| 摘要 |
PURPOSE:To confirm the locking state of a DC motor at high precision, by comparing voltage as the result of phase-comparing reference signal with rota tional output signal, and by driving a LED. CONSTITUTION:A PPL synchronous monitoring apparatus for confirming the locking state of a DC motor is organized with a phase comparator 1 comparing the phase difference between reference signal Ea and rotational output signal Er, a voltage comparator 2 with the compared output Ed for the first input and reference voltage ES1 for the second input, a voltage comparator 3 with reference voltage ES2 for the first input and said voltage Ed for the second input. NAND gates 4, 5, and the series circuit of a LED 7 and a resistance 8. In this manner, for example, when the phase in the rotational output signal Er is passed by 1/2 cycle or more than in the reference signal Ea, then the output Ed of the phase comparator 1 corresponds to the output of pulse more positive than that on a reference level, and the operation of the first and the second comparators 2, 3 is turned to a level 0, and only during the term, the LED 7 is lit, and it can be known that PLL is getting out of a locking state. |
