Photoelectric pick=up to locate point in rotating field - has sensor unit with light and dark areas with position determined by phase shifts relative to peripheral double track areas

摘要

The photoelectric system for astro-navigation is used to measure the position of a point in an X-Y co-ordinate field and employs a rotating sector plate with a photoelectric receiver (16) to produce a signal from a central region divided by two spiral boundary lines into light and dark zones, and two peripheral pick-up units (30, 31) from a double track edge. The peripheral units (30, 31) may be photo-electric, magnetic, capacitive or inductive. - In the electronic processing circuit, each peripheral pick-up is connected to an amplifier (32, 33) and a phase shifter (20, 24), followed by a further phase shifter (22, 27) and a rectifier (21). The latter returns a signal through an integrating amplifier (19) to the first phase shifter (20). - The photo-electric receiver signal is amplified (17) and demodulated (18, 23), with one branch signal appearing at a rectifier (25) to determine the other co-ordinate, a signal being returned through a second integrating amplifier (26) to determine the second co-ordinate.