Electrophotography – Document handling – Copy
Reexamination Certificate
2003-01-27
2004-06-15
Ngo, Hoang (Department: 2852)
Electrophotography
Document handling
Copy
Reexamination Certificate
active
06751437
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus such as a printer or an electrophotographic copier, in which paper is conveyed in a circulatory conveyance path for formation of images on both sides of the paper.
2. Description of the Related Art
Image forming apparatuses are known which comprise circulatory conveyance means (hereinafter referred to as an ADU) for reversibly conveying paper on which an image has been formed on one side of the paper and circulatorily conveying the paper in order to allow images to be formed on both sides of the paper such as standard paper.
Among these image forming apparatuses, there is known a type of image forming apparatus employing a so-called non-stacked circulatory conveyance method in which a plurality of sheets of paper (e.g., five sheets of paper) are continuously supplied from a paper supply tray, a toner image formed on a photosensitive drum is continuously transferred onto a first or front side of the paper and the toner image is fixed onto the paper. Thereafter, the paper is reversed by the ADU, and circulatorily conveyed towards the transfer region where another toner image formed on the photosensitive drum is transferred onto a second or back side of the paper, fixed to the paper, and then the paper is discharged to a discharge tray, so that plural sheets of paper are not stacked at a time in an intermediate tray.
FIG. 1
shows, in an illustrative view, an example of the structure of such image forming apparatus.
A copier as an example of such image forming apparatus comprises an automatic document feeder
1
on an upper part of the body of the copier, and includes within the copier body an image reader
2
, an image formation section
3
, a paper housing section
4
, a paper supply section
5
, a reverse/discharge/paper resupply section
6
, and an ADU
8
that serves as the circulatory conveyance means.
The automatic document feeder
1
is a device for sending out documents one by one at a time, conveying the documents to an image reading position, and discharging documents whose image has been read to a predetermined place. The automatic document feeder
1
includes a document mount
11
on which documents are mounted; document separation means
12
for separating the documents mounted on the document mount
11
; document conveying means
13
including plural rollers for conveying the documents separated by the document separating means
12
; document discharge means
14
for discharging the documents conveyed by the document conveying means
13
; a document discharge tray
15
for receiving the documents discharged by the document discharge means
14
; and document reversal means
16
comprising a pair of rollers for reversing the documents to read images on both sides of the documents. Plural sheets of the documents (not illustrated) mounted on the document mount
11
are separated one by one at a time by the document separation means
12
, and conveyed toward the image reading position by the document conveying means
13
.
The image reader
2
is disposed below the document conveyance means
13
, and images on the documents are read through a slit
21
forming the image reader
2
. Documents whose images have been read are discharged onto the document discharge tray
15
by the document discharge means
14
.
When images on both sides of a document are to be read, documents for which an image on one side has been read are guided to the document reversal means
16
, the documents are reversed by counter-rotational control of the rollers in a state in which trailing ends of the documents are held between the rollers, and then the documents are conveyed once more by the document conveyance means
13
, whereby it is possible to read the images on the other sides of the documents at the image reading position. This process is repeated for the number of documents mounted on the document mount
11
.
The automatic document feeder
1
is structured to be retractable. By retracting the automatic document feeder
1
, a document can be mounted directly on a platen glass
22
and copied.
The image reader
2
is a means for obtaining image data by reading the images on the documents. The image reader
2
includes the slit
21
; a first mirror unit
23
comprising a lamp
231
as a light source that irradiates the documents, and a first mirror
232
that reflects light reflected from the documents; a second mirror unit
24
comprising a second mirror
241
for reflecting light from the first mirror
232
and a third mirror
242
; an image formation lens
25
that images onto an image pickup device
26
such as CCD light reflected from the second mirror unit
24
; and a line CCD
26
adapted to obtain image information by photoelectrically converting the light image imaged by the image formation lens
25
. After the image information thus obtained is subjected to appropriate image processing, it is temporarily stored in a memory not shown.
When the documents fed by the automatic document feeder
1
are read by the image reader
2
, the first mirror unit
23
and the second mirror unit
24
are positioned as illustrated.
Images on documents that are directly mounted onto the platen glass
22
are read by the first mirror unit
23
and the second mirror unit
24
which are moved along the platen glass
22
while maintaining an optical path length therebetween.
The image formation section
3
forms images by an electrophotographic process on the basis of the image data obtained by the image reader
2
. The image formation section
3
includes the photosensitive drum
31
having on a surface thereof a photoelectrically conductive photosensitive layer; an electrifier
32
for uniformly electrifying the surface of the photosensitive drum
31
; a laser writing system
33
as an exposure means for exposing the photosensitive drum
31
to form a latent image thereon that is activated on the basis of the image-processed image data; a developer
34
for developing the latent image formed on the photosensitive drum
31
to form a toner image; a transfer electrode
35
for transferring the toner image onto the paper; a charge remover
36
for accelerating separation of the paper with the toner image transferred thereon from the photosensitive drum
31
by effecting an AC corona discharge to remove the charge; cleaning means
37
for cleaning the photosensitive drum
31
after the transferring process has been concluded; a fixing device
38
of heating roller type for fixing the toner image on the paper; and the reverse/discharge/paper resupply section
6
and the ADU
8
.
The photosensitive drum
31
, which is rotated in a direction shown by an arrow by appropriate drive means, is sequentially electrified by the electrifier
32
, the electrostatic latent image is formed by dot exposure by the laser writing system
33
, and the toner image is formed by the developer
34
. Then, the toner image is transferred via the action of the transfer electrode
35
onto the paper that is synchronously conveyed by initiating rotation of registration rollers
56
, which are second paper supply means, so that the paper is superposed on the toner image region, whereby an image is formed on the paper.
The paper with the toner image transferred thereon is separated from the photosensitive drum
31
by the charge remover
36
, and the toner image is fixed on the paper by the heat and pressure applied by the fixing device
38
.
The photosensitive drum
31
continues to rotate while the remaining toner on the photosensitive drum
31
which has passed through the transfer region is removed by the cleaning means
37
for preparation of the next image formation.
A conveyor belt
39
for conveying the paper separated from the photosensitive drum
31
by the charge remover
36
is disposed between the charge remover
36
and the fixing device
38
.
Paper feed trays
400
,
410
and
420
including housing sections
405
,
415
and
425
comprising housing containers for housing stacked sheets of the paper and the
Frishauf Holtz Goodman & Chick P.C.
Konica Corporatioin
Ngo Hoang
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