Electrophotography – Image formation – Development
Reexamination Certificate
2000-07-31
2001-09-25
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Development
C399S348000, C399S251000
Reexamination Certificate
active
06295430
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drying unit coupling apparatus of a liquid electrophotographic printer.
2. Description of the Related Art
In general, a liquid electrophotographic printer such as a color laser printer or copying machine, as shown in
FIG. 1
, includes a developing unit
20
for developing a predetermined image on a photoreceptor medium
10
such as a photoreceptor web endlessly circulating, a drying unit
30
for drying liquid solution (hereinafter, referred to as carrier) remaining on the developed photoreceptor medium
10
, and a transferring unit
40
for transferring the developed image on the photoreceptor medium
10
to a sheet of paper S.
The drying unit
30
includes a drying roller
31
for absorbing the carrier remaining on the photoreceptor medium
10
as drying roller
31
rotates in contact with the photoreceptor medium
10
, and heating rollers
32
for vaporizing the carrier absorbed by the drying roller
31
by applying heat.
Here, during printing, the photoreceptor medium
10
, the drying roller
31
and the heating rollers
32
are driven in close contact with one another, as shown in the drawing. When driven, the drying roller
31
and the heating rollers
32
absorb and vaporize the carrier, respectively. Meanwhile, when printing is not performed for a long time, the photoreceptor medium
10
, the drying roller
31
and the heating rollers
32
need to be separated from one another. Also, in a printing-ready mode before printing begins, it is necessary to preheat the drying roller
31
to save the time needed for it to warm up. For preheating, in the printing-ready mode, the drying roller
31
is separated from the photoreceptor medium
10
and rotated by being in close contact with the heating rollers
32
. Thus, in the drying unit
30
, the drying roller
31
and the heating roller
32
are allowed to move within a range of a predetermined distance according to a printing mode, a printing-ready mode and a stop mode.
The photoreceptor medium
10
circulates by being wound around a driving roller
12
and rollers
14
and
15
, and its surface is uniformly charged by a charger
18
. A laser scanning unit
22
scans a laser beam onto the charged photoreceptor medium
10
according to a desired printing image. The surface of the photoreceptor medium
10
is selectively exposed to the scanned laser beam to form an electrostatic latent image. The electrostatic latent image is developed by developer adhering thereto, which is provided by the developing unit
20
. The developed developer is squeezed by the developing unit
20
and dried by the drying unit
30
, to thus form a desired image. The dried image is transferred to a sheet of paper S via the transferring roller
42
of the transferring unit
40
.
However, according to the conventional technology, when the photoreceptor medium
10
or the drying unit
30
needs repairing or replacement, performing repair or replacement is not possible in the state in which the drying roller
31
is separated a predetermined distance from the driving roller
12
, that is, in a stop mode. Also, since the drying unit
30
is formed of a single assembly, in order to perform the above works, the entire drying unit
30
must be disassembled and the drying roller
31
detached from the driving roller
12
or a main frame, which inconveniences a user. Accordingly, for the replacement of the photoreceptor medium or the repairing and replacement of the drying unit, more distance between the drying roller
31
and the photoreceptor medium
10
is needed than in a stop mode.
To overcome the above problem, an apparatus for separating a drying unit frame (where the drying roller is installed) a predetermined distance from the main frame (where the driving roller is installed) by using a cam member has been suggested in Korean Patent Application No. 98-44191. In the apparatus, a pair of gears are installed at the main frame and a cam shaft to correspond to each other and be meshed with each other when the main frame and an auxiliary frame, which supports the cam shaft, are coupled to each other. Thus, as the engaged gears rotate, the cam member pushes the drying unit frame in one direction so that the drying unit frame can be separated from or approach the main frame.
In the above apparatus, the gears stay engaged while an operation is performed in each of a stop mode, a printing-ready mode and a printing mode. However, when the engagement of the gears become loose due to movement of the drying unit or if the gears become improperly engaged, the gears may be damaged or an error may occur in the distance that the drying unit is separated from the main frame. Thus, it is necessary to constantly maintain the engagement of the gears when the drying unit is in close contact with the main frame.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a drying unit coupling apparatus of a liquid electrophotographic printer having an improved structure in which the engagement of the driving gear installed at the main frame and the driven gear installed at the cam shaft are prevented from disengaging when the auxiliary frame is coupled to the main frame.
Accordingly, to achieve the above objective, there is provided a drying unit coupling apparatus of a liquid electrophotographic printer, which comprises a main frame where a driving roller for supporting a photoreceptor medium operative to circulate is supported, a driving gear installed at the main frame, a cam shaft supported at an auxiliary frame which is slidably installed at the main frame, a drying unit frame where a drying roller for absorbing a liquid carrier remaining on the photoreceptor medium, a heating roller for heating the drying roller, and a separation plate and a contact plate are installed, a driven gear installed at the cam shaft and engaged with the driving gear when the auxiliary frame and the main frame are coupled, a cam member, installed at the cam shaft, for selectively pushing the separation plate or the contact plate so that the drying unit frame closely contacts or separates from the main frame, and a position fixing means for fixing the position of the cam shaft in a state of the driving gear and the driven gear being engaged, to prevent the driving gear and the driven gear from deviating from each other.
It is preferred in the present invention that the position fixing means comprises a position fixing bar extended from a rotation shaft of the driving gear, a slider, slidably installed at the cam shaft, having a position determination hole into which the position fixing bar is inserted, and a coupling/releasing means for coupling and releasing the position determination hole and the position fixing bar by selectively moving the slider.
Also, it is preferred in the present invention that the coupling/releasing means comprises a spring, installed at the cam shaft, for elastically pressing the slider so that the position determination hole is separated from the position fixing bar, and a pivot unit, installed at the auxiliary frame to be capable of pivoting, for pushing the slider toward the position fixing bar so that the position determination hole and the position fixing bar are coupled to each other.
Also, it is preferred in the present invention that the pivot unit comprises a support shaft rotatably installed at the auxiliary frame, a pivot member, fixed to the support shaft, having an inclined surface to contact the slider so as to push the slider toward the position fixing bar during rotation, and a handle lever, fixed to the support shaft and installed at a handle lever installation portion formed by penetrating the auxiliary frame to enable the handle lever to pivot with respect to the auxiliary frame.
Also, it is preferred in the present invention that a stopper portion is formed at the pivot member to be stepped, to limit a pivoting range of the pivot member by hooking one side of the slider.
Also, it is preferred in the present in
Chen Sophia S.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
Tran Hoan
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