GB1396781A - Device for measuring angles - Google Patents

Abstract

1396781 Digital measurement of angles J F DA ROSA TABORDA 3 May 1972 [5 May 1971] 20682/72 Heading G1N To measure the angles subtended at the centre of a continuously rotating disc by two pick-up heads spaced around the periphery sensing the passage of a single peripheral magnetic mark, the signals from the pick-ups gate clock pulses to one or the other of two counters depending on whether the mark is passing in the smaller or the larger of the two arcs defined by the angle of the heads on the disc circumference. As shown in the figure at start-up a pulse from pick-up head L 1 first opens gate 11 so that the following pulse from L2 passes through 11 to open gate 12 and also gate 14 permitting clock pulses from generator GER to pass through open gate 15 and be directed via circuit C2 on the output lead S1 to counter CT1. The next pulse from L1 passes through 12 to switch circuit C2 whereby clock pulses pass from its output S0 to counter CT2 until the next pulse from L2 on passing through I1 and I3 and circuit C1 to output S1 to switch circuit C2 back to passing clock pulses to counter CT1. When counter CT1 reaches a predetermined count it switches circuit Cl so that the next pulse from L2 passes over output S0 to block gate I5 and stop further counting. The ratio of count CT2 to the sum of both counts equals the required angle CAB.