Electrophotography – Image formation – Fixing
Reexamination Certificate
2002-10-10
2004-02-10
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Fixing
C219S216000, C399S333000, C432S060000
Reexamination Certificate
active
06690907
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Patent Application No. 2001-62359, filed Oct. 10, 2001, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fusing apparatus of an electrophotographic image forming apparatus, and more particularly, to a fusing apparatus having an internal pipe maintaining a surface temperature of a fusing roller at a uniform level without a temperature deviation.
2. Description of the Related Art
FIG. 1
is a schematic perspective view of a conventional electrophotographic image forming apparatus. Referring to
FIG. 1
, the conventional electrophotographic image forming apparatus includes a paper ejecting unit
1
, an operating unit
2
, a control board cover
3
, an upper cover opening button
4
, a paper display window
5
, a multi-purpose feeding window
6
, a paper cassette
7
, an option cassette
8
, and an auxiliary stand
9
.
FIG. 2
is a schematic cross-sectional view of a conventional fusing apparatus
10
of the conventional electrophotographic image forming apparatus employing a halogen lamp as a heat source. Referring to
FIG. 2
, the conventional fusing apparatus
10
includes a cylindrical fusing roller
11
and a heat-generating portion
12
, e.g., the halogen lamp, installed at an interior center of the fusing roller
11
.
A coating layer
11
a
, such as Teflon, is coated on a surface of the fusing roller
11
. The heating-generating portion
12
generates heat inside the fusing roller
11
, and the fusing roller
11
is heated from an interior surface thereof by a radiant heat transmitted from the heat-generating portion
12
.
FIG. 3
is a longitudinal sectional view illustrating a relationship between the fusing apparatus
10
and a pressure roller
13
of the conventional electrophotographic image forming apparatus employing the halogen lamp as the heat source as shown in FIG.
2
.
Referring to
FIG. 3
, the pressure roller
13
is disposed to face a paper
14
in a lower portion of the fusing apparatus
10
. The pressure roller
13
is elastically supported by a spring device
13
a
to press the paper
14
toward the fusing roller
11
with a predetermined pressure, and the paper
14
passes between the fusing roller
11
and the pressure roller
13
. A powdered toner image
14
a
is formed on the paper
14
and is pressed with the predetermined pressure and heated by heat while passing between the fusing roller
11
and the pressure roller
13
. In other words, the toner image
14
a
is fixed onto the paper
14
by the heat of the fusing roller
11
and the pressure of the pressure roller
13
.
A thermistor
15
measuring the surface temperature of the fusing roller
11
and a thermostat
16
cutting off the supply of power when the surface temperature of the fusing roller
11
exceeds a predetermined set value, are provided at one side of the fusing apparatus
10
. The thermistor
15
measures the surface temperature of the fusing roller
11
and transmits an electric signal corresponding to the measured temperature to a controller (not shown) of a printer (not shown). The controller controls an amount of electricity supplied to the halogen lamp
12
according to the measured temperature to maintain the surface temperature of the fusing roller
11
within a given range. When the temperature of the fusing roller
11
exceeds the predetermined set value because the thermistor
15
and the controller fails in controlling the temperature of the fusing roller
11
, a contact (not shown) of the thermostat
16
becomes open to cut off the supply of power to the halogen lamp
12
.
Such a conventional fusing apparatus using the halogen lamp as the heat source unnecessarily consumes a large amount of electric power. Particularly, when power is turned on, the conventional fusing apparatus requires quite a long warming-up time. In other words, until the fusing roller
11
reaches a desired temperature after applying power, a predetermined time must elapse. The warming-up time may range from several tens of seconds to several minutes. In addition, in the conventional fusing apparatus, since the fusing roller
11
is heated by radiation transmitted from the heat source, heat transmission is slow, and compensation for a temperature deviation caused by a decrease in temperature occurring due to a contact with the paper
14
is slow, so it is difficult to maintain the temperature of the fusing roller
11
constant. Moreover, since the electric power must be periodically applied to the heat source in order to maintain the temperature of the fusing roller
11
constant in a standby mode in which an operation of the printer is in pause, unnecessary electric power is consumed. A considerable time is required to convert the standby mode into an operation mode for an image output, and thus it is difficult to achieve a fast image output.
FIG. 4
is a schematic longitudinal sectional view of another conventional fusing apparatus employed in the electrophotographic image forming apparatus. Referring to
FIG. 4
, a heating plate
22
is provided at an inner bottom portion of a flexible, cylindrical film tube
21
. A pressure roller
23
having a spring device
23
a
is disposed to face the heating plate
22
at a lower portion thereof and the paper
14
is disposed therebetween.
The film tube
21
is rotated by a separate rotating device. Although it consumes a lower power to locally heat a portion between the heating plate
22
and the pressure roller
23
, it is difficult to achieve fast printing in the fusing apparatus of FIG.
4
.
In order to solve the above problem, fusing apparatuses adopting a heat pipe capable of instantaneously heating the fusing roller using a high heat conductivity and having a low power consumption characteristic are disclosed in Japanese Patent Publication Nos. JP6348176, Hei 11-282294, and Hei 2000-25976.
The fusing apparatuses adopting the heat pipe are configured such that different heat sources are arranged at one portion of the fusing roller, the one portion deviating from a fusion area. Such arrangement of the heat sources may result in an increase in an overall size of the fusing apparatus, which needs to be improved in an increased structural complexity.
The fusing apparatuses disclosed in Japanese Patent Publication Nos. Showa 60-55368, Hei 4-335691, Hei 4-360185, Hei 8-171301, Hei 8-262905, Hei 8-305195 and 9-90811, may not have the increased structural complexity due to the heat source incorporated into the fusing roller. However, since these apparatuses have a plurality of the heat pipes locally disposed in the fusing roller, a manufacturing process is very complex. Also, since the heat pipes are locally disposed in the fusing roller, there is a temperature difference between a space between two adjacent heat pipes and portions directly contacting the heat pipes. Thus, since there is a difference in the surface temperature throughout a heat pipe, the toner image cannot be fixed properly on the paper, and a print quality of the toner image fixed on the paper deteriorates.
SUMMARY OF THE INVENTION
To solve the above and other problems, it is an object of the present invention to provide a fusing apparatus having an internal pipe with improved fusibility by maintaining an entire surface temperature of a fusing roller at a uniform level without a temperature deviation.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects of the invention, there is provided a fusing apparatus of an electrophotographic image forming apparatus. The fusing apparatus includes an internal pipe having a tubular body portion and end portions integrally formed with the body portion at both ends of the body portion, a heat-generating portion installed to wrap the bod
Royer William J.
Staas & Halsey , LLP
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