DEVICE AND METHOD OF DETECTING 3T SIGNAL SWING COMPONENT FOR FOCUSING OPTICAL PICKUP IN OPTICAL DISK DEVICE

摘要

PROBLEM TO BE SOLVED: To miniaturize a 3T signal swing component detecting device for focusing an optical pickup used for an optical disk device. SOLUTION: Light reflected from an optical disk is converted to an electrical RF signal via an objective lens of an optical pickup and a quadripartite element. An edge signal having a short pulse width of 50 nsec is generated, before and after the point of time when a half period of 3T signal is elapsed after the trailing time of an EFM signal converting the RF signal. A 3T signal swing component is obtained by extracting, holding and smoothing the RF signal with this edge signal. This 3T signal swing component is used for focusing the optical pickup.