JPS6219947Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a radiation thermometer that measures the temperature of an object by removing the influence of emissivity.

Conventional radiation thermometers include monochromatic thermometers that measure the temperature of an object based on the amount of radiant energy from the object, and two different types.
There were two-color thermometers that determined the temperature of an object from the ratio of spectral radiant energies of wavelengths. These radiation thermometers can only measure the true temperature of a black body in the case of a monochrome thermometer, and only a gray body in the case of a two-color thermometer, and the influence of emissivity cannot be removed for ordinary objects, which is a major problem. It was hot.

In view of the above points, the purpose of this invention is to provide an improved radiation thermometer that can measure the surface temperature of ordinary objects by removing the influence of emissivity.

The principle of this invention will be explained with reference to FIG. In the figure, 1 indicates an object to be measured with temperature T and emissivity ε, and 2
is set at a predetermined distance from the measured object 1 and emits radiant energy to the measured object 1.
A comparative hot plate 3 with Tc and emissivity εc detects the radiant energy emitted by the object to be measured 1 itself through the opening 2a of the comparative hot plate 2 and the radiant energy of the comparative hot plate 2 reflected from the object to be measured 1. It is a radiation detector.

Let L(λ, T) be the spectral radiant energy luminance emitted from the black body when the wavelength λ and the temperature T, and the measured object 1
When the distance between and the comparison hot plate 2 is , the radiation detector 3
If the output signal is e(), the following equation holds true when the distance is 1 and the emissivity εc of the comparison hot plate 2 is sufficiently close to 1.

e(1)=ε・L(λ,T)+εc(1−ε)L(λ,Tc)・f(1)...(1) The first term on the right side of equation (1) is the object to be measured 1 itself The second term is the contribution of the radiant energy emitted by the comparison hot plate 2, εcL (λ, Tc)
is the contribution of the radiation energy reflected from the object to be measured and incident on the radiation detector 3, and f(1) is the contribution of the radiation energy from the comparison hot plate 2 reflected by the object to be measured 1 and incident on the radiation detector 3. This is a shape factor that indicates the proportion of

Next, the distance between the object to be measured 1 and the comparison hot plate 2 is set to 2.
Then, the following formula holds true.

e(2)=ε・L(λ,T)+εc(1−ε)L(λ,Tc)・f(2)...(2) Subtracting equation (2) from equation (1) gives e(1 )-e(2)=εc(1-ε)・L(λ,Tc)・{f(1)-f(2)}...(3) Therefore, 1-ε=e(1) −e(2)/εc·L(λ, Tc)·{f(1)−f(2)} (4). On this right-hand side, e(1)−e(
2) is a measurable quantity and εc, L (λ, Tc) are known quantities, so if f(1) - f(2) is known, the emissivity ε can be found from equation (3). . By substituting the obtained emissivity ε into the equation (1) or (2), the temperature T of the object to be measured 1 can be determined at all times.

Note that the shape factor f( ) is a quantity that depends only on the geometrical shapes of the object to be measured 1 and the comparison hot plate 2 and their mutual positional relationship, so it may be determined in advance by measurement.

By the way, in cases where the object to be measured 1 has a strong specularity and the aperture 2a of the comparison heating plate 2 is located at the center, even if the radiant energy emitted from the comparison heating plate 2 reflects off the object to be measured 1, the opening does not occur. In order to prevent the temperature from reaching the hole 2a and making it impossible to measure, the comparison hot plate 2 is configured as follows. That is, the opening 2a is provided at a position off the center of the comparative hot plate 2, and the comparative hot plate 2 is moved in an oblique direction at a certain angle θ with respect to the perpendicular direction.

The comparison heating plate 2 may have various shapes, such as a hemispherical inner surface coated with black paint to provide a blackbody condition, or a flat plate.

FIG. 2 is a configuration explanatory diagram showing a more specific embodiment of this invention. In the figure, the object to be measured 1
On the other hand, the comparison heating plate 2 can be moved obliquely at a certain angle θ, and the radiation detector 3 can be moved from the object to be measured 1 through the aperture 2a located off the center of the comparison heating plate 2. It has become possible to detect the radiant energy of Further, the distance between the comparative hot plate 2 and the object to be measured 1 can be changed by a drive mechanism (not shown), and if necessary, it can be moved laterally in the B direction to eliminate the influence thereof. Further, a heater H is provided on the comparative heat plate 2, and its temperature Tc is detected by a temperature detector D such as a thermocouple.
is detected, and the temperature controller 4 controls the heater H to control its temperature. Then, the position signal of the comparison heat plate 2, the temperature signal Tc, and the output signal e() of the radiation detector 3 are input to a calculation unit 5 such as a microcomputer, and the temperature T of the object to be measured 1 as described above is calculated. Control of the movement of the comparison hot plate 2 for measurement, etc., and arithmetic processing are performed, and output signals T, ε, etc. can be taken out from the output terminal 6. Note that all the processing of the temperature control section 4 may be performed by the calculation section 5.

As mentioned above, this idea is based on the changes in the output signal of the radiation detector when the comparative heat plate is moved, and is used to perform arithmetic processing to measure the emissivity and temperature of the object to be measured. In this case, the comparison heating plate is moved diagonally.

Therefore, the influence of the emissivity of the object to be measured can be removed to measure the correct temperature, and even if the emissivity fluctuates, corrections can be made automatically, so it is suitable for always on-line measurements. The temperature of a moving object can also be easily measured. In addition, in the case of metal plates with strong specularity such as steel plates, the distance between the object to be measured and the comparison hot plate can be made sufficiently large, so when measuring running steel plates, etc., fluctuations such as vertical vibrations of the object to be measured can be avoided. Measurements can be made safely even when In addition, since it is not an equilibrium method in which the temperature of the comparison hot plate is matched with the temperature of the object to be measured, high-speed response is possible. Also, any type of radiation detector may be used,
It has excellent effects such as being able to output emissivity and temperature simultaneously. In particular, when measuring highly specular metals, etc., since the comparison hot plate is moved in an oblique direction, the influence of the measurement hole is small and stable and accurate measurements can be made.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the principle of this invention, and Figure 2 is:
FIG. 1 is a configuration explanatory diagram showing an embodiment of this invention. DESCRIPTION OF SYMBOLS 1...Object to be measured, 2...Comparison hot plate, 3...Radiation detector, 5...Calculation unit, 2a...Measurement hole.

Claims (1)

[Scope of utility model registration request] A comparative hot plate having a measurement hole at a position offset from the center and movable in an oblique direction and emits radiant energy to an object to be measured; and radiant energy emitted by the object to be measured itself and reflected from the object to be measured. a radiation detector that detects the radiant energy of the comparative hot plate through a measurement hole of the comparative hot plate;
and a calculation unit that calculates the emissivity of the object to be measured based on a change in the output signal of the radiation detector when the distance between the object to be measured and the comparison hot plate is changed, and measures the temperature of the object to be measured. A radiation thermometer featuring