JPS59103117A - Temperature controller - Google Patents

Abstract

PURPOSE:To facilitate the mild measurement of temperature by providing a bidirectional switch element between a heating element and an AC power supply to ensure conduction in both directions until the prescribed time elapses to heat up the heating element and then having conduction in a single direction to suppress the heating. CONSTITUTION:A triac D1 is provided between an AC power supply AC and a heating element HT, and a gate voltage generating circuit A is connected to the gate of the triac D1. In addition, a heating element TS produces a temperature signal corresponding to the temperature of the element HT, and a short circuit current detecting circuit G is connected to a line L2 of the element HT. Furthermore a DC power supply circuit B which produces the DC voltage by the input of the power supply AC is added together with a timepiece circuit C which sets the start time for control of temperature, a temperature setting circuit E and a gate voltage generation control circuit F. The triac D1 is made to conduct in both directions until the prescribed time elapses to heat up the element HT. Then the D1 conducts automatically in a single direction to suppress the heating of the element HT. This ensures easy and mild measurement of temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a temperature control device for heating appliances such as electric blankets and foot warmers, and similar devices, which are equipped with a heating element that generates heat when AC power is applied.

<Prior art> Temperature control devices used in such appliances and devices:
For comfortable heating, it is necessary to control the application of AC power to the heating element. For this reason, conventionally, a heat sensitive body such as a thermostat is provided, and the heat sensitive body is operated depending on whether the temperature is above a predetermined temperature to control the application of AC power to the heat generating body. In such a control method, alternating current power is applied to the heating element to generate heat until the temperature reaches a set temperature at which the heat sensitive element operates, and thereby the temperature can be rapidly increased to perform heating. However, heating appliances generally have a heat retention structure that prevents the heat generated by the heating element from being taken away by the surrounding cold air, so if the set temperature remains the same after the time period from when the heating element was first turned on, it will become excessive. There may be times when it becomes too warm. For this reason, while heating can be done with rapid temperature rise, when using heating equipment for a long time,
In order to perform moderate (mild) heating, it may be necessary to adjust the above-mentioned set temperature. However, with conventional temperature control devices, this adjustment is only made manually, which makes it difficult to perform mild heating.

Purpose of the present invention: When a heating device is first used, the temperature is raised rapidly to enable early heating, and after a predetermined period of time has passed from the beginning of use, the temperature of the heating device is automatically reduced to a mild temperature. The purpose is to make it easier to warm up mildly by lowering the temperature and maintaining that temperature continuously.

For this purpose, the present invention provides a bidirectional switching element between the heating element and the AC power source, and allows the switching element to conduct in both directions from the start of temperature control until a predetermined period of time has elapsed. The heating element generates heat to rapidly raise the temperature, and after a predetermined period of time, it automatically conducts in one direction to suppress the amount of heat generated by the heating element, lowering the heating temperature and continuing mild heating. I'm trying to get the best out of it.

<Example> FIG. 1 is an electrical circuit diagram of one embodiment of the present invention.

In Fig. 1, the symbol A'C is a commercial AC power supply, HT is a heating element placed at a predetermined position in a heating appliance such as an electric blanket, and Dl is a series connection between the commercial AC power supply AC and the heating element H'T. A triac is a bidirectional switching element connected to a TRIAC. This heating element HT has a heating wire L1,
A tube made of polyamide resin or the like is coated on the outer periphery of the heating wire L□, and a conductive short-circuit line L3 is wound around the outer periphery of the tube L2. This tube L2 not only acts as an electrical insulator between the heating wire L1 and the shorting wire, but also serves to electrically short-circuit both of the wires L3 to each other, since it will melt when the heating wire L1 is at an abnormally high temperature. have an effect. TS is a heat sensitive element that outputs a temperature signal in response to the temperature of the heating element HT, and includes a primary winding L4 wound around a core (not shown) and vinyl chloride coated on the outer periphery of this primary winding L4. A tube L5 made of a material having a negative temperature coefficient of resistance such as the like, and a secondary winding wound around the outer circumference of the tube L5 are provided. This tube L5 has a property that its resistance value decreases as the temperature of the heating device increases due to the heating element HT.

A is a gate voltage generation circuit that applies a voltage to the gate of the triac D1 to control bidirectional/unidirectional conduction and bidirectional non-conduction of the triac D1. This gate voltage generation circuit A includes a photoreceptor transistor TR, which constitutes a photocoupler.
including. B is a DC power supply circuit that generates DC voltage from the output of AC power supply AC supplied through resistor R28. This DC power supply circuit B obtains a DC voltage from a diode D15 and a capacitor C5. This DC power supply circuit B has a control signal generation circuit including transistors TR4 and TR5. One of the transistors TR5 has a positive half-wave output waveform from the AC power source AC, which is connected to the resistors R25 to R25.
28 to the base, the positive half-wave rise causes an instantaneous high level signal S1 as the first gate conduction control signal to be generated at its collector at 9 o'clock.

The other transistor TR4 receives a negative half-wave output waveform from the AC power supply AC through the resistor R24 to its base, so that it is activated as a second gate conduction control signal at the rise of the negative half-wave. An instantaneous high level signal S2 is generated at its collector. SW is a normally open switch for starting temperature control.

C is a timing circuit that outputs a first timing signal until a predetermined time has elapsed after the normally open switch SW is closed, and outputs a second timing signal after the predetermined time has elapsed. This clock circuit C includes a capacitor C6 and a capacitor C
4, and a resistor R171''18 that divides the voltage of the DC power supply circuit B.

The combination of this capacitor C4 and resistors R15, R16, etc. allows the first. A charging/discharging circuit is configured to generate the second time measurement signal. In addition, this clock circuit C is a comparator CP
2. This comparator CP2 has a positive phase side input terminal 10 and a negative phase side input terminal -. The charging voltage of the capacitor C4 is applied to this positive phase side input terminal as a timing voltage. In addition, voltage dividing resistors R, , R
The voltage divided by 18 is given as a reference voltage for timekeeping operation.

This comparator CP2 compares the charging voltage of the capacitor C4 with a reference voltage. In this comparison, when the charging voltage of capacitor C6 is higher, a high level signal is output as the first time measurement signal, and in the opposite case, the second time measurement signal is output.
Outputs a low level signal as a timing signal. Note that this comparator CP2 has an open collector and is connected to the collector of the transistor TR4 via a diode D1□, and to the power supply line L7 via a diode D1□.

E is a temperature setting circuit that outputs a temperature setting signal. This temperature setting circuit E includes a temperature setting variable resistor R13 and a comparator CP having an open collector. This comparator cpl has a negative phase side input terminal - and a positive phase side input terminal. The temperature signal of the heat sensitive body TS is input to this negative phase side input terminal, and the same reference voltage as that applied to the negative phase side input terminal of the comparator CP2 of the timing circuit C is input to the positive phase side input terminal. A reference voltage is provided. The negative phase side input terminal of the comparator CP□ of this temperature setting circuit E is a resistor RI,
It is connected to the connection part P1 between R□2. A transistor TR for setting the maximum temperature is placed on both ends of the variable resistor R13 for temperature setting.
Three collectors and emitters are connected. The base of this transistor TR is connected to the connection P2 between the diode D1□ and the resistor. The base of this transistor TR is connected to resistors R19 and R19 during output of the first clock signal.
A high voltage for continuity is applied from DC power supply circuit B through 20. This high voltage for conduction makes the transistor TR3 conductive. As a result, both ends of the temperature setting variable resistor R13 are electrically short-circuited. Due to this short circuit, the temperature setting circuit E is set to the maximum temperature setting value Q, m.

F is a gate voltage generation control circuit for controlling the gate voltage generation timing of the gate voltage generation circuit A. This gate voltage generation control circuit F is controlled to be in an operable or inoperable state by a temperature setting signal from a temperature setting circuit E. This gate voltage generation control circuit F includes a first . Instantaneous high level signals S□, S2 are applied as second gate conduction control signals.

For this reason, the gate voltage generation control circuit F
R2 and a photocoupler light emitting diode D8.

An instantaneous high level signal is applied to the base of this transistor TR2. As a result, the transistor TR2 becomes conductive and the light emitting diode emits light.

The light receiving transistor TR of the gate voltage generating circuit A receives the emitted light. This causes the gate voltage generation circuit A to generate a gate voltage.

Note that G is connected to the short-circuit wire - and when the current flowing through the heating wire L1 flows as a short-circuit current to the short-circuit wire L3, this short-circuit current is detected and a voltage is generated that makes the triac D1 non-conductive in both directions. This is a short circuit current detection circuit. Also, the diode D7, the resistor and the thyristor D9 are
Circuit H to short-circuit the negative half-wave output of AC power supply AC
Configure. This short circuit H prevents the negative half-wave output of the AC power supply AC from being input to the temperature setting circuit E via the resistors R141R16. This thyristor D, therefore, connects the alternating current power supply AC to its gate via a resistor.
The negative half-wave output is output and conduction occurs.

Next, the operation will be explained with reference to FIGS. 2 and 3.

First, the normally open switch SW is closed to start temperature control.

As a result, the capacitor C4 of the clock circuit C is charged by the DC current flowing through the power line L7 of the DC power supply circuit B.

In this charging, the charging voltage of the capacitor C4 input to the positive phase side input terminal of the comparator CP2 in the clock circuit C becomes higher than the reference voltage input to the negative phase side input terminal - of the comparator CP2. .

Therefore, the output level of the comparator cP2 increases.

That is, the clock circuit C enters the first clock signal output state. This output state continues for a period T□ until the charging voltage of capacitor C4 becomes lower than its reference voltage.

During this period T1, the diode D11 becomes non-conductive. For this reason, each collector of the transistors TR11i and TR has a voltage as shown in FIG. 2(b) which is synchronized at the rise of each half cycle of the output waveform of the AC power supply AC shown in FIG. 2(a).
An instantaneous high level signal S1+ 82 shown in (C) is generated.

This instantaneous high level signal S1. S2 and S2 are alternately input to the connection portion P3 as shown in FIG. 3(d). on the other hand,
Since the clock circuit C is outputting the first clock signal, the diode D1° is non-conductive. Therefore, the transistor TR3 of the temperature setting circuit E is connected to the resistor RI9. It is conductive by a DC voltage passing through R2°. As a result, the temperature setting variable resistor R13 is electrically short-circuited.

As a result, the temperature setting circuit Fi is set to the maximum temperature setting value Qm. In this state, the temperature setting signal is not output from the temperature setting circuit E at first. For this reason, the connection part P
3, the instantaneous high level signal S1. S2 is applied to the base of transistor TR2 in gate voltage generation control circuit F as a base signal. As a result, the transistor TR
2 is conductive. Due to this conduction, the light emitting diode D8 emits light. Furthermore, due to this light emission, the gate voltage generation circuit A
The inner light-receiving transistor TR□ becomes conductive. The timing of this conduction is determined by the instantaneous high level signal S shown in Fig. 2 (b) (C).
,, is synchronized with the occurrence of S2. Therefore, the gate voltage generating circuit A generates the gate voltage signal S3 that makes the triac D□ conductive at the timing shown in FIG. 2(e). As a result, the triac D1 becomes as shown in Fig. 2 (
The output of either the positive or negative cycle of the alternating current power supply AC shown in a) is electrically conductive. Therefore, power having the waveform shown in FIG. 2(f) is applied to the heating line L1 of the heating element HT. In this way, the heating element HT has a temperature gradient curve A shown in FIG.
As shown in , the temperature is rapidly raised to the maximum set temperature Qm. In this way, time t. When the maximum set temperature Q, m is reached, the heat-sensitive tube L5 of the heat-sensitive body TS is also heated and its temperature increases, and its impedance becomes sufficiently small. Therefore, the positive half-wave side output of the AC power supply AC is input to the capacitor C3 via the heat sensitive body TS and the resistor RION diode D1o. Note that the negative half-wave side output of the AC power source AC flows to the gate of the thyristor D through the resistor, thereby making the thyristor D9 conductive. Therefore, this negative half-wave side output flowing through the resistor R14° and R2° is hardly outputted to the capacitor C3, but is outputted to the diode D7, the resistor, and the thyristor D9. Therefore, capacitor C3 is hardly charged by this negative half-wave side output. by the way,
The charging voltage of the capacitor C3 increases due to the output on the half-wave side of the above voltage. Therefore, the negative phase side input terminal of comparator CPl -
The input voltage of the input terminal becomes higher than that of the input terminal on the positive phase side, and a temperature setting signal is generated from the temperature setting circuit E.

Then, the instantaneous high level signal S, which had been input to the gate voltage generation control circuit F via the connection P3,...
S2 ends up being input to comparator CP1. As a result, the transistor TR2 of the gate voltage generation control circuit F becomes non-conductive. By doing this, the light emitting diode D8
stops emitting light, and as a result, the gate voltage generation circuit A
will no longer generate gate voltage. Therefore, the triac D1il-i becomes non-conducting. In this way, the heating element HT
Since the alternating current power supply AC is no longer applied to , heat generation is stopped, and the heat generation temperature is slightly lower than the maximum set temperature Q, m. However, when the heat generation temperature decreases, the impedance of the heat-sensitive tube L5 of the heat-sensitive element TS increases, so contrary to the above, the triac D1 conducts in both directions again, and the output of the AC power supply AC becomes positive and negative again to the heat-generating element HT. The heating element HT is heated again by being applied in the amphibious cycle. In this way, the heat generation temperature becomes the maximum set temperature Qm again. Time t. Thereafter, by repeating such operations, the period T1
The temperature of the heating element HT remains at the maximum set temperature Q until
It is held at m. In this way, the heating device can be sufficiently warmed up in an extremely short period of time.

Next, when the period T1 has elapsed, the capacitor C of the timing circuit C
4 charging voltage becomes low. As a result, the input voltage to the positive phase side input terminal + of the comparator CP2 becomes lower than that to the negative phase side input terminal -.

Therefore, the clock circuit C outputs the second clock signal.

This second clock signal causes the diodes D1□ and D12 to conduct during a period T2 after the elapse of the period T1. Therefore, as shown in period T2 in FIG. 2(C), an instantaneous high level signal is no longer applied to the collector of transistor TR4 of DC power supply circuit B. At the same time, the base voltage of the transistor T% of the temperature setting circuit E decreases, so this transistor TR3 is cut off, and the short circuit between both ends of the temperature setting variable resistor R13 is released. Therefore, the set temperature of the temperature setting circuit E decreases from the highest set temperature value Q, m to the set temperature value QO set by the temperature setting variable resistor R□3. Therefore, the operation of the gate voltage generation control circuit F is controlled only by the instantaneous high level signal shown in period T2 in FIG. 2(b). However, in this operation, the temperature reaches the set temperature Q at time t1,
It is impossible until the input voltage at the negative phase side input terminal - of the comparator CP becomes lower than that at the positive phase side input terminal. Then, at time t1, when the temperature becomes lower than the set temperature value QO, it becomes possible to operate. In this operable state, the gate I/voltage generation control circuit F is operated by the instantaneous high level signal S□ as described above. As a result of this operation, as also described above, the light emitting diode D8 emits light, the gate voltage generating circuit A generates a gate voltage, and the triac D1 becomes conductive. Since this conduction is synchronized with the generation timing of the instantaneous high level signal S1, the triac D1 conducts in one direction by the positive half-wave side output of the AC power supply AC. For which heating element H
T is made to generate heat by the output of the waveform shown in FIG. 2(f). After time t in FIG. 3, the temperature of the heating element HT is maintained at approximately the set temperature QO in the same manner as in the above-described operation. In this way, after the heating device is rapidly heated, it is automatically controlled to the set temperature Qo for obtaining mild warmth. In FIG. 3, temperature gradient curve B shows the case where temperature control is started without closing the normally open switch SW.

In addition, although the above-mentioned example was applied to the rapid heating circuit of a heating appliance, it can also be applied to its preliminary heating circuit.

<Effects> As described above, according to the present invention, a bidirectional switching element is provided between the heating element and the AC power source, and this switching element is made bidirectionally conductive until a predetermined period of time has elapsed from the start of temperature control. This causes the heating element to generate heat during either the positive or negative half cycle of the output waveform of the AC power supply, and after a predetermined period of time, by making the heating element conductive in one direction, it generates heat during either the positive or negative half cycle of the output waveform of the AC power supply. Since the body generates heat, the temperature can be raised rapidly until a predetermined period of time has elapsed, allowing for early warming.
After a predetermined time has elapsed, the temperature can be automatically lowered to a preset temperature that provides a predetermined mild temperature, and after reaching the preset temperature, the temperature can be automatically maintained at the preset temperature value.
Therefore, milder heating can be achieved more easily than when manually setting the temperature.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an electric circuit diagram, FIG. 2 is a signal waveform diagram for explaining operation, and FIG. 3 is a temperature control characteristic diagram. AC: AC power supply, Dl: TRIAC (bidirectional switching element), HT: heating element, A: gate voltage generation circuit, B: DC power supply circuit, C: clock circuit, E:
・Temperature setting circuit, F... Gate voltage generation control circuit, TS
...Thermosensitive element, SW...Temperature control start switch. Patent applicant: Sharp Corporation Representative: Patent attorney: Kazuhide Okada

Claims (1)

[Claims] (1) Connected between the AC power source and the heating element. a bidirectional switching element equipped with a gate; a timing circuit that outputs a first timing signal until a predetermined time has elapsed from the start of temperature control and outputs a second timing signal after the elapse of the predetermined time; and a heating element. A heat sensitive body outputs a temperature signal in response to temperature, and the temperature is set to a first temperature set value while the first clock signal is applied, and after the second clock signal is applied, the temperature is set to the first temperature setting value.
a temperature setting circuit that outputs a temperature setting signal when the temperature signal corresponds to a second temperature setting value that is lower than the temperature setting value of the AC power supply; a control signal generating circuit that generates a first gate conduction control signal when the gate conduction changes to a negative half cycle direction, and generates a second gate conduction control signal when the gate conduction control signal changes in the negative half cycle direction; a gate voltage generation circuit that applies a voltage that makes the bidirectional switching element conductive; and a gate voltage generation timing of the gate voltage generation circuit that is set to the first timing when the first clock signal is being output and the temperature setting signal is not being generated. ．． Gate voltage generation controlled in response to the second gate conduction control signal, and controlled in response to one of the gate conduction control signals when the second timing signal is being output and the temperature setting signal is not generated. A temperature control device comprising a control circuit.