Patent ID: 6449235
Filing Date: 2002-09-10
Classification: G11B

Abstract:
An optical pickup apparatus accessing first to third optical discs with a gradually increasing density, comprising:first and second light sources for respectively generating different wavelengths of light beams; an optical system allowing a light beam generated by any one of the first and second light sources to be selectively irradiated onto the discs, said optical system including an aperture number control means for determining the number of aperture of the light beam to have a different value depending on an optical disc to be accessed whereby a light beam generated at the first light source to be irradiated with a first value of aperture number when the optical disc to be accessed is the first optical disc, said optical system allowing a light beam generated at the second light source to be irradiated with a second value of aperture number smaller than the first value of aperture number when the optical disc to be accessed is the second optical disc, said aperture number control means including a wave selecting-polarizing member capable of performing both a wavelength selecting function for selecting between different wavelengths of light beams and a polarizing function; and photo detecting means for detecting a light beam reflected from the accessed optical disc and converting it into an electrical signal, wherein the optical system allows a light beam generated at the first light source to be irradiated when the optical disc to be accessed is the first optical disc, whereas it allows a light beam generated at any one of the first and second light sources to be irradiated when the optical disc to be accessed is any one of the second and third optical discs.