JPH10172732A - Constant temperature heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dispersion of a temperature of a central part of a heat radiating plate by contacting projecting parts of a metallic terminal having the projecting parts in the thickness direction with an electrode surface of a positive characteristic thermistor in a constant temperature heating element using a positive temperature coefficient thyristor in a case whose one surface is opened. SOLUTION: An elastic metallic terminal 12, a positive temperature coefficient thermistor 13 where electrodes 18 are imparted to both surfaces, a metallic terminal 14 having projecting parts 14a by embossing work in the thickness direction, an insulating sheet 15 and a heat radiating plate 16 are arranged in layers in order in a ceramic case 11 whose one surface is opened. The heat radiating plate 16 is also calked and fixed to the ceramic case 11 by a metallic band 17, and end parts of the metallic terminals 12 and 14 are derived outside. In this way, since the projecting parts 14a are arranged in the thickness direction of the metallic terminal 14, dispersion of a temperature in the central part of the heat radiating plate 16 can be reduced. Such a constant temperature heating element is used for an electronic mosquito-repellent unit or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant temperature heating element using a PTC thermistor.

[0002]

2. Description of the Related Art A positive temperature coefficient thermistor is a semiconductor ceramic having a property in which the resistance value rises rapidly when the temperature exceeds a certain temperature (Curie temperature). Therefore, when voltage is applied to this, it starts to generate heat, but when it exceeds the Curie temperature,
Its temperature rises and maintains a constant temperature. As described above, it is widely applied as a safe constant-temperature heating element that does not overheat.

[0003] Such a constant-temperature heating element is often used in electronic mosquito traps and the like. Hereinafter, a conventional constant temperature heating element will be described.

FIG. 3 shows a configuration of a conventional constant temperature heating element. That is, an elastic metal terminal 2, a positive temperature coefficient thermistor 3 having electrodes 8 provided on both sides, a metal terminal 4, an insulating sheet 5, and a heat sink 6 are sequentially stacked in a porcelain case 1 having an opening on one side. In addition, the heat sink 6 is fixed to the porcelain case 1 by caulking using a metal band 7, and the ends of both metal terminals 2 and 4 are led out.

FIG. 4 is an enlarged sectional view showing a connection state. The operation of the constant temperature heating element configured as described above will be described below.

First, when a predetermined voltage is applied to the metal terminals 2 and 4, a voltage is applied to the positive temperature coefficient thermistor 3 through the metal terminals 2 and 4, respectively, and starts to generate heat. Rise, keep constant temperature. Then, the amount of heat generated at this time heats the metal terminal 4, the insulating sheet 5, and the heat radiating plate 6, and the insecticide is volatilized from the mat set on the heat radiating plate 6 and in which the insecticide solution is permeated. Therefore, in order to volatilize a certain amount of insecticide, the thickness of the insulating sheet 5 is changed to control the amount of heat, and the temperature of the central part of the heat sink 6 is made constant.

[0007]

In the above-mentioned conventional structure, there is a problem that the temperature variation in the central portion of the heat sink 6 is large.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a constant-temperature heating element having high reliability by reducing the temperature variation at the center of the heat sink of each constant-temperature heating element.

[0009]

In order to achieve this object, a constant-temperature heating element according to the present invention is designed to improve the temperature variation in the central part of the heat sink between the constant-temperature heating elements. The projection is brought into contact with the electrode surface of the positive temperature coefficient thermistor.

[0010]

According to the first aspect of the present invention, by contacting the convex portion in the thickness direction of the metal terminal with the electrode surface of the positive temperature coefficient thermistor, the center portion of each of the constant temperature heating elements is radiated. Temperature variation can be reduced, and high reliability can be obtained.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a constant temperature heating element, and FIG. 2 is an enlarged sectional view showing a connection state.

1 and 2, an elastic metal terminal 12 is provided in a porcelain case 11 having one side open, and electrodes 1 are provided on both sides.
PTC thermistor 13 (dimensions 14
mm, a thickness of 3 mm), a metal terminal 14 having a projection 14a formed by stamping in the thickness direction, and an insulating sheet (thickness: 3 mm).
5 mm) 15 and a heat radiating plate 16 are sequentially superimposed on each other.
And the metal terminals 12 and 14 are fixed.
Is led out to the outside. The metal terminal 14 has a protrusion 14a formed by stamping in the thickness direction, and ten samples each having a height of the protrusion 14a of 0.05, 1.0, and 1.5 (mm) are manufactured. did.

The following Table 1 shows the temperature at the center of the heat radiating plate 16 of the constant temperature heating element using the sample. Further, the thickness of the insulating sheet 5 is set to 0.3 using the conventional metal terminal 4.
Ten pieces each having a size of 5, 0.40, 0.45, 0.50 (mm) were produced.

[0014]

[Table 1]

As is clear from the above (Table 1), by providing the protrusions 14a by stamping in the thickness direction of the metal terminals 14, it is possible to reduce the temperature variation at the center of the heat radiating plate 16 of each constant temperature heating element. it can.

[0016]

As described above, according to the present invention, by providing a convex portion in the thickness direction of the metal terminal, it is possible to reduce the temperature variation at the center of the heat radiating plate of each constant temperature heating element.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a constant temperature heating element according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the same.

FIG. 3 is an exploded perspective view of a conventional example.

FIG. 4 is an enlarged sectional view of a main part of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Porcelain case 12 Metal terminal 13 Positive thermistor 14 Metal terminal 14a Convex part 15 Insulating sheet 16 Heat sink 17 Metal band 18 Electrode

Claims (1)

[Claims] 1. A first metal terminal, a positive temperature coefficient thermistor having electrodes provided on both surfaces thereof, in a case having an opening on one surface,
A constant-temperature heating element in which a second metal terminal having a convex portion in a thickness direction, an insulating sheet, and a heat sink are sequentially stacked, and the convex portion of the metal terminal is brought into contact with an electrode surface of a positive temperature coefficient thermistor.