JPS62139151A - Optical disk - Google Patents

Abstract

PURPOSE:To attain a large capacity by recording information both in a pregroup and its adjacent pregroup. CONSTITUTION:In terms of an optical disk comprising by forming a recording layer 3 on an optical disk substrate 1 through a protective layer 2, information is recorded both in the pregroup 5 and its adjacent pregroup. With the advanced tracking technique the pitch of the pregroup 5 is reduced to 1.6mum from 2.5mum. On the other hand a projection part lying in a groove between the pregroups remains flat. Thus a recording density can be substantially improved, and information can be correctly read out by forming an ID part installed the top of the pregroup at a shifted position.

Description

[Detailed Description of the Invention] [Summary] An optical disc substrate in which the number of recording layers (2) is doubled by recording information not only in the pregroove but also in the gap between the pregrooves.

[Industrial application field]

The present invention relates to the structure of an optical disk disc with increased recording density.

Optical disk (:l) A memory that uses laser light to record high-density information.The recording layer has advantages such as being able to perform recording and playback with human contact, and being less susceptible to LJ due to the influence of dust. It has a number of features.

That is, the laser beam is transmitted by the lens so that the diameter is about Itt.
The area can be narrowed down to a small spot of m, and therefore the area required to record information for one focus is approximately 1tm2.

Therefore, compared to the 1lfi disk or magnetic tape, which requires a surface 41i of several tens to hundreds of μm2 to record information on one pit, it requires a much smaller surface 41i.
[l! Recording is possible.

FIG. 1 is a plan view and a sectional view of an optical disk for explaining the present invention, and its structure is the same as the conventional one.

Of course, the optical disc substrate 1 is made of polymethyl methacrylate.
1. (abbreviation PMMA) and polycarbonate (abbreviation 11)
C) or other plastics (transparent materials such as glass, 1)
Then, a pre-groove (guide? Nf) indicating the recording position of information is formed on 1-L of the optical disc substrate 1. The recording layer 3 is formed through the
Two optical disk substrates 1 are arranged facing each other by a spacer ring 4 with the recording layer 3 on the inside, and are fixed.

And recording information and 100 no. 1: Optical disk 1 (board 1
1111 is projected from the outside onto the recording layer at the pregroove position, and 3L is used to utilize the fact that the phantom reflectance changes due to light interference and the rotation direction of polarized light changes depending on the presence or absence of information. More and more are being released.

The present invention relates to the structure of an optical disc that significantly increases the recording density when recording information on the 2I recording layer.

[Prior Art] Various types of recording layers with different information recording methods have been put into practical use in optical discs.

In other words, there is a read-only memory that uses a low-melting point metal as a recording medium and records information by the presence or absence of holes (pips). Ijrasahle Memory
), and also uses a vertical 411 film as a recording medium,
Laser 11. The magnetization reversal caused by the temperature of the magnetic film subjected to α radiation is used for writing information, and the rotation of the polarization plane of the reflected light differs depending on the magnetization h direction is used for reading.) Rewriting 1 possible There's also memory.

Although there are various recording methods as described above, all of them still involve recording information in the pregroove position provided on the optical disc) &FiJQ/f'.

Zuna Sai) also has a concentric or spiral shape with a width of 0.5-0.8 μm, an iM of 0.05-0, +18 m, and a large number of pregrooves with a pitch of about 1.6 μm. A used optical disk plate l with a pregroove is prepared by casting, for example, PMMA resin onto a molded stamper. A recording layer 3 is formed via the lower protective layer 2 by vacuum evaporation, sputtering, or the like.

In the case of an optical disc substrate in which pregrooves are formed concentrically, each pregroove is divided into a plurality of pieces in advance during substrate molding, and the track number is placed on the smooth part at the leading position.
, sector number, clock signal, etc. are recorded, and the emotion is recorded in the pregroove following this.

Further, in the case of an optical disk substrate in which a pregroove is formed in a spiral shape, these l and rank information (U) are recorded at the beginning position of the pregroove.

Optical discs are formed with this structure,
As tracking technology advances, improvements are being made in the direction of increasing the recording density of information by narrowing the interval between pregrooves.

[Problems to be Solved by the Invention] As described above, increasing the capacity of optical discs is progressing in the direction of reducing the spacing between pregrooves, which are formed in large numbers concentrically or spirally. At this time, there is a problem that the laser spot also irradiates the adjacent pregroove, resulting in poor l-rank followability.

Therefore, there is a need for another method to increase capacity.

[Means for solving problems]

The problem described in ``-- is achieved by an optical disk in which a recording layer is formed on an optical disk substrate H via a protective layer, and information is recorded both in the pregroove and in the adjacent pregroove position. be able to.

[Effect]

The present invention improves the positioning accuracy of the pre-groove laser spot by one line, one line, and one line, by the advancement of l-ranking technology.
It is something that has been improved from time to time.

However, the pitch of the pregroove has been reduced from the original 25 pm to 1.6 μm due to the advancement of tracking technology.

On the other hand, the ridges between the pregrooves remain flat.

The present invention focuses on this point and writes information in this portion as well.

Here, there are two types of optical disk substrates: one in which the pregroove is formed concentrically, and the other in which the pregroove is formed in a spiral shape.In the former case, information such as track number and sector number is stored. In this case, the present invention has to be recorded with good reliability.In order to implement the present invention, the recording position of the track information (hereinafter referred to as the ID section) must be set in the pre-groove or in the pre-groove. When writing between grooves, the writing position may be shifted in the circumferential direction.

〔Example〕

FIG. 2 is a perspective view showing a conventional state of writing trunk information, and FIG. 3 is a perspective view showing a method of implementing the present invention.

FIG. 2 shows a part of the optical disc substrate 1 on which the pregroove 5, track information 6 is formed from a stamper, and if) part 6 is located at the same position of the pregroove formed concentrically. are formed at regular intervals.

FIG. 1A schematically shows this, and the hi-radial solid line 7 shown here indicates the Ir) portion 6.

The present invention records information in the flat gap 8 between the existing pregrooves 5 formed in this manner.

When using such a method, it is best to form the ID part at a different position from the conventional method to ensure the reliability of the ID part formed during molding of the optical disc substrate, but the 31st edition changes this. In the perspective view shown in the figure, the pregroove 5 was formed as shown in the gap neck.

The broken line 9 shown in FIG. 1(A) shows the case where the If) portion 6 is formed at an intermediate position as in the conventional case, and crosstalk regarding track information can be completely eliminated.

Note that the same applies to the case where the pregroove is formed in a spiral shape, and the reliability of the optical disc according to the present invention can be improved by forming the pattern with the ID portion 6 shifted.

〔Effect of the invention〕

According to the present invention, it is possible to greatly improve the recording density, and by forming the 10 portions provided at the beginning of the pregroove in a shifted position, it is possible to read without error.

[Brief explanation of drawings]

FIG. 1 is a plan view (A) and a cross-sectional view (B) of an optical disc, FIG. 2 is a perspective view illustrating trunk information in a pregroove, and FIG. 3 is a perspective view illustrating track information between pregrooves. It is. In the figure, 1 is an optical disc substrate, 3 is a recording layer, 5 is a pregroove, 6 is an ID portion, and 8 is a gap portion. Figure 2 Figure 3

Claims (3)

[Claims] (1) An optical disc comprising a recording layer formed on an optical disc substrate with a protective layer interposed therebetween, in which information is recorded both in a pregroove and in an adjacent pregroove. (2) The optical disc according to claim 1, wherein track information is recorded both in the pregroove and in adjacent pregrooves. (3) The optical disc according to claim 2, wherein the writing position of the track information recorded in the pregroove and between adjacent pregrooves is shifted in the inner circumferential direction.