| 摘要 |
PURPOSE:To securely detect dust passing through an in-tube air passage by providing one photosensors composed of a light emission body and a light reception body and two convex lenses. CONSTITUTION:A 1st and a 2nd convex lenses 11 and 12 are provided, the light emission body 13 is provided on the outside focus F1 of the lens 11, and the light reception body 14 is provided at the outside focus F2 of the lens 12. Then, light emitted by the light emission body 134 is refracted in passing through the lens 11 to become parallel light 15, which passing through the lens 11 to become parallel light 15, which passes through the in-tube air passage without any gap. This parallel light 15 is refracted again and converged by the lens 12, and projected on the light reception surface of the light reception body 14. Therefore, when dust 10 passes through the air passage 6, part of the parallel light 15 which is emitted by the light emission body 13 to reach the light reception body 14 is cut off by the dust 10 and the photodetection quantity of the light reception body 14 decreases, so that a current generated by the light reception body 14 decreases. Variation of the fine current generated by the light reception body 14 is detected and displayed and it is confirmed from the display state that the dust 10 does not pass through the air passage 6 any more, thereby recognizing the end of cleaning. |
