JPH0547401Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a curved prism type liquid refractometer, particularly to a holder structure for a curved prism.

[Conventional technology]

In general, a curved prism liquid refractometer is basically constructed as shown in Figure 3, in which light emitted from a light emitting diode (LED) 1 passes through a liquid 2 with a refractive index n ₁ and is then curved. It reaches the curved prism surface 3a of the prism 3, where the refractive index n ₂ (known) of the curved prism 3 and the refractive index of the liquid 2
Based on n ₁ , the light is refracted according to Snell's law, and further passes through the curved prism 3 and enters the light receiving surface 4 a of the photodiode (PD) 4 .

Thus, on the light receiving surface 4a of PD4, LED1
A bright area where light from the LED 1 is incident and a dark area where no light from the LED 1 is incident are generated, and the bright/dark boundary line is formed by the light incident tangentially to the prism surface 3a and the prism of the curved prism 3. It extends parallel to the longitudinal direction of the surface 3a. Therefore, since the refraction angle θ ₀ of light incident tangentially to the prism surface 3a is determined by the value of the refractive index n ₁ of the liquid 2, the light receiving surface of the PD 4 is determined according to the value of the refractive index ₁ . The bright/dark boundary line on 4a moves in the direction of the arrow X in Figure 3, and the PD4 outputs a current that is approximately proportional to the amount of light it receives, so by measuring this current, the position of the bright/dark boundary line can be obtained. Thus, the refraction angle θ ₀ is determined based on the position of this bright-dark boundary line, and the refractive index n ₁ of the liquid 2 is calculated using the following formula, sin (π/2)/sin θ ₀ = n ₂ /n ₁ . .

Here, in such a curved prism liquid refractometer, the curved prism surface 3a and both side surfaces of the curved prism 3 are exposed to the outside. When inserting the curved prism 3 into a narrow hole to measure the specific gravity of a liquid, etc., the prism surface 3a and both sides of the curved prism 3 may be damaged due to actions such as touching the curved prism 3 against the battery case. These scratches cause diffuse reflection of incident light when measuring the refractive index of the liquid, making it impossible to accurately measure the refractive index of the liquid.

For this reason, for example, the application filed by the present applicant in 1983-
A holder structure for a curved prism liquid refractometer disclosed in No. 136822 has been proposed.

According to this, the curved prism type liquid refractometer 10 is constructed by incorporating an LED 1, a curved prism 3, and a PD 4 into a holder 11, as shown in FIG. The optical positional relationship of the LED 1, curve prism 3, and PD 4 is the same as that of the conventional curve prism type liquid refractometer shown in FIG. In this case, the holder 11 has side walls 11a, 11b extending upwardly along both side surfaces 3b, 3c of the curved prism 3 and beyond the curved prism surface 3a.

According to such a configuration, when measuring the refractive index of a liquid, the light emitted from the LED 1 is reflected by the curved prism surface 3a of the curved prism 3, as in the conventional curved prism type liquid refractometer. The light is refracted according to the law, passes through the curved prism 3, reaches the light-receiving surface of the PD4, and detects the amount of light received by the PD4, thereby determining the position of the bright-dark boundary line on the light-receiving surface of the PD4. , the refractive index n ₁ of the liquid 2 is calculated by determining the refraction angle of the light incident from the LED 1 in a tangential direction to the prism surface 3a of the curved prism 3. Here, both side surfaces 3b and 3c of the curved prism 3 are covered and shielded from light by the side walls 11a and 11b of the holder 11, so that no external disturbance light enters from these both side surfaces 3b and 3c, and Therefore, the refractive index of the liquid can be measured accurately. Furthermore, even when the curved prism type liquid refractometer 10 is inserted into a narrow hole for measuring the specific gravity of battery liquid, the prism surface 3a and both side surfaces 3 of the curved prism 3 are
b, 3c are the side walls 11a, 11b of the holder 11
Since these surfaces 3a, 3 are protected by
Diffuse reflection does not occur due to scratches b and 3c.

[Problem that the invention attempts to solve]

However, when the holder 11 with the above configuration is used, when the curved prism liquid refractometer 10 is inserted into the liquid, the side wall 11 of the holder 11
a, 11b and both sides 3b, 3 of the curved prism 3
between c (part A in Figure 5) and the LED of the holder 11.
Air bubbles may enter between the mounting surface and the tip of the prism surface 3a of the curved prism 3 (section B in FIG. 4), and these air bubbles may form a narrow gap.
Since it is in part B of Figure 5 and part A of Figure 5,
It cannot be easily removed. Therefore, due to these bubbles, the light from the LED 1 does not properly enter the curved prism 3, causing measurement errors, and especially if the bubbles enter part B in Figure 4, the measurement will be greatly affected. This will cause errors.

[Purpose of invention]

In view of the above points, it is an object of the present invention to provide a curved prism type liquid refractometer that prevents air bubbles from adhering to the curved prism surface and both side surfaces of the curved prism.

[Means and actions for solving problems]

The above object, according to the present invention, includes a curved prism, a light emitting element disposed near the tip of the curved prism surface of the curved prism, and a light emitting element disposed opposite to the exit surface at the rear end of the curved prism. A curved prism type liquid refractometer comprising a curved prism, a light-emitting element, and a light-receiving element, in which a portion of the holder for supporting the curved prism, the light-emitting element, and the light-receiving element faces a side surface of the curved prism is cut out, This is achieved by configuring the light emitting element mounting surface of the holder, which faces the tip of the curved prism, to include a protrusion that comes into contact with the tip of the curved prism.

According to this invention, since both sides of the curved prism are opened by the notches of the holder, air bubbles do not adhere to both sides, and the tip of the prism surface of the curved prism is not exposed to the light emitting element of the holder. Since it comes into contact with the protrusion provided on the mounting surface, air bubbles will not adhere to the vicinity of the tip of the prism surface of the curved prism, and therefore the light from the light emitting element will not be obstructed by air bubbles and the curved prism can be properly mounted. This makes it possible to accurately measure the refractive index of the liquid.

〔Example〕

Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings.

1 and 2 show an embodiment of a curved prism type liquid refractometer according to the present invention, and this curved prism type liquid refractometer 20 has an LED 1, a curved prism 3 and a PD 4 as shown in the figure. It is constructed by being incorporated into the holder 21. The optical positional relationship of the LED 1, curve prism 3, and PD 4 is the same as that of the conventional curve prism type liquid refractometer 10 shown in FIG.

The back surface of the curved prism 3 is fixed to the holder 21 by an appropriate method such as adhesive. The holder 21 has both sides 3b of the curved prism 3,
3c is cut out (see Fig. 2), and a mounting surface 21a of the LED 1 facing the tip 3d of the curved prism 3 of the holder 21 is cut out.
A protruding portion 21b is formed to abut against the tip 3d of the curved prism 3.

The embodiment of the present invention is configured as described above.
When the curved prism type liquid refractometer 20 is inserted into the liquid, both sides 3b, 3 of the curved prism 3
c is open by the notched portion of the holder 21, so air bubbles will not adhere to both side surfaces 3b and 3c, and the tip 3d of the curved prism 3 is used to attach the LED 1 of the holder 21. Since it is in contact with the surface 21a, no air bubbles will adhere to the tip 3d, so when measuring the refractive index of the liquid, the light emitted from the LED 1 can be used similarly to the conventional curved prism type liquid refractometer. The light reaches the curved prism surface 3a of the curved prism 3 without being obstructed by bubbles, where it is refracted according to Snell's law, passes through the curved prism 3, reaches the light receiving surface of the PD 4, and is received by the PD 4. By detecting the amount of light, the position of the bright/dark boundary line on the light-receiving surface of the PD 4 is determined, and from this, the refraction angle of the light incident from the LED 1 in the tangential direction to the prism surface 3a of the curved prism 3 is determined. Refractive index of liquid 2
n ₁ can be calculated.

Note that even when the curved prism type liquid refractometer 20 is inserted into a narrow hole for measuring the specific gravity of battery liquid, the prism surface 3a and both side surfaces 3b and 3c of the curved prism 3 are attached to the holder 21.
Since the surfaces 3a, 3b, and 3c are protected by the enlarged portions near both ends, they will not be damaged during operation, and therefore, there will be no occurrence of diffused reflection due to scratches on these surfaces 3a, 3b, and 3c.

[Effect of idea]

As described above, according to the present invention, there is provided a curved prism, a light emitting element disposed near the tip of the curved prism surface of the curved prism, and a light emitting element disposed opposite to the exit surface at the rear end of the curved prism. In a curved prism type liquid refractometer consisting of a curved prism, a light-receiving element, and a holder for supporting the curved prism, the light-emitting element, and the light-receiving element, a portion facing the side surface of the curved prism is cut out. , and since the light emitting element mounting surface of the holder opposite to the tip of the curved prism is formed with a protrusion that comes into contact with the tip of the curved prism, both sides of the curved prism are opened by the notch of the holder. Since the tip of the prism surface of the curved prism comes into contact with the protrusion provided on the light emitting element mounting surface of the holder, the prism surface of the curved prism There are no air bubbles attached near the tip. Therefore, the light from the light emitting element is not obstructed by air bubbles and properly enters the curved prism, and furthermore, the prism surface and both side surfaces of the curved prism are protected by the portions of the holder located before and after the curved prism. Because it is protected by
The curved prism will not be damaged by hitting a battery case or the like. Therefore, diffuse reflection of incident light due to scratches on the prism surface or both side surfaces of the curved prism is effectively prevented, thereby making it possible to accurately measure the refractive index of the liquid.

Thus, the present invention provides an extremely excellent curved prism type liquid refractometer that can accurately measure the refractive index of a liquid without causing air bubbles to adhere to the curved prism surface or both sides of the curved prism. will be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical sectional view of an embodiment of a curved prism liquid refractometer according to the present invention, and FIG. 2 is a sectional view taken along the line -- in FIG. Fig. 3 is a schematic side view showing the configuration of a conventional curved prism type liquid refractometer, Fig. 4 is a longitudinal sectional view showing a specific example of a conventional curved prism type liquid refractometer, and Fig. It is a sectional view taken along the line - in the figure. 1... LED, 2... Liquid, 3... Curved prism, 4... PD, 20... Curved prism type liquid refractometer, 21... Holder, 21a...
LED mounting surface, 21b... protruding part.

Claims (1)

[Scope of utility model registration request] A curved prism comprising a curved prism, a light-emitting element disposed near the tip of a curved prism surface of the curved prism, and a light-receiving element disposed opposite the exit surface at the rear end of the curved prism. In the type liquid refractometer, the holder for supporting the curved prism, the light emitting element, and the light receiving element has a cutout in a portion facing the side surface of the curved prism, and a portion facing the tip of the curved prism of the holder. 1. A curved prism type liquid refractometer, wherein the light emitting element mounting surface is provided with a protrusion that comes into contact with the tip of the curved prism.