JPH0534207A - Temperature detecting apparatus for heat generating cloth - Google Patents

Abstract

PURPOSE:To obtain a temperature detecting apparatus wherein the time change of a temperature detecting wire for detecting the heating temperature in heat, generating cloth is suppressed. CONSTITUTION:An AC signal is applied into a voltage dividing circuit wherein a temperature detecting wire around which first and second windings 31 and 33 are wound through a heat sensitive material 32 is connected to a voltage dividing resistor 12 in series. Thus, a temperature detecting device 6 is constituted. The current through the voltage dividing circuit is changed in correspondence with the changes in impedances of the first and second windings 31 and 33 based on temperature due to the change in permittivity of the heat sensitive material 32. Therefore, the AC voltage corresponding to the temperature of the voltage dividing resistor 12 is generated. The temperature for controlling the current conduction of a heat generating wire 2 can be detected by operating the effective value of the AC voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device for controlling the temperature of an electric heater using a heating cloth such as an electric carpet or an electric blanket.

[0002]

2. Description of the Related Art An example of an electric circuit diagram of a conventional electric carpet or electric blanket is shown in FIG. As shown in the figure, a heating circuit is configured by connecting a heating wire 2 and a switching element 3 in series to a power supply 1. By controlling the gate current of the switching element 3 by the temperature control circuit 15, the energization to the heating wire 2 is ON / OFF controlled, and the heating temperature by the heating wire 2 can be controlled.
A temperature detecting device 16 is provided as a means for detecting the temperature of the heating wire 2 for controlling the temperature. The temperature detecting device 16 rectifies the temperature detecting line 7, the voltage dividing resistors 8 and 9 connected in series to the temperature detecting line 7, and the AC voltage generated in the voltage dividing resistor 9 and inputs it to the temperature control circuit 15 as a DC voltage. It is composed of a diode 10 and a capacitor 11. As shown in FIG. 4, the temperature detecting wire 7 is formed by spirally winding a first winding wire 31 on a heat-resistant core material 30, and covering it with a heat-sensitive material 32 made of an insulating resin such as nylon. The winding 33 is spirally wound in the winding direction opposite to the winding direction of the first winding 31, and the outer side thereof is covered with an insulating jacket 34. The heat sensitive material 32 is heated by arranging the temperature detecting wire 7 near the heat generating wire 2 arranged on the heat generating cloth. Due to the change in the dielectric constant depending on the temperature of the heat sensitive material 32, the first and second windings 31, 3
Since the impedance between 3 changes, the temperature detection line 7 is connected in series with the voltage dividing resistors 8 and 9 to the power source 1 as shown in FIG. Since the current flowing through the series circuit changes due to the impedance change, the voltage across the voltage dividing resistor 9 changes depending on the temperature. Therefore, the AC voltage corresponding to the temperature across the voltage dividing resistor 9 is transferred to the diode 10 and the capacitor 1.
The temperature is controlled by rectifying by 1 and inputting to the temperature control circuit 15 as a DC voltage.

[0003]

Since the above-mentioned heat-sensitive material has the characteristic that the change over time occurs when the direct-current component is continuously applied and the impedance change with respect to the temperature change becomes small, the direct-current component is not sensitive to the heat-sensitive material. It must be configured so that it is not applied to 32. However, in the above-mentioned conventional temperature detecting device 16, since the rectifying circuit is connected to the voltage dividing resistors 8 and 9 connected to the temperature detecting line 7, the direct current component is continuously added to the heat sensitive material 32 although it is slight. Inevitably, there was a problem that changes with time tended to occur. Also,
Since the AC voltage from the power supply 1 is applied to the temperature detection device 16, there is a problem that the fluctuation of the power supply voltage affects the fluctuation of the detection voltage for the temperature control and the temperature control becomes unstable. An object of the present invention is to provide a temperature detecting device for a heating cloth that solves the above-mentioned conventional problems.

[0004]

According to the present invention for achieving the above object, a temperature detecting wire formed by winding a first winding and a second winding through a heat sensitive material is provided along a heating cloth. In a temperature detecting device for a heating cloth, which is arranged in the vicinity of an installed heating wire and detects the heating temperature by the heating wire as an impedance change due to the temperature of the heat-sensitive material, the temperature detection wire and the voltage dividing resistor are connected in series. To form a voltage dividing circuit, detect the voltage dividing voltage of the voltage dividing resistor when an AC signal containing no DC component is applied to the voltage dividing circuit, and calculate the effective value of the voltage dividing voltage. Thus, the impedance change due to the temperature between the first and second windings is obtained.

[0005]

According to the present invention, by applying an AC signal containing no DC component to the voltage dividing circuit in which the temperature detecting line and the voltage dividing resistor are connected in series, the dielectric of the heat-sensitive material forming the temperature detecting line is applied. As the impedance between the first and second windings changes with temperature as the rate changes with temperature, the current in the voltage dividing circuit changes, so that the voltage dividing resistor receives an AC voltage corresponding to temperature. Occur. By calculating the effective value of this AC voltage, the temperature that controls the energization of the heating wire can be detected. When the alternating current signal applied to the temperature detecting device is an intermittent alternating current signal, the duty ratio of the load applied to the heat sensitive material becomes small, so that the temporal change of the heat sensitive material can be further suppressed.

[0006]

FIG. 1 shows a circuit diagram of an embodiment of a heating cloth to which the present invention is applied. The same parts as those of the conventional example are designated by the same reference numerals, and the description thereof will be omitted. In the figure, a heating circuit is configured by connecting a heating line 2 and a switching element 3 in series to a power source 1, and the gate current of the switching element 3 is controlled by a temperature control circuit 5 to reach the heating line 2. Is turned on / off. The temperature control circuit 5 is operated by the DC power supply circuit 4 whose voltage has been made constant, and is constructed so as not to be affected by fluctuations in the power supply voltage. Further, the temperature control circuit 5 is equipped with an AC signal generation circuit for temperature detection, and applies the output AC signal to the temperature detection device 6. The temperature detecting device 6 is composed of the temperature detecting line 7 and the voltage dividing resistor 12 shown in FIG. 4, and the temperature detecting line 7 is arranged in the vicinity of the heat generating line 2 arranged on the heat generating cloth. Since the dielectric constant of the heat sensitive material 32 changes due to the heating of the heating wire 2, the impedance between the first and second windings 31 and 33 changes. Therefore, when an AC signal containing no DC component output from the C and E terminals of the temperature control circuit 5 is applied to the voltage dividing circuit in which the temperature detecting line 7 and the voltage dividing resistor 12 are connected in series, the applied voltage changes depending on the temperature. Since the voltage is divided by the temperature detection line 7 whose impedance changes and the voltage dividing resistor 12, a voltage which changes with temperature is obtained at both ends of the voltage dividing resistor 12. When the AC signal applied to the temperature detection device 6 is, for example, an intermittent rectangular wave as shown in FIG. 2A, the temperature detection line is provided across the voltage dividing resistor 12 as shown in FIG. 2B. A voltage proportional to the impedance change due to the temperature of 7 is generated. By inputting the voltage across the voltage dividing resistor 12 to the D and E terminals of the temperature control circuit 5 and calculating the effective value, the detected temperature for temperature control can be obtained. The AC signal applied to the temperature detection device 6 is intermittently applied as shown in FIG.
It is read as a voltage change accompanying the impedance change of the temperature detection line 7 when a signal is applied. Therefore, the temperature detection line 7
Since the AC signal applied between the first winding wire 31 and the second winding wire 33 is intermittent, the change over time of the heat sensitive material 32 is suppressed as compared with the case where the heat sensitive material 32 is always energized. .

[0007]

As described above, according to the present invention, an AC signal from the temperature control circuit is applied to the temperature detection line for temperature detection in addition to the AC voltage from the power source.
Stable temperature detection is possible without being affected by fluctuations in the power supply voltage, a rectifier circuit is not included in the detection circuit, and no direct current component is added to the heat-sensitive material of the temperature detection line, suppressing the change over time of the heat-sensitive material. You can Therefore, it is possible to configure a temperature control circuit for the heating cloth, which is provided with a temperature detecting device which is stable and has little change over time.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a heating cloth having a temperature detecting device according to the present invention.

FIG. 2A is a waveform diagram of an AC signal applied to the temperature detecting device according to the present invention and FIG.

FIG. 3 is an electric circuit diagram of a conventional heating cloth.

FIG. 4 is a configuration diagram showing a structure of a temperature detection line.

[Explanation of symbols]

2 ... Exothermic line 6 ... Temperature detection device 7 ... Temperature detection line 12 ... Voltage resistance 31 ... First winding 32 ... Heat sensitive material 33 ... Second winding

Claims (2)

[Claims] 1. A heat detecting wire formed by winding a first winding and a second winding through a heat sensitive material is arranged in the vicinity of a heat generating wire arranged along a heat generating cloth to generate the heat. In a temperature detecting device for a heating cloth that detects a heating temperature by a wire as an impedance change due to the temperature of the heat-sensitive material, the temperature detecting wire and a voltage dividing resistor are connected in series to form a voltage dividing circuit. The temperature between the first and second windings is calculated by detecting the divided voltage of the voltage dividing resistor when an AC signal containing no DC component is applied to the An apparatus for detecting the temperature of a heating cloth, which is characterized by obtaining impedance change by 2. The temperature detecting device for a heating cloth according to claim 1, wherein an intermittent AC signal is applied to the voltage dividing circuit.