JPH02189743A - Optical disk - Google Patents

Abstract

PURPOSE:To reduce a cost by recording a signal to the projecting part of a tracking groove on one face and recording the signal on a recessed part of the tracking groove on the other face to apply recording/reproduction to the double-side of the tracking groove. CONSTITUTION:An optical head 10 makes access to the projecting part GU of a tracking groove G to apply recording and reproduction and the other optical head 10 makes access to the recessed part GD of the tracking groove G to apply recording and reproduction. For example, a signal read from a base 5 is recorded to the projecting part GU of the tracking groove G and the signal read from the other side is recorded to the recessed part GD of the tracking groove G. Thus, the double-side of the tracking groove G is used for recording and reproducing the signal. Thus, the cost of the optical disk being a recording medium is halved.

Description

[Detailed Description of the Invention] [Summary] Regarding the signal recording structure on an optical disc, the purpose of reducing the cost of the optical disc is to create a single-sided disc that has a tracking groove on one side of the substrate. Recording is performed on both sides of one tracking groove by recording on the convex portion and recording on the other side in the concave portion of the tracking groove. [Industrial Application Field] The present invention relates to a signal recording structure on an optical disc.

In recent years, new optical disc products are being developed and mass-produced at a rapid pace, but there is a need to significantly reduce the cost of such optical discs.

[Problems to be solved by conventional technology and the invention] Optical discs are of read-only (ROM) type and write-once type.

There are various methods such as rewritable type, but all of them have a configuration in which recording and playback are performed by being guided by a tracking groove.For example, a disk with a diameter of 130m+a has numerous tracking grooves arranged concentrically at a pitch of 1.6μm (tracking grooves). groove)
is provided.

Fig. 3 shows a schematic cross-sectional view of a conventional double-sided optical disc.
00 Peng, thickness 1.2 mm), 3 is the hub (outer diameter 70
sφ), a metal hub is attached to the contact portion of the rotating shaft to prevent damage to the disk, and recording films having tracking grooves are provided inside to face each other, so that the single-sided disk 1. A double-sided optical disc is constructed by pasting two discs together.

FIG. 4 is an enlarged partial view of FIG. 3 and a diagram showing recording/reproducing operations, where 5 is a glass substrate (thickness 1.2 mm+), and 6 is a photopolymer (2P) provided with tracking grooves (pre-groups) G. ) film (film thickness approximately 30 μm), 7 is a magnetic recording film (
10 is an optical head, and 11 is a laser beam. That is, the single-sided disks 1 and 2 are made of glass substrate 5.
A double-sided optical disc is a double-sided optical disc consisting of a photopolymer film 6 and a magnetic recording film 7, which are bonded together using an adhesive 8. Signals are reproduced or recorded by irradiating a laser beam 11 transmitted through the substrate along the tracking groove. In addition, as shown in FIG.
The usual method is to irradiate the concave portion of the tracking groove for reproduction. Recording and reproduction of such signals can be done by, for example,
In a rewritable optical disk, the perpendicular magnetization direction is reversed using a laser beam for recording, erasing, and reproducing. There are various other methods such as recording and erasing by irradiating laser light to change the phase from an amorphous phase to a crystalline phase.

However, as shown in FIGS. 2 and 3, conventional double-sided optical discs have a structure in which single-sided discs are laminated together, so they have the drawback of increasing material costs and processing man-hours.

The present invention proposes an optical disc aimed at reducing the cost of such a double-sided optical disc that uses both sides for recording and reproduction.

[Means to solve the problem]

The problem is, as shown in Figure 1, in a single-sided disk that has a tracking groove on one side of the substrate, one side records in the convex part GU of the tracking groove, and the other side records in the concave part GD of the tracking groove. This problem is solved by an optical disc in which recording and reproduction are performed from both sides of one tracking groove G.

C. In other words, the present invention uses a conventional single-sided disc to perform recording and reproduction from both sides in the same way as a double-sided optical disc. In this way, the single-sided disc can be used to record and reproduce signals in the same way as a double-sided optical disc. This greatly reduces the cost of optical discs.

〔Example〕

Examples will be described in detail below with reference to the drawings.

FIG. 1 is an enlarged partial view of the optical disc according to the present invention and a diagram showing recording/reproduction, and as in FIG. 3, 5 is a glass base vi (
Thickness 1.2mm), 6 is photopoly with tracking groove G? -Jll (#thickness about 30 μm).

7 is a magnetic recording film (M thickness approximately 0.1 μm), 10 is an optical head, and 11 is a laser beam. That is, the optical disc according to the present invention is a single-sided disc 1 itself, and FIG. 2 shows a schematic sectional view of the single-sided disc.

The tracking groove (pre-group) G is formed of a photopolymer (2P) film of ultraviolet curing resin, and its dimensions are, for example, a group width of 0.8 μm, a pitch of 1°6 μm, and a groove depth of 8.
00 nm, and a magnetic recording film 7 is deposited thereon by sputtering, and the magnetic recording film 7 is, for example, ↑bz+F8
It is composed of t+cOs amorphous alloy (terbium iron cobalt amorphous alloy). In addition to the glass substrate, a transparent synthetic resin plate such as PMMA or PC may be used as the substrate.

Thus, as shown in FIG.
accesses the convex portion GO of the tracking groove G to perform recording/reproduction, and the other optical head 10 accesses the concave portion GD of the tracking groove to perform recording/reproduction6. For example, a signal read from the substrate side is read from the tracking groove G. The signal to be read from the opposite side is recorded in the concave portion GD of the tracking groove G. In this way, both sides of a single tracking groove can be used for recording and reproducing signals, and the price of optical discs as recording media can be halved.

Furthermore, access to such optical discs can be performed basically the same as before, with only slight improvements.

Note that the embodiment diagrams in FIGS. 1 and 2 are diagrams in which the magnetic recording film 7 is not coated with a protective film, but since covering with a protective film can prevent damage to the magnetic recording film, at least the magnetic recording film 7 is not coated with a protective film. It is desirable to coat the exposed surface with a protective film.

[Effects of the Invention] As is clear from the above description, according to the present invention, signals are recorded and reproduced on both sides of a conventional single-sided disk, which significantly reduces the cost of optical disks, that is, compared to the conventional double-sided disk. The cost can be reduced to less than half that of optical discs.

FIG. 3 is a schematic cross-sectional view of a conventional double-sided optical disc, and FIG. 4 is an enlarged partial view of FIG. 3 and a diagram showing recording and reproduction.

In the figure, G is the tracking groove (pre-group), GO is the convex part,
GD is a concave portion, 1.2 is a single-sided disk, 3 is a hub, 5 is a glass substrate, 6 is a photopolymer (2P) film, 7 is a magnetic recording film, 10 is an optical head, and 11 is a laser beam.

[Brief explanation of the drawing]

Fig. 1 is an enlarged partial view of an optical disc according to the present invention and a diagram showing recording/reproduction. □Payer Ubun M
And Figure 1, 1 word on both sides, Vigilante L (for Z...5 on one side) Sufu. Toga's confession ■ Figure 2: $3L￥l's jA leaving part a mouth and u＠-kity＠4% for $ll! ]Figure 4

Claims (1)

[Claims] In a single-sided disk that has a tracking groove on one side of the substrate, one side records on the convex part of the tracking groove, and the other side records on the concave part of the tracking groove, so that recording and reproduction can be performed on both sides of one tracking groove. An optical disc characterized by: