Patent GB-1450461-A (GB)
Title: Electronic watch with electro-mecahnical indication provided with  means for correction for minor deviations
IPC: G06F1/14
Filed: 1974-01-29
Abstract: 1450461 Electronic watches BERNARD GOLAY SA 29 Jan 1974 [1 Feb 1973] 04077/74 Heading G3T An electronic watch comprising a crystal controlled oscillator followed by a frequency divider and an electro-mechanical time indicating arrangement (e.g. including a stepping motor coupled to an indicator via a gear train, or a spring drum driven generator synchronized to an electronic circuit, or a balance wheel motor, is provided, with an arrangement for correcting minor deviations in the time indicated from the correct time, (e.g. within 30 secs of correct time), which arrangement may be combined with or apart from the normal time setting and correcting means of the watch. In Fig. 2 a stepping motor 13 receives pulses at 2Hz from a frequency divider 2 via an AND gate 9 and pulse shaper 12. The correction arrangement includes a reference counter B which receives pulses at 1Hz derived from the divider via a binary counter 3, and an identical counter A which receives pulses at 2Hz and via the gate 9 and in synchronizm with those applied to the motor. Thus with each step of the motor the counter A advances one unit. The numerical difference between the two counters is detected by a phase comparator 6 and exclusive OR gates 7, 8. When A leads B the output of Ex-OR gate 8 blocks gate 9 so that the counter A and motor 13 no longer receive the 2Hz drive pulses, while counter B continues to advance until B=A. If A lags B then since it receives pulses at twice the rate of those received by B, it will rapidly catch up on B until A=B, whereupon A stops advancing until B leads again so that synchronization between the counters A, B and with the motor 13 and time display occurs. Thus when the second hand passes over position 00 the counters A + B will be at zero. SETTING Setting to correct minor deviations is effected by closure of a reset switch of counter B at the instant of a time signal, without having recourse to main setting facilities (not described). If counters A + B and the second hand are in the 15sec position and the reset switch is closed to reset B to 00, the comparator-detector will react by stopping the motor 13 and counter A, (since gate 9 will be closed) until counter B catches up with and passes counter A.  If counters A and B and the second hand are in the 45 sec position and the reset switch is closed to reset B to 00, the comparator detector will react and allow the 2Hz signal to pass to the motor 13 and counter A via gate 9. Counter A will advance at twice the speed of counter B until it has caught up with B. In an alternative embodiment Fig. 3 (not shown) pulses are delivered by a coil (8) driven by a motor (e.g. a spring motor or a balance wheel motor) to the counter A connected for comparison with reference counter B fed from a crystal controlled oscillator. If A leads B a gate (10) loads the coil 8 to apply a damping effect on the motor so as to slow it down until A becomes in phase with B. No driving pulses are applied to the motor from the circuit of Fig. 3, the energy source being mechanical.