Patent GB-1096788-A (GB)
Title: Electro-mechanical integrator
IPC: H03M1/00
Filed: 1965-03-30
Abstract: 1,096,788. Integrating circuits. COMPUTING DEVICES OF CANADA Ltd. March 30, 1965 [April 1, 1964], No. 13486/65. Heading G4G. An input signal to be integrated varies in amplitude with time on one side of a zero reference level (Fig. 1, not shown) and is derived from input shaft 28 positioning a wiper of potentiometer 27 (Fig. 2). A clock motor 11 rotates shaft 12 at constant speed to sweep wiper 16 of potentiometer 17 and derive therefrom a sawtooth reference signal varying linearly with time between reference zero and a fixed voltage V. The motor also rotates cam 15 closing contacts 22, once per revolution in a predetermined shaft position and counter 34 through normally disengaged magnetic clutch 14. The signals at wipers 16, 26 are applied to amplifier 25, which develops an output only when the signal from wiper 26 exceeds that from wiper 16, and otherwise a zero output; such output being applied over normally open contacts 31 shunted by normally open contacts 22 to coil 30 operative to close contacts 31, and also contacts 32 operative to energize solenoid 20 of clutch 14. In operation, contacts 22 are momentarily closed at the beginning of a sweep of the reference signal from zero (time t1), and the output of amplifier 25 then energizes coil 30 to hold over contacts 31 until the reference and input signals reach equality (time t2) when coil 30 is de-energized and contacts 31, 32 re-open. The cycle repeats continuously, and the intervals t 1  to t 2 ; t 3  to t 4 ; t 5  to t 7  etc. (Fig. 1, not shown) are proportional to the input signal amplitudes at t 2 , t 4 , t 6  etc. Solenoid 20 is energized and clutch 14 engaged for the successive time intervals t 1  to t 2 ; t 3  to t 4 ; t 5  to t 6  etc. so that the amplifier displacement of shaft 18 measured by counter 34 represents the time integral of the input signal if the period of the reference signal is short relative to that of the input signal. Integration in the opposite direction is obtainable by arranging the clutch to be engaged for time periods t 2  to t 3 , t 4  to t 5 , t 6  to t 7  etc. In a modified bidirectional integrator (Fig. 3, not shown) input and reference resolvers energized by a carrier signal E sin W ct  are rotated respectively by an input signal shaft and a clock motor shaft introducing a rotational reference signal developing a single null for 2# rotation of its associated resolver. The input of the latter modified by introduction of a phase shifted carrier signal through a CR circuit is given by K[(cos w mt - 1) sin (w ct  + α)] + sin w mt  sin w ct  where K is a small fraction and α is a small angle, is demodulated and applied to a flip-flop controlling the energization of the solenoid of a brake coupled through a slip clutch to a clock motor also driving a cam momentarily operating a trigger switch for the flip-flop, once per revolution. A differential gear driving in counter receives mechanical inputs from the motor through a 2 :1 step driven gear directly under control of the slip clutch and brake. The flip-flop is triggered to energize the brake solenoid when the rotational reference signal input to the reference resolver is deviated # from zero, and to de-energize it when the demodulated voltage reaches a preset small value of coincidence between the input and reference signal shafts; the sum of the energization and de-energization times being constant and the ratio thereof varying with the demodulated voltage. The counter is driven one way on energization and the other way on de-energization at half the speed of the clock motor, and as the input shaft rotates to represent values above or below zero the output shaft and counter rotates to represent the time integral of the input. In a further modification (Figs. 4, 5, not shown) an input shaft rotates a synchro energized from a 3-phase reference voltage to develop a voltage whose phase represents the input variable, and a clock motor rotates a further similarly energized synchro to develop a reference voltage of time variable phase. A phase detector pulses when the input and reference voltages are of equal phase to trigger a flip-flop passing or arresting pulses from a frequency source driven from the clock motor to a further flip-flop driving a step motor in one or other direction to rotate a counter. A position detector pulses the flip-flops when the clock motor shaft is positioned at reference angles 0 and #. It is shown that as the input shaft rotates to represent values above or below zero, the counter is driven in forward and reverse series alternately at constant rate for differing time intervals so that its net reaction represents the time integral of the input. The reference signal may vary non-linearly when it is required to integrate a function of the input.