Patent ID: 6493304
Filing Date: 2002-12-10
Classification: G11B

Abstract:
An optical disk apparatus for reproducing information from plural types of information carriers or for recording information to plural types of information carriers, comprisingtwo or more light sources with different wavelengths, converging means of converging a light beam emitted from each of said light sources on a surface of said information carrier, movement means of moving the converged spot of said light beam converged by said converging means in a direction substantially perpendicular to the surface of said information carrier, convergence condition detection means of outputting a signal corresponding to a convergence condition of said light beam on the surface of said information carrier, amplitude detection means of outputting an amplitude signal corresponding to an amplitude of said signal of said convergence condition detection means, and focus control means of driving said movement means in accordance with said output signal of said convergence condition detection means and of performing control so that the convergence condition of said light beam on said information carrier becomes substantially constant, wherein at a start or a restart of said apparatus, before said focus control means is driven, when said movement means is driven to move said converging means close to and then away from said information carrier or away from and then close to said information carrier, and when each of said light sources is turned on and light with a wavelength corresponding to said light source is emitted, the amplitude signal obtained from said amplitude detection means is stored in storage means, said apparatus makes distinction to determine the type of said loaded information carrier on the basis of the amplitude signal stored in said storage means, and said apparatus finds a light source compatible with the type of said information carrier and then drives said focus control means.