Patent ID: 6529455
Filing Date: 2003-03-04
Classification: G11B

Abstract:
A disk apparatus, comprising:a laser for emitting laser light; an objective lens for converging and illuminating laser light to a disk surface; producing means for producing a focus-related signal based on laser light reflected upon the disk surface; first moving means for moving said objective lens within a first range with respect to a focusing direction; determining means for determining a second predetermined range including a focal position and narrower than the first predetermined range, based on the focus-related signal produced upon moving said objective lens within the first predetermined range; second moving means for repeatedly moving said objective lens within the second predetermined range; detecting means for detecting the focal position based on the focus-related signal produced upon moving said objective lens within the second predetermined range; said producing means includes a plurality of photodetector elements and error signal producing means for performing predetermined operation processing on outputs of said plurality of photodetector elements to produce a focus error signal; and said detecting means detecting a focal point based on the focus error signal; wherein said determining means includes first lens position detecting means to detect a first lens position where the focus error signal is minimized in level, second lens position detecting means to detect a second lens position where the focus error signal is maximized in level, calculating means to calculate a middle point of the first lens position and the second lens position, and second predetermined range determining means to determine as the second predetermined range a range having the middle position as a center and narrower than the first predetermined range.