Patent ID: 7224655

Claim:
A method for detecting a tilted disc, the method comprising: positioning a pickup unit at a first predetermined location on an inner circumference of an optical disc; radiating light on the optical disc at the first predetermined location; moving the pickup unit away from the optical disc; moving the pickup unit towards the optical disc; measuring a time T 1 at which a first focus error signal, generated when light is reflected from a recording layer of the optical disc, is output; positioning the pickup at a second predetermined location on an outer circumference of the optical disc; radiating light on the optical disc at the second predetermined location; moving the pickup unit away from the optical disc; moving the pickup unit towards the optical disc; measuring a time T 2 at which a second focus error signal, generated when light is reflected from the recording layer of the optical disc, is output; determining a tilt degree indicating value T, using the measured times T 1 and T 2 ; and comparing the tilt degree indicating value T with a predetermined reference value R to determine if the optical disc is the tilted disc.