Electrophotography – Diagnostics – Document handling
Reexamination Certificate
2001-02-23
2003-03-18
Grainger, Quana M. (Department: 2852)
Electrophotography
Diagnostics
Document handling
C399S021000
Reexamination Certificate
active
06535698
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording medium conveyance method and apparatus applied to image forming apparatuses such as copying machines, printers, facsimiles and inkjet printers, and a storage medium that contains a control program for use in controlling the recording medium conveyance apparatus.
2. Description of Related Art
FIG. 8
is a schematic diagram showing the internal structure of a conventional image forming apparatus (e.g., a copying machine, a printer, a facsimile and an inkjet printer). In
FIG. 8
, reference numeral
801
denotes a photosensitive drum, which forms a toner image from a latent image. Reference numeral
802
denotes a laser scanner, which depicts a latent image on the photosensitive drum
801
, and
803
a tone developer, which puts toner on the latent image on the photosensitive drum
801
. Reference numeral
804
denotes a feeding roller
804
, which feeds a recording medium (e.g., recording paper) P, described later. Reference numeral
805
denotes a transfer part, which transfers an image onto the recording medium P and separates the recording medium P from the photosensitive drum
801
(recording medium separating part), and
806
a toner fixing part, which fixes the toner on the recording medium P. Reference numeral
807
denotes a post-separation sensor, which senses a separation jam,
808
a reader part, which reads an image, and
809
a pair of resist rollers, which stops and feeds the recording medium P according to a control sequence before the recording medium P is fed to the transfer part
805
. Reference numeral
810
denotes a transfer electrifier, which transfers a toner image on the photosensitive drum
801
,
811
a separation electrifier, which separates the recording medium P from the photosensitive drum
801
, and
812
a cleaning means, which removes the toner residing on the photosensitive drum
801
. Symbol P designates recording paper as the recording medium.
FIG. 9
is a schematic diagram showing the internal structure of parts around a photosensitive drum of a conventional image forming apparatus. In
FIG. 9
, reference numeral
901
denotes a photosensitive drum as an image carrier, which forms a toner image from a latent image, and
902
a part, which transfers an image on a recording medium (e.g., recording paper)
906
, described later, and then separates the recording medium
906
from the photosensitive drum
901
. Reference numeral
903
denotes a cleaning means that removes toner residing on the photosensitive drum
901
, and
904
a separation electrifier, which separates the recording medium
906
from the photosensitive drum
901
. Reference numeral
905
denotes a post-separation sensor, which senses a separation jam, and
906
the recording medium.
FIG. 9
shows a state wherein the recording medium
906
, which is poorly separated from the photosensitive drum
901
, is passing the lower side of the photosensitive drum
901
.
FIG. 10
is a schematic diagram showing an input from the outside of a conventional image forming apparatus. In
FIG. 10
, reference numeral
1001
denotes a conveyance belt, which conveys a recording medium by electrostatic absorption, and
1001
a
and
1001
b
belt driving rollers for driving the conveyance belt
1001
. Reference numeral
1002
denotes an absorption electrifier for absorbing the recording medium onto the conveyance belt
1001
,
1003
a separation electrifier, which separates the recording medium from the conveyance belt
1001
, and
1004
a post-separation sensor for detecting a separation jam. Reference numeral
1005
denotes a pair of resist rollers, which stops and feeds the recording medium before the recording medium is fed to a transfer part, and
1006
a photosensitive drum as an image carrier, which forms a toner image describing a latent image.
FIG. 11
is a diagram showing a conventional method of detecting a separation delay jam. In
FIG. 11
, reference numeral
1101
denotes a resist clutch signal that is an actuating signal from a resist clutch, which operates the pair of resist rollers (denoted by
809
in
FIG. 8 and 1005
in FIG.
10
). Reference numeral
1102
denotes a sensor signal from the post-separation sensor (denoted by
807
in
FIG. 8
,
905
in
FIG. 10 and 1004
in FIG.
10
). Reference numeral
1103
denotes a point in time where the resist clutch is operated. Reference numeral
1104
denotes a jam detection timing. Reference numeral
1105
indicates that a sensor signal
1102
is High, and
1106
indicates that a sensor signal
1102
is Low.
There will now be given some examples of separation devices provided in an image forming apparatus such as a copying machine, a printer, a facsimile and an inkjet printer, which separate a recording medium such as paper, an OHP, a board and a cloth. If the image forming apparatus is a copying machine and the recording medium is paper, a first example of the separation devices is a device that transfers images depicted on the photosensitive drum
801
as the image carrier onto sheets of paper, which are conveyed on a sheet-by-sheet basis from the feeding part
804
in
FIG. 8
, and then electrostatically separates the paper from the photosensitive drum
801
.
A second example of the separation devices is a device that is provided in a copying machine having the conveyance belt
1001
in FIG.
10
and applies an electric current to the absorption electrifier
1002
, absorbs the paper onto the conveyance belt
1001
, transfers an image depicted the photosensitive drum
1006
as the image carrier onto the paper by the transfer electrifier
1007
, separates the paper from the photosensitive drum
1006
and then separates the paper from the conveyance belt
1001
by the separation electrifier
1003
.
If the image forming apparatus is an inkjet printer, an example of the separation devices is a device that separates the recording medium from a head member, which forms an image by jetting ink.
Referring next to
FIG. 8
, a brief description will be given of the entire operation of the image forming apparatus having the separation device as the above-mentioned first example.
In
FIG. 8
, a laser beam emitted from the laser scanner
802
is irradiated onto the photosensitive drum
801
, which is rotating clockwise as viewed in the figure. This forms an electrostatic latent image on the photosensitive drum
801
, and the tone developer
803
visualizes the electrostatic latent image. The laser scanner
802
emits a laser beam according to an original image read by the reader part
808
. On the other hand, sheets of the recording medium P, which are stacked in a recording medium cassette, not shown, are fed from the cassette. The feeding roller
804
, which is rotating counterclockwise as viewed in the figure, sequentially feeds the sheets of the recording medium P stacked in the recording medium cassette from the top one on a sheet-by-sheet basis. The recording medium P fed from the recording medium cassette is sent to the pair of resist rollers
809
, which are not rotating. Each sheet of the recording medium P stops moving when it abuts against a nip of the pair of resist rollers
809
and forms a predetermined amount of loop. This corrects oblique movement of the recording medium P, so that an image can be recorded on the recording medium which is in a correct position. The recording medium P, after having been corrected from the oblique position, is conveyed to the transfer part
805
between the photosensitive drum
801
and the transfer electrifier
810
by the pair of resist rollers
809
which start rotation in predetermined timing. While the recording medium P is passing the transfer part
805
, the transfer electrifier
810
transfers a toner image onto the photosensitive drum
801
. During the transfer of the toner image, the recording medium P is electrostatically absorbed onto the photosensitive drum
801
, but is separated from the photosensitive drum
801
by the separation electrifier
811
. The recording medium P, which has been pro
Canon Kabushiki Kaisha
Grainger Quana M.
Rossi & Associates
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