Patent ID: 8385167
Filing Date: 2013-02-26
Classification: G11B

Abstract:
1. A method of reproducing data from an information storage medium using a pickup, the information storage medium comprising a plurality of recording layers, each of the recording layers comprising a user data area, the method comprising: reproducing a first amount of data from one of the recording layers closest to the pickup; and reproducing lesser amounts of data than the first amount of data from other ones of the recording layers farther from the pickup than the recording layer closest to the pickup, the amount of data reproduced from each of the recording layers progressively decreasing from the recording layer closest to the pickup to one of the recording layers farthest from the pickup; wherein the recording layers are the only recording layers in the information storage medium; a region in which user data is not recorded is located on an inner circumference of a user data area of each of the recording layers; a region in which user data is not recorded is located on an outer circumference of a user data area of each of the recording layers; the region on the inner circumference of the user data area is the only region between the inner circumference of the user data area of each of the recording layers and an inner periphery of each of the recording layers; the region on the outer circumference of the user data area is the only region between the outer circumference of the user data area of each of the recording layers and an outer periphery of each of the recording layers; and each of the region on the inner circumference of the user data area of one of the recording layers second closest to the pickup, and the region on the outer circumference of the user data area of the recording layer second closest to the pickup, corresponds to about a number of tracks determined according to the following equation:  where SL is a thickness of a spacer layer between adjacent ones of the recording layers, TP is a track pitch, NA is a numerical aperture of an objective lens in the pickup, and n is a refractive index of the information storage medium.