Counter control circuit for profile measuring equipment - uses detector output connected to inverting AND gate and has input connected to gate counter

摘要

The counter control circuit is used in conjunction with a laser-operated profile area measuring equipment for determining aerodynamic properties of moving vehicles. The circuit uses the synchronising pulses from the stepping-motor drive as direct timing pulses for the counter gating. The clock pulses (34) are fed to one input of an AND-gate (31). The AND-gate has a second, inverting input (33) which is connected to the output of the photo-detector (28) which responds to the illumination of the laser beam as it scans the object under investigation. When the beam is broken by the object, there is no output from the detector and the AND-gate allows the clock pulses to be registered by the counter. When the detector conducts, the AND-gate is inhibited and the count is frozen.