JPH0410374A - Flat exothermic body - Google Patents

Abstract

PURPOSE:To improve the safety of a flat exothermic body by so positioning a conductive ribbon near a conductive elastomer layer as to cover the entire surface thereof, and shutting off an electrode from a power supply when the abnormal heat generation of the conductive elastomer layer is detected from a change in the resistance of the conductive ribbon. CONSTITUTION:Upon occurrence of local heat generation in the conductive elastomer layer 11 of a flat exothermic body 10A, the conductive ribbon R11 of a breaking device 10B covering the entire surface of the layer 11 gives an excessive increase in resistance. At the same time, voltage at the non-reversible input end of an operation amplifier OP becomes lower than voltage at a reversible input end, and a low level output signal appears at the output end of the amplifier OP. Voltage, therefore, drops between the base and emitter of a transistor TR, and a non-conductive state appears between the base and emitter. Consequently, an exciting coil Ry is turned to non-excitation state and a relay contact ry is opened, thereby interrupting power supply from an AC power supply E to the electrodes 12 and 13 of the flat exothermic body 10A. According to the aforesaid construction, the safety of the exothermic body 10A can be improved.

Description

Detailed Description of the Invention (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a planar heating element in which electrode force is applied to a conductive elastomer layer. The change in resistance of a conductive ribbon placed so as to cover the entire surface of the nearby area is monitored, and when a change in resistance of the conductive ribbon due to abnormal heat generation of the conductive elastomer layer is detected, the electrode is removed. This relates to a planar heating element that is cut off from the power supply (power source).

[Prior Art] Conventionally, this type of planar heating element has been equipped with a thermostat and a small number of temperature fuses near the conductive elastomer layer to prevent abnormal heat generation in the conductive elastomer layer. It has been proposed that the electrode be disconnected from the power supply when it is detected.

[Problems to be solved] However, with conventional planar heating elements, it was impossible to identify in advance the location where abnormal heat generation occurs.
In order to reliably detect the conductive elastomer layer, there is a disadvantage that a temperature fuse or thermostat must be placed over the entire surface of the conductive elastomer layer, resulting in (11) flexibility of the conductive elastomer layer. There was a drawback that it hindered the

Therefore, in order to eliminate these drawbacks, the present invention provides a conductive ribbon in the vicinity of the conductive elastomer layer so as to cover the entire surface of the conductive elastomer layer. It is an object of the present invention to provide a planar heating element whose electrodes are cut off from the power supply when abnormal heat generation is detected.

(2) Structure of the invention [Means for solving the problems] The means for solving the problems provided by the present invention is as follows: “In a planar heating element in which electrodes are arranged on a conductive elastomer layer, (all conductive The conductive ribbon (R++l) is arranged in a class 8 frame and the resistance changes according to the heat generation in the conductive elastomer layer (11), and (b) the conductive ribbon (R. and (c) monitoring results from the monitoring means (OP, RIa, R-8R2□). When abnormal heat generation is found in the conductive elastomer layer (11), a disconnection means (for disconnecting the electrodes (12, 131) from the power supply is installed).
TR; Ry+ry:R. , F).

[Function] The sheet heating element according to the present invention is a sheet heating element in which electrodes are arranged on a conductive elastomer layer, and in particular, (
a) A conductive ribbon which is disposed near the conductive elastomer layer and whose resistance changes according to heat generation in the conductive elastomer layer; It comprises a monitoring means for monitoring resistance changes, and a cutoff means for cutting off the electrode from the power supply when abnormal heat generation is found in the conductive elastomer layer from the monitoring results by the CL monitoring means. (1) It has the effect of making it possible to detect even local abnormal heat generation over the entire surface of the conductive elastomer layer, and 1ii) While avoiding inhibiting the flexibility of the conductive elastomer layer, It functions to reliably detect abnormal heat generation, and as a result (iii) it functions to improve safety.

[Example] Next, the planar heating element according to the present invention will be specifically described with reference to the accompanying drawings, citing preferred examples thereof.

However, the examples described below are described to facilitate or accelerate understanding of the present invention, and are not described to limit the present invention.

In other words, each element disclosed in the embodiments described below includes all design changes and equivalent substitutions that fall within the spirit and technical scope of the present invention.

(El,・!day) FIG. 1 is a configuration diagram showing a first embodiment of a planar heating element according to the present invention.

FIG. 2 is an exploded perspective view showing a part of the embodiment shown in FIG. 1 in an enlarged manner.

FIG. 3 is a configuration diagram showing a second embodiment of the planar heating element according to the present invention.

First, the structure of a first embodiment of a planar heating element according to the present invention will be described in detail with reference to FIGS. 1 and 2.

This is a planar heating element according to the present invention, which is attached to the back of the planar heating element main body and to the back of the planar heating element main body, and when heat generation occurs at the back of the planar heating element main body. A cutoff device is provided to detect this and cut off the power supply from the alternating current BE to the back of the planar heating element main body.

A conductive elastomer layer 11 is formed on at least one surface of a known cloth base material (not shown) in a well-known manner at the back of the main body of the sheet heating element.
is formed, and a plurality (in this case, two) of electrodes 12.13 are arranged on the surface of the conductive elastomer layer 11 in a well-known manner. Electrode 1213 is connected to AC power source E.

The back of the planar heating element main body is further provided with an insulating film 14.15 in order to prevent the conductive elastomer layer 11 and the electrodes 12.13 from coming into contact with surrounding members.

The insulation film 16 is designed to cover the entire surface of the conductive elastomer layer 11 near the back of the sheet heating element body.
The conductive ribbon R++ is connected in series with the conductive ribbon R++, which is disposed through the conductive ribbon R++ and has a positive temperature characteristic or negative temperature characteristic c (hereinafter referred to as "positive temperature characteristic" below), and the conductive ribbon RI+. The non-inverting input end is connected to the variable resistor R+z for adjusting the voltage at the connection point with the conductive ribbon RI+, and the connection point between the conductive ribbon RI+ and the variable resistor R1□, and the inverting input end is Fixed resistance R2
and a transistor TR whose base is connected to the output terminal of the operational amplifier OP via a resistor R3, and a transistor TR connected in series to the collector of the transistor TR. and a relay contact r disposed between the electrode 12.13 at the back of the planar heating element body and the AC power source E and opened by the relay coil R1. It is preferable that the conductive ribbon R11 has a resistance that changes within the range of 10 to I(l[lkΩ). Here, the positive temperature characteristic refers to the characteristic that the resistance increases as the temperature rises. refers to the characteristic that resistance decreases as temperature rises.

The interrupting device 10B also connects the DC voltage to the conductive ribbon R by means of a rectifier REC connected to the AC power supply E.
1+ and a series circuit of variable resistor R12 and fixed resistor Ra+
It is applied to a series circuit of variable resistor R2H, a relay coil R, and a series circuit of transistor TR, and is further applied to the base of transistor TR via resistors R4 and Rs.

Further, with reference to FIGS. 1 and 2, the first embodiment of the planar heating element according to the present invention will be described.

Its action will be explained in detail.

The one-plate rectifier REC is connected to the AC power supply E,
DC voltage is applied to conductive ribbon R11 and variable resistor R1□
A series circuit of a fixed resistor R21 and a variable resistor R2□, a relay coil Ry, and a transistor T'H
and the base of the transistor TR.

In this state, relay contact ry is closed in an appropriate manner and maintained in its closed state. Along with this, the AC power source E is connected to the electrodes 12.13 at the back of the planar heating element main body, and the conductive elastomer layer 11 starts to generate heat.

When normal heat generation does not occur in the conductive elastomer layer 11 of the surface-shaped heating element body 10A, the resistance of the conductive ribbon R1 of the interrupting device 10B does not increase excessively.

Therefore, the voltage at the non-inverting input terminal of the operational amplifier OP does not drop excessively, and a low-level output does not appear at its output terminal.

As a result, the transistor TR can maintain the voltage between the base and emitter, so it maintains the conductive state, and as a result, the relay coil R maintains the excited state.

Therefore, the relay contact ry maintains the closed state and continues to supply power from the AC power source E to the electrodes 12 and 13 at the back of the sheet heating element main body.

凰! When abnormal heat generation (for example, local heat generation) occurs in the conductive elastomer layer 11 at the back of the planar heating element main body, the resistance of the conductive ribbon R1+ of the interrupting device increases excessively.

If the resistance of the conductive ribbon R11 increases too much, the voltage at the non-inverting input of the operational amplifier OP will be lower than the voltage at the inverting input, and a low level output will appear at its output.

As a result, the voltage between the pace emitter of the transistor TR decreases, so that the transistor TR becomes non-conductive, and as a result, the excitation coil R becomes a non-excitation state.

Therefore, the relay contact ry is opened, and the power supply from the AC power source E to the electrodes 12, 13 of the planar heating element main body is stopped.

Incidentally, in order to prevent accidents, the relay contact ry is designed not to close even if the relay coil R is energized once it is opened by -degree.

(Construction of Part 2) The structure of a second embodiment of the planar heating element according to the present invention will be described in detail with reference to FIG. 3.

The second embodiment has the following exceptions: a resistor R6 is provided in place of the relay coil R2, a temperature fuse F is provided in place of the relay contact r, and the conductive ribbon R has negative temperature characteristics. , has the same configuration as the first embodiment.

Therefore, in the second embodiment, when abnormal heat generation occurs in the planar heating element main body 10A, the resistance of the conductive ribbon R1+ decreases, the transistor TR becomes conductive, and the resistance R
This embodiment has the same function as the first embodiment except that the temperature fuse F is blown out by step 5 and the power supply from the AC power source E to the electrodes 12 and 13 at the back of the sheet heating element body is stopped.

Therefore, here, the same reference numerals as in the first embodiment are given to the same members as those included in the first embodiment, and other detailed explanations will be omitted.

In the above description, only the case of AC power source E has been described, but the present invention is not limited thereto, and also includes the case of DC power source. Incidentally, in the case of a DC power supply, the rectifier REC can be removed.

Further, in the first embodiment described above, only the case where the conductive ribbon R++ has positive temperature characteristics has been described, but the present invention is not limited to this, and the conductive ribbon R++ has positive temperature characteristics.
This also includes cases where + has negative temperature characteristics. In this case, the arrangement position of the conductive ribbon Rl1 and the arrangement position of the resistor RI2 may be exchanged, or the connection position with respect to the operational amplifier OP may be exchanged.

Further, in the second embodiment described above, only the case where the conductive ribbon R31 has negative temperature characteristics has been described, but the present invention is not limited to this, and the conductive ribbon R3
This also includes cases where 1 has positive temperature characteristics. In this case, the arrangement position of the conductive ribbon R11 and the arrangement position of the resistor R1□ may be exchanged, or the connection position with respect to the operational amplifier OP may be exchanged.

(3) Effects of the invention As is clear from the above description, the sheet heating element according to the present invention is a sheet heating element in which electrodes are disposed on a conductive elastomer layer, and in particular, (al conductive (b) A conductive ribbon that is arranged near the elastomer layer and whose resistance changes according to heat generation in the conductive elastomer layer; (ill conductive elastomer layer); and (ill conductive elastomer layer). It has the effect of being able to detect even abnormal heat generation of sex class 8F, and furthermore, (ii) it is possible to avoid inhibiting the flexibility of the conductive elastomer layer, and to reliably detect abnormal heat generation in local areas of the conductive elastomer layer. As a result, it has the effect of improving safety.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of a planar heating element according to the present invention, FIG. 2 is an exploded perspective view showing a part of the embodiment shown in FIG. 1 on an enlarged scale, and FIG. The figure is a configuration diagram showing a second embodiment of the sheet heating element according to the present invention.

Claims (1)

[Scope of Claims] In a planar heating element in which an electrode is disposed on a conductive elastomer layer, (a) the conductive elastomer layer (11) is disposed in the vicinity of the conductive elastomer layer (11); ) The conductive ribbon (R
_1_1); (b) monitoring means (OP, R_1_2, R_2_1, R_2_2) connected to the conductive ribbon (R_1_1) and for monitoring changes in resistance of the conductive ribbon; and (c) monitoring means (OP, R_1_2, R_2_1, R_
Based on the monitoring results of 2_2), the conductive elastomer layer (11
), when it was discovered that abnormal heat generation occurred at the electrode (12
, 13) from the power source (TR; R
_y, r_y; R_5, F).