Machine tool displacement control - uses two counters operating independently from phototransistors sensing position of rotating apertured disc

摘要

An electronic vernier is employed to measure displacement in a machine tool in order to control speed or to stop the moving part. Two counters operating independently from one detector provide the control signals. Three phototransistors are located in an enclosure with windows behind a rotating disc also with windows. The transistors are submitted to light and dark as the disc rotates and the signal transitions cause a monostable to generate a pulse. The monostable signals depend on direction and speed of rotation and are applied via gating circuits to provide signals for two counter channels. Each channel has count up and count down signals for the counters.