JPH02246031A - Optical disk - Google Patents

Abstract

PURPOSE:To obtain the optical disk having read-only parts and writable parts within the same disk surface by forming a recording medium having magneto- optical recordable regions freshly on an optical disk substrate on which read- only information is recorded. CONSTITUTION:The plastic substrate 1 on which the reproduction only information is recorded as ruggedness of the substrate is used as the substrate and a thin recording film 3 which has the recordable parts, allows magneto-optical recording and consists of TbFeCo is held in place between Si3N4 films 2, 4 to serve as protective films and is formed thereon. Servo is applied in grooves to read a change in reflectivity as a signal in the case of reproducing the reproduction-only parts. On the other hand, the servo is applied between the grooves and management information is read by using a circuit for magneto- optical reproduction to execute recording and reproduction in the case of making recording in the recordable parts. The optical disk wide in both of the recordable region where the free recording of the information can be made by a user and the reproduction-only region which is a ROM region is thus obtd.

Description

[Detailed Description of the Invention] [Summary] Related to optical discs, especially optical discs that have a read-only area and a writable area on the same disc surface, there is a recordable area where the user can freely record information, and an RO.
The purpose of the present invention is to provide an optical disc having a wide read-only area in the M ml range, and an optical disc substrate having an area in which read-only information is recorded as unevenness on the substrate, and an optical disc formed on the optical disc substrate to record the read-only information. The recording thin film is configured to include a recording thin film in which management information of a recordable area is recorded magneto-optically using a tracking guide portion as a guide, and recordable information is also recorded magneto-optically.

(Industrial Application Field) The present invention relates to an optical disc, and particularly to an optical disc having a read-only portion and a writable portion within the same disc surface.

Optical discs have high recording density and are highly anticipated as large-capacity files. Is this optical disc a CD-RO? j
It has been put into practical use as a read-only memory. In this case, only general data is initially set as files on the optical disc, and personal data is stored separately from general data.

Therefore, there is a need for a disc that simultaneously has a read-only portion and a recordable portion in a single disc.

[Conventional technology]

Conventionally, read-only optical discs are produced by irradiating a photoresist with a laser to expose information, developing it, forming an electrode on it, electroforming (plating) it, and peeling off the plated part (stamper) to form a stamper. do.

By using the stamper produced as described above and transferring the information to the substrate by an injection method or a photopolymer method, various types of recorded information are formed as recesses on the substrate.

In addition to the information formed as irregularities on the substrate by the stamper, in order to provide a portion for recording information, a groove is required to be followed by a laser beam for recording and reproduction.
In addition, a portion in which management information such as track position is recorded is required. In this part, information is recorded in the groove part where no management information is recorded.

[Problems to be Solved by the Invention] As explained above, conventionally, a read-only (playback-only) area is mainly formed on a single disc, and furthermore, the playback-only area and the recordable area are located in different areas. Therefore, if the area of the main reproduction-only part becomes wider, the area of the recordable part naturally becomes smaller.

An object of the present invention is to provide an optical disc that has a wide recordable area where a user can freely record information and a read-only area that is a ROM Si area.

[Means to solve the problem]

According to the present invention, the above problem is solved by an optical disc substrate having an area where read-only information is recorded as irregularities on the substrate, and management of the recordable area formed on the optical disc substrate and using a tracking guide section of the read-only information as a guide. The problem is solved by an optical disk characterized in that it has a recording thin film on which information is recorded magneto-optically and in which recordable information is also recorded magneto-optically.

[For production]

That is, according to the present invention, a recording medium having a new magneto-optical recordable area is formed on a conventional optical disk substrate on which read-only information is recorded.
An optical disc having a writable portion within the same disc surface can be provided.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view showing one embodiment of the optical disc of the present invention.

As shown in FIG. 1, a plastic substrate 1 is used as the substrate, on which reproduction-only information is recorded as unevenness on the substrate, and a magneto-optical recordable TbF film having a recordable portion is used as the substrate.
A recording thin film 3 made of eCo is sandwiched between Si, N, and films 2 and 4, which serve as protective films. 5 is an adhesive.

The manufacturing process involves vacuum packaging the plastic substrate 1 on which the above-mentioned reproduction-only information is recorded! (Pressure below 5Xl0-'Pa)
Ar and Nz
The Si3N film 2 was formed to a thickness of 80 nm by sputtering with 1 ol of gas mixed in a vacuum of 0.5 Pa, and then TbFeC.

0.5 in an Ar gas atmosphere using an alloy target of
A TbFeCo film 3 was formed to a thickness of 1100 nm at a vacuum degree of Pa. Next, Si3N was further deposited on this TbFeCo film 3.
4 Film 4 was formed to a thickness of 80 nm. Using a magneto-optical disk recording and reproducing device on the obtained disk, a tracking guide section of the reproduction-only information recording section (in the case of Fig. 2, the opening pit 7
) was used as a guide to record groove position information 6 as shown in FIG. 7 is a recessed part for reproduction-only data or management information.When recording the position information of the groove, a space of 512 bytes is provided behind it along with a synchronization signal for clocking the signal for the track number and sector number. , recorded. As shown in FIG. 2, the arrangement of the grooves (groups) is, for example, groove depth 0.07. +111, groove width 0.
6- and the distance between each groove row was set to 1.6-.

In order to use the optical disc according to the present invention having a read-only portion and a recordable portion, a device is required that can apply servo both inside the grooves and between the grooves. When reproducing the reproduction-only portion, a servo is applied inside the groove, and changes in reflectance are read as a signal. On the other hand, when recording and recording in the recordable area, apply a servo between the grooves.
By using a magneto-optical reproducing circuit, recording and reproducing can be performed by reading management information.

FIG. 3 is a schematic diagram showing an example of an optical head for a magneto-optical disk for reading information recorded on an optical disk.

The optical head shown in FIG. 3 includes a semiconductor laser 10, a collimating lens 11, a beam splitter 12, and an objective lens 1.
It is composed of a 3.1/2 wavelength plate 14, a polarizing beam splitter 15, a condensing lens 16, a first detector (photodetector) 17, and a second detector 18. The servo circuit is omitted to simplify the diagram. The magneto-optical disk device performs reproduction based on the difference in the deflection angle (Kerr rotation angle) of the reflected light from the disk 20.

Normally, the reflected light is incident on the polarized beam splitter 15 at an angle of 451 using the 172 wavelength plate 14 shown in FIG. 3, but as shown in FIG.
When the shifted light "O" and the second detector IIIN are shifted by θ, the output of the detector changes as shown in Table 1 below.

If we take the sum and difference of each detector from Table 1, we get Table 2.

Table 2 Accordingly, the amplitude of the reflected light output is the sum case 2 fτE @ cosθ difference case 2
f d E, sin θ.

Since 0≦1@, cosθ is clear! , and in the case of the sum, the term θ related to magnetism disappears.

- There remains a term E corresponding to the change in reflectance toward the tip magnetic signal, but it is reproducible because the amplitude is only modulated by the change in reflectance. Particularly in the case of the present invention, the bits that contribute to the change in reflectance are at the ends of the laser beam, and the beam center (portion A) is flat, so the contribution to E is small and there is no problem.

〔Effect of the invention〕

As explained above, according to the present invention, the management information of the recordable area is made of magneto-optical signals, so when reading the read-only area, the magneto-optical signals are not visible (the magneto-optical signals have the same intensity). There is no interference between the recordable area and the read-only area (because the polarization planes are different). Similarly, when reading the recordable portion, the optical system for detecting the magneto-optical signal is configured to cancel changes in light intensity, so no interference occurs. As described above, according to the present invention, recording can be performed both inside the grooves and between the grooves without increasing the interval between the grooves formed in advance.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the optical disc of the present invention, FIG. 2 is a perspective view showing one embodiment of the groove shape of the present invention, and FIG. 3 is a cross-sectional view showing one embodiment of the optical disc of the present invention. FIG. 4 is a schematic diagram showing an example of an optical head for a magneto-optical disk for reading, and FIG. 4 is a diagram showing output changes when the reflection angle for two disks is deviated from normal by θ. 1...Plastic substrate, 2...Si3N, film,
3... Recording thin film, 4...5iJ4 film 6.
... Information recorded magnetically 7 ... Information transferred by stamper 10 ... Semiconductor laser, 11 ... Collimator lens, 12 ... Beam blur, ivy, 13 ... Objective lens, 14 ...1/2 wavelength plate, 15... Polarizing beam splitter, 16... Condensing lens, 17... First detector, 18... Second detector.

Claims (1)

[Claims] 1. An optical disc substrate having an area where read-only information is recorded as unevenness on the substrate, and management of the area formed on the optical disc substrate and recordable using a tracking guide section of the read-only information as a guide. An optical disc characterized by having a recording thin film on which information is recorded magneto-optically and recordable information is also recorded magneto-optically.