JP2000348361A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical disk device capable of controlling the tilt in the tangential direction of a disk even for the PWM recording disk and also capable of controlling the tilt in the tangential direction even for the disk in the process of recording operation. SOLUTION: An orthogonal deviation signal is produced by comparing plural tap coefficients each other of an FIR equalizer circuit included in an adaptive equalizer 8, and an actuator of an optical pickup 2 is controlled so that this orthogonal deviation signal is minimized. At the time of recording operation, the orthogonal deviation signal preliminarily being learned by a recording track is stored in the amount of one track, and the actuator of the optical pickup 2 is controlled in accordance with this orthogonal deviation signal kept for storage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for recording or reproducing an optical disk, and more particularly, to an optical disk apparatus having an aberration correcting or tilt adjusting apparatus for maintaining an orthogonal relationship between an optical axis of an optical pickup and a recording surface of the optical disk. The present invention relates to an optical disk device.

[0002]

2. Description of the Related Art A disk-shaped recording medium is capable of high-speed random access and achieves a high recording density by narrowing a data track pitch and a pit pitch. In recent years, optical disks, such as DVDs, have been widely used as large-capacity recording media due to their high recording density, and further higher recording densities have been promoted in order to achieve even higher capacities. ing. However, an optical disk is generally made of a low-rigidity material such as polycarbonate, so that deformation due to warping or even bending due to its own weight cannot be ignored.

When digital data is recorded on a disk medium and original digital data is reproduced by an optical head, for example, the recording surface of the medium is not orthogonal to the optical axis of the objective lens of the optical head. If it has an inclination (hereinafter, referred to as “orthogonal deviation” or “tilt”), a beam spot irradiated on a pit on the information recording surface is distorted due to aberration, and a reproduced signal waveform output from the optical head is distorted. Also, due to the aberration distortion of the beam spot, reflected lights from adjacent pits interfere with each other to reduce the modulation degree of the reproduction signal, or a shift (peak shift) occurs in the peak time of the reproduction signal, thereby causing information reproduction. Problems such as incorrect identification of (RF) signals occur.

As a method of removing a distortion component included in a reproduced signal waveform, a FIR (Finite Impulse Response) has conventionally been used.
An adaptive equalizer using a filter is used. Particularly recently, the reproduced signal is quantized by an A / D converter,
Adaptive equalization is performed by digital processing. However, due to the rapid increase in recording density of recent optical disks, the reproduced signal is also sensitively affected by the tilt of the disk and the defocus of the reproducing system. Also, DV
In the case of an optical disk such as a D-RAM which performs recording / reproduction, the tilt and defocus of the disk have an adverse effect on both recording and reproduction, and furthermore, highly accurate aberration correction is required. Under such circumstances, tilt correction for adjusting the orthogonal relationship between the optical disk and the optical axis of the optical pickup is effective as a means for removing the aberration distortion component generated in the reproduction signal waveform.

[0005] As an example of the conventional tilt correction, for example, as described in Japanese Patent Application Laid-Open No. 61-51630, a tilt sensor for detecting a deviation of the orthogonal relationship between a disk surface and a light beam of an optical pickup is used. There is known a tilt control device that performs control so as to maintain an orthogonal relationship according to a detected orthogonal shift signal. However, in this method, it is necessary to dispose the photosensors on the left and right sides of the objective lens of the optical pickup, which complicates and enlarges the apparatus, and it is substantially difficult to control the tilt in the tangential direction of the disk. To solve this problem, see, for example, Japanese Patent Laid-Open No. 5-174.
No. 406 has proposed a tilt control method. This method uses a tangential direction (that is, a track direction) when reproducing information recorded by PPM (pulse phase modulation).
Is detected and corrected based on the deviation of the peak time of the reproduction signal.

[0006]

However, in recent optical disk devices, PWM is required to increase the recording density.
(Pulse width modulation) recording is the mainstream, and the above-mentioned conventional method has a problem that it cannot cope with data reproduction of PWM recording. Another problem is that tilt control in the tangential direction on the disk during the data recording operation cannot be performed.

SUMMARY OF THE INVENTION In view of the above problems, the present invention can perform tangential aberration correction and tilt control on a PWM-recorded disk, and can correct tangential aberration and tilt on a disk during a recording operation. It is an object of the present invention to provide an optical disk device capable of performing control.

[0008]

In order to solve the above-mentioned problems, a tilt control apparatus according to the present invention is applied to an optical disk apparatus having an FIR filter that generates a plurality of tap coefficients by performing adaptive equalization in a reproduction system. What is claimed is: 1. A tilt control device for controlling a deviation of an orthogonal relationship with an optical axis of a light beam emitted from an optical pickup onto an optical disc so as to minimize the deviation. An orthogonal shift detecting means for outputting an orthogonal shift detection signal according to the orthogonal shift, an inclination driving means for correcting the orthogonal shift by tilting the optical axis of the light beam, and Orthogonal shift control means for controlling the inclination driving means so as to minimize the orthogonal shift of the light beam.

The plurality of tap coefficients are an odd number in the order of delay input, and the orthogonal shift control means includes at least one of a set of remaining symmetric tap coefficients excluding the tap coefficient corresponding to the center position as a comparative symmetry axis. The comparison operation in the combination is controlled so that the tap coefficient values become substantially equal.

The optical disk apparatus of the present invention has an FIR filter for performing adaptive equalization in a reproducing system, and controls the optical disk so that the deviation of the orthogonal relationship between the optical disk and the optical axis of the light beam applied to the optical disk is minimized. An optical pickup that irradiates the light beam onto the optical disc to reproduce information recorded on the optical disc; and converts a reproduced analog signal of the optical pickup into a digital signal. A / D conversion means for performing conversion; and adaptive equalization means having the FIR filter and adaptively equalizing an output signal of the A / D conversion means. An orthogonal shift detection unit that outputs an orthogonal shift detection signal according to the orthogonal shift with the optical axis of the light beam using a plurality of tap coefficients,
Tilt driving means for correcting the orthogonal shift by tilting the optical axis of the light beam, and driving control of the tilt driving means in accordance with the orthogonal shift detection signal so that the orthogonal shift of the light beam is minimized. And orthogonal displacement control means for controlling

In the above optical disk apparatus, an optical disk apparatus for recording / reproducing information on / from a recordable / reproducible optical disk in a sector format having a pre-pit address, wherein information is recorded on or reproduced from the optical disk by using a pre-pit address. The recording / reproducing is performed by performing tilt control in accordance with the quadrature shift signal obtained from the tap coefficient of the FIR filter that has undergone the learning. Further, the orthogonal shift signal obtained from the tap coefficient of the FIR filter learned at the pre-pit address when information is recorded on the optical disk is based on a value learned and stored in advance.

Further, when recording information on or reproducing information from the optical disc, the F
The orthogonal shift signal obtained from the tap coefficient of the IR filter is stored, and the tilt control is performed in accordance with the stored orthogonal shift signal to perform recording / reproduction.

The orthogonal deviation control means stores an orthogonal deviation signal based on a learning result in an arbitrary track of a disk to be reproduced, and performs tilt control based on the stored value. I do.

Further, the light beam aberration control device of the present invention comprises:
A light beam aberration control device, which is applied to an optical disc device having an FIR filter that generates a plurality of tap coefficients by performing adaptive equalization in a reproduction system and controls aberration of a light beam emitted from an optical pickup to the optical disc, An aberration detection unit that outputs an aberration detection signal corresponding to the aberration of the light beam using a plurality of tap coefficients of the FIR filter; an aberration correction unit that corrects the aberration of the light beam; And aberration control means for controlling the driving of the correction means so as to minimize the aberration of the light beam.

The plurality of tap coefficients are an odd number in the order of the delay input, and the aberration control means includes at least one combination of the remaining symmetric tap coefficient sets excluding the tap coefficient corresponding to the center position as the axis of comparison symmetry. Is controlled so that the tap coefficient values become substantially equal in the comparison operation in.

The aberration correcting means comprises a liquid crystal tilt correcting element divided into a plurality of segments, and performs aberration correction of the light beam by changing the light refractive index of the liquid crystal element for each segment. .

Further, the optical disc apparatus of the present invention has an FIR filter for performing adaptive equalization in a reproducing system, and includes an optical disc and an aberration control apparatus for controlling an optical beam irradiated on the optical disc to minimize aberration. An optical pickup for irradiating the optical beam with the light beam to reproduce information recorded on the optical disk, and an A / D for converting a reproduced analog signal of the optical pickup into a digital signal A conversion means, and an adaptive equalization means having the FIR filter and adaptively equalizing an output signal of the A / D conversion means, wherein the aberration control device calculates a plurality of tap coefficients of the FIR filter. An aberration detecting means for outputting an aberration detection signal corresponding to the aberration of the light beam by using the light beam; an aberration correcting means for correcting the aberration of the light beam; Characterized in that and a aberration control means for controlling so aberration of the light beam by driving and controlling the aberration correcting means is minimized in response to the signal.

In the above optical disc apparatus, an optical disc apparatus for recording / reproducing information on / from a recordable / reproducible optical disc having a sector format having a pre-pit address, wherein information is recorded on or reproduced from the optical disc by a pre-pit address. Aberration control is performed in accordance with an aberration detection signal obtained from a tap coefficient of the FIR filter, which has been learned, and recording / reproduction is performed.

In the above arrangement, the aberration detection signal obtained from the tap coefficient of the FIR filter learned at the pre-pit address when recording information on the optical disk is based on a value learned and stored in advance. I do.

When recording information on or reproducing information from the optical disk, an aberration detection signal obtained from a tap coefficient of the FIR filter previously learned on a recording track is stored, and the stored aberration detection signal is stored. And performs recording / reproduction.

The aberration control means stores an aberration detection signal based on a learning result in an arbitrary track of a disk to be reproduced, and performs aberration control based on the stored value. .

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the attached drawings, similar components are denoted by the same reference numerals.

First, the schematic basic configuration of the recording / reproducing operation of the optical disk device according to the present invention will be described with reference to FIG. The optical disk device includes an optical disk, a disk spindle motor, an optical pickup, a laser drive circuit (LPC), a modulator / demodulator, an error detection / correction device, an I / F device,
It is composed of an amplifier, an adaptive equalizer / binarizer, a focus tracking controller, a control CPU, and the like. The disk motor rotates the optical disk, and the optical pickup
It is composed of an optical lens, an actuator, and a semiconductor laser, and reads and writes data on an optical disk. The laser drive circuit (LPC) drives the laser of the optical pickup. The modem digitally modulates data into a form suitable for recording at the time of recording and demodulates at the time of reproduction. The error detection and correction unit performs error detection and correction, and the I / F unit controls an interface with a host computer via an external input / output terminal. The amplifier / adaptive equalizer / binarizer amplifies the reproduced signal, performs adaptive equalization learning, and performs binarization processing. The focus tracking controller causes the optical pickup to follow the target track and causes the laser light to converge on the recording surface.

The control CPU is a control device for controlling the entire optical disk recording and reproducing apparatus.
It performs playback control, adaptive equalization control, tilt aberration control, command control such as command interpretation, and recording control. Control CPU
Is preferably configured by a microcomputer or the like, and each function can be configured by software.

The operation of recording data in the optical disk device configured as described above will be briefly described below. User data sent from an external terminal from a host computer or the like is sent to a modulator / demodulator via an I / F controller, an error detection / correction device, and the like, and is digitally modulated. On the other hand, the control CPU specifies a target track to the focus tracking controller. The focus tracking controller records the input data by moving the optical head to a target track. The digitally modulated data is sent to a laser driving circuit (LPC), and the intensity of the laser is changed according to the modulated data, so that the data is recorded in the data recording area of the target sector on the optical disk.

Next, when reproducing data, the control CP
U sends the target track for playback to the focus tracking controller. The focus tracking controller causes the light beam from the optical pickup to follow the target track.
As with the recording operation, the amplifier
A reproduced binary signal is generated by an adaptive equalizer / binarizer or the like, and a target sector is detected by a modem. The modulator / demodulator digitally demodulates the reproduced binary signal obtained from the data recording area of the target sector, and sends it as reproduced data to the host computer via the error detection / correction device and the I / F controller.

All the above operations are executed as a series of operations under the control of the control CPU. It should be noted that the timing control circuit and the PLL in FIG.
Such devices that can be used in common with devices used in conventional optical disk recording / reproducing devices, etc., are not described here.

(Embodiment 1) FIG. 1 shows a block configuration of an optical disk reproducing apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes an optical disk, 2 irradiates a laser beam to the optical disk 1, reads recording data according to the intensity of the reflected light, and outputs an electric signal. 3 amplifies the output signal of the optical pickup 2; A preamplifier 4 for outputting a reproduced RF signal receives an RF signal output from the preamplifier 3 as an input, and an auto gain control circuit (hereinafter, referred to as an AGC circuit) for controlling a gain so that an output signal amplitude of a subsequent equalizer 5 becomes constant. 5 and 5 are equalizers for improving the frequency characteristics of the output signal of the AGC circuit 4, and 6 is an equalizer 5
A / D converter for analog-to-digital conversion of the output signal of the A / D converter 7 is a PLL for performing a phase control with the output signal of the A / D converter 6 to generate a synchronous clock synchronized with the output signal of the A / D converter 6 Circuit.

Reference numeral 8 denotes an adaptive equalizer for adaptively equalizing the output signal of the A / D converter 6, and reference numeral 9 denotes an FIR equalizer (also referred to as "FIR filter unit") which is a component of the adaptive equalizer 8. The orthogonal displacement detector 10 detects the orthogonal displacement (tilt) between the optical disc 1 and the optical axis of the light beam emitted by the optical pickup 2 from the plurality of tap coefficients, and outputs a quadrature displacement signal according to the displacement amount. The tilt control unit 11 drives a tilt actuator of the optical pickup 2 described later according to the orthogonal shift signal output from the shift detection unit 9 so as to control the optical disc and the light beam optical axis to intersect vertically. A Viterbi decoder for Viterbi decoding the output signal of the equalizer 8,
A demodulator 12 demodulates the signal binarized by the Viterbi decoder 11 and outputs a signal before modulation.

The structure of the optical pickup 2 having the tilt actuator will be described with reference to FIG. 2a is an objective lens for condensing a light beam, 2b is an objective lens holding member for holding the objective lens 2a, 2c is a magnet A, 2 located at an end of the objective lens holding member 2b in the disk rotation direction.
d denotes magnets B and 2e located at ends of the objective lens holding member 2b in the direction opposite to the disk rotation direction, and fixing wires 2f and 2e for fixing the objective lens holding member 2b in a semi-fixed state.
g denotes coils A and B provided at positions facing the magnets A (2c) and B (2d), respectively, and provided at a fixed distance from each magnet. By controlling, the objective lens can be tilted in the track tangential direction.

Here, the tilt actuator is constituted by the magnets A and B (2c, 2d) and the coils A, B (2f, 2g), and functions as orthogonal displacement correction driving means. In the above configuration, the tilt actuator can tilt and drive the objective lens of the optical pickup or the entire optical pickup in the tangential direction of the optical disc.

FIG. 3 is a block diagram showing an example of the configuration of the adaptive equalizer 8. The FIR equalizer (FIR filter) 21, the equalization error evaluator 22, and the tap coefficient updater 23
And A sample value obtained by sampling the reproduced signal with the channel clock in the A / D converter 6 is input to the adaptive equalizer 8. The tap coefficient updating unit 23 calculates the F in accordance with a known LMS operation expression (Equation 1) described later so as to perform predetermined equalization according to a control signal from a control unit described later.
The tap coefficients of the IR equalizing circuit 21 are sequentially updated. The updated tap coefficient is fed back to the FIR equalization circuit 21 and sent to the quadrature deviation detecting unit 9.

FIG. 4 is a block diagram showing an example of the configuration of the FIR equalization circuit 21. The plurality of delay circuits 30 delay the signal at the sampling period obtained from the PLL circuit 7, and the input or output of each delay circuit 30. Signal and tap coefficient C1
A plurality of multipliers 31a to 31g (hereinafter, referred to as "31") for multiplying C7, an adder 32 for adding the multiplication result of each multiplier 31, and an output of a time division processing coefficient selection counter (not shown) And a signal selector 33 for selecting and outputting an input or output signal of each delay circuit 30. In the present embodiment, an example is described in which the input signal from the A / D (6) is 7 bits and seven multipliers 31 are arranged. In the above configuration, the addition result obtained by the adder 32 is input to the equalization error evaluator 22 and sent to the Viterbi decoder 11 at the subsequent stage. On the other hand, the output signal from the signal selector 33 in FIG. 4 is also input to the equalization error evaluator 22 for the determination of the equalization error.

FIG. 5 is a block diagram showing an example of the configuration of the equalization error evaluation section 22. The provisional determination section 41 receives the output signal of the adder 32 and determines its equalization target value TL. 4, a target value register 42 for outputting an equalized target value TL, a subtractor 43 for subtracting the output signal of the adder 32 from the equalized target value TL output from the target value register 42, and FIG. , A multiplier 44 for multiplying the output signal from the signal selector 33 and the output signal from the subtractor 43, and a multiplier 45 for multiplying the output signal of the multiplier 44 by a predetermined coefficient μ.

FIG. 6 is a block diagram showing a configuration example of the tap coefficient updating unit 23. The tap coefficient updating unit 23 holds the initial value Co or the updated tap coefficient Cm, and feeds back the tap coefficient to each multiplier 31 of the FIR equalization circuit 21. A coefficient register 51 for supplying a tap coefficient to the orthogonal displacement detection unit 9;
A coefficient selector 52 for selecting a coefficient register 51 and outputting a current tap coefficient based on an output of a coefficient selection counter (not shown), and a multiplier 4 of the equalization error evaluation unit 22 shown in FIG.
5 and the output signal of the coefficient selector 52, and outputs an updated tap coefficient.

Next, the operation of the adaptive equalizer 8 having the above configuration will be described. When starting up the disc,
The coefficient register 51 is loaded with the initial value Co. The tap coefficients C1 to C7 are input from the coefficient register 51 to each multiplier 31 shown in FIG. Reproduction signal S at a certain time n
When n is sequentially input from the A / D (6) to each delay circuit 30 of the FIR equalizer 21 shown in FIG.
1 calculates ΣmSm, n · Cm, n and outputs the result from the adder 32. Then, the m-th tap coefficient Cm is obtained by (Equation 1) by the least mean square (LMS) algorithm, and is updated as follows.

[0037]

## EQU1 ## Cm, n + 1 = Cm, n + μ · Sm, n (TLn
−ΣmSm, n · Cm, n) Here, the coefficient μ is a step size parameter, and m is an integer of 1 to 7. Also, on the right side of the equation (Equation 1), ΣmSm, n · Cm, n is the output of the adder 32, (T
Ln−ΣmSm, n · Cm, n) indicates the output of the subtractor 43, that is, the equalization error, and μ · Sm, n (TLn−ΣmSm, n)
(Cm, n) represents the output of the multiplier 45, and the updated tap coefficient Cm, n + 1 is output from the multiplier 53 and fed back to the coefficient register 51.

The tentative determination section 41 of the equalization error evaluation section 22 shown in FIG. 5 determines which target value the signal input from the adder 32 of the FIR equalization circuit 21 should be equalized, and makes a determination. The result is output to the target value register 42.
The target value register 42 outputs the determined equalization target value TL. The subtracter 43 subtracts the signal ΣmSm, n · Cm, n input from the adder 32 of the FIR equalization circuit 21 from the equalization target value TL, and outputs an equalization error.

The signal selector 33 shown in FIG. 4 is controlled by the output of a coefficient selection counter (not shown), and outputs an m-th tap coefficient C
m or the input or output signal Sm of the delay circuit 30 multiplied by m
(Ie, S1 to S7) are selected and output to the multiplier 44 shown in FIG. The multiplier 44 multiplies the output signal Sm, n of the signal selector 33 at the current time n by the equalization error obtained by the subtractor 43 and outputs the result to the multiplier 45. The multiplier 45 multiplies the output signal of the multiplier 44 by the step size parameter u and outputs the result to the adder 53 of FIG.

The coefficient selector 52 is controlled by the coefficient selection counter output in the same manner as described above, and the m-th tap coefficient Cm is selected and output to the adder 53. The adder 53 is a multiplier 4
5 is added to the current m-th tap coefficient Cm, n which is the output signal of the coefficient selector 52, and the updated m
The coefficient Cm, n + 1 is output. The coefficient register 51
The updated tap coefficient is newly held. When this step is repeated based on a coefficient counter (not shown), the tap coefficients C1 to C7 for removing the intersymbol interference of the disk reproduction signal and forming the most preferable reproduction signal.
Is obtained.

FIG. 7 is a graph showing a learning result of tap coefficients of the FIR equalization circuit 21 when a signal obtained by actually adding a tangential tilt (hereinafter referred to as T tilt) of the disk to the adaptive equalizer 8 is input. It is. In the figure, tap coefficient C input to multiplier 31d at the center position (see FIG. 4)
Tap coefficients other than 4 are C1 and C7, C2 and C6, C3
And C5 are related to each other. FIG.
7 is a partially enlarged view of the tap coefficient excluding the center position tap coefficient C4 in FIG. 7, in which the horizontal axis represents T tilt and the vertical axis represents the value of the tap coefficient.

FIGS. 9 (a), 9 (b) and 9 (c) are diagrams showing tilt directions (normal, positive and negative directions). As can be seen from the relationship with the graph of FIG. And C7, when T tilt is in the minus direction, C1 <
C7, C1> C7 in the plus direction, and C1
Focusing on 3 and C5, C3 <C5 when the T tilt is in the minus direction, C3> C5 when the T tilt is in the plus direction, and C2> C6 when the T tilt is in the minus direction, and focusing on C2 and C6. In the case of the direction, C2 <C6. When T tilt is 0, C1 = C7, C
3 ≒ C5 and C2 ≒ C6. Therefore, the orthogonal shift detector 9 can obtain an orthogonal shift signal by calculating the combination of these tap coefficients. For example, (C
If 7-C1) is positive, the T tilt is determined to be negative, and the optical pickup 2 is corrected in the positive direction.
If (C7-C1) is minus, the T tilt is determined to be plus, and the T tilt can be corrected by correcting the optical pickup 2 in the minus direction.

For example, if the spot shape of the light beam applied to the optical disk is ideally circular and the T tilt occurs, the light beam applied to the optical disk from the optical pickup is obliquely incident. Becomes elliptical, and the intensity distribution of the light beam is biased due to the influence of aberration. This bias greatly affects the direction in which the optical pickup is tilted. Since the adaptive equalizer operates in a direction to remove the influence of the aberration, the balance of the left and right tap coefficients around the center tap (C4) is lost. That is, where the tap coefficients are symmetrical (coincident), the influence of the aberration due to the tilt is minimized.
At this time, the relationship between the unbalance of the tap coefficient and the tilt direction changes depending on the light beam spot and the tap interval.

Next, the tilt control operation in the reproduction operation of the entire optical disk device shown in FIG. 1 will be described. A read signal of the optical disk 1 read by the optical pickup 2 is input to the preamplifier 3, and an RF signal is output.
Thereafter, the frequency characteristics are improved and the amplitude is adjusted by the AGC circuit 4 and the equalizer 5, and the gain is controlled so that the output amplitude of the equalizer 5 becomes a constant amplitude.
It is input to the D converter 6. Analog / A / D converter 6
The digitally converted signal is input to the PLL circuit 7,
The LL circuit 7 compares the phase of the digital signal from the A / D converter 6 with the reproduction reference clock,
By performing phase lock control, a clock synchronized with the disk reproduction signal is generated and supplied as a sampling clock of the A / D converter 6 and a system clock of each component block unit.

The disk reproduction signal synchronously sampled by the A / D converter 6 is input to the adaptive equalizer 8. The adaptive equalizer 8 performs the equalization learning of the disk reproduction signal as described above, and outputs tap coefficients C1 to C7 for forming the reproduction signal with the most preferable disk reproduction signal at each position in the disk circumferential direction. . When the obtained tap coefficients are input to the orthogonal shift detector 9, the orthogonal shift detector 9 calculates, for example, (C7-C1) and outputs an orthogonal shift signal, as described above.

If the orthogonal shift signal is positive, the tilt controller 10 sets the magnet A (2c) of the optical pickup 2 to the magnet B
(2d) The current flowing through the coil A (2f) and the coil B (2g) is controlled so as to approach the disk relatively, and if the orthogonal displacement signal is negative, the magnet A (2c) of the optical pickup 2 is magnetized. The current flowing through the coil A (2f) and the coil B (2g) is controlled so as to be farther from the disk than the disk B (2d). Control is performed so as to be minimum (zero) as shown in FIG. As a result, the disc T-tilt correction is performed, a disc reproduction signal with little intersymbol interference is obtained, and the intersymbol interference that cannot be removed by the tilt control is signal-processed by the adaptive equalizer 8 so that the optimal signal is Viterbi-corrected. It is input to the decoder 11. The Viterbi decoder 11 binarizes the input signal and outputs a binarized signal to the demodulator 12. The demodulator 12 demodulates the NRZI data, converts the demodulated NRZI data into a format of user data before modulation, and outputs the data to a subsequent processing circuit.

As described above, according to the first embodiment,
For a disk having a T tilt or a drive system including an optical pickup, tilt control adapted at each position in the circumferential direction of the disk can be performed with high accuracy with a simple configuration, and a disk reproduction signal is the most preferable reproduction signal. Can be formed, so that a reproduction margin can be ensured even when the density of the disk increases.

(Embodiment 2) FIG. 10 shows a block configuration of an optical disk reproducing apparatus according to Embodiment 2 of the present invention. The difference from the first embodiment is that aberration correction is performed instead of performing tilt control in the circumferential direction of the disk, and a liquid crystal aberration correction element is used by changing the configuration of an optical pickup 2 described below to a tilt actuator.
The orthogonal displacement detector 9 is provided to the aberration detector 13 and the tilt controller 1
By replacing 0 with the aberration control unit 14, the configuration is applied to an aberration correction unit for aberration distortion caused by orthogonal displacement of a beam spot irradiated on the information recording surface, and a good reproduction signal waveform is obtained.

FIG. 11 shows the structure of an optical pickup 2 'according to the second embodiment. Reference numeral 2a denotes an objective lens, and 2h denotes a liquid crystal aberration correcting element used for aberration correcting means. FIG. 12 is a detailed configuration diagram illustrating an example of the liquid crystal aberration correction element 2h. The liquid crystal aberration correcting element 2h is divided into, for example, four segments in the tangential direction of the disk, and the first tilt correcting element 2i, the second tilt correcting element 2j, the third tilt correcting element 2k, Four tilt correction elements 2m are arranged in this order. These tilt correction elements have a variable refractive index liquid crystal element that can independently change the refractive index of light for each segment.

Next, with respect to the operation in the second embodiment using the above configuration, only the portions different from the first embodiment will be described. The tangential aberration of the disk is considered to be caused mainly by T tilt. Therefore, the method of detecting the orthogonal shift using the combination comparison of the tap coefficients of the adaptive equalizer 8 described in the first embodiment with reference to the graph of FIG. 8 and FIG. Can also be applied,
As in the case of detecting the orthogonal shift signal, the aberration detection unit 13 obtains an aberration detection signal by performing a calculation by comparing and combining the tap coefficients obtained by the FIR equalization circuit 21. For example, the refractive indices of light controlled by the first tilt correction element 2i, the second tilt correction element 2j, the third tilt correction element 2k, and the fourth tilt correction element 2m are set to n1, n2,
Assuming n3 and n4, if (C7-C1) is positive, the aberration control unit 14 adjusts each refractive index so that n1 <n2 <n3 <n4, and if (C7-C1) is negative, n1 If the aberration control unit 14 controls each refractive index such that>n2>n3> n4, aberration can be corrected.

As described above, according to the second embodiment,
For a disk or drive system having tangential aberration, it is possible to perform adaptive aberration control at each position in the disk circumferential direction, and a disk reproduction signal can form a most preferable reproduction signal.
Even if the density of the disk increases, a reproduction margin can be secured. Although the divided shape of the liquid crystal aberration correcting element 2h, which is the aberration correcting means, is divided into four in the tangential direction of the disk, the shape is not limited to this, and may be appropriately changed depending on the type of aberration to be corrected. For example, the liquid crystal aberration correcting element 2h 'shown in FIG. 13 may be divided into three parts so that the center and the vicinity of the outer peripheral end have the same refractive index. Further, the optical pickup 2 ′ having these liquid crystal aberration correction elements can be used in combination with the tilt control method (9, 10) shown in FIG.

(Embodiment 3) FIG. 14 shows a block configuration of an optical disk apparatus according to Embodiment 3 of the present invention. In the present embodiment, the tilt control method shown in FIG. 1 described in the first embodiment is employed, and a different point is that a controller 15 is newly added, and the adaptive equalizer 8, the orthogonal shift detector 9, and the tilt This is a recording / reproducing apparatus in which the control unit 10 and the optical pickup 2 are controlled by the controller 15. In FIG. 14, only the configuration of the disk reproducing system is shown in detail, but the configuration of the disk recording system has already been described with reference to FIG.

FIGS. 15 (a), (b), (c), (d),
(E), (f), and (g) correspond to the third, fourth, fifth, and sixth embodiments.
FIG. 3 is a timing chart for explaining the operation of FIG. FIG. 15 shows the relationship between the RF signal output from the preamplifier 3 and the disk format when reading a DVD-RAM disk having a prepit address, and the respective gate signals as control signals output from the controller 15. It is shown.
One sector is composed of a pre-pit address section 61 recorded at a position shifted by a half track from the recording guide groove, and an information (user data) recording section 62 in which the recording guide groove is meandering periodically. ing.

Next, the operation of the optical disk device according to the third embodiment will be described with reference to FIGS. Here, only portions different from the first embodiment will be described. When data is recorded on an optical disk, when the optical pickup reaches a sector to be recorded, the controller 15 outputs a pre-pit address gate signal PAG to the adaptive equalizer 8, the orthogonal shift detector 9, and the tilt controller 10. I do. Therefore, while the pre-pit address gate signal is “1” (High), the adaptive equalizer 8 adaptively equalizes the reproduced signal of the pre-pit address section 61 so as to be optimal, and the orthogonal shift detecting section 9
Is calculated from the tap coefficient of the FIR equalizer 21 by, for example, (C
7-C1) is calculated and an orthogonal shift signal is output. The tilt control unit 10 controls the tilt actuator of the optical pickup 2 based on the tilt control operation of the first embodiment so that the orthogonal displacement between the optical disk 1 and the optical axis of the beam emitted from the optical pickup 2 is minimized (substantially zero). Control.

The beam of the optical pickup 2 is applied to the information recording section 6.
When the pre-pit address gate signal PAG becomes "0" (Low), the adaptive equalizer 8, the orthogonal shift detector 9, and the tilt controller 10 maintain the above-mentioned control performed in the pre-pit address, and The controller 15 outputs a recording gate signal RG to the optical pickup 2, and the optical pickup 2 is controlled by the laser driving circuit LPC shown in FIG.
During the period of i), a desired user data signal is recorded.

Next, when data is reproduced from the disk, the pre-pit address gate signal PA
While G is "1", the adaptive equalizer 8 adaptively equalizes the reproduced signal of the pre-pit address section 61 so that the reproduced signal is optimal, and the orthogonal shift detecting section 9 obtains, for example, (( C7-C1) is calculated and an orthogonal shift signal is output. The tilt control unit 10 controls the tilt actuator of the optical pickup 2 based on the operation of the first embodiment so that the orthogonal displacement between the optical disc 1 and the optical axis of the beam emitted from the optical pickup 2 is minimized.

The beam of the optical pickup 2 is applied to the information recording section 6.
When the pre-pit address gate signal becomes "0", the quadrature deviation detecting unit 9 and the tilt control unit 10 maintain the control immediately before the pre-pit address unit 61, and at the same time, the controller 15 adapts. The reproduction gate signal RPG is output to the equalizer 8. Subsequently, the reproduction signal of the information recorded in the information recording unit 62 is
The signal is input to an adaptive equalizer 8 via a GC circuit 4, an equalizer 5, and an A / D converter 6. Since the reproduction signal quality differs between the pre-pit address section 61 and the information recording section 62, the adaptive equalizer 8 performs adaptive equalization learning for forming a reproduction signal having the most preferable disc reproduction signal, and performs the tilt control. Signal processing of errors due to intersymbol interference
The optimal signal is input to the Viterbi decoder 11. The Viterbi decoder 11 binarizes the input signal and converts the binarized signal to the demodulator 1
Output to 2. The demodulator 12 demodulates the NRZI data, converts the NRZI data into user data before modulation, and outputs the user data to a subsequent processing circuit.

As described above, according to the third embodiment,
Even when data is recorded on the optical disc 1, tilt control suitable for each position in the disc circumferential direction can be performed on a disc or a drive system having a T tilt. Therefore, when recording on a disc, recording can be performed in the most preferable tilt-controlled state, and during reproduction, a reproduction signal can be formed in the most preferable tilt-controlled state. Even after that, a recording / reproducing margin can be secured.

In the third embodiment, the adaptive control and the tilt control are performed for the entire pre-pit address, but it is needless to say that the control may be performed for a part of the pre-pit address. Although the recording is performed simultaneously with the learning in the pre-pit address reproduction, the learned orthogonal shift signal may be stored in advance and read out at the time of recording to perform tilt control. Also, the track to be learned in advance need not be the same as the target track to be recorded. Further, in the third embodiment, the tilt control at the time of reproduction is operated only in the pre-pit address section 61, and the tilt control is maintained at the time of reproducing the information recorded in the information recording section 62. Needless to say, the operation may be always performed when the information recorded in the information recording unit 62 is reproduced.

(Embodiment 4) FIG. 16 shows a block configuration of an optical disk apparatus according to Embodiment 4 of the present invention. In the present embodiment, the aberration control method shown in FIG. 10 described in the second embodiment is employed, and a different point is that a controller 15 is newly added, and the adaptive equalizer 8, the aberration detection unit 13, and the aberration control That is, a recording / reproducing apparatus in which the unit 14 and the optical pickup 2 are controlled by the controller 15. However, FIG. 16 shows only the configuration of the disk reproducing system in detail, but the configuration of the disk recording system is
Since it has already been described with reference to FIG. 19, it is omitted here. Therefore, the difference from the third embodiment is that the optical pickup 2 ′ is used, the orthogonal displacement detection unit 9 is provided for the aberration detection unit 13, and the tilt control unit 10 is provided for the aberration control unit 14.
It has been replaced by

Next, the operation of the fourth embodiment will be described with reference to FIGS.
6 will be described. Here, only portions different from the second embodiment will be described. When recording data on an optical disc,
When the optical pickup reaches the sector to be recorded, the controller 15 sends the pre-pit address gate signal PA to the adaptive equalizer 8, the aberration detector 13, and the aberration controller 14.
G is output. Therefore, while the pre-pit address gate signal is "1", the adaptive equalizer 8 adaptively equalizes the reproduced signal of the pre-pit address section 61 so as to be optimal, and the aberration detection section 13 taps the FIR equalization circuit 21. For example, (C7-C1) is calculated from the coefficient, and an aberration detection signal is output. Based on the aberration control operation of the second embodiment, the aberration control unit 14 controls the first liquid crystal tilt correction element 2i and the second liquid crystal tilt correction element 2j of the optical pickup 2 ′ so that the aberration is minimized (substantially zero). The third liquid crystal tilt correction element 2
k, and controls the refractive index of light of the fourth liquid crystal tilt correction element 2m.

When the beam of the optical pickup 2 ′ advances to the information recording section 62 and the prepit address gate signal becomes “0”, the adaptive equalizer 8, the aberration detection section 13, and the aberration control section 1
4 maintains the control performed in the pre-pit address section, and at the same time, the controller 15 controls the optical pickup 2 ′.
The optical pickup 2 'is controlled by the laser drive circuit LPC shown in FIG. 19, and records a desired signal while the recording gate signal is "1".

Next, when data is reproduced from the disk, the pre-pit address gate signal PA
While G is “1”, the adaptive equalizer 8 adaptively equalizes the reproduced signal of the pre-pit address section 61 so that the reproduced signal is optimized, and the aberration detecting section 13 calculates the tap coefficient of the FIR equalizing circuit 21 from, for example, ( C7-C1) is calculated and an aberration detection signal is output. The aberration control unit 14 is based on the operation of the second embodiment,
Each of the first tilt correction element 2i, the second tilt correction element 2j, the third tilt correction element 2k, and the fourth tilt correction element 2m of the liquid crystal aberration correction element of the optical pickup 2 'is configured to minimize the aberration. Controls the refractive index of light.

When the beam of the optical pickup 2 ′ advances to the information recording section 62 and the pre-pit address gate signal becomes “0”, the aberration detection section 13 and the aberration control section 14 are made to the pre-pit address section 61. At the same time as maintaining the previous control, the controller 15 outputs the reproduction gate signal RPG to the adaptive equalizer 8. Subsequently, the reproduction signal of the information recorded in the information recording unit 62 is
The signal is input to an adaptive equalizer 8 via a C circuit 4, an equalizer 5, and an A / D converter 6. Since the reproduction signal quality is different between the pre-pit address section 61 and the information recording section 62, the adaptive equalizer 8 performs equalization learning for forming a reproduction signal with the most preferable disc reproduction signal, and is removed by aberration control. An error due to no intersymbol interference is signal-processed, and an optimum reproduced signal is input to the Viterbi decoder 11. The Viterbi decoder 11 binarizes the input signal and outputs a binarized signal to the demodulator 12. The demodulator 12 demodulates the NRZI data, converts the NRZI data into user data before modulation, and sends the user data to a subsequent processing circuit.

As described above, according to the fourth embodiment,
Also in the case of recording on the optical disc 1, it is possible to perform adaptive aberration control at each position in the disc circumferential direction on a disc or a drive system having a tangential aberration. Therefore, when recording on a disc, recording can be performed with the most preferable aberration-controlled state, and also during reproduction, a reproduction signal can be formed with the most preferable aberration-controlled state. Even when the density is increased, a recording / reproducing margin can be secured.

In the fourth embodiment, adaptive control and aberration control are performed for the entire pre-pit address. However, it goes without saying that control may be performed for a part of the pre-pit address. Although the recording is performed at the same time as the learning in the pre-pit address reproduction, the aberration detection signal learned in advance may be stored and read out at the time of recording to control the aberration. The track to be learned in advance may not be the same as the target track to be recorded. Further, in the fourth embodiment, the aberration control at the time of reproduction is operated only in the pre-pit address section 61, and the aberration control is maintained at the time of reproducing the information recorded in the information recording section 62. Needless to say, the operation may be always performed when the information recorded in the information recording unit 62 is reproduced.

(Fifth Embodiment) FIG. 17 shows a block configuration of a fifth embodiment of the present invention. The components are the same as those of the third embodiment, except that the type of the output gate signal of the controller 15 and the connection destination are changed.

Next, the operation in the fifth embodiment will be described with reference to FIG.
5 and FIG. At the time of starting the disc or immediately before recording, a seek to the learning track provided on the optical disc 1 is performed. Then, the tilt control is fixed to the neutral position, and the information is recorded in the information recording unit 62 while the recording gate signal RG output from the controller 15 is “1”. Next, this recording track is reproduced while the tilt control is fixed at the neutral position, and the controller 15
The learning reproduction gate signal LRPG output by
(See (g)) is "1", the information is reproduced, and the adaptive equalizer 8
Is adaptively equalized so that the reproduced signal of the information recording unit 62 is optimal, and the orthogonal shift detection unit 9 calculates, for example, (C7-C1) from the tap coefficients of the FIR equalization circuit 21 to convert the orthogonal shift signal to Output. The tilt control unit 10 stores the orthogonal shift signal for one track in the temporary storage unit (10a) in association with the circumferential position of the disk.

When reaching the sector to be recorded,
The controller 15 outputs a recording gate signal RG. While the recording gate signal is "1", the tilt control unit 10 controls the optical pickup 2 so that the orthogonal shift is minimized in accordance with the orthogonal shift signal previously stored for one track in association with the circumferential position of the disk. Of the tilt actuator is controlled. The optical pickup 2 is controlled by the laser driving circuit LPC shown in FIG. 19, and records a desired signal while the recording gate signal is "1".

When a sector to be reproduced is reached,
The controller 15 outputs a reproduction gate signal RPG.
While the reproduction gate signal is "1", the tilt control unit 10 controls the optical pickup 2 so that the orthogonal shift is minimized in accordance with the orthogonal shift signal previously stored for one track in association with the circumferential position of the disk. Of the tilt actuator is controlled. Next, the reproduction signal of the information recorded in the information recording unit 62 is supplied to the preamplifier 3, the AGC circuit 4, the equalizer 5, the A / D
The signal is input to the adaptive equalizer 8 via the converter 6. The adaptive equalizer 8 updates the tap coefficients by performing equalization learning for forming the most preferable reproduction signal from the information recording unit 62 of the disc, and removes errors due to intersymbol interference that cannot be removed by tilt control. The signal is processed, and an optimal signal is input to the Viterbi decoder 11. The Viterbi decoder 11 binarizes the input signal and outputs a binarized signal to the demodulator 12. The demodulator 12 demodulates the NRZI data, converts the NRZI data into user data before modulation, and outputs the user data to a subsequent processing circuit.

As described above, according to the fifth embodiment,
Even in the case of recording on the optical disc 1, it is possible to perform a tilt control suitable for a disc or a drive system having a T tilt at each position in the disc circumferential direction. Therefore, when recording on a disk, it is possible to perform recording in the most preferable state and at the time of reproduction, it is possible to form a most preferable reproduction signal. it can.

The recording track to be learned in advance may be a track near the track to be recorded. Also,
The recording track to be learned in advance may be the own track before overwriting. Further, the recording track to be learned in advance may be a track previously recorded on the learning track. The track to be learned in advance may be a track recorded immediately before recording on a track near the track to be recorded.

In the fifth embodiment, the learning is performed only while the learning reproduction gate signal LRPG is "1", and the tilt control during recording or reproduction is performed while the recording gate signal or the reproduction gate signal is "1". However, the tilt control at the time of recording or reproduction may be continuously performed with the pre-pit address portion 61 by learning together with the pre-pit address portion 61.

In the fifth embodiment, the description has been given of the operation on the optical disc capable of recording and reproduction. However, when the reproduction-only disc is reproduced, a learning track, a reproduction target track, or an arbitrary track is used for learning. The target track may be stored, and the target track may be reproduced by performing tilt control using the stored value. Further, the stored learning result may be a control signal of an actuator that has been tilt-controlled in accordance with the orthogonal shift signal.

(Sixth Embodiment) FIG. 18 is a block diagram showing a sixth embodiment of the present invention. The difference from the fourth embodiment is that the type of the output gate signal of the controller 15 and the connection destination are changed.

Next, the operation of the sixth embodiment will be described with reference to FIGS.
8 will be described. At the time of starting the disc or immediately before recording, the learning track provided on the optical disc 1 is sought. Then, the aberration control is fixed to the neutral control value, and the information is recorded in the information recording unit 62 while the recording gate signal output from the controller 15 is “1”. Next, the recording track is reproduced while the aberration control is fixed at the neutral control value, and the information is reproduced while the learning reproduction gate signal LRPG output from the controller 15 is “1”. The adaptive equalization is performed so that the reproduction signal of the information recording unit 62 is optimized.
For example, (C7-C1) is calculated from the coefficient of 1 to output an aberration detection signal. The aberration control unit 14 stores this aberration detection signal for one track in the temporary storage unit (14a) in association with the circumferential position of the disk.

Then, when reaching the sector to be recorded, the controller 15 outputs a recording gate signal RG. While the recording gate signal is "1", the aberration control unit 14 controls the optical pickup 2 'so that the aberration is minimized in accordance with the aberration detection signal previously stored for one track in association with the circumferential position of the disk. Of the first tilt correction element 2i, the second tilt correction element 2j, the third tilt correction element 2k,
Of the light of the tilt correction element 2m is controlled. The optical pickup 2 is controlled by the laser driving circuit LPC shown in FIG. 19, and records a desired signal while the recording gate signal RG is "1".

When a sector to be reproduced is reached,
The controller 15 outputs a reproduction gate signal RPG.
While the reproduction gate signal is “1”, the aberration control unit 14 controls the optical pickup 2 ′ so that the aberration is minimized in accordance with the aberration detection signal stored in advance for one track in association with the circumferential position of the disk. Of the first tilt correction element 2i, the second
Of the third tilt correcting element 2j, the third tilt correcting element 2k, and the fourth tilt correcting element 2m.

Next, the reproduced signal of the information recorded in the information recording section 62 is input to the adaptive equalizer 8 via the preamplifier 3, the AGC circuit 4, the equalizer 5, and the A / D converter 6.
The adaptive equalizer 8 performs learning for forming a reproduction signal most preferably a disk reproduction signal, performs signal processing on intersymbol interference that cannot be removed by aberration control, and an optimum signal is input to the Viterbi decoder 11. The Viterbi decoder 11 binarizes the input signal and outputs a binarized signal to the demodulator 12. The demodulator 12 demodulates the NRZI data, converts the NRZI data into user data before modulation, and outputs the user data to a subsequent processing circuit.

As described above, according to the sixth embodiment,
Even in the case of recording on the optical disc 1, it is possible to perform adaptive aberration control on a disc or a drive system having a tangential aberration at each position in the disc circumferential direction. Therefore, it is possible to record in the most preferable state when recording on the disk, and to form the most preferable reproduction signal during reproduction. Can be.

The recording track to be learned in advance may be a track near the track to be recorded. Also,
The recording track to be learned in advance may be the own track before overwriting. Further, the recording track to be learned in advance may be a track previously recorded on the learning track. The track to be learned in advance may be a track recorded immediately before recording on a track near the track to be recorded.

In the sixth embodiment, the learning is performed only while the learning reproduction gate signal is "1", and the aberration control during recording or reproduction is performed only when the recording gate signal or the reproduction gate signal is "1". However, the aberration control during recording or reproduction may be continuously performed together with the pre-pit address section 61 by learning together with the pre-pit address section 61. Further, in the sixth embodiment, the operation on the optical disc capable of recording and reproduction has been described, but the learning track or the track to be reproduced when reproducing the reproduction-only disc,
Alternatively, the data may be learned and stored in an arbitrary track, and the target track may be reproduced by controlling the aberration with the stored value when reproducing the target track.

[0083]

As described above, according to the present invention,
For a disk or a drive having a T tilt, it is possible to perform an appropriate tilt control at each position in the disk circumferential direction, and it is possible to form the most preferable disk reproduction signal in the disk reproduction. Also, a reproduction margin can be secured.

Further, according to the present invention, it is possible to perform an aberration control adaptively at each position in the disk circumferential direction on a disk or a drive having a tangential aberration, and the most preferable reproduction signal in the disk reproduction. Can be formed, so that a reproduction margin can be ensured even when the density of the disk increases.

Further, according to the present invention, even in the case of recording on an optical disk, a tilt control suitable for each position in the disk circumferential direction can be performed on a disk or a drive having a T tilt. Therefore, recording can be performed in the most preferable state when recording on the disk, and the most preferable reproduction signal can be formed also during reproduction, so that a recording / reproducing margin can be secured even when the density of the disk increases. it can. Further, by learning on a recording track, the accuracy of tilt control can be improved.

Further, according to the present invention, even in the case of recording on an optical disk, it is possible to perform adaptive aberration control on a disk or a drive having tangential aberration at each position in the disk circumferential direction. Therefore, recording can be performed in the most preferable state when recording on the disk, and the most preferable reproduction signal can be formed also during reproduction, so that a recording / reproducing margin can be secured even when the density of the disk increases. it can. Further, by learning on the recording track, the accuracy of aberration control can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disc reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a front view showing a configuration of the optical pickup according to the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of an example of an adaptive equalizer;

FIG. 4 is a block diagram showing a detailed configuration of an FIR equalization circuit;

FIG. 5 is a block diagram showing a detailed configuration of an equalization error evaluation unit.

FIG. 6 is a block diagram illustrating a detailed configuration of a tap coefficient updating unit.

FIG. 7 is a diagram showing learning results of tap coefficients of an FIR equalization circuit;

FIG. 8 is a partially enlarged view of FIG. 7;

FIG. 9 is a diagram showing a tilt direction;

FIG. 10 is a block diagram of an optical disc reproducing apparatus according to Embodiment 2 of the present invention.

FIG. 11 is a front view showing an optical pickup according to a second embodiment of the present invention.

12 is a detailed configuration diagram showing an example of a liquid crystal tilt correction element of the optical pickup in FIG.

FIG. 13 is another detailed configuration diagram of the liquid crystal tilt correction element.

FIG. 14 is a block diagram of an optical disc reproducing apparatus according to Embodiment 3 of the present invention.

FIG. 15 is an operation explanatory view of Embodiments 3, 4, 5, and 6 of the present invention.

FIG. 16 is a block diagram of an optical disc reproducing apparatus according to Embodiment 4 of the present invention.

FIG. 17 is a block diagram of an optical disc reproducing device according to a fifth embodiment of the present invention.

FIG. 18 is a block diagram of an optical disc reproducing apparatus according to Embodiment 6 of the present invention.

FIG. 19 is a block diagram illustrating a recording / reproducing operation of the optical disc device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical pickup 3 Preamplifier 4 AGC circuit 5 Equalizer 6 A / D converter 7 PLL circuit 8 Adaptive equalizer 9 Orthogonal shift detection part 10 Tilt control part 11 Viterbi decoder 12 Demodulator 13 Aberration detection part 14 Aberration control part 15 Controller 21 FIR equalization circuit 22 Equalization error evaluation unit 23 Tap coefficient update unit

Claims (17)

[Claims] The present invention is applied to an optical disc apparatus having an FIR filter that generates a plurality of tap coefficients by performing adaptive equalization in a reproduction system, and a deviation of an orthogonal relationship between an optical axis of a light beam applied from an optical pickup to the optical disc and an optical disc. A tilt control device for controlling the optical beam to be minimized, comprising: a quadrature deviation detecting means for outputting a quadrature deviation signal according to a quadrature deviation from an optical axis of a light beam using a tap coefficient of the FIR filter; Tilt driving means for correcting the orthogonal shift by tilt-driving the optical axis of, and driving control of the tilt driving means in accordance with the orthogonal shift detection signal, so as to minimize the orthogonal shift of the light beam. A tilt control device, comprising: orthogonal displacement control means. 2. The orthogonal deviation control means controls the tap coefficients so that the tap coefficient values become substantially equal in at least one combination of tap coefficient sets symmetrical with respect to a center position of the plurality of tap coefficients. The tilt control device according to claim 1, wherein the tilt control is performed. 3. A tilt control device which has an FIR filter for performing adaptive equalization in a reproducing system and controls an optical disc and a deviation of an orthogonal relation between an optical axis of a light beam applied to the optical disc and the optical axis to be minimized. An optical pickup for irradiating the optical beam onto the optical disk to reproduce information recorded on the optical disk; and an A / D for converting a reproduced analog signal of the optical pickup into a digital signal. Conversion means; and an adaptive equalization means having the FIR filter and adaptively equalizing the output signal of the A / D conversion means, wherein the tilt control device calculates a plurality of tap coefficients of the FIR filter. Orthogonal displacement detection means for outputting an orthogonal displacement detection signal corresponding to the orthogonal displacement of the light beam with the optical axis, and tilt driving of the optical axis of the light beam. Tilt driving means for correcting the orthogonal shift, and orthogonal shift control means for controlling the drive of the tilt in accordance with the orthogonal shift detection signal and controlling the orthogonal shift of the light beam to be minimized. An optical disk device characterized by the above-mentioned. 4. The orthogonal deviation control means controls the tap coefficients to be substantially equal in at least one combination of a set of tap coefficients symmetrical with respect to a center position of the plurality of tap coefficients. The optical disk device according to claim 3, wherein 5. An optical disc apparatus for recording / reproducing information on / from a recordable / reproducible optical disc having a sector format having a pre-pit address, wherein equalization learning is performed with a pre-pit address when recording / reproducing information on / from the optical disc. 4. The optical disc apparatus according to claim 3, wherein tilt control is performed in accordance with an orthogonal shift signal obtained from a tap coefficient of the FIR filter, and recording / reproduction is performed. 6. The orthogonal shift signal obtained from a tap coefficient of an FIR filter learned at a pre-pit address when information is recorded on an optical disk is based on a value learned and stored in advance. Item 6. An optical disk device according to item 5. 7. The FIR learned in advance on a recording track when recording information on or reproducing information from the optical disk.
4. The optical disc apparatus according to claim 3, wherein an orthogonal shift signal obtained from a tap coefficient of the filter is stored, and tilt control is performed in accordance with the stored orthogonal shift signal to perform recording / reproduction. . 8. The orthogonal deviation control means stores an orthogonal deviation signal based on a learning result in an arbitrary track of a disk to be reproduced, and performs tilt control based on the stored value. 4. The optical disk device according to claim 3, wherein: 9. A light beam aberration control apparatus applied to an optical disc apparatus having an FIR filter that generates a plurality of tap coefficients by performing adaptive equalization in a reproduction system, and controls an aberration of a light beam applied to an optical disc from an optical pickup. An aberration detection unit that outputs an aberration detection signal corresponding to the aberration of the light beam using a plurality of tap coefficients of the FIR filter; an aberration correction unit that corrects the aberration of the light beam; And an aberration control means for controlling the aberration correction means to drive the aberration so as to minimize the aberration of the light beam in accordance with the control. 10. The aberration control means performs a comparison operation on at least one combination of a set of tap coefficients symmetrical with respect to a center position of the plurality of tap coefficients,
10. The optical beam aberration control device according to claim 9, wherein the tap coefficient values are controlled to be substantially equal. 11. The aberration correcting means comprises a liquid crystal tilt correcting element divided into a plurality of segments, and performs aberration correction of a light beam by changing a light refractive index of a liquid crystal element for each segment. Claim 9
A light beam aberration control device according to claim 1. 12. An FIR for performing adaptive equalization in a reproduction system.
What is claimed is: 1. An optical disc apparatus comprising: a filter, an optical disc, and an aberration control device configured to control an aberration of a light beam applied to the optical disc to be minimized. An optical pickup for reproducing information recorded on the optical pickup; an A / D converter for converting an analog signal reproduced from the optical pickup into a digital signal; and an FIR filter. An adaptive equalization unit that performs adaptive equalization, wherein the aberration control device outputs an aberration detection signal corresponding to the aberration of the light beam using a plurality of tap coefficients of the FIR filter; Aberration correction means for correcting the aberration of the light beam, and driving control of the aberration correction means according to the aberration detection signal so that the aberration of the light beam is minimized. An optical disc drive, comprising: 13. The aberration control unit performs a comparison operation on at least one combination of a set of tap coefficients symmetrical with respect to a center position of the plurality of tap coefficients,
13. The optical disk device according to claim 12, wherein the tap coefficient values are controlled to be substantially equal. 14. An optical disc apparatus for recording / reproducing information on / from a sector-format recordable / reproducible optical disc having a pre-pit address, wherein equalization learning is performed with a pre-pit address when recording or reproducing information on or from the optical disc. 13. The optical disc apparatus according to claim 12, wherein aberration control is performed according to an aberration detection signal obtained from a tap coefficient of the FIR filter, and recording / reproduction is performed. 15. An aberration detection signal obtained from a tap coefficient of an FIR filter learned at a pre-pit address when recording information on an optical disc is based on a value learned and stored in advance. Item 15. The optical disk device according to item 14. 16. A method according to claim 1, wherein the recording and reproducing of the information on the optical disc is performed by using the FI learned in advance on a recording track.
13. The optical disc according to claim 12, wherein an aberration detection signal obtained from a tap coefficient of the R filter is stored, and aberration control is performed in accordance with the stored aberration detection signal to perform recording / reproduction. apparatus. 17. The aberration control means stores an aberration detection signal based on a learning result in an arbitrary track of a disk to be reproduced, and performs aberration control based on the stored value. 13. The optical disk device according to claim 12, wherein: