WO2000004353A1

WO2000004353A1 - Radiation thermometer

Info

Publication number: WO2000004353A1
Application number: PCT/JP1998/003138
Authority: WO
Inventors: Kazuhito Sakano
Original assignee: Kazuhito Sakano
Priority date: 1998-07-14
Filing date: 1998-07-14
Publication date: 2000-01-27
Also published as: AU8129698A

Abstract

A radiation thermometer that detects infrared rays emitted from an object with a thermopile to effect a non-contact measurement of the temperature of the object. The thermometer enables accurate temperature measurement, has a less number of components, is produced at a low cost, and has an excellent durability. The thermometer comprises self-controlled positive temperature coefficient heating elements (11, 12, 13, 14) for maintaining required portions such as a thermopile (5), a wave guide (4) and a printed circuit board (6) at predetermined temperatures. When currents are passed through the heating elements, their resistances sharply increase at certain temperatures. Therefore the flows of currents are controlled and the heating elements are maintained at predetermined temperatures. In this way, the required portions such as the thermopile (5) can be maintained at predetermined temperatures, for example at 32 °C.

Description

Specification

Radiation thermometer

TECHNICAL FIELD The present invention relates to a radiation thermometer, and more particularly, to a radiation thermometer that detects infrared rays radiated from a measurement target with a thermopile and measures the temperature of the measurement target in a non-contact manner.

2. Description of the Related Art Conventionally, a radiation thermometer has been used to detect infrared rays emitted from an object to be measured and to measure the temperature of the object without contact. For example, in recent years, thermometers emit more radiation from the eardrum and surrounding tissues than contact-type thermometers such as the sublingual thermometer that measures the temperature in the oral cavity and the axillary thermometer that measures the temperature in the axilla for reasons of hygiene and convenience. The demand for non-contact thermometers that measure body temperature by detecting infrared rays is increasing.

Since the tympanic membrane is located deep in the human body and is less susceptible to the external environment, it can measure body temperature more accurately than other parts of the human body such as the oral cavity and axilla. One.

Non-contact type thermometers generally use a pyroelectric sensor or a thermopile sensor as a non-contact type temperature sensor for detecting infrared rays radiated from an object to be measured. A pyroelectric sensor is a sensor that detects, as an output, a change in surface charge of a pyroelectric body due to a temperature change when absorbing infrared energy radiated from a measurement object. Impatience In order to output only when the temperature of the pyroelectric body changes, the electric sensor outputs the continuous output by intermittently cutting off the incident infrared rays by shoving. On the other hand, a thermopile sensor is a sensor in which thermocouples are deposited using integrated circuit technology, and a continuous output for the temperature difference between the hot junction and the cold junction is obtained by a large number of directly connected thermocouples. .

Hereinafter, a non-contact thermometer using a thermopile will be described as an example of a conventional radiation thermometer as a non-contact temperature sensor for detecting infrared radiation emitted from an object to be measured.

As a conventional non-contact type thermometer using a thermopile, there is, for example, a temperature measuring device disclosed in Japanese Patent Application Laid-Open No. Sho 61-117424. Such a temperature detector will be described with reference to FIGS. 5 to 7.

As shown in FIG. 5, the temperature detecting device includes a probe unit 21, a chopper unit 22, and a charging unit (not shown). The probe unit 21 has a structure that can be grasped with the hand of the operator when performing temperature measurement on a patient. That is, at the time of temperature measurement, the user grasps the handle 23 provided on the probe unit 21 and handles the probe unit 21. Further, the probe unit 21 is mechanically matched with the chopper unit 22, and the electronic mechanisms inside the probe unit 21 and the chopper unit 22 are the same as those of the first embodiment. As shown in Fig. 5, they are electrically connected by cord 24.

As shown in Fig. 6, the probe unit 21 is provided with a head portion 25 protruding from the front end of the handle 23 in the shape of a "K", as shown in Fig. 6, and a head portion 25 The probe 26 is attached to the tip of. The probe 26 is covered with a plastic disposable temperature cover 27 for hygienic reasons at the time of temperature measurement and inserted into the patient's ear canal.

The insides of the head portion 25 and the probe 26 have the structure shown in FIG. That is, a cylindrical metal housing 28 having excellent thermal conductivity is provided inside the head portion 25 and the probe 26, and an infrared ray is detected inside the metal housing 28 to generate an electromotive force. A thermopile 29 is provided. Further, inside the metal housing 28, a waveguide 30 for introducing infrared rays to the thermopile 29 and a gold A heater section 31 for controlling the temperature of the metal housing 28 to a set temperature (for example, a temperature near body temperature of 36.6 ° C.) is provided. The temperature control section 31 is controlled by a temperature control circuit (not shown). Such a temperature control circuit has a thermistor, a heating resistor, an amplifier and the like.

Since the metal housing 28, the thermopile 29 and the waveguide 30 are arranged so as to be in thermal contact with each other, the temperature of the metal housing 28 must be controlled to the set temperature in the heater 31. Thus, the metal housing 28, thermopile 29 and waveguide 30 are maintained at the same set temperature.

The chopper unit 22 is rectangular and box-shaped as shown in FIG. A handle 23 is placed in a concave portion formed on the upper surface of the chopper unit 22. The head portion 25 and the probe 26 can be accommodated in a receiving portion communicating with the concave portion. . Further, a thermometer 27 is arranged on the upper surface of the chopper unit 22 and a liquid crystal display 32 for displaying the measured body temperature and the like is also installed. Inside the chopper unit 22, the electronic circuit for calculating the body temperature based on the data detected by the probe unit 21 and the error of the thermopile 29 due to the temperature change of the measurement environment are reduced. A chopper evening geter is provided. The chopper unit 22 is charged by a charging unit (not shown).

The body temperature is measured by such a thermometer as follows.

As shown in Fig. 6, at the time of temperature measurement, the probe 26 is inserted into the patient's ear canal, and infrared radiation radiated from the eardrum and surrounding tissue is detected from the waveguide 30 into the thermopile 29. I do. The thermopile 29 generates an electromotive force according to the amount of incident infrared light, and the output signal is sent to the microcomputer inside the tiller unit 22.

Here, the output of the thermopile 29 is V, the temperature of the object to be measured (body temperature) is T, and the temperature of the thermopile 29 is Τ. Then, the output V of the thermopile 29 is given by Stephan-Boltzmann's law.

V = k (T ⁴ — T. ⁴ ) k is a constant (1)

It is expressed as As mentioned above, the temperature T of the thermopile 29. The temperature can be controlled to the set temperature by the night section 31. Therefore, from (1), the output V of the thermopile 29 and the temperature T of the thermopile 29 are obtained. Data is sent to a microcomputer provided inside the chopper's unit 22. Based on the data, a fourth root calculation is performed by the microcomputer to obtain the patient's body temperature T. .

The temperature detector disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 611-117422 is caused by the fact that the probe 26 removes heat from the ear canal by controlling the probe 26 to the set temperature. The temperature of the ear canal was prevented from lowering, and as a result, the measurement error due to the temperature change of the ear canal was reduced.

In addition, the temperature detector disclosed in Japanese Patent Application Laid-Open No. 61-114742 controls the temperature of the thermopile 29 to a set temperature, thereby allowing the temperature of the thermopile to change with the temperature change of the measurement environment. The measurement error caused by the output change of 29 was able to be reduced.

However, although the conventional radiation thermometer has the above advantages as exemplified in the temperature measuring device disclosed in Japanese Patent Application Laid-Open No. 61-114,222, it has the following problems. I got it.

As shown in the temperature detector shown in No. 6-11, the conventional radiation thermometer uses a thermometer such as a thermistor to set the probe and thermopile to the set temperature. A complicated temperature control circuit was required. Therefore, the cost increase due to the increase in the number of parts was inevitable.

In addition, a chopper target was required to reduce thermopile errors due to temperature changes in the measurement environment. For this reason, not only was the cost increased, but also the complexity of optimizing the thermopile with a chopper was obtained.

In addition, in the conventional radiation thermometer, in a low-temperature measurement environment, for example, in a measurement environment at 0 ° C to 10 ° C, the electronic components of the circuit board built into the radiation thermometer cause temperature drift. In some cases, a measurement error may occur due to this. On the other hand, it is necessary to provide a correction circuit and the like in order to prevent the temperature drift of such electronic components, and in order to improve the measurement accuracy, such a circuit is inevitably complicated. The increase in points has led to higher costs.

Furthermore, the conventional radiation thermometer sets the probe and thermopile to the set temperature as described above. In order to achieve this, the temperature control circuit had to be complicated, and there was also a problem in durability against impacts such as dropping.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art, improve the measurement accuracy, and provide an inexpensive and durable radiation thermometer with a small number of parts.

DISCLOSURE OF THE INVENTION The present invention, which is provided to solve the above-described problems, provides a radiation thermometer that detects infrared rays emitted from a measurement target and measures the temperature of the measurement target, and maintains a required portion at a required temperature. The radiation thermometer has a self-control positive temperature coefficient heating element.

The self-regulating positive temperature coefficient heating element has the property that the electrical resistance of the heating element increases as the temperature of the heating element rises when energized, so the current is suppressed and the heating element reaches the set temperature. Is maintained.

Therefore, a radiation thermometer that detects infrared radiation emitted from the measurement target and measures the temperature of the measurement target has a self-control type positive temperature coefficient heating element that maintains the required temperature at the required temperature, so that the required location is required. A complicated temperature control circuit including a temperature measuring element such as a thermistor is not required to maintain the temperature. Therefore, it is possible to provide an inexpensive and durable radiation thermometer with improved measurement accuracy and a reduced number of parts. In addition, since the self-regulating positive temperature coefficient heating element does not rise above the set temperature as described above, especially when the radiation thermometer according to the present invention is a thermometer, burns due to overheating can be prevented. Can be prevented. Therefore, a highly safe thermometer can be provided.

In addition, the present invention provided to solve the above-mentioned problem is directed to a self-control that maintains all required parts at a set temperature in a radiation thermometer that detects infrared radiation emitted from a measurement target and measures the temperature of the measurement target. A radiation thermometer characterized by having a positive temperature coefficient heating element.

The components that make up the radiation thermometer include the temperature of the measurement environment and the heat generated by the components themselves (CPU, etc.). In general, each component is in various temperatures due to the effects of heat-generating electronic components. Therefore, conventionally, in order to maintain a required portion of the radiation thermometer at a set temperature, a heating device, a temperature measuring element, and a temperature control circuit were required for each component.

Therefore, a radiation thermometer that detects infrared radiation emitted from the measurement target and measures the temperature of the measurement target has a self-regulating positive temperature coefficient heating element that maintains all required parts at a set temperature, so that all required parts are maintained. It is not necessary to provide a heating device, a temperature measuring element, and a temperature control circuit for each required part when maintaining the required temperature at the set temperature, and all of the required parts are maintained at the set temperature with one self-control positive temperature coefficient heating element. can do. Therefore, it is possible to provide an inexpensive and durable radiation thermometer with improved measurement accuracy and a reduced number of parts.

In the radiation thermometer according to the present invention described above, the required part can be selected from at least one of a thermopile, a nozzle, and a printed circuit board. When a thermopile is selected as the required part, the thermopile can be controlled to the set temperature, so that measurement errors caused by changes in the output of the thermopile due to temperature changes in the measurement environment can be reduced.

In addition, when the nozzle is selected as the required part, the nozzle can be controlled to the set temperature. Therefore, particularly when the radiation thermometer according to the present invention is an ear thermometer, the nozzle is connected to the ear hole. It is possible to prevent the temperature of the ear canal from lowering due to the deprivation of heat, and as a result, it is possible to reduce the measurement error due to the temperature change of the ear canal.

Furthermore, when a printed circuit board is selected as the required part, the circuit board can be controlled to the set temperature, so that the circuit can be controlled even in a low-temperature measurement environment, for example, in a measurement environment at 0 ° C to 1 ° C. The electronic components on the substrate can be prevented from causing a temperature drift, and measurement errors can be reduced.

The above-mentioned thermopile and printed circuit board can be attached to a board that houses them together.

By using a board having a thermopile and a printed circuit board in this way, a self-controlling positive temperature coefficient heating element can be attached to the board. The temperature of the substrate can be controlled. The self-controlling positive temperature coefficient heating element used in the radiation thermometer according to the present invention is preferably planar. If the self-control type positive temperature coefficient heating element is planar, it can be attached regardless of the shape of each required part, such as winding it around the required part or attaching it.

Further, it is preferable to attach a planar self-control type positive temperature coefficient heating element to the printed circuit board of the radiation thermometer according to the present invention. By attaching a planar self-control type positive temperature coefficient heating element to a printed circuit board, the printed circuit board can be efficiently heated.

Further, it is preferable to print a planar self-control type positive temperature coefficient heating element on the printed circuit board of the radiation thermometer according to the present invention. By printing a planar self-control positive temperature coefficient heating element on a printed circuit board, the printed circuit board can be heated more efficiently.

Further, it is preferable that the printed circuit board of the radiation thermometer according to the present invention is formed of a planar self-control type positive temperature coefficient heating element. When the printed circuit board is made of a planar self-control type positive temperature coefficient heating element, the printed circuit board can be heated more efficiently.

Further, when the radiation thermometer according to the present invention is an ear thermometer, it is preferable that a required portion of the radiation thermometer is maintained at a temperature near body temperature. For example, since the output of the thermopile becomes lower as the temperature is closer to the temperature of the object to be measured, the noise when the output is amplified also becomes lower. Therefore, the measurement error can be reduced as the temperature of the thermopile is closer to the body temperature. Also, as the temperature of the nozzle is closer to the body temperature, the temperature of the ear canal can be prevented from lowering due to the nozzle taking away heat from the ear canal, and as a result, the measurement error due to the temperature change of the ear canal can be reduced. Further, by maintaining the electronic components in the thermometer at a temperature near the body temperature, temperature drift can be prevented, and thus measurement errors can be reduced.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a partially cutaway perspective view of a radiation thermometer according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an infrared detector in the radiation thermometer according to one embodiment of the present invention.

FIG. 3 is a resistance-temperature characteristic graph of a positive temperature coefficient heating element in the radiation thermometer according to one embodiment of the present invention.

FIG. 4 is a block circuit diagram showing a radiation thermometer according to one embodiment of the present invention.

FIG. 5 is a plan view showing a conventional temperature detector.

FIG. 6 is an explanatory diagram showing a temperature detection state in a conventional temperature detection device.

FIG. 7 is a cross-sectional view of an infrared detector in a conventional temperature detector. Explanation of reference numerals

1 Main unit case

2 Infrared detector

3 Temperature measurement circuit

Four

5 Thermopiles

6 Printed circuit board

7 Switch

8 LCD temperature display

9 Hybrid board

1 0 nozzle

1 1 4 Self-control type positive temperature coefficient heating element

1 5 Operational amplifier

1 6 Microcomputer

1 7 Drive IC BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The radiation thermometer according to one embodiment of the present invention is an ear thermometer. As shown in FIG. 1, a main body case 1, an infrared detection section 2 and a temperature measurement circuit section 3 housed in the main body case 1. It is composed of The infrared detecting section 2 has a waveguide 4 and a thermopile 5, and the temperature measuring circuit section 3 has a printed circuit board 6, a switch 7, and a liquid crystal temperature display 8.

The infrared detecting section 2 and the temperature measuring circuit section 3 are incorporated and fixed in a plate-shaped hybrid board 9 as shown in FIG. The hybrid board 9 has a shape with a thin tip in accordance with the shape and the location of the waveguide 4, the circuit pile 5, the printed circuit board 6, and the like.

The nozzle 10 at the tip of the main body case 1 inserted into the ear canal is formed so as to become thinner toward the tip so as not to be inserted deeply into the ear canal, so that the user can use it safely. Further, the infrared detecting section 2 is disposed at the tip of the main body case 1 and detects infrared rays incident from a hole provided at the tip of the nozzle 10.

As shown in FIGS. 1 and 2, the infrared detecting section 2 is installed in a thermopile 5 for detecting infrared rays radiated from the eardrum and in the nozzle 10 at the tip of the main body case 1 and radiated from the eardrum. And a waveguide 4 for efficiently transmitting weak infrared light. As shown in Fig. 1, planar self-control type positive temperature coefficient heating elements 11 and 12 are attached to the surfaces of the thermopile 5 and the waveguide 4, and the inner surface of the nozzle 10 is As shown in FIG. 2, a planar self-control positive temperature coefficient heating element 13 is attached. As will be described later, a planar self-control positive temperature coefficient heating element 14 is also attached to the printed circuit board 6. As described above, in the present embodiment, a planar self-control type positive temperature coefficient heating element that can be attached regardless of the shape of each required component is used.

Conductive wires are connected to the planar self-control type positive temperature coefficient heating elements 11 to 14 so that a constant current can flow. The self-controlled positive temperature coefficient heating element By controlling the flow, the infrared detector 2 and the nozzle 10 are controlled to a set temperature near the body temperature, for example, 32 ° C.

Here, the self-control type positive temperature coefficient heating elements 11 to 14 will be described. As shown in the resistance-temperature characteristic graph of Fig. 3, the self-control type positive temperature coefficient heating elements 11 to 14 increase the electrical resistance of the heating element as the temperature of the heating element rises when energized. It is a heating element with characteristics. In particular, the self-control positive temperature coefficient heating elements 11 to 14 have the property that the electrical resistance increases rapidly at a certain temperature. Generally, when a current is passed through a resistor, it generates heat.However, the self-control type positive temperature coefficient heating element 11 to 14 rapidly increases its electrical resistance at a certain temperature as described above. The positive temperature coefficient heating elements 11 to 14 are maintained at a constant temperature.

That is, the self-control type positive temperature coefficient heating elements 11 to 14 are heating elements that can control the heating temperature by themselves. Therefore, by attaching the self-control type positive temperature coefficient heating elements 11 to 14 to required portions such as the thermopile 5, the required portions such as the thermopile 5 can be maintained at a set temperature, for example, 32 ° C.

In the radiation thermometer according to the present embodiment, since the self-control type positive temperature coefficient heating elements 11 to 14 are directly attached to the required parts such as the thermopile 5, the required parts such as the Can be maintained at the set temperature. In addition, since the self-control type positive temperature coefficient heating elements 11 to 14 are not heated above the set temperature, the radiation according to the present embodiment using the self-control type positive temperature coefficient heating elements 11 to 14 is performed. Thermometers are safe with no danger of overheating.

By maintaining the required temperature at the set temperature near the body temperature, the following effects can be obtained. As the temperature of the thermopile 5 becomes closer to the temperature of the object to be measured, the output becomes smaller, so that the noise when the output is amplified becomes smaller. In addition, the digital resolution of the microcomputer 16 described later can be improved. Therefore, the measurement error can be reduced as the temperature of the thermopile 5 is set closer to the body temperature. In addition, as the temperature of the nozzle 10 is closer to the body temperature, the temperature of the ear canal can be prevented from lowering due to the nozzle 10 taking heat from the ear canal. Can be reduced. In addition, maintaining the electronic components in the thermometer at a temperature near body temperature prevents temperature drift. Therefore, the measurement error can be reduced.

The temperature measurement circuit section has a printed circuit board 6 in which a temperature measurement circuit is incorporated, a switch 7 directly attached to the print board 6, and a liquid crystal temperature display 8. The printed circuit board 6 is connected to the thermopile 5. Further, the switch 7 and the liquid crystal temperature indicator 8 are exposed to the outside of the main body case 1 through holes provided in the main body case 1 respectively. When switch 7 is pressed, the body temperature measurement starts, and the LCD temperature display 8 displays the measured body temperature digitally.

Further, the printed circuit board 6 is fitted into the hybrid board 9, and as shown in FIGS. 1 and 2, the upper and lower surfaces of the printed circuit board 6 are provided with planar self-control type positive temperature coefficient heating elements 14 respectively. Affixed.

In the radiation thermometer according to the present embodiment, as shown in FIGS. 1 and 2, the thermopile 5, the waveguide 4, the nozzle 10 and the printed circuit board 6 are each maintained at a set temperature. The self-regulating positive temperature coefficient heating elements 11 to 14 are attached to them, but the method of attaching the self-controlling positive temperature coefficient heating elements to these required parts is not limited to the above. . That is, for example, in FIG. 1, the entire hybrid board 9 in which the thermopile 5, the printed circuit board 6, and the like are incorporated may be wound with one planar self-controlling positive temperature coefficient heating element. As for the printed circuit board 6, a planar self-control type positive temperature coefficient heating element may be printed on the printed circuit board 6. Further, the board itself other than the electronic components of the printed board 6 may be formed of a planar self-control type positive temperature coefficient heating element. In particular, by printing a planar self-control type positive temperature coefficient heating element on the printed circuit board 6, and by forming the substrate itself with a planar self-control type positive temperature coefficient heating element, heat can be efficiently supplied to electronic components. Can be transmitted.

Next, how the body temperature is measured by the radiation thermometer described above will be described with reference to the block circuit diagram of FIG.

In FIG. 4, the thermopile 5 provided in the radiation thermometer outputs a voltage depending on the amount of infrared rays radiated from the eardrum and the temperature of the thermopile 5. That is, the thermopile 5 outputs a voltage corresponding to the difference between the temperature of the measurement target and the temperature of the thermopile 5. The operational amplifier 15 connected to the thermopile 5 amplifies the small voltage output from the thermopile 5 to a predetermined magnitude. Connected to operational amplifiers 15 The microcomputer 16 has an A / D converter built in, and the microcomputer 16 performs arithmetic processing based on the output signal from the operational amplifier 15 and outputs the temperature value output of the measurement target to the liquid crystal temperature display 8. send. The liquid crystal temperature display 8 digitally displays the temperature of the object to be measured.

As shown in FIGS. 1 and 2, the planar self-control positive temperature coefficient heating elements 11 to 14 are attached to the inner surface of the nozzle 10, the waveguide 4, the thermopile 5, and the printed circuit board 6, respectively. Have been. The drive IC 17 supplies a predetermined current to the self-controlling positive temperature coefficient heating elements 11 to 14 in accordance with the heating command signal from the microcomputer 16.

In the radiation thermometer according to the present embodiment, a heating command signal is sent from the microcomputer 16 to the drive IC 17 by the user pressing the switch 7 before the start of the temperature measurement, and the heating command signal is sent in accordance with the heating command signal. A predetermined current flows through the self-control type positive temperature coefficient heating elements 11 to 14 to heat a predetermined portion. For this reason, at the start of temperature measurement, the predetermined part has risen to the set temperature.

Then, when the user presses switch 7 and the command to start temperature measurement is transmitted to microcomputer 16, microcomputer 16 receives the amplified output signal of thermopile 5 from operational amplifier 15 and self- The arithmetic processing is performed based on the temperature of the thermopile 5 preset by the control type positive temperature coefficient heating elements 11 to 14. The temperature of the eardrum detected by the microphone mouth computer 16 is recognized by being displayed on the liquid crystal temperature display 8.

As described above, the radiation thermometer according to the present embodiment includes the thermopile 5, the waveguide 4, the nozzle 10, the printed circuit board 6, and the planar self-control type positive temperature coefficient heating elements 11 to 14. By mounting, the drive IC 17 can be integrated into one without requiring a temperature control circuit for each required part. Therefore, according to the radiation thermometer according to the present embodiment, it is possible to provide an inexpensive and durable radiation thermometer that has improved measurement accuracy, has a small number of components, and has a small number of components.

Further, in the radiation thermometer according to the present embodiment, the printed circuit board 6 is maintained at the set temperature by the sheet-shaped self-control type positive temperature coefficient heating element 14, so that the measurement error can be obtained even in a low-temperature measurement environment. Can be reduced.

Claims

The scope of the claims

I. A radiation thermometer that detects infrared radiation emitted from a measurement target and measures the temperature of the measurement target, characterized in that it has a self-regulating positive temperature coefficient heating element that maintains required parts at the required temperature. Radiation thermometer.

2. A radiation thermometer that measures the temperature of a measurement target by detecting infrared radiation emitted from the measurement target, characterized by having a self-regulating positive temperature coefficient heating element that maintains all required parts at a set temperature. Radiation thermometer.

3. The radiation thermometer according to claim 1, wherein the required part is selected from at least one of a thermopile, a nozzle, and a printed circuit board.

4. The radiation thermometer according to claim 2, wherein the required part is selected from at least one of a thermopile, a nozzle, and a printed circuit board.

5. The radiation thermometer according to claim 3 or 4, further comprising a board having a thermopile and a printed circuit board.

6. The radiation thermometer according to claim 1, wherein the self-control type positive temperature coefficient heating element has a planar shape.

7. The radiation thermometer according to claim 5, wherein the self-control type positive temperature coefficient heating element has a planar shape.

8. The radiation thermometer according to claim 6, comprising a printed circuit board to which a planar self-control type positive temperature coefficient heating element is attached.

9. The radiation thermometer according to claim 7, comprising a printed circuit board to which a planar self-control type positive temperature coefficient heating element is attached.

10. The radiation thermometer according to claim 6, further comprising a printed circuit board on which a planar self-control type positive temperature coefficient heating element is printed.

8. The radiation thermometer according to claim 7, further comprising a printed circuit board on which a planar self-control type positive temperature coefficient heating element is printed.

12. The radiation thermometer according to claim 6, wherein the substrate has a printed circuit board made of a planar self-control type positive temperature coefficient heating element.

13. The radiation thermometer according to claim 7, wherein the substrate has a printed circuit board made of a planar self-control type positive temperature coefficient heating element.

14. The radiation thermometer according to claim 1, wherein the required temperature is a temperature near a body temperature.

15. The radiation thermometer according to claim 5, wherein the required temperature is a temperature near a body temperature.

16. The radiation thermometer according to claim 6, wherein the required temperature is a temperature near a body temperature.

17. The radiation thermometer according to claim 7, wherein the required temperature is a temperature near a body temperature.