Patent ID: 7948836

Claim:
An optical disk drive in which laser beams are emitted to an optical disk in a state of not rotated, and simultaneously an objective lens which collects said laser beams is moved to a direction approaching said optical disk at a constant speed, a time length required for moving a focused position of said laser beams from a surface of said optical disk to a recording layer is measured by observing a reflected light from said optical disk, and a type of said optical disk is determined based on the time length Tdet thus measured, said optical disk drive comprises, a calculating means which calculates an additional travel time Tadd, based on said Tdet and an in-periphery maximum surface wobbling amount (Vd×2) of said optical disk, a moving means which further moves said objective lens for said additional travel time Tadd at said constant speed after said laser beams are focused on said recording layer, a rotating means which rotates said optical disk after the laser beams focuses on the recording layer, a move-away means which moves said objective lens in a direction to be away from said optical disk, and a detecting means which detects that said laser beams are focused on said recording layer of said optical disk after said move-away process is started; wherein the moving means executes a portion of a first half of a reciprocating movement and the move-away means executes a second half of the reciprocating movement.