| 摘要 |
<p>PURPOSE: To provide a zero adjusting device and a method therefor in which a zero adjustment can be easily, smoothly and precisely performed by one push of a switch by use of a digital circuit, and stably kept for a long time. CONSTITUTION: This device has a frequency reducing device 12 for making a high frequency clock signal inputted from a clock source 1 into a low frequency reference signal, and a phase detecting means 17 for outputting a voltage value corresponding to the difference between the phase of the detected low frequency signal and the phase of the reference signal and a DC voltage having a positive or negative value. It also has a signal judging circuit 19 for outputting a phase-shifting polarity selection signal for instructing the advance or delay in conformation to the positive or negative value of the inputted DC voltage, and a phase-shifting instruction pulse having a pulse interval corresponding to the input DC voltage value. In reply to the phase-shifting polarity selection signal and the phase-shifting instruction pulse, the phase of the reference signal is advanced or delayed, whereby zero adjustment is performed.</p> |
