JPS615488A - Optical disk - Google Patents

Abstract

PURPOSE:To identify optical without providing a special sensor by supplying an information signal for identifying disks in a projected and recessed shape beforehand at part of a track formed in a spiral-like or concentric circles shape. CONSTITUTION:Areas RA and RB denote a track of an addition writing-type optical disk or erase-type optical disk and that of a reproduction only optical disk, respectively, while areas thetaA and thetaB show a data field and a format area of a disk identifying signal part, etc., respectively. A track 13 of the area RA radiates light beams 17 narrowed extremely slightly in a continuous spiral-like shape by means of a groove 14 having a width W, depth (d) and track pitch P and an irregular bit string 15 to the groove 14, records and reproduces data. A necessary length of signals for formating a disk identifying signal part, etc., beforehand on the optical disk is given as the bit string 15 with the irregular structure which can be optically detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc used in an optical disc device that reproduces, records, or reproduces information signals such as digital data by narrowing down a laser beam.

Conventional configuration and its problems Optical disks can record and reproduce information signals by narrowing the laser beam to a minute optical spot with a diameter of about 1 μm, so the recording density is high and the memory cost per bit is low.
It is attracting attention as a high-density, large-capacity digital memory because of its high-speed access and non-contact recording and playback capabilities.

Optical disks used as memory can be roughly divided into three new categories.

One of them is Digital Audio Disc (DAD).
This is a read-only optical disc in which information signals are provided in advance as pit train tracks on the optical disc. 2
The first is a write-once optical disc, which allows one-time recording by punching holes in the recording layer using the thermal energy of a laser beam or by locally changing the optical density of the recording layer. It is suitable for use as an optical disc for long-term storage that can be recorded and played back by the user.

The other type is a rewritable or erasable optical disc.
There are devices that reversibly change the optical density of the recording layer using the thermal energy of a laser, and optical disk and screen devices provide an erasing light beam separate from the recording and reproducing light beam to obtain data under suitable erasing conditions. There are some suggestions.

In practice, it can be said that it is extremely difficult to use the three types of optical discs described above in a single optical disc device without changing the device conditions in any way. For example, if a write-once optical disc is irradiated with an erasing light beam with erasing power, erroneous recording may occur, or in order to obtain a high-quality reproduction signal, the power of the light beam irradiated onto the optical disc must be It is necessary to vary the control gains for focusing, tracking, etc., because the recording light beam power and the reflectance of the optical disc differ depending on the type of optical disc.

Therefore, it is possible for the user to set the optical disc device each time depending on the optical disc being used, such as prohibiting irradiation of the erasing light beam onto a write-once disc, controlling the laser light such as the irradiation light power, and switching the control gain. However, it is very inconvenient to use.

As a way to solve this problem, the optical disc is stored in a cartridge, and a hole is provided for identifying the optical disc, which differs depending on the type of optical disc stored in the cartridge.
This hole is detected by a sensor installed in the optical disc device.1. The optical disk device identifies what type of optical disk is installed, and based on this identification result, automatically controls the laser beam or changes the control gain as described above to create a state suitable for the installed optical disk. A method is proposed.

However, with this method, it is necessary to change the shape of the cartridge depending on the type of optical disc to be stored, and it is also necessary to provide the optical disc device with a special sensor for disc identification.

OBJECTS OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide an optical disc that can quickly identify an optical disc without providing a special sensor in an optical disc device.

, Structure of the Invention The present invention is an optical disk having a structure in which a track is formed in a spiral shape or a concentric shape, and a part of the track is provided with an information signal for disk identification in the form of a concave and convex shape. □ Description of Embodiment FIG. 1 is an external view showing an outline of the disc format of an optical disc in an embodiment of the present invention. Tracks on an optical disk are formed spirally or concentrically, but in the following description, it will be assumed that they are formed spirally.

In the figure, reference numeral 1 denotes an optical disk, which has a center hole 2 in its center for rotating and driving the optical disk (in this embodiment, driving it at a constant rotation speed in the direction of arrow R).

3 is an index field. Index field 3 is index mark (ID M') 4
and a jumping region (TG) 5.

6 is the sector, and one trunk has up to SO-S n.
It has (n+1) equally spaced sectors 6.

Each sector 6 has a sector header area 7 at the beginning,
Data field (Do~D n
) has 8.

The sector header area 7 is a disk identification signal section (DS゛)
9, Sector mark (SM) 1o, Address field (
AO-An) 11.

The index mark 4 of the index field 3 is used as a track jumping start signal for retracing the spiral track by one track every revolution of the optical disk and always retracing the same track. By driving the aperture lens of the optical head in the direction perpendicular to the track by an amount equivalent to a track retrieval using an index signal detected from a reproduction signal reproduced by an optical head provided in an optical disk device (not shown), the track within the jumping area 6 is Jump back to the original track. The address field 11 and AO following the jumping area 6 are read to confirm whether the track jumping has been performed correctly.

The disc identification signal section 9 has different pre-provided signals corresponding to read-only, write-once, or erasable optical discs, as will be described later. Identification of which type of optical disc is loaded is made by reproducing the disc identification signal portion 9 with an optical head and detecting the reproduced signal. The optical disc device detects the playback signal of the disc identification signal section 9, identifies the loaded optical disc from the detection signal, and, for example, prohibits irradiation of the erasing light beam if it is identified as a write-once optical disc. Appropriate measures and controls are performed for recording and reproducing the write-once optical disc.

Address field 11 includes a preamble for clock synchronization for clock reproduction, an address mark for detecting the start of an address, a track address assigned to each track, and a sector address assigned to each sector. etc., and the sector mark 10 is used to provide a good and high detection ability for sector addresses, but the details thereof will be omitted.

Next, the disk structure will be explained according to FIG. FIG. 2 is a conceptual perspective view partially showing the radial direction of the optical disc in cross section.

The read-only optical disc has a grooved track that has data in the data field described above in advance.

In the figure, tracks of an RA area write-once type or erasable type optical disc are shown, and tracks of an RB area read-only type optical disc are shown. Also, θA area data field 8
.theta.B area indicates a previously formatted area such as the disk identification signal part 9 and the index mark 4.

In the figure, the base material 12 is made of a transparent or semi-transparent material. The RA area track 13 has a width W, a depth d, a groove 14 having a track width P, and a row of pits 15 having a concave and convex shape, forming seven continuous spiral tracks 13. A recording film 16 having a thickness of t is formed on the track 13 by a method such as vapor deposition, and a protective layer 16 is provided thereon. The depth d1 and the width W of the groove 14 are designed to function as an optically detectable trunk.

Data recording, reproduction, etc. are performed by projecting a finely focused light beam 17 onto the groove 14 portion. 18 indicates a focus point where an optical density change has occurred.

A signal for formatting the optical disc in advance, such as the disc identification signal section 9, is provided with a length necessary as a focus row 15 of an optically detectable uneven structure.

Area B indicates the track of the read-only optical disc, and θA
In the data field 9, the data to be reproduced may be provided in advance as a bit string having an optically detectable concave-convex structure as shown in the track 13', or as shown in the track 13''. Groove 1 similar to groove 14 in area A
The data to be reproduced may be further provided as a focus row with a concave-convex structure on the optical disc 4'.The vapor deposited film of the read-only optical disc may be the same as the recording thin film 17 described above.
In order to improve the reproduction signal quality, it is preferable to deposit a thin film of Al.

In the above description, a disc identification signal is provided in the sector header area of each sector, but this has the effect of increasing reliability because disc identification can be performed for each sector, the smallest unit in which data is recorded and reproduced. However, there is one location per track, for example, sector S.

It goes without saying that the gist of the present invention will not be deviated from the spirit of the present invention if the index mark is provided only on the index mark or next to the index mark.

Effects of the Invention The optical disc of the present invention has a track formed in a spiral or concentric pattern, and has a structure in which an information signal for disc identification is provided in advance as a concave-convex pit in a part of the trunk. Since the above signal is reproduced by the head and the disc identification can be detected from the reproduced signal, a special detection sensor for disc identification is not required.

Its practical value is great, as read-only, write-once, and erasable optical discs with different conditions such as length, disc irradiation light power, etc. can be used with one optical disc device without any adjustment by the user.

[Brief explanation of drawings]

FIG. 1 is an external view showing an optical disc according to an embodiment of the present invention;
FIG. 2 is a perspective view with a partial cross section showing the structure of the optical disc shown in FIG. 1. 01... Optical disc, 6... Sector, 8... Disc identification signal section, 13.13', 13"...track. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
figure,? 3) Figure 2 EB R4

Claims (3)

[Claims] (1) An optical disc having a spiral or concentric track, and having a disc identification signal provided in advance in the form of optically detectable irregularities on a part of the track. (2) The optical disc according to claim 1, wherein a disc identification signal is provided at at least one location per track of one revolution of the optical disc. (3) The optical disc according to claim 1, wherein a sector is provided in the track in the rotational direction of the optical disc and includes a sector header area and a data field, and a disc identification signal is provided in the sector header area. .