JPH01152655A - Peltier element control circuit - Google Patents

Abstract

PURPOSE:To reduce the number of constituent elements which are necessary for performing temperature control and lessen electricity consumption in cooperation with the fact that no resistance is included in a live circuit, by setting the first, second, and third voltages in the order of decreasing voltage and controlling two transistors by outputs of a control voltage generating circuit. CONSTITUTION:Emitters of transistors 21 and 41 are commonly connected to one side of terminals of a Peltier element 10 and a collector of the NPN-type transistor 21 is connected to a drive voltage source having a voltage +V and the collector of the NPN-type transistor 41 is connected to the drive voltage source having the voltage -V; besides, other side of the terminals of the Peltier element 10 is earthed. In a state that a setting operation temperature of the Peltier element 10 reaches thermal equilibrium, an operational amplifier 201 generates its output voltage 0V. and the element is constructed so that it generates a positive voltage at its output when its ambient temperature is higher than the set operation temperature and it generates a negative voltage at its output when the ambient temperature is lower than the set operation temperature.

Description

[Detailed Description of the Invention] [Summary] Regarding a Peltier element control circuit that fixes the voltage at one terminal of a Peltier element and generates cooling and heat generation, the following points are to be solved in order to reduce circuit scale and power consumption. The driving current of the Beltier element is controlled by a control voltage generated from a control voltage generation circuit according to the deviation of the operating temperature of the controlled object whose temperature is controlled by the Peltier element from the set operating temperature. In the Peltier element control circuit that controls the first
providing first and second transistors connected in series between a power supply terminal of a drive voltage and a power supply terminal of a third drive voltage;
The Vertier element is connected between the connection point of both the transistors and the power supply terminal of the second drive voltage, and the first... The second and third drive voltages are set to higher voltage values in this order, and both transistors are controlled by the output of the control voltage generation circuit.

[Industrial application field]

The present invention relates to a Peltier element control circuit that fixes one terminal voltage of a Beltier element to a fixed potential and causes cooling and heat generation thereto.

In semiconductor devices, etc., the operating characteristics of the device are temperature dependent as a characteristic inherent to the device, so even if the ambient temperature of the device fluctuates, from the perspective of stabilizing the operation of the device, the device can be kept at the set operating temperature. Means for stabilizing the device operating temperature is provided for the device so that it always operates at a constant temperature. For example, when a laser diode is used for signal transmission, a Vertier element is used to keep the operating temperature of the laser diode constant even when the ambient temperature changes in order to enable easy reception on the receiving side and extend the transmission path length. That's what I do.

[Conventional technology]

As a Peltier element control circuit for controlling the operating temperature of the laser diode as described above, there is a circuit as shown in FIG. In this figure, lO is a Bertier element,
Its structure, as shown in FIG. 6, is well known in the art.

The Bertier element IO absorbs heat when a current flows from its constituent metal A to its constituent metal B, and generates heat when the direction of current flow is reversed. Then, an object whose temperature is controlled by the Bertier element IO, for example, a laser diode 12
is the heat exchange surface 10 of the Beltier element 10. Fixed on top. Further, a thermistor 14 is fixed on the heat exchange surface 10+. This thermistor 14 constitutes one circuit side of a bridge circuit 16 shown in FIG. The set operating temperature converted voltage (reference voltage) V□f of the laser diode 12 is output from the terminal 16A of the bridge circuit 16, and the terminal 1
6. to operating temperature-converted voltage v× of laser diode 12
is output.

These two mold pressures Vl'! f+VX is an operational amplifier 18c.

18h. When the operating temperature of the laser diode 12 rises above the set operating temperature, the voltage V,. ,>When the voltage becomes 8, the NPN transistor TR1 is turned on and the NPN
A control voltage is output from operational amplifier 18c that changes the conductivity of PN transistor TR3 to a value that achieves the temperature control objective. In this way, the current passed through the Bertier element 10 is from the metal A to the metal B, so that the laser diode 12 is cooled and its operating temperature is lowered.

As the control voltage decreases, the control voltage is also changed to a value that allows the current flowing through the Vertier element 10 to reach a thermal equilibrium state at the set operating temperature of the laser diode 12.

Conversely, when the operating temperature of the laser diode 12 falls below the set operating temperature, the voltage v0. <When the voltage Vx is reached, the operational amplifier 18. A control voltage is generated from. This control voltage is N
The PN transistor TR2 is turned on to control the current value of the NPN transistor TR4. In this way, the direction of the current flowing through the Bertier element 10 is opposite to that in the case of the temperature increase described above, so the laser diode 12 is heated and its operating temperature increases. In this case, the applied current is also changed to a value that allows the Bertier element 10 to enter a thermal equilibrium state at the set operating temperature (see FIG. 7).

Temperature control as described above allows laser diode 12 to operate at its set operating temperature.

[Problem that the invention seeks to solve]

In this conventional circuit, two operational amplifiers 18c and 18 are used to control the current value of the energizing current and to switch the energizing direction in order to cause the Bertier element 10 to have a heat generating function or an endothermic function.
h and four NPN transistors TRI, TR2, T
Since R3 and TR4 are required, the circuit scale becomes large and a large mounting area is required. Since two transistors are interposed in the switched current-carrying branch, not only does that consume power, but no matter which current-carrying branch is formed, the current-carrying branch is Since a resistor is involved, power consumption there inevitably occurs. In addition, due to the large number of series-connected elements entering the current-carrying branch, the driving voltage of the circuit must be increased.

The present invention was created in view of such problems, and its purpose is to provide a Peltier element control circuit that can achieve desired temperature control while reducing circuit scale and power consumption. do.

[Means for solving problems]

FIG. 1 shows a basic configuration diagram of the present invention. In this diagram,
Reference numeral 2.4 denotes first and second transistors connected in series between the power supply terminal 5 for the first drive voltage and the power supply terminal 7 for the third drive voltage. 10 is a Peltier element, and this element 10 connects the connection point 3 between the first transistor 2 and the second transistor 4 and the power supply terminal 9 for the third drive voltage.
is connected between. And the above-mentioned 1. The second and third drive voltages are set to higher voltage values in this order. The output of the control voltage generation circuit 20 causes both the transistors 2
, 4 was configured to control the circuit of the present invention. The control voltage generation circuit 20 generates a control voltage that indicates the direction and degree of change in the operating temperature of the controlled object relative to the set operating temperature.

[For production]

When the operating temperature of the controlled object changes from its set operating temperature, the control voltage generation circuit 20 generates a control voltage that represents the direction and degree of the change.

Depending on the polarity of the control voltage generated, both transistors 2 or 4 are turned on and their conductivity corresponds to the value of the control voltage. Therefore, the drive current controlled by the transistor 2 or 4 causes the Peltier element 10 to generate an amount of heat that causes the temperature change to return to the original state. Thus, the controlled object can always operate at its set operating temperature.

In order to achieve this temperature control, as is clear from the above, in addition to starting and stopping energization and controlling the amount of energization using a single transistor, the circuit also requires a conventional resistor. Since it does not contain , power consumption is reduced. In addition, one control voltage generation circuit is sufficient to control the transistors for this purpose, resulting in a reduction in circuit scale. Since the number of elements connected in series between the drive voltages is reduced, this helps in lowering the drive voltage.

〔Example〕

FIG. 2 shows an embodiment of the invention. In this figure, 2
．． is an NPN transistor; 4. are PNP transistors, and the emitters of these transistors 2+ and 4+ are commonly connected to one terminal of the Peltier element 10. The collector of the NPN transistor 21 is connected to a +V volt driving voltage source, the collector of the PNP transistor 4 is connected to a 1 volt driving voltage source, while the other terminal of the Peltier element 10 is grounded.

Reference numeral 20 denotes an operational amplifier constituting the control voltage generating circuit 20, whose non-inverting input is connected to the terminal 16a of the bridge circuit 16 shown in FIG. 5, and its inverting input is connected to the terminal 16B of the bridge circuit 16.

The operational amplifier 201 generates a voltage of 0 volts at its output in a thermal equilibrium state at the set operating temperature of the Peltier element 10, a positive voltage when the ambient temperature rises above the set operating temperature, and a positive voltage when the ambient temperature rises above the set operating temperature. The configuration is such that a negative voltage is generated at the output when the voltage drops.

The operation of this Peltier element control circuit is as follows.

If the ambient temperature of the laser diode 12 increases due to an increase in the outside temperature, etc., the resistance value of the thermistor 14, which is located near the laser diode l2 and responds to the temperature increase, decreases, and the reference voltage Vr*f>operates. Temperature conversion voltage■8
Therefore, the control voltage generation circuit 20. outputs a positive voltage sufficient to return the temperature increase to the thermal equilibrium state. This voltage causes the NPN transistor 2. is turned on, and a current flows through the Beltier element 10 in a direction that causes the Beltier element 10 to exhibit a cooling effect. The value of the current is determined by the voltage value applied to the base of transistor 2I. The voltage value gradually decreases as the temperature decreases due to the cooling effect generated in the Vertier element 10, and settles to a constant value.

Conversely, if the operating temperature of the laser diode 12 drops for some reason, in this case the thermistor 14
Since the resistance value of the control voltage generating circuit 20. increases, the operating temperature equivalent voltage vx>the reference voltage V rat, and a negative voltage sufficient to return the temperature drop to the thermal equilibrium state is applied to the control voltage generating circuit 20. generated from. This negative voltage is applied to the PNP transistor 4
．． is turned on, a current flows through the Beltier element 10 in a direction that produces a heating effect, and the operating temperature of the Beltier element 10 gradually decreases. The voltage applied to the base of the PNP transistor 41 in this case is generated in substantially the same manner as in the case of temperature rise, except for its polarity.

Thus, this circuit maintains the operating temperature of laser diode 12 at its set operating temperature, even if the operating temperature of laser diode 12 rises or falls above its set operating temperature.

As is clear from the above, this temperature control requires 1
Since it is sufficient to use one operational amplifier and two transistors as its main parts, the above-described temperature control can be achieved with a reduction in the number of components and power consumption. Grounding the other terminal of the Beltier element 10 reduces the number of lead wires.

FIG. 3 shows another embodiment, in which the fixed operating voltage applied to the Bertier element 10 is raised by a predetermined value from ground potential to +v, and the lower voltage is +v2 volts. At the same time, the drive voltage applied to the collector of the PNP transistor 41 is changed from -vI volts to the ground potential, and the control voltage generated from the control voltage generation circuit 20□ is changed to a value determined according to the change in the above two drive voltage levels. There is a difference from the embodiment in FIG. 2 in that only the following changes can be made. This difference can be solved by generating the control voltage as a voltage higher than the ground potential, so the operational amplifier 2
As for the power supply voltage to 0g, only the positive side voltage 1v1 is sufficient.

Since such a change in drive voltage does not cause any essential change in the operation of the circuit, the circuit operation associated with this change can be easily understood by referring to the above explanation, so the detailed explanation will not be given. Don't repeat explanations.

[Effects of the Invention] As described above, according to the present invention, since the start and stop of energization to the Beltier element and the control of the amount of energization are performed by a single element, it is possible to control the temperature of the object to be controlled. The number of components required for this is small, and the power consumption is also reduced because the current-carrying circuit does not include a resistor. Therefore, advantages can also be obtained in terms of implementation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of the present invention, FIG. 2 is a diagram showing one embodiment of the present invention, FIG. 3 is a diagram showing another embodiment of the present invention, and FIG. 4 is a diagram showing conventional Peltier element control. FIG. 5 is a diagram showing a circuit for generating a set operating temperature-converted voltage and an operating temperature-converted voltage; FIG. 6 is a structural diagram of a Beltier element; and FIG. 7 is a control characteristic curve diagram of a Beltier element. 1 to 3, 2.4 is a transistor (NPN type transistor 2,
PNP type transistor 41), 5.7.9 is a power supply terminal, 10 is a Bertier element, 20 is a control voltage generation circuit (operational amplifier 201.20□)
It is. / 1st day's original (K type product Figure 1 +, 1st day's - Torakata color example Figure 2 Hondo Sun Moon stick implementation 4 rows Figure 3 Figure 5 ~ Luce element ÷ opening Figure 5 Figure 6/'elL nae 1-) control frame 凰 - 穆concave Figure 7

Claims (3)

[Claims] (1) The control voltage generated from the control voltage generation circuit (20) is used to control the Peltier element (10) according to the deviation of the operating temperature of the controlled object whose temperature is controlled by the Peltier element (10) from the set operating temperature. In a Peltier element control circuit that controls a drive current, first and second transistors ( 2, 4), and both the transistors (2, 4) are provided.
4) connection point (3) and the second drive voltage power supply terminal (9)
The Peltier element (10) is connected between the
A Peltier device characterized in that the first, second, and third drive voltages are set as high voltage values in this order, and both the transistors (2, 4) are controlled by the output of the control voltage generation circuit (20). Element control circuit. (2) The Peltier element control circuit according to claim 1, wherein the second drive voltage is applied as a ground potential. (3) The second driving voltage is a preset positive driving voltage between the positive first driving voltage and the third driving voltage given as a ground potential. The Peltier element control circuit according to scope 1.