JPS63198839A - Temperature detector - Google Patents

Abstract

PURPOSE:To approximate the characteristic line of a reference value signal to the characteristic curve of a thermistor and to make detection accurate by adjusting a voltage applied to a ladder resistance part which generates a staircase reference value signal and the earth potential according to the detection output of the thermistor. CONSTITUTION:Switches b0-b6 (not shown in figure) in a buffer 8 are switched according to the on-off states of the output ports F0-F3 and D0-D2 of a microcomputer 5 and a reference signal which is obtained by dividing the potential difference between the earth potential (b) of the ladder resistance part 7 and the voltage VCC applied to a buffer part 8 stepwise is generated at an output terminal (a). A comparator 6 compares the reference signal with the detection signal of the thermistor 9. The microcomputer 5 detects the temperature according to the result. A 1st adjusting circuit 11 and a 2nd adjusting circuit 13 vary the earth potential (b) of the ladder resistance part 7 and the voltage VCC applied to the buffer part 8 according to which of ranges below VL, between VL and VH, and above VH the detection signal of the thermistor 9 is in. Then the reference signal characteristics approximate to the characteristics of the thermistor and accurate temperature detection is performed.

Description

Detailed Description of the Invention (() Industrial Application Field The present invention sequentially outputs temperature data signals from a microcomputer to generate a step-like reference value signal through a buffer section and a ladder resistor section. The present invention relates to a temperature detection device in which a comparator compares a signal and a detection signal of a thermistor of an object to be measured, and the microcomputer detects the temperature of the object based on the comparison result of the comparator.

Conventional technology In the conventional technology filed by the present applicant in Japanese Patent Application No. 61-67464, a temperature data signal is sequentially output from a microcomputer and a stepped reference value signal is generated through a buffer section and a ladder resistor section. The stepped reference value signal and the detection signal of the thermistor of the object to be measured are compared by a comparator, and the temperature of the object to be measured is detected by the microcomputer based on the comparison result of the comparator. Since the detection signal has a so-called non-linear characteristic that cannot change proportionally to temperature changes, a potential difference occurs between it and the step-like reference value signal with a linear characteristic, and the microcomputer reads the detected temperature by that potential difference. There is a drawback that an error occurs between the temperature and the actual temperature of the object to be measured.

(c) Problems to be Solved by the Invention The present invention attempts to solve the above-mentioned drawbacks and to make the temperature read by the microcomputer approximately correspond to the actual temperature of the object to be measured.

B) Means for Solving the Problems The present invention sequentially outputs temperature data signals from a microcomputer to generate a stepped reference value signal through a buffer section and a ladder resistor section, and combines the stepped reference value signal with the object to be measured. A comparator compares the detection signal of the thermistor, and the microcomputer detects the temperature of the object based on the comparison result of the comparator.

Based on the detection signal of the thermistor, the comparison temperature range of the stepped reference value signal and the detection signal is divided into a plurality of temperature ranges, and the voltage applied to the buffer section is adjusted in accordance with each comparison temperature range, and the ladder resistance section is adjusted. In order to adjust the potential of the ground portion of the step-like reference value signal, the characteristic line of the stepped reference value signal is approximated to the characteristic curve of the thermistor.

N) Function According to the present invention, even if the detection signal of the thermistor changes non-linearly with respect to temperature changes, the step-like reference value signal as a comparison signal also changes its characteristic straight line in accordance with each comparison temperature range. The tilt angle is adjusted so that the temperature read by the microcomputer is approximately equal to the actual temperature of the object to be measured.

(f) Example Next, one embodiment of the present invention will be described.

In Figure 1, (1) is the DC power supply circuit section, and the father current power supply (
A step-down transformer (2) connected to a converter (not shown).

It has a commutator (3) and an RO smoothing circuit (4), and supplies voltages of 5 volts and 7 volts to various parts. (5) is the microcontroller output port (FO) ~ (F5) (Do) ~ (D2)
It sequentially outputs a temperature data signal (g) (to be described later), and has an input capo (AI). The input capo (A1) is for inputting the output signal of the first comparator (6) to determine the temperature of the object to be measured. (
7) is a ladder resistance section which is connected to the output capacitors (FO) to (F5) (DO) to (D2) via the buffer section (8), and outputs a step-like reference value from the output terminal (IL) to be described later. Output a signal. (9) is a thermistor that is installed on an object to be measured, such as a pump body, to ensure good heat transfer, and its resistance value has a so-called non-linear characteristic that cannot change proportionally to temperature changes. In the first comparator (6), a detection signal is input to the negative side from between the thermistor (9) and the dividing resistor (IG), and before this detection signal is input to the positive side, the first comparator (6) outputs a stepped base value signal. When the potential of the stepped reference value signal becomes high, a high level signal is outputted and inputted to the input capo (A1). In the microcomputer (5), when the potential of the input capo (At) is reversed to a high level,
The temperature data signal of the microcomputer (5) at that time is checked, and the temperature of the object to be measured is determined based on the temperature data signal (δ) value at that time.

aυ is a first adjustment circuit section of the characteristic line (121 (described later)) of the stepped reference value signal, and a second
As shown in the figure, the ladder resistor section (7
) is adjusted in accordance with each comparative temperature range.

αJ is the characteristic line (121) of the stepwise reference value signal, and a second adjustment circuit unit adjusts the slope angle of the characteristic line α in accordance with each comparison temperature range.

The buffer section (8), as shown in FIG.
Each output of the microcomputer (5) (FO) to (Fs
) (vo) to (D2), the switch (bO
) to (b6), and these switches sequentially output temperature data signals (0) to (δ) to (127 ) by sequentially turning on and off as shown in FIG. 4 in response to each output step.

The output terminal of the ladder resistor (7) (the potential of the cap is 0 to 2 (X+
R)・-122・vQO(yaa) is configured to generate the above-mentioned step-like reference value signal by changing up to the voltage applied to the buffer section.Here, the ladder resistor section (7
) is proportional to the applied voltage (VCC) of the buffer section (8), and therefore, the slope angle of the characteristic straight line of the stepped reference value signal is also adjusted in accordance with the applied voltage (Vca) of the buffer section (8). can.

In the 5g2 adjustment circuit unit 0, a second comparator G41 receives the vL level signal and the VH level signal, respectively.
1'F3 comparator α9 and 1 comparator n4
By inputting the detection signal of the thermistor (9) to each of +ts, if the potential of this detection signal is in the range of 0 to VL volts, the output terminals of both converters Iα9 will be at a low level, and the transistor (Ql) will be turned off. , the transistor (Q2) is turned on, the transistor (Q5) is turned on, and a voltage of 5 volts is applied to the buffer section (8) via the transistor (Q5). Further, when the potential of the detection signal is in the range of VL-'/1 (volts), the output terminals of both comparators 0409 are at a high level, and the transistor (Ql) is turned on and the transistor (Q4) is turned on.

A voltage of 7 volts is applied to the buffer section (8) via the transistor (q4).Also, when the potential of the detection signal becomes greater than VH volts, both comparators (1
41 (l), the force end returns to the low level, and therefore a voltage of 5 volts is applied to the buffer section (8) via the transistor (Q3). In short, the second adjustment circuit section a3
Now, in the comparison temperature range of 0 to VL volts and the comparison temperature range of VH volts or more shown in FIG. 2, the step-like reference value signal is The characteristic line (121L) (12(
The characteristic straight line (121) of the stepped reference value signal is adjusted by adjusting the inclination angle of 1) to a small value, and by switching the applied voltage of the buffer section (8) to 7 volts in the comparison temperature range of VL-VH volts. functions to greatly adjust the angle of inclination of the The reason why the slope angles of the characteristic lines (12L) and (120) are slightly different is that they are influenced by the change in the potential of the ground section ('b) of the buffer section (8) caused by the first adjustment circuit section 1131.

The first adjustment circuit section 1lII includes a fourth comparator (which receives the YL level signal and VH level signal, respectively).
By inputting the detection signal of the thermistor (9) to each of the first and second comparators 1F3αη), the potential of this detection signal becomes Q~
The outputs of both comparators (161σD) are high level and low level, respectively, corresponding to the ranges of ML volts, VL-VH volts, and VH volts.

Transistors (Q5) (Q4) for high level high level, low level high level signal, and these high and low level signals
The relay α arc 9 is turned on and off, fon on, and
It turns off and on. Furthermore, in the first adjustment circuit section a1J,
The relay α8 (13 normally closed contacts (18NO)
) (19NO) and normally open contact (18NO) (19NO)
According to the operation of the detection signal, a normally open contact (18NO
) turns on, and the voltage drop (Vl a
), the potential of the ground portion tl)l of the ladder resistor portion (7) is raised by the amount. Further, the potential of the detection signal is VL-
In the range of VH volts, the normally closed contact (18NO) and normally closed contact (19NO) are turned on, and the single contact (18NO) is turned on.
) (19NO), the ground portion (1)) of the ladder resistor portion (7) is directly grounded and maintained at the ground level. In addition, the normally open contact (15'NO) is turned on in the range where the potential of the front edge detection signal is equal to or higher than VH. The potential of the grounding part (1)l of the ladder resistance part (7) is raised by the voltage drop (Vzb) of the Zener diode (211) connected to this normally open contact (19NO). By adjusting the potential of the earth part 0 in (7), υ.

As shown in FIG. 2, the characteristic line α2 of the step-like reference value signal of the output terminal (al) of the ladder resistance section (7) is the slope characteristic line (at 5 volts) described above in the range of 0 to VL volts ( 12&) is the voltage drop CVi of Zener diode ■
&), and in the range of VL to VH volts, the above-mentioned slope characteristic line (121) at 7 volts
is maintained on the extension line of the ground level, and in the range above tVH volts, the slope characteristic line (12C) at 5 volts mentioned above is the Zener diode C! Voltage drop of υ (
Therefore, the slope characteristic lines (12a), (12b), and (12o) match at the vL level and the VH level, forming a continuous step-like characteristic line 0 of the reference value signal.

In the Maemi temperature checking device, when the detection signal of the thermistor (9) is in the range of 0 to VL volts, the voltage applied to the buffer section (8) is adjusted to 5 volts, and the ladder resistance section (
7) Earth part (1>1 potential is Zener diode ■
Therefore, the characteristic line (12&) of the stepped reference value signal is approximated to the characteristic curve of the thermistor (9).

Therefore, the accurate temperature of the object to be measured can be detected based on the characteristic line (121L).

Further, when the detection signal of the thermistor (9) is in the range of VL-VH volts, the applied voltage of the buffer section (8) is adjusted to 7 volts, and the ladder resistor section (force ground section 0
) is maintained at 0 level, so that the characteristic line (12
C) is approximated to the characteristic curve of the thermistor (9), and therefore the accurate temperature of the object to be measured is detected based on the characteristic line (121)).

Further, when the detection signal of the thermistor (9) is in the range of VH volts or more, the applied voltage of the buffer section (8) is adjusted to 5 volts, and the earth section t of the ladder resistor section (7) is adjusted to 5 volts.
l) The potential of I is raised by the voltage drop (vzb) of the Zener diode c211, so that the characteristic line (12
0) is approximated to the characteristic curve, and therefore the characteristic line (12(
+), the accurate temperature of the object to be measured is detected.

(g) Effects of the Invention Since the present invention is configured as described above, even if the characteristic line of the thermistor detection signal changes in a curved manner in response to temperature changes, the stepped reference value signal is compared with the characteristic line. The inclination angle of the characteristic line is also adjusted to approximate the characteristic curve of the thermistor in each comparative temperature range, so that the detected temperature read by the microcomputer can be approximated to the actual temperature of the object to be measured. Furthermore, the process of approximating the characteristic line of the stepped reference value signal to the characteristic curve of the thermistor can be easily performed by a microcomputer by simply adjusting the applied voltage of the buffer section of the ladder resistor section and the potential of the ground section corresponding to each comparison temperature range. It can be easily performed without the need for complex internal processing.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention. Fig. 1 is an electric circuit diagram, Fig. 2 is a comparative explanation of the characteristic curve of the stepped reference value signal with respect to the thermistor characteristic curve, Fig. 6 is an explanatory diagram of the ladder resistance section and buffer section in Fig. 1, and Fig. 4 is an illustration of the ladder resistance section and buffer section in Fig. 1. The figure is an explanatory diagram of the operation of the ladder resistance section and the buffer section. (5)...Microcomputer, fi+...Comparator (
(first comparator), (71... ladder resistance section,
(8) Buffer section. (9)...Thermistor, σ2...Characteristic line, c? Z
... Characteristic curve, (δ) ... Temperature data signal, (b)
...Earth Department.

Claims (1)

[Claims] 1) A step-like reference value signal is generated by sequentially outputting a temperature data signal from a microcomputer through a buffer section and a ladder resistor section, and the step-like reference value signal and a detection signal of a nermistor of the object to be measured are combined. is compared by a comparator, and the temperature of the object to be measured is detected by the microcomputer based on the comparison result of the comparator, wherein the stepped reference value signal and the detection signal are determined based on the detection signal of the thermistor. By dividing the comparison temperature range into a plurality of parts and adjusting the voltage applied to the buffer part and the potential of the ground part of the ladder resistance part corresponding to each comparison temperature range, the stepped reference value signal can be adjusted. A temperature detection device characterized in that a characteristic line is approximated to a characteristic curve of the thermistor.