Electrophotography – Cleaning of imaging surface – Removing liquid developer
Reexamination Certificate
2000-06-15
2001-12-11
Braun, Fred L (Department: 2852)
Electrophotography
Cleaning of imaging surface
Removing liquid developer
C399S327000
Reexamination Certificate
active
06330421
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid electrophotographic printer, and more particularly, to a cleaning apparatus for removing various contaminants containing untransferred toner remaining on a photoreceptor belt and/or a transfer roller after printing, using a cleaning member having a solvent, and a liquid electrophotographic printer having the cleaning apparatus.
Here, printers generally refer to all kinds of image printing apparatuses for printing an image using an electrophotographic process, for example, copiers, facsimile apparatuses or the like, as well as general laser printers.
2. Description of the Related Art
In general, a liquid electrophotographic printer forms an electrostatic latent image on a photosensitive medium such as a photoreceptor belt by scanning a laser beam onto the photoreceptor belt, develops the electrostatic latent image formed on the photoreceptor belt using a developer liquid, which is a mixture of solid toner of a predetermined color and liquid carrier serving as a solvent, and transfers the developed image to a printing sheet, thereby printing a desired image.
The liquid electrophotographic printer typically have two parts; an engine which consists of essential parts for performing a printing process, and a controller for interpreting data transmitted from a data outputting device such as a computer, constructing to-be-printed image data by individual bits of a one-page size to then be stored in a video RAM, communicating with the engine so as to perform printing and then transmitting the data stored in the video RAM to the engine in the form of serial data.
An exemplary liquid electrophotographic printer having the aforementioned configuration is schematically shown in
FIG. 1
, which will now be described briefly.
As illustrated, the liquid electrophotographic printer includes a photoreceptor belt
10
wound around and supported by rollers
1
,
2
and
3
which are installed within a printer body and traveling along a predetermined track.
In the neighborhood of the photoreceptor belt
10
are installed an erasure unit
20
for erasing the surface potential formed on the photoreceptor belt
10
, a charging unit
30
for charging the photoreceptor belt
10
from which the surface potential has been erased, to a predetermined potential, an exposure unit
40
for forming an electrostatic latent image by scanning a laser beam converted according to electric data of a portion to be printed, onto the photoreceptor belt
10
, a development unit
50
for supplying a developer liquid, which is a mixture of solid toner and liquid carrier, to the photoreceptor belt
10
to thus adhere the toner to a portion of the surface of the photoreceptor belt
10
where the electrostatic latent image is formed, thereby forming a visible image, a drying unit
60
for absorbing only the carrier contained in the developer liquid other than the toner adhered to the photoreceptor belt
10
, drying and removing the same, a transfer/fixation unit
70
for transferring the toner formed on the photoreceptor belt
10
as an image, to a printing sheet
80
.
Inside the photoreceptor belt
10
are installed a plurality of backup rollers
4
,
5
,
6
and
7
in close contact with the photoreceptor belt
10
to then be passively driven.
Also, the exposure unit
40
includes four laser scanning units (LSUs)
41
,
42
,
43
and
44
corresponding to various colors, for example, yellow (Y), magenta (M), cyan (C) and black (K), respectively.
The development unit
50
includes four development rollers
51
,
52
,
53
and
54
rotating selectively in close contact with the photoreceptor belt
10
, and squeegee rollers
51
′,
52
′,
53
′ and
54
′ installed next to the development rollers
51
,
52
,
53
and
54
, respectively.
The drying unit
60
includes a dry roller
62
rotatably installed in a bracket (not shown) provided inside a manifold
61
, and a pair of heating rollers
63
and
63
′ selectively in close contact with the dry roller
62
.
The transfer/fixation unit
70
includes a transfer roller
71
selectively brought into close contact with the photoreceptor belt
10
, and a fixation roller
72
selectively brought into close contact with the transfer roller
71
. The printing sheet is fed between the transfer roller
71
and the fixation roller
72
. At this stage, the image transferred to the transfer roller
71
is conveyed to the printing sheet
80
. The fixation roller
72
fuses the toner image to then be adhered to the printing sheet
80
by applying heat and pressure to the toner image conveyed to the printing sheet.
Although not shown, the liquid electrophotographic printer further includes a developer liquid supplying device for continuously supplying a developer liquid having a predetermined concentration to the development unit
50
, a sheet feeding unit for supplying printing sheets and a sheet ejection unit.
The printing process of the aforementioned liquid electrophotographic printer is performed as follows.
If a printing instruction is input from a data outputting device such as a computer, the erasure unit
20
first operates to electrically clear the residual charges remaining on the photoreceptor belt
10
. Then, the charging unit
30
applies a high voltage to the photoreceptor belt
10
to charge the surface thereof to a predetermined potential (generally 500 to 700 V).
Next, the exposure unit
40
scans a laser beam converted according to the electric data of a portion to be printed on the photoreceptor belt
10
charged to the predetermined potential, thereby forming an electrostatic latent image on the photoreceptor belt
10
due to a difference in the surface potential.
After exposure, the development unit
50
performs development, in which the electrostatic latent image formed on the photoreceptor belt
10
is converted into a visible image using toner particles. The development unit
50
adheres the toner contained in an externally supplied developer liquid to the portion of the photoreceptor belt
10
where the electrostatic latent image is formed, thereby forming the visible image on the photoreceptor belt
10
. Here, the liquid carrier contained in the developer liquid is squeezed simultaneously with development to then be primarily separated for removal.
The surplus carrier which is not removed by the development unit
50
is absorbed by the dry roller
62
while the photoreceptor belt
10
passes through the drying unit
60
, and then evaporated by a pair of heating rollers
63
and
63
′ for removal, so that the toner image formed on the photoreceptor belt
10
becomes a suitable image to be transferred.
The toner image developed on the photoreceptor belt
10
through the above-described process is transferred to the transfer roller
71
via the transfer/fixation unit
70
. The image transferred to the transfer roller
71
is conveyed to the printing sheet
80
fed between the transfer roller
71
and the fixation roller
72
, and are completely fused to then be fixed to the printing sheet
80
when heat and pressure are applied by the fixation roller
72
.
During the above-described process, transferring an image, for example, from the photoreceptor
10
to the transfer roller
71
or from the transfer roller
71
to the printing sheet
80
, is performed due to a difference in the surface energy, that is, a difference in the adhesion, between each of the photoreceptor belt
10
, the transfer roller
71
and the printing sheet
80
. In other words, since the adhesion of the photoreceptor belt
10
is set to be relatively higher than that of the transfer roller
71
, and the adhesion of the printing sheet
80
is set to be higher than that of the transfer roller
71
, the toner image of the photoreceptor belt
10
is transferred to the transfer roller
71
and is finally transferred to the printing sheet
80
.
Here, it is desirable that the image of the photoreceptor belt
10
is completely transferred to the transfer roller
71
and that t
Hogan David Charles
Park Moon-bae
Park Woo-Young
Braun Fred L
Bushnell , Esq. Robert E.
Samsung Electronics Co,. Ltd
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