Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2003-01-06
2004-08-31
Chapman, Mark A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S111400, C399S159000
Reexamination Certificate
active
06783906
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a color image forming apparatus such as a color printer, etc., and more detailedly, relates to a tandem type color image forming apparatus wherein a multiple number of photoreceptors are charged so as to develop color images by developing devices holding different color toners.
(2) Description of the Prior Art
Recently, in the field of color electrophotographic processing, tandem type color image forming apparatuses in which a multiple number of photoreceptor drums are arranged in line to obtain a color image of multiple colors of toner have been used in order to enhance the printing speed. This tandem type color image processing lends itself to color image forming apparatuses and multi-color image forming apparatuses for outputting image formed articles of reproduction and composition of color images and multi-color images by successively transferring a plurality of color separation images for color image data or multi-color image data, in a layered manner, as well as machines having these functions.
FIG. 1
is a front sectional view showing the overall configuration of a digital color copier
1
as a typical example of the tandem type. Copier body
1
has an original table
111
and an aftermentioned control panel on the top thereof and has an image reading portion
110
and an image forming unit
210
within. A reversing automatic document feeder (RADF)
112
is arranged on the top surface of original table
111
in a predetermined position with resect to the original table
111
surface whilst being supported so as to be opened and closed relative to original table
111
.
RADF
112
, first, conveys an original so that one side of the original opposes image reading portion
110
at the predetermined position on original table
111
. After the image scanning of this side is completed, the original is inverted and conveyed to original table
111
so that the other side opposes image reading portion
110
at the predetermined position on original table
111
. Then, when RADF
112
completes image scanning of both sides of one original, the original is discharged and the duplex copy conveying operation for a next document is implemented. The operation of the conveyance and face inversion of the original is controlled in association with the whole copier operation.
Image reading portion
110
is disposed below original table
111
in order to read the image of the original conveyed onto original table
111
by means of RADF
112
. Image reading portion
110
includes original scanning portion
113
and
114
which reciprocates along, and in parallel to, the undersurface of original table
111
, an optical lens
115
and a CCD line sensor
116
as a photoelectric converting device.
This original scanning portion
113
and
114
is composed of first and second scanner units
113
and
114
. First scanner unit
113
has an exposure lamp for illuminating the original image surface and a first mirror for deflecting the reflection image of light from the original toward the predetermined direction and moves at the predetermined speed in a reciprocating manner in parallel with, whilst being kept a certain distance away from, the undersurface of original table
111
. Second scanner unit
114
has second and third mirrors which deflect the reflected light image from the original, deflected by first mirror of first scanner unit
113
toward the predetermined direction and moves in a reciprocating manner at a speed related to that of first scanner unit
113
and in parallel thereto.
Optical lens
115
reduces the reflected light image from the original, thus deflected by third mirror of the second scanner unit, so that the reduced light image will be focused on the predetermined position on CCD line sensor
116
.
CCD line sensor
116
implements sequential photoelectric conversion of the focused light image into electric signals and outputs them. CCD line sensor
116
is a three-line color CCD which reads monochrome or color images and outputs line data as to color separation components R (red), G (green) and B (blue). The original image information thus obtained in the electric signal form from this CCD line sensor
116
is further transferred to the image processor where predetermined image data processes are performed.
Next, the configuration of image forming unit
210
and the configuration of the components related to image forming unit
210
will be described.
Provided below image forming unit
210
is a paper feeding mechanism
211
which separates a sheet of paper (recording medium) P, one by one, from a stack of paper held in a paper tray and feeds it toward image forming unit
210
. The paper P thus separated is delivered into image forming unit
210
with its timing controlled by a pair of registration rollers
212
located before image forming unit
210
. The paper P with an image formed on its one side is conveyed and re-fed to image forming unit
210
in time with image forming of image forming unit
210
.
Arranged under image forming unit
210
is a conveyer and transfer belt mechanism
213
. A conveyer and transfer belt
216
of conveyer and transfer belt mechanism
213
is wound and tensioned between a driving roller
214
and an idle roller
215
so that the upper and lower parts of the belt extend approximately parallel to each other. The conveyer and transfer belt
216
electrostatically attracts paper P to itself to convey it. Further, a pattern image density measuring unit is provided under and in proximity to conveyer and transfer belt
216
.
Arranged in the paper conveyance path, downstream of conveyer and transfer belt mechanism
213
is a fixing unit
217
. This fixing unit
217
fixes the transferred toner image onto paper P.
The paper P having passed through the nip between a pair of fixing rollers of fixing unit
217
passes through a conveyance direction switching gate
218
and is discharged by discharge rollers
219
to a paper output tray
220
attached to the outer wall of copier body
1
.
This switching gate
218
selectively connects the conveyance path of paper P after fixing with either the path to discharge paper P to the outside of copier body
1
or the path to recirculate paper P toward image forming unit
210
. The paper P which is designated to be conveyed again to image forming unit
210
by means of switching gate
218
is inverted by means of a switch-back conveyance path
221
and then re-fed to image forming unit
210
.
Arranged above, and in proximity to, conveyer and transfer belt
216
in image forming unit
210
are the first image forming station Pa, the second image forming station Pb, the third image forming station Pc and the fourth image forming station Pd, in the above mentioned order from the upstream side of the paper conveyance path.
Conveyer and transfer belt
216
is frictionally driven by driving roller
214
in the direction indicated by arrow Z in
FIG. 1
, and carries paper P which is fed by paper feeding mechanism
211
as stated above and sequentially conveys it through image forming stations Pa to Pd.
All the image forming stations Pa to Pd are of a substantially identical configuration. Each image forming station Pa, Pb, Pc and Pd has a photoreceptor drum
222
a
,
222
b
,
222
c
and
222
d
, which is driven in the rotational direction indicated by arrow F in FIG.
1
.
Provided around each photoreceptor drum
222
a
-
222
d
, are a primary charger
223
a
,
223
b
,
223
c
and
223
d
for uniformly charging photoreceptor drum
222
a
-
222
d
, a developing unit
224
a
,
224
b
,
224
c
and
224
d
for developing the static latent image formed on photoreceptor drum
222
a
-
222
d
, a transfer charger
225
a
,
225
b
,
225
c
and
225
d
for transferring the developed toner image on photoreceptor drum
222
a
-
222
d
to paper P, cleaning unit
226
a
,
226
b
,
226
c
and
226
d
for removing the leftover toner from photoreceptor drum
222
a
-
222
d
, in this order with respect to the rotational direction of each photoreceptor drum
Ishida Toshihisa
Kida Kouji
Matsumoto Masanori
Sawai Tadayuki
Takeda Yuko
Chapman Mark A.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
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