KR20040049463A - Method and apparatus for compensating disc tilt - Google Patents

Abstract

PURPOSE: A method and a device for compensating the tilt of an optical disc are provided to compensate the tilt based on a correlation equation generated by using the inner/outer circumference information data for a measuring position and an inner/outer circumference tilt of the optical disc. CONSTITUTION: An RF amplifier(320) generates a focus error signal and a tracking error signal by the lens-up/down of a pickup(314). A system controller(324) measures the tilt at an inner/outer circumference through the focus error signal and the tracking error signal generated from the RF amplifier, and reads the information data of the inner/the outer circumference at a measuring position of the optical disc. The system controller compensates the tilt for a search target position by generating the correlation equation with use of the tilt data and the position information data for the inner/outer circumference.

Description

Tilt correction method and apparatus for optical discs {Method and apparatus for compensating disc tilt}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing system, and more particularly, to a tilt correction method and apparatus for correcting tilt using an equation generated from a tilt amount and measurement position data in an optical disk.

Since compact disc-ROM (CD-ROM) which is an early optical disc, the density of an optical disc and the high speed of an optical recording / reproducing apparatus are rapidly developing. Recently, optical discs capable of recording as well as reproducing information have emerged.

In order to stably record / reproduce information on such a high density optical disk, the angle between the optical axis of the light beam emitted from the optical pickup and the reflecting surface of the optical disk must be adjusted to be vertical.

In general, when the optical axis of the light beam emitted from the optical pickup is not perpendicular to the disk reflecting surface, the reproduction signal is degraded, thereby reducing the signal-to-noise ratio of the reproduction signal.

The reason why the optical axis is not perpendicular to the disc is the error of the optical pickup itself, the error of various peripheral parts, the distortion of the disc, and the like. The disc deviation from the optical axis from the optical axis is called tilt, and is reproduced according to the degree of tilt. The degree of error will vary.

In general, it is known that normal reproduction is impossible when jitter corresponding to a reproduction error is 15% or more.

The change in the jitter amount according to the tilt angle is shown in FIG. 1. In FIG. 1, the solid line portion corresponds to the DVD-ROM, and the dotted line portion corresponds to the CD-ROM. As can be seen from FIG. 1, as the tilt angle is increased, the jitter increases in a parabolic form. Therefore, if the tilt angle can be maintained at zero, it is possible to minimize jitter causing an error in the reproduction signal. In particular, since the jitter changes very sensitively to the tilt angle when playing a high-density disc such as a DVD-ROM or a DVD-RAM, even if the tilt angle caused by various components' errors and assembly accumulation errors is small, normal playback is not possible. It becomes impossible.

Therefore, the optical disk reproducing / recording apparatus can correct normal tilt only when the tilt amount is corrected.

2 is a conceptual diagram showing a tilt correction method in a conventional optical disc reproducing / recording apparatus.

2, the tilt adjustment range is divided by a predetermined number from the inner circumference to the outer circumference of the disc. For example, the tilt amount estimation points are set to A, B, C, D, and E in the disk, and the tilt adjustment range is divided into six. Then, the tilt is corrected individually by interpolation for each of the divided tilt adjustment ranges.

However, the conventional tilt correction method has a problem in that the tilt correction takes a long time and the precision decreases because the number of tilt measurements and corrections is large.

An object of the present invention is to provide a tilt correction method and apparatus for correcting the tilt amount based on an equation generated using the inner and outer circumference tilt amount of the disk and the inner and outer circumference information data on the measurement position.

MEANS TO SOLVE THE PROBLEM In order to solve the said technical subject, in the tilt correction method of an optical disc recording / reproducing apparatus, the present invention is a tilt correction method of the optical disc recording / reproducing apparatus.

(a) calculating data corresponding to the amount of tilt in the inner and outer circumferences of the disk;

(b) reading predetermined position information data at inner and outer circumferences of the measured position of the disk;

(c) generating equations for the tilt data of the inner and outer circumferences calculated in step (a) and the position information data of the inner and outer circumferences calculated in step (b);

and (d) correcting the tilt amount corresponding to the search target position based on the equation generated in step (c).

MEANS TO SOLVE THE PROBLEM In order to solve the said another technical subject, this invention is the tilt correction apparatus of the optical disc recording / reproducing system, The tilt correction apparatus of the optical disc recording / reproducing system,

An RF amplifier configured to generate a focus error signal and a tracking error signal through lens up and down of the pickup;

The tilt amount is measured at the inner and outer circumferences of the disk through the focus error and tracking error signals generated by the RF amplifier, leads to predetermined information data at the inner and outer circumferences of the measuring position of the disk, and the inner and outer tilt amount. And a system controller for generating an equation for the position information data and correcting the tilt amount corresponding to the search target position.

1 is a characteristic diagram illustrating a change in jitter according to a tilt angle in CD-ROM and DVD-ROM.

2 is a conceptual diagram showing a tilt correction method in a conventional optical disc reproducing / recording apparatus.

3 is an overall block diagram of an optical disc recording / reproducing apparatus according to the present invention.

4A and 4B are flowcharts illustrating a tilt correction method according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3 is an overall block diagram of an optical disc recording / reproducing apparatus according to the present invention.

The operation of the optical disc recording / reproducing apparatus shown in FIG. 3 is divided into a recording mode and a reproduction mode as follows.

In the recording mode, the DSP (Digital Signal Processor) unit 322 adds an error correction code (ECC) to the encoded audio / video data and picks up the unit 314 according to the lens up and down commands of the system controller 324. Generates a signal for driving the lens.

The RF amplifier 316 converts an electrical signal input from the DSP unit 322 into an optical signal. The pickup section 314 includes an actuator for focusing and tracking, and records the optical signal converted by the RF amplifier 316 on the disk 312.

The servo unit 318 receives the information necessary for servo control from the DSP unit 322 through the RF amplifier 316 and the system controller 324 to perform stable servo.

The system controller 324 controls the entire system and records data on the disk 312 through the DSP unit 322, the RF amplifier 320, and the pickup unit 314 whenever the user inputs desired information.

On the other hand, in the playback mode, the pickup section 314 reads the optical signal from the disk 312 which stores data.

The RF amplifier 320 converts an optical signal output from the pickup unit 314 into an electrical signal, extracts a servo signal and modulation data for performing servo, and focus error from the optical signal output from the pickup unit 314. The signal and tracking error signal and the S-curve signal are detected.

The DSP unit 322 demodulates the modulated data extracted from the RF amplifier 316, performs ECC, removes additional data while correcting an error, and picks up according to a lens up and down command of the system controller 324. The unit 314 generates a signal for driving the lens.

The servo unit 318 receives information necessary for servo control from the RF amplifier 320 and the system controller 324 to perform stable servo.

The system controller 324 controls the pickup unit 314, the RF amplifier 320, and the DSP unit 322 according to a command input by a user. In particular, the system controller 324 controls the pickup error signal generated by the RF amplifier 320. The amount of tilt is measured at the inner and outer circumferences of the disk through the tracking drive signal or the S-curve detection signal, the predetermined information data is read at the inner and outer circumferences of the measuring position of the disk, and the calculated inner and outer circumference tilt data and information data. Create an equation using to correct the tilt amount corresponding to the search target position.

The storage unit 326 stores data on the amount of tilt calculated by the system controller 324 and predetermined information data at the inner and outer periphery at the measurement position of the disk, for example, distance data at the measurement position, and S-curve detection time data. Stores address data, time information data, and the like.

4A and 4B are flowcharts illustrating a tilt correction method according to the present invention.

First, when the disc is inserted into the turntable (step 412), the optical pickup for irradiating the beam to the recording surface of the disc is raised for a predetermined time and then lowered to measure the reference voltage of the focus error signal for measuring the tilt amount (step 414). ).

Then, the spindle servo is turned on to rotate the disk (step 416).

Next, the disc type mounted on the turntable is determined (step 418). For example, CDs and DVDs are determined according to the size of the initial RF signal.

Next, the focus server loop is operated in the state where the disk type is determined (step 422).

The tracking servo is then operated to automatically adjust parameters for disk drive, such as balance, tracking error gain, focus error gain, and RF gain (step 424).

Subsequently, the tilt amount of the disk inner and outer circumferences is measured based on the voltage of the focus error signal (step 426). For example, the amount of tilt is determined by the jitter best point (minimum jitter) at the inner and outer positions using the focus error values at the inner and outer disks, the position of the S-curve at the inner and outer disks, the focus drive value, and the tracking drive value. Tilt angle). Alternatively, a table is generated in which the jitter amount and the tilt angle correspond to each other based on the obtained jitter best point.

Subsequently, the tilt amount measured in the inner and outer circumferences of the disk or the tilt amount data set by the table is read (step 432).

Next, the positional information data of the inner circumference and the outer circumference at the measurement position is read (step 434). For example, the position information data corresponds to distance data at the measurement position, data of the S-curve detection time, data of time information, and the like.

Subsequently, equations such as a straight line passing through two points, an equation of a curve, and an equation of a curve passing through three points are generated using the measured tilt data of the disk and the position information data at the measurement position (step 436). .

Subsequently, information (address) on the target location to be searched is input (step 438).

Subsequently, the tilt amount corresponding to the search target position is corrected based on the obtained equation (step 442). For example, assuming that the data corresponding to the inner circumference (x0, y0) and the outer circumference (x1, y1) are the inner circumference (0, 0) and the outer circumference (20, 20) on the disk, the equation y = ax + b passing two points Let's apply. Here, the tilt amount measured at the inner circumference is y0, the tilt amount measured at the outer circumference is y1, the position information data of the inner circumference x0, and the position information data of the outer circumference are x1. Then 1) 0 = a * 0 + b, b = 0, and 2) 20 = a * 20 + 0, a = 1. Thus y = x holds. Therefore, if the target position is 10 seconds, since y = 10, the correction corresponding to the tilt amount 10 is performed.

The present invention is not limited to the above-described embodiment, and of course, modifications may be made by those skilled in the art within the spirit of the present invention.

As described above, according to the present invention, since the tilt correction is performed in the entire disc section by correcting the tilt amount through the equation generated by the information of the tilt amount and the measurement position in the inner and outer circumference of the disk, the tilt correction time is increased. It can be shortened and the precision increased.

Claims (5)

In the tilt correction method of the optical disk recording / playback apparatus, (a) calculating data corresponding to the amount of tilt in the inner and outer circumferences of the disk; (b) reading position information data of an inner circumference and an outer circumference at the disc measuring position; (c) generating a predetermined equation from the tilt data of the inner and outer circumferences calculated in step (a) and the position information data of the inner and outer circumferences calculated in step (b); and (d) correcting the tilt amount corresponding to the search target position based on the equation generated in step (c). The tilt correction method according to claim 1, wherein the information data of the measurement position of the disc is one of distance data at the measurement position, data of S-curve detection time, and data of time information. The tilt correction method according to claim 1, wherein the tilt amount between the inner and outer circumferences of the disk is measured at a tilt angle with a minimum jitter amount. The tilt correction method according to claim 1, wherein the step (d) corrects the tilt amount determined according to the equation for every predetermined position when the tilt amount data and the outer and outer position information data of the disk are set. . In the tilt correction apparatus of the optical disc recording / playback system, An RF amplifier configured to generate a focus error signal and a tracking error signal through lens up and down of the pickup; The tilt amount is measured at the inner and outer circumferences of the disk through the focus error and tracking error signals generated by the RF amplifier, and the position information data of the inner and outer circumferences at the measured position of the disk is read, and then the inner and outer tilt amount data. And a system controller for generating a predetermined equation from the inner and outer circumference position information data to correct a tilt amount corresponding to a search target position.