| 摘要 |
PURPOSE:To control a drum motor with high accuracy by using a phase comparison signal obtained through the frequency division of a vertical synchronizing signal. CONSTITUTION:A signal in 60Hz from a vertical synchronizing signal generator 12 is formed into a signal in 15Hz by a 1/4 frequency divider 13 and supplied to a digital counter 11 as a reset signal RT. The digital counter 11 counts down a clock signal in 3.58MHz, its count is reset by a reset signal in 15Hz and the counter 11 outputs a signal for phase comparison in 45Hz. This 45Hz phase comparison signal is supplied to a phase comparator 14 of a drum motor servo circuit 15. On the other hand, a rotating pulse (45Hz) from a drum motor 6 is used as it is for the phase comparison signal and supplied to a phase comparator 14, where the phase is compared with that of the signal from the digital counter 11. A phase comparison error signal is extracted by this phase comparison, applied to a motor driving circuit 5 to control the drum motor 6 to a prescribed speed. |
