Electrophotography – Image formation – Development
Reexamination Certificate
2001-06-15
2002-12-17
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06496674
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for recovering a carrier from a photoreceptor belt of a liquid electrophotographic printer.
2. Description of the Related Art
Generally, liquid electrophotographic printers, applied to printers or photocopiers, print an image by applying a developer, in which a solid toner of a predetermined color is mixed with a liquid carrier acting as a solvent, to an electrostatic latent image formed on a photoreceptor medium such as a photoreceptor belt running along an endless track.
FIG. 1
is a schematic diagram illustrating the configuration of a conventional liquid electrophotographic printer. Referring to
FIG. 1
, a liquid electrophotographic printer includes a photoreceptor belt
10
which is supported by a plurality of guide rollers
11
and runs along an endless track, a plurality of development devices
13
a
,
13
b
,
13
c
and
13
d
, a drying unit
20
and a transfer roller
16
.
The photoreceptor belt
10
is charged to a predetermined potential at a charging station
15
. The potential of the photoreceptor belt
10
changes depending on beams emitted from a plurality of laser scanning units
14
a
,
14
b
,
14
c
and
14
d
which are installed in close proximity to the respective development devices
13
a
,
13
b
,
13
c
and
13
d
, so that an electrostatic latent image is formed on the photoreceptor belt
10
. The development devices
13
a
,
13
b
,
13
c
and
13
d
allow a developer, in which a toner is mixed with a liquid carrier, to selectively adhere to an electrostatic latent image area on the photoreceptor belt
10
. Toners T are supplied to a transfer roller
16
, and then transferred to printing paper P passing between the transfer roller
16
and a fixing roller
17
due to a difference in surface energy.
The drying unit
20
includes a drying roller
22
and heating rollers
24
. The drying roller
22
absorbs the liquid carrier from the photoreceptor belt
10
which has passed the development devices
13
a
,
13
b
,
13
c
and
13
d
. The heating rollers
24
assist the function of the drying roller
22
by evaporating the liquid carrier absorbed by the drying roller
22
. Since the evaporated carrier negatively affects the human body, it is necessary to prevent the evaporated carrier from effusing to the air. Moreover, it is necessary to recover the carrier in order to reduce the consumption of the carrier so that costs can be reduced. Accordingly, a liquid electrophotographic printer is usually provided with a carrier recovery apparatus for recovering a liquid carrier by collecting and condensing carrier vapor evaporated by the drying unit
20
.
FIG. 2
is a schematic diagram illustrating a conventional carrier recovery apparatus provided near a drying unit in a liquid electrophotographic printer. Referring to
FIG. 2
, a drying unit
20
includes a drying roller
22
, heating rollers
24
and a manifold
25
. The drying roller
22
is disposed a predetermined distance from a guide roller
11
to be parallel with the guide roller
11
, and absorbs a liquid carrier which adheres to a photoreceptor belt
10
. The heating rollers
24
evaporate the liquid carrier absorbed by the drying roller
22
. The manifold
25
collects the evaporated carrier vapor. In this case, some of the collected carrier vapor is liquefied and induced to a carrier recovery container
40
provided under the manifold
25
, and the remaining carrier vapor is induced to a condenser
30
.
The condenser
30
contains a low temperature liquid condensate. The upper portion of the condenser
30
is connected to an inflow pipe
31
through which the carrier vapor flows from the drying unit
20
into the condenser
30
and to a carrier vapor discharge pipe
34
through which uncondensed carrier vapor is discharged from the condenser
30
. One side of the condenser
30
is connected to a carrier liquid discharge pipe
33
through which a condensed liquid carrier is discharged from the condenser
30
. A peltier chip
44
is provided on another side of the condenser
30
to maintain a low temperature inside the condenser. Heat generated from the peltier chip
44
is effused to a heat sink
46
.
Carrier vapor is induced from the drying unit
20
into the condenser
30
through the inflow pipe
31
. Then, the carrier vapor contacts the liquid condensate to be liquefied. Uncondensed carrier vapor is induced through the carrier vapor discharge pipe
34
to a filter
35
and discharged to the outside through the filter
35
. A liquid carrier condensed in the condenser
30
is discharged through the carrier liquid discharge pipe
33
to the carrier recovery container
40
.
A first pump
32
for pumping carrier vapor out of the drying unit
20
into the condenser
30
is installed at a predetermined portion of the inflow pipe
31
. A second pump
42
for supplying a liquid carrier collected within the carrier recovery container
40
to a development device (not shown) is installed at a predetermined portion of a carrier supply pipe
41
. A third pump
52
for discharging carrier vapor is installed at a predetermined portion of the carrier vapor discharge pipe
34
.
In a carrier recovery apparatus having such a structure, high temperature carrier vapor generated in the drying unit
20
may flow into the condenser
30
through the inflow pipe
31
without being cooled down appropriately, thereby decreasing the efficiency of condensing carrier vapor. Consequently, the recovery percentage of a carrier decreases. In addition, polluted carrier vapor which is not sufficiently filtered is discharged from the condenser
30
, thereby shortening the duration of the filter
35
.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a carrier recovery apparatus using a cooling unit with a radiator in a liquid electrophotographic printer to improve the efficiency of condensing carrier vapor, thereby increasing the recovery percentage of a carrier and extending the duration of a filter.
Accordingly, to achieve the above object of the invention, in one embodiment, there is provided a carrier recovery apparatus of a liquid electrophotographic printer, including a drying unit for absorbing and evaporating a liquid carrier remaining on a photoreceptor belt after development, a cooling unit for cooling and condensing carrier vapor evaporated by the drying unit, a condenser for cooling the carrier vapor which has passed through the cooling unit to condense the carrier vapor which has not been condensed by the cooling unit, and a carrier recovery container for storing a liquid carrier discharged from the condenser.
In another embodiment, there is provided a carrier recovery apparatus of a liquid electrophotographic printer, including a drying unit for absorbing and evaporating a liquid carrier remaining on a photoreceptor belt after development, a first cooling unit for cooling and condensing carrier vapor evaporated by the drying unit, a second cooling unit for cooling the carrier vapor which has passed through the first cooling unit to condense the carrier vapor which has not been condensed by the first cooling unit, a condenser for cooling the carrier vapor which has passed through the second cooling unit to condense the carrier vapor which has not been condensed by the first and second cooling units, and a carrier recovery container for storing a liquid carrier discharged from the condenser.
REFERENCES:
patent: 3880515 (1975-04-01), Tanaka et al.
patent: 5884128 (1999-03-01), Park
patent: 6085055 (2000-07-01), Shin et al.
patent: 6101356 (2000-08-01), Kim et al.
patent: 6141518 (2000-10-01), Shin et al.
Baik Un-ho
Kim Yong-geun
Pang Jeong-hun
Royer William J.
Samsung Electronics Co,. Ltd
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