JPH0346126A - Optical disk - Google Patents

Abstract

PURPOSE:To enlarge capacity by contriving the arrangement of respective pits such as arranging a pit for track counter in the leading part of a servo field and afterwards, arranging wobble pit, clock pit and wobble pit in this order. CONSTITUTION:Clock pits 15 are arranged on centers 16 of tracks in the fixed positions in a track direction. Pits 12 for track count are slightly deviated from the centers 16 and arranged in deviated positions successively repeatedly in the track direction for each prescribed number of tracks. Distances between the pits 12 and the clock pits 15 are changed on three steps. Wobble pits 13 and 14 are slightly deviated from the centers 16 mutually reversely and the distance between the pit 14 and clock pit 15 is fixed. The distance between the pit 13 and clock pit 15 is changed on three steps. The combination of these three steps are more than three steps and changed for each prescribed number of tracks in the order determined in advance.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to optical disks including magneto-optical disks.

[Conventional technology]

Generally, optical discs have concentric or spiral tracks formed into one track (track for one revolution).
is divided into a plurality of sectors, each sector being larger than a plurality of blocks, and each block consisting of a servo field and a data field.

Conventionally, an optical disk has been provided with wobble pits 1 and 2 and a clock pit 3 in the servo field as shown in Figs. 3 and 4, as disclosed in Japanese Patent Laid-Open No. 63-2259.
It is known from Publication No. 24.

In the optical disc shown in FIG. 3, wobble bit 1.
2 are slightly shifted to opposite sides from the center 4 of the track, and the wobble pits 1 are arranged at positions at by C, d that are repeatedly shifted in the track direction for every predetermined number of tracks. Further, the wobble pit 2 and the clock pit 3 are arranged at fixed positions e and f in the track direction, respectively, and the clock bit 3 is arranged on the center 4 of the track.

In the optical disc shown in FIG. 4, the wobble pits 2 are arranged at positions g*)l*l that are repeatedly shifted in the track direction every predetermined number of tracks compared to the optical disc shown in FIG.

These optical discs are set in an optical disc device and driven to rotate by a motor, and a laser beam with a writing power from a laser is irradiated onto a target track on the optical disc by an optical pickup, thereby writing data into a data field. In addition, the optical pickup irradiates the optical disk with a laser beam with readout power from the laser, and the reflected light is received by a light receiving element.The output signal of this light receiving element is amplified by a preamplifier and outputted, thereby providing data. Data is read from the field. Also, when writing and reading data, the output power of the laser is used as read power at the servo field, and a signal corresponding to clock pit 3 is obtained from the preamplifier, but this signal is read from the data field. This serves as a timing reference for the information received. The signal from the preamplifier includes signals corresponding to wobble pits 1 and 2, and the track deviation detection circuit detects the deviation between the optical pickup and the target track on the optical disk from this signal. The detection signal controls the optical pickup to follow the target track. Furthermore, a track crossing of the optical pickup is detected by a track crossing detection circuit from signals corresponding to wobble pits 1 and 2 included in the signal from the preamplifier, and the detection signal is used to perform a seek to the target track of the optical pickup. will be held.

As shown in FIG. 5, other optical discs have a wobble pit pair 1°2 in the servo field, and two track counting pits 5 and 6 in addition to the clock bit 3.
The track counting pits 5 and 6 are placed at the beginning of the servo field, and then the wobble pits 1. Clock bit 3. There is one in which wobble pits 2 are arranged sequentially. In this case, wobble pits 1 and 2 and clock bit 3 are respectively placed at fixed positions j* and *N in the track direction, and track count pits 5 and 6 are each repeatedly shifted in the track direction for every predetermined number of tracks. Position m, n, o.

It is located at Pjqyr'.

In the optical disk device, a track deviation detection circuit detects the deviation between the optical pickup and the target track on the optical disk from the signals corresponding to wobble pits 1 and 2 included in the signal from the preamplifier, and generates the track deviation detection signal. The optical pickup is controlled to follow the target track.

Further, the track crossing of the optical pickup is detected by the track crossing detection circuit from the signals corresponding to the track count pits 5 and 6 included in the signal from the preamplifier, and the detection signal is used to determine the target of the optical pickup. A seek to the track is performed.

[Problem to be solved by the invention]

In the optical disks shown in FIGS. 3 and 4 above, when the wobble pit 1.2 is placed at the beginning of the servo field, the optical disk device causes the laser to emit light with the writing power up to just before the servo field during data writing, and the servo When the output power of the laser is switched to the readout power in the field, the preamplifier does not settle immediately, making the wobble pit 1.2 unreadable. Therefore.

The first part of the servo field must be blank and then wobble pits 1 and 2 must be brought in,
If this is done, the number of unnecessary blanks will increase, resulting in a decrease in capacity.

Furthermore, in the optical disc shown in FIG. 5, there is no need for the optical disc device to read the track counting pits 5 and 6 during data writing, and the preamplifier can be set while passing through the track counting pits 5 and 6. good. Since the laser output power is not switched during seek when the optical disk device needs to read the track count pits 5 and 6, the optical disk device can read the track count pits 5 and 6 without any problem. However, bit 5 for track count
, 6, the servo field becomes large and the capacity decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc that can improve the above-mentioned drawbacks and increase its capacity.

[Means to solve the problem]

To achieve the above object, the present invention provides an optical disc having a clock pit, which is a reference pit for information, and a wobble pit pair in a servo field. A track counting pit is provided and the track counting pit is placed at the head of the servo field, and the distance between at least one of the wobble pit pair and the clock pit, and the distance between the track counting pit and the glock bit. each having two or more predetermined steps, the combination of each step of the distance being three or more predetermined steps, and repeating the combination of each step of the distance in a predetermined order for each one or more tracks. This is something I decided to change.

[For production]

During data writing, when the optical disk device switches the laser output power from the write power to the read power, the preamplification level settles before reading the wobble pit pair, and during a seek, the optical disk device changes the laser output power from the write power to the read power. Detecting track crossings by reading at least one of the track counting pits.

〔Example〕

FIG. 1 shows servo fields for eight tracks in one embodiment of the present invention.

The optical disc of this embodiment has concentric or spiral tracks, one track (track for one revolution) is divided into a plurality of sectors, and each sector is divided into a plurality of blocks. A block consists of a servo field and a data field. Each servo field is provided with a track counting pit 12, a wobble pit pair consisting of wobble pits 13 and 14, and a clock pit 15.
2 is placed at the beginning of the servo field, followed by a wobble pit 13, a clock pit 15, and a wobble pit 14. clock pit 15
are arranged on the center 16 of the track, and at fixed positions in the track direction (for example, at each position where the servo field is divided into 20 in the track direction [12th position P12 in Pl-P2O). The track counting pit 12 is slightly shifted to one side from the center 16 of the track, and is shifted to the opposite side from the wobble pit 13. It is arranged at the third to fifth positions @P3 to P5) in the track direction in the field, and the distance to the clock pit 15 changes in three steps. This 3
There are three or more predetermined combinations of stages,
And it changes repeatedly in a predetermined order every predetermined number of tracks. The wobble pits 13 and 14 are slightly shifted to opposite sides from the center 16 of the track, and one wobble pit 14 is arranged at a fixed position in the track direction (for example, the 15th position P15 in the track direction in the servo field). The distance between the clock pit 15 and the clock pit 15 is constant. The other wobble pit 13 is arranged at a repeatedly shifted position W in the track direction for every predetermined number of tracks (for example, the 7th to 9th positions IP7 to P9 in the track direction in the servo field), and is disposed at a position W that is repeatedly shifted from the clock pit 15 to the clock pit 15. The distance between them changes in three stages. This 3
There are three or more predetermined combinations of stages,
And it changes repeatedly in a predetermined order every predetermined number of tracks.

FIG. 2 shows servo fields for 16 tracks in another embodiment of the invention.

In this embodiment, in the above embodiment, wobble pit 1
4 and the clock pit 15 are reversed, and the clock pit 15 is located at a certain position in the track direction (for example, each position P1 where the servo field is divided into 21 parts in the track direction).
It is placed at the 16th position [Pl6] in ~P21. The track counting pits 12 are arranged at repeatedly shifted positions in the track direction for each predetermined number of tracks (3rd to 5th positions 23 to P5 in the track direction in the servo field), and are located between the clock pits 15 and the clock pits 15. The distance changes in three stages. The combination of these three stages has three or more predetermined stages, and changes repeatedly in a predetermined order for each predetermined number of tracks. The wobble pits 13 are arranged at positions that are repeatedly shifted in the track direction for each predetermined number of tracks (7th to 9th positions P7 to P9 in the track direction in the servo field), and the distance between them and the clock pits 15 is The wobble pits 14 are arranged in three stages, and the wobble pits 14 are repeatedly arranged in the track direction for every predetermined number of tracks at shifted positions @ (12th and 13th positions P12 and P13 in the track direction in the servo field 11). The distance to the pit 15 changes in two steps. Each combination of these three stages and two stages is a predetermined three stages.
There are more than one stage, and the number of tracks changes repeatedly in a predetermined order for each predetermined number of tracks.

The optical disc of each of the above embodiments is set in an optical disc device and rotated by a motor, and an optical pickup irradiates a target track on the optical disc with a laser beam of writing power from a laser, thereby writing data in a data field. In addition, the optical pickup irradiates the optical disk with a laser beam with readout power from the laser, and the reflected light is received by a light receiving element.The output signal of this light receiving element is amplified by a preamplifier and outputted, thereby providing data. Data is read from the field. Also, when writing or reading data, the output power of the laser is switched to read power at the servo field, and a signal corresponding to the clock pit 15 is obtained from the preamplifier, but this signal is read from the track. Serves as a timing reference for the data. The signals from the preamplifier include signals corresponding to wobble pits 13 and 14, and the track deviation detection circuit detects the deviation between the optical pickup and the target track on the optical disk from this signal. The detection signal controls the optical pickup to follow the target track. During data writing, the preamplifier settles before reading the wobble pit pair 13 when the optical disk device switches the laser output power from the write power to the read power. Furthermore, track counting pits 12 . included in the signal from the preamplifier. Track crossing of the optical pickup is detected by the track crossing detection circuit from the signal corresponding to the wobble pit 13, and the optical pickup seeks to the target track using the detection signal.

〔Effect of the invention〕

As described above, according to the present invention, in an optical disk having a clock pit, which is a reference pit for information, and a wobble pit pair in a servo field, there is one in addition to the clock pit and the wobble pit pair in the servo field.
or more track counting pits are provided, and the track counting pits are arranged at the head of the servo field, and the distance between at least one of the wobble pit pair and the clock pit is determined by the distance between the track counting pit and the clock pit. The distance between each track is set to two or more predetermined steps, the combination of each step of the distance is set to three or more predetermined steps, and the combination of each step of the distance is set to a predetermined combination for each of one or more tracks. Since the optical disc device can read the track counting pit and at least one of the wobble pit pair and detect track crossing, the number of track counting pits can be reduced. Even without providing a blank, when the optical disk device switches the laser output power from write power to read power while writing data, the preamplifier will settle before reading the wobble pit pair, increasing the capacity. .

[Brief explanation of drawings]

1 and 2 are plan views showing a portion of each embodiment of the present invention, and FIGS. 3 to 5 are plan views showing a portion of each conventional optical disk. 11... Servo field, 12... Track count bit, 13.14... Wobble pit, 15... Clock bit.

Claims (1)

[Claims] In an optical disk having a clock pit, which is a reference pit for information, and a wobble pit pair in the servo field, one or more track counting pits are provided in the servo field in addition to the clock pit and the wobble pit pair, and this track counting is performed. The distance between at least one of the pair of wobble pits and the clock pit, and the distance between the track counting pit and the clock pit are each set to two or more predetermined steps. An optical disc characterized in that the combinations of the distance steps are three or more predetermined steps, and the combinations of the distance steps are repeatedly changed in a predetermined order for each one or more tracks.