CIRCUIT FOR PREVENTING FLICKER FAULT OF LIGHT SOURCE IN TROLLEY WIRE INSPECTING AND MEASURING INSTRUMENT

PURPOSE:To surely prevent the generation of an error in measurement data by detecting the flickering width of a sodium discharge tube by a sensor and restarting the scanning of a CCD after delaying the same by as much as the time width of the flickering. CONSTITUTION:The sodium discharge tube by a commercial power source is used for the light source 3 and, therefore, the flickering thereof arises at the time of irradiating an aerial trolley wire 1 with the light source 3 and measuring the sliding width and deviation quantity by the CCD 5. The quantity of the emitted light is then detected by the sensor 10 and the output thereof is adjusted to a suitable level by an AMP 10a and is sent to a comparator 11. The output voltage which does not attain the reference value is counted by a counter 12 to which a prescribed clock signal is applied in the comparator 11. The resulted signal of the time width t2 is inputted to a control circuit 13 and the scanning is stopped. The scanning is then restarted with the delay by the time t2 and, therefore, the generation of the error is surely obviated.