Focus control for optical scanner

Focus control method and focus controller

Focus control method and optical disc recording/reproducing...

Focus control method, and optical disk unit with focus offset co

Focus control system

Focus control system for optical read-out apparatus

Focus control through detection of the rate of error in discs wi

Focus control via AC input signal

Focus control via AC input signal

Focus controlling apparatus and method, and optical disc drive

Focus detecting apparatus utilizing reflecting surface having va

Focus detecting optical head

Focus detection and control apparatus for maintaining accurate f

Focus detection in a digital focus servo system

Focus detection mechanism and optical head and optical storage d

Focus detection system for an optical disk drive using photo sen

Focus detector which serves to split off a portion of a detected

Focus draw-in system for optical disc device

Focus drive circuit and focus search method based on relative po

Focus error detecting apparatus of optical pickup with a...