Optical disk having a particular format to store user-selected data, such as video data or computer files, including a dedicated TOC region

Abstract

A method of reproducing data from an optical disk having a diameter less than 140mm, a thickness of 1,2mm and a recording area divided into a lead-in area, and a program area, and wherein said data is recorded as pits representing modulated, error-correction encoded user information in sectors in user tracks in said program area and representing modulated, error-correcting encoded control information in sectors in one of said lead-in area or said program area, with said control information including addresses of respective user tracks, the tracks having a track pitch in the range of 0.646µm to 1.05µm, said method comprising the steps of rotating said disk to obtain a constant linear velocity; projecting a pickup light beam through a lens for optically reading the rotating disk, said pickup light beam having a spatial frequency I=» / 2NA, where the spatial frequency I is less than the track pitch, » is the wavelength of the pickup light beam and NA is the numerical aperture of the lens; demodulating the data read from said disk; error correcting the demodulated data; separating the error corrected data into control information and user information; and using said control information to access and read selected user tracks in response to access instructions from a user.

Description

BACKGROUND OF THE INVENTIONThe invention relates to a novel optical disk and, more particularly, to that disk, to a method of recording and reading information on the disk and to apparatus for carrying out that method.Optical disks have been used as mass storage devices for computer applications, and such optical disks are known as CD-ROMs. The disk which is used as the CD-ROM is modeled after the standard compact disk (CD) that has been developed for audio applications and is basically an audio CD with various improvements and refinements particularly adapted for computer applications. Using such a CD as a standard, the CD-ROM has a data storage capacity of about 600 Mbytes. By using audio CD technology as its basis, the CD-ROM and its disk drive have become relatively inexpensive and are quite popular.However, since conventional audio CDs with their inherent format and storage capacity have been adapted for CD-ROMs, it has heretofore been difficult to improve the data storage capa...

AI Technical Summary

Benefits of technology

Another object of this invention is to provide an optical disk which exhibits a higher access speed, thereby permitting quick access of arbitrary locations, such as sectors, to be accessed quickly.

A further object of this invention is to improve the storage capacity of an optical disk, thereby making it more advantageous for use as a CD-ROM.

An additional object is to provide an improved optical disk which stores data with reduced redundancy.

Still another object of this invention is to provide an improved recording format for an optical disk which enhances the error correcting ability thereof.

Another object of this invention is to provide an optical disk having a substantially improved recording density, thereby facilitating use of the disk as a CD-ROM.

A further object of this invention is to provide an improved optical disk having data recorded in sectors, with each sector having a sector header that is easily and rapidly read, particularly because the sector header is not encoded in a form which requires a substantially long amount of time before it is successfully decoded and recognized.

Problems solved by technology

However, since conventional audio CDs with their inherent format and storage capacity have been adapted for CD-ROMs, it has heretofore been difficult to improve the data storage capacity.

In typical computer applications, a capacity of 600 Mbytes has been found to be insufficient.

However, computer applications generally require a transfer rate far in excess of 14 Mbps; but it is difficult to attain a faster transfer rate with conventional CD-ROMs.

Yet another disadvantage associated with conventional CD-ROMs, and which is due to the fact that the audio CD format has been adapted for computer applications, is the relatively long access time associated with accessing a particular location on the disk.

For example, accessing a particular sector may take too much time for the CD controller to identify which sector is being read by the optical pick-up.

A still further difficulty associated with CD-ROMs, and which also is attributed to the fact that such CD-ROMs are based upon audio CD technology, is the error correcting ability thereof.

However, in computer applications, interpolation often cannot be used to conceal errors because of the low correlation of such data.

However, the block completion code generally takes a relatively long amount of time to decode the data, and more importantly, its error correction ability is believed to be insufficient in the event that multiple errors are present in a block.

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