| 摘要 |
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. |
