Liquid electrophotographic image forming apparatus

Details Liquid electrophotographic image forming apparatus Liquid electrophotographic image forming apparatus

2003-03-25

2004-03-23

Ngo, Hoang (Department: 2852)

Electrophotography

Image formation

Development

C399S238000, C399S239000

Reexamination Certificate

active

06711370

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 2002-39151 filed Jul. 6, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid electrophotographic image forming apparatus, and more particularly, to a liquid electrophotographic image forming apparatus in which a developer, to develop an image formed on a photosensitive body and an ink reservoir to supply ink to the developer are formed monolithically.
2. Description of the Related Art
In general, electrophotographic image forming apparatuses form an electrostatic latent image on a photosensitive medium, such as a photosensitive drum or photosensitive belt, develop the electrostatic latent image by a developing agent of a predetermined color, and transfer the developed image onto a sheet of paper, thereby forming a desired image.
Such electrophotographic image forming apparatuses are classified into a dry type and a wet type according to the type of the developing agent. Dry type image forming apparatuses use toner in a powder state, while liquid image forming apparatuses use a liquid developing agent, in which the toner is mixed with a volatile liquid carrier. The liquid image forming apparatuses have better printing quality than the dry type image forming apparatuses and reduce the risks of health problems caused by harmful toner dust.
FIG. 1
schematically shows the structure of a conventional liquid color image forming apparatus.
Referring to
FIG. 1
, a plurality of image forming units are arranged serially along a circulation route of a transfer belt
40
, which moves on an endless track by a plurality of rollers
41
,
42
, and
44
. Each of the image forming units transfers cyan (C), magenta (M), yellow (Y), and black (K) images, respectively, onto the transfer belt
40
.
Each image forming unit includes a photosensitive drum
30
, which transfers a toner image of a predetermined color onto the transfer belt
40
; a charger
36
, which charges the surface of the photosensitive drum
30
at a predetermined electric potential; a laser scanning unit (LSU)
38
, which forms an electrostatic latent image by radiating light onto the charged surface of the photosensitive drum
30
; a developing unit
10
, which develops the electrostatic latent image into a predetermined toner image; and a cleaning blade
32
, which removes a developing agent remaining on the photosensitive drum
30
after the developed toner image is transferred onto the transfer belt
40
. Reference numeral
34
denotes an eraser that erases an electric potential on the photosensitive drum
30
.
When the transfer belt
40
is supported and rotated by a driving roller
41
, a second transfer backup roller
44
and a plurality of first transfer backup rollers
42
corresponding to the photosensitive drum
30
, the image that is formed on the photosensitive drum
30
is transferred onto the transfer belt
40
. A second transfer roller
43
is installed to rotate in a direction opposite to the rotation of the second transfer backup roller
44
, and the transfer belt
40
is placed between the second transfer backup roller
44
and the second transfer roller
43
. The second transfer roller
43
transfers the image on the transfer belt
40
onto a sheet of paper
60
.
The paper
60
onto which the color image is transferred by the second transfer roller
43
is heated at a predetermined temperature and pressurized by a fusing unit
50
installed on a paper ejecting route, and the toner image is fixed on the paper
60
.
FIG. 2
shows a detailed diagram of the image forming unit of FIG.
1
and illustrates a magenta developing unit
10
-M among developing units having the same structure of FIG.
1
.
Referring to
FIG. 2
, the developing unit
10
includes a developing portion
11
, an ink reservoir
12
in which ink supplied to the developing portion
11
is stored, and a circulating portion
13
which circulates ink between the developing portion
11
and the ink reservoir
12
.
The developing portion
11
includes a developing container
14
in which a developing agent (hereinafter, referred to as ink) is stored; a developing roller
15
, part of which is dipped in the developing agent and installed to face the photosensitive drum
30
; a depositing roller
16
; a cleaning roller
17
; and a metering roller
18
.
Part of the developing roller
15
is dipped in the developing agent stored in the developing container
14
. The depositing roller
16
is dipped in the developing agent stored in the developing container
14
, and a predetermined voltage is applied to the depositing roller
16
being spaced apart from the developing roller
15
by a predetermined gap. The depositing roller
16
deposits the developing agent onto the surface of the developing roller
15
utilizing a difference in an electric potential between the depositing roller
16
and the developing roller
15
having the predetermined voltage.
The metering roller
18
is installed to be adjacent to the developing roller
15
and regulates the developing agent placed on the developing roller
15
to a predetermined thickness.
An ink feed hole
19
and an ink exhaust hole
20
are provided in the developing container
14
. The circulating portion
13
includes an ink feed route
21
that connects the ink reservoir
12
to the ink feed hole
19
of the developing container
14
, and an ink withdrawal route
22
that connects the ink reservoir
12
to the ink exhaust hole
20
of the developing container
14
. A pump
23
is installed on the ink feed route
21
.
Ink withdrawn from the ink reservoir
12
by the pump
23
is supplied to the developing container
14
via the ink feed route
21
connected to the ink feed hole
19
. Since the developing agent in the developing container
14
is maintained at a uniform level, ink that exceeds this level is withdrawn to the ink reservoir
12
via the ink withdrawal route
22
connected to the ink exhaust hole
20
.
According to the above-mentioned structure, ink withdrawn from the ink reservoir
12
passes through the ink feed route
21
, the developing container
14
, and the ink withdrawal route
22
, back to the ink reservoir
12
.
However, according to the structure of
FIG. 2
, an additional ink reservoir
12
is needed to supply ink to the developing portion
11
, a hose is required to form an ink circulation route between the ink reservoir
12
and the developing container
14
, and the pump
23
is used to supply ink, thereby increasing the volume of the image forming apparatus. In addition, the hose may be clogged by ink. Thus, when replacing the hose or ink reservoir
12
with another one, it is difficult to attach and detach a coupler (not shown) to and from the hose or ink reservoir
12
, and accordingly, ink may leak out of the unit.
SUMMARY OF THE INVENTION
Accordingly, it is an aspect of the present invention to provide a liquid image forming apparatus in which a developing portion and an ink reservoir are formed monolithically and a unit to supply ink to the developing portion.
Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
The foregoing and/or other aspects of the present invention are achieved by providing a liquid image forming apparatus comprising: a developing portion in which a developing roller to develop an electrostatic latent image formed on a photosensitive body in a predetermined color is installed and which is maintained at a uniform level so that the developing roller is dipped at a predetermined level; an ink reservoir in which ink supplied to the developing portion is stored; and an ink supplying unit that supplies ink stored in the ink reservoir to the developing portion. The developing portion and the ink reservoir are provided in one developing container. Th

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