JPH10290790A - Radiation thermometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve temperature check accuracy while reducing the thermal imbalance between a condensing means and an infrared sensor as much as possible by inserting and arranging the condensing means and the infrared sensor together inside a probe means in contact with an earhole part. SOLUTION: An arithmetic means 8 is turned into standby state by pressing a power source switch 12, a probe 2 is inserted into the earhole part, and an operating switch 13 is pressed. The arithmetic means 8 drives a chopper 10 and infrared rays radiated from the earhole part are detected by an infrared sensor 4, amplified by a filter amplifier 6, converted to a digital value by an A/D converter 7 and inputted to the arithmetic means 8. At the same time, the temperature of infrared sensor 4 itself is detected by a temperature detector 5, converted to a digital value by the A/D converter 7 and inputted to the arithmetic means 8 as well. As the output of infrared sensor 4, a value proportional to the fourth power difference between the temperature of earhole part and the temperature of infrared sensor 4 itself is outputted. Since the condensor and the infrared sensor are inserted into the probe, no temperature gap occurs.

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 body temperature by detecting infrared energy near the eardrum.

[0002]

2. Description of the Related Art Recently, an eardrum thermometer (hereinafter referred to as a radiation thermometer) which detects infrared rays radiated from the vicinity of the eardrum and measures the body temperature of the human body in about 1 to 2 seconds is applied to the measurement of the body temperature. It has become. Such a radiation thermometer has a probe inserted into the ear canal, and a waveguide for optically connecting infrared light incident from the tip of the probe to an infrared sensor disposed in the main body of the thermometer. Pyroelectric elements are generally used for infrared sensors. The principle of this detection is that a voltage proportional to the fourth power difference between the temperature of the object and the temperature of the infrared sensor itself can be taken out. If the temperature of the infrared sensor itself is detected by a thermistor, the temperature of the object can be detected by calculation. It is. The detection temperature accuracy required for the radiation thermometer is ± 0.1 ° C., and extremely high accuracy is required. As issues to realize this detection accuracy,
The biggest problem is that the infrared sensor detects not only the ear canal temperature of the target object but also the temperature of the waveguide inside the probe because of the presence of the probe. Since no imbalance occurs, the error is zero, but if different, an error occurs. In other words, the temperature inside the probe, that is, the temperature of the waveguide, and the thermal balance of the infrared sensor itself are important issues in terms of detection accuracy, and many proposals have been made. Such a thermometer is typically described in JP-A-5-26169, and the configuration is shown in FIG. Waveguide 80
It is desirable that the temperature of the waveguide 80 be stable so that unknown temperature factors are not added to the temperature and the measured temperature of the patient is not adversely affected. When the probe 81 comes into contact with the patient's ear, a heat flow is generated between the probe 81 and the ear hole in contact with the probe 81. As a result, the measurement of the patient's body temperature is inaccurate by transferring the patient's heat through the probe to the waveguide 80 causing a "hot spot" or temperature fluctuation in the waveguide 80. Probe 8
Although it is desirable that no physical contact between 1 and the ear canal occurs, such contact is inevitable. In order to minimize the influence of external heat on the thermometer, the above publication discloses a radiator means 82 in thermal contact with the waveguide 80.
The heat radiator means 82 is made of copper having relatively high heat diffusion and heat conductivity and a large heat capacity, and furthermore, the space between the heat radiator means 82 and the probe 81 is air-insulated. Air insulation means 83 for forming the resulting closed layer
It is disclosed that the infrared sensor 84 is disposed in the main body case.

Japanese Patent Application Laid-Open No. 61-117422 has a heating control means for preheating the probe to a reference temperature close to the body temperature. It is disclosed that an attempt is made to eliminate the thermal imbalance of the waveguide caused by insertion into the part.

[0004]

However, Japanese Patent Application Laid-Open No.
The radiation thermometer described in 1-1117422 is extremely excellent in temperature measurement accuracy, but on the other hand, requires a heating control device with high control accuracy, so that the structure and circuit configuration are complicated and the cost is increased. There is.

The radiation thermometer disclosed in Japanese Patent Application Laid-Open No. Hei 5-26169 has a large heat capacity, such as copper, and constitutes a waveguide or a radiator. It is not transmitted to the sensor, and the infrared sensor is located not in the probe but in the thermometer body case at a position away from the tip of the waveguide, so the line length from the waveguide to the infrared sensor is long and the temperature distribution Occurs, and the temperature difference between the waveguide and the infrared sensor increases, causing a temperature measurement error. The longer the waveguide, the greater this error. Further, in order to reduce the temperature measurement error, the inner surface of the waveguide is processed so as to increase the reflectance of infrared rays. Accuracy cannot be obtained. Measurement is performed by inserting a probe of the radiation thermometer into the ear canal. Generally, the measurement is completed in 1 to 2 seconds with the eardrum radiation thermometer, and thus measurement is easily performed a plurality of times. At this time, heat flow occurs between the ear canal and the probe. Then, if the thermal balance between the waveguide and the infrared sensor becomes inconsistent, the measured value will be different each time measurement is performed. That is, when the probe of the thermometer is inserted into the ear canal, heat flows between the ear canal and the probe. As a result, the temperature inside the probe, that is, the temperature of the waveguide, and the thermal imbalance of the infrared sensor itself cause a temperature detection error, which is a serious problem in terms of detection accuracy and stability.

[0006] Even if such a thermal change occurs, it is desired not to increase the cost and to improve the temperature detection accuracy by minimizing the thermal imbalance between the light collecting means and the infrared sensor. I have.

[0007]

In order to solve the above-mentioned problems, the present invention does not dispose the focusing means and the infrared sensor at a distance from each other as in the prior art, but instead installs the inside of the probe means in contact with the ear canal. The light collecting means and the infrared sensor are both inserted and arranged.

According to the above invention, since the light collecting means and the infrared sensor are both disposed inside the probe means, the light collecting means and the infrared sensor can be protected from thermal changes from the outer surface of the probe or from around the probe. Thus, thermal unbalance is less likely to occur, and the temperature measurement accuracy is improved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is directed to a probe for inserting into an ear canal of a human body, a condenser for condensing infrared rays radiated from the vicinity of the eardrum through the probe, and a condenser for collecting the infrared rays. An infrared sensor for detecting emitted infrared light is provided, and the light collecting means and the infrared sensor are inserted in the probe means.

The light condensing means is constituted by a lens, and is arranged substantially at the tip of the probe means.

[0011] The light collecting means is constituted by a hollow tubular member having a smooth mirror surface and an inner surface having a reflectance of greater than 0.95 for infrared rays in a wavelength region detected by the infrared sensor.

Further, since the light-collecting means and the infrared sensor are enclosed in the probe means by the isothermal block means for making their temperatures uniform, the thermal balance between the light-collecting means and the infrared sensor itself is lost. Hateful.

Further, since the air gap layer is provided between the probe means and the isothermal block means, heat from the probe means is not easily transmitted to the isothermal block means.

Further, since the reflectivity of the inner surface of the probe means or the outer surface of the isothermal block means which is in contact with the air gap layer is made larger than 0.95, radiant heat from the probe means is hardly transmitted to the isothermal block.

Further, since the lens is a flat lens utilizing the diffraction effect, it can be made thin and small, and the thin film type pyroelectric sensor is used as the infrared sensor. It can be fully charged and arranged.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing a configuration of a radiation thermometer according to Embodiment 1 of the present invention.

In FIG. 1, reference numeral 1 denotes a radiation thermometer main body, and 2 denotes a portion to be inserted into an ear hole, which is a probe means. Reference numeral 3 denotes a condensing means for condensing infrared rays radiated from the vicinity of the eardrum. In this embodiment, a flat lens utilizing a diffraction effect is used. Reference numeral 4 denotes an infrared sensor for detecting infrared light condensed by the lens 3 serving as a light condensing means, and reference numeral 5 denotes a temperature detector for detecting the temperature of the infrared sensor 4 itself, which is a thermistor. Reference numeral 6 denotes a filter amplifier that amplifies a voltage value output from the infrared sensor 4. Reference numeral 7 denotes an AD converter for converting the output of the filter amplifier 6 and the output of the temperature detecting means 5 from an analog value to a digital value, and 8 denotes an arithmetic means for converting and calculating body temperature information based on the output of the AD converter 7. And 9 are display means for displaying the body temperature information calculated by the calculation means 8. As the infrared sensor 5, a pyroelectric element is mainly used.
3. There is a single crystal such as TGS or an organic film such as PVDF, but a bulk type pyroelectric sensor using a ceramic material is generally widely used. However, the infrared sensor used in this embodiment uses a thin-film pyroelectric sensor mainly composed of PbTiO3. The chip area of a bulk pyroelectric sensor is about 2 mm x 2 mm, whereas the chip area of a thin-film pyroelectric sensor is 0.2 m
It is about mx 0.2 mm, and the chip area can be very small. The position of the temperature detector 5 may be any position at which the temperature of the infrared sensor 4 can be detected, and is desirably combined with or adjacent to the infrared sensor 4. 10
Is a chopper for intermittently transmitting infrared light, and is disposed in front of the infrared sensor 4. Reference numeral 11 denotes a power supply, which is composed of a dry battery. Reference numeral 12 denotes a power switch, and 13 denotes a measurement switch, both of which use a push switch.
In this embodiment, the arithmetic means 8 uses a microcomputer, and the display means 9 uses a liquid crystal display device. Further, in this embodiment, a configuration is adopted in which a lens 3 as a light condensing unit, a chopper 10, an infrared sensor 4, and a temperature detector 5 are mounted in the probe unit 2. In addition, the diffraction type flat lens processed using the etching technology is designed such that slight irregularities of about the wavelength are periodically formed on the surface, and the diffraction from each cycle is in phase with the focal point. I have. Therefore, the lens becomes thin and can be miniaturized. In the present embodiment, this lens is arranged at a substantially distal end of the probe means 2 to be inserted into the ear canal, and the infrared sensor 4 is also arranged near this.

The operation will be described. When measuring the temperature, the user holds the radiation thermometer 1 in his hand and presses the power switch 12. In this state, the calculating means 8 enters a standby state. Next, the probe means 2 is inserted into the ear hole, and the operation switch 13 is turned on.
push. When the operation switch 13 is pressed, the calculating means 8
Drives the chopper 10. The infrared radiation emitted from the ear canal is detected by the infrared sensor 4, amplified by the filter amplifier 6, converted to a digital value by the AD converter 7, and then input to the arithmetic unit 8. At this time, at the same time, the temperature of the infrared sensor 4 itself is also detected by the temperature detector 5, converted into a digital value by the AD converter 7, and similarly input to the calculating means 8. As the output of the infrared sensor 4, a value proportional to the fourth power difference between the temperature of the ear canal and the temperature of the infrared sensor 4 itself is output. Further, since the temperature of the infrared sensor 4 itself is detected by the temperature detector 5, the calculating means 8 can calculate the temperature of the ear canal by performing a predetermined calculation. It takes about 1.5 seconds from when the operation switch 13 is pressed until the measurement is completed. A radiation thermometer that detects infrared rays radiated from the eardrum is generally measured a plurality of times repeatedly because the measurement time is generally as short as 1 to 2 seconds. One of the factors that determine the reproducibility of the measurement value is the probe means 2
Thermal factors added by

In many cases, the temperature measurement is repeatedly performed by the same person, but a heat flow is generated between the ear means and the probe means 2, and the longer the contact between the probe means 2 and the ear means, the greater the effect. . FIG. 2 shows the temperature change with time of the inner surface of the probe means 2 and the infrared sensor 4 when the probe means 2 of the thermometer is continuously inserted into the ear canal in a room at room temperature of 25 ° C. "A" in FIG.
2 shows the temperature change of the infrared sensor 4 and b in FIG. 2 shows the temperature change of the lens 3 which is the light condensing means. In 30 seconds, the temperature of the inner surface of the probe means 2, the light collecting means 3 and the temperature of the infrared sensor 4 are about 0.
Although the temperature rises by about 7 ° C., each temperature gap is within 0.1 ° C. This is because the temperature change of the infrared sensor 4 greatly changes due to the heat conduction from the ear hole through the probe means 2, but since the infrared sensor 4 is arranged at a substantially distal end in the probe means 2, the probe means This is because the temperature changes substantially equal to the inner surface temperature of No. 2. Further, in this embodiment, since the lens 3 is used as the light collecting means 3, 95% of the infrared energy
And the radiation energy from the inner surface of the probe means 2 is about 5%. Therefore, the temperature gap of 0.1 ° C. between the inner surface of the probe means 2 and the infrared sensor 4 is 0.01 ° C. or less as a temperature detection error. This is a value sufficiently smaller than the accuracy required for the thermometer, ± 0.1 ° C.

FIG. 3 shows the three-dimensional viewing angle θ of the infrared sensor 4. Since the infrared sensor 4 using a thin-film pyroelectric sensor with a very small chip area and the ultra-small flat lens 3 utilizing the diffraction effect are effectively combined, the infrared sensor 4 and the light condensing means are used. Can be mounted together in the probe means 2. According to this configuration, the optical three-dimensional viewing angle θ of the infrared sensor 4 can be increased as compared with the case where the lens 3 is disposed at the tip of the probe means 2 and the infrared sensor 4 is disposed in the main body case. This leads to an increase in the amount of incident infrared light, which leads to an improvement in temperature accuracy.

As described above, according to this embodiment, the lens 3 serving as the light condensing means is provided in the probe means 2 inserted into the ear canal.
And the infrared sensor 4 are inserted and arranged, so that the temperature change between the inner surface of the probe means 2 and the infrared sensor 4 shows almost the same change with respect to a thermal change from the outside, and the thermal balance is maintained. It is. Therefore, even if the temperature is repeatedly measured, the error in the temperature measurement can be reduced, and the stability can be improved repeatedly.

(Embodiment 2) FIG. 4 is a configuration block diagram of a radiation thermometer according to Embodiment 2 of the present invention.

The structure is substantially the same as that of the first embodiment, except that a lens 3 as a light condensing means, an infrared sensor 4, and a temperature detector 5
In that it is unitized by a metallic isothermal block 14 having good heat conduction. Even in the absence of the isothermal block 14, the light collecting means 3 and the infrared sensor 4 make almost the same temperature change with respect to an external thermal change, as described in the first embodiment. Needless to say, it is better to suppress thermal changes. Since the isothermal block 14 is inserted and disposed in the substantially distal end portion of the probe means 2,
Even if a thermal stress is applied from outside the probe means 2,
The inside of the isothermal block 14 shows the same temperature change in terms of temperature, and the thermal balance between the infrared sensor 4 and the isothermal block 14 is maintained. The accuracy of temperature detection is further improved as compared with 1.

(Embodiment 3) FIG. 5 is a structural block diagram of a radiation thermometer according to Embodiment 3 of the present invention. The configuration is substantially the same as that of the first or second embodiment, except that the condensing means is not the lens 3 but a hollow tubular member 15 having a large inner surface reflectance. The infrared radiation emitted from the vicinity of the eardrum is
The light is condensed on the infrared sensor 4 while being reflected on the inner surface of the lens.
Although the infrared sensor 4 receives the radiant energy of the inner surface temperature of the hollow tubular member 15, the radiant energy of the inner surface temperature of the hollow tubular member 15 is minimized because the infrared sensor 4 is mirror-finished so that the reflectivity becomes extremely large. Becomes possible. The reflectance of the inner surface of the hollow tubular member 15 is 0.95
In this case, the remaining 5% receives the thermal radiation from the inner surface of the hollow tubular member 15 to the infrared sensor 4. But,
In this embodiment, since the hollow tubular member 15 and the infrared sensor 4 are disposed in the probe means 2, even if a thermal change is applied to the probe means 2 from the outside, the hollow tubular member 15 and the infrared sensor 4 The temperature gap is almost thermally balanced. With this configuration, it was confirmed that even if the temperature gap between the hollow tubular member 15 and the infrared sensor 4 transiently occurred at 0.1 ° C., the thermal radiation error from the hollow tubular member 15 was 0.01 ° C. or less. In other words, in order to make the accuracy as a thermometer within ± 0.1 ° C., errors in the circuit system also exist at about 0.05 ° C. to 0.07 ° C., so that the heat radiation error from the hollow tubular member 15 can be ignored. Need to be lowered to Therefore, the reflectivity of the inner surface of the hollow tubular member 15 is preferably greater than 0.95.

According to this configuration, the same effect as that of the first or second embodiment can be obtained. (Embodiment 4) FIG. 6 is a block diagram showing a configuration of a radiation thermometer according to Embodiment 4 of the present invention.

The structure is substantially the same as that of the second embodiment, except that an air gap layer 16 is provided between the inner surface of the probe means 2 and the isothermal block 14 in which the lens 3 as the light condensing means, the infrared sensor 4 and the temperature detector 5 are stored. Is different. With this configuration, the thermal fluctuation applied to the isothermal block 14 can be suppressed due to the presence of the air gap layer 16 against the thermal fluctuation applied from outside the probe unit 2. Even if the thermal fluctuation is transmitted, since the lens 3 and the infrared sensor 4 as the light condensing means are arranged in the isothermal block 14 and the isothermal block 14 is inserted in the probe means 2, the infrared ray The sensor 4 and the isothermal block 14 only fluctuate while maintaining a thermal balance. According to this configuration, the temperature detection accuracy is improved as compared with the second embodiment.

(Embodiment 5) FIG. 7 is a block diagram showing a configuration of a radiation thermometer according to Embodiment 5 of the present invention.

The structure is almost the same as that of the fourth embodiment, except that the reflectivity of the inner surface of the probe means 2 or the outer surface of the isothermal block means 14 which is in contact with the air gap layer is increased. In this embodiment, the inner surface of the probe means 2 or the outer surface of the isothermal block means 14 is smooth-mirror-finished and then plated with gold in order to increase the reflectance with respect to infrared light in the wavelength range detected by the infrared sensor 4. 17 is given, but there is no limitation on the method. With this configuration,
Further, since the temperature fluctuation due to radiation is suppressed with respect to the thermal fluctuation applied from the outside of the probe means 2, the thermal fluctuation to the isothermal block 14 is smaller than in the fourth embodiment, and the infrared sensor 4 and the isothermal block The heat balance between 14 will be maintained.

The reflectivity of both the inner surface of the probe means 2 and the outer surface of the isothermal block means 14 is increased, and the reflectivity for infrared rays in the wavelength range detected by the infrared sensor 4 is made greater than 0.95. By doing so, the above effect can be increased.

According to this configuration, the temperature detection accuracy is further improved as compared with the fourth embodiment.

[0031]

As apparent from the above description, the radiation thermometer of the present invention has the following advantages.

Since the light-collecting means and the infrared sensor are inserted and arranged in the probe means inserted into the ear canal, the inner surface of the probe means and the temperature of the light-collecting means and the infrared sensor are protected against external thermal changes. The change shows almost the same change and no temperature gap occurs. Therefore, even if the temperature is repeatedly measured, the temperature measurement error can be reduced, and the repetition stability can be improved.

Further, since the lens serving as the light condensing means is disposed substantially at the front end of the probe means, there is also an effect for dust prevention.

The lens and the infrared sensor, which are the light condensing means, are unitized by a metallic isothermal block having good heat conductivity and are arranged in the substantially distal end portion of the probe means. Even if thermal change is added from
The inside of the isothermal block shows the same temperature change in terms of temperature, and the thermal balance between the infrared sensor and the isothermal block is maintained, so even if the temperature is repeatedly measured in the ear canal, the accuracy of temperature measurement is further improved Can be done.

Further, even if the light collecting means is a hollow tubular member having a large internal surface reflectance instead of a lens, infrared rays radiated from the vicinity of the eardrum are collected on the infrared sensor while being reflected by the inner surface of the hollow tubular member. However, the reflectivity of the inner surface is set to 0.
Since it is larger than 95, the radiant energy of the inner surface temperature of the hollow tubular member can be suppressed as much as possible,
Further, since the hollow tubular member and the infrared sensor are inserted and arranged in the probe means, even if a thermal change is applied to the probe means from the outside, the temperature gap between the hollow tubular member and the infrared sensor is almost negligible. Is balanced. Therefore, even if the temperature is repeatedly measured at the ear hole, the accuracy of the temperature measurement can be further improved.

Also, since an air gap layer is provided between the inner surface of the probe means and the isothermal block in which the light collecting means and the infrared sensor are stored, the air gap is prevented from being applied to thermal fluctuations applied from outside the probe means. Due to the layer, thermal fluctuations to the isothermal block can be suppressed.

Further, since the reflectivity of the inner surface of the probe means in contact with the air gap layer and the outer surface of the isothermal block is set to be larger than 0.95, temperature fluctuation due to radiation is suppressed with respect to thermal fluctuation applied from outside the probe means. Thermal fluctuations to the isothermal block are further reduced,
In addition, since the heat balance between the infrared sensor and the isothermal block is maintained, the accuracy of the temperature detection is further improved.

[Brief description of the drawings]

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

FIG. 2 is a temperature change diagram of the radiation thermometer.

FIG. 3 is a diagram showing a stereoscopic viewing angle of an infrared sensor of the radiation thermometer.

FIG. 4 is a configuration block diagram of a radiation thermometer according to a second embodiment of the present invention.

FIG. 5 is a configuration block diagram of a radiation thermometer according to a third embodiment of the present invention.

FIG. 6 is a configuration block diagram of a radiation thermometer according to a fourth embodiment of the present invention.

FIG. 7 is a configuration block diagram of a radiation thermometer according to a fifth embodiment of the present invention.

FIG. 8 is an external view of a conventional radiation thermometer.

[Explanation of symbols]

 2 Probe means 3 Lens (light collecting means) 4 Infrared sensor 14 Isothermal block 15 Hollow tubular member (light collecting means) 16 Air gap layer

Claims (8)

[Claims] 1. A probe means inserted into an ear canal of a human body;
A light collecting means for collecting infrared light radiated from the vicinity of the eardrum through the probe means, and an infrared sensor for detecting infrared light collected by the light collecting means, wherein the light collecting means and the infrared sensor A radiation thermometer mounted in the probe means. 2. A radiation thermometer according to claim 1, wherein said light condensing means comprises a lens and is disposed substantially at a tip of said probe means. 3. The radiation thermometer according to claim 1, wherein the light condensing means is a hollow tubular member having an inner surface having a reflectivity greater than 0.95 for infrared rays in a wavelength region detected by the infrared sensor. . 4. The radiation thermometer according to claim 1, wherein the lens and the infrared sensor, which are the light condensing means, are enclosed in the isothermal block means for making their temperatures uniform, and are mounted on the probe means. 5. The radiation thermometer according to claim 4, further comprising an air gap layer between the probe means and the isothermal block means. 6. The radiation thermometer according to claim 5, wherein the reflectance of the inner surface of the probe means or the outer surface of the isothermal block means which is in contact with the air gap layer is larger than 0.95. 7. The radiation thermometer according to claim 2, wherein the lens is a flat lens utilizing a diffraction effect. 8. The radiation thermometer according to claim 1, wherein the infrared sensor is a thin-film pyroelectric sensor.