JPH09105678A - Temperature measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the detecting accuracy by providing a predicted error generating means for temperature detection output, a predicted error delay means and a temperature detection output compensating means from a temperature sensor. SOLUTION: A temperature detector 3 detects the temperature of a material to be measured from the temperature detection output supplied from a thermocouple 1, and supplies it to a subtracter 6. An error generator 4 generates the predicted error voltage Ve of the error of the output of the thermocouple 1 due to the heat generation of a heater, and supplies it to an N-th delay filter 5. The filter 5 delays the voltage Ve supplied from the generator 4, and supplies it to a subtracter 6. The subtracter 6 obtains the difference between the voltage supplied from the detector 3 and the voltage Ve delayed by the filter 5, and outputs it as the detection temperature via an output terminal 7. Thus, the predicted error voltage is equivalently low immediately after a power source is turned on, and the predicted error voltage increases in response to the lapse of time from the energization of the power source, and hence the compensation adapted fro the output change of the detector 3 can be executed to make it possible to accurately measure the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring device for detecting the temperature of an object to be measured.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the structure of a conventional temperature measuring apparatus. In the figure, 11 is a housing, 12 is a heating element such as a resistor, a relay, an amplifier, etc. provided in the housing 11.
3 is a thermocouple as a temperature sensor that generates a voltage according to the temperature of the object to be measured, a thermistor (hereinafter referred to as a thermocouple), 14 is an input terminal for connecting the thermocouple 13, and 15 is an input from the thermocouple 13. A temperature detection unit that detects the temperature of the object to be detected based on the temperature detection output supplied through the terminal 14, 16 is a substrate provided with the temperature detection unit 15, and 17 is a storage unit for the heating element 12 and the substrate 16. It is an insulation board that divides the space.

FIG. 3 shows an equivalent circuit of the thermocouple 13, wherein 18 is connected between the input terminal 14 and the temperature detecting section 15, and a temperature compensating section for compensating the temperature change of the input terminal 14,
19 is an output terminal.

Next, the operation will be described. The temperature compensating section 18 is composed of a conductor wire having a large number of bent portions, separates the input terminal 14 from the temperature detecting section 15 and the like, and heat from the heating element 12 is transferred through a wiring pattern or the like to thereby input the input terminal 14. Prevents fluctuations in the terminal temperature of. In addition, when the heat is transferred via the air inside the housing, the heat may be gradually transferred to the input terminal 14 through the housing itself. In order to prevent the shift of the input terminal temperature due to such heat transfer,
The housing 11 is enlarged, or the heat insulating plate 17 is provided inside the housing so that heat generated from the heating element 12 is not transmitted to the input terminal 14,
By always making the input terminal 14 equal to the temperature of the housing itself due to the outside air temperature, it is possible to perform temperature measurement by accurate temperature compensation of the thermocouple 13. Then, the input terminal 14
A heat insulating material or the like is provided between the housing and the housing 11 having the heating element 12 therein to prevent a difference between the actual temperature of the input terminal portion and the output value of the thermocouple 13 provided near the input terminal portion. It was

[0005]

Since the conventional temperature measuring device is constructed as described above, there are problems such as an increase in size of the device itself and an increase in cost due to the provision of the heat insulating plate 17. On the other hand, if the device itself is simply downsized without taking the above-described configuration, when the time elapses after the power is turned on, the temperature of the temperature compensator 18 is increased by the heat from the heating element.
The temperature of the input terminal 14 gradually rises through the lead wire of
There is a problem that an error occurs in the temperature detection output of the thermocouple 13 and the temperature of the object to be measured cannot be accurately measured.

Therefore, it is considered that the temperature detection output from the thermocouple 13 is compensated based on the temperature rise of the input terminal 14 to improve the accuracy of the temperature measurement, but in this case, the structure of the temperature measuring device is complicated. There was a problem such as becoming

The present invention has been made to solve the above problems, and an object thereof is to obtain a temperature measuring device with improved detection accuracy.

[0008]

According to a first aspect of the present invention, there is provided a temperature measuring device, an error generating means for generating a prediction error of a temperature detection output based on heat generation of a heating element in the temperature measuring device, and the error. The delay means delays the prediction error generated by the generating means, and the compensating means compensates the temperature detection output from the temperature sensor based on the prediction error delayed by the delay means.

In the temperature measuring device according to the second aspect of the invention, the delay means is constituted by a first-order lag filter or an N-th lag filter.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1. In FIG. 1, reference numeral 1 is a thermocouple (temperature sensor) that generates a temperature detection output according to the temperature of an object to be measured, and 2 is an input terminal to which the temperature detection output from the thermocouple 1 is supplied. And 3 is a temperature detection unit that detects the temperature of the object to be measured from the temperature detection output supplied via the input terminal 2. Further, 4 is an error generating unit (error generating unit) that generates a prediction error based on the heat generated by the heating element in the temperature measuring device, and 5 is a first-order lag filter or N for delaying the prediction error from the error generating unit 4. A next-delay filter (delay means), 6 is a subtractor (compensation means) for obtaining a difference between the temperature detected by the temperature detection unit 3 and a prediction error delayed by the N-order delay filter 5, and 7 is a subtractor. 6 is an output terminal for outputting the output signal of 6.

The error generating section 4 is composed of, for example, a constant voltage generating circuit and the like, and the error of the temperature detection output of the thermocouple 1 due to the heat generated by the heating elements such as the resistance, relay and amplifier in the temperature measuring device is numerically predicted. Generate an error voltage. In particular,
This prediction error voltage Ve digitizes the error of the temperature detection output of the thermocouple 1 due to the heat generation of individual heating elements such as resistors, relays and amplifiers in the temperature measuring device as shown in the following equation 1, The error is accumulated and calculated.

[0012]

(Equation 1)

Here, the heat from the heating element is not transferred to the input terminal 2 immediately after the power of the temperature measuring device is turned on, but is gradually transferred with the lapse of time after the power is turned on and the heat of the input terminal 2 is transferred. Gradually raise the terminal temperature. Therefore, in this temperature measuring device, the prediction error voltage Ve from the error generator 4 is delayed by the Nth delay filter 5. The Nth-order lag filter 5 is composed of, for example, a first-order lag filter having a transfer function G (s) as shown in the following Expression 2.

[0014]

(Equation 2)

The time constant T of the Nth-order lag filter 5 is determined in consideration of the heat transfer speed from the heating element, and the Nth-order lag filter 5 is constituted by a CR filter which is a first-order lag filter, for example. In such a case, the values of the resistance of the resistor R and the capacitance of the capacitor C are adjusted to change the values.

Next, the operation will be described. When the temperature of the object to be measured is measured, if the thermocouple 1 is brought into contact with the object to be measured, the thermocouple 1 generates a voltage (temperature detection output) according to the temperature of the object to be measured, and the thermocouple 1 generates the voltage via the input terminal 2. And supplies it to the temperature detector 3. The temperature detector 3 detects the temperature of the object to be measured from the temperature detection output supplied from the thermocouple 1 and supplies it to the subtractor 6. For example, if the temperature of the object to be measured is 25 ° C., the thermocouple 1 generates a voltage corresponding to this 25 ° C., and the temperature detection unit 3 detects that the temperature of the object to be measured is 25 ° C. from the voltage supplied from the thermocouple 1.
Is detected, and the detected temperature is supplied to the subtractor 6 as the voltage Vd.

On the other hand, the error generator 4 generates the above-mentioned prediction error voltage Ve, which is a predicted value of the error of the temperature detection output of the thermocouple 1 due to the heat generation of the heating element, and supplies it to the Nth-order delay filter 5. Specifically, there are a relay A, a relay B, and a voltage output unit as heating elements in the temperature measuring device, and the error in the temperature detection output of the thermocouple 1 due to these heat generation is 0.1 ° C.,
When the temperatures are 0.1 ° C. and 0.2 ° C., the error generating unit 4 sets the voltage corresponding to 0.4 ° C., which is the sum of these errors, as the prediction error voltage Ve. The Nth delay filter 5 delays the prediction error voltage Ve supplied from the error generator 4 and supplies it to the subtracter 6. The subtractor 6 receives the voltage Vd supplied from the temperature detection unit 3 and the prediction error voltage V delayed by the Nth delay filter 5.
The difference with e is obtained and output as the detected temperature via the output terminal 7.

As described above, since the error generating section 4 delays the prediction error voltage indicating the error due to the heat generation of the heating element by the Nth-order delay filter 5, the prediction error voltage is equivalently small immediately after the power is turned on. The prediction error voltage increases according to the time elapsed since the power was turned on. Therefore, even if the terminal temperature of the input terminal 2 fluctuates with the lapse of time after the power is turned on, the output of the temperature detection unit 3 can be compensated for the fluctuation of the terminal temperature by the delayed prediction error voltage. The temperature of the measured object can be accurately measured.

[0019]

As described above, according to the present invention, the delay means for causing the error generating means to generate the prediction error of the temperature detection output based on the heat generation of the heating element in the temperature measuring device and delaying the generated prediction error. Therefore, the temperature detection output from the temperature sensor such as a thermocouple or thermistor is compensated based on the delayed prediction error, so the error due to the heat generation of the heating element in the temperature measuring device is compensated. Then, the temperature of the measured object can be accurately measured.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing a conventional temperature measuring device.

FIG. 3 is an equivalent circuit diagram of a thermocouple.

[Explanation of symbols]

 1 Thermocouple (Temperature Sensor) 4 Error Generator (Error Generator) 5 Nth Delay Filter (Delay Means) 6 Subtractor (Compensation Means) 11 Housing

Claims (2)

[Claims] 1. A temperature sensor that outputs a temperature detection output according to the temperature of an object to be measured, and an error generating unit that generates a prediction error of the temperature detection output based on the heat generated by a heating element in a housing equipped with this temperature sensor. A temperature measuring device comprising: a delay unit that delays a prediction error generated by the error generation unit; and a compensation unit that compensates a temperature detection output from the temperature sensor based on the prediction error delayed by the delay unit. 2. The temperature measuring device according to claim 1, wherein the delay means is a first-order lag filter or an N-order lag filter.