Electrophotography – Image formation – Transfer
Reexamination Certificate
2002-03-15
2004-01-13
Pendegrass, Joan (Department: 2852)
Electrophotography
Image formation
Transfer
C347S003000, C399S002000, C399S223000, C399S341000
Reexamination Certificate
active
06678493
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copying machine, a printer and a facsimile machine. More particularly, the invention relates to an image forming apparatus of the type which uses a belt transfer member when an image is transferred onto a recording medium, and improvement of a belt module for use with the image forming apparatus.
2. Description of the Related Art
An intermediate transfer type image forming apparatus maybe exemplified for this type of the image forming apparatus. In the image forming apparatus, a toner image is formed by an image forming unit based on the electrophotography, is primarily transferred onto the intermediate transfer member, and the toner image is secondarily transferred from the intermediate transfer member onto a recording medium.
In this type of the image forming apparatus, to form a color image, color component toner images are primarily transferred onto the intermediate transfer member in successive manner to superimpose those component color toner images. In the primary image transferring process, the images are transferred onto the intermediate transfer member in good conditions. As a result, a good color image suffering from less color misregistration is obtained.
An endless intermediate transfer belt or a cylindrical intermediate transfer drum is generally used for the intermediate transfer member. In most cases, the intermediate transfer belt is used since the respective devices within the image forming apparatus may be laid out at high freedom.
The following proposals are present for the purpose of improving a color image quality. A first proposal is that developing devices containing six color component toners are mounted on a rotary developing unit, thereby improving the color reproducibility of a reproduced image (e.g., JP-A-Hei.10-301402). A second proposal is that with an intention of reproducing a glossy image, a plurality of image forming units using basic four colors, cyan, yellow, magenta, and black, are disposed around the intermediate transfer belt, and an image forming unit using a transparent, clear toner is additionally provided therearound (e.g., JP-A-2000-347476).
In the conventional intermediate transfer type image forming apparatus, the rotary developing unit is size increased by an amount corresponding to the increased number of developing devices. Further, the number of image forming units disposed around the intermediate transfer belt is increased, so that the image forming apparatus is size increased as a whole.
Those technical problems arises not only in the image forming apparatus having the intermediate transfer belt but also in the image forming apparatus having an image bearing belt for supporting images thereon and transporting them.
Accordingly, an object of the present invention is to provide an image forming apparatus which makes more improvement of the color reproducibility of a reproduced image while effectively suppressing the size increase of the whole image forming apparatus, and a belt module for use with the image forming apparatus.
SUMMARY OF THE INVENTION
In the image forming apparatus having a belt transfer member such as an intermediate transfer belt, the belt transfer member is generally constructed such that an endless belt is wound on tension rolls. Accordingly, an area occupied by the belt transfer member is determined by the positions of the tension rolls. Therefore, it is possible to secure a space in which the image forming unit is installed by narrowing the space occupied by the belt transfer member. The inventors of the present invention directed their attention to this point, and reached the technical idea of the present invention.
In the following description, reference numerals are added to constituent elements to facilitate understanding the invention. However, the reference numerals do not limit the invention to the following description.
As shown in
FIG. 1
, according to the invention, there is provided an image forming apparatus having at least one image forming unit
1
(for example
1
a
to
1
d
), a belt transferring member
2
, a plurality of tension rolls
3
(for example
3
a
to
3
c
), and a bending member
5
, in which the image forming unit
1
forms a visual image on the belt transferring member
2
to transfer the visual image onto a recording medium
8
through the belt transferring member
2
, the belt transferring member
2
has an endless belt
4
wound on the tension rolls
3
, the bending member
5
is disposed in outside of the endless belt
4
between at least a pair of tension rolls
3
(for example
3
b
and
3
c
) to bend the endless belt
4
toward inside of a tangential line m connected between an outer peripheral ends of at least the pair of adjacent tension rolls
3
, the tangential line m and the endless belt
4
define an outer bending concave region
6
, and it is possible to dispose an additional image forming unit
7
in the outer bending concave region
6
.
In the technique thus constructed, the image forming units
1
may be not only of the electrophotography type and electrostatic recording type, but also of the ink jet type, the magnetrophy type, the elcography type, the offset printing, the gravure printing, and the thermal-transfer printing.
The wording “at least one image forming units
1
” is used to imply that the image forming apparatus involves a plural-cycle machine with one image forming unit
1
as well as a tandem machine with a plurality of image forming units
1
.
If the image forming unit
1
is based on the electrophotography process, the belt transfer member
2
means mainly the intermediate transfer member. If the image forming unit is of the ink jet type, the belt transfer member
2
involves a visual image transport/transfer member which carries the image thereon and transports the image, and transfers the image on a recording medium.
The bending member
5
may appropriately be selected so long as the bending member
5
bends the endless belt
4
toward the inside of a tangential line “m” connecting points on the outer circumferences of a couple of tension rolls
3
(e.g.,
3
b,
3
c
), and locates the bent endless belt
4
inside the tangential line, is additionally provided outside the endless belt
4
located between at least the couple of adjacent tension rolls
3
(e.g.,
3
b,
3
c
). In this case, care must be taken so as not to impair the transportation of the belt transfer member
2
, and a disturbance of the visual image.
The endless belt
4
is bent by the bending member
5
and the tension rolls
3
(e.g.,
3
b,
3
c
) adjacent to the bending member. The outside bending concave region
6
is secured between the bent part of the endless belt
4
and the tangential line “m”.
The outside bending concave region
6
is not specifically limited so far as to allow the image forming unit
7
to additionally be installed therein. In this case, it is not essential whether or not the image forming unit
7
is additionally installed.
To improve the color reproducibility of the reproduced image, the image forming unit
7
is additionally provided within the outside bending concave region
6
.
By so doing, even if the image forming unit
7
is additionally provided within the outside bending concave region
6
of the endless belt
4
, there is no increase of the apparatus size.
Here, it is essential that the image forming unit
7
is merely installed at the outside bending concave region
6
, and it is not essential that it is located completely within the outside bending concave region
6
.
In the image forming apparatus of the invention, it is not always needed that the image forming unit
7
is additionally installed. If such a space as to allow the additional installation of the image forming unit is provided, the image forming unit may be additionally installed as an option as desired.
Wit regard to the layout of the bending member
5
, the bending member
5
is in contact with the surface of the belt transfer member
2
. Therefore,
Maeyama Ryuichiro
Okamoto Yoshikazu
Fuji 'Xerox Co., Ltd.
Oliff & Berridg,e PLC
Pendegrass Joan
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