JPH10171541A - Temperature controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the response characteristic of a temperature controller having slow heat transmission response and the stability of temperature after arrival at a prescribed temperature. SOLUTION: This temperature controller is provided with a heating circuit 14 for heating a heater 12 based on a compared result between temperature measuring voltage and temperature setting voltage, a temperature sensor 16 for detecting the temperature of the heater 12, a temperature measuring circuit connected to the sensor 16 and capable of applying temperature measuring voltage to the circuit 14, and a temperature setting circuit 20 for applying temperature setting voltage corresponding to a prescribed temperature to the circuit 14. An adder 30 adds a continuous wave having periodicity to the output of the circuit 18 or the circuit 20 to control the heater 12 at the prescried temperature. The continuous wave is a triangular wave having a period selected by 1/5 the heat transmission response time of the heater 12 at a 50% duty ratio and having a peak value selected between about 1/2 to 1/20 of a voltage comparing range. The period or level of the continuous wave is changed by an integrator for detecting the terminal voltage of the heater 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating circuit for heating a heater and a temperature control device for maintaining a temperature at a predetermined temperature while measuring a temperature with a temperature sensor.

[0002]

2. Description of the Related Art FIG. 1 shows a block diagram of a conventional temperature control device. The temperature control device includes a heating circuit 14 for heating the heater 12, a temperature sensor 16 for detecting the temperature of the heater 12, and a temperature measurement circuit connected to the temperature sensor 16 for supplying a temperature measurement voltage to the heating circuit 14. And a heating circuit 20 for supplying a heating voltage corresponding to a predetermined temperature to the heating circuit 14.

The heating circuit 14 comprises a comparator 22 for comparing output voltages of the temperature measuring circuit 18 and the temperature setting circuit 20, and a comparator 22.
And an emitter follower 24 for heating the heater 12 by current-amplifying the output of the heater 12. The heating circuit 20 outputs a desired predetermined temperature as a heating voltage Vs of, for example, 10 mV / ° C.

A temperature measuring circuit 18 measures the temperature detected by the temperature sensor 16 to a temperature measuring voltage V of the same level as the temperature setting circuit 20.
Output as t. In the heating circuit 14, the heating voltage V
s and the measured voltage Vt are compared by the comparator 22. If the set temperature voltage Vs is larger, power is supplied to the heater 12, and the measured temperature voltage Vt is supplied to the heater 12.
If t is larger, so-called on / off control for interrupting power supply to the heater 12 is performed.

Further, the second temperature control device shown in FIG. 3 includes a temperature setting circuit 20 and a temperature measuring circuit 18 as in the case of FIG. However, the heating circuit 14 includes a first amplifier 22 that amplifies a difference between a set temperature voltage corresponding to a predetermined temperature and a temperature measurement voltage,
A second amplifier 23 that operates so that the output voltage of the amplifier becomes equal to the terminal voltage of the heater 12 is provided, and a heating control circuit of a proportional control type is configured.

[0006]

FIG. 2 shows the relationship between the control voltage and the temperature of the temperature control device shown in FIG. Since this temperature control device is an on / off control, the speed of reaching the predetermined temperature is relatively fast since the power is kept on until the temperature reaches the predetermined temperature when the power is turned on.

However, when the measured voltage Vt is equal to the set temperature V
Even when s exceeds s, there is a problem that the temperature continues to rise for a while due to a time lag between the heating by the heater 12 and the measurement by the temperature sensor 16, and the actual temperature causes an overshoot. On the other hand, when the temperature is decreasing, the measured temperature does not increase for a while even when the power supply to the heater 12 is started, and an undershoot occurs. Therefore, the time until the temperature actually stabilizes becomes long.

Further, since the temperature control device has a heat capacity, even if the heating of the heater 12 is stopped, a heat transfer response time tm is required until the measured temperature of the temperature sensor 16 starts to decrease. For this reason, even after the temperature once reaches a predetermined temperature, on / off is always repeated at intervals corresponding to the heat transfer response time of the device, so that there is a problem that a long heat transfer response time tm causes temperature fluctuation.

This temperature fluctuation increases as the heat transfer response time tm increases. Further, in the second conventional example, although the temperature stability at a predetermined temperature is good by increasing the gain of the first amplifier, there is a problem that the time to reach the predetermined temperature when the power is turned on is conversely delayed.

The present invention has been made to solve such a problem, and the response at the time of turning on the power is relatively quick.
An object of the present invention is to provide a temperature control device having good temperature stability at a predetermined temperature.

[0011]

In order to achieve the above object, a temperature control device according to the present invention comprises a heating circuit for heating a heater based on a comparison result of a measured voltage and a set temperature, and a heating circuit for heating the heater. A temperature sensor connected to the temperature sensor for detecting the temperature of the temperature, supplying the temperature measurement voltage to the heating circuit, and supplying a temperature corresponding to a predetermined temperature to the heating circuit. A circuit, and an adder for adding a periodic continuous wave to the output of the temperature measuring circuit or the temperature setting circuit to control the heater to the predetermined temperature.

The continuous wave is a triangular wave, especially a duty ratio of 5
0%, having a cycle selected to be 1/5 or less of the heat transfer response time of the heater, and from about 1/2 to 1/2 of the voltage comparison range.
It may be a triangular wave having a peak value selected between about 0, or the period or level may be changed by a low-pass filter or an integrator that detects the terminal voltage of the heater.

Therefore, according to the present invention, a continuous wave set at a frequency faster than the heat transfer response time of the apparatus and a peak value smaller than the temperature control voltage range is added to the output voltage of the temperature measuring circuit or the temperature setting circuit. The voltage waveform obtained by adding the continuous waves is compared with the other DC output voltage to heat the heater.

[0014]

FIG. 4 is a conceptual diagram of voltage comparison and heating control of a temperature control device according to the present invention. Here, it is assumed that the voltage of the continuous triangular wave is added to the temperature measurement voltage Vt of the temperature measurement circuit, and the output voltage of the adder is the temperature measurement voltage Vt ′.

Immediately after the power is turned on, since the heater 12 is cold as shown in FIG. 4A, the temperature measurement voltage Vt 'is lower than the temperature setting voltage Vs of the temperature setting circuit 20, and power supply to the heater 12 is not performed. It is always on and will heat with maximum power.

When the temperature measurement voltage Vt 'rises due to the heating of the heater 12 and reaches near a predetermined temperature, the voltage comparison is performed in such a manner that the added triangular wave voltage crosses the temperature setting voltage Vs as shown in FIG. Then, the power supply to the heater 12 is turned on / off. At this time, if the temperature measurement voltage Vt of the original temperature measurement circuit is still smaller than the temperature setting voltage Vs, only the top of the triangular wave of the temperature measurement voltage Vt1 crosses the temperature setting voltage Vs,
The ON / OFF timing of the power supply to the heater 12 is longer in the ON state than in the OFF state.

That is, when the measured temperature approaches the predetermined temperature, overheating can be prevented by intermittently turning on / off the heating of the heater 12. After the temperature is stabilized at the predetermined temperature, as shown in FIG.
The on / off operation is performed at the center of the triangular wave, that is, at the position of the temperature measurement voltage Vt. Since this on / off has the same cycle as the triangular wave with a duty ratio of 50%, when the cycle ta of the triangular wave is sufficiently shorter than the heat transfer response of the device, a control delay due to the heat transfer response of the device may occur. Instead, the temperature is stably maintained at a predetermined temperature.

The above description is an example in the case where the measured temperature is equal to or lower than the predetermined temperature. However, even when the measured temperature is equal to or higher than the predetermined temperature, the same operation works, so that undershoot is prevented and the temperature stability is improved. Can be planned.

FIG. 5 is a block diagram of a temperature control device according to a first embodiment of the present invention. The temperature control device of the present invention includes a heating circuit 14 for heating the heater 12 and a temperature sensor 16 for detecting the temperature of the heater 12. The temperature sensor 16 is mounted near the heater 12, measures the temperature of the temperature control device by the temperature measurement circuit 18, and outputs the temperature at a temperature measurement voltage Vt of, for example, 10 mV / ° C. The temperature sensor 16 is connected to a temperature measurement circuit 18 that converts the detected temperature into a temperature measurement voltage.

On the other hand, the non-inverting input terminal of the heating circuit 14
A heating circuit 20 for supplying a heating voltage corresponding to a predetermined temperature is connected. This temperature setting circuit 20 converts a desired predetermined temperature into a voltage value having the same level as the output voltage and outputs the same. This output voltage, that is, the set voltage Vs, is output from the comparator 2
2 is input to the non-inverting input terminal.

According to the present invention, the temperature measurement voltage of the temperature measurement circuit 18 is applied to the first input terminal of the adder 30. The output of the triangular wave generating circuit 32 that generates a triangular wave having a predetermined period and a peak value is applied to a second input terminal of the adder 30, and the output terminal is connected to the inverting input terminal of the heating circuit 14.

Therefore, the triangular wave generated from the triangular wave generating circuit 32 is added to the output voltage of the temperature measuring circuit 18 in the adder 30 and is supplied to the inverting input terminal of the comparator 22 in the heating circuit 14 as the temperature measuring voltage Vt '. Is entered. The comparator 22
Compare the temperature setting voltage Vs with the temperature measurement voltage Vt ′, and determine the temperature setting voltage Vs
Is larger, the power is supplied to the heater 12 via the emitter follower 24.

This triangular wave has a duty ratio of 50%,
Generated continuously at the same frequency and level. The frequency and level of the triangular wave are 1/1 of the heat transfer response time tm of the device.
5 or less, and about 1 /
It has a peak value selected between about 2 and 1/20. For example, when the heat transfer response time tm of the device is 1 second and the voltage comparison range is 10 V, the frequency is 100H.
z and the peak value are set to 2 Vp-p.

Here, by arbitrarily selecting the frequency and level of the triangular wave, the temperature control characteristics of the device can be freely determined, and the temperature fluctuation due to the original heat transfer response characteristics and the response characteristics can be improved. be able to.

FIG. 6 shows a block diagram of the second embodiment. In the above-described first embodiment, the continuous wave added to the output voltage of the temperature measuring circuit 18 has a constant frequency and level, whereas in the second embodiment, according to the heating state of the heater 12,
By changing this parameter, temperature control with a higher degree of freedom is performed.

In this embodiment, as in the first embodiment, a comparator 22, an emitter follower 24, and a heater 12 are provided in addition to a temperature setting circuit 20 and a temperature measuring circuit 18 using a temperature sensor 16.
, A triangular wave generating circuit 32, and an adder 30, and a low-pass filter or an integrator 34 is added.

Here, the triangular wave generating circuit 32 is a voltage controlled oscillator (VCO) or the like that can change the frequency and / or level of the output waveform by inputting an external voltage or current.

The load-side terminal of the heater 12 is connected to an integrator 34 for integrating a voltage waveform. This integrator 34
A high-frequency component contained in the terminal voltage waveform is removed, and a substantially DC voltage that gradually changes is output. This approximately DC voltage is
The triangular wave is applied to the control input terminal of the triangular wave generating circuit 32 to generate a triangular wave having a corresponding cycle or level.

For example, when the measured temperature is lower than the predetermined temperature as shown in FIG. 4A, the level of the triangular wave is reduced, and the power is supplied to the heater 12 until the measured temperature approximates the predetermined temperature. By changing the triangular wave so as to increase the level of the triangular wave when the temperature is stabilized at the predetermined temperature, the response time can be improved by shortening the time required to reach the predetermined temperature from power-on.

The waveform added to the output voltage of the temperature measuring circuit 18 is not necessarily a triangular wave as long as it is a waveform continuously generated at the same frequency and level with a duty ratio of 50%. , Sine waves and other waveforms can be substituted.

[0031]

As described above, according to the present invention, even if the temperature control device has a slow heat transfer response, the overshoot and the undershoot at the time of turning on the power are improved, the response characteristics are improved, and the temperature reaches a predetermined temperature. The stability of the temperature can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first conventional temperature control device.

FIG. 2 is a control conceptual diagram of the temperature control device of FIG. 1;

FIG. 3 is a block diagram of a temperature control device of a second conventional example.

FIG. 4 is a control conceptual diagram of the temperature control device according to the present invention.

FIG. 5 is a block diagram of the temperature control device according to the first embodiment of the present invention.

FIG. 6 is a block diagram of a temperature control device according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 12 heater 14 heating circuit 16 temperature sensor 18 temperature measuring circuit 20 temperature setting circuit 22 comparator 30 adder 32 triangular wave generating circuit 34 integrator

Claims (4)

[Claims] 1. A heating circuit for heating a heater based on a result of comparison between a measured voltage and a set temperature, a temperature sensor for detecting a temperature of the heater, and a temperature sensor connected to the temperature sensor for detecting the measured voltage. A temperature measuring circuit for supplying the heating circuit, a heating circuit for supplying the heating voltage corresponding to a predetermined temperature to the heating circuit, and a continuous wave having a periodicity in an output of the temperature measuring circuit or the heating circuit. A temperature control device comprising: an adder for controlling the heater to the predetermined temperature by adding. 2. The apparatus according to claim 1, wherein said continuous wave is a triangular wave. 3. The continuous wave has a duty ratio of 50%, has a period selected to be 1/5 or less of the heat transfer response time of the heater, and has a period of about 1/2 to 1/20 of a voltage comparison range. 2. The device according to claim 1, wherein the triangular wave has a peak value selected between the two. 4. The apparatus according to claim 1, wherein the continuous wave is changed in period or level by a low-pass filter or an integrator for detecting a terminal voltage of the heater.