| 摘要 |
<p>PURPOSE:To eliminate jitters by counting the 2nd clock signal independent of the 1st clock signal synchronizing with a digital signal and by controlling the transport speed of a recording medium by detecting a difference of the count value. CONSTITUTION:A write address WA from the 1st counter 24 and a read address RA from the 2nd counter 28 are inputted to an error detector 38, which outputs both addresses WA and RA and their difference signal J. This difference signal J is passed through a D/A converter 40 and an amplifier 32 to obtain a signal controlling the turning speed of a motor 12. A servo loop controlling the speed of this motor 12 operates to hold the difference signal between count values WA and RA at a prescribed value, thus keeping the transmission speed of a digital signal A constant. In this constitution, turning-speed control over a disk 10 is exercised on the basis of the bit transmission speed of the digital signal A without depending upon the synchronizing signal of the digital signal A, so jitters due to the detection error, etc., of the synchronizing signal are completely eliminated.</p> |
