Electrophotography – Control of electrophotography process – Responsive to number of copies or passage of time
Reexamination Certificate
1999-12-23
2001-02-27
Chen, Sophia S. (Department: 2852)
Electrophotography
Control of electrophotography process
Responsive to number of copies or passage of time
C399S036000, C399S237000, C399S251000, C430S117200
Reexamination Certificate
active
06195514
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid image forming apparatus and a method thereof, and more particularly, to a liquid image forming apparatus which can reduce deformation of an image film formed on a photoreceptor web, and a method thereof.
2. Description of the Related Art
An image forming apparatus is divided into a liquid type and a dry type according to the type of developer used. The liquid image forming apparatus uses developer in which toner in a powder state is distributed in a volatile liquid carrier. In the liquid imaging system, an electrostatic latent image is formed by emitting a laser beam onto a photoreceptor web or organic photoreceptor (OPR) circulating along an endless path. Liquid toner is supplied to develop the electrostatic latent image into a toner image and the toner image is transferred to a printing paper.
FIG. 1
shows the structure of a conventional imaging system. Referring to
FIG. 1
, a photoreceptor web
110
is supported by a backup roller
111
, a steering roller
112
, and a driving roller
113
. The backup roller
111
presses the photoreceptor web
110
to provide a predetermined pressure to the transfer roller
114
installed adjacent thereto to transfer a toner image in a film state formed on the photoreceptor web to the transfer roller
114
. A press roller
115
in contact with the transfer roller
114
at a predetermined pressure is installed at one side of the transfer roller
114
to transfer the toner image adhering to the transfer roller
114
to a print paper
116
passing between the transfer roller
114
and the press roller
115
.
An image forming apparatus
200
for forming the toner image on a surface of the photoreceptor web
110
is disposed along the photoreceptor web
110
between the steering roller
112
and the driving roller
113
. The image forming apparatus
200
includes laser scanning units (LSU's)
202
a
,
202
b
,
202
c
, and
202
d
, using a laser beam and developing units
201
a
,
201
b
,
201
c
, and
201
d
, which are alternately installed. For each color, that is, yellow, magenta, cyan and black, a laser scanning unit and a developing unit adjacent thereto form a toner image unit.
The laser scanning units
202
a
,
202
b
,
202
c
, and
202
d
, emit a laser beam onto the surface of the photoreceptor web
110
according to an image signal per color to form an electrostatic latent image. The developing units
201
a
,
201
b
,
201
c
, and
201
d
, develops the latent image formed by the laser scanning units to a toner image.
The developing units
201
a
,
201
b
,
201
c
, and
201
d
, of the image forming apparatus
200
each include a developing roller for coating a developer of a predetermined color on the photoreceptor web
110
, and a squeeze roller for removing excess developer coated on the photoreceptor web
110
.
An image drying roller
120
for removing liquid carrier remaining on the toner image from the photoreceptor web
110
is provided to be adjacent to the driving roller
113
. The surface of the image drying roller
120
consists of an outer surface having an affinity for oil for absorbing the liquid carrier from the photoreceptor web
110
and an inner surface disposed under the outer surface and having an anti-oil characteristic for preventing intrusion of the liquid carrier. The image drying roller
120
absorbs the liquid carrier remaining on the surface of the photoreceptor web
110
while being rotated in contact with the photoreceptor web
110
. Two heating rollers
121
and
122
separated a predetermined distance from each other are in contact with the image drying roller
120
. The heating rollers
121
and
122
heat the image drying roller
120
and vaporizes the liquid carrier absorbed in the surface thereof. The vaporized liquid carrier is collected by an additional collection apparatus (not shown).
In the conventional image forming apparatus
200
having the above structure, the image drying roller
120
performs a rolling movement while contacting the photoreceptor web
110
. The image drying roller
120
should rotate adaptively corresponding to the movement of the photoreceptor web
110
. If the image drying roller
120
rotates not complying with the movement of the photoreceptor web
110
, the image drying roller
120
slips on the photoreceptor web
110
. The slippage of the image drying roller
120
results in abrasion of the surface of the photoreceptor web
110
, thus damaging the toner image on the photoreceptor web
110
.
Damage to the toner image due to slippage of the image drying roller
120
occurs when the liquid carrier absorbed in the surface of the image drying roller
120
is accumulated over a predetermined degree. Particularly, when the image processing is performed for a long time and the amount of vaporization of the liquid carrier by the heating rollers
121
and
122
continuously exceeds that of the liquid carrier absorbed from the photoreceptor web
110
, the image drying roller
120
slips on the photoreceptor web
110
.
The slippage phenomenon also occurs when the image drying roller
120
continuously absorbs the liquid carrier while contacting the photoreceptor web
110
so that an appropriate temperature is not maintained during the continuous formation of an image. Such a phenomenon occurs at the conventional image forming apparatus so that a desired quality image cannot be obtained.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide a liquid image forming apparatus which can form a quality image, and a method thereof.
Accordingly, to achieve the above objective, there is provided a liquid image forming apparatus including at least a driving roller, a photoreceptor web circulating along an endless path by a backup roller and a steering roller, an image forming portion for forming a toner image on the photoreceptor web with liquid toner including a liquid carrier, an image drying roller for absorbing the liquid carrier remaining on the photoreceptor web while performing a rolling movement in contact with the photoreceptor web, a heating roller for heating the image drying roller, and a transfer roller for pressing the photoreceptor web against the backup roller at a predetermined pressure to transfer the toner image attached to the photoreceptor web to a printing paper. The liquid image forming apparatus includes a rotation speed detection portion provided at one side of the image drying roller for detecting a rotation speed of the image drying roller, a speed comparison portion for determining whether the image drying roller is rotating at normal speed by comparing the rotation speed of the image drying roller detected by the rotation speed detection portion with a predetermined range of a reference rotation speed; and a controlling portion for making the heating roller heat the image drying roller to a reference temperature to vaporize the liquid carrier absorbed by the image drying roller when it is determined from a signal from the speed comparison portion that the image drying roller does not maintain the regular speed.
It is preferable in the present invention that, when the image drying roller is not maintained at the normal speed, the controlling portion makes the image drying roller become separated from the photoreceptor web after a unit toner image presently processed is completely transferred to the printing paper by the transfer roller.
According to another aspect of the above invention, there is provided a method for forming an image by a liquid image forming apparatus including at least a driving roller, a photoreceptor web circulating along an endless path by a backup roller and a steering roller, an image forming portion for forming a toner image on the photoreceptor web with liquid toner including a liquid carrier, an image drying roller for absorbing the liquid carrier remaining on the photoreceptor web while performing a rolling movement in contact with the photoreceptor web, a heating roller for heating
Chen Sophia S.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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