JPS5587987A - Electronic watch - Google Patents

Abstract

PURPOSE: To improve the counting accuracy of an electronic watch by obtaining a frequency signal from the frequency difference between two oscillators having equal frequency temperature coefficient at every special time unit and detecting the frequency error on the basis of the signal to thereby variably control the frequency dividing ratio thereof.

CONSTITUTION: The frequency difference such as, for example, 5Hz between an oscillator 1 for oscillating 32,768Hz at predetermined temperature and an oscillator 2 having equal frequency temperature coefficient to that of the oscillator 1 is detected by a detector 4, and counted by a counter 5 to invert, for example, the output of a flip-flop (FF) at every one hour. The output B from the flip-flop enables to pass a frequency division signal E of 512Hz through an AND gate 7, and to pass a frequency division signal D of 8,192Hz through AND gate 9 by the outputs C and G from a flip-flop 8. Assuming that the number of pulses per one hour of the frequency division signal E is reduced by three, the flip-flop 8 is inverted after three pulses after one hour is elapsed by the counters 14, 11 and zero detector 12, etc., and an Exclusive OR gate 17 produces a signal M superimposed with three pulses once per two hours at the output L of 256Hz from the frequency divider 16 to thereby automatically correct the frequency divider 18.

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