Electrophotography – Image formation – Development
Reexamination Certificate
1999-11-16
2001-04-10
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06215973
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a squeegee roller cleaning apparatus for a liquid electrophotographic printer and, more particularly, to a squeegee roller cleaning apparatus for a liquid electrophotographic printer having a blade with an improved structure and shape for removing developer remaining between a squeegee roller and a photoreceptor web.
2. Description of the Related Art
FIG. 1
shows the structure of a conventional liquid electrophotographic printer. Referring to
FIG. 1
, a development unit of a conventional liquid electrophotographic printer includes a photoreceptor web
10
circulating by being supported by a plurality of rollers
11
, a tray
12
installed under the photoreceptor web
10
for collecting developer remaining after being used for development, a development roller
14
supported by a development frame (not shown) and moving up and down by an elevating means (not shown), a manifold
20
for injecting developer into a gap G (hereinafter, referred to as a development gap) formed between the development roller
14
and the photoreceptor web
10
, a development tank
13
for collecting and holding the developer injected into the development gap G, a development roller cleaning apparatus for removing developer adhering to the outer circumferential surface of the development roller
14
, and a developer removing means for removing developer remaining on the photoreceptor web
10
after being used for the development.
The development roller cleaning apparatus consists of a brush roller
18
for cleaning developer adhering to the development roller
14
, by being supported by the development tank
13
and rotating in contact with the development roller
14
, and a development blade
22
having one end in contact with the outer circumference of the development roller
14
and the other end assembled to the body of the manifold
20
, for removing developer remaining between the brush roller
18
and the development roller
14
and transferred to the surface of the development roller
14
. Reference numeral
24
denotes a packing member for discharging developer in the development tank
13
into the tray
12
and reference numeral
26
denotes a stopper for limiting the movement of the packing member
24
.
The developer removing means consists of a squeegee roller
15
installed adjacent to the development roller
14
for pressing and removing developer adhering to the photoreceptor web
10
, an air injection nozzle
16
for removing developer by injecting air into a portion where the squeegee roller
15
contacts the photoreceptor web
10
, a squeegee blade
17
for removing developer flowing down along the outer circumference of the squeegee roller
15
while being in contact with the surface of the squeegee roller
15
.
During development, the development roller
14
ascends toward the photoreceptor web
10
to maintain the development gap G in the tray
12
. As the development roller
14
moves, the development tank
13
and the manifold
20
are moved upward together. The manifold
20
injects developer into the development gap G and, as the development roller
14
rotates, an area for an electrostatic latent image formed on the surface of the photoreceptor web
10
is developed. Developer carrier adhering to the area for an electrostatic latent image on the photoreceptor web
10
is removed by the developer removing means.
In other words, the squeegee roller
15
is in contact with the photoreceptor web
10
and passively rotated thereby in a direction in which the photoreceptor web
10
travels. In doing so, the squeegee roller
15
presses the developer adhering to the electrostatic latent image area so that toner becomes filmy and most of the carrier other than the filmy toner is removed. Here, the air injection nozzle
16
injects air toward the squeegee roller
15
. That is, the carrier squeezed by the squeegee roller
15
flowing along a contact line between the squeegee roller
15
and the photoreceptor web
10
meets the air injected by the air injection nozzle
16
to scatter and fall downward. Here, the blade
17
maintains a state of being separated a predetermined distance from the outer circumferential surface of the squeegee roller
15
.
As shown in
FIG. 2
, after the development mode is terminated, the development roller
14
descends in the tray
12
. As the development roller
14
moves down, the packing member
24
contacting the stopper
26
relatively ascends to open a lower portion of the development tank
13
. Thus, the developer in the development tank
13
is discharged into the tray
12
.
However, a drip-line is generated as developer continues to remain between the photoreceptor web
10
and the squeegee roller
15
. The drip-line is generated when developer gathers at a portion where the squeegee roller
15
and the photoreceptor web
10
closely contact each other during development. To remove the drip-line developer, in a state in which the operating speed of the photoreceptor web
10
is reduced, a pressing force of the squeegee roller
15
which presses the photoreceptor web
10
is slightly reduced. Then, by driving the squeegee roller
15
to rotate in the reverse direction to the direction in which the photoreceptor web
10
travels, the drip-line developer is removed due to the rotation of the squeegee roller
15
. The removed developer flows down along the squeegee roller
15
and falls into the tray
12
by being wiped by the blade
17
. The developer falling into the tray
12
is collected on the bottom surface of the tray
12
and supplied to a circulation tank (not shown).
In the developer removing means of the development unit having the above structure, the squeegee blade
17
must satisfy the conditions as follows.
First, the developer falls downward without a hold up volume phenomenon occurring when the developer is maintained at a contact point between the leading edge of the blade and the squeegee roller, so that developer does not adhere to the surface of the blade.
Second, the developer must be completely removed so that the developer does not remain on the surface of the squeegee roller.
Third, the blade must not be flipped over to the reverse due to a rotational moment by the rotation of the squeegee roller. That is, as the blade is deformed by the friction with the squeegee roller, the leading edge of the blade must not be lifted, either partially or entirely, from the surface of the squeegee roller.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a squeegee roller cleaning apparatus for a liquid electrophotographic printer in which the structure and shape of the blade are improved so that the efficiency in removing the developer remaining between the photoreceptor web and the squeegee roller is increased.
Accordingly, to achieve the above objective, there is provided a squeegee roller cleaning apparatus for a liquid electrophotographic printer, which comprises a plate installed at a tray, parallel to the axial direction of a squeegee roller, under a photoreceptor web to be capable of pivoting, a surface-contact blade member supported at the plate so as to selectively surface-contact the outer circumferential surface of the squeegee roller, an elastic spring coupled between the tray and the plate, and a means for making the plate pivot such that the surface-contact blade member can contact or be separated from the outer circumferential surface of the squeegee roller.
It is preferred in the present invention that the pivot means comprises a cam member installed at the tray to be capable of rotating so as to contact the plate, and a driving motor for driving the cam member.
Also, it is preferred in the present invention that the surface-contact blade member comprises a surface contact portion disposed to be inwardly rounded to the outer circumferential surface of the squeegee roller.
Also, it is preferred in the present invention that the radius of the surface-contact portion is less than t
Royer William J.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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