| 摘要 |
PURPOSE:To obtain a detector with a higher reliability while requiring no adjustment by arranging a light emitting section on one of opposed side walls of a water introduction case and a light receiving section at the other thereof in such a manner as to be inclined downward. CONSTITUTION:Water in a washing tank is introduced into a water introduction case 10 made up of a light shielding material and a water level in the case 10 varies with a change in the water level within the washing tank. A light emitting element 14 comprising a light emitting diode and a light receiving element 15 comprising a photo transistor are arranged on cylindrical element holders 12 and 13 provided on opposed walls 10a and 10b of the case 10 as being inclined downward. Then, light leaving the light emitting element 14 is reflected on a water surface in the case 10 to be incident into the light receiving element 15. A control section 16 which comprises a drive circuit 17 for driving the light emitting element 14, a signal processing circuit 18 for converting an electrical signal from the light receiving element 15 into a voltage to be outputted and a rate of change detecting circuit 19 for outputting a water level detection signal detects a rate of change in an output voltage from the circuit 18 when an intensity of light received with the light receiving element 15 reaches its maximum to output a water level detection signal. |
