JPS61267107A - Temperature detector for heat sensitive heating unit - Google Patents

Abstract

PURPOSE:To desiccate absorbed moisture of heat sensitive resin in early stage of current application by connecting an end of a heat generating line and an end of a temperature detecting line with a thermoelectric conversion element and controlling temperature detecting current corresponding to the temperature of a heat sensitive resin. CONSTITUTION:A heat generating line 2 and a temperature detecting line 3 are provided separately on the heat sensitive resin film 1 of a heat sensitive heating unit A, and when a contact S is closed, current flows from a commercial power source 7 to the heat generating line 2 and heat is generated. When impedance of the heat sensitive resin film 1 is lowered by rise of temperature, current flows to a detection resistance R1 from the heat generating line 2 through the temperature detecting line 3 and a thermoelectric conversion element Th. Accordingly, a switching circuit B operates and makes the contact S off. When the heat sensitive resin film absorbs moisture, rise of temperature is low, and accordingly, the thermoelectric conversion element Th keeps large resistance value, and the switching circuit B does not operate until temperature rises sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a temperature detection device for a heat-sensitive heating element used in a wide-area heating device such as an electric carpet or an electric blanket.

(Background technology) Conventionally, nylon 12 and other materials have been used as sensor materials for temperature detection in large-area heating devices such as electric carpets and electric blankets because they are easy to manufacture and process and provide a large constant. A modified polyamide resin is used. However, this type of plastic thermistor material is generally hygroscopic, and has the disadvantage that its impedance characteristics change not only depending on temperature but also on the amount of moisture absorbed by the plastic thermistor material. FIG. 7 shows an example of the impedance characteristics of a thermosensitive heating element, with temperature plotted on the horizontal axis and impedance change rate on the vertical axis.The impedance value decreases significantly due to moisture absorption.

Therefore, when you start using electric carpets etc. early in the season, the thermistor material has absorbed some moisture during storage, so the impedance of the sensor material has decreased, and the temperature control circuit will be closed even though the actual temperature is low. It operates under the assumption that the temperature is high, and since the surface temperature is low, the temperature gradually rises by repeatedly turning on and off, so it has the disadvantage that it does not get warm easily. Moreover, the moisture absorption of the plastic thermistor described above gradually dries up due to the heat generated by energization, so the phenomenon of ``too hot'' occurs when used for a long time, which also poses a problem.

In addition, if the temperature is not set on the assumption that the plastic thermistor material absorbs a certain amount of moisture, the phenomenon of ``too lukewarm'' may occur even at the highest temperature setting at the beginning of the season, and furthermore, the energization rate may be too low. This means that the thermistor material hardly dries, and the temperature never rises.

(Object of the Invention) The present invention has been proposed in order to improve the above-mentioned drawbacks, and a heating line and a temperature detection line are separated and arranged side by side on a thermosensitive resin material with negative characteristics, and the heating line and To dry a plastic thermistor material (heat-sensitive resin) in a short period of time at the initial stage of energization, in a heat-sensitive heating element that performs temperature control by detecting an impedance change of the thermo-sensitive resin material between it and the temperature detection line. The purpose is to provide a wide area heating device that can provide a comfortable temperature at any time without the phenomenon of being "lukewarm" at the beginning of the season or "too warm" during the season, using a simple and highly safe temperature detection device. It is said that

(Disclosure of the Invention) The characteristics of the present invention are that in a wide area electric heating device,
It detects that the energization rate to the heat generating line is low and corrects the initial set temperature, and automatically increases the energization rate when the energization rate to the heat generating line is low, i.e. when the surface temperature is low due to moisture absorption of the plastic thermistor. The temperature control operation is such that the drying speed of the plastic thermistor is increased by increasing the temperature, and when the surface temperature rises, the temperature control operation is automatically lowered to the normal setting. The point is that it can be easily and safely realized by providing an element.

Next, embodiments of the present invention will be described.

First, FIG. 5 shows a heat-sensitive sheet heating element used in the wide-area heating device of the present invention, in which (a) is a plan view and (b) is a partial sectional view. In the figure, 1 is a thermosensitive resin film (plastic thermistor material), 2 is a heating line, and 3
indicates a temperature detection line, and 4°5 indicates an insulating film. In addition, since the present invention is concerned with the drying speed of moisture absorption of the heat-sensitive resin film 1, the heating line 2 and the temperature detection line 3 are on the same plane as shown in FIG. It is preferable that one side of the resin film 1 has only the insulating film 5 and that there is nothing that inhibits the drying of moisture in the thermosensitive resin film, but this is not necessarily an absolute condition. Furthermore, in the case of the heat-sensitive sheet heating element shown in FIG. 5(b), it is preferable for the surface of the insulating film 5 to be on the front side because the drying speed will be faster.

Furthermore, FIG. 6 shows the structure of a heat-sensitive cord-like heat-generating body, and this type of cord-like heat-sensitive heat-generating body is also applicable to the present invention. As for the structure, a temperature sensor s3' is wound around a core material 7', a thermosensitive resin material 1' is arranged around it, a heating line 2' is wound around it, and an insulating material 4 is arranged around it.
It is covered with '.

Now, FIG. 1 is an electrical configuration diagram of an electric carpet showing one embodiment of the present invention. In the figure, A indicates a thermosensitive heating element, 1 is a thermosensitive resin film, 2 is a heating line, 3 is a temperature detection line, 2m, and 2b.

3m and 3b are lead wire connection parts, respectively. In addition, 7 is a commercial power supply, B is a switching circuit, C is a constant voltage DC power supply, T is a transformer, R1 is a detection resistor, Dl is a diode,
C0 is the capacitor, S is the normally open setting of the relay RV,
In the switching circuit B, 8 is a comparison circuit, D2 is a surge absorption diode, Q is a transistor, and R2 is a resistor. Further, Th indicates a thermoelectric conversion element such as a thermistor, which is a characteristic part of the present invention.

The thermoelectric conversion element Th is attached to a location where the heat generation temperature can be detected depending on the degree of energization of the heat generation line 2. The specific location is preferably in the connection section 22 that includes the temperature control circuit etc. as shown in FIG. An example of this is an electric circuit component in which a difference in heat generation temperature occurs depending on the energization rate to the heat generating line 2, such as the outer part of the transformer T.

However, the basic operation of this temperature control circuit is as follows.
When the temperature of the heat generating line 2 increases, the impedance of the thermosensitive resin film 1 decreases, and the temperature is detected from the heat generating line 2 for 1 s.
The current flowing to the detection resistor R□ through the thermoelectric conversion element Th via the capacitor C1 increases, and the voltage v0 across the capacitor C1 increases. This output voltage v0 is input to the comparator circuit 8 and compared with a reference voltage value, and when the output voltage v0 exceeds this reference voltage, the comparator circuit 8 selects the switching circuit B which has been kept in the on state within the safe temperature range. The transistor Q that constitutes the rear stage is reversed to the off state, the driving of the excitation coil of the relay Ry connected in series to this transistor Q is stopped, and the normally open contact S is changed from the previously on state to the off state. The power supply path of the heating line 2 is cut off by reversing the line. Further, when the temperature decreases, the normally open contact S is turned on again, and these operations lead the heat-sensitive heating element A to a constant temperature.

By the way, when the thermosensitive resin film 1 absorbs moisture and its impedance decreases, the current conductivity to the heating line 2 is low and the temperature does not rise much, so the electrical resistance of the thermoelectric conversion element Th maintains a large value. The thermoelectric conversion element Th serves as a limiting resistance for the control current flowing through the detection resistor R.

Therefore, even if the impedance of the thermosensitive resin film 1 decreases due to moisture absorption, the voltage v0 across the detection resistor R1
will maintain a small value.

Therefore, the normally open contact S is maintained in the on state and energized until the temperature rise progresses further and the control current flowing through the detection resistor R1 becomes larger, and the temperature rises to a predetermined temperature.
The moisture in the thermosensitive resin film 1 dries quickly. Further, the resistance value of the thermoelectric conversion element Th decreases as the temperature rises, and has no effect near the normal operating temperature, so that as the thermosensitive resin film 1 continues to dry, the control state shifts to a normal control state.

There is no particular restriction on the mounting position of the thermoelectric conversion element Th in terms of its electrical configuration, as it may serve as a limiting resistance for the control current as described above. Connections as shown in FIGS. 4 and 4 are also possible. That is, in FIG. 3, the voltage generated across the temperature detection line 3 is input to the switching circuit B, and the temperature detection line 3
A thermoelectric conversion element Th is connected between one end 3a and one end 2a of the heating line 2. Further, in FIG. 4, a thermoelectric conversion element Th is inserted into the path of a control current flowing from the heating line 2 to the temperature detection 93, and the current is detected by a current transformer CT.

Furthermore, although not shown, the thermoelectric conversion element Th may be used in combination with a volume resistor for temperature adjustment, or other fixed value impedances may be used to limit the effective fluctuation temperature range of the thermoelectric conversion element Th. May be used in combination with other ingredients.

(Effects of the Invention) As described above, in the present invention, a heat generating line disposed on a heat-sensitive resin material having negative characteristics, and a line between the heat generating line and the heat generating line which are separated and arranged in parallel with each other and the heat generating line are provided. In the heat-sensitive heating element comprising a temperature detection line for detecting an impedance change of the heat-sensitive resin material, one end of the heat generation line and one end of the temperature detection line are connected via a thermoelectric conversion element having a negative characteristic such as a thermistor. , Temperature control is performed by detecting a current of a magnitude corresponding to the temperature of the heat-sensitive resin material flowing through a path connecting one end of the heat generating line and one end of the temperature detection line. The moisture in the resin can be quickly dried,
Since the maximum setting temperature of the wide area heater can be matched to the characteristics of the heat-sensitive resin during drying, there is no risk of getting too hot or getting burnt at low temperatures.

(b) Since the presence or absence of temperature rise due to energization can be detected by a sensor different from the thermosensitive resin of the thermosensitive heating element and the setting can be automatically increased, the surface temperature rises quickly and there is a feeling of heating even when dry. can be obtained quickly.

(c) Compared to other methods such as adjusting the reference voltage level of the switching circuit of the temperature control circuit, etc. Rj configuration and operation are simple. In particular, with conventional models that are energized continuously for a certain period of time in the initial stage of energization, if the power is turned off once after the temperature rises and then turned on again immediately, some areas become partially insulated. However, in the present invention, there is no such danger.

There are other effects.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a temperature control circuit showing one embodiment of the present invention, Fig. 2 is an external view of an electric carpet showing the placement location of thermoelectric conversion elements, and Figs. 3 and 4 show other embodiments. 5 and 6 are structural diagrams of a thermosensitive heating element used in the present invention, and FIG. 7 is a diagram showing a state of change in impedance of the thermosensitive heating element depending on the moisture absorption level. 1...Thermosensitive resin film, 2...Heating line, 3...Temperature detection line, 4, 5...
Insulating film, 2m, 2b, 3m, 3b...
...Lead wire connection part, Th...Thermoelectric conversion element and 1 other person Fig. 1 Fig. 2 Fig. 7 □Yicheng °C)

Claims (1)

[Claims] A heating line disposed on a heat-sensitive resin material with negative characteristics, and a temperature detection line that is separated from and parallel to the heat-generating line and detects a change in impedance of the heat-sensitive resin material between the heat-generating line and the heat-generating line. In the heat-sensitive heating element, one end of the heating line and one end of the temperature sensing line are connected via a thermoelectric conversion element with a negative characteristic such as a thermistor, and one end of the heating line and one end of the temperature sensing line are connected. A temperature detection device for a thermosensitive heating element, characterized in that the temperature is controlled by detecting a current having a magnitude corresponding to the temperature of a thermosensitive resin material flowing through a connected path.