Electrophotography – Image formation – Fixing
Reexamination Certificate
1999-12-23
2001-06-05
Moses, Richard (Department: 2852)
Electrophotography
Image formation
Fixing
C271S309000, C271S311000
Reexamination Certificate
active
06243556
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a claw apparatus for a liquid electrophotographic printer and, more particularly, to a claw apparatus for a liquid electrophotographic printer which can prevent a paper jam phenomenon from occurring as a sheet of paper passing between a transfer roller and a fixation roller adheres on and is rolled on the surface of the transfer roller by a peel force.
2. Description of the Related Art
In a typical liquid electrophotographic printer, an electrostatic latent image formed on a photoreceptor medium, such as a photoreceptor web, is developed with developer having a predetermined color, and a toner image formed on the photoreceptor medium is transferred to a sheet of paper to print a desired image.
As shown in
FIG. 1
, the typical liquid electrophotographic printer includes a photoreceptor medium
1
circulating in a direction indicated by arrow A, and a development unit
2
disposed under the photoreceptor medium
1
. An electrostatic latent image is formed by a laser scanning unit LSU (not shown) on the surface of the photoreceptor medium
1
. The electrostatic latent image is developed by toner of the developer injected by the development unit
2
and a toner image is formed. The toner image is transferred to a sheet of paper
7
by a transfer unit
10
. The transfer unit
10
includes a transfer roller
3
for receiving the toner image formed on the photoreceptor medium
1
due to the difference in surface energy between the photoreceptor medium
1
and the transfer roller
3
, and a fixation roller
4
for pressing the transfer roller
3
to transfer the image on the transfer roller
3
to the paper
7
utilizing the difference in surface energy between the transfer roller
3
and the paper
7
. Reference numeral
5
denotes a backup roller for supporting the photoreceptor medium
1
and guiding circulation of the photoreceptor medium
1
.
As it is well-known, not only the surface of the photoreceptor medium
1
can be charged by a charger (not shown), but also the level of electric potential of the surface of the photoreceptor medium
1
can be selectively converted by beam scanning of the laser scanning unit. In a typical liquid electrophotographic printer, the entire surface of the photoreceptor medium
1
is charged by a corona charge to an electric potential of about 600 volts and the electric potential of the surface of the photoreceptor medium
1
is selectively dropped to about 150 volts by the laser scanning unit, so that a predetermined electrostatic latent image is formed. When toner charged to the electric potential of about 450 volts is added to the above electrostatic latent image, the toner adheres to only a portion where the level of electric potential is dropped and accordingly an image is formed.
A conventional claw apparatus
6
is installed adjacent to the transfer roller
3
to prevent a jam occurring as the paper
7
passing between the transfer roller
3
and the fixation roller
4
proceeds while adhering to the surface of the transfer roller
3
due to a peel force. This is because the jam phenomenon can be prevented when the leading end of the claw apparatus
6
is disposed at least at a point where the leading end of the paper
7
is separated about 0.5 mm from a contact point between the transfer roller
3
and the fixation roller
4
. However, as the leading end of the claw apparatus
6
has a mechanical allowance of ±0.2 mm, the jam phenomenon is difficult to eliminate unless the claw apparatus
6
is precisely processed. Also, to provide an additional unit to prevent the jam phenomenon makes the structure of the printer more complicated.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a claw apparatus for a liquid electrophotographic printer having an improved structure in which a claw is configured into two pieces forming an injection hole and simultaneously air can be injected through the injection hole so that the above paper jam phenomenon can be prevented.
Accordingly, to achieve the above objective, there is provided a claw apparatus for a liquid electrophotographic printer for preventing a sheet of paper passing through a transfer roller and the fixation roller from adhering to and curling around the transfer roller due to a peel force, in which the claw apparatus includes a guide portion which guides the paper passing between the transfer roller and the fixation roller, a curved portion encompassing a portion of an outer circumferential surface of the transfer roller, and an injection portion, formed at the curved portion, which injects air through a gap formed between the curved portion and the transfer roller so that the paper passing between the transfer roller and the fixation roller can be guided toward the guide portion.
It is preferable in the present invention that a plurality of indentations are formed on the surface of the guide portion to prevent damage to an image transferred to the paper.
Also, it is preferable in the present invention that the injection portion is formed by coupling a first piece where an air path is formed and a second piece where an injection inlet connected to the air path is formed.
Also, it is preferable in the present invention that the first piece further comprises a support portion integrally formed with the first piece so that the first piece can be supported by both ends of the transfer roller.
Also, it is preferable in the present invention that a plurality of coupling holes operative to be coupled to a main body of the printer are formed in the second piece to prevent deformation of the second piece.
REFERENCES:
patent: 3784190 (1974-01-01), Crawford
patent: 3981085 (1976-09-01), Franko
patent: 4061330 (1977-12-01), Yanagawa
patent: 4364657 (1982-12-01), Landa
patent: 4420152 (1983-12-01), Miyashita
patent: 5406363 (1995-04-01), Siegel
patent: 51-104350 (1976-09-01), None
patent: 58-74265 (1983-05-01), None
patent: 8-227227 (1996-09-01), None
Moses Richard
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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