GB1350721A - Electronic circuit for quartz crystal watch - Google Patents

Abstract

1350721 Electronic watches DAINI SEIKOSHA K K 17 March 1972 [20 March 1971] 12637/72 Heading G3T A drive circuit to drive an electro-mechanical oscillator (e.g. in a watch), comprises a crystal controlled oscillator circuit 1, Fig. 1, the output of which (at 16384 Hz) is divided by a chain of fourteen divide-by-two M.O.S.F.E.T. frequency divider stages to produce a timing pulse train at 1 Hz and pulse width of 500 m secs. A wave shaper (WS), Fig. 2, (not shown), reduces this width to 8 m secs in order to reduce power consumption. Pulses from the shaper at a terminal 2d are applied to a bi-stable circuit 4 and via a diode D to a monostable circuit 5 which controls the bi-stable circuit so as to pass current alternately in opposite directions through a coil L of the electro-mechanical transducer. A permanent magnet armature of the transducer is thereby caused to oscillate. In the oscillator circuit 1 a crystal 1a is maintained oscillating by a circuit including a transistor 11. A capacitor 11 compensates for frequency drift due to temperature changes. Capacitors 12, 13 are for fine and coarse frequency adjustment respectively. A timing pulse output at 2d comprises a train of positive pulses which render transistors T41, T42 conductive so that current passes through coil L in a direction "A". When the voltage at 2d decreases a normally conducting transistor T51 becomes temporarily non-conducting so that T45, T43 are permitted to conduct. This causes current to flow in coil L in the opposite direction B. Meanwhile the charge in a capacitor C51 increases the potential at the base of T51 which again conducts. The non-conducting period of T51 depends upon the time constant of R51 C51. In Fig. 3, a transducer for a watch comprises a permanent magnet 9 mounted on the axle of a pallet 8 and co-operative with the driving coil L which is wound on a magnetic core 7. The pallet drives a seconds wheel 10 and hand 13 in known manner. A limit spring 14 engages a gear wheel 12 coaxial with wheel 10. SETTING A switch 3, operated via the watch crown, applies a negative potential to a point 2e thus blocking the divider stages subsequent to the tenth stage so that the watch is stopped - when the crown is in one position. The watch is restarted by pushing the crown to its other position to synchronize with a reference time.