Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
2001-05-04
2003-07-22
Tran, Hoan (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
C399S239000
Reexamination Certificate
active
06597880
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wet electrophotographic printer and, more particularly, to a wet electrophotographic printer capable of preventing peripheral devices such as a photoreceptor belt from being contaminated by ink which flows outwardly at both ends of a plurality of rollers after being used for a development process.
2. Description of the Related Art
In general, a wet electrophotographic printer emits a laser beam onto a photoreceptor such as a photoreceptor belt to generate an electrostatic latent image, develops the electrostatic latent image by using a developer liquid which is normally mixed with a toner in a solid state having a predetermined color, and a carrier in a liquid state functioning as a solvent, and produces a desired image on a paper through transcription.
In
FIG. 1
, there are shown major components of a wet electrophotographic printer as described above. A photoreceptor belt
1
is trained over rollers
2
,
3
, and
4
mounted within a main body of the printer (not shown), to run or circulate therearound. An electostatic latent image is formed on the photoreceptor belt
1
by a beam exposing device (not shown), and then is developed by a developing device
10
. An image formed on the photoreceptor belt
1
by the developing device
10
is dried by a drier
20
, up to a level required for transcription, and finally is transcribed in a transcriber
30
onto a paper supplied from the outside.
The developing device
10
is provided with a plurality of development units (normally four), each of which corresponds to a color. Representative of other development units, development unit
11
includes a development roller
13
for transcribing a developer injected from a developer injection nozzle
12
onto a region of the electrostatic latent image on the photoreceptor belt
1
, and a squeegee roller
14
for removing the carrier from the developer transcribed onto the photoreceptor belt
1
. Although not shown in the drawings, a cleaning roller for removing sludge of the developer smeared around the squeegee roller
14
is provided in the developing device
10
.
When the electrostatic latent image of the photoreceptor belt
1
arrives at the development roller
13
, the toner contained in the developer is moved to the region of the electrostatic latent image on the photoreceptor belt
1
to adhere thereto, due to an electric potential difference between the region of the electrostatic latent image and the development roller
13
. Since a portion of the photoreceptor belt
1
unexposed to the beam has a higher electric potential than that of the development roller, the developer is smeared on the belt
1
rather than the toner. The electrostatic latent image is filmed over with a portion of the toner adhering to the electrostatic latent image by the squeegee roller
14
depressing the photoreceptor belt
1
, and the developer with the rest of the toner is removed by the squeegee roller
14
.
The development is performed in such a manner so that the development roller
13
and the squeegee roller
14
, both in close contact to the photoreceptor belt
1
, depress the photoreceptor belt
1
, thereby spreading the developer over the rollers
13
,
14
. Consequently, the remaining developer not used for the development process is driven or pushed out toward both ends of the rollers
13
,
14
. The rollers
13
,
14
may be contaminated with the remaining ink, i.e., the ink pushed out which pollutes the peripheral devices including the photoreceptor belt
1
.
In
FIGS. 2 through 5
, a conventional ink contamination prevention device for preventing the contamination by the remaining ink described above is shown. The conventional ink contamination prevention device is provided with a pair of protrusions
40
,
40
′ for stopping a flow of the ink toward both ends of the development roller
13
.
As shown in
FIG. 4
, the ink contamination prevention device constructed in this manner can prevent the remaining ink
100
from flowing to the outside of the development roller
13
, since the protrusions
40
,
40
′ stop the flow of the remaining ink
100
.
However, as shown in
FIG. 5
, since the protrusions for stopping the flow of the remaining ink are formed in a simple annular shape around a shaft of the development roller
13
in the conventional ink contamination prevention device, when the development roller
13
rotates, there is a possibility of the remaining ink
100
accommodated in recesses defined by the protrusions
40
,
40
′, flowing to the outside of the development roller
13
beyond the protrusions
40
,
40
′. That is, stopping the flow of the remaining ink
100
is not fully achieved, thereby polluting the roller and the peripheral devices and degrading the lifetime of those components. Further, if the contamination by the remaining ink described above occurs in the squeegee roller
14
, the remaining ink may flow from an end of the squeegee roller
14
to the photoreceptor belt
1
to pollute the same, causing a degradation of the quality of the print.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the invention to provide an ink pollution prevention device capable of preventing remaining ink from polluting rollers, peripheral devices, and a photoreceptor such as a photoreceptor belt by fully stopping a flow of the remaining ink toward the outside of a roller at both ends of the roller.
In order to achieve the object, the present invention provides an ink pollution prevention device in a wet electrophotographic printer, for preventing a developer from polluting a photoreceptor and peripheral devices by flowing out at the ends of a development roller, a squeegee roller, and a cleaning roller to the outside of the rollers. The device is provided with a pair of ink stoppers, with stoppers disposed around both sides of a shaft of each roller in a symmetrical manner with each other. Each ink stopper has a plurality of peaks and recesses which form a continuous helical shape in an opposite helical direction from the other ink stopper. The helical shape of the ink stopper is oriented so as to permit the ink in the ink stopper to flow toward the center of the roller along the recesses, when the roller is rotated.
The ink stopper can be integrally formed with a shaft of each roller or independently formed and mounted on the shaft, as a fixed member.
REFERENCES:
patent: 5322298 (1994-06-01), Maier
patent: 6210103 (2001-04-01), Ramsay
patent: 3-67355 (1991-01-01), None
patent: 8-179634 (1996-12-01), None
patent: 2938003 (1999-11-01), None
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