Electrophotography – Image formation – Development
Reexamination Certificate
2002-01-15
2004-08-17
Beatty, Robert (Department: 2852)
Electrophotography
Image formation
Development
C192S048920
Reexamination Certificate
active
06778798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotating force transmitting apparatus for transmitting a rotating force and an image forming apparatus such as a copying machine, a printer, a facsimile machine, and the like that is equipped with the rotating force transmitting apparatus and employs an electrophotographic process, an electrostatic recording process or the like.
2. Description of Related Art
The principal part of a full color electrostatic copying machine being an example of an image forming apparatus equipped with a rotating force transmitting apparatus will be described.
The full color electrostatic copying machine records an image having a plurality of colors on a recording medium by means of a digital image printer portion (hereinafter referred to as a “printer portion”) on the basis of image information from a color image reader portion (hereinafter referred to as a “reader portion”) for reading the image information on an original.
As shown in
FIG. 5
, in the printer portion, a pre-exposure lamp
11
, a corona charger
2
, a laser exposure optical system (not shown), a Y-developing unit
4
y
, a C-developing unit
4
c
, an M-developing unit
4
m
and a Bk-developing unit
4
Bk being four developing devices for different colors, means
13
for detecting a quantity of light on the photosensitive drum
1
, a transferring apparatus (not shown), a cleaning device
6
and the like are disposed around the photosensitive drum
1
being a latent image bearing member. The Y-developing unit
4
y
is a developing unit for yellow. The C-developing unit
4
c
is a developing unit for cyan. The M-developing unit
4
m
is a developing unit for magenta. The Bk-developing unit
4
Bk is a developing unit for black.
When an image is formed by the printer portion, the charger
2
uniformly charges the photosensitive drum
1
after the photosensitive drum
1
has rotated in the direction indicated by the arrow to eliminate residual charges on the outer periphery of the photosensitive dram
1
with the pre-exposure lamp
11
. Then, light images E are irradiated on the photosensitive drum
1
so that latent images of respective separated colors of the light images E are formed on the photosensitive drum
1
.
Next, the latent images on the photosensitive drum
1
are developed by the operations of the developing units
4
y
,
4
c
,
4
m
and
4
Bk corresponding to each separated color, and the images of toner being a powder developer having a base composed of a resin and a pigment are formed on the photosensitive drum
1
. Incidentally, the developing units
4
y
,
4
c
,
4
m
and
4
Bk are configured to approach the photosensitive drum
1
alternatively correspondingly to each separated color by the operations of respective eccentric cams
24
y
,
24
c
,
24
m
and
24
Bk.
On the other hand, a recording material being a recording medium contained in a recording-material cassette (not shown) is fed to a transferring portion formed between the photosensitive drum
1
and the transferring apparatus (not shown) by the conveying system of the electrostatic copying machine, and the toner images on the photosensitive drum
1
are transferred on the recording material by the transferring apparatus. After that, the recording material on which the color image is formed is delivered to the outside.
The rotating force transmitting apparatus
100
for rotating each of the developing units
4
y
,
4
c
,
4
m
and
4
Bk for each color will be described.
FIG. 6
is an expanded view of the rotating force transmitting apparatus
100
. A rotating force from a drive motor (not shown) is transmitted to an input pulley
102
, an input shaft
103
and a distributing gear
104
by a timing belt
101
. The distributing gear
104
engages with an M-clutch gear
109
m
, a C-clutch gear
109
c
and idler gears
105
and
107
. A rotating force from the idler gear
105
is transmitted to a Bk-clutch gear
109
Bk through the idler gear
106
, and a rotating force form the idler gear
107
is transmitted to a Y-clutch gear
109
y
through the idler gear
108
.
Now, when an M-clutch
110
m
is turned on, the M-developing unit
4
m
is rotated through an output shaft
111
m
, an output gear
112
m
and a sleeve gear
113
m
. Similarly, when a C-clutch
110
c
is turned on, the C-developing unit
4
c
is rotated through an output shaft
111
c
, an output gear
112
c
and a sleeve gear
113
c
. When a Y-clutch
110
y
is turned on, the Y-developing unit
4
y
is rotated through an output shaft
111
y
, an output gear
112
y
and a sleeve gear
113
y
. When a Bk-clutch
110
Bk is turned on, the Bk-developing unit
4
Bk is rotated through an output shaft
111
Bk, an output gear
112
Bk and a sleeve gear
113
Bk. A pair of supporting plates
114
and
115
supports the input shaft
103
and the output shafts
111
m
,
111
c
,
111
y
and
111
Bk rotatably.
The operations of the pressure of each of the developing units
4
y
,
4
c
,
4
m
and
4
Bk, clutching timing and the like will be described.
The operations will be described with reference to the timing charts of
FIG. 7
, FIG.
8
and FIG.
9
. Hereupon, concrete numerical values are set for making the descriptions of the operations easy to understand. Incidentally, the numerical values are for the sake of reference, and the related art is not restricted to the numerical values.
The diameter of the photosensitive drum
1
is set at 180 mm, and the peripheral speed (or the image-forming process speed) of the photosensitive drum
1
is set at 200 mm/sec. The developing units
4
y
,
4
c
,
4
m
and
4
Bk are disposed around the photosensitive drum
1
within an angular range of 0 degrees to 100 degrees with respect to a horizontal direction in the clockwise direction equidistantly (at the interval of 33.3 degrees) in the order of yellow (Y), cyan (C), magenta (M) and black (Bk). The order of developing is M, C, Y and Bk.
A case where an image of the A-4 size is continuously copied in a full color copying mode will be described.
Abscissa axes of the timing charts shown in
FIG. 7
to
FIG. 9
indicate time (or distance).
FIG. 9
is an enlarged view of the M-developing operation shown in FIG.
7
and FIG.
8
. The waveforms in the top row to the third row in
FIGS. 7 and 8
indicate latent images on the photosensitive drum
1
at the M-developing position, the pressuring operation of the M-developing unit
4
m
to the latent images, and the on-off actions of the M-clutch
110
m
, respectively. Because the latent images for two prints are formed on the photosensitive drum
1
during the rotation of the photosensitive drum
1
in the A-4 continuous copying mode, a reference mark M
1
designates a latent image of magenta in the copy on the first sheet, and a reference mark M
2
designates a latent image of magenta in the copy on the second sheet.
Similarly, the waveforms in the fourth row to the sixth row in
FIG. 7
indicate latent images on the photosensitive drum
1
at the C-developing position, the pressuring operation of the C-developing unit
4
c
, and the actions of the C-clutch
110
c
, respectively. The waveforms in the seventh row to the ninth row in
FIG. 7
indicate latent images on the photosensitive drum
1
at the Y-developing position, the pressuring operation of the Y-developing unit
4
y
, and the actions of the Y-clutch
110
y
, respectively. The waveforms in the tenth row to the twelfth row in
FIG. 7
indicate latent images on the photosensitive drum
1
at the Bk-developing position, the pressuring operation of the Bk-developing unit
4
Bk, and the actions of the Bk-clutch
110
Bk, respectively.
The formation of the latent images is started. The latent image of each color is equidistantly formed on the outer periphery of the photosensitive drum
1
having the diameter of 180 mm for two prints of the A-4 size. Because the length of the outer periphery of the photosensitive drum
1
is about 565.2 mm and the width of the A-4 size is 210 mm, the interval of the latent images is 72.6 mm from the calculation
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