| 摘要 |
PURPOSE:To accurately measure a flow rate, by a method wherein the passage of a flowing body is detected by a light receiving member by blocking, light- decreasing or reflecting the light emitted from a light emitting member by the flowing body going around in a flow passage in the state carried by a liquid. CONSTITUTION:A light emitting member 19 is composed of a light emitting diode and arranged on the optical axis of a convex lens 14. A light receiving member 20 is arranged on the optical axis of a concave lens 15 so as to be opposed to the light emitting body 19 across a flow passage 13. In this case, the flowing body received in the passage 13 flow through the flow passage 13 along with a liquid and repeatedly goes around in the flow passage 13. Therefore, the light emitted from the light emitting member 19 is blocked by a flowing body 18 at each time when the flowing body 18 passes between the light emitting member 19 and the light receiving member 20 and a signal is intermittently outputted from the light receiving member 20. Therefore, when the cycle of said signal and a pulse per unit time are measured by an operation circuit, the flow rate of the liquid passing through the flow passage 13 can be accurately detected.
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