GB1300257A - Synchronized horological system - Google Patents

Abstract

1300257 Electronic watches TIMEX CORP 16 March 1970 [14 March 1969 13 Jan 1970] 12630/70 Heading G3T [Also in Division H3] An electronically controlled watch comprises a balance wheel 25 Fig. 3 carrying a coil 26 which interacts with stationary ceramic magnets 33 and receives drive current pulses from a drive circuit Fig. 6 comprising a regenerative astable multivibrator (Relaxation oscillator), synchronizing pulses being applied to the drive circuit by a frequency divider circuit (including a series of relaxation oscillators or flip flops, not shown) which produces low frequency synchronizing pulses from the output of an h.f. oscillator e. g. a crystal oscillator. The balance wheel is coupled via gears to a time indicator. Alternatively the magnets may be on the balance wheel and the coil stationary. DRIVE CIRCUIT FIG. 6 The coil 26 functions both as a driving means and as a pick-up, a backe. m.f. beinginducedtherein by its movement relative to the magnets, of which there are three in the preferred embodiment. The circuit is triggered by three independent ways:- (1) By the e. m.f. induced in the coil which acts via C58 to turn ON transistor 50 which turns ON a transistor 55 and passes drive current through the coil from a battery 52. After the back e. m.f. is in effect swamped by the forward current the forward current pulse will continue for a period determined by C58 and R51. (2) Due to the connection of the base of Tr 50 via R53 to the negative battery terminal a train of pulses will be produced by the ciucuit even in the absence of balance wheel movement, and sufficient to start such movement as the circuit is self oscillating. (3) By a synchronizing pulse on line 59 which when added to the back e. m.f. can produce a signal of sufficient magnitude to trigger Tr50. A synchronizing pulse alone would be inadequate for this purpose. SYNCHRONIZATION Fig.11 illustrates the waveform of the voltage induced in the coil over a portion of a cycle of movement of the balance wheel. Synchronizing pulses are applied at points 71, 72 and 73. Trigger pulses will be produced where the algebraic sum voltage waveform goes more negative than a voltage level V o , i. e. at 74 and 75, the portion 75 corresponding to triggering for a normal drive pulse. The trigering at point 74 produces an additional drive pulse to accelerate the balance wheel, (or retard it depending upon the position of the balance wheel and whether it is fast or slow). The synchronizing pulses at points 72, 73 have no effect on the drive circuit. Four main drive pulses are applied to the coil in each full oscillation of the wheel. A drive pulse should be applied at the point of zero displacement, maximum velocity of the balance wheel to avoid change in the frequency of oscillation.