JPH0523702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an apparatus for measuring the emissivity and temperature of an object (object) to be measured such as a steel plate.

[Prior Art] For example, the applicant has
As stated in the publication, a method is proposed to determine the emissivity of the object to be measured from the change in the output of the radiation detector when the distance between the comparison heat plate (auxiliary heat source, radiation source) and the object to be measured is changed. . Alternatively, instead of changing the distance, a method can be considered in which light is projected from different angles and similar calculations are performed from the reflected light to perform measurements.

[Problems to be Solved by the Invention] In this case, if a PbS element is used as a detector, the emissivity, surface condition, etc. of the measurement target will vary greatly, and the PbS element will vary greatly.
If the energy incident on the element becomes excessive, PbS
Due to the nonlinear characteristics of the element input and output, the relationship between the incident light and its output changes from the linear region in Figure 4A to Figure 4B.
There is a problem in that this results in a state in the saturated region, resulting in calculation errors.

In view of the above points, an object of the present invention is to provide a radiation temperature measuring device that limits the maximum input to an element to a region where the linearity of the element is maintained, and that enables high-precision measurement at all times. It is to be.

[Means for Solving the Problems] The present invention provides a light source that emits or receives light at at least two or more predetermined angles with respect to the normal to a measurement position of a measurement object, and a PbS having nonlinear input/output characteristics.
The ratio of the contribution rate, which is the ratio of the difference between each of the two detection signals from light emission and reception at different angles by this detector and the detection signal when no light comes from the light source, is Calculating means that calculates the emissivity based on the difference in contribution rate and a predetermined relationship, and calculates the temperature of the measurement target from this emissivity, and the detector when the maximum light is emitted from the light source. The radiation temperature measuring device is equipped with a control means for controlling the intensity of the light source to be constant based on the output.

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

In the figure, 1 is the object to be measured, 2 is a light source that projects light onto the object 1 at a predetermined angle via a chopper 3 and optical fibers 4 and 5, and 7 is a light source that emits light from the light source 2 to the object 1 to be measured. 8 is a detector 7 made of PbS or the like having nonlinear input/output characteristics as shown in FIG.
It is a calculation means such as an analog circuit, a microcomputer, a personal computer, etc. that performs a predetermined calculation based on the detection signal from the computer. The two tips 41 and 42 of the optical fiber 4 arranged on the same circumference form an angle θ with respect to the normal line of the measurement position P of the measurement object 1 (corresponding to the incident light of the optical fiber 6 for detection in this example). ₁ ,
Two tips 51 and 52 arranged on the same circumference of the optical fiber 5 project the light from the light source 2 at a predetermined angle of θ ₂ . In addition, as shown in FIG. 2, for example, the chopper 3 is provided with outer openings 31, 31 and wide openings 32, 32 alternately, and is rotated by a motor M to turn off the light from the light source 2, and The light period is divided and intermittent, such that the light is emitted only to the inner optical fiber 4 closest to the center, and the light is emitted to both the optical fibers 4 and 5. In addition, each of the optical fibers 4 and 5 includes optical fibers 41 to 42 and 51 to 42, respectively.
52 are tied together, and the light source 2 is provided with a lens L for projecting light. Although not shown, visual field limiting means such as rod lenses and microlenses that limit the visual field are optical fibers 41 to 42 and 51 to 5.
It is provided at the tip of 2 and 6.

Furthermore, the output of the detector 7 when the maximum light from the light source 2 is emitted from the aperture 32 of the chopper 3 is held by the sample and hold means H, and compared with the reference value er by the comparator C, and the output of the transistor Tr etc. The voltage E supplied to the light source 2 via er
The intensity of the light source 2 is controlled to be constant. In this way, the control means 9 including the sample hold means H and the comparator C are configured.

The temperature of the measurement object 1 is T, the emissivity is ε, the radiant energy of the light source 2 is Er, the output signal of the detector 7 is Ei,
Let the ambient temperature be Ta, and the radiant energy equivalent to a blackbody at temperature T be E(T).

A state in which only the radiation energy from the measurement target 1 is detected while being shielded by the chopper 3, a state in which light is emitted from the optical fiber 4 inside the aperture 31 of the chopper 3, and a state in which light is emitted from both optical fibers 4 and 5 by the aperture 32 in the chopper 3. The output signals E ₀ , E ₁ , and E ₂ of the detector 7 in each state of light projection are as follows.

E ₀ = εE(T) + (1-ε) E (Ta) ...(1) E ₁ = εE(T) + g ₁ (1-ε) Er + (1-g ₁ ) (1-ε) E (Ta) ……(2) E ₂ = εE(T)+g ₂ (1−ε)Er+(1−g ₂ ) (1−ε)E(Ta) ……(3) Here, g ₁ , g ₂ is the rate at which the radiant energy from the light source 2 is diffusely reflected by the measurement object 1 and enters the detector 7.

In other words, when there is no light from light source 2, the first term on the right side of equation (1) is the radiant energy from the measurement object 1 itself, and the second term is the temperature Ta of the surrounding wall surface (not shown).
This is the contribution of radiant energy due to The second term on the right side of equations (2) and (3) is the contribution from the light source 2, and the third term is the contribution from the surroundings.

By subtracting equation (1) from equation (2) and subtracting equation (1) from equation (3), the following equation is obtained.

E ₁ −E ₀ =g ₁ (1−ε) Er−g ₁ (1−ε)E(Ta) E ₂ −E ₀ =g ₂ (1−ε) Er−g ₂ (1−ε)E( Ta) Taking the ratio R, the following formula is obtained.

R=(E ₁ −E ₀ )/(E ₂ −E ₀ )=g ₁ /g ₂ (4) Further, by subtracting equations (2) and (3), the following equation is obtained.

E ₂ −E ₁ =(g ₂ −g ₁ )(1−ε) {Er−E(Ta)} From this, the emissivity ε becomes the following formula.

ε=1−( _E2 − _E1 )/[( _g2 − _g1 )・{Er−E(Ta)}]……(5) Here, D= _g2 − _g1 and 3R= _g1 The relationship with /g ₂ is
As shown in FIG. 3, it has been experimentally found that D=f(R), which is a predetermined functional relationship. In other words,
D can be determined from R, and the other values on the right side of equation (5) can be determined by measurement, etc., so the emissivity ε can be determined.

Then, from equation (1), E(T) = {E ₀ − (1-ε) E(Ta)}/ε...(6), so in equation (6), we can calculate from equation (5). By substituting the emissivity ε, etc., the true temperature of the measurement object 1 can be found.

In other words, before the measurement, as shown in FIG. 3, the functional relationship D=
f(R) is stored in the calculation means 8.

Next, when measuring, rotate the chopper 3 and light source 2.
Extinguishing to block the light of the optical fiber 4 from the aperture 31
Light is projected at an angle θ ₁ through the optical fiber 5 from the aperture 32.
Light is projected at an angle θ ₂ through (1), (2),
E ₀ , E ₁ , and E ₂ in equation (3) are detected by a detector 7 through an optical fiber 6 in the normal direction, and the surrounding temperature Tr,
The radiant energy Er of the light source 2 is detected by a temperature detector or the like (not shown) and supplied to the calculation means 8, respectively. Note that the Er of the light source 2 is determined from another photoelectric element or the value of the power supply.

The calculation means 8 calculates the ratio R of equation (4) from the signals E ₀ , E ₁ , and E ₂ , calculates D from this, and calculates the signal Ta.
E(Ta) is calculated, and the right side of equation (5) is calculated to find the emissivity ε. Furthermore, the temperature T of the measurement object 1 can be determined by calculating equation (6) using the emissivity ε.

Then, the output E ₂ of the detector 7 when the light from the light source projected from the aperture 32 of the chopper 3 is at its maximum.
is held by the sample and hold means H of the control circuit 9, compared with the reference value er by the comparator C, and drives the transistor Tr so that the voltage E supplied to the light source 2 is always er, that is, E ₂ = er. The intensity of light emitted from light source 2 is controlled so that Er=f
(er) is controlled so that it is always constant.

As a result, the output of the detector 7 made of a PbS element does not operate in the saturated region shown in FIG. 4B, but in the linear region shown in FIG. There are no particular restrictions on
Stable and highly accurate measurements are always possible.

In addition, by increasing the number of tips of the optical fibers 4 and 5, the projection angle is increased, and 2
It may be divided into blocks and the light supply sides of the fibers 4 and 5 may be tied together. In this case, the number of optical fibers may be further increased to completely fill the light projection surface. Furthermore, the same effect can be obtained even if the optical fibers 4 and 5 are configured to emit light separately instead of emitting light at the same time.

[Effect of the invention] Since emissivity and temperature are measured in advance by using the fact that the difference in contribution rates has a predetermined relationship with the ratio of contribution rates, it is possible to measure emissivity and temperature with a simple configuration. It is possible to measure the temperature of the correct target. Furthermore, since it does not have a heat source, there is no deterioration of the detector etc. due to heat generation, and it does not have large moving parts that move the heat source, so it is small and compact. Moreover, by using an optical fiber, it becomes non-inductive.

In addition, since the intensity of the light source is controlled by the control means based on the detector output when the maximum light is emitted from the light source, the detector output does not saturate and operates in a linear region. , the emissivity of the measured object,
Even if the surface condition etc. fluctuate, it is not affected by this and can always perform highly accurate and stable measurements.

[Brief explanation of drawings]

1 and 2 are configuration explanatory diagrams showing one embodiment of the present invention, FIG. 3 is a diagram of the relationship between the contribution rate difference D and the ratio R, and FIG. 4 is a diagram of the output characteristics of the detector. It is. 1...Measurement object, 2...Light source, 3...Chopper, 4, 5, 6...Optical fiber, 7...Detector,
8...Calculating means, 9...Controlling means.

Claims (1)

[Scope of Claims] 1. A light source with the same radiant energy that projects at two or more predetermined angles with respect to the normal line of the measurement position of the measurement object, and the radiant energy from this light source is reflected from the measurement object and the normal line of the measurement position When a single detector such as PbS, which has nonlinear input/output characteristics, is incident from different directions, and when light is reflected from the measurement target by emitting and receiving light at different angles and enters the detector with contribution factors g1 and g2. Find the ratio of the difference between each of the two detection signals E1 and E2 and the detection signal E0 when no radiant energy from the light source comes, R = (E1 - E0) / (E2 - E0) = g1 / g2, The difference D in the contribution rate is calculated based on the relationship experimentally determined in advance between the ratio R=g2/g1 and the difference D in the contribution rate=(g2-g1), and the difference D in the contribution rate and the temperature sensor are calculated. The emissivity of the object to be measured is determined using the ambient temperature and the radiant energy of the light source determined in By sample-holding the output of the detector and comparing it with a reference value, the output is controlled to be the same as the reference value, and the emission intensity of the light source is controlled to be constant, so that the linearity of the output of the detector is maintained. A radiation temperature measuring device characterized by comprising: a control means for controlling a region where the temperature drops. 2. The radiation temperature measuring device according to claim 1, which emits or receives light through an optical fiber.