JPH04103047A - Optical disk - Google Patents

Abstract

PURPOSE:To allow the recording of fixed information by subjecting a DRAW type medium layer to irreversible changes by the light beam output sufficiently larger than at the time of ordinary recording and erasing operations. CONSTITUTION:The DRAW type medium layer 65 is locally heated and melted by a laser beam 22 of sufficient intensity to form bits 66 in exactly the same manner as recording on ordinary DRAW type medium media to execute recording on the DRAW type medium layer 65. Further, the laser beam 22 for reproducing is reflected by the DRAW type medium layer 65 in the same manner as with an ordinary magneto-optical recording medium 52a if the DRAW type medium layer 65 is not recorded at all. The laser beam 22 passes the bits 66 if the recording is made as the bits 66 and, therefore, the reflected light 2 is eventually largely changed in intensity according to the presence or absence of the bits 66. A user is able to record fixed data afterward on the medium which allows repetitive erasing and recording.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc related to recording and reproducing information using a light beam, and particularly relates to an optical disc in which a rewritable medium and a recordable medium are integrated.

[Conventional technology]

Optical disks can record information by forming minute bits as irregularities on a substrate, and because they are suitable for mass production, video disks, CDs, D-ROMs, etc. first became popular as data storage media. In the future, field-recordable optical discs will become popular, and a format in which data or programs are pre-recorded on a part of the recordable optical disc as irregularities on the board, and then the user records data in the field in the margins. optical discs are also expected to become popular.

[Problem to be solved by the invention]

In conventional optical discs, recording fixed information as irregularities on a substrate requires considerable cost and time to create a mold, and the problem is that the production of a large number of identical discs is almost limited. In addition, from the viewpoint of data protection, individual users also desire to have data parts on the disk that will not be destroyed under normal usage conditions. Thus, there is a need for an optical disc that allows a user to easily create fixed data information on a rewritable medium.

The present invention attempts to solve the above-mentioned problems by providing a medium that is rewritable but allows recording similar to that of a write-once medium by increasing the output of a recording light beam. be.

[Means to solve the problem]

The optical disc of the present invention is an optical disc including a reflective layer constituting a rewritable optical storage medium, wherein the reflective layer is a write-once medium layer having lower storage sensitivity than the rewritable optical storage medium, By using a light beam output that is sufficiently larger than that during the recording/erasing operation, irreversible changes are caused in the write-once medium layer to perform recording, thereby making it possible to record fixed information.

〔Example〕

Next, the present invention will be explained using a magneto-optical disk as an example with reference to the drawings.

FIG. 5 is a diagram explaining the concept of an optical disk system, and particularly shows the case where a magneto-optical disk is used. In the figure, number 11 is an optical disk, and number 12 is an optical disk 11.
The track above is shown. The track 12 may have a spiral or concentric circular shape, but the concentric circular shape is shown in the figure. Numbers 21 to 33 are used to explain the structure and operation of the optical head. 0 Number 21 indicates a semiconductor laser, and the laser beam 22 emitted from the semiconductor laser 21 is converted into parallel light by a condensing lens 23. half mirror 2
4. A minute spot 26 with a diameter of about 1 micron is formed on the optical disk 11 through the objective lens 25. The reflected light 27 from the optical disc 11 is reflected by the objective lens 25. It passes through the half mirror 24 and enters the analyzer 28. The light emitted from the analyzer 28 enters photodetectors 29 and 30, and their respective difference signals 32
and a sum signal 33 is obtained. Reference numeral 34 indicates an optical disk device control section that controls the operation of the optical head and various parts of the optical disk device, and is connected to the host computer 40 by a signal line 41. In the figure, circuit systems related to focus error detection or tracking error detection are well known and are omitted because they are not directly relevant to understanding the present invention. Numeral 31 is a bias coil for applying a bias magnetic field to the optical disk 11 during recording or erasing.

FIG. 3 is a sectional view showing a track portion of a magneto-optical disk. In FIG. 1, number 51 is a transparent substrate with approximately 1.2
Made of polycarbonate resin with a thickness of mm, number 52
is a magneto-optical medium provided on the substrate 51, and numeral 53 is an adhesive layer. Further, number 54 indicates an area where data is recorded in advance, that is, a pre-recording section, and number 55 indicates a section where the user records data. Data is recorded in advance in a concave and convex manner with the depth of the disk, and normally a track address, sector address, etc. are provided at the beginning of the sector. Even when data and programs are provided in advance, they are similarly recorded as irregularities on the substrate.6 Next, the operation of the optical disk device will be explained using FIGS. 3 and 5. Recording in the area numbered 55 on the optical disc 11 is modulated by the optical disc control unit 34 according to data sent from the host computer 40 via the signal line 41, and the semiconductor laser 21 generates a laser beam 22 of high and low strength, and at the same time A DC current is supplied to the bias coil 31 and a magnetic field is applied in a direction perpendicular to the optical disk 11.The spot 26 produces an output of about 2 milliwatts or 10 milliwatts on the optical recording medium 5 using a laser beam 22 of high or low strength.
2, when a large output is applied, the temperature of the optical recording medium 52 rises within the size range of the small spot 26, and the spot 26 moves to another area due to the rotation of the optical disc 11, or the output becomes small. , after the part has cooled down,
Magnetization in the same direction as the magnetic field applied by the bias coil 31 remains on the optical recording medium 52 to perform recording.

Next, to reproduce data from the optical disc 11, the output of the semiconductor laser 21 is controlled by the optical disc device control unit 34, and a spot 26 with an optical output of approximately 2 milliwatts is scanned along the track 12 of the optical disc 11. Let's do it. When the spot 26 scans the preformat portion 54 of the track 12 on the optical disk 11, the unevenness of the substrate 51 is converted into the intensity of the reflected light 27, which is detected as the amplitude of the sum signal 33. When the spot 26 scans over the area 55, the recording is made as a change in the magnetization of the optical recording medium 52, so the plane of polarization of the reflected light 27 is changed by the well-known Kerr or Faraday effect, and the analyzer 2
8, the reflected light 27 is divided into components having orthogonal polarization planes and inputted into photodetectors 29 and 30, where changes in magnetization are converted as the strength and weakness of a difference signal 32, and recorded data is reproduced.

FIG. 4 is a sectional view illustrating FIG. 3 in more detail. In FIG. 4, the magneto-optical medium 52 can be constructed in a variety of ways; for example, approximately
00 angstrom silicon nitride (SiN), number 62
A media layer of approximately 300 angstroms of terbium iron cobalt titanium (TbFeCoTi), numbered 63.
About 300 angstroms of silicon nitride (Si
Each layer is sequentially formed by sputtering, such as a reflective layer of approximately 500 angstroms of aluminum (AJ) shown at 64 and 64. Recording is performed on the medium layer 62, but other layers play roles such as protecting the medium layer 62 and improving recording/reproducing sensitivity.

In the embodiment of the present invention, the reflective layer 64 constituting the magneto-optical medium 52 is of a write-once type made of a tellurium (Te) base metal (for example, a Te5ePb alloy with a thickness of about 300 angstroms formed by vapor deposition, sputtering, etc.). Depending on the laser beam 22 applied to the medium when recording on the medium layer 62, the recording sensitivity of the write-once medium layer is set so low that recording is not performed on the write-once medium layer. shall be kept.

FIG. 1 is a sectional view illustrating a first embodiment of an optical disk according to the present invention, in which a magneto-optical medium 52a in which the reflective layer 64 in FIG. 4 is replaced with a write-once medium layer 65,
Mode of recording performed on the write-once medium layer 65 and laser light 2
2 and reflected light 27 are schematically shown. Write-once medium layer 65
For recording, the write-once medium layer 65 is locally heated and melted using a laser beam 22 of sufficient intensity to form bits 66, just like recording on a normal write-once medium. In this case, the laser beam for recording may be applied from above in FIG. 1, that is, in the same way as the laser beam 22 shown, or conversely, it may be applied from below. From the viewpoint of recording sensitivity, since there is reflection from the medium layer 62 when the recording laser beam is applied from above as shown in FIG. 1, it is more advantageous to apply the recording laser beam from below. Data reproduction on the write-once medium layer 65 is performed by the same principle operation as in write-once recording. That is, when no recording is made on the write-once medium layer 65, the laser beam 22 for reproduction is applied to the write-once medium layer 65 in the same way as in a normal magneto-optical recording medium (as shown in FIG. 4).
If the laser beam 22 is reflected by the bit 66 and recorded as the bit 66, the laser beam 22 will pass through the bit 66, so the intensity of the reflected light 27 will vary greatly depending on the presence or absence of the bit 66. , the aforementioned preformat section 54
The data on the write-once medium layer 65 is reproduced using the same principle of operation as in the reproduction.

In the first embodiment of the present invention, the structure of the magneto-optical medium 52a is as shown in FIG. It will become a thing. That is, as shown in FIG. 1, if the write-once medium layer 65 forms bits for recording, spacers are provided on the inner and outer peripheries of the optical disc, which correspond to the adhesive layer 53 in FIG. The structure is configured so that a portion becomes an air layer. In addition, in the case of the write-once medium layer 65 that performs recording by causing a phase change without forming bits, it is not necessary to have an air layer on one side, so a structure without an air layer as shown in FIG. 3 is used. I can do it. Furthermore, in the case of a double-sided medium as shown in FIG. 3, the laser beam 22 is incident from above to record on the write-once medium layer 65 as shown in FIG.

FIG. 2 is a cross-sectional view showing a second embodiment of the present invention.6 In the second embodiment of the present invention, recording is performed by directly irradiating the write-once medium layer 65 with a laser beam from below in FIG. An optical disk 70 can be formed by using a transparent flat substrate with an air layer 71 interposed therebetween.

In explaining the present invention, the principle operation has been explained using a magneto-optical disk as an example. However, without departing from the spirit of the present invention, for example, it is possible to change the configuration of the medium layer or to substitute a magneto-optical disk. It goes without saying that various changes and modifications can be made, such as using optical disks with other phase changes, and the above description does not limit the scope of the present invention. [Effects of the Invention] As explained above, this invention The invention has a multi-layered structure of a medium that can be repeatedly recorded and erased and a write-once medium whose recording principle is irreversible physical and chemical change, and the recording sensitivity of the write-once medium is set lower than that of the medium that can be repeatedly recorded and erased. Optical technology that allows users to later record permanent data on repeatably erasable recordable media.
We can provide discs.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view showing a second embodiment of the invention, FIG. 3 is a sectional view showing a track portion of a magneto-optical disk, and FIG. FIG. 4 is a sectional view explaining FIG. 3 in detail, and FIG. 5 is a diagram explaining the concept of the optical disk system. 11.70...Optical disc, 12...Track, 2
1... Semiconductor laser, 22... Laser light, 23
...Condensing lens, 24...Half mirror-125...
・Objective lens, 26... Spot, 27... Reflected light, 28... Analyzer, 29.30... Photodetector, 31
...Bias coil, 32...Difference signal, 33...
Sum signal, 34... Optical disk device control unit: 40...
Host computer, 41... Signal line, 51... Substrate, 52... Media layer, 52a... Magneto-optical medium, 53
. . . Adhesive layer, 54 . . . Area where data is recorded in advance, 55 . . . Area where the user records data, 61.
63...SiN film layer, 62-...TbFeCoTi film layer, 64-A, R film reflective layer, 65...Writable medium layer, 66...Pit, 71...Air layer, 72...・
protective cover

Claims (1)

[Claims] 1. An optical disc including a reflective layer constituting a rewritable optical storage medium, wherein the reflective layer is a write-once medium layer having lower storage sensitivity than the rewritable optical storage medium.