| 摘要 |
PURPOSE:To detect a foreign substance to prevent the occurrence of an accident by placing a light source and a condenser in the left side of a clear thin tube that contains fluid and another condenser and a line sensor in the right side of the tube. CONSTITUTION:When a foreign substance such as dust that cuts off the light is mixed in the fluid in the thin tube 3, the value of detection current in the sensor 5 decreases since the quantity of penetrated light is reduced by the dust, and the output Va of the I/V converter 6 is also reduced. Since the output Va becomes less than the lower side reference voltage E2, both outputs V1, V2 of two voltage comparators 7, 8 becomes ''0'' level, and the output V3 of the gate circuit G1 becomes ''0'' level also. Accordingly the output V0 of the inverter G2 is inverted to ''1'' level. As a result, the processing circuit 9 is operated to inform the mix of foreign substance. |
