Electrophotography – Internal machine environment – Forced air circulation
Reexamination Certificate
2001-03-26
2003-02-18
Tran, Hoan (Department: 2852)
Electrophotography
Internal machine environment
Forced air circulation
C399S093000
Reexamination Certificate
active
06522847
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-091381, filed Mar. 29, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
This invention relates to an image forming apparatus for forming an image by means of electrophotographic method on a recording medium moving in a vertical direction.
The image forming apparatus of this kind is used, for example, in a facsimile machine or a copying machine, or is used as a printer.
FIG. 4
is a view schematically showing a vertical section of a conventional image forming apparatus which is constituted as a printer.
The conventional printer shown in
FIG. 4
is detachably provided with a tray
14
for a recording medium at a predetermined position of a lower end portion of an inner space of an outer housing
10
. The tray
14
for the recording medium holds a plurality of ordinary plain paper sheets each having a predetermined size as a recording medium in a mutually laminated state. In the inner space of the outer housing
10
, there are further arranged a pick-up mechanism
16
for picking up one after another a plurality of paper sheets
12
in the tray
14
at an upper end thereof, and a transfer unit
20
for transferring the paper sheet
12
, picked up from the plurality of paper sheets
12
in the tray
14
with the pick-up mechanism
16
, in an upward direction in the inner space along a predetermined transfer path
18
. In an upper wall of the outer housing
10
at a position corresponding to an upper end of the transfer path
18
, an outlet opening
10
a
of the recording medium
10
is formed through which the paper sheet
12
ejected from the upper end of the transfer path
18
passes. On an upper surface of the upper wall of the outer housing
10
, a tray
10
b
is formed on which the paper sheet
12
passed through the outlet opening
10
a
is stacked.
Further, in the inner space of the outer housing
10
, an electrophotographic type image forming unit
22
is arranged at a predetermined position along the transfer path
18
. The image forming unit
22
includes a photosensitive drum
22
a
which faces one of planar side surfaces of the paper sheet
12
being transferred in the transfer path
18
, and is rotated in accordance with a transfer direction and a transfer speed of the paper sheet
18
in the transfer path
18
.
The image forming unit
22
further includes a discharging device
22
b,
a charging device
22
c,
an exposing device
22
d
and a developing device
22
e
which are arranged along the external circumferential surface of the photosensitive drum
22
a
in this order in a rotation direction R of the photosensitive drum
22
a.
The image forming unit
22
further includes a transfer device
22
f
and a separating device
22
g
arranged at two positions so that they face the external circumferential surface of the photosensitive drum
22
a
with the transfer path
18
interposed therebetween. The transfer device
22
f
is arranged on an upstream side than the separating device
22
g
in the rotation direction R of the photosensitive drum
22
a.
The image forming unit
22
further includes a fixing device
22
h
on a downstream side than the photosensitive drum
22
a
in the transfer direction of the paper sheet
12
in the transfer path
18
.
The image forming unit
22
which is constituted as described above is provided with an operation controller
22
i
for controlling an operation of the image forming unit
22
. The operation controller
22
i
is connected to an external data processing device (not shown) such as a personal computer or the like located outside of the image forming unit
22
, and the controller
22
i
controls the operation of the image forming unit
22
on the basis of various operation control signal from the data processing device.
When the operation controller
22
i
receives an image formation start signal from the data processing device, the operation controller
22
i
makes the pick-up mechanism
16
pick up the upper most one paper sheet
12
from the tray
14
, and makes a rotation of the photosensitive drum
22
a
stars at a predetermined speed in a predetermined rotation direction in correspondence to the pick-up of the paper sheet
12
. At the same time, the operation controller
22
i
makes the discharging device
22
b
uniformly discharge the external circumferential surface of the photosensitive drum
22
a
being rotated, and makes the charging device
22
c
uniformly charge the external circumferential surface of the photosensitive drum
22
a
being rotated.
The exposing device
22
d
receives an image data signal from the data processing device through the operation controller
22
i,
and exposes the uniformly charged external circumferential surface of the photosensitive drum
22
a
in correspondence to the image data signal. Next, the developing device
22
e
develops the external circumferential surface of the photosensitive drum
22
a
with toner T to form a toner image at an exposed portion corresponding to the image data signal on the uniformly charged external circumferential surface.
The transfer unit
20
transfers the paper sheet
12
in the transfer path
18
such that an image formation start corresponding position on one plain side surface of the paper sheet
12
, which corresponds to an image formation start position separated from the leading end on the other plain side surface of the sheet
12
, faces the transfer device
22
f
when a leading end of the toner image on the external circumferential surface of the photosensitive drum
22
a
faces the transfer device
22
f.
Consequently, the transfer device
22
f
starts transferring the toner image on the external circumferential surface of the photosensitive drum
22
a
onto the other plain side surface (the image formation surface) of the paper sheet
12
at the image formation start position. Next, the separating device
22
g
separates the paper sheet
12
from the external circumferential surface of the photosensitive drum
22
a
while the toner image is held on the image formation surface on the paper sheet
12
.
The paper sheet
12
separated from the external circumferential surface of the photosensitive drum
22
a
while holding the toner image is directed toward the fixing device
22
h
in the transfer path
18
by the transfer unit
20
, and the fixing device
22
h
fixes the toner image onto the image formation surface of the paper sheet
12
. The paper sheet
12
which has passed through the fixing device
22
h
is ejected from the upper end of the transfer path
18
onto the recording medium discharge tray lob on the upper surface of the upper wall of the outer housing
10
through the outlet opening
10
a
of the upper wall of the outer housing
10
.
In the conventional printer which is constituted in the above-mentioned manner and is operated in the above described manner, each of the charging device
22
c,
the transfer device
22
f,
and the separating device
22
g
has a high voltage wire HVW respectively. With the application of a high voltage to the high voltage wire HVW, the wire HVW generates a corona discharge to make each of the devices
22
c,
22
f,
and
22
g
operate as described above.
The corona discharge ionizes oxygen molecules in the air so that ozone is generated. Ozone is toxic to the above described various devices and other members in the outer housing
10
of the conventional printer described above, particularly to a photosensitive layer of the external circumferential surface of the photosensitive drum
22
a,
thereby decreasing the life of these devices and members.
The conventional printer described above has a heat discharging fan for discharging heat generated from the above described various devices and other members in the inner space of the outer housing
1
to the outside space, and the heat discharging fan conveys ozone to the outside space together with heated air in the inner space of the outer housing
Frishauf Holtz Goodman & Chick P.C.
Toshiba Tec Kabushiki Kaisha
Tran Hoan
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