| 摘要 |
PURPOSE:To adequately detect a liquid, by providing a light source and a light detector so as to interpose a liquid sending tube therebetween while positioning the light detector at the focus position of a lens formed by the presence of a liquid in the liquid sending tube. CONSTITUTION:LED3 as a light source and a photo-transistor 4 as a light detector are proided in opposed relationship so as to interpose a transparent liquid sending tube 2 made of FEP therebetween. In this case, the liquid sending tube 2 has no light collecting action when a liquid is absent in the liquid sending tube 2 but performs lens action when a liquid L enters the liquid sending tube 2 to collect light from LED3 onto one focus. The photo-transistor 4 is positioned at an almost focal point. Whereupon, the difference of light intensity is generated on the photo-transistor 4 by the presence and absence of the liquid L. By this mechanism, the liquid can be adequately detected even if the attenuation due to the liquid is low. |
