Patent ID: 6246650
Filing Date: 2001-06-12
Classification: G11B

Abstract:
An information reproducing apparatus, comprising:reproducing means for reproducing information recorded on a record medium;driving means for driving the record medium in a variable speed;storing means for temporarily storing information reproduced by said reproducing means at a transfer rate in accordance with the speed of said driving means;reading means for reading information stored in said storing means;checking means for checking the amount of information reproduced by said reproducing means;measuring means for measuring a jitter of information reproduced by said reproducing means; anddrive controlling means for controlling the speed of said driving means in accordance with the amount of information checked by said checking means or the jitter measured by said measuring means;wherein said measuring means includes:a phase comparator configured to receive an EFM signal and a reproduced clock signal and in accordance therewith, generating a phase comparator output signal;a low pass filter configured to receive said phase comparator output signal and to output a low pass filtered signal;a voltage controlled oscillator (VCO) configured to receive the low pass filtered signal and outputting said reproduced clock signal;a converter for converting said phase comparator output signal to an equivalent digital signal;a jitter measuring circuit for storing said digital signal output from said converter and for outputting a predetermined number of frames of said digital signal output; anda comparator for comparing said predetermined number of frames of said digital signal output with a predetermined value to determine whether the digital signal output exceeds said predetermined value;wherein said phase comparator compares the phase of said EFM signal and the phrase of an output signal of the VCO.