| 摘要 |
PURPOSE:To sense accurate liquid level at all time by furnishing at the liquid level a reflex board elevating and sinking plumbly, receiving a light receipt signal, adjusting the light emission angle of a light projection part in accordance with the light incident condition on a light receiving part, and thereby measuring the light emission angle at the light projection part. CONSTITUTION:In the steady state, the light emitted by a light projection part 3 is reflected by a reflex board 2 and cast onto a light receiving part 4 in its position between light receiving elements (a, b). Therein a motor driving circuit 6 remains with no signal feeding, and no rotate command is given to a motor 7. Thus a potentiometer 8 is at a standstill, and the current light level is indicated. If the liquid level sinks, for example, while the light emission angle of the light projection part 3 remains unmoved, the reflex board 2 displaces down, and the reflected light in put incident to the lefthand element (a). Therein a leftwise rotate signal is given to the motor 7 from the driving circuit 6, and the light projection part 3 turns counterclockwise, and the motor 7 stops when the reflected light is incident between the elements (a, b). At this time, a meter 8 will show the liquid level in sunk position. Accordingly, accurate liquid level is obtainable only by measuring the light emission angle at the time. |
