Electrophotography – Control of electrophotography process – Control of developing
Reexamination Certificate
2000-09-11
2002-02-19
Grimley, Arthur T. (Department: 2852)
Electrophotography
Control of electrophotography process
Control of developing
C399S237000, C399S348000
Reexamination Certificate
active
06349186
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a development apparatus of a liquid electrophotographic printer, and also, to a method for controlling the mode of a developing station of a liquid electrophotographic printer, for preventing a photosensitive belt from being contaminated while cleaning the development roller and performing sufficient cleaning of the development roller and a development roller driving apparatus therefor.
2. Description of the Related Art
In general, a liquid electrophotographic printer such as a color laser printer, as shown in
FIG. 1
, includes a photosensitive belt
10
supported by a plurality of rollers
11
,
12
and
13
installed in a printer body (not shown) which makes a circular movement in an endless track. An image to be printed is developed on one surface of the photosensitive belt
10
by a developing station
14
, and the developed image is dried via a drying station
15
to then be transferred to a sheet of printing paper
1
by a transfer/pressing station
16
having a transfer roller
16
a
and a pressing roller
16
b
. The developing station
14
supplies a developer liquid to the photosensitive belt
10
, and separates most of the liquid carrier contained in the developer liquid so that only toner is left over a latent electrostatic image portion of the photosensitive belt
10
, thereby allowing transfer of the image in the transfer/pressing station
16
.
The developing station
14
, as shown in
FIG. 3
, is installed such that a development roller
21
and a development backup roller
22
selectively come in tight contact with the photosensitive belt
10
disposed therebetween. A developer liquid spray nozzle
23
is installed to spray a developer liquid between the development roller
21
and the photosensitive belt
10
. The development roller
21
uniformly applies the developer liquid sprayed from the spray nozzle
23
to the photosensitive belt
10
while being rotated by a driving apparatus (not shown). A cleaning roller
24
is installed under the development roller
21
to be selectively in contact with the development roller, for cleaning the development roller
21
. A squeezing roller
31
and a squeezing backup roller
32
are installed in the rear of the development roller
21
in view of the rotation direction of the development roller
21
, so as to selectively come into tight contact with the photosensitive belt
10
disposed therebetween. By being passive-rotated in selective contact with the photosensitive belt
10
, the squeezing roller
31
squeezes out the liquid carrier from the developer liquid applied on the photosensitive belt
10
for removal. Subsequently, the squeezing roller
31
reversely rotates in a drip line removal mode. Thus, although not shown, a separate driver for reversely rotating the squeezing roller
31
is provided in the developing station
14
. A squeezing blade
34
contacts the squeezing roller
31
reversely rotating in the drip line removal mode, and removes the ink drawn by the squeezing roller
31
. The squeezing blade
34
is configured to selectively contact the squeezing roller
31
and is spaced apart from the squeezing roller
31
in the printing mode, as shown in FIG.
3
.
As shown in
FIG. 4
, the aforementioned developing station sequentially operates in the order of a printing mode (step S
40
), a development roller cleaning mode (step S
50
), a drip line removal mode (step S
60
) and a home mode (step S
70
), which will now be described in more detail.
Initially, in a printing standby state, the developing station is in a home mode (step S
70
). In the home mode (step S
70
), the development roller
21
and the squeezing roller
31
are spaced approximately 12 mm apart from the photosensitive belt
10
. Here, the development roller
21
and the squeezing roller
31
do not rotate but are at a standstill.
In the home mode (step S
70
), if a printing start signal is applied, the development roller
21
and the squeezing roller
31
are pressed into tight contact with the photosensitive belt
10
by a pressing unit (not shown) with a predetermined pressure of about 20 kg/f. Here, the development roller
21
is rotated by a driver (not shown) and the squeezing roller
31
is passively rotated by the photosensitive belt
10
. Then, a developer liquid is sprayed through the developer liquid spray nozzle
23
, thereby performing the printing mode (step S
40
).
In the development roller cleaning mode (step S
50
), the development roller
21
is subjected to racing for the purposes of removing the developer liquid remaining on the developer liquid spray nozzle
23
and the cleaning roller
24
and sufficiently cleaning the development roller
21
after completing the printing mode (step S
40
). The development roller cleaning mode (step S
50
) is achieved by the racing of the development roller
21
in the same state as in the printing mode (step S
40
).
After completing the development roller cleaning mode (step S
50
), a drip line removal mode (step S
60
), in which unnecessary toner remaining on the photosensitive belt
10
is removed, is performed. In the drip line removal mode (step S
60
), the development roller
21
is spaced approximately 4 mm apart from the photosensitive belt
10
. The squeezing roller
31
receives power from the not-shown driver in a state that it is pressed into tight contact with the photosensitive belt
10
with a predetermined pressure (about 4 kg/f), and rotates in the reverse direction to the printing mode, to collect the toner present on the photosensitive belt
10
. Here, the squeezing blade
34
is brought into contact with the squeezing roller
31
which reversely rotates as above, and removes the toner collected by the squeezing roller
31
.
After the drip line removal mode (step S
60
) is completed, the procedure is returned to the home mode (step S
70
) in which the development roller
21
and the squeezing roller
31
are spaced approximately 12 mm apart from the photosensitive belt
10
and is in a printing standby state.
However, according to the conventional method for controlling the mode of a developing station, a development roller cleaning mode is performed in a state that a development roller comes into tight contact with the photosensitive belt, after the printing mode and before the drip line removal mode. Thus, the photosensitive belt may be contaminated by the development roller while the development roller is being cleaned. Also, for the same reason as above, the development roller can be cleaned for only about 20 seconds. That is, a sufficient time for cleaning the development roller cannot be ensured. Accordingly, degradation in development quality cannot be avoided due to contamination of the development roller.
SUMMARY OF THE INVENTION
To solve the above problems, it is a first object of the present invention to provide a method for controlling the mode of a developing station of a liquid electrophotographic printer, which can prevent the photosensitive belt from being contaminated by a development roller in the development roller cleaning mode.
It is a second object of the present invention to provide a method for controlling the mode of a developing station of a liquid electrophotographic printer, which can ensure a sufficient time for cleaning the development roller.
It is a third object of the present invention to provide a development roller driving apparatus for implementing the method for controlling the mode of a developing station of a liquid electrophotographic printer.
Accordingly, to achieve the above objects, there is provided a method for controlling the mode of a developing station of a liquid electrophotographic printer, wherein a printing mode, a drip line removal mode and a home mode are sequentially performed, and a development roller is subjected to racing in the home mode to be cleaned.
Since the development roller is cleaned in the home mode in which the development roller is spaced approximately 12 mm apart from the photosensitive belt, the photosensitive
No Kwang-ho
Park Woo-yong
Grimley Arthur T.
Samsung Electronics Co,. Ltd.
Sughrue & Mion, PLLC
Tran Hoan
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