JPH0242636A - optical disc media - Google Patents

Abstract

PURPOSE:To obtain a correct tracking signal and to execute a tracking control by cutting one part of a groove at every prescribed interval, making it into a total reflecting surface, utilizing the total reflecting surface and correcting an offset. CONSTITUTION:A disk 76 is composed of a guide track 62 to guide a light spot recording and reproducing information and a sector mark part 64 to generate a timing detecting a total reflected area 63. The total reflecting surface to function as an offset detected area is provided. Namely, a part of a groove 6 is cut at every prescribed interval, and the cut part is made into the total reflecting surface. By using the disk 76, the offset is detected from a reflect light when the offset detected area is irradiated with a light beam, the tracking signal is corrected based on the offset, the irradiated position with the light beam is tracking-controlled based on the tracking signal, and simultaneously, the information is recorded and reproduced. Thus, without being inflenced by the inclination of the disk, the tracking control can be correctly executed, and simultaneously, the information can be recorded and reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information recording and reproducing device for recording and reproducing information on an optical disk, and in particular, an optical information recording and reproducing device that records and reproduces information on an optical disk. The present invention relates to an information recording and reproducing method for recording and reproducing information while guiding a light beam spot, an optical disk used in the method, and an optical information recording and reproducing apparatus.

Conventionally, for example, in an optical disk that stores digital information in a form that can be optically recorded and reproduced, a groove for guiding a light beam spot is provided on the optical disk in advance, and the light beam is guided by relying on this groove when recording information. Optical disk devices capable of additional recording that record information while guiding spots have been proposed (for example, Pre
ssinformation Ph1lips Nov
, 7th 1978 or JP-A-54-130102
(see issue).

In order to guide the light beam spot, the diffracted light from the optical disk is received by two photodetectors placed parallel to the track, and by differentially outputting the respective outputs, the light beam spot and the light beam spot are guided. Some devices obtain a tracking signal that indicates the deviation from the groove. However, since the photodetector is located in the far-field region of the diffracted light, if the optical beam is swung or the disk is tilted, an offset will occur in the tracking signal, making it impossible to track the track properly.

FIG. 1 is a diagram illustrating the principle that an offset occurs in a tracking signal due to spot movement on a photodetector surface in a tracking signal detection device using diffracted light. Figure 1(a) shows a photodetector (having light-receiving surfaces 1 and 2)
FIG. 1(b) is a plan view of the spot position at the top.
It is a sectional view corresponding to the center line of A', and shows the intensity distribution of a light spot. FIG. 1(c) is a sectional view showing the intensity distribution of a light spot focused by an objective lens on the disk surface and the positional relationship of the groove, corresponding to the spot on the photodetector. In the case of (a) in Fig. 1(c), the center 7 of the light spot is located at a place where there is no groove on the disc surface, and in the case of (b) in Fig. 1(c), the center 7 of the optical spot is located at the center 8 of the groove. In the case of (c) in Fig. 1(c), the light spot is at the left end of the groove (or on the inside of the rotation of the disk), and in the case of (c) in Fig. 3(c),
Case d) indicates the case at the left end of the groove (or at the outer side of the rotation of the disk). In Figure 1, the spot 4 on the photodetector indicated by the dotted line is caused by moving the optical axis of the objective lens to follow the tilt or eccentricity of the disk with respect to the optical axis of the objective lens. It is.

In Figure 1, the photodetector has two parts 1 and 2 with light receiving surfaces.
It is divided into two, and the intervals between them are very narrow.

When the spot on the disk surface is at the center of the groove 6, the spot on the photodetector surface is as shown in FIG. The amount of diffracted light is incident. However, in this state, if the spot position on the photodetector surface moves due to the inclination of the disk or the movement of the objective lens, it will become as shown by dotted line 4.

A tracking signal based on diffracted light usually uses a differential signal output from the light receiving sections 1 and 2 as a tracking signal to detect an imbalance in the diffracted light.

Then, when the spot position on the photodetector surface moves as described above, even though the spot center 7 on the disk surface coincides with the center 8 of the groove 6, the differential between the light receiving sections 1 and 2 The signal will not become zero, and an offset will occur as a tracking signal.

Furthermore, in the case of (c) in FIG. 1(c) where the center 7 of the spot on the disk surface is at the left end of the groove 6, the intensity distribution of the spot on the photodetector surface is ), the amount of light incident on the light receiving section 1 increases, and the amount of light entering the light receiving section 1 and 2 increases.
An unbalance occurs in the differential output of the disc, and the amount and direction of deviation between the spot center and the track center on the disk surface can be determined.

In addition, when the spot center on the disk surface is at the right end of the groove as shown in (d) of Fig. 1('c), the intensity distribution of the spot on the photodetector surface is as shown in Fig. 1(b). d), and the differential output of the light receiving sections 1 and 2 is the opposite of that in case (c) of FIG. 1(C).

The present invention has been made to solve the above problems, and when recording and reproducing information while controlling tracking by detecting the unbalance of diffracted light due to the guide groove, it is necessary to detect the inclination of the disk and the light of the objective lens. It is an object of the present invention to provide an information recording and reproducing method that enables accurate tracking control by correcting the offset of a tracking signal due to axis movement, an optical disk used in the method, and an optical information recording and reproducing apparatus.

In the present invention, a part of the groove for guiding the irradiated light beam spot along the rotational direction is cut at predetermined intervals to form a total reflection surface, that is, a mirror surface area that reflects the light beam spot almost as it is, The feature is that the offset is corrected using this total reflection surface. In other words, only the offset component of the track signal appears on the total reflection surface, and it functions as an offset detection area, so the offset component is detected from this total reflection surface and held, and the tracking signal due to the diffracted light from the guide groove is corrected to ensure accuracy. A tracking signal is obtained to perform tracking control.

The present invention will be explained in detail with reference to FIG. Figure 2 shows the light receiving sections 1 and 2 when the spot center 7 on the disk surface passes through 1d6 from the left end to the right end and shifts the spot position on the photodetector surface by the amount of deviation Δ. This shows the change in the differential output 15. Point 10 indicates the case where the spot center 7 on the disk surface is at the left end of the groove 6, and point 11 indicates the case where the spot center 7 is at the right end of the groove 6. , sunspot 1
2 shows the case where the spot center 7 is located at the center of the groove 6.

A solid line 14 connects the black dots 12, and when 4 is viewed as a tracking signal, it represents the relationship between spot movement and offset on the photodetector surface.

On the other hand, the one-dot line 13 indicates the case (a) in Figures 1 (a) to (c), that is, the spot on the disk surface is on the total reflection surface without grooves, and the spot on the photodetector surface is only Δ. It shows the differential output of light receiving sections 1 and 2 when they are moved.

As is clear from FIG. 2, when the amount of movement Δ of the spot on the photodetector surface is small, the ratio of the amount of deviation between the dotted line 13 and the actual #114 to the amplitude of the differential output ]-5 is small; The value of the dotted line 13 may be substituted for the solid line 14. Dotted line 13
Since the output is the differential output of the light receiving parts 1 and 2 on the total reflection surface, a total reflection surface is provided in a part of the groove, and the value of the differential output 13 when the light spot passes through the total reflection surface is By extracting the value, detecting the offset, and correcting the differential output using this value, it is possible to obtain an accurate tracking signal without offset, unaffected by the tilt of the disk or the movement of the optical axis of the objective lens. .

FIG. 3 is a diagram schematically showing a main part of an embodiment of an optical disc of the present invention provided with a total reflection surface functioning as an offset detection area.

In FIG. 3, a portion of the groove 6 is cut and the cut portion is used as a total reflection surface. Figure 3(a) is a plan view, and Figure 3(b) is a cross section taken along line B-B'.
It is. The cut portion is flat without grooves 6, and its length Q is preferably such that when the spot 20 is at the cut portion, it is not affected by the surrounding grooves 6. For example, it is larger than or equal to the used spot size (the diameter at which the spot intensity is 1/e2).

The depth h of the groove 6 is preferably λ/8 (λ is the wavelength of the laser beam used) in terms of optical path length, but it may be deviated from this depending on other conditions. Of course, the invention is not limited.

FIG. 4 is a plan view showing an example of a track configuration of an optical disk capable of additional recording according to the present invention.

For example, the usage area of the disk is an area with an outermost circumference of 280φ and an innermost circumference of 180φ, and there are 32,000 tracks at a pitch of 1.6 μm in a radial direction of 50 mm, that is, a light spot is guided along the rotation direction. Concentric or spiral grooves are provided in advance for this purpose.

- The track of a book is divided into 64 sections in the circumferential direction, and each track is divided into 64 pieces of information called sectors. In Figure 4, one track has sectors 30°31.
32, 33, 34, 35, 36, 37, old, etc., and the more detailed structure of the sector 34, for example, is as shown in FIG. That is, each sector has a mark (
There is a circuit (usually PLL (Phase Loc)) that generates a clock to detect the primary address information (track number and sector number).
There is a signal 41 for activating (using a ked Loop), and then there is address information 42. The above three signals are recorded in advance. Next, a gap 43 is prepared in front of the additional recording area 44. This is to allow time for the information signal to be detected and to start recording, so that it is not effectively recorded.

An area 45 indicated by a dotted line is a buffer area, where rotational fluctuations,
It has the role of absorbing increases in recording area due to causes such as Glock jitter.

In the above-mentioned additionally recordable optical disc, the above-mentioned total reflection surface is preferably inserted in an area where no additional recording will be performed, and preferably in the gap 43 or the buffer 45 area.

That is, a part of the guide groove 6 provided concentrically or spirally along the track is cut by the area A of the cap 43 or the buffer 45, and a total reflection surface functioning as an offset detection area is formed at predetermined intervals. establish. The length Q is such a length that the light spot is not affected by the surrounding grooves when it is at the cut portion, as described above, and is equal to or larger than the light spot size.

According to the present invention, the sector structure described above is not required, and any area may be used as long as no special problem arises in data processing.

Next, a method for detecting the total reflection surface that functions as the offset detection area described above will be described.

The first method is to detect the offset in real time. First, it is necessary to know that the light spot is located at the total reflection surface. In the case of an optical disc that allows additional recording, the time interval from the sector mark to the area where the total reflection surface is inserted is known in advance, so first, the sector mark is detected, and then the time is measured to determine the area of the total reflection surface. It is only necessary to detect that a light spot has arrived.

According to the method described above, the offset can be detected and held by sampling and holding the differential output of the photodetector at the timing detected by the method described above.

Note that when using a method that involves a time delay in detecting that the light spot is on the total reflection surface, the differential output of the photodetector may be analog-delayed by the above-mentioned time delay. As an analog delay method, CCD (
Corge CogpledDevice) or a delay line.

FIG. 6 is a diagram showing the configuration of an embodiment of the present invention.

In the figure, the light beam emitted from the laser 71 is transmitted through the lens 72.
, it becomes parallel light, and the prism 73°λ/4 plate 74 (λ
: laser wavelength), passes through a focusing lens 75 and converges into a spot of about 1 μmφ on a disk 76 having a guide track. A reflective film or a recording film is deposited on the disk 76, and the light beam incident on the guide track 77 is reflected and passes through the aperture lens 75. λ/4 plate 74
, and are guided to the information detection system through the prism 73. The information detection system (the automatic focus detection system is not shown) consists of a focusing lens 78 and a photodetector 79 whose light receiving surface is divided into two for detecting tracking signals and information signals. As shown in FIG. 7, the disk 76 has guide tracks 62. It is composed of a sector mark section 64 that generates the timing for detecting the total reflection area 63. The guide track 62 has a groove with a depth of about λ/8, and as explained in FIG. 1, the distribution of reflected diffracted light changes depending on the positional relationship of the incident spot with respect to the guide track 62. A tracking signal is obtained by receiving light with a split photodetector 79 and differentially converting each signal with a differential amplifier 80. FIG. 8 shows the output waveforms from each circuit. FIG. 8(a) shows a normal track signal when the disk is not tilted. The portion showing a flat level in the signal indicates when the spot passes through the total internal reflection region. Next, the track signal when the disc tilts is shown in Figure 8 (
Shown in b). At this time, the optical axis of one reflected light moves due to the inclination of the disk, which causes an offset of Δ. For this reason, the track servo system tracks the electrical zero as the center of the track, resulting in track deviation. The tracking signal at this time has a waveform as shown in FIG. 8(c), and has an offset of Δ when passing through the total reflection region. When the output of the two-split photodetector 79 is summed by a summation amplifier 81, an information signal is obtained. In FIG. 9(d) of the information signal middle cylinder, attention is paid to the sector mark portion 64. This output is passed through a synchronization signal detector 82 to generate a gate signal for extracting the total reflection region 63 (shown in FIG. 8(e)). The gate signal is sent to the gate circuit 83
The signal in the total reflection region is extracted from the tracking signal. The output is led to a hold circuit 84, which holds the extracted signal and detects an offset signal (8th
(shown in figure (f)). This signal is differentially applied to the tracking signal by a differential amplifier 85, and a tracking signal with the offset due to the disk tilt corrected is obtained as the output of the differential amplifier 85.The signal is passed through a track servo circuit 86 and is used to drive a lens for track tracking. Drive device 87.

This allows accurate track tracking.

In the present invention, a case has been described in which track tracking is performed using a lens, but the same applies when track tracking is performed by swinging a beam with a mirror.

According to the present invention, it is possible to correct the offset in the tracking signal caused by the tilt of the disc, so that information can be recorded and reproduced while accurately controlling tracking without being affected by the tilt of the disc.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the principle of offset generation, Figure 2
The figure is a diagram for explaining changes in differential output from a photodetector, FIGS. 3 to 5 are diagrams for explaining the configuration of an optical disc according to the present invention, and FIG. The diagrams illustrating one embodiment, FIGS. 7 and 8, are diagrams for explaining its operation. 71... Laser, 72... Lens, 73... Prism, 74... λ/4 plate, 75... Stop lens, 76... Disk, 77... Guide groove, 78...・
Convergent lens, 79... Two-split photodetector, 80... Differential amplifier, 81... Harmonic amplifier, 82... Synchronous signal detection circuit, 83... Gate circuit, 84... Hold Circuit, 85...differential amplifier, 86...track servo circuit. 87... Lens immediate action device. Figure 1 Figure 3 Figure 4 Figure 2 Figure 55U

Claims (1)

[Scope of Claims] 1. A recordable optical disc having a recording film for recording in an optically readable form, having a groove for guiding an irradiated light beam along the rotational direction, One rotation of the groove is divided into a plurality of sectors, each sector has a first area in which a mark indicating the starting point of the sector is recorded in advance, and a second area in which the above information is recorded, A portion of the optical beam is cut at predetermined intervals to provide an offset detection area between the first area and the second area for detecting the offset of a tracking signal obtained from the diffracted light of the optical beam by the groove. irradiate the rotating optical disk with the light beam, detect a tracking signal from the diffracted light of the light beam by the groove, and detect when the light beam is irradiating the first area. A signal indicating the mark is extracted from the reflected light, a gate signal indicating the timing when the light beam is irradiating the offset detection area is generated based on the extracted signal, and the gate signal is used to control the light beam. detects an offset from the reflected light when the beam is irradiating the offset detection area, corrects the tracking signal based on the detected offset, and tracks the irradiation position of the light beam based on the corrected tracking signal. A method for recording and reproducing information characterized by recording and reproducing information under control. 2. The first aspect of the present invention is characterized in that a signal due to reflected light when the light beam is irradiating the offset detection area is sampled, and the sampled signal is held to detect the offset. How to record and play back the information described in section. 3. A recordable optical disc having a recording film that records information in an optically readable form, which has a groove for guiding the irradiated light beam along the rotational direction, and has a groove that guides the irradiated light beam along the rotational direction. is divided into a plurality of sectors, each sector has a first area in which a mark indicating the starting point of the sector is recorded in advance, and a second area in which the above information is recorded, and a part of the groove is divided into a predetermined area. An offset detection area is provided between the first area and the second area for detecting the offset of the tracking signal obtained from the diffracted light of the light beam by the groove. Characteristic optical disc. 4. The optical disc according to claim 3, wherein the offset detection area is comprised of a reflective surface that reflects the light beam almost as it is without being affected by the groove. 5. The optical disc according to claim 4, wherein the length of the reflective surface is equal to or longer than the spot diameter of the light beam. 6. Claims 3 to 5, characterized in that address information indicating the address of the sector and a synchronization signal for detecting the address information are recorded in advance in the first area. An optical disc described in any of the above. 7. A recordable optical disc having a recording film for recording information in an optically readable form, the disc having a groove for guiding an irradiated light beam along a rotational direction, wherein one revolution of the groove is divided into a plurality of sectors, each sector has a first area in which a mark indicating the starting point of the sector is recorded in advance, and a second area in which the above information is recorded, and a part of the groove is divided into a predetermined area. The first offset detection area is cut at intervals of
an optical system for irradiating the light beam onto the rotating optical disk provided between the region and the second region; a track deviation detection means for detecting a tracking signal from the diffracted light of the light beam by the groove; A gate that extracts a signal indicating the mark from the reflected light when the light beam is irradiating the first region and indicates a timing when the light beam is irradiating the offset detection region based on the extracted signal. a signal generating means for generating a signal; an offset detecting means for detecting an offset from reflected light when the light beam is irradiating the offset detection area with the light beam according to the gate signal; It has a correction means for correcting the tracking signal, and a tracking control means for tracking-controlling the irradiation position of the light beam based on the corrected tracking signal from the correction means, An optical information recording/reproducing device characterized by recording and reproducing information while tracking and controlling an irradiation position. 8. The offset detection means comprises means for sampling a signal caused by reflected light when the light beam is irradiating the offset detection area and holding the sampled signal. The optical information recording and reproducing device according to scope 7. 9. Claims 7 or 8, characterized in that address information indicating the address of the sector and a synchronization signal for detecting the address information are recorded in advance in the first area. The optical information recording/reproducing device described in . 10. Any one of claims 7 to 9, wherein the offset detection area is comprised of a reflective surface that reflects the light beam almost as it is without being affected by the groove. The optical information recording/reproducing device described in . 11. The optical information recording and reproducing apparatus according to claim 10, wherein the length of the reflecting surface is equal to or longer than the spot diameter of the light beam.