JP2001021417A - Radiation thermometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exclude an error cause due to element characteristics of the like of a circuit component and to accurately measure by correcting digital data converted from a sensor output signal, a temperature signal based on conversion linearity of an A-D converter. SOLUTION: A CPU 5 controls a signal selecting circuit 10, inputs a reference input voltage from a reference voltage generator 11 to an A-D converter 4, executes a plurality of times of A-D conversions, and then obtains an error curve of conversion linearity from the relationship between the data and a charging time. At the start of a measurement, the CPU 5 A-D converts a sensor temperature signal of a temperature sensor 2 to obtain digital data. Then, the CPU A-D converts a sensor output signal of an infrared sensor 1 to obtain digital data. Then, the CPU 5 obtains A-D converted values of the sensor temperature signal and the sensor output signal from the error curve of the linearity, corrects the data of the temperature signal and the output signal by using the converted values, then measures a temperature to be measured, and displays the temperature on an LCD 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation thermometer for measuring the temperature of an object to be measured by infrared rays emitted from the object to be measured.

[0002]

2. Description of the Related Art As a radiation thermometer of this type, for example, an infrared thermometer for measuring by a method disclosed in Japanese Patent Application Laid-Open No. 8-145800 is known. This infrared thermometer is an infrared sensor, a probe that captures infrared rays from the ear canal, a temperature sensor that detects the temperature of the infrared sensor itself, a preamplifier (amplifier) that amplifies the output of the infrared sensor and the output of the temperature sensor, and an amplifier that is amplified by the preamplifier. An A / D converter for A / D converting the output of the infrared sensor and the output of the temperature sensor, and a CPU for calculating the temperature of the measurement target from the output of the A / D converted infrared sensor and the output of the temperature sensor ing.

In such an infrared thermometer, the temperature of the object to be measured is determined based on a predetermined calculation formula from the output of the infrared sensor and the output of the temperature sensor, which are captured as digital data by the CPU (for example, see JP-A-61-117422). Is calculated.

[0004]

However, in the case of the above prior art, however, the measurement accuracy or the measurement accuracy or the influence of the environmental temperature due to the element performance of the electronic circuit components constituting the infrared thermometer, the error factors depending on the circuit configuration, and the environmental temperature. It is difficult to increase measurement reliability. The problems are listed below for each factor.

[0005] First, digital data given to the CPU includes element characteristics of the A / D converter, particularly, whether the conversion linearity is good or not (whether the A / D conversion output is correctly proportional to the input signal level). Error is mixed. Specifically, A /
When a typical double integration type A / D converter is used as the D converter, the conversion linearity deteriorates due to the leakage current of the capacitor element constituting the integration circuit, and as a result, the measurement error in the infrared thermometer as described above. Is the cause of the occurrence.

Second, as a temperature sensor used in the infrared thermometer having the above-mentioned structure, a temperature-measuring resistance material such as a thermistor is often used. This is based on a change in the resistance value of the infrared sensor itself. Because it measures temperature, the circuit for detecting the resistance value of the thermistor is:
It is equivalently connected in parallel to the output circuit of the infrared sensor through the insulation leakage resistance, causing the output of the infrared sensor to leak and causing a part of the output not to be taken into the CPU.

Third, it is known that an amplifier generally has an offset voltage (or offset current) of an input circuit, and the level of an output voltage is largely shifted by the offset voltage (or offset current). Here, the offset voltage refers to a voltage obtained by converting an output voltage appearing at an output terminal in the absence of an input signal into an amplifier into a voltage on the input side. As a method of eliminating the offset voltage, a method of applying a voltage in a direction opposite to the offset voltage to the input terminal and a method of adjusting the bias of the transistor inside the amplifier are known. design"). However, there is a problem that such a method is not always stable against a change in temperature, and also causes an increase in the number of parts and complexity of the circuit.

Fourth, when a signal on which the offset voltage of the amplifier as described above is superimposed is input to the A / D converter, A
The signal component occupying the input signal level that can be / D converted is reduced. In this case, if the gain of the amplifier is increased, it exceeds the allowable input signal level of the A / D converter, so that the gain of the amplifier must be kept low. As a result, the signal components as the output of the infrared sensor and the output of the temperature sensor become small, resulting in a measurement error.

Fifth, a thermopile typically used as an infrared sensor in the infrared thermometer as described above is a sensor that generates an electromotive force due to a temperature difference between the temperature of the infrared sensor itself and the temperature of the object to be measured. When used as a thermometer, a measurement error occurs unless the temperature difference between the temperature of the use environment and the temperature of the measurement target is not stable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to eliminate an error factor due to an element characteristic or a circuit configuration of a circuit component constituting a radiation thermometer, and to provide a highly accurate measurement. It is to provide a radiation thermometer which can be used.

It is another object of the present invention to provide a radiation thermometer capable of preventing a radiation thermometer from being used in an environment where an error is likely to occur and performing highly reliable measurement.

[0012]

To achieve the above object, the present invention employs the following constitution. That is, the present invention provides an emission sensor including an infrared sensor that outputs a sensor output signal corresponding to the amount of infrared light emitted from a measurement target, and a temperature sensor that outputs a sensor temperature signal corresponding to the temperature of the infrared sensor itself. It is a thermometer and further includes the following configuration.

First, the present invention provides an A / D converter for converting a sensor output signal and the sensor temperature signal into digital data, and calculates a temperature of an object to be measured based on the digital data obtained by the A / D converter. And a control unit that performs the control.

The control unit is configured to convert the reference input signal as the reference input signal by the A / D converter based on a relationship between the digital data obtained by the A / D converter and information on the reference input signal. The linearity is measured, and at least one of the digital data converted from the sensor output signal and the digital data converted from the sensor temperature signal is corrected based on the converted linearity to calculate the temperature of the measurement target. .

In this case, when the deviation of the measured conversion linearity from the ideal conversion linearity is not less than a predetermined value,
It may further include a notifying unit for notifying that measurement cannot be performed.

Further, the A / D converter includes an integrator capable of setting a charging time by the control unit. The control unit sets a plurality of different charging times and sets a reference input by the A / D converter. A plurality of types of digital data converted from the signal may be obtained, and the conversion linearity may be detected from the relationship between the plurality of types of digital data and the charging time.

[0017] The control unit may determine a leakage resistance of the integrator based on a relationship between digital data converted from a reference input signal as an input signal to be a reference by the A / D converter and information related to the reference input signal. May be calculated, and the measured amount of each sensor may be corrected based on the leakage resistance.

Secondly, the present invention is a radiation thermometer provided in such a manner that the temperature sensor is in contact with the infrared sensor, and the temperature sensor is in contact with the infrared sensor. A contact leakage current prevention means is provided for preventing the generated leakage current from affecting the sensor output signal.

Third, the present invention provides an amplifier including an inverting input terminal and a non-inverting input terminal for amplifying the sensor output signal, and an amplifier for converting the sensor output signal to the inverting input terminal or the non-inverting input terminal. An input switch section for connecting to one of them, and a control section for calculating a temperature of a measurement target based on the sensor output signal amplified by the amplifier and the sensor temperature signal.

The control section calculates the temperature of the object to be measured based on a difference signal between the sensor output signal amplified from the inverting input terminal and the sensor output signal amplified from the non-inverting input terminal.

Fourth, the present invention provides a bias generation source for superimposing a bias on the sensor output signal, an amplifier for amplifying the sensor output signal, and an amplifier for amplifying the sensor output signal and the sensor temperature signal. An A / D converter that converts the data into digital data and a control unit that calculates the temperature of the measurement target based on the digital data obtained by the A / D converter are provided.

The bias of the bias source is controlled such that the amplified sensor output signal falls within a predetermined input signal allowable range of the A / D converter.

The bias of the bias generation source may be controlled based on a preset predicted temperature of the measurement object and digital data converted from the sensor temperature signal.

When an amplifier for amplifying the sensor output signal is included, the gain of the amplifier for amplifying the sensor output signal may be controlled based on a preset temperature of the object to be measured and the sensor temperature signal. .

When the A / D converter includes an integrator, an A / D converter for A / D-converting a sensor output signal based on a preset predicted temperature of the object to be measured and the sensor temperature signal.
The charging time of the integrator included in the converter may be controlled.

Fifth, the present invention provides an A / D converter for converting the sensor output signal and the sensor temperature signal into digital data.
A converter and a control unit for calculating the temperature of the measurement target based on the digital data obtained by the A / D converter are provided.

The control section reads digital data converted by the A / D converter from the sensor temperature signal at predetermined time intervals.

At the end of input of the digital data converted from the sensor temperature signal from the A / D converter to the control unit,
When the power supply to the temperature sensor or the A / D converter is stopped and the input of the digital data converted from the sensor temperature signal is started, the temperature sensor or the A / D converter in the power supply stopped state May be restarted.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A radiation thermometer according to Embodiment 1 will be described with reference to FIG. 1 and FIG.
FIG. 1 is a block diagram of a radiation thermometer according to Embodiment 1 of the present invention, and FIG. 2 is a flowchart showing the operation.

<Configuration of Radiation Thermometer> FIG. 1 is a block diagram showing the configuration of the radiation thermometer. This radiation thermometer,
An infrared sensor 1 that detects infrared rays emitted from a measurement target (for example, an eardrum in an ear canal); a temperature sensor 2 that measures the temperature of the infrared sensor 1 itself; an output (sensor output signal) and a temperature of the infrared sensor 1 An amplifier 3 that receives the output (sensor temperature signal) of the sensor 2 and amplifies the output;
A reference voltage generator 11 for generating a reference voltage as a reference input voltage; a sensor output signal amplified by the amplifier 3;
An A / D converter 4 for converting a sensor temperature signal and a reference input voltage into digital data; and a sensor output signal, a sensor temperature signal, and a reference input voltage amplified by the amplifier 3 in accordance with an input switching signal. A signal selection circuit 10 connected to the input circuit of the A / D converter 4, and a control target program which executes a control program and converts the temperature of the measurement target based on the sensor output signal and the sensor temperature signal converted into digital data by the A / D converter 4. CPU 5 (corresponding to a control unit) to calculate, and LCD for displaying the temperature of the measurement target calculated by CPU 5
6 (liquid crystal display) and a memory 7 for storing control programs and data.

The infrared sensor 1 is composed of a thermopile, and generates a sensor output signal (electromotive force) by receiving infrared rays from the object to be measured.

The temperature sensor 2 is composed of a thermistor,
A contact with the infrared sensor 1 detects a change in temperature of the infrared sensor 1 itself as a change in resistance value. The change in the voltage across the thermistor due to the change in the resistance corresponds to the sensor temperature signal.

The amplifier 3 receives the output of the infrared sensor 1 (sensor output signal) and the output of the temperature sensor 2 (sensor temperature signal), and amplifies the output to a signal level convertible by the A / D converter 4.

The voltage generated from the reference voltage generator 11 is used as a reference input voltage when the CPU 5 measures the conversion linearity of the A / D converter 4.

The signal selection circuit 10 selects one of the sensor output signal amplified by the amplifier 3 in accordance with the switching signal input from the CPU 5, the sensor temperature signal, and the reference input voltage generated by the reference voltage generator 11. Connect to the input terminal of A / D converter 4.

The processing of the A / D converter 4 and the CPU 5 will be described in detail below. <Conversion method of A / D converter> The A / D converter 4 converts the sensor output signal and the sensor temperature signal amplified by the amplifier 3 into digital data. In the present embodiment,
As the A / D converter 4, a double integration type A / D converter composed of an integrating circuit (corresponding to an integrator), a comparator, and a counter is adopted (for example, Noriyuki Ito, "Digital Circuit" published by Nihon Riko Publishing Co., Ltd., Section 16.3, Section 2) Refer to the multiple integration type AD converter). FIG. 14 shows a configuration of a double integration type A / D converter.

The A / D converter of this system integrates an input signal V1 to be converted by an integration circuit for a fixed period T1 (hereinafter referred to as a charging time), and integrates this with a known discharge reference voltage.
Discharge is performed at V2, and digital data of the input signal V1 is obtained from the time T2 required for the discharge (actually, the number of clocks measured by the counter), the charging time T1, and the discharge reference voltage V2. This relationship is represented by the following (Equation 1).

T2 = −T1 × (V1-V3) / (V2-V3) (1) where V1 is the voltage of the input signal.

V2: Reference voltage for discharge.

V3: Reference potential of the A / D converter 4.

T1 is the charging time of the integrating circuit by the input signal.

T2: Discharge time.

The input signal voltage (V1
-V3) is proportional to the discharge time T2, so the gate signal that is turned on during the discharge time T2 passes the reference clock pulse and counts with a counter. Data can be obtained. <Process of CPU> The CPU 5 executes the control program stored in the memory 7 and calculates the temperature of the measurement target from the sensor output signal and the sensor temperature signal converted into digital data. At that time, the CPU 5 supplies a reference input voltage from the signal selection circuit 10 to the A / D converter 4 by inputting a switching signal to the signal selection circuit 10 and measures the conversion linearity of the A / D converter 4 in advance. In advance, the temperature of the measurement target is corrected based on the result. Hereinafter, the processing of the CPU 5 will be described in detail.

Now, in the above-mentioned double integration type A / D converter, an A / D conversion output (digital data) obtained when the same reference input voltage is A / D converted in two kinds of charging times T1a and T1b. Are ADa and ADb, and when the above (Equation 1) is satisfied, T1a / T1b = ADa / ADb... (Equation 2) is satisfied. That is, even when the same input signal is A / D converted, the A / D conversion output is proportional to the charging time of the integration circuit. This is equivalent to changing the various input signal voltages (V1-V3) to A / D at the same charging time T1 in (Equation 1).
The result is the same as the result of the conversion.

However, in an actual double integration type A / D converter, (Equation 2) is not always satisfied due to the influence of the leakage current of the capacitor of the integration circuit. This is equivalent to the fact that when various input signal voltages are A / D converted in the same charging time, an A / D conversion output (digital data) that is not necessarily proportional to the input signal voltage is obtained, that is, a double It shows an error in the conversion linearity of the integrating A / D converter. Then, X = T1a / T1b-ADa / ADb ..... (Equation 3) is measured by changing the charging time, and if this error is obtained in advance, the actual A / D conversion output (digital data) can be calculated. Can be corrected.

FIG. 3 is a graph in which the charging time is plotted on the horizontal axis, the output (digital data) measured by A / D conversion of the same reference input voltage at various charging times is plotted on the vertical axis.
Theoretical value 1 shown by a solid line in an example in which a plurality of 1s are plotted.
It is a graph shown with 00. In FIG. 3, a plurality of measured values 101 correspond to conversion linearity, and a theoretical value 100 corresponds to ideal conversion linearity.

FIG. 4 is a graph in which the measured value 101 of the A / D conversion output (digital data) shown in FIG.
12 is a graph showing an error curve 102 obtained by plotting an error from a theoretical value (ideal conversion linearity) at that time on a vertical axis. Correcting the actual A / D conversion output (digital data) with the value obtained from the empirical formula (error curve) in FIG. 4 eliminates the error from the theoretical value 100 of the conversion linearity shown in FIG. Can be. Such an empirical formula is
It can be generally obtained by the least square method.

In this embodiment, the CPU 5 stores the coefficient of the error curve 102 (experimental formula) shown in FIG. A / D conversion output (digital data)
Is corrected, and the temperature of the measurement target (the eardrum) is calculated based on the corrected digital data. <Example of Operation> Next, an example of the entire operation of the radiation thermometer shown in FIG. 1 will be described with reference to the flowchart of FIG.

First, when a power switch (not shown) is turned on (step 101 (hereinafter abbreviated as S101)), the CPU 5
Executes the control program stored in the memory 7 to execute the following operation.

First, the CPU 5 controls the signal selection circuit 10 to connect the reference input voltage from the reference voltage generation unit 11 to the input terminal of the A / D converter 4 and then to charge the integration circuit with a plurality of charges. Set the charging time to A / D converter 4 and
The / D conversion is executed a plurality of times to obtain an error curve 102 of the conversion linearity shown in FIG. 4 (S102). Thereafter, the CPU 5 enters a standby state (S103).

When a measurement start switch (not shown) is pressed,
The CPU 5 detects that the measurement start switch has been pressed, and starts the measurement using the detection as a trigger (S104).

First, the sensor temperature signal of the temperature sensor 2 is expressed by A /
D conversion is performed to obtain the digital data (S105).

Next, the sensor output signal of the infrared sensor 1 is set to A /
D conversion is performed to obtain the digital data (S106).

Next, the CPU 5 calculates an A / D conversion correction value of the sensor temperature signal and the sensor output signal from the error curve 102 of the conversion linearity obtained in the processing of S102 (S107).

Then, using the A / D conversion correction value, S
After correcting the digital data of the sensor temperature signal and the sensor output signal obtained in the processes of 105 and S106, the temperature of the measurement target is obtained using these, and displayed on the LCD 6 (S1).
08).

In this way, every time the power switch is turned on, the CPU 5 obtains the conversion linearity of the A / D converter 4 and corrects the error due to the deviation from the theoretical value. Even if a change with time or a change in temperature occurs, the temperature of the measurement target is obtained using the A / D conversion output in which an error due to a deviation from the theoretical value of the conversion linearity is corrected in accordance with the change. Therefore, the accuracy of the temperature measurement by the radiation thermometer can be improved. <Modification> In the configuration of FIG. 1 described above, the output (reference input voltage) of the reference voltage generator 11 is directly transmitted through the signal selection circuit 10.
Although connected to the A / D converter 4, the reference input voltage from the reference voltage generator 11 may be input to the signal selection circuit 10 through the amplifier 3 instead. By doing so, the conversion linearity of the amplifier 3 and the A / D converter 4 can be measured and corrected.

The infrared sensor 1 or the temperature sensor 2
If the output signal is sufficiently large and can be converted by the A / D converter 4, these signals are directly converted by the A / D converter 4
If the / D conversion is performed, the amplifier 3 can be omitted.

In this embodiment, the digital data is corrected by generally measuring the conversion linearity of the A / D converter 4. However, the cause of the error as illustrated in FIG. 3 or FIG. Digital data may be corrected by assuming a leakage current of a capacitor in the integration circuit in the / D converter 4 and obtaining the leakage resistance.

Now, the resistance of the integration circuit is R, the capacitance is C,
Assuming that the output voltage of the integrated signal is V0, when the input signal voltage is the reference input voltage Vi (constant), the output voltage of the integration circuit is expressed by the following (Equation 4). V0 = ViT1 / CR (Equation 4) Here, T1 is a charging time of the integration circuit.

However, there is a leakage current in the capacitor of the integration circuit, which is Δi1 (the equivalent leakage resistance value at that time is represented by r
Assuming 1), the output voltage is as shown in the following (Equation 5).

[0062] On the other hand, when the capacitor of the integrating circuit charged to V0 is discharged at the reference voltage Vr, V0 = VrT2 / CR (6) where T2 is the discharging time of the integrating circuit.

However, there is a leakage current in the capacitor of the integration circuit, which is represented by Δi2 (the equivalent leakage resistance value at that time is represented by r
Assuming 2), the output voltage is as shown in the following (Equation 7).

[0064] Therefore, a known reference input voltage Vi is input to the integration circuit of the A / D converter 4, and the actual measured value of the integration circuit output V0 when the integration is performed for a predetermined charging time T1 and the value calculated by the theoretical equation (Equation 4) The leakage resistance r1 is calculated from the difference (Eq. 5), and the charged voltage V0 is used as a reference voltage for discharging.
The leakage resistance r2 can be calculated according to (Equation 7) from the difference between the measured value of the discharge time T2 when discharging at Vr and the theoretical equation (Equation 6).

Therefore, these R, r 1, and r 2 are stored in the memory, and the CPU 5 corrects the output of the A / D converter 4 according to (Equation 5) and (Equation 7). Similar results can be obtained. This expresses the interpretation of the deviation from the theoretical value of the conversion linearity as the leakage resistance of the integration circuit of the A / D converter 4, and is included in one embodiment of the first embodiment.

In this embodiment, a double integral type A / D converter is used as the A / D converter 4, but the application of the present invention for correcting the conversion linearity is not limited to this. In short, the conversion linearity as the A / D converter 4 is measured in advance from the relationship between the reference input signal (analog signal) and the A / D conversion output (digital data) at that time, and the conversion linearity is used for actual measurement. It is only necessary that the A / D conversion output can be corrected.
That is, according to the present invention, even in a radiation thermometer including an A / D converter having no means for changing the charging time of the integration circuit, the reference voltage generation unit 11 that generates voltages at a plurality of points as reference input signals can be prepared. If applicable. Therefore,
Infrared sensor 1, temperature sensor 2, and A / D converter 4 irrespective of A / D conversion method, such as A / D converter with sample and hold circuit, counter clamp A / D converter, successive approximation A / D converter, etc. The present invention can be applied to a radiation thermometer of a type including:

In this embodiment, the radiation thermometer for correcting the error of the conversion linearity of the A / D conversion output is shown. However, when the measured conversion linearity greatly deviates from the theoretical value, the correction is stopped. May be displayed. FIG. 5 shows a flowchart of a program for performing such display. FIG. 5 is obtained by adding the processing of S120 to S122 to the processing of FIG. 2 and omitting the processing of S104 and subsequent steps of FIG.

In this process, after measuring the conversion linearity in the same manner as in FIG. 2 (S102), it is determined whether or not the deviation of the actually measured conversion linearity from the theoretical value is within a predetermined range (S12).
0) If it is within the predetermined range, it shifts to the standby state as in FIG. 2 (S103), but if it is not within the predetermined range, it indicates that the conversion linearity is degraded (S121), and To
Turn off (S122).

In such a case, the leakage current of the integrating circuit temporarily increases due to the environment of high humidity or the environment in which dew condensation occurs due to a rapid temperature change, and the measurement reliability is lowered. Can be stopped, and the display of a measurement result having a large error can be prevented.

In this embodiment, an example is described in which the conversion linearity of the A / D conversion is measured every time the power switch is turned on. (Instruction by button) may be detected and measured, and an error curve based on the measurement result may be held until the next instruction. The timer may interrupt the control program executed by the CPU 5 to periodically measure the conversion linearity of the A / D conversion. Alternatively, the conversion linearity may be obtained for each measurement of the temperature (body temperature) of the measurement target.

(Embodiment 2) In Embodiment 1 described above, the radiation thermometer for correcting the error of the conversion linearity of the A / D conversion output has been described. In this embodiment, a thermistor is used as the temperature sensor 2. A radiation thermometer having a configuration for preventing leakage current caused by contact between the infrared sensor 1 and the temperature sensor 2 when used in contact with the infrared sensor 1 will be described.

FIG. 16 is a configuration diagram of a sensor part of a conventional radiation thermometer that does not consider the leakage current from an infrared sensor prepared for comparison with the radiation thermometer according to the second embodiment. The radiation thermometer shown in FIG. 16 uses a thermopile 1A as the infrared sensor 1 and a thermistor 2A as the temperature sensor 2. Further, one end of the thermistor 2A is connected to a constant voltage source, and the other end is grounded through a fixed resistor 12. Since other configurations and operations are the same as those of the first embodiment, the same components will be described with reference to FIG.

In this radiation thermometer, the potential of the fixed resistor on the thermistor side is applied to the A / D converter 4 through the signal selection circuit 10.
The temperature of the thermopile 1A itself can be measured by measuring a potential change due to a change in the resistance value of the thermistor 2A. Here, the resistance value of the fixed resistor 12 is usually several tens of kiloohms. On the other hand, when the terminals (a) and (b) of the thermistor 2A and the terminals (c) and (d) of the thermopile 1A are arranged adjacent to each other, the insulation leakage resistance between the terminals is several tens to several hundreds of kilohms. It may be.
In such a case, the leakage current through the insulating leakage resistance and the fixed resistance flows due to the electromotive force (on the order of microvolt) of the thermopile 1A, and a measurement error due to the influence of the leakage current cannot be ignored.

FIG. 6 is a block diagram showing the sensor part of the radiation thermometer according to the present embodiment in detail. As compared with FIG. 16, a switch 13 is provided between the thermistor and the constant voltage source, The switch 14 is also provided on the ground side terminal of the resistor. These switches 13 and switch 1
4 corresponds to a contact leakage current prevention means. Switch 13
An analog switch controllable by the CPU 5 is used for the switch 14.

When the CPU 5 takes in the sensor output signal from the thermopile 1A through the A / D converter 4, it gives a control signal to open the switches 13 and 14 in advance, and then reads the sensor output signal.

In this way, by opening both ends of the thermistor 2A, that is, the detection circuit of the thermistor 2A including the fixed resistor 12, the leakage current due to the electromotive force of the thermopile 1A can be suppressed. As a result, it is possible to accurately detect infrared rays with little influence of leakage current.

The switches 13 and 14 include:
Any type can be used as long as it can be controlled by the CPU 5, such as an electric switch such as an FET or a mechanical switch such as a reed switch or a relay.

(Embodiment 3) A radiation thermometer according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG.
FIG. 8 is a block diagram showing a configuration of a radiation thermometer according to the third embodiment, and FIG. 8 is a diagram showing a change in an amplified signal by the amplifier 3 shown in FIG.

The radiation thermometer according to the present embodiment eliminates the offset voltage of the amplifier 3. As shown in FIG. 7, the voltage across the infrared sensor 1 is
１８18 (corresponding to an input switch section) are connected to the inverting input terminal 3a and the non-inverting input terminal 3b of the amplifier 3 in a reversible manner. The connection of each switch 15-18 is
Can be switched by the switching signal. Other configurations and operations are the same as those of the first embodiment, and therefore, the same components will be denoted by the same reference characters and description thereof will be omitted.

In such a configuration, the output Vout1 of the amplifier 3 when the switches 15 and 17 are turned on, and the output Vout of the amplifier 3 when the switches 16 and 18 are turned on.
2 means that the output (electromotive force) of the infrared sensor 1 is output from the inverting input terminal 3a and the non-inverting input terminal 3b of the amplifier 3, respectively.
FIG. 8 shows the result of amplification in place of each other.
As shown in (1), the output is in the opposite direction to the reference voltage.

This relationship can be expressed by the following equation.

Vout1 = G · (E + Vos + Vr)... (Equation 6) Vout2 = G · (−E + Vos−Vr) .. (Equation 7) where E: infrared sensor 1 (electromotive force).

Vos: Offset voltage of the amplifier 3.

Vr: Reference voltage.

G: The gain of the amplifier 3. By taking the difference between (Equation 6) and (Equation 7), Vout1−Vout2 = 2G · (E + Vr) (Equation 8), and the offset voltage of the amplifier 3 is cancelled. Therefore, by latching either Vout1 or Vout2, taking the differential signal of both, and performing A / D conversion, the influence of the offset voltage of the amplifier 3 can be eliminated when measuring the temperature. As a result, when measuring the temperature, it is possible to suppress the influence of the change in the offset voltage due to the temperature characteristic of the amplifier 3 or the change with time, and to improve the accuracy of the temperature measurement.

A / D conversion is performed on each of Vout1 and Vout2,
The difference may be obtained from each converted digital data.

(Embodiment 4) <Configuration of radiation thermometer> A radiation thermometer according to Embodiment 4 of the present invention will be described with reference to FIGS. FIG. 9 is a block diagram showing a configuration of a radiation thermometer according to Embodiment 4 of the present invention. FIGS. 10 and 11 show signals of the integration circuit of the double integration type A / D converter 4A shown in FIG. It is a figure showing a change.

The radiation thermometer of the present embodiment is a double integration type
The purpose is to optimize the output level of digital data output from the A / D converter 4A. In FIG. 9, the output of the amplifier 3 is A / D converted by the double integration type A / D converter 4A,
It is configured to be passed to U5. The reference voltage generator 22 applies a discharge reference voltage V3 to the double integration type A / D converter 4A.

Further, the amplifier 3 and the double integration type A / D converter 4A are set at a potential shifted by the reference voltage V2 by the reference voltage generator 21. 1, the infrared sensor 1 is placed at a potential (corresponding to a bias) shifted by the reference voltage V1 by a reference voltage generator 11 (corresponding to a bias source).

The reference voltage generators 11, 21 and 22 are provided with control terminals for controlling the output voltage.
Can control the output voltage. This control terminal serves as a fixed resistance selection switch for determining the reference voltage of the constant voltage circuit inside the reference voltage generators 11, 21 and 22, and by switching the reference voltage, the reference voltage generators 11, 21 and 22 are switched. Output voltage is switched. Other configurations and operations are the same as those of the first embodiment, and therefore, the same components will be denoted by the same reference characters and description thereof will be omitted. <Operation> In the present embodiment, a thermopile is used as the infrared sensor 1. The output of the infrared sensor 1 in that case is represented by the following relational expression (Expression 9).

E = L ((Tx + 273.15) ⁴ − (Ta + 273.15) ⁴ ) (Equation 9) where E: output (V) of the infrared sensor.

Tx: temperature (° C.) of the object to be measured.

Ta: temperature (° C.) of the infrared sensor itself.

L: Sensitivity of the infrared sensor.

In a radiation thermometer, Tx is usually 32 ° C. to 42 ° C.
° C, while Ta, which depends on the ambient temperature, is 5
° C to 40 ° C and the difference between Tx and Ta is small.
Is on the order of microvolts.

The input voltage of the amplifier 3 is V = V1 + E (Equation 10) where V1 is a reference voltage of the infrared sensor. That is, the input to the amplifier 3 is a voltage that has changed in the positive or negative direction on the order of microvolts around the reference voltage V1 according to the relationship between Tx and Ta.

In the radiation thermometer of FIG. 9, V1 and V1 + E are respectively selected by the signal selection circuit 10, amplified by the amplifier 3, and then converted into digital data by the double integration type A / D converter 4A. After that, it is taken into the CPU 5. And V
The difference between the respective digital data obtained by A / D conversion from each of 1 and V1 + E becomes the digital data of the output of the infrared sensor 1.

Here, the following conditions are required to enable A / D conversion in the circuit of FIG. 9 (for example,
Noriyuki Ito "Digital Circuit" 1
See section 6.3, Double-integral AD converter.

V1 + Vos>V2> V3 ..... (Equation 11) and V1 + E + Vos>V2> V3 .... (Equation 12) where (Equation 11) and (Equation 12) All inequality signs may be reversed.

In the equations (11) and (12), V1 is a reference voltage of the infrared sensor 1.

V2: Reference voltage of the amplifier 3 and the double integration type A / D converter 4A.

V3: Reference voltage for discharge of the integration circuit of the double integration type A / D converter 4A.

E: Output (electromotive force) of the infrared sensor 1.

Vos: Offset voltage of the amplifier 3.

These relational expressions indicate that the input signal of the double integration type A / D converter 4A must always be either higher or lower than the reference voltage V2, and the discharge reference voltage V3 is Means that the magnitude of the input signal must be opposite to that of the reference voltage V2.

Since the amplifier 3 is composed of a general-purpose operational amplifier, the offset voltage Vos is about ± several tens of millivolts.
In order to satisfy (Equation 11) and (Equation 12), the difference between V1 and V2 must be set much larger than the offset voltage Vos in consideration of the variation. On the other hand, V1 and V2
When the difference is larger, since the reference voltage of the amplifier 3 is V2, the bias of the input signal is increased. Therefore, in order to prevent overflow from occurring in the A / D converter 4 after being amplified by the amplifier 3, the gain of the amplifier 3 must be set small.

Therefore, in the present embodiment, the reference voltage V1 is
The setting can be made from the CPU 5, and from the offset voltage Vos (or the output of the amplifier 3 when there is no input signal), V1 is set so that the above (Equation 11) and (Equation 12) are satisfied and V1-V2 is minimized. The value is determined, and the reference voltage generator 11 is controlled.

The control of the reference voltage generator 11 is as follows.
It can be performed by switching the reference voltage of the constant voltage circuit (for example, "Design of OP amplifier circuit" by Okamura Dio, published by CQ)
Refer to Chapter 8 Application to Constant Voltage and Constant Current Circuits).

As a result, the gain of the amplifier 3 can be increased to full scale without causing overflow in the A / D converter 4 due to the offset voltage Vos and the reference voltage V1-V2. Can be effectively amplified and A / D converted. As a result, measurement with substantially high sensitivity and high accuracy (high resolution) becomes possible.

FIGS. 10 and 11 show output signals of the integrating circuit in the double integrating A / D converter at this time.
It is. FIGS. 10 and 11 are both solid lines showing changes in the output of the integration circuit during charging by V1-V2 and changes in the output of the integration circuit during discharging by V3-V2. The dotted line in each of FIG. 10 and FIG.
5 shows changes in the output of the integration circuit during charging by V1 + E-V2 with the output E superimposed thereon and the output of the integration circuit during discharging by V3-V2. Each of the two dotted lines in each of FIGS. 10 and 11 takes into account the case where the output E of the infrared sensor 1 is positive and negative.

FIG. 10 shows a case where the reference voltage V1 is not adjusted, and FIG. 11 shows a case where the reference voltage V1 is adjusted. A / D conversion range 33
And 33A indicate a conversion possible range (dynamic range) determined by the number of bits of the A / D converter 4. FIG.
Compared to the case of FIG. 11, in the case of FIG. 11, there is a margin of the A / D convertible region only in the region indicated by the hatched portion 34. As a result, the possibility of occurrence of overflow in the double integration type A / D converter 4A is reduced, and the gain of the amplifier 3 corresponding to the range of the hatched portion 34 can be increased.

The gain of the amplifier 3 can be changed by changing the resistance value of a feedback resistor in a general inverting amplifier or non-inverting amplifier, but it is widely known (for example, “OP OP” Amplifier circuit design ”). To control this from the CPU 5, a plurality of resistors are provided in advance as feedback resistors, and these are connected to an analog switch (FET).
Switch, analog multiplexer IC, etc.).

In this way, the gain of the amplifier 3 can be increased and the A / D converter 4 can be used in a region near full scale, so that the radiation thermometer can be effectively made highly sensitive.

<Modification> In the present embodiment, the gain of the amplifier 3 is realized by switching a plurality of feedback resistors (fixed resistors) with an analog switch. Instead, a semiconductor element such as an FET is used as a feedback resistor. Alternatively, an equivalent variable resistance element using a resistance change due to a change in the bias and the gate voltage may be used.

In this embodiment, the gain of the amplifier 3 is adjusted by adjusting the reference voltage V1 of the infrared sensor 1 shown in FIG. Instead, the charging time of the integration circuit of the double integration type A / D converter 4A may be increased.
This is because, as described in the first embodiment, increasing the charging time of the integration circuit substantially increases the gain of the A / D converter.

The double integration type A / D converter 4A includes an integration circuit, a comparator, and a counter, integrates an input signal to be converted by an integration circuit for a fixed period (charge time), and converts the integrated signal into a known discharge reference. Discharge is performed by a voltage, and the time required for the discharge is measured by the number of clocks of a counter to obtain digital data.

In order to change the charging time of the integrating circuit, it is necessary to change the number of counter bits. Therefore, the counter may be provided in advance with the maximum number of bits including the spare bits, and the number of bits of the counter may be limited to the maximum number of bits according to the required charging time. As the number of bits of the counter used increases, the response of the A / D conversion decreases, and this ultimately becomes a trade-off between the required gain and the required response.

To change the number of counter bits, any one of the bits of the counter is set as a carry bit and can be selected by a charge time selection signal from the CPU 5 through a multiplexer. By changing the bit position selected from the CPU 5, the position of the carry bit can be changed.
The number of bits of the counter, that is, the charging time can be changed.
FIG. 15 shows the configuration of the double integration type A / D converter 4A configured as described above.

Instead of the multiplexer, each bit of the counter is taken out through a three-state buffer, and a signal at a bit position larger than the required number of bits is output from the three-state buffer by a charging time selection signal from the CPU 5. May be set to a high impedance state so as not to contribute to the measurement of the charging time.

In this embodiment, an example in which the reference voltage V1 of the infrared sensor 1 is adjusted based only on the offset voltage of the amplifier 3 shown in FIG. Can be adjusted to include the output of

That is, as shown in (Equation 9), the output E of the infrared sensor 1 is determined by the temperature Tx of the object to be measured and the temperature Ta of the infrared sensor 1 itself. Body temperature) Tx is 32 ° C ~ 42 ° C
Therefore, if the temperature Ta of the infrared sensor 1 itself is determined, the full-scale output of the output E of the infrared sensor 1 can be predicted from (Equation 9). Therefore, from the relationship between the predicted value of the output E based on the temperature Ta of the infrared sensor 1 itself and the offset voltage Vos, (Expression 11) and (Expression 12) are satisfied, and the reference voltage V1 is set so that V1-V2 is minimized. Should be determined. Furthermore, the output E of the infrared sensor 1 predicted from the offset voltage Vos of the amplifier 3 and (Equation 9) satisfies (Equation 12), and the input of the amplifier 3 based on V2, that is, V1 + E + If Vos-V2 is adjusted to be as large as possible within the range where overflow does not occur in the A / D converter 4 after amplification, the radiation thermometer can be substantially made high sensitivity and high resolution.
In this case, the gain may be adjusted by either the above-described method of adjusting the gain of the amplifier 3 or the method of increasing the charging time of the integration circuit of the double integration A / D converter 4A.

In this embodiment, a double integration type A / D converter 4A is used as the A / D converter 4. However, this is not necessarily an A / D converter having an integration circuit as an electric circuit. The operation of the double integration type A / D converter 4A may be realized by a program executed by the CPU 5 as it is. In such a case, the charging time can be changed only by changing the number of additions (addition section) of the input signal in the program. Therefore, when the gain of the amplifier 3 is changed, or when the double integration A / This can be easily realized as compared with a method of increasing the charging time of the D converter 4A.

The reference voltage generator 11 as described above
The measurement of the offset voltage of the amplifier 3 and the sensor temperature signal for determining the reference voltage, the gain of the amplifier 3, the charging time of the integration circuit, and the like are usually performed when the radiation thermometer is used.
However, the control program is further started by a timer built in the CPU 5, and the offset voltage of the amplifier 3 and the sensor temperature signal of the temperature sensor 2 are periodically measured. When the thermometer is used, the reference voltage 11, the gain of the amplifier 3, the charging time of the integrating circuit, and the like may be determined by also reflecting the accumulated past measurement results.

(Embodiment 5) FIG. 12 shows Embodiment 5 of the present invention.
3 is a flowchart showing the operation of the radiation thermometer according to the first embodiment.
The radiation thermometer of the present embodiment periodically uses the infrared sensor 1.
The temperature of the infrared sensor 1 is measured to guarantee the temperature detection in a state where the temperature of the infrared sensor 1 itself is stabilized, and the mode shifts to the low power consumption mode unless the temperature is measured periodically. FIG. 12 is a flowchart showing the processing of a program executed by the CPU 5 for controlling the radiation thermometer.

The configuration of the radiation thermometer of this embodiment is the same as that of the first embodiment, except that the CPU 5 has a built-in timer, and that components other than the CPU 5 (temperature sensor) in the low power consumption mode. 2, Amplifier 3, A / D converter 4
) Is provided with a power switch (not shown) that can be opened and closed by the CPU 5 for disconnecting the power supply from a power source (not shown), and an instruction button (not shown) for instructing transition to the low power consumption mode.

Here, the low power consumption mode refers to a state in which components other than the CPU 5 including the timer are separated from the power supply, and power consumption is suppressed. These differences and CPU
The configuration and operation other than the control program executed by the fifth embodiment are the same as those of the first embodiment, and will be described with reference to FIG. 1 as necessary.

The processing of the program executed by the CPU 5 will be described below with reference to FIG. Normal measurement is completed (S12
0), upon detecting the pressing of the shift button to the low power consumption mode, the CPU 5 opens the power switch, disconnects the components other than the CPU 5 from the power supply, and shifts to the low power consumption mode (S121).

Next, a timer built in the CPU 5 is set (S122), and after a lapse of a predetermined time (S123), the operation mode returns to the normal operation mode, and all the circuit components are connected to a power supply (not shown) (S124). . Then, the digital data obtained by A / D conversion is fetched from the output of the temperature sensor (S125), the next predetermined time (waiting time in the low power consumption mode) is set (S126), and the mode shifts to the low power consumption mode again. (S121).

As described above, since the CPU 5 periodically monitors the temperature of the temperature sensor 2, even if the temperature of the infrared sensor 1 itself is stable even when it is used for measurement after a certain period of time, it is determined whether the temperature of the infrared sensor 1 itself is stable. Can be determined.

FIG. 13 is a flowchart showing an example of a process in which the CPU 5 periodically monitors the temperature of the infrared sensor 1 and displays a change in the temperature when the temperature change is large as described above. FIG. 13 is prepared in order to explain the processing subsequent to FIG. 12 in detail.
Steps S120 to S126 are simply shown as steps S140 to S141. Further, in FIG. 13, after the low power consumption button is released and the mode shifts to the measurable normal mode (S 142), the measured temperature of the infrared sensor 1, that is, the result obtained by taking in the output of the temperature sensor 2 and the predetermined time before If the obtained result is not within the predetermined value (S1
45) shows a process of displaying on the LCD 6 that the environmental temperature is unstable.

As described above, the temperature sensor 2 is
A / D-converting and monitoring the output of the above makes it possible to determine whether or not the body temperature is measured in a state where the sensor temperature is sufficiently stable. In addition, before the measurement, the fact that the state of the radiation thermometer is unstable is displayed on the LCD 6 so that
Useless measurement work can be prevented. However, at the end of the measurement, it may be determined whether or not the measurement has been performed stably, and this may be notified to the user. In any case, display of unreliable measurement results can be prevented in this way.

On the other hand, except when the output of the temperature sensor 2 is read, by shifting to the low power consumption mode,
It is possible to monitor the temperature of the infrared sensor 1 while reducing the power consumption of the D converter 4 and avoiding the problem that the number of times of use in the built-in power type radiation thermometer is reduced.

When the output of the temperature sensor 2 is A / D-converted and monitored at predetermined time intervals, and when it is detected that the radiation thermometer has shifted from an unstable state to a stable state, this fact is notified. May be displayed.

As a means for notifying that the radiation thermometer is unstable, a display such as the LCD 6 is used to display the fact as described above, as well as a display using a light emitting diode, a buzzer, or the like. Various means that can be recognized by the user of the radiation thermometer, such as a warning by the sound of the sound and generation of mechanical vibration by the vibrator, can be used.

[0135]

According to the present invention, in a radiation thermometer,
Since the conversion error due to the deviation from the element characteristics of the A / D converter, particularly the deviation from the conversion linearity, is corrected, the measurement accuracy can be improved.

Further, in the radiation thermometer, when taking in the output of the infrared sensor, the leakage current from the infrared sensor can be suppressed, so that the measurement accuracy can be improved.

Further, according to the present invention, the offset voltage of the amplifier can be easily and stably eliminated in the radiation thermometer, so that the measurement accuracy can be improved.

Further, according to the present invention, in the radiation thermometer, the overflow of the A / D converter due to the offset voltage of the amplifier can be prevented, and the signal component as the output of the infrared sensor can be increased. A radiation thermometer can be provided.

Further, according to the present invention, in the radiation thermometer, the temperature of the infrared sensor itself is periodically monitored, so that the measurement can be performed in an environment where the difference between the temperature of the infrared sensor itself and the temperature of the object to be measured is unstable. Can be prevented. Further, in this case, it is possible to provide a low-power-consumption radiant thermometer that suppresses power consumption except when monitoring the temperature of the infrared sensor itself.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a radiation thermometer according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart showing the operation of the radiation thermometer according to the first embodiment.

FIG. 3 is a graph showing A / D conversion output with respect to charging time of an integration circuit.

FIG. 4 is a graph showing an error from conversion linearity with respect to an A / D conversion output.

FIG. 5 is a flowchart showing the operation of a radiation thermometer according to a modification of the first embodiment;

FIG. 6 is a block diagram showing a configuration of a radiation thermometer according to the second embodiment.

FIG. 7 is a block diagram showing a configuration of a radiation thermometer according to Embodiment 3.

FIG. 8 is a diagram showing an amplifier output signal according to the third embodiment;

FIG. 9 is a block diagram showing a configuration of a radiation thermometer according to a fourth embodiment.

FIG. 10 is a diagram showing an integrated signal of the A / D converter according to the fourth embodiment.

FIG. 11 is a diagram showing an integrated signal of an A / D converter according to a fourth embodiment.

FIG. 12 is a flowchart showing the operation of the radiation thermometer according to the fifth embodiment.

FIG. 13 is a flowchart showing the operation of the radiation thermometer according to the fifth embodiment.

FIG. 14 is a diagram showing a double integration type A / D converter according to the first embodiment;

FIG. 15 shows a double integration type A / D according to a modification of the fourth embodiment.
Diagram showing converter

FIG. 16 is a block diagram showing a configuration of a conventional radiation thermometer for the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infrared sensor 1A Thermopile 2 Temperature sensor 2A Thermistor 3 Amplifier 4 A / D converter 4A Double integration type A / D converter 5 CPU 10 Signal selection circuit 11 Reference voltage 21 Circuit reference voltage 22 Discharge reference voltage

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Ota 24F Yamanouchi Yamanoshitamachi, Ukyo-ku, Kyoto-shi, Japan OMRON Life Science Laboratory Co., Ltd. F-term (reference) 2G066 AC13 BA08 BB11 BC02 BC07 BC13 CA15 CA20

Claims (12)

[Claims] 1. An infrared sensor for outputting a sensor output signal corresponding to the amount of infrared radiation radiated from an object to be measured, a temperature sensor for outputting a sensor temperature signal corresponding to the temperature of the infrared sensor itself, and the sensor output signal An A / D converter that converts the sensor temperature signal into digital data, and a control unit that calculates a temperature of a measurement target based on digital data obtained by the A / D converter, wherein the control unit includes a reference and The reference input signal as an input signal is digital data converted by the A / D converter, from the relationship between the information related to the reference input signal,
Measure the conversion linearity of the A / D converter, and correct and measure at least one of digital data converted from the sensor output signal and digital data converted from the sensor temperature signal based on the conversion linearity. A radiation thermometer that calculates the target temperature. 2. The apparatus according to claim 1, further comprising a notifying unit for notifying that the measurement cannot be performed when the deviation of the conversion linearity measured by the control unit from the ideal conversion linearity is equal to or larger than a predetermined value. Radiation thermometer. 3. The A / D converter includes an integrator capable of setting a charging time by the control unit. The control unit sets a plurality of different charging times and sets a reference input by the A / D converter. The radiation thermometer according to claim 1, wherein a plurality of types of digital data converted from the signal are obtained, and conversion linearity is detected from a relationship between the plurality of types of digital data and the charging time. 4. An infrared sensor for outputting a sensor output signal in accordance with the amount of infrared radiation radiated from an object to be measured, a temperature sensor for outputting a sensor temperature signal in accordance with the temperature of the infrared sensor itself, and an integrator. A / A for converting the sensor output signal and the sensor temperature signal into digital data
A D converter, and a control unit for calculating the temperature of the measurement target based on digital data obtained by the A / D converter, wherein the control unit has a reference input as an input signal to be a reference by the A / D converter. Calculating the leak resistance of the integrator from the relationship between the digital data converted from the signal and the information related to the reference input signal, and based on the leak resistance, the digital data converted from the sensor output signal and the sensor A radiation thermometer that corrects at least one of digital data converted from a temperature signal and calculates a temperature of a measurement target. 5. An infrared sensor for outputting a sensor output signal in accordance with an amount of infrared radiation emitted from an object to be measured, and a sensor temperature signal provided in contact with the infrared sensor and corresponding to the temperature of the infrared sensor itself. A temperature sensor that outputs, a control unit that receives the sensor output signal and the sensor temperature signal, and calculates a temperature of a measurement target based on the sensor output signal; and a case where the sensor output signal is provided from the infrared sensor to the control unit. A radiation thermometer comprising contact leakage current prevention means for preventing a leakage current generated due to contact between the temperature sensor and the infrared sensor from affecting the sensor output signal. 6. An infrared sensor for outputting a sensor output signal according to an amount of infrared radiation emitted from a measurement object, a temperature sensor for outputting a sensor temperature signal according to a temperature of the infrared sensor itself, and the sensor output signal. An amplifier including an inverting input terminal and a non-inverting input terminal for amplifying the input signal, an input switch unit for connecting the sensor output signal to either the inverting input terminal or the non-inverting input terminal, and the amplifier A control unit that calculates the temperature of the measurement target based on the amplified sensor output signal and the sensor temperature signal, wherein the control unit is configured to amplify the sensor output signal from the inverting input terminal and the non-inverting input terminal. A radiation thermometer for calculating a temperature of a measurement target based on a difference signal from the sensor output signal amplified from the temperature. 7. An infrared sensor for outputting a sensor output signal in accordance with an amount of infrared radiation radiated from an object to be measured, a bias source for superimposing a bias on the sensor output signal, and a temperature of the infrared sensor itself. A temperature sensor that outputs a corresponding sensor temperature signal, an amplifier that amplifies the sensor output signal, an A / D converter that converts the amplified sensor output signal and the sensor temperature signal into digital data, and an A / D converter. A controller for calculating the temperature of the measurement target based on the digital data obtained by the converter, the bias of the bias source, the amplified sensor output signal is a predetermined input signal allowable range of the A / D converter Radiation thermometer controlled to fit in. 8. The radiation thermometer according to claim 7, wherein the bias of the bias generation source is controlled based on a preset predicted temperature of the measurement object and digital data converted from the sensor temperature signal. 9. An infrared sensor for outputting a sensor output signal according to an amount of infrared radiation radiated from an object to be measured, a temperature sensor for outputting a sensor temperature signal corresponding to a temperature of the infrared sensor itself, and the sensor output signal. And a control unit that calculates the temperature of the measurement target based on the sensor output signal and the sensor temperature signal amplified by the amplifier, wherein the gain of the amplifier is a preset prediction of the measurement target. A radiation thermometer that is controlled based on a temperature and the sensor temperature signal. 10. An infrared sensor for outputting a sensor output signal corresponding to the amount of infrared radiation emitted from a measurement object, a temperature sensor for outputting a sensor temperature signal corresponding to the temperature of the infrared sensor itself, and an integrator. An A / D converter that converts the sensor output signal and the sensor temperature signal into digital data, and a control unit that calculates a temperature of a measurement target based on digital data obtained by the A / D converter, A radiation thermometer in which the charging time of the device is controlled based on a preset predicted temperature of a measurement target and digital data converted from the sensor temperature signal. 11. An infrared sensor for outputting a sensor output signal in accordance with the amount of infrared radiation emitted from a measurement object, a temperature sensor for outputting a sensor temperature signal in accordance with the temperature of the infrared sensor itself, and the sensor output signal. And an A / D converter for converting the sensor temperature signal into digital data,
A control unit for calculating the temperature of the measurement target based on the digital data obtained by the A / D converter, wherein the control unit converts the sensor temperature signal into digital data converted by the A / D converter. Radiation thermometer that reads every hour. 12. When the input of the digital data obtained by converting the sensor temperature signal from the A / D converter to the control unit ends, power supply to the temperature sensor or the A / D converter is stopped. 12. The radiation thermometer according to claim 11, wherein when the input of the digital data converted from the temperature signal is started, the power supply to the temperature sensor or the A / D converter in the power supply stopped state is restarted.