JPH0523701B2 - - 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 relatively hot plate (auxiliary heat source,
We have proposed a method for determining the emissivity of a measurement target from changes in the output of a radiation detector when the distance between the radiation source and the measurement target is changed. Another possible method is to project light from different angles instead of changing the distance, perform similar calculations on the reflected light, and perform measurements.

[Problems to be Solved by the Invention] However, the former method has problems such as the need for a large device for driving the comparative hot plate. The latter method has the problem that if the steel plate varies in inclination with respect to the horizontal position, the angles of incidence and reflection change, resulting in measurement errors.

In view of the following points, an object of the present invention is to provide a device that more easily measures the emissivity and temperature of an object.

[Means for Solving the Problems] The present invention comprises a light source that emits light at at least two or more projection angles with respect to the normal to a measurement position of a measurement object, and a detector that receives light from the light source. , the contribution rate ratio, which is the ratio of the difference between each of the two detection signals and the detection signal when no light is coming from the light source, for different light projection angles by this detector has a predetermined relationship with the contribution rate difference. calculation means for determining emissivity based on a certain fact and calculating the temperature of the object to be measured from this emissivity; This is a radiation temperature measuring device that projects light from at least three or more points.

[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. The detector 8, such as a photoelectric element that receives reflected light etc. through the optical fiber 6, is a calculation means such as an analog circuit, a microcomputer, a personal computer, etc., which performs predetermined calculations based on the detection signal from the detector 7. be. Four tips 41, 42, 4 arranged on the same circumference of the optical fiber 4 with respect to the normal to the measurement position P of the measurement object 1 (corresponding to the incident light of the detection optical fiber 6 in this example)
3 and 44 project light from the light source _{2 at a predetermined angle θ 1} , and four tips 51 , 52 , 53 , and 54 arranged on the same circumference of the optical fiber 5 project light at a predetermined angle θ ₂ . Further, the chopper 3 has outer openings 31, 31, wide openings 32, 32, as shown in FIG.
are provided alternately, and when rotated by a motor M, the light from the light source 2 is turned off, the light is emitted only from the inner optical fiber 4 near the normal line, and the light is emitted from both the optical fibers 4 and 5. Intermittent in time division.
Further, the light supply sides of the optical fibers 4 and 5 bind the fibers 41 to 44 and 51 to 54, respectively, 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 for limiting the visual field are provided at the tips of the optical fibers 41-44, 51-54, and 6.

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 radiant energy from measurement target 1 is detected by being shielded by Chotsupa 3, Chotsupa 3
The aperture 31 allows the optical fiber 4 inside the normal
Output signals E ₀ , E 1 , _{E 2 of} the detector 7 in each state: light is emitted from the optical fibers 4 and 5 from the aperture 32 of the chopper 3.
becomes 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 measurement object 1 itself,
The second term is the contribution of radiant energy due to the temperature Ta surrounding the wall surface (not shown), etc. 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 ₂ −E ₀ )/(E ₁ −E ₀ )=g ₂ /g ₁ (4) Furthermore, 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−(E ₂ −E ₁ )/[(g ₂ −g ₁ )・{Er −E(Ta)}] …(5) Here, D=g ₁ −g ₂ and R=g It has been experimentally found that the relationship with ₂ /g ₁ is D=f(R) as shown in FIG. 3, which is a predetermined functional relationship. In other words, D can be found from R, and the other values on the right side of equation (5) can be found through measurements, etc., so the emissivity ε
can be found.

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, the functional relationship D=f between D and R obtained by measurement as shown in FIG.
(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
The light is emitted through the aperture 32 at an angle θ ₁ , and the light is emitted through the optical fiber 5 from the aperture 32 at an angle θ ₂ , respectively (1), (2), (3).
The E ₀ , E ₁ , and E ₂ of the equations are detected by a detector 7 through the optical fiber 6 in the normal direction, and the ambient temperature Tr and the radiant energy Er of the light source 2 are detected by a temperature detector, etc. (not shown). , are 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.

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 simultaneously.

[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. In particular, 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. Furthermore, since the light is emitted from the same circumference, even if the measurement target changes in angle, the increase or decrease in light at the symmetrical position is canceled out, and highly accurate measurement is always possible.

[Brief explanation of the drawing]

1 and 2 are configuration explanatory diagrams showing one embodiment of the present invention, and FIG. 3 is a diagram showing the relationship between the difference D and the ratio R of contribution rates. 1...Measurement object, 2...Light source, 3...Chopper, 4, 5, 6...Optical fiber, 7...Detector,
8... Calculation 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 A detector that detects things incident from different directions, and a detector that detects when the radiant energy from the light source at different projection angles is reflected from the measurement target and incident independently with contribution rates g1 and g2. Ratio of the difference between each of the two detection signals E1 and E2 and the detection signal E0 when radiant energy from the light source is not received R = (E2 - E0) / (E1 - E0) =
g2/g1 is calculated, and the difference D in the contribution rate is calculated based on the relationship experimentally determined in advance between the ratio of contribution rates R = g2/g1 and the difference in contribution rates D = (g1 - g2). It is characterized by being equipped with calculation means for determining the emissivity of the object to be measured using the rate difference D, the surrounding temperature determined by a temperature detector, etc., and the radiant energy of the light source, and calculating the temperature of the object to be measured from this emissivity. Radiation temperature measuring device. 2. The radiation temperature measuring device according to claim 1, characterized in that the light from the light source is sequentially and intermittently projected using a chopper. 3. The radiation temperature measuring device according to claim 1 or 2, which emits or receives light through an optical fiber. 4. The radiation temperature measuring device according to claim 3, characterized in that the light supply sides of the multi-optical fibers arranged on the same circumference are bundled. 5. The radiation according to claim 3 or 4, characterized in that the projection angle of the optical fiber is increased, the beam is divided into two blocks at a certain angle, and the light supply side of the optical fiber is bundled. Temperature measuring device. 6 The supply of light from the light source to the optical fiber is quenched,
Inner block close to normal, 3 of both blocks
6. The radiation temperature measuring device according to claim 5, wherein the radiation temperature measuring device is divided into steps. 7. The radiation temperature measuring device according to any one of claims 1 to 6, characterized in that a field-limiting means such as a gradient index rod lens or a microlens is provided at the tip of the optical fiber.