Analog or digital optical detection system - uses LED's transmitting light to photodiodes in differential amplifier circuit providing output to analog=digital converter

摘要

The system includes light emitting diodes arranged in a lens structure to provide beams of light incident upon photodiodes. The photodiodes are connected in the input circuits of differential amplifiers which also receive a standard voltage derived from a supply by means of a potential divider circuit. The outputs for the differential amplifiers are fed to a further differential amplifier which provides an analogue output signal at a terminal. This may control an electromagnetic relay. The circuit includes changeable contacts so that its operating characteristics may be adjusted to suit particular requirements. The system is partic. intended for security and the detection of broken strands in weaving and knitting machines.