Electrophotography – Image formation – Charging
Reexamination Certificate
2000-11-21
2002-05-21
Brase, Sandra (Department: 2852)
Electrophotography
Image formation
Charging
C399S172000
Reexamination Certificate
active
06393237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scorotron charging apparatus consisting of a wire, shield, and a grid used in an electrophotographic apparatus including a printer and a copying apparatus and in particular, to a scorotron charging apparatus including a side seal arranged between the grid and the shield.
2. Description of the Related Art
It is known that in a conventional scorotron charging apparatus in an electrophotographic apparatus, charging can be performed with less wire current by increasing the shield voltage.
As shown in
FIG. 7
, the conventional scorotron charging apparatus is an electric charger including a shield
31
, a grid
33
, and a wire
34
. In this electric charger, the voltage of the shield
31
is increased to obtain a potential between the grid
33
and the wire
34
while a sufficient interval “a” is required between the shield
31
and the grid
33
so that no arc discharge is caused. For this, ozone leaks through the interval “a” in this electric charger.
Moreover, as shown in
FIG. 8
, another type of conventional scorotron apparatus includes a shield
41
, a grid
43
, a wire
44
, and an insulation material
42
covering the space between the shield
41
and the grid
43
, so that no ark discharge is caused between the shield
41
and the grid
43
and leakage of ozone can be prevented. In the space inside this electric charger, a great amount of ion in generated. In this structure, the ion adheres to the insulation material
42
to cause charging. Moreover, when the charging potential of the insulation material
42
exceeds a predetermined value, arc discharge is caused with respect to the shield
41
and the grid
43
, causing an incorrect operation of a control circuit in the vicinity due to noise.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide scorotron charging apparatus including a side seal made from a semiconductor material arranged between the grid and shield so as to increase the charging efficiency and assure a uniform and stable charging.
The scorotron charging apparatus according to the present invention comprises: a wire; a shield; a grid; and a side seal arranged between the grid and the shield.
According to another aspect of the present invention, the side seal may be made from a semiconductor material.
According to still another aspect of the present invention, the side seal may have a resistance value in a range from 1 to 100 M&OHgr;.
According to yet another aspect of the present invention, the side seal may be made from a conductive plastic containing a conductive agent such as carbon.
According to still further aspect of the present invention, the conductive plastic may be polycarbonate or polyacetal containing a conductive agent such as carbon.
According to yet still another aspect of the present invention, the side seal may be made from a material having a resistance value in a range from 1M to 1000 M&OHgr; cm.
According to still yet another aspect of the present invention, the current flowing into the side seal may create a voltage inclination.
According to yet another aspect of the present invention, the side seal may be made from a flat plate.
According to still another aspect of the present invention, a plurality of holes may be opened in the back surface of the shield for exhausting air.
According to still yet another aspect of the present invention, the apparatus may further comprise a fan arranged for generating an air flow through the plurality of holes for exhausting air.
REFERENCES:
patent: 3578970 (1971-05-01), Michaud et al.
patent: 4745282 (1988-05-01), Tagawa et al.
patent: 5526222 (1996-06-01), Fender
patent: 5655186 (1997-08-01), Godlove et al.
Brase Sandra
Fuji 'Xerox Co., Ltd.
McGinn & Gibb PLLC
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