Electrophotography – Image formation – Transfer
Reexamination Certificate
2000-12-13
2002-04-30
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Transfer
C399S049000
Reexamination Certificate
active
06381435
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a color image forming apparatus. This color image forming apparatus may be a copying machine, a printer, and a facsimile. The color image forming apparatus may utilize the technology of electro-photography, electro-statics, or may utilize some other technology for forming the image on a paper.
BACKGROUND OF THE INVENTION
Conventionally, a tandem type of color image forming apparatus is known. In this conventional color image forming apparatus, a separate image forming unit for forming an image of a separate color, for example, yellow (hereafter Y), magenta (hereafter M), cyan (hereafter C), and black (hereafter K), respectively, are lined up along a conveyer belt. The conveyer belt conveys the paper, on which the image is to be formed, under each image forming unit. The conventional color image forming apparatus is shown in detail in FIG.
2
.
As shown in
FIG. 2
, in the conventional color image forming apparatus, a plurality of image forming units
1
Y,
1
M,
1
C, and
1
K are sequentially disposed along a conveyer belt
3
. The conveyer belt
3
is installed over conveyer rollers
4
and
5
so as to move in a direction shown by an arrow in FIG.
2
. One roller of the conveyer rollers
4
and
5
also drives the conveyer belt
3
in addition to just moving the conveyer belt
3
, and the other roller just moves the conveyer belt
3
. A paper feeder comprises a paper feed tray
6
. A pile of papers is placed in the paper feed tray
6
. A paper
2
on the top of this pile of paper is fed to the conveyer belt
3
by not shown a paper feed roller. The paper
2
sticks to the conveyer belt
3
due to electrostatic adsorption.
The conveyer belt
3
conveys the paper
2
under the Y image forming unit
1
Y. At this position, a transfer unit
7
Y of the Y image forming unit
1
Y forms a Y image (i.e. a yellow color image) on the paper
2
. The Y image forming unit
1
Y has a drum like photosensitive body
8
Y that supports an image, a charging unit
9
Y disposed in the periphery of the photosensitive body
8
Y for uniformly charging the photosensitive body
8
Y, an exposure unit
10
Y as an exposure means performing exposure for the photosensitive body
8
Y, a development unit
11
Y as a development means developing an electrostatic latent image on the photosensitive body
8
Y to form a Y toner image, and a photosensitive body cleaner
12
Y as a cleaning means cleaning the photosensitive body
8
Y.
The photosensitive body
8
Y is rotated and driven by a not shown rotation mechanism so as to be charged uniformly by the charging unit
9
Y. Then, the photosensitive body
8
Y is exposed to a laser light
13
Y from the exposure unit
10
Y so as to form an electrostatic latent image. This electrostatic latent image on the photosensitive body
8
Y is developed by the development unit
11
Y so that the Y toner image is formed on the photosensitive body
8
Y. This Y toner image on the photosensitive body
8
Y is transferred onto the transfer paper
2
on the conveyer belt
3
at a position (a transfer position) where the photosensitive body
8
Y and the transfer paper
2
on the conveyer belt
3
come in contact with each other by means of the transfer unit
7
Y so that the Y toner image of only the yellow color is formed on the paper
2
. After the transfer of the Y toner image is completed, the photosensitive body
8
Y is prepared for the next image formation while unnecessary toner remaining on the surface is cleaned by the photosensitive body cleaner
12
Y.
The paper
2
having the Y image formed thereon is then brought under the M image forming unit
1
M by moving the conveyer belt
3
. At this position, a transfer unit
7
M of the M image forming unit
1
M forms an M image (i.e. a magenta color image) over the already formed Y image. Then, the paper
2
having the Y image and M image formed thereon is brought under the C image forming unit
1
C by moving the conveyer belt
3
. At this position, a transfer unit
7
C of the C image forming unit
1
C forms an C image (i.e. a cyan color image) over the already formed Y image and M image. Then, the paper
2
having the Y image, M image, and C image formed thereon is brought under the K image forming unit
1
K by moving the conveyer belt
3
. At this position, a transfer unit
7
K of the K image forming unit
1
K forms an K image (i.e. a black color image) over the already formed Y image, M image, and C image. Thus, a full color image is formed on the paper
2
. Then, the paper
2
having an image printed thereon is conveyed under a fixing unit
14
. The fixing unit
14
fixes the image. Finally, the paper
2
is discharged outside the machine.
The M image forming unit
1
M, the C image forming unit
1
C, and the K image forming unit
1
K have drum like photosensitive bodies
8
M,
8
C, and
8
K as image support bodies, charging units
9
M,
9
C, and
9
K disposed in the peripheries of the photosensitive bodies
8
M,
8
C, and
8
K as charging means for uniformly charging the photosensitive bodies
8
M,
8
C, and
8
K, exposure units
10
M,
10
C, and
10
K as exposure means performing exposure for the photosensitive bodies
8
M,
8
C, and
8
K, development units
11
M,
11
C, and
11
K as development means developing electrostatic latent images on the photosensitive bodies
8
M,
8
C, and
8
K to make an M toner image, a C toner image, and a K toner image, and photosensitive body cleaners
121
M,
12
C, and
12
K as cleaning means cleaning the photosensitive bodies
8
M,
8
C, and
8
K, respectively, similarly to the Y image forming unit
1
Y.
In the M image forming unit
1
M, the C image forming unit
1
C, and the K image forming unit
1
K, after the photosensitive bodies
8
M,
8
C, and
8
K are rotated and driven by means of rotation mechanisms which are not shown so as to be uniformly charged with electricity by the charging units
9
M,
9
C, and
9
K, respectively, they are exposed to laser lights
13
M,
13
C, and
13
K corresponding to an M image signal, a C image signal, and a K image signal by the exposure units
10
M,
10
C, and
10
K to form electrostatic latent images, respectively. These electrostatic latent images on the photosensitive bodies
8
M,
8
C, and
8
K are developed by the development units
11
M,
11
C, and
11
K so that the M toner image, the C toner image, and the K toner image are formed on the photosensitive bodies
8
M,
8
C, and
8
K. The M toner image, the C toner image, and the K toner image on the photosensitive bodies
8
M,
8
C, and
8
K are transferred onto the transfer paper
2
on the conveyer belt
3
at the positions (transfer positions) where the photosensitive bodies
8
M,
8
C, and
8
K and the transfer paper
2
on the conveyer belt
3
come in contact with each other by means of the transfer units
7
M,
7
C, and
7
K. After the transfer of the M toner image, the C toner image, and the K toner image are completed, the photosensitive bodies
8
M,
8
C, and
8
K are prepared for the next image formations while unnecessary toner remaining on the surfaces is cleaned by the photosensitive body cleaners
12
M,
12
C, and
12
K.
In the conventional color image forming apparatus it is necessary that the different color images are formed at exact positions. For example, if the positions of the image forming units is not aligned, then the image will get distorted. Therefore, a technique for an alignment between respective colors is a significant issue from the constitutional standpoint. The factors that cause static positional deviation of respective colors mainly include skew, positional deviation of the resist in the sub-scanning direction and main scanning direction, and error in magnification in the main scanning direction.
A skew correction is performed by, for example, regulating the inclination of an optical unit or the inclination of a beam reflection mirror existing therein or the like.
In the color image forming method described in Japanese Patent Application Laid-Open No. HEI 10-198110, detection unit for detecting a positional deviatio
Hanada Motonori
Iwata Nobuo
Nakagawa Hideo
Nakazato Yasushi
Sato Toshiya
Chen Sophia S.
Ricoh & Company, Ltd.
LandOfFree
Color image forming apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Color image forming apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Color image forming apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2842138