JP3210222B2 - Temperature measuring device - Google Patents

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 a temperature of an object to be measured.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing the configuration of a conventional temperature measuring apparatus. In the figure, reference numeral 11 denotes a housing, 12 denotes a heating element provided in the housing 11, such as a resistor, a relay, and an amplifier.
Reference numeral 3 denotes a thermocouple and a thermistor (hereinafter, referred to as a thermocouple) as a temperature sensor for generating a voltage according to the temperature of the device under test, 14 denotes an input terminal for connecting the thermocouple 13, and 15 denotes an input from the thermocouple 13. A temperature detection unit for detecting the temperature of the object to be detected based on a temperature detection output supplied via a terminal 14; 16 a substrate provided with a temperature detection unit 15; It is a heat insulating plate that separates the spaces.

FIG. 3 shows an equivalent circuit of the thermocouple 13. A temperature compensator 18 is connected between the input terminal 14 and the temperature detector 15, and compensates for a 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 conducting wire having a large number of bent portions, and separates the input terminal 14 from the temperature detecting section 15 and the like, and heat from the heating element 12 is transmitted via a wiring pattern or the like, and To prevent the terminal temperature from fluctuating. Further, when heat is transmitted through the air inside the housing, heat may gradually transfer to the input terminal 14 through the housing itself. To prevent the input terminal temperature from shifting due to such heat transfer,
The case 11 is enlarged, or the heat insulating plate 17 is provided inside the case, and 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, temperature measurement by accurate temperature compensation of the thermocouple 13 has been enabled. And 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 deviation between the actual temperature of the input terminal and the output value of the thermocouple 13 provided near the input terminal. Was.

[0005]

Since the conventional temperature measuring device is configured as described above, there are problems such as an increase in the 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 miniaturized without taking the above-described configuration, the temperature compensating unit 18 will be heated by the heat from the heating element after a lapse of time from power-on.
The temperature of the input terminal 14 gradually rises through the conducting wire of
There has been a problem that an error occurs in the temperature detection output of the thermocouple 13 and the temperature of the device to be measured cannot be accurately measured.

For this reason, it is conceivable to improve the accuracy of temperature measurement by compensating the temperature detection output from the thermocouple 13 based on the temperature rise of the input terminal 14, but in this case, the configuration of the temperature measurement device is complicated. There was a problem such as becoming.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object 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 apparatus, comprising: 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 apparatus; A delay unit for delaying a prediction error generated by the generation unit; and a compensation unit for compensating a temperature detection output from the temperature sensor based on the prediction error delayed by the delay unit.

According to a second aspect of the invention, there is provided a temperature measuring device, wherein the delay means is constituted by a first-order lag filter or an N-order 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 denotes a thermocouple (temperature sensor) that generates a temperature detection output according to the temperature of an object to be measured, and 2 denotes an input terminal to which the temperature detection output from the thermocouple 1 is supplied. Reference numeral 3 denotes a temperature detection unit that detects the temperature of the device under test from the temperature detection output supplied via the input terminal 2. Reference numeral 4 denotes an error generation unit (error generation means) for generating a prediction error based on heat generation of the heating element in the temperature measuring device. Reference numeral 5 denotes a first-order lag filter or N which delays the prediction error from the error generation unit 4. Reference numeral 6 denotes a second-order filter (delay means), 6 is a subtractor (compensation means) for calculating a difference between the temperature detected by the temperature detection unit 3 and the 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.

The error generating section 4 is composed of, for example, a constant voltage generating circuit or the like. The error of the temperature detection output of the thermocouple 1 due to heat generated by a heating element such as a resistor, a relay, and an amplifier in the temperature measuring device is represented by a numerical value. Generates error voltage. In particular,
This predicted error voltage Ve quantifies the error of the temperature detection output of the thermocouple 1 due to the heat generated by the individual heating elements such as the resistance, the relay, and the amplifier in the temperature measuring device as shown in the following equation 1, and all the errors for the heating elements are obtained. The error is accumulated and found.

[0012]

(Equation 1)

Here, the heat from the heating element is not transmitted to the input terminal 2 immediately after the power supply of the temperature measuring device is turned on, but is gradually transmitted with the lapse of time since the power supply is turned on. Gradually increase terminal temperature. For this reason, in this temperature measuring device, the predicted error voltage Ve from the error generator 4 is delayed by the Nth-order lag filter 5. The Nth-order lag filter 5 is, 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 delay filter 5 is determined in consideration of the speed of heat transfer from the heating element. Such an Nth-order delay filter 5 is constituted by, for example, a CR filter which is a first-order delay filter. In this case, the resistance is varied by adjusting the values of the resistance of the resistor R and the capacitance of the capacitor C.

Next, the operation will be described. When the thermocouple 1 is brought into contact with the object to be measured when measuring the temperature of the object to be measured, the thermocouple 1 generates a voltage (temperature detection output) corresponding to the temperature of the object to be measured. To the temperature detector 3. The temperature detector 3 detects the temperature of the device under test from the temperature detection output supplied from the thermocouple 1 and supplies the temperature to the subtracter 6. For example, if the temperature of the device under test is 25 ° C., the thermocouple 1 generates a voltage corresponding to the temperature of 25 ° C., and the temperature detection unit 3 determines that the temperature of the device under test is 25 ° C. based on the voltage supplied from the thermocouple 1.
And supplies the detected temperature to the subtractor 6 as a voltage Vd.

On the other hand, the error generator 4 generates the above-described predicted error voltage Ve, which is a predicted value of the error of the temperature detection output of the thermocouple 1 due to the heat generated by 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 section as heating elements in the temperature measuring device, and the error of the temperature detection output of the thermocouple 1 due to the heat generation is 0.1 ° C., respectively.
When the temperatures are 0.1 ° C. and 0.2 ° C., the error generator 4 sets the voltage corresponding to 0.4 ° C. which is the sum of these errors as the predicted error voltage Ve. The Nth-order 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 calculates the voltage Vd supplied from the temperature detector 3 and the prediction error voltage V delayed by the Nth-order delay filter 5.
The difference from e is obtained and output via the output terminal 7 as the detected temperature.

As described above, since the predicted error voltage indicating the error due to the heating of the heating element is delayed by the N-order delay filter 5 by the error generating section 4, the predicted error voltage is equivalently small immediately after the power is turned on. In addition, the prediction error voltage increases according to the elapsed time from the power-on. For this reason, even if the terminal temperature of the input terminal 2 fluctuates due to the lapse of time since the power-on, the output of the temperature detecting unit 3 can be compensated by the delayed prediction error voltage in accordance with the fluctuation of the terminal temperature. Thus, the temperature of the device under test can be accurately measured.

[0019]

As described above, according to the present invention, a delay means for generating a prediction error of a temperature detection output based on heat generation of a heating element in a temperature measuring device from an error generating means and delaying the generated prediction error. The temperature detection output from a temperature sensor such as a thermocouple or a thermistor is configured to be compensated based on the delayed prediction error, so that an error due to heat generation of a heating element in the temperature measuring device is compensated. Thus, the temperature of the device under test 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]

 DESCRIPTION OF SYMBOLS 1 Thermocouple (temperature sensor) 4 Error generation part (error generation means) 5 N-order lag filter (delay means) 6 Subtractor (compensation means) 11 Housing

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01K 7/00 G01K 1/20 G01D 3/028

Claims (2)

(57) [Claims] 1. A temperature sensor for outputting a temperature detection output corresponding to the temperature of an object to be measured, and an error generating means for generating a prediction error of the temperature detection output based on heat generation of a heating element in a housing provided with the temperature sensor. And a delay unit for delaying a prediction error generated by the error generation unit, and a compensation unit for compensating 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.