KR20000026832A - Method for controlling tilt - Google Patents

Abstract

PURPOSE: A method for controlling tilt is provided to stably and accurately detect a tilt by compensating the tilt using a set amount of controlling tilt and operating a disk. CONSTITUTION: An optical pick-up(101) records and reproduces information to an optical disk(100). A tracking error detecting unit(102) detects a TE(Tracking Error) signal using an electric signal outputted from the optical pick-up(101). A DC offset detecting unit(103) detects a DC offset component of the TE signal detected at a predetermined position. An RF level detecting unit(104) detects a level of an RF signal for detecting as to whether a previously compensated tilt is normally compensated when operating a disk. A microprocessor(105) computes a tilt control amount in a corresponding position from the DC offset value of the DC offset detecting unit(103) to store the computed value to a database and performs a verification of a tilt compensation. A tracking servo(106) controls a tracking actuator of the optical pick-up(101) using the TE signal. A tilt controller(107) compensates a tilt according to a control of the microprocessor(105).

Description

Tilt Control Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density optical recording medium system, and more particularly, to a tilt control method for detecting a tilt control amount through an optical recording medium initialization process and applying the same when operating the optical recording medium.

In general, optical recording media are classified into three types, such as read-only ROM, write-once worm type, and rewritable rewritable type. Lose.

The ROM type optical recording medium may include a compact disc read only memory (CD-ROM) and a digital versatile disc read only memory (DVD-ROM), and a worm type optical recording medium may be written once. Recordable Compact Discs (CD-Rs) and Recordable Digital Versatile Discs (DVD-Rs).

In addition, freely rewritable discs include a rewritable compact disc (CD-RW), a rewritable digital versatile disc (DVD-RW, DVD-RAM), and the like.

The above-described rewritable optical recording medium, such as an optical disc, has a signal track having a structure of land and groove, so that tracking control can be performed even on a blank disc in which no information signal is recorded. In order to increase the recording density, an information signal is recorded on each track of a mountain and a valley. That is, the wavelength of the laser light of the optical pickup for recording / reproducing is shortened, and the numerical aperture of the objective lens for condensing is increased to reduce the size of the light beam for recording and reproducing.

In addition, in high density optical discs, the distance between signal tracks, that is, the signal track pitch, is reduced in order to increase the recording density.

On the other hand, such an optical disk may be distorted during the injection and curing of the resin in the manufacturing process, which may cause eccentricity even if the center hole is drilled. Further, even if the disc track is accurately recorded in a spiral shape at a pitch of a predetermined standard, an eccentricity is generated because the center hole is varied. Thus, the disk rotates with eccentricity, so it is difficult for the central axis of the motor and the center of these tracks to completely coincide.

Therefore, since it is difficult to read exactly the signal of the desired track accurately, the CD and DVD system sets the standard for this misalignment amount, and the tracking servo is performed so that the light beam can always follow the desired track even if such eccentricity occurs.

That is, the tracking servo generates an electric signal corresponding to the beam trace state and based on the signal, moves the objective lens and the optical pickup main body in a radial direction to correct the position of the beam to accurately track the track.

On the other hand, when the beam deviates from the track, not only the eccentricity of the disc described above but also the case where the disc is inclined. This can occur due to mechanical problems such as errors when mounting the disk to the spindle motor. That is, the focusing and tracking do not exactly match vertically, but are distorted. In this way, the disk is tilted.

This tilt was not a big problem for CDs with large track pitches because of their wide track pitch. Here, the tilt margin is an amount that can be corrected even if the disk is inclined to some extent. However, in DVDs whose track pitch is narrowed due to high density, the tilt margin is small, so that even if only a small tilt occurs, that is, the disc is tilted slightly, the beam passes over to the next track. In this case, the tracking servo is not enough. That is, even if the track is moved to the side track, the tracking servo can determine that the track is correctly tracked if the beam is in the center of the track.

In this case, data cannot be read correctly during reproduction, and since the data cannot be recorded accurately on the track during recording, double distortion occurs when the recorded data is reproduced.

Therefore, as a method for solving the above-mentioned tilt, there is a method of detecting the tilt of the disk with a dedicated tilt sensor for detecting the tilt in the pickup, for example, a tilt-only light receiving element. However, the above-described method has a problem in that the size of the set becomes large while the efficiency is not very good.

The present invention is to solve the above problems, an object of the present invention is to set the tilt control amount by detecting the DC offset of the tracking error for each disc position while moving the optical pickup in the disc radial direction at the beginning of the disc mounting The present invention provides a tilt control method of applying this to each disk position when operating a disk.

1 is a block diagram of an optical disk recording / reproducing apparatus for tilt control according to the present invention.

FIG. 2A is a diagram illustrating an example in which tilt occurs in the optical disk of FIG. 1; FIG.

FIG. 2B illustrates a relationship between a tracking error signal and a DC offset according to a tilt state as shown in FIG. 2A.

2C is a view showing an example of the tilt control amount according to the tilt state as shown in FIG. 2A

FIG. 2D illustrates an example of an RF signal in a tilted state as shown in FIG. 2A

Explanation of symbols for main parts of the drawings

100: optical disk 101: optical pickup

102: tracking error detector 103: DC offset detector

104: RF level detector 105: Micom

106: tracking servo 107: tilt controller

The tilt control method according to the present invention for achieving the above object, the initial detection step of detecting and storing the tilt control amount of the optical disk for each predetermined disk position when the optical disk is mounted, and the tilt obtained in the step when operating the disk And a compensation step of performing tilt compensation by applying the control amount according to the disk position.

The initial detecting step includes detecting a tracking error signal while transferring the optical pickup from the inner circumference to the outer circumferential direction, detecting a DC offset component of the tracking error signal at a predetermined disk position, and detecting the DC offset component at each position from the detected DC offset component. Obtaining a tilt control amount, and storing the tilt control amount by database.

The disk position of the step is characterized in that a plurality of predetermined intervals.

The disk position of the step is characterized in that a plurality is specified so that the interval becomes narrower from the inner circumference to the outer circumference.

The DC offset detecting step is characterized by detecting the DC offset component of the averaged value after averaging the tracking error signal.

The tilt compensating step detects the level of the RF signal at the corresponding position while compensating the tilt of the position using the tilt control amount for each position of the optical recording medium initially set at the time of recording / reproducing the data, and then detects the level of the RF signal at the position. Characterized in verifying the compensation.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

The present invention determines a plurality of positions (or regions) on the disc in advance, and detects the DC offset component of the tracking error at each position while transferring the optical pickup from the inner circumference to the outer circumference at the initial stage when the disc is mounted, and the tilt control at that position. After setting the amount, the tilt is compensated first by the set tilt control amount according to the position of the disc when the disc is operated, and then recording / playback is performed.

FIG. 1 is a block diagram of an optical disk recording / reproducing apparatus according to the present invention for tilt control. An optical disk 100 capable of rewriting data and an optical pickup for recording and reproducing information on the optical disk 100 are shown in FIG. (101), a tracking error detection unit (102) for detecting a tracking error (TE) signal using an electrical signal output from the optical pickup (101), for detecting a DC offset component of the detected TE signal at a predetermined position DC offset detector 103, an RF level detector 104 for detecting the level of the RF signal to detect whether the tilt is compensated in advance during the operation of the disc, and the DC offset value of the DC offset detector 103 at the corresponding position The microcontroller 105 obtains the tilt control amount of the database and performs database verification, and performs verification of the tilt compensation by comparing the detected RF level during the disc operation, and the optical pickup 1 using the TE signal. A tracking servo 106 for controlling the tracking actuator of 01) and a tilt controller 107 for compensating for tilt by the control of the microcomputer 105. The tilt controller 107 is a tilt servo mechanism that corrects tilt by moving the optical pickup or by moving the disk itself.

The present invention configured as described above transfers the optical pickup 101 from the inner circumference to the outer circumferential direction at the initial stage when the disk is mounted or the optical disk recording / reproducing apparatus is turned on. Then, the TE detector 102 may detect the tracking error signal according to the movement of the optical pickup 101. In this case, the DC offset detector 103 detects a DC offset value of the TE signal detected at a predetermined position.

In other words, the position of detecting the DC offset is predetermined on the disk, and a plurality of positions having a predetermined interval may be specified, and the tilt increases as the outer periphery increases, so that the plurality of positions are densified toward the outer periphery for precise control. You can also specify. In other words, it takes a long time to detect a DC offset across all areas of the disk, so it specifies a number of locations.

If there is an optical disc mounting or a tilt of the disc itself as shown in FIG. 2A, and it exists with a predetermined angle in the upward direction and the positions A, B, and C are previously specified, the DC offset component of the tracking error signal is As shown in FIG. 2B, it becomes larger toward the outer periphery direction (A <B <C).

In this case, the DC offset detection unit 103 detects the peak-to-peak of the tracking error signal during DC offset detection to remove the component of the eccentricity, averages the center level, and then averages the tracking. Detect the DC offset component of the error signal.

The microcomputer 105 receives a DC offset value at a predetermined position from the DC offset detector 104 to obtain and store a tilt control amount of the corresponding position as shown in FIG. 2C. That is, the tilt control amount at each position is databased.

Then, recording or reproduction is performed at the request of the user.

At this time, when the optical pickup 101 comes to the designated position, for example, the A position, the microcomputer 105 controls the tilt controller 107 to compensate for the tilt by the tilt control amount set at the A position first, and then records / plays back at the A position. Do this. That is, the disk 100 or the optical pickup 101 is moved by the tilt control amount of the database A position, which is opposite to the direction in which the tilt is generated, for example, downward. At the same time, the RF level detector 104 detects the level of the RF signal using the electrical signal output from the optical pickup 101 to verify whether the tilt compensation is properly performed. If the tilt is not corrected, the RF level at positions A, B, and C is changed as shown in FIG. 2D.

That is, since the level of the RF signal is reduced in magnitude when the tilt is not completely compensated, the microcomputer 105 may know the compensation state of the tilt through the level of the RF signal. In this case, the mirror area where no pit or marking is present always has the same RF level when the amount of laser diode is constant. Can be verified accurately

When the microcomputer 105 determines that the tilt is not completely compensated through the level of the RF signal, the microcomputer 105 obtains and stores the tilt control amount based on the DC offset value. Afterwards, when it comes back to the A position, verification is simultaneously performed while compensating the tilt with the tilt control amount.

By this process, when the optical pickup 101 comes to another designated position, for example, the B position, the above-described process is repeated as it is.

As described above, according to the tilt control method of the present invention, the DC offset component of the tracking error signal at a predetermined position while transferring the optical pickup from the inner circumference to the circumferential direction at the initial stage when the optical disk is mounted or the optical disk recording / reproducing apparatus is turned on. Is detected, and the tilt control amount is database-configured from the detected DC offset value, and then the disc is operated by compensating the tilt with the set tilt control amount according to the disc position and then operating the disc. The tilt can be detected and compensated stably and accurately without using a light receiving element. In addition, in the recording / reproducing process of the data, the tilt is compensated for each position by the tilt control amount calculated in advance, and then verified using the level of the RF signal, thereby enabling more accurate tilt control.

Claims (7)

An optical recording medium recording / reproducing apparatus which performs tracking servo and focusing servo by detecting a tracking error signal and a focusing error signal by using an electrical signal of an optical pickup that receives a laser at a designated position of the optical recording medium and then picks up the reflected light. In the tilt control method of, An initial detection step of detecting and storing the tilt control amount of the optical recording medium for each predetermined position of the optical recording medium when the optical recording medium is mounted; And a compensation step of performing tilt compensation by applying the tilt control amount obtained in the step according to the position of the optical recording medium when the optical recording medium is operated. The method of claim 1, The initial detection step Detecting a tracking error signal while transferring the optical pickup from an inner circumference to an outer circumference direction; Detecting a DC offset component of the tracking error signal for each optical record medium position and obtaining a tilt control amount at each position from the detected DC offset component; And tilting the tilt control amount into a database. The method of claim 2, The optical record carrier position of the step A tilt control method, characterized in that a plurality of positions are set to have a constant interval. The method of claim 2, The optical record carrier position of the step Tilt control method, characterized in that the plurality of positions are set so that the interval becomes narrower from the inner circumference to the outer circumference. The method of claim 2, The DC offset detection step And averaging the tracking error signal and detecting a DC offset component of the averaged value. The method of claim 5, The DC offset detection step And detecting a peak-to-peak of the tracking error signal and averaging a center level. The method of claim 1, The tilt compensation step When recording / reproducing data, the tilt control amount for each position of the optical recording medium which is initially set is compensated for, and then the recording / reproducing is performed to detect the level of the radio frequency (RF) signal at the corresponding position to perform tilt compensation. Tilt control method characterized in that the verification.