JPH0829267A - Structure of temperature detection element in line-shaped heating element and its formation method - Google Patents

Abstract

PURPOSE:To obtain a line-shaped heating element which reduces the influence of a noise by increasing a current in a high-temperature region, which reduces the change amount of a resistance value and whose temperature control accuracy is enhanced by a method wherein a resistor which contains cobalt and/or manganese is formed on an insulating board so as to be filmlike. CONSTITUTION:In a line-shaped heating element 1, a heat-generating resistor 3 is formed on the surface of an insulating board 2 so as to be a line shape. A paste, for a resistor, which contains one or both out of cobalt and manganese is screen-printed on the rear of the board 2, it is then fired, and a filmlike resistor 5 is formed. Then, a conductive paste such as a silver paste or the like is screen-printed on the rear of the board 2, it is then fired, and one pair of electrode patterns 7, 8 are formed in such a way that they are overlapped partly with both ends of the resistor 5. The resistor 5 is trimmed in such a way that its resistance value becomes a prescribed value, and it is then overcoated with a protective film 9 such as a glass or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a temperature of a heating resistor in a line type heating body formed by linearly forming a heating resistor on the surface of an insulating substrate, and the temperature becomes a predetermined value. The present invention relates to the structure of a temperature detecting element for detecting the temperature of the heating resistor and the method for forming the temperature detecting element when performing feedback control as described above.

[0002]

2. Description of the Related Art Conventionally, for this type of temperature detecting element, a thermistor chip piece formed by sintering a ceramic containing a metal oxide as a main component is used. The back surface of the insulating substrate is die-bonded so that both ends of the thermistor chip piece are electrically connected to a pair of electrode patterns previously formed on the back surface of the insulating substrate. By utilizing the fact that it changes with temperature, by increasing or decreasing the amount of power to the heating resistor,
The configuration is such that the temperature is controlled to reach a predetermined value.

However, in such a structure in which the thermistor chip piece is die-bonded between the pair of electrode patterns previously formed on the surface of the insulating substrate in the line type heating element, the thermistor chip piece is used. However, since it is lifted by the thickness of the electrode pattern from the surface of the insulating substrate, the response is low,
Moreover, since the thermistor chip piece is projected from the surface of the insulating substrate, the stage member that supports the insulating substrate in the line-type heating element from the back surface side thereof,
It is necessary to provide a recess so that the thermistor chip piece can be fitted in the recess, and since the interior of the recess becomes a heat storage space, not only the correct temperature cannot be detected, but also the thermistor chip piece manufacturing process, Since the step of die-bonding the thermistor chip piece to the insulating substrate is required, the manufacturing cost is significantly increased in combination with the provision of the recess in the stage member.

In addition, since the temperature resistance value of the thermistor chip changes subtly due to the difference in thermal expansion between the thermistor chip and the insulating substrate, the temperature control accuracy is low. Therefore, Japanese Patent Laid-Open No. 5-265350 as a prior art discloses that, in order to solve the problem of using the thermistor chip, the back surface of the insulating substrate in the line-type heating element contains dangsten and molybdenum. Forming a film-shaped resistor by applying a resistor paste having a high positive temperature coefficient of resistance to the film by screen printing and baking it, and using this film-shaped resistor as a temperature detection element. Is proposed.

[0005]

However, as in this prior art, the film resistor used as the temperature detecting element is
By including dangsten and molybdenum, as shown by the dotted curve A in FIG. 7, it has a positive high temperature coefficient and has a high resistance value in a high temperature range and a small current value, which causes noise. In addition to being easily affected by the above, there is a problem that the accuracy of temperature control for the heating resistor is considerably low because the amount of change in resistance value in a high temperature range is large.

The present invention has the above prior art in the case where the film-like resistor formed directly on the back surface of the insulating substrate in the line type heating element is used as the temperature detecting element as in the above prior art. It is a technical object to provide a structure of a temperature detecting element and a method for forming the temperature detecting element, which solve the problem.

[0007]

In order to achieve this technical object, the present invention provides a "line type heating element comprising a heating resistor formed on an insulating substrate, wherein the insulating substrate is either cobalt or manganese. A resistor including one or both of them is formed in a film shape, and the film-shaped resistor serves as a temperature detection element for the heating resistor. "

Further, the forming method according to the present invention is a line type heating element comprising a heating resistor formed on an insulating substrate, wherein the insulating substrate contains one or both of cobalt and manganese. The paste is applied in a film form by screen printing and then fired to form a film-like resistor, and then electrode patterns for both ends of this film-like resistor are prepared. It is formed so that it overlaps with both ends. ”

[0009]

[Operation] The temperature detecting element configured as described above has a high negative resistance as shown by a solid curve B in FIG. 7 by including one or both of cobalt and manganese in the film resistor. By having the temperature coefficient of resistance, the resistance value in the high temperature range can be lowered and the current value can be increased, and the change amount of the resistance value in the high temperature range can be reduced.

By the way, when a resistor is formed in a film shape on an insulating substrate and the film resistor is used as a temperature detecting element, the temperature coefficient of resistance is increased and the variation in the temperature coefficient of resistance is reduced. It is necessary to reduce the film thickness of the film resistor and equalize the film thickness of the film resistor at various points. Then, when forming the film resistor and the electrode pattern for both ends thereof on the insulating substrate, first, the both electrode patterns are formed first, and then the resistor paste is screen-printed. Applying the film makes it difficult to reduce the film thickness of the film resistor because the screen used for this screen printing will float above the insulating substrate in the area between both electrode patterns. Not only does it exist, but it is not possible to make the film thickness uniform at every location.

On the other hand, according to the present invention, the insulating substrate is
First, a resistor paste is applied in a film form by screen printing and then fired to form a film resistor, and then electrode patterns for both ends of the film resistor are formed. Is formed so as to overlap with both ends of the film resistor, and when the resistor paste is applied to the insulating substrate by screen printing,
Since the screen used for this can be in close contact with the insulating substrate, the film thickness of the film resistor can be reduced and the variation in the film thickness can be reduced.

[0012]

As described above, according to the present invention, the temperature detecting element formed directly on the insulating substrate can be provided with a high negative temperature coefficient of resistance, so that the current value in the high temperature range can be increased. Can be increased to reduce the influence of noise and reduce the amount of change in resistance value in a high temperature range, so that the accuracy of temperature control for the heating resistor can be significantly improved.

Further, according to the method of forming a temperature detecting element of the present invention, the temperature detecting element in the line type heating element is
It has the effect of increasing the temperature and reducing the variation in the temperature coefficient of resistance.

[0014]

Embodiments of the present invention will be described below with reference to the drawings of FIGS. FIG. 1 shows a line type heating body 1 in which a heating resistor 3 is formed in a line on the surface of an insulating substrate 2.
Indicates. As shown in FIG. 2, this line-type heating body 1 is
With the inside upside down, with respect to the back surface of the insulating substrate 2,
Screen printing called filling a resistor paste containing one or both of cobalt and manganese in the aperture 4a of the screen 4 is overlapped with the screen 4 having the aperture 4a for resistor formation. After that, by firing, a film-shaped resistor 5 is formed as shown in FIG.

As a result, the film thickness of the membranous resistance film 5 can be reduced to the plate thickness of the screen used in the screen printing, and can be made uniform at each place. Next, as shown in FIG. 4, a screen 6 having two punched windows 6a and 6b for electrode pattern formation is overlaid on the back surface of the insulating substrate 2, and the punched windows 6a and 6b in the screen 6 are stacked.
By conducting screen printing called filling with a conductive paste such as silver paste in the inside and firing, a pair of electrode patterns 7 and 8 are formed, as shown in FIG. 5 and FIG. 8 is formed so as to partially overlap both ends of the film resistor 5.

The film resistor 5 is trimmed so that its resistance value becomes a predetermined value, and then overcoated with a protective film 9 such as glass. The film-shaped resistor 5 formed on the back surface of the insulating substrate 2 in the line-type heating element 1 contains one or both of cobalt and manganese, and thus, as shown by a solid curve B in FIG. Since it has a high temperature coefficient of resistance, the resistance value in the high temperature range becomes low and the current value becomes high, and the change amount of the resistance value in the high temperature range becomes small.

Therefore, as shown in FIG.
The power supply circuit 10 is controlled by the temperature control circuit 11 which receives the current flowing through the film resistor 5 so as to reduce the power to the heating resistor 3 when the current flowing through the film resistor 5 increases. Thus, the temperature of the heating resistor 3 can be accurately controlled with good responsiveness so as to reach a predetermined value.

[Brief description of drawings]

FIG. 1 is a perspective view of a line-type heating body.

FIG. 2 is a perspective view showing a state where a film resistor is formed on the back surface of an insulating substrate in a line-type heating body.

FIG. 3 is a perspective view showing a state where a film resistor is formed on the back surface of the insulating substrate in the line-type heating body.

FIG. 4 is a perspective view showing a state in which an electrode pattern is formed on the back surface of an insulating substrate in a line-type heating body.

FIG. 5 is a perspective view showing a state where an electrode pattern is formed on the back surface of an insulating substrate in a line-type heating body.

6 is an enlarged sectional view taken along line VI-VI of FIG.

FIG. 7 is a diagram showing a temperature coefficient of resistance of a film resistor.

[Explanation of symbols]

 1 Line type heating element 2 Insulating substrate 3 Heating resistor 4 Screen 5 Membrane resistor 7, 8 Electrode pattern

Claims (2)

[Claims] 1. A line-type heating element comprising a heating resistor formed on an insulating substrate, wherein a resistor containing one or both of cobalt and manganese is formed in a film shape on the insulating substrate. A structure of a temperature detecting element in a line-type heating body, wherein a film-shaped resistor is used as a temperature detecting element for the heating resistor. 2. A line-type heating element comprising a heating resistor formed on the surface of an insulating substrate, wherein a resistor paste containing one or both of cobalt and manganese is screen-printed on the insulating substrate. To form a film-like resistor by firing and then applying it to form a film.
A method for forming a temperature detecting element in a line-type heating element, characterized in that the electrode patterns for both ends of the film-shaped resistor are formed so that both electrode patterns overlap the both ends of the film-shaped resistor.