JPS6135493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation temperature measuring method for measuring the temperature of an object to be measured using radiant energy from the object.

Conventionally, radiation thermometers include monochromatic thermometers that determine the object temperature from the amount of radiant energy from the object to be measured, and two-color thermometers that determine the object temperature from the ratio of spectral radiant energy of two different wavelengths. However, since objects have their own emissivity, a monochrome thermometer can only measure the correct temperature of a black body, and a two-color thermometer can only measure the correct temperature of a gray body, which has a constant ratio of emissivity to wavelength. It was difficult to measure.

In view of the above points, it is an object of the present invention to provide a radiation temperature measuring method that can measure the surface temperature of a general object while eliminating the influence of emissivity.

The principle of this invention is as follows.

Let the desired true temperature be T, and the selected three wavelengths λ
The spectral radiant energy for ₁ , λ ₂ , λ ₃ is
E ₁ (λ ₁ , T), E ₂ (λ ₂ , T), E ₃ (λ ₃ ,
T).

Under the blackbody condition, for example, the ratio R ₁₂ of energy for wavelengths λ ₁ and λ ₂ is R ₁₂ = E ₁ (λ ₁ , T)/E ₂ (λ ₂ , T) (1), and λ ₁ , Since λ ₂ is known, equation (1) can be reduced to T
The true temperature can be found as T=f ₁₂ (R ₁₂ )...(2). This is a normal two-color thermometer.

However, in general, the emissivity varies depending on the type of object, conditions, wavelength, etc., and wavelengths λ ₁ , λ ₂ , λ ₃
If the emissivity for each is ε ₁ , ε ₂ , ε ₃ , then (1)
The formula is R ₁₂ ′=ε ₁・E ₁ (λ ₁ ,T)/ε ₂・E ₂ (λ
₂ , T)…(3). The temperature T ₁₂ found from this becomes T ₁₂ = f ₁₂ (R ₁₂ ′) ...(4), and only when ε ₁ = ε ₂ , T = T ₁₂ , which is the correct temperature, and when ε ₁ ≠ ε ₂ , the error is eliminated. arise.

〓〓〓〓
In order to always obtain the true temperature, this invention is performed as follows.

The ratio for the wavelengths λ ₂ and λ ₃ is R ₂₃ ′=ε ₂・E ₂ (λ ₂・T)/ε ₃・E ₃ (λ
₃ , T)...(5), and the temperature _T23 found from this is _T23 = _f23 ( _R23 ')...(6).

The temperatures determined from equations (4) and (6) have predetermined errors ΔT ₁₂ and ΔT ₂₃ from the true temperature T, respectively.
In order to eliminate this error and obtain the true temperature T, the following calculation is performed.

T ₁₂₃ = T ₁₂ + α (T ₁₂ - T ₂₃ )...(7) Substituting T ₁₂ = T + ΔT ₁₂ and T ₂₃ = T + ΔT ₂₃ results in the following.

T ₁₂₃ = (T + △T ₁₂ ) + α (△T ₁₂ − △T ₂₃ ) …(8) In other words, the error of the difference between T ₁₂ and T ₂₃ (△T ₁₂ − △
α should be determined so that T ₂₃ ) and the error ΔT ₁₂ of T ₁₂ with respect to the true temperature T are canceled out. In other words, if we set α=−△T ₁₂ /△T ₁₂ −△T ₂₃ …(10) from the condition of △T ₁₂ + α (△T ₁₂ −△T ₂₃ )=〇 …(9), equation (8) becomes T ₁₂₃ =T (11), which always indicates the true temperature. Note that the following calculation may be performed by modifying equation (7).

T ₁₂₃ =(1+α)T ₁₂ −αT ₂₃ (12) Next, an embodiment of the present invention will be described with reference to FIG. The radiant energy from the measured object 1 is
The light is focused by a condenser lens 2, and the spectral radiant energy of three wavelengths λ ₁ , λ ₂ , _{λ 3} is selectively transmitted through a spectrometer 3 consisting of a rotating sector on which a filter is mounted, a diffraction grating, etc., and is transmitted to a detector. 4 and is converted into an electrical signal. The output signal of this detector 4 is amplified by an amplifier 5, and the synchronization signal of the spectrometer 3 generates the signals ε ₁ E ₁ , ε ₂ E ₂ ,
ε ₃ E ₃ is taken out. The first and second spectral radiant energies ε ₁ E ₁ , ε ₂ E ₂ of the signal separator 6 are subjected to a ratio calculation by the first divider 71 to obtain the equation (3) above.
R ₁₂ ′ is obtained, and the second and third spectral radiant energies ε ₂ E ₂ , ε ₃ , and E ₃ are ratio-calculated by the second divider 72 to obtain R ₂₃ ′ in the above equation (5). are obtained, and the calculation units 81 and 82 calculate T ₁₂ = f ₁₂ in the above equations (4) and (6), respectively.
(R ₁₂ ′), T ₂₃ = f ₂₃ (R ₂₃ ′) and calculate the temperature signal.
T ₁₂ and T ₂₃ are added and subtracted by the above equation (7) in the adder/subtractor 9, and the true temperature signal T ₁₂₃ is obtained from the above equation (11).
(=T) is obtained from the output terminal 10. Note that the adder/subtracter 9 can be easily configured using an operational amplifier.
Alternatively, digital calculation processing may be performed using a microcomputer.

For example, wavelength λ ₁ = 1.75 μm, λ ₂ = 2.05 μm,
λ ₃ = 2.35 μm, T ₁₂₃ = T ₁₂ + 2.5 (T ₁₂ −
T ₂₃ ), as shown in FIG. 2, this method has extremely high accuracy with an error of less than about 1/10 of the true value for each temperature compared to the two-color method. In addition, r ₁₂ and r ₂₃ in the figure are the radiation ratio (ε ₁ /ε
₂ , ε ₂ /ε ₃ ).

As mentioned above, this invention can be applied to three types of objects to be measured.
This is a radiation temperature measurement method that measures the temperature of an object by adding and subtracting the ratio of two spectral radiant energies.

Therefore, the influence of emissivity, which was the greatest weakness of conventional radiation thermometers, can be eliminated, and highly accurate measurements are always possible. In addition, it is as easy to use as a conventional radiation thermometer, easy to maintain and inspect, suitable for on-line measurement, and can be applied to temperature measurements of various objects and a wide range of applications. Further, the emissivity can also be easily determined through calculation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between temperature and error. 1... Object to be measured, 2... Condensing lens, 3... Spectrometer, 4... Detector, 5... Amplifier, 6... Signal separator,
71, 72...Divider, 81, 82...Arithmetic unit, 9...
Adder/subtractor. 〓〓〓〓

Claims (1)

[Claims] 1. Of the radiant energy from the object to be measured, 3
A radiation temperature measurement method characterized by selecting spectral radiant energy corresponding to three or more wavelengths, converting it into an electrical signal, and adding or subtracting the ratio of these selected spectral radiant energies to measure the temperature of the object to be measured. . 2. The claim 1 is characterized in that the ratio of the first or second spectral radiant energy is added or subtracted by multiplying the difference in the ratio of the first and second spectral radiant energies by a constant. The radiation temperature measurement method according to item 1.