JPH11232676A - Optical disk controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk controller, by which the tolerance of a regenerative signal to an inclination in the radial direction of an optical disk is extended. SOLUTION: The optical disk controller has actuators 13b, 13d driving and adjusting an objective lens for an optical pickup 12 regarding the servo direction of an optical disk, control circuits 13a, 13c driving and controlling the actuators in the tracking direction and the focus direction on the basis of a tracking error signal TE and a focus error signal FE by detecting signals from each light-receiving section of divided photodetectors in the optical pickup 12, a measuring means 15 detecting a jitter value on the basis of detecting signals from each light-receiving section of the photodetectors for the optical pickup 12, and an arithmetic circuit 16 imparting offset to the above-mentioned tracking error signal so that the above-mentioned jitter value is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk control device, and more particularly to tracking control.

[0002]

2. Description of the Related Art Conventionally, for example, when reproducing an optical disk, a signal recording surface of an optical disk which is driven to rotate is
Light is emitted from the optical pickup, and the return light is detected by the optical pickup to reproduce a signal from the optical disk. In this case, tracking control is performed so that the light emitted from the optical pickup accurately traces the center of the track on the optical disk.

For example, a push-pull method is known as such tracking control. The push-pull method is
The photodetector of the optical pickup forms a total of four light receiving portions divided into two in the vertical and horizontal directions, that is, in the tracking direction (radial direction) and the track direction (tangential direction) of the optical disk. That is, the push-pull signal is generated based on the difference signal between the detection signals from each set of the light-receiving units divided in the radial direction of the optical disk among the light-receiving units, and the push-pull signal is used as a tracking error signal. The tracking servo is performed.

[0004]

By the way, in such a push-pull method, when the optical disk has an inclination, particularly in a radial direction, a crosstalk component from an adjacent track becomes large, and a spot is formed on the optical disk. Even if the center of the upper track is accurately traced, the quality of the reproduced signal is degraded. For this reason, conventionally, there is a problem that there is only a tolerance of about ± 0.6 to 0.7 degrees with respect to the tilt of the optical disc in the radial direction, and an optical disc having a large warp cannot be reproduced.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide an optical disk control device that increases the tolerance of a reproduction signal with respect to a radial inclination of an optical disk.

[0006]

According to the present invention, a signal recording surface of an optical disk is irradiated with light from an optical pickup, and the return light is detected by the optical pickup to obtain a signal for the optical disk. A control device for an optical disk device for recording and / or reproducing data,
An actuator for driving and adjusting the light focusing means of the optical pickup with respect to the servo direction of the optical disc; and a tracking error signal and a focus error signal generated based on detection signals from the respective light receiving portions of the divided photodetectors of the optical pickup. A control circuit for driving and controlling the actuator in a tracking direction and a focusing direction based on the detection error; a measuring unit for detecting a jitter value based on a detection signal from each light receiving unit of a photodetector of the optical pickup; And an arithmetic circuit for calculating an offset voltage value given to the signal so as to minimize the jitter value.

According to the above arrangement, when performing tracking control or focus control by driving and adjusting the objective lens of the optical pickup in the servo direction, that is, the tracking direction or the focus direction by the actuator, the measuring unit is provided with a photodetector of the optical pickup. The arithmetic circuit applies an offset voltage to the tracking error signal such that the jitter value is minimized based on the detected signal from. Thereby, the trace position of the spot on the optical disk by the tracking servo is optimized with respect to the radial tilt angle of the disk at each time. Therefore, the crosstalk component from the adjacent track is reduced within a range that does not deteriorate the reproduction signal by minimizing the jitter value. Therefore, the tolerance of the tracking error signal is increased with respect to the radial tilt of the optical disk, and even an optical disk having a large radial tilt such as an optical disk having a large warp can be reproduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. still,
Since the embodiments described below are preferred specific examples of the present invention, various technically preferred limitations are added.
The scope of the present invention is not limited to these embodiments unless otherwise specified in the following description.

FIG. 1 shows an optical disk device to which an embodiment of an optical disk control device according to the present invention is applied.
In FIG. 1, an optical disk device 10 includes an optical disk 11
An optical pickup 12 that records or reproduces a signal with respect to an optical disc; an optical disc control device 13 that performs tracking control and focus control of the optical pickup 12;
A data reproducing unit 14 for generating a reproduced signal based on a detection signal from the optical pickup 12, a jitter measuring circuit 15 as a measuring means, an arithmetic circuit 16, and a spindle driving unit for driving the optical disk 11 to rotate at a predetermined rotational speed 1
7 and a sled drive unit 18 for moving the entire optical pickup 12 in the radial direction of the optical disk. Here, the jitter measuring circuit 15 and the arithmetic circuit 1
6 is configured in the optical disk control device 13.

The optical pickup 12 is supported so as to be movable in two axial directions, that is, in a tracking direction and a focusing direction, with respect to the optical disk 11, irradiates the signal recording surface of the optical disk 11 with light, and detects the return light. It has become. Here, the optical pickup 12
As shown in FIG. 2, the photodetector 12a is divided into four light receiving sections A, B, C, and C in the tracking direction (radial direction) and the track direction (tangential direction) of the optical disk.
D. The light receiving sections A, B, C, and D output detection signals Sa, Sb, Sc, and Sd, respectively. Then, from these detection signals, a reproduction signal RF is obtained as a sum signal of the detection signals from all the light receiving units by, for example, an arithmetic circuit or the like configured adjacent to the photodetector. Further, based on the detection signal of each light receiving unit, (Sc + Sd)-(Sa
+ Sb), a tracking error signal TE by the DPD method and a focus error signal FE by (Sd + Sb)-(Sc + Sa) are generated.

[0011] The optical disk control device 13 uses the detection signal detected by the above-described optical pickup 12 to generate a D signal.
A tracking servo circuit 13a for performing tracking control based on a tracking error signal TE generated by the PD method; and an optical pickup 1 based on a tracking control signal from the tracking servo circuit 13a.
(2) a tracking actuator 13b for driving and adjusting an objective lens (not shown) as a light focusing means in the tracking direction, and a focus error signal FE similarly generated from a detection signal from the optical pickup by an astigmatism method. A focus servo circuit 13c for performing focus control, and the focus servo circuit 13c
And a focus actuator 13d that drives and adjusts the objective lens of the optical pickup 12 in the focus direction based on the focus control signal from the camera.

The data reproducing section 14 includes an equalizer 14a, a reproduced signal processing circuit 14b, a demodulation and error correction circuit 14c, and a PLL circuit 14d which are connected in sequence. The equalizer 14a detects detection signals Sa, Sb, Sc, and S from the photodetector of the optical pickup 12.
With respect to d, the reproduction signal RF, which is the sum signal thereof, is input, and equalization processing is performed. The reproduction signal processing circuit 1
4b performs correction (asymmetry correction) of the output signal from the equalizer 14a, and outputs the correction signal to the PLL circuit 1
4d. Further, a binarization process is performed by receiving a synchronization clock from the PLL circuit. Then, the reproduction signal processing circuit 14b outputs the binary data relating to the reproduction signal RF to the demodulation and error correction circuit 14c. The PLL circuit 14d outputs a phase error signal for generating a synchronous clock to the jitter measuring circuit 15. Thereby, the jitter measuring circuit 15
Then, the jitter is calculated. The demodulation and error correction circuit 14c performs demodulation processing and error correction processing of the binary data using a clock signal generated by the PLL circuit 14d based on the reproduction signal (correction signal).

The jitter measuring circuit 15 measures a jitter value of a reproduced (RF) signal based on a phase error signal for generating a synchronous clock provided from the PLL circuit 14d. The arithmetic circuit 16 performs an arithmetic operation based on the jitter value from the jitter measuring circuit 15,
As described later, an offset signal that minimizes the jitter value is generated and output to the tracking servo circuit 13a. Specifically, a predetermined voltage value for correcting the jitter value of the reproduced signal is obtained, and the determined voltage value is provided to the tracking servo circuit 13a as an offset voltage value corresponding to the predetermined voltage value. As a result, the tracking servo circuit 13a performs tracking control based on the tracking error signal TE from the optical pickup 12 and the offset signal (voltage) from the arithmetic circuit 14f.

Further, the spindle drive unit 17 includes a spindle motor 17a for driving the optical disc 11 to rotate.
, Rotation detecting means 17b, spindle servo circuit 17
and a spindle drive circuit 17d. The rotation detecting means 17b detects the rotation speed of the spindle motor 17a and outputs a detection signal. The spindle servo circuit 17c includes the rotation detecting unit 1
The spindle error signal SPE is output based on the detection signal from the optical pickup 7b and a thread position signal indicating the thread position of the optical pickup 12. The thread position signal is detected by a thread position detecting means 12a provided in the optical pickup 12. Spindle drive circuit 1
7d drives and controls the spindle motor 17a based on a spindle error signal from the spindle servo circuit 17c, and drives the spindle motor 17a to rotate at a predetermined rotation speed.

The thread drive section 18 includes a smoothing circuit 18a for smoothing a tracking control signal from a tracking servo circuit 13a of the optical disk control device 13.
, A thread servo circuit 18b, and a thread driving unit 1
8c. The smoothing circuit 18a detects the deviation of the thread position by smoothing the tracking control signal, and outputs this detection signal. The thread servo circuit 18b outputs a thread error signal based on the detection signal from the smoothing circuit 18a. The sled drive unit 18c drives the optical pickup in sled, that is, drives and controls the optical pickup 11 in the radial direction based on the sled error signal.

The optical disk device 10 according to the present embodiment comprises:
It is configured as described above and operates as follows.
First, the optical disk 11 is rotationally driven by the spindle drive unit 17, and the optical pickup 12 is moved by the sled drive unit 18 along the guide (not shown).
By moving the objective lens in the radial direction, the optical axis of the objective lens is moved to a desired track position on the optical disk 11 to perform access.

In this state, the light beam emitted from the optical pickup 12 is focused on the signal recording surface of the optical disk 11, and the return light from the optical disk 11 is incident on the photodetector 12a of the optical pickup 12. Then, detection signals Sa, Sb, Sc, and Sd are output from the respective light receiving portions A, B, C, and D of the photodetector 12a to generate a reproduction signal RF and a tracking error signal TE.
And a focus error signal FE.

As a result, the reproduced signal RF is input to the equalizer 14a of the data reproducing section 14, where it is equalized, corrected by the reproduced signal processing circuit 14b, binarized, and then demodulated and error corrected by the demodulation and error correction circuit 14c. Is entered into
Based on the clock signal from the PLL circuit 14d, the signal is demodulated and error-corrected, and is output to the outside as a reproduced signal.

The jitter value is input to an arithmetic circuit 16 and an offset signal (offset voltage) for minimizing the jitter value is generated. This offset signal is output to the tracking servo circuit 1 of the optical disk controller 13.
3a.

Here, the jitter value of the reproduced signal RF changes with respect to the offset signal as shown in the graph of FIG. That is, in the case of an offset signal that completely cancels the offset, the objective lens is held on-track by the tracking control, and the jitter value of the detection signal changes as shown by a curve a in the graph of FIG. .

On the other hand, when the offset due to the offset signal corresponds to, for example, + 5% and + 10% of detrack, the jitter value is represented by the curves b and b in the graph of FIG.
In the case of changing as shown by c, for example, corresponding to -5% and -10% of detrack, the jitter value changes as shown by curves d and e in the graph of FIG.

Therefore, in this embodiment, the arithmetic circuit 16 generates an offset signal based on the result measured by the jitter value measuring circuit 15 for the current jitter value so that the jitter value is minimized. Specifically, the arithmetic circuit 16 generates, for example, an offset signal that gives a predetermined voltage to the tracking error signal. In this case, the arithmetic circuit 16 calculates the voltage value and the degree of cancellation of the correction offset corresponding to the voltage value, for example, based on a predetermined function given by measurement in advance. Alternatively, a memory (not shown) is provided inside or outside the arithmetic circuit 16 and holds table data regarding the voltage value and the degree of removal of the offset.
The offset signal may be generated by selecting a corresponding voltage value from a predetermined table value based on the result measured by the jitter value measurement circuit 15.

By providing this offset signal to the tracking servo circuit 13a, the tracking servo circuit 13a generates a corrected offset tracking control signal based on the above-mentioned tracking error signal TE and this offset signal. , The drive control of the tracking actuator 13b is performed. Thereby, the tracking error signal T
Since an offset signal that minimizes the jitter value is given to E, the signal is reduced to the extent that the reproduced signal does not deteriorate. Therefore, even for an optical disk having a large inclination, such as an optical disk having a large warp, a spot is traced at a position on the optical disk where the crosstalk component from an adjacent track is reduced, so that tolerance is increased. Is enlarged. In the present invention, the means for obtaining the tracking error signal is not limited to the above embodiment, but may be obtained by any method.

[0024]

As described above, according to the present invention, it is possible to provide an optical disk control device in which the tolerance of the reproduction signal with respect to the radial inclination of the optical disk is increased.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a configuration of an optical disk device incorporating an embodiment of an optical disk control device according to the present invention.

FIG. 2 is a schematic plan view showing a photodetector of an optical pickup in the optical disk device of FIG.

FIG. 3 is a graph showing a jitter value by a jitter measuring circuit when an offset signal is changed in the optical disc device of FIG. 1;

[Explanation of symbols]

10 optical disk device, 11 optical disk, 1
2 ... optical pickup, 13 ... optical disk control device, 13a ... tracking servo circuit, 13b
..Tracking actuator, 14 ... data reproducing unit, 14a ... equalizer, 14b ... binarization circuit, 14c ... demodulation and error correction circuit, 14d ...
・ PLL circuit, 15 ・ ・ ・ Jitter measurement circuit, 16 ・ ・
· Arithmetic circuit, 17 ··· spindle drive unit, 18 ···
Thread drive.

Continued on the front page (72) Inventor Nobuyasu Kikuchi 6-35 Kita Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (2)

[Claims] 1. A control device of an optical disk device for irradiating a signal recording surface of an optical disk with light from an optical pickup, detecting the return light by the optical pickup, and recording and / or reproducing signals on the optical disk. An actuator for driving and adjusting the light focusing means of the optical pickup with respect to the servo direction of the optical disc; a tracking error signal generated based on a detection signal from each light receiving unit of the divided photodetector of the optical pickup; and A control circuit that drives and controls the actuator in a tracking direction and a focus direction based on a focus error signal, and a measuring unit that detects a jitter value based on a detection signal from each light receiving unit of a photodetector of the optical pickup, In response to the tracking error signal, Optical disk control device, characterized in that it includes a calculating circuit for obtaining an offset voltage value applied to minimize the over value. 2. The measuring means measures a jitter value based on a reproduced signal and a synchronous clock based on the reproduced signal, and the arithmetic circuit determines an offset voltage so as to minimize the jitter measured value, and calculates a tracking error. 2. The optical disk control device according to claim 1, wherein the optical disk control device is configured to be added to a signal.