Disklike storage medium and tracking method using the same

Details Disklike storage medium and tracking method using the same Disklike storage medium and tracking method using the same

2000-09-26

2003-09-30

Tran, Thang V. (Department: 2653)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S275300

Reexamination Certificate

active

06628578

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a disk-shaped storage medium on or from which data is recorded or reproduced using a laser beam, and to a tracking method using the disk-shaped storage medium.
BACKGROUND ART
Recently, as disk-shaped storage media, optical disks have been put into practical use as large capacity data files and media for storing music or images. However, it further is intended to increase the capacities of such disk-shaped storage media so that they can be applied in more various uses. For efficient access to a large capacity optical disk, the following method is employed in general. That is, recording data are distributed to sectors in a certain unit of data size, and recording and reproduction are performed using the sectors as base units for rewriting. To the respective sectors as the base units for rewriting, addresses for identifying the sectors are added. Generally, the addresses are recorded as pits formed of concave and convex parts in an optical disk. A land/groove recording system has been employed commonly. In the system, track-guide grooves and inter-groove portions are used as areas for recording data in order to increase the density in a track direction.
A conventional optical disk having this sector configuration is described with reference to FIG.
12
.
In FIG.
12
(
a
), numeral
1001
indicates a substrate, numeral
1002
a recording film, numeral
1003
a first track, numeral
1004
a second track, numeral
1005
a sector of a divided portion of the track, numeral
1006
an address for identifying the sector, and numeral
1007
a data recording area for recording data. The first track
1003
is formed of a groove and the second track
1004
is formed of an inter-groove portion sandwiched by the groove of the first track. As shown in FIG.
12
(
a
), the first track
1003
and the second track
1004
are configured to be positioned alternately on a one-revolution basis. Tracking by an optical beam is performed using the groove as a guide. However, the first track
1003
is in the groove and the second track
1004
is on the inter-groove portion, and therefore a tracking polarity is required to be inverted for the shift between the first track and the second track. As marks serving for detecting the polarity inversion, polarity inversion marks
1008
are provided in locations where the shift between the first track and the second track takes place. An optical disk device inverts the polarity in tracking using the polarity inversion marks
1008
. In the sector
1005
, the address
1006
and the data recording area
1007
are arranged as shown in FIG.
12
(
b
).
Furthermore, as shown in FIG.
12
(
c
), the address
1006
added for identifying the sector
1005
includes a sector mark
1009
indicating a sector starting point, a VFO mark
1010
used for generating a clock for the reproduction of the address part, an address mark
1011
for indicating the start of address data, a sector number
1012
, a track number
1013
, and an error detection code
1014
. Since the sector mark
1009
and the address mark
1011
provide a data pattern for identifying the start of the address data, the data pattern is required to be a unique pattern that does not appear in the sector number
1012
, the track number
1013
, and the error detection code
1014
. Therefore, the address data of the sector number
1012
, the track number
1013
, and the error detection code
1014
are recorded after being processed by bi-phase modulation or run-length-limiting modulation (RLL modulation). By this modulation process, a data pattern that does not appear from modulation rules for the other data can be obtained. Thus, a unique data pattern not in accordance with the modulation rules is used for the sector mark
1009
and the address mark
1011
. The sector mark
1009
has a sufficient length to identify the start of the address area easily even when a PLL clock for synchronization is not locked.
As the modulation to the address data portion, the conventional example shown in
FIG. 12
employs a bi-phase modulation in which “0” is modulated to be “00” or “11”, and “1” to be “10” or “01”. According to this modulation, a pattern with at least three “1” or “0” in a row is changed into a unique pattern not in accordance with the modulation rules. As the pattern not in accordance with the modulation rules, the conventional example shown in
FIG. 12
employs “10001110” for the address mark
1011
and “111111110000000” for the sector mark
1009
. A method of reproducing the address part in this conventional example is described briefly as follows.
Initially, the sector mark is detected. The sector mark has a unique pattern having eight “1” and eight “0” consecutively. When a mark with at least a certain length is detected using a free-running PLL clock, the sector mark
1009
can be detected easily. When this sector mark
1009
is detected, the PLL clock used for address demodulation is locked by the subsequent VFO
1010
. After the lock of the PLL clock, the PLL clock determines “1” and “0” of the reproduced data, thus obtaining determination data. When the pattern of“10001110” as the address mark
1011
is detected from the determination data, the subsequent data are identified as the sector number
1012
, the track number
1013
, and the error detection code
1014
. In this way, the detection of the address mark
1011
allows the subsequent data to be identified as the sector number
1012
, the track number
1013
, and the error detection code
1014
that are to be demodulated. Thus, the data are demodulated.
In the above-mentioned conventional example, the address part
1006
includes the VFO mark
1010
for clock synchronization. However, a method in which the clock for demodulating address data is obtained by another means also has been practiced. This type of conventional example is described with reference to FIG.
13
.
In FIG.
13
(
a
), numeral
1101
indicates a substrate, numeral
1102
a recording film, numeral
1103
a track, numeral
1104
a sector of a divided portion of the track, numeral
1105
a segment of a divided portion of the sector, numeral
1106
an address for identifying the sector, and numeral
1107
a data recording area for recording data.
As shown in FIG.
13
(
b
), in the leading location of the segment
1105
, wobble pits
1108
used for obtaining a tracking signal and the subsequent clock pit
1109
for generating a clock for address and data demodulation are provided. As shown in FIG.
13
(
c
), the address
1106
added to identify the sector
1104
includes an address mark
1110
for indicating the start of the address data, a sector number
1111
, a track number
1112
, and an error detection code
1113
. As in the above-mentioned conventional example, the address mark
1110
has a unique pattern that does not appear in the sector number
1111
, the track number
1112
, and the error detection code
1113
. Similarly in the conventional example shown in
FIG. 13
, the bi-phase modulation is employed for modulating the address data portion and “10001110” is used as the address mark
1110
as in the above-mentioned conventional example.
A method of reproducing the address part in this conventional example is described briefly as follows. Initially, the clock pit
1109
is detected. Using this clock pit, the frequency of a clock pit detection signal is multiplied by N using the PLL, thus generating a PLL clock for address demodulation. In the trailing part of the PLL clock, as in the above-mentioned conventional example, “1” and “0” of the reproduced data are determined, thus obtaining determination data. When the pattern of “10001110” as the address mark
1110
is detected from this determination data, the subsequent data are identified as the sector number
1111
, the track number
1112
, and the error detection code
1113
. In this way, the detection of the address mark
1110
allows the subsequent data to be identified as the sector number
1111
, the track number
1112
, and the error detection code
1113
that are to be demodul

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