JPS61287059A - Optical disc - Google Patents

Abstract

PURPOSE:To eliminate storing of valueless information by mixing a recording layer in which the information record by light is not erasable with a recording layer in which the information recorded by light is erasable and re-recordable. CONSTITUTION:An optical disc 1 consists of the recording layer 3 (additive- writing recording layer) to which information is able to be additionally written and unerasable, a substrate 2a on one surface of which the said recording layer is laminated, the recording layer erasable recording layer) 4 which information is able to be recorded in, erased from, and rewritten in, and a substrate 2b on one surface of which the said layer 4 is laminated. The layers 3 and 4 are made face each other, and an annular spacer 6 is provided between them. Since the layer 3 disables any erasure of the information once recorded in itself, erroneous erasure never occurrs, so permanent storeing is able. By constituting the additive-writing recording layer and the erasable recording layer in one disc, the advantages of the both is utilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical disc on which information can be recorded and reproduced using light.

[Technical background and problems of the invention]

2. Description of the Related Art Recently, the existence of optical discs, which can record and reproduce information using light, have been attracting attention as large-capacity memories. Commonly known discs include, for example, video discs and audio compact discs. In addition, image files or document files using writable write-once optical discs have already been put into practical use in large-scale offices.

Optical discs are playback-only and write-once type.

It can be classified into three types: rewrite type, but among them, write-once type and rewrite type have the following drawbacks.

The reason is that new information can be written in the unrecorded portion of a write-once optical disc, but information that has already been written cannot be erased, and new information cannot be written in this portion. As a rewritable optical disk, for example, a magneto-optical disk has been proposed, which can be erased and rewritten like a conventional magnetic medium. However, this magneto-optical disk has poor reliability as a disk medium.

There are problems such as the inability to overwrite information and the difficulty in adjusting the output of light such as laser light when recording information on this magneto-optical disk.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an optical disc that takes advantage of the advantages of write-once optical discs and erasable optical discs.

[Summary of the invention]

The outline of the present invention for achieving the above object is to provide an optical disc having a recording layer capable of recording and reproducing information using light.
Hikari IJI is characterized by a mixture of a recording layer in which information recorded by light cannot be erased and a recording layer in which information recorded by light can be erased and re-recorded! Ink.

[Embodiments of the invention]

FIG. 1 is an external perspective view of an optical disc according to an embodiment of the present invention. As shown in the figure, the shape of the optical disc 1 is a perfect circle centered on the center hole 5, and the outer diameter thereof can be set to any desired outer diameter, for example, 30 cm, 12 cm, etc.

FIG. 2 is a sectional view of the optical disc of the present invention.

In the figure, an optical disc 1 includes a recording layer 3 (hereinafter referred to as a write-once recording layer) on which information can be written once again by light but cannot be erased, a substrate 2a on which this recording layer is laminated on one side, and a substrate 2a on which information can be written once again by means of light. It has a recording layer 4 capable of recording, erasing and re-recording, and a substrate 2b (hereinafter referred to as an erasable recording layer) provided with this recording layer 4 laminated on one side, and the write once recording layer 3 and this erasable recording layer 4 face each other, and a ring-shaped spacer 6 is sandwiched between them. A center hole 5 is provided in the center of this optical disc so that it can be connected to a drive device (not shown) for rotating this optical disc 1.

In the optical disc l having the above configuration, the substrates 2a, 2
b is a glass plate, for example, and on the surface of the glass plate on which the recording layer 3 is to be formed, guide grooves 13 shown in FIG. The recording layer 3, for example, Pb-T'e-Se, is provided by vapor deposition on the surface on which the guide groove 13 is formed. Next, the erasable recording layer 4 is, for example, a magneto-optical disk, which is made of a disk substrate such as polycarbonate and an amorphous magnetic material such as Tb-Fe-C.
By forming a perpendicularly magnetized film with aligned magnetization directions such as o,
This is used as a recording layer.

FIG. 3 is a sectional view of another embodiment of the optical disc of the present invention shown in FIG. 2. In the figure, optical disc 1
In this example, a write-once recording layer 3 and an erasable recording layer 4 are laminated on both sides of a substrate, for example, a glass plate 2.

Furthermore, a protective layer 7 is laminated on the surfaces of the write once recording layer 3 and the erasable recording layer 4, and is made of plastic or the like to protect the respective recording layers from scratches, fingerprints, oxidation, etc. It consists of

FIG. 4 shows a schematic perspective view of a recording and reproducing apparatus for recording and reproducing information onto an optical disc l using light. In the figure, an optical head 1O for recording and reproducing information on the write-once recording layer 3 of an optical disc 1 using light, for example, laser light, a motor 11 for rotationally driving this optical disc, and the optical head 10 are shown. It consists of a linear actuator 12 for moving the write-once recording layer 3 along, for example, a guide groove 13. Note that each of these parts is controlled via a control part (not shown).

FIG. 5 is an explanatory diagram for explaining recording and reproduction of information on the erasable recording layer 4. In the figure, (a) shows the relationship between a coil 20 that applies a magnetic field for recording information on an erasable recording layer 4 provided on an optical disk and a substrate 2 on which the erasable recording layer 4 is formed. FIG. 5B shows a state in which information is recorded using, for example, a laser beam focused by the objective lens 21 while a magnetic field is being generated in FIG. The figure (c) is the above (a)
), shows the information recording portion 22 resulting from the information recording action shown in (b).

Information recording onto the write-once recording layer 3 using light is performed using an information recording/reproducing apparatus such as an optical head 10 as shown in FIG.
It is carried out by For example, a laser beam is irradiated from the optical head 10 toward the recording layer 3 of the optical disc 1, and the recording layer 3 is melted by the energy of the laser beam to form holes (bits) to record information. In order to reproduce information from the pits formed in the recording layer 3, the optical head 10 tracks the pits with a radar beam having a weaker output than the laser output used during recording, for example, about 5n+W. can be played. This reproduction information is reproduced as a signal based on, for example, the difference in reflectance between the bits formed in the recording layer 3 and the laser beam irradiated to the other areas, and this signal is taken in again from the optical head 10 and transferred to, for example, a CRT (not shown).
The area irradiated with laser light can be reversed even with a weak magnetic field of about 100 oersteds. Also, since the part not irradiated with laser light is at room temperature, it does not reverse even if a magnetic field is applied. That is, the laser beam determines the recording area, and the spot diameter of the laser beam narrowed down by the objective lens 21 is about 1 μm, making it possible to record at a very high density. In order to erase this recorded information, by reversing the direction of the magnetic field applied at the same time as the laser beam, the state can be returned to a state where no information is recorded.

The aforementioned write-once recording layer 3. According to the optical disc of the present invention having the erasable recording layer 4, by providing the write-once recording layer 3 and the erasable recording layer 4 in one disc, the characteristics of each recording layer can be utilized. In the magneto-optical recording layer 4 described above, new information can be recorded using light in a portion where information has already been recorded. In other words, the operation of erasing and recording can be performed as many times as you like, so for example, if medical management record data is initially recorded, and after this data is used, this data is no longer needed, and then specific data within this data is When a case arises where it is desired to record and preserve only this specific data, this specific data can be recorded in the write once type recording layer 3, other data can be erased according to the principle shown in FIG. 5 mentioned above, and new data can be inserted and used. It becomes like this.

Although the write-once recording layer 3 records information, it is impossible to erase the information based on the above-mentioned principle, so there is no possibility of erroneous erasure (information can be stored permanently). By having a write-once recording layer and an erasable recording layer in one disc in this way, it is possible to take advantage of the advantages of these two recording layers, so the above-mentioned effects can be achieved compared to when they are used alone. You can get it.

The present invention is not limited to the embodiments described above, and can be implemented with various modifications within the scope of the gist of the present invention. For example, as shown in FIG. 6, a write-once recording layer 3 and an erasable recording layer N4 are placed on one side of the optical disc 1, and the write-once recording layer 3 is placed on the inside.
may be provided, and an erasable recording layer 4 may be provided on the outside.

〔Effect of the invention〕

As detailed above, the present invention has a write-once recording layer and an erasable recording layer of one disc, so that only necessary information is recorded and stored in the write-once recording layer, and other information is stored on the erasable recording layer. Since recording and erasing can be performed in layers, it is possible to provide an optical disc that does not store unnecessary information.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of an embodiment of the optical disc of the present invention;
FIG. 2 is a sectional view of the optical disc shown in FIG. 1, FIG. 3 is a sectional view of another embodiment of the optical disc of the present invention, and FIG. , a schematic perspective view for explaining the reproduction method, FIG. 5(a),
(b) and (c) are explanatory diagrams of a method for recording and reproducing information on the erasable recording layer 4, and FIG. 6 is an external perspective view of another embodiment of the optical disc of the present invention. 1... Optical disc, 3... Write-once recording layer, 4...
Erasable recording layer.

Claims (1)

[Claims] An optical disc having a recording layer on which information can be recorded and reproduced by light, characterized by having a recording layer in which information recorded by light cannot be erased and a recording layer in which information recorded by light can be erased and re-recorded. optical disc.