| 摘要 |
PURPOSE:To improve the time accuracy of a timepiece by providing a counter which uses crystal as an oscillation source and a counter which uses the power source frequency as an oscillation source, and periodically finding the difference between both counted values and making corrections. CONSTITUTION:A microcomputer(MC) 6 incorporates a timer counter 1 which outputs a timer signal, the crystal counter 2 which uses crystal as an oscillation source, and the power source counter 3 which uses the power source frequency as the oscillation source. An oscillator 8, on the other hand, oscillates crystal 7 outside the MC and the oscillation frequency from the oscillator 8 is divided by a frequency divider 9, whose output signal is supplied to the counters 1 and 2. Then, an arithmetic circuit 4 finds the difference in counted value between the counters 2 and 3 periodically and the output value is stored temporarily in a counter 5A for a register. Then, an adding circuit 5B adds the output value of the counter 1 to the output value of the counter 5A and outputs the sum to the counter 1 to perform the correction.
|
