| 摘要 |
PURPOSE:To avoid the influence of print on a vessel and the like in optically measuring liquid level in a vessel having transparency. CONSTITUTION:To an edge part 3a running up along the vessel wall surface due to surface tension which is around the liquid level of the liquid in vessel 1, light is casted from an upward lighting a source 21 with a specific incident angle theta. An image sensor 22 is arranged in the position to receive the right reflection light reflected with the same angle as the incident light among the light reflected at the edge 3a of the liquid level and a very bright spot is produced by the right reflection light on the sensor surface 22a. This bright spot appears at the position corresponding to the liquid level. Even if a part of it disappears due to the influence of print on the vessel and the like, the liquid level can be exactly measured from other bright points. |
