OPTICAL DISC AND OPTICAL DISC UNIT

Abstract: An optical disk (1) has sector ID areas (2), a disk ID area (3), a table of content area (4), a ROM area (5) and a RAM area (6). The ROM area stores software programs and basic data and is made non-rewritable by employing a physically permanent recording means, such as embossing ditch patterns, whilst the RAM area is left rewritable. In addition, the ROM has an erasing program, which automatically executes an erasing operation on the recording region. Because of the physical impossibility of an erasing operation this does not affect the ROM portion of the optical disk. If the contents of the ROM is illegally copied onto a rewritable disk, however, then the erasing program comes into effect and prevents the copy disk from being used.

Description: This invention relates to an optical disk capable of optically recording and reproducing data, and an optical disk device adapted to record and reproduce data using the optical disk as the recording medium. Background Art Programs for performing desired data processing, including basic programs, such as, above all, operating systems (OS), various programming languages, simplified program languages or word processeors, or the basic data indispensable for these programs, such as dictionary data, pattern data for Chinese characters or parameter data for pattern recognition, are occasionally not in need of being rewritten in a manner distinct from a variety of general data that are to be processed, but rather some form of write inhibit processing is desired, in order to prevent inadvertent rewriting of the contents by mistaken operation. To this end, in a magnetic disk, such as so-called floppy disk, the basic program or the basic data are protected by specifying the possible presence of write inhibition for each file by a software technique. However, the write protection implemented by the software technique may be cancelled rather easily by the software such that writing on a file specified for write inhibition may be occasionally performed during, for example, the program runaway or on occurrence of software errors. Therefore, for more reliable protection, a disk having the program and the basic data recorded thereon is provided as a so-called program disk separately from the data disk and the write inhibit measures by mechanical or hardware technique employing so-called protect seal or protect notch are frequently applied to the program disk in its entirety. It is noted that, as disclosed for example in the Japanese Patent Publication KOKAI No. 100249/1983, there has been proposed an optical information recording carrier which is provided with signal tracks composed of pits dedicated to reproduction for facilitating adjustment of the recording/reproducing optical system. Recently, a recording medium having an extremely high recording density, such as an opto-magnetic disk, has made its debut. With the optical disk having the ultra-high recording density, it is not desirable from effective utilization of the recording capacity to prepare a disk dedicated to a program file to inhibit the writing therein. Thus the basic program such as the aforementioned OS is formed by tens to hundreds of kilobytes, whereas the basic data are usually formed of hundreds of kilobytes, so that, even when several basic programs and data are recorded in combination, the recording capacity of the order of several megabytes suffice. However, the optical disk usually has the recording capacity amounting to several hundreds of megabytes, which is larger by two decimal places than that for the basic data or program. Therefore, when an optical disk is non-rewritably set as a so-called program disk, recording is made only in a small portion of the recording capacity, while the remaining major portion is not used for recording, which means an economical demerit. Therefore, one is obliged to resort to designating the write inhibit for each file by software technique for protection against mistaken writing, which has a drawback that it has only insufficient protection capability against software errors, as mentioned above. On the other hand, various copy inhibit measures are taken against duplication without authorization. However, the risk is extremely high that the program disk be duplicated and illicitly used by other than the authorized users with the aid of a copy program. EP-A-0204154, which forms the basis of the precharacterising portions of appended claims 1 and 6, is principally concerned with preventing unauthorized duplication of data stored on a magnetic disk. It discloses using a disk of high coercivity such that signals cannot be erased but therefore suffers from the problems discussed above. It also discloses recording validating signals in high coercivity regions of the disk. The operating machine tries to alter these signals and if it is successful, it recognizes the disk as a copy and then destroys data on the disk by erasure, overwriting, etc. According to the present invention, there is provided a disk suitable for data recording and reproduction, a program being recorded on said disk for attempting to alter signals previously recorded non-rewritably at a prescribed region on the disk, characterized in that said disk is an optical disk, said program is an erasure program for executing an erasure of said prescribed region of the disk and said signals comprise said erasure program along with a software program adapted for handling data recorded on the disk and/or along with basic data required for executing a software program. It is already known from FR-A-2578083 to combine rewritable and non-rewritable storage regions on a same disk. According to the invention an erasure program for executing the erasure of the recording regions of the optical disk may be previously non-rewritably recorded on a prescribed region on the disk, along with a file the rewriting of which is not required, such as the software program or the basic data, so that a powerful and reliable write protection as compared with simple protection by software may be implemented. When the record contents of the optical disk are duplicated, the software program and the basic data are erased by the erasure program so that an illicit or unauthorized use of the copy disk is inhibited. According to a further aspect of the present invention there is provided a disk controller for recording and/or reproducing data on and from a disk according to the invention comprising means for automatically accessing and reading said erasure program and means for automatically executing an erasure operation of the prescribed regions. Claim 6 contains a method according to the invention. The invention will be more clearly understood from the following description, given by way of example only with reference to the accompanying drawings in which: Fig. 1 is a diagrammatic plan view showing an optical disk according to the present invention; Fig. 2 is a diagrammatic block diagram showing the construction of an optical disk device adapted for recording/reproducing data using the optical disk as the recording medium; and Fig. 3 is a flow chart for illustration of the operation of the optical disk device. BEST MODE OF PRACTICING THE INVENTION By referring to Figs. 1 to 3, certain embodiments of the optical disk and the optical disk device of the present invention will be explained. Referring to Fig. 1, the optical disk 1 is capable of opto-magnetically recording and/or reproducing the signals. Concentrically or spirally extending tracks are divided into prescribed lengths or at prescribed angles for defining a plurality of sectors. An ID portion 2 in which ID codes including track or sector addresses are recorded, is prerecorded and formed (pre-formatted) as by so-called embossing at the leading position of each of these sectors. In a region of the innermost track of the optical disk 1, a so-called lead-in portion or a disk ID 3 is recorded. Adjacent to the disk ID towards the outer periphery is a so-called TOC (table of contents) portion 4 in which an index information concerning the disk record contents is recorded. The region delimited between an outer peripheral position a of the TOC portion 4 and a position b separated from the position a towards the outer periphery a predetermined distance is a non-rewritable read-only ROM 5. The remaining region as far as the outermost peripheral positon c of the disk is a rewritable RAM 6 adapted for realizing the functions proper to the opto-magnetic recording type disk 1. The ROM 5 is so designed that the signals cannot be written physically therein by an optical pickup head of the user's disk device. For example, the signal recording system adopted in the ROM 5 such that, similarly to the preformated ID 2 in each sector, signals are recorded as the physical changes in shape by forming pits or holes on the recording surface by a so-called embossing operation. However, whilst the address data etc. of the sector IDs 2 are the data used in the optical disk device, such as a disk controller, the contents recorded in the ROM 5 are programs or data exchanged with e.g. a host computer outside the disk device and an erasure program for executing the erasure operation of the recording regions. Thus, in the ROM 5, there is previously recorded and formed by the disk suppliers an erasure program adapted for designating and erasing the recording regions in the ROM 5, in addition to a basic software program, such as the aforementioned OS, programming languages, simplified program languages or word processor softwares, and data such as dictionary data or patterns of Chinese characters, that are indispensable to these programs. It is noted that a discriminative information indicating whether the optical disk is of the type having the aforementioned ROM 5 is written in the disk ID 3, such that, when the disk system is raised in its position for use at the user or initialized by a resetting operation, the optical pickup head first reads out the disk ID 3 to determine if the optical disk is provided with the ROM 5. In the TOC portion 4, the inner peripheral foundary positon a and the outer peripheral boundary position b are recorded. The diagrammatic construction and operation of the essential portion of the system which is adapted for recording and/or reproducing the optical disk on which the boundary positional information of the region of the ROM 5 is recorded, will be explained by referring to Figs. 2 and 3. On starting the use of the optical disk 1, the optical pickup head 10 scans the disk ID 3 of the disk 1 as described hereinabove to reproduce the record contents by a signal reading circuit 11. Depending on the reproduced disk ID information, the disk controller 12 determines whether the optical disk 1 now in use is or is not of the type having the ROM 5 (steps S₁ and S₂ in Fig. 3). When the result is NO (that is, when the disk is not provided with the ROM) the customary disk control operation is performed. Conversely, when the result is YES, the TOC portion 4 of the optical disk 1 is read to read the inner and outer peripheral boundary positoins of the ROM 5 to store the boundary position information in a memory (steps S₃ and S₄ in Fig. 3). The contents of the ROM 5 are then read and the disk controller 12 executes automatically the erasure operation of the ROM by the erasure program afforded as the record contents of the ROM 5, after which the host computer 20 executes the main program, such as word processing, afforeded as the record contents of the ROM 5 (steps S₅, S₆ and S₇). It is noted that the optical disk device is so designed as to exchange data or control signals with exterior devices, such as the host computer 20, through the disk controller 12, while the signals from the optical pickup head 10 are transmitted to the disk controller 12 through a signal read-out circuit 11. Responsive to control commands from the host computer 20, the disk controller 12 controls a laser driver 13 and a head shift control circuit 14 to perform control operatios in the read-, write and erase modes by the optical pickup head 10. The head shift control circuit 14 also operates to drive the head shift motor 15 into rotaiton to control the shifting of the optical pickup head 10 radially of the disk by way of a head supporting plate 16. In the present embodiment, when an erasure operation is automatically executed on the non-rewritable ROM 5 of the optical disk 1, the record contents of the ROM 5 cannot be rewritten or erased, whilst any adverse effects by the mistaken operation, such as destruction of the program or basic data can be completely prevented so that the powerful write protection of the data in the ROM 5 is realized. Since the ROM 5 and the RAM 6 exist together in one disk 1 so that a program disk and a data disk may be combined into one disk to provide an optical disk convenient in practical application. When the record contents of the optical disk 1 are copied to another rewritable optical disk such as an opto-magnetic disk to produce a duplicated disk, the erasure program is executed at the step S₆ for automatically erasing the contents of the copied ROM portions so that use of the disk copied without authorization is inhibited.

Claims: A disk (1) suitable for data recording and reproduction, a program being recorded on said disk for attempting to alter signals previously recorded non-rewritably at a prescribed region (5) on the disk (1), characterized in that said disk is an optical disk, said program is an erasure program for executing an erasure of said prescribed region of the disk (1) and said signals comprise said erasure program along with a software program adapted for handling data recorded on the disk (1) and/or along with basic data required for executing a software program. The optical disk according to claim 1 characterized in that said basic data and said erasure program are previously recorded on the recording surface as physical shape changes. The optical disk according to claim 1 characterized in that said basic data and the erasure program are recorded on the inner periphery (5) of the disk (1). The optical disk according to claim 3 further characterized in that an index information (4) associated with the disk record contents is recorded inwardly of the inner periphery of the disk (1). A disk controller for recording and/or reproducing data on and from a disk (1) according to any one of claims 1 to 4 comprising means for automatically accessing and reading said erasure program and means for automatically executing an erasure operation of the prescribed regions. A method of inhibiting duplication of a disk (1) suitable for data recording and reproduction, comprising recording a program on said disk for attempting to alter signals previously recorded at a predetermined non-rewritable region of the disk, the method being characterized by said disk being an optical disk, said program being an erasure program for executing an erasure of said prescribed region of the disk and said signals comprising said erasure program along with a software program adapted for handling data recorded on the disk (1) and/or along with basic data required for executing a software program.

Inventors: YOSHIDA TADAO SONY CORPORATION, YOSHIDA, TADAO SONY CORPORATION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1987
Main classification: G11B20
IPC codes: G11B7, G06F21, G06F12, G11B11, G11B20