JPH0140461B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a thermosensitive heating element.

Conventionally, in electric heating devices such as electric carpets, negative temperature -
Temperature detection electrodes 2 are stretched on one side of a thermosensitive resin surface material 1 made of a polyamide-based material having impedance characteristics, and a heating line 3 is stretched on the other side.
Both sides of this thermosensitive resin surface material 1 are covered with insulating films 4, 4.
The temperature of the heat-sensitive sheet heating element 5 coated with is controlled by, for example, a temperature control circuit as shown in FIG. 3 in the following manner.

That is, the heating line 3 of the heat-sensitive sheet heating element 5
A power supply 8 is connected to the power supply through the normally open contact 7a of the power supply relay 7, and the oscillation circuit 10 is operated with the output voltage V _D of the power supply circuit 9 that converts the power supply 8 into a constant voltage DC power supply. The high frequency voltage V outputted from the circuit is divided by a voltage dividing capacitor 11 and applied between the temperature detection electrode 2 and the heating line 3 of the heat-sensitive sheet heating element 5, and the voltage is applied to the impedance of the heat-sensitive sheet heating element 5. Filter circuit 12 for voltage signal
The detected value is input to the comparison circuit 14 that constitutes the front stage of the next stage switching circuit 13, and the reference voltage of this comparison circuit 14 is compared with the electrical detection value. When the voltage falls below this reference voltage, this comparator circuit 14 inverts the transistor 15 constituting the latter stage of the switching circuit 13, which had been kept in the on state within the safe temperature range, to the off state, and connects the transistor 15 in series. The excitation coil of the power supply relay 7 stops driving, and the normally open contact 7a connected between the power source 8 and the heating line 3 is reversed from the on state to the off state, and the power supply to the heater circuit is stopped. It was designed to cut off the road.

However, in the structure of the heat-sensitive sheet heating element 5, if foreign matter 6 such as iron powder or carbon particles is mixed into the layer during extrusion molding of the heat-sensitive resin face material 1, the thickness of the heat-sensitive resin face material 1 may be reduced. Since the foreign material 6 is thin, usually about 40 to 100 μm, the heat generating line 3 and the temperature detection electrode 2 are short-circuited by this foreign object 6, as shown in FIG.
The impedance detected between the temperature detection electrode 2 and the heating line 3 does not indicate the impedance of the thermosensitive resin surface material 1, which poses a problem in that temperature control is hindered.

In order to avoid such inconveniences, it is necessary to use a material with sufficient thickness as the thermosensitive resin facing material 1 in advance, so that even if foreign matter 6 is mixed into the layer of the thermosensitive resin facing material 1, the presence of the foreign matter 6 will cause heat generation. It is necessary to prevent a short circuit from occurring between the line 3 and the temperature detection electrode 2, but on the other hand, when this is applied to an electric carpet, etc., it is necessary to have appropriate flexibility. However, there is a limit to the method of increasing the thickness of the thermosensitive resin surface material 1 as described above, and there is a drawback that a large amount of material is required.

Therefore, an object of the present invention is to provide a heat-sensitive heating element that can prevent short circuits due to foreign matter between the heat-generating line and the temperature detection electrode without increasing the thickness of the heat-sensitive resin material. .

An embodiment of this invention is shown in FIGS. 5 and 6. That is, this heat-sensitive heating element is an example applied to a planar heat-sensitive element 5', and a heat-generating line 3' made of aluminum foil or the like is disposed on one side of a heat-sensitive resin surface material 1' that exhibits negative temperature-impedance characteristics. At the same time, a temperature detection electrode 2' made of a conductive material such as aluminum foil is also arranged in parallel on the same surface of this thermosensitive resin surface material 1' with a predetermined interval between it and the heating line 3'. , a plurality of auxiliary conductive plates 16 made of a conductive material such as aluminum foil are distributed and stretched over the entire other surface of the thermosensitive resin surface material 1', and further, both surfaces of the thermosensitive resin surface material 1' are stretched. It is covered with insulating films 4', 4'.

This planar heat-sensitive heating element 5' has both terminals 3'a,
A power source is applied between terminals 3'a and 3'a to generate heat, and between the terminal 2'a of the temperature detection electrode 2' facing the edge of the thermosensitive resin surface material 1' and the terminal 3'a of the heating line 3'. By applying a high-frequency voltage using the circuit configuration shown in Figure 3 above, the impedance of the thermosensitive resin surface material 1' between both terminals 2'a and 3'a is detected, and the temperature is controlled accordingly. That's what I do.

With this configuration, due to the presence of a plurality of auxiliary conductive plates 16 distributed and stretched on one side of the thermosensitive resin surface material 1', no voltage is applied between the heating line 3' and the temperature detection electrode 2'. A voltage is applied between the temperature detection electrode 2' and the auxiliary conductive plate 16 facing the temperature detection electrode 2', and between the auxiliary conductive plate 16 and the heating line 3' facing the auxiliary conductive plate 16, respectively. A partial voltage electric field path P as shown by the imaginary lines in FIG. Due to foreign matter 6 such as powder particles,
For example, even if there is a short circuit between the heat generating line 3' and the auxiliary conductive plate 16, or between the temperature detection electrode 2' and the auxiliary conductive plate 16, there will be no short circuit between the heat generating line 3' and the temperature detection electrode 2'. Moreover, even if a plurality of foreign substances 6 are mixed in, the occurrence of the short circuit can be greatly suppressed because the auxiliary conductive plates 16 are arranged in a dispersed manner. There is no need to increase the thickness, and flexibility is not inhibited.

Further, as shown in FIG. 8, if the thickness of the thermosensitive resin surface material 1' is t, then the partial voltage electric field path P applied between the heating line 3' and the temperature detection electrode 2' is as follows:
This results in an impedance equivalent to that obtained by interposing a heat-sensitive resin face material 1' with a thickness of 2t, and in order to provide the same impedance as in the conventional structure shown in FIG. While it is necessary to use the face material 1, in this embodiment, the heat-sensitive resin face material 1', which is half the thickness, is used between the heat generating line 3' and the temperature detection electrode 2' without any problem in terms of temperature detection accuracy. Sufficient impedance can be provided.

Furthermore, as the heat generating line 3' is heated, the impedance of the area near the heat generating line 3' of the thermosensitive resin surface material 1' decreases before that of other areas; Since the structure in which the heating line 3 and the temperature detection electrode 2 are arranged opposite to each other in the thickness direction of the thermosensitive resin surface material 1 with the thermosensitive resin surface material 1 in between, as shown in FIG. Impedance does not change sufficiently in the area near the temperature detection electrode 2', and temperature control is performed in response to a local temperature rise before the temperature of the entire area of the thermosensitive resin surface material 1' has risen sufficiently. Uniform temperature control can be performed over the entire area without causing any turbulence.

Moreover, since the heat generating line 3' and the temperature detection electrode 2' are arranged side by side on the same surface of the thermosensitive resin surface material 1', the heat generating line 3' can be removed by etching.
And when forming the temperature detection electrode 2', the area where the conductive surface material such as aluminum foil is eluted is reduced accordingly, the etching process can be carried out in a short time, and the efficiency of use of the conductive surface material is improved. .

By dispersing the heating line 3' and the temperature detection electrode 2' which are arranged in parallel densely on the surface of the thermosensitive resin surface material 1', they act as a reinforcing material for the thermosensitive heating element. It is also possible to improve the strength.

Another embodiment of the invention is shown in FIG. That is, this heat-sensitive heating element has a cord-shaped heat-sensitive heating element 5'' instead of the above-mentioned embodiment in which the overall structure is planar.
In this example, a heat-generating line 3'' and a temperature detection electrode 2'' each formed in a band shape are arranged and wound spirally on the outer peripheral surface of a tube-shaped thermosensitive resin material 1'', and the tube-shaped thermosensitive resin material 1'' is A plurality of auxiliary conductive wires 16' are distributed and arranged around the central axis of the material 1'',
After that, the outer periphery of the heat-sensitive resin material 1'' is covered with an insulating material 4'', and a power supply is applied between both terminals of the heating line 3'', and a high frequency signal is applied between the heating line 3'' and the temperature detection electrode 2''. The usage example of applying a voltage and detecting the change in impedance of the thermosensitive resin material 1'' is the same as in the previous embodiment.

With this configuration, the auxiliary conductive wires 16'...
acts in the same way as the auxiliary conductive plate 16 in the case of the embodiment described above, and a plurality of distributed partial voltage electric field paths are provided between the heat generating line 3'' and the temperature detection electrode 2''. The same effect as in the example can be achieved.

As described above, the heat-sensitive heating element of the present invention includes a heat-sensitive resin material, a heat-generating line arranged on one side of the heat-sensitive resin material, and a heat-generating line arranged parallel to and separated from the heat-generating line on one side of the thermosensitive resin material. a temperature detection electrode that detects an impedance change in the thermosensitive resin material between the heat generating line and the temperature detection electrode, which is distributed on the other surface of the thermosensitive resin material and interposed with the heat sensitive resin material; Since it is equipped with a plurality of auxiliary conductive materials that provide a good conductive path in the area, the auxiliary conductive material is interposed so that a portion of the heat-sensitive resin material layer between the heating line and the temperature detection electrode is connected via the auxiliary conductive material. It is possible to form a piezoelectric field path in a dispersed manner, and it is possible to avoid short circuits between the heating line and the temperature detection electrode due to the contamination of foreign matter, and the impedance of the thermosensitive resin material between the heating line and the temperature detection electrode is also sufficiently large. It has the effect of being able to perform highly accurate temperature control without impairing flexibility.

[Brief explanation of drawings]

1 and 2 are respectively a perspective view and a sectional view of a conventional example, FIG. 3 is a temperature control circuit diagram of a heat-sensitive heating element of the conventional example, FIG. 4 is an explanatory diagram showing the drawbacks of the conventional example, and FIG. FIG. 6 is a partially cutaway plan view and a cross-sectional view showing an embodiment of the present invention, respectively;
7 and 8 are explanatory diagrams of its operation, FIG. 9 is a sectional view of a main part of a conventional example, and FIG. 10 is a perspective view showing another embodiment of the present invention. 1'...Thermosensitive resin surface material, 1''...Thermosensitive resin material,
2', 2''...Temperature detection electrode, 3', 3''...Heating line, 4'...Insulating film, 4''...Insulating material, 5',
5″...Thermal heating element, 16...Auxiliary conductive plate, 1
6'...Auxiliary conductive wire.

Claims (1)

[Claims] 1. Detecting the impedance change of the thermosensitive resin material between the thermosensitive resin material, the heat generating line arranged on one side of the thermosensitive resin material, and the heat generating line arranged in parallel with the heat generating line on one side of the thermosensitive resin material. and a plurality of auxiliary conductors distributed on the other surface of the thermosensitive resin material to provide a good conductive path in a partial area between the heat generating line and the temperature detection electrode with the thermosensitive resin material interposed therebetween. A heat-sensitive heating element with a material.