JPS6139248A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To improve the recording density to nearly twice in comparison with the center of a recording tack used as an information recording region as a conventional method by using an edge part of a recording track as the information recording region. CONSTITUTION:A recording optical beam 17 is irradiated on the edge 18 of a recording track 16 to form a pit 15. In this case, since the recording optical beam 17 irradiates accurately the edge 18, it is better to record data by applying position control while a tracking track 13 is scanned by a tracking optical beam 14. Since the information is recorded on the edge 18 of the recording track 16 and the edge 18 is used as the information recording region, the information is recorded on both edges of the recording track and the recording density is nearly doubled in comparison with a conventional method where only the center of the recording track is used as the information recording region.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an optical information recording carrier with a high recording density, and more specifically, to an optical information recording carrier with a high recording density, and more specifically, an optical information recording carrier with a double recording density by recording information on the edge portions of recording tracks. Regarding information record carrier.

[Technical background of the invention and its problems]

There are two types of optical discs when classified from the point of view of recording and playback. That is, there are writable optical discs and read-only optical discs.

Optical discs that can only be played back are used as video discs and compact discs, and these optical discs are copied from master discs that already have information such as video and audio recorded on them, and cannot be used for additional recording. It is.

On the other hand, recording on a writable optical disc is performed by irradiating a light beam such as a laser onto a light-sensitive recording material film formed on a disc substrate, focusing the beam to a microscopic diameter of 1 μm or less. There are methods to form irregularities and pits by melting and evaporating the film, and methods to change the reflectance and transmittance of the photosensitive recording material film by irradiating it with a light beam to form shading of the reflectance, etc. It is being

In the master optical disk for producing the above-mentioned optical disks that can be recorded and played back or optical disks that can only be played back, concentric or spiral grooves are formed in advance on the disk before information is recorded. . This groove is also called a pre-group, and is effective in making tracking easier, preventing the light beam from flying off due to equipment vibration, etc., and making it easier to detect the track position when recording a track address code. be.

As described above, among the optical discs on which pregroups are formed, there are optical discs that are preformatted by putting address signals for identifying specific tracks in some of the tracks.

For example, Japanese Patent Application Laid-Open No. 59-5449 discloses an optical disc comprising a substrate 3.1, a photosensitive recording material film 32, and a guide track as shown in FIG. By changing the width of the guide track 33 (tFIJ) of this optical disc, an address signal 36, which is an auxiliary signal, is recorded.

・Furthermore, main signals such as video and audio signals are recorded by irradiating the light beam 34 onto the center of the guide track 33 to form a pit.

The process of creating a video disc or compact disc can be applied to the formation of the force guide track 33 and the toothed groove. That is, 7 photoresist is applied to a predetermined thickness on a glass substrate, and a predetermined groove is formed by irradiating a light beam such as an argon laser. At this time, the width of the groove can be changed by changing the spot diameter of the laser, as disclosed in Japanese Patent Laid-Open No. 59-5449. After laser irradiation, development is performed to form uneven tracks, a stamper is made from the obtained laser processed product, and a stamper is used to mold the substrate, plate 3.1, on which the grooves have been transferred. can get. Thereafter, a photosensitive recording material film is formed on the substrate 3'1, and the main signal is recorded.

The recording method such as this auxiliary signal is performed only when forming the substrate 31 of the pre-group.
It is not applicable to recording the main signal.

Attempts have been made to improve the recording density of the main signal in the various optical discs described above.

For example, attempts have been made to reduce the shape of the pit 35 or to narrow the width of the guide track 33.

However, there is a problem in that it is not easy to improve the recording density with the conventional method because there are limits to the focusing of the light beam, the power, the sensitivity of the recording material, the track width, etc.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide an optical information recording carrier with significantly increased recording density.

[Summary of the invention]

As a result of extensive research, the inventors of the present invention have discovered that information can be recorded on both edges of the recording track of an optical information recording carrier in which concentric or spiral grooves are formed! By forming a pit in the center of the recording track, we have invented an optical information recording carrier that can almost double the recording density compared to the case where pits are formed in the center of the recording track.

That is, the optical information record carrier of the present invention is an optical information record carrier in which concentric or spiral grooves are formed and a recording track and a tracking track are defined by the grooves, in which at least one of the recording tracks is defined by a recording track and a tracking track. It is characterized in that information is recorded on the edge part of.

The optical information recording carrier as used in the present invention means an optical disk master for producing a recordable/readable optical disk and a readable only optical disk.

In the present invention, concentric or spiral grooves are first formed. This groove can be formed by applying the same process for creating video discs and compact discs.

In other words, in the case of an optical disc that can be recorded and played back, photoresist is coated on a glass substrate to a predetermined thickness, irradiated with a light beam, developed, uneven tracks are formed, and plastic molded from a stand bar. By doing so, the desired substrate can be obtained. Tl1-C on this substrate.

TlQx, Te-8e, To-C8,, Tl-Ti
- A recording film is formed using a recording material such as a Tl1 alloy such as Ag-8*; an organic dye such as a pentamethine dye or a squarylium dye. The optical disc thus obtained is shown in FIG. In FIG. 1, 11 is a substrate;
2 represents a recording film, a 13-layer groove, and a tracking track.

On the other hand, in the case of an optical disk master that can only be played, an adhesive coating agent is applied onto the glass substrate, and a photoresist is applied on top of it to a predetermined thickness, in this case a thickness corresponding to the depth of the groove after development. A master disc is obtained by coating the film by, for example, a rotation method, irradiating it with a light beam, and developing it.

The master disk obtained in this way is shown in FIG.

In FIG. 2, 21 is a substrate, 26 is an adhesion aid, 22
23 represents a photoresist, and 23 represents a groove and a tracking track.

In either case of FIG. 1 or FIG. 2, it is preferable that the groove to be formed has a rectangular cross section.

By forming the grooves, concave portions and convex portions are formed on the disk. In that case, either the concave portion or the convex portion may be used as a recording track.

It is preferable to use the convex portions as recording tracks and the concave portions as tracking tracks.

In forming this groove, when the wavelength λ of the light beam and the numerical aperture NASk of the lens are constants determined by the shape of the aperture of the lens and the intensity distribution of the cross section of the incident beam, the spot diameter d of the light beam is: ? To avoid crosstalk during recording and playback, it is necessary to
The track width line of the recording track is preferably set to 3% or more, and the track width of the tracking track is preferably set to 6 or more. When the width of the recording track is 39/2 and the width of the tracking track is d, the optical information of the present invention The recording density of the record carrier is the highest. Therefore, when the constraints on optical systems such as lasers and lenses are severe, wavelengths and lenses can be selected by changing the track width.

In the present invention, the signals to be recorded on the optical disc or master disc in which grooves are formed as described above include video signals, audio signals,
The main element is an information signal such as a color signal, and does not include an auxiliary signal such as a track address signal.

Information is recorded by irradiating the edge portion of the recording track with a light beam corresponding to such an information signal to form semicircular or semi-elliptical pits or by changing the reflectance-transmittance of the irradiated area. . When irradiating the edge portion of the recording track with a light beam corresponding to this information signal, the tracking light beam is scanned over the tracking track so that the edge portion of the recording track is irradiated with the light beam correctly. It is better to perform position control.

For example, in the optical disc shown in FIG. 1, the pits 15 are formed by irradiating the recording light beam 17 onto the edge portion 18 of the recording track 16. At this time, in order to accurately irradiate the edge portion 18 with the recording light beam 17, it is preferable to perform recording by controlling the position while scanning the tracking track 13 with the tracking light beam 14.

In the master disk shown in FIG. 2, pits are formed by irradiating the edge portion 28 of the recording track 22 with the recording light beam 27, as in FIG. Position control is performed using the tracking light beam 24 in the same way as in the case of FIG.

In this way, information is recorded on the edge part of the recording track,
Since the edge portion is used as the information recording area, information can be recorded on both edge portions of the recording track, making it possible to approximately double the recording density compared to the conventional case where only the center portion of the recording track is used as the information recording area. can.

Furthermore, in the case where eight concentric grooves are formed in the optical information recording carrier as described above, recording is performed sequentially from the inner circumference to the outer circumference, or from the outer circumference to the inner circumference. good. On the other hand, in the case of a spiral, different signals are input at both ends of one recording track, and are recorded by selecting either the left edge or the right edge from the inner area to the outer periphery or vice versa. I do. Furthermore, it is also possible to record the signal continuously from the outer circumference to the inner circumference (for example, by first recording the signal from the inner circumference to the outer circumference on the left edge, and then moving to the right edge when the signal reaches the outermost circumference). can.

As described above, information recorded on the edge portion is also reproduced by irradiating the edge portion with a reproduction beam in the same manner as during recording.

[Embodiments of the invention]

Example 1 Recording was performed on an optical disk capable of recording and reproducing as shown in FIG.

First, Te-CJ with a thickness of 0.13 μm was deposited on a plastic substrate with a continuous spiral groove by snotting T. (tellurium) in CH4 gas.
[I was formed and used as a recording film.

At this time, the width of the recording track is 1.2 μm, the width of the racking track is 0.8 μ”1) the depth of the rack is 0
．． It was a 2μ falcon.

A semiconductor laser with a wavelength of 800 nm was focused to a diameter of 0.4 μm, and the edge portion of the recording track was irradiated with a light beam corresponding to an information signal to form pits and recording was performed.

In an optical disc having the track size as described above, the recording density when recording was performed on the edge portion of the recording track was 3.0 Gbyt@/'ii.

On the other hand, when recording is performed in the center of the recording track as in the past on an optical disk of the same size as above and the same track size, the recording density is increased to 1.4 Gbytes.
・There were 7 pages.

Example 2 Recording was performed on a master optical disc that can only be played back, as shown in FIG.

First, a hexamethyldisilazane/karariru adhesion aid was applied onto a glass substrate, and a photoresist was applied thereon to a thickness of 0.1 μm using a rotation method. It was exposed to a light beam and developed to form spiral grooves.

At this time, the width of the recording track was 1.2 μm, and the width of the tracking track was 0.8 μm.

Wavelength 4! i8fimOAr'' laser was narrowed down to o, spm diameter, and the edge part of the recording track was irradiated with a light beam according to the information signal to form pits and recorded. In the master disk of Kyo φ, the recording radius was set to 145 m1 from 55 Kyo, and when recording was performed on the edge of the recording track at a constant angular velocity of 18 GO rpm, the recording density was 1 hour/side for moving images.

On the other hand, when recording was performed in the center of the recording track in the conventional manner on an optical disk having the same size of master disc as above and the same track size, the recording density was 0.5 hours/side.

〔Effect of the invention〕

As detailed above, in the optical information recording carrier of the present invention, the edge portion of the recording track is used as the information recording area, so compared to the conventional case where the center portion of the recording track is used as the information recording area, the recording density is approximately 2 It can be doubled, and its industrial value is great in the information society〇

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram when the present invention is applied to a dangerously optical disc that allows recording and playback, Fig. 2 is a schematic diagram when the present invention is applied to a master of an optical disc that can only be reproduced, and Fig. 3 is a conventional diagram. FIG. 2 is a schematic diagram showing an example optical disc. Explanation of symbols 11. 21, 31S substrate 12, 32: Recording film 13.
23:) Rucking track 16.22: Recording track 15, 25: Pit 1B
, 28: Edge portion 26: Adhesion aid 17.27:
Recording light beam 14.24:) Racking light beam Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In an optical information recording carrier in which concentric or spiral grooves are formed and a recording track and a tracking track are defined by the grooves, at least one edge of the recording track An optical information recording carrier, characterized in that information is recorded on a portion of the optical information recording carrier. 2. The optical information recording carrier according to claim 1, wherein the recording track is either a concave portion or a convex portion of the optical information recording carrier formed by the groove. 3. The optical information recording carrier according to claim 1, wherein the groove has a rectangular cross-sectional shape. 4. Optical information according to claim 1, wherein the minimum track width of the recording track is 3/2 of the optical beam spot diameter, and the minimum track width of the tracking track is equal to the optical beam spot diameter. record carrier. 5. The optical information recording carrier according to claim 1, wherein the information recorded on the edge portion is a video and/or audio signal.