GB1313010A - Electronic watch - Google Patents

Abstract

1313010 Electronic watches HAMILTON WATCH CO 30 Oct 1970 [13 Aug 1970] 51799/70 Heading G3T A battery powered electronic wrist watch comprises a crystal controlled oscillator circuit the high frequency output (262, 144 Hz) of which is fed to a frequency divider which produces therefrom low frequency (16 Hz) timing impulses to drive an electro-mechanical resonator which is coupled via a gear train to hour, minute and second hands and to a date indicating ring. The natural frequency of the resonator is adjustable to correspond to the output frequency of the divider. Setting means is also described. The oscillator circuit 12 (Fig.4) comprises a quartz crystal 76 connected between gates and drains of complementary M.O.S. field-effect transistors 78, 80. Fine tuning is by capacitor 84. Complementary output signals on lines 86, 88 from the oscillator are applied to a first stage 90 of a 14-stage integrated circuit frequency divider 16 comprising a chain of flip-flops. The output of stage FF-14 is fed to a driver 20 including an RC differentiator 94, 92. The differentiated pulses are applied to gates of a complementary pair of field effect transistors 96, 98 the output of which is fed via resistor 100 to a switching transistor 104. Thus transistor 104 will supply drive current pulses, derived from the battery at 68, 70, to a coil 30 of the electro-mechanical resonator causing the coil to oscillate in a permanent magnet field at 16 Hz. In a modification Fig.4A (not shown) the complementary pairs of transistors are also included in the integrated circuit. The electro-mechanical resonator comprises an armature coil 30 (Fig. 2) on a core (not shown) journalled by 'balance' staff sections 34, 36 in bearings 38, 40 for oscillatory movement in the field of magnets 26, 28. The staff drives an eccentric 54 on which is pivotted one end of a lever 56 which transmits oscillatory movement of the staff to an index wheel 58. A hairspring 42, the effective length of which is adjustable in a conventional manner to adjust the natural frequency of the resonator, has six times the stiffness of lower hairspring 48. The springs carry current from the drive circuit to the coil. A setting stem (148) Fig.7 (not shown) has two positions. In its innermost position the watch will run normally and rotation of the stem causes a rapid set assembly to rotate a calendar ring (218) having radially inwardly facing teeth (222). At its outermost position the stem acts to positively brake the gear train and open a switch Fig. 9C (not shown) in the battery circuit, and rotation of the stem acts through a setting wheel to set the hands and the date indicator. Electrical inter-connections are formed on a printed circuit board. The back of the watch is electrically conductive and bears resiliently against a 3 volt circular battery to form a negative pole terminal thereof.