JP2516912B2 - Temperature control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device capable of controlling the temperature of a target with high accuracy even when the outside air temperature changes.

Conventional Technology The conventional technology is shown in FIG. Conventionally, the controlled object 1 to be temperature-controlled is hermetically sealed with the container 2 and the radiation fins 3, and the inside is evacuated to remove the influence of the outside temperature on the controlled object 1. The controlled object 1 is fixed to the cooling plate 4, and the temperature of the controlled object 1 is detected by the temperature sensor 5 attached to the cooling plate 4. The temperature signal corresponding to the temperature from the temperature sensor 5 and the setting signal from the setting circuit 6 are compared by the comparison circuit 7,
A signal corresponding to the difference between them is output. The drive circuit 8 outputs a current proportional to the signal from the comparison circuit 7, and the Peltier element 9 heats or cools the cooling plate 4 and the control target 1 by the current from the drive circuit 8 to control the temperature of the control target 1. The temperature is set to a temperature corresponding to the setting signal from the setting circuit 6. The Peltier element 9 has two surfaces, and heat is carried from one surface to the other surface by passing an electric current, and as a result, one surface is cooled and the other surface is heated. For example, when the controlled object 1 is cooled, the surface of the Peltier element 9 on the side of the radiation fin 3 is heated, but the radiation fin 3 is attached to prevent the temperature from becoming high.

As described above, in the conventional technique, the surroundings of the controlled object 1 are evacuated to remove the effect of heat conduction by the air, the effect of the outside temperature is prevented, and the current to the Peltier element 9 is controlled. The temperature is set to the target value (Yamaguchi et al .: Temperature control device for semiconductor laser using Peltier element, Spectroscopic Research Vol. 32, No. 5, P328 (1983)).

However, such a vacuum device is very large, heavy, and expensive. If heat cannot be completely cut off using such a vacuum device, heat will flow from the outside toward the controlled object.

In the conventional technique, a current proportional to the difference between the temperature signal corresponding to the temperature of the controlled object from the temperature sensor and the setting signal from the setting circuit is passed through the Peltier element to proportionally control the temperature of the controlled object. Since it is proportional control, an error always occurs between the temperature of the controlled object and the set temperature determined by the setting circuit, and this error increases as the difference between the outside air temperature and the set temperature increases.

Therefore, in the conventional device, when the outside air temperature changes, the temperature of the controlled object deviates from the set temperature and cannot be kept constant. However, if the ratio of proportional control is increased,
Although the error can be reduced by that much, the control becomes unstable at the same time, and therefore there is a limit to the method of increasing the ratio to reduce the error.

Means for Solving Problems In order to solve the above-mentioned problems of the prior art, the present invention provides a temperature sensor for detecting the temperature of a controlled object, a setter for determining a target temperature, and a temperature sensor. A controller that outputs a current proportional to the difference between the temperature signal corresponding to the temperature of the control target and the setting signal corresponding to the target temperature from the setter; and a Peltier element that heats or cools the control target by the current from the controller. , And a mechanism section for thermally coupling the temperature sensor and the outside air.

Action In the prior art, the temperature determined by the setter (target temperature) is compared with the temperature of the control target detected by the temperature sensor (target temperature), and a current proportional to the difference is passed through the Peltier element to perform proportional control. ing. Since the control is proportional, the target temperature does not match the target temperature, and the target temperature deviates from the target temperature to the outside air temperature side. In the present invention, since the temperature sensor and the outside air are thermally coupled, a difference occurs between the temperature detected by the temperature sensor (detection temperature) and the temperature of the control target (true target temperature), and the detection is performed. The temperature deviates from the true target temperature to the outside temperature side. Then, the detected temperature and the target temperature are compared, and proportional control is performed as in the above-described conventional technique, but the detected temperature deviates from the target temperature to the outside air temperature side.

The difference between the true target temperature and the detected temperature changes depending on the degree of thermal coupling between the temperature sensor and the outside air (thermal coupling degree), and the difference between the target temperature and the detected temperature changes according to the ratio of proportional control. The true target temperature can be matched with the target temperature by appropriately adjusting the coupling ratio and the ratio of the proportional control.

Practical example When trying to set the temperature of the controlled object (target temperature) to the target temperature by proportional control as in the prior art, an error occurs between the target temperature and the target temperature, and the difference between the outside air temperature and the target temperature is generated. The larger is, the larger the error is (the fifth
Figure). In order to reduce this error, it is sufficient to increase the ratio of the proportional control, but if it is set too high, the control becomes unstable, so there is a limit to reducing the error.

In order to remove the error caused by such proportional control, proportional / integral control or proportional / integral / derivative control may be used, but in the present invention, it is possible to reduce the error while using proportional control.

One embodiment of the present invention is shown in FIG. The controlled object 11 is fixed to the cooling plate 12, the cooling plate 12 contacts one surface of the Peltier element 13, and the other surface of the Peltier element 13 has a radiation fin.
14 are in contact. By passing a current through the Peltier element 13 in this way, the controlled object 11 can be heated or cooled through the cooling plate 12. The heat insulating material 15 prevents heat from flowing into or out of the controlled object 11 or the like from the outside, and improves the efficiency of heating or cooling by the Peltier element 13. The temperature of the controlled object 11 is detected by the temperature sensor 16 through the cooling plate 12. The heat insulating material 15 is provided with a heat coupling portion 17 to thermally couple the outside air and the temperature sensor 16. Temperature detected by temperature sensor 16 (detected temperature)
The temperature signal corresponding to is input to the comparison circuit 19 together with the setting signal from the setting circuit 18 for determining the temperature (target temperature) to be set for the controlled object 11, and a signal proportional to the difference between the temperature signal and the setting signal is output. Output. The drive circuit 20 supplies a current proportional to the signal from the proportional circuit 19 to the Peltier element 13.

In this way, the temperature detected by the temperature sensor 16 is controlled so as to match the target temperature determined by the setting circuit 18.

However, since proportional control is performed, the detected temperature and the target temperature do not match, and the detected temperature deviates from the target temperature to the outside air temperature side, as in the conventional technique.

By the way, in the present invention, since the temperature sensor 16 and the outside air are thermally coupled through the thermal coupling portion 17, the temperature sensor 16
Unlike the temperature detected by and the temperature of the control target 11 (true target temperature), the true target temperature deviates from the detected temperature to a temperature opposite to the outside air temperature.

When the degree of thermal coupling of the thermal coupling portion 17 (the amount of heat that flows into the temperature sensor from the outside or the amount of heat that flows out from the temperature sensor to the outside) is very small, corresponding to the related art,
Since the temperature detected by the temperature sensor 16 and the true target temperature are equal, if the proportion of the proportional control is increased in order to match the true target temperature with the target temperature, the operation becomes unstable.

If the degree of thermal coupling is increased, the true target temperature shifts from the detected temperature to a temperature opposite to the outside air temperature as described above. This deviation is determined by the degree of thermal coupling. By the way, since the proportional control is performed on the detected temperature, the deviation of the detected temperature from the target temperature is related to the outside air temperature and the ratio of the proportional control, and does not depend on the thermal coupling degree. Therefore, if the ratio of proportional control is adjusted to bring the detected temperature close to the target temperature and the degree of thermal coupling is adjusted, the true target temperature and the target temperature can be matched.

This will be described in detail below with reference to FIG. When the degree of thermal coupling is small (Fig. 2 (a)), the deviation of the true target temperature from the detected temperature is small. When the outside air temperature departs from the target temperature, the detected temperature departs from the target temperature as shown in the figure. Further, since the deviation of the true target temperature from the detected temperature is small, in order to set the true target temperature to the target temperature even if the outside air temperature is far from the target temperature, the proportions are proportional as shown by points A → B → C in the figure. It is necessary to gradually increase the control ratio.

On the contrary, when the degree of coupling is large, the deviation of the true target temperature from the detected temperature is large. Therefore, contrary to the above case, even if the outside air temperature deviates from the target temperature, it is necessary to gradually reduce the ratio of the proportional control in order to set the true target temperature to the target temperature.

Therefore, if the thermal coupling degree is chosen to be an appropriate value, it is shown in Fig. 2 (b).
, Where the proportional control ratio is constant (point D)
Thus, even if the outside air temperature changes, the true target temperature can be set as the target temperature.

The above is the case where the outside air temperature is higher than the target temperature. Considering a case where the outside air temperature is higher than the target temperature by the same temperature and a case where the outside air temperature is lower than the target temperature, the deviations of the detected temperature and the true target temperature from the target temperature are equal (FIG. 2 (c)). Therefore, even if the outside air temperature is lower than the target temperature, if the ratio of the thermal coupling and proportional control is set to the optimum value in the above case, the true target temperature will be the target temperature even if the outside air temperature changes. Can be set.

3 and 4 show an embodiment of the thermal coupling portion 17. The heat coupling part 16 has a cylindrical shape, and as shown in FIG.
It consists of 22 and is incorporated into the insulation 15 and can be rotated as shown. The heat transfer section 21 is in close contact with the cooling plate 12, and the temperature sensor 16 can be thermally coupled to the outside air through the cooling plate 12. The heat insulating section 22 is for preventing the input and output of unnecessary heat. The heat transfer portion 21 can change the contact area with the cooling plate 12 by rotating as shown in FIG. 4 (a cross-sectional view of the AA ′ surface in FIG. 3 on the temperature sensor side). The degree of thermal coupling with the outside air can be adjusted.

EFFECTS OF THE INVENTION As described above, in the present invention, even if the outside air temperature changes, the deviation of the temperature of the controlled object from the target temperature can be reduced, although the proportional control method having a simple configuration is used. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a temperature control device according to an embodiment of the present invention, FIG. 2 is an operation explanatory diagram of the device, and FIGS. 3 and 4 are diagrams showing an embodiment of a thermal coupling portion in the device, FIG. 5 is an operation explanatory view of a conventional temperature control device, and FIG. 6 is a configuration diagram of the device. 13 …… Peltier element, 16 …… Temperature sensor, 17 …… Thermal coupling section, 18 …… Setting circuit, 19 …… Comparison circuit, 20 …… Drive circuit.

Claims (1)

(57) [Claims] 1. A temperature sensor for detecting the temperature of a controlled object,
A setter that determines the target temperature, a controller that outputs a current proportional to the difference between the signals from the temperature sensor and the setter, and a Peltier element that heats or cools the control target by the current from the controller. A temperature control device comprising: a temperature sensor and a mechanism part that thermally couples the temperature sensor with the outside air and makes the degree of thermal coupling variable.