JPH04289539A - Optical disk - Google Patents

Abstract

PURPOSE:To suppress the occurrence of crosstalk between tracks even at the time when sector identifier parts and data parts of respective sectors are adjacently arranged on tracks of recessed and projecting grooves with respect to an optical disk on which information is recorded and reproduced with laser light. CONSTITUTION:Information is recorded in a sector identifier part 13S1i of one groove by a light intensity signal, and information is recorded in a data part 13S1d following this sector identifier part 13S1i by a photomagnetic signal. Information is recorded in a sector identifier part 14S1i of the other groove parallel with and adjacent to the sector identifier part 13S1i by the photomagnetic signal, and information is recorded in a data part 14S1d, which follows the sector identifier part 14S1i and is adjacent to the data part 13S1d, by the light intensity signal, and recording areas where information are recorded by the light intensity signal and the photomagnetic signal are alternately arranged in adjacent grooves.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention uses laser light to record,
This invention relates to an optical disc that is played back. In recent years, optical discs have already been put into practical use, and their recording capacity is approximately 540 MB for a 5-inch optical disc, which is the largest capacity among removable recording media. However, in the future, there is a demand for the development of means to further increase the recording density.

0002

2. Description of the Related Art FIG. 2 is a schematic plan view showing an example of a conventional recordable/reproducible optical disc. In the figure, 1 is an optical disk made of a disk-shaped recording medium, 2 is a center hole for mounting the optical disk 1 on a disk motor (not shown), and 3
is a plurality of tracks having a predetermined depth and width formed concentrically or spirally on the surface of the optical disc 1, one of which is representatively shown. The track spacing used is, for example, about 1.6 μm. S1 to Sn indicate information recording areas (hereinafter referred to as sectors) provided by dividing the track 3 on the surface of the disk 1 radially from the center point of the disk 1.

One sector includes a sector identifier area i for storing unique address signals etc. for each track, and a recording/recording area i.
The sector identifier area i and the data area d are usually arranged radially in the radial direction of the optical disc 1, adjacent to each other on a track-by-track basis. Reference numeral 4 indicates a rotation start mark for generating a recording position alignment signal, and arrow P indicates the rotation direction of the optical disc 1.

FIG. 3 is a partially enlarged cutaway perspective view of the track in FIG. 2 and a diagram showing a laser beam irradiation method. In order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and their repeated explanation will be omitted. This figure shows only one side of the optical disc 1, but there are cases where this structure is pasted together to use both sides. In the figure, an optical disc 1 is formed by forming a recording thin film 6 on the surface of a transparent disc base material 5 (e.g., glass, plastic, etc.), and focuses laser light through an objective lens 7, resulting in a spot light 8. is transmitted through the transparent body of the disc base material 5 and irradiated onto the recording thin film 6.

One track 3 consists of a concave groove (also called a land section) 3a and a convex groove (also called a groove section) 3b adjacent thereto, when viewed from the objective lens 7 side. Therefore, sectors S1 to Sn are arranged for each concave groove 3a and convex groove 3b, and each sector is provided with a sector identifier area i and a data area d.

Here, the convex groove 3b adjacent to one track
In order to explain the contents recorded in a typical sector S1 formed on the concave groove 3a, the code of the sector identifier area i of the sector S1 on the track 11 formed on the convex groove 3b is 11S1i, The code of the data section area d that follows this is determined as 11S1d. Similarly, the concave groove 3 adjacent to the convex groove 3b
The code of the sector identifier area i of the sector S1 on the track 12 formed in step a is defined as 12S1i, and the code of the data area d following this is defined as 12S1d.

[0007] Since the normal sector identifier area i is a read-only area, it is necessary to form address information, etc. in advance along the track on the surface of the recording thin film 6 in the shape of uneven pits using an electroforming process or the like. This is done by The playback signal, such as an address signal, is detected by detecting the strength of the reflected light from the uneven shape. Further, recording in the data area d is performed using means such as a light intensity signal or a magneto-optical signal by irradiation with a laser beam.

In the conventional recording method, recording was performed only in the concave grooves 2a in order to avoid crosstalk errors during reproduction, but in recent years, in order to improve the recording density, recording has been performed in the convex grooves 2b as described below. are now being recorded as well.

FIG. 4 is a partially enlarged cutaway perspective view of the area recorded on the track of FIG.
This is shown with reference to 0. In the figure, reference numeral 10 indicates a concave track adjacent to a convex track 11. The convex groove track 11 has a sector identifier section 11 in sector S1.
The uneven shape of S1i is recorded, and a pit signal 9 (information signal) is recorded in the data section 11S1d using a spot light 8 narrowed down by an objective lens 7.

In addition, in the track 12 of the adjacent concave groove, a concavo-convex shape of a sector identifier portion 12S1i is recorded in the sector S1, and a pit signal 9 is recorded in the data portion 12S1d. The feature of this recording method is that the uneven recording area of the sector identifier part 11S1i of one track 11 and the sector identifier part 12S of the adjacent track 12 in the same sector S1
The point is that the uneven recording areas of 1i are arranged so as not to be adjacent to each other. However, it is permissible for the grooves to be adjacent to each other with at least one concave groove or convex groove interposed therebetween.

By arranging the sector identifier areas i in which address signals having the same type of irregularities are recorded so that they are not adjacent to each other between tracks, it is possible to reproduce stable address signals without crosstalk, and the recording density can be increased. Improving.

0012

According to the conventional recording method, the arrangement format of each sector must be shifted by the dimensional length of the sector identifier area for each adjacent track. Moreover, the dimensional length of the data section is generally longer than that of the sector identifier section, so arranging the sector identifier sections so that they are not adjacent between tracks means that most of the data sections are adjacent to each other. This arrangement is inevitable. Therefore, even if it is possible to suppress the occurrence of crosstalk errors between sector identifier sections between adjacent uneven groove tracks, there is a drawback that crosstalk errors may occur in sections where data signals are arranged adjacently. .

The present invention has been made in view of the above-mentioned drawbacks of the conventional art, and even if the sector identifier part and the data part of each sector are arranged in concave groove and convex groove tracks so as to be adjacent to each other, crosstalk between tracks occurs. The purpose of the present invention is to provide an optical disc that can suppress the occurrence of.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present invention, as shown in FIG. Each groove 3a, 3b has a sector identifier area i for recording address information etc. and a data area d for storing data as a pair. Sectors S1 to Sn configured
In an optical disk that is divided radially in the circumferential direction at , and optically or magneto-optically records or reproduces information in sectors S1 to Sn of each groove using a laser beam,
In one of the grooves, a sector identifier section 13S1 is provided with a light intensity signal.
i, and recorded in the data section 13S1d following the sector identifier section 13S1i as a magneto-optical signal,
A magneto-optical signal is recorded in the sector identifier part 14S1i of the other groove parallel to and adjacent to the sector identifier part 13S1i, and a light intensity signal is recorded in the data part 14S1d adjacent to the data part 13S1d following the sector identifier part 14S1i. However, recording areas for optical intensity signals and magneto-optical signals are arranged alternately for each adjacent groove.

[0015]

[Operation] In the track of the concave groove 3a, the sector identification part records with a light intensity signal and the data part uses a magneto-optical signal, and in the track of the adjacent convex groove 3b, the sector identification part records with a magneto-optical signal and the data part records with a magneto-optical signal. By alternately recording with intensity signals, on the optical disk, any part of the optical disk where the optical intensity is recorded is recorded with a magneto-optical signal, and the adjacent track is recorded with a magneto-optical signal. Since recording is performed next to the track using a light intensity signal, it is possible to prevent crosstalk from occurring due to the difference in signal detection principles.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a cutaway view of an optical disc showing an embodiment of the present invention. In this embodiment, a pit portion corresponding to a light intensity signal is formed in advance on a substrate with a laser beam guide groove. Next, a protective film, a recording film, and a protective film are formed on this substrate in this order by sputtering. In this case, the recording film may be made of a rare earth-transition metal amorphous alloy having the Kerr effect, and TbFeCo was used here.

The protective film may be any film as long as it has both the effect of protecting the recording film from oxidation and the like and the enhancement effect of increasing the Kerr rotation angle.
iO2 was used. Moreover, polycarbonate was used for the substrate. In this embodiment, in the groove, the sector identifier part is a light intensity signal and the data part is a magneto-optical signal.
It is possible to have compatibility with conventional optical discs. Furthermore, since the data section in the convex groove is provided as a pre-bit, it can be used as a partial ROM.

In this embodiment, since adjacent tracks are always recorded with different recording signals (if it is a magneto-optical signal, the adjacent track is recorded with a light intensity signal, or vice versa), crosstalk is caused by recording in the convex groove. This is almost the same level as a conventional optical disc (neighboring signals are not detected). As a conventional example, when a magneto-optical signal with a bit length of 2.4 μm is recorded in the concave groove and a magneto-optical signal is reproduced from the convex groove, the carrier level (concave groove) - carrier level (convex groove) = 23 dB
was gotten.

[0019]

[Effects of the Invention] According to the present invention, it is possible to achieve approximately twice the density compared to the conventional method. Moreover, since the magneto-optical signal is recorded next to the optical intensity signal, and the optical intensity signal is recorded next to the magneto-optical signal, the effect of crosstalk is the same as before even if there is no gap between tracks. be.

[Brief explanation of the drawing]

FIG. 1 is a cutaway view of an optical disc showing an embodiment of the present invention.

FIG. 2 is a schematic plan view showing an example of a conventional recordable/playable optical disc.

3 is a partially enlarged cutaway perspective view of the track of FIG. 2; FIG.

4 is a partially enlarged cutaway perspective view of the area recorded on the track of FIG. 3; FIG.

[Explanation of symbols]

3 Track 3a Concave groove 3b Convex groove 13S1i, 14S1i Sector identifier section 13S1d
, 14S1d Data part i Sector identifier part area d Data part area S1 to Sn sector

Claims (1)

[Claims] [Claim 1] A groove (3a) having a predetermined depth and width.
and convex grooves (3b) parallel to and adjacent to the concave grooves (3a) are arranged in parallel in a concentric or spiral manner, and each groove (3a, 3b) has address information. A sector identifier area (i) for recording data, etc., and a data area (d) for storing data are divided radially in the circumferential direction into sectors (S1 to Sn) each configured as a pair, and each is divided radially in the circumferential direction. The sector (S
1 to Sn), in which recording or reproduction is performed optically or magneto-optically, in one of the grooves, a light intensity signal is recorded in a sector identifier part (13S1i), and data following the sector identifier part (13S1i) is recorded. Part (13S1d
), a magneto-optical signal is recorded in the sector identifier part (14S1i) of the other groove parallel to and adjacent to the sector identifier part (13S1i), and a magneto-optical signal is recorded in the sector identifier part (14S1i) following the sector identifier part (14S1i). The data section (13S
An optical disc characterized in that a data portion (14S1d) adjacent to 1d) is recorded with a light intensity signal, and recording areas of the light intensity signal and magneto-optical signal are arranged alternately in each adjacent groove.