JPH03240110A - Low voltage type temperature controller - Google Patents

Abstract

PURPOSE:To reduce the power consumption of a temperature controller by providing an output circuit of a low power consumption type and a relay which switches reciprocally the connecting direction between the positive/negative output terminals of the output circuit and a load input terminal. CONSTITUTION:When the temperature detected by a sensor is not equal to a set level, a PI control part 1 outputs a positive or negative DC voltage signal proportional to the error between both temperatures. An output circuit 3 supplies a drive current between a positive terminal 10 and a negative terminal 11 with use of the voltage necessary for control of a load. At the same time, polarity detection circuit 4 turns on or off a relay 5 in response to the positive or negative output of the part 1. Thus the relay 5 is switched so that the currents supplied from both terminals 10 and 11 of the circuit 3 flow to the load in the reciprocal direction. Therefore the circuit 3 just outputs a current of the absolute value regardless of the reciprocal flowing direction of the current. As a result, the low power consumption type control circuits and elements like a PWM control circuit 12, an FET 14, etc., are available. Thus the power consumption is reduced for a temperature controller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a temperature control device for equipment whose temperature is controlled by direct current voltage, such as a Bertier effect element for controlling a semiconductor laser.

(Prior Art) The oscillation wavelength of a semiconductor laser depends on the temperature, and as shown in FIG. 2, the oscillation wavelength changes by about 0.0°C with a temperature change of 1°C. O7n
Since the temperature varies by m, it is necessary to strictly control the temperature to improve measurement accuracy.

For this reason, conventional temperature control circuits are implemented using the one power supply system shown in FIG. 3 and the two power supply system shown in FIG. 4.

The conventional temperature control circuit shown in FIG.
An output temperature signal is input, and a DC control voltage of a predetermined magnitude and positive or negative value is output in accordance with the temperature difference between the detected temperature and the set temperature and the polarity.

In the above temperature control circuit, the PI control circuit (
The output signal of 1) is sent to two control circuits (18
)(19) will be done manually.

One control circuit (18) outputs a DC voltage when the input terminal is positive, and the other control circuit (19) outputs a DC voltage when the input voltage is negative.

The drive circuit (23) includes a DC power supply (20) and four transistors Q1, Q2, Q3, and Q4, and has an output terminal a.
, b in the positive direction or in the negative direction. P ■
When the control circuit (1) outputs a negative DC voltage, one control circuit (19) outputs a signal and the transistor Q,...
Excite Q2, form a circuit that flows through the power source (20), Ql, terminal Aa, load, terminal bB, and Q2, and cool the load. When the PI control circuit (1) outputs a positive DC voltage, the other control circuit (18) outputs a signal to excite transistors Q3 and Q4, and the power supply (20), Q3,
A circuit flowing through terminal Bb, the load, and terminal aA1Q4 is formed to cause the load to generate heat.

(Problem to be solved) In both of the above conventional circuits, the current flowing to the load is controlled by the voltage drop of the two transistors, so power is consumed by the voltage drop of the transistor. .

A voltage of 0.6 V is sufficient to control the cooling element, but the power supply must be 2.6 V or higher to compensate for the voltage drop.

Moreover, such low voltage power supplies are usually inefficient. There is a 5V type as the minimum power supply commonly used.
In that case, 5-0.6=4.4V was wasted in the transistor.

The conventional temperature control circuit shown in FIG. 4 includes a PI control circuit (1), two power supplies (21) (22), and two transistors Q6 and Q6 connected with different polarities. When either one of the transistors is excited in response to the control signal of 1), a-1-b or b
-1-a direction. This embodiment also has the problem of voltage drop across the transistors and the need for two power supplies.

The present invention reveals a temperature control circuit with low power consumption.

(Structure) The present invention provides a low power consumption type output circuit (3) that outputs a predetermined DC voltage signal in accordance with the magnitude of the output signal of the P, I control circuit (1), and the output circuit (3). Positive and negative output terminals (1
0) A relay (5) that switches the connection direction between forward and reverse to connect (11) to the input terminal of the load (8), and a relay (5) connected to the relay (5) and corresponding to the polarity of the control unit output signal It has a polarity detection circuit (4) that controls the drive of the relay.

(Function) When the temperature detected by the sensor deviates from the set temperature, the control section (1) outputs a positive or negative DC voltage signal proportional to the amount of deviation.

Corresponding to the magnitude of the control section output, the output circuit (3) generates a voltage (approximately 0.0.
Outputs the drive current at 6 V).

On the other hand, a polarity detection circuit (4) corresponds to the positive or negative of the control unit output.
switches the relay (5) on or off so that the current from the positive and negative terminals (10) (11) of the output circuit (3) flows in the positive direction or in the reverse direction with respect to the load (8).

(Effect) Since the output circuit (3) only outputs the absolute value of current regardless of whether the current flow direction is positive or reverse, it is Power consumption type control circuits and elements can be used.

Furthermore, since the current direction for the load is switched by the relay (5), no power is consumed at the relay contacts, and a circuit with extremely low voltage drop and power consumption can be achieved. Therefore, even if the voltage of the power supply (13) is a commonly used 5V power supply, it can be converted to 0.6V, which is necessary for controlling the cooling element, without wasting power.

(Example) The following example was performed on a current control circuit for a cooling element of a semiconductor laser device, but the object of the present invention is not limited to the above, and is applicable to temperature control circuits such as air conditioning equipment, refrigeration equipment, etc. Of course, it can be applied to all types of equipment.

The semiconductor device operates a semiconductor laser using a constant current drive circuit (24
) to oscillate laser light, and the cooling element (8) is controlled by a current control circuit to control the oscillation wavelength of the laser light.

A sensor (not shown) provided at a suitable location detects the temperature of the semiconductor laser or its surroundings and inputs the detected temperature to the PI control circuit (1). When the detected temperature is equal to the set temperature, the detection part (
1) either does not output, or outputs a positive or negative DC voltage when both temperatures are different from each other. The output voltage signal of the detection section (1) is transmitted to the absolute value circuit (2) and the polarity detection circuit (4).
The absolute value circuit (2) inputs a voltage having a strength corresponding to the difference between the detected temperature and the set temperature to the output circuit (3).

The output circuit (3) includes a PWM control circuit (12) and an FET (1
4), a switching circuit consisting of a diode (15), and a smoothing circuit consisting of an inductance (16) and a capacitance (17), which converts a voltage of a predetermined pulse width into 2 in response to an input signal from an absolute value circuit (2). Two terminals (1
0a) Output to (10b). The terminal (10a) (
10b) are respectively other terminals (11a011b) (llb)
Correspondingly, by switching the contact pieces (9a) and (9b), the connections between the input and output terminals a and b to the cooling element (8) are switched, and the current direction can be changed between forward and reverse.

The switching operation of the contacts (9a) and (9b) is performed using the relay (5).
) is driven by.

The polarity of the output signal of the PI control circuit (1) is detected by a known polarity detection circuit (4), and a transistor (6) is detected.
The relay (5) is regulated by turning on and off.

There is almost no power consumption in the PWM control circuit (12), switching circuit, and relay contacts (10) (11).
A current control circuit with low power consumption was formed.

The implementation of the present invention is not limited to the above description, and can be modified within the scope of the claims.

For example, the PI control circuit (1) can be changed to a PID control circuit, and the FET (14) can be changed to a transistor or other circuit.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram of a current control circuit according to the present invention,
FIG. 2 is a graph showing the relationship between the oscillation wavelength of a semiconductor laser and the temperature, and FIGS. 3 and 4 show a conventional temperature control device. (1)...detection section (3)...output circuit (5)
...Relay (13)...Power supply (8)...
Load

Claims (1)

[Claims] (1) A control section (1) that outputs a DC voltage signal of a predetermined polarity and a predetermined voltage according to the difference between the detected temperature and the set temperature and the direction to be controlled; A low power consumption type output circuit (3) that outputs a DC voltage signal, and the connection direction is positive to connect the positive and negative output terminals (10) and (11) of the output circuit (3) to the input terminal of the load (8). It is characterized by comprising a relay (5) that switches in the opposite direction, and a polarity detection circuit (4) that is connected to the relay (5) and controls the drive of the relay in accordance with the polarity of the control unit output signal. Low voltage temperature control device.