Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
1999-07-21
2001-01-30
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Photoconductive member
C198S806000
Reexamination Certificate
active
06181900
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a photoreceptor belt control apparatus, for a printer, which steers a photoreceptor belt, and applies tension to and removes tension from the photoreceptor belt. More particularly, the present invention relates to a photoreceptor belt control apparatus for preventing the photoreceptor belt from traveling laterally, and for applying tension to and releasing tension from the photoreceptor belt by driving auxiliary frames that support a steering roller.
2. Description of the Related Art
A general printer, such as a laser printer, forms a latent electrostatic image by scanning a photoreceptor belt using a laser scanning unit, develops the latent electrostatic image with a color ink using a developing unit, and transfers the developed image onto a printing paper.
Referring to
FIG. 1
, a general printer includes a photoreceptor belt
10
that circulates continuously around a set of rollers
12
,
14
and
21
installed in the main body of the printer. The general printer further includes an erase lamp
15
for erasing a surface potential formed on the photoreceptor belt
10
, a charger
17
for charging the photoreceptor belt
10
with a predetermined potential, a plurality of laser scanning units (LSU)
18
for scanning the photoreceptor belt
10
with laser beams to form latent electrostatic images for respective colors, and a plurality of developing units
19
for developing the latent electrostatic images.
As the photoreceptor belt
10
circulates around the rollers
12
,
14
and
21
, it tends to travel laterally, i.e., in the length direction of the rollers
12
,
14
, and
21
. Also, it is necessary to release the tension in the photoreceptor belt
10
, for example, upon attachment and detachment of a belt unit including the photoreceptor belt
10
and the rollers
12
,
14
, and
21
.
Referring to
FIGS. 1 and 2
, a conventional photoreceptor belt control apparatus for the general printer includes a photoreceptor belt steering unit
20
for correcting the lateral travel of the photoreceptor belt
10
on the basis of information detected by a lateral travel detector (not shown), and a tension applying/releasing unit
40
for controlling the tension in the photoreceptor belt
10
.
The photoreceptor belt steering unit
20
includes a frame
23
installed on a printer main body
1
, a pivot member
25
pivotally installed on the frame
23
, a steering roller
21
installed on the pivot member
25
for supporting the photoreceptor belt
10
so that the photoreceptor belt
10
rotates along a fixed path, a pair of stable rollers
27
installed on the frame
23
to prevent the photoreceptor belt
10
from being crumpled as it passes over the steering roller
21
, and a control unit
30
installed on the printer main body
1
for controlling the upward and downward (direction indicated by arrow A) tilt of the steering roller
21
.
The tension applying/releasing unit
40
includes a guide bar
41
with one end hinged to the center of the pivot member
25
, a first cam member
43
, an elastic member
45
installed on the outer circumference of the guide bar
41
, the elastic member
45
having ends that respectively contact the first cam member
43
and the frame
23
, and a control knob
47
for controlling the first cam member
43
. The control knob
47
controls the elasticity of the elastic member
45
to adjust the pressure of the steering roller
21
against the photoreceptor belt
10
, thereby adjusting the tension in the photoreceptor belt
10
.
The pivot member
25
is coupled to the guide bar
41
by a coupling pin
39
, and pivots in an X-Y plane about the coupling pin
39
. The pivot member
25
pivots in a direction to compensate for an unbalanced pressure that the steering roller
21
applies against the photoreceptor belt
10
. A sliding plate
46
is slidably installed on the outer circumference of the guide bar
41
so as to compress the elastic member
45
according to the rotation position of the first cam member
43
.
A shaft
21
a
of the steering roller
21
is inserted into a holding hole
25
a
formed in the pivot member
25
. An elastic piece
26
, for pressing the shaft
21
a
of the steering roller
21
into the holding hole
25
a
, is installed on the pivot member
25
adjacent to the holding hole
25
a.
The control unit
30
includes a driving motor
31
fixed to the printer main body
1
, a second cam member
33
whose center is combined with a shaft
31
a
of the driving motor
31
, the second cam member
33
having a cam hole
33
a
, and a rotating guide protrusion
35
coupled to the pivot member
25
and inserted into the cam hole
33
a
. The position of the cam hole
33
a
varies with the rotation of the driving motor
31
, thereby changing the relative position of the rotating guide protrusion
35
. The steering roller
21
pivots on the guide bar
41
in the direction indicated by arrow A.
When a lateral travel degree of the photoreceptor belt
10
is detected by the lateral travel detector, the second cam member
33
rotates to adjust the tilt of the steering roller
21
. The tilt of the steering roller
21
causes the photoreceptor belt
10
to return to its initial lateral position. In this way, the lateral travel of the photoreceptor belt
10
is corrected.
The pair of stable rollers
27
are installed parallel to the steering roller
21
, and respectively contact a portion of the photoreceptor belt
10
heading for the steering roller
21
and a portion of the photoreceptor belt
10
that has passed across the steering roller
21
. These stable rollers
27
prevent the photoreceptor belt
10
from crumpling.
Although generally thought to be acceptable, the conventional photoreceptor belt control apparatus is not without shortcomings. In particular, the steering roller
21
pivots about the coupling pin
39
, which is located at the end of the guide bar
41
. This pivoting action requires structure that occupies valuable internal space in a printer main body. The structure includes the pivot member
25
, guide bar
41
, and frame
23
. Thus, the miniaturization of the photoreceptor belt control apparatus is limited.
Also, the first cam member
43
adjusts the elastic force applied to the guide bar
41
, and thus the tension in the photoreceptor belt
10
is adjustable. This conventional structure, however, does not allow a convenient retreating movement of the steering roller
21
in the direction indicated by arrow X.
SUMMARY OF THE INVENTION
To solve the above problems, the present photoreceptor belt control apparatus for a printer controls the tension in the photoreceptor belt by driving auxiliary frames installed on both ends of a steering roller, thereby guiding the tilt of the steering roller.
Accordingly, there is provided a photoreceptor belt control apparatus for a printer designed to correct lateral travel of a photoreceptor belt supported by rollers rotatably installed on a belt frame, and/or to control the tension of the photoreceptor belt. The apparatus comprises: a belt frame; a pair of auxiliary frames slidably and pivotally installed on the belt frame; a steering roller whose ends are rotatably installed respectively on the auxiliary frames, the steering roller rotating in contact with the photoreceptor belt; a shaft whose ends are rotatably installed on the belt frame; a cam unit installed on at least one end of the shaft for controlling the inclination of the steering roller by pivoting each of the auxiliary frames according to the rotational position of the shaft; and a tension control unit for controlling tension in the photoreceptor belt by sliding the pair of auxiliary frames.
REFERENCES:
patent: 3500694 (1970-03-01), Jones et al.
patent: 3801092 (1974-04-01), Jordan
patent: 4061222 (1977-12-01), Rushing
patent: 4674858 (1987-06-01), Nagayama
patent: 5078263 (1992-01-01), Thompson et al.
patent: 5659851 (1997-08-01), Moe et al.
patent: 5784676 (1998-07-01), Iseki et al.
patent: 0 818 715 (1998-01-01), None
patent: 62-272
Bang Jung-hun
Lee Jong-Chan
Lee Min-soo
Royer William J.
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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