Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1999-01-28
2002-08-20
Nguyen, Lamson D. (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S131000
Reexamination Certificate
active
06437817
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and an image forming method using a transparent laminated film on which a color toner image is formed by an electrophotographic printing method or an electrostatic printing method. More particularly, the present invention relates to an image forming apparatus and an image forming method for forming a color image on a transparent laminated film which is to be placed on an overhead projector (OHP).
FIG. 5
is a cross-section of an electrophotographic printing apparatus, capable of forming a full-color image. In
FIG. 5
, the electrophotographic printing apparatus comprises a transfer material conveyance system located from one side to the substantial center of the apparatus main body
100
, a latent image forming unit provided adjacent to a transfer drum
8
which is a part of the transfer material conveyance system, and a rotation-type developing unit serving as developing means, located adjacent to the latent image forming unit. The aforementioned transfer material conveyance system comprises: transfer material feeding trays
101
and
102
which are detachably inserted to openings provided on one side (right side in
FIG. 5
) of the apparatus main body
100
; transfer material feeding rollers
103
and
104
provided substantially directly above the trays
101
and
102
; feeding guides
4
A and
104
b
comprising feeding rollers
106
, which are located adjacent to the feeding rollers
103
and
104
; a transfer drum
8
rotatable in the direction of an arrow in
FIG. 5
; a conveyance belt
15
provided adjacent to a separation claw
14
; and a fixer
16
which is provided near the end of the conveyance belt
15
in the conveyance direction, and is provided adjacent to a discharge tray
17
which extends from the apparatus main body
100
and is detachable from the apparatus main body
100
. The transfer drum
8
is located adjacent to the feeding guide
104
b
. Near the periphery of the transfer drum
8
, an abutting roller
7
, a gripper
6
, a transfer-material separation charger
12
, and a separation claw
14
are provided in the upstream-to-downstream direction of the rotation of the transfer drum
8
. In the interior periphery of the transfer drum
8
, a transfer charger
9
and a transfer-material separation charger
13
are provided.
The latent image forming unit comprises: the photosensitive drum
2
serving as an image transfer body, whose outer periphery abuts against the outer periphery of the aforementioned transfer drum
8
, and is rotatable in the direction of an arrow in
FIG. 5
; image exposure means, such as a laser-beam scanner, for forming an electrostatic latent image on the periphery of the photosensitive drum
2
; and image exposure reflection means such as a polygon mirror. Near the periphery of the photosensitive drum
2
, an electrostatic charger for discharge (hereinafter referred to as discharger)
10
, cleaning means
11
, and a primary electrostatic charger
3
are provided in the upstream-to-downstream direction of the rotation of the photosensitive drum
2
.
The rotation-type developing unit comprises: a rotational body
4
a;
and an yellow developer
4
Y, a magenta developer
4
M, a cyan developer
4
C and a black developer
4
BK which are incorporated in the rotational body
4
a
and enable to visualize the electrostatic latent image formed on the periphery of the photosensitive drum
2
at a position facing the periphery of the photosensitive drum
2
.
An image forming sequence of the image forming apparatus having the above-described construction is briefly described, taking a full-color mode as an example. When the photosensitive drum
2
is rotated in the direction of the arrow in
FIG. 5
, a photosensitive material on the photosensitive drum
2
is uniformly charged by the primary electrostatic charger
3
, then image exposure is performed by a laser beam E which is modulated by yellow image signals of an original image (not shown). By this, an electrostatic latent image is formed on the photosensitive drum
2
, and the electrostatic latent image is developed by the yellow developer
4
Y which is positioned at a predetermined developing positions by rotation of the rotational body
4
a.
Meanwhile, a transfer material conveyed through the feeding guide
4
A, feeding rollers
106
, and feeding guide
104
b
, is gripped by the gripper
6
in a predetermined timing, and is electrostatically wrapped around the transfer drum
8
by the abutting roller
7
and electrodes facing the abutting roller
7
. While the transfer drum
8
rotates in the direction of an arrow in
FIG. 5
in synchronization with the photosensitive drum
2
, the image developed by the yellow developer
4
Y is transferred by the transfer charger
9
at the position where the periphery of the photosensitive drum
2
abuts against the periphery of the transfer drum
8
. The transfer drum
8
continues its rotation, preparing to transfer the next color (magenta in FIG.
5
).
The photosensitive drum
2
is discharged by the discharger
10
and cleaned by the cleaning means
11
. Then, the photosensitive drum
2
is charged again by the primary electrostatic charger
3
and the above-described image exposure is performed according to the subsequent magenta image signals. The above-described image exposure is performed on the photosensitive drum
2
according to magenta image signals. The rotation-type developing unit rotates while an electrostatic latent image is formed on the photosensitive drum
2
according to the magenta image signals by the above image exposure. The magenta developer
4
M is positioned at a predetermined developing position and a predetermined magenta development is performed. Next, the above-described process is performed with respect to cyan and black and completes the transfer process for four colors. The four-color toner image formed on the transfer material is discharged by the discharger
10
and charger
13
. The gripper
6
releases the transfer material, the transfer material is then separated from the transfer drum
8
by the separation claw
14
and is transferred to the fixer
16
by the conveyance belt
15
to be fixed by heat and pressure. As a result, a series of full-color print sequences is completed and the necessary full-color print image is formed. The fixer
16
includes a surface-lubricant coating mechanism which promotes separation of an OHP film from a fixation member. However, it is a recent trend to use less amount of the surface lubricant.
Next, toner used in the electrophotographic apparatus is described.
Toner for a color electrophotographic printing apparatus requires excellent melting and color mixture characteristics when heat is applied. Thus, toner having a sharp-melt characteristic is preferable where the softening point is low and melting time is short.
The use of a sharp-melt toner improves the color reproducible range of an original image, and enables to achieve a colored copy consistent with a multiple-color original image.
The foregoing sharp-melt toner is manufactured by melting and mixing, e.g., polyester resin, styrene-acrylic resin, colorant (dye, sublimation-type dye), charge control agent and the like, then grinding and classifying them. If necessary, a process of adding various external agents to the toner may be added.
For color toner, it is particularly preferable to employ toner utilizing polyester as a binding resin, taking into account fixation and sharp-melt characteristics. The sharp-melt polyester resin is a high molecular compound including ester bonding in the principal chain of a molecule in which diol compound and dicarboxylic acid are synthesized.
Particularly, because of its sharp melting characteristic, it is preferable to use polyester resin, represented by the following formula (1) (R is ethylene or propylene radical; x and y are respectively a positive integer which is 1 or more; and the average value of x+y is 2 to 10), where a bisphenol derivative or its substituent as a diol component, and a car
Ishizuka Jiro
Ohta Mitsuhiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Nguyen Lamson D.
LandOfFree
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