JPH10340457A - Optical disk and its recording and reproducing device - Google Patents

Abstract

(57) Abstract: An optical disk for recording data at a high density on both a disk in which a land data recording area and a groove data recording area are alternately arranged in both the radial direction and the track direction, and the optical disk. Provided is a recording / reproducing device. SOLUTION: A land area and a groove area are alternately arranged in a range of 200 to 4000 per round of a track.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk and a recording / reproducing apparatus for the optical disk.

[0002]

2. Description of the Related Art At present, as a method of recording information in an optical disk apparatus, a guide track is formed on a disk as approximately 1 /.
A concave linear groove (referred to as a groove track) having a depth of 8 wavelengths is usually formed spirally at a track pitch of 1.6 μm, and data to be recorded is recorded on the concave groove or on the convex groove. Was recorded on one of the tracks. In recording, information is recorded on a track while condensing a laser beam on a small spot, optically detecting the center of the track, and causing the light spot to follow the track by an actuator. As a recording material, a write-once medium such as As-Te-Se, a magnetic recording medium such as Tb-Fe-Co, and a phase change recording medium such as Ge-Sb-Te are used. To reproduce the signal on the track recorded in this way,
The laser beam is focused on a small spot with a low output, and the data is reproduced while optically tracking the track.
More recently, in order to increase the recording capacity of the optical disk, the track density is doubled by recording on both tracks of the convex land portions L6 and L7 and the concave groove portions G6 and G7 as shown in FIG. A so-called land / groove recording method is considered. Regarding this land / groove recording, for example, reference Miyagawa,
Y. Gotoh, K .; Nishiuchi, E .; Ohn
o and N. Akahira: “Land and
groove recording for hig
h track density on phase
change optical disks ”, Jp
n. J. Appl. Phys. 32,5324 / 5
328 (1993). The push-pull method is used to track a track optically, but at higher densities, higher accuracy is required for tracking,
Any offset in the optical system causes a track offset, which causes a problem that the light spot is shifted from the center of the track when recording or reproducing data.

[0003] The prior art will be described below with reference to FIGS. 4 and 5. In FIG. 4, when a beam spot is irradiated on a land L1 formed on an optical disc and a part of the beam spot is irradiated on adjacent grooves G1 and G2, laser light is emitted from the land L1, the grooves G1 and G2. Is reflected.

[0004] The zero-order diffracted light LS10 is obtained from the land L1, and the first-order diffracted light LS12 is obtained from the grooves G1 and G2.
LS21 is obtained. The above-mentioned 0th-order diffracted light LS10, 1st-order diffracted lights LS21 and LS12 are guided to a photodetector 8 provided in an optical pickup (not shown).
Is irradiated as shown in FIG.

As shown in FIG. 5, in the photodetector 8 divided into two, the area AR10 irradiated with the 0th-order diffracted light LS10 is shown by a solid line as a circular portion, and is hatched. The ranges AR21 and AR12 are ranges irradiated with the zero-order diffracted light LS10 and the first-order diffracted lights LS21 and LS12. In the photodetector 8, the first-order diffracted light LS2
1. The LS 12 is photoelectrically converted to an electric signal. Therefore, the level difference of the light intensity is converted into the level difference of the electric signal. Then, the level difference of the electric signal [ELA-EL
B] is used as a tracking error signal.

Further, conventionally, there has been known a method of wobbling a groove on a disk in a radial direction of the disk as a mark for obtaining a clock signal for recording and reproducing a data signal. FIG. 3 shows an example in which one side of a groove (in this example, a width of 0.6 μm) is slightly wobbled (in this example, an amplitude of 30 nanometers). A track on the disk is irradiated with a laser beam, a wobbling signal is reproduced, and a clock signal is generated to record data. However, this method has a problem that it is difficult to produce a high-quality disc when the groove width is reduced.

[0007]

The problem to be solved by the present invention is described with reference to FIG. 3 in which data is recorded in a form in which data can be optically read in both the groove and the land.
This will be described with reference to FIGS.

FIG. 3 shows an enlarged schematic sectional view and a schematic enlarged plan view of a part of a land / groove recording disk for recording on the lands L6 and L7 and the grooves G6 and G7 in order to increase the recording capacity of the optical disk. . In the illustrated example, the width of the groove portion and the width of the land portion are 0.6 microns. In order to optically track the land portion L6 or the groove portion G7, the push-pull method shown in FIGS. 4 and 5 is generally used. However, when the land width and the groove width are reduced to approximately 0.6 μm, Higher accuracy is required for tracking, and the above-described one-beam differential push-pull method generates a level difference [ELA-ELB] when the optical disk is tilted or eccentric, resulting in a DC offset, As a result, there is a problem that the track is erroneously determined as detrack. As a result, a problem occurs in recording and reproducing data on lands and grooves having a narrow track width, which is a major obstacle to practical use.

Further, in FIG. 3, the side surface of the groove is wobbled to obtain a clock signal at the time of data recording. Although the wobbling width is small (for example, 30 nanometers), it is susceptible to interference with the data signal recorded thereon, which is a major cause of signal reading error, and the track and land are narrowed (for example, 0.6 nm). Micron size or less), which is a major obstacle to practical application. Further, a groove of one wobble has many problems such as the necessity of a two-beam laser cutting device when forming a disk.

[0010]

According to the present invention, there is provided a land data recording area having substantially the same width on a track on which information formed in a spiral or concentric manner can be recorded on an optical disk medium according to the first invention. And the groove data recording area are alternately arranged in both the radial direction and the track direction, and the land area and the groove area are alternately arranged from 200 to 4000 per circuit of the track. .

In a recording / reproducing apparatus according to a second aspect of the present invention, a means for irradiating a rotating optical disk with a light beam and detecting a push-pull tracking signal in a land area and a groove area of a track by the light beam. Means for detecting a data recording clock signal at a boundary between a land and a groove on a track.

In the recording / reproducing apparatus according to the third aspect of the present invention, means for irradiating a rotating optical disk with a light beam, and a tracking signal is detected at the boundary between a land and a groove in the track direction by the light beam. Means.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 illustrates an optical disk recording / reproducing apparatus according to the present invention. In FIG. 1A, a phase change film or a magneto-optical thin film 2 is formed on a disk substrate 5. Laser light output from the laser diode 4 used in the optical pickup 3 is collimated by the collimator lens 20. The parallel light reaches an objective lens 22 via a beam splitter 21. The above-mentioned parallel light is condensed by the objective lens 22, and the surface 5a of the optical disc 5
To form a beam spot BS0. The laser light reflected from the surface 5a of the optical disk 5
2. The light is guided to the photodetector 7 via the beam splitter 21 and irradiated on the photodetector 7. The photodetector 7 is a quadrant photodetector composed of photodetectors 7a, 7b, 7c and 7d. The light applied to the photodetector 7 is
a, 7b, 7c, and 7d, the outputs of which are output from the differential amplifiers 23, 24, and 24 as shown in B, C, and D of FIG.
25.

As shown in FIG. 1B, the photodetectors 7a and 7
The output from b is supplied to the (-) terminal of the differential amplifier 23, and the output from the photodetectors 7c and 7d is supplied to the (+) terminal of the differential amplifier 23. The differential signal output of the differential amplifier 23 is supplied to the clock forming circuit 26.

Further, as shown in FIG. 1C, the output from the photodetectors 7a and 7c is supplied to the (-) terminal of the differential amplifier 24 with the signal photoelectrically converted by the photodetector 7, Outputs from the photodetectors 7b and 7d are supplied to the (+) side terminal of the differential amplifier 24. The differential signal output of the differential amplifier 24 is used as a push-pull tracking signal as a lens drive circuit 27.
Supplied to

As shown in FIG. 1D, the signals photoelectrically converted by the photodetector 7 and the outputs from the photodetectors 7a and 7d are supplied to the (-) terminal of the differential amplifier 25. Outputs from the photodetectors 7b and 7c are supplied to the (+) side terminal of the differential amplifier 25. The differential signal output of the differential amplifier 25 is supplied to the lens drive circuit 27 as a tracking signal.

Next, the formation of a clock signal, which is one embodiment of the present invention, will be described. In FIG. 2 showing a disk structure according to a second embodiment of the present invention, an optical pickup 3 moves along a track center Lch indicated by a dotted line. Therefore, the light distribution at which the reflected light of the beam spot BS0 irradiates the photodetector 7 at the time points t1 and t2 at the boundary between the land portion L and the groove portion G is, at the time point t1, the light distribution of the photodetectors 7a, 7b, 7c and 7d. 7a, 7b, at time t
In 2, it is biased to 7c and 7d. However, beam spot BS0
Is within the range between t1 and t2, and at the time of being located at the track center Lch, the light distribution irradiated on the photodetector 7 is uniform. That is, the outputs from the photodetectors 7a and 7b are supplied to the (−) side terminal of the differential amplifier 23, and are output from the photodetectors 7c and 7b.
Since the output from d is supplied to the (+) terminal of the differential amplifier 23, when the beam spot BSO is located at the time point t1, a positive output signal appears from the differential amplifier 23 and the time point t
When located at 2, a negative output signal appears. When the beam spot BSO is located in the groove G between the time points t1 and t2, the output signal of the differential amplifier does not appear. Therefore, the output of the differential amplifier can be supplied to the clock forming circuit 26, and a clock signal can be formed from the output of the differential amplifier. The clock signal formed by the clock forming circuit 26 is multiplied and used to generate a data channel clock.

Next, the formation of a push-pull tracking signal, which is one embodiment of the present invention, will be described. In FIG. 2 showing the disk structure of the present invention, an optical pickup 3 is shown.
Is the beam spot B between t1 and t2 when it deviates in any direction from the track center Lch indicated by the dotted line.
The light distribution of the reflected light of S0 applied to the photodetector 7 is 7
a, 7c side, or 7b. 7d, the outputs from the photodetectors 7a and 7c are supplied to the (−) terminal of the differential amplifier 24, and the outputs from the photodetectors 7b and 7d are supplied to the (+) terminal of the differential amplifier 24. And the differential amplifier 24
The differential signal output from appears. This differential signal output is supplied to the lens drive circuit 27 for use as a push-pull tracking signal.

Next, the formation of a tracking signal, which is one embodiment of the present invention, will be described. In FIG. 2, when the optical pickup 3 is slightly off-track in any direction from the track center Lch indicated by the dotted line, the light distribution irradiated on the photodetector 7 at the time points t1 and t2 at the boundary between the land and the groove is Are biased toward the photodetectors 7a, 7d or 7b, 7c facing the oblique direction. That is, the outputs from the photodetectors 7a and 7d are supplied to the (−) terminal of the differential amplifier 23, and the outputs from the photodetectors 7b and 7d are supplied to the (+) terminal of the differential amplifier 25. So
A differential signal output as a tracking signal can be obtained from the differential amplifier 25. Therefore, this differential signal output can be supplied to the drive circuit 27 as a tracking control signal.

[0021]

According to the present invention, the beam spot accurately follows the track center without generating a track offset in the land and groove areas, and a more accurate clock signal can be obtained, so that high-density information data of the optical disk can be accurately recorded. Can be played.

[Brief description of the drawings]

FIG. 1 is a block diagram of a recording and reproducing apparatus for recording and reproducing information on lands and grooves according to the present invention.

FIG. 2 is an enlarged schematic view showing a part of the structure of a land and groove disk used in the present invention.

FIG. 3 is an enlarged schematic sectional view and a schematic enlarged plan view of a part of a known land / groove recording disk.

FIG. 4 is a schematic diagram illustrating the relationship between a known land / groove recording disk and its reflected diffracted light.

FIG. 5 is a schematic diagram illustrating an irradiation range of a known two-divided photodetector with a diffracted light of a light beam spot.

[Explanation of symbols]

L land part, G groove part, LS disk diffraction light, BS0 light beam spot, Lch track center line, 2 recording film, 3 optical pickup, 4
Laser diode, 5 disk, 7, 8 photodetector, 20, 22 lens, 21 beam splitter, 23, 24, 25 differential amplifier, 26 clock formation circuit, 27 lens drive circuit

Claims (3)

[Claims] 1. A recordable optical disk having a recording film for recording information in an optically readable form, comprising a land portion having substantially the same width on a spiral or concentric track on which information can be recorded. The data recording area and the groove data recording area are alternately arranged both in the radial direction and in the track direction, and the land area and the groove area are alternately arranged in the number of 200 to 4000 per round of the track. Characteristic recording medium. 2. A means for irradiating a rotating optical disc with a light beam according to claim 1 having a recording film for recording information in an optically readable form; A recording / reproducing apparatus comprising: means for detecting a push-pull tracking signal in a groove area; and means for detecting a data recording clock signal at a boundary between a land and a groove on a track. 3. A means for irradiating a light beam to a rotating optical disk according to claim 1, further comprising a recording film for recording information in an optically readable form, and a land portion in a track direction by said light beam. Means for detecting a tracking signal at a boundary portion of the groove portion.