JP3169845B2 - Optical recording medium and optical head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium in which once recorded information is to be re-recorded, information already recorded is not overwritten or erased, and an optical head used for the optical recording medium.

[0002]

2. Description of the Related Art Conventional magneto-optical disks and phase-change optical disks are capable of overwriting even if they are recorded.
It was necessary to perform a recording inhibit (write inhibit) operation on the device side.

Conventionally, in order to protect recorded information, a magneto-optical recording medium in which information that a user intends to save permanently can be added to a part of a user area, as in Japanese Utility Model Laid-Open No. 5-50531, for example. Or there was a phase change recording medium. In this method, information to be stored permanently is recorded not in the entire surface of the optical disc but in a limited area (recording area), and another area (rewriting area) is used for normal recording / reproduction without using this recording area. It was responded by that. FIG. 5 shows the configuration of this optical disk. A write-once area 503 and a rewrite area 504 are provided in a user area 502 of an optical disk 501, and a guard area 505 is provided between these two recording areas.

Further, as disclosed in Japanese Patent Application Laid-Open No. 2-73549, a track is provided that cannot be rewritten to either land / groove, and recording / reproducing is performed only on the other track of land / groove.

[0005] As shown in these inventions and inventions, there is a need for an optical recording medium configured so as not to overwrite already recorded tracks. For example, when dealing with a phenomenon that cannot be reproduced again, such as one scene of a movie, it is necessary to strictly protect the video from being overwritten.

[0006]

However, the above-mentioned conventional optical disk has the following problems. With the conventional recording inhibit function, it is not always possible to reliably prevent overwriting due to device compatibility problems or system control malfunctions.

In particular, in the case of an electronic device, most of the devices are computer-controlled, and there is a risk that precious video information or control software or the like may be erased due to overwriting due to a malfunction.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical recording medium that can be protected on the medium side without damaging already recorded information even if a malfunction of an electronic device or the like occurs, and an optical recording medium used for the optical recording medium. Is to provide a head.

[0009]

Means for Solving the Problems The present inventor has made various studies in order to achieve the above object, and as a result, completed the present invention.

The present invention relates to an optical recording medium after recording information.
As can be prevented body overwriting, the overwriting preventing film laser wavelength different laser radiation in the transmittance of the recording information is reduced irreversibly incident light beam
The present invention relates to an optical recording medium provided on a recording film on an emission side .

The present invention also relates to the above-mentioned overwrite prevention film.
The present invention relates to the above optical recording medium in which a film having photochromic properties is provided on a thermal recording type recording film.

The present invention also relates to the above-mentioned overwrite prevention film.
The present invention also relates to the above-mentioned optical recording medium in which a thermal recording type film is provided on a recording film having photochromic characteristics.

Further, the present invention is an optical head capable of making the above-mentioned optical recording medium overwritable simultaneously with recording of information, and has a configuration capable of emitting two light beams having different wavelengths, and irradiates the optical beam first. We record information with light beam,
Wavelength different from the laser wavelength for recording information to be irradiated later
In the light beam, the overwrite prevention film so that it is possible to reduce the transmittance of the recording film of a track in which the information is recorded
And an optical head having a configuration capable of reducing the transmittance of the optical head.

[0014]

Embodiments of the present invention will be described below in detail.

FIGS. 1 and 3 show the configuration of the optical recording medium of the present invention, and FIG. 2 shows the configuration of the optical head of the present invention. In the optical recording medium of FIG. 1, a heat mode recording film (thermal recording type recording film) is formed as an information recording film 101, and an optical mode recording which reacts to the wavelength of light instead of the power of light as an overwrite prevention film 102. A film (photochromic film) is formed. These laminated two-layer recording films (101, 10
The upper and lower 2), the protective film (e.g., ZnS-SiO ₂₎ 1
03 and 104 are formed. With such a configuration, the incident beam from the substrate 105 side passes through the protective film 104 and irradiates the two recording films (101, 102), and the light beam transmitted through these films becomes the protective film 103.
Is reflected by the reflective film 106, and again the protective film 103
Is transmitted to the two recording films (101, 102) from the side opposite to the incident beam.

Next, the two recording films (101, 10
The recording process 2) will be described. Overwrite prevention film 1
02, a recording light beam 108 having a wavelength λ1 different from the wavelength λ2 of a light beam (light beam for which overwriting is not possible) 107 for forming a mask by reducing the transmittance of the information beam and passing through the overwrite prevention film 102. A recording mark 109 is formed on 101. Subsequently, a light beam 107 (wavelength λ) for masking the recorded information recording film 101 is used.
In 2), the overwrite prevention film 102 is irradiated to reduce its transmittance. This light beam 107 is shown by a broken line in FIG. FIG. 1 shows a case in which the recording light beam 108 and the overwrite disable light beam 107 are irradiated through separate objective lenses 110 and 111.

At the time of the next reproduction, reproduction is performed by increasing the power of the light beam. However, when the light beam reaches the information recording film 101, overwriting is performed so that the power cannot be recorded. If the transmittance of the write protection film 102 is reduced, the information recording film 101 will not be overwritten.

FIG. 2 shows an example of the optical system of the optical head according to the present invention. This shows a case where the recording light beam (wavelength λ1) and the overwrite-impossible light beam (wavelength λ2) are applied to the respective films of the optical disk through the same objective lens 112.

The light beam from the laser light source 113 for emitting the recording light beam (wavelength λ1) is
At 14, the light becomes parallel light, goes straight through the half mirror 115,
It is raised five times by the mirror 116, goes straight through the dichroic mirror 117, and enters the objective lens 112. A light beam (shown by a broken line) from the laser light source 118 that emits an overwrite-disabled light beam (wavelength λ2) is converted into parallel light by a collimator lens 119, is deflected by 90 degrees by a dichroic mirror 117, and enters the objective lens 112. . At this time, the overwrite disable light beam (wavelength λ2) is adjusted so as to be inclined with respect to the optical axis of the recording light beam (wavelength λ1), and both light beams are focused on the same track. .

FIG. 3 shows the film configuration of FIG. 1 in which the arrangement of the optical mode recording film and the heat mode recording film is changed. That is, from the side where the light beam enters the optical disk, the substrate / protective film / heat mode recording film (overwrite prevention film) / optical mode recording film (information recording film) / protective film /
The reflective films are formed in this order. Germanium-antimony-tellurium (GeSbT)
e), indium / silver / antimony / tellurium (InAg)
When a heat mode recording film made of SbTe) or the like is used, by setting the temperature to a specific temperature such as a melting temperature or more,
The heat mode recording film changes from a crystalline state to an amorphous state, and the transmittance is reduced. As a result, overwriting can be prevented.

The heat mode recording film according to the present invention is, for example, terbium / iron / cobalt (TbFeCo) if it is a magneto-optical recording medium, or germanium / antimony / tellurium (GeSbTe) if it is a phase change recording medium.
Indium, silver, antimony, tellurium (InAgSbT
e) and the like.

The optical mode recording film of the present invention is preferably formed of an organic photochromic material. The photochromic material is described in detail in “The Chemistry of Organic Photochromism” published by The Society of Chemicals Publishing, edited by The Chemical Society of Japan. Examples of the photochromic compound include spiropyrans, spirooxazines, diarylethenes, fulgides, and cyclophanes. Furthermore, the following literature also describes organic photochromism. By using these materials for the overwrite prevention film, the transmittance can be reduced after information is recorded. “Optoelectronics Material Manual” published by Optronics, pp.
70-75, Edited by the New Material Handbook Editing Committee, “New Material Handbook” published by Maruzen Co., Ltd. 712-7
14. Edited by the Optical Electronics Encyclopedia Editing Committee, Inc.
"Encyclopedia of Optoelectronics" published by the Industrial Research Council, pp. 3
19-325.

Japanese Patent Application Laid-Open No. Hei 8-263843 discloses a super-resolution recording film made of an organic film. Among such organic films, a film of diarylethene particularly suitable for high-density recording is disclosed. It is desirable for application to the present invention. Although the above publication describes an optical recording medium for performing high-density recording and an efficient reproducing method / apparatus thereof,
The present invention is intended to prevent the already recorded information from being overwritten even if the optical recording medium on which the information has been once recorded is erroneously overwritten. Configuration is also different.

As the overwrite prevention film in the present invention, for example, a photobleachable dye film using a nitrone-based organic compound or a fluorine ring-based diarylethene material may be formed.

The optical recording medium having the structure shown in FIG. 1 has a transmittance (in a recording wavelength region) of the transmittance before overwriting is not performed as a material of a film having photochromic characteristics. The ratio is 2
It is desirable to use the above materials.

FIG. 4 shows an example of the transmittance characteristics of the overwrite protection film with respect to the wavelength during recording and during reproduction. Solid line 4
01 indicates the transmittance at the time of information recording, and the broken line 402 indicates the transmittance at the time of reproduction after information recording. In the figure, λ1 indicates the wavelength of the recording light beam, and λ2 indicates the wavelength of the overwrite-impossible light beam. The transmittance at the time of recording at the wavelength λ1 is high (solid line 401), and good recording is possible. However, after recording once, the transmittance decreases at both the wavelengths λ1 and λ2 (broken line 402) and the wavelength λ1 In this case, recording on the information recording film is impossible due to insufficient light quantity. In addition, even when the optical beam is irradiated not only with the wavelength λ1 but also with a wavelength region where the transmittance of the wavy line 402 is low, overwriting on the information recording film can be prevented.

[0027]

As is clear from the above description, according to the present invention, even if an overwrite operation occurs erroneously due to a malfunction of the electronic device, etc., the information once recorded is not lost, and the recorded light is not lost. The recording medium can be protected.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of an optical recording medium of the present invention.

FIG. 2 is an explanatory diagram of an optical system of the optical head according to the present invention.

FIG. 3 is an explanatory sectional view of the optical recording medium of the present invention.

FIG. 4 is a graph showing transmittance characteristics with respect to wavelength of an overwrite prevention film of the optical recording medium of the present invention.

FIG. 5 is a plan view of a conventional optical recording medium.

[Explanation of symbols]

 101, 301 Information recording film 102, 302 Overwrite prevention film 103, 104, 303, 304 Protective film 105, 305 Substrate 106, 306 Reflective film 107, 307 Overwrite disabled light beam 108, 308 Recording light beam 109, 309 Recording mark 110, 111, 112, 310, 311 Objective lens 113, 118 Laser light source 114, 119 Collimator lens 115 Half mirror 116 45 degree mirror 117 Dichroic mirror 120 Optical recording medium 501 Optical disk 502 User area 503 Additional recording area 504 Rewriting area 505 Guard region

Claims (6)

(57) [Claims] An overwrite prevention film whose transmittance is irreversibly reduced by laser irradiation of a laser wavelength different from the laser wavelength for recording information so that overwriting of the optical recording medium after recording of information is prevented. At least part of the write-once recording area provided on the recording film on the light beam incident side
Optical recording medium having . 2. The optical recording medium according to claim 1, wherein a film having photochromic properties is provided on the thermal recording type recording film as the overwriting prevention film. 3. The optical recording medium according to claim 1, wherein a thermal recording type film is provided on the recording film having photochromic characteristics as the overwrite prevention film. 4. The optical recording medium according to claim 2, wherein any one of spiropyrans, diarylethenes, fulgides, cyclophanes, and spirooxazines is used as a material for the film having photochromic properties. 5. The optical recording medium according to claim 3, wherein any one of spiropyrans, diarylethenes, fulgides, cyclophanes, and spirooxazines is used as a material for the recording film having photochromic properties. 6. An optical head capable of overwriting the optical recording medium according to claim 1 simultaneously with recording of information, wherein said optical head can emit two light beams having different wavelengths. The information is recorded with a light beam that is irradiated first, and the light beam that is irradiated later and has a wavelength different from the laser wavelength for recording the information is transmitted through the recording film of the track on which the information is recorded. An optical head having a configuration capable of reducing the transmittance of the overwrite prevention film so that the transmittance can be reduced.