Electric heating – Heating devices – Combined with diverse-type art device
Reexamination Certificate
2000-03-29
2001-06-26
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with diverse-type art device
C399S330000
Reexamination Certificate
active
06252199
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a heating roller for fixing toner in especially an electrophotographic apparatus such as a printer.
Conventionally, toner fixing device in an electrophotographic apparatus such as a printer is constituted such that a heating roller having a heating means, and a press roller located to face each other, and printed paper is allowed to pass between these rollers so that toner is heated and fixed.
Moreover, as for the above-mentioned heating roller, a heating roller, which is constituted such that a heating element such as a halogen lamp is provided into a metallic pipe which is made of aluminum or stainless steel, etc. has been used, but there arose a problem that it needed not less than one minute for warming up because of its low heat effectiveness, and its electric power consumption also became high.
Therefore, there suggests a heating roller which is constituted such that a heating resistor is provided onto the outer circumferential surface of a cylinder made of a metallic pipe with an insulating layer made of an organic resin such as polyimide lying therebetween, and a cleavage layer is provided onto its surface (of. Japanese Patent Application Laid-Opens No. 55-72390/1990 and No. 62-200380/1987, etc).
In addition, there also suggests a heating roller for fixing which is constituted such that heating resistor is provided onto the inner circumferential surface of a cylinder with an insulating layer lying therebetween, and a cleavage layer is provided onto the outer circumferential surface of the cylinder (of. Japanese Patent Application Laid-Open No. 55-72390/1980, etc).
However, in the case of such a heating roller for fixing constituted such that a heating resistor is provided onto the circumferential surface of the cylinder with the insulating layer lying therebetween, during a long time use, there arose a problem that the cylinder and the heating resistor were easily short-circuited because of poor insulation of the insulating layer.
In the present invention, therefore, a heating roller for fixing, which is constituted such that a heating resistor is provided onto the circumferential surface of the cylinder with the insulating layer lying therebetween, and a cleavage layer is provided onto the outermost circumferential surface, is characterized in that the maximum height of surface roughness (Rmax) on the surface of the heating resistor of the cylinder is in the range of 0.8 to 50 &mgr;m.
Furthermore, the present invention is characterized in that no protrusion whose height exceeds 50 &mgr;m exists on the surface of the cylinder, and a number of the protrusions whose height is 20 to 50 &mgr;m is less than 2 per 1 cm
2
, and a number of the protrusion whose height is 10 is 20 &mgr;m is less than 5 per 1 cm
2
.
Namely, since the above-mentioned cylinder is mostly formed by drawing and converting a metallic pipe, many protrusions exist on its surface, and its maximum height of surface roughness (Rmax) is about 70 to 130 &mgr;m. For this reason, the thickness of the insulating layer becomes thinner at the protruded portions, and it easily causes poor insulation. In the present invention, accordingly, it was found that poor insulation could be prevented by removing the protrusion which exist on the surface of the above-mentioned cylinder, so that the maximum height of surface roughness (Rmax) is in the range of 0.8 to 50 &mgr;m.
In addition, even if the maximum height is within the said range, a lot of protrusions easily cause poor insulation. So, in this invention, it was found that when poor insulation can be further pretended by means that no protrusion whose height exceeds 50 &mgr;m exists on the surface of the said cylinder, and a number of the protrusion whose height is 20 to 50 &mgr;m is less than 2per 1 cm
2
, and a number of the protrusion whose height is 10 to 20 &mgr;m is less than 5 per 1 cm
2
.
The present invention relates to a heating roller for fixing toner in especially an electrophotographic apparatus such as a printer, and relates to a cylindrical heater which is used as a heater for hot water, and a air-conditioning heater.
Conventionally, a toner fixing device in the electrophotographic apparatus such as a printer is constituted such that a heating roller having a heat means, and a press roller located to face each other, and a printed paper is allowed to pass between these rollers so that toner is heated and fixed.
Moreover, as for the above-mentioned heating roller, a heating roller, which is constituted such that a heating element such as a halogen lamp is provided into a metallic pipe made of aluminum or stainless steel, etc. but there arose a problem that is needed not less than one minute for warming up because of its low effectiveness, and its electric power consumption also became high.
Therefore, there suggests a heating roller which is constituted such that a heating resistor is provided onto the outer circumferential surface of the cylinder made of a metallic pipe with an insulating layer made of an organic resin such as polyimide lying therebetween, and a cleavage layer is provided onto its surface (of. Japanese Patent Application Laid-Opens No. 55-72390/1980 and No. 62-200380/1987, etc).
As shown in
FIG. 11
, there also suggests a heating roller which is constituted such that a spiral slots
131
are formed on the full length of the heating resistor
103
which is formed on the whole surface of the cylinder
101
(of. Japanese Patent Application Publication No. 6-36121/1994 and Japanese Patent Application Laid-Open No. 2-308291/1990). In this way, a resistance value of the heating resistor
103
is adjusted to be a prescribed value by forming the spiral slots
131
, and the resistance value can be partially adjusted by changing intervals between the slots
131
. For example, the temperature of both ends of the heating roller for fixing easily drops by its heat radiation, but it is possible to heat uniformly by adjusting the intervals between the slots
131
and raising beforehand its resistance value of both ends of the heating resistor
103
.
Furthermore, a cylindrical heater having the same construction as the above-mentioned heater is used as a heater for hot water which heats water running inside, an air-conditioning heater, and a heater for heating a element, etc.
However, in the heating roller for fixing shown in
FIG. 11
, it is difficult to accurately adjust its resistance value partially because the spiral slots
131
are shaped on the full length thereof.
Namely, in the heating roller for fixing, since heat radiation easily occurs on its ends as mentioned above, it needs to raise the resistance of its ends. Furthermore, it needs to adjust the heat value by delicately changing the resistance value along an axial direction of the cylindrical like that it needs to vary the heat value on a paper-passing part from that on the other part. On the other hand, in the spiral slots
131
shown in
FIG. 11
extending to the full length thereof, it is very difficult to accurately form the slots
131
by delicately changing its interval since the resistance value can be adjusted only by the intervals of the slots
131
.
Accordingly, the present invention provides a cylindrical heater having a heating resistor on a surface of the cylinder with an insulating layer lying therebetween is characterized in that the heating resistor is divided into plural zones along an axial direction of the cylinder, and slots for adjusting the resistance are respectively shaped in each zone.
Namely, the slots are not formed on the full length of the surface, the slots are formed respectively in each zone along an axial direction. As a result, the resistance value can be adjusted partially and easily.
In addition, the present invention is characterized in that the slots formed almost parallel at a certain angle with respect to the axial direction of the cylinder. Furthermore, the almost parallel slots mean that respective slots are arranged almost parallel when the heating resistor is unfolded in plain styl
Hayashi Kouihi
Maruyama Takahiro
Nakamura Shigenobu
Takenishi Shinsuke
Toyota Katsuya
Hogan & Hartson LLP
Kyocera Corporation
Pelham Joseph
LandOfFree
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