JPH06202503A - Ceramic heater - Google Patents

Abstract

PURPOSE:To assure sufficient electrical reliability and to make size smaller, electric consumption lower and cost lower by shifting the positions of first and second electrical contact parts from each other in the longitudinal direction of a ceramic substrate outside an electrical resistor position and providing these contact parts wider than the width of the patterns formed on the ceramic substrate. CONSTITUTION:The first and second electrical contact parts 23, 24 exist on the same end side in the longitudinal direction of the ceramic substrate 21, are shifted in their positions from each other in the longitudinal direction of the ceramic substrate 21 outside the electrical resistor position and are provided wider than the pattern parts 22, 25, 26 exclusive of the contact parts formed on the ceramic substrate 21. One piece of a connector 10 for power feed provided with both of power feed electrodes 5a, 6a of the electrical contact parts 23, 24 is fitted to one end provided with the electrical contact parts 23, 24 to supply electric power to the electrical resistor 22. Then, the contact area is increased without increasing the area of the ceramic substrate 21. The distance between the electrical contact parts 23, 24 is sufficiently obtd. and the reliability is assured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is based on a heat-resistant and electrically insulating ceramic substrate and an electric resistor (current-generating resistor) formed on the substrate. The present invention relates to a ceramic heater that supplies electric power to generate heat.

[0002]

2. Description of the Related Art The ceramic heater as described above is used, for example, as a heating body of a film heating type image heating and fixing device.

A film heating type image heating and fixing device is
JP-A-63-313182 and JP-A-1-2636
No. 79 / JP-A-2-157878 / JP-A-4
No. 44075 to 44083, a method of applying heat from a heating element to a recording material as a material to be heated through a film to heat and fix an unfixed image on the recording material as a permanent image. In addition, other known heat roller system
Compared with image heating and fixing devices such as hot plate type and heat chamber type, since a low heating capacity heating element with a rapid temperature rise and a thin film can be used, power saving and wait time reduction (quick startability) ) Is possible. In addition, it has an advantage that various drawbacks of other conventional heating devices can be eliminated, and is effective. The ceramic heater as described above is used as the heating element.

In FIG. 3, Japanese Patent Application Laid-Open No. 4-44075 to 44083.
The schematic configuration of the film heating type image heating and fixing device disclosed in Japanese Patent Laid-Open Publication No. 2003-242242 is shown.

Reference numeral 1 designates a film inner surface guide member made of a heat-resistant / heat-insulating material having a substantially semi-circular trough shape in cross section. A heating element fitting groove is provided along the length of the guide member 1 at a substantially central portion on the lower surface of the outer surface thereof, and a low-heat capacity ceramic heater (heating element) 2 is fitted and supported in the groove.

A cylindrical heat-resistant fixing film 3 is loosely fitted onto the film inner surface guide member 1 with the heater 2. That is, the inner peripheral length of the cylindrical fixing film 3 and the outer peripheral length of the film inner surface guide member 1 including the heater 2 are larger than those of the film 3 by, for example, 3 mm, so that the film 3 includes the guide member 1 including the heater 2. However, the circumference is loosely fitted to the outside.

Reference numeral 4 is a pressure roller (pressure contact roller, backup roller), and the film 3 is sandwiched between the pressure roller 4 and the heater 2 to press the pressure roller 4 against the heater 2 (for example, The total pressure in A4 is 3 to 6 kg).

A gear (not shown) fixed to one shaft end of the pressure roller 4 meshes with a gear (not shown) of a drive system of the image forming apparatus main body, and is rotationally driven at a predetermined peripheral speed. As a result, the surface friction of the pressure roller 4 causes the cylindrical fixing film 3 to slide in close contact with the lower surface of the heater 2 and rotate around the film inner surface guide member 1.

In this film rotation driving state, the recording material P carrying the unfixed toner image T is introduced between the film 3 and the pressure roller 4, and is brought into close contact with the rotating film 3 and fixed together with the film 3. When the recording material P passes through the fixing nip portion N by passing through the nip portion N, the heater 2
Is applied to the recording material P via the film 1 to heat and fix the toner image T.

That is, the recording material P does not slip at least in the fixing nip portion N due to the contact pressure of the rotary pressure roller 4 against the heater 2, and the fixing film 3 and the pressure roller 4 are not slipped.
Sent at the same speed as. The heat of the heater 2 is applied to the fixing film 3 by using this fixing nip portion passing process as a heating and pressurizing process.
The unfixed toner image T on the recording material P is melted and pressed.

After the fixing film 3 and the recording material P have passed through the fixing nip portion N, they are conveyed while being in close contact with each other due to the adhesive force of the toner T which is melted and softened. The heat of the softened / melted toner T is radiated as a cooling process in this carrying process.
The toner T is cooled and solidified to form a permanently fixed image on the recording material P. After the cooling step, the fixing film 3 and the recording material P are easily separated from each other by the cooling and solidification of the toner, and the recording material P is discharged from the apparatus.

The fixing film 3 has heat resistance, toner releasability, and
It is a tough single layer film or a composite layer film that has been subjected to a desired surface treatment or lamination treatment. For example, about 50 μm polyester (PE
T) or a single layer film of polyimide (PI), or a composite layer film obtained by further treating the film surface with a release layer of tetrafluoroethylene (PTFE).

The ceramic heater 2 as a heating element is shown in FIG.
As shown in (a) of FIG. 3, an insulating, high heat resistant, low heat capacity ceramic substrate 21 having a length in a direction orthogonal to the recording material P conveyance direction, and printing on the front surface side of the substrate along the length. It has a low heat capacity as a whole, which has a basic structure of an electric resistor 22 formed in a linear shape or a strip shape.

The ceramic substrate 21 has a thickness of 1 m as an example.
m, width 6 mm, length 240 mm alumina (Al ₂ O
₃ ) Substrate. Alternatively, it is a composite material substrate including the same.

The electric resistor 22 is provided along the longitudinal direction in the substantially central portion on the front surface side of the ceramic substrate 21, for example, TaSiO.
₂ , Ag / Pd (silver palladium), RuO ₂ , Ta ₂
N, Nichrome, PdO, Pd, Ag, Bi ₂ Ru ₂ O ₇
Conductive heating resistors such as the above, and paste materials such as these with a thickness of about 10
It is provided by vapor deposition, sputtering, CVD, screen printing or the like in a linear or strip shape having a width of 1 μm and a width of 1 to 3 mm.

Reference numerals 23 and 24 are electrically connected to both longitudinal ends of the electric resistor 22, respectively, and are pattern-formed on the surfaces of both ends of the ceramic substrate 21. 2 is an electrical contact portion (electrode portion). The first and second electrical contact parts are good conductors A
g, Pt, Au, etc.

The ceramic heater 2 is an electric resistor 2.
The surface on which 2 is formed is used as a film contact sliding surface, and is attached and held on the lower surface of the film inner surface guide member 1 with the surface side facing downward.

The surface of the ceramic heater 2 on which the electric resistor 22 is formed, which is a film contact sliding surface, is covered with a surface protective layer of thin heat-resistant glass or fluororesin in order to prevent abrasion of the film 3 due to sliding conveyance. You may. In addition, a lubricant may be applied to the sliding contact surface of the heater 2 with the fixing film.

Numerals 5 and 6 are power supply connectors (external power supply connectors) fitted to both ends of the ceramic heater 2.
And the power supply electrode (contactor) 5a of each connector
6a comes into contact with the first and second electrical contact portions 23 and 24 on the ceramic heater 2 side to establish electrical conduction.

Reference numerals 7 and 8 denote a power supply source (commercial power supply) in series between the connectors 5 and 6 and a switch element circuit for controlling the supply power. The switch element circuit 7 is controlled by a microcomputer (CPU) 9.

When the switching element circuit 8 is turned on by the CPU 9, the electrical resistor 2 of the ceramic heater 2 is turned on.
Power is supplied to 2, and the electric resistor 22 rapidly raises the entire temperature of the ceramic heater 2 including the heat generating substrate 21. The temperature rise temperature is detected by a temperature detection element (not shown), the temperature detection information is fed back to the CPU 9, and the CPU 9 appropriately turns on the switching element circuit 8 so that the temperature of the ceramic heater 2 is maintained at a predetermined fixing temperature. The power supply to the electric resistor 22 of the ceramic heater 2 is controlled by turning off.

[0022]

In the ceramic heater 2 shown in FIG. 4 (a), the first and second electrical contact portions 23 and 24 for supplying electricity to the electrical resistor 22 are provided at both longitudinal ends of the heater. Since the ceramic heater 2 is mounted on the heater 2, the power supply connectors 5 and 6 must be fitted to the ceramic heater 2 on both sides of one end and the other end in the longitudinal direction of the heater 2.
In addition, the length of the lead wires 5b and 6b for power feeding also becomes long, which causes a problem in assembly efficiency.

Therefore, there is a connector in which the power supply connector may be fitted only to one end side of the heater 2 so as to solve the above-mentioned problems such as the assembly efficiency and the length of the power supply lead wire.

That is, as shown in FIG. 4B, a pair of electric resistors 2 are arranged in parallel on the surface of the ceramic substrate 21 along the longitudinal direction.
2 ₁ · 22 ₂ to form, the pair of resistors 22 _1, 22 ₂
First and second electrical contact portions 23 and 24 are arranged side by side in the width direction of the ceramic substrate 21, and conductive patterns 25 such as Ag, Pt, Au, etc. are provided between the other end portions on the same side.
Of the heater 2,
One of the power supply electrodes 5a and 6a for the first and second electric contact portions 23 and 24 is provided on the one end side where the first and second electric contact portions 23 and 24 are provided. The power supply connector 10 is fitted to supply electric power to the electrical resistor 22.

However, in this structure, both the first and second electrical contact portions 23 and 24 arranged side by side on the same end portion side surface of the heater substrate 21 are connected to the power supply electrode 5a on the connector 10 side.
In order to secure a sufficient electrical contact state with the 6a, the required width as well as the one shown in FIG. If a sufficient electrical separation distance (extended surface distance) is secured, the ceramic substrate 21 to be used becomes wider and has a larger area than that of FIG. 2A, and the heater 2 and the device are increased in size and power consumption is increased. , Increase costs, etc.

According to the present invention, similarly, the first and second electric contact portions for supplying electric power to the electric resistor are arranged at one end portion on the same side of the heater, and power is supplied only to the end portion of the heater. The ceramic heater has a structure in which the connector for electrical connection is fitted, but the area of both the first and second electrical contact portions is as large as necessary without increasing the area of the ceramic substrate, and the first and second It is an object of the present invention to provide a device which solves the above problems by making it possible to secure a sufficient distance between the electrical contact parts.

[0027]

SUMMARY OF THE INVENTION The present invention is a ceramic heater having a ceramic substrate and an electric resistor formed on the substrate as a basic structure, and supplying electric power to the electric resistor to generate heat. , A first electric contact portion for supplying electric power to the electric resistor and a second electric contact portion after passing through the electric resistor from the first electric contact portion are both ceramics. On the same end side in the longitudinal direction of the substrate, offset from each other in the longitudinal direction of the ceramic substrate outside the position of the electrical resistor, and wider than the other pattern portions formed on the ceramic substrate. A ceramic heater, characterized in that it is provided.

[0028]

Since the first and second electric contact portions for supplying electric power to the electric resistor are on the same end side of the heater, the external power feeding connector may be fitted only on one end side of the heater. Therefore, the assembling efficiency is good, and the lead length of the power supply lead wire is also short.

By disposing the first and second electric contact portions provided on one end portion side on the same side of the heater so as to be displaced from each other in the longitudinal direction of the ceramic substrate, the width dimension of the ceramic substrate is not increased. That is, without increasing the area of the ceramic substrate, it is possible to make the contact area as wide as necessary to secure a sufficient electrical contact state with the power supply electrode of the external power supply connector, and the distance between both contact sections. Can be taken sufficiently and the electrical reliability can be secured.

From the position of the electric resistor, the first and second
By displacing the electric contact portion of (1), it is possible to prevent thermal stress on the power feeding electrode of the power feeding connector.

[0031]

【Example】

<Embodiment 1> (FIG. 1) A ceramic substrate 2 according to this embodiment includes a ceramic substrate 21.
The electric resistor 22 and the power supply circuit pattern 26 are formed in parallel along the longitudinal direction on the surface of the electric resistor 22.
A first electric contact portion 23 is provided on the surface of the ceramic substrate on the one end side thereof so as to be electrically connected to the electric resistor 21, and the same side of the power supply circuit pattern 26 as the first electric contact portion 23 is provided. A second electric contact portion 24 is provided in series with the power supply circuit pattern 26 on the surface of the ceramic substrate on the side of one end thereof. The other end of the electric resistor 22 and the other end of the power supply circuit pattern 26 are electrically connected by a conductive pattern 25.

The first and second electrical contact portions 23, 24,
The conductive pattern 25 and the power supply circuit pattern 26 are Ag,
It is made of a good conductor material such as Pt or Au.

The ceramic substrate 21 is made of Al ₂ O ₃ or the like, and the electric resistor 22 is an energized heat generating resistor such as PdO or Pd.

Then, the first and second electric contact portions 23 are formed.
As shown in the drawing, 24 is formed on the ceramic substrate 21 on the same end side in the longitudinal direction of the ceramic substrate 21 and displaced from each other in the longitudinal direction of the ceramic substrate outside the position of the electric resistor. Other pattern part 2
It is provided with a width wider than 2, 25 and 26.

With respect to one end side of the heater 2 where the first and second electric contact portions 23 and 24 are provided, the power supply electrode 5a for the first and second electric contact portions 23 and 24 is provided. 6
One power supply connector 10 having both a is fitted and the electric resistor 22 is inserted as shown in FIGS. 4 (a) and 4 (b).
Power is supplied to.

The power supply connector 10 is shown in FIG.
Similar to the above, since it is sufficient to fit the heater 2 only to one end side, problems such as the assembly efficiency and the length of the power supply lead wire are eliminated.

The first side provided on the same end of the heater 2
And the second electrical contact portions 23 and 24 are connected to the ceramic substrate 2
By arranging them so as to be displaced from each other in the longitudinal direction of 1, the contact area can be increased as required without increasing the width dimension of the ceramic substrate 21, that is, without increasing the area of the ceramic substrate 21. Both contact points 23.2
The distance of 4 can be taken sufficiently and the electrical reliability can be secured.

By displacing the first and second electrical contact portions 23 and 24 from the position of the electrical resistor 22, it is possible to prevent thermal stress on the power feeding electrodes 5a and 6a of the power feeding connector 10.

<Embodiment 2> (FIG. 2) The ceramic heater 2 of the present embodiment includes a ceramic substrate 21.
2A along the longitudinal direction on the surface (heater surface side) of FIG.
The electrical resistor 22 is formed as shown in FIG.
2 (b) of FIG.
Forming a power supply circuit pattern 26 as described above, and providing a first electrical contact portion 23 on the surface of the ceramic substrate on one end side of the electrical resistor 22 so as to be electrically connected to the electrical resistor 22.
A second electric contact portion 24 is provided in series with the electric circuit pattern 26 on the back surface of the ceramic substrate on one end side of the power supply electric circuit pattern 26 on the same side as the first electric contact portion 23. Further, the other end side of the electric resistor 22 on the front surface side of the ceramic substrate and the other end side of the power supply circuit pattern 26 on the rear surface side of the ceramic substrate are electrically through holes 27 formed of Ag, Pt, Au or the like. I have been in contact with.

The first and second electrical contact portions of the heater 2 are provided with respect to the one end portions where the first and second electrical contact portions 23 and 24 are provided on the front and back surfaces of the ceramic substrate 21. 23.
One power supply connector 10 having both power supply electrodes 5a and 6a for 24 is fitted to supply power to the electrical resistor 22. FIG. 2C is an enlarged vertical cross-sectional view of the heater end side including the first and second electrical contact portions 23 and 24.

Also in the heater 2 of this embodiment, the first and second electrical contact portions 23 and 24 are on the same end side in the longitudinal direction of the ceramic substrate 21 and outside the electric resistor position. Other pattern portions 2 which are displaced from each other in the longitudinal direction and which are formed on the ceramic substrate 21
It is provided with a width wider than those of 2.26.27 and has the same effect as the heater 2 of the first embodiment.

Further, as in this embodiment, the ceramic substrate 21
When the first and second electric contact portions 23 and 24 for supplying electric power to the electric resistor 22 are separately arranged on the front surface side and the back surface side of the heater 2, the heater 2 of the first embodiment is further provided. The width of the ceramic substrate 21 can be made narrow.

[0043]

As described above, according to the present invention, the first and second electric contact portions for supplying electric power to the electric resistor are arranged at one end side on the same side of the heater, and the heater is provided. Regarding the configuration in which the assembly efficiency is improved by fitting the power supply connector only on the end side and the lead wire length is shortened, the first and Any of the second electrical contact portions can have a large area, and the distance between both contact portions can be sufficiently large to ensure sufficient electrical reliability, downsizing and space saving. It is possible to reduce the power consumption and the cost, and it is effective and suitable for use as a heating body of a film heating type image heating and fixing device as in the above-mentioned example.

[Brief description of drawings]

FIG. 1 is a plan view of a ceramic heater according to a first embodiment.

2A is a plan view of the front surface side of the ceramic heater of Example 2, FIG. 2B is a rear view, and FIG. 2C is a heater end side having first and second electrical contact portions. Enlarged vertical sectional view

FIG. 3 is a schematic configuration diagram of an example of a film heating type image heating and fixing device using a ceramic heater.

4A is a plan view of a ceramic heater of the apparatus and an energization circuit diagram, and FIG. 4B is a plan view of a ceramic heater having another configuration.

[Explanation of symbols]

1 film inner surface guide member 2 heating member (ceramic heater) 3 cylindrical fixing film 4 pressing roller N press nip (fixing nip portion) P recording material T unfixed toner image 21 ceramic substrate 22, 22 _1, 22 ₂ Electrical Resistor (Electrical heating resistor) 23.24 First and second electrical contact parts (electrode part) 25 Conductive pattern 26 Power supply circuit pattern 27 Through hole 5 ・ 6 ・ 10 Power supply connector 5a ・ 5b Power supply electrode 7 power supply (commercial power supply) 8 switching element circuit 9 microcomputer (CPU)

Claims (1)

[Claims] 1. A ceramic heater having a ceramic substrate and an electric resistor formed on the substrate as a basic structure, and supplying electric power to the electric resistor to generate heat. The first electrical contact portion for supply and the second electrical contact portion after passing through the electrical resistor from the first electrical contact portion are both on the same end side in the longitudinal direction of the ceramic substrate. And being displaced from each other in the longitudinal direction of the ceramic substrate outside the electrical resistor position,
A ceramic heater having a width wider than that of the other pattern portion formed on the ceramic substrate.