JPH0734304B2 - Disk-shaped recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A. Industrial field of use B. Outline of invention C. Prior art D. Problems to be solved by the invention E. Means for solving the problem F. Operation G. Example G-1. Implementation Outline of example (Figs. 1 to 3) G-2. Recording format of optical disc (Fig. 3) G-3. Specific example of address signal portion (Fig. 1) G-4. Specific example of pit shape (Fig. 2) G-5. Specific example of address mark (Fig. 4) G-6. Example of other address mark (Fig. 5) H. Effects of the invention A. Industrial application field The present invention relates to a disc-shaped recording medium such as a magneto-optical disc, and more particularly to a disc-shaped recording medium in which a time-division servo signal such as a so-called sector servo signal is pre-recorded and formed on the disc.

B. Outline of the Invention The present invention comprises a servo signal area in which servo pits and the like are formed and a data / address signal area in which data, addresses, etc. are written are alternately provided along the circumferential direction of the disk. In a disc-shaped recording medium, a so-called mn modulation (where m
<N) is used, and some of the bit patterns that are not adopted in the m-n modulation are used as address marks, and these bit patterns are selected and recorded according to desired address information and the like, and In addition to enabling the desired information to be utilized effectively,
By providing address information in the address mark, high speed access is possible.

C. Conventional Technology In recent years, disc-shaped recording media such as optical discs and magneto-optical discs utilizing an optical or magneto-optical signal recording / reproducing method have been developed and are being supplied to the market.
These disk-shaped recording media include ROM (Read Only Memory) type recording media such as so-called CDs (Compact Discs) and so-called write-once data that allows users to write data once. There is known a recording medium of a type, a recording medium capable of rewriting data (so-called overwriting) such as a magneto-optical disk.
As one of the techniques for realizing a unified recording format for these various recording media, as in the case of so-called sector servo in a hard disk in the field of magnetic disks, a concentric or spiral shape on the disk is used. Servo signals are recorded in advance on a track at predetermined intervals or at predetermined angles (so-called preformatting), and continuous servo control is performed by sampling and holding these discrete servo signals during disk rotation drive. So-called sampled servo technology has been proposed. In this case, the servo signal is recorded by mechanically forming so-called pits or bumps. The recording interval of the servo signal, that is, the data signal recording area between the servo signal and the next servo signal is set sufficiently shorter than one sector as one unit of the recording data, and for example, several tens of data signals are set. The recording areas collectively form one sector.

D. Problems to be Solved by the Invention By the way, in the disc-shaped recording medium formed by recording and forming the discrete servo signals as described above, the head of the plurality of data signal recording areas forming one sector is formed. In the data recording area of, an address signal including information such as the track number and sector number of the sector is recorded. This address signal is generally modulated by the same modulation method as data, and is recorded by so-called embossing that forms mechanical uneven shapes such as bits and bumps, like the servo signal described above. When the data signal is also recorded and formed by the bits or bumps as in the ROM type or PROM type disc, the address and the data cannot be distinguished when the signal is read by the disc reproducing device or the like. Therefore, an identification signal called an address mark is recorded in the servo block in which the address signal is recorded, and the address signal for the sector is the data signal area at the head position of one sector. It is possible to determine what is recorded.

In order to distinguish the address mark from the data or address, a bit pattern different from the bit pattern used for the recording channel bits of the data or address may be used, or a bit pattern outside the above-mentioned modulation rules may be used. ing. And, this address mark is used only for synchronization of channel bits other than this, and is not used for other purposes, and in terms of effective utilization efficiency of the signal recording area of the disk-shaped recording medium, Further improvement is desired.

The issuer, etc. paying attention to such a point, make the above-mentioned address mark itself carry some information so as to effectively utilize the signal. For example, by inserting the address information, high-speed access is also possible. It is intended to provide a disc-shaped recording medium.

E. Means for Solving the Problems In order to achieve the above-mentioned object, the disk-shaped recording medium according to the present invention has a servo signal area in which a servo signal is recorded in advance, and at least a data signal and an address signal are written. In a disk-shaped recording medium in which data and address signal areas are alternately provided along the circumferential direction of the disk, a bit pattern of m bits is converted into a bit pattern of n bits (m <n). m-
The data signal and the address signal are modulated by n modulation and sequentially recorded in the data / address signal area, and an address mark for indicating that the signal recorded in the data / address signal area is an address signal ,
It is characterized in that bit patterns more than those used in the mn modulation are used, and these bit patterns are selected and recorded according to address information.

F. Action By including address information in the address mark, effective use of signals can be achieved and high-speed access becomes possible.

G. Examples Hereinafter, one example of the disc-shaped recording medium of the present invention will be described with reference to the drawings.

G-1. Schematic Description of Embodiments (FIGS. 1 to 3) FIG. 1 shows a servo signal region 3 and a data area in a disk-shaped recording medium such as an optical disk according to an embodiment of the present invention.
The address signal area 4 is schematically shown, and these areas 3 and 4 are alternately provided on a track 2 formed along the circumferential direction of the optical disc 1 shown in FIG.
In the example of FIG. 1, an address signal is recorded in the data / address signal area 4, and a concrete example of the recording form of the address mark at the head position of this address signal and the servo area is shown in FIG.

In this case, so-called mn modulation (where m <n) is used as the modulation method for the data signal and the address signal, and
-A plurality of types of bit patterns not used for -n modulation are used as the address mark, and any one of the plurality of bit patterns is selected according to desired address information, for example, a track number or a sector number. By recording, address information is included in the address mark.

G-2. Disc Recording Format (FIG. 3) Prior to a detailed description of the embodiment, a disc-shaped recording medium having the above-described sample servo recording format, for example, an optical disc, is referred to FIG. While explaining.

In FIG. 3, concentric (or spiral) tracks 2 of the optical disc 1 are divided into sectors at predetermined angles or lengths, and the sectors are further recorded with servo signals in the form of pits. The data / address signal area 4 at the head of one sector is divided into a plurality of groups of a servo signal area 3 and a data / address signal area 4 in which a data signal and an address signal are written.
At least an address signal is recorded in the. When the net data size of one sector is, for example, 512 bytes, additional information, error correction code, etc. are added to this to form record data of, for example, about 672 bytes.
When the length of the data / address signal area 4 is, for example, 16 bytes, one sector is constituted by the area 4 of, for example, about 43 in consideration of address signal recording. 1
The track 2 of the book has n such sectors, for example
32 are provided.

G-3. Concrete Example of Address Signal Part (FIG. 1) Next, regarding the recorded contents of the area 4 in which the address signal is recorded corresponding to the head position of the sector in the data / address signal area 4. , Will be described with reference to FIG.

In the data / address signal area 4 of FIG. 1, an address signal portion 5 of, for example, 8 bytes is recorded and formed continuously with the servo area 3 in a recording form such as the so-called pit. In this address signal portion 5, in order from the beginning position,
Address marks ADM _T and ADM _{S of} 1 byte each are recorded, and following these address marks ADM _T and ADM _S , a spare byte TR _R of a track number of 1 byte each,
The same upper byte TR _M , the same lower byte TR _L and the sector number S are recorded. Subsequent to the sector number S, inverted data _M and _L of the upper byte TR _M and the lower byte TR _L of the track number are recorded in order. In addition, for example, in the 16-byte data / address signal area 4, the remaining 8 bytes other than the address signal portion 5 are
Saved for other purposes.

Here, the address marks ADM _T and ADM _S are recorded with a bit pattern different from the modulation bit pattern of these signals in order to distinguish them from normal data signals and address signals. This is because, for example, in mn modulation in which m-bit input data is converted into n-bit output data (where m <n), the above mn-modulation rule is satisfied in the n-bit bit pattern, but the data is So-called spare bit patterns that were not adopted in the conversion table,
It is used as the address marks ADM _T and ADM _S. Further, in the embodiment of the present invention, by selecting one of the plurality of spare bit patterns for these address marks ADM _T and ADM _S according to desired address information, the address ADM _T and ADM _S It has address information itself. For example, a track number can be identified for the address mark ADM _T , and a sector number can be identified for the address mark ADM _S by selecting one of 16 types of bit patterns, for example.

G-4. Specific examples of the pit shape (Figure 2) Figure 2 herein shows a specific example of the recording state of the address mark ADM _T immediately following the servo signal area 3 and region 3 (pit shape) ing.

In FIG. 2, three pits P _A , P _B and P _C are formed in the servo signal area 3, respectively. Pit P _A ,
P _B is formed with a vertical shift with the center line (dotted line) of the track formed on the disk 1 interposed therebetween, and the pits P _C are formed on the center line. The diameter of each of these pits P _A , P _B , and P _C is about 0.5 to 1.0 μm, and the actual length L of the servo signal area 3 is, for example, 15 to 30 μm.
It is about m. The arrangement of the pits P _A , P _B , and P _{C in} the direction orthogonal to the track direction, that is, the radial direction of the optical disc 1 will be described. The pits P _B and P _C are linearly arranged. Whereas
The pits P _A are arranged such that their positions are displaced, for example, every 16 tracks in the longitudinal direction of the tracks. The array of the pits P _A , which is displaced every 16 positions, is used for performing a so-called traverse count for obtaining the track number of the track currently being scanned by the optical pickup. Here, the pit P _A is sampled at the timing of the sample pulse SP ₁ or the sample pulse SP _{2 in} the reproducing circuit system, and each pit P _B , P _C is sample pulse SP ₃ , SP ₅
Sampled at each of the above, and further, above pit P _B
The mirror area between the pit and the pit P _C is sampled by the sample pulse SP ₄ and used for various servos and clock generation. That is, the servo signal of this embodiment is used for each control operation of focusing, tracking, clocking, and the traverse count.

If the data address signal region 4 that follows the servo signal area 3 corresponds to the beginning of the sector, the address signal as described above is recorded, the address mark ADM _T is disposed immediately after the servo signal area 3 . In the example of FIG. 2, 4/14 modulation, which is a type of 8-14 modulation, is used as the data signal modulation method, and the address mark ADM _T (and ADM _S ) is used.
For this, 16 types of spare bit patterns in the 4/14 modulation that are easy to decode are used.

G-5. Specific example of address mark (Fig. 4) Generally, in m-n modulation (where m <n), n-bit channel bits recorded for 2m input data of m bits. The number of patterns of 2n is simply 2n, but considering the recording / reproducing characteristics and the like, at least the number of input data is a pattern that satisfies a predetermined condition from these 2n channel bit patterns.
A conversion table for mn modulation is obtained by selecting 2m pieces and associating them with the input data. For example, to explain 4/14 modulation, which is a type of 8-14 modulation, for a modulated 14-bit pattern, select 4 bit positions from 14 bit positions, set "1", and set the rest. "0"
In addition, the 14th bit is always set to “0”, and under the condition that the distance between consecutive “1s” is 2 or more, for example, from the 14th bit pattern that satisfies this condition, You get a conversion table like a table.

According to the number of bits of the input data, ⁸
= 256 kinds of 14-bit patterns are used, but 14-bit patterns satisfying the above conditions exist other than those described in Table 1 above, and other than conversion of input 8-bit data. It is stored or reserved as a spare bit pattern for use.

Of the above spare bit patterns not included in Table 1, for example, 16 kinds that can easily decode numerical values such as track numbers are selected, and these 16 kinds of spare bit patterns are selected as the above-mentioned track. Corresponds to numbers 0 to 15 such as numbers and sector numbers. Specific examples are shown in Table 2.

FIG. 4 shows a specific pit shape recorded and formed on the disk in correspondence with Table 2 above. In FIG. 4,
The horizontal axis shows the pit position in the track direction corresponding to the channel bit, the vertical axis shows the track number and the like, and the pit P is formed at the position of bit "1".

When such a spare bit pattern is used for the address mark, the address mark can be easily discriminated by three consecutive "1" s.
By the position of one "1", the numerical value represented by the bit pattern can be easily decoded, that is, with a decoder having a relatively simple circuit configuration.

Here, the address mark for displaying the track number described above
In the case where the ADM _T (see FIG. 1) is used to indicate the track number by using the spare bit pattern shown in the above Table 2 and FIG. 4, for example, in combination with the above-mentioned traverse count for every 16 tracks during seek operation, etc. , 1 track can be specified in a short time without reading the address. Also the above address mark ADM _S
By instructing the sector number by using the spare bit pattern described above, sector management in one track can be performed, and high-speed seek and high-speed access can be realized in addition to the track number detection. Even if the number of sectors on one track is 32, the sector can be specified by detecting half-rotation of the disk. Even if such detection is not performed, every two sectors for every 32 sectors on one track can be identified. Can be identified and is sufficiently practical.
If the data size of one sector is, for example, 1024 bytes, and one track is 16 sectors, one track can be represented by the sector number display by the 16 types of spare bit patterns shown in Table 2 and FIG. Of course, one sector of can be identified.

G-6. Examples of other address marks (Fig. 5) When the bit patterns of the address marks shown in Table 2 and Fig. 4 described above use 4/14 modulation which is a kind of 8-14 modulation. Other than this, in the case of 4/15 modulation which is a kind of 8-15 modulation, a bit pattern not used for modulation can also be used as an address mark in the same manner. A specific example of the bit pattern used for the address mark in the case of this 4/15 modulation will be described with reference to Table 3 and FIG.

This 4/15 modulation means that for 8-bit input data, 15
When converting to a 15-bit pattern that can be obtained by selecting four positions from each of the bit positions of and setting them to "1", from the odd-numbered position of the above 15 bit positions,
The rule is to select two or two even-numbered positions and not select the last fifteenth position. Bit pattern of 15 bits which satisfies this rule is present more than two ⁸ bit pattern which is not used for conversion of the input data of 8 bits are left as the bit pattern of the preliminary. Of these spare bit patterns, as the bit patterns that can be easily decoded, for example, eight kinds of bit patterns in which four "1" are consecutive are used, and the numerical values of 0 to 7 as the track number and the sector number are used. Can be represented and is shown in Table 3 and FIG.

By using such a bit pattern as an address mark, if four consecutive "1" s are detected, it can be determined as an address mark. By detecting the leading position of the four consecutive "1" s, the numerical value can be easily decoded. It is possible to check the track number and sector number.

It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the case of 4/14 modulation described above, four consecutive "1" The above bit pattern may be used for the address mark, and in addition to this, any bit pattern not used for the above-mentioned modulation can be used for the address mark. Also,
The modulation method is not limited to the above 4/14 modulation or the above 4/15 modulation,
The present invention can be applied to various modulation methods.
Further, the address mark may be only for the track number or only for the sector number, and an address mark indicating other address information may be provided, and one address information, for example, a track number or the like may have an address mark of 2 bytes or more. You may use it.

Also, an address mark indicating identification information other than the address can be provided.

H. Effect of the Invention According to the disc-shaped recording medium of the present invention, by including address information in the address mark itself, the signal can be effectively used and high-speed seek and access can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a recording form of a main part of each track in a disk-shaped recording medium according to an embodiment of the present invention, and FIG. 2 is a radial direction of the disk with respect to a servo signal area and an address mark immediately after the area. FIG. 3 is a schematic diagram showing the arrangement of pits existing along the line, FIG. 3 is a schematic diagram showing the recording pattern of the magneto-optical disk in the above-mentioned embodiment, and FIGS. 4 and 5 are the bit patterns used for address marks. It is a figure which shows each different specific example. 1 ... Optical disc 2 ... Track 3 ... Servo signal area 4 ... Data / address signal area 5 ... Address signal recording portion

Claims (1)

[Claims] 1. A disk-shaped structure in which a servo signal area in which a servo signal is recorded in advance and a data / address signal area in which at least a data signal and an address signal are written are provided alternately along the circumferential direction of the disk. In the recording medium, the data signal and the address signal are modulated by mn modulation for converting a bit pattern of m bits into a bit pattern of n bits (where m <n) and sequentially recorded in the data / address signal area. A bit pattern other than the pattern used in the mn modulation is used as an address mark for indicating that the signal recorded in the data / address signal area is an address signal. A disc-shaped recording in which a bit pattern is selected and recorded according to address information. Media.