JPH10197360A - Temperature-measuring circuit and temperature-measuring resistance body input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To duplicate a temperature-measuring circuit using a temperature- measuring resistance body(RTD) and a temperature-measuring resistance body input device. SOLUTION: Constant current circuits 1, 8 having bypass diodes 7, 13 are connected in series, thereby supplying a current to an RTD 4, 100% reference resistors 5, 11 and 0% reference resistors 6, 12. Voltages of the RTD 4 and both end parts of each reference resistor are switched by signal switches 3, 10. A measured temperature is operated by an operating part via amplifying parts 2, 9 and sent outside. Even when the constant current circuit 1 fails, the constant current source 8 supplies the current via the bypass diode 7 to continue the temperature measurement. Moreover, even if a temperature-measuring resistance body input device 101 fails, the temperature measurement is continued at the side of a temperature-measuring resistance body input device 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring circuit for measuring a temperature by using a resistance temperature detector as a detector, and to a resistance temperature detector input device for processing an input from the resistance temperature detector, and more particularly to a duplexer. Things.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a block diagram illustrating a conventional control device disclosed in Japanese Patent Laid-Open Publication No. H10-26095. In the figure, 22 is a main adjustment unit, 23 is a sub adjustment unit, 24 is an internal communication line, 25 is a switching unit,
26 is a relay unit.

Next, the operation will be described. Signals such as a thermocouple, a resistance temperature detector, a DC voltage, and a DC current which are taken in as inputs are input to the main control unit 22 and the sub-control unit 23 in parallel, and control calculations such as PID are performed based on the setting data. Switching unit 25 using the result as a control output
Output via.

Normally, the control output from the main control unit 22 is output via the switching unit 25. However, when the auxiliary control unit 23 detects an abnormal signal from the main control unit 22 via the internal communication line 24, By switching the relay section 26, the control output from the sub-adjustment unit 23 is transmitted.
In this way, the adjustment unit is duplicated to improve reliability.

[0005]

Since the conventional control device is configured as described above, a voltage input can be easily performed in the case of duplexing, but the RTD (Resistance Temperature)
RTD that processes input from Detector (RTD)
(RTD) There is a problem that a signal of a type in which a predetermined current is applied and a voltage across both ends is input, as in an input device, cannot be easily applied.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an RTD input device which can easily be duplexed without adjustment even when an RTD signal is input;
It is an object of the present invention to obtain a temperature measurement circuit that uses TD and supports duplication.

[0007]

[Means for Solving the Problems]

(1) A temperature measuring circuit according to the present invention is a current source in which a first constant current source having a bypass diode connected in parallel and a second constant current source having another bypass diode connected in parallel are serially connected in the forward direction. A series resistor connected in series with a temperature detecting resistor for temperature detection, a first reference resistor, and a second reference resistor, and supplied with current from the current source; the temperature measuring resistor and the first reference; A first calculating section for calculating a measured temperature based on a potential difference between both ends of the resistor, and a second calculating section for calculating a measured temperature based on a potential difference between both ends of the temperature measuring resistor and the second reference resistor. An arithmetic unit is provided, and the constant current source, the reference resistance, and the arithmetic unit are duplicated.

(2) In the temperature measuring circuit according to (1), the current source has switching means connected in series to each of the first constant current source and the second constant current source. A bypass diode is connected, and the first and second constant current sources can be turned on / off by the two opening / closing means.

(3) The temperature measuring resistor input device according to the present invention is a temperature measuring circuit according to (1) or (2), wherein a first constant current source having a bypass diode connected in parallel, a first reference. The resistance and the first calculation unit constitute a first resistance thermometer input device, and the second constant current source, the second reference resistance, and the second calculation unit having the bypass diode connected in parallel form the second calculation unit. This constitutes a resistance temperature detector input device.

(4) The temperature measuring circuit according to the present invention is configured such that a first constant current source having a bypass diode connected in parallel and a second constant current source having another bypass diode connected in parallel are serially connected in the forward direction. A current source, a temperature measuring resistor for temperature detection and a reference resistor connected in series and a current is supplied from the current source, a series resistor, and a potential difference between both ends of the temperature measuring resistor and the reference resistor. A constant current source and an arithmetic unit are provided in duplicate.

(5) In the temperature measuring circuit according to the above (4), the current source has switching means connected in series to each of the first constant current source and the second constant current source. A bypass diode is connected, and the first and second constant current sources can be turned on / off by the two opening / closing means.

(6) A temperature measuring resistor input device according to the present invention is the first of the temperature measuring circuits of (4) or (5).
Constitutes a first resistance thermometer input device with the constant current source and the first calculation unit, and forms a second resistance temperature sensor input device with the second constant current source and the second calculation unit. It is composed.

(7) In the temperature measuring circuit according to the present invention, a first constant voltage source having a diode connected in series in the forward direction and a second constant voltage source having another diode connected in series in the forward direction are the same. A voltage source connected in parallel with polarity, a temperature measuring resistor for temperature detection and a reference resistor connected in series, and a current is supplied by applying a voltage from the voltage source, the temperature measuring resistor and the reference resistor A first and a second calculating unit for calculating a measured temperature based on a potential difference between both ends of the constant voltage source;
The operation unit is duplicated.

(8) In the temperature measuring circuit of (7), switching means connected in series to each of the first constant voltage source and the second constant voltage source are provided, and the first constant voltage source and the second constant voltage source are provided by the first and second switching means. And the second constant voltage source can be turned on and off freely.

(9) The temperature-measuring-resistance-element input device according to the present invention includes the first constant-voltage source having a diode connected in series in the forward direction and the first constant-voltage source in the temperature measuring circuit according to (7) or (8). And a second constant voltage source in which diodes are connected in series in a forward direction and a second arithmetic unit, and a second resistance thermometer input device. It is what constituted.

(10) The temperature measuring circuit according to the present invention comprises:
A first constant voltage source in which diodes are connected in series in a forward direction;
A voltage source in which another diode is serially connected in the forward direction and a second constant voltage source in parallel with the same polarity, a temperature measuring resistor for temperature detection, and a first reference resistor and a second reference resistor in series; A first calculating unit for calculating a measured temperature based on a potential difference between both ends of the series resistor to which a current is supplied by applying a voltage from the voltage source and the temperature measuring resistor and the first reference resistor; A second calculating section for calculating a measured temperature based on a potential difference between both ends of the temperature measuring resistor and the second reference resistor, wherein a constant voltage source, a reference resistor, and a calculating section are duplicated. .

(11) In the temperature measuring circuit of (10), switching means connected in series to each of the first constant voltage source and the second constant voltage source are provided, and the first constant voltage source and the second constant voltage source are provided by the first and second switching means. And the second constant voltage source can be turned on and off freely.

(12) The temperature-measuring-resistance-element input device according to the present invention is the temperature-measuring circuit of (10) or (11), wherein the first constant-voltage source having a diode connected in series in the forward direction and the first constant-voltage source. A first resistance thermometer input device, a second constant voltage source in which diodes are connected in series in a forward direction, a second reference resistance, and a second operation. And the second part constitute a second resistance bulb input device.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a temperature measuring circuit including a resistance temperature detector input device, and FIG. 2 is a block diagram of a portion of the circuit of FIG. FIG. 3 is a circuit diagram for explaining the operation in which the circuit diagram of FIG. 1 is easily understood. Although the connection between the RTD and the reference resistor is slightly different from that of FIG. 1, the operation principle is written for easy understanding. This is the same for the circuit diagrams for explaining the operation after the second embodiment (FIG. 5 and others).

In FIGS. 1 and 3, reference numerals 1 and 8 denote constant current circuits, reference numerals 2 and 9 denote amplification circuits, reference numerals 3 and 10 denote signal switches, and switches S1, S2 and S3 are sequentially turned on by software (others are turned on). OFF), and switches S4, S5 and S6 are sequentially turned on. Reference numeral 4 denotes an RTD (resistance temperature detector) for detecting the temperature of the temperature measurement target;
The 0% side reference resistance determines the upper limit value of the measurement temperature range, that is, the full scale value. Reference numerals 6 and 12 denote 0% -side reference resistances, which determine the lower limit of the temperature measurement range.

Reference numerals 7 and 13 denote diodes that bypass the constant current circuits 1 and 8, respectively. 101 is a first resistance temperature detector input device, and 102 is a second resistance temperature detector input device.

In FIG. 2, reference numerals 31 and 41 denote A / D converters, and reference numerals 32 and 42 denote arithmetic units for calculating the measured temperature from the detected resistance value of the RTD. Reference numerals 33 and 43 denote watchdog timers used for detecting failures of computers and the like.
If the clock signal from the built-in CPU is not input within a predetermined time, the arithmetic units 32 and 42 send out a signal as a failure. Note that the inside of the first resistance thermometer input device 101 represents the entire first calculation unit, and the inside of the second resistance temperature sensor input device 102 represents the entire second calculation unit. Process with software.

Next, the operation will be described. The specified current flowing through the RTD 4 is supplied from the constant current circuits 1 and 8. When the RTD input devices 101 and 102 are duplicated, the constant current circuit 1
8 in series. The output current of the constant current circuit 1 is shown in FIG.
RTD4 → reference resistance 11 → reference resistance 12 → constant current circuit 8
→ Reference resistance 5 → Reference resistance 6

On the other hand, the output current of the constant current circuit 8 flows through the path of the reference resistance 5 → reference resistance 6 → constant current circuit 1 → RTD4 → reference resistance 11 → reference resistance 12.

The RTD 4, the reference resistor 5, the reference resistor 6, the reference resistor 11, and the reference resistor 12 have the larger one of the output currents of the constant current circuit 1 and the constant current circuit 8, and the diode 7 or the diode 13 has the larger output current. The difference between the output currents of the constant current circuits shunts. Since the currents flowing through the RTD 4 and the four reference resistors 5, 6, 11, and 12 are equal, the output currents of the constant current circuits 1 and 8 of the duplicated RTD input devices 101 and 102 are adjusted to be equal. Even without doing so, the resistance value of the RTD can be obtained from the voltages at both ends of the RTD 4, the reference resistors 5, 11 and the reference resistors 6, 12.

The detected voltages at both ends of the RTD 4, the reference resistances 5, 11, and the reference resistances 6, 12 are sequentially switched by switches S1, S2, S3 and S4, S5, S6 in the signal switches 3, 10, and are then amplified. After amplification in 2,9, A /
The temperature of the object to be measured detected by the RTD 4 is calculated and output by the calculation units 32 and 42 which are digitally converted by the D converters 31 and 41 and have a built-in CPU.

If the constant current circuit 1 breaks down and there is no current output, the current of the constant current circuit 8 bypasses the diode 1 to flow a constant current, so that the measurement can be continued. In this case, the RTD 4 and the reference resistors 5, 6, 11, and 12
Although the absolute values of the currents flowing through the RTDs vary, they are all relatively equal, so that the resistance value of the RTD can be obtained from the voltages across the reference resistors 11, 12 and the RTD4.

As described above, in this embodiment, the arithmetic processing part (the first part) after the constant current circuit, the reference resistance, and the signal switch is performed.
And the second arithmetic unit), and the difference between the output currents of the two constant current circuits does not cause an error even if the output is duplicated. Further, even if one of the constant current circuits fails, the temperature measurement can be continued by the other constant current circuit, and the reliability can be improved.

Embodiment 2 FIG. 4 shows a circuit diagram of this embodiment, and FIG. 5 shows a circuit diagram for explaining the operation. Note that the operation processing part shown in FIG. 2 is the same as that of the first embodiment, and thus the description thereof will be omitted in the following embodiments.

In the first embodiment, the case where the constant current circuits are connected in series has been described.
Switches 14 and 15 are provided as shown in FIGS. 4 and 5 to switch between the constant current circuits 1 and 8.

In this case, although the absolute values of the currents flowing through the RTD 4 and the reference resistors 5, 6, 11, and 12 are changed by the switching, they are all relatively equal. The temperature can be measured by calculating the resistance value of the RTD.

For switching, for example, the switch 14 is set to O
N, when the switch 15 is turned off and the RTD input device 101 side is used, when the watchdog timer 33 detects a failure of the arithmetic unit 32, the switch 14 is turned off, the switch 15 is turned on and the RTD input device 102 side is turned on. Switch. When a failure occurs, the switch may be switched artificially.

As described above, in this embodiment, if a failure occurs in one of the duplicated RTD input devices, the other RTD input device will fail.
Since switching to the D input device is performed, reliability can be improved.

Embodiment 3 FIG. 6 is a circuit diagram of this embodiment, and FIG. 7 is a circuit diagram for explaining the operation. In the first embodiment, the reference resistors 5, 6, 15, and 16 are
Although the case where it is incorporated in the input devices 101 and 102 has been described, in this embodiment, as shown in FIG.
6, 17 and bypass diodes 7, 13 are provided.

In this way, for example, when the RTD input device 101 is replaced, even if the RTD input device 101 is disconnected from the circuit at the terminal portion thereof, the RTD input device 102 is not affected, so that the RTD input device 102 is easily replaced. can do. The operation is the same as that of the first embodiment except that the potential difference between both ends of the reference resistors 16 and 17 is input to the signal switches 3 and 10, respectively.

As described above, in this embodiment, the constant current circuit and the arithmetic processing part (first and second arithmetic parts) after the signal switch are duplicated, and a problem occurs in one of the RTD input devices. Also, disconnection or replacement from the circuit is the other RTD
Since the operation can be performed without affecting the input device, the efficiency of maintenance and inspection work can be improved.

Embodiment 4 FIG. FIG. 8 shows a circuit diagram of this embodiment, and FIG. 9 shows a circuit diagram for explaining the operation. As shown in FIGS. 8 and 9, the constant current circuits 1 and
8 are provided with switches 14 and 15 respectively. The operations of the switches 14 and 15 are the same as in the second embodiment, and a description thereof will be omitted.

As described above, in this embodiment, even if a failure occurs in one of the duplicated RTD input devices as in the second embodiment, switching to the other RTD input device is performed, thereby improving reliability. be able to. Further, as in the third embodiment, even if a failure occurs in one of the RTD input devices, disconnection from the circuit, replacement, and the like can be performed without affecting the other RTD input device. Can be achieved.

Embodiment 5 FIG. 10 shows a circuit diagram of this embodiment, and FIG. 11 shows a circuit diagram for explaining the operation. As shown in the figure, the constant voltage circuits 18 and 19 in which diodes 20 and 21 are connected in series are duplicated by connecting them in parallel, and even if there is a difference between the output voltages of the constant voltage circuits 18 and 19, the larger one is used. An output voltage is output, and a current flows through the RTD 4 and the reference resistors 16 and 17.

Even if one of the constant voltage circuits has a defect, the constant voltage circuit is isolated by the diode 20 or 21, so that the measurement operation can be continued with the other constant voltage circuit. In this case, even if the output voltage value slightly fluctuates, the absolute values of the currents flowing through the RTD 4 and the reference resistances 16 and 17 change, but all become relatively equal. , The resistance value of the RTD can be determined from the voltage, and the temperature can be measured.

When one RTD input device is replaced or repaired, disconnection from the circuit can be performed without affecting the other RTD input device.

As described above, in this embodiment, the constant voltage circuit and the operation processing portion (first and second operation portions) after the signal switch are duplicated, and one of the constant voltage circuits has a problem. Also, the measurement operation can be continued by the other constant voltage circuit. Further, even if a failure occurs in one of the RTD input devices, disconnection or replacement from the circuit can be performed without affecting the other RTD input device, so that the efficiency of maintenance and inspection work can be improved.

Embodiment 6 FIG. FIG. 12 is a circuit diagram of this embodiment, and FIG. 13 is a circuit diagram for explaining the operation. As shown in FIGS. 12 and 13, switches 14 and 15 are provided in each of the constant voltage circuits 18 and 19 of the fifth embodiment. The switches 14 and 15 switch the constant voltage circuits 18 and 19, respectively.

In this case, as in the fifth embodiment, the absolute value of the current flowing through the RTD 4 and the current flowing through the reference resistors 16 and 17 are changed by the switching. From the voltage at both ends, R
The temperature can be measured by determining the resistance value of TD.

Switching is performed, for example, by turning on the switch 14 and turning off the switch 15 in the same manner as in the second embodiment.
When the watchdog timer 33 detects a failure of the arithmetic unit 32 shown in FIG. 2 while using the TD input device 101, the switch 14 is turned off and the switch 15 is turned on to switch to the RTD input device 102 side. When a failure occurs, the switches may be switched artificially.

As described above, in this embodiment, if a failure occurs in one of the duplicated RTD input devices, the other RTD input device will fail.
Since switching to the D input device is performed, reliability can be improved. Further, as in the fifth embodiment, even if a failure occurs in one of the RTD input devices, disconnection or replacement of the RTD input device can be performed without affecting the other RTD input device. Can be achieved.

Embodiment 7 FIG. FIG. 14 is a circuit diagram of this embodiment, and FIG. 15 is a circuit diagram for explaining the operation. Diode 2 connected in series with constant voltage circuits 18 and 19
The configurations of 0 and 21 are the same as those of the fifth embodiment, but the reference resistors are provided in the first and second RTD input devices 101 and 102, respectively.

The constant voltage circuits 18 and 19 are duplicated by being connected in parallel, so that even if there is a difference between the output voltages of the constant voltage circuits 18 and 19, the larger output voltage is output, and the RTD 4 and the reference resistors 5, 6 Current flows through 11 and 12.

Then, even if one of the constant voltage circuits is defective, the other constant voltage circuit can continue the measurement operation. In this case, even if the output voltage value slightly changes, R
Although the absolute values of the current flowing through TD4 and the reference resistors 5, 6, 11, and 12 change, they are all relatively equal.
The resistance value of the RTD can be determined from the voltage between both ends of the RTD 4 and the reference resistors 5, 6, 11, and 12, and the temperature can be measured.

Further, even if a failure occurs in the operation unit or the like of one RTD input device, the measurement operation can be continued with the other RTD input device. However, when one RTD input device is disconnected from the circuit when the RTD input device is replaced or repaired, it cannot be disconnected without affecting the other RTD input device as in the fifth embodiment. When disconnecting,
Requires a connection change.

As described above, in this embodiment, the arithmetic processing portion (the first portion) after the constant voltage circuit, the reference resistor, and the signal switch is performed.
And the second arithmetic unit), so that even if a malfunction occurs in one of the constant voltage circuits, the measurement operation can be continued in the other constant voltage circuit. Also, if one RTD input device fails,
The measurement operation can be performed using the other RTD input device.

Embodiment 8 FIG. FIG. 16 shows a circuit diagram of this embodiment. FIG. 16 is obtained by providing switches 14 and 15 in FIG. 14 of the seventh embodiment. This switch 14,
Reference numeral 15 switches the constant voltage circuits 18 and 19, respectively.

In this case as well, the absolute value of the current flowing in the RTD 4 and the reference current flowing through the reference resistors 5, 6, 11, and 12 change as in the fifth embodiment. The temperature can be measured by determining the resistance value of the RTD from the voltage across the terminals 5, 6, 11, and 12.

The switch is switched automatically upon detection of a failure, but may be switched manually.

As described above, in this embodiment, if a failure occurs in one of the duplicated RTD input devices, the other RTD input device will fail.
Since switching to the D input device is performed, reliability can be improved.

Embodiment 9 FIG. In the first embodiment, as shown in FIG. 1, switches S1, S2, S3 and S4, S3
5 and S6 are sequentially switched, and when S1 is 0N, RTD
4. Measure the temperature of the measurement target with 4, and turn on S5 and S6
In the case of, the gain / offset calibration of the amplifier circuits 2 and 9 and the A / D converters 31 and 41 by the reference resistance is performed.
The switches S1 and S4 may be normally turned on to measure the temperature, and the switches S2, S3 and S5 and S6 may be sequentially turned on at predetermined time intervals to perform calibration.

Although the calculation unit in FIG. 2 according to the first embodiment calculates the measured temperature by software processing using a CPU, the circuit is configured by hardware, which is a conventional measuring means, and the measured temperature is calculated. May be measured. Also, the diodes 7, 13 in FIG. 1 and the diode 2 in FIG.
A rectifying element having a rectifying action other than a diode may be used for 0, 21 and the like. In the present invention, the rectifying element is also included in the category of the diode.

[0058]

As described above, according to the present invention, in order to realize a dual temperature measuring circuit using a resistance temperature detector and a dual resistance temperature detector input device used in this circuit,
A constant current or constant voltage power supply, a calculation unit for calculating the measurement temperature, and the like are duplicated so that temperature measurement can be continued even if a failure occurs in the power supply or the calculation unit, so that reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a temperature measuring circuit according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a calculation unit of the resistance bulb input device according to Embodiment 1 of the present invention;

FIG. 3 is a circuit diagram for describing an operation of the temperature measurement circuit according to the first embodiment of the present invention.

FIG. 4 is a circuit diagram of a temperature measuring circuit according to a second embodiment of the present invention.

FIG. 5 is a circuit diagram for explaining an operation of the temperature measuring circuit according to the second embodiment of the present invention.

FIG. 6 is a circuit diagram of a temperature measuring circuit according to a third embodiment of the present invention.

FIG. 7 is a circuit diagram for describing an operation of a temperature measurement circuit according to Embodiment 3 of the present invention.

FIG. 8 is a circuit diagram of a temperature measuring circuit according to a fourth embodiment of the present invention.

FIG. 9 is a circuit diagram for describing an operation of a temperature measurement circuit according to a fourth embodiment of the present invention.

FIG. 10 is a circuit diagram of a temperature measuring circuit according to a fifth embodiment of the present invention.

FIG. 11 is a circuit diagram for describing an operation of a temperature measurement circuit according to a fifth embodiment of the present invention.

FIG. 12 is a circuit diagram of a temperature measuring circuit according to a sixth embodiment of the present invention.

FIG. 13 is a circuit diagram for describing an operation of a temperature measuring circuit according to a sixth embodiment of the present invention.

FIG. 14 is a circuit diagram of a temperature measuring circuit according to a seventh embodiment of the present invention.

FIG. 15 is a circuit diagram for describing an operation of a temperature measurement circuit according to a seventh embodiment of the present invention.

FIG. 16 is a circuit diagram of a temperature measurement circuit according to an eighth embodiment of the present invention.

FIG. 17 is a block diagram of a conventional control device.

[Explanation of symbols]

1,8 constant current circuit, 2,9 amplifier circuit,
3,10 signal switch, 4 RTD (resistance temperature detector) 5,11 100% side reference resistance, 6,120% side reference resistance, 7,13 diode, 14,15
Switch (opening / closing means), 16 external 100% side reference resistance, 17 external 0% side reference resistance, 18, 19 constant voltage circuit, 20, 21 diode, 31, 41
A / D converter, 32, 42 arithmetic unit, 33, 43
Watchdog timer.

Claims (12)

[Claims] A first diode having a bypass diode connected in parallel;
Current source in which a constant current source having a constant current source and a second constant current source having another bypass diode connected in parallel are connected in series in the forward direction, a temperature measuring resistor for temperature detection, a first reference resistor, and a second reference A first resistor connected in series to supply a current from the current source; a first calculator for calculating a measured temperature based on a potential difference between both ends of the temperature measuring resistor and the first reference resistor; ,
A second calculating unit that calculates a measured temperature based on a potential difference between both ends of the temperature measuring resistor and the second reference resistor,
A temperature measurement circuit characterized in that a constant current source, a reference resistor, and a calculation unit are duplicated. 2. The temperature measuring circuit according to claim 1, wherein the current source has switching means connected in series to each of the first constant current source and the second constant current source, and has a bypass diode connected to both ends thereof. A temperature measuring circuit characterized in that the first and second constant current sources can be freely turned on and off by the opening and closing means. 3. The temperature measuring circuit according to claim 1 or 2, wherein a first constant current source having a bypass diode connected in parallel, a first reference resistor, and a first temperature measuring resistor in a first calculating section. A second constant current source, a second reference resistance, and a second arithmetic unit, which constitute a body input device and a bypass diode connected in parallel, constitute a second resistance bulb input device. Resistance thermometer input device. 4. A first circuit in which bypass diodes are connected in parallel.
A current source in which a constant current source having a constant current source and a second constant current source having another bypass diode connected in parallel are connected in series in a forward direction; A first resistor and a second calculator for calculating a measured temperature based on a potential difference between both ends of the temperature measuring resistor and the reference resistor, and a constant current source;
A temperature measurement circuit characterized in that the operation unit is duplicated. 5. The temperature measuring circuit according to claim 4, wherein the current source has switching means connected in series to each of the first constant current source and the second constant current source, and has a bypass diode connected to both ends thereof. A temperature measuring circuit characterized in that the first and second constant current sources can be freely turned on and off by the opening and closing means. 6. The temperature measuring circuit according to claim 4 or 5, wherein the first constant current source and the first arithmetic unit constitute a first resistance temperature detector input device, and the second constant current source and the first arithmetic unit. Constant current source and second
A second resistance thermometer input device comprising: a second resistance thermometer input device; 7. A first device in which diodes are connected in series in a forward direction.
A constant voltage source, a second constant voltage source in which another diode is connected in series in the forward direction, a voltage source in which the same polarity is connected in parallel, a temperature measuring resistor for temperature detection, and a reference resistor connected in series. A series resistor to which a current is supplied by applying a voltage from a voltage source,
It is provided with first and second two calculation units for calculating a measured temperature based on a potential difference between both ends of the resistance temperature detector and the reference resistance, and a constant voltage source and a calculation unit are duplicated. Temperature measurement circuit. 8. The temperature measuring circuit according to claim 7, wherein:
A switching means connected in series to each of the constant voltage source and the second constant voltage source, and the first and second constant voltage sources can be freely turned on and off by the two switching means. Measurement circuit. 9. A first resistance thermometer input device comprising a first constant voltage source in which diodes are serially connected in a forward direction and a first arithmetic unit in the temperature measurement circuit according to claim 7 or 8. And a second constant-voltage source in which diodes are connected in series in the forward direction and a second arithmetic unit constitute a second resistance-temperature detector input device. . 10. A voltage source in which a first constant voltage source in which diodes are connected in series in the forward direction and a second constant voltage source in which another diode is connected in series in the forward direction are connected in parallel with the same polarity, and temperature detection. Resistor, a first reference resistor, and a second reference resistor connected in series, and a current is supplied by applying a voltage from the voltage source; the temperature resistor and the first resistor A first calculating unit for calculating a measured temperature based on a potential difference between both ends of the reference resistor; and a second calculating unit for calculating a measured temperature based on a potential difference between both ends of the temperature measuring resistor and the second reference resistor. A temperature measuring circuit comprising: a constant voltage source, a reference resistor, and a dual computing unit. 11. The temperature measuring circuit according to claim 10,
Opening / closing means connected in series to each of the first constant voltage source and the second constant voltage source is provided, and the first and second constant voltage sources are provided by the two opening / closing means.
A temperature measuring circuit characterized in that the constant voltage source can be freely turned on and off. 12. The temperature measuring circuit according to claim 10 or 11, wherein a first constant voltage source having a diode connected in series in a forward direction, a first reference resistor, and a first calculation unit. A second resistance thermometer input device comprises a second constant voltage source in which diodes are connected in series in a forward direction, a second reference resistor, and a second arithmetic unit. A thermometer input device.