Crystal-controlled mechanical resonator

Abstract

Abstract A MINIATURE TIMEPIECE DRIVEN BY A TUNING-FORK MOTOR WHOSE VIBRATORY ACTION IS ELECTROMAGNETICALLY SUSTAINED BY AN ELECTRONIC DRIVE CIRCUIT. TO REGULATE THE TIMING RATE OF THE MOTOR, A FREQUENCY STANDARD IS PROVIDED IN THE FORM OF A CRYSTAL OSCILLATOR WHOSE FREQUENCY IS AN EXACT MULTIPLE OF THE PRESCRIBED TIMING FREQUENCY OF THE MOTOR. THE MOTOR IS PRESET TO OPERATE AT A TIMING RATE DISPLACED TO ONE SIDE OF THE PRESCRIBED FREQUENCY TO A DEGREE DETERMINED BY THE MAXIMUM ANTICIPATED DEVIATION IN TIMING RATE CHARACTERISTIC OF THE MOTOR. TO EFFECT REGULATION, PULSES ARE DERIVED FROM THE ELECTRONIC CIRCUIT, THE PULSES HAVING A PERIODICALLY EQUAL TO THE OPERATING FREQUENCY OF THE FORK. THESE PULSE ARE COMPARED IN A COINCIDENCE CIRCUIT WITH THE STANDARD OSCILLATIONS TO PRODUCE AN ERROR SIGNAL ONLY WHEN THE PULSE ARE DISPLACED IN PHASE FROM THE PARTICULAR SUBMULTIPLE OF OSCILLATIONS WHICH CORRESPONDS TO THE PRESCRIBED FREQUENCY. THE ERROR SIGNAL ACTIVATES A FREQUENCY-CORRECTION CIRCUIT COUPLED TO THE ELECTRONIC DRIVE CIRCUIT ASSOCIATED WITH THE TUNING-FORK MOTOR, WHEREBY THE PHASE OF THE PULSE DERIVED FROM THE ELECTRONIC CIRCUIT SHIFTS IN A DIRECTION TO BRING ABOUT PHASE-LOCKING WITH SAID SUBMULTIPLE.

Inventors

• 👤 William O Bennett
• 👤 Dale R Koehler

Bibliographic Details