Optical disk and optical disk reproduction system

Details Optical disk and optical disk reproduction system Optical disk and optical disk reproduction system

1998-11-19

2001-08-07

Edun, Muhammad (Department: 2651)

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

Control of information signal processing channel

C369S047210, C369S053200, C369S053410

Reexamination Certificate

active

06272081

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to optical disks, such as CDs (Compact Disks) and DVDs (Digital Versatile Disks), and optical disk reproduction systems, and more particularly to an improved method of recording TOC (Table-OF-Contents) information on an optical disk.
In optical disks such as CDs (Compact Disks), TOC (Table-OF-Contents) information is used to make instantaneous access to a start point of a designated recording track. It has been conventional to record such TOC information as subcodes in a lead-in area of the disk. Specifically, as shown FIG.
11
. the optical disks generally include a lead-in area LIA disposed along its inner periphery, a lead-out area LOA disposed along its outer periphery, and a program area PGA located in between the lead-in area LIA and the lead-out area LOA. These three areas each contain recording units called “EFM (Eight to Fourteen Modulation)” frames. Each of the EFM frames, as illustratively shown in
FIG. 12
, includes a synchronizing bit, a subcode (one symbol), data (12 symbols), P parity bits (four symbols), data (12 symbols) and Q parity bits (four symbols), and the 12-symbol data and P and Q parity bits constitute data of a main channel. Thus, each of the EFM frames of the optical disk contains a total of 33 symbols in the main channel and subcode channel: 32 symbols in the main channel; and one symbol in the subcode channel. Because each of the symbols consists of “14+3” bits and “24+3” bits are used as the synchronizing bit, each of the EFM frames has a total length of “24+3+(14+3)×33” (=588) bits. The subcodes of 98 such EFM frames together constitute a single subcode block that represents a single unity of information, and TOC (Table-OF-Contents) information is recorded in the subcode block of the lead-in area LIA.
FIG. 13
shows one of the subcode blocks in the lead-in area LIA. The subcode in each of the EFM frames is EFM-decoded into one-byte or eight-bit data, and unique channel names “P” to “W” are allocated respectively to the eight bits of the decoded subcode. The subcodes of the first two EFM frames are called “S
0
” and “S
1
” codes, which are used as a synchronizing signal. A group of the subcodes of channel Q in 96 EFM frames is commonly called a “subcode frame”, and this subcode frame represents positional information of a track. In the subcode frame consisting of 96 Q-channel bits, bits Q
1
to Q
4
represent a data/audio flag, bits Q
5
to Q
8
represent an address, bits Q
9
to Q
16
represent a track number, bits Q
17
to Q
24
a start point, and bits Q
25
to Q
48
represent a relative position TIME of the subcode frame in the lead-in area LIA; the relative position data TIME comprises a set of three data MIN, SEC and FRAME indicative of minute, second and frame, respectively. Further, of the 96 Q-channel bits, bits Q
57
to Q
80
represent an absolute position PTIME of a track corresponding to a track number specified by the above-mentioned start point, the absolute position data PTIME comprises a set of data PMIN, PSEC and PFRAME. Last 16 bits Q
81
to Q
96
represent a CRC (Cyclic Redundancy Check) code to be used for error detection.
A plurality of such subcode frames arranged in the aforementioned manner together constitute TOC information as illustratively shown in FIG.
14
. The TOC information indicates respective track numbers and start points of all of the tracks provided in the program area PGA. Because the subcodes themselves do not have error correcting capability, the same start point information of each one of the tracks is recorded repetitively three times in succession. Similarly, a same set of three types of control information, i.e., control information A
0
(indicative of the leading or forefront track number, a type of the disk, etc.), control information A
1
(indicative of the last track number) and control information A
2
(indicative of a total recording time period), are recorded repetitively three times in succession in an end portion (corresponding to frame numbers “n+m” to “n+m+8” in the illustrated example) of the TOC information. Such TOC information is recorded repetitively in the lead-in area.
Today, the number of tracks recordable in the program area PGA differs depending on the type of the optical disk; the smallest number is just one while the greatest number is 99. Thus, the maximum number of subcode frames necessary for recording TOC information will be
[99 (the number of the recordable tracks)+3 (the number of the types of the control information)]×3=306  Mathematical Expression (1)
In the CDs (Compact Disks), 75 frames correspond to a time length of one second and it will take 1/75 (=0.0133) seconds to read out a single subcode frame at the normal replay speed. Thus, with the CD having the greatest number of, i.e., 99 recordable tracks, it would take as long a time as 4 seconds to completely read out the TOC information.
Further, although read errors may be detected by use of the CRC code in the subcode frame, the subcode frame does not have error correcting capability. Thus, when some read error is detected, next one of the repetitively recorded TOC information has to be re-read, which would require an even longer readout time.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an optical disk and optical disk reproduction system which allow table-of-contents (TOC) information on the disk to be read out at high speed.
In order to accomplish the above-mentioned object, the present invention provides an optical disk having various information recorded thereon on a frame-by-frame basis, each of the frames being organized in a predetermined format comprising a main channel where data are recorded and a subcode providing additional information including recorded positions of the data, which is characterized in that table-of-contents information for the data recorded in the main channels is contained in the main channels of the optical disk.
Because the table-of-contents or TOC information is recorded, rather than in the subcode channels, in the main channels having a much greater capacity than the subcode channels, the present invention can record the TOC or table-of-contents information collectively as a single data block, thereby eliminating the need for recording it dispersedly across a multiplicity of subcode frames as in the past. With such an arrangement, the present invention affords the superior benefit that the table-of-contents information can be read out collectively within a short period of time and hence at a greatly increased speed.
For that purpose, when a subcode block representing a single unity of information is formed of a plurality of the subcodes belonging to n frames, the table-of-contents information is contained in the main channels of the n frames in such a manner that every piece of information needed as the table-of-contents information is fully incorporated in a predetermined data block made up of the data of the main channels belonging to the n frames.
The table-of-contents information may be recorded in the main channels of any of the lead-in, program and lead-out areas of the optical disk. In the case where the table-of-contents information is recorded in the main channels of the lead-in area whose subcode has no absolute position information of its own, repetitive recording of the table-of-contents information substantially throughout the lead-in area would greatly facilitate retrieval or acquisition of the information. Because no substantive data is recorded in the lead-in area, such repetitive recording of the table-of-contents information throughout the lead-in area would not result in a waste of storage area.
Further, in the case where the table-of-contents information is recorded in the main channels of the program area or lead-out area, the table-of-contents information may be located in a particular recording position previously agreed upon between an optical disk dri

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