JPH04227514A - Temperature controller - Google Patents

Abstract

PURPOSE:To prevent initial overshooting and speedily perform stable temperature control to target temperature. CONSTITUTION:A temperature detecting element is fitted in a heater 1 and its output is inputted to the '+' input terminal of a comparator 6. Six kind of voltage levels corresponding to six reference temperatures appear at the '-'input terminal of the comparator 6 in order op a time-division basis and flip-flops 9a-9f are set in order according to the comparison result of the comparator 6. A lighting control circuit 3 detects which temperature area the heater 1 is in from the outputs of the flip-flops 9a-9f and controls a lighting ratio according to the respective areas.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device that can accurately control a set temperature in accordance with the temperature of a controlled object.

0002

[Prior Art] Conventionally, the most commonly used temperature control device compares the temperature of a predetermined target to be controlled with the temperature of a heater, and if the temperature of the heater is lower, power is supplied to the heater. supply. Furthermore, when the temperature of the heater is higher, the power supply to the heater is stopped or reduced to suppress the rise in the temperature of the heater.

0003

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology has the following problems. In other words, depending on the set temperature of the controlled object, the heater is turned on or off.
Since the only control possible is whether the temperature is F or not, it is very rough and the overshoot with respect to the set temperature is large and unstable.

[0004] The present invention solves the above-mentioned problems and makes it possible to quickly and accurately control the target temperature.

[0005]

[Means for Solving the Problem] As a means for solving the problem, the present invention stores power supply control data stored in a storage means based on the reference temperature obtained from the comparison means, the detected temperature near the heating element, and the difference value. The device is equipped with temperature control means for selecting and controlling the power supply.

[0006]

[Operation] By means of the above means, the present invention can control the electric power supplied to the heater depending on the temperature range to which the object to be controlled belongs, and can stably control the temperature to the target temperature.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a temperature control device according to an embodiment of the present invention. In the figure, 1 is a heater;
A temperature detection element such as a thermistor is installed inside, and the output of the temperature control element is input to the + input terminal of the comparator 6. 2 is a power source that supplies power to the heater 1; 3 is a lighting control circuit that controls the power supplied to the heater 1; Here, the lighting ratio refers to the ratio of the operating time of the entire device including the heater to the lighting time of the heater 1, and in this embodiment, five types of lighting ratios are used as shown in FIG. Note that the shaded area in FIG. 2 means that the heater is turned on. 4 is a pulse generator that generates clock pulses, and 5 is a decoder that sequentially selects one of the six output terminals to make it conductive according to the clock pulses output from the pulse generator 4. Note that the reason why there are six outputs from the decoder 5 is because six reference temperatures are set in this embodiment. Resistors 8a to 8f are resistors 7
A voltage level corresponding to the reference temperature is created by the ratio of the resistance value to the reference temperature. That is, any one of the six reference temperatures is created by the ratio of the resistance values of the resistor 7 and the resistor 8f. Further, another reference temperature is created by the ratio of the resistance values of the resistor 7 and the resistor 8e, and other reference temperatures are created in the same manner.

Here, if the six reference temperatures are determined as shown in FIG. 3, the magnitude relationship of the resistance values of the six resistors 8a to 8f is 8f<8c<8e<8a<8d<8b. becomes. Therefore, as shown in FIG. 3, six voltage levels corresponding to the six reference temperatures are sequentially displayed at the negative terminal of the comparator 6 in a time-division manner. Comparator 6 is
The output signal of the temperature detection element provided in the heater 1 and the voltage levels corresponding to the six reference temperatures are compared in a time-sharing manner, and if the temperature of the heater 1 is higher, its output is is at a high level, and when the temperature of the heater 1 is lower, it is at a low level. 9a to 9f are all flip-flops (hereinafter referred to as FF), and are shown in FIG.
As shown in , 6 FFs are output from decoder 5.
One FF among 9a to 9f becomes active. Also,
A signal informing the comparison result from the comparator 6 is input to the FFs 9a to 9f, and the FFs that have become active are operated by the output from the comparator 6. Therefore, FF9a
.about.9f sequentially become active and operate in response to a signal notifying the comparison result obtained from the comparator 6 in a time-division manner. 10
, 11 and 12 are counters that count the number of clock pulses being output from the pulse generator 4 when the outputs from the FFs 9a and 9f are at high level. 19,
20 and 21 are memories that store the contents of counters 10, 11, and 12, respectively. Reference numerals 22 and 23 indicate determination circuits, which compare the output contents from the memories 19 and 20 with the contents stored in advance in the determination circuits 22 and 23, and output when the output contents of the memories 19 and 20 are smaller. Set the signal to high level. Similarly, 24 is also a determination circuit, but the determination circuit 24 stores two types of contents in advance and outputs three types of determination results. 13a and 1
3b is a counter that is cleared at the falling edge of the input signal from the differentiating circuit 18 and counts the clock pulses from the pulse generator 4 during the period when the input signal is at a high level. 1
4 is an OR circuit, and 15, 16 and 17 are inverters. Further, 18 is a differentiation circuit that differentiates the output signal of the FF 9a.

The temperature control section configured as described above performs the temperature control described below. That is, using reference temperatures a, b, c, d, and e, six regions [A, B, H, D, H, H] are provided as shown in FIG.
It detects in which region the temperature exists, and controls the lighting ratio according to the region in which the temperature exists. (Table 1) shows the area [A, B, H, D, H, H] and FF [9a, 9b
, 9c, 9d, 9e].

0010

[Table 1]

The lighting ratio control circuit 3 includes FFs [9a, 9b,
9c, 9d, 9e], it is detected in which range the temperature of the heater 1 exists. That is, FF [
If the outputs of FFs [9b, 9d, 9a] are L (low level) and the outputs of FFs [9e, 9c] are H (high level), the temperature of heater 1 exists in area 2. Detect. This detection is performed by resistors 8a to 8a as shown in FIG.
This is done after all 8f have been selected. When the lighting ratio control circuit 3 detects in which region the temperature of the heater 1 is present, it controls the lighting ratio according to each region as shown in FIG. In other words, heater 1 is placed in area C.
If there is a temperature of , the lighting ratio is 1/5,
If it exists in region A or F, the supply of power to heater 1 is completely stopped because the temperature is abnormally high or low. Note that the lighting ratio for each area is not limited to the numerical values shown in FIG. 2, and may be arbitrarily determined. By performing the temperature control as described above, the temperature of the heater 1 can be maintained at the reference temperature a, which is the set temperature, and the temperature ripple (difference between the reference temperature a and the temperature of the heater 1) can be reduced. can.

0012

As described above, the present invention selects and supplies power supply control data stored in the storage means based on the reference temperature obtained from the comparison means, the detected temperature near the heating element, and the difference value. Equipped with a temperature control means that executes power control, the rate of temperature change of the heater is determined, and the power supplied to the heater is controlled based on this determination result, which prevents initial overshoot and maintains the target temperature. On the other hand, stable temperature control can be quickly performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a temperature control device according to an embodiment of the present invention.

[Figure 2] Waveform diagram showing lighting ratio

[Figure 3] Diagram showing the relationship between the reference voltage applied to the - terminal of the comparator and time

[Figure 4] Temperature characteristics diagram of heater

[Explanation of symbols]

1 Heater 2 Power supply 3 Lighting ratio control circuit 4 Pulse generator 5 Decoder 6 Comparators 9a to 9f Flip-flops 10, 11, 12, 13a, 13b Counter 18
Differentiation circuit 19, 20, 21 Memory 22, 23, 24 Judgment circuit

Claims (1)

[Claims] 1. Temperature setting means for setting a target temperature to be maintained in the vicinity of the heating element; temperature detection means for detecting the temperature in the vicinity of the heating element; and at least two reference temperatures including the target temperature. a reference temperature generating means for time-divisionally generating voltage levels; a comparison means for comparing the reference temperature with a detected temperature near the heating element; and a storage means for storing data for controlling power supply to the heating element. and a control means for selecting data stored in the storage means based on the output from the comparison means and controlling supply power.