JPH08254466A - Radiation thermometer - Google Patents

Abstract

PURPOSE: To provide a low-cost radiation thermometer which is constructed in a small size so as to be portable, with which the temp. sensing accuracy as a thermometer is well maintained by correcting the sensitivity data of an infrared sensor on the basis of the temp. sensing data. CONSTITUTION: A radiation thermometer is used as a physical temp. meter upon inserting a probe 16 into an external ear hole of a person as testee. The structure comprises an infrared sensor 3a, light guide tube 20, and hard cap 21 which are coupled together by a metal housing 19 having good thermal conductivity, and therefore, a good heat balance is ensured at all times, and the temp. made common is sensed by a temp. sensor 3b. A sensing signal processing means emits the infrared data and temp. sensing data digitized on the basis of the electric signal given by the infrared sensor 3a and temp. sensor 3b. A sensitivity correction calculating means makes correction of the sensitivity data of the infrared sensor 3a on the basis of the temp. sensing data, while a temp. calculating means emits the temp. data of the object to be measured on the basis of the infrared data, temp. sensing data, and sensitivity data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation thermometer, and more particularly to a radiation thermometer system that does not use a preheating device in its main body.

[0002]

2. Description of the Related Art As a thermometer, for example, a pen-type electronic thermometer has recently become popular in place of a glass thermometer.

The characteristics of this electronic thermometer are that it does not break, is easy to read, and has a buzzer for the end of temperature measurement, but the time required for temperature measurement is about 5 to 10 minutes, which is almost the same as the glass thermometer. This is the reason why the temperature measurement is troublesome. This has a problem in the method of inserting the sensor unit into the armpit or the mouth and bringing it into contact with the measurement site for measurement, and there are two reasons why the measurement time is long.

First, the skin temperature under the armpit and the mucous membrane temperature in the mouth are lower than the body temperature before the start of the temperature measurement, and the body temperature is gradually approached by closing the armpit or the mouth.

Second, the thermometer sensor unit is cooled to the ambient temperature, and when it is inserted into the measurement site, the temperature of the measurement site is further lowered, and it takes time to equilibrate to the original body temperature.

This state will be described with reference to FIG.

FIG. 14 is a temperature measurement curve of a contact type electronic thermometer in which the horizontal axis represents the temperature measurement time and the vertical axis represents the measurement temperature. H is the armpit temperature curve as the measurement site and M is the measurement temperature curve of the thermometer. is there.

That is, at t ₁ at the start of temperature measurement, the skin temperature under the armpit is 36 ° C. or lower, and the temperature of the thermometer sensor unit is also cooled to 30 ° C. or lower. The state from the close axillary by inserting the thermometer sensor unit to underarm measured temperature M of the thermometer sensor section gradually increases rapidly, but the temperature H underarm until t ₂ by being cooled by the thermometer sensor unit After processing, it begins to rise towards true body temperature. When the sensor part of the thermometer is heated to the armpit skin temperature, the point t
_{From 3 on} , the two temperature curves H and M rise in agreement, but it takes about 5 to 10 minutes to rise to the true body temperature as mentioned above.

As is well known, the actual body temperature measuring method is to measure at a constant interval from the time point t ₁ , compare the measured values and store the maximum value in sequence.
The difference between the measured values is determined, and when the difference between the measured values becomes smaller than a predetermined value, the temperature measurement is stopped at the point t ₄ , and at the same time, the maximum value at that time is displayed as the body temperature. (For example, JP-A-50-31888).

Considering the conditions for performing the body temperature measurement in a short time in consideration of the first and second reasons, a site where the body temperature is selected before starting the temperature measurement is selected and the sensor is cold. If the measurement can be performed without contacting with each other, the measurement can be performed in a short time.

Therefore, a radiation thermometer has been proposed in which the eardrum is selected as the body temperature region before the temperature measurement is started, and the temperature of the region is measured in a non-contact manner (for example, Japanese Patent Laid-Open Publication No. Sho 6-66).
No. 1-117422).

Next, the principle of the radiation thermometer, which is the basis of the radiation thermometer, will be described. "All objects are
Infrared radiation is emitted from the surface, and the amount of infrared radiation energy and spectral characteristics are determined by the absolute temperature of the object, and also depend on the properties of the object and the finished surface condition. 』It is based on this law of physics. The law showing this will be explained.

First, Planck's law expresses the relationship between the radiation intensity, spectral distribution, and temperature of a black body.

[0014]

[Equation 1] FIG. 15 illustrates the Planck's law. It can be seen that the radiant energy increases as the blackbody temperature increases. Further, it can be seen that the radiant energy changes depending on the wavelength, and the peak value of the distribution shifts to the short wavelength side as the temperature rises, but it radiates over a wide wavelength band.

The total energy emitted from the black body is given by Eq. (1) with respect to W (λ, T) for λ from λ = 0 to λ =
It is obtained by integrating to ∞. This is the Stefan-Boltzmann law.

[0016]

[Equation 2] As is clear from the equation (2), the total radiant energy W ₁ is proportional to the fourth power of the absolute temperature T of the black body light source. Also,
It should be noted that the formula (2) is a formula obtained by integrating infrared radiation emitted from a black body over all wavelengths.

All of the above rules have been derived for a black body with an emissivity of 1.00. However, in reality, most objects are not perfect radiators, and their emissivity is 1.00
Less than. Therefore, it is necessary to correct by multiplying by the emissivity. Therefore, the radiant energy W ₂ of most objects that are not black bodies can be expressed by equation (3).

[0018]

(Equation 3) Equation (3) represents the infrared radiation energy emitted from the object and incident on the infrared sensor, but the infrared sensor itself also emits infrared radiation according to the same law. Therefore, if the temperature of the infrared sensor itself is T ₀ , it means that the energy of σT ₀ ⁴ is radiated in the infrared, and the energy W obtained by subtracting the radiation from the incidence is given by the equation (4).

W = σ (εT ⁴ + γTa ⁴ −T ₀ ⁴ ) ... (4) Ta: ambient temperature of the object γ: reflectance of the object Since the transmittance of the object to be measured can be regarded as zero, γ = 1−ε holds. .

In the equation (4), it is assumed that the infrared sensor is ideally made and the emissivity of the infrared sensor is 1.00.

If the infrared sensor is left in the environment of the ambient temperature Ta for a long time and the infrared sensor temperature T ₀ is equal to the ambient temperature Ta, the equation (4) is expressed by the equation (5). become.

W = σ (εT ⁴ + γT ₀ ⁴ −T ₀ ⁴ ) = εσ (T ⁴ −T ₀ ⁴ ) ... (5) FIG. 18 is a basic configuration diagram of a conventional radiation thermometer. The configuration will be described.

The radiation thermometer 7 is composed of an optical system 2, a detector 3, an amplifier 4, an arithmetic unit 5, and a display device 6.

The optical system 2 comprises a condenser 2a for efficiently condensing infrared radiation from the object L to be measured and a filter 2b having a transmission wavelength characteristic. The light collecting means 2a is a cylinder whose inner surface is plated with gold. Also filter 2
A silicon filter is used for b.

The detector 3 comprises an infrared sensor 3a and a temperature sensor 3b. The infrared sensor 3a converts infrared radiation energy obtained by subtracting radiation from the infrared sensor 3a itself from incidence of infrared radiation energy collected by the optical system 2 into an electric signal, that is, an infrared voltage Vs. Further, the temperature sensor 3b is arranged in the vicinity of the infrared sensor 3a in order to measure the temperature T ₀ of the infrared sensor 3a and its vicinity, and outputs the temperature sensitive voltage Vt. A thermopile is used for the infrared sensor 3a, and a temperature-sensitive diode such as a thermistor is used for the temperature-sensitive sensor 3b.

The amplification section 4 includes an infrared sensor 3a, that is, an amplification circuit for amplifying the infrared voltage Vs which is the output of the thermopile, and A / A for converting the output voltage of the amplification circuit into digitized infrared data Vd. An infrared amplifier 4a composed of a D converter circuit, a temperature sensor 3b, that is, an amplifier circuit for amplifying a temperature-sensitive voltage Vt which is a forward voltage of the temperature-sensitive diode, and an output voltage of the amplifier circuit are digitized. The temperature-sensitive amplifier 4b includes an A / D conversion circuit for converting the temperature-sensitive data T ₀ .

Then, the two signals V from the amplifier 4 are
d and T ₀ are converted into temperature data T by the calculation unit 5 and displayed on the display device 6. Here, the calculation unit 5 sets the emissivity ε of the measured object L to the emissivity input means 5a.
And an arithmetic circuit 5c for performing an operation based on the equation (5).

With the above configuration, the temperature of the object to be measured L can be measured by the non-contact method, but how it operates will be described.

First, the measured object L radiates infrared rays,
The wavelength spectrum distribution covers a wide wavelength range as shown in FIG. The infrared radiation is collected by the light collecting means 2a.
Is condensed by the filter 2, passes through the filter 2b having a transmission wavelength characteristic, and reaches the infrared sensor 3a.

In addition, there is infrared radiation energy that reaches the infrared sensor 3a. First, infrared radiation is radiated from an object around the object L to be measured, which is the object L to be measured.
It is the infrared radiant energy that reaches after passing through the filter 2b after being reflected by. In addition, infrared radiation is radiated from the infrared sensor 3a or an object in the vicinity of the infrared radiation, which is reflected by the filter 2b and reaches the infrared radiation energy, and infrared radiation energy which is reached by the infrared radiation from the filter 2b. is there.

The infrared radiant energy from the infrared sensor 3a can be expressed by equation (3). However, ε =
Set to 1.00. That is, measuring the temperature of the infrared sensor 3a itself indirectly measures the infrared radiation energy from the infrared sensor 3a. Therefore, the temperature sensor 3b is arranged in the vicinity of the infrared sensor 3a, and the infrared sensor 3b
A and its surrounding temperature T ₀ are measured.

Then, the infrared sensor 3a converts the infrared radiant energy W obtained by subtracting the radiated infrared radiant energy from the incident infrared radiant energy into an electric signal. Infrared sensor 3
Since a uses a thermopile, the infrared voltage Vs proportional to the infrared radiation energy W is output.

Here, the infrared voltage Vs, which is the output voltage of the infrared sensor 3a, is the infrared radiation energy W per unit area.
And sensitivity R is multiplied by the product of the light receiving area S of the infrared sensor 3a. Further, the infrared data Vd, which is the output voltage of the infrared amplifier 4a, is obtained by multiplying the infrared voltage Vs of the infrared sensor 3a by the amplification factor A of the infrared amplifier 4a.

Vs = R · W · S Vd = A · Vs Since the above relationship holds, the equation (5) can be expressed as the equation (6).

Vd = ε · σ SRA (T ⁴ −T ₀ ⁴ ) (6) Vd: Output voltage of infrared amplifier 4 a S: Light receiving area of infrared sensor 3 a R: Sensitivity of infrared sensor A: Infrared amplifier Amplification factor of 4a In general, K ₁ = σSRA is set and the equation (6) is rearranged to calculate the temperature T of the measured object L based on the equation (7).

[0036]

[Equation 4] However, the thermal infrared sensor itself used in the conventional radiation thermometer has no wavelength dependence, but a silicon filter or a quartz filter is used as a window material on the front surface of the can package in which the infrared sensor is mounted. Transparent material such as. This is because infrared radiation from an object has a wavelength spectrum distribution as shown in FIG. 15, so that only the wavelength band that is mainly radiated is transmitted and the influence of external light is reduced. is there. Each of the transparent materials has a unique transmission wavelength characteristic, and an appropriate transparent material is selected depending on the temperature of the object to be measured, the workability of the transparent material, the price of the material, and the like.

FIG. 16 illustrates the transmittance of a silicon filter which is one of the transparent materials. It can be seen that the silicon filter shown in FIG. 16 transmits only the wavelength band of about 1 to 18 [μm]. The transmittance is about 54%.

As described above, the infrared sensor with a filter itself is a thermal type and has no wavelength dependence, but has a wavelength dependence that allows only a specific wavelength band to be transmitted by a filter which is a window material.

Therefore, the formula (5) obtained by integrating the infrared radiant energy input to the infrared sensor with a filter for all wavelengths is valid for the infrared sensor with a filter that transmits only a specific wavelength band. This means that there will be no error, and the error will be included.

Further, in the conventional structure, the sensitivity R of the infrared sensor is treated as a constant, but the actual sensitivity R of the infrared sensor fluctuates depending on the infrared sensor temperature T _0. The state is shown in FIG.

That is, in FIG. 19, the output voltage Vs of the thermopile used as the infrared sensor is actually measured using a black body to obtain the sensitivity R, and the infrared sensor temperature T ₀ is changed to detect the sensitivity at each temperature. The change in R is plotted. As a result, it was found that the temperature dependence of the sensitivity R can be approximated to a straight line as shown in the equation (8).

R = α {1 + β (T ₀ −T _m )} (8) Here, α is the sensitivity R that serves as a reference when T ₀ = T _m . T _m is a representative temperature of the infrared sensor temperature, for example,
For example, the infrared sensor temperature when measuring the infrared sensor sensitivity in the factory. β represents the degree of fluctuation and is 1 [deg]
The fluctuation rate was about -0.3 [% / deg].

As a matter of course, the fluctuation of the sensitivity R as described above causes an error.

The above-mentioned fluctuation rate β depends on the manufacturing conditions of the thermopile and can be reduced by increasing the purity and the processing accuracy, but in the case of a commercially available thermopile considering mass productivity. It becomes the above value.

However, the usual radiation thermometer is intended for measuring high temperatures, and its measuring range is 0 to 300.
Since the measurement accuracy is about ± (2 to 3) ° C., the error due to the filter characteristics, the sensitivity variation of the infrared sensor, etc. can be ignored and the countermeasure is omitted.

Considering the measurement conditions of the thermometer, the temperature measuring range may be as narrow as 33 ° C. to 43 ° C., but the temperature measuring accuracy is required to be ± 0.1 ° C.

Therefore, when the radiation thermometer is used as, for example, a thermometer, it is necessary to improve the temperature detection accuracy by taking some measures against an error due to the filter characteristic, the sensitivity variation of the infrared sensor and the like.

As a countermeasure against this, the above-mentioned Japanese Patent Laid-Open No. 61-1174
The radiation thermometer disclosed in No. 22 has the following system.

That is, the probe unit has an infrared sensor, the chopper unit has a target, and the charging unit has three units.

Then, heating control means for preheating the infrared sensor and the target to the reference temperature (36.5 ° C.) of the external ear canal is provided, and the heating control means is driven by the charging energy from the charging unit. There is.

When measuring the body temperature, the probe unit is set in the chopper unit, and the heating control means calibrates the probe having the infrared sensor and the target in a preheated state. After that, the probe unit is removed and removed. Body temperature is measured by inserting infrared light into the ear canal, detecting infrared radiation from the eardrum, and comparing it with infrared radiation from the target.

Next, the reason why the temperature detection accuracy is improved by the above method will be described.

This system eliminates various error factors by preheating the probe having the infrared sensor and the target to the reference temperature (36.5 ° C.) close to the normal body temperature by the heating control means. .

That is, by heating the probe to a reference temperature higher than room temperature, the infrared sensor is kept at a constant temperature regardless of the ambient temperature, so that the sensitivity variation of the infrared sensor disappears and the error can be ignored. In addition, the calibration is performed by setting the body temperature to be measured and the reference temperature of the target close to each other, and then the comparative measurement is performed so that the error due to the filter characteristic can be ignored.

Further, since the probe is preheated to a temperature close to the body temperature, when the conventional cold probe is inserted into the ear canal, the temperature of the ear canal and the eardrum is lowered by the probe, and the correct body temperature cannot be measured. The problem is also solved.

[0056]

However, the above-mentioned Japanese Patent Laid-Open No.
Although the radiation thermometer disclosed in JP-A 1-117422 is extremely excellent in terms of accuracy of temperature measurement, on the other hand, it requires a heating control device with high control accuracy, which complicates its structure and circuit configuration and increases cost. There is a problem of becoming. Also, a long stabilization time was required to preheat the probe and target and control them to a constant temperature. Furthermore, since the energy for driving the heating control device is relatively high power, the result is that the shape is large and a charging unit having a power cord is required. Therefore, in a portable thermometer using a small battery as an energy source, It can be said that it is impossible to adopt this method.

An object of the present invention is to solve the above problems by providing a radiation thermometer which maintains the temperature measuring accuracy as a thermometer and is portable and downsized at low cost.

[0058]

The summary of the present invention for achieving the above object is as follows.

That is, according to the present invention, an infrared sensor that receives heat radiation from an object to be measured and outputs an electric signal, and a sensor that measures the temperature of the infrared sensor and its surroundings and outputs an electric signal. A temperature sensor, detection signal processing means for outputting infrared data and temperature sensitive data digitized based on electric signals from the infrared sensor and the temperature sensitive sensor; and the infrared sensor based on the temperature sensitive data. And a temperature calculation means for calculating temperature data of the object to be measured based on the infrared data, the temperature sensitive data, and the sensitivity data.

Therefore, according to the present invention, even when the sensitivity of the infrared sensor changes with temperature, it is possible to surely correct this sensor sensitivity error and perform accurate temperature measurement.

Further, according to the present invention, the sensitivity correction calculation means calculates the sensitivity data R by the following formula: R = α {1 + β (T ₀ −T _m )} T ₀ : Temperature sensitive data of the temperature sensitive sensor T _m : temperature during sensitivity adjustment α: sensitivity at temperature T _m β: rate of change of sensitivity.

Therefore, according to the present invention, the sensor sensitivity correction described above can be performed reliably and easily.

[0063]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Basic Example) FIG. 11 is a basic configuration block diagram showing a basic example of a radiation thermometer according to the present invention. In this basic example, the sensitivity R is improved by using a thermopile with good manufacturing conditions. This is a basic example in which fluctuations can be ignored and the filter characteristics are corrected.

In FIG. 11, the same reference numerals as those in FIG. 18 indicate the same components, and the description thereof will be omitted. The difference from FIG. 18 lies in that the temperature of the eardrum of the ear as the measured object L is measured and the calculation unit 5 is described below.

The calculation unit 5 in the radiation thermometer 70 has an emissivity input means 5a for setting the emissivity ε of the object L to be measured,
It is composed of a filter correction means 5b for setting information on the transmission wavelength characteristic of the filter 2b and a temperature calculation circuit 5c.

Therefore, the calculation section 5 calculates the measured temperature Tb based on the emissivity set value from the emissivity input means 5a and the filter correction value from the filter correction means 5b.

First, a temperature calculation formula considering the wavelength dependence of the infrared sensor with a filter according to this basic example will be described.

As described above, the infrared sensor 3a converts the infrared radiant energy W obtained by subtracting the radiation from the incident into the infrared voltage Vs, but the energy W is expressed by the equation (9).

[0070]

(Equation 5) The first term of the equation (9) is energy that is radiated from the measured object L having the emissivity ε by infrared radiation and reaches through the filter.
The second term is the energy radiated from the surrounding object at the temperature T ₀ , reflected by the measured object L, transmitted through the filter 2b and reached. The third term is infrared radiation from the infrared sensor 3a at the temperature T ₀ or an object in the vicinity thereof, and the filter 2b
Is the energy that is reached by being reflected by the filter or the infrared radiation emitted from the filter 2b at the temperature T ₀ . Here, there is a relationship that "for a transmissive material, the sum of the transmissivity, the reflectivity, and the emissivity is equal to 1.", and the third term is a term in consideration of the reflection or radiation by the filter 2b. Also note that this reflection reflects the infrared radiation from the infrared sensor 3a side by the filter 2b. Finally, the fourth term is the energy radiated from the infrared sensor 3a itself at the temperature T ₀ , and the negative sign is negative.

Equation (9) can be rewritten as equation (10).

[0072]

(Equation 6) That is, the infrared radiant energy W obtained by subtracting the radiation from the incidence on the infrared sensor 3a having the filter 2b is "proportional to the difference of the fourth power of the absolute temperature" as in the equation (5). It has been found that the equation must be one that takes into consideration the transmission wavelength characteristic of the filter 2b as in equation (10). In other words, a new equation is needed to replace the Stefan-Boltzmann law shown in equation (2).

Therefore, if infrared radiation energy that is radiated from a black body at an absolute temperature T and that passes through a filter having a transmittance η (λ) is F (T), it can be expressed as in equation (11).

[0074]

(Equation 7) Here, the temperature range of the absolute temperature T is changed from Tmin to Tmax.
, An arbitrary absolute temperature T _{1 of} the section,
Table 1 summarizes the calculation results obtained by calculating the equation (11) for T ₂ , T ₃ ... T _n .

[0075]

[Table 1] Therefore, how the relation between the absolute temperature T and the infrared radiant energy F (T) transmitted through the filter shown in Table 1 is related to Stefan-Boltzmann's law was examined. FIG. 17 is a graph showing the examination process. It will be described with reference to FIG.

The horizontal axis of the graph is absolute temperature, the unit is [K], and the vertical axis is radiant energy, and the unit is [W / cm ² ]. The curve A in FIG. 17 is the characteristic curve of the equation (2) indicating the Stefan-Boltzmann law, and the curve B is the characteristic curve of this basic example in consideration of the filter characteristic.

The curve B is the absolute temperature T ₁ to
Blot each point in T _n to create curve B ',
The curve A is deformed and moved to be superposed on the curve B ′. The types of the deformation and movement are the coefficient a of the quartic term of the curve A, the movement amount b in the horizontal axis direction, and the vertical axis direction. It has become possible to superimpose them by selecting the moving amount c of.

From this result, the equation (11) was approximated to the equation (12) using the three kinds of set values a, b, and c.

F (T) = a · (T−b) ⁴ + c (12) Then, from the values shown in Table 1, a shown in the equation (12),
The optimum values of b and c are obtained by a method such as the least square method,
Substituting this value into equation (12) gives an approximate equation.

Here, regarding a, b, and c, Stefan ·
The explanation will be given in comparison with the equation (2) which is Boltzmann's law.

A is a coefficient of the fourth-order term of the absolute temperature T, which corresponds to the Stefan-Boltzmann constant σ of the curve A, the unit is [W / cm ² · deg ⁴ ], and b is the symmetry axis temperature. In curve A, the absolute temperature is 0 [K], but in curve B, the absolute temperature b [K] is the axis of symmetry.

C indicates the minimum value, which is 0 [W / cm ² ] in the curve A, but C [W / cm ² ] in the curve B.
cm ² ] is the offset.

Then, using the above approximate expression (12), (1
Rewriting equation (0) yields equation (13).

W = ε [a · (T−b) ⁴ + c] −ε [a · (T ₀ −b) ⁴ + c] = ε · a [(T−b) ⁴ − (T ₀ −b) ⁴ ] (13) As can be seen from the equation (13), the minimum value c is canceled.

Here, the infrared data Vd by the infrared rays radiated from the eardrum is K ₂ = aSRA by the light receiving area S of the infrared sensor 3a, the sensitivity R, and the amplification factor A of the infrared amplifier 4a.
In other words, the equation (13) becomes the equation (14), and the body temperature Tb by the eardrum is calculated by the equation (15) based on the equation (14).

[0086]

(Equation 8) That is, when a filter having a transmission wavelength characteristic is used as an optical system member, "the infrared radiation energy is the absolute temperature T
It is proportional to the fourth power of. It is necessary to perform the calculation based on the equation (14) that "the infrared radiant energy is proportional to the fourth power of (absolute temperature T-symmetry axis temperature b)." is there.

From this result, the symmetry axis temperature b is output from the filter correction means 5b shown in FIG. 11, and the arithmetic circuit 5c calculates the measured object L, that is, the body temperature Tb of the eardrum based on the equation (15). .

Next, an approximate expression considering the silicon filter actually used as the filter 2b will be described.

FIG. 16 shows the transmission wavelength characteristic of the silicon filter.
However, in order to simplify the calculation, “the transmission wavelength band of the silicon filter is 1 to 18 [μm] and the transmittance is 54 [%]. ]

[0090]

[Equation 9] Calculation is performed by substituting the expression (1) for W (λ, T).

Further, since the measuring environment and the measuring temperature range of the object to be measured are within the range of 0 [° C.] to 50 [° C.],
Tmin was 273 [K] and Tmax was 323 [K]. Table 2 shows the calculation results of equation (16).

From the data shown in Table 2, a, b and c when approximated to the equation (12) are obtained by the least square method.

A = 4.104 × 10 ⁻¹² [W / cm ² · deg ⁴ ] b = 45.96 [K] c = −6.144 × 10 ⁻⁴ [W / cm ² ] That is, the value obtained here The coefficient a of the fourth-order term and the symmetry axis temperature b
Is a value showing the transmission wavelength characteristic of the silicon filter, and the coefficient a of the quartic term and the value of the symmetry axis temperature b are output from the filter correction means 5b. The filter correction means 5b is a part of the arithmetic program memory of the arithmetic unit 5, and the coefficient a of the quartic term and the symmetry axis temperature b are written therein.

[0094]

[Table 2] That is, when the silicon filter is used as the window material for the measurement of the infrared sensor, the temperature T of the object to be measured is not calculated by the equation (5), but by the formula (5).
By calculating with the equation (14), it is possible to perform highly accurate temperature calculation.

As is clear from the above description, according to this embodiment, even if a transparent material having a transmission wavelength characteristic is used as the window material of the infrared sensor, the temperature of the object to be measured can be measured with high accuracy. You can

Further, even when the material of the transparent material which is the window material of the infrared sensor is changed, the temperature can be measured with high accuracy by rewriting the value of the filter correction means 5b which is a part of the program memory.

In this basic example, the approximation formula of the quartic term like the formula (12) is adopted as a new formula replacing the Stefan-Boltzmann law. However, as shown in FIG. Since only a part of the curve like Tmax is used, it is not always necessary to approximate the fourth-order term, and even if it is approximated by an appropriate higher-order expression, the accuracy as a thermometer can be sufficiently obtained. Expression (14) ′ can also be adopted as the expression.

Vd = εK ′ ₂ {(Tb−b ′) ² − (T ₀ −b ′) ² } ... (14) ′ (First Embodiment) Next, as the first embodiment of the present invention, mass productivity is obtained. A specific configuration of the radiation thermometer actually manufactured by using a commercially available thermopile in consideration of the above will be described. In practice, the radiation thermometer of this embodiment is used as a thermometer.

2 and 3 are a rear view and a side view of the radiation thermometer in this embodiment. Reference numeral 1 denotes a radiation thermometer, which is composed of a main body portion 10 and a head portion 11, a display device 6 for displaying temperature on the back surface of the main body portion 10, a check button 12 having a push button structure on the front surface, and a side surface. A power switch 13 having a slide structure and measure buttons 14 and 15 having a push button structure are provided in the.

Further, the head portion 11 is provided so as to project from the end portion of the main body portion 10 in a "dogleg shape", and the tip of the head portion 11 is the probe 16, and the probe 1
Reference numeral 6 is composed of the optical system 2 and the detector 3 shown in FIG.

This optical system is provided with a condensing means for condensing infrared radiation from the object to be measured and a filter having a transmission wavelength characteristic.

The operation method of the radiation thermometer 1 is to perform a check operation described later in a state in which the power switch 13 is turned on, and then, while inserting the probe 16 into the ear canal of the subject, the measure button 14 is inserted. , 15 is turned on, the temperature measurement is instantly completed, and the result is displayed on the display device 6 as the temperature.

FIG. 4 is a sectional view of the head portion 11,
The case bodies 17 and 18 are made of a resin molded body having extremely low thermal conductivity. And the probe 1 of the case body 17
The portion forming 6 is a cylindrical tube portion 17a, and a metal housing 19 made of a metal such as aluminum which is lightweight and has good heat conductivity is fitted to the tube portion 17a. The metal housing 19 has a cylindrical portion 19a, a hollow portion 19b communicating with the cylindrical portion 19a, and a recess 19c for embedding the temperature sensitive element.
And a base portion 19d provided with
A step portion 19e for mounting a filter is provided at the tip of 9a. A light guide tube 20 having a gold (Au) plating on the inner circumference of a brass (Bu) pipe is fitted to the cylindrical portion 19a, and infrared rays are selectively passed through the stepped portion 19e at the tip and a dustproof function is provided. The hard cap 21 it has is fixed. Further, a thermopile as the infrared sensor 3a is embedded in the hollow portion 19b of the base portion 19d, and the temperature sensor 3b is embedded in the recess 19c by sealing resins 22 and 23, respectively.

The infrared sensor 3a and the temperature-sensitive sensor 3b are connected to the wiring pattern of the circuit board 26 by lead wires 24 and 25, respectively, and led to an amplifier circuit described later.

According to the above structure, since the infrared sensor 3a, the light guide tube 20 and the hard cap 21 are connected by the metal housing 19 having good heat conductivity, a heat balance is always obtained and the heat balance is made common. The temperature is detected by the temperature sensor 3b.

Reference numeral 28 denotes a temperature detecting cover which is detachably attached to the probe 16, is made of a resin having poor heat conductivity, and the tip end portion 28a is made of a material which transmits infrared rays.

FIG. 5 is an enlarged cross-sectional view of the tip portion of the probe 16, which prevents the tip portion 28a of the thermometric cover 28 from covering the tip of the probe 16 so that the probe 16 will not come into contact with the inner wall of the external ear canal. are doing.

FIG. 6 shows a case 30 for storing the radiation thermometer 1.
FIG. 3 is a side view showing a state in which the storage case 30 is mounted on the storage case 30. The storage case 30 is provided with a mounting portion 30a for mounting the main body portion 10 and a storage portion 30b for storing the probe 16.
A reflection plate 31 is fixed to a position corresponding to the tip of the probe 16 on the bottom surface 30c of the housing portion 30b.

Further, the storage case 30 is provided with a button pressure-responsive portion 30d at a position corresponding to the check button 12. When the radiation thermometer 1 is set in the storage case 30 as shown in FIG. 6 with the power switch 13 turned on, the tip of the probe 16 is set in the reflection plate 31 and the check button is pressed by the button pressure-sensitive portion 30d. 12 is turned on. This state is a function check state which will be described later, and it can be known from the display state of the display device 6 whether or not temperature measurement is possible.

FIG. 7 is a sectional view of the ear showing a state where the radiation thermometer 1 measures the temperature. Reference numeral 40 is an auricle, 41 is an outer ear canal, and 42 is an eardrum. Many downy hairs 43 grow on the inner wall. Earwax 44 may accumulate on the inner wall of the outer ear canal 41.

As shown, the probe 16 of the radiation thermometer 1
The temperature can be instantaneously measured by inserting into the external ear canal 41 and pressing the measure buttons 14 and 15 with the tip end facing the eardrum 42.

FIG. 1 is a block diagram of the radiation thermometer 1 shown in FIG. 2. The same members as those in FIG. 11 are designated by the same reference numerals and the description thereof will be omitted.

A portion different from that of FIG. 11 will be described. Reference numeral 50 denotes a detection signal processing unit, which corresponds to the amplification unit 4 shown in FIG. 11 and has a specific configuration. That is, the infrared amplifier circuit 5 for amplifying the infrared voltage Vs output from the infrared sensor 3a.
1. A temperature-sensitive amplifier circuit 52 for amplifying the temperature-sensitive voltage Vt output from the temperature-sensitive sensor 3b, and a peak hold circuit 5 for holding the peak value of the output voltage Vs of the infrared amplifier circuit 51.
3. The output voltage Vs of the infrared amplifier circuit 51 and the output voltage Vsp of the peak hold circuit 53 are input to the input terminals I ₁ and I ₂ , respectively, and the output terminal 0 according to the condition of the control terminal C.
Output from the temperature-sensitive amplifier circuit 52, and a switching circuit 54 for selectively outputting from the A / D conversion circuit 55 that converts the infrared voltage Vs or Vsp output from the switching circuit 54 into digitized infrared data Vd. The infrared voltage Vs and the temperature-sensitive voltage V that are input from the detection unit 3 are included in the A / D conversion circuit 55 that converts the voltage Vt into digitized temperature-sensitive data T _0.
Infrared data Vd and temperature-sensitive data T ₀ that are obtained by digitizing t
Converted to and output.

The calculation unit 60 corresponds to the calculation unit 5 of FIG. 11, but includes a temperature calculation circuit 61 corresponding to the emissivity input unit 5a, the filter correction unit 5b, and the calculation circuit 5c.
Temperature data Tb calculated by the temperature calculation circuit 61
_The infrared data Vd output from the display drive circuit 62 and the detection signal processing unit 50 for inputting ₁ to display the temperature on the temperature display unit 6a of the display device 6 and the infrared data Vd are input.
When the zero is detected to be zero, the zero detection circuit 63 for outputting the detection signal S ₀ to turn on the measurement permission mark 6b of the display device 6, and the temperature sensing output from the detection signal processing unit 50. A sensitivity correction calculation circuit 64 for inputting the data T ₀ and calculating and outputting the sensitivity R according to the equation (8) shown in FIG. 19, and a light receiving area of the infrared sensor 3a shown in the equation (6). Sensitivity data input means 65 for outputting a value input and set from the outside as sensitivity data D based on S and the amplification factor A of the infrared amplification circuit 51.

Reference numeral 90 denotes a switch circuit, which is connected to the measure switch SWm operated by the measure buttons 14 and 15 and the check switch SWc operated by the check button 12 shown in FIG. Measure switch SW when pressed
When m is turned on, the measure signal Sm is output from the M terminal.

When the radiation thermometer 1 is set in the storage case 30 as shown in FIG. 6, the check button 12 is pressed to turn on the check switch SWc, and the check signal Sc is output from the C terminal.

The measure signal Sm output from the M terminal of the switch circuit 90 is supplied to the enable terminals E of the temperature calculation circuit 61 and the sensitivity correction calculation circuit 64, thereby setting both circuits in the calculation mode. The zero detection circuit 63 is reset.

The check signal Sc output from the C terminal of the switch circuit 90 is supplied to the enable terminal E of the zero detection circuit 63, the control terminal C of the switching circuit 54, and the reset terminal R of the peak hold circuit 53.

Next, the operation of the radiation thermometer 1 having the above structure will be described.

First, in the initial state in which the power switch 13 of the radiation thermometer 1 shown in FIG. 2 is turned on, both the check switch SWc and the major switch SWm are off, so the check signal from the switch circuit 70 is sent. Neither Sc nor major signal Sm is output.

As a result, the arithmetic unit 60 is operated by the temperature arithmetic circuit 6
1 and the sensitivity correction calculation circuit 64 are set to the non-calculation mode,
The zero detection circuit 63 is also set to the non-operation mode.

The switching circuit 54 of the detection signal processing unit 50 is I
_The voltage Vsp input to the _two terminals is selectively output to the output terminal 0, and the peak hold circuit 53 is released from the reset state and is in the operating state. The above is the initial state, and the function check mode will be described next.

When the radiation thermometer 1 is attached to the storage case 30 as shown in FIG. 6, the check button 12 is pressed against the button pressing portion 30d of the storage case 30 to turn on the check switch SWc of FIG. The tip of the probe 16 is set at the position of the reflection plate 31.

As a result, the switch circuit 90 of FIG. 1 outputs the check signal Sc from the C terminal when the check switch SWc is turned on, and the peak hold circuit 5
3, the switching circuit 54, and the zero detection circuit 63. By supplying the check signal Sc, the detection signal processing unit 50 resets the peak hold circuit 53 and, at the same time, the switching circuit 54 causes the voltage Vs supplied to the input terminal I _1.
Is switched to the output terminal 0 for selective output, and the A /
The D conversion circuit 55 digitally converts the infrared voltage Vs and outputs infrared data Vd.

In the calculation section 60, the temperature calculation circuit 61 and the sensitivity correction calculation circuit 64 are set in the non-calculation mode, and only the zero detection circuit 63 is in the operating state. The above is the state of each part in the function check mode. In the operation of the radiation thermometer 1 in this function check mode, the infrared rays reflected by the reflection plate 31 are reflected by the infrared sensor 3a and the infrared amplification circuit 5.
1, the infrared data Vd converted by the switching circuit 54 and the A / D conversion circuit 55 is determined by the zero detection circuit 63. If the infrared data Vd is zero, the zero detection circuit 63 outputs the detection signal S to the output terminal 0. ₀ is output and the measurement permission mark 6b of the display device 6 is turned on.

The contents of the function check mode will now be described.

As described above, in FIG. 4, the infrared sensor 3a, the light guide tube 20, and the hard cap 21 are connected by the metal housing 19 having good heat conductivity to obtain heat balance. Yes, the function check is a mode for confirming that the heat balance is good.

That is, the infrared radiant energy emitted from the light guide tube 20 and the hard cap 21 at the temperature T is reflected by the reflecting plate 31 and enters the infrared sensor 3a. The infrared radiant energy is also radiated from the infrared sensor 3a at the temperature T _0. The energy W of the difference obtained by subtracting the radiation from this incident is W = εσ (T ⁴ −T as shown in the above equation (5). ₀ ⁴ ), and if T = T ₀ , there is no energy W, and
The respective voltages Vs, Vs and the infrared data Vd shown in (3) become zero, and the zero detection circuit 63 outputs the detection signal S ₀ .

That is, it is confirmed by lighting the measurement permission mark 6b that the heat source that causes noise does not exist in the optical system 2 and the temperature can be measured.

The zero detection circuit 63 judges the value of the infrared data Vd as a digital value, and it is not necessary to make the judgment value strictly zero, and if it is smaller than a predetermined judgment value, it is ignored. As possible, the detection signal S ₀
Is output.

However, when T ≠ T ₀ in the equation (5), that is, when there is a temperature difference between the infrared sensor 3a and the light guide tube 20 and the hard cap 21, the energy W of the difference exists. Therefore, the value of the infrared data Vd is zero detection circuit 63.
It becomes larger than the judgment level of. As a result, the detection signal S ₀ is not output and the measurement permission mark 6b is not illuminated.

In the actual use of the radiation thermometer 1, the state of T ≠ T ₀ occurs as described above in the following cases. That is, this is the case where the operating environment temperature of the radiation thermometer 1 is suddenly changed. In this case, T ≠ T ₀ due to the difference in heat capacity between elements and the response, and the infrared data Vd based on the energy W of the difference. Since the measurement error occurs only for the value of, measurement is not possible.

In this case, if the metal housing 19 is left to stand for a while at a constant ambient temperature.
As a result of heat conduction being carried out via, the temperature will eventually stabilize in the heat balance state and the measurement will be permitted, but this stabilization time may require several tens of minutes.

The above is the function check mode, and the temperature measurement mode will be described next.

After confirming the lighting of the measurement permission mark 6b in the function check mode, the radiation thermometer 1 is removed from the storage case 30.

When the radiation thermometer 1 is removed from the storage case 30, the check switch SWc is turned off by releasing the pressing of the check button 12, and the check signal Sc output from the C terminal of the switch circuit 90 is released.
Disappears.

As a result, when the reset of the peak hold circuit 53 is released, the switching circuit 54 returns to the selected state of the input terminal I ₂ , and the zero detection circuit 63 also returns to the non-operating state.

As a result, the detection signal processing unit 50 A / D-converts the peak voltage Vsp held by the peak hold circuit 53 from the infrared voltage Vs output from the infrared amplifier circuit 51 via the switching circuit 54. The peak voltage Vsp is supplied to the circuit 55 and digitized to output infrared data Vd.

Further, the zero detection circuit 63 of the arithmetic unit 60 returns to the non-operating state, but since the detection signal S ₀ is held by the memory circuit provided in the zero detection circuit 63, the measurement of the display device 6 is permitted. The mark 6b continues to be illuminated.

Then, the detection signal S ₀ of the zero detection circuit 63 is obtained.
Continues until the memory circuit is reset by supplying the measure signal to the reset terminal R.

The above is the measurement standby state. From this state, as shown in FIG. 7, after inserting the probe 16 of the radiation thermometer 1 into the ear canal 41, the temperature is measured by pressing the measure buttons 14 and 15.

That is, when the major buttons 14 and 15 are pressed, the major switch SWm in FIG.
Then, the measure signal Sm is output from the M terminal of the switch circuit 90.

In the result calculation section 60, the temperature calculation circuit 61 and the sensitivity correction calculation circuit 64 are set to the calculation mode, the zero detection circuit 63 is reset at the same time, and the measurement permission mark 6b of the display device 6 is turned off.

Then, the probe 1 inserted into the external ear canal 41
6 (tympanic membrane 42 incident on the optical system 2 and the detector 3 in FIG. 1)
The infrared radiant energy from the infrared sensor 3a is converted into an infrared voltage Vs by the infrared sensor 3a of the detection unit 3, and the infrared amplifier circuit 5
After being amplified to the voltage Vs by 1, the peak hold circuit 53
At, the peak voltage Vsp is held.

Further, the peak voltage Vsp is converted into infrared data Vd by the A / D conversion circuit 55 and supplied to the calculation section 60.

The temperature-sensitive sensor 3b embedded in the metal housing 19 of FIG. 4 detects the temperature of the infrared sensor 3a and converts it into the temperature-sensitive voltage Vt, and then the temperature-sensitive data T ₀ by the A / D conversion circuit 56. And is supplied to the arithmetic unit 60.

[0147] The arithmetic unit 60 by the infrared data Vd and the temperature-sensitive data T ₀ is supplied, first sensitivity correction calculation circuit 64 is based on temperature-sensitive data T ₀ and 19 that is supplied (8) The value of sensitivity R is calculated by. The variation rate β is β = −0.003.

Next, the temperature calculation circuit 61 inputs the sensitivity R calculated by the sensitivity correction calculation circuit 64, the sensitivity data D from the sensitivity data input means 65, and the coefficient a of the quartic term from the filter correction means 5b. The sensitivity coefficient K ₃ of the lever system is calculated by K ₃ = aRD.

Then, the calculated sensitivity coefficient K ₃ , the emissivity ε from the emissivity input means 5a, and the symmetry axis temperature b from the filter correction means 5b are input, and the calculation of equation (17) is performed.

Vd = εK ₃ {(Tb ₁ −b) ⁴ − (T ₀ −b) ⁴ } (17) Further, by rearranging the equation (17), the temperature data Tb ₁ shown in the equation (18) is calculated. To do. The outer ear canal is surrounded at the same temperature, and the cavity can be regarded as a black body, so that the emissivity ε is ε = 1.

[0151]

[Equation 10] Then, the temperature data Tb ₁ is displayed on the numeral display portion 6 a of the display device 6 via the display drive circuit 62.

The above is one temperature measurement operation, and this series of operations will be described with reference to the flowchart of FIG.

First, when the probe 16 is inserted into the external ear canal 41 (step 1), the infrared energy radiated from the eardrum 42 becomes the infrared voltage Vs, and the peak voltage Vsp is held by the peak hold circuit 53 (step 2). . Next, the presence or absence of the major signal Sm is determined (step 3).
When the major buttons 14 and 15 are not pressed, the determination is NO, and only the peak value hold operation of step 2 is performed.

When the measure buttons 14 and 15 are pressed, the result is YES and the zero signal is detected by the measure signal Sm.
Is reset (step 4) and the sensitivity correction calculation circuit 64 reads the temperature sensitive data T ₀ (step 5) and calculates the sensitivity R (step 6).

Further, the temperature calculation circuit 61 reads the emissivity ε, the coefficient a, the sensitivity R, and the sensitivity data D (step 7),
The sensitivity coefficient K ₃ is calculated using a, R and D (step 8).

Further, the temperature calculation circuit 61 determines that the symmetry axis temperature b
And the peak-held infrared data Vd are read (step 9), and the temperature data Tb ₁ is calculated (step 1).
0).

Then, the display drive circuit 62 inputs the temperature data Tb ₁ and displays the temperature on the display device 6 (step 11), whereby the temperature measuring operation is completed.

Next, the role of the peak hold circuit 53 shown in FIG. 1 will be described with reference to FIG.

FIG. 9 is a temperature measurement curve of the radiation thermometer 1 according to the present invention, which is compared with the temperature measurement curve of the conventional electronic thermometer shown in FIG.

The horizontal axis represents the temperature measurement time, the vertical axis represents the measurement temperature, and the measurement site is the outer ear canal 41. The temperature curve Hs of the outer ear canal 41 and the measurement temperature curve Ms of the radiation thermometer 1 coincide with each other.

As described above, the hair 43 and the earwax 44 are present in the outer ear canal 41 of the ear shown in FIG.
As in the eardrum 42, the state before the temperature measurement of 3 and the earwax 44 is warmed to a temperature very close to this, and this state is shown in FIG.
Is the time point of t ₁ .

That is, the moment when the probe 16 is inserted into the outer ear canal 41 is time t ₁ , and since the inside of the outer ear canal 41 is almost at the temperature Tb ₁ at this moment, the infrared sensor 3a shows an infrared ray of a temperature level. Radiant energy is incident and stored in the peak hold circuit 53 of FIG. 1 as the peak voltage Vsp.

Immediately after the probe 16 is inserted, however, the temperature inside the ear canal 41 is cooled by the probe 16 and sharply drops like a temperature curve Hs. With this decrease, the infrared voltage Vs detected by the infrared sensor 3a
Also falls to the level of the temperature measurement curve Ms and cannot exceed the peak voltage Vsp, so the peak hold circuit 53 stores the peak voltage Vsp at time t ₁ .

It takes about 10 minutes for the lowered temperature curve Hs to return to the original temperature level Tb _1. The reason will be described with reference to FIG.

That is, although the temperature of the eardrum 42, the hair 43, the earwax 44, etc. is all lowered by the insertion of the probe 16 into the external ear canal 41, the eardrum 42 among the above parts is relatively quickly transferred by heat conduction from the body. It is possible to return to the level of the temperature Tb ₁ .

However, the downy hair 43 and the earwax 44, which have a low degree of close contact with the body, have a low thermal conductivity from the body, so that it takes about 10 minutes to return to the level of the temperature Tb ₁ .

Therefore, the internal temperature of the outer ear canal 41 is the temperature Tb ₁
Is at the level of t when the probe 16 is inserted.
_There is only _one point. Since a series of arithmetic processing of the radiation thermometer 1 cannot be performed with the infrared radiation energy of this short time, an instantaneous peak voltage Vs as shown by a dotted line in FIG.
p is stored as analog data in the peak hold circuit 53, and the stored peak voltage Vsp is used for A / D
Temperature measurement can be performed by performing conversion and a series of arithmetic processing.

That is, in the radiation thermometer without the preheating device as in the present invention, the peak hold circuit 53 is required. By using this peak hold circuit 53, the temperature Tb ₁ at the time point t ₁ can be kept extremely short. It becomes possible to measure.

FIG. 10 is a concrete configuration diagram of the peak hold circuit 53. It shows an input buffer 80, an output buffer 81, a backflow preventing diode 82, a signal charging capacitor 83, and a voltage charged in the capacitor 83. And a reset transistor R for inputting the infrared voltage Vs and outputting the peak value as the peak voltage Vsp.
When the switch transistor 84 is turned on by the check signal Sc supplied to, the charging voltage of the capacitor 83 is discharged.

(Other Embodiments) FIG. 12 is a sectional view of a head portion 110 according to another embodiment of the present invention. The same members as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 12, the portion different from FIG. 4 exposes the light guide tube 20 by providing a through hole 19f in the cylindrical portion 19a of the metal housing 19, and the temperature sensitive sensor 3c is exposed at the exposed portion of this light guide tube 20. Has been fixed.

The temperature sensor 3c is the temperature sensor 3b.
Is the same as the above, and the fixing method uses a mold resin.

That is, the difference from the first embodiment is that
This is a method of correcting the heat balance in the probe 16. While the first embodiment adopts the method of confirming the heat balance in the function check mode and permitting the measurement, the measurement is not permitted while the heat balance is not achieved. The form is two temperature sensors 3b, 3
By providing c, the temperature difference between the infrared sensor 3a and the light guide tube 20 is detected, and if the temperature difference is abnormally large, the measurement is not permitted, but the temperature difference is a preset value. If it is smaller, the temperature measurement is allowed even if the heat balance is not balanced, and the temperature data is calculated by performing the calculation with the temperature difference corrected to the measured value to determine the measurable condition of the radiation thermometer. It is wide.

The circuit configuration and operation will be described below with reference to FIG. 13. The same members as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 12, the detecting section 3 is provided with a temperature sensor 3c for measuring the temperature Tp of the light guide tube 20. The detection signal processing unit 50 includes a switching circuit 5
4 disappears and the output voltage Vs of the peak hold circuit 53
p is directly supplied to the A / D conversion circuit 55, and a temperature sensitive amplifier circuit 57 and an A / D conversion circuit 58 are newly provided to output the temperature sensitive data Tp.

Further, in the arithmetic unit 60, the emissivity εp of the light guide tube 20 is set in the emissivity input means 5a shown in FIG. 1, and a temperature difference detection circuit 67 is provided instead of the zero detection circuit 63. The temperature difference detection circuit 67 inputs the temperature data T ₀ of the infrared sensor 3a detected by the two temperature sensitive sensors 3b and 3c shown in FIG. 12 and the temperature data Tp of the light guide tube 20 and is determined in advance. A temperature difference determination is performed on the obtained measurement limit temperature difference Td.

When | T ₀ −Tp | <Td, that is, when the temperature difference is smaller than the limit temperature difference, the detection signal S ₀ is output and the measurement permission mark 6b of the display device 6 is turned on. This temperature difference determination operation is always performed while the power switch 13 shown in FIG. 3 is ON,
It is not necessary to operate the check button 12 as in the first embodiment.

It is similar to the first embodiment that the temperature measurement mode is entered when the measurement permission mark 6b is turned on.
The difference is that the temperature calculation circuit 61 receives temperature sensing data Tp of the light guide tube 20 in addition to the data described in FIG. 1, and the temperature calculation circuit 61 in the present embodiment uses the equation (19). The temperature data Tb ₂ is calculated.

[0179]

[Equation 11] The temperature data Tb ₂ is obtained by correcting the temperature difference by calculation and is displayed on the temperature display section 6 a of the display device 6 via the display drive circuit 62.

Further, the check signal Sc output from the switch circuit 90 of this embodiment is the peak hold circuit 53.
I'm only doing a reset. Therefore, when the temperature is re-measured, it is necessary to confirm the lighting of the measurement permission mark 6b and then operate the check button 12 to reset the peak hold circuit 53.

As described above, according to this embodiment, the temperature can be measured without waiting until the respective parts of the probe 16 are completely in thermal balance, so that the interval of repeated measurement can be shortened. Further, since a function check by infrared radiation is not required, a switching circuit and a storage case are not required, and the structure can be simplified.

In the present embodiment, the configuration in which the second temperature sensor 3c is brought into close contact with the light guide tube 20 is shown as the optimum embodiment, but the present invention is not limited to this. That is, the purpose of the second temperature sensor 3c is to guide the light guide tube 2 which is more sensitive to the ambient temperature than the embedded portion of the temperature sensor 3b.
0 is to detect the surface temperature, and considering that the surface of the light guide tube 20 and the ambient temperature are substantially the same, the temperature sensor 3c is mounted on the circuit board on which the IC chip for measurement is mounted. Then, the ambient temperature is measured, and this can be sufficiently used as the surface temperature of the light guide tube 20.

[0183]

As described above, according to the present invention, the sensitivity correction value is supplied to the temperature calculation circuit to calculate the temperature data, so that the measurement accuracy can be improved without using the conventional preheating device. Since it can be satisfied, it can be driven by a small battery, and it is possible to realize a small and low-priced radiation thermometer with a short measurement time.

[Brief description of drawings]

FIG. 1 is an overall block diagram of a radiation thermometer showing a first embodiment of the present invention.

FIG. 2 is a back view of the radiation thermometer according to the first embodiment.

FIG. 3 is a side view of the radiation thermometer shown in FIG.

FIG. 4 is a cross-sectional view showing a main part of a head part of the radiation thermometer shown in the first embodiment.

FIG. 5 is an enlarged cross-sectional view of the tip portion of the probe according to the first embodiment.

FIG. 6 is a side view showing a state in which the radiation thermometer according to the first embodiment is attached to a storage case.

FIG. 7 is a cross-sectional view of an ear showing a measurement state.

FIG. 8 is a flowchart showing the operation of the radiation thermometer shown in FIG.

FIG. 9 is a diagram showing a temperature measurement curve of the radiation thermometer of the present invention.

10 is a configuration diagram of the peak hold circuit shown in FIG. 1. FIG.

FIG. 11 is an overall block diagram showing a basic example of a radiation thermometer according to the present invention.

FIG. 12 is a cross-sectional view of a head portion showing another embodiment of the present invention.

FIG. 13 is an overall block diagram of a radiation thermometer according to another embodiment.

FIG. 14 is a temperature measurement curve diagram of a conventional contact type electronic thermometer.

FIG. 15 is a wavelength spectrum characteristic diagram of infrared radiation energy of an object.

FIG. 16 is a transmission wavelength characteristic diagram of a silicon filter.

FIG. 17 is a characteristic diagram showing a relationship between absolute temperature and radiant energy.

FIG. 18 is a block diagram of a conventional radiation thermometer.

FIG. 19 is a temperature characteristic diagram of conventional infrared sensor sensitivity.

[Explanation of symbols]

1, 70 Radiation thermometer, 2 Optical system, 3a Infrared sensor, 3b, 3c Temperature sensor, 5,60 Calculation part, 5b
Filter correction means, 16 probes, 50 detection signal processing section, 53 peak hold circuit, 61 temperature calculation circuit, 63 zero detection circuit, 64 sensitivity correction calculation circuit.

Claims (2)

[Claims] 1. An infrared sensor that receives heat radiation from an object to be measured and outputs an electric signal; a temperature sensor that measures the temperature of the infrared sensor and its surroundings and outputs an electric signal; Detection signal processing means for outputting infrared data and temperature sensitive data digitized based on electric signals from the external sensor and the temperature sensitive sensor, and sensitivity data of the infrared sensor is calculated based on the temperature sensitive data. A radiation thermometer, comprising: sensitivity correction calculation means; and temperature calculation means for calculating temperature data of the object to be measured based on the infrared data, temperature sensitive data, and sensitivity data. 2. The sensitivity correction calculation means calculates the sensitivity data R by the following formula: R = α {1 + β (T ₀ −T _m )} T ₀ : Temperature-sensitive data of temperature sensor T _m : At the time of sensitivity adjustment 2. The radiation thermometer according to claim 1, wherein: temperature α: sensitivity at temperature T _m β: fluctuation rate of sensitivity.