Optical information device, optical storage medium, optical storage medium inspection device, and optical storage inspection method

Abstract

This optical disc drive has an optical pickup head that emits a light beam to an optical storage medium, detects the light beam reflected from the optical storage medium, and outputs a signal based on the received reflected light; a jitter measuring unit for measuring jitter in signals output from the optical pickup head; and an evaluation unit for determining from the measured jitter if the optical storage medium is good or defective. The jitter measuring unit measures jitter in a train of 3T or longer marks or spaces from an optical storage medium to which digital information is recorded as a train of marks or spaces of length kT based on a period T and an integer k of two or more.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an optical storage medium for recording information using marks and spaces, an optical disc drive for recording, reading, or deleting data on the optical storage medium, an optical storage medium inspection apparatus for determining whether the optical storage medium is good or defective, and an optical storage medium inspection method for determining whether the optical storage medium is good or defective. [0003] 2. Description of the Related Art [0004] High density, high capacity optical storage media known as DVD, or Digital Versatile Disc, have been developed as a practical high density, high capacity storage medium, and are today widely used as a data medium for handling video and other such large amounts of information. Development of two-layer optical storage media capable of recording to two data recording layers has also been reported by various manufacturers as a means of a...

AI Technical Summary

Benefits of technology

[0045] Yet further preferably, a gain adjustment means for reducing variation in the amplitude of signals input to a demodulation means when reflectivity of the optical storage medium varies is also provided.

[0116] With the configuration of an optical storage medium inspection apparatus according to the present invention described above jitter not including jitter relating to marks and spaces of the shortest recordable length is measured and used to determine whether the optical storage medium is good or defective. More specifically, two threshold values are used to identify the shortest marks. When using a two-layer optical storage medium to which data is recorded with the same recording density on two data recording surfaces, this reduces the effect of increased jitter resulting from marks on the recording layer closer to the optical pickup head being smaller than the desired size, and enables a reliable good / defective determination. The effect of degraded jitter resulting from the shortest marks and spaces can likewise be reduced when applied to an optical disc drive, and data can be reproduced with high reliability from two data recording layers. Data can also be recorded and reproduced with high reliability using an optical storage medium on which jitter from the shortest marks and spaces is worse than jitter from longer marks and spaces.

Problems solved by technology

While data can therefore be correctly recorded with the shortest marks even if the recording power fluctuates somewhat, the effect of power fluctuation cannot be ignored for marks longer than the shortest marks particularly if the recording density increases, and recorded signal quality can deteriorate.

Furthermore, if relative tilt between the optical storage medium and head or defocusing occurs during playback, the playback signal quality drops for signals read from marks longer than the shortest mark, and it may not be possible to correctly reproduce the data.

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