JPS6041293B2 - radiation thermometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radiation thermometer, and more particularly to a radiation thermometer that can measure the true temperature of steel materials of 100,000 or less in a non-contact manner and with high reliability.

The radiation pyrometry method, which measures the radiant energy emitted from the surface of a heated body such as steel and converts it into temperature, has the characteristic of being able to measure the temperature of the heated body without contact.
The current theoretical system of surface phenomena of objects is still uncertain, while it is inevitable that any measurement equipment currently in use will introduce some fundamental error in temperature indication.

If the object to be measured is a black body, there is no problem as it is fully stated by Planck's law, but in order to measure the surface temperature of a steel material that is not a black body on a factory production line, it is necessary to use the so-called emissivity (in, T).
, wavelength input, temperature T, and the atmosphere between the steel material and the thermometer must be strictly determined for accurate temperature measurement. However, it is nearly impossible to precisely understand the steel production lines at all temperatures, all steel surface conditions, steam waste gas generated from equipment cooling water, etc., and this situation changes from time to time. True temperature measurement is required under extremely adverse conditions. Particularly in places where there are no quality or operational control parameters other than temperature, such as heat treatment lines, radiation temperature measurement using a total radiation pyrometer, a photodetector with a certain band such as silicon Si, lead sulfide PbS, indium antimony lnSb, etc. For example, the American Standards Station (N
We have selected and installed brightness pyrometers with emissivities of 0.653 French and 2.3 French, whose emissivity has been accurately measured by IBmeau of Standard, etc., mainly considering heat treatment temperature and traceability.

In addition, in some cases, multiple thermometers have been installed to improve reliability, but these thermometers inherently produce errors, so if the usage conditions on the line change, the accuracy must be checked and adjusted again under new usage conditions. Requires. On the other hand, two-color thermometers, which have recently become technologically possible, have considerably smaller errors due to the influence of emissivity;
If the input 2) is not constant, measurement errors will still occur.

In addition, since this thermometer is often realized using electronic circuits that are theoretically very complex, if it is installed near the production line, the ambient temperature will be In places where electrical errors are likely to occur due to vibrations, heat generated by internal circuits, etc., and where strict temperature control is required, multiple thermometers must be installed, which is extremely expensive. A decisive disadvantage of installing multiple thermometers to improve reliability is that it is often difficult to view the same location on the steel material being measured from the same angle, so Even when a meter is used, a measurement error of about 100 is unavoidable. The present invention was made to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a radiation thermometer that can obtain extremely reliable measurement results.

The present invention provides a radiation thermometer including a rotating filter having three or more wavelengths that sequentially allows only light of specific wavelengths different from each other to pass among the light emitted from the surface of a salt body to be measured; The temperature between each two wavelengths is calculated sequentially from a single light-receiving element that sequentially receives the light, and the output of the light-receiving element, and if two or more calculated values are within the allowable error range, the average is calculated. The above object is achieved by including an arithmetic processing circuit which outputs a value as a measured temperature, and if it is larger than an allowable error range, outputs it as a measurement abnormality.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In this embodiment, as shown in the attached drawings, out of the light 12 emitted from the surface of the steel material 10, which is the body to be heated, the light of three different specific wavelengths is transmitted. A rotary filter 16 rotated by a motor 4 that sequentially allows light to pass through the rotary filter 6, a single light receiving element 18 that sequentially receives the light that has passed through the rotary filter 6, and the output of the light receiving element 18 being subjected to signal processing. An equalizer amplifier 20 that amplifies to a suitable level, a high-speed analog-to-digital converter (hereinafter referred to as a high-speed AD converter) 22 that converts an analog signal output from the equalizer amplifier 20 into a digital signal at high speed, and the high-speed AD converter 22 Based on the output of the motor 4 and the output of the motor 4 that rotationally drives the rotary filter 6, the light receiving element 1 corresponding to each wavelength range ^,,^2,input 3 of the rotary filter 6 is selected.
8 outputs are input sequentially, and the temperature between each two wavelengths is calculated sequentially. If two or more calculated values are within the allowable error range, the average value is output as the measured temperature. A high-speed digital computing machine 24 using a microcomputer, which outputs a measurement abnormality, and a high-speed digital-to-analog converter (hereinafter referred to as (referred to as a high-speed AD converter) 26, and a display device 2 that indicates or records the output of the high-speed AD converter 26.
It consists of 8. The different specific wavelengths of the rotary filter 16 include the temperature of the steel material 10, which is the object to be measured, and the atmosphere between the steel material 10 and the thermometer, such as infrared rays such as water vapor and carbon dioxide. With reference to the transmittance, a wavelength is selected that substantially satisfies the "gray body" state and provides sufficient sensitivity for the light receiving element 18, for example lead sulfide (PbS).

If the measurement range is 500 to 1000 qo, for example, 2.
Three wavelengths of 0.04 m, 2.30 m, and 2.64 m are suitable. The action will be explained below. The light 12 emitted from the steel material 10 is sequentially measured at wavelengths by the rotating filter 6.
, ^2, and input 3, and the light receiving element 18
is input. The output of the light receiving element 16 is input to a high speed digital arithmetic unit 24 via an equalizer amplifier 20 and a high speed AD converter 22.

At this time, since the high-speed digital arithmetic unit 24 simultaneously receives the synchronization signal 15 from the motor 14 that rotationally drives the rotary filter 16, it can determine which measurement wavelength the output of the high-speed AD converter 22 corresponds to. It is possible to output. The brightness of the light input to the light receiving element 18 corresponding to each of the wavelength ranges ENTER, ^2, and INR 3 is as follows according to Wien's formula. L(in・,T) =Go(^,)C,in,−5exp(1C2/in,T)・
... [1'L (in 2, T) Nigo (in 2) C, in 2-5
exp(1C2/^,T)...SeL 3,T)=do(^3)CI^3 -5eXp(-C2/^3T>-
-With}Here C, 23.74 x 10-12 (W/skin)
C2=1.438 (inhibition K).

Therefore, the brightness ratio of each wavelength is as follows compared to the conventional two-color thermometer.

R. = Trunk zone R2: u# Residential zone R3 = Kanjite'4}, '5), {The brightness ratio R,, R2, R3 of equation 61 is not a function immediately after the radiation fringe rate, but is a function of the emissivity ratio. It is a function of temperature.

However, if the wavelength is selected as described above, the emissivity ratio is 1
．． Since it becomes extremely close to 0, the influence of this emissivity is virtually eliminated, and by knowing the luminance ratios R, , R2, and R3,
Temperatures T in, 2, T in 23, and T in 3 between each wavelength can be calculated. The high-speed digital calculator 24 performs the above calculation and calculates the temperature between each wavelength T^,2, T input 23,
In addition to calculating T^3, each measured temperature T input, 2, T input 2
3. Temperature difference △T,, △T2 for T input 31
, ΔT3 are calculated according to the following formula. IT entry 12-T entry 2
3I: △TI … [7] IT enters Kyouichi T^3
1! △T2 ...{8}IT^'s -T~2
Ini △T3...[9] The high-speed digital calculator 24 calculates these measured temperature differences △T,, △T2, △T3
If two or more of these temperatures are within the allowable error range (for example, 5° C. or less), the average value of these temperatures is output to the high-speed AD converter 26 as the measured temperature To.

Further, if the difference between two or more calculated values is outside the tolerance range, the measured temperature is not output as a measurement abnormality. This self-diagnosis function allows a single thermometer to perform functions that were previously only possible with multiple thermometers, making it possible to obtain extremely reliable measured values. In the embodiment, various calculations are performed using a high-speed digital processing machine such as a dedicated microcomputer.
Measured values with higher precision can be obtained than with conventional analog calculations, and drift in measured values can be eliminated. In addition, since the incident energy from the same field of view is divided by the rotating filter, it is possible to always use the incident energy from the same viewing angle, which is much better than when multiple thermometers are installed separately. This eliminates the need for field of view, angle evaluation, and correction of measured values.

In the above embodiment, the calculation results are immediately displayed on the display device 28, but it is of course possible to use an interface instead of the display device 28 to input the results to other control devices, etc. It is.

As explained above, the present invention is a radiation thermometer.

A rotating filter having three or more wavelengths that sequentially allows only light in different specific wavelength ranges to pass among the light emitted from the surface of the warm body, and the light that has passed through the rotating filter is sequentially received.
The temperature between each two wavelengths is calculated sequentially from a single light-receiving element and the output of the light-receiving element, and if two or more calculated values are within the allowable error range, the average value is output as the measured temperature. , and an arithmetic processing circuit that outputs a measurement abnormality if the error is greater than the allowable error range, allowing for extremely accurate and reliable measurements regardless of environmental conditions such as the presence of water vapor in the measurement atmosphere. It has the excellent effect that the value can be obtained with one radiation thermometer.

[Brief explanation of the drawing]

The accompanying drawing is a block diagram showing the configuration of an embodiment of a radiation thermometer according to the present invention. 10...Steel, 12...Light, 14...
...Motor, 16...Rotating filter, 18...
... Light receiving element, 20 ... Equalizer amplifier, 2
2...High-speed analog-to-digital converter, 24.
. . . High-speed digital arithmetic unit, 26 . . . High-speed digital-to-analog converter, 28 . . . Display device.

Claims (1)

[Claims] 1 A rotating filter with three or more wavelengths that sequentially allows only light in different specific wavelength ranges to pass among the light emitted from the surface of the temperature-measuring object, and a single filter that sequentially receives the light that has passed through the rotating filter. The temperature between each two wavelengths is calculated sequentially from the light-receiving element and the output of the light-receiving element, and if two or more calculated values are within the tolerance range, the average value is output as the measured temperature, and the tolerance error is calculated. A radiation thermometer characterized by comprising: an arithmetic processing circuit that outputs a measurement abnormality if the temperature exceeds the range.