JPH05325420A - Information recording medium - Google Patents

Abstract

PURPOSE:To discriminate a track by one track resolution even by a small number of Gray codes by forming a host pattern by combining Gray codes of plural patterns extending over plural blocks. CONSTITUTION:In a track T1, a Gray code 2 having a pattern A, and a Gray code 5 having a pattern B are mixed. The Gray code has one piece or two pieces in three kinds of patterns of A, B and C, and also, forms a host pattern by these combinations extending over three blocks. That is, an arbitrary track extending from T1 to T9 is described by the host pattern expressed by the kind of two patterns in A, B and C and their mixing ratio. Accordingly, when the head reads the Gray code extending over three blocks, one track in 9 tracks is discriminated from a prescribed relational expression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium having a track address used for high speed track search.

[0002]

2. Description of the Related Art In recent years, information recording media such as optical disks or magnetic disks have been improved so that information can be retrieved at higher speed.

An example of the above-mentioned conventional information recording medium will be described below with reference to the drawings.

FIG. 4 is a partial block diagram of a conventional information recording medium. In FIG. 4, 10 is a servo block, and 30 is a recording information block. Both of them are provided alternately along the track T1 on the information recording medium substrate. The record information block 30 is a place for recording information data, which is composed of about 100 bits. A gray code 20 is provided in each servo block. 1
The servo blocks in the tracks all have the same pattern of gray code. For example, the servo block of track T1 is provided with the pattern A gray code. Similarly, as shown in FIG.
3 has pattern A, T4 to T6 have B, and T7 to T9.
Are assigned C respectively.

The operation of the information recording medium having the above structure will be described below.

First, when the read head is moved from another track to search the track T1, the track T1 is searched.
Must be distinguishable from the head.
Gray code 20 is an identification code therefor. Ideally, one identification code should be assigned to every track formed on the information recording medium, but if the number of tracks is large, the area for that becomes large,
As a result, the information recording area is pressed. For example, in the case of an optical disc having a total number of tracks of about 9000, a 14-bit Gray code area is required. Therefore, in order to identify a track with a small number of bits, the entire track area is divided into zones, and the gray code 20 is periodically assigned to each zone. For example, if the entire track area is divided into 1000 zones, each zone becomes 9 tracks, and the gray code can express 9 patterns, that is, about 4 bits.

In order to further reduce the gray code area, in the conventional example, the same gray code is assigned to a fixed number (= M) of tracks to reduce the number of patterns to 1 / M. For example, as shown in FIG. 4, in each zone having 9 tracks, if one pattern is assigned to 3 continuous tracks, the gray code 20 can be described by 3 patterns, that is, about 2 bits. (For example, “Nikkei Electronics 12/15” No. 410, pages 163-167).

[0008]

However, in the above-mentioned configuration, the same pattern code is assigned to several lines, so that there is a problem that the track identification resolution by the gray code is lowered. That is, not only the track T1 but also the gray codes of T2 and T3 have the same pattern A, so that the track T1 could not be identified only by the gray code. As a result, in order to identify a track, the track address provided every approximately 1000 bytes must be read, which causes a decrease in track search speed.

In view of the above problems, the present invention provides an information recording medium capable of identifying a track with one track resolution even with a gray code having a small number of bits.

[0010]

In order to solve the above problems, the information recording medium of the present invention has an upper pattern formed by combining gray codes of a plurality of patterns arranged over a plurality of blocks. It is a thing.

[0011]

According to the present invention, the number of patterns can be increased without increasing the number of bits of the gray code area, and as a result, the track discrimination ability can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An information recording medium according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the essential parts of an information recording medium in an embodiment of the present invention. In FIG. 1, reference numerals 1 and 4 denote servo blocks, which have Gray codes 2 and 5, respectively. Reference numerals 3 and 6 are recording information blocks. Each is provided on the track T1 and has substantially the same function as the conventional example. The difference from the conventional example is that the gray code 2 having the pattern A and the gray code 5 having the pattern B are mixed in one track. FIG. 2 shows the arrangement of gray code groups in one zone (= 9 tracks). Gray code is A, B,
One or two of the three C patterns are provided, and the combination of these patterns over three blocks forms the upper pattern.

The operation of the information recording medium having the above structure will be described below with reference to FIGS. 1 and 2.
First, on track T1, A, A,
B gray code is provided. Similarly track T
The combination from 2 to the track T9 is described by the combination of the above-mentioned three patterns of gray codes.

These relational expressions are listed below. T1 = (A, A, B) T4 = (B, B, C) T7 = (C, C, A) T2 = (A, B, B) T5 = (B, C, C) T8 = (C, A, A) T3 = (B, B, B) T6 = (C, C, C) T9 = (A, A, A) That is, any track from T1 to T9 is Of these, the two patterns are uniquely described by the upper patterns expressed by the types and their mixing ratio (for example, the track T1 is A: B = 2: 1). Therefore, if the head reads the gray code over three blocks, one of nine tracks can be identified by the above relational expression. Generally speaking, N (=
By mixing and arranging the gray codes of 3) patterns over M (= 3) blocks, one track in N × M (= 9) tracks can be identified. As a result, one zone (= 9
(Track) can be represented without reducing the track resolution.

As described above, according to the present embodiment, by combining a plurality of patterns of gray codes over a plurality of blocks to form an upper pattern, a gray code with a small number of bits can be used without deteriorating the track identification capability. It becomes possible to secure a zone.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram of the second embodiment of the present invention. For simplicity, track number T is shown in FIG.
Only the arrangement of 1 to T21 and the gray codes 2 and 5 are shown. The difference from the first embodiment is that in the previous embodiment, the upper pattern that extends over a plurality of blocks is represented by the mixture ratio of two types of gray code patterns, whereas two types of gray code patterns are used. Is a point represented by a cyclic binary display of. As a result, N (= 3) gray codes are arranged in M (= 3) blocks, so that N × (2
^M −1) (= 21) tracks can be described.

As described above, a wider track zone can be ensured by representing the upper pattern over a plurality of blocks in binary representation of two types of gray code patterns.

[0019]

As described above, according to the present invention, by combining a plurality of patterns of gray codes over a plurality of blocks to form a higher-order pattern, a gray code with a small number of bits does not impair the track identification capability and a wide zone. It becomes possible to secure.

[Brief description of drawings]

FIG. 1 is a configuration diagram of essential parts of an information recording medium in a first embodiment of the present invention.

FIG. 2 is a configuration diagram of an information recording medium in the same embodiment.

FIG. 3 is a configuration diagram of an information recording medium in a second embodiment of the present invention.

FIG. 4 is a configuration diagram of main parts of a conventional information recording medium.

FIG. 5 is a configuration diagram of a conventional information recording medium.

[Explanation of symbols]

 1, 4 Servo block 2, 5 Gray code 3, 6 Information recording block

Claims (3)

[Claims] 1. An information recording medium in which track identification marks capable of taking a finite number of patterns are provided at predetermined intervals, and a track identification mark having a first pattern and a second
An information recording medium, wherein an upper pattern determined by a fixed number of track identification marks consisting of either one or both of the track identification marks having the pattern is provided on an arbitrary track. 2. A high-order pattern is represented by a composition ratio of a track identification mark having a first pattern and a track identification mark having a second pattern among a fixed number of track identification marks. 1. The information recording medium described in 1. 3. The upper pattern is represented by a binary representation of a track identification mark having a first pattern and a track identification mark having a second pattern out of a fixed number of track identification marks. Item 1. The information recording medium according to item 1.