Optical disc and disc drive apparatus for writing/reading data into/from the disc

Claim 2

An optical disc recording/reproducing system comprising: an optical disc having a plurality of tracks divided into a plurality of sectors (So-Sn) comprising sector identifier portions (ID) in which address information is recorded and data field portions (DF) for recording data, said tracks defining a data read-only area (4) in which data has been recorded and a data recording/reproducing area (3) in which data can be recorded in data field portions (DF), said sectors (So-Sn) each having a data identification flag (F) to indicate whether the sector is of the data read-only area, or the data recording/reproducing area; an optical head (41-52) for irradiating said disc with a laser beam; data recording means (29, 30) for reading address information of a sector identifier portion (ID) of a sector accessed on the disc, comparing the read address information with address information of a target sector for data recording/reproducing, and writing data into the data field portion of an accessed sector having address information coincident with address information of said target sector; data reproducing means (38) for reading data from the data field portion of an accessed target sector; means (26) for reading address information from the sector identifier portion (ID) of the accessed sector; and area discrimination means (111, 28) for discriminating from the read address information, depending on a data identification flag in said identifier portion, whether the accessed sector is of said data read-only area (4), or of said data recording/reproducing area (3); characterised in that: said disc is provided with at least one dummy sector (DS) at the boundary between said data read-only area (4) and said data recording/reproducing area (3), in which dummy sector (DS) no data is recorded in, or reproduced from the data field portions (DS), said dummy sector (DS) having a readable identifier portion (ID) for a data identification flag (F); and that said system includes: control means (40, 54, 108, 109) for causing reproduction-signal reading conditions to become optimum when said data field identification flag of said current sector cannot be correctly read, said control means causing said conditions to become optimum by referring to the data field identification flag of the preceding sector identifier portion, which can be correctly read, waveform equalizer means (37) for waveform-equalizing a signal reproduced by said optical head (41-52); and waveform equalizer-control means (39) for controllably changing waveform equalization amounts of said equalizer means (37) in response to said area discrimination means (111, 28).

Claim 3

A system according to Claim 2 and further including servo means (53, 54) for focusing said laser beam for tracking on said disc and writing inhibit means (112, 34) for inhibiting said data recording means (29, 30) from writing data in said accessed sector when said area discriminating means (111, 28) discriminates that said accessed sector is of said data read-only area (4).

Claim 4

A system according to Claim 3 and further including means for stabilising the tracking operation of said servo means (53, 54) thereby enabling said optical head (41-52) to be precisely positioned after traversing the boundary of said data read-only area (4) and said recording/reproducing area (3) in making the search.

Claim 5

A system according to Claim 4 and further including servo gain switching means (55) for switching the servo gain of said servo means (55) in response to said discrimination means (111, 28).

Claim 6

A system according to Claim 4, wherein said servo gain switching means (55) switches the servo gain of said servo means (53, 54) so that the loop gain of the servo means (53, 54) for focusing said laser beam is constant in said data read-only area (4) and in said data recording/reproducing area (3).