| 摘要 |
PURPOSE:To improve the durability and reliability of a liquid level detection sensor by providing a light guide means atop of an optical fiber and preventing an optical element from contacting liquid. CONSTITUTION:The light guide means 14 which has a refractive index nearly equal to the refractive index of a light level to be measured is arranged atop of the optical fiber 12 in contact with the liquid. The light from a light source 10 is made incident on a directional coupling means 11 and then its reflected light from the means 14 provided to the tip part of the optical fiber 12 is incident on a liquid level measuring circuit 15 through the coupler, so that the liquid level is detected optically. Therefore, optical components dipped in the liquid are small in number, so the durability is improved; and a signal level ratio as to whether or not there is the liquid is settable large, so signal processing is facilitate, malfunction is reduced, and the reliability is improved. |
