JPS63249937A - Optical disk - Google Patents

Abstract

PURPOSE:To shorten the accessing time of information, by providing track identification code recording parts at the end part of the outermost peripheral side of spiral tracks arranged spirally on a recording plane, and superposing those large number of track identification code recording parts at the outermost peripheral part of the recording plane in a circumferential direction. CONSTITUTION:A large number of tracks 16a... are provided spirally on the recording plane of an optical disk 10. At the end parts of the outermost peripheral side of the tracks 16a-16c, the track identification code recording parts 18a-18c on which identification codes to identify the tracks 16a-16c are provided. By constituting a device in such way, since the track identification code recording parts of the tracks are provided by superposing them at the outermost peripheral side of the recording plane in the circumferential direction, it is possible to read out a track identification code recorded on the track identification code recording part without moving an optical head, and to retrieve a desired track. In such a way, it is possible to perform the retrieval of the desired track rapidly, and to shorten the accessing time of the information remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an optical disc having a large number of tracks, and more particularly to a technique for facilitating and speeding up a track search operation.

2. Description of the Related Art Optical discs are known that have a large number of concentric tracks on a circular recording surface and use light to record information on the tracks or reproduce information recorded on the tracks. For example, read-only optical discs in which information is recorded by arranging a large number of focal points along a track, write-once optical discs in which desired information is recorded by forming bits with laser light, and magnetic discs. The recording layer is made of a material with optical anisotropy, and by irradiating the recording layer with laser light and locally magnetizing the recording layer, information is recorded along the track and by using Kerr rotation angle etc. Examples include magneto-optical disks that reproduce information recorded on a layer.

Problems to be Solved by the Invention The tracks of such an optical disk are usually arranged in a number of concentric circles, and an optical head is used to record information on the tracks or to reproduce information from the tracks. When positioning on a track, the optical head is coarsely fed in a direction intersecting the track, and the track number recorded in a predetermined area of each track is read, and when the desired track number is detected,
The precision feed precisely positions the optical head on the track. As a result, it takes a relatively long time to search for a desired track, making it difficult to access information efficiently.

Means for Solving the Problems The present invention has been made against the background of the above circumstances.
The objective is to provide an optical disc that can shorten information access time.

In order to achieve such an object, the gist of the present invention is to provide a large number of tracks within a circular recording surface, and to record information on the tracks using light or reproduce the information recorded on the tracks. In the optical disc of the type, the tracks are arranged in a spiral on the recording surface, and an identification code for identifying each track is recorded at the outermost peripheral end of the spiral tracks. and a large number of track identification code recording sections are arranged in a row in the circumferential direction at the outermost periphery of the recording surface.

In this manner, the track identification code recording portions of each track are provided in succession in the circumferential direction at the outermost periphery of the recording surface, so the track identification code can be recorded without moving the optical head. A desired 1-rank can be searched by reading the track identification code recorded in the recording section.

Therefore, a search for a desired track can be performed quickly, and the time for accessing information is significantly reduced.

The track identification code recording section of each track is preferably provided with a start bit located at the beginning of the track identification code recording section and different from the bits continuing in the track identification code recording section as the identification code of that track.

In this way, it is possible to easily identify the start bit that is mixed among a large number of bits that are continuous as the identification code of each track at the outermost circumference of the recording surface, so there is an advantage that the starting point of each track can be easily detected. be.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, 10 is a circular optical disc. A track identification code recording area 12 is provided in an area on the outermost side of the recording surface provided on one side of the optical disc 10 and having a width dimension of approximately 1.0 to 2.0 tracks. A data recording area 14 is provided on the inner circumferential side of the track identification code recording area 12.

As shown in detail in FIG. 2, a large number of tracks 16 are spirally provided on the recording surface of the optical disc 10. In the figure, tracks 16a, 16b, and 16C, which are some of the tracks 16, are conceptually depicted. At the outermost end of each track 16a, 16b and 16c, there is a
Track identification code recording sections 18a, 18b and 18G are provided, respectively, in which identification codes for identifying the track identification code are recorded.
On the inner circumferential side following b and 18c, a data recording section 20a,
20b and 20c are provided. In this example,
The identification code is composed of an 8-bit code signal and represents a track number. Note that the data recording sections 20a, 20b, and 20C are constituted by a series of data bits representing written information. Each ellipse in FIG. 2 represents an individual data bit, and the 0 and - colors within the ellipse represent the signal state, ie, the signal of the bit is "1" and "0", respectively.

The track identification code recording sections 18a, 18b and 18c of the respective tracks 16a, 16b and 16c are located in the track identification code recording area 12, and the data recording sections 20a, 20b and 20C are located in the track identification code recording area 12.
are located in the data recording area 14 and are connected in a substantially circumferential direction. That is, the track identification code recording sections 18a, 18b, and 18C are arranged in a slight spiral within the width of the track identification code recording area 12, but they are arranged so that the deviation is one track interval or less. Therefore, they are substantially connected in the circumferential direction within the track identification code recording area 12.

The track identification code recording sections 18a, 18b and 18
Start bits 22a, 22b and 22c are provided at the ends within C, ie at the beginnings of tracks 16a, j6b and 16c, respectively. These start bits 22a, 22b, and 22c are formed to have a total length 2β, which is approximately twice the total length ρ of other bits in the track identification code recording sections 18a, 18b, and 18C, for example. It can be easily identified from the bits.

Next, a case will be described in which information is reproduced by an optical head (not shown) that is movable in the radial direction of the optical disc 10 while the optical disc 10 is continuously rotated around its axis.

The optical head is positioned on the track identification code recording area 12 provided at the outermost circumference of the optical disc 10, and first,
Track identification code recording section 18, for example 18a, 18b
, 180, and the like are sequentially read out.

At this time, the optical head moves each track 16a, 16b, 1
These track identification code recording sections 18a, 18b, and 18C are moved slightly in the radial direction of the optical disc 10 along the track identification code recording area 1.
2, the optical head is hardly moved and the track number unique to each track is read out. In this case, when the start bit 22 is detected, the following 8 bits of information are read out as a track identification code, and for example, after the 8th focus of the tracker identification code recording section 18b is read out, the optical head is moved to the outer periphery. The data is jumped to the side by one track, and the start bit 22c and subsequent parts of the next track identification code recording section 18C are read out. Then, in a control device (not shown), it is determined whether or not the predetermined desired track number and the actually read track number match, and when this determination is affirmed, the desired track is detected. Ru. When a desired track 16, for example 16b, is detected in this way, the optical head moves to that track 16.
b is moved in the radial direction. During this movement process, the information recorded in the data recording section 20b of the track 16b is read out by the optical head. In this case, the track identification codes of all the tracks 16 are read out within one revolution of the optical disc 10, so that the track identification code of the desired track 16 is detected within one revolution of the optical disc 10.

Note that even when detecting the desired track 16 when recording information in the data recording section 20 of the track 16, the desired track is quickly detected as in the above reproduction.

As described above, according to the present embodiment, the track identification code of the desired track 16 is detected within one revolution of the optical disk 10 without moving the optical head, so that the track search can be performed quickly. As a result, information access time is significantly reduced.

Although one embodiment of the present invention has been described above based on the drawings,
The invention also applies in other aspects.

For example, in the above-mentioned embodiment, the track identification code recording section 18 recorded a coat signal indicating the track number, but instead of the track number, a signal indicating a track-specific character such as an alphabet may be used as the track identification code. It may be recorded as .

Further, within the transformer identification code recording area 12, track identification code recording sections 18a, 18b, 18C, etc. may be arranged along concentric circles of the optical disc 10. In this case, there is an advantage that the optical head does not have to be moved when searching for the track 16.

The optical disc 10 may be a read-only optical disc in which information is recorded by arranging a large number of focal points along a track, or a write-once type optical disc in which desired information is recorded by forming bits with laser light. Optical disks, whose recording layer is made of a material with magnetic optical anisotropy, record information along the track and change the Kerr rotation angle by irradiating the recording layer with laser light and locally magnetizing it. It may also be a magneto-optical disk in which information recorded on the recording layer is reproduced using the magnetic disk.

Further, although the start bit 22 is composed of one bit having a different total length from other bits in the track identification code recording section 18, it may be composed of a plurality of bits. In the above-mentioned playback-only optical disc and write-once optical disc, the bits are composed of so-called bits,
In the magneto-optical disk, the bit is constituted by a locally magnetized portion of the recording layer.

It should be noted that the above-mentioned embodiment is merely one embodiment of the present invention, and the present invention can be variously modified in other aspects as well.

[Brief explanation of the drawing] FIG. 1 is a front view showing an embodiment of the present invention. FIG. 2 is an enlarged view of a part of FIG. 1. 10: Optical disc 12; Track identification code recording area 16: Truck 18 Nidrak identification code recording section 22 start bits

Claims (2)

[Claims] (1) In an optical disc that has a large number of tracks on a circular recording surface and uses light to record information on the tracks or reproduce information recorded on the tracks, the tracks are arranged in a spiral pattern on the recording surface. The spiral tracks are arranged in a shape, and a track identification code recording section for recording an identification code for identifying each track is provided at the outermost end of each of the spiral tracks. , an optical disc characterized in that the recording surfaces are arranged in a row in the circumferential direction at the outermost peripheral part. (2) In the track identification code recording section of each track,
The optical disc according to claim 1, wherein a start bit is located at the beginning of the track identification code recording section and is provided as an identification code of the track, which is different from bits that continue in the track identification code recording section. .