JPH0348578B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a record carrier for optical discs for recording and reproducing video signals, audio signals or digital information files. In such recording/reproduction, a video signal or an audio signal can be FM-modulated and converted into a rectangular wave signal that rises and falls at the zero cross point, thereby producing a signal similar to a digital signal. An example of such a conversion method is disclosed in Japanese Patent Application Laid-Open No. 1973
Since it is explained in detail in No.-65730, detailed explanation will be omitted here. As a method for recording and reproducing the binary information or digital information obtained in this way,
There is a method of optically recording on a disc-shaped rotating record carrier. Conceivable recording materials include metal materials, amorphous materials, color materials, etc., and recording can be performed using relatively low-output light sources such as gas lasers, solid-state lasers, and semiconductor lasers. For example, a light beam emitted from a semiconductor laser modulated by a recording signal is focused by a coupling lens to become a parallel light beam,
The light is incident on the objective lens, and the effect of the light energy enables binary recording onto a record carrier located at the focal plane of the objective lens. The recorded signal is divided into two parts: the exposed part and the unexposed part of the light.
It is a value signal. The signal can be read out by irradiating a light beam onto the signal, detecting the physical influence of the signal on the light beam with a photodetector, and demodulating the information signal. In order to perform such recording and reproduction at high density, it is necessary to irradiate a light beam onto the record carrier as a minute spot during recording and reproduction. For example, in commercially available optical video disks, the length of the signal element is about 0.56 microns to 2 microns, and the signal width is very fine, about 0.4 to 0.6 microns. In order to form such a signal element, it is necessary to make the light beam into a minute spot of approximately the same order, but in such a case, the tolerance for focal position error and track centering tolerance for the spot are extremely strict. Accuracy is required. For example, the focal position error tolerance is ±1.5 μm, and the track center ring tolerance is within ±0.1 to 0.2 μm. On the other hand, it may be necessary to add other information to a zone for recording and reproducing certain information on a record carrier for recording and reproducing. In such a case, when performing so-called add-on recording in which the record carrier is once removed from the apparatus and information is added again, it is necessary to make the record carrier exactly adjacent to the previously recorded information track. For this purpose, a groove is recorded as a guide for the track, and a recording material is coated on it, or a thin layer with a groove guide transparent to the light beam is formed on the recording material. It is effective to do so. Providing such an air groove guide is a very useful means for performing tracking servo to correct track errors, and it also reduces tracking errors by ±0.1 to 0.2.
It is easy to make it within microns. Another important aspect of add-on recording is identifying the specific track for a given recording. For this reason, an address code for identification has conventionally been recorded on a part of the truck. A conventional and common method of inserting address codes is to intermittently erase the grooves from part of the track when forming the grooves. The address code is reproduced by detecting the length of the lost portion or the length of the intermittent empty grooves.

Figure 1 shows one track of a conventional general record carrier containing an address code, where 1 is the record carrier substrate, 2 is the recording layer, 3 is the address code, and 4 is the track for recording information. The empty groove 5 is a recording signal element. Such address codes 3 and air grooves 4 can be formed by using substantially the same disc manufacturing process for optical video discs and compact discs. That is, the photoresist is placed on the glass master to a predetermined thickness (500 to 1500 Å).
It is coated and exposed to a light beam such as an argon laser to record the grooves. This method of recording address codes has two drawbacks as described below.

(1) Since the address code is included in a part of the track, when reproducing the address, it is necessary to reproduce one round of the track.

(2) Since the address is intermittently included on the track, when playing back the video signal or audio signal, the address part is cut off.

Further, the following disadvantages arise from the above two disadvantages. In other words, since the address part is included in a part of the track, the address signal can only be reproduced after one track revolution, so the reproduction time is at least one track revolution, for example, when the record carrier is at 1800 rpm. 33 if rotating
msec is required. This is a problem when performing address searches. Also, if the video signal or audio signal is interrupted because the address is intermittent on the track, the effect can be removed from the screen by inserting it between the blacking in the case of the video signal, but the audio signal Intermittent noise is mixed into the signal. As a countermeasure to this problem, it is necessary to compress the audio signal and record it, and to extend and reproduce the address part when reproducing it.

From the above, the desirable conditions for address signal recording are that as many address signals as possible must be recorded in a track in order to access the desired track at high speed, and the address signal must be recorded in a form that does not disrupt the recording/reproducing signal. It is desirable that the information be recorded.

The present invention has been made in order to deal with such conventional problems, and has a concentric or spiral continuous track provided in advance for recording and reproducing grayscale information. An object of the present invention is to provide a record carrier in which auxiliary information for recording and reproducing information is included in the entire track as changes in the depth direction of a substantially rectangular cross section.

Embodiments of the present invention will be described below based on the drawings. First, in the first embodiment shown in FIG. 2 and the second embodiment shown in FIG. 3, 11 is a record carrier substrate, 12 is a recording layer, and 13 is a concentric or spiral series on which auxiliary information signals are recorded. A track groove (empty groove) 14 having a substantially rectangular cross section is a signal element for recording and reproducing.

In both of these two embodiments, a track groove 13 is provided in the longitudinal direction of the track groove 13 in which the auxiliary information signal is recorded.
In the embodiment shown in FIG. 2, the cross-sectional area is changed, and in the embodiment shown in FIG. 3, the cross-sectional area is changed into a wave shape, and in the embodiment shown in FIG. In the drawings, the period of the auxiliary signal including the address signal is extremely exaggerated, and the period is approximately the same as that of the signal element for recording and reproduction.
The band of the auxiliary signal can be relatively low. For example, the signal band for recording and playback is several megahertz, and for NTSC color modulation, it is 3.5MHz to 13M.
Audio signal as Hz 2.2MHz±100KHz and 2.8MHz
If it is set to ±100KHz, the auxiliary signal can be input into a band of tens of kilohertz below 100KHz.
In this way, complete separation can be achieved in terms of bands, and since the amplitude is also small, it is possible to reduce noise components such as cross-modulation.

In the embodiment shown in FIG. 2, the auxiliary signal is recorded as a change in the thickness of the record carrier. When changing in the thickness direction, the signal depth is
Must be 0.1 micron or less. Also, one of the methods for forming an auxiliary signal such as the embodiment shown in FIG.
One example is the mechanical cutting method. Such a cutting method is, for example, a method in which a copper plate is cut with a diamond cutter mounted on an electrostrictive element.

In any of these embodiments, the track groove 13
The change in cross-sectional shape is within 5% of the average cross-sectional area.

The auxiliary signal of each embodiment formed in this way is a phase pattern, and if the recording/reproducing signal is formed as a gray pattern, the reproduced signal will be the sum of both, which has the advantage of being able to alleviate cross-modulation components. In other words, in the case of a phase pattern, the diffracted light beam generally shows a spatially anisotropic pattern, whereas in the case of a gradation pattern, the diffracted light beam shows a spatially isotropic pattern. It is known that By utilizing such physical changes, it is possible to improve the signal-to-noise ratio of the signal.

Note that the auxiliary information referred to in the present invention is not limited to simply information for recognizing a track, but may also be, for example, an audio signal used auxiliary or an independent information signal. An identification code for identifying the truck may then be included.

The optical disc record carrier of the present invention can be implemented as described above, and can solve the problems described in the conventional example at once, and can perform high-speed access and eliminate intermittent noise without interrupting the address signal. No contamination. In particular, by inputting an auxiliary signal such as an address signal in the form of a phase in the depth direction, it is possible to separate it from the information signal of the gray pattern, and it is possible to prevent the mixture of cross-modulation.

[Brief explanation of drawings]

FIG. 1 is an enlarged perspective view of a main part of a conventional record carrier, and FIGS. 2 and 3 are enlarged perspective views of main parts showing first and second embodiments of the present invention, respectively. 11...Record carrier substrate, 12...Recording layer, 13
...Track groove, 14...Signal element.

Claims (1)

[Scope of Claims] 1. It has concentric or spiral continuous tracks provided in advance for recording and reproducing grayscale information, and the entire continuous track is provided with a continuous track for recording and reproducing information. A record carrier for an optical disk that contains auxiliary information as changes in the depth direction of a substantially rectangular cross section. 2. The optical disc record carrier according to claim 1, wherein the track auxiliary information includes an identification code for identifying at least one track. 3. The optical disk record carrier according to claim 1, wherein the change in the cross-sectional shape of the track is within 5% of the average area of the cross-section.