Optical disc

Abstract

An optical disc which has a rewritable first recording region and a read-only second recording region. The first recording region is composed of groove tracks and land tracks which are alternately provided on a disc substrate spirally or concentrically. Each first track is divided into a plurality of first sectors. Each first sector has a first header region where identification data by which the first sector is identified are recorded and a first data region in which user data are recorded with recording marks where the optical characteristics of the recording surface are changed. The second recording region has second tracks which are composed of a physical pit row which are provided on the disc substrate spirally or concentrically. Each second track is divided into a plurality of second sectors. Each second sector has a second header region where identification data by which the second sector is identified are recorded and a second data region in which read-only data are recorded by means of the pit row. The first header region includes a first physical pit row. Each pit of the first pit row has a width in a radial direction of the disc which is substantially equal to the width of the group track and, further, the pits are staggered along the center line of the group track radially with pitches of approximately a quarter of the pitch of the group track. The second header region includes a second physical pit row. Each pit of the second pit row has a width in a radial direction of the disc which is smaller than the width of the group track and, further, the pits are arranged generally along the center line of the second track to be tracked.

Description

technical field [0001] The present invention relates to an optical disc and its reproducing device, more specifically to an optical disc with a rewritable area and a read-only area and its reproducing device. Background technique [0002] Optical discs are classified into a read-only type that allows only reproduction of recorded data and a rewritable type that allows a user to record data thereon. A read-only optical disc has tracks formed in a spiral or concentric shape on a disc substrate. An array of concavo-convex portions (pits) is physically formed along the track in accordance with information to be recorded. A rewritable optical disk has grooves formed in a spiral or concentric shape on a disk substrate and a recording film formed on the grooves. The groove defines the track. When the user wants to record data on the disk, the disk is irradiated with a laser beam along the track, and the intensity of the laser beam is modulated according to the data to be recorde...

AI Technical Summary

Problems solved by technology

[0014] However, in conventional optical discs, the data format and modulation code used in the rewritable area and the read-only area are different from each other as described above.

A conventional recording / reproducing device for such an optical disc needs to have two separate signal processing circuits for a rewritable area and a read-only area, which complicates and increases the circuit size of the device.

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