JPS6097580A - Temperature control system of electric heating carpet - Google Patents

Abstract

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

Description

TECHNICAL FIELD The present invention relates to a temperature control system for electrically heated rugs such as hot carpets.

(Background technology) Hot carpet heaters have a slight surface finish such as felt or cloth, and can be used alone, but can be used with various covers depending on the preference of the user. There are many things. In this case, the problem is that the surface temperature of the cover varies depending on the thickness of the cover used. By the operation of the temperature control circuit, the temperature near the heater is controlled to match the set temperature given by the temperature regulator, but differences in the cover surface temperature occur due to differences in the thermal conductivity of the cover. It is something that comes.

Therefore, if the set temperature remains unchanged without the cover, the temperature will drop when the cover is used, making it feel lukewarm, and conversely, if the temperature is appropriate when using the horn bar, it will be too hot when the cover is removed.

However, in the past, it was necessary for the user to manually vary the set temperature according to the type of cover and search for the appropriate temperature, which was very cumbersome and had the disadvantage of poor operability.

(Object of the Invention) The present invention was proposed in view of the above points, and provides an electric heating rug that significantly improves operability by automatically changing the set temperature according to the type of cover used. The purpose of this invention is to provide a temperature control method.

(Disclosure of invention) Hereinafter, the present invention will be explained in detail along with the drawings.

FIG. 1 shows the external appearance of an electric heating rug to which the present invention is applied, where 11 is a heater surface, 12 is provided at a corner end of the heater surface 11, and a temperature control circuit section, a heater, and a sensor are provided. This is a case of a terminal part including a connection part of an electrode. Note that the cover covers the heater surface 11 and the case 1.
Although the case 12 is covered so as to cover the case 12, a part of the case 12 may be exposed.

FIG. 2 shows an embodiment of a temperature control circuit embodying the present invention. To explain the configuration in the figure, the commercial power supply 1 includes a contact RVa+ of a relay Ry.

A heater H of a heat generating element 2 is connected through Ryaz at both ends, and a mm circuit 3 for supplying a DC Wi source to each circuit section is further connected to the commercial type xi. Further, the heating element 2 is a sensor electrode S+ provided close to the heater H over almost the entire surface thereof.

A heat-sensitive material, such as a plastic semiconductor, exhibiting a negative characteristic impedance with respect to temperature is provided between the sensor electrodes S+ and S2.

A DC voltage is applied to one sensor electrode S from the power supply circuit 3 via the voltage dividing circuit 4, and the other sensor electrode S
2 is grounded, and has a configuration in which the applied DC voltage is divided by the impedance of the voltage dividing circuit 4 and the impedance of the heat-sensitive material.

Then, the sensor 4J electrode S1 is connected to the temperature detector 5,
It is extracted as a signal indicating the temperature near the heater. Note that the signal applied to the sensor electrode S1 may be an alternating current signal, and in that case, the temperature detector 5 may be provided with a rectifying/smoothing function.

On the other hand, a variable resistor VR and a resistor R+ are connected between the DC output terminal of the power supply circuit 3 and the ground as a temperature regulator.

Rs, a series circuit of a negative characteristic thermistor NTC as a heat-sensitive element is connected in parallel with each other, and the connection point between resistor R+ and resistor R1 and the movable terminal of variable resistor vR are connected to resistor R2, respectively.
, R3, and this connection point is connected to an inverting input terminal of an operational amplifier A constituting a comparator circuit. Furthermore, a Zener diode ZD is connected to both ends of the resistor R+ in a direction opposite to the applied voltage, and this is for setting an upper limit temperature so that the set temperature does not rise indefinitely, as will be described later. .

The non-inverting input terminal to the operational amplifier is then connected to the output terminal of the temperature detector 5 and to its own output terminal via a resistor R4 in order to provide appropriate hysteresis to the comparison level.

Further, Q is a transistor for driving a relay, the emitter is grounded, the collector is connected to the DC output terminal of the Wi power supply circuit via the relay RV, and the base is connected to the output terminal of the operational amplifier A via the resistor Rs. ing. In addition,
In FIG. 2, the heating element 2 corresponds to the heater surface 11 in FIG. 1, and the other circuit parts are housed in a case 12.

FIG. 3 shows the influence on the internal temperature of the case 12 by the cover placed over the electric heating rug when the cover is actually used. In the figure, the horizontal axis shows the thickness of the cover used, and the vertical axis shows the temperature inside the case, where a is a case without a cover, b is a medium-thick cover such as velor, and C is a thick cover such as Saxony Shaggy. handle. In other words, the temperature inside the case 12 is determined by the balance between the heat generated by the temperature control circuit itself and the heat flowing out to or flowing in from the outside, so the presence of the cover increases the insulation effect and causes the temperature to rise. There is a tendency to Therefore, in the present invention, as described above, by utilizing the correlation between the thickness of the cover and the internal temperature of the case 12, the woofer is
The internal temperature of No. 2 is detected, and the set value of the temperature control is corrected according to this detected value. The case 12 is hardly thermally affected by the heater surface 11, and the temperature inside the case is related only to the thickness of the cover, assuming that the outside temperature (room temperature) is constant.

Hereinafter, referring back to FIG. 2, the operation of the circuit will be explained. Commercial power supply 1
When the power supply circuit 3 is turned on, DC power is applied to each part from the power supply circuit 3, and the circuit enters an operating state. At this time, a DC voltage is applied to the sensor electrode SL of the heating element 2 via the voltage dividing circuit 4,
Impedance of voltage divider circuit 4 and sensor electrode S+, 82
A voltage corresponding to the partial pressure ratio with the impedance of the heat-sensitive material interposed therebetween is input to the temperature detector 5. The temperature detector 5 performs appropriate processing such as noise removal, and supplies a detection signal having a characteristic of decreasing as the temperature increases to the non-inverting input terminal of the operational amplifier A constituting the comparator circuit.

However, at the initial stage of startup, the heating element 2 has not yet been sufficiently warmed up, so the voltage applied to the non-inverting input terminal of the operational amplifier is high enough, and the output of the operational amplifier saturates positively. Q is turned on to drive relay RV, and contacts RVa+ and Rya2 are turned on to energize heater H. Thereafter, the temperature of the heating element 2 rises by energizing the heater H (as a result, the impedance of the heat-sensitive material interposed between the sensor electrodes S++ and S2 decreases, and the temperature is detected by the non-inverting horn terminal of the operational amplifier A). The signal decreases and finally falls below the set value given to the inverting input terminal of operational amplifier A, causing the output horn of the operational amplifier to be inverted.As a result, I and transistor Q are turned off, and the driving of relay rl is also stopped. Therefore, contact R
Va+ and RVa2 are also turned off, power supply to the heater H is stopped, and heating of the heating element 2 is stopped. In addition, the operational amplifier A has a certain width of hysteresis due to the positive feedback resistor R4, and when the temperature detection signal rises as the heating element 2 cools and exceeds the hysteresis width, it is reversed again and the transistor Q , the heater H is energized by the operation of the relay RV. After that, these operations are repeated, so that the heating element 2 is controlled to match the set temperature corresponding to the set value applied to the inverting input terminal of the operational amplifier A.

On the other hand, the variable resistor VR of the temperature regulator is manually operated according to an indication scale (not shown),
The voltage set by the movable terminal is applied to the inverting input terminal of operational amplifier A via resistor R3, but in order to make corrections to this set value according to the temperature inside the case and the cover thickness, resistor R+ +Rs is applied. , a voltage is superimposed via the resistor R2 from the connection point of the resistors R+ and Rs of the series circuit formed by the negative characteristic 4 no-mister NTC. Naturally, the impedance of the negative characteristic narmistor NtC decreases as the temperature inside the case increases, so the voltage at the connection point of the resistors R+ and Rs connected in series with it decreases with a constant slope as the temperature inside the case increases. , therefore 1
As the thickness of 1 bar increases, the setting value given to operational amplifier A is moved to the higher temperature side. In Figure 4, the horizontal axis shows the temperature inside the case where the temperature control circuit is housed, and the vertical axis shows the surface temperature TH of the heating element 2 and the surface temperature Tc of the cover. By increasing the surface temperature TH of the heating element 2 in accordance with the increase in the thickness of the bar, the surface temperature Tc of the cover is maintained at a constant value. In FIG. 4, a corresponds to a state without a cover, b corresponds to a case where a medium-thick cover such as velor is used, and C corresponds to a case where a thick cover such as Saxony Shaggy is used.

In addition, the reason why the increase in the surface temperature To of the heating element 20 is canceled and kept flat after it exceeds the 0 point in FIG. 4 is to prevent the temperature of the heating element 2 from increasing indefinitely. In the circuit shown in FIG. 2, the correction amount is clamped to a constant value by utilizing the fact that the Zener diode IO starts conducting. Note that the amount of increase in the set temperature relative to the cover thickness can be set by the characteristics of the negative characteristic thermistor NTC and the values of the resistors R+ and Rs, so each numerical value is It is to be determined.

(Effect of Mineaki) As mentioned above, Honi! In the case of octopus, the temperature of the heater is detected, compared with the set temperature, and the power to the heater is turned on.
In an electric heating rug that is controlled off, the set temperature is corrected according to the thickness of the cover that is placed over the electric heating rug, and the surface temperature of the cover is kept constant, so the electric heating rug can be used alone. It is possible to keep the temperature at an appropriate temperature with the standard setting box, regardless of whether it is used with a lid on or with a cover on, which significantly improves operability. There is.

[Brief explanation of drawings]

Fig. 1 is an external view showing an example of an electric heating rug to which the present invention is applied, Fig. 2 is a circuit diagram of a temperature control circuit embodying the present invention, and Figs. 3 and 4 are as shown in Fig. 2. FIG. 3 is an explanatory diagram of the operating state of the illustrated embodiment. '1... commercial power supply, 2... heating element, 1]...
・Heater, St, S2... Hinsa electrode, 3...
Power supply circuit, 4... Voltage dividing circuit, 5... Furniture detector, RV... Relay, RVa+, RVa2...
Contact, A...Operational amplifier, Q...Transistor, NTC...Negative characteristic thermistor, Zll...
...Zener diode, R+, ~, Rs...Resistance, VR...Variable resistor Fig. 1] 2 Fig. 2 Fig. 3r! ;4 Figure 4

Claims (2)

[Claims] (1) In an electric heating rug that detects the temperature of a heater and compares it with a set temperature to control on/off the electricity supply to the heater, the set temperature is adjusted according to the thickness of the cover that covers the electric heating rug. A temperature control method for an electric heating rug, characterized in that the surface temperature of the cover is kept constant by correcting the above. (2) A heat-sensitive element such as a negative characteristic thermistor is provided in the case that is provided at the corner of the electric heating rug and the control circuit is housed, and the output voltage of the resistive voltage divider circuit that includes this heat-sensitive element in series is Claim 1 wherein the voltage is superimposed on the set voltage given from the temperature regulator and the set temperature is corrected.
Temperature control method for electric heating rugs as described in section.