JPS6120241A - Disk-shaped optical recording medium - Google Patents

Abstract

PURPOSE:To provide the sure information of a user region by protecting the address region of the user region against the irradiation of a laser beam by a protecting means. CONSTITUTION:The laser beam 13 emitted from a laser generator 12 arrives at a medium 1 by passing through an optical modulator 14, a beam splitter 15, a projecting lens 16, a tracking mirror 17 and an objective lens 18. The illumination of the beam 13 is high in the stage of recording and is low in the stage of reading. The beam 13 reflected from the medium 1 in either case is split by the beam splitter 15 and is passed through a photodetector 20, an amplifier 21 and a demodulating circuit 22, by which the reading out data is obtd. Whether the high-frequency component generated by pits 10 is included in the data or not is detected by a high-frequency detecting circuit 23. The output from the generator 12 is decreased by a laser change-over circuit 24 if it is assumed here that the high-frequency component is detected during writing. The irradiation of the beam 13 having the strong illumination to the tracks 3 of the fixed program region 4 and the address region 8 is thus obviated and said regions are safely protected.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a disk-shaped optical recording medium on which optical information is recorded by an optical recording device.

Technical Background and Problems In general, this type of recording medium is a disk made of glass or plastic coated with a metal film such as tellurium or bismuth that deforms into a bit shape when irradiated with a laser beam. has been made into Tracks formed on the surface of the medium include concentric tracks and spiral tracks, and either type is selected and used depending on the information content. For example, with code information, even a single bit error in reading or writing can result in completely different information.
It is necessary to trace the same track repeatedly. Therefore, it is desirable to use concentric tracks for code information.

On the other hand, even in a medium in which concentric tracks are formed, there is fixed program information, and this information must not be destroyed by a laser beam. This is recorded in a fixed program area. Furthermore, even in the user area where writing and reading are repeated, each track has a track address, and each sector has a sector address. Nowadays, a disc-shaped disk with a diameter of 12 cs has 500 to 600 MB of recorded information, and a disk with a diameter of 30 cm has an enormous amount of information, more than IGB.

What information is recorded in which area is managed by track addresses and sector addresses. Therefore, if the address information is destroyed, it becomes impossible to read the information, and it is the same as if all the information in that track or sector was destroyed.

OBJECTS OF THE INVENTION The present invention aims to provide a disc-shaped optical recording medium that can ensure information in a user area.

SUMMARY OF THE INVENTION The present invention protects the address area of the user area from laser beam irradiation by a protection means.
The structure is such that the address information is not destroyed even if it is repeatedly written, thereby increasing the reliability of the data.

Embodiment of the Invention First, a disk-shaped medium 1 is provided, and the surface of this medium 1 is used as a recording surface 2. On this recording surface 2, a large number of concentric tracks 3 are formed. The center side of the medium 1 is a fixed program area 4 in which fixed information is recorded, and the outer circumferential side is a user area 5.

The recording surface 2 also has a track address 6 in the radial direction.
and a sector address 7 are formed to provide an address area 8.

Therefore, pits 10 are formed on the side of the track 3 in the fixed program area 4 and on the side of the track 3 in the address area 8 as protection means, and the pitch is much finer than that of the data bits 9. .

Next, the optical recording device 11 will be explained based on FIG. First, a laser generator 12 is provided, and a laser beam 13 emitted from the laser generator 12 is transmitted to the optical modulator 1.
4. The medium 1 is irradiated through the beam splitter 15, the projection lens 16, the tracking mirror 17, and the objective lens 18. The optical modulator 14 also includes a modulator drive circuit 19.
is connected. This modulator drive circuit 19 is given write data. Next, a light receiver 20 is provided which receives the beam from the beam splitter 15, and an amplifier 21 is connected to the light receiver 20. A demodulation circuit 22 and a high frequency detection circuit 23 are connected to the amplifier 21. The read data is sent from the demodulation circuit 22 to a processing circuit (not shown). Further, the high frequency detection circuit 2
3 is connected to a laser switching circuit 24, and this laser switching circuit 24 is connected to the laser generator 12.

In such a configuration, the laser beam 13 emitted from the laser generator 12 is transmitted through an optical modulator 14, a beam splitter 15, a projection lens 16, a tracking mirror 17,
It reaches the medium 1 through the objective lens 18. The illuminance of the laser beam 13 is high during recording, and the illuminance is low during reading.

In either case, the laser beam 13 reflected from the medium 1 is split by the beam splitter 15, passes through the photoreceiver 20, the amplifier 21, and the demodulation circuit 22, and is converted into read data, which is generated by pits 10 in the data. High frequency detection circuit 2 detects whether high frequency components are included.
Detected by 3. If a high frequency component is detected during writing, the output of the laser generator 12 is reduced by the laser switching circuit 24. As a result, the track 3 between the fixed program area 4 and the address area 8 is not irradiated with the laser beam 13 of high intensity, and is safely protected.

Incidentally, in practice, instead of the pit 10 shown in FIG. 2, a wavy track 25 may be used as a protection means as shown in FIG. 4.

Further, as a protective means, a film made of aluminum or the like may be coated. Further, the material of the portion to be protected may be changed.

Effects of the Invention The present invention provides a method to protect recorded contents from being destroyed even if the address area of the user area is irradiated with a laser beam in a disc-shaped medium in which concentric tracks are formed on the same surface as described above. By taking measures, it is possible to reliably protect the recorded contents, and in particular, it is possible to effectively protect the address area of the user area, which is irradiated with a strong laser beam for writing, to ensure the integrity of the data. This can improve reliability.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a plan view of a medium, FIG. 2 is an enlarged plan view of a part of the track, FIG. 3 is a circuit diagram of an optical recording device, and FIG. The figure is a partially enlarged plan view of a truck showing another example of the protection means. 1... Medium, 2... Recording surface, 3... Track, 4
・・Fixed program area, 5・User area, 8・
... Address area, 10 ... Pit (protection means), 1
3... Laser beam, 25... Wavy track (protective means) Applicant Tokyo Electric Co., Ltd. J, Z diagram

Claims (1)

[Claims] In a disk-shaped medium having a large number of concentric tracks formed on the same surface, a fixed program area and a user area are formed on the recording surface of the medium divided into an inner circumferential side and an outer circumferential side, and the user area 1. A disk-shaped optical recording medium characterized in that a protective means is applied to prevent recorded contents from being destroyed even if an address area therein is irradiated with a laser beam.