JPS6058412B2 - radiation thermometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation thermometer that measures the temperature of an object by using radiant energy from the object.

Traditionally, radiation thermometers include monochromatic thermometers that measure the temperature of an object based on the amount of radiant energy from the object being measured, and two different types of radiation thermometers.
Determining object temperature from the ratio of wavelength spectral radiant energy 2
The color thermometer is hot.

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 thermometer that can measure the surface temperature of an ordinary object while eliminating the influence of emissivity.

The principle of this invention is as follows.

Let the desired true temperature be T, and the three selected wavelengths λ,,λ.

,λ. The spectral radiant energy for E, (λ,,T)
,E. (λ2, T), E. (λ., T). Under blackbody conditions, for example, the wavelengths λ,,λ.

The ratio of energy to R12 is E, (λ,,T) R゛"■E.

(λ2, T) ゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜゜ (1), and λ,, λ. is known (1
) is solved for T, and the true temperature is T f, O(R, O
)・・・・・・・・・・・・・・・・・・・・・(2)
It can be found as

This is a normal two-color thermometer. However, in general,
If the emissivity varies depending on the type of object, conditions, wavelength, etc., and the emissivity for wavelengths λ, λ2, and λ3 are E1, E2, and Ea, then equation (1) is ε λ R12'■ ゜ ...・・・・・・・・・・・・・・・
...(3) E2E2(λ2, T).

The temperature Tl2 found from this is as follows, and shows the correct temperature T=Tl2 only when ε1=ε2, and an error occurs when E1 is half ε2.

In order to always obtain the true temperature, this invention is performed as follows.
The ratio to the wavelengths λ2 and λ3 is as follows, and the temperature T23 found thereby is as follows.

The temperatures determined from equations (4) and (6) have predetermined errors ΔTl2 and ΔT23 from the true temperature T, respectively.

In order to eliminate this error and obtain the true temperature T, the following calculation is performed. When Tl2=T+ΔTl2, T23=T+ΔT2PH, it becomes as follows.

In other words, Tl.

, T23 (ΔTl2−ΔT23) and Tl2
α may be determined so that the error ΔTl2 with respect to the true temperature T is canceled out. In other words, from the condition of (8)
The formula is as follows, which always indicates the true temperature.

Note that the following calculation may be performed by modifying equation (7). Next, an embodiment of the present invention will be described with reference to FIG. The radiant energy from the object to be measured 1 is collected by the condensing lens 2
A rotating sector on which the light is focused and a filter is mounted,
Three wavelengths λ1, λ are detected by a spectrometer 3 consisting of a diffraction grating, etc.
The spectral radiation energy of 2 λ3 is selectively transmitted, enters the detector 4, and is converted into an electrical signal. The output signal of this detector 4 is amplified by an amplifier 5, and the signal ε1E1, E2 for each selected wavelength is synchronized with the spectrometer 3.
E2, E, and E3 are taken out. The first and second spectral radiant energies ε1E1 and E2E2 of the signal separator 6 are subjected to a ratio calculation by the first divider 71, and R of the above equation (3) is calculated.
l2'' is obtained, and the second and third spectral radiant energies E
2E2 and ε3E3 are subjected to a ratio calculation by the second divider 72 to obtain R23'' of the equation (5), and the calculation units 81 and 8
2, Tl2=Fl2 in equations (4) and (6) above, respectively.
(Rl.''), T23=F23(R?') to obtain the temperature signal Tl2, T23, which is subjected to addition/subtraction processing by the above equation (7) in the adder/subtractor 9, and the above equation (11) is true. A temperature signal Tl23 (=T) is obtained from the output terminal 10.The adder/subtractor 9 can be easily configured using an operational amplifier, or may perform digital calculation processing using a microcomputer.For example, the wavelength λ1= 17.5 μM, λ2=
2.05μTn, λ3 = 2.35μm, Tl23
=Tl. +2.5 (Tl2-T23), as shown in Figure 2, this method has extremely high accuracy with an error of about 1110 or less from the true value for each temperature compared to the two-color method. . Note that Rl2 and r23 in the figure represent the emissivity ratio (ε11E2, E2h3). As described above, the present invention is a radiation thermometer that measures the temperature of an object by adding and subtracting the ratios of three spectral radiant energies of the object.

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, and suitable for on-line measurement, and can be applied to temperature measurements of various objects and a wide range of applications. Furthermore, the emissivity can be easily determined through calculation.

[Brief explanation of the drawing]

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

Claims (1)

[Scope of Claims] 1. A spectrometer that selectively transmits spectral radiant energy corresponding to at least three wavelengths of radiant energy from a position to be measured; a detector that converts the output signal into a signal, an amplifier that amplifies the output signal of this detector, a signal separator that separates and extracts the output of this amplifier for each of the selected wavelengths, and a ratio that takes the ratio of the output signal of this signal separator. It is characterized by comprising a calculator, a calculator that converts the output signal of the divider into a temperature signal, and an adder/subtracter that adds and subtracts the output signal of the calculator, and measures the temperature of the object to be measured. Radiation thermometer. 2 For the ratio of the first or second spectral radiant energy,
2. The radiation thermometer according to claim 1, further comprising an adder/subtractor that adds or subtracts the difference between the ratios of the first and second spectral radiant energies by multiplying it by a constant.