JPH0236324A - Cavity type black body for calibrating radiation thermometer - Google Patents

Abstract

PURPOSE:To increase the number of times of reflecting energy in a cavity by projecting the bottom surface of the cavity which faces an opening part toward the opening part. CONSTITUTION:The bottom surface 4 of the cavity 2 is projected toward the opening part 3 and energy which is entered into the cavity 2 through the opening part 3 does not exit unless it is reflected four times by the wall surface in the cavity 2. The energy attenuates every time it is reflected to reduce the influence upon the radiation thermometer RT provided facing the opening part 3 as much as possible. Further, the bottom surface 4 of the cavity 2 is projected toward the opening part 3 to reduce the depth L of the cavity 2 and the tip angle beta at the bottom part can be made large, so the temperature distribution of the bottom surface 4 is easily uniformed and the cavity type black body 1 itself is reduced in size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a hollow body for calibrating a radiation thermometer (hereinafter simply referred to as a hollow body).

[Conventional technology]

As shown in Fig. 4, the cavity of the conventional cavity concrete is (a
) cylindrical shape, (b) conical shape, (C) spherical shape, (d) conical cylindrical shape, (e) double conical shape, (f) cylindrical shape with aperture, etc., the bottom surface 42 of each cavity 41 extends from the opening 43. It was formed to move away.

This is because these shapes are easy to process except for the spherical shape, and the radiation thermometers conventionally used have a narrow viewing angle, so the hollow shape described above was sufficient.

By the way, recently, inexpensive radiation thermometers using thermopiles have come into use, but this type of radiation thermometer needs to receive and absorb a lot of energy for sensitivity, so conventional The viewing angle is wider than that of the

Therefore, based on the above-mentioned idea, if we try to manufacture a cavity suitable for the radiation thermometer with a wide viewing angle, for example in the double cone shape shown in Fig. 4(e), it will be as shown in Fig. 5. , the distance from the opening 52 of the cavity 51 to the bottom surface 53 (
depth) l needs to be large.

[Problem to be solved by the invention]

However, as mentioned above, the depth of the cavity 51! As the temperature becomes larger, the temperature control range on the side wall surface 54 inside the cavity 51 becomes wider in proportion to it, and temperature control becomes that much more difficult, and as shown by the solid line A in FIG.
The energy incident from the outside is applied to the wall surface of the cavity 51.
Due to the second reflection, the incident energy goes out of the cavity 51 through the opening 52, causing the inconvenience that the incident energy cannot be sufficiently attenuated within the cavity 451. or,
Since the depth 2 of the cavity 51 is large, there is also the problem that the hollow male body 5G becomes larger accordingly. In addition, in FIG. 5, RT indicates a radiation thermometer.

The present invention has been made with the above-mentioned considerations in mind, and its purpose is to be able to sufficiently attenuate incident energy from the outside inside the cavity, even though it is small.
Moreover, it is an object of the present invention to provide a hollow black body for calibrating a radiation thermometer whose temperature can be easily controlled.

[Failure to solve the problem]

In order to achieve the above-mentioned object, the cavity-shaped embodiment for calibration of the radiation thermometer according to the present invention is configured such that the bottom surface facing the opening of the cavity projects toward the opening.

[Effect]

According to the above configuration, the number of reflections of incident energy inside the cavity increases, and the incident energy can be sufficiently attenuated inside the cavity. In addition, since the depth of the cavity can be shortened and the tip angle can be increased, the size of the cavity itself can be reduced, and the temperature on the inner wall of the cavity can be easily controlled. Therefore, the above objective is fully achieved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a black body furnace incorporating a hollow black body according to the present invention. It is formed by The cavity 2 formed inside the cavity 2 is formed so that a bottom surface 4 that opposes the opening 3 protrudes toward the opening 3. In the illustrated example, the central portion 4A of the bottom surface 4 is the opening. 3 side, and slope portions 4B on both sides thereof,
4B is formed. This shape is approximately the same as that in FIG. 4(C) with the bottom surface 42 protruding toward the opening 43 side. 5.5 is a side wall surface formed between both ends of the bottom surface 4 and the end of the opening 3. The surfaces of the bottom surface 4 and side wall surfaces 5, 5 are subjected to a blackening treatment to sufficiently increase the reflectance.

The hollow field body 1 configured as described above is attached to the wall surface of the stainless steel inner tank 7 via the flange 6 through the opening 3.
It is installed so that it faces the wall.

The interior of the inner tank 7 is filled with oil 8 to a predetermined depth so as to immerse a hollow black body l therein, and a stirring side t which is rotationally driven by a heater 9 and a motor 10 is provided.
The lill is housed in such a way that it is immersed in oil 8.

12A and 12B are inner lids provided in the inner tank 7, 13 is a stainless steel outer tank, 14 is a heat insulating material provided between the inner tank 7 and the outer tank 13, and 15 is provided on the top of the outer tank 13. It is the outer lid.

A hole 16 is provided to correspond to the opening 3 of the hollow black body 1 and penetrates through predetermined portions of the inner tank 7, the outer tank 13, and the heat insulating material 14. The inside of the cavity 2 of the cavity black body 1 can be measured using the radiation thermometer RT.

FIG. 2 shows the state of energy reflection in the hollow black body l having the above-mentioned internal shape. Since the bottom surface 4 of the cavity 2 protrudes toward the opening 3, the opening can be accessed from the outside of the hollow male body 1. The energy that has entered the cavity 2 through the section 3 is shown by the solid line B.
As shown in the figure, the light does not come out of the cavity 2 unless it is reflected four times on the walls of the cavity 2. By making the bottom surface 4 of the cavity 2 protrude toward the opening 3 side, this produces a cavity effect equivalent to a smaller tip angle (angle α in FIG. 4(e)) of the tip cone. Conceivable.

Therefore, the energy is attenuated each time it is reflected, and the influence on the radiation thermometers R and T provided facing the opening 3 can be extremely reduced.

Furthermore, by making the bottom surface 4 of the cavity 2 protrude toward the opening 3 side, the depth L of the cavity 2 can be reduced, and the tip angle (spreading angle) β at the bottom surface 4 can be increased. The temperature distribution on the bottom surface 4 can be easily made uniform, and the size of the hollow black body 1 itself can be reduced. Most preferably, the cavity 2 is spherical, as shown in FIG. 3. With this configuration, energy can be substantially confined within the cavity 2.

In the embodiment shown in FIGS. 1 and 2 above, the angle formed by the side wall surface 5.5 of the cavity 2 is
Although the viewing angle is larger than the viewing angle, the present invention can also be applied to the cavity 2 where the angle is smaller than the viewing angle if the temperature of the side wall surface 5.5 is adequately controlled. .

〔Effect of the invention〕

As explained above, the hollow blackbody for calibrating a radiation thermometer according to the present invention has the bottom surface facing the opening of the cavity protruding toward the opening, so that energy is reflected inside the cavity. It is possible to increase the number of repetitions, reduce the reflectance of energy coming in from the outside, and even if the finish accuracy of the cavity surface is somewhat poor, it is possible to obtain a high emissivity, so there is no negative effect on the radiation thermometer. This can be reliably calibrated without being affected.

Furthermore, according to the present invention, since the depth of the cavity can be reduced, the shape of the cavity itself can be made smaller, and the expansion angle of the bottom of the cavity can be increased, making temperature control easier. effective.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention, FIG. 1 is a vertical cross-sectional view showing an example of a blackbody furnace incorporating a hollow body according to the present invention, and FIG. FIG. 3 is a diagram showing a state of energy reflection in a cavity inside the body. FIG. 3 is a sectional view showing a hollow body according to another embodiment of the present invention. FIGS. 4 and 5 are diagrams for explaining the prior art. FIG. 4 is a cross-sectional view showing the shape of a conventional cavity-shaped body, and FIG. FIG. 3 is a diagram showing a state of energy reflection in a cavity inside the body. l...Cavity shaped body, 2...Cavity, 3...Opening part,
4...Bottom, RT...Radiation thermometer. Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A hollow black body for calibrating a radiation thermometer, the bottom surface of which faces the opening of the cavity protrudes toward the opening.