Then, the developed image is transferred to paper by a predetermined transfer medium and is pressed and heated to completely fix the image on the paper.
FIG. 1
shows an example of an image forming apparatus of a color printer. Referring to
FIG. 1
, an image forming apparatus includes a photoreceptive drum
10
which is a photosensitive body, a charger
11
which charges the photosensitive drum
10
, a laser scanning unit (LSU)
12
as an exposing unit which forms an electrostatic latent image by scanning light onto the charged photoreceptive drum
10
, a development unit
13
which develops the electrostatic latent image with four colors of black (K), yellow (Y), magenta (M), and cyan (C), a transfer belt
14
on which four different color images developed on the photoreceptive drum
10
are sequentially overlapped, a first transfer roller
14
a
which transfers the image developed on the photoreceptive drum
10
to the transfer belt
14
, a second transfer roller
14
b
which transfers the image of four overlapping colors on the transfer belt
14
to paper, and a fusing unit
15
which presses and heats the paper to fix the transferred image on the paper. Developing rollers
13
a
-K,
13
a
-Y,
13
a
-M, and
13
a
-C of four developers
13
-K,
13
-Y,
13
-M, and
13
-C provided in the development unit
13
are arranged separated by a predetermined gap from the photoreceptive drum
10
and sequentially develop the electrostatic latent image on the photoreceptive drum
10
when a development bias voltage is applied to corresponding developing rollers. Reference numerals
16
,
17
,
18
, and
19
denote a paper cassette for storing a supply of paper, a blade for cleaning the photoreceptive drum
10
, an eraser, and a transfer path along which the paper is ejected, respectively.
The image forming apparatus having the above structure performs an image forming process as follows. First, when the charger
11
charges the photoreceptive drum
10
, the LSU
12
scans light to form an electrostatic latent image of an image to be developed with the first color. For example, when black is to be developed first, a predetermined bias voltage is applied to the black developing roller
13
a
-K. Then, a development unit driving motor (not shown) drives the developing roller
13
a
-K so that a toner adhering on the outer circumferential surface thereof is transferred to a portion of the photoreceptive drum
10
contacting the developing roller
13
a
-K. The black image developed as above is transferred to the transfer belt
14
via a first transfer nip N
1
. Next, an electrostatic latent image for the second color is formed through the charging and exposing steps with respect to the photoreceptive drum
10
. For example, where yellow is to be developed secondly, a predetermined development bias voltage is applied to the yellow developing roller
13
a
-Y and the developing roller
13
a
-Y is driven to develop the electrostatic latent image on the photoreceptive drum
10
. The yellow developed as above is transferred onto the transfer belt
14
to overlap the black image previously transferred to the belt
14
. In the same manner, images of the third color, magenta, and the fourth color, cyan, are developed and transferred so that an image having a desired color is completely formed on the transfer belt
14
. Thereafter, the completed color image formed on the transfer belt
14
is transferred to paper supplied to a second transfer nip N
2
between the transfer belt
14
and the second transfer roller
14
b
. As the paper passes through the fusing unit
15
, the color image is heated and pressed to be completely fixed onto the paper.
FIG. 2
is a view showing a structure of a driving apparatus of the development unit of FIG.
1
.
FIG. 3
is a partial plan view of the driving apparatus of FIG.
2
.
Referring to
FIGS. 1-3
, the developing rollers
13
a
-K,
13
a
-Y,
13
a
-M, and
13
a
-C are arranged around the photoreceptive drum
10
to be sequentially separated from the photoreceptive drum
10
with a predetermined gap. A deceleration gear
31
which is a two-step gear is connected to a pinion gear
30
of a development unit driving motor (not shown). The deceleration gear
31
is connected to developing roller gears
20
-K,
20
-Y,
20
-M, and
20
-C via idle gears
32
,
33
,
34
, and
35
and electronic clutches
36
. The electronic clutches
36
are provided to correspond to the respective developing rollers
13
a
. The idle gears
32
,
33
,
34
, and
35
are arranged in an appropriate number between the deceleration gear
31
and the electronic clutch
36
to transfer a rotational force of the gear
30
of the development unit driving motor to each of the electronic clutches
36
. A first gear
37
connected to the idle gear
32
or
35
and a second gear
38
connected to the developing roller gear
20
are provided at opposite ends of each of the electronic clutches
36
, as shown in FIG.
3
. When the electronic clutch
36
is turned on, the rotation of the first gear
37
is transferred to the second gear
38
and the developing roller gear
20
. When the electronic clutch
36
is turned off, the first gear
37
and the second gear
38
are disconnected.
In the operation of the driving apparatus of the development apparatus having the above structure, when the black developer
13
-K is to be used, the development unit driving motor and the gear
30
are rotated clockwise. According to the rotation of the development unit driving gear
30
, the first gears
37
-K and
37
-Y of the electronic clutches
36
-K and
36
-Y connected to the first idle gear
32
and the first gears
37
-M and
37
-C of the electronic clutches
36
-M and
36
-C connected to the second, third, and fourth idle gears
33
,
34
, and
35
are rotated. Next, when the electronic clutch
36
-K for the black developer
13
-K is turned on, the rotation of the first gear
37
-K is transferred to the second gear
38
-K. Accordingly, the developing roller gear
20
-K and the developing roller
13
a
-K are driven. Here, a development bias voltage is applied to the developing roller
13
a
-K so that toner on the surface of the developing roller
13
a
-K develops the electrostatic latent image of the photoreceptive drum
10
.
Next, to drive the yellow developing roller
13
-Y, the development bias voltage applied to the black developing roller
13
-K is cut off and the electronic clutch
36
-K is turned off. Then, a development bias voltage for yellow is applied to the yellow developing roller
13
-Y and the electronic clutch
36
-Y is turned on, so that the rotation power of the first gear
37
-Y is transferred to the second gear
38
-Y. Thus, the developing roller gear
20
-Y and the developing roller
13
a
-Y are driven. The development of magenta and cyan are sequentially performed in a similar manner.
However, since the driving apparatus of the developers having the above structure requires a plurality of electronic clutches, a cost for material increases.
SUMMARY OF THE INVENTION
To solve the above and/or other problems, the present invention provides a developer driving apparatus of a color image forming apparatus which sequentially drives developers by a mechanical means instea
Ahn Byeong-hwa
Kim Yu-man
Yoon Young-min
Lee Susan
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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