Patent ID: 6424605
Filing Date: 2002-07-23
Classification: G11B

Abstract:
An optical disc drive compatible with a plurality of types of optical discs of different track pitches to write and/or read data into and/or from a loaded one of such optical discs, comprising:a first pickup provided for a first optical disc having a first track pitch; a second pickup provided for a second optical disc having a second track pitch smaller than the first one; a focus servo circuit to control a focus servo of the first and second pickups and pull in the focus servo, based on a focus error signal; a tracking servo circuit to control tracking of the first and second pickups based on a tracking error signal; and a control circuit to start pulling in the focus servo using the first pickup with respect to a loaded optical disc, detect, based on the focus error signal resulting from the focus servo pull-in operation, that the first pickup is in a nearly perfect focus, and then move the first pickup radially relative to the disc when the first pickup is in the nearly perfect focus, and then judge the loaded optical disc as the first one when a tracking error signal is detected during the radial move of the first pickup, or as the second one when no tracking error signal is detected during the radial move of the first pickup, wherein said focus servo circuit closes a focus servo loop after said control circuit judges the loaded optical disc as the first one or as the second one.