JPS58169338A - Device for recording and reproducing timing information in optical disc - Google Patents

Abstract

PURPOSE:To make timing information usable by such constitution wherein the spot of a light beam for reproducing timing reproduces the timing information in precedence of the light spot of data and records light information. CONSTITUTION:The beams from two semiconductor lasers 31, 32 which are driven by electric power sources 51, 52 are condensed on the recording surface of a disc 11 with a lens 33, a polarizing prism 34, a lambda/435, and a lens 36, whereby a light spot 310 and a lead spot 320 preceding the same are formed. The timing information created on a track 10 is read by the spor 320 through a detector 38, and is conducted to a clock reproducing circuit, by which a clock is reproduced. The power intensity of the spot 310 is modulated by the reproduced clock and information is recorded on the track.

Description

[Detailed Description of the Invention] When recording data in an optical disk device, the rotational speed of the disk and the write clock always have a predetermined relationship Kff.
lf. In addition, the write clock must be sufficiently stable to ensure reliability of read data. One method that satisfies the above conditions is to build a sufficiently high-precision lock on all tracks on the disk, reproduce the clock with a read head, and use it as a write clock. However, if the structure of the optical head is such that not only read/write signal detection but also servo signal detection such as automatic focusing and tracking control is performed using a single optical spot (single spot method),
Since the write data signal is also read into the clock read signal, the write data affects the clock reproduction during writing as a very large disturbance on the clock reproduction. In order to reduce this influence, it is necessary to set special restrictions (such as not including a clock component in the data spectrum) as a modulation method for write data. Therefore, there is a drawback that the modulation method cannot be freely selected.

Furthermore, in the above method, since clock information is attached to the track, accurate tracking must be ensured in order to reproduce the clock. Another problem is that it cannot be operated without providing track information in advance.

The purpose of the present invention is to
An object of the present invention is to obtain a timing information recording and reproducing device for an optical disc that can use timing information built into the disc. A second object of the present invention is to provide a timing information recording and reproducing apparatus for a disc in which no tracks are prerecorded.

The basic configuration of the present invention is that a read light beam spot for tie-setting reproduction precedes a data light spot, and the preceding read spot reproduces timing information recorded on the disc to generate a write clock signal. death,
? : The write operation of the recording data is performed by the write block. Data reading is the same as in the conventional method. The optical spot for data reading may be provided separately or may be shared with the optical spot for timing reproduction.

The present invention will be explained in detail by way of examples below. FIG. 1 is a configuration diagram of the main parts related to reading and writing of the original disk device. The motor 2 is rotated by the la disk at a constant speed. 3 is a read/write optical head, 4 is a read circuit that processes a read signal from the head 3, 5 is a write signal processing circuit, 6 is a write clock regeneration circuit, 7 is a read data processing circuit, and 8 is a write data processing circuit. . FIG. 2 shows the IR of the disc 1, and track information 10 is recorded on the recording surface. There are several ways to create timing information on tracks 10.

For example, tracking a track is 1/81i of the wavelength λ of the moonlight laser spot! A groove is formed at the angle, where λ/
4 bits deep as a timing information point, λ7
It is possible to change the optical characteristics (reflectance, etc.) of the recording layer in place of 4 bits. Further, the above λ/8 track #I may be modulated with a timing signal. A conventionally known modulation method can be used for the modulation method.

FIG. 3 is a diagram showing the basic structure of the optical head 3. In the optical head according to the present invention, at least two semiconductor lasers 31
, 32Ytvl, are each independently driven by a current source of 51.52. 33, 36°, 39 are lenses, 34 is a deflection prism, 35 is a λ/4 wavelength plate, 38, 39 is a photodetector, and 11 is the recording surface of the disk. Laser light source 31.
9. 32 are placed a short distance apart. Therefore, since the angle of incidence on the lens 33 differs by a very small angle, the light spot is focused on a point on the recording surface of the disk that is separated by a very small distance. Light spots 310 and 329 correspond to laser light sources 31 and 32, respectively.

The above two light spots are arranged on the track as shown in figure jI4. Light spot 320 is for lead, 31
0 is for writing, and the rotational direction of the disk and the relationship between the above two spots are that read spot 320 is light spot 3.
It is placed before 10. The timing information built into the track 10 indicates the lead spot 32 that preceded it.
0 leads to a read clock recovery circuit and a clock reflected in the rotational state of the disk is recovered. This reproduction clock is used as the operating clock of the write signal processing circuit 5, and the power intensity of the light spot 31G is modulated according to the write information to record information on the track. lead spot 32
A specific example of detecting clock information placed on a track by 0 is shown in FIG. Reflected light from lead spot 320 is configured to return to photodetector 38 in FIG. The photodetector 38 includes two detectors 381 and 382.
The arrangement of these two detectors is such that the tracks 10 on the detectors are in front-to-back relationship, ie, the arrows in FIG. 5 are in the direction of the tracks. Output signals 383 and 384 from the two detectors are used in a differential amplifier 385 to calculate the difference between the two outputs. This difference signal 386 is used to reduce noise components using a tank circuit or the like tuned to the clock frequency built into the truck, and then performs clock regeneration using a PLL or the like (the above-mentioned tank circuit and PLL
(The structure itself is not shown because it can be realized by ordinary circuit means).

FIG. 6 is a diagram showing a disk structure according to a second embodiment of the present invention. Information is recorded along the track IO on the recording surface of the disk 1, but in the case of FIG. However, in the case of this embodiment, the grooves 12 are formed radially from the center of the disk at regular angular increments. Groove 1
2 is formed in such a shape that the cross section on the track surface is shown in Figure 7. The depth of the groove 12 may be approximately λ/10 to λ/several lO. The effect of a groove of about λ/several 10 on the data is minute, and the deterioration of the S/N of the data signal due to this is negligible. Since the above groove information is read by diffraction of the lead spot 320, the uneven structure of the groove 12 is the seventh
It is exactly the same even if the convex structure is used instead of the concave groove shown in the figure. j
In the method shown in FIG. 16, no timing information is written on the track, so no tracking control is required for the reproduction of a single track. This point is markedly different from the case shown in FIG. 2, and can be applied to discs in which track information is not previously created.

In FIG. 6, the grooves 12 must be formed with high precision over the entire surface of the disk at minute, constant angular increments. Creating grooves with high precision and uniformity over the entire surface of the disk requires extremely high precision equipment.

However, data is recorded on the disk in fixed recording units.
For example, it is executed in units of sectors.

Since the number of sectors is several tens or more for each track (for example, divided into sectors of one track t64), the recording accuracy of the above-mentioned timing information groove can be guaranteed in units of sectors. That is, in Figure 6.

12-1, 12-2. If a sector is represented by =, 12-n, $112 for each sector may be created with a certain precision, and there is no practical problem even if there is discontinuity at the sector switching point. Therefore, it is possible to create a groove for one sector with the necessary precision and reproduce it by shifting the angle by one sector. This is because a disk medium is characterized in that it can be reproduced in a form in which the timing information and the like are recorded.

By reproducing a master disc made by the above method, a disc of this type can be easily obtained.

As described above, according to the present invention, timing information built into a disc can be reproduced without being affected by write data. As a result, there are no restrictions on the modulation method for recorded information, and any modulation method can be selected. Furthermore, if the disc has the structure shown in Figure 6, tracking control is not required for tying playback, and the invention can be applied to discs in which track information is not written in advance. Moreover, in this case, there is no restriction on arranging the preceding read spots and light spots on a track, which has the advantage of facilitating adjustment of the optical head. This feature is very effective in practice since the alignment accuracy of the two spots is approximately α1 μm, which requires extremely high precision adjustment.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing the main parts related to read/write (read/write) K of the original disc device, Fig. 2 is a diagram showing the disc medium in the present invention, Fig. 3 is a diagram showing an embodiment of the optical head, and Fig. 4 is a disc A diagram showing the relationship between two original spots on the recording surface and a track, FIG. 5 is a diagram showing an embodiment of a timing signal detector based on a return source from a lead spot, and FIG. 6 is a diagram showing a second implementation of the disk structure. An example figure, Figure 7, is the same as Figure 6! i1 Mouth'fJz diagram 'g3 diagram'fJ 6 diagram

Claims (1)

[Claims] 1. Timing information is created in advance on the recording surface of the optical disc by minute irregularities or shading, and the light spot for recording information is also used as a read source for detecting the timing information in advance. Timing information in an optical disc, characterized in that a light spot is arranged and light information is recorded by modulating the intensity of the light spot according to a timing signal reproduced from a detection signal from the lead spot. Recording and playback device.