JPH0915053A - Infrared temperature measuring apparatus - Google Patents

Abstract

PURPOSE: To obtain a highly accurate infrared temperature measuring apparatus. CONSTITUTION: The infrared temperature measuring apparatus comprises a thermistor THR1 to which a voltage is applied through a resistor R1, a chopper 4 for intercepting the infrared rays incident on the thermistor THR1 intermittently, a temperature regulator 5 for the thermistor THR1, and a section 6 for controlling the temperature regulator 5 based on a signal corresponding to the voltage across a resistor R1 so that the difference of voltage across the resistor R1 will be zero when the infrared rays are intercepted, and when not intercepted. Consequently, the relationship between the resistance of thermistor THR1 and the temperature requires no correction and the aging of thermistor THR1 gives no adverse effect. Furthermore, fluctuation in the characteristics among a plurality of thermistors gives no adverse effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared temperature measuring device for capturing infrared rays and measuring the temperature of a temperature measured object.

[0002]

2. Description of the Related Art An example of a conventional infrared temperature measuring device will be described with reference to the circuit diagram of FIG. In the figure, THR1 is an thermistor for detecting infrared rays, and is arranged so that the infrared rays emitted from the temperature-measuring object are directly incident thereon. THR2 is a thermistor for temperature compensation. A resistor R1 is connected in series to the infrared detection thermistor THR1, and the temperature compensation thermistor THR2
A resistor R2 is connected in series to the infrared detection thermistor.
Series circuit of THR1 and resistor R1 and thermistor THR2 for temperature compensation
And a series circuit of the resistor R2 are connected in parallel to form a bridge circuit 1. The connection point between the infrared detection thermistor THR1 and the temperature compensation thermistor THR2 is connected to the high potential side of the power supply E, and the connection point of the resistors R1 and R2 is connected to the low potential side of the power supply E.

A1 is an infrared detection thermistor THR1.
And resistance R1 connection point, temperature compensation thermistor THR2 and resistance
An amplifier that amplifies the voltage V1 between the connection points of R2, A2 is an amplifier that amplifies the voltage V2 across the resistor R2. The voltage V1 is a signal that reflects the temperature difference between the temperature-measuring object and the infrared detection thermistor THR1, and the voltage V2 is a signal that reflects the temperature of the infrared detection thermistor THR1 at room temperature, that is, in a state where infrared rays are not absorbed. These voltages V1 and V2 are input to the signal processing circuit 2 after being amplified by the amplifiers A1 and A2, respectively. The signal processing circuit 2 is configured to process the input signal and calculate the temperature of the temperature measured object based on the theoretical equation shown in the equation (1). R = R ₀ EXP {B (1 / T ₀ -1 / T)} (1) where R ₀ is the resistance value of the thermistor at the reference temperature T ₀ (K),
B is the thermistor constant.

[0004]

When the temperature is measured using the infrared temperature measuring device shown in FIG. 3, the amplifiers A1 and A2 are included in addition to the error factors included in the theoretical formula (equation (1)).
Since there were errors due to error factors such as offset voltage in the and the infrared detection thermistor THR1 and temperature compensation thermistor THR2 characteristics, various correction processes are usually performed to improve the measurement accuracy. It was But,
As a result, the circuit becomes quite complicated and large in scale, and there is a problem in that the accuracy that can be obtained is limited.

The present invention has been made in view of the above problems. An object of the present invention is to correct an infrared temperature measuring device using a thermistor without being affected by variations in thermistor characteristics. Another object of the present invention is to provide a highly accurate infrared temperature measuring device structure.

[0006]

In order to achieve the above object, the infrared temperature measuring device according to claim 1 is a thermistor to which a voltage is applied via a resistor connected in series, and an infrared ray incident on the thermistor. A chopper for intermittently shutting off the temperature, temperature adjusting means arranged in the vicinity of the thermistor for adjusting the temperature of the thermistor, and inputting a signal according to the voltage across the thermistor or the voltage across the resistor, infrared rays are emitted. And a temperature controller for controlling the temperature of the temperature adjusting means so that the difference between the voltage across the thermistor or the voltage across the resistor when the infrared light is not blocked is zero. It is a feature.

An infrared temperature measuring device according to a second aspect of the present invention is a thermistor to which a voltage is applied via a resistor connected in series, a chopper for intermittently interrupting the infrared ray incident on the thermistor, and both ends of the thermistor. A signal corresponding to the voltage or the voltage across the resistor is input so that the difference between the voltage across the thermistor and the voltage across the resistor when the infrared light is blocked and when the infrared light is not blocked is zero. And a temperature controller for controlling the temperature of the chopper.

[0008]

The infrared temperature measuring device according to claim 1 applies a voltage to a series circuit of a thermistor for detecting infrared rays and a resistor,
It is characterized in that the voltage across the thermistor or the voltage across a resistor is measured while the infrared rays radiated from the temperature measured object to the thermistor are intermittently cut by the chopper. If the temperature of the object to be measured and the temperature of the thermistor are different, the voltage across the thermistor or the voltage across the resistor becomes a signal containing an AC component that changes according to the opening and closing of the chopper.
Here, the temperature control unit controls the temperature so that the AC component of the voltage across them becomes zero, that is, the voltage across the thermistor or the voltage across the resistor becomes constant regardless of the open / closed state of the chopper. If the temperature of the thermistor is adjusted by adjusting the temperature of, the temperature of the temperature adjusting means (thermistor) at this time becomes the temperature of the temperature measured object.

In the infrared temperature measuring device according to the second aspect of the invention, a voltage is applied to a series circuit of a thermistor and a resistor, and while infrared rays radiated from the temperature measured object to the thermistor are interrupted by a chopper, the voltage across the thermistor or the resistance. Is the same as the infrared temperature measuring device according to claim 1, but the infrared temperature measuring device according to claim 2 is that the AC component of the voltage across the thermistor or the voltage across the resistor is zero. Therefore, the temperature of the chopper is adjusted by the temperature control unit so that the temperature of the chopper when the AC component of the voltage across the thermistor or the voltage across the resistor becomes zero is the temperature of the measured object. Becomes

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the infrared temperature measuring device of the present invention will be described based on the block diagram of FIG. In the figure, THR1 is a thermistor and is arranged so that the infrared rays emitted from the DUT 3 are directly incident thereon. A resistance R1 is connected in series to the thermistor THR1, and the power supply voltage Vdd is applied to the series circuit. Reference numeral 4 denotes a chopper which is arranged between the temperature measured object 3 and the thermistor THR1 and intermittently blocks infrared rays incident on the thermistor THR1. Also, A1
Is an amplifier for amplifying the voltage across the resistor R1, 5 is a temperature adjusting device for adjusting the temperature of the thermistor THR1, which is arranged in the vicinity of the thermistor THR1 as a temperature adjusting means, 6 is an input of the output of the amplifier A1, and is a chopper 4 The temperature control unit controls the temperature of the temperature adjusting device 5 so that the difference between the voltages across the resistor R1 when the infrared light is blocked and when the infrared light is not blocked is zero. In addition, although means for driving the chopper 4 and the like are provided, only the main configuration is shown in FIG. 1 and other configurations are omitted.

Next, the operation of the infrared temperature measuring device shown in FIG. 1 will be described. Before the measurement, the chopper 4 is in a closed state, and the infrared rays emitted from the temperature measured object 3 are not incident on the thermistor THR1. The voltage across the resistor R1 (DC voltage) is input to the amplifier A1. At the time of measurement, the chopper 4 is kept open for a certain period of time. As a result, the infrared rays emitted from the temperature measured object 3 enter the thermistor THR1. At this time, if the temperature of the DUT 3 is higher than the temperature of the thermistor THR1, the thermistor THR1
The resistance value of the resistor R1 decreases, and the voltage across the resistor R1 and the output voltage of the amplifier A1 increase. In this case, the temperature controller 6 controls the temperature adjusting device 5 to raise the temperature of the thermistor THR1.

After that, the chopper 4 is opened again for a certain period of time. At this time, if the temperature of the DUT 3 is lower than the temperature of the thermistor THR1, the temperature control unit 6
Controls the temperature adjusting device 5 to operate to lower the temperature of the thermistor THR1. Repeat this operation, chopper 4
If the change in the voltage across the resistor R1 becomes zero when the is opened, the temperature of the thermistor THR1 (temperature adjusting device 5) at that time becomes the temperature of the temperature measured object 3.

A different embodiment of the infrared temperature measuring apparatus of the present invention will be described with reference to the configuration diagram of FIG. However, the same components as those shown in FIG. 1 are designated by the same reference numerals. In the figure, THR1 is a thermistor, and the measured object 3
It is arranged so that the infrared rays emitted from it directly enter. A resistance R1 is connected in series to the thermistor THR1, and the power supply voltage Vdd is applied to the series circuit.
4 is placed between the DUT 3 and the thermistor THR1,
It is a chopper that intermittently blocks infrared rays that enter the thermistor THR1. The chopper 4 is made of a material whose temperature can be adjusted. A1 is an amplifier that amplifies the voltage across the resistor R1, 6 is the input of the output of the amplifier A1, and the difference between the voltage across the resistor R1 when the infrared rays are blocked by the chopper 4 and when the infrared rays are not blocked is zero. So that
A temperature control unit that controls the temperature of the chopper 4.

Next, the operation of the infrared temperature measuring device shown in FIG. 2 will be described. Before the measurement, the chopper 4 is in the closed state, and the infrared rays emitted from the temperature measured object 3 do not enter the thermistor THR1. The amplifier A1 has a resistor R1
The voltage between both ends (DC voltage) is input. At the time of measurement, the chopper 4 is kept open for a certain period of time. As a result, the infrared rays emitted from the temperature measured object 3 enter the thermistor THR1. At this time, if the temperature of the DUT 3 is higher than the temperature of the thermistor THR1, the resistance value of the thermistor THR1 decreases, and the voltage across the resistor R1 and the output voltage of the amplifier A1 increase. In this case, the temperature control unit 6
Operates to raise the temperature of the chopper 4.

After that, the chopper 4 is opened again for a certain period of time. At this time, if the temperature of the DUT 3 is lower than the temperature of the thermistor THR1, the temperature control unit 6
Operates to lower the temperature of the chopper 4. When this operation is repeated and the chopper 4 is opened, if the change in the voltage across the resistor R1 becomes zero, the temperature of the chopper 4 at that time becomes the temperature of the temperature measured object 3.

[0016]

In the infrared temperature measuring device according to the first or second aspect of the present invention, the temperature controllable temperature reference object (temperature control device) can be used without directly reading the temperature of the temperature measured object from the resistance value of the thermistor. The temperature of the temperature measurement object is measured by comparing the amount of infrared radiation emitted from the adjustment device and the chopper) with the amount of infrared radiation emitted from the temperature measurement object. Therefore, the resistance value of the thermistor and its temperature are measured. There is no need to correct the relationship. Further, it is not affected by changes in the characteristics of the thermistor due to changes over time. Furthermore, since only one thermistor is used, it is not affected by the characteristic variations among the thermistors. Therefore, the infrared temperature measuring device according to claim 1 or 2 enables highly accurate temperature measurement.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing another embodiment of the infrared temperature measuring device of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional infrared temperature measuring device.

[Explanation of symbols]

 R1 resistance THR1 thermistor 4 chopper 5 temperature adjustment device (temperature adjustment means) 6 temperature control unit

Claims (2)

[Claims] 1. A thermistor to which a voltage is applied through a resistor connected in series, a chopper that intermittently blocks infrared rays from entering the thermistor, and a temperature of the thermistor that is disposed in the vicinity of the thermistor. A temperature adjusting means for adjusting and a signal according to the voltage across the thermistor or the voltage across the resistor are input, and the voltage across the thermistor or the resistor in the case of blocking infrared light and the case of not blocking infrared light An infrared temperature measuring device, comprising: a temperature control unit that controls the temperature of the temperature adjusting unit so that the voltage difference between both ends becomes zero. 2. A thermistor to which a voltage is applied via a resistor connected in series, a chopper for intermittently blocking infrared rays from entering the thermistor, and a voltage across the thermistor or a voltage across the resistor. A temperature control unit that controls the temperature of the chopper so that the difference between the voltage across the thermistor or the voltage across the resistor when the infrared light is blocked and the infrared light is not blocked is zero. An infrared temperature measuring device comprising: