JPH0367135A - Radiation thermometer - Google Patents

Abstract

PURPOSE:To allow correct temp. measurement even in the process of oxidation of a material to be measured of fluctuating emissivities by making temp. measurement in accordance with the max. output among the outputs corresponding to the wavelengths of detectors with a measuring means. CONSTITUTION:The measuring means 7 decides, computes and outputs the signal for the wavelength to provide the max. output with which the emissivity is nearly 1 and which is high in indicated value and is approximate to the true temp. among the outputs of the detectors 41, 42 with respect to the plural wavelengths separated by a separating means 3, such as rotating sector as a temp. signal. The correct temp. measurement is possible even in the process of the oxidation of the material to be measured by such multiwavelength measurement. The measurement is first carried out on the short wavelength side and the measuring wavelength is successively switched to the long wavelength side and the measurement is made when the indication on the short wavelength side comes to change even if the indication on the long wavelength side by the growth of the oxide film is slightly low and remains stable. The stable temp. measurement in the process of the oxidation of a steel sheet, etc., is then executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a radiation thermometer that measures the temperature of an object in a non-contact manner.

[Prior Art] Conventionally, radiation thermometers that measure the temperature of a measured object in a non-contact manner are known as thermometers.

[Problems to be Solved by the Invention] However, if the emissivity of the object to be measured is unknown, it is difficult to accurately measure the temperature. Particularly when measuring the temperature during the oxidation process of steel plates, etc., the oxide film thickness may increase due to the growth of the oxide film. The temperature changed and the emissivity fluctuated greatly, making it difficult to measure the temperature.

In view of the above points, an object of the present invention is to provide a radiation thermometer that can measure temperature with sufficient accuracy even if there is a fluctuation in emissivity due to changes in oxide film thickness during the oxidation process of the object to be measured. It is to be.

[Means for Solving the Problems] The present invention separates radiant energy from an object to be measured into a plurality of wavelengths using a separating means, detects the radiant energy for each separated wavelength with a detector, and uses a measuring means to detect the radiant energy of each separated wavelength. This is a radiation thermometer that measures temperature based on the maximum output among the outputs corresponding to the wavelength of this detector.

[Embodiment] FIG. 1 is a configuration explanatory diagram showing an embodiment of the present invention.

In the figure, 1 is an optical system such as a lens that condenses the radiant energy from the object to be measured, 21 and 22 are half mirrors or mirrors as a branching means for branching the light from the optical system (2), and 3 is a branching means 21 .22 is a separating means such as a rotating sector for separating and extracting light of a plurality of wavelengths through a plurality of filters 31, 32, 33, and 34 having different transmission wavelengths; 41.42 is a separating means; Detector 3 detects the radiant energy of each wavelength separated and converts it into an electric signal; 6 is a synchronous detector that converts the output signals of the detectors 41 and 42 into a synchronous signal corresponding to each wavelength of the separating means 3; Separation and amplification means 7 separates and amplifies the output of the means 5 and extracts output signals corresponding to each wavelength; 7 is a separation and amplification means 6;
It is a measuring means that performs processing such as selecting the maximum value (peak value) from the output of and outputting it as a temperature value to measure the temperature.

Further, the output of the measuring means 7 is indicated to an indicator 8 or the like.

In addition, in the case of only one detector 41, the half mirror 21 and mirror 22 of the branching means can be omitted.

By the way, it is known that during the oxidation process of steel plates and the like, an oxide film grows on the surface of the steel plate, and as the oxide film grows, the oxide film changes, causing a drastic change in the spectral emissivity.

For example, as can be seen from the relationship between the measured wavelength λ and the spectral emissivity ε for iron Fe in Figure 2, when the oxide film thickness d=o, the emissivity monotonically decreases as the wavelength increases. However, as the oxide film grows, the emissivity ε on the short wavelength side increases rapidly, and changes oscillatorily and decreases toward the long wavelength side, approaching a constant value.

In general, radiation thermometers are affected by emissivity, so
In practice, the correct temperature is measured with a thermocouple, etc., the emissivity is measured, and the emissivity is corrected. However, in the oxidation process described above, the emissivity changes drastically, making correction difficult, and it is difficult to make a stable measurement. Difficult to measure.

Therefore, if the measurement wavelengths of short wavelength λ1 and long wavelength λ2 are selected in FIG. 2 and measurements are made during the oxidation process of the object to be measured, as the oxidation progresses, measurements and instructions as shown in FIG. 3 are obtained.

In other words, as the oxide film grows, the short wavelength λ first.

The indication on the side rises rapidly, passes through the peak value, moves like a damped oscillation, and settles down to a constant value, but at this point, the long wavelength λ
There is no change in the 2-open instruction (process from B to D). Furthermore, if the temperature T of the object to be measured changes, the short wavelength λ1 and the long wavelength λ2
In both cases, the indication changes simultaneously (process A), and at the peak point of indication at short wavelength λ1 (C), the emissivity is
Point 1 indicates the true temperature.

From the above, in FIG. 1, among the outputs of the detectors 41 and 42 for a plurality of wavelengths separated by the separating means 3 such as a rotating sector, the emissivity ε is close to 1 in FIG. In FIG. 3, the measuring hand Pi6 determines, calculates, and outputs a signal for a wavelength having a high indicated value and a maximum (peak) output close to the true temperature as a temperature signal. This multi-wavelength measurement enables accurate temperature measurement even during the oxidation process of the object to be measured.

In addition, in general, the effect of emissivity is that the shorter the measurement wavelength, the higher the so-called n value, and the effect can be reduced, so measurements with higher accuracy can be achieved by measuring at shorter wavelengths (Temperature Measurement, 188 /189, Society of Instrument and Control Engineers (19
81) etc.).

Therefore, first measure at the short wavelength side, and if the indication at the short wavelength side starts to change due to the growth of the oxide film, even though the indication at the long wavelength side is low and stable, then the measurement wavelength If you measure by sequentially switching to the long wavelength side,
Stable temperature measurement can be performed during the oxidation process of steel plates, etc.

In this case, at the peak of the indication on the short wavelength side, it indicates almost the true temperature, so the emissivity is determined from the ratio of the indication value on the short wavelength side and the indication value on the long wavelength side at this time, and based on this emissivity, If you apply emissivity correction to the measured value on the side, you will get the correct measured value.

FIG. 4 shows the main part of another second embodiment of the present invention. The radiation energy from the object to be measured is converted into multi-wavelength light by a separating means 30 consisting of a spectroscopic means such as a prism or a diffraction grating. A detector 40 such as an image sensor including multiple elements simultaneously detects light of multiple wavelengths, and a measuring means 7 performs the above-mentioned predetermined measurements and calculations to measure the temperature.

FIG. 5 shows a main part of another third embodiment of the present invention, in which the radiant energy from the object to be measured is transmitted through a large number of mirrors 21.
．． 22, and separated by a separating means consisting of filters 31, 32, 33, 34 having different transmission wavelengths, the multi-wavelength lights are sent to detectors 41, 42, . ．．
43 and 44, and the measuring means 7 performs the above-mentioned predetermined measurements and calculations based on each output signal to measure the temperature.

[Effects of the Invention] As described above, the present invention measures temperature from the maximum value based on light of multiple wavelengths, so even in the oxidation process of the object to be measured whose emissivity fluctuates, Accurate temperature measurement becomes possible.

[Brief explanation of drawings]

1, 4 and 5 are configuration explanatory diagrams showing one embodiment of the present invention, and FIGS. 2 and 3 are relationship diagrams for explaining the operation. 1...Optical system, 21.22...Mirror (branching means)
, 3.30...Separation means, 31-34...Filter, 41-44.40...Detector, 5...Synchronization detection means, 6...Separation amplification means, 7...Measurement Means, 8...
・Indicator and 4 figures

Claims (1)

[Claims] 1. A separating means that separates the radiant energy from the object to be measured into multiple wavelengths, a detector that detects the radiant energy of the multiple wavelengths by this separating means, and a maximum output of this detector corresponding to the wavelength. A radiation thermometer comprising a measuring means for measuring temperature based on the output of the radiation thermometer.