Electrophotography – Image formation – Fixing
Reexamination Certificate
2001-09-05
2003-07-01
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Fixing
C118S060000
Reexamination Certificate
active
06587663
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a releasing agent applying apparatus for preferable use in a fixing apparatus of an image forming apparatus such as a copying machine or a printer and for applying a releasing agent to a fixing roller or the like.
2. Related Background Art
Referring to
FIG. 6
, there is shown a cross section of a fixing apparatus having an oil applying mechanism.
As shown in
FIG. 6
, the fixing apparatus comprises a fixing roller
151
which is a rotatably arranged fixing member, a pressing roller
152
which is a pressing member rotating being press-contacted with the fixing roller
151
, a releasing agent applying apparatus
153
which is a releasability imparting apparatus, and roller cleaning apparatuses
154
and
155
.
There are arranged heaters
156
and
157
such as halogen lamps inside the fixing roller
151
and the pressing roller
152
, respectively. In addition, thermistors
158
and
159
are arranged for the fixing roller
151
and the pressing roller
152
so as to be in contact therewith, respectively, thereby regulating temperatures of surfaces of the fixing roller
151
and the pressing roller
152
by controlling voltages to the heaters
156
and
157
via a temperature regulation circuit (not shown).
Additionally, the fixing roller
151
is provided with the cleaning apparatus
154
and the releasing agent applying apparatus
153
. The cleaning apparatus
154
cleans offset toner on the fixing roller
151
and the releasing agent applying apparatus
153
applies silicone oil which is a releasing agent to the fixing roller
151
, thus facilitating a separation of a transfer paper P which is a recording material from the fixing roller
151
and preventing toner offset.
The cleaning apparatus
154
comprises a cleaning web
154
a
made of a belt-shaped heat-resistant nonwoven fabric, a pushing roller
154
b
for pushing the cleaning web
154
a
against the fixing roller
151
, an unwinding roller
154
c
for unwinding a new cleaning web
154
a
, and a winding roller
154
d
for gradually winding up the cleaning web
154
a
having a deteriorated cleaning performance due to adhering toner. Particularly to prevent a detection failure on the thermistor
158
caused by adhering offset toner on the thermistor
158
, the cleaning apparatus
154
is arranged upstream of a rotary direction of the fixing roller
151
relative to the thermistor
158
.
Describing a method of winding up the cleaning web
154
a
, a solenoid (not shown) is turned on and a one-way clutch (not shown) operates when it is determined that copies have been made by a predetermined number of sheets on the basis of a counter (not shown), by which the cleaning web is wound up by a predetermined amount in a reverse direction to the rotary direction of the fixing roller
151
. The winding-up in the reverse direction prevents the cleaning web
154
a
from being wound up in the above rotary direction.
The releasing agent applying apparatus
153
comprises an oil pan
153
a
which is a storage member for storing a releasing agent such as silicone oil, rollers
153
b
and
153
c
which are releasing agent supplying members for scooping up oil which is a releasing agent from the oil pan
153
a
, an applying roller
153
d
which is a releasing agent applying member for applying oil from the scooping rollers
153
b
and
153
c
to the fixing roller
151
, and a regulating blade
153
e
which is a releasing agent regulating member for regulating an amount of the applied oil from the applying roller
153
d.
Particularly to apply oil uniformly to the fixing roller
151
, the releasing agent applying apparatus
153
is arranged downstream of the rotary direction of the fixing roller
151
relative to the thermistor
158
. The applying roller
153
d
is a rotatable roller coated with silicone rubber on its surface made of sponge rubber, abutting the fixing roller
151
for applying the oil. The regulating blade
153
e
is an elastic blade made of fluororubber or the like for regulating an amount of applied oil by an abutting angle, an abutting pressure, or the like.
In addition, the pressing roller
152
is provided with a cleaning apparatus
155
comprising a cleaning web
155
a
, a pushing roller
155
c
, an unwinding roller
155
b
, a winding roller
155
d
and the like in the same manner as for the cleaning apparatus
154
for the fixing roller
151
, so as to clean toner adhering to the pressing roller
152
via the fixing roller
151
.
Furthermore, there is an oil removing blade
160
which is a releasing agent removing elastic member for removing a surplus releasing agent remaining on the pressing roller
152
, abutting the pressing roller
152
. Without this oil removing blade
160
, the surplus releasing agent is stagnant in a nip between the fixing roller
151
and the pressing roller
152
, thereby staining a transfer paper or causing an approaching failure to the nip due to a slippage of an OHP transparent laminate film. As materials for the oil removing blade
160
, there can be used silicone rubber, fluororubber and the like. The blade abuts the pressing roller
152
by an appropriate approaching amount in a forward or backward direction relative to the rotary direction of the pressing roller
152
.
If a transfer paper P is a conveyed in this condition, the fixing roller
151
and the pressing roller
152
rotate, a silicone oil is applied to the fixing roller
151
on its surface as a releasing agent, the transfer paper P is pressed and heated at almost constant pressure and temperature in both directions from the outside of the front and rear surfaces when passing between the fixing roller
151
and the pressing roller
152
, by which an unfixed toner image on the surface of the transfer paper P is fluxed and fixed and then a full-color image is formed on the transfer paper P. The image-fixed transfer paper P is separated from the pressing roller
152
by a lower separation claw (not shown) and then ejected to an outside of the apparatus.
In the conventional releasability imparting apparatus such as the above releasing agent applying apparatus
153
, however, there is a disadvantage that it may cause the following problem.
In the releasing agent applying apparatus
153
, the amount of oil applied to the fixing roller
151
is suppressed by the regulating blade
153
e
to a predetermined amount. As the number of sheets to be processed increases, the regulating blade
153
e
is stained by offset toner or paper dust.
Then, if this kind of dust adheres to an edge portion of the regulating blade
153
e
where the regulating blade
153
e
abuts the applying roller
153
d
, only a portion cannot be submitted to the oil amount regulation on the fixing roller
151
, thereby causing oil to slip through the regulating blade
153
e.
This causes an oil streak for an OHP or for an image having a large amount of toner, which may lead to quality degradation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a releasing agent applying apparatus which prevents toner, paper dust or the like from adhering to a releasing agent regulating member.
It is another object of the present invention to provide a releasing agent applying apparatus which enables a releasing agent to be uniformly applied.
It is still another object of the present invention to provide a releasing agent applying apparatus which comprises an applying rotator for applying a releasing agent to an applied member, a supplying member for supplying a releasing agent to the applying rotator, a regulating member for regulating an amount of a releasing agent on the applying rotator, and a cleaning member for cleaning a surface of the applying rotator.
Other objects of the present invention besides those discussed above shall be apparent to those skilled in the art from the description of preferred embodiments of the invention which follows.
REFERENCES:
patent: 5463457 (1995-10-01), Takeuchi et al.
patent: 5563695 (1996-10-01), Sakurai et al.
patent: 563418
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Royer William J.
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