Patent ID: 8289826
Filing Date: 2012-10-16
Classification: G11B

Abstract:
1. An optical pickup comprising: a light source configured to emit a light beam; an objective lens configured to collect the light beam on a desired recording layer among one recording layer or two recording layers or more, which are installed in an optical disc and where tracks having a spiral shape or a concentric shape are formed; a lens moving unit configured to move the objective lens in a tracking direction directed toward at least an inner circumference side or an outer circumference side of the optical disc; a light splitting device configured to split a reflected light beam reflected by recording layer into a plurality of reflected light beams and to propagate the plurality of reflected light beams; and a light detection device configured to generate a central light detecting signal, an inner circumference side light detecting signal, and an outer circumference side light detecting signal according to received light amounts thereof by a central light detecting area, an inner circumference side light detecting area, and an outer circumference side light detecting area, which receive a central portion, an inner circumference side portion, and an outer circumference side portion of an image of the reflected light beam in a radial direction of the optical disc and to allow a predetermined signal processing unit to generate a tracking error signal by using the inner circumference side light detecting signal and the outer circumference side light detecting signal, each of which is added with a product of a predetermined coefficient and the central light detecting signal; wherein the light detection device generates a central preceding side light detecting signal, a central following side light detecting signal, an inner circumference preceding side light detecting signal, an inner circumference following side light detecting signal, an outer circumference preceding side light detecting signal, and an outer circumference following side light detecting signal according to received light amounts thereof by a central preceding side light detecting area, a central following side light detecting area, an inner circumference preceding side light detecting area, an inner circumference following side light detecting area, an outer circumference preceding side light detecting area, and an outer circumference following side light detecting area, which receive a central portion of an image of the reflected light beam in the radial direction of the optical disc and a preceding side portion and a following side portion of each of an inner circumference side portion and an outer circumference side portion in the tracking direction of a track, and wherein the signal processing unit generates the tracking error signal by using the inner circumference preceding side light detecting signal and the outer circumference preceding side light detecting signal, each of which is added with a product of a predetermined coefficient and the central preceding side light detecting signal, and the inner circumference following side light detecting signal and the outer circumference following side light detecting signal, each of which is added with a product of a predetermined coefficient and the central following side light detecting signal.