JP2001118274A - Recording medium, recording medium drive, and tilt detection method - Google Patents

Abstract

(57) [Summary] [Problem] To detect a tilt amount quickly and with high accuracy without providing a dedicated sensor. An optical disk reproducing apparatus includes: an optical pickup for reading digital data recorded on an optical disk; and an amplitude detection circuit for detecting an amplitude of a wobble component signal passed by a band-pass filter.
And a tilt detection circuit 24 for detecting a tilt amount. The optical disk reproducing device 10 has a wobble groove W
A groove portion G having a structure in which G and the straight groove portions SG are alternately connected is provided, and irradiation is performed on an optical disc in which one of both side walls of the recording area is a wobble groove portion WG and the other is a straight groove portion SG. The difference value of the amplitude of each wobble component signal based on the return light when the laser light is located on the inner circumference side and the outer circumference side of the optical disk with respect to the wobbling portion is obtained as a tilt instruction value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium on which digital data is recorded and a method for recording and / or recording digital data on a disk-shaped recording medium by rotating a disk-shaped recording medium.
Also, the present invention relates to a recording medium driving device for performing reproduction and a tilt detection method for detecting a tilt amount generated when the disk-shaped recording medium is rotationally driven.

[0002]

2. Description of the Related Art For example, a so-called CD (Compact Disc), DVD (Digital Versatile Disc or Digital Video) is used as a recording medium on which digital data is optically recorded.
Disc) and other optical discs are widely known.

An optical disk drive for recording and / or reproducing digital data on and from such an optical disk has a small spot where a laser beam is condensed by an optical pickup on a rotationally driven optical disk at a desired position. Irradiate and record and / or reproduce digital data. At this time, in order to stably record digital data on the optical disk or to faithfully reproduce the digital data recorded on the optical disk, the optical pickup makes the laser beam follow a track provided on the surface of the optical disk. Operate.

[0004]

However, in the above-mentioned optical disk, the optical disk may be warped by the influence of the environment such as temperature and humidity during use and / or storage, and may be caused by the warp of the optical disk due to the handling state or the tilt of the optical pickup in the optical disk drive. As a result, radial tilt may occur. Since this tilt causes aberration in the reproduction optical spot, distortion of the reproduction signal and MTF (Modulati
On transfer function) and recording power efficiency are known to be reduced.

In recent years, in order to increase the density of an optical disk, a numerical aperture (numerical aperture) of an objective lens in an optical pickup has been used in an optical disk drive.
e; NA) tends to be increased. For example, an objective lens having an NA value of 0.45 for a CD and an NA value of 0.60 for a DVD is used. Along with this, the thickness of the substrate of the optical disk has been reduced. For this reason, in the current situation, the optical disc is likely to be warped and has a large NA, so that the angle dependence of the aberration is also increasing.

On the other hand, in an optical disk drive, a dedicated sensor is provided to detect a tilt amount in order to compensate for the tilt, and an objective lens, an actuator and the like in an optical pickup are tilted based on the detected signal. Has been put to practical use.

However, in the conventional optical disk drive, if the optical disk has a small diameter, a place for installing a sensor for detecting the amount of tilt cannot be sufficiently secured, and it is difficult to detect the amount of tilt. there were.

The present invention has been made in view of the above circumstances, and solves the problem of the tilt detection method in the conventional optical disk drive, and quickly and accurately detects a tilt amount from a signal obtained by an optical pickup. The object of the present invention is to provide a recording medium drive device and a tilt detection method for quickly and highly accurately detecting a tilt amount from a signal obtained by an optical pickup using the recording medium, by using the recording medium capable of detecting the tilt. And

[0009]

A recording medium according to the present invention for achieving the above object is a recording medium on which digital data is recorded, and one of two side walls of a recording area on which recording data is recorded. On the other hand, signal information that can be distinguished from the recording data is recorded, and the width or the position is modulated on both side walls. A guide groove having a structure in which modulation guide grooves are alternately connected is provided, and one of both side walls of the recording area is a modulation guide groove and the other is a non-modulation guide groove.

In the recording medium according to the present invention, recording data is recorded in a modulation guide groove and a recording area in which one of the side walls is a modulation guide groove and the other is a non-modulation guide groove.

According to another aspect of the present invention, there is provided a recording medium driving apparatus in which signal information distinguishable from recording data is recorded on one of both side walls of a recording area in which recording data is recorded. A guide groove having a structure in which a modulation guide groove serving as a signal information recording side wall which is a side wall on which signal information is recorded by modulating a width or a position on both side walls, and a non-modulation guide groove which does not modulate both side walls are alternately connected. While rotating a disk-shaped recording medium in which one of the side walls of the recording area is a modulation guide groove and the other is a non-modulation guide groove,
A recording medium drive for recording and / or reproducing digital data on a disk-shaped recording medium, wherein the disk-shaped recording medium is irradiated with a laser beam and reflected and diffracted on the surface of the disk-shaped recording medium. Optical pickup means for receiving the returning light, amplitude detecting means for detecting the amplitude of a signal based on the returning light from the signal information recording side wall, and a laser beam detected by the amplitude detecting means being a disk larger than the signal information recording side wall. The amplitude of the first signal, which is a signal based on the return light from the signal information recording side wall when located on the inner peripheral side of the linear recording medium, and the laser light detected by the amplitude detecting means is a disk more than the signal information recording side wall For detecting the amount of tilt based on the amplitude of a second signal which is a signal based on the return light from the signal information recording side wall when located on the outer peripheral side of the linear recording medium It is characterized in that output and means.

[0012] The recording medium driving apparatus according to the present invention detects tilt based on the amplitude of the first signal and the amplitude of the second signal based on the return light from the signal information recording side wall in the disc-shaped recording medium. The tilt amount is detected by the means.

Further, in the tilt detecting method according to the present invention for achieving the above-mentioned object, according to the tilt detecting method, signal information distinguishable from the recording data is recorded on one of both side walls of a recording area where the recording data is recorded. A guide groove having a structure in which a modulation guide groove serving as a signal information recording side wall, which is a side wall on which signal information is recorded by modulating a width or a position on a wall, and a non-modulation guide groove which does not modulate both side walls, is provided. A laser beam is applied to a disc-shaped recording medium in which one of both side walls of the recording area is a modulation guide groove and the other is a non-modulation guide groove, and is reflected and diffracted on the surface of the disc-shaped recording medium. Receiving the returning light, detecting the amplitude of the signal based on the returning light from the signal information recording side wall, and detecting the detected laser light on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. The amplitude of the first signal, which is a signal based on the return light from the signal information recording side wall, and the signal light from the signal information recording side wall when the detected laser light is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. The tilt amount is detected based on the amplitude of a second signal that is a signal based on the return light.

In the tilt detecting method according to the present invention, the tilt amount is determined based on the amplitude of the first signal and the amplitude of the second signal based on the return light from the signal information recording side wall of the disc-shaped recording medium. To detect.

[0015]

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

In this embodiment, a recording medium driving apparatus according to the present invention is used, for example, in a CD (Compact Disc) or a DVD.
(Digital Versatile Disc or Digital Video Dis
c) The present invention is applied to an optical disk reproducing apparatus for reproducing digital data from an optical disk which is a disk-shaped recording medium on which digital data such as MD (Mini Disk, a product name of Sony Corporation) is recorded. First, the principle of the tilt detection method performed by the optical disc reproducing apparatus will be described.

As shown in FIG. 1, a preferred optical disc to which the present invention is applied has a groove which is a guide groove in which a wobble always exists on one side with respect to a recording area. That is, this optical disc is, for example, FM-modulated (Fr
signal information recording side wall W wobbled with address information, which is signal information that has been subjected to frequency modulation.
Groove WG which is a modulation guide groove having a wobble on both sides, and a straight groove portion (straight groov) which is a non-modulation guide groove having no wobble.
e) Groove portion G having a structure in which SG and SG are alternately connected.
Is provided. In this optical disk, one of both side walls of the recording area has a wobble groove portion WG.
And the wobble groove portion W in an arbitrary groove portion G so that the other is a straight groove portion SG.
G is provided with a groove portion G so as to be adjacent to the straight groove portion SG in the adjacent groove portion G. Further, in the optical disk, the groove portion G and the adjacent groove portion G have tracks T _n−1 , T _n , T _{n + 1} ,.
And these tracks are used as recording areas.

The area A in FIG. 1 of such an optical disc has a structure as shown in FIG. 2, for example. That is, considering the extension curve from the wobble groove portion WG in the arbitrary groove portion G to the straight groove portion SG as shown by a broken line portion BL _{1 in} the figure, the wobble groove portion WG in the adjacent groove portion G is considered.
It is linked to a straight groove portion SG a shape axisymmetric in the broken line BL ₂ is a curve of the same shape as the broken line BL _1. The structure of the groove portion G in FIG.
It is an example and is not limited.

In the following description, if necessary, as shown in FIG. 3, the beam spot in the case where the wobble groove portion WG is located on the inner peripheral side of the optical disk with respect to the laser beam from the optical pickup (not shown) will be described. Spot S
It is _A, the beam spot in the case on the outer peripheral side of the optical disk and the spot S _B. Each of these beam spots is a Gaussian beam whose intensity distribution exhibits a Gaussian distribution. Furthermore, in the following description, if necessary, the track the spot S _A is irradiated with the track T _A, the track the spot S _B is irradiated with the track T _B.

FIG. 4 shows the result of numerical calculation of the change in the intensity distribution of the laser beam due to the tilt.

[0021] The spot S _B to be irradiated on the optical disk,
When the irradiation is normally performed without being affected by the tilt, that is, when the tilt amount is “0 °”, the wobble whose intensity distribution is located on both sides as shown by a solid line portion C _0B in FIG. Groove part WG and straight groove part SG
With respect to. Therefore, the return light reflected and diffracted by the disc surface, a symmetrical central position of the track T _B in the radial direction of the optical disk.

On the other hand, due to the distortion due to the aberration influenced by a tilt, the spot irradiated on the optical disc S _B is in a state inclined in the direction of the wobbled groove portion WG,
For example, as shown in broken line in the drawing unit C _0.6B or drawing in chain line portion C _1.2B. In other words, the spot is irradiated to the optical disk S _B, when the tilt amount "0.6 °" is "1.2 °", respectively, in FIG broken line C _0.6B, chain line portion C
_As shown in _1.2B , in both cases, the intensity distribution becomes asymmetric with respect to the wobble groove portion WG and the straight groove portion SG located on both sides, and the intensity of the laser beam applied to the wobble groove portion WG is normally applied. And the intensity of the laser beam applied to the straight groove portion SG becomes higher than that in the case where the laser beam is normally applied. This tendency becomes more remarkable as the tilt amount increases. Therefore, the return light reflected and diffracted on the disk surface becomes asymmetric with respect to the wobble groove portion WG and the straight groove portion SG located on both sides, and the return light from the wobble groove portion WG and the straight groove portion SG located on both sides. intensity I _0.6B, I _1.2B also different from each other.

Furthermore, influenced by the tilt, the spot S _A which is applied to the optical disk in a state inclined in the direction of the straight groove portion SG, although not shown, the wobble groove portion WG and straight its intensity distribution is located on both sides It becomes asymmetric with respect to the groove portion SG, the intensity of the laser beam applied to the wobble groove portion WG becomes higher than that when the laser beam is normally applied, and the straight groove portion S
The intensity of the laser light applied to G becomes lower than that in the case of normal irradiation. Therefore, the return light reflected and diffracted on the disk surface becomes asymmetric with respect to the wobble groove portion WG and the straight groove portion SG located on both sides, and the return light from the wobble groove portion WG and the straight groove portion SG located on both sides. The strengths are also different.

FIG. 5 shows the result of numerical calculation of the characteristics of the signal based on the return light from the wobble groove portion WG when the optical disk is irradiated with laser light while actually changing the tilt amount. Here, the wobble component signal which is a signal based on the return light from the wobble groove portion WG with respect to the tilt amount is different from the wobble groove portion WG.
ADIP given to signal information recording side wall W in
(ADress In Pre-groove).

[0025] The curve obtained by plotting the change in the amplitude of the signal based on the return light from the wobbled groove portion WG by spot S _A (wobble component signal SIG _A) relative tilt quantity and curve C _A, a wobble due to the spot S _B for the amount of tilt When the amplitude plotted curve changes in signal based on the return light from the groove portion WG (wobble component signal SIG _B) and the curve C _B, as shown in the figure, the amplitude of the wobble component signal SIG _a, wobble component The amplitude of the signal SIG _B depends on the amount of tilt, and the amount of tilt is “0 °”.
It tends to be symmetric about the case of. Then, with these wobble component signal SIG _A, if the signal represented by the difference between the wobble component signal SIG _B and tilt detection signal SIG _T, as represented by the curve C _T, the tilt amount "0 °" And “about -0.75
A linear characteristic can be obtained in the range of ゜ to about +0.75 ゜. The pull-in range is “about -1.2 ゜ to about +1.2 ゜”.

The optical disk reproducing apparatus 10 shown in FIG. 6 as an embodiment of the present invention detects the amount of tilt by using such characteristics and compensates for it.

As shown in FIG. 1, the optical disk reproducing apparatus 10 includes an optical pickup 11 for reading digital data recorded on an optical disk (not shown) and a current-voltage conversion (IV conversion) of a signal output from the optical pickup 11. Iv) an IV conversion circuit 12, a servo circuit 13 for controlling the optical pickup 11 to keep the distance to the optical disk constant, and controlling a rotation driving operation of a spindle motor (not shown), and passing a signal of a desired frequency component. Band Pass Filter
r; BPF) 14, a peak envelope detection circuit 15 for detecting the peak envelope of the wobble component signal passed by the band-pass filter 14, and a bottom for detecting the bottom envelope of the wobble component signal passed by the band-pass filter 14. Envelope detection circuit 1
6, the peak envelope and the bottom envelope detection circuit 1 detected by the peak envelope detection circuit 15
6, a subtractor 17 for obtaining a difference from the bottom envelope detected by the control unit 6, an amplitude detection circuit 18 for detecting the amplitude of the wobble component signal based on an output from the subtractor 17,
A track discrimination circuit 19 for the wobble component signal passed by the band pass filter 14 to determine due to return light from either the track T _B is due to return light from the track T _A, is passed by the band pass filter 14 An address detection circuit 20 for extracting an address recorded on the optical disk from the wobble component signal and detecting the address.
RF (Radio Frequency) input from V conversion circuit 12
An equalizer 21 for performing a waveform equalization process on the signal; a data determination circuit 22 for extracting data from the signal input from the equalizer 21 to determine a data detection capability; and a tilt detected by a tilt detection circuit 24 described later. A target value setting circuit 23 for setting a target value for compensating a tilt instruction value indicating the amount, a tilt detection circuit 24 for detecting a tilt amount, and a focus coil 27a of the optical pickup 11 for tilt compensation. , 27b for generating a drive signal for driving the drive signals.

The optical pickup 11 includes an objective lens 26 for condensing laser light from a laser diode 29, focus coils 27a and 27b for tilting the objective lens 26 with respect to the optical disk, and these focus coils 27a and 27b. Objective lens 2 by electromagnetic force
6, a laser diode (LD) 29 that emits laser light, and internally reflects the return light that transmits the laser light emitted from the laser diode 29 and is reflected and diffracted on the optical disk surface. And a photodiode (PD) 31 for receiving return light reflected and diffracted on the optical disk surface and incident by the prism 30.

The objective lens 26 includes a laser diode 29
From the laser beam and irradiates the optical disk (not shown).

The focus coils 27a and 27b are for tilting the objective lens 26 with respect to the optical disk. These focus coils 27a, 27
A current having a magnitude based on the drive signal supplied from the drive signal generation circuit 25 flows through b. The focus coils 27a and 27b respectively drive the actuator 28 in a direction to compensate for tilt by an electromagnetic force generated by an effect with a magnet (not shown).

The actuator 28 drives the objective lens 26 to track the objective lens 26 at a desired position on an optical disk (not shown).
Further, the actuator 28 includes the focus coil 27
The objective lens 26 is tilted with respect to the optical disk by the electromagnetic force of a and 27b.

The laser diode 29 has, for example, a light emitting portion made of a semiconductor laser, and emits laser light. The laser light emitted from the laser diode 29 enters the prism 30.

The prism 30 receives and transmits the laser light emitted from the laser diode 29,
6, the return light reflected and diffracted on the surface of the optical disk is incident and internally reflected, and the photodiode 3
Emitted to 1.

The photodiode 31 has a photodetector and a photoelectric conversion unit, receives the return light reflected and diffracted on the optical disk surface and made incident by the prism 30, converts the light into an electric signal, and outputs the electric signal to the IV conversion circuit 12 at the subsequent stage. I do.

The optical pickup 11 irradiates the optical disk (not shown) with the laser light emitted from the laser diode 29 and receives return light reflected and diffracted on the surface of the optical disk, thereby recording data on tracks on the surface of the optical disk. Read out the digital data. In addition, as shown in FIG. 7, the optical pickup 11 actually has two sub beam spots SS ₁ and S 2 in addition to the spot S _A (spot S _B ) serving as the main beam spot.
Irradiating the optical disc (not shown) S _2, having an optical system for receiving a return light reflected and diffracted by the optical disk surface. These sub beam spots SS ₁ and SS ₂ are respectively radiated onto the straight groove portion SG or the wobble groove portion WG according to the position of the main beam spot. The return light obtained by reflecting and diffracting the sub beam spots SS ₁ and SS ₂ on the optical disc surface is used for the track discrimination of the main beam spot by the track discrimination circuit 19. Further, the optical pickup 11 outputs a focus error signal indicating a focus error of the objective lens 26 to the drive signal generation circuit 25.

The IV conversion circuit 12 includes the photodiode 3
The signal output from 1 is subjected to current-voltage conversion. The IV conversion circuit 12 converts the signal obtained by the conversion into a servo circuit 13 in the subsequent stage.
And output to the bandpass filter 14. Further, the IV conversion circuit 12 outputs the RF signal obtained by the conversion to the equalizer 21 at the subsequent stage.

The servo circuit 13 drives the optical pickup 11 based on the signal supplied from the IV conversion circuit 12 so as to focus the optical pickup 11 so as to keep the distance from the optical disk constant, and controls the rotational driving operation of a spindle motor (not shown). I do.

The band-pass filter 14 is an IV conversion circuit 1
2 of the wobble groove portion WG
In order to extract the wobble component signal from the RF signal component, the RF signal component and other noise components are cut off, and a signal having a desired frequency component is passed. The wobble component signal passed by the band-pass filter 14 is supplied to a peak envelope detection circuit 15, a bottom envelope detection circuit 16, a track discrimination circuit 19, and an address detection circuit 20 at the subsequent stage.

The peak envelope detection circuit 15 detects the peak envelope of the wobble component signal passed by the band pass filter 14. The peak envelope detection circuit 15 outputs the detected peak envelope to the subsequent-stage subtractor 17.

The bottom envelope detection circuit 16 detects the bottom envelope of the wobble component signal passed by the band pass filter 14. The bottom envelope detection circuit 16 outputs the detected bottom envelope to a subtractor 17 at the subsequent stage.

The subtracter 17 calculates the difference between the peak envelope supplied from the peak envelope detection circuit 15 and the bottom envelope supplied from the bottom envelope detection circuit 16, and outputs the obtained difference signal to the amplitude detection circuit 18 at the subsequent stage. Output.

The amplitude detection circuit 18 detects the amplitude of the wobble component signal based on the difference signal supplied from the subtracter 17. The amplitude detection circuit 18 outputs an amplitude detection signal indicating the detected amplitude to the subsequent tilt detection circuit 24.

[0043] or a track discrimination circuit 19, a wobble component signal passed by the band pass filter 14, is due to return light from the track T _A like the spot S _A described above, the track as a spot S _B or it determines by return light from the T _B.

Specifically, the track discriminating circuit 19 discriminates the track of the main beam spot as follows. For example, the spot S which is the main beam spot
_Assuming that _A is irradiated as shown in FIG. 7 earlier, the signal based on the return light by the sub-beam spot SS ₂ is transmitted by the signal information recording side wall W wobbled with the FM-modulated address information. It has a certain frequency due to the influence. Therefore, a signal obtained by filtering this signal by the band-pass filter 14 has a predetermined amplitude value. On the other hand, the signal based on the return light by the sub beam spot SS _1, since it is intended to include only a DC component, the amplitude value of a signal obtained by filtering this signal by the band pass filter 14 is substantially "0". Accordingly, the track discriminating circuit 19 converts the signal based on the return light from each of the sub-beam spots SS ₁ and SS ₂ into a band-pass filter 14.
By by comparing the signal obtained by filtering, it is possible to a main beam spot to determine whether the spot S _B is a spot S _A.

The track discriminating circuit 19 outputs a track discriminating signal indicating the result of discriminating the track to the subsequent address detecting circuit 20 and tilt detecting circuit 24.

The address detection circuit 20 extracts and detects the address recorded on the optical disk from the wobble component signal passed by the band pass filter 14. At this time, based on the track discrimination signal supplied from the track discrimination circuit 19, the address detection circuit 20 determines whether the detected address is due to the return light from the track T _A like the spot S _A or the spot S _B Like truck T _B
It is determined whether or not this is due to the return light from the camera.

The equalizer 21 receives the RF signal from the IV conversion circuit 12 and performs, for example, a waveform equalization process for correcting a jitter error of the RF signal. This equalizer 21
Adjusts the gain based on a tilt error signal supplied from a tilt detection circuit 24 described later,
Compensation for lowering of Transfer Function). The equalizer 21 outputs the signal on which the waveform equalization processing has been performed to the data determination circuit 22 at the subsequent stage.

The data discriminating circuit 22 extracts data from the signal input from the equalizer 21 and discriminates a data detecting ability such as a jitter error. Data discrimination circuit 22
A data determination signal indicating the result of determining the data detection capability is provided to a target value setting circuit 23 and a tilt detection circuit 24 in the subsequent stage.
Output to

The target value setting circuit 23 includes a data discriminating circuit 2
2, a target value for compensating for a tilt instruction value indicating the tilt amount detected by the tilt detection circuit 24 is set. The target value setting circuit 23 outputs the set target value to the subtractor 35 of the tilt detection circuit 24.

The tilt detection circuit 24 includes a switch 32 for opening and closing based on the sample pulses generated from the sample pulse circuit, not shown, the amplitude of the wobble component signal only by the return light from the track T _A like the spot S _A an amplitude detection circuit 33a for detecting, from the track T _B like the spot S _B and an amplitude detection circuit 33b for detecting the amplitude of the wobble component signal only by the return light, from the track T _a detected by the amplitude detection circuit 33a The amplitude value of the wobble component signal due to the return light and the amplitude detection circuit 33b
A subtractor 34 for obtaining the difference between the amplitude value of the wobble component signal by the return light from the track T _B detected by the difference value and the target value setting circuit 2 which is supplied from the subtractor 34
And a subtractor 35 for obtaining a difference from the target value supplied from the third unit.

The switch 32 opens and closes based on a sample pulse generated from a sample pulse circuit (not shown), and connects or disconnects the amplitude detection circuit 18 with the amplitude detection circuit 33a or 33b. Specifically, the sample pulse circuit, not shown, detects that the main beam spot has moved from the track T _A to the track T _B, the sample pulse occurs immediately supplied to the switch 32. The switch 32 connects the amplitude detection circuit 18 and the amplitude detection circuit 33b based on the sample pulse. When detecting that the main beam spot has moved from the track T _B to the track T _A , the sample pulse circuit (not shown) immediately generates a sample pulse and supplies it to the switch 32. The switch 32 controls the amplitude detection circuit 18 and the amplitude detection circuit 33 based on the sample pulse.
and a.

The amplitude detection circuit 33a includes the amplitude detection circuit 18
Enter the amplitude detection signal indicating the detected amplitude by, detecting the amplitude of the wobble component signal only by the return light from the track T _A. The amplitude detection circuit 33a outputs an amplitude signal indicating the detected amplitude value to the subsequent-stage subtractor 34.

The amplitude detection circuit 33b includes the amplitude detection circuit 18
Enter the amplitude detection signal indicating the detected amplitude by, detecting the amplitude of the wobble component signal only by the return light from the track T _B. The amplitude detection circuit 33b outputs an amplitude signal indicating the detected amplitude value to the subsequent subtractor.

The subtractor 34 calculates the amplitude value indicated by the amplitude signal supplied from the amplitude detection circuit 33a and the amplitude detection circuit 33b.
And the difference from the amplitude value indicated by the amplitude signal supplied from.
The subtractor 34 outputs the tilt instruction value, which is the obtained difference value, to the subtractor 35 at the subsequent stage.

The subtractor 35 calculates a difference between the tilt instruction value supplied from the subtractor 34 and the target value supplied from the target value setting circuit 23, and outputs a tilt error signal represented by the difference value at a subsequent stage. The signal is output to the equalizer 21 and the drive signal generation circuit 25.

The tilt detection circuit 24 detects the amount of tilt based on the amplitude detection signal of the wobble component signal supplied from the amplitude detection circuit 18 and the track discrimination signal supplied from the track discrimination circuit 19. , And outputs the generated tilt error signal to the equalizer 21 and the drive signal generation circuit 25.

The drive signal generation circuit 25 adds the focus error signal supplied from the optical pickup 11 and the tilt error signal supplied from the tilt detection circuit 24, and the adder 36 supplied from the optical pickup 11. A subtractor 3 that calculates the difference between the focus error signal and the tilt error signal supplied from the tilt detection circuit 24
7, a drive circuit 38a that generates a drive signal indicating the magnitude of the current flowing through the focus coil 27a based on the added value supplied from the adder 36, and a focus coil based on the difference value supplied from the subtractor 37. And a drive circuit 38b for generating a drive signal indicating the magnitude of the current flowing through 27b.

The adder 36 calculates the sum of the focus error signal indicating the focus error of the objective lens 26 supplied from the optical pickup 11 and the tilt error signal supplied from the tilt detection circuit 24, and drives the added value. Output to the circuit 38a.

The subtractor 37 calculates the difference between the focus error signal indicating the focus error of the objective lens 26 supplied from the optical pickup 11 and the tilt error signal supplied from the tilt detection circuit 24, and drives the difference value. Output to the circuit 38b.

The drive circuit 38a generates a drive signal indicating the magnitude of the current flowing through the focus coil 27a based on the added value supplied from the adder 36. The drive circuit 38a outputs the generated drive signal to the focus coil 27a.

The drive circuit 38b generates a drive signal indicating the magnitude of the current flowing through the focus coil 27b based on the difference value supplied from the subtractor 37. The drive circuit 38b outputs the generated drive signal to the focus coil 27b.

Such a drive signal generation circuit 25
A drive signal for compensating tilt is generated and output to the focus coils 27a and 27b.

The optical disk reproducing apparatus 10 having the above-described components is configured to perform the track T _A like the spot S _A described above.
The wobble component signal SIG _A in the case where the laser beam is irradiated, the wobble component signal in the case where the laser beam is irradiated on the track T _B like the spot S _B SIG _B
Sampling the bets, the difference by the tilt detection circuit 24, a wobble component signal SIG _A in the case where the laser beam is irradiated on the track T _A, a wobble component signal SIG _B in the case where the laser beam is irradiated on the track T _B A tilt instruction value represented by a value is obtained, and the optical pickup 11 is controlled and driven so that the tilt instruction value approaches the target value set by the target value setting circuit 23.

Here, in the optical disk reproducing apparatus 10, a value set arbitrarily in advance or a value recorded in a control track which is a control information recording area of the optical disk may be used as the target value. 1
0 is an initial operation at the time of loading the optical disc,
The target value can be set by the following method.

The optical disk reproducing apparatus 10 transmits a drive signal to the focus coil 2 when loading the optical disk.
7a and 27b, and drive the actuator 28 of the optical pickup 11 while changing it. Then, the optical disc reproducing apparatus 10 obtains a tilt instruction value according to the change of the tilt amount by the tilt detection circuit 24, and sequentially supplies the tilt instruction value to the target value setting circuit 23. Further, the optical disk reproducing device 10 includes a target value setting circuit 23.
Thus, the correlation between the tilt instruction value supplied from the tilt detection circuit 24 and the data detection error based on the data determination signal supplied from the data determination circuit 22 is measured.
Then, the optical disk reproducing device 10 sets the target value setting circuit 2
According to 3, the tilt instruction value that minimizes the data detection error is set as the target value.

As described above, the optical disk reproducing apparatus 10
Can set an optimal target value based on the correlation between the tilt instruction value and the data detection error.

The optical disk reproducing apparatus 10 is, specifically,
According to the method described below, the wobble component signal
_A and the wobble component signal SIG _B are sampled to detect a tilt amount.

As shown in FIG. 8 (A), the optical disk reproducing apparatus 10 operates in the same manner as in the normal reproduction.
1 by irradiating a main beam spot on the track T _n. Track T _n in the figure, when expressed using the track T _A and the track T _B described above, the track T _B - track T _A - track T _B - since it has a track T _A, the main beam spot, When expressed using the spot S _A and the spot S _B , the spot S _B −the spot S _A
-Spot S _B -Spot S _A That is, the optical disk reproducing apparatus 10, usually similar to the time of reproduction, by irradiating a main beam spot on the same track T _n by the optical pickup 11, the main beam spot is the spot S _A
And generating alternately if the spot S _B.

[0069] At this time, if the spot S _A and the spot S _B is applied to the optical disk normally without being influenced by the tilt, that is, when the tilt amount is "0 °", the band-pass filter 14 wobble component signal passed by is observed as shown in FIG. (B), and the wobble component signal SIG _a based on the return light from the wobbled groove portion WG by spot S _a, the spot S _B by the wobbled groove portion WG The amplitude of the wobble component signal SIG _B based on the return light from is the same as that of the wobble component signal SIG _B.

[0070] On the other hand, the spot S _A and the spot S _B is influenced by a tilt, if it is applied to the optical disk in a state inclined in the direction of the wobbled groove portion WG is wobble component that is passed by the band pass filter 14 signals are observed as shown in FIG. (C), and the wobble component signal SIG _a based on the return light from the wobbled groove portion WG by spot S _a, based on the return light from the wobbled groove portion WG by spot S _B Wobble component signal S
The amplitude differs from IG _B.

Therefore, the amplitudes of the wobble component signals SIG _A and SIG _B shown in FIG. 9C are detected by the amplitude detection circuits 33 a and 33 _b of the tilt detection circuit 24 and supplied to the subtractor 34. As shown in FIG. 3D, the amplitude changes like an edge in accordance with the movement of the main beam spot. In FIG. 3D, the amplitude value of the wobble component signal is represented by L (I), and L (I + 1), L (I + 1),
L (I + 2),...

The optical disc reproducing apparatus 10 detects a tilt instruction value, which is a difference value obtained by the subtractor 34 of the tilt detection circuit 24, based on the amplitude signal as shown in FIG. . That is, the optical disk reproducing device 10 irradiates the main beam spot on each of the certain continuous tracks T _A and T _B on the track T _n by the optical pickup 11, and the amplitude values L (I), L ( I + 1) is detected, and the amplitude value L (I−I) of the wobble component signal detected in the previous period is detected.
2) Using L (I-1), the subtractor 34 of the tilt detection circuit 24 calculates L (I-1) -L (I-2) to obtain a tilt instruction value. A tilt error signal is generated based on the value. Then, the optical disk reproducing apparatus 10, the amplitude value of the next successive track T _A and the track T wobble component signal by irradiating each of _B on the track T _n the main beam spot by the optical pickup 11 L (I + 2), L During the period of detecting (I + 3), the amplitude value L of the previously detected wobble component signal
Using (I) and L (I + 1), a tilt instruction value is obtained by the tilt detection circuit 24 to generate a tilt error signal. The optical disk reproducing device 10 repeats such an operation a plurality of times. Incidentally, discrimination between the wobble component signal SIG _B in the case where the wobble component signal SIG _A in the case where the laser beam is irradiated on the track T _A, the track T _B is the laser beam is irradiated is performed by the track discrimination circuit 19 This is as described above.

As described above, the optical disk reproducing apparatus 10
Can be compensated by detecting the amount of tilt. By detecting the amount of tilt in this way, the optical disk reproducing device 10 can quickly detect the amount of tilt without waiting for the rotation of the optical disk. In addition, the optical disk reproducing device 10 obtains a plurality of tilt instruction values during one rotation of the optical disk, so that the tilt amount can be detected with high accuracy.

That is, for example, when the amplitude values of the wobble component signals in the track T _A and the track T _B are stored and calculated later, the tilt amount of at least two rotations is detected separately from the normal operation. Since it requires time and calculation time, when seeking from the innermost circumference where the tilt amount is small to the outermost circumference where the tilt amount is large on the optical disc,
A rotation waiting time of 2 rotations + α is required, which causes a problem of lowering the effective access speed.

Further, when the tilt amount is detected based on one sample information during one rotation of the optical disk, there is a problem that it is not possible to follow the rotation fluctuation. For example, in the case of an optical disk rotating at 600 rpm, There is a problem that the time constant is increased to about 2 seconds. Further, in a case where only one of the tracks T _A and T _B is continuously reproduced,
There is a problem that the tilt amount cannot be detected.

The optical disk reproducing apparatus 10 can solve such a problem, and can quickly perform high-precision tilt detection and compensation without performing complicated operations.

As described above, the optical disk reproducing apparatus 10 has the groove portion G having a structure in which the wobble groove portion WG and the straight groove portion SG are connected alternately.
The optical disk provided with the groove portion G is provided so that the wobble groove portion WG in the arbitrary groove portion G is adjacent to the straight groove portion SG in the adjacent groove portion G in the same manner as during normal reproduction. , successive tracks T _a and the track T _B in the main beam spot on the track T _n by the optical pickup 11
By irradiating each of them, and detecting the return light thereof, tilt detection and compensation can be performed without providing a dedicated sensor for tilt detection. For this reason, the optical disc reproducing apparatus 10 controls the numerical aperture (Nume
It is possible to detect and compensate for the amount of tilt even for an optical disk that is thin and has a small diameter with an increase in rical aperture (NA).

The present invention is not limited to the above-described embodiment. For example, the present invention can be applied not only to an optical disk reproducing apparatus for reproducing digital data from an optical disk but also to a recording apparatus for recording digital data on an optical disk. Of course, it is possible.

As described above, it goes without saying that the present invention can be appropriately changed without departing from the spirit of the present invention.

[0080]

As described in detail above, the recording medium according to the present invention is a recording medium on which digital data is recorded, wherein one side wall of both side walls of a recording area on which the recording data is recorded is provided. A modulation guide groove in which signal information that can be distinguished from recording data is recorded, and a width or a position is modulated on both side walls, and a signal information recording side wall is a side wall on which signal information is recorded, and a non-modulation guide that does not modulate both side walls. A guide groove having a structure in which grooves are alternately connected is provided, and one of both side walls of the recording area is a modulation guide groove and the other is a non-modulation guide groove.

Therefore, the recording medium according to the present invention
Recording data is recorded in a modulation guide groove and a recording area in which one of the side walls is a modulation guide groove and the other is a non-modulation guide groove. Therefore, an apparatus that drives the recording medium to rotate and records and / or reproduces digital data on the recording medium is based on the amplitude and the amplitude of the first signal based on the return light from the signal information recording side wall of the recording medium. The tilt amount can be detected based on the amplitude of the second signal, and the tilt can be detected quickly and with high accuracy without providing a dedicated sensor for tilt detection.

Further, in the recording medium driving device according to the present invention, signal information distinguishable from the recording data is recorded on one of the two side walls of the recording area where the recording data is recorded,
A modulation guide groove as a signal information recording side wall which is a side wall on which signal information is recorded by modulating the width or position on both side walls,
A disc-shaped recording medium in which a guide groove having a structure in which non-modulation guide grooves that do not modulate both side walls are alternately provided, and one of both side walls of the recording area is a modulation guide groove and the other is a non-modulation guide groove. Is a recording medium driving device for rotating and driving the disc-shaped recording medium to record and / or reproduce digital data on the disc-shaped recording medium. Optical pickup means for receiving return light reflected and diffracted by the surface, amplitude detection means for detecting the amplitude of a signal based on the return light from the signal information recording side wall, and laser light detected by the amplitude detection means The amplitude of the first signal, which is a signal based on the return light from the signal information recording side wall when located on the inner peripheral side of the disc-shaped recording medium with respect to the recording side wall, and is detected by the amplitude detecting means. The tilt amount is detected based on the amplitude of a second signal which is a signal based on the return light from the signal information recording side wall when the obtained laser beam is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. And a tilt detecting means.

Therefore, the recording medium driving device according to the present invention provides tilt detecting means based on the amplitude of the first signal and the amplitude of the second signal based on the return light from the signal information recording side wall of the disk-shaped recording medium. Thus, the tilt amount can be detected, and the tilt can be detected quickly and accurately without providing a dedicated sensor for tilt detection.

Further, in the tilt detecting method according to the present invention, signal information that can be distinguished from the recording data is recorded on one of the side walls of the recording area where the recording data is recorded,
A modulation guide groove as a signal information recording side wall which is a side wall on which signal information is recorded by modulating the width or position on both side walls,
A disc-shaped recording medium in which a guide groove having a structure in which non-modulation guide grooves that do not modulate both side walls are alternately provided, and one of both side walls of the recording area is a modulation guide groove and the other is a non-modulation guide groove. Irradiates a laser beam to the disc, receives the return light reflected and diffracted on the surface of the disc-shaped recording medium, detects the amplitude of a signal based on the return light from the signal information recording side wall, and detects the detected laser light. The amplitude of the first signal, which is a signal based on the return light from the signal information recording side wall when the signal information recording side wall is located on the inner peripheral side of the signal information recording side wall, and the detected laser beam are reflected from the signal information recording side wall. Also, the tilt amount is detected based on the amplitude of the second signal, which is a signal based on the return light from the signal information recording side wall when located on the outer peripheral side of the disc-shaped recording medium.

Accordingly, the tilt detecting method according to the present invention detects the amount of tilt based on the amplitude of the first signal and the amplitude of the second signal based on the return light from the signal information recording side wall in the disc-shaped recording medium. This makes it possible to quickly and accurately detect tilt without requiring a dedicated sensor for tilt detection.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical disk applied to an optical disk reproducing device shown as an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the optical disc shown in FIG. 1, illustrating a state where an area A in FIG. 1 is enlarged;

FIG. 3 is a diagram illustrating the arrangement of beam spots.

FIG. 4 is a diagram illustrating a result obtained by calculating a change in intensity distribution of a laser beam due to tilt by numerical calculation.

FIG. 5 is a diagram illustrating a relationship between a wobble component signal and a tilt amount, and is a result obtained by numerical calculation of a characteristic of the wobble component signal when the optical disk is irradiated with laser light while actually changing the tilt amount. FIG.

FIG. 6 is a block diagram illustrating a configuration of the optical disc reproducing device.

FIG. 7 is a diagram illustrating an arrangement of a main beam spot and a sub beam spot.

8A and 8B are diagrams illustrating a method of detecting a tilt amount by sampling a wobble component signal, wherein FIG. 8A illustrates a state of movement of a main beam spot, and FIG. (C) shows a wobble component signal in the case of being affected by tilt, (D) shows an amplitude signal, and (E) shows a detected tilt instruction value. FIG.

[Explanation of symbols]

Reference Signs List 10 optical disk reproducing device, 11 optical pickup, 18, 33a, 33b amplitude detecting circuit, 19
Track discriminating circuit, 21 equalizer, 22 data discriminating circuit, 23 target value setting circuit, 24 tilt detecting circuit, 25 drive signal generating circuit, 26 objective lens, 29 laser diode, 31 photodiode

Claims (27)

[Claims] 1. A recording medium on which digital data is recorded, wherein signal information distinguishable from the recording data is recorded on one of two side walls of a recording area on which the recording data is recorded. A guide groove having a structure in which a modulation guide groove serving as a signal information recording side wall which is a side wall on which the signal information is recorded by modulating a width or a position and a non-modulation guide groove which does not modulate both side walls is alternately connected. A recording medium, wherein one of both side walls of the recording area is the modulation guide groove and the other is the non-modulation guide groove. 2. The recording medium according to claim 1, wherein address information as the signal information is recorded on the signal information recording side wall. 3. The method according to claim 1, wherein the shape is a disk.
Recording medium according to the above. 4. A signal information that can be distinguished from the recording data is recorded on one side wall of both sides of a recording area where recording data is recorded, and the signal information is recorded by modulating a width or a position on both side walls. A guide groove having a structure in which modulation guide grooves serving as signal information recording side walls, which are the side walls, and non-modulation guide grooves that do not modulate both side walls are provided alternately, and one of both side walls of the recording area is provided. A recording medium driving device for rotating and driving a disk-shaped recording medium that is the modulation guide groove and the other is the non-modulation guide groove, and records and / or reproduces digital data on the disk-shaped recording medium. An optical pickup means for irradiating the disc-shaped recording medium with a laser beam and receiving return light reflected and diffracted on the surface of the disc-shaped recording medium; Amplitude detection means for detecting the amplitude of a signal based on the return light of the laser beam; and wherein the laser light detected by the amplitude detection means is located on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. The amplitude of the first signal, which is a signal based on the return light from the signal information recording side wall, and the laser light detected by the amplitude detecting means is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. And a tilt detecting means for detecting a tilt amount based on the amplitude of a second signal which is a signal based on the return light from the signal information recording side wall in the case where the recording medium is driven. 5. The optical pickup means irradiates the same recording area with the laser light, and when the laser light is located on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall, And a case where the laser beam is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. The tilt detecting means detects the amplitude of the first signal detected by the amplitude detecting means. 5. The recording medium driving device according to claim 4, wherein a difference value between the amplitude and the amplitude of the second signal detected by the amplitude detection means is obtained as a tilt instruction value indicating the tilt amount. 6. The recording medium drive according to claim 4, wherein address information as the signal information is recorded on the signal information recording side wall of the disc-shaped recording medium. 7. A first recording area which is a recording area irradiated by the laser light when the laser light is located on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall;
A second recording area which is continuous with the first recording area and is a recording area irradiated with the laser light when the laser light is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. 5. The recording medium drive according to claim 4, further comprising a recording area discriminating unit for discriminating the area. 8. The tilt detecting means moves the laser beam over the first recording area and the second recording area by the optical pickup means, and controls the tilt of the first signal and the amplitude of the first signal. During the period in which the amplitude of the second signal is detected by the amplitude detecting means, the amplitude of the first signal detected by the amplitude detecting means in the preceding period and the second signal are detected.
8. The recording medium driving device according to claim 7, wherein a difference value from the amplitude of the recording medium is obtained. 9. The recording medium driving device according to claim 4, further comprising target value setting means for setting a target value for compensating the tilt instruction value indicating the tilt amount. 10. The recording medium drive according to claim 9, wherein the target value is a value arbitrarily set in advance. 11. The recording medium drive according to claim 9, wherein the target value is a value recorded in a control information recording area of the disk-shaped recording medium. 12. A data discriminating means for extracting the recording data from an RF signal based on the return light reflected and diffracted on the surface of the disc-shaped recording medium, and for discriminating a data detection capability for the recording data, and a tilt indication value. And a drive signal generating means for generating a drive signal for compensating tilt based on a tilt error signal represented by a difference value between the tilt instruction value and a target value for compensating for the tilt instruction value; The signal generating means changes the amount of tilt based on the drive signal and controls and drives the optical pickup means. The tilt detecting means obtains a tilt instruction value according to the change in tilt amount, and the target value The setting means includes a data indicating the tilt instruction value obtained by the tilt detecting means and a result of determining the data detecting ability by the data determining means. Based on the data discrimination signal, a recording medium driving apparatus according to claim 9, wherein the setting the target value. 13. A drive signal for compensating tilt based on a tilt error signal represented by a difference value between a tilt instruction value indicating the tilt amount and a target value for compensating the tilt instruction value. 5. The recording medium driving device according to claim 4, further comprising a drive signal generating means for generating a drive signal. 14. The optical pickup device according to claim 13, wherein the optical pickup device is controlled based on the drive signal generated by the drive signal generation device so that the tilt instruction value approaches the target value. Recording medium drive. 15. A waveform equalizer for performing a waveform equalization process on an RF signal based on return light reflected and diffracted on the surface of the disc-shaped recording medium, wherein the waveform equalizer includes the tilt detector 14. The recording medium driving device according to claim 13, wherein gain adjustment is performed based on the tilt error signal obtained by the following. 16. Signal information that can be distinguished from the recording data is recorded on one side wall of both sides of a recording area where recording data is recorded, and the signal information is recorded by modulating the width or position on both side walls. A guide groove having a structure in which modulation guide grooves serving as signal information recording side walls, which are the side walls, and non-modulation guide grooves that do not modulate both side walls are provided alternately, and one of both side walls of the recording area is provided. The modulation guide groove and the other is a non-modulation guide groove to the disk-shaped recording medium, while irradiating a laser beam, receiving the return light reflected and diffracted on the surface of the disk-shaped recording medium, Detecting the amplitude of the signal based on the return light from the signal information recording side wall; and detecting the signal information when the detected laser beam is located on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. The is a signal based on the return light from the side wall 1
And a second signal which is a signal based on the return light from the signal information recording side wall when the detected laser beam is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. A tilt amount is detected based on the amplitude of the tilt. 17. The same recording area is irradiated with the laser light, and the laser light is located on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. A case where the amplitude of the detected first signal and the amplitude of the detected second signal are alternately generated, and a case where the amplitude is detected on the outer peripheral side of the disc-shaped recording medium with respect to the recording side wall. 17. The tilt detecting method according to claim 16, wherein the tilt detection value is obtained as a tilt instruction value indicating the amount. 18. The tilt detecting method according to claim 16, wherein address information as the signal information is recorded on the signal information recording side wall of the disc-shaped recording medium. 19. A first recording area which is a recording area irradiated by the laser light when the laser light is located on the inner peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall; And a second recording area, which is a recording area irradiated by the laser light when the laser light is located on the outer peripheral side of the disc-shaped recording medium with respect to the signal information recording side wall. 17. The tilt detection method according to claim 16, wherein the determination is performed. 20. The method according to claim 1, wherein the laser beam is moved over the first recording area and the second recording area, and the amplitude of the first signal and the amplitude of the second signal are detected. 20. The tilt detecting method according to claim 19, wherein a difference value between the amplitude of the first signal detected in the previous period and the second amplitude is obtained during the period. 21. The tilt detecting method according to claim 16, wherein a target value for compensating the tilt instruction value indicating the tilt amount is set. 22. The tilt detecting method according to claim 21, wherein the target value is a value arbitrarily set in advance. 23. The tilt detecting method according to claim 21, wherein the target value is a value recorded in a control information recording area of the disc-shaped recording medium. 24. The recording data is extracted from an RF signal based on the return light reflected and diffracted on the surface of the disk-shaped recording medium, and the data detection capability for the recording data is determined. The optical pickup means for irradiating the laser light and receiving the return light reflected and diffracted on the surface of the disk-shaped recording medium is provided with a difference between the tilt instruction value and a target value for compensating the tilt instruction value. The tilt amount is changed based on the drive signal for compensating for the tilt generated based on the tilt error signal represented by the value, and the drive is performed with the tilt amount changed. 22. The target value is set based on a tilt instruction value and a data determination signal indicating a result of determining the data detection capability. Tilt detection method of. 25. A drive signal for compensating tilt based on a tilt error signal represented by a difference value between a tilt command value indicating the tilt amount and a target value for compensating the tilt command value. 17. The tilt detecting method according to claim 16, wherein 26. An optical pickup means for irradiating the disc-shaped recording medium with a laser beam and receiving return light reflected and diffracted on the surface of the disc-shaped recording medium, based on the drive signal, 3. The control device according to claim 2, wherein the instruction value is controlled so as to approach the target value.
6. The tilt detection method according to 5. 27. A gain adjustment in a waveform equalization process performed on an RF signal based on return light reflected and diffracted on the surface of the disk-shaped recording medium, based on the tilt error signal. Item 30. The tilt detection method according to Item 25.