JPS61101990A - Wide area temperature detection sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an improvement in a wide-area temperature detection sensor for controlling the temperature of a wide-area heating element such as an electric carpet or an electric blanket.

(Background Art) Conventionally, temperature control of wide area heating elements such as electric carpets and electric blankets requires the use of wide area temperature detection sensors. The reason for this is that when using a thermostat or chip-shaped thermistor, if a part of the part away from the installation location is partially insulated, the temperature in that part will become abnormally high, creating a dangerous situation. In order to prevent this, it is possible to increase the number of thermostats, but since it is necessary to use a considerable number of thermostats, it is necessary to use heat-sensitive sheet heating elements or heat-sensitive heating wires as shown in Figures 1 and 2. etc. are used.

In Fig. 1, l is a thermosensitive resin film, 2 is a heating wire, and 3 is a heat-sensitive resin film.
2 is a temperature sensing line, 4 is an insulating film, 6 is a multi-segmented reflective electrode, and in Fig. 2, 1' is a thermosensitive resin layer, 2 is a heating element, 3 is a temperature sensing line, 4' is an insulating layer, and 7' is a Show the core.

Modified resins such as polyamide resins and polyvinyl chloride are usually used as thermosensitive resins for these temperature detection sensors as plastic thermistors. Temperature of those thermosensitive resins -
Figure 3 shows the impedance change rate characteristics.

Next, the operation of this wide area temperature detection sensor will be explained with reference to a conventional example.

In an example applied to an electric carpet (size 2 tatami mats), the uniform temperature over the entire surface of the dial is normally designed to be 506C (indicated by a, b, and b in Figure 3). However, when considering the actual usage conditions of electric car vents, it is conceivable that, for example, only one cushion may be placed on the surface when the dial is set to high.

In this case, since the temperature of the cushion part is insulated, it will be slightly higher than the temperature set on the high uniform dial (ie, 50°C). The reason for this is that the wide-area temperature sensor detects a uniform temperature over the entire surface (a,
This is because it is used in a temperature control circuit that turns on when it reaches a value equivalent to the impedance value corresponding to , b, ). In a partially insulated state, as the temperature of the insulated part increases, the impedance decreases only in that part, but as the on-off operation is repeated, the partial insulation and other impedances decrease. Maximum temperature at the point where heat dissipation maintains a balance (shown in Figure 3 a, , b2)
l is decided.

Figure 3 shows one 50 crn square cushion in a room with a room temperature of 15°C.
The highest temperature (a2. b2) and the temperature of the uninsulated part (a
, , b, ) and the uniform temperature across the entire surface (a, , bl) are plotted on the thermistor characteristics.

By the way, reducing this maximum temperature is especially important in preventing low-temperature burns, ensuring safety when used in conjunction with other heating appliances (e.g. kotatsu), and selling products under product names such as Styro Tatami, which have become popular recently. Foamed materials with low heat resistance and heat deformation temperature are now required to prevent deformation of flooring materials.

Possible means to meet this requirement include increasing the thermistor constant (so-called B constant) of the thermosensitive resin material, especially on the high temperature side, and controlling the detection area by dividing it into smaller areas. Reasons include the fact that the B constant will not increase beyond a certain limit even if a larger amount of additive is added than necessary, and the latter will complicate the lead wire V junction and complicate the temperature control circuit. It was difficult to realize this.

(Object of the Invention) The present invention was proposed to improve the above-mentioned drawbacks, and it is possible to detect the partial overheating temperature that occurs when only a part of the wide heating element is insulated at a low temperature. The purpose is to

(Disclosure of the Invention) The present invention has been obtained as a result of studies focusing on sensor configurations exhibiting conventional sensor characteristics to satisfy this requirement.

In other words, we focused on the fact that when using resin A and resin B, even if they are the same conventional example (see FIG. 3), resin A has a lower maximum temperature. The difference between this person and B is the maximum temperature setting (a
, , bl) to the low temperature side (
This is because the difference in B constant) has a large influence.

Therefore, the present invention was obtained as a result of investigating whether there is a method for stably detecting the thermistor characteristics at a temperature lower than the maximum temperature setting by reducing the B constant without using a heat-sensitive material.

In order to reduce the thermistor constant at a lower temperature than the maximum set temperature, a certain amount of current flows through the insulating film layer at low temperatures, and at high temperatures the current flowing through the insulating film layer is ignored by the detected value of the sensor characteristics. It turns out that it is best to choose constituent materials that are small.

Next, an example will be described.

FIG. 4 shows a first embodiment of the present invention, in which 1 is a thermosensitive resin film, 2 is a heating line, 3 is a temperature detection line, and 4 and 5 are insulating films.

This structure differs from the conventional example shown in FIG. 1 in that the multi-segment reflective electrode of the heat-sensitive sheet heating element is eliminated. In this way, the absolute value of the impedance of the thermosensitive resin film 1 becomes sharper than before, and since the current flowing through the insulating film 5 affects the detected value on the low temperature side, the B constant on the low temperature side becomes small. The B constant on the low temperature side can be determined arbitrarily by %, mainly depending on the gap size between the heating line 2 and the temperature detection line 3, the insulation film material, and the float.
It can be divided.

FIG. 5 shows a second embodiment of the present invention, in which l is a thermosensitive resin film, 2 is a heating line, 3 is a temperature detection line, 4' is a low specific impedance insulating film, and 6 is a multi-division reflection film. Shows electrodes. In this embodiment, the insulating film of the conventional heat-sensitive sheet heating element is replaced with a material having a lower specific impedance. For example, polyethylene resin in which carbon particles such as acetylene black are dispersed is suitable. In this case, the B constant on the low temperature side can be adjusted by adjusting the amount of carbon added.

FIG. 6 shows a third embodiment of the present invention, in which numeral 7 indicates an aluminum vapor-deposited film.

A highly conductive film such as an aluminum vapor-deposited film is pasted on the outside of the insulating film of a conventional heat-sensitive sheet heating element. In this case, the B constant can be adjusted by adjusting the material and thickness of the insulating film and the conductivity of the deposited film.

Next, a fourth embodiment will be described. Example 1 (Figure 4)
Similarly, the absolute value of the impedance is increased by winding two heating wires and two temperature sensing wires in parallel on the same surface.

Next, a fifth embodiment will be described. The conventional example shown in FIG. 2 is wound so that the facing area of the heating wire and the temperature sensing wire is reduced.

Next, an experimental example will be explained.

The structure shown in Fig. 4 is used, and the planar heating element is constructed.
Thermal resin film thickness 60 microns, heating line (aluminum foil,
20μ thickness, line width 5 words), temperature detection line (aluminum foil, 20
Figure 7 shows the characteristic values when configured with μ thickness, line width (3 words), insulating film (polyethylene 100 microns, polyester 50 microns), gap between lines 2 gB, dimensions 6 om x 90ffi. This figure is at room temperature 15°
This shows the results of a test in room C with a 50 crn square cushion placed on it, and it can be seen that the maximum temperature is lower than in Figure 3.

As described above, the feature of the present invention is that B
The purpose is to make the constant small so that in a high temperature range, due to the characteristics of the negative temperature thermistor, the current flowing through parts other than the thermosensitive resin film becomes negligible.

In the explanation, the term "current flowing through the insulating film" is used, but although accurate analysis is not possible, it is thought that the surface current of the insulating film, the current flowing through the adhesive layer between the layers, etc. also contribute to the success of the present invention.

(Effects of the Invention) As described above, the present invention is configured such that the thermistor detection characteristics in the uniform temperature setting region over the entire surface of the thermosensitive resin material are detected in the direction in which the thermistor constant becomes smaller, and the high temperature region is almost the same as that of the thermosensitive resin material. By using a sensor configuration that depends only on the characteristics of the material, the maximum temperature can be reduced even if a heat-insulating part occurs in a part of the heat-sensitive sheet heating element, and partial overheating can be detected at a low temperature. It has the potential to be effective.

[Brief explanation of the drawing]

Figures 1 and 2 show conventional thermosensitive resin heating elements;
The figure shows the characteristics of the thermosensitive resin, FIG. 4 shows one embodiment of the thermosensitive resin sensor of the present invention, FIGS. 5 and 6 show other embodiments, and FIG. 7 shows the characteristics of the temperature detection sensor of the present invention.

Claims (3)

[Claims] (1) A heating line made of metal foil and a temperature sensing line are arranged almost in parallel on the same plane, and a thermosensitive resin film with negative characteristics is provided so as to be in contact with both the heating line and the temperature sensing line. In a product in which an insulating film is attached from both sides, the thermistor detection characteristics in the uniform temperature setting area over the entire surface of the thermosensitive resin material are configured so that detection is performed in the direction where the thermistor constant becomes smaller, and the high temperature area is almost the same as the thermosensitive resin material. A wide area temperature detection sensor characterized by a sensor configuration that depends only on the characteristics of the material. (2) The wide-area temperature detection sensor according to claim 1, characterized in that the insulating film disposed on the outside is made of a material with low intrinsic impedance. (3) The wide area temperature detection sensor according to claim 1, characterized in that an aluminum vapor-deposited film is provided on at least one side outside the insulating film.