JPH0529068A - Structure of heating element and heater for office automation equipment - Google Patents

Abstract

PURPOSE:To prevent an electric resistance film from electric disconnection by laminating a first current supplying conductor film, the electric resistance film and a second current supplying conductor film on an insulating substrate having heat resistance. CONSTITUTION:A first current supplying conductor film 2 is formed on an insulating substrate 1 made of a heat resistant material. A current supplying terminal 4 connected to an AC power source 3 is disposed at one end of the first conductor film 2. An electric resistance film 5 is superposed in a laminated manner. A second current supplying conductor film 6 is laminated on the electric resistance film 5. Another current supplying terminal 7 connected to the AC power source 3 is disposed at one end of the second current supplying conductor film 6. Accordingly, the electric resistance film is of three layer structure. The electric resistance film can generate heat over the whole surface thereof when a voltage is applied between the first current supplying conductor film and the second current supplying conductor film, thus preventing the electric resistance film from electric disconnection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a heating body used in a heating section such as a toner fixing section in a copying machine or an electrophotographic printer (laser printer, printer, etc.), and copying using this heating body. The present invention relates to a heating device in an office automation device such as a machine or an electrophotographic printer.

[0002]

2. Description of the Related Art Heretofore, a roller type heating element has been used as this type of heating element, but this roller type heating element is not only complicated in structure and considerably expensive, but also large in size. ,
Recently, as described in JP-A-2-65086 and JP-A-2-129883 as prior art, a strip-shaped electric resistance portion is provided on the upper surface of a rectangular insulating substrate. Is formed so as to extend in a straight line along the longitudinal direction of the electric resistance part, and energization terminal parts are formed at both ends of the electric resistance part so that the electric resistance part generates heat from the energization terminal parts at both ends thereof by applying a current. The heating element configured as above is used.

[0003]

However, the heating element according to the prior art has a structure in which a strip-shaped electric resistance portion and current-carrying terminal portions for both ends of the electric resistance portion are formed on the upper surface of the insulating substrate. The serial structure has advantages that it is simple and inexpensive, and that it can be downsized, but on the other hand ,. When a part of the strip-shaped electric resistance portion formed on the upper surface of the insulating substrate is defective, the electric circuit is cut off and the electric resistance portion does not generate heat. Must be replaced. ． Since the electric resistance part of the heating element of the prior art is a serial type, a large current flows in the connection part of the electric resistance part to the energization terminal part, and the temperature difference between the energization terminal part and Is large, so when using repeatedly,
The disconnection frequently occurs at the connecting portions having different material characteristics, and the durability is low. ． The heating element of the prior art, the electric resistance portion is a serial type, in order to expand the area of the heat generation in the width direction,
When the width dimension of the electric resistance portion is increased, the resistance value is reduced and the amount of heat generation is reduced. Therefore, there is a certain limit in expanding the heat generation region in the width direction, and it is not possible to widen the width. . ． In order to improve the above-mentioned point, the above-mentioned JP-A-2-1 is used.
As described in Japanese Patent No. 29883, it is sufficient to widen the connecting portion. However, if the connecting portion is widened, the resistance of that portion is low, and accordingly, the amount of heat generation is small and the temperature is low. The temperature distribution in the longitudinal direction becomes uneven. There was a problem such as.

An object of the present invention is to solve the above-mentioned problems in a heating element in which an electric resistance portion is formed on the upper surface of an insulating substrate, and another object is to provide a copying machine or electrophotography. An object of the present invention is to provide a heating device having high durability and reliability in office automation equipment such as a printer.

[0005]

According to the present invention, which has achieved the above-mentioned object, an electric resistance film is provided on the upper surface of a heat-resistant insulating substrate.
A first energizing conductor film was sandwiched between the electric resistance film and the insulating substrate to form a laminate, and a second energizing conductor film was formed on the upper surface of the electric resistance film.

[0006]

With this structure, the electric resistance film has a three-layer structure in which it is sandwiched between the first conducting conductor film and the second conducting conductor film, and the first conducting conductor film and the second conducting conductor film are formed. By applying a voltage between the electric resistance film,
Since heat is generated over the entire surface, it is possible to reliably prevent the occurrence of disconnection in the electric resistance film, and to lower the temperature of both end portions along the longitudinal direction to a greater extent than in the case of the prior art. In addition, even if a part of the electric resistance film and the both-conducting conductor film is lost, the current supply to the whole is not interrupted, so that the whole part does not generate heat due to damage. This can be prevented, and even if the width dimension of the electric resistance film is increased, the width dimensions of the first conducting conductor film and the second conducting conductor film are correspondingly increased, so that the entire surface is surely secured. It can generate heat.

[0007]

As described above, according to the present invention, it is possible to prevent a situation in which a part of the electric resistance film and the both-current-carrying conductor film is damaged and the whole heat generation does not work.
Moreover, it is possible to prevent the occurrence of disconnection in the electric resistance film by repeated use, it is possible to average the temperature distribution along the longitudinal direction, and further, if it is possible to expand the heat generating region in the width direction, The reliability and durability of the heating element can be greatly improved.

On the other hand, since the heating element of the present invention has the effects as described above, as described in "Claim 2", the heating element of the present invention is fixed to a toner in a copying machine or an electrophotographic printer. When it is used as a heating section of an OA device such as a section, the durability and reliability of the heating device of the OA device can be improved.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. In the figure, reference numeral 1 denotes an insulating substrate formed of a heat-resistant material such as ceramic in a rectangular shape. On the upper surface of the insulating substrate 1, a first conductive conductor film 2 is formed in a strip shape having a width W. A current-carrying terminal portion 4 for the AC power source 3 is provided at one end thereof, and then an electric resistance film 5 is laminated so that the outer peripheral edge of the electric resistance film 5 is protruded from the outer peripheral edge of the first current-carrying conductive film 2 by an appropriate size. Then, a second conducting conductor film 6 having substantially the same width dimension as that of the first conducting conductor film 2 is laminated on the upper surface of the electric resistance film 5, and the second conducting film is formed. An energizing terminal portion 7 for the AC power source 3 is provided at one end of the conductor film 6.

Reference numeral 8 is a protective film such as glass that covers the entire surface, and the first conducting conductor film 2 and the second conducting conductor film 6 are coated with a paste such as gold or silver and then baked. The electric resistance film 5 is also formed by
It is formed by applying a paste such as ruthenium oxide or a silver-palladium alloy and then firing it. With this structure, the electric resistance film 5 has a three-layer structure in which it is sandwiched between the first conducting conductor film 2 and the second conducting conductor film 6, and the first conducting conductor film 2 and the second conducting conductor are formed. By applying a voltage between the electric resistance film 5 and the film 6, the electric resistance film 5 generates heat over its entire surface.

Therefore, it is possible to surely prevent the electric resistance film 5 from being broken, and it is possible to greatly reduce the temperature of the both end portions along the longitudinal direction from the case of the prior art. Yes, and the electric resistance film 5
Also, even if a part of the two conducting conductor films 2 and 6 is lost, the energization to the whole is not interrupted, so that it is possible to prevent the entire part from being extinguished due to damage.
Further, even if the width dimension of the electric resistance film 5 is increased, the width dimensions of the first conducting conductor film 2 and the second conducting conductor film 6 are correspondingly increased, so that the entire surface thereof is surely heated. It is possible.

By the way, the above-mentioned heating element generates heat over the entire width W, and the temperature at both ends in the width direction is determined by heat radiation to the atmosphere.
The temperature in the central portion in the width direction also tends to be low.
Therefore, in the case where heat is generated over the portion of the width dimension W, in order to make the entire temperature in the width direction exceed the required temperature, the temperature characteristic is shown in FIG.
The temperature at the center in the width direction will be much higher than the required temperature.
The durability of the electric resistance film 5 is deteriorated.

On the other hand, as shown in FIGS. 4 and 5, the first conducting conductor film is composed of two first conducting conductor films 2a and 2b.
Then, the electric resistance films 5a and 5b are respectively formed on the upper surfaces thereof, and then the second conducting conductor films 6a and 6b are formed on the upper surfaces of the electric resistance films 5a and 5b, respectively. Then, since both of the electric resistance films 5a and 5b generate heat at the same time, the temperature characteristic of each of the electric resistance films 5a and 5b becomes as shown by solid lines Ba and Bb in FIG. The temperature of the part can be brought close to the required temperature, and the temperature distribution in the width direction can be averaged.

FIG. 4 is a perspective view of a copying machine using toner. In this figure, reference numeral 9 is a paper sheet 10.
Is a transfer roller for heating and fixing the paper 10 printed by the transfer roller 9 by the heating device 11. The heating device described in the embodiment of FIG. 1 is used as the heating device 11. The sheet 10 is used in the width direction by contacting the heating element in the embodiment of FIG. 1 while moving or in the vicinity thereof. Can be heated to about the same temperature, and in the same way,
It can be applied to a heating device in various OA devices such as a toner fixing unit in an electrophotographic printer.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III in FIG.

FIG. 4 is a plan view showing a second embodiment of the present invention.

5 is an enlarged sectional view taken along line VV of FIG.

FIG. 6 is a perspective view showing a main part of a copying machine.

[Explanation of symbols]

1 Insulation board 2, 2a, 2b first conducting conductor film 3 AC power supply 4 energizing terminals 5,5a, 5b Electric resistance film 6,6a, 6b Second conductive film

Claims (2)

[Claims] 1. An electric resistance film is formed on the upper surface of a heat-resistant insulating substrate in a laminated shape with the first conducting conductor film sandwiched between the electric resistance film and the insulating substrate, and the upper surface of the electric resistance film. A structure of a heating body, characterized in that a second conducting conductor film is formed on the substrate. 2. A heating device for OA equipment, characterized in that the heating element according to claim 1 is used for a heating portion in OA equipment such as a toner fixing portion in a copying machine or an electrophotographic printer. .