JPS60256923A - Optical disc exclusive for reproduction - Google Patents

Abstract

PURPOSE:To attain high speed access by providing a guide track for non-recording of information between a directory region and an information recording region so as to make tracking/focusing stable and attaining accurate cross count of the track. CONSTITUTION:Information is written in tracks 10, 12 in the recording regions I, IIat manufacture of an optical disc, the information has a sector structure comprising an address section 5 and an information recording section 6, a track 11 of a space has a guide track only and has no sector structure. The track 11 is formed in the same pitch as that of the tracks 10, 12, and even if the optical head is placed at the space at the start, the tracking/focusing is attained and the optical head is made stable in the steady-state. Since no recorded region misleading the count of track crossing exists for the optical head when it moves between the regions I and II, the accurate count is attained and the transfer of the optical head is made smooth.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a signal recording form of a read-only optical disc on which signals are recorded in advance.

Conventional Structures and Problems Optical disks are attracting attention as high-density, large-capacity memories because they are non-contact and can record or reproduce signals by focusing a laser beam onto a minute spot. Therefore, many information recording and reproducing devices using optical disks are on the market. In the future, when optical disk devices become widespread as external memories in computer systems and the like, operating systems, ready-made programs, data, etc. will be provided on optical disks. In other words, there arises a need for a read-only optical disc. Since a read-only optical disk is played back by a device capable of recording and playing back, its signal recording format needs to be consistent and compatible with the signal recording mode of the optical disk for recording and playback. FIG. 1 is a diagram showing an optical disc for recording and reproduction. In FIG. 1, reference numeral 1 indicates an optical disk, and reference numeral 2 indicates an optical disk.) An IJ area 3 is an information recording area.

When using a memory such as an optical disk for recording and playback, in addition to an information recording area for recording information to be recorded, it is common to have a directory area on the memory for recording address information of the information recording area where that information is recorded. It is true. In addition, if the capacity of these areas is defined in advance, the content of the information to be recorded will be changed.

Depending on the quality, some areas of memory may become unusable. Therefore, in a memory such as an optical disk, as shown in FIG.
The information recording area 3 extends from the innermost circumference toward the outer circumference, and conversely, as shown in Figure 1, the information recording area 3 extends from the outermost circumference toward the inner circumference of the optical disc 1 and extends from the innermost circumference to the outer circumference. There is one that has a directory area 2. In such an optical disc, each time information is recorded, these two areas, the directory area 2 and the information recording area 3, extend from the outermost circumference and the innermost circumference of the optical disk 1 toward the center. When these two areas touch, recording on this optical disc 1 becomes impossible, and the unusable area of the optical disc 1 becomes minimum.

Furthermore, in order to record and reproduce digital information, it is essential that the memory area, directory area 2 and information recording area 3 have a sector structure. FIG. 2 shows an example of the sector structure of an optical disc. In Figure 2, 4 is sector, 6
is an address section, and 6 is an information recording section. In this example, when one track corresponds to one circumference of the optical disk, one -track is composed of n sectors 4. The sector 4 consists of an address section 5 in which address information of the sector is recorded when the optical disc is manufactured, and an information recording section 6 that is recorded and reproduced by an information recording/reproducing device when the optical disc is used. Therefore, the entire memory area of an optical disc for recording and reproduction has a sector structure.

In a read-only optical disk, the signal recording format is as shown in ai or b in FIG. 1, but the capacity of recorded information does not necessarily correspond to the recording on one optical disk.

Since the outermost and innermost peripheries of the optical disc in FIG. 1 are determined by the operating range of the optical head of the optical disc device, a blank space occurs between the directory area and the information recording area in a read-only optical disc. In an optical disc that has an optically detectable guide trunk, if the guide track is not provided in the blank area as described above, the cost of creating the original disc during optical disc manufacturing is reduced, but the optical disc when starting up the optical disc device is When the head is located in a blank area, tracking and focusing problems may occur, and when the optical head moves between the directory area and the information recording area, track crossings cannot be counted, causing problems in moving the optical head. occurs. In addition, if a guide track with a sector structure is provided in the blank area in the same way as in an optical disk for recording and playback, track crossing that occurs when the optical head crosses the address area when moving, which is a problem also in optical disks for recording and playback. A problem arises in which counting becomes unstable. In read-only optical discs, the addition of unstable elements due to unnecessary blank spaces is a problem that must be avoided.

OBJECTS OF THE INVENTION The present invention is intended to solve the problems associated with the signal recording format of a playback-only optical disc that is compatible with the signal recording format of the conventional optical disc for recording and playback, and to solve the problem when starting up an optical disc device. It is an object of the present invention to provide a read-only optical disc that solves problems when transporting an optical head and enables higher-speed information reading.

Structure of the Invention The present invention provides a read-only optical disc having an optically detectable guide trunk, by providing a guide track without a sector structure in the blank space between the directory area and the information recording area. The optical head can quickly track the guide trunk when the disk device is started up, and it is also possible to reduce the number of errors in counting when the optical head crosses a track in a blank area when moving the optical head.

Description of examples The present invention will now be described in detail.

FIG. 3 is a diagram showing a signal recording form of a read-only optical disc in an embodiment of the present invention. In Figure 3, 1
is an optical disc, 7 is a recording area (1), 8 is a recording area (I
I), 9 is a blank space. Recording area (I) 7 and recording area (■) 8 in FIG. 3 correspond to a and b in FIG. It has a sector structure as shown in Figure 2. Then, record area (I) 7 and record area (■
) 8, a blank space 9 is created between them. The invention particularly relates to this blank space 9 and will be explained below. FIG. 4 is a diagram showing a signal recording format for each track in the first embodiment of the present invention. 5 is an address section, 6 is an information recording section,
10 is a track of recording area (I) 7, 11 is a trunk of blank area 9, and 12 is a track of recording area (■) 8.

Information is written to tracks 10 and 12 in recording area (1) 7 and recording area (■) 8 during optical disk manufacturing.
This information is stored in the address section 6 and the information recording section 6.
It has a sector structure consisting of:

The track 11 in the blank area 9 is only a guide trunk and has no sector structure. The tracks 11 in the blank area 9 are formed at the same pitch as the tracks 10.12 in the recording area (■) 7 and the recording area (■) 8, so that when the optical disk device is started, the optical head is placed above the blank area 9. Tracking and focusing can be performed even when the movement of the optical head settles into a steady state. ! In addition, when the optical head moves between the recording area (I) 7 and the recording area (■) 8, it is more accurate because there is no low recording area that would cause errors in the counting of track crossings of the optical head. The transfer becomes smoother. The effect of the signal recording mode described in the first embodiment of the present invention does not change even if the shape of the guide track is spiral or concentric. However, the first embodiment has a drawback in that the position of the optical head is not known when the optical disk device is started up. This drawback can be overcome by the second embodiment described below.

FIG. 5 is a diagram showing a signal recording form for each track in the blank area 9 in the second embodiment of the present invention. In FIG. 5, 11 is a track of the blank area 9, and 13 is a track address area. In FIG. 6, a track address section 13 for specifying the track address of the track 11 in the blank area 9 of FIG. 4 is added every prescribed lap, that is, every three laps in this embodiment. This embodiment is effective for optical discs in which the guide track has a spiral shape. That is, after starting up the optical disk device, the position of the optical head can be known in at least three rotations. If the guide tracks are concentric, a similar effect can be expected by providing one track address section 13 for each station, that is, one track. Note that if the track address section 13 is provided in the blank section 9 in this way, the light beam will pass between the bits forming this track address section, causing an error in counting the number of track crossings of the optical head. This ratio is smaller than when the section 9 has a sector structure in which one track has a plurality of sectors, such as the recording area (I) 7 and the recording area (■) 8. In addition, in the first and second embodiments of the present invention, empty trunks having a sector structure are provided at both ends of the blank space 9 to cover the maximum counting error of the optical head across the track. Even if the optical head is located in the middle of the blank area 9 due to an error, that position becomes an empty track with the sector structure described above, and the track address can be detected, so the speed of track access by the optical head can be increased. Effects of the Invention The present invention provides a signal recording format for a blank area in a playback-only optical disc in which a directory area, a blank area, and an information recording area are arranged in the outermost or innermost area in this order, in which nothing is recorded in the blank area. By providing a free guide track, it is possible to stabilize the tracking and force nosing of the optical head when the optical disk device is started up, and to make the counting of trunk crossings when the optical head is moved more accurate. Furthermore, by providing a trunk address section on the guide track in the blank area at every prescribed circumference, the position of the optical head can be easily determined when starting up the optical disk device. As described above, the read-only optical disk of the present invention is compatible with conventional optical disks for recording and playback, and enables higher-speed access, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical disc for recording and reproduction, and FIG. 2 is a format diagram showing an example of the sector structure of an optical disc.
FIG. 3 is an explanatory diagram of the signal recording format of a read-only optical disc in one embodiment of the present invention, FIG. 4 is a format diagram showing the signal recording format for each track in the first embodiment of the present invention, and FIG. 5 2 is a formant diagram showing a signal recording format for each track in a blank area according to a second embodiment of the present invention. FIG. 1... Optical disc, 2... Directory area, 3... Information recording area, 4...
Sector, 6...address section, 6...information recording section, 7...recording area (I), 8...
...Recording area (It), 9...Blank area, 10,
11゜12...Truck, 13...Trunk address section. Part 1 Figure 3!

Claims (2)

[Claims] (1) An optically detectable guide track, a directory area provided along the guide track from the outermost circumference (or innermost circumference) toward the inner circumference (or outer circumference), and a directory area provided along the guide track from the outermost circumference (or innermost circumference) to the inner circumference (or outer circumference); has an information recording area provided from the innermost circumference (or outermost circumference) to the outer circumference (or inner circumference), and has a sector structure in which the directory area and the information recording area are divided into a plurality of parts; Each of the sectors is composed of an address section for specifying the address of the sector and an information recording section, and a guide track in which no information is recorded is provided between the IJ area and the information recording area. A playback-only optical disc with special features. (2) A read-only optical disc according to claim 1, which is provided with a track address section for specifying the track address of a guide track provided between the directory area and the information recording area every predetermined lap. .