JPH05288611A - Temperature measuring apparatus - Google Patents

Abstract

PURPOSE:To enable temperature measurement with sensors of various kinds at a high accuracy with a simple construction by enabling the loading or unloading of a ore-amplification section corresponding to multiple kinds of sensor sections. CONSTITUTION:Radiation light is obtained with intensity thereof corresponding to a measuring temperature with a detector 1. The radiation light is inputted into a photoelectric conversion section 2 within a pre-amplification section 4 to convert the intensity of the light into a voltage signal. The amplification section 4 is arranged to enable the loading or unloading thereof and can be replaced with any pre- amplification section suitable for various sensor sections without individual adjustment. An analog voltage signal from the conversion section 2 is converted into a digital signal with an A/D converter 5a at an A/D conversion section 5 to be outputted to a digital signal processing section 6. The digital output from the conversion section 5 is inputted into a microprocessor CPU to be computed and converted into a value of temperature unit to be sent to an input/output circuit I/O. In the computation, characteristics and correction factors of the detector 1, the conversion section 2 and the like as stored in first and second nonvolatile memories 3 and 5b are read out to be used as arithmetic parameter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a temperature measuring device capable of measuring temperature by appropriately replacing various temperature sensors suitable for an object to be measured.

[0002]

2. Description of the Related Art Sensors such as thermocouples and resistance temperature detectors are used for temperature measurement. These sensors output physical quantities of analog values corresponding to the temperature to be measured. For example, in the case of a thermocouple, thermoelectromotive force corresponding to temperature is output as an electric signal. Then, this physical quantity is converted into a temperature unit that is normally used. Conventionally, in such conversion, the output from the sensor is converted and amplified as an electric signal, and then a conversion circuit corresponding to each sensor is used to calculate the temperature using a conversion table (conversion formula). For example, by using a circuit such as a photoelectric conversion circuit or a linear approximation circuit as a conversion circuit, an instruction is given by an analog meter, or A / D conversion (analog-
Digital conversion), and then convert to temperature units by digital operation using a microcomputer, etc.
The temperature was displayed as a digital value.

[0003]

In the conventional temperature measuring device, it was difficult to deal with many kinds of sensors with the same temperature measuring device.

That is, the output of the sensor differs depending on its type. For example, in the temperature measurement using radiant light, the sensor output is light, in the temperature measurement using a thermocouple, the sensor output is voltage, and in the resistance thermometer, the sensor output is obtained as a resistance value. A separate conversion circuit is required according to the type. Therefore, in order to support all of these sensors, it is necessary to prepare various conversion circuits and change the amplification factor or the like according to the sensor, which makes the device complicated.

Further, if such a large number of conversion circuits are provided, it is necessary to prepare a conversion table and conversion formulas corresponding to those sensors. In order to obtain high accuracy, a strict conversion table and conversion formula are required, and the amount of data for that becomes huge, and the temperature measuring device becomes complicated.

Particularly, in the case of temperature measurement using radiant light as a sensor signal, such a problem becomes remarkable. Since light measurement is required, photoelectric conversion is included, and sensitivity calibration according to each sensor is required in a wide intensity range.

An object of the present invention is to solve the above problems and to provide a temperature measuring device having a simple structure capable of measuring temperature with different kinds of sensors with high accuracy.

[0008]

A temperature measuring device according to the present invention comprises: (a) a sensor section for outputting a sensor signal of a physical quantity having an analog value corresponding to a measured temperature; and (b) converting the sensor signal into an analog electric signal. A pre-amplification unit corresponding to the sensor unit, and a non-volatile memory unit that holds the characteristics of the sensor unit and the sensor conversion unit as a digital value, and (c) the pre-amplification unit. And a conversion unit that detachably mounts the conversion unit, converts the output of the sensor conversion unit into a digital signal, and a calculation unit that calculates the digital signal and the digital value read from the nonvolatile memory unit and outputs the temperature. And a main body including and.

The measuring method using the temperature measuring device according to the present invention is as follows. First, a correction value (error coefficient) is obtained by holding the sensor unit in a predetermined temperature state for calibration and measuring the temperature. The correction value is stored in the nonvolatile memory unit. Next, the sensor unit is installed at the target temperature measurement position, and a sensor signal is obtained from the sensor unit. The sensor converter converts the sensor signal into an analog electric signal. Then, the analog electric signal is converted into a digital signal by the conversion unit, and the measured temperature is calculated by the calculation unit using the digital signal, the correction value stored in the non-volatile memory unit, and other information about the sensor unit and the sensor conversion unit. Calculate

[0010]

According to the present invention, the preamplifier corresponding to many kinds of sensor units can be attached / detached, and the conversion unit for digital signals and the digital operation unit are common. It is possible to use an optimum sensor conversion unit for each of the above, and a temperature measuring device having a simple structure is possible. At the same time, the non-volatile memory provided in each preamplifier holds the characteristic values related to the sensor unit and the sensor conversion unit such as calibration values as digital values, so all data for temperature conversion is prepared in the main body. There is no need, and the structure of the temperature measuring device can be simplified. in addition,
Since the correction coefficient at the time of calibration is stored using the non-volatile memory, it is easy to change these coefficients in the usage state.

Therefore, according to the present invention, a temperature measuring device having a simple structure enables temperature measurement by a large number of different sensor units with high accuracy.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A temperature measuring device according to an embodiment of the present invention will be described in detail below with reference to FIGS. First,
An embodiment using a black body radiator as the sensor unit will be described.

The detector 1 provided with a noble metal thin film blackbody radiator at the tip of the optical waveguide is used as the sensor section. By thermally coupling the tip portion of the detector 1 to the portion to be measured, it is possible to obtain radiant light having an intensity corresponding to the measurement temperature.

This radiant light is input to the photoelectric conversion section 2 which is a sensor conversion section via an optical fiber. Photoelectric conversion unit 2
At, the light intensity of the radiant light is converted into a voltage signal. The photoelectric conversion section 2 constitutes a preamplification section 4 together with a first nonvolatile memory 3 which is an EEPROM (electrically erasable read memory). The photoelectric conversion unit 2 is composed of an optical / electrical converter such as a photodiode and a current / voltage converter for converting the output current of the photoelectrical conversion unit 2 into an optimum voltage for the next stage.

The analog voltage signal output from the photoelectric conversion unit 2 is input to the A / D conversion unit 5 and converted into a digital signal. The A / D converter 5 includes an A / D converter 5a and an EEP.
The second non-volatile memory 5b is composed of a ROM (electrically erasable reading memory). This A
In the D / D converter 5a, the input signal is amplified by the amplifier, and the signal matching unit (Signal Conditioner) A
A / D after being converted to an analog voltage suitable for the D / D converter
D converted.

The digital signal processing unit 6 serving as an arithmetic unit is a microprocessor connected by a digital data bus.
It is composed of a CPU, a RAM memory RAM, a ROM memory ROM, a non-volatile memory EPM, and an interface circuit I / F. The digital output from the A / D converter 5 can be accessed from the microprocessor CPU via the interface circuit I / F. Microprocessor cpu
According to the program stored in the ROM memory ROM, the RAM memory RAM is used as a work area, and calculation for converting the digital output from the A / D conversion unit 5 into a temperature unit value such as Celsius is performed.

During this calculation, the interface circuit I / F
The characteristic and the correction coefficient of the detector 1 and the photoelectric conversion unit 2 stored in the first non-volatile memory 3 are read out via the, and the characteristic and the correction coefficient stored in the second non-volatile memory 5b. Is read out and used as a parameter for calculation to the temperature. The coefficient stored as digital data in the first non-volatile memory 3 is an optical and electrical error coefficient (optical / optical) calculated during calibration of temperature measurement.
The conversion efficiency of the electric converter, the conversion rate of the current / voltage converter, the actual measurement value of each calibration coefficient, the spectral transmission characteristic of the optical system, etc.) and the value set at the time of factory shipment are stored. The coefficient representing the conversion characteristic of the A / D conversion unit 5 is also stored in the second non-volatile memory 5a as digital data. In addition, the amplification degree and operation mode of the photoelectric conversion unit 2 and the A / D converter 5a are controlled by the first interface circuit I / F.
Of the digital signal processing unit 6 based on the data stored in the nonvolatile memory 3 and the second nonvolatile memory 5a.
It is controlled by.

The temperature value calculated in this manner is output from the input / output circuit I / O via the interface circuit I / F. As the output means, there are a display section composed of a liquid crystal display, a D / A conversion section which converts the temperature value into an analog signal again and outputs it, a communication circuit which is connected to a standard communication means by a digital signal, an alarm output circuit, It is equipped. The input / output circuit I / O also includes a key input unit for inputting temperature display parameters and the like. These output modes, parameters, etc. are stored in the non-volatile memory EPM, which is an EEPROM, and can be changed arbitrarily during temperature measurement.

A temperature measuring device 7 comprising the above-mentioned preamplifier 4, A / D converter 5, and digital signal processor 6.
In the above, the preamplification unit 4 and the A / D conversion unit 5 are plugged in the main body of the temperature measuring device 7, and have a structure that can be easily removed and replaced.

As another example of the replaceable preamplifier section 4,
A preamplifier 4'suitable for temperature measurement using a thermocouple will be described with reference to FIG.

A thermocouple is used as the detector 1 ', and this thermoelectromotive force is input to the preamplifier 4'. In the sensor conversion unit 2 ′ of the preamplification unit 4 ′, the minute thermoelectromotive force is amplified to an appropriate voltage as an input of the A / D conversion unit 5 and output from the preamplification unit 4 as an analog voltage. .. The sensor conversion unit 2 ′ constitutes a preamplification unit 4 ′ together with the first nonvolatile memory 3 ′ which is an EEPROM (electrically erasable read memory).

The first non-volatile memory 3'stores, as digital data, the values set at the time of factory shipment corresponding to the thermocouple used as the detector 1'and the coefficients calculated at the time of calibration.

When the preamplification section 4 of the embodiment of FIG. 1 is replaced by the preamplification section 4'of the embodiment of FIG. 2, the digital signal processing section 6 includes a first non-volatile memory 3 '. It is possible to control the preamplifier 4 ′ and the A / D converter 5 according to the information stored in, and perform a digital operation on the digital output from the A / D converter 5. Therefore, the preamplifier suitable for various sensor units does not require individual adjustment (output level adjustment, etc.), and can be replaced without adjustment. Note that the A / D converter 5 can be easily removed and replaced so that the temperature measuring device can be easily maintained and inspected.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining a temperature measuring device using a black body radiator which is an embodiment of the present invention.

FIG. 2 is a block diagram for explaining a sensor conversion unit suitable for the temperature measuring device according to the embodiment of the present invention.

[Explanation of symbols]

 1, 1 '... Detector (sensor section, thermocouple), 2, 2' ... Photoelectric conversion section (sensor conversion section), 3, 3 '... First non-volatile memory, 4, 4' ... Preamplification section , 5 ... A / D converter, 5a ... A / D converter, 5b ... Second non-volatile memory, 6 ... Digital signal processor, 7 ... Temperature measuring device main body, CPU ... Microprocessor, RAM ... RAM memory , ROM ... ROM memory, EPM ... Non-volatile memory, I / F ... Interface circuit, I / O ... Input / output circuit.

Claims (1)

[Claims] 1. A sensor unit for outputting a sensor signal of a physical quantity having an analog value corresponding to a measured temperature; (b) a sensor conversion unit for converting the sensor signal into an analog electric signal; and the sensor unit and the above. A non-volatile memory unit that holds the characteristics of the sensor conversion unit as a digital value, and a preamplification unit corresponding to the sensor unit, and (c) the preamplification unit is detachably attached, and the sensor conversion unit And a converter for converting the output of the above into a digital signal and a calculator for calculating the digital signal and the digital value read from the non-volatile memory unit and outputting the temperature. And a temperature measuring device.