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普通电子表(即五功能电子表)表芯去向液晶屏的12和13号引线通常可引出作为外部定时控制信号线。这两根信号线上所产生的信号在液晶屏显示“XX:P”或”“XX:A”时均为一定频率的交流脉冲信号,但其峰值却是根据显示“XX:P”还是”XX:A”而有所不同。当显示 XX:P 时这信号的峰值小于显示 XX:A 时的峰值。将这信号鉴别处理后,我们就能得到以逻辑0和逻辑1表示的 XX:P 和 XX:A 信号。当我们将电子表调到显示 XX:P 或 XX:A 时,再将与电子表计数按钮并联的开关闭合,则液晶板上的显示状态将作1s步距的交替变换,即:1P→2P→3P→4P→5P→6P→7P→8P→9P→10P→11P→12A→1A→2A→3A→4A→5A→6A→7A→8A→9A→10A→11A→12P→1P→…。这样,我们就得到了周期为24s,占空比近似50%的基准脉冲信号,作为具有一般定时精度的定时器中的计数器的计数脉冲。
Ordinary electronic watch (ie, five-function electronic watch) go to the LCD screen leads 12 and 13 can usually lead as external timing control signal line. The signals generated on these two signal lines are all AC pulse signals of certain frequency when the LCD displays “XX: P” or “XX: A”, but the peak value is based on the display of “XX: P” or “ XX: A. ”The peak of this signal is smaller when XX: P is displayed than the peak at XX: A. After this signal discrimination, we can obtain XX: P with logic 0 and logic 1 And XX: A signal.When we dial the display to show XX: P or XX: A, and then with the electronic meter button in parallel switch is closed, the liquid crystal display on the state will be alternately alternating 1s step , Namely: 1P → 2P → 3P → 4P → 5P → 6P → 7P → 8P → 9P → 10P → 11P → 12A → 1A → 2A → 3A → 4A → 5A → 6A → 7A → 8A → 9A → 10A → 11A → 12P → 1P → .... Thus, we get a reference pulse signal with a period of 24s and a duty cycle of approximately 50% as the count pulse of the counter in the timer with normal timing accuracy.