| 摘要 |
PURPOSE:To correctly measure a liquid level even if the liquid changes in temperature by providing a float for shielding light from a light emitting part at the same degree as a thermal expansion coefficient of liquid with specific gravity larger than 1. CONSTITUTION:Since a level of a float 1 is equal to a light axis of a light emitting part 2a and a light receiving part 3a, light from the light emitting part 2a is shielded by the float 1 to prevent the light receiving part 3a from generating current, resulting in no electric signal sent to a liquid supply control part. Then if condensed water 5 gathers on the float 1 with the liquid temperature dropping to an ambient temperature or lower, the light receiving part 3a senses weak light which transmits through the water 5 and supplies liquid to a liquid tank. A level of the liquid 6 in a liquid introducing pipe 4 connected to the liquid tank rises, so that the float 1 shields the light from the light emitting part 2a. Thus supply of the liquid to the liquid tank stops. Thus even if a liquid level varies with the liquid temperature varied, the float 1 always stays at the liquid level but not differs in position from the liquid level, thereby correctly measuring the liquid level. |
