GB1412319A - Oscillating balance wheel movement - Google Patents

Abstract

1412319 Electric timepieces JAZ SA 9 Nov 1973 [10 Nov 1972 3 April 1973] 52200/73 Heading G3T To permit synchronization of an electromagnetically maintained balance 1 with a pulse generator, magnets a, a', Fig. 1, are offset from the driving and control coils in the neutral position of the balance, and the natural balance period is arranged to be different from that of the pulse generator, synchronizing pulses being supplied to the driving coil when the balance is not passing through its neutral position. As shown the magnets are on the balance and the driving and control coils are combined in a fixed structure b, but this may be reversed. The pulse generator is a quartz crystal oscillator Q, Fig. 5, connected via an integrated circuit frequency divider CI to the base of transistor Tr in the balance maintaining circuit. The sync pulses may alternatively be fed to the collector circuit Fig. 3 (not shown), and thus directly to the driving coil Bm. Diode D prevents the sync. pulses from passing through the control coil Bc via capacitor C. If the drive coil and magnets produce repulsion, the balance period (T1), Fig. 4 (not shown) is shorter than the sync. pulse period (T2) and the sync. pulses (is) retard the balance. If magnetic attraction is used, the case is reversed. The circuit gives a maintaining pulse (im) every half cycle and a sync. pulse every cycle.