Electronically controlled stop-watch

Claim 1

IN AN ELECTREONIC TIMEPIECE PROVIDED WITH A TUNING FORK AND GEARWORKS FOR OPERATING TIME INDICATORS, SAID GEARWORKS HAVING A RATCHET WHEEL WHICH IS ACTUATED BY A PAWL ENGAGING THE TEETH THEREOF AND ATTACHED TO ONE TINE OF SAID FORK WHEREBY AS SAID PAWL RECIPROCATES SAID WHEEL IS CAUSED TO TURN; AN ELECTRONIC CIRCUIT FOR SUSTANING THE VIBRATIONS OF SAID TUNING FORK AND COMPRISING (A) A VOLTAGE SOURCE HAVING A PREDETERMINED POTENTIAL VALUE, (B) A TRANSISTOR HAVING A CONTROL ELEMENT, (C) AN ELECTROMAGNETIC DRIVE COIL OPERATIVELY COUPLED TO SAID TUNING FORK AND ELECTRICALLY CONNECTED TO SAID SOURCE THROUGH SAID TRANSISTOR TO APPLY ACTUATING PULSES TO SAID FORK TO SUSTAIN VIBRATORY MOTION THEREOF WHEN SAID TRANSISTOR IS RENDERED PERIODICALLY CONDUCTIVE, THE AMPLITUDE OF WORK VIBRATION BEING A FUNCTION OF THE POTENTIAL OF SAID SOURCE; (D) AN ELECTROMAGNETIC PICKUP COIL OPERATIVELY COUPLED TO SAID TUNING FORK AND ELECTRICALLY CONNECTED TO THE CONTROL ELEMENT OF SAID TRANSISTOR OF DERIVE CONTROL PULSES FROM SAID TUNING FORK AT A RATE DETERMINED BY THE VIBRATORY RATE THEREOF AND TO APPLY SAID CONTROL PULSES TO SAID CONTROL ELEMENT TO RENDER SAID TRANSISTOR PERIODICALLY CONDUCTIVE; AND (E) MEANS INCLUDING A SWITCH TO REDUCE THE POTENTIAL OF SAID SOURCE BELOW ITS PREDETERMINDED VALUE TO A DEGREE LOWERING THE AMPLITUDE OF FORK VIBRATION TO A POINT INSUFFICIENT TO DRIVE SAID RATCHET WHEEL, WHEREBY THE TIMEPIECE ACTION IS STOPPED WHILE SAID FORK REMAINS IN VIBRATION.