KR100587268B1 - Recording and reproducing method of optical record carrier and device therefor - Google Patents

Abstract

A method and apparatus for recording and reproducing an optical recording medium for detecting and compensating for a detrack of an optical recording medium in a high density optical recording medium system, and particularly, a method of performing wobble signals formed in a wobbling form in a user area in which actual data is recorded. By detecting the detrack with the level change, it is possible to prevent the deterioration of data due to the detrack during recording and reproduction, to stabilize the tracking servo quickly, and to operate the system stably.

De-Track, Wobble

Description

Method for recording and reproducing an optical record carrier and its apparatus {Method for recording / playing of optical record medium and apparatus for the same}

1 is a block diagram of a recording and reproducing apparatus of an optical recording medium according to the present invention;

2 is a diagram illustrating an example of the photo detector of FIG. 1;

3 is a graph illustrating an example in which a level of a wobble signal is changed due to a detrack offset change.

4A to 4C illustrate an example in which the level of the wobble signal varies according to the detrack offset.

Explanation of symbols for main parts of the drawings

101: optical disk 102: optical pickup

103: high frequency (RF) and servo error generation unit 104: de-track detection unit

105: servo control unit 106: tracking drive unit

The present invention relates to an optical recording medium system, and more particularly, to a method and apparatus for detecting and compensating for a detrack of an optical recording medium.

In general, optical recording media are largely divided into three types: read-only ROM, write-once worm type, and rewritable rewritable type. Lose.

Among these, freely and repeatedly rewritable optical recording media such as an optical disc include a rewritable compact disc (CD-RW) and a rewritable digital versatile disc (DVD-RW, DVD-RAM, DVD). + RW).

The above-described rewritable optical recording medium, such as an optical disc such as a DVD-RAM, has a signal track having a structure of mountains and grooves, so that tracking control can be performed even on a blank disc in which no information signal is recorded. Recently, in order to increase the recording density, information signals are recorded on the tracks of the hills and valleys, respectively. 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 such a rewritable high-density optical disc, the distance between signal tracks, that is, the signal track pitch, is reduced to increase the recording density.

In this case, in the case of a rewritable disc, since the first disc has no information, disc control and recording are impossible.

For this purpose, disc tracks are created in lands and grooves, and information is recorded along the tracks. Information for random access and rotation control is recorded separately on the disc, so that tracking control can be performed on a blank disc in which no information signal is recorded. To do it.

The control information may be recorded by pre-formatting the header area at the start of the sector for each sector, or may be recorded in a wobbling shape along the track of the user area in which the actual data is recorded. It may be.

Here, the wobbling is a modulated clock that modulates a constant clock to supply information to the disk, for example, information on the corresponding position, information about the rotation speed of the disk, and the like to the power of the laser diode, thereby controlling the information by changing the light beam of the laser. Is recorded at the boundary of the track.

In order to record information on such an optical disc or to reproduce the recorded information, tracking control is performed through an optical pickup.

That is, the tracking control, for example, the tracking servo detects a tracking error signal from an electrical signal generated corresponding to the beam trace state and radially rotates the objective lens of the optical pickup by driving a tracking actuator in the optical pickup according to the tracking error signal. Direction to correct the position of the beam and follow a predetermined track.

At this time, even if the tracking error signal is zero, a detrack may occur in which the optical focus is shifted from the track center. This detrack was not a problem in the CD world.

However, in optical discs that can record and play data in both lands and grooves, such as DVD-RAM, track pitches are narrow for higher density, and when such detracks occur, the side tracks are much affected.

In addition, even if the tracking is correct in the track of the land by the depth difference between the land and the groove, if it is applied to the track of the groove as it is, the groove may not be on-track. That is, detracking may occur. Similarly, when tracking is tracked on the groove track, detrack may occur in the track of the land due to the depth difference between the land and the groove.

Therefore, in such a detrack state, since the beam easily passes to the adjacent track, crosstalk is generated a lot, and data recording / reproducing, such as erasing the data of the adjacent track, becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for recording and reproducing an optical recording medium for detecting and adjusting a detrack by a level change of a wobble signal formed in a user area of an optical disc. In providing.

According to an aspect of the present invention, there is provided a method of recording and reproducing an optical recording medium, wherein an optical recording medium having a recordable data area formed by wobbling on a track with information capable of recognizing a reference frequency is provided. Detecting and storing the level of the wobble signal in the data area corresponding to the track amount as a reference level, detecting the level of the wobble signal in the data area during recording and playback, and the level and the level of the detected wobble signal. And comparing the stored reference levels to detect the detrack amount and performing the tracking servo in the direction of decreasing the detrack amount.
The method of recording and reproducing an optical recording medium according to the present invention, in an optical recording medium having a recordable data area formed by wobbling on a track information capable of recognizing a reference frequency, the wobble of the data area during data recording and reproduction Detecting a detrack by the amount of change of the signal, and performing a tracking servo that compensates for the detected detrack when the detrack is detected.
The detrack detection step includes detecting a level of a wobble signal in the absence of a detrack in advance and storing it as a reference level, detecting a level of a wobble signal in the data area during data recording and reproducing, and detecting the detected wobble. And detecting the detrack size from the difference signal between the level of the signal and the previously stored reference level, and detecting the direction of the detrack by the sign of the difference signal.
An apparatus for recording and reproducing an optical recording medium according to the present invention is capable of wobble of the data area during data recording and reproducing on an optical recording medium having a recordable data area formed by wobbling information on a track to recognize a reference frequency. After detecting the level of the signal and comparing with the stored reference level, the de-track detection unit for detecting the size and direction of the de-track, and the tracking drive signal is generated from the size and direction of the de-track detected by the de-track detection unit And a tracking servo for compensating for the detrack.
The detrack detection unit detects a level of the wobble signal when there is no detrack and stores the level as a reference level.
The wobble signal level of the detrack detector is a potential difference obtained by holding a peak and a bottom of the wobble signal.

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 utilizes a characteristic in which the voltage level (ie, peak to peak voltage, Vpp) of the wobble signal wobbled on the track of the user area of the optical disc varies with the degree of detrack. To detect and compensate for tracks.

FIG. 1 is a block diagram of an optical disc recording / reproducing apparatus for performing the detrack control method according to the present invention, and shows only a part related to tracking.

Referring to FIG. 1, an optical disk 101 capable of rewriting data, an optical pickup 102 for recording and reproducing information on the optical disk 101, and a high frequency RF from an electrical signal output from the optical pickup 102 (Or also referred to as lead channel 1). A high frequency (RF) and servo error generator 103 generating a signal and a servo error signal, and a read channel 2 output from the high frequency (RF) and servo error generator 103. A detrack detector 104 which detects a wobble signal from the signal and detects a detrack by a level change of the detected wobble signal, and a servo controller which converts the amount of detrack detected by the detrack detector 104 into a tracking drive signal ( 105, and a tracking driver 106 that controls the optical pickup 102 according to the tracking drive signal to compensate for the detrack.

Here, the optical pickup 102 is provided with a photo detector that detects the light amount of the beam and converts it into an electrical signal, the optical detector is an example of the signal track direction and radial of the optical disk 101 as shown in FIG. Four photodetectors (PDA, PDB, PDC, PDD) that are specifically divided in the direction, i.e., divided into four directions.

In the present invention configured as described above, the optical disc 101 has a signal track structure of lands and grooves, and data can be recorded or reproduced not only on the tracks of the lands or grooves, but also on the tracks of the lands and grooves. have.

Thus, the laser light emitted by the laser diode of the optical pickup 102 during mounting or recording / reproducing of the optical disk 101 is placed on the signal track of the rotating optical disk 101, where the reflected light is directed to the optical detector. Incident.

The photo detector includes a plurality of photo detection elements, and an electrical signal proportional to the amount of light obtained from each photo detection element is output to the radio frequency (RF) and servo error generator 103.

If the photodetector is configured as shown in FIG. 2, the photodetector outputs electrical signals a, b, c, and d in proportion to the amount of light obtained from the respective photodetector elements PDA, PDB, PDC, and PDD. Output to the generation unit 103.

The high frequency RF and the servo error generator 103 combine the electrical signals a, b, c, and d to generate a high frequency RF signal for data reproduction, a read channel 2 signal for servo control, a focus error signal, and the like. Create The RF signal may be obtained by (a + b + c + d) an electrical signal output from the photo detector, and the read channel 2 signal may be an electrical signal output from the photo detector (a +). d)-(b + c), and a tracking error (TE) signal can be obtained by processing the read channel 2 signal.

If the photo detector is divided into two in the track direction, a high frequency (RF) signal (= I1 + I2) and a read channel 2 signal (= I1-I2) are detected from the light amount balance of both photodiodes I1 and I2. do. That is, a + d in FIG. 2 corresponds to I1 and b + c corresponds to I2.

At this time, the wobble signal recorded on each track is detected only in the read channel 2 signal.

Accordingly, the read channel 2 signal among the servo error signals detected by the high frequency RF and the servo error generator 103 is output to the detrack detector 104.

The detrack detector 104 detects a wobble signal from the read channel 2 signal and detects a level of the wobble signal. In this case, the level Vpp of the wobble signal may be obtained by holding the peak and the bottom of the wobble signal, respectively.

In this case, Table 1 below is output in a state in which the servo error signal is well-adjusted by adjusting the defocus and detrack in the tilt zero (ie, mechanism 0) state, and the tilt and defocus offset are fixed in the fixed state. A wobble signal level change is shown due to a track offset change.

   Detrack []   Wobble [Vpp]      0.00     0.043      1.00     0.041      2.00     0.041      3.00     0.041      4.00     0.039      4.97     0.039      6.00     0.034      7.00     0.034      8.00     0.032      9.00     0.037     10.00     0.027

3 is a graph of Table 1, and the level value of the wobble signal varies according to the detrack offset value.

Accordingly, the present invention compares the level Vpp of the wobble signal just detected with the level Vpp of the wobble signal currently detected, and knows the relative detrack amount based on the difference.

4A to 4C illustrate examples, and it can be seen that the level Vpp of the wobble signal varies according to the detrack offset. Therefore, it can be seen how far from the track center the present is than before. Here, we can see how far it is from the track center relative to the relative amount, that is, it is not known whether it is inward or outward relative to the track center.

Therefore, in the present invention, if the level of the wobble signal when there is no detrack in advance is stored as a reference level, the amount and magnitude of the detrack is determined by comparing the level of the wobble signal detected during recording and reproducing with the previously stored reference level. It can be seen.

If the difference between the predetermined reference level and the level of the wobble signal currently detected is α, the magnitude of the detrack can be known by the α value, and the direction of the detrack can be known by the symbol α. Therefore, if the sign of α is-, the detrack may be compensated by α in the + direction, and if the sign of α is +, the detrack may be compensated by α in the-direction. That is, what is necessary is just to compensate in the direction which reduces a detrack amount.

Accordingly, the servo controller 105 converts the size and direction of the detrack obtained by the above-described method into a tracking drive signal and outputs the tracking drive signal to the tracking driver 106.

The tracking driver 106 drives the tracking actuator of the optical pickup 102 and the disc 101 by driving the tracking actuator in the optical pickup 102 in accordance with the tracking drive signal, i.e., in the + or-direction by the size of the detrack. Control it to match.

As described above, since the wobble signal of the present invention is recorded anywhere in the user area, the wobble signal can be detected in real time. If the reference level is set in advance, the time for determining and compensating for the presence or absence of the de-track during actual data recording and playback can be shortened. By doing so, the tracking servo can be stabilized quickly.

As described above, according to the method and apparatus for recording and reproducing an optical recording medium according to the present invention, by detecting a level of a wobble signal during actual data recording and reproducing, and detecting and compensating a detrack from a change in the voltage level of the wobble signal, It prevents the deterioration of data due to detrack during recording and playback, and stabilizes the tracking servo quickly to enable real-time recording, while at the same time operating the system stably.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (13)

A method of recording and reproducing an optical recording medium having a recordable data area formed by wobbling information on a track to recognize a reference frequency, the method comprising: Detecting the level of the wobble signal when there is no detrack and storing it as a reference level in advance; Detecting the level of the wobble signal in the data area during actual data recording and reproducing; Comparing the level of the detected wobble signal with a previously stored reference level to determine a detrack and outputting a result value; And performing a tracking servo that compensates for the detrack from the resultant value. The method of claim 1, And the wobble signal of the step is detected from a read channel 2 signal which is a difference of an electrical signal proportional to the amount of reflected light detected on the basis of the track direction of the optical record carrier. The method of claim 1, wherein the wobble signal level of the step is And a potential difference obtained by holding a peak and a bottom of the wobble signal. The method of claim 1, wherein the detrack detection step is And detecting and outputting a detrack size as a difference signal between a previously stored reference level and a level of a wobble signal detected during recording and reproduction. The method of claim 1, wherein the detrack detection step is And detecting and outputting a detrack direction using a sign of a difference signal between a previously stored reference level and a level of a wobble signal detected during recording and reproduction. The method of claim 1, wherein said tracking servo step is And tracking tracking by generating a tracking drive signal in the size and direction of the detrack detected in the step. A method of recording and reproducing an optical recording medium having a recordable data area formed by wobbling information on a track to recognize a reference frequency, the method comprising: Detecting the detrack by comparing the level of the wobble signal in the data area with a reference level during data recording and reproducing; And performing a tracking servo for compensating for the detected detrack if the detrack is detected in the step. 8. The method of claim 7, wherein the detrack detection step is Detecting the level of the wobble signal when there is no detrack and storing it as a reference level in advance; Detecting the level of the wobble signal in the data area during data recording and reproducing; Detecting a detrack size from a difference signal between the detected level of the wobble signal and a pre-stored reference level, and detecting the direction of the detrack by the sign of the difference signal. Record playback method. 9. The method of claim 8, wherein said tracking servo step is And a tracking drive signal is generated in the magnitude and direction of the detrack detected in the step to compensate for the detrack. An apparatus for recording and reproducing an optical recording medium having a recordable data area formed by wobbling information on a track capable of recognizing a reference frequency. A de-track detector for detecting the level and direction of the de-track by detecting the level of the wobble signal in the data area and comparing the pre-stored reference level during data recording and reproducing; And a tracking servo that generates a tracking drive signal from the size and direction of the detrack detected by the detrack detection unit, and compensates for the detrack. The method of claim 10, wherein the detrack detection unit An apparatus for recording and reproducing an optical recording medium, wherein the level of the wobble signal when there is no detrack is detected in advance and stored as a reference level. The method of claim 10, And the wobble signal of the detrack detection unit is detected from a read channel 2 signal which is a difference of an electrical signal proportional to the amount of reflected light detected based on the track direction of the optical record carrier. 11. The method of claim 10, wherein the wobble signal level of the detrack detection unit is And a potential difference obtained by holding a peak and a bottom of the wobble signal.

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