Patent ID: 7508742

Claim:
An optical disk type recognition method for determining whether an optical disk is present in an optical disk apparatus, and determining whether a disk that is present is CD or DVD, the method comprising: by using an optical disk apparatus provided with an optical pick-up using an infrared light source and a red light source, the optical pick-up comprising a photodetector for receiving a light beam and converting the light beam into an electrical signal, the photodetector comprising: a first photo detecting portion for receiving red light emitted from the red light source and outputting a signal for detecting a focusing error signal for DVD; and a second photo detecting portion for receiving infrared light emitted from the infrared light source and outputting a signal for detecting a focusing error signal for CD, determining whether an optical disk is present by emitting the infrared light source first when the power of the optical disk apparatus is turned on, or when an optical disk is inserted into the apparatus, and determining the kinds of the optical disk by using the reflected light from the optical disk when the optical disk is present, wherein the optical pick-up comprises a diffractive optical element in an optical path through which both the red light and the infrared light pass, wherein a wavelength of the red light λ 1 and a wavelength of the infrared light λ 2 substantially satisfy the following relationship: d 1 :d 2=λ1:λ2 where d 1 denotes a half distance between a center of the first photo detecting portion receiving a −first order diffracted light obtained as a result of the diffractive optical element diffracting the red light and a center of a photo detecting portion receiving a +first order diffracted light obtained as a result of the diffractive optical element diffracting the red light, and wherein d 2 denotes a half distance between a center of the second photo detecting portion receiving a −first order diffracted light obtained as a result of the diffractive optical element diffracting the infrared light and a center of a photo detecting portion receiving a +first order diffracted light obtained as a result of the diffractive optical element diffracting the infrared light.