Radiation thermometer

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a radiation thermometer, and more particularly to a radiation thermometer system that does not use a preheating device in the main body.

【0002】

[Conventional technology]

As a thermometer, for example, a pen-type electronic thermometer that replaces a glass thermometer has become widespread in recent years.

【0003】

The features of this electronic thermometer are that it does not break, it is easy to read, and there is a buzzer at the end of temperature measurement, but it takes about 5 to 10 minutes to measure the temperature, which is almost the same as a glass thermometer, and this is the temperature measurement. Is the cause of trouble. There is a problem with the method of inserting the sensor part into the armpit or mouth and contacting the measurement site for measurement, and there are two reasons why the measurement time is long.

【0004】

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 temperature measurement, and gradually approach the body temperature by closing the armpit and mouth.

【0005】

Secondly, the thermometer sensor unit is cooled to the ambient temperature, and by inserting it into the measurement site, the temperature of the measurement site is further lowered, and it takes more time to equilibrate to the original body temperature.

【0006】

This state will be described with reference to FIG.

【0007】

Figure 14 is the horizontal axis the test temperature time, the temperature measurement curve of a contact-type electronic clinical thermometer for the vertical axis and the measurement temperature, H is the temperature curve of the axilla as a measurement site, M is the measured temperature curve of the thermometer.

【0008】

That is, t at the start of temperature measurement₁In, the axillary skin temperature is 36 ° C or less, and the temperature of the thermometer sensor unit is also cooled to 30 ° C or less. When the thermometer sensor unit is inserted under the armpit and the armpit is closed from this state, the measured temperature M of the thermometer sensor unit rises sharply, but the temperature H of the armpit is cooled by the thermometer sensor unit.₂After processing to, it begins to rise toward true body temperature. And when the sensor part of the thermometer is warmed to the skin temperature under the armpit, the point t₃From then on, the two temperature curves H and M rise in unison, but it takes about 5 to 10 minutes to rise to true body temperature as described above.

【0009】

And as is well known, the actual body temperature measurement method is t₁When measurement is performed at regular intervals from the time point, the measured values are compared and the maximum value is sequentially stored, the difference between the measured values is judged, and the difference between the measured values becomes smaller than the predetermined value. , Point t₄At the same time as the temperature measurement is stopped, the maximum value at that time is displayed as the body temperature (for example, Japanese Patent Application Laid-Open No. 50-31888).

【0010】

Considering the conditions for measuring the body temperature in a short time in consideration of the first and second reasons, select the part where the body temperature is before the start of the temperature measurement and bring the cold sensor into contact with it. If the measurement can be performed without any problem, the measurement can be performed in a short time.

【0011】

Therefore, a radiant thermometer has been proposed in which the eardrum is selected as the part of the body temperature before the start of temperature measurement and the temperature of the part is measured in a non-contact manner (for example, Japanese Patent Application Laid-Open No. 61-117422).

【0012】

Next, the principle of the radiation thermometer, which is the basis of the radiation thermometer, will be described. "Every object emits infrared radiation from its surface, and the amount and spectral characteristics of its infrared radiant energy are determined by the absolute temperature of the object, depending on the nature of the object and the finished surface condition. ]\ It is based on this law of physics. The law that indicates this will be described.

【0013】

First, Planck's law expresses the relationship between blackbody radiation intensity, spectral distribution, and temperature.

【0014】

[Number 1]

<img file="JP2813331B2_D0001.tif" />Figure 15 illustrates Planck's law. It can be seen that the radiant energy increases as the temperature of the blackbody increases. It can also be seen that the radiant energy changes depending on the wavelength, and the peak value of the distribution shifts to the shorter wavelength side as the temperature rises, but it radiates over a wide wavelength band.

【0015】

The total energy emitted from the blackbody is obtained by integrating W (λ, T) given by Eq. (1) with respect to λ from λ = 0 to λ = . This is Stefan-Boltzmann's law.

【0016】

[Number 2]

<img file="JP2813331B2_D0002.tif" />As is clear from equation (2), the total radiant energy W₁Is proportional to the fourth power of the absolute temperature T of the blackbody light source. It should also be noted that Eq. (2) is an equation obtained by integrating the infrared radiation emitted from the blackbody for all wavelengths.

【0017】

All of the above rules are derived for a blackbody with an emissivity of 1.00. However, in reality most objects are not perfect radiators and their emissivity is less than 1.00. Therefore, it is necessary to multiply by the emissivity and correct. Therefore, the radiant energy W of most non-blackbody objects₂Can be expressed as Eq. (3).

【0018】

[Number 3]

<img file="JP2813331B2_D0003.tif" />Equation (3) expresses the infrared radiant energy emitted from an object and incident on the infrared sensor, but the infrared sensor itself also emits infrared radiation according to the same rule. Therefore, the temperature of the infrared sensor itself is T.₀If so, σT₀⁴The energy of is emitted in the infrared, and the energy W obtained by subtracting the radiation from the incident is given by Eq. (4).

【0019】

W = σ (εT⁴+ γT₀⁴-T₀⁴) ...(Four) 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.

【0020】

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

【0021】

In addition, the infrared sensor has been left in an environment with an ambient temperature of Ta for a long time, and the infrared sensor temperature is T.₀Assuming that is equal to the ambient temperature Ta, Eq. (4) becomes Eq. (5).

【0022】

W = σ (εT⁴+ γT₀⁴-T₀⁴) = εσ (T⁴-T₀⁴) ...(Five) FIG. 18 is a basic configuration diagram of a conventional radiation thermometer, and the configuration will be described below based on the drawings.

【0023】

The radiation thermometer 7 is composed of an optical system 2, a detection unit 3, an amplification unit 4, a calculation unit 5, and a display device 6.

【0024】

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

【0025】

The detection unit 3 includes an infrared sensor 3a and a temperature sensor 3b. The infrared sensor 3a converts the infrared radiant energy obtained by subtracting the radiation from the infrared sensor 3a itself from the incident such as the infrared radiant energy collected by the optical system 2 into an electric signal, that is, an infrared voltage Vs. The temperature sensor 3b is the temperature T of the infrared sensor 3a and its vicinity.₀It is placed near the infrared sensor 3a to measure the temperature sensitivity voltage Vt. A thermopile is used for the infrared sensor 3a, and a temperature sensitive diode, for example, a thermistor, is used for the temperature sensor 3b.

【0026】

The amplifier 4 is an amplifier circuit that amplifies the infrared sensor 3a, that is, the infrared voltage Vs that is the output of the thermopile, and an A / D conversion circuit that converts the output voltage of the amplifier circuit into digitized infrared data Vd. An infrared amplifier 4a composed of Data T₀It consists of a temperature sensitive amplifier 4b composed of an A / D conversion circuit that converts to.

【0027】

Then, the two signals Vd and T from the amplification unit 4₀Is converted into temperature data T by the calculation unit 5 and displayed on the display device 6. Here, the calculation unit 5 is composed of an emissivity input means 5a for setting the emissivity ε of the object to be measured L and a calculation circuit 5c for performing a calculation based on the equation (5).

【0028】

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

【0029】

First, the object L to be measured emits infrared radiation, and its wavelength spectrum distribution extends over a wide wavelength range as shown in FIG. Then, the infrared radiation is focused by the light guide means 2a, passes through the filter 2b having a transmission wavelength characteristic, and reaches the infrared sensor 3a.

【0030】

There are other infrared radiant energies that reach the infrared sensor 3a. One is infrared radiant energy that is emitted from an object around the object L to be measured, is reflected by the object L to be measured, and then passes through the filter 2b to reach it. Others are infrared radiation emitted from an object in or around the infrared sensor 3a, which is reflected by the filter 2b and reaches, and infrared radiation energy reached by infrared radiation from the filter 2b. is there.

【0031】

Then, the infrared radiant energy from the infrared sensor 3a can be expressed as Eq. (3). However, ε = 1.00. That is, measuring the temperature of the infrared sensor 3a itself indirectly measures the infrared radiant 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 3a and its ambient temperature T.₀Is being measured.

【0032】

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

【0033】

Here, the infrared voltage Vs, which is the output voltage of the infrared sensor 3a, is the product of the infrared radiant energy W per unit area and the light receiving area S of the infrared sensor 3a multiplied by the sensitivity R. 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.

【0034】

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

【0035】

Vd = ε σSRA (T⁴-T₀⁴) ... (6) Vd: Output voltage of infrared amplifier 4a S: Light receiving area of infrared sensor 3a R: Sensitivity of infrared sensor A: Amplification rate of infrared amplifier 4a In general, K₁Set Eq. (6) as = σSRA and calculate the temperature T of the object to be measured L based on Eq. (7).

【0036】

[Number 4]

<img file="JP2813331B2_D0004.tif" />However, the thermal infrared sensor itself used in conventional radiation thermometers is not wavelength-dependent, but a silicon filter or quartz filter is used as a window material on the front of the can package on which the infrared sensor is mounted. A transparent material such as is arranged. This is because infrared radiation from an object has a wavelength spectrum distribution as shown in Fig. 15, so it mainly transmits only the radiating wavelength band and reduces the influence of external light. is there. Each of the transmission materials has a unique transmission wavelength characteristic, and an appropriate transmission material is selected depending on the temperature of the object to be measured, the processability of the transmission material, the price of the material, and the like.

【0037】

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]. And the transmittance is about 54%.

【0038】

As described above, the infrared sensor with a filter is a thermal type sensor itself 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.

【0039】

Therefore, Eq. (5) obtained by integrating the infrared radiant energy input to the infrared sensor with a filter for all wavelengths does not hold for an infrared sensor with a filter that transmits only a specific wavelength band. As a result, an error is included by this amount.

【0040】

Furthermore, in the conventional configuration, the sensitivity R of the infrared sensor is treated as a constant, but the sensitivity R of the actual infrared sensor is the infrared sensor temperature T.₀It fluctuates depending on the above, and this state is shown in Fig. 19.

【0041】

That is, FIG. 19 shows the sensitivity R obtained by actually measuring the output voltage Vs of the thermopile used as the infrared sensor using a blackbody, and the infrared sensor temperature T.₀Is a plot of the change in sensitivity R at each temperature. As a result, it was found that the temperature dependence of the sensitivity R can be approximated on a straight line as shown in Eq. (8).

【0042】

R = α {1 + β (T₀-T_m)} ... (8) Where α is T₀= T_mThis is the sensitivity R that serves as the reference for. T_mIs a representative temperature of the infrared sensor temperature, for example, the infrared sensor temperature when the infrared sensor sensitivity in a factory is measured. β represents the degree of fluctuation, and the volatility per [deg] was -0.3 [% / deg].

【0043】

It is natural that the fluctuation of the sensitivity R as described above becomes an error.

【0044】

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

【0045】

However, ordinary radiation thermometers are intended for high temperature measurement, and their measurement range is about 0 to 300 ° C, and the measurement accuracy is about ± (2 to 3) ° C. , The measures were omitted because the error due to the sensitivity fluctuation of the infrared sensor can be ignored.

【0046】

However, considering the measurement conditions as a thermometer, the temperature measurement range may be as narrow as 33 ° C to 43 ° C, but the temperature measurement accuracy is required to be ± 0.1 ° C.

【0047】

Therefore, when the radiation thermometer is used as a thermometer, for example, it is necessary to improve the temperature measurement accuracy by taking some measures against errors due to the filter characteristics and the sensitivity fluctuation of the infrared sensor.

【0048】

As a countermeasure, the radiant thermometer of JP-A-61-117422 has the following method.

【0049】

That is, it has a three-unit configuration consisting of a probe unit equipped with an infrared sensor, a chopper unit equipped with a target, and a charging unit.

【0050】

Then, a 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.

【0051】

When measuring body temperature, the probe unit is set in the chopper unit and calibrated with the probe having an infrared sensor and the target preheated by the heating control means, and then the probe unit is removed and inserted into the external ear canal. Then, the infrared rays radiated from the eardrum are detected, and the body temperature is measured by comparing with the infrared rays radiated from the target.

【0052】

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

【0053】

In this method, various error factors are eliminated by preheating the probe having an infrared sensor and the target to a reference temperature (36.5 ° C) close to the normal body temperature by a heating control means.

【0054】

That is, by heating the probe to a reference temperature higher than room temperature, the sensitivity of the infrared sensor does not fluctuate by keeping the infrared sensor at a constant temperature regardless of the ambient temperature, and the error can be ignored. Further, after calibrating the body temperature to be measured and the reference temperature of the target as close values, the error due to the filter characteristics is set to a level that can be ignored by performing comparative measurement.

【0055】

Furthermore, since the probe is preheated to a temperature close to body temperature, the problem that when a conventional cold probe is inserted into the external ear canal, the temperature of the external ear canal and eardrum is lowered by the probe and correct body temperature measurement is not performed is solved. doing.

【0056】

[Problems to be Solved by the Invention]

However, although the radiator thermometer of JP-A-61-117422 is extremely excellent in terms of temperature measurement accuracy, on the other hand, its structure and circuit configuration are complicated because it requires a heating control device with high control accuracy. There is a problem that the cost will increase. In addition, a long stabilization time was required to preheat the probe and target and control them to a constant temperature. Further, since the energy for driving the heating control device is relatively large, the result is that a charging unit having a large shape and a power cord is required. Therefore, a portable thermometer using a small battery as an energy source may be used. It can be said that it is impossible to adopt this method.

【0057】

An object of the present invention is to solve the above problems, to maintain the temperature measurement accuracy as a thermometer, and to provide a portable and miniaturized radiation thermometer at low cost.

【0058】

[Means for solving problems]

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

【0059】

That is, according to the present invention, a light guide means for collecting heat radiation from an object to be measured, and an infrared sensor that receives the heat radiation collected through the light guide means and outputs an electric signal. A temperature sensitive sensor that measures the absolute temperature as a reference and outputs an electric signal, and outputs digitized infrared data and temperature sensitive data based on the electric signals from the infrared sensor and the temperature sensitive sensor. A reference consisting of a detection signal processing means, a temperature calculation means for calculating temperature data of an object to be measured based on the infrared data and temperature sensing data, and a reflector located on the tip side of the light guide means for the infrared sensor. A comparative detection circuit having a zero detection circuit that detects comparative infrared data while facing the comparison surface, determines that the value of the comparative infrared data is zero or minute, and outputs a comparative detection signal. Including a display device that displays the temperature according to the temperature data and is provided with a measurement permission mark that is lit by the comparison detection signal output from the zero detection circuit, and the comparison infrared data obtained by measuring the temperature of the reference comparison surface. When there is an imbalance in the thermal balance between the light guide means of the radiation thermometer and the infrared sensor, the temperature measurement is suspended until the thermal balance reaches a desired equilibrium state.

【0060】

Therefore, according to the present invention, even if there is an imbalance in heat balance between the light guide means and the infrared sensor, it can be detected as comparative infrared data, and this comparative infrared data is used. Therefore, it is possible to use it for various temperature measurement processes, such as suspending temperature measurement until the thermal balance reaches a desired equilibrium state, or using this comparative infrared data for calculation of temperature data. As a result, according to the present invention, the temperature measurement accuracy of the radiation thermometer can be preferably maintained.

【0061】

【0062】

Further, according to the present invention, the state of the thermal balance can be determined based on the presence or absence of comparative infrared data, and it is possible to reliably and accurately measure the temperature when the thermal balance is within a predetermined region.

【0063】

Further, according to the present invention, there is an advantage that the possibility of temperature measurement can be easily recognized by the display circuit.

【0064】

Further, according to the present invention, since the reference comparison surface for detecting the comparative infrared data is provided on the tip side of the light guide means of the radiation thermometer, the detection of the comparative infrared data becomes extremely easy. There is.

【0065】

Further, the present invention is characterized in that the reflector located on the tip end side of the light guide means is provided in the case for accommodating the radiation thermometer.

【0066】

Therefore, according to the present invention, when performing the temperature measurement action by the radiation thermometer, it is possible to detect the comparative infrared data while the thermometer itself is housed in the case.

【0067】

【0068】

【0069】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

【0070】

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

【0071】

In FIG. 11, the same numbers as those in FIG. 18 indicate the same configuration, and the description thereof will be omitted. The differences from FIG. 18 are the measurement of the temperature of the eardrum of the ear as the object L to be measured and the calculation unit 5, which will be described below.

【0072】

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

【0073】

Therefore, the calculation unit 5 calculates the measurement 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.

【0074】

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

【0075】

As mentioned 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 as shown in Eq. (9).

【0076】

[Number 5]

<img file="JP2813331B2_D0005.tif" />The first term of Eq. (9) is the energy that is emitted infraredly from the object L to be measured with an emissivity ε and reaches through the filter. The second term is temperature T₀It is the energy that is emitted infraredly from the surrounding object, reflected by the object L to be measured, and reaches through the filter 2b. The third term is temperature T₀Energy emitted from the infrared sensor 3a or an object around it, reflected by the filter 2b, or temperature T₀It is the energy reached by infrared radiation from the filter 2b of. Here, there is a relationship that "for a transmissive material, the sum of the transmittance, the reflectance, and the emissivity is equal to 1.", And the third term is a term considering the reflection by the filter 2b or the radiation. It should also be noted that this reflection reflects the infrared radiation from the infrared sensor 3a side by the filter 2b. Finally, the fourth term is temperature T₀It is the energy emitted infraredly from the infrared sensor 3a itself, and the negative number is negative.

【0077】

Then, Eq. (9) can be rewritten as Eq. (10).

【0078】

[Number 6]

<img file="JP2813331B2_D0006.tif" />That is, the infrared radiant energy W obtained by subtracting the radiation from the incident of the infrared sensor 3a having the filter 2b is "proportional to the difference of the fourth power of the absolute temperature" as shown in Eq. (5). ], But it was found that the equation should take into account the transmission wavelength characteristics of the filter 2b as in equation (10). In other words, a new equation that replaces Stefan-Boltzmann's law shown in equation (2) is required.

【0079】

Therefore, if the infrared radiant energy emitted from the blackbody at absolute temperature T and transmitted through the filter having the transmittance η (λ) is F (T), it can be expressed as in Eq. (11).

【0080】

[Number 7]

<img file="JP2813331B2_D0007.tif" />Here, assuming that the temperature range of the absolute temperature T is a section from Tmin to Tmax, an arbitrary absolute temperature T in that section is assumed.₁, T₂, T₃... T_nTable 1 shows the calculation results of Eq. (11).

【0081】

[table 1]

<img file="JP2813331B2_D0008.tif" />Therefore, we examined how the relationship between the absolute temperature T shown in Table 1 and the infrared radiant energy F (T) transmitted through the filter is related to Stefan-Boltzmann's law. The graph showing the examination process is shown in FIG. This will be described with reference to FIG.

【0082】

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

【0083】

The curve B is the absolute temperature T shown in Table 1.₁~ T_nA curve B ́ is created by blotting each point in the above curve B ́, and the curve A is deformed and moved and superimposed on the curve B ́. The type of this deformation and movement is described in the fourth-order term of the curve A. By selecting the coefficient a, the amount of movement b in the horizontal axis direction, and the amount of movement c in the vertical axis direction, it became possible to superimpose them.

【0084】

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

【0085】

F (T) = a (Tb)⁴+ c ... (12) Then, from the values shown in Table 1, find the optimum values of a, b, and c shown in Eq. (12) by a method such as the least squares method, and substitute these values into Eq. (12) to obtain an approximate expression.

【0086】

Here, a, b, and c will be explained in comparison with Stefan-Boltzmann's law (2).

【0087】

a is the coefficient of the fourth-order term of the absolute temperature T, which corresponds to the Stefan-Boltzmann constant σ of the curve A, and the unit is [W / cm.² Deg⁴], B indicate the axis of symmetry temperature. In curve A, the absolute temperature is 0 [K], but in curve B, the absolute temperature b [K] is the axis of symmetry.

【0088】

c indicates the minimum value, and 0 [W / cm] on curve A.²], But on curve B, C [W / cm²] Is the offset.

【0089】

Then, when the equation (10) is rewritten using the approximate equation (12), the equation (13) is obtained.

【0090】

W = ε [a (Tb)⁴+ c] -ε [a (T₀-b)⁴+ c] = ε a [(Tb)⁴-(T₀-b)⁴] ...(13) As can be seen from the above equation (13), the minimum value c is canceled.

【0091】

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

【0092】

[Number 8]

<img file="JP2813331B2_D0009.tif" />In other words, when a filter with transmission wavelength characteristics is used for the optical system member, the calculation is not performed using the rule that "infrared radiant energy is proportional to the fourth power of absolute temperature T." It is necessary to calculate based on equation (14) that "infrared radiant energy is proportional to the fourth power of (absolute temperature T-axis of symmetry temperature b)."

【0093】

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

【0094】

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

【0095】

The transmission wavelength characteristics of the silicon filter are shown in FIG. 16, but in order to simplify the calculation, "the transmission wavelength band of the silicon filter is 1 to 18 [μm], and its transmittance is 54 [%]. ].

【0096】

[Number 9]

<img file="JP2813331B2_D0010.tif" />Calculate by substituting Eq. (1) for W (λ, T).

【0097】

In addition, since the measurement environment and the measurement temperature range of the object to be measured were within the range of 0 [° C] to 50 [° C], Tmin was set to 273 [K] and Tmax was set to 323 [K]. Table 2 shows the calculation results of Eq. (16).

【0098】

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

【0099】

a = 4.104 × 10^-12[W / cm² Deg⁴] b = 45.96 [K] c = -6.144 × 10^-4[W / cm²] That is, the coefficient a of the fourth-order term and the temperature b of the axis of symmetry obtained here are values indicating the transmission wavelength characteristics of the silicon filter, and the values of the coefficient a of the fourth-order term and the temperature b of the axis of symmetry are output from the filter correction means 5b. ing. The filter correction means 5b is a part of the arithmetic program memory of the arithmetic unit 5, and the coefficient a of the fourth-order term and the temperature b of the axis of symmetry are written therein.

【0100】

[Table 2]

<img file="JP2813331B2_D0011.tif" />That is, when the silicon filter is used as the window material for the measurement of the infrared sensor, when calculating the temperature T of the object to be measured, it is not calculated by the formula (5) but by the formula (14). By calculating with, highly accurate temperature calculation can be performed.

【0101】

As is clear from the above description, according to this basic example, even if a transmission 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.

【0102】

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.

【0103】

In this basic example, as a new equation to replace Stefan-Boltzmann's law, an approximate equation of the fourth order term was adopted as in equation (12), but as shown in Fig. 17, the thermometer has a measurement range of Tmin to Tmax. Since only a part of the curve is used, it does not necessarily have to be an approximation of the fourth-order term, and even if it is approximated by an appropriate higher-order equation, sufficient accuracy as a thermometer can be obtained. 14) ́ type can also be adopted.

【0104】

Vd = εK ́₂{(Tb-b ́)²-(T₀-b ́)²} ...(14 (First Embodiment) Next, as the first embodiment of the present invention, a specific configuration of a radiation thermometer actually manufactured using a commercially available thermopile in consideration of mass productivity will be described. In practice, the radiation thermometer of this embodiment is used as a thermometer.

【0105】

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

【0106】

Further, the head portion 11 is provided so as to project in a "dogleg" shape from the end portion of the main body portion 10, and the tip of the head portion 11 is a probe 16, which is shown in FIG. It is composed of a light guide means including an optical system 2 and a detection unit 3.

【0107】

That is, this optical system is provided with a light guide means for condensing infrared radiation from the object to be measured and a filter having transmission wavelength characteristics.

【0108】

The operation method of the radiation thermometer 1 is to perform a check operation described later with the power switch 13 turned on, and then insert the probe 16 into the external ear canal of the subject while pressing the major buttons 14 and 15. The temperature measurement is completed instantly just by turning on either one or both, and the result is displayed as the temperature on the display device 6.

【0109】

FIG. 4 is a cross-sectional view of the head portion 11, and the case bodies 17 and 18 are made of a resin molded body having extremely low thermal conductivity. The portion of the case body 17 forming the probe 16 is a cylindrical tubular portion 17a, and the tubular portion 17a is fitted with a metal housing 19 made of a lightweight metal having good thermal conductivity such as aluminum. There is. The metal housing 19 is provided with a cylindrical portion 19a, a hollow portion 19b communicating with the cylindrical portion 19a, and a base portion 19d provided with a recess 19c for embedding a temperature-sensitive element, and a filter is attached to the tip of the cylindrical portion 19a. A stepped portion 19e for use is provided. A light guide tube 20 with gold (Au) plating on the inner circumference of the 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 to be held 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.

【0110】

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

【0111】

According to the above configuration, since the infrared sensor 3a, the light guide tube 20, and the hard cap 21 are connected by the metal housing 19 having good thermal conductivity, a thermal balance is always obtained, and the common temperature is felt. It is designed to be detected by the temperature sensor 3b.

【0112】

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

【0113】

FIG. 5 is an enlarged cross-sectional view of the tip of the probe 16 and prevents the probe 16 from coming into contact with the inner wall of the external ear canal by covering the tip of the probe 16 with the tip 28a of the temperature measuring cover 28. ..

【0114】

FIG. 6 is a side view showing a state in which the radiation thermometer 1 is mounted on the storage case 30, and the storage case 30 is stored for storing the mounting portion 30a for mounting the main body 10 and the probe 16. A portion 30b is provided, and a reflector 31 forming a reference comparison surface in the present invention is fixed to a position corresponding to the tip of the probe 16 on the bottom surface 30c of the storage portion 30b.

【0115】

Further, the storage case 30 is provided with a button pressure receiving 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 on the reflector 31 and a check button is provided by the button pressure responding unit 30d. 12 turns on. This state is a function check state described later, and it is possible to know whether or not temperature measurement is possible from the display state of the display device 6.

【0116】

FIG. 7 is a cross-sectional view of the ear portion showing a state in which the temperature is measured by the radiation thermometer 1. 40 is the pinna, 41 is the external ear canal, 42 is the eardrum, and the inner wall of the external ear canal 41 A large number of hair growth 43 grows. Earwax 44 may have accumulated on the inner wall of the outer ear canal 41.

【0117】

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

【0118】

FIG. 1 is a block diagram of the radiation thermometer 1 shown in FIG. 2, and the same members as those in FIG. 11 are numbered the same, and the description thereof will be omitted.

【0119】

Explaining the part different from FIG. 11, 50 is a detection signal processing unit, which corresponds to the amplification unit 4 shown in FIG. 11 and shows a specific configuration. That is, the output of the infrared amplifier circuit 51 that amplifies the infrared voltage Vs output by the infrared sensor 3a, the temperature-sensitive amplifier circuit 52 that amplifies the temperature-sensitive voltage Vt output by the temperature-sensitive sensor 3b, and the infrared amplifier circuit 51. The peak hold circuit 53 for holding the peak value of the voltage Vs, the output voltage Vs of the infrared amplifier circuit 51 and the output voltage Vsp of the peak hold circuit 53 are input terminals I, respectively.₁And I₂Switching circuit 54 that inputs to and selects and outputs from output terminal 0 according to the conditions of control terminal C, and A / D that converts the infrared voltage Vs or Vsp output from the switching circuit 54 into digitized infrared data Vd. The temperature-sensitive data T in which the output voltage Vt of the conversion circuit 55 and the temperature-sensitive amplifier circuit 52 is digitized.₀It has an A / D conversion circuit 55 that converts to, and digitizes the infrared voltage Vs and temperature-sensitive voltage Vt input from the detection unit 3, and the infrared data Vd and temperature-sensitive data T.₀Convert to and output.

【0120】

The calculation unit 60 corresponds to the calculation unit 5 of FIG. 11, but was calculated by the emissivity input means 5a, the filter correction means 5b, the temperature calculation circuit 61 corresponding to the calculation circuit 5c, and the temperature calculation circuit 61. Temperature data Tb₁Is input to the display drive circuit 62 that displays the temperature on the temperature display unit 6a of the display device 6, and the comparative infrared data Vd output from the detection signal processing unit 50 during temperature measurement processing such as function check is input. When the comparative infrared data Vd is detected to be zero, the detection signal S₀The zero detection circuit 63 for lighting the measurement permission mark 6b of the display device 6 and the temperature sensitive data T output from the detection signal processing unit 50.₀Is input, and the sensitivity correction calculation circuit 64 for calculating and outputting the sensitivity R according to the equation (8) shown in FIG. 19 and the light receiving area S and red of the infrared sensor 3a shown in the equation (6) above. It has a sensitivity data input means 65 that outputs a value input and set from the outside as sensitivity data D based on the amplification factor A of the external amplifier circuit 51.

【0121】

Reference numeral 90 denotes a switch circuit, in which the major switch SWm operated by the major buttons 14 and 15 shown in FIG. 2 and the check switch SWc operated by the check button 12 are connected, and when the major button 14 or 15 is pressed, the check switch SWc is connected. The major switch SWm is turned on and the major signal Sm is output from the M terminal.

【0122】

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

【0123】

Then, the major signal Sm output from the M terminal of the switch circuit 90 is supplied to each enable terminal E of the temperature calculation circuit 61 and the sensitivity correction calculation circuit 64 to set both circuits to the calculation mode and at the same time the zero detection. Reset circuit 63.

【0124】

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.

【0125】

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

【0126】

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 measure switch SWm are turned off, so the check signal Sc and the measure from the switch circuit 70 No signal Sm is output.

【0127】

As a result, in the calculation unit 60, the temperature calculation circuit 61 and the sensitivity correction calculation circuit 64 are set to the non-calculation mode, and the zero detection circuit 63 is also set to the non-operation mode.

【0128】

The switching circuit 54 of the detection signal processing unit 50 is I.₂The voltage Vsp input to the terminal is selectively output to the output terminal 0, and the peak hold circuit 53 is in the operating state after the reset is released. The above is the initial state, and next, the function check mode will be described.

【0129】

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, so that the check switch SWc of FIG. 1 is turned on and the probe 16 is turned on. The tip is set at the position of the reflector 31.

【0130】

As a result, the switch circuit 90 in FIG. 1 outputs a check signal Sc from the C terminal when the check switch SWc is turned ON, and supplies the check signal Sc to the peak hold circuit 53, the changeover circuit 54, and the zero detection circuit 63. When this check signal Sc is supplied, the detection signal processing unit 50 resets the peak hold circuit 53, and at the same time, the switching circuit 54 is input terminal I.₁The voltage Vs supplied to the output terminal 0 is selectively output to the output terminal 0, and the A / D conversion circuit 55 digitally converts the infrared voltage Vs and outputs the infrared data Vd.

【0131】

Further, in the calculation unit 60, the temperature calculation circuit 61 and the sensitivity correction calculation circuit 64 are set to 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, and the operation of the radiation thermometer 1 in this function check mode is to convert the infrared rays reflected by the reflector 31 forming the reference comparison surface into the infrared sensor 3a and the infrared amplifier circuit. 51, the comparison infrared data Vd converted by the switching circuit 54 and the A / D conversion circuit 55 is determined by the zero detection circuit 63, and if this comparison infrared data Vd is zero, the zero detection circuit 63 detects at the output terminal 0. Signal S₀Is output, and the measurement permission mark 6b of the display device 6 is turned on.

【0132】

Here, the contents of the above function check mode will be described.

【0133】

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

【0134】

That is, the infrared radiant energy radiated from the light guide tube 20 and the hard cap 21 having a temperature T is reflected by the reflector 31 and incident on the infrared sensor 3a. Also temperature T₀Infrared radiant energy is also emitted from the infrared sensor 3a of the above, and the energy W of the difference obtained by subtracting the radiation from this incident is as shown in Eq. (5) above. W = εσ (T⁴-T₀⁴) And T = T₀If so, the energy W does not exist, and each voltage Vs, Vs and comparative infrared data Vd shown in FIG. 1 become zero, and the detection signal S from the zero detection circuit 63.₀Is output.

【0135】

That is, it is confirmed by lighting the measurement permission mark 6b that there is no heat source that becomes noise in the portion of the optical system 2, the heat balance is in an equilibrium state, and accurate temperature measurement is possible.

【0136】

The zero detection circuit 63 determines the value of the comparative infrared data Vd as a digital value, and the determination value does not have to be strictly zero, and can be ignored if it is smaller than a predetermined determination value. As the detection signal S₀Is output.

【0137】

However, in the above equation (5), T T₀If there is a temperature difference between the infrared sensor 3a and the light guide tube 20 and the hard cap 21, the value of the comparative infrared data Vd is the determination of the zero detection circuit 63 because the energy W of the difference exists. Greater than the level. This result detection signal S₀Is not output and the measurement permission mark 6b is not lit.

【0138】

When using the actual radiation thermometer 1, T T as described above.₀The state of occurs in the following cases. That is, it is a case where the operating environment temperature of the radiation thermometer 1 is suddenly changed. In this case, T T due to the difference in heat capacity and responsiveness between each element.₀Therefore, the heat balance is irregular, and a measurement error occurs only by the value of the comparative infrared data Vd based on the energy W of the difference, so that the measurement is impossible.

【0139】

In this state, if left at a constant environmental temperature for a while, heat conduction will occur through the metal housing 19, and eventually the heat balance will be stable and the measurement will be permitted. , This stabilization time may take tens of minutes.

【0140】

As described above, according to the present invention, the comparative infrared data obtained by measuring the temperature of the reference comparison surface is used for the function check, and the measurement is permitted in a state where the thermal balance state is stable. However, in the present invention, the comparative infrared data can be used for arbitrary temperature measurement processing, for example, the infrared data itself can be used for temperature calculation even when the heat balance exceeds a predetermined value.

【0141】

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

【0142】

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

【0143】

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

【0144】

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

【0145】

As a result, the detection signal processing unit 50 transfers the peak voltage Vsp held by the peak hold circuit 53 from the infrared voltage Vs output from the infrared amplifier circuit 51 to the A / D conversion circuit 55 via the switching circuit 54. It supplies and outputs infrared data Vd, which is a digitized version of this peak voltage Vsp.

【0146】

Further, the zero detection circuit 63 of the arithmetic unit 60 returns to the non-operating state, but the detection signal S₀Is held by a storage circuit provided in the zero detection circuit 63, so that the measurement permission mark 6b of the display device 6 remains lit.

【0147】

Then, the detection signal S of the zero detection circuit 63₀Continues until the storage circuit is reset by supplying a major signal to the reset terminal R.

【0148】

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

【0149】

That is, when the major buttons 14 and 15 are pressed, the major switch SWm in FIG. 1 is turned on, and the major signal Sm is output from the M terminal of the switch circuit 90.

【0150】

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

【0151】

Then, the infrared radiant energy from the tympanic membrane 42 incident on the probe 16 (optical system 2 and detection unit 3 in FIG. 1) inserted into the external ear canal 41 is converted into an infrared voltage Vs by the infrared sensor 3a of the detection unit 3. Further, after being amplified to the voltage Vs by the infrared amplifier circuit 51, the peak voltage Vsp is held by the peak hold circuit 53.

【0152】

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

【0153】

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

【0154】

Infrared data Vd and temperature sensitive data T₀Is supplied, the calculation unit 60 first receives the temperature-sensitive data T to which the sensitivity correction calculation circuit 64 is supplied.₀And the value of sensitivity R is calculated by Eq. (8) based on Fig. 19. The volatility β is β = -0.003.

【0155】

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 fourth term from the filter correction means 5b, and this system. Sensitivity coefficient K₃K₃Calculated by = aRD.

【0156】

Next calculated sensitivity coefficient K₃And the emissivity ε from the emissivity input means 5a and the symmetry axis temperature b from the filter correction means 5b are input to perform the calculation of Eq. (17).

【0157】

Vd = εK₃{(Tb₁-b)⁴-(T₀-b)⁴} ... (17) Furthermore, by rearranging Eq. (17), the temperature data Tb shown in Eq. (18)₁Is calculated. Since the external ear canal is surrounded by the same temperature and the cavity can be regarded as a blackbody, the emissivity ε is set to ε = 1.

【0158】

[Number 10]

<img file="JP2813331B2_D0012.tif" />And the temperature data Tb₁Is displayed on the number display unit 6a of the display device 6 via the display drive circuit 62.

【0159】

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

【0160】

First, when the probe 16 is inserted into the external ear canal 41 (step 1), the radiated infrared energy 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), but if the major buttons 14 and 15 are not pressed, the result is NO, and only the peak value hold operation in step 2 is performed.

【0161】

When the major buttons 14 and 15 are pressed, YES is set and the zero detection circuit 63 is reset by the major signal Sm (step 4), and the sensitivity correction calculation circuit 64 is subjected to temperature sensitivity data T.₀(Step 5) Calculate the sensitivity R (Step 6).

【0162】

Further, the temperature calculation circuit 61 reads the emissivity ε, the coefficient a, the sensitivity R, and the sensitivity data D (step 7), and uses the a, R, and D to obtain the sensitivity coefficient K.₃Is calculated (step 8).

【0163】

Further, the temperature calculation circuit 61 reads the infrared data Vd peak-held with the temperature b on the axis of symmetry (step 9), and the temperature data Tb.₁Is calculated (step 10).

【0164】

Then, the display drive circuit 62 is subjected to the temperature data Tb.₁Is input to display the temperature on the display device 6 (step 11), and the temperature measurement operation is completed.

【0165】

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

【0166】

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

【0167】

The horizontal axis is the temperature measurement time, the vertical axis is the measurement temperature, and the measurement site is the external ear canal 41. The temperature curve Hs of the external ear canal 41 and the measurement temperature curve Ms of the radiation thermometer 1 are the same.

【0168】

As described above, hair growth 43 and earwax 44 are present in the external ear canal 41 of the ear shown in FIG. 7, but the state of the hair growth 43 and earwax 44 before the start of temperature measurement is extremely close to the temperature like the eardrum 42. It is warmed to, and this state is t in Fig. 9.₁At the time of.

【0169】

That is, the moment when the probe 16 is inserted into the external ear canal 41 is t.₁At this moment, the temperature inside the external ear canal 41 is almost Tb.₁Therefore, the infrared radiant energy at the temperature level is incident on the infrared sensor 3a and stored as the peak voltage Vsp in the peak hold circuit 53 in FIG.

【0170】

However, immediately after the probe 16 is inserted, the temperature inside the external ear canal 41 drops sharply as shown by the temperature curve Hs due to being cooled by the probe 16. Along with this decrease, the infrared voltage Vs detected by the infrared sensor 3a also decreases to the level of the temperature measurement curve Ms, and the peak voltage Vsp cannot be exceeded.₁The peak voltage Vsp at the time point is stored.

【0171】

And the lowered temperature curve Hs is the original temperature level Tb₁It takes about 10 minutes to return to, and the reason for this will be explained with reference to Fig. 7.

【0172】

That is, the temperature of the eardrum 42, the hair growth 43, the earwax 44, etc. is all lowered by inserting the probe 16 into the external ear hole 41, but the eardrum 42 of the above parts is relatively quickly heated by heat conduction from the body.₁You can return to the level of.

【0173】

However, the temperature Tb of hair growth 43 and earwax 44, which have low adhesion to the body, is low in thermal conductivity from the body.₁As a result, it takes about 10 minutes to return to the level of.

【0174】

Therefore, the internal temperature of the external ear canal 41 is the temperature Tb.₁At the level of t at the moment when probe 16 is inserted₁Only at the time. Since the series of arithmetic processing of the radiation thermometer 1 cannot be performed with this short-time infrared radiant energy, the momentary peak voltage Vsp is stored in the peak hold circuit 53 as analog data as shown by the dotted line in FIG. The temperature can be measured by performing A / D conversion and a series of arithmetic processing using this stored peak voltage Vsp.

【0175】

That is, a peak hold circuit 53 is required in a radiation thermometer that does not have a preheating device as in the present invention, and by using this peak hold circuit 53, t₁Current temperature Tb₁Can be measured in an extremely short time.

【0176】

FIG. 10 is a specific configuration diagram of the peak hold circuit 53, in order to discharge the voltage charged in the input buffer 80, the output buffer 81, the backflow prevention diode 82, the signal charging capacitor 83, and the capacitor 83. It is composed of the switch transistor 84 of the above, inputs the infrared voltage Vs, outputs the peak value as the peak voltage Vsp, and turns on the switch transistor 84 by the check signal Sc supplied to the reset terminal R to make a capacitor. 83 Charges Discharges the pressure.

【0177】

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

【0178】

In FIG. 12, the portion different from FIG. 4 is that the light guide tube 20 is exposed by providing a through hole 19f in the cylindrical portion 19a of the metal housing 19, and the temperature sensor 3c is fixed to the exposed portion of the light guide tube 20. It is in that.

【0179】

This temperature sensor 3c is the same as the temperature sensor 3b, and the fixing method is also using a mold resin.

【0180】

That is, the difference from the first embodiment lies in the heat balance correction method in the probe 16. While the first embodiment adopts a method of confirming the thermal balance in the function check mode and permitting the measurement, the measurement is disallowed while the thermal balance is not balanced, whereas this embodiment is , By providing two temperature sensors 3b and 3c, the temperature difference between the infrared sensor 3a and the light guide tube 20 is detected, and if this temperature difference is abnormally large, the measurement is disallowed. If the temperature difference is smaller than the predetermined set value, the temperature measurement is permitted even if the thermal balance is not achieved, and the temperature data is calculated by adding the correction of the temperature difference to the measured value. , The measurable conditions of the radiation thermometer are widened.

【0181】

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

【0182】

As shown in FIG. 12, the detection unit 3 is provided with a temperature sensitive sensor 3c for measuring the temperature Tp of the light guide tube 20. In the detection signal processing unit 50, the switching circuit 54 disappears and the output voltage Vsp of the peak hold circuit 53 is directly supplied to the A / D conversion circuit 55, and the temperature sensing amplifier circuit 57 and the A / D conversion circuit 58 Is newly provided to output temperature sensitive data Tp.

【0183】

Further, in the calculation unit 60, the emissivity εp of the light guide tube 20 is set in the emissivity input means 5a shown in FIG. 1, and the temperature difference detection circuit 67 is provided instead of the zero detection circuit 63. The temperature difference detection circuit 67 is the temperature data T of the infrared sensors 3a detected by the two temperature sensors 3b and 3c shown in FIG.₀Then, the temperature data Tp of the light guide tube 20 is input, and the temperature difference is determined with respect to the predetermined measurement limit temperature difference Td.

【0184】

And | T₀-When Tp | &lt;Td, that is, when the temperature difference is smaller than the limit temperature difference, the detection signal S₀Is output to light the measurement permission mark 6b of the display device 6. This temperature difference determination operation is always performed while the power switch 13 shown in FIG. 3 is ON, and does not require the operation of the check button 12 as in the first embodiment.

【0185】

When the measurement permission mark 6b lights up, the temperature measurement mode is entered in the same manner as in the first embodiment, except that the temperature calculation circuit 61 has the light guide tube 20 in addition to the data described in FIG. The temperature sensitive data Tp of is input, and the temperature calculation circuit 61 in the present embodiment has the temperature data Tb according to the equation (19).₂Is calculated.

【0186】

[Number 11]

<img file="JP2813331B2_D0013.tif" />This temperature data Tb₂Is the temperature difference corrected by calculation, and is displayed on the temperature display unit 6a of the display device 6 via the display drive circuit 62.

【0187】

Further, the check signal Sc output from the switch circuit 90 of the present embodiment only resets the peak hold circuit 53. Therefore, when re-measuring the temperature, it is necessary to confirm that the measurement permission mark 6b is lit, and then operate the check button 12 to reset the peak hold circuit 53.

【0188】

As described above, according to the present embodiment, the temperature can be measured without waiting for each part of the probe 16 to be completely heat-balanced, so that the interval of repeated measurement can be shortened. Further, since the function check by infrared radiation is not required, a switching circuit and a storage case are not required, and the configuration can be simplified.

【0189】

In this 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 embodiment is not limited to this. That is, the purpose of the second temperature sensor 3c is to detect the surface temperature of the light guide tube 20 that responds more sensitively to the ambient temperature than the embedded portion of the temperature sensor 3b, and the light guide tube 20 Considering that the surface and the ambient temperature are almost the same, the temperature sensor 3c is mounted on the circuit board on which the IC chip for measurement is mounted to measure the ambient temperature, and this is measured as the surface temperature of the light guide tube 20. It is fully available.

【0190】

[Effect of the invention]

As described above, according to the present invention, in the temperature measurement operation, the comparative infrared data is detected with the infrared sensor of the radiation thermometer facing a predetermined reference comparison surface, and the thermal balance of the light guide means and the infrared sensor is detected. Can be checked, and various temperature measurement processes using the comparative infrared data obtained at the time of this function check, for example, disapproval of temperature measurement operation in a state where the heat balance is irregular, or the obtained infrared data It is possible to easily perform temperature calculation correction and the like using. As a result, it became possible to drive with a small battery, and it was possible to realize a small and inexpensive radiation thermometer with a short measurement time.

[Simple explanation of drawings]

[Figure 1]

It is the whole block diagram of the radiation thermometer which shows 1st Embodiment of this invention.

[Figure 2]

It is a back view of the radiation thermometer in the first embodiment.

[Fig. 3]

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

[Fig. 4]

It is sectional drawing which shows the main part of the head part of the radiation thermometer shown in 1st Embodiment.

[Fig. 5]

It is an enlarged sectional view of the tip part of the probe in 1st Embodiment.

[Fig. 6]

It is a side view which shows the state which attached the radiation thermometer in 1st Embodiment to a storage case.

[Fig. 7]

It is sectional drawing of the selvage part which shows the measurement state.

[Fig. 8]

It is a flowchart which shows the operation of the radiation thermometer shown in FIG.

[Fig. 9]

It is a figure which shows the temperature measurement curve of the radiation thermometer of this invention.

[Fig. 10]

It is a block diagram of the peak hold circuit shown in FIG.

[Fig. 11]

It is an overall block diagram which shows the basic example of the radiation thermometer which concerns on this invention.

[Fig. 12]

It is sectional drawing of the head part which shows the other embodiment of this invention.

[Fig. 13]

It is the whole block diagram of the radiation thermometer which concerns on other embodiment.

[Fig. 14]

It is a temperature measurement curve diagram of the conventional contact type electronic thermometer.

[Fig. 15]

It is a wavelength spectrum characteristic diagram of the infrared radiant energy of an object.

[Fig. 16]

It is a transmission wavelength characteristic figure of a silicon filter.

[Fig. 17]

It is a characteristic diagram which shows the relationship between absolute temperature and radiant energy.

[Fig. 18]

It is a block diagram of a conventional radiation thermometer.

[Fig. 19]

It is a temperature characteristic diagram of the conventional infrared sensor sensitivity.

[Explanation of symbols]

1,70 radiation thermometer, 2 optics, 3a infrared sensor, 3b, 3c temperature sensor, 5,60 arithmetic unit, 5b filter correction means, 16 probe, 20 light guide tube, 30 storage case, 31 reflector, 50 Detection signal processor, 53 Peak hold circuit, 61 Temperature calculation circuit, 63 Zero detection circuit, 64 Sensitivity correction calculation circuit.