JPS613034A - Air bubble detection sensor - Google Patents

Abstract

PURPOSE:To certainly perform the detection of air bubbles, by holding a light transmissive pipe between a light emitting element and a light receiving element and using a concave lens as the lens in the side of the light emitting element. CONSTITUTION:A light emitting element 12, of which the light emitting surface is made concave so as to be closely contacted with a pipe 2, and a light receiving element 13, of which the light receiving surface is formed into a concave one (may be not necessarily a concave surface) so as to be closely contacted with the pipe 2, are arranged in opposed relationship and pressed to the pipe 2 by proper force. When there is no liquid in the pipe 2, the light emitting from the light emitting element 12 is refracted to the direction separated from the light receiving element 13 except the part in the vicinity of the center line and does not reach the light receiving element 13. Next, when the liquid is present in the pipe 2, the liquid in the pipe functions as a convex lens and, therefore, the light emitting from the light emitting element 12 is almost incident to the light receiving element 13. As a result, the large difference can be generated in the intensity of light incident to the light receiving element by the presence or absence of the liquid and the presence or absence of the liquid or the detection of air bubbles can be performed certainly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor that detects the presence of liquid flowing in a tube that transmits light.

Conventionally, there have been many cases in which it has been necessary to detect the liquid flowing inside the tube, and in the case of the 7m machine, it was necessary to detect air bubbles contained in the liquid and issue an alarm or stop the flow of the liquid. Conventionally, a sensor as shown in FIG. 1 has been mainly used for this purpose.

This is installed in the middle of the pipe through which the liquid flows, as shown in Figure 2 6.
Light emitting element as shown in λ. A tube and a light receiving element 5 are placed so as to face each other with - sandwiched therebetween, and the light receiving element 5 detects the intensity of transmitted light depending on the presence or absence of liquid flowing in the tube. However, with such a structure, the intensity of light is mainly caused by the presence or absence of absorption of light by the liquid, so the present invention was made to solve these problems, especially when detecting highly transparent liquids. As shown in Figure 3, its structure consists of a light emitting element 12 whose light emitting surface is concave so that it comes into close contact with the tube 2, and a light receiving surface which is concave and comes into close contact with the tube 2. The light receiving element 13 is arranged so as to sandwich the tube 2 so as to face each other, and is configured to be pushed against the tube 2 with an appropriate force. 10, ] are the light emitting element 12 and the light receiving element 13, respectively.
It is a support for

According to the above configuration, when there is no liquid in the tube 2 as shown in FIG. 4, the light emitted from the light emitting element is refracted away from the light receiving element except for the part near the center line. However, the light does not reach the photodetector. Next, when there is liquid in the tube 2, the liquid in the tube 2 plays the role of a convex lens, so that most of the light emitted from the light emitting element 12 passes through the light receiving element 1, as shown in FIG.
3. As described above, according to the configuration of the present invention, it is possible to make a large difference in the strength of the light incident on the light receiving element I depending on the presence or absence of liquid, so it is possible to reliably detect the presence or absence of τα bodies or air bubbles. . In the above description, it is assumed that the light receiving element 13 as well as the light projecting element 12 has a concave surface. In this case, the synergistic effect of the lens effect on the light emitting element side and the lens effect on the light receiving element side allows the presence or absence of liquid to be detected most accurately, but only the light emitting element 12 is made concave as shown in FIG. It is clear that the conventional type shown in FIG. 2 can be used with great effect.

In addition, as shown in FIG. 6, the light emitting surface or the light receiving surface of the light emitting element or the light receiving element is not directly processed. By combining it with the conventional type of light emitting/receiving element 20, a concave lens effect is created, creating an S-like shape.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the appearance of a conventional bubble detection sensor. FIG. 2 is a sectional view showing the internal structure of a conventional bubble detection sensor. FIG. 3 is a sectional view showing the structure of the present invention. FIG. 4 is an explanatory diagram showing the path of light when there is no liquid. FIG. 5 is a diagram showing the path of light when there is a tα body. FIG. 6 is a diagram showing a method of constructing a lens. Notebook 1 Figure 2 Figure 6

Claims (2)

[Claims] (1) A tube that transmits light is sandwiched between a light emitting element and a light receiving element,
What is claimed is: 1. A bubble detection sensor for detecting the presence or absence of liquid in a tube using transmitted light, characterized in that a lens on the side of a light emitting element has a concave surface and is configured to be in close contact with the tube. (2) The bubble detection sensor according to claim 1, wherein the lens on the light-receiving element side has a concave surface and is configured to be in close contact with the tube.