JPH0250535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical disk which is a disk-shaped record carrier used in an optical recording/reproducing device such as a video disk.

When generating information from an optical disk, it is necessary to search for a track on which the desired information is recorded. Conventionally, in order to search for such a track, each information track is provided with an address signal, or the number of tracks crossed by a light beam during the search is counted to find the required track. However, as the recording density of a single optical disk increases and reaches tens of thousands of tracks, a large number of types of information from different fields can be recorded on a single optical disk. If such various types of information were recorded on a single optical disk in continuous tracks, that is, at equal track pitches, the search device for searching for the track containing the necessary information would become complicated, and the search speed would be reduced. is delayed. This is because each track must contain an address signal corresponding to the field of information, and the address signal must be reproduced for each track during a search.
Moreover, the search speed becomes slower. However, if the recording density of optical disks increases dramatically in the future, it is quite conceivable that various different signals, such as digital data signals, audio signals, and video signals, will be recorded and reproduced on a single optical disk.

Conventionally, when handling data recorded in different fields or recording information using different signal systems, the optical disk was replaced each time. However, if the recording density is improved as described above, there is no need to replace the disk, and all information can be recorded on a single disk. By the way, when recording such various types of information, it is rare to record information in all fields at once. The normal usage is to add and record new information one after another. If various types of information are recorded sequentially from the outer or inner tracks of the optical disk in the order in which the information is obtained, the search for reproducing the required information becomes complicated, as described above. .

In order to eliminate this drawback, the tracks on the optical disk are divided into several groups and the field of information to be recorded in each group is determined. The areas between the groups have a different shape change or optical characteristic change than the area of the information recording track. For example, it can be identified by providing an unrecorded portion with no tracks. Furthermore, by utilizing changes in the shape of the disk, for example in the form of tracks, or changes in the optical properties of the photosensitive material coated on the disk surface, a droplet index is placed between the groups. By doing this, it is possible to first search for the field (group) to which the required information belongs from among the huge amount of records on various disks using the above-mentioned index, and then search the tracks within the group using the address signals of each track. You can search by reading. By recording such tracks in groups, information can be recorded and organized on the optical disk, and searches on the disk can be performed easily and at high speed.

Next, we will discuss specific uses of the optical disk in which the tracks are divided into several groups in this manner.
Just as we store various documents in files by field, we divide information recording tracks into groups on optical disks by field. By inserting an index indicating a field between groups, an easily searchable document disk file is constructed. If there are additional documents,
All you have to do is search for a group in the relevant field and record it after the last recording track in that group.

In addition, such group recording is also useful when a plurality of programs of moving images such as movies are recorded on a single optical disk in the case of a video disk. By using the intergroup index, you can quickly search for the beginning of the program you want to see.

Furthermore, educational equipment using video and audio can also be constructed using optical disks. For example, in the first group, an instructional program is recorded, and in the next group, there is an unrecorded section in which the user learns and records according to the program recorded in the previous group. In this way, by creating groups in which the user can write freely and groups in which teaching programs are recorded in advance alternately, it is possible to construct an optical recording and reproducing device that is highly effective in teaching.

The present invention proposes an optical disk that can achieve the above object, and one embodiment thereof will be described below with reference to the drawings.

FIG. 1 is a block diagram of an optical disc search device that searches for an optical disc on which group recording has been performed as described above. A light beam emitted from a light source 1 such as a semiconductor laser is focused by an aperture lens 3 onto a track on an optical disk 2 as a light spot. Reflected light is obtained in response to optical changes on the disk, and is separated into light beams in a tracking direction 5 and a focusing direction 6 by an optical wedge 4. The separated light beams are received by two-split photodetectors 7a and 7b and input to differential amplifiers 21a and 21b, which output focusing error signals 8 and tracking error signals 9, respectively. Focusing error signal 8
is added to the voice coil 10 that drives the aperture lens 3 to control the focusing point. The tracking error signal 9 drives the mirror 11 to accurately track the track on the optical disk 2. Further, the tracking error signal 9 is passed through a signal processing circuit 12 to a linear motor 14 that moves a disk motor 13 rotating the optical disk 2 in the disk radial direction.
added to. This linear motor 14 is used to search groups on the optical disk 2 and tracks within the groups.

Next, one embodiment of the structure of the optical disk of the present invention will be described based on FIG. 2. FIG. 2a is a partial plan view of an optical disk 2 in which recorded information tracks 15 are divided into several groups and unrecorded portions 16 are provided between each group. FIG. 2b is a sectional view taken along the line AA in FIG. 2a. The information recording track area (group) 15 is one in which information is recorded as pits in the form of grooves, or a photosensitive recording material is coated on the optical disk 2, and the area is exposed to light by being projected with a light spot and the reflectance of the recording material is increased. It may also be a track in which information is recorded as pits depending on changes. Alternatively, a disc structure in which the optical disc 2 coated with the recording material is provided with groove-shaped guide tracks is also possible. The tracking error signal 9 indicates that the optical spot is being tracked (Fig. 7b).
It is obtained from the signal waveform when crossing , as shown in Fig. 7c. When a light spot crosses between groups 16 where there is no track, a track crossing signal as shown in FIG. Can be done. Signal processing circuit 1 of Yotsute search device
2 can be easily constructed. In other words, it is sufficient to count the time during which there is no track crossing signal, and if the time is longer than a certain value, it can be determined that it is between groups.

FIG. 3a shows an embodiment in which an index is placed between groups 16. As in FIG. 2, a portion without an information recording track is provided between the groups 16, and an index track 17 is provided in a portion of the group 16. FIG. 3b is a sectional view taken along the line AA in FIG. 3a. The search for the inter-group 16 in this case is the same as in the case of FIG. 2, and it is sufficient to detect a portion where there is no track crossing signal. Furthermore, in this case, if the group gap 16 is detected, the linear motor 14 is stopped and the index track 1
Tracking control is applied to 7. Then, by reproducing the addresses and the like of the index track 17, it is possible to identify the fields recorded in the following group or the fields of information to be recorded.

FIG. 4a also shows another embodiment in which an index is inserted between groups 16. FIG. 4b is a sectional view taken along the line AA in FIG. 4a. In this case, as shown in FIG. 3, the index track 17 is not tracked and reproduced in the circumferential direction, but the light spot simply traverses the track crossing index 18, and the recording that continues between the groups 16 is created. Fields recorded in the information track group 15 or fields to be recorded can be identified. In this way, the light spot can be identified simply by crossing the index, making high-speed searching easy. The structure of the track crossing index 18 is such that tracks with the same track pitch as the recorded information tracks 15 are provided between groups 16, and the number of the tracks is made to correspond to the index number of the recorded information track group 15 that follows. The search method is the same as in Figure 3, with 16 between groups.
By searching for the field and counting the number of tracks in the track crossing index 18 provided between the groups 16, the field of the group 15 that follows it can be identified.

FIG. 5a shows another embodiment in which the index is encoded to increase the amount of information in the cross-track index. Figure 5b is A-A in Figure 5a.
A cross-sectional view is shown. In this case, the index is provided with tracks having different track pitches between groups 16, and by changing the pitch, encoding is performed in the track cross direction. In the example shown in FIG. 5, a PE code (phase encoding) 20 is used to construct the track crossing index 19.
The rising and falling edges of the pulse of the PE code 20 are made to correspond to the index track. In this way, the track crossing index 1
By coding 9 by changing the track pitch, the amount of information in the index can be increased, and the field being recorded or the field to be recorded in the subsequent recorded information track group 15 can be identified simply by the light spot crossing the index. It is possible to search quickly and easily.

FIG. 6 shows an embodiment of a signal processing circuit (corresponding to 12 in FIG. 1) for decoding the track crossing index 19 shown in FIG. Figure 7 is the 6th
3 shows signal waveforms of each portion a to h in the signal processing circuit of FIGS. a to h; FIG. FIG. 7b, like FIG. 5b, shows a radial section through the track transverse index. The track pitches of the track crossing index in FIG. 7b correspond to the rising and falling edges of the PE code (corresponding to FIG. 7a) as described above. When the light spot crosses the track crossing index 19 (FIG. 7b) during the search, the tracking error signal of the two-split photodetector 7 takes on a waveform having a peak at the edge of the track groove, as shown in FIG. 7c. The output of the differential amplifier 21b is input to a low-pass filter 22, which reduces high frequency components due to noise on the optical disk, etc., and detects only the positive peak of the tracking error signal (FIG. 7c) by the peak detector 2.
3 (Fig. 7d). This peak pulse (FIG. 7d) is input to the T-type flip-flop 24, which outputs a PE code (FIG. 7a).

The following configuration is for PE code circle decoding. The mono-multivibrators 25, 26, and 27 are triggered one after another by the peak pulse (FIG. 7d), and the regenerated clock for PE code decoding (FIG. 7g) is regenerated. 7e shows the output waveform of the mono multivibrator 25, and FIG. 7f shows the output waveform of the mono multivibrator 26. The regenerated clock (Fig. 7g) triggers the D-type flip-flop 28, converting the PE code into a serial binary code (Fig. 7h).
It is decrypted to Furthermore, this binary code is input to the shift register 29 and output as a parallel binary code.
The thus reproduced index is compared by the comparator 30 with the index previously set by the user in the data control 31, and the linear motor control circuit 32 is driven to perform a search. In this way, when a PE code is used as a track crossing index, the clock can be reproduced from the code itself, so it is possible to reproduce the index with a stable and simple decoding circuit without being affected by the track crossing speed of the search linear motor 14. can.

As explained above, according to the present invention, it is possible to easily organize information by field on a disk, and by providing an index between groups, groups containing the required information field can be quickly and easily organized. You can search using a simple search device. Furthermore, by using this index as a track-crossing index, the information in the index can be reproduced simply by the light spot crossing the track-crossing index in the radial direction, without stopping the search linear motor and reproducing the track in the circumferential direction. It is possible to provide an optical disk retrieval device that can quickly identify the contents between groups and retrieve a necessary track, and that is faster and has a simpler configuration.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of the optical disk search device, Figure 2
Figures a and b are a partial plan view and a cross-sectional view showing an embodiment of an optical disk that performs group recording according to the present invention;
Figures a, b to 5 a, b are partial plan views and sectional views showing other embodiments in which the optical disk of the present invention is provided with an inter-group index, and Figure 6 is a diagram showing a signal processing circuit for index reproduction. A block diagram showing one embodiment, FIG. 7 is a signal waveform diagram of each part in FIG. 6. 2...Optical disk, 7...2-split photodetector, 12
...Signal processing circuit, 14...Linear motor, 15...Information recording track (group), 16... Between groups, 17... Index track, 18, 19... Track crossing index, 20... PE code.

Claims (1)

[Claims] 1. In an optical disk that optically records information in the form of concentric or spiral tracks,
The tracks on the disk are divided into several groups, the disk shape or optical characteristics are changed between at least successive groups, and at least the group numbers assigned to the successive groups or the group contents are assigned between the groups. Equipped with an index that allows identification,
An optical disk characterized in that the index is composed of a plurality of track groups provided between the groups, and the index information is reproduced by a light beam crossing the tracks in a radial direction.