JPH09288831A - Optical disk tracking method and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtain a stable tracking error signal and track cross signal at the time of tracking an optical disk. SOLUTION: A main beam BM is converged on a land or a groove of the optical disk 6, while sub-beams BS1 and BS2 are converged between the land and the groove, and these beams are reflected by the optical disk 6 so that by using a push-pull signal Md of the main beam BM, becoming 0 in the center of the land and also the center of the groove, the tracking error signal TE is generated. Then, the track cross signal TC is generated by using push-pull signals S1d and S2d of the sub-beams BS1 and BS2 reflected by the optical disk 6, becoming positive (or negative) on the land and also negative (or positive) on the groove and then a zero cross between the land and the groove without fail. Consequently, both signals TE and TC are stably obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc tracking method and an optical disc device.

[0002]

2. Description of the Related Art Generally, when a light spot for recording or reproducing information is made to follow a track or jump to another track, it is set to 0 on the center line of the track.
And a tracking error signal that changes in proportion to the distance from the center line and a track cross signal that determines whether it is on a track or between tracks (on a land or on a groove). And need.

That is, since the optical disk has a large number of tracks instead of one track (a spiral track corresponds to a large number of tracks in the radial direction of the disk), the light spot P is formed as shown in FIG. 13 (a). When a plurality of tracks are crossed (φ indicates the center line of each track in the figure), the tracking error signal is similarly repeated as shown in FIG. Be sure to make a zero-cross at the center) as indicated by the broken line. Therefore, if the tracking error signal is 0 at a certain moment and there is no track cross signal, the light spot is located on the center line φ of the track, so it is 0, or it is located between the tracks. I don't know if it is 0. Specifically, when an attempt is made to jump the light spot P to another track by giving a certain jump pulse, it is unfortunately moved between tracks due to variations in driving force. Pull-in control is performed, but since the polarity of the tracking error signal is opposite to the polarity that can be settled normally on the track,
The position of the light spot P diverges and falls into an uncontrollable state. In order to prevent such an inconvenience, the track cross signal is used so that the track pull-in is not performed by the tracking error signal between the tracks.

Recently, in order to increase the recording capacity, an optical disk device for recording / reproducing information on both the land and the groove has been considered, but in this case,
Since tracking control must be performed even at a position between tracks, the polarity of the tracking error signal must be inverted between the land and the groove (see, for example, Japanese Patent Laid-Open No. 6-84172).
Obtaining a stable track cross signal becomes more important.

By the way, a differential push-pull method is known as a method for obtaining a stable tracking error signal and a track cross signal in an optical disk apparatus for recording / reproducing information on either a land or a groove having different widths. (See, for example, Japanese Patent Publication No. 4-34212). Therefore, as is well known in CD-R and the like, a conventional method for obtaining a tracking error signal and a track cross signal will be described by taking an optical disk device that records and reproduces information on a groove narrower than a land as an example.

Here, the three-beam system is used, and as shown in FIG. 14, when the main light beam B _M is converged on the groove G which is a recording track, two sub-light beams are moved forward and backward in the disc rotation direction. B _S1 and B _S2 are set so as to converge on the land L that is adjacent to the groove G inward and outward. The light-receiving element that individually receives and detects the main light beam B _M and the sub-light beams B _S1 and B _S2 reflected from the optical disc 100 detects the push-pull signal and the sum signal of the individual light beams. More specifically, each of these light receiving elements is divided into two in the track crossing direction, and a push-pull signal is detected by obtaining the difference in the amount of light received in each region.
The sum signal is detected by taking the sum.

The push-pull signal Md of the main luminous flux B _M is shown in FIG.
As shown in FIG. 5 (a), the signal becomes a sinusoidal signal having 0 at the center of the groove G and the center of the land L, and the sum signal Ms of the main light flux B _M is low at the groove G as shown in FIG. 16 (a). The signal is high in L and has a sinusoidal signal including an offset component as a whole. The push-pull signals S1d and S2d and the sum signals S1s and S2s of the sub-beams B _S1 and B _S2 are shown in FIG.
As shown in FIGS. 16B and 16C, the phase is 18 with respect to the push-pull signal Md and the sum signal Ms of the main light beam B _M.
It becomes a sinusoidal signal with a 0 ° shift. Note that FIG. 15 and FIG.
The vertical line indicated by the alternate long and short dash line in 6 indicates the center line of the track (the groove G in this case).

[0008] Then, push the main luminous flux B _M pull signal M
d and push-pull signals S1d and S2d of the sub-beams B _S1 and B _S2
The difference signal from the sum signal (S1d + S2d) (see FIG. 15D) is obtained as the tracking error signal TE (FIG. 15).
(See (e)). According to this, the objective lens that converges the main light flux B _M and the sub-light fluxes B _S1 and B _S2 on the optical disc 100 moves to follow the eccentricity of the optical disc 100, and the positional relationship between each light flux and the corresponding light receiving element. Even if the deviation occurs, the main luminous flux B
_Since the push-pull signal Md of _M and the push-pull signals M1d and M2d of the sub-beams B _S1 and B _S2 are offset in the same direction (see the broken line in FIG. 15), the offset is offset by taking the difference. To be done. That is, even if the optical axis shifts, no offset occurs in the tracking error signal TE. Similarly, even if the optical disc 100 is tilted, no offset occurs in the tracking error signal TE.

The sum signal Ms of the main light flux B _M and the sum signal M1s of the sub-light fluxes B _S1 and B _S2 (M1s + M)
2s) (see FIG. 16 (d)) is obtained as the track cross signal TC (see FIG. 16 (e)). The track cross signal TC is negative on the groove G and is on the land L.
Above, it becomes a positive sinusoidal signal.

Incidentally, it is considered that a similar track cross signal can be obtained by subtracting a constant value from the sum signal Ms of the main light flux B _M. However, in reality, when a recording mark is formed by forming a pit shape or a change in reflectance as in a CD-R, and the amount of reflected light is changed depending on the presence or absence of the recording mark, the recorded area is not recorded. When crossing the recording area, the level of the sum signal Ms varies depending on the presence or absence of a recording mark, so a stable track cross signal cannot be obtained only by subtracting a constant value. A broken line in FIG. 16 indicates a portion where the signal level is lowered by the recording mark having a low reflectance. However, the influence of the presence or absence of the recording mark is the main luminous flux B _M.
And the sub-beams B _S1 and B _S2 are similarly received, the main beam B _M
Sum signal Ms and sum signals M1s and M2s of sub-beams B _S1 and B _S2
By taking the difference signal with the sum signal (M1s + M2s) of the two, the track cross signal TC that is negative on the groove G and positive on the land L is always obtained stably.

[0011]

However, as shown in FIG. 17, the width ratio of the land L and the groove G is approximately 1: 1.
(Generally, in a next-generation optical disc that records on both the land L and the groove G to increase the capacity, the land L
Optical disc 101 having a width ratio of 1: 1 in order to obtain a reproduction signal of equal quality from the groove G and the groove G).
In this case, the sum signal Ms of the main luminous flux B _M is high on the land L and the groove G as shown in FIG.
It becomes a sinusoidal signal that becomes low between the grooves and that includes an offset component. In FIG. 18, the vertical line indicated by the alternate long and short dash line indicates the center line of the track (the groove G and the land L in this case). That is, when recording / reproducing is performed on only one of the land L and the groove G for the optical disc 100 as shown in FIG. 14, the main light beam B _M
The sum signal Ms of 1 has one cycle between a pair of lands and a group, but in the optical disc 101 as shown in FIG. 17, two cycles of a pair of lands and grooves, that is, the same for the land L and the groove G. The signal appears repeatedly. Therefore, the sum signal Ms of the main light beam B _M and the sum signals M1s of the sub light beams B _S1 and B _S2 (see FIG. 18B) and M2s (see FIG. 18C).
Even if the difference between the sum signal M1s + M2s (see FIG. 18 (d)) is obtained, it becomes a signal as shown in FIG. 18 (e),
It is not possible to obtain a desired track cross signal TC that can distinguish between the land L and the groove G.

Another problem is that in an optical disc for recording / reproducing on both lands and grooves, there is no buffer zone without recording marks as in the case of an optical disc for recording / reproducing only on lands or grooves. However, when a push-pull signal is obtained, it is easily affected by adjacent recording marks, and there is a point that an offset occurs in the tracking error signal depending on the presence or absence of the adjacent recording mark. In this respect, there is an example of a sample servo in which a sample pit for guiding an optical spot is provided on an optical disk and a tracking error signal is obtained by a signal when the sample pit passes (for example, see JP-A-6-203411).
However, in order to perform accurate tracking by this method, it is necessary to frequently provide sample pits, and the capacity for recording information decreases accordingly, which is against the demand for larger capacity.

Therefore, an object of the present invention is to provide an optical disk tracking method and an optical disk device which can always obtain stable tracking error signals and track cross signals when tracking an optical disk.

Further, it is possible to prevent the tracking error signal from being offset due to the optical axis shift and the tilt of the optical disk, or to prevent the tracking error signal from being offset due to the presence or absence of the recording mark in the adjacent area. An object of the present invention is to provide a tracking method and an optical disc device.

[0015]

According to another aspect of the present invention, there is provided an optical disc tracking method, wherein a laser beam is divided into a main light beam and at least one sub-light beam, and the main light beam is converged on a land or groove of the optical disk. In addition, the sub-light flux is converged in the middle between the land and the groove of the optical disc, a tracking error signal is generated by using the push-pull signal of the main light flux reflected from the optical disc, and the tracking error signal is generated. A track cross signal is generated using the push-pull signal. As an optical disk device for this purpose, in the invention described in claim 2, a laser light source, a light beam splitting device for splitting the laser light emitted from the laser light source into a main light beam and at least one sub-light beam, and the main light beam. An objective lens for converging on the land or groove of the optical disc and converging the sub-light flux in the middle of the land and groove of the optical disc, and a main light flux which is divided into two in the track crossing direction and reflected from the optical disc is detected. A main light receiving element, a tracking error signal generating means for generating a tracking error signal using a push-pull signal obtained as a result of detection by the main light receiving element, and a sub-beam which is divided into two in the track crossing direction and reflected from the optical disc. The track light is detected using the sub-light-receiving element to be detected and the push-pull signal of the detection result of this sub-light-receiving element. And a track cross signal generation means for generating a signal.

Therefore, according to the first and second aspects of the invention, the tracking error signal is stably obtained by the push-pull signal of the main light flux, which is 0 at both the center of the land and the center of the groove, and the track crossing signal is obtained. The signal is stably obtained by the push-pull signal of the sub-beam which is positive (or negative) on the land and negative (or positive) on the groove. Even if the recorded area and the unrecorded area where the reflected light amount changes are crossed, the push-pull signal of the sub-beam always always crosses zero. Therefore, by using the push-pull signal of the sub-beam, a stable track cross signal can be obtained. Obtainable. In particular, if the difference signal between the push-pull signals of the two sub-beams is used as the push-pull signal of the sub-beam, the amplitude becomes larger than in the case where only one is used, so that the track cross signal can be obtained more stably. it can.

In the optical disk tracking method of the present invention as defined in claim 3, the laser light is divided into a main light beam and two sub-light beams symmetrical with respect to the main light beam, and the main light beam is landed or grooved on the optical disk. While converging, the two sub-light fluxes are respectively converged between the land and the groove of the optical disc, the push-pull signal of the main light flux reflected from the optical disc is Md, and the two sub-light fluxes reflected from the optical disc are each Push-pull signal of S1
d, S2d and a constant corresponding to the light quantity ratio of the main light flux and the sub-light flux are k, a tracking error signal is generated by Md-k (S1d + S2d), and a track cross signal is generated by S1d-S2d. . As an optical disk device for this purpose, in the invention according to claim 4, a laser light source,
A beam splitting means for splitting the laser beam emitted from the laser light source into a main beam and two sub-beams symmetric with respect to the main beam, and two beams for converging the main beam on the land or groove of the optical disk. An objective lens for converging each of the sub-beams in the middle of a land and a groove of the optical disc, a main light-receiving element for dividing a main beam reflected by the optical disc into two, and a main light-receiving element for detecting the main beam in the track-crossing direction. Two sub-light-receiving elements, which are divided into two, respectively detect two sub-light fluxes reflected from the optical disk, main push-pull signal generating means for generating a push-pull signal Md from the detection result of the main light-receiving element, and 2
Sub push-pull signal generating means for generating push-pull signals S1d and S2d of the respective sub-beams from the detection results of the two sub-light receiving elements, and an operation of Md-k (S1d + S2d) (where k is the main beam and the sub-beam). It has a tracking error signal generating means for generating a tracking error signal by a constant corresponding to the light quantity ratio of 1) and a track cross signal generating means for generating a track cross signal by the calculation of S1d-S2d.

Therefore, according to the third and fourth aspects of the invention, when the optical axis shift or the optical disc has an inclination, an offset occurs in the push-pull signal of each light beam.
Since the main light flux and the two sub-light fluxes are affected by the optical axis shift and the tilt of the optical disc in the same direction, the positive and negative signs of the generated offset are also the same. Here, since the push-pull signals S1d and S2d of the two sub-beams are out of phase with each other by 180 °,
In S1d + S2d obtained by adding these, only the offset component remains. Therefore, the push-pull signals S1d of the two sub-beams,
By subtracting the value obtained by adding S2d and multiplying it by k from the push-pull signal Md of the main light beam to obtain the tracking error signal, the offset amount due to the optical axis shift or the tilt of the optical disc is canceled. The track cross signal is the same as in the case of the invention according to claims 1 and 2.

According to a fifth aspect of the present invention, in a tracking method for an optical disk in which information is recorded or reproduced alternately on a land and a groove for each rotation of an optical disk that is driven to rotate, a laser beam and a main light beam are used. Is divided into two sub-beams that are symmetric with respect to the disc rotation direction.
The main light flux is converged on the land or groove of the optical disc, and one sub-light flux preceding the main light flux in the disc rotation direction is preceded by recording in the disc radial direction with the land or groove where the main light flux is converged. Converge to the middle of the groove or land adjacent to the side,
At the same time, the other sub-light flux that follows the main light flux in the disc rotation direction is converged at a position symmetrical with respect to the main light flux.
The push-pull signal of the main light flux reflected from the optical disk is Md, the push-pull signals of the two sub-light fluxes reflected from the optical disk are S1d and S2d, and constants corresponding to the light quantity ratio between the main light flux and the sub-light flux. Let k be Md
A tracking error signal is generated by -k '(S1d + S2d), and a track cross signal is generated by S1d-S2d. As an optical disk device for this purpose, in the invention described in claim 6, in the optical disk device which alternately records or reproduces information on a land and a groove for each revolution of the optical disk driven to rotate, a laser light source and the laser light source are provided. And a beam splitting means for splitting the laser beam emitted from the beam into a main beam and two sub-beams that are symmetric with respect to the main beam in the front-back direction in the disc rotation direction; and the main beam on the land or groove of the optical disc. While converging, one sub-light flux preceding the main light flux in the disc rotation direction is placed between the land or groove where the main light flux is converged and the groove or land adjacent to the side where recording is ahead in the disc radial direction. Objective for converging and converging the other sub-light flux following the main light flux in the disc rotation direction to a position symmetrical with respect to the main light flux. And lens, is divided into two parts across the track, and a main light receiving element for detecting the main light beam reflected from the optical disk, across the tracks 2
Two sub-light-receiving elements, which are each divided to detect two sub-light fluxes reflected from the optical disk, main push-pull signal generating means for generating a push-pull signal Md from the detection result of the main light-receiving element, and two Sub push-pull signal generating means for generating push-pull signals S1d and S2d of each sub-beam from the detection result of the sub-light receiving element, and Md-k '
(S1d + S2d) (where k'is a constant corresponding to the light quantity ratio of the main light flux and the sub-light flux) and a tracking error signal generating means for generating a tracking error signal, and a calculation of S1d-S2d generates a track cross signal. And a track cross signal generating means for generating.

Therefore, according to the fifth and sixth aspects of the invention, when information is continuously recorded in the unrecorded area of the optical disc over the land and the groove, the side where the recording precedes in the disc radial direction. Although the recording marks which have been recorded exist adjacent to each other, the recording marks do not exist adjacent to the side where recording is performed in the radial direction of the disc, so that an offset occurs in the push-pull signal Md of the main light beam. . Therefore, when the main light flux is converged on the land (or groove) of the optical disc, one sub-light flux preceding the main light flux in the disc rotation direction is recorded before the land (or groove) in the disc radial direction. On the side of the other side light flux which is converged in the middle of the groove (or land) adjacent to the side of the main light flux, and which is arranged behind the main light flux in the disc rotation direction is symmetrical with respect to the main light flux, that is, the land ( Or, by converging it in the middle of the groove (or land) adjacent to the recording trailing side in the disc radial direction with respect to the groove, the two recording sub-beams are recorded in the radial direction. Although the recording marks that have been recorded are adjacent to each other, the recording marks do not exist on the side where the recording follows. That is, there is an offset in the push-pull signals S1d and S2d of the two sub-beams, and the sign of the offset is the push-pull signal Md of the main beam.
Is the same as Here, since the phases of the push-pull signals S1d and S2d of the two sub-beams are shifted by 180 °, only the offset component remains in S1d + S2d in which they are added.
Therefore, by adding the push-pull signals S1d and S2d of the two sub-beams and multiplying by a predetermined constant k ', the value is subtracted from the push-pull signal Md of the main beam to obtain a tracking error signal, thereby recording on only one side. The offset of the tracking error signal due to the presence of the mark is canceled. The track cross signal is the same as in the case of the invention according to claims 1 and 2.

According to a seventh aspect of the present invention, in a tracking method for an optical disk in which information is recorded or reproduced alternately on a land and a groove for each rotation of the rotationally driven optical disk, a laser beam is used as a main light beam and this main light beam. Is divided into two sub-beams that are symmetric with respect to the disc rotation direction.
The main light beam is converged on the land or groove of the optical disc, and one sub-light beam preceding the main light beam in the disc rotation direction is recorded in the disc radial direction with the land or groove on which the main light beam is converged. Converge in the middle of the groove or land adjacent to the running side,
Further, the other sub-light flux following the main light flux in the disc rotation direction is converged to a position symmetrical with respect to the main light flux, and a push-pull signal of the main light flux reflected from the optical disc is reflected by Md. The respective push-pull signals of the two sub-beams that are generated are S1d and S2d, and the sum signals of the two sub-beams that are reflected from the optical disk are S1s and S, respectively.
2s, a constant corresponding to the light quantity ratio of the main light flux and the sub light flux, etc.
Then, the tracking error signal is generated by Md + k ″ (S1s−S2s) and the track cross signal is generated by S1d−S2d. In an optical disc device that alternately records or reproduces information on a land and a groove for each revolution of a driven optical disc, a laser light source, a laser beam emitted from the laser light source, and a main light flux and a main light flux with respect to the main light flux. A beam splitting means for splitting the beam into two sub-beams that are symmetrical in the front-back direction of the disc, and the main beam is converged on the land or groove of the optical disc, and one of the main beam precedes the main beam in the disc rotational direction. The sub-light flux of the main light flux and the land or groove in which the main light flux is converged are adjacent to the land or groove in the radial direction of the disk, which is adjacent to the recording side. To the middle of the
An objective lens that converges the other sub-light flux following the main light flux in the disc rotation direction to a position symmetrical to the main light flux, and a main light flux that is split into two in the track crossing direction and reflected from the optical disc. A push-pull signal M based on the detection result of the main light-receiving element, two main light-receiving elements that detect two sub-light fluxes that are divided into two in the track crossing direction, and that detect two sub-light fluxes reflected from the optical disk.
main push-pull signal generating means for generating d, sub-push pull signal generating means for generating push-pull signals S1d, S2d of the respective sub-beams from the detection results of the two sub-light receiving elements, and the two sub-light receiving elements Sub-sum signal generation means for generating sum signals S1s and S2s of the respective sub-beams from the detection result of
Md + k ″ (S1s−S2s) (where k ″ is a constant corresponding to the light quantity ratio between the main light flux and the sub-light flux) and a tracking error signal generating means for generating a tracking error signal, and S1d−S2d And a track cross signal generating means for generating a track cross signal.

Therefore, according to the seventh and eighth aspects of the invention, when information is continuously recorded in the unrecorded area of the optical disc over the land and the groove, the side where the recording precedes in the disc radial direction. Although the recording marks which have been recorded exist adjacent to each other, the recording marks do not exist adjacent to the side where recording is performed in the radial direction of the disc, so that an offset occurs in the push-pull signal Md of the main light beam. . Therefore, when the main light flux is converged on the land (or groove) of the optical disc, one sub-light flux following the main light flux in the disc rotation direction is recorded in the disc radial direction with respect to the land (or groove). The other sub-beam that converges in the middle of the groove (or land) adjacent to the preceding side and precedes the main beam in the disc rotation direction is symmetrical with respect to the main beam, that is, the land (or By converging to the middle of the groove (or land) adjacent to the recording trailing side in the disc radial direction with respect to the groove, the sub-light flux preceding in the disc rotation direction converges to a position where there is no recording mark. The sub-light flux that follows in the disc rotation direction is converged at a position where recording marks may exist on both sides of the boundary line. Here, the sum signals S1s and S2s of the two sub-beams
When a difference S1s-S2s is obtained, a signal corresponding to the effect of the recording mark is obtained. Therefore, a value obtained by multiplying the difference signal S1s-S2s by a predetermined constant k ″ is added to the push-pull signal Md of the main light beam to perform tracking. By obtaining the error signal, the offset of the tracking error signal due to the presence of the recording mark on only one side is canceled out.The track cross signal is the same as in the case of the first and second aspects of the invention.

According to a ninth aspect of the present invention, in a tracking method for an optical disk in which information is recorded or reproduced alternately on a land and a groove for each rotation of the rotationally driven optical disk, a laser beam is used as a main light beam and this main light beam. Is divided into two sub-beams that are symmetric with respect to the disc rotation direction.
The main light beam is converged on the land or groove of the optical disc, and one sub-light beam preceding the main light beam in the disc rotation direction is recorded in the disc radial direction with the land or groove on which the main light beam is converged. Converge in the middle of the groove or land adjacent to the running side,
Further, the other sub-light flux following the main light flux in the disc rotation direction is converged to a position symmetrical with respect to the main light flux, and a push-pull signal of the main light flux reflected from the optical disc is reflected by Md. The respective push-pull signals of the two sub-beams that are generated are S1d and S2d, and the sum signals of the two sub-beams that are reflected from the optical disk are S1s and S, respectively.
2s, a constant corresponding to the light quantity ratio of the main light flux and the sub-light flux, etc., k,
If k ", Md-k (S1d + S2d) + k" (S1s
-S2s) to generate a tracking error signal,
A track cross signal is generated by S2d. As an optical disk device for this purpose, in the invention described in claim 10, a laser light source and the laser light source are provided in the optical disk device which records or reproduces information alternately on a land and a groove for each rotation of the optical disk which is driven to rotate. And a beam splitting means for splitting the laser beam emitted from the beam into a main beam and two sub-beams that are symmetric with respect to the main beam in the front-back direction in the disc rotation direction; and the main beam on the land or groove of the optical disc. In the middle of the land or groove where the main light beam is converged and one of the sub-light beams that converges and precedes the main light beam in the disc rotation direction and the groove or land that is adjacent to the trailing side in the disk radial direction. And a second sub-light flux that follows the main light flux in the disc rotation direction to a position symmetrical with respect to the main light flux. A lens, a main light receiving element which is divided into two in the track crossing direction and detects a main light beam reflected from the optical disc, and a two light sub-beam which is divided into two in the track crossing direction and reflected from the optical disc. Two sub-light receiving elements, a main push-pull signal generating means for generating a push-pull signal Md from the detection result of the main light-receiving element, and a push-pull signal S1d of each sub-beam from the detection results of the two sub-light receiving elements. , S2d, a sub push-pull signal generating means, a sub sum signal generating means for generating sum signals S1s and S2s of the respective sub light fluxes from detection results of the two sub light receiving elements, and Md-k (S1d + S2d) +
Tracking error signal generating means for generating a tracking error signal by the calculation k ″ (S1s−S2s) (where k and k ″ are constants corresponding to the light quantity ratio of the main light beam and the sub light beam), and S1d−S2d. And a track cross signal generating means for generating a track cross signal by calculation.

Therefore, according to the inventions of claims 9 and 10, basically the same as the case of the inventions of claims 7 and 8, but the push-pull signal and the sum signal with respect to the two sub-beams. In consideration of the above, the signal S1d + S2d between the push-pull signals is used to obtain a signal corresponding to the optical axis deviation or the tilt of the optical disc, and the difference S1s-S2s between the sum signals is used to obtain the signal corresponding to the influence of the recording mark, thereby obtaining the tracking error. Since the signal is used for calculating the signal, a stable tracking error signal is obtained in which the effects of the offset due to the optical axis shift or the tilt of the optical disc and the offset due to the presence of the recording mark on only one side are canceled.

In the inventions as claimed in claims 11 and 12, as the optical disk used in each of the above-mentioned inventions, an optical disk having a land-to-groove width ratio of approximately 1: 1 is used. Therefore, even when using an optical disk aiming at a large capacity, the tracking error signal and the track cross signal can be stably obtained, and the track following operation and the track jump operation can be stably performed.

[0026]

FIG. 1 shows a first embodiment of the present invention.
A description will be given based on FIG. First, laser light emitted from a semiconductor laser (laser light source) 1 is collimated by a collimator lens 2 and then passed through a diffraction grating (beam splitting means) 3 whose transmittance changes sinusoidally, It is diffracted into 0th order light and ± 1st order light, and the 0th order light is split so that the main light beam B _M ± 1st order light beam becomes two sub-light beams B _S1 and B _S2 . These light fluxes B _M , B _S1 , and B _S2 are transmitted through the beam splitter 4 and converged by the objective lens 5 so as to form a minute light spot on the surface of the optical disc 6. These light fluxes B _M reflected by the optical disc 6,
B _S1 and B _S2 again pass through the objective lens 5 to become parallel light, which is further reflected by the beam splitter 4 and separated from the incident light, and then narrowed by a condenser lens 7 to correspond to the respective light receiving elements. It is incident on 8, 9 and 10 and is used for signal detection. The objective lens 5 is provided with an actuator 11 that displaces the objective lens 5 in the tracking direction.

With the basic structure and operation as described above, the optical disc 6 of the present embodiment is as shown in FIG.
The land L and the groove G are used in such a relationship that the ratio of their widths is 1: 1. For such an optical disk 6, when the main light beam B _M used for recording, reproducing or erasing information, focusing and tracking is located on the center line of the groove G (or on the center line of the land L), it is used for tracking. Sub-light fluxes B _S1 , B used for
_The objective lens 5 is arranged so that _S2 converges on the groove G (or the land L) between the adjacent lands L (or the groove G) on the outer peripheral side and the inner peripheral side of the disc, respectively.
The convergence position by has been adjusted. As can be seen from FIG. 2, the two sub-beams B _S1 and B _S2 are converged at symmetrical positions with respect to the main beam B _M , and are in front of and behind in the disc rotation direction. For example, when the sub light beams sub beam B _S1 precedes in the disk rotational direction than the main beam B _M, sub beam B _S2 becomes sub beam for trailing in the direction of disk rotation than the main luminous flux B _M.

The light receiving element 8 serves as a main light receiving element, and is divided into two light receiving areas a,
A photodiode with b is used. Both of the light receiving elements 9 and 10 serve as sub-light receiving elements, and photodiodes having light receiving regions c, d, e, f divided into two in the track crossing direction are used.

A differential amplifier 12 is connected to the light receiving element 8 for calculating a push-pull signal Md according to a diffraction pattern due to diffraction of the groove G and the land L by taking an output difference between the light receiving areas a and b. ing. Tracking error signal generating means 13 is provided which uses the push-pull signal Md obtained by the differential amplifier 12 as a tracking error signal TE. In addition, the light receiving elements 9 and 10
Differential amplifiers 14 and 15 for calculating push-pull signals S1d and S2d by calculating the output difference between the respective light receiving regions c, d, e, and f are connected to. A differential amplifier 16 that takes the difference between the push-pull signals S1d and S2d is connected to the output side of these differential amplifiers 14 and 15. These differential amplifiers 14, 15 and 16 constitute a track cross signal generation means 17 which uses S1d-S2d as the track cross signal TC. Further, there is provided a tracking control circuit 18 to which the tracking error signal TE obtained from the differential amplifier 12 and the track cross signal TC obtained from the differential amplifier 16 are input. The tracking control circuit 18 includes the actuator 11
A drive circuit 19 for driving the is connected.

In such a structure, the main light beam B _M emitted to the optical disc 6 is reflected by the optical disc 6 and then enters the light receiving element 8 to be detected. Now, assuming that the main light beam B _M is traversed in the track crossing direction, the difference between the outputs obtained from the light receiving regions a and b of the light receiving element 8 is obtained by the differential amplifier 12, and as shown in FIG. , A push-pull signal Md corresponding to the diffraction pattern of the land L and the groove G is obtained. By using this push-pull signal Md as the tracking error signal TE, the land L is used as the tracking error signal TE.
A signal which becomes 0 at the center of the groove and the center of the groove G is obtained. In FIG. 3, the vertical line indicated by the alternate long and short dash line indicates the center line of the track (hence, the groove G and the land L) (the same applies to FIGS. 5, 8 and 11 described later).

On the other hand, the two sub-light fluxes B _S1 and B _S2 that follow the main light flux B _M are also reflected by the optical disk 6 and detected by the light-receiving elements 9 and 10 by the differential amplifiers 14 and 15, respectively. By taking the difference, as shown in FIGS. 3B and 3C, push-pull signals S1d and S2d corresponding to the diffraction pattern of the land L and the groove G are obtained. Therefore, the track cross signal TC is obtained as a difference S1d-S2d between the two push-pull signals S1d and S2d by the differential amplifier 16 which is positive on the land L and negative on the groove G (see FIG. 3 (d)). Here, even if the sub-beams B _S1 and B _S2 cross the recorded area and the unrecorded area where the reflected light amount changes on the optical disc 6, the push-pull signals S1d and S2d and the difference signal S1d-S2d are always the land L. Since the zero crossing occurs at the boundary between the groove G and the groove G, a stable track crossing signal T
C can be obtained.

A drive signal is sent from the tracking control circuit 18 to the drive circuit 19 based on the tracking error signal TE and the track cross signal TC thus obtained, and the drive circuit 19 supplies power to the actuator 11. As a result, tracking operation such as follow-up control for the track (land L or groove G) and jump operation to another track is executed.

In this embodiment, the track cross signal TC is obtained by the difference S1d-S2d between the two push-pull signals S1d and S2d. However, only one of the push-pull signals S1d and S2d is track-crossed. It may be the signal TC. When the push-pull signal S1d is a track cross signal, a signal that is positive on the land L and negative on the groove G is obtained. Conversely, when the push-pull signal S2d is a track cross signal, on the contrary, A signal that is negative on L and positive on groove G is obtained. However, when the diffraction grating 3 is used as the light beam splitting means, sub-light beams B _S1 and B _{S2 with} respect to the 0th-order light which is the main light beam B _M for recording and reproduction.
Since the ± 1st order light has a small amount of light, the amplitude of the track cross signal TC is small only with the push-pull signal S1d or S2d. Therefore, two push-pull signals S1d and S2d are used, and the difference S1d and S2d is obtained. It is desirable to increase the amplitude.

A second embodiment of the present invention will be described with reference to FIGS. 4 and 5.
It will be described based on. The same parts as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof will be omitted (the same applies to the following embodiments).

In the present embodiment, the differential amplifier 12
Functions as the main push-pull signal generating means 21, and the differential amplifiers 14 and 15 are respectively operated as the sub push-pull signal generating means 2.
2, 23 are set to function. Also,
An adding amplifier 24 for adding push-pull signals S1d, S2d by the sub-beams B _S1 , B _S2 and an amplifier 25 for multiplying the output S1d + S2d of the adding amplifier 24 by k are added.
k is a constant corresponding to the ratio of the light amounts of the main light beam B _M and the sub light beams B _S1 and B _S2 . Further, there is provided a differential amplifier 26 that takes the difference between the push-pull signal Md obtained by the differential amplifier 12 and the output k (S1d + S2d) obtained by the amplifier 25. The tracking error signal generating means 2 is composed of the adding amplifier 24, the amplifier 25, and the differential amplifier 26.
7 are configured.

In such a structure, in the present embodiment, Md-k (S1d + S) output from the differential amplifier 26.
The signal 2d) is the tracking error signal TE. If the optical axis is deviated or the optical disc 6 is tilted, the push-pull signals Md, S1d and S2d have an offset as shown by the broken line in FIG. However, the main luminous flux B
_{Since M} and the sub-beams B _S1 and B _S2 are affected by the optical axis shift and the tilt of the optical disk 6 in the same direction, the positive and negative signs of the generated offset are also the same. Here, push-pull signal S
Since the phases of 1d and S2d are 180 ° out of phase, only the offset remains in the signal S1d + S2d obtained by adding the two, so an appropriate constant k is multiplied and this offset is pushed. By subtracting from the pull signal Md, the tracking error signal TE in which the offset amount is canceled is obtained. The track cross signal TC is the same as that in the above-described embodiment.

A third embodiment of the present invention will be described with reference to FIGS. The optical disc device according to the present embodiment is also configured in the same manner as in the case of FIG. 1A, but recording / reproduction of information is alternately performed on the land L and the groove G for each revolution of the optical disc 6. It is applied to the optical disc device of the method of performing. It is assumed that the addresses on the optical disk 6 are set to increase sequentially from the inner circumference side to the outer circumference side, and the recording is set to be performed in ascending order of the addresses. That is, in the radial direction of the disc, the inner circumference side corresponds to the side where the recording precedes, and the outer circumference side corresponds to the side where the recording follows. Further, the sub-beam bundle B _S1 precedes in the disc rotation direction, and the sub-beam bundle B _S2 follows in the disc rotation direction.

[0038] Under such assumption, when converges the main luminous flux B _M as shown in FIG. 6 on the center line of the groove G, the sub-luminous flux B _S1 which precedes the direction of disk rotation than the main beam B _M is The groove G and the land L adjacent to the inner peripheral side thereof
Of the sub-light flux B _S2 which converges in the middle of the groove G and the land L adjacent to the outer circumference of the groove G, and the sub-light flux B _{S2 which} follows the main light flux B _{M in the} disc rotation direction. The convergence position of the light flux is set. 28 in FIG.
Is a recording mark.

In the circuit configuration shown in FIG. 7, k
Instead of the doubling amplifier 25, a k ′ multiplying amplifier 29 is used. k ′ is a constant corresponding to the ratio of the light amounts of the main light beam B _M and the sub light beams B _S1 and B _S2 and the degree of influence of the recording mark 28. As a result, M output from the differential amplifier 26
The signal d-k '(S1d + S2d) is the tracking error signal TE.

In such a structure, as shown in FIG. 6, when recording in an unrecorded area by the main light beam B _M , the recording mark 28 does not exist on the outer peripheral side in the disc radial direction, but in the disc radial direction. Since the recorded marks 28 that have been recorded are adjacent to each other on the inner peripheral side, the push-pull signal Md of the main light beam B _M has an offset as shown by the broken line in FIG. 8A. On the other hand, the sub-light flux B _S1 preceding the main light flux B _{M in the} disc rotation direction is converged in the middle of the land L adjacent to the inner circumference side, and the sub-light flux B _S1 is recorded on the inner circumference side. 28 exists and the recording mark 28 does not exist on the outer peripheral side, and the push-pull signal S1d also has an offset as shown by the broken line in FIG. 8B. Further, the sub-beam B _S2 following the main beam B _{M in the} disc rotation direction is converged in the middle of the land L adjacent to the outer peripheral side, and this sub-beam B _S2 is also recorded mark 28 on the inner peripheral side. Exists, and the recording mark 28 does not exist on the outer peripheral side, and the push-pull signal S2d also has an offset as shown by the broken line in FIG. 8C. That is, main luminous flux B _M sub beam B _S1, B _S2 also a state where there is only the recording mark 28 side, sub beam B _S1, B _S2 by the push-pull signals S1d, in the same direction as the push-pull signal Md to S2d Produces an offset. Since the push-pull signals S1d and S2d are out of phase with each other by 180 °, only the offset remains in the signal S1d + S2d obtained by adding the two, as shown in FIG. By subtracting this offset amount from the push-pull signal Md, the tracking error signal TE in which the offset amount due to the presence of the recording mark 28 on only one side is canceled out.
Is obtained. The track cross signal TC is the same as that in the above-described embodiment.

Regarding the above-mentioned respective embodiments,
Even when applied to an optical disc in which the width ratio of the land L and the groove G is not 1: 1, the stable tracking error signal TE and the track cross signal TC can be obtained in the same manner, and the stable tracking error signal TE and the track cross signal TC can be obtained. The offset and the offset due to the presence or absence of the recording mark in the adjacent area can be offset.

A fourth embodiment of the present invention will be described with reference to FIGS. 9 to 10. The optical disc device according to the present embodiment is also configured in the same manner as in the case of FIG. 1A, but as in the case of the third embodiment, the land L and the groove G are provided for each revolution of the optical disc 6. It is applied to an optical disc device of a system that alternately records and reproduces information. The addresses on the optical disk 6 are set so as to sequentially increase from the inner circumference side to the outer circumference side, and
It is assumed that the recording is set to be performed in ascending order of addresses. Further, the sub-beam bundle B _S1 precedes in the disc rotation direction, and the sub-beam bundle B _S2 follows in the disc rotation direction.

Under such a premise, when the main light beam B _M is converged on the center line of the groove G as shown in FIG. 9, the positions of the sub light beams B _S1 and B _S2 are opposite to those in the case of FIG. To be set in a relationship. That is, the sub-light flux B _S1 preceding the main light flux B _{M in the} disc rotation direction is converged in the middle of the groove G and the land L adjacent to the outer periphery thereof, and the main light flux B _M
The converging position is set so that the sub-light flux B _S2 that follows in the disc rotation direction converges in the middle between the groove G and the land L adjacent to the inner peripheral side thereof.

Further, in the circuit configuration shown in FIG.
Addition amplifiers 31 and 32 that add the outputs obtained from the light receiving regions c, d, e, and f of the light receiving elements 9 and 10 based on the sub-beams B _S1 and B _S2 are added. These summing amplifier 3
Reference numerals 1 and 32 function as sub-sum signal generation means 33 and 34 for generating sum signals S1s and S2s of the sub-beams B _S1 and B _S2 . Also, a differential amplifier 3 that takes the difference between these sum signals S1s and S2s
5 and an amplifier 36 for multiplying the output S1s-S2s of the differential amplifier 35 by k ″. K ″ is the ratio of the light amount of the main light beam B _M and the sub-light beams B _S1 , B _S2 and the recording mark. It is a constant corresponding to the influence degree of 28. Further, there is provided an adding amplifier 37 for adding the push-pull signal Md obtained by the differential amplifier 12 and the output k ″ (S1s−S2s) obtained by the amplifier 36. These differential amplifiers 35, 36 and A tracking error signal signal generating means 38 is configured by the adding amplifier 37. The adding amplifier 37.
The signal Md + k ″ (S1d−S2d) output by the above is the tracking error signal TE.

In such a structure, as shown in FIG. 9, when recording in the unrecorded area by the main light beam B _M , the recording mark 28 does not exist on the outer peripheral side in the disc radial direction, but in the disc radial direction. Since the recorded marks 28 that have been recorded are adjacent to each other on the inner peripheral side, the push-pull signal Md of the main light beam B _M has an offset as shown by the broken line in FIG. 11A. On the other hand, the sub-beam B _S1 preceding the main beam B _{M in the} disc rotation direction is converged in the middle of the land L adjacent to the outer peripheral side, and the sub-beam B _S1 has recording marks 28 on both inner and outer peripheral sides. Is not present, and the sum signal S1s thereof is as shown in FIG. 11 (b). On the other hand, the sub-light flux B _S2 following the main light flux B _{M in the} disc rotation direction is adjacent to the land L adjacent to the inner circumferential side.
And the recording marks 28 are present on both sides of the inner and outer peripheries of the sub-light flux B _S2 , and the sum signal S2s thereof changes as shown by the broken line in FIG. 11 (c). To do. That is, the sum signal S1s, which is originally the same,
A difference occurs in S2s, and the difference signal S1s-S2s between them is shown in FIG.
As shown in (d), only the offset remains. Therefore, by multiplying the appropriate constant k ″ and adding this offset to the push-pull signal Md, the recording mark 28 on only one side is recorded.
The tracking error signal TE is obtained by offsetting the offset amount due to the presence of. Track cross signal TC
Regarding the above, it is similar to the case of the above-described embodiment.

The fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is based on the above-described fourth embodiment, and the positional relationship among the main light flux B _M , the sub-light fluxes B _S1 , B _S2, etc. is set in the same manner as in the case of FIG.

In the circuit configuration shown in FIG. 12, an adding amplifier 24 and an amplifier 25 for multiplying by k are provided as in the case of FIG. 4, and a differential amplifier 35, as in the case of FIG.
An amplifier 36 for multiplying by k ″ is provided. Further, the signal k ″ (S1s−S2s) obtained from the amplifier 36 and the amplifier 2 are provided.
5 is provided with a differential amplifier 39 that takes the difference from the signal k (S1d + S2d) obtained, and an addition amplifier 40 that adds the output of this differential amplifier 39 and the push-pull signal Md obtained from the differential amplifier 12. ing. These summing amplifiers 24 and 40, differential amplifiers 35 and 39, and amplifiers 25 and 3
6 constitutes a tracking error signal generating means 41. As a result, the signal Md-k (S1d + S2d) + k "(S1s-S2s) output from the adding amplifier 40 is used as the tracking error signal TE.

According to the present embodiment, the push-pull signals S1d and S2d and the sum signals S1s and S2s are taken into consideration with respect to the two sub-beams B _S1 and B _S2 , and the push-pull signal S is taken into consideration.
A signal corresponding to the optical axis shift and the tilt of the optical disc 6 is obtained by the sum S1d + S2d of 1d and S2d, and the sum signal S1s,
Since the signal corresponding to the influence of the recording mark 28 is obtained by the difference S1s-S2s between S2s and is used for the calculation of the tracking error signal TE, the offset due to the optical axis shift or the inclination of the optical disc 6 and the recording mark on only one side are obtained. A stable tracking error signal TE is obtained in which the influence of the presence of 28 and the offset are both canceled out.

[0049]

According to the first and second aspects of the present invention, the main light flux is converged on the land or groove of the optical disk and the sub-light flux is converged in the middle of the land and the groove, and is reflected by the optical disk. Since the tracking error signal is generated by using the push-pull signal of and the track cross signal is generated by using the push-pull signal of the sub-beam reflected from the optical disc, the tracking error signal and the track cross signal are stabilized. It is possible to obtain an appropriate tracking operation.

According to the third and fourth aspects of the present invention, the main light flux is converged on the land or groove of the optical disk, and the two sub-light fluxes symmetrical about the main light flux are converged in the middle of the land and the groove. A tracking error signal is generated by the difference between the push-pull signal of the main light beam reflected from the optical disk and the sum signal of the push-pull signals of the two sub-light beams, and the push-pull signal of the sub-light beam reflected from the optical disk is used. Since the track cross signal is generated, it is possible to stably obtain the tracking error signal and the track cross signal, and it is possible to prevent the tracking error signal from being offset due to the optical axis shift or the tilt of the optical disc. This can be prevented, and an appropriate tracking operation can be performed.

According to the fifth and sixth aspects of the invention, when information is recorded or reproduced alternately on the land and the groove for each rotation, the main light flux is converged on the land or the groove of the optical disc, and One of the sub-beams preceding the main beam in the disc rotation direction is converged in the middle between the land or groove where the main beam converges and the groove or land adjacent to the side where recording is preceded in the disc radial direction, and The other sub-light flux that follows the light flux in the disc rotation direction is converged to a position symmetrical to the main light flux, and the difference between the push-pull signal of the main light flux and the sum signal of the push-pull signals of the two sub-light fluxes is converged. A tracking error signal is generated by using the push-pull signal of the sub-beam reflected from the optical disc to generate a track cross signal. Error signal and a track cross signal can be stably obtained, and an offset can be prevented from occurring in a tracking error signal due to the presence or absence of an adjacent recording mark, and an appropriate tracking operation can be performed. be able to.

According to the seventh and eighth aspects of the invention, when information is recorded or reproduced alternately on the land and the groove for each rotation, the main light flux is converged on the land or the groove of the optical disc, and One sub-light flux preceding the main light flux in the disc rotation direction is converged in the middle of the land or groove where the main light flux is converged and the groove or land adjacent to the recording trailing side in the disc radial direction, and The other sub-beam that follows the main beam in the disc rotation direction is converged to a position symmetrical to the main beam, and the push-pull signal of the main beam and the difference signal of the sum signals of the two sub-beams are added. The tracking error signal is generated by using the push-pull signal of the sub-beam reflected from the optical disc, and the tracking cross signal is generated. And a track cross signal can be stably obtained, and an offset can be prevented from occurring in a tracking error signal due to the presence or absence of an adjacent recording mark, and an appropriate tracking operation can be performed. it can.

According to the inventions of claims 9 and 10, 1
When recording or reproducing information alternately on the land and groove for each circumference, the main light flux is converged on the land or groove of the optical disc, and one sub-light flux preceding the main light flux in the disc rotation direction is The sub-light flux that converges in the middle of the land or groove where the light flux is converged and the groove or land that is adjacent to the recording trailing side in the disc radial direction and that follows the main light flux in the disc rotation direction The light beam is converged to a position symmetrical with respect to the main light beam, the difference signal of the sum signals of the two sub light beams is added to the push pull signal of the main light beam, and the sum signal of the push pull signals of the two sub light beams is further added. Since a tracking error signal is generated by subtracting, and the track cross signal is generated using the push-pull signal of the sub-beam reflected from the optical disc, It is possible to stably obtain the racking error signal and the track cross signal, and prevent the tracking error signal from being offset due to the optical axis shift, the tilt of the optical disc, and the presence or absence of the adjacent recording mark. Therefore, the proper tracking operation can be performed.

According to the invention described in claims 11 and 12,
As the optical disk used in each of the above-mentioned inventions, the width ratio of the land and the groove is set to about 1: 1.
Even when using an optical disc aiming at a large capacity, the tracking error signal and the track cross signal can be stably obtained, and the track following operation and the track jump operation can be stably performed.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a configuration diagram of an optical system of an optical disc device, and FIG. 1B is a circuit configuration diagram.

FIG. 2 is a schematic plan view showing the positional relationship of light beams on an optical disc.

FIG. 3 is a waveform diagram showing the waveform of each signal.

FIG. 4 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a waveform diagram showing the waveform of each signal.

FIG. 6 is a schematic plan view showing the positional relationship of each light beam on the optical disc of the third embodiment of the present invention.

FIG. 7 is a circuit configuration diagram.

FIG. 8 is a waveform diagram showing the waveform of each signal.

FIG. 9 is a schematic plan view showing the positional relationship of each light beam on the optical disc of the fourth embodiment of the present invention.

FIG. 10 is a circuit configuration diagram.

FIG. 11 is a waveform diagram showing the waveform of each signal.

FIG. 12 is a circuit configuration diagram showing a fifth embodiment of the present invention.

FIG. 13 is an explanatory diagram for explaining, as a general theory, a state of a tracking signal when a light spot crosses a track.

FIG. 14 is a schematic plan view showing the positional relationship of each light beam on the optical disc for explaining the conventional differential push-pull method.

FIG. 15 is a waveform diagram showing the waveform of each signal for obtaining a tracking error signal.

FIG. 16 is a waveform diagram showing waveforms of respective signals for obtaining a track cross signal.

FIG. 17 is a schematic plan view showing the positional relationship of each light beam on the optical disc when the ratio of the width of the land to that of the groove is 1: 1.

FIG. 18 is a waveform diagram showing waveforms of respective signals for obtaining a track cross signal.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laser light source 3 Luminous flux dividing means 5 Objective lens 6 Optical disk 8 Main light receiving element 9,10 Sub light receiving element 13 Tracking error signal generating means 17 Track cross signal generating means 21 Main push pull signal generating means 22, 23 Sub push pull signal generating means 27 Track Cross Signal Generation Means 33, 34 Sub Sum Signal Generation Means 38 Tracking Error Signal Generation Means 41 Tracking Error Signal Generation Means B _M Main Luminous Flux B _S1 , B _S2 Sub Luminous Flux

Claims (12)

[Claims] 1. A laser beam is divided into a main light beam and at least one sub-light beam, the main light beam is converged on a land or a groove of an optical disc, and the sub-light beam is converged on an intermediate point between the land and the groove of the optical disc. A tracking error signal is generated using the push-pull signal of the main light flux reflected from the optical disk, and a track cross signal is generated using the push-pull signal of the sub-light flux reflected from the optical disk. Optical disc tracking method. 2. A laser light source, a light beam splitting means for splitting the laser light emitted from the laser light source into a main light beam and at least one sub-light beam, and the main light beam is converged on a land or groove of an optical disk. An objective lens for converging the sub-light flux in the middle of a land and a groove of the optical disc, a main light-receiving element that is divided into two in the track crossing direction and detects a main light flux reflected from the optical disc, and a main light-receiving element of the main light-receiving element. A tracking error signal generating means for generating a tracking error signal by using a push-pull signal as a detection result, a sub light receiving element for detecting a sub light flux reflected from the optical disc which is divided into two in the track crossing direction, and this sub light reception. A track-cross signal generator that generates a track-cross signal using the push-pull signal that is the detection result of the device. An optical disk device comprising: a step. 3. A laser beam is divided into a main light beam and two sub-light beams symmetrical with respect to the main light beam, the main light beam is converged on a land or a groove of an optical disk, and the two sub-light beams are respectively formed. The push-pull signal of the main light flux reflected from the optical disc is converged to the middle between the land and the groove of the optical disc, and the push-pull signals of the two sub-light fluxes reflected from the optical disc are S1d, S2d, and the main light flux. Let k be a constant corresponding to the light quantity ratio between
A tracking method for an optical disk, wherein a tracking error signal is generated by (S1d + S2d) and a track cross signal is generated by S1d-S2d. 4. A laser light source, a light beam splitting means for splitting the laser light emitted from the laser light source into a main light beam and two sub-light beams which are symmetrical with respect to the main light beam, and the main light beam is land of an optical disk. Alternatively, an objective lens for converging on the groove and converging the two sub-beams in the middle between the land and the groove of the optical disc, and a main beam reflected by the optical disc that is divided into two in the track crossing direction are detected. A main light receiving element, two sub light receiving elements which are divided into two in the track crossing direction and each detect two sub light fluxes reflected from the optical disk, and a push-pull signal Md is generated from the detection result of the main light receiving element. Main push-pull signal generating means, and a sub-push that generates push-pull signals S1d and S2d of each sub-beam from the detection results of the two sub-light receiving elements. S1d-S2d, and a tracking error signal generating means for generating a tracking error signal by an Md-k (S1d + S2d) calculation (where k is a constant corresponding to the light quantity ratio of the main light flux and the sub-light flux). An optical disk device comprising: a track cross signal generation unit that generates a track cross signal by the following calculation. 5. A tracking method for an optical disc, wherein information is recorded or reproduced alternately on a land and a groove for each revolution of a rotationally driven optical disc, wherein a laser beam is a main light beam and a disc rotation direction with respect to the main light beam. Is divided into two sub-beams that are symmetrical before and after the main beam, and the main beam is converged on the land or groove of the optical disc, and one sub-beam that precedes the main beam in the disc rotation direction is the main beam. Is converged in the middle between the land or groove on which recording is converged and the groove or land adjacent to the side where recording is preceded in the disk radial direction,
Further, the other sub-light flux following the main light flux in the disc rotation direction is converged to a position symmetrical with respect to the main light flux, and the push-pull signal of the main light flux reflected from the optical disc is Md, which is reflected from the optical disc. Let S1d and S2d be the push-pull signals of each of the two sub-light fluxes that are generated, and k'be a constant corresponding to the light quantity ratio between the main light flux and the sub-light flux.
An optical disk tracking method, wherein a tracking error signal is generated by -k '(S1d + S2d) and a track cross signal is generated by S1d-S2d. 6. An optical disc apparatus for recording or reproducing information alternately on a land and a groove for each revolution of a rotationally driven optical disc, wherein a laser light source and a laser beam emitted from the laser light source are main light fluxes. A light beam splitting unit that splits the main light beam into two sub-light beams that are symmetrical in the front-back direction in the disc rotation direction, and converges the main light beam on a land or groove of the optical disc, and further discs than the main light beam. One of the sub-beams preceding in the rotation direction is converged to the middle of the land or groove where the main beam is converged and the groove or land adjacent to the side where recording is preceded in the disc radial direction,
Further, an objective lens for converging the other sub-light flux following the main light flux in the disc rotation direction to a position symmetrical with respect to the main light flux, and the main lens which is divided into two in the track crossing direction and is reflected from the optical disc. A main light receiving element that detects a light beam, two sub light receiving elements that are divided into two in the track crossing direction and detect two sub light beams reflected from the optical disk, and a push-pull signal from the detection result of the main light receiving element. Md-k '(S1d + S2d), a main push-pull signal generating means for generating Md, a sub-push-pull signal generating means for generating push-pull signals S1d, S2d of the respective sub-beams from the detection results of the two sub-light receiving elements. ) (However, k'is a constant corresponding to the light quantity ratio of the main light beam and the sub-light beam) and generates a tracking error signal. When optical disk apparatus characterized by having a track cross signal generation means for generating a track cross signal by S1d-S2d it becomes operational. 7. A tracking method for an optical disc, wherein information is recorded or reproduced alternately on a land and a groove for each rotation of the rotationally driven optical disc, wherein a laser beam is a main light beam and a disc rotation direction with respect to the main light beam. Is divided into two sub-beams that are symmetrical before and after the main beam, and the main beam is converged on the land or groove of the optical disc, and one sub-beam that precedes the main beam in the disc rotation direction is the main beam. Is converged in the middle of the land or groove that is converged and the groove or land adjacent to the recording trailing side in the disk radial direction,
Further, the other sub-light flux following the main light flux in the disc rotation direction is converged to a position symmetrical with respect to the main light flux, and the push-pull signal of the main light flux reflected from the optical disc is Md, which is reflected from the optical disc. The push-pull signals of each of the two sub-beams that are generated are S1d and S2d, and the sum signals of the two sub-beams that are reflected from the optical disk are S1s,
S2s, where a constant corresponding to the light quantity ratio between the main light flux and the sub-light flux is k ″, a tracking error signal is generated by Md + k ″ (S1s−S2s), and a track cross signal is generated by S1d−S2d. A method for tracking an optical disc, comprising: 8. An optical disk device for alternately recording or reproducing information on a land and a groove for each revolution of an optical disk driven to rotate, wherein a laser light source and a laser beam emitted from this laser light source are main light fluxes. A light beam splitting unit that splits the main light beam into two sub-light beams that are symmetrical in the front-back direction in the disc rotation direction, and converges the main light beam on a land or groove of the optical disc, and further discs than the main light beam. One of the sub-beams preceding in the rotational direction is converged to an intermediate position between the land or groove on which the main beam is converged and the groove or land adjacent to the trailing side of recording in the disc radial direction,
Further, an objective lens for converging the other sub-light flux following the main light flux in the disc rotation direction to a position symmetrical with respect to the main light flux, and the main lens which is divided into two in the track crossing direction and is reflected from the optical disc. A main light receiving element that detects a light beam, two sub light receiving elements that are divided into two in the track crossing direction and detect two sub light beams reflected from the optical disk, and a push-pull signal from the detection result of the main light receiving element. Main push-pull signal generating means for generating Md, sub-push pull signal generating means for generating push-pull signals S1d, S2d of the respective sub-beams from the detection results of the two sub-light receiving elements, and the two sub-light receiving elements From the detection result of each sub-beam, a sub-sum signal generating means for generating sum signals S1s and S2s of each sub-beam, and an operation of Md + k ″ (S1s−S2s) (where k ″ is the main beam and the sub-beam). An optical disc, comprising: a tracking error signal generating means for generating a tracking error signal by a constant corresponding to the light quantity ratio of (1) and a track cross signal generating means for generating a track cross signal by the calculation S1d-S2d. apparatus. 9. A tracking method for an optical disc, wherein information is recorded or reproduced alternately on a land and a groove for each revolution of the rotationally driven optical disc, wherein a laser beam is a main light beam and a disc rotation direction with respect to the main light beam. Is divided into two sub-beams that are symmetrical before and after the main beam, and the main beam is converged on the land or groove of the optical disc, and one sub-beam that precedes the main beam in the disc rotation direction is the main beam. Is converged in the middle of the land or groove that is converged and the groove or land adjacent to the recording trailing side in the disk radial direction,
Further, the other sub-light flux following the main light flux in the disc rotation direction is converged to a position symmetrical with respect to the main light flux, and the push-pull signal of the main light flux reflected from the optical disc is Md, which is reflected from the optical disc. The push-pull signals of each of the two sub-beams that are generated are S1d and S2d, and the sum signals of the two sub-beams that are reflected from the optical disk are S1s,
S2s, where K and k "are constants corresponding to the light quantity ratio of the main light flux and the sub-light flux, Md-k (S1d + S2d) + k"
A tracking error signal is generated by (S1s-S2s) and a track cross signal is generated by S1d-S2d. 10. An optical disk device for recording or reproducing information alternately on a land and a groove for each revolution of a rotationally driven optical disk, comprising: a laser light source; and a laser beam emitted from the laser light source as a main light flux. A light beam splitting unit that splits the main light beam into two sub-light beams that are symmetrical in the front-back direction in the disc rotation direction, and converges the main light beam on a land or groove of the optical disc, and further discs than the main light beam. One of the sub-beams preceding in the rotational direction is converged to an intermediate position between the land or groove on which the main beam is converged and the groove or land adjacent to the trailing side of recording in the disc radial direction,
Further, an objective lens for converging the other sub-light flux following the main light flux in the disc rotation direction to a position symmetrical with respect to the main light flux, and the main lens which is divided into two in the track crossing direction and is reflected from the optical disc. A main light receiving element that detects a light beam, two sub light receiving elements that are divided into two in the track crossing direction and detect two sub light beams reflected from the optical disk, and a push-pull signal from the detection result of the main light receiving element. Main push-pull signal generating means for generating Md, sub-push pull signal generating means for generating push-pull signals S1d, S2d of the respective sub-beams from the detection results of the two sub-light receiving elements, and the two sub-light receiving elements From the detection result of the sub-beams, a sub-sum signal generating means for generating sum signals S1s and S2s of the respective sub-beams, and a calculation Md-k (S1d + S2d) + k "(S1s-S2s) ″ Is a constant corresponding to the light quantity ratio between the main light flux and the sub-light flux, etc.), and a tracking error signal generation means for generating a tracking error signal, and a track cross signal generation means for generating a track cross signal by the calculation S1d−S2d. An optical disk device comprising: 11. The optical disk according to claim 1, wherein the width ratio of the land to the groove is approximately 1: 1.
A method for tracking an optical disc according to 3, 5, 7 or 9. 12. The optical disk according to claim 2, wherein the land-to-groove width ratio is approximately 1: 1.
The optical disk device according to 4, 6, 8 or 10.