GB1349974A - Electric timepiece with chronograph indicator - Google Patents

Abstract

1349974 Electronic timepieces EBAUCHES S A 23 July 1971 [7 Aug 1970] 34676/71 Heading G3T In an electronic timepiece functioning both to indicate the time of day and as a chronograph, a drive circuit for the timepiece balance wheel transducer is modified automatically when the chronograph section is turned ON in order to compensate for the extra power required to drive the chronograph indicator and maintain the amplitude of oscillation of the balance wheel unchanged. In Fig. 2, pick-up and drive coils 12, 13 respectively, co-operate with magnets 10, 11 on a balance wheel 9. When the chronograph indication is to be used a push piece (7) is manually operated thereby closing a switch 19 which connects a resistor 18 in parallel with a time constant circuit C16 R17. This alters the bias of a drive transistor 15 so that stronger drive current pulses are applied to coil 13. In a modification Fig. 3, (not shown), there are two pick-up coils the second of which is switched in when chronograph operation is required. In a similar arrangement Fig. 4, (not shown), second drive coil is switched in. In an embodiment Fig. 5, (not shown), one coil serves as both drive and pick-up, and there are two transistors one serving as a drive and the other as a control transistor.