Electrophotography – Image formation – Development
Reexamination Certificate
1999-11-30
2001-11-20
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06321054
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a squeegee roller cleaning apparatus of a liquid electrophotographic printer and, more particularly, to a squeegee roller cleaning apparatus of a liquid electrophotographic printer having an improved structure so that hold-up volume developer remaining at a portion where a blade and squeegee roller contact each other is removed after a drip-line removal mode.
2. Description of the Related Art
In a typical liquid electrophotographic printer, as shown in
FIG. 1
, a photoreceptor web
10
that is a photoreceptor medium is supported by a plurality of guide rollers
11
to circulate along an endless path. The surface of the photoreceptor web
10
is charged by a charger
12
to the electric potential of about 600 V. The surface of the photoreceptor web
10
charged as above is converted to a predetermined electric potential (about 250V) by light emitted from a plurality of laser scanning units
13
so that an electrostatic latent image is formed thereon. A plurality of development units
20
for developing the electrostatic latent image with developer is installed to form a predetermined gap (hereinafter, referred to as a development gap) between the photoreceptor web
10
and each development unit
20
. The development unit
20
also includes a development roller
22
maintaining an electric potential of about 450V. Charged developer is injected into the development gap by an injector (not shown). As the electric potential of the developer is lower than that of the development roller
22
, the developer is transferred to an area where the electrostatic image is formed and adheres thereto.
The developer adhering to the electrostatic latent image area due to the difference in electric potential is squeezed by a squeegee roller
24
so that toner in the developer becomes filmy and is converted to a toner image. The remainder of the developer, other than the filmy toner, is removed by being squeezed from the photoreceptor web
10
. Here, the toner image is dried by a drying unit
15
. Also, the toner image is transferred from the photoreceptor web
10
to a transfer roller
16
due to the difference in surface energy between the transfer roller
16
and the photoreceptor web
10
. The toner image on the surface of the transfer roller
16
is printed on the surface of a print paper P passing between the transfer roller
16
and a fixation roller
17
.
After the development mode, as shown in
FIG. 2
, the development roller
22
is lowered to remove the developer, or drip-line developer D, remaining on the photoreceptor web
10
between the development roller
22
and the squeegee roller
24
. Then, the squeegee roller
24
, while being in contact with the photoreceptor web
10
, is rotated opposite the direction in which the photoreceptor web
10
travels. As a result, the drip-line developer D is removed from the photoreceptor web
10
and the removed drip-line developer flows along the outer circumference of the squeegee roller
24
and is removed by a squeegee blade
26
contacting the surface of the squeegee roller
24
.
However, after the drip-line removal mode, as shown in
FIG. 3
, the developer at a portion where the squeegee roller
24
and the blade
26
contact each other is not clearly removed so that a small amount of remaining developer referred to as hold-up volume developer B remains unnecessarily.
The blade
26
linearly contacts the squeegee roller
24
in a lengthwise direction. Thus, as shown in
FIG. 4
, the hold-up volume developer B remains on the surfaces of the blade
26
and the squeegee roller
24
even when the blade
26
is separated from the squeegee roller
24
. The leftover developer remaining on the surface of the squeegee roller
24
is hardened thereon and transferred to the photoreceptor web
10
at the next development mode to contaminate the photoreceptor web
10
as well as the transfer roller
16
of FIG.
1
.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a squeegee roller cleaning apparatus of a liquid electrophotographic printer which removes a small amount of developer, referred to herein as the hold-up volume developer, remaining on the surface of the squeegee roller after a drip-line removal mode so that the photoreceptor web and transfer roller can be prevented from being contaminated.
Accordingly, to achieve the above objective, there is provided a squeegee roller cleaning apparatus of a liquid electrophotographic printer, which comprises a squeegee roller mounted to be operative for movement in order to selectively contact a photoreceptor web circulating along an endless path, and a cleaning roller including at least one blade member which is spirally twisted on an outer circumference of a rotary rod so as to contact the squeegee roller by the movement of the squeegee roller.
It is preferred in the present invention that the cleaning roller comprises a coupling groove formed in the outer circumferential surface of the rotary rod so that a root portion of the blade member can be inserted.
Also, it is preferred in the present invention that the blade member is formed of a rubber material to be elastically twisted.
It is preferred in the present invention to provide a squeegee blade capable of movement to longitudinally contact the squeegee roller.
It is a further objective of the present invention to provide a method of removing a hold-up volume of developer from a squeegee roller situated in a liquid electrophotographic printer, wherein the liquid electrophotographic printer includes a photoreceptor web circulating along an endless path, a movable squeegee roller that selectively contacts the photoreceptor web, a cleaning roller that includes at least one blade member spirally twisted on an outer circumference of a rotary rod so as to contact the squeegee roller, and a movable squeegee blade that selectively contacts the squeegee roller.
Accordingly, to achieve the above objective, there is provided a method to remove the hold-up developer volume by displacing the squeegee roller from the photoreceptor web; contacting the squeegee roller with a squeegee blade and rotating the squeegee roller against the squeegee blade, halting the rotation of the squeegee roller and displacing the squeegee blade from the squeegee roller, thereby leaving a hold-up volume of developer remaining on the squeegee roller; displacing the squeegee roller, whereby at least one blade member of the cleaning roller contacts the squeegee roller; and rotating the squeegee roller so that at least one blade member removes the hold-up volume of developer remaining on the squeegee roller.
It is preferred that the squeegee roller is rotated in a direction opposite to the direction of travel of the photoreceptor web when the squeegee roller is rotated against the squeegee blade.
Also, it is preferred that the squeegee roller is rotated in a direction opposite to the rotational direction of the cleaning roller when the at least one blade member is in contact with the squeegee roller.
REFERENCES:
patent: 5937250 (1999-08-01), Kwak et al.
patent: 6094553 (2000-07-01), Shima
Royer William J.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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