| 摘要 |
PURPOSE:To reduce wow and flutter by composing a frequency generator to produce a signal frequency-modulated by a modulation signal having a basic frequency of n times of the rotating frequency. CONSTITUTION:A disk 11 with slits has a dense slit portion 11a having a dense period of slits and a rough slit portion 11b having rough period of slits such as four portions on a circumference. A frequency generator 12 is composed together with the disk 11 and a photointerrupter 3. Thus, the generator 12 outputs a signal frequency-modulated by a modulation signal having a basic frequency of n times of the rotating frquency of a motor 1. The output of the generator 12 is converted by a frequency/voltage converter 6 into a voltage, and a voltage comparing amplifier 7 supplies a deviation signal between the voltage and the reference voltage to a motor drive circuit 9. |
