Optical disk device with disk type recognition

An optical disk drive having the ability to read data from multiple types of optical disks, each including at least one information storage layer, the drive comprising:

• a motor for spinning a given one of the optical disks;
• at least one light source for radiating light beams with multiple different wavelengths;
• at least one lens for converging each said light beam onto the optical disk;
• a spherical aberration correcting section that is able to change the spherical aberration states of the light beam;
• and
• a control section for controlling the operations of the motor, the light source, the lens and the spherical aberration correcting section,
• wherein the control section includes disk type recognizing means that irradiates the given optical disk with a light beam using the light source and the lens, thereby recognizing the type of the given optical disk, and
• wherein the disk type recognizing means recognizes the type of the given optical disk by reference to first and second signal waveforms that have been generated based on the light beams reflected from the optical disk when the spherical aberration correcting section sets the spherical aberration states of the light beam to a first state and a second state, respectively, the second state being different from the first state.

A method for driving an optical disk drive having the ability to read data from an optical disk including at least one information storage layer, the method comprising the steps of:

• obtaining a first signal waveform by irradiating the optical disk with a light beam, of which the spherical aberration has been set to a first state, and by detecting the light beam that has been reflected from the optical disk;
• obtaining a second signal waveform by irradiating the optical disk with a light beam, of which the spherical aberration has been set to a second state that is different from the first state, and by detecting the light beam that has been reflected from the optical disk;
• and
• recognizing the type of the given optical disk by the first and second signal waveforms.