JPH06142063A - Radiation clinical thermometer - Google Patents

Abstract

PURPOSE:To enable arithmetic processing in a short time by allowing a temperature compensation in an optical system of a radiation clinical thermometer to simplify an equation for calculating a body temperature. CONSTITUTION:A first temperature sensor 32a is mounted for measuring temperature of an infrared sensor 31 and a second temperature sensor 32b is mounted for measuring the temperature of a light guide tube. An output voltage of the infrared sensor 31 is computed and amplified with an analog circuit using an optical system temperature compensation circuit 44 basing on a temperature difference signal Td from the two temperature sensors 32a and 32b. This allows simplifying of the circuitry of the analog circuit and further enables the calculation of a body temperature by a simple equation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation thermometer which detects thermal radiation energy and measures the temperature in a non-contact manner, and more particularly to temperature compensation of an optical system.

[0002]

2. Description of the Related Art In order to measure a body temperature in a short time, a radiation thermometer has been proposed which selects an eardrum as a measurement site and measures the temperature of the site without contact. For example, the radiation thermometer disclosed in Japanese Patent Laid-Open No. 61-117422. This radiation thermometer measures the eardrum temperature by inserting the head portion of the probe unit into the ear canal and collecting the heat radiation from the eardrum on an infrared sensor by a light guide tube arranged in the head portion. . The probe unit equipped with this infrared sensor is provided with heating control means for preheating to a reference temperature (36.5 ° C.). The head portion is preheated to a temperature close to the body temperature in advance, and calibrated in that state. Therefore, even if the head portion is inserted into the ear canal, the temperature of the head portion does not change, and the error factor caused by that is eliminated.

In other words, the inner surface of the light guide tube has been devised so as to increase the reflectance, but it cannot be a perfect reflector. Therefore, in order to prevent the heat radiation from the light guide tube itself from causing a measurement error, it is necessary to set the temperature of the inner surface of the light guide tube to the same temperature as the temperature of the infrared sensor itself.
Even if the head portion is inserted into the ear canal, the temperature of the head portion is stabilized at the reference temperature (36.5 ° C.) in order to prevent the temperature from changing. This makes it possible to ignore the heat radiation from the inner surface of the light guide tube.

However, the radiation thermometer disclosed in Japanese Unexamined Patent Publication No. 61-117422 requires a heating control device with high control accuracy, which complicates the structure and circuit configuration of the device, resulting in a large device and increased cost. There is a problem that becomes. In addition, a long stabilization time was required to preheat the head part and control it to a constant temperature. Furthermore, a large amount of energy is required to drive the heating control device, and a portable thermometer that uses a small battery as an energy source
It is impossible to adopt this method.

Therefore, in a small portable thermometer without a heating control device, and when the probe is inserted into the ear canal to measure the eardrum temperature, the temperature of the probe changes, but an error due to it changes. Radiation thermometers with high temperature measurement accuracy have been proposed. For example, Japanese Patent Laid-Open No. 2-
It is the radiation thermometer of 28524 gazette. JP-A-2-28
The radiation thermometer of Japanese Patent No. 524 is also the same as the radiation thermometer of Japanese Patent Laid-Open No. 61-117422 in that a light guide tube is used as an optical system to collect the heat radiation from the eardrum.

However, it does not have a heating control device for the infrared sensor, and the temperature of the infrared sensor and the light guide tube is stabilized at the ambient temperature, that is, room temperature. In addition to providing the first temperature sensor near the infrared sensor, a second temperature sensor is also provided in the light guide tube to measure the temperature based on the temperatures of the infrared sensor and the light guide tube. is doing. Then, if the temperature difference between the infrared sensor and the light guide tube is abnormally large, the measurement is disallowed, but if the temperature difference is smaller than the preset value, the measurement will be performed even if there is a temperature difference between them. It is a radiation thermometer that calculates the body temperature data by allowing the calculation and considering the temperature of the infrared sensor and the light guide tube. That is, the calculation for calculating the body temperature data includes the output voltage of the infrared sensor, the temperature of the first temperature sensitive sensor for measuring the infrared sensor, and the second temperature sensitive for measuring the surface temperature of the light guide tube. It is performed by a microcomputer based on the temperature of the sensor.

For example, when the probe is inserted into the ear canal, the temperature of the infrared sensor hardly changes, but the temperature of the light guide tube gradually rises. Then, although there is a temperature difference between the infrared sensor and the light guide tube, the body temperature data is calculated by performing a calculation in consideration of those temperatures. Therefore, even if there is a temperature difference between the two, the radiation thermometer eliminates the error caused by the temperature difference.

[0008]

However, the radiation thermometer disclosed in Japanese Patent Laid-Open No. 28285/1990 has the following problems. That is, based on the temperature data of the two temperature sensors and the output of the infrared sensor, the body temperature data is calculated using a complicated equation based on a total of three variables. Became complicated and required a lot of time for calculation processing. It was also difficult to measure and set the constants such as the emissivity of the light guide tube in this equation in advance.

An object of the present invention is to solve the above problems and to calculate body temperature data by a simple equation so that the arithmetic processing can be performed in a short time.

[0010]

In order to achieve the above object, the present invention has the following constitution. That is,
An optical system having a light guide tube for collecting heat radiation from a measurement object, an infrared sensor for converting heat radiation energy collected through the light guide tube into an electric signal, and a temperature of the infrared sensor A detection element having a first temperature-sensitive sensor for measuring temperature, a second temperature-sensitive sensor for measuring surface temperature of the light guide tube, and electric signals from the first and second temperature-sensitive sensors and the In a radiation thermometer equipped with an arithmetic circuit for calculating body temperature data according to an electric signal from an infrared sensor and a display device for displaying body temperature according to the body temperature data, a temperature difference is obtained by the first and second temperature sensitive sensors. And an optical system temperature compensation circuit that arithmetically amplifies an electric signal from the infrared sensor based on a temperature difference signal from the temperature difference circuit by an analog circuit.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a front view of the radiation thermometer according to the present embodiment. This radiation thermometer is a thermometer that measures eardrum temperature,
It is composed of a main body 10, a probe 11, and a head 12. The main body 10 is provided with a liquid crystal display element 61 for displaying body temperature and a measurement switch 53 having a push button structure.

The operating method of the radiation thermometer is as follows. First, the radiation thermometer is taken out from the storage case (not shown) in which it is stored. Then, the power is automatically turned on by a reed switch (not shown) built in the radiation thermometer and a permanent magnet (not shown) attached to the storage case. Next, the measurement switch 53 is pressed to start temperature measurement. After that, the probe 11 is inserted into the ear canal of the subject and directed toward the eardrum to measure the eardrum temperature. After the probe 11 is correctly directed to the eardrum, the radiothermometer is taken out from the ear canal. Here, since the display temperature of the liquid crystal display element 61 indicates the highest temperature measured, the body temperature of the eardrum is displayed.
Then, the body temperature display of the liquid crystal display element 61 is read as the eardrum temperature of the subject. However, when the radiation thermometer is in a state in which measurement is not possible, when the measurement switch 53 is pressed, the measurement prohibition mark 61m lights up.

FIG. 3 is a basic configuration diagram of the radiation thermometer of this embodiment, and the configuration will be described below with reference to the drawings. The radiation thermometer is composed of an optical system 2, a detection element 3, an amplification circuit 4, an arithmetic control circuit 5, and a display device 6.

The optical system 2 comprises a light guide tube 21 for efficiently collecting the heat radiation from the eardrum T which is a measurement object, and a filter 22 having a transmission wavelength characteristic. Light guide tube 21
Is made of metal pipe such as brass or stainless steel, or glass pipe. Its inner surface is mirror-polished and gold (Au) plated to increase the reflectance.
However, since the light guide tube 21 cannot be a perfect reflector having a reflectance of 1.00, it has some emissivity. The filter 22 is made of an optical crystal such as silicon (Si) or barium fluoride (BaF2), or a polymer such as polyethylene. It also has a selective passage of infrared wavelengths and a dustproof function.

The detecting element 3 comprises an infrared sensor 31 and two temperature sensitive sensors 32a and 32b. A thermopile is used for the infrared sensor 31, and converts thermal radiation energy into an electric signal. That is, in the infrared sensor 31, the thermal radiation energy obtained by subtracting the thermal radiation from the infrared sensor 31 itself from the thermal radiation collected by the optical system 2 and incident on the infrared sensor 31 is converted into an electric signal, that is, an electromotive force. To be converted. Also, two temperature sensitive sensors 32a and 32b
Is a thermistor. The first temperature sensor 32a is arranged near the infrared sensor 31 in order to measure the temperature To of the infrared sensor 31.
The second temperature sensor 32b is provided to detect the surface temperature Tp of the light guide tube 21 and is in close contact with the light guide tube 21. Then, the temperature difference signal Td indicating the temperature difference between the temperatures To and Tp is generated by the two temperature sensitive sensors 32a.
And the temperature difference circuit 32 including 32b.

The amplifier circuit 4 comprises an optical system temperature compensating circuit 44, a temperature measuring circuit 45, and an A / D converting circuit 46. As shown in FIG. 1, the optical system temperature compensation circuit 44 includes a first-stage amplification circuit 41 that amplifies an electric signal of the infrared sensor 31.
And a compensation circuit 43 for compensating the temperature of the optical system 2. Further, the optical system temperature compensating circuit 44 can detect and output a temperature difference between the temperature To of the infrared sensor 31 and the temperature Tp of the light guide tube 21 based on the temperature inspection signal Sc. The detailed circuit configuration of the optical system temperature compensation circuit 44 will be described with reference to FIG. In addition, the temperature measuring circuit 45 is configured to measure the resistance value of the first temperature sensitive sensor 32a, and a circuit for driving the first temperature sensitive sensor 32a with a constant current and the voltage across the temperature sensitive sensor 32a. It consists of a circuit that amplifies. Further, the first temperature sensor 32a
Is connected to the temperature measuring circuit 45 when measuring the temperature To of the infrared sensor 31, and is switched to each circuit by a semiconductor switch so as to configure the temperature difference circuit 32 when detecting the temperature difference signal Td. It has become. The A / D conversion circuit 46 includes the optical system temperature compensation circuit 4
4 and the output signal of the temperature measuring circuit 45 are used as input signals, and two systems of data are configured to be selected and digitized according to the A / D selection signal Sa.

The arithmetic control circuit 5 comprises an arithmetic circuit 51 and a switch control circuit 52, and a microcomputer is used. The switch control circuit 52 has a circuit configuration including a push button type measurement switch 53. Then, in synchronization with the pressing of the measurement switch 53,
Control signals of the temperature inspection signal Sc, the A / D selection signal Sa, and the calculation start signal Sb are generated. Further, the arithmetic circuit 51 calculates the body temperature data Tb based on the two systems of data transferred from the A / D conversion circuit 46 in synchronization with the arithmetic start signal Sb. Further, when the optical system temperature compensation range is exceeded, a prohibition signal is generated.

The display device 6 comprises a liquid crystal display element 61 and a display drive circuit 62. The liquid crystal display element 61 has a body temperature display for digitally displaying the body temperature data Tb and a measurement prohibition mark 61m notifying that the temperature exceeds the optical system temperature compensation range. The body temperature data Tb and the prohibition signal output from the arithmetic circuit 51 are displayed on the display drive circuit 6.
It is converted by 2 and displayed on the liquid crystal display element 61.

The operation of measuring the temperature of the eardrum T in the radiation thermometer constructed as described above will be described. First, the eardrum T, which is the measurement object, radiates heat. It follows Stefan Boltzmann's law that "thermal radiation energy is proportional to the fourth power of the absolute temperature of an object." Also, the ear canal is surrounded by the same temperature,
This can be regarded as a black body cavity. Therefore, the eardrum's emissivity may be treated as 1.00.

The transmission wavelength characteristic of the filter 22 matches the wavelength spectral distribution of the thermal radiation emitted from the eardrum T. The heat radiation emitted from the eardrum T is transmitted to the light guide tube 2
The inner surface of 1 is repeatedly reflected multiple times and reaches the infrared sensor 31. The transmittance and reflectance of this optical system 2 are 1.00.
Is ideal, but in reality it cannot be 1.00, so the thermal radiation emitted from the eardrum T reaches the infrared sensor 31 after being attenuated. Moreover, since the emissivity of the light guide tube 21 is not 0.00, heat radiation is also emitted from the light guide tube 21. This also reaches the infrared sensor 31.

Further, the infrared sensor 31 also emits thermal radiation. Since the detection unit of the infrared sensor 31 is processed to increase the absorptance, the emissivity is 1.00.
Has become. In order to indirectly measure the thermal radiation energy emitted from the infrared sensor 31, the temperature To of the infrared sensor 31 is measured by the temperature sensor 32a. Then, the infrared sensor 31 converts the thermal radiation energy obtained by subtracting the emission from the incident into an electric signal. Infrared sensor 3
Since the thermopile is used for 1, the electromotive force proportional to the thermal radiation energy is generated.

By the way, in a standard state, the temperature Tp of the light guide tube 21 and the temperature To of the infrared sensor 31 are equal. In this state, temperature compensation of the optical system is not necessary. This is because the thermal radiation emitted from the light guide tube 21 and incident on the infrared sensor 31 is subtracted by a part of the thermal radiation emitted from the infrared sensor 31, and thus does not become a noise component. Since the sensitivity is adjusted in this state, no error occurs in the measurement.

However, when the temperature Tp of the light guide tube 21 is higher than the temperature To of the infrared sensor 31, too much heat radiation is emitted from the light guide tube 21. As a result, the amount of thermal radiation that enters the infrared sensor 31 increases, and the infrared sensor 3
The output voltage of 1 also becomes high. In this state, if the same amplification as in the standard state is performed, the output signal Vr of the optical system temperature compensation circuit 44 becomes high, and the body temperature data Tb obtained by the calculation of the calculation circuit 51 is the actual eardrum T. Will be higher than the temperature. Therefore, the amplification degree of the optical system temperature compensation circuit 44 is configured to be lowered according to the temperature difference between the temperature Tp and the temperature To. Then, it operates so as to have the same voltage as the output signal Vr in the standard state.

On the contrary, when the temperature Tp of the light guide tube 21 is lower than the temperature To of the infrared sensor 31, the amplification degree of the optical system temperature compensation circuit 44 is increased. That is, the amplification degree of the optical system temperature compensation circuit 44 is determined according to the temperature Tp of the light guide tube 21 and the temperature To of the infrared sensor 31. The relationship between the temperature of the first temperature sensitive sensor and the voltage of the output signal Vr is always the same as that in the standard state. Therefore, the body temperature data Tb calculated by the calculation circuit 51 is always the eardrum T
Operates to match the temperature of.

The temperature difference between the temperature Tp of the light guide tube 21 and the temperature To of the infrared sensor 31 is determined by the first and second temperature sensitive sensors 3
From the temperature difference circuit 32 based on 2a and 32b, the temperature difference signal T
It is output as d. Then, the amplification degree of the optical system temperature compensation circuit 44 is adjusted by the temperature difference signal Td.

FIG. 4 is a sectional view of the probe 11 and the head 12 of the radiation thermometer according to this embodiment. Probe 11
The case of the head 12 and the case of the head 12 are made of a resin molded body having extremely low heat conductivity. The case forming the probe has a cylindrical shape.

A lightweight and highly heat-conductive housing 23 such as aluminum is fitted in the cylindrical case. The housing 23 is provided with a cylindrical portion and a base portion, the base portion is provided with a hollow portion communicating with the cylindrical portion, and the cylindrical portion is further provided with a through hole and a recess for embedding the temperature sensor. The light guide tube 21 is fitted in the through hole. Further, a filter 22 is fixed to the step portion at the tip of the light guide tube 21.

Further, an infrared sensor 31 and a first temperature sensitive sensor 32a are embedded in a hollow portion of the base portion with a sealing resin. The second temperature sensor 32b is provided in the recess.
Are buried by the sealing resin. The infrared sensor 31 and the two temperature-sensitive sensors 32a and 32b are each connected to a wiring pattern of a circuit board (not shown) by a lead wire and led to an amplification circuit described later.

FIG. 1 is a more detailed circuit configuration diagram of the infrared sensor 31, the temperature difference detection circuit 32, and the optical system temperature compensation circuit 44 for explaining the temperature correction of the light guide tube. The first temperature sensor 32a constitutes the temperature difference circuit 32 for detecting the temperature difference signal Td, and is cut off from the temperature measuring circuit 45 by a semiconductor switch.

The temperature difference circuit 32 includes a first temperature sensor 32.
a and the second temperature sensor 32b are connected in series, and both ends thereof are connected to the (+) power source and the (-) power source, respectively.
And this power supply, like + 2.5V and -2.5V,
It is the same voltage as the reference potential. Then, the temperature difference signal Td divided by the first temperature sensor 32a and the second temperature sensor 32b is output. The two temperature sensors 32a and 32b are made of thermistors having similar electrical characteristics.

The optical system temperature compensating circuit 44 comprises a first stage amplifying circuit 41, a switching circuit 42 and a compensating circuit 43. The first-stage amplifier circuit 41 is a normal non-inverting amplifier composed of an operational amplifier 41a, an input resistor 41b and a feedback resistor 41c. The infrared sensor 31 is connected to the non-inverting input.
It is connected. The compensation circuit 43 includes an operational amplifier 43a, two input resistors 43b and 43c, and a feedback resistor 4.
It is a normal inverting adder circuit composed of 3d. The input of the input resistor 43b is connected to the output of the switching circuit 42, and the input resistor 43c is connected to the temperature difference signal Td of the temperature difference circuit 32. Then, the output signal Vr
Are connected to the A / D conversion circuit 46.

Further, the switching circuit 42 has one input connected to the output of the first-stage amplifier circuit 41 and the other input connected to the reference potential. Then, the switch structure is made of a semiconductor that selects and outputs one of them according to the temperature inspection signal Sc. During normal temperature measurement, the output of the first-stage amplifier circuit 41 is selected. Further, when checking the temperature difference between the first temperature sensitive sensor 32a and the second temperature sensitive sensor 32b, the reference potential is selected.

Next, the temperature compensation operation of the optical system, particularly the light guide tube 21, will be described. At this time, the switching circuit 42 selects the output of the first-stage amplifier circuit 41. First of all,
When the temperature Tp of the light guide tube 21 and the temperature To of the infrared sensor 31 are equal, that is, when the temperatures of the two temperature sensitive sensors are equal, the two resistance values are equal. The temperature difference signal Td of the temperature difference circuit 32 is
The potential becomes an intermediate potential between the (+) power supply and the (-) power supply, and this potential becomes equal to the reference potential. Therefore, the compensation circuit 43 operates as an inverting amplifier circuit having only one input resistance 43b side. That is, the infrared sensor 31 is amplified by the first-stage amplifier circuit 41, and the compensation circuit 43 inverts and amplifies the voltage as it is.

Next, when the temperature Tp of the light guide tube 21 is higher than the temperature To of the infrared sensor 31, the output voltage of the infrared sensor 31 becomes high as described above. then,
The resistance value of the second temperature sensor 32b is smaller than that of the first temperature sensor 32a. Then, the temperature difference signal Td is
It becomes lower than the reference potential. As a result, the compensation circuit 43
One of the inputs becomes a negative input and operates as a subtraction circuit. That is, although the output voltage of the infrared sensor 31 becomes high, the temperature difference signal Td is subtracted from the output of the first-stage amplifier circuit 41 by the compensation circuit 43 so that the voltage becomes the same as the output signal Vr in the standard state. , Which means that it is inverted and amplified.

On the contrary, when the temperature Tp of the light guide tube 21 is lower than the temperature To of the infrared sensor 31, the infrared sensor 31
However, the compensation circuit 43 adds the temperature difference signal Td from the output of the first-stage amplifier circuit 41 and inversely amplifies it. As described above, even if the temperature Tp of the light guide tube 21 and the temperature To of the infrared sensor 31 are not the same in the standard state, the output signal Vr of the optical system temperature compensating circuit 44 is output in the analog circuit. Computational amplification is performed and the voltage is corrected to the same voltage as in the standard state.

In the temperature compensation of the optical system, the temperature difference between the light guide tube 21 and the infrared sensor 31 is generally set within an allowable range. This permissible range can be set by experimental results actually measured or simulations. Here, the operation of checking whether the temperature difference between the light guide tube 21 and the infrared sensor 31 is within the allowable range will be described. At this time, the switching circuit 42 selects the reference potential, and the input on the input resistance 43b side of the compensation circuit 43 is at the reference potential. That is, the compensating circuit 43 is inverting and amplifying only the temperature difference signal Td of the temperature difference circuit 32.

First, when the temperature Tp of the light guide tube 21 is higher than the temperature To of the infrared sensor 31, the temperature difference signal Td becomes
It becomes lower than the reference potential. Then, the output signal Vr of the compensation circuit 43 has a positive potential. On the contrary, when the temperature of the light guide tube 21 is lower than the temperature of the infrared sensor 31, the output signal Vr of the compensation circuit 43 becomes negative. The allowable positive and negative limit values at these times are set in advance and are compared with this potential.

Specifically, the positive and negative limit values are
It is stored in the arithmetic control circuit 5 as A / D converted digital data. Then, it is checked whether the temperature difference between the light guide tube 21 and the infrared sensor 31 is within the allowable range by comparing with the limit value stored in the arithmetic control circuit 5. When the result is within the range of the positive and negative limit values, the temperature is compensated for measurement, but when it is out of the range, the measurement prohibition mark 61m is turned on without performing the measurement. .

In order to measure the surface temperature of the light guide tube, the second temperature sensitive sensor 32b does not necessarily have to be embedded in the recess of the housing 23 with the sealing resin. For example, in order to prevent an error in measurement accuracy when the room temperature changes, the second temperature sensor 32b may respond to the room temperature change in the same manner as the surface temperature of the light guide tube. In this case, the second temperature sensor 32b may be mounted on the circuit board because it does not need to be in contact with the light guide tube 21 as long as it has the same response.

The infrared sensor is not limited to the thermopile, but can be applied to a system using a pyroelectric element. Further, the temperature sensor is not limited to the thermistor, and any element having a temperature characteristic may be used, and a diode or the like may be used.

The housing 23 is shown as an example in which aluminum has good heat conductivity. However, since the light guide tube 21 does not have to have the same temperature as the infrared sensor 31, it does not necessarily have to be a metal in consideration of heat conduction. It suffices that the components of the optical system 2, the detection element 3 and the like can be fixed, and may be made of plastic or the like. Of course, these may be fixed with an adhesive or the like without the housing.

[0042]

As described above, according to the present invention, the temperature information of the light guide tube of the optical system is used as the temperature difference between the infrared sensor and the light guide tube, and in the optical system temperature compensating circuit, the operational amplification is performed in the analog circuit. Is corrected. Therefore, a temperature measuring circuit for measuring the temperature of the light guide tube, an A / D conversion circuit, or an input selection circuit for the A / D conversion circuit can be eliminated. Therefore, the circuit configuration can be simplified.

Even when a temperature difference occurs between the infrared sensor and the light guide tube, a complicated equation is calculated based on the three variables, that is, the temperature data of the two temperature sensitive sensors and the output data of the infrared sensor. It is no longer necessary to use and calculate temperature data. Also, it is no longer necessary to measure the emissivity of the light guide tube in advance. Instead of this, a simple equation based on the two variables of the temperature data of the first temperature-sensitive sensor and the output data of the infrared sensor when the infrared sensor and the light guide tube are in a standard state where there is no temperature difference. Now you can calculate the temperature data. As a result, arithmetic processing can be performed in a short time.

In addition to the first temperature sensitive sensor for measuring the temperature To of the infrared sensor, a second temperature sensitive sensor is provided for measuring the surface temperature Tp of the light guide tube. Then, since the body temperature data is calculated by correcting the temperature difference, it is possible to measure the body temperature without waiting for a state where there is no temperature difference even if there is a temperature difference between them. Therefore, the interval of repeated measurement can be shortened, and in collective temperature measurement, the temperature can be measured in a short time without waiting time.

Further, when the temperature difference between the two temperature-sensitive sensors exceeds the allowable range of optical system temperature compensation, the measurement-prohibiting mark is turned on to prohibit the measurement, without lowering the measurement accuracy. We were able to obtain sufficient measurement accuracy as a thermometer.

Further, since the measurement accuracy could be satisfied without using a heating device as in the prior art, it was possible to drive with a small battery, and it was possible to realize a small and low-priced thermometer. Furthermore, the radiation thermometer for measuring the eardrum temperature was considered to be a medical device for doctors and nurses used by doctors and nurses in hospitals, etc., but according to the present invention, it has a great effect in spreading it to general households. is there.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of a detection element and an infrared amplification circuit showing temperature correction of a light guide tube of the present invention.

FIG. 2 is a front view of a radiation thermometer showing an embodiment of the present invention.

FIG. 3 is a basic configuration diagram of a radiation thermometer showing an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a probe and a head showing attachment of an optical system and a detection element of the present invention.

[Explanation of symbols]

 2 Optical system 3 Detection element 4 Amplification circuit 5 Operation control circuit 21 Light guide tube 23 Housing 31 Infrared sensor 32 Temperature difference circuit 32a First temperature sensor 32b Second temperature sensor 43 Compensation circuit 44 Optical system temperature compensation circuit 45 temperature measuring circuit 46 A / D conversion circuit 51 arithmetic circuit

Claims (1)

[Claims] 1. An optical system having a light guide tube for collecting heat radiation from a measurement object, an infrared sensor for converting heat radiation energy collected through the light guide tube into an electric signal, and the red sensor. From the first and second temperature-sensitive sensors, a detection element having a first temperature-sensitive sensor that measures the temperature of the outer sensor and a second temperature-sensitive sensor that measures the surface temperature of the light guide tube In a radiation thermometer provided with an arithmetic circuit for calculating body temperature data according to the electric signal from the infrared sensor and a display device for displaying the body temperature according to the body temperature data,
The temperature difference circuit that detects the temperature difference by the first and second temperature sensors and the electric signal from the infrared sensor are arithmetically amplified by an analog circuit based on the temperature difference signal from the temperature difference circuit. A radiation thermometer having an optical system temperature compensation circuit.