Browse Prior Art Database

Optical Data Storage

IP.com Disclosure Number: IPCOM000115709D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 59K

Publishing Venue

IBM

Related People

Demura, M: AUTHOR [+2]

Abstract

Disclosed is a system for improving the accuracy of data phase lock timing with selecting the differential data detection from two data detection method by phase lock in the optical disk drive system. This disclosed system is widely applicable to data detection of any optical disk drive system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 88% of the total text.

Optical Data Storage

      Disclosed is a system for improving the accuracy of data phase
lock timing with selecting the differential data detection from two
data detection method by phase lock in the optical disk drive system.
This disclosed system is widely applicable to data detection of any
optical disk drive system.

      Generally optical disk system has following two data detections
in the circuit.  One is the differential detection, the other is
signal compared detection with variable DC tracking threshold level.
Logical AND data from both output generates the final detected data.
When the optical spot rushes into the data area from preformatted
area at optical disk, DC transient comes out within the reading
signal (Fig. 1).  The signal compared detection circuit does not work
well for this DC transient and finally causes dropping out of final
detected data in VFO3 area for phase lock (Fig. 2).  The detection
circuit counts the number of VFO3 data in the phase lock process.
When the detection circuit reaches the target counts, the circuit
locks the phase and puts out the phase lock sense signal.  Dropping
out of some VFO3 data while this counting mode delays the phase lock
timing.  This disclosed system disables the above signal compared
circuit with switch (SW1) which is controlled by phase lock sense
signal before completed the phase lock process (Fig. 3).  This
systems is able to prevent the dropping out of VFO3 data as shown in
Fig. 4 and improves...