JPH0531277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the configuration of a heating element useful as a heating appliance, a general heating device, and the like.

Conventional technology A conventional heating element having a positive temperature coefficient of resistance (hereinafter referred to as PTC) is disclosed in Japanese Patent Publication No. 57-43995 and Japanese Patent Publication No. 55-40161, for example.
The structure was as shown in Figure 5.

That is, a pair of band-shaped electrodes 2 facing each other are provided on an insulating substrate 1, and a PTC heating resistor 3 is provided from above, and the temperature is self-controlled to an appropriate level by the PTC characteristics of this PTC resistor 3. It was something that would be done.

Problems to be Solved by the Invention However, with this configuration, especially
When the PTC heating element 3 has a high calorific value, the temperature distribution becomes abnormally uneven, and not only do abnormally high temperature parts and parts that hardly generate heat occur, but the abnormally high temperature parts have the risk of smoke and ignition phenomena. There was a problem.

This is due to the following phenomenon.

Now, if a voltage is applied to this heating element to energize it, theoretically, as shown by the solid line a in Figure 6, the heat generation temperature will be almost uniform in the three parts of the PTC heating element, for example, as shown in Figure 7. It is self-controlled to a certain temperature due to PTC characteristics such as However, this
Due to non-uniformity in the resistance distribution of the PTC heating element 3, partial differences in the insulation state from the outside, local heating from the outside, etc., the resistance distribution in the direction between the pair of electrodes becomes slightly non-uniform, and the resistance value becomes relatively When a large part A occurs, the voltage applied to part A increases,
Part A generates a larger amount of heat than other parts, and a temperature distribution as shown by the broken line b in FIG. 6 occurs. Along with this, the resistance value of section A becomes even higher due to the PTC characteristics, the voltage applied to section A becomes even greater, and the temperature of section A becomes even higher. In this way, a high temperature heat generation point A is finally formed as shown in FIG. The calorific value distribution in the direction between the pair of electrodes 2 at this time is shown in FIG. In this way, once a temperature distribution occurs even slightly, the PTC
The characteristics encourage and increase the temperature difference. In the following explanation, this phenomenon will be referred to as a voltage concentration phenomenon.

This voltage concentration phenomenon is more likely to occur as the amount of heat generated is higher, and conventional PTC heating elements 3 are designed to prevent this by limiting the amount of heat generated or by using an insulating substrate 1 with very good thermal conductivity. We had to deal with the voltage concentration phenomenon.

By the way, a resistor with excellent thermal conductivity, that is,
If a ceramic resistor element made of barium titanate or the like is used, the limit on the amount of heat generated to suppress this voltage concentration phenomenon can be considerably increased. However, the size and shape of this resistor must be considerably restricted in terms of processability, and for heating large areas, a large number of small elements must be installed, and power supply connections, etc. Not only is this complicated, but it also lacks flexibility, is easily broken, and is difficult to thermally bond to a heat sink, etc., which is a major problem in that it is practically impractical in the field of industrial application of the present invention.

Under these circumstances, PTC, whose main component is a composition in which conductive particles are dispersed in a crystalline polymer, is a heating element that does not cause voltage concentration phenomenon even with a high calorific value and has excellent workability. Using a resistor,
It may be possible to reduce the temperature distribution by appropriately reducing the distance between the pair of electrodes, but in the configuration shown in Figure 5, the area occupied by electrode 2 becomes large, and the area occupied by the PTC resistor part becomes strip-like. Electrode 2
Even if the width is made narrower, it becomes very small and it is difficult to obtain a high calorific value, and there is also a large amount of material loss. Further, even if an expensive material with very good thermal conductivity is used for the insulating substrate 1, it is not very effective. Therefore, it is assumed that all of the above problems can be solved by configuring a pair of electrodes on both sides of the PTC resistor in the form of a thin plate with an appropriate thickness, but the major problem here is that This is a method of feeding power to electrodes configured on both sides. For example, if a heat load body such as a heat radiator is thermally coupled to the first electrode side, there is no way to remove the heat radiator of the power supply part to the electrode by cutting out, drilling, or shifting it. Although it is easy to think of this, when using it for various devices, etc.
Not only does the power supply structure become complicated, but when mechanical force such as tension or pressure of the power supply conductor is applied to the connection terminal portion of the power supply section, this force is absorbed only by the connection terminal portion. This is extremely dangerous, as it may lead to abnormal overheating, ignition, etc. due to poor conduction of the connecting terminal and increased electrical contact resistance. Further, the heat radiator is often made of a conductive material such as metal, and in this case, the removed area of the heat radiator cannot be made very small from the viewpoint of safety such as electric leakage.

Therefore, the present invention solves the above-mentioned conventional problems by providing an extremely simple and highly reliable power supply structure, and realizing a safe heating element that does not cause the voltage concentration phenomenon and can generate a high amount of heat. It is something that makes you

Means for solving the problem A thin plate-shaped strip-shaped resistor with a positive temperature coefficient of resistance, whose main component is a composition in which conductive particles are dispersed in a crystalline polymer, and a strip-shaped resistor provided on both sides of the resistor. comprising first and second strip-shaped electrodes, a power supply connection terminal, and an insulating film that covers the electrodes, a resistor, and the connection terminal, and one of the first and second electrodes is connected to a resistor. The first and second electrodes and the resistor are arranged in the longitudinal direction while being shifted in the width direction of the strip shape so as to protrude without overlapping with respect to the body and the other electrode, and the connecting terminal is attached to the protruding portion. This configuration is made up of:

Effect: At least one electrode has a
There is a part that protrudes outside the PTC resistor, and if a connection terminal for power supply is provided in this part, power can be supplied in the same direction to this heating element, and all of the above problems will be solved. It is possible to realize a heating element that is safe, highly reliable, and has excellent workability in terms of calorific value.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. Incidentally, for the sake of simplicity, the same numbers are given to the same types of parts in each embodiment of the present invention. Further, in order to clarify the usage example of the heat generating element of the present invention, the explanation will be continued with an example in which the heat sink 4 and the insulating film 5 are used as the heat load bodies of the heat generating element.

In FIG. 1, 6 and 7 are first and second electrodes, and a thin plate-shaped PTC resistor 8 is arranged between the electrodes 6 and 7 so as to be electrically conductive. In this example, a protruding portion A is provided that protrudes from the PTC anti-antibody 6 and the other electrode 7 so as not to polymerize. By making a power supply connection between this protruding portion A and an arbitrary position of the electrode 7, it is possible to supply power in the same direction to this heating element, and the construction of various heat load bodies can be extremely simplified.

In the embodiment shown in FIG. 2, the heating element of the present invention is thermally coupled to the heat dissipation plate 4 and the insulating film 5, but similarly to the above, the electrode 6 is provided with a protruding portion A, and this portion serves as a lead. By connecting the wires 9, power can be supplied to the heating element in the same direction.
This eliminates the need to cut out, make holes in, or shift the heat sink 4 and the like. Also,
Since this connection part can be easily held by the heat sink 4 and the insulating film 5, even if mechanical force such as pulling or pressing is applied to the lead wire connection part, the connection part may break or abnormal heat may overheat due to contact resistance. It has the excellent feature of being extremely safe, as it can prevent ignition and abnormal overheating and ignition due to electrode disconnection.

In addition, the lower part of the electrode 7 in FIG.
0 is connected, but this may cause material and mechanical damage to the PTC resistor 8 that occurs when the temperature becomes high as in the case of soldering connections, or when the connection point is pressed, etc. Abnormal overheating and ignition due to this can be prevented.

In addition, as shown in FIG. 3, the PTC anti-antibody 8 is
Alternatively, it may be more prominent than 7. Also,
The PTC anti-antibody 8 and the electrodes 6 and 7 are band-shaped, and at least one of the electrodes is shifted in the width direction, so it is very easy to shape these components. Processing to integrate the strip shape in the longitudinal direction can be easily performed, and no material loss occurs. In addition, the power supply connection terminal also has the effect of being able to be placed at any position in the longitudinal direction in accordance with the configuration of various devices.

Furthermore, considering the actual usage configuration, an insulating film 11 or the like is often pasted on the electrode 7 side as shown in FIG. They are thermally bonded via 5. In this configuration, the temperature on the electrode 7 side is often higher than that on the heat sink 4 side due to thermal diffusion of the heat sink 4, and this tendency is further exacerbated by the PTC characteristics of the PTC anti-antibody 8. Due to the heat conduction of 7 itself to the heat dissipation plate 4, the temperature distribution in the direction between the electrodes 6 and 7 can be made more uniform, and the thermal efficiency is also improved.

By the way, PTC anti-antibody 8 is a polymer composition containing a particulate conductive agent mainly composed of carbon black, and examples of the resin used for this include polyethylene-vinyl acetate copolymer and polyethylene-ethyl acrylate copolymer. ,polyethylene,
There are crystalline resins such as polyolefins such as polypropylene, polyamides, polyvinylidene halides, and polyesters, and each exhibits a sharp positive temperature coefficient near its crystal transformation point. Also, a pair of electrodes 6, 7
The distance is about 0.3 to 3 mm, and the PTC anti-antibody 8 may be a composition with high specific resistance, and the PTC characteristics for self-temperature control can be easily obtained.

Next, as the electrodes 6 and 7, copper foil with a thickness of 35 μm was used in this embodiment, but any material may be used as long as it is a conductor.

Further, in this embodiment, the heat radiating body 4 is used as the heat load body of the heat generating body, but the same effect can be achieved using any heat load body that radiates or receives heat.

Effects of the Invention As described above, the heating element of the present invention provides the following effects.

(1) Since the electrode has a protruding part, when connecting it to various heat loads, it is possible to supply power very easily without having to perform complicated processing such as removing the heat load, and it is highly reliable. A high power supply structure is possible.

(2) Since the power supply structure can be reliably processed in areas where the electrodes and resistors do not overlap, there are fewer protrusions caused by the power supply connection, and the electrodes and resistors can be sealed and covered with an insulating film, allowing the resistor to be thin-walled. Not only can we achieve a configuration that is safe and capable of generating a high amount of heat evenly and does not cause voltage concentration phenomena, but it also improves electrical insulation and the ability to block oxygen, etc. from electrodes and resistors, further increasing reliability. be able to.

(3) The above effects can be achieved with an extremely simple processing configuration in which the electrodes and the resistor are shifted in position, which is extremely advantageous in practice.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a heating element according to a first embodiment of the invention, FIG. 2 is a perspective view of a heating element according to a second embodiment of the invention, and FIG. 3 is a perspective view of a heating element according to a second embodiment of the invention. FIG. 4 is a sectional view of a heating element according to a fourth embodiment of the present invention, FIG. 5 is a plan view of a conventional heating element, and FIG.
The figure is a heat generation temperature distribution diagram of the heating element, Figure 7 is a PTC characteristic diagram of the heating element, Figure 8 is a schematic diagram of the voltage concentration phenomenon occurring in the heating element, and Figure 9 is when the voltage concentration phenomenon occurs. It is a calorific value distribution map. 4... Heat sink, 5, 11... Insulating film,
6, 7...electrode, 8...PTC resistor.

Claims (1)

[Claims] 1. A thin plate-shaped strip-shaped resistor having a positive temperature coefficient of resistance, the main component of which is a composition in which conductive fine particles are dispersed in a crystalline polymer, and a first resistor provided on both sides of the resistor. A second strip-shaped electrode, a power supply connection terminal, and an insulating film that covers the electrode, a resistor, and the connection terminal, and one of the first and second electrodes is connected to the resistor and the other. The first and second electrodes and the resistor are arranged in the longitudinal direction while being shifted in the width direction of the band shape so as to protrude from the electrodes without overlapping, and the connecting terminal is disposed in the protruding portion. A heating element.