Patent ID: 6081492
Filing Date: 2000-06-27
Classification: G11B

Abstract:
A signal processing circuit of a disc reproduction device for generating a reproduction clock synchronized with a reproduction signal from the disc and performing signal processing with respect to the reproduction signal based on the reproduction clock, comprising:a rotational speed counting means for generating a first control signal in accordance with a change of speed of a rotational speed of said disc with respect to a reference speed;a first oscillating means for generating a first reference clock of a predetermined frequency;a second oscillating means changing in its oscillation frequency in accordance with said first or second control signal to provide an oscillation signal of said second oscillating means;a phase comparing means for generating said second control signal in accordance with a phase difference between the first reference clock by said first oscillating means and an oscillation signal of said second oscillating means;a first PLL circuit for generating a second reference clock of a predetermined frequency based on the oscillation frequency of the oscillation signal of said second oscillating means;a second PLL circuit for generating said reproduction clock based on said reference clock and controlling said reproduction clock in accordance with the frequency change and phase change of said reproduction signal with respect to this reproduction clock; anda means for switching the first or the second control signal for inputting the first or the second control signal to said second oscillating means at the time of reproduction and access.