JPS5821285B2 - temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hot water temperature control device that controls the power of a load (heater) disposed on a glass door of a refrigerator or the like in accordance with ambient humidity.

Hereinafter, a detailed explanation of the present invention will be given with reference to FIG. 1.
is constructed by inserting a variable resistance element R1 such as a humidity sensor whose resistance value changes depending on humidity on one side, an adjustable variable resistance R4 on the other corresponding side, and fixed resistances R2 and R3 on the other two sides. is a bridge circuit whose input terminal is a diode D.
1, the output terminal is connected to the positive side of the secondary winding of the transformer T, and the output terminal is connected to the fixed resistor R5, R connected in series with the secondary winding.
6 through a capacitor C1.

2 is an amplification transistor, its base is connected to the point a, its emitter is connected to the positive side of the secondary winding via a fixed resistor R7, and its collector is connected to the negative side of the secondary winding via a fixed resistor R8. and constitutes a bias circuit.

A capacitor C2 and a diode D2 are connected to the collector of the transistor 9, and a smoothing capacitor C3 and variable resistors R13t and R15 are connected between the collector of the transistor and the secondary winding.
R17t R19 and fixed resistance R14゜R162RIB
A voltage dividing resistor consisting of tR20 is connected.

3, 4, 5, and 6 are reverse blocking three-terminal thyristors, each with its cathode on the negative side of the secondary winding, and the gate of thyristor 6 between variable resistor R19 and fixed resistor R20. The gate of thyristor 4 is connected between R17 and fixed resistor R18, and the gate of thyristor 3 is connected between variable resistor R15 and fixed resistor 'Rta, and between variable resistor R13.

Rg t R101R11t R12 is a fixed resistor connected to the anode of the thyristor 6 and the output terminal of the rectifier bridge 7.

The anode of the thyristor 5 is connected between the resistors R0 and RIO, and the anode of the thyristor 4 is connected to the resistor RIO'! :The anode of the thyristor 3 is connected between R11 and the rectifier bridge is connected between the resistors R11 and R12.
3, D4, D5.

One input terminal A is connected to the power supply 9 through a load 8 such as a heater, and the output terminal C is connected to the negative side of the secondary winding, and the other input terminal 2 is connected to the power supply 1 through a capacitor C4.
Connected to 0.

A triac (bidirectional thyristor) 11 is connected in series to power supplies 9 and 10 via a load 8, and its gate is connected to a diac (constant voltage conduction element) 12.

The positive side of the diac 12 is connected between the other input terminal 2 of the rectifying bridge 7 and a capacitor C4.

To explain the operation of the above circuit configuration, a pulsating voltage half-wave rectified by a diode D1 is applied to a bridge circuit 1 having a variable resistance element R1 such as a humidity sensor on one side via an output voltage of a transformer T.

An unbalanced voltage corresponding to the humidity of the control section is generated at the signal end of the bridge circuit 1, and a change in this unbalanced voltage is transmitted to the base of the transistor 2 via the capacitor C1.

A DC bias is applied to the transistor 2 through resistors R, R6, R7, and R8, and the change in base potential is amplified according to the change in base potential.

This amplified variation passes through a capacitor C2 and is taken out as an AC component, rectified by a diode D2, and used as a DC component.

Thyristors 3, 4, 5, and 6 are set to conduct in the order of 6 to 3, and when the change in the DC component is the smallest, that is, when the humidity is the lowest in the humidity detection range of variable resistance element R1, thyristor 6 is turned on. A signal is applied to the gate to make the thyristor 6 conductive.

As a result, the resistors R9, Rlo, R11, and R1□ are connected in series, and the capacitor C4 is charged through these resistors and the rectifying bridge 7, so that the voltage at both ends becomes low.

When the breakover voltage of triac 12 is reached, capacitor C4 partially discharges and provides a signal to the gate of triac 11.

As a result, an ignition pulse signal is applied to the triac 11 and the load 8 is made conductive.

When the thyristor 6 is conductive, the resistors R0 to R1□ are connected in series, so the resistance value is maximum, and the resistor R0
, Rlo, RB, the time constant of R12 and the capacitor C4 makes the triac 11 conductive.

In this case, the load voltage waveform becomes as shown at the beginning of Figure 2, and the power becomes the minimum.

Also, when the thyristor 5 becomes conductive due to a change in humidity, the cathode side of the thyristor 5 goes to a high potential, and the cathode side of the thyristor 6 goes to a high potential through the line connecting the cathodes of the thyristors 5 and 6, and the thyristor 6
becomes non-conductive.

In this case, resistors R1o, R11, R1□ and capacitor C4
The sitri-ac 11 is made conductive according to the time constant of .

When the thyristor 4 becomes conductive, the cathode of the thyristor 5 becomes high potential through the line connecting the cathodes of the thyristor 4 and the thyristor 5, and the thyristor 5 becomes non-conductive.

In this case, the triac 11 is made conductive by the time constant of the resistors R1□, R12 and the capacitor C4.

Next, when thyristor 3 becomes conductive, thyristor 4 becomes non-conductive.

In this case, when the DC component change is the largest, that is, when the humidity is highest in the humidity detection range of variable resistance element R1, the resistance value is the minimum, and the triac 11 is activated by the time constant of resistor R1□ and capacitor C4. Make conductive.

In this case, the load voltage waveform becomes as shown at the beginning of FIG. 2, and the power becomes maximum.

The characteristic curve for controlling the phase of a load in response to changes in humidity is difficult to grasp and may vary significantly depending on the location where the load is installed.

The present invention has been made in view of this point, and the control width and accuracy can be adjusted according to changes in humidity by variable resistors R13, R15, R1.
□, R1, fix the conduction angle with resistors R0, R1o, R10,
This is determined by R1°.

In addition, the present invention allows the conduction angle to be selected in any number of steps by increasing the number of thyristors, and also uses a variable resistance element such as a thermistor instead of a humidity sensor to reduce the load even when humidity changes. It is possible to control the power.

As described above, according to the present invention, any one of the thyristors is made conductive in accordance with the output of the bridge circuit, thereby changing the time constant to make the triac conductive, thereby controlling the time during which current is applied to the load. It is possible to supply power to the load that corresponds to the ambient humidity, which changes significantly depending on the seasonal changes or the location where the load is installed.If the load is an anti-condensation heater, it can be Condensation can be reliably prevented.

[Brief Description of the Drawings] Fig. 1 is an electric circuit diagram of an embodiment of the temperature control circuit of the present invention;
Figure A is the load voltage waveform diagram when the power is minimum, and Figure 1 is the load voltage waveform diagram when the power is maximum. 1... Bridge circuit, 2... Transistor, 3, 4
゜5.6...Thyristor, 8...Load, 11...
Triac, 12...Diac, R,...variable resistance element. c4-...Capacitor, R9, RIOt 'Rtt J
R12"' Fixed resistance, R13, R15, R17, R1
9...Variable resistance.

Claims (1)

[Claims] 1 A bridge circuit equipped with a variable resistance element such as a humidity sensor on one side, a transistor that amplifies the output of the circuit, and a gate connected to the midpoint of each voltage dividing resistor connected to the output terminal of the transistor. A plurality of reverse blocking three-terminal thyristors are connected between the anode of the last stage thyristor among these thyristors and one output terminal of a diode rectifier bridge, and the anodes of other thyristors are connected to the midpoint of each thyristor. a plurality of fixed resistors connected in series, a line that connects the cathodes of each of the thyristors to turn off the thyristors downstream of the turned-on thyristor, and the cathode of the first-stage thyristor and the other output terminal of the rectifier bridge. a load connected between one input terminal and one power supply terminal of the rectification bridge, and a capacitor connected between the other input terminal and the other power supply terminal of the rectification bridge. and a triac that is made conductive by a time constant between the capacitor and the plurality of fixed resistors, and one thyristor of the plurality of thyristors is made conductive according to the output of the bridge circuit to adjust the time constant. A hot water temperature control circuit characterized in that the electric power of the load is controlled by changing the conduction time to the triac.