Electrophotography – Image formation – Development
Reexamination Certificate
1999-09-20
2001-11-27
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
C399S246000
Reexamination Certificate
active
06324367
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reversible pump having an improved structure such that intake fluid is selectively discharged in two directions, and a system for supplying developer in a liquid electrophotographic printer using the same.
2. Description of the Related Art
In general, liquid electrophotographic printers print desired images by developing electrostatic latent images, formed on a photoreceptor medium such as a photoreceptor belt, using a developer of a predetermined color and transcribing the resultant images on paper.
As shown in
FIG. 1
, the liquid electrophotographic printer is comprised of a developing unit
20
for supplying a developer to a photoreceptor belt
10
and developing the photoreceptor belt
10
, and a developer supply system for continuously supplying a developer of a predetermined concentration to the developing unit
20
.
The developer supply system includes a developer tank
30
for containing a developer of a concentration suitable for developing, a spray nozzle
60
for supplying the developer to the photoreceptor belt
10
and the developing unit
20
, and a supply pump
40
for pumping the developer from the developer tank
30
to the spray nozzle
60
. The developer contained in the developer tank
30
is a diluted solution where concentrated ink including powder toner and liquid carrier are mixed in a predetermined ratio. Thus, in order to prevent the concentration of the developer from becoming non-uniform since the toner settles at the bottom of the developer tank
30
, a valve
50
is installed between the supply pump
40
and the spray nozzle
60
in the developer supplying system to return the developer to the developer tank
30
and agitate the developer within the developer tank
30
. That is, the valve
50
operates so that the developer contained in the developer tank
30
is pumped by the supply pump
40
and supplied to the developing unit
20
via the spray nozzle
60
, and that the developer pumped by the supply pump
40
returns to the developer tank
30
in a standby state after the developing operation is completed.
As shown in
FIGS. 2 and 3
, the supply pump
40
includes an impeller
41
rotatably installed within a case
45
having an intake
42
and an outlet
43
, a motor
44
for rotating the impeller
41
, and a plurality of blades
41
a installed on the impeller
41
. In the supply pump
40
having this general structure, fluid taken in through the intake
42
is discharged through the outlet
43
as the impeller
41
rotates in the direction indicated by an arrow.
However, the conventional supply pump
40
can perform only two operations such as discharge or suspension of fluid according to the driving of the motor
44
. Thus, an expensive valve
50
must be installed as described above to supply the developer within the developer tank
30
to the developing unit
20
or return the same to the developer tank
30
. Accordingly, in a printer for realizing a plurality of colors such as a color laser printer, a valve must be installed for the developing unit of each color, thereby increasing the number of component parts to be managed. Therefore, a pump having a structure which can realize a plurality of fluid discharging paths without adopting an expensive valve is required.
SUMMARY OF THE INVENTION
To solve the above problem, it is an object of the present invention to provide a reversible pump having an improved structure such that a plurality of fluid discharging paths are realized by the pump itself, and a system for supplying a developer in a liquid electrophotographic printer using the same.
To achieve the above object, the present invention provides a reversible pump comprising: a case having an intake through which fluid is taken in, a first outlet for discharging internal fluid to the outside, and a second outlet for discharging internal fluid to the outside; an impeller rotatably installed within the case which is capable of rotating in normal and reverse directions, the impeller having a plurality of blades the right and left sides of which are symmetrical to each other in the radial direction of the impeller so that the rotational loads in both the forward and reverse directions are substantially the same; and a motor for rotating the impeller, wherein the fluid is discharged to either the first or second outlet according to the rotating direction of the impeller.
To achieve the above object, the present invention provides a developer supply system in a liquid electrophotographic printer, the system comprising: a developer tank for containing the developer; a spray nozzle for supplying the developer to the developing unit and photoreceptor belt therein; and a reversible pump including a case having an intake through which fluid is taken in from the developer tank, a first outlet for discharging the developer to the spray nozzle, and a second outlet for discharging the developer to the developer tank, an impeller rotatably installed within the case which is capable of rotating in normal and reverse directions, the impeller having a plurality of blades the right and left sides of each are symmetrical to each other in the radial direction of the impeller so that the rotational loads in both the forward and reverse directions are substantially the same, and a motor for rotating the impeller.
REFERENCES:
patent: 4350429 (1982-09-01), Slavin
patent: 4605297 (1986-08-01), Livingston
patent: 5918093 (1999-06-01), Kim
patent: 5970289 (1999-10-01), Yoo
patent: 5999778 (1999-12-01), Chang et al.
patent: 6011943 (2000-01-01), Kim
Ateya Antoun I.
Kim Jung-Woo
Royer William J.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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