KR20000074746A - Method for recording/playing of optical recording medium - Google Patents

Abstract

PURPOSE: A recording and reproducing method of an optical recording medium is to detect and compensate a detrack by a variation amount of a tracking error signal detected from a crossed head region. CONSTITUTION: The recording and reproducing method of an optical recording medium in which a plurality of non-record regions having a different phase are arranged between writable data regions to classify the data region comprises the steps of: judging whether or not tracking error signals detected from sections having a different phase within the non-record regions have a symmetrical relation on the basis of a reference level; judging by a track sector when them have the symmetrical relation and a detrack when them have an asymmetrical relation, and then outputting the resultant value; and performing a tracking servo from the resultant value. The third step comprises performing the tracking servo so that the tracking error signals having the different phase have the symmetrical relation on the basis of the reference level.

Description

Method of recording and reproducing an optical recording medium {Method for recording / playing of optical recording medium}

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

Optical recording media that can be freely repeatedly rewritable, such as optical discs, include a rewritable compact disc (CD-RW) and a rewritable digital versatile disc (DVD-RW, DVD-RAM, DVD +). RW).

The above-described rewritable optical disc, especially DVD-RAM, 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, information signals are recorded in tracks of lands and grooves, respectively. To this end, 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.

Further, in such a high density optical disc, the distance between signal tracks, that is, the signal track pitch, is reduced in order 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 as shown in FIG. 1, or may be recorded in a wobbling shape along the track. 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.

The header area preformatted at the start of each sector is further composed of four header fields (header 1 field and header 4 field). At this time, the four header fields are arranged staggered from the track center, Figure 1 is an example, the structure of the header field for the first sector in one track. 1, it can be seen that the track boundary of the user area in which actual data is recorded is wobbled.

In such an optical recording / reproducing apparatus, in order to record information or to reproduce the recorded information, tracking control is performed through 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 an optical disc capable of recording and reproducing data in both land and groove, such as a DVD-RAM, the track pitch is narrow for high density, and such detracking has a great effect on the next track.

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 recording and reproducing method of an optical recording medium which detects and compensates for a detrack by a change amount of a tracking error signal detected in a staggered header area. Is in.

1 shows the arrangement of a header preformatted at the start of each sector in a typical rewritable disc.

2 is a block diagram of an optical disk recording / reproducing apparatus for detrack control according to the present invention;

3 is a diagram illustrating an example of a light detector of the optical pickup of FIG. 2;

FIG. 4 is a graph illustrating examples of tracking error signals detected in headers 1 and 2 and headers 3 and 4 by detrack offset changes. FIG.

5A to 5C show changes in the level of the tracking error signal detected in the headers 1 and 3 and the headers 3 and 4 by the detrack offset change.

Explanation of symbols for main parts of the drawings

201: optical disc 202: optical pickup

203: RF and servo error generation unit 204: Detrack detection unit

205: servo control unit 206: tracking drive unit

In the recording and reproducing method of the optical recording medium according to the present invention for achieving the above object, a plurality of header areas of different phases are arranged as non-recording areas to distinguish the shape of the data area between recordable data areas. Determining whether tracking error signals detected from respective phases having different phases in the non-recorded area in the optical recording medium have a symmetrical relationship with respect to a reference level; If it is an asymmetric relationship, it is determined that it is a detrack and outputs the result value, and performing tracking servo from the result value.

The reference level of the step is characterized in that the tracking error signal detected in the data area.

The reference level of the step is characterized in that the center level of the tracking error signal.

In the tracking servo step, the tracking servo is performed such that two tracking error signals having different phases have a symmetrical relationship with respect to a reference level.

The recording and reproducing method of an optical recording medium according to the present invention is detected in the non-recording area in an optical recording medium in which a plurality of non-recording areas of different phases are arranged between the recordable data areas to distinguish the shape of the data area. Obtaining a difference between a tracking error signal and a reference level and outputting the difference as a first difference signal, and obtaining a difference between the tracking error signal detected in a non-recorded area having a phase different from that of the non-recorded area and the reference level. Outputting as a primary signal, obtaining a second difference signal between each of the first difference signals of the above steps, determining that the track center is equal to or less than a predetermined reference value, and detracking if the second difference signal is equal to or less than a predetermined reference value. And outputting the result value, and performing a tracking servo from the result value. And a gong.

The reference level of the step is characterized in that the center level of the tracking error signal detected in the data area.

The tracking servo performing step may detect the detrack size from the result of the second difference signal.

In the performing of the tracking servo, the detrack direction is detected from the sign of the second difference signal.

The tracking servo performing step may compensate for the detrack in a direction in which the magnitudes of the first difference signals obtained in the above steps are the same.

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 is to detect and compensate for the detrack by symmetry of the level difference between the reference error level and the tracking error signal detected in each header area having different phases in the system in which the header areas are staggered from the track center.

Fig. 2 is a block diagram showing the construction of an optical disc recording / reproducing apparatus for performing the detrack control method according to the present invention.

2, an optical disc 201 capable of rewriting data, an optical pick-up 202 for recording and reproducing information on the optical disc 201, and an RF (or an RF signal from an electrical signal output from the optical pick-up 202). Also referred to as lead channel 1.) Detecting the magnitude and direction of the detrack from the RF and servo error generator 203 generating the signal and the servo error signal, and the tracking error signal output from the RF and servo error generator 203. The detrack detection unit 204, the servo control unit 205 which generates a tracking drive signal from the magnitude and direction of the detrack detected by the detrack detection unit 204, and the optical pickup 202 according to the tracking drive signal. It is composed of a tracking drive unit 206 to control and compensate the detrack.

Here, the optical pickup 202 is provided with a photo detector for detecting the light amount of the beam and converting it into an electrical signal, the optical detector is an example of the signal track direction and the radial direction of the optical disk 201 as shown in FIG. In this case, it is possible to configure four specific photodetectors (PDA, PDB, PDC, PDD).

In the present invention configured as described above, the optical disc 201 has a signal track having a 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. At the start of each sector, the header 1, 2 fields and the header 3, 4 fields are alternately arranged in a preformat. That is, the phases of the header 1,2 fields are inversely opposite to the header 3,4 fields.

Thus, the laser light emitted by the laser diode of the optical pickup 202 during mounting or recording / reproducing of the optical disk 201 is placed on the signal track of the rotating optical disk 201, where the reflected light is directed to the optical detector. Incident.

The photo detector includes a plurality of photo detectors, and an electrical signal proportional to the amount of light obtained from each photo detector is output to the RF and servo error generator 203.

If the photodetector is configured as shown in FIG. 3, the photodetector outputs electrical signals a, b, c, and d that are proportional to the amount of light obtained from each of the photodetector elements PDA, PDB, PDC, and PDD. 203).

The RF and servo error generator 203 combines the electrical signals a, b, c, and d to generate an RF signal for data reproduction, a read channel 2 signal for servo control, a focus error signal, and the like. The RF signal may be obtained by (a + b + c + d) the electrical signal output from the photo detector, and the read channel 2 signal may be the (a + d) − electrical signal output from the photo detector. (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, the RF signal (= I1 + I2) and the read channel 2 signal (= I1-I2) are detected from the light amount balance of both photodiodes I1 and I2. That is, a + d in FIG. 3 corresponds to I1 and b + c corresponds to I2.

Therefore, the present invention detects the detrack by using the difference between the reference error level and the level of the tracking error signal detected in the headers 1 and 2 and the headers 3 and 4, which are alternately arranged. Here, the reference level may use the center level of the tracking error signal detected in the user area.

To this end, the TE signal among the servo error signals detected by the RF and servo error generator 203 is output to the detrack detector 204.

The detrack detection unit 204 samples the tracking error signals output from the header 1 and 2 areas and the header 3 and 4 areas, respectively, and detects a difference between the reference levels.

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. It shows the level change of the tracking error signal due to the track offset change.

Detrack [] Header 1,2 [V] Header 3, 4 [V] 0.00 4.90 0.50 1.00 4.30 1.30 2.00 4.10 1.50 3.00 3.70 2.10 4.00 3.20 2.50 4.97 2.50 3.10 6.00 1.70 4.00 7.00 0.80 4.30 8.00 0.20 4.80 9.00 0.00 4.90 10.00 -1.10 5.50

4 is a graph of Table 1, wherein the potential difference between the tracking error signal detected in the header 1 and 2 areas and the reference level and the potential difference between the tracking error signal detected in the header 3 and 4 areas and the reference level are symmetrical. This is when there is no detrack.

That is, the tracking error signal is greatly changed up and down to follow it in the header section. When the tracking error signal is not detracked based on the tracking error signal in the user area where actual data is recorded, that is, the track center. The two potential differences are almost the same when passing through the headers 1,2 and 3,4, whereas in the case of detracking, the magnitudes of the two potential differences are different when passing through the headers 1,2 and 3,4.

Therefore, the potential difference between the TE signal detected in the header 1 and 2 areas and the reference level (potential of the tracking error signal detected in the header 1 and 2 areas-the potential of the reference level = Vp1) and the TE detected in the header 3 and 4 areas. Comparing the potential difference between the signal and the reference level (potential of the tracking error signal detected in the headers 3 and 4 region-potential of the reference level = Vp2) shows whether there is a detrack or not.

5A to 5C illustrate examples, in which the tilt is a tracking error signal detected while only changing the detrack offset while the tracking is on and the focus is on. 5A to 5C, the signal shown on the left is a tracking error signal V _HD12 detected in the header 1 and 2 areas, and the signal displayed on the right is a tracking error signal V _HD34 detected in the header 3 and 4 areas. and, a voltage (V _TE) detected by the center level of the tracking error signal of the user area in this embodiment is the voltage at the reference level.

Here, when there is no detrack, the potential difference between the tracking error signal detected in the header 1 and 2 areas and the reference level (Vp1 = | V _HD12 -V _TE |) and the tracking error signal detected in the header 3 and 4 areas. And the potential difference between the reference level and Vp2 = | V _HD34 -V _TE | are almost the same as in FIG. 5B. That is, the potential difference between the tracking error signal detected in the header 1 and 2 areas and the reference level (Vp1 = | V _HD12 -V _TE |) and the potential difference between the tracking error signal detected in the header 3 and 4 areas and the reference level. (Vp2 = | V _HD34 -V _TE |) is symmetrical.

This is expressed by the following equation (1).

｜ V _HD34 -V _TE ｜

5A and 5C, the potential difference Vp1 between the tracking error signal detected in the header 1 and 2 areas and the reference level and the potential difference Vp2 between the tracking error signal detected in the header 3 and 4 areas and the reference level as shown in FIGS. 5A and 5C. If is different, that is, asymmetric means that the detrack has occurred. At this time, the larger the detrack, the greater the degree of asymmetry.

This is expressed by the following equation (2).

V _HD12 -V _TE | ≠ | V _HD34 -V _TE |

Accordingly, the present invention provides a potential difference between the tracking error signal detected in the header 1 and 2 areas and the reference level (Vp1 = | V _HD12 -V _TE |) and the tracking error signal detected in the header 3 and 4 areas and the reference level. If the potential difference (Vp2 = | V _HD34 -V _TE |) is different, that is, when the difference value (= Vp1-Vp2) of the two potential differences exceeds the predetermined reference value (V _Th1 ) as shown in Equation 3 below, it is determined that a detrack has occurred. If it does not exceed a certain reference value V _Th1 , the optical focus is determined to be on-track, which is well-suited to the track center.

Vp1-Vp2 ≤ V _Th1

Thus, the potential difference Vp1 between the tracking error signal detected in the header 1 and 2 areas and the reference level and the potential difference Vp2 between the tracking error signal detected in the header 3 and 4 areas and the reference level are obtained, respectively. Comparing the size reveals the size and direction of the detrack.

If the value of Vp1-Vp2 is alpha, the magnitude of the detrack can be determined by the alpha value, and the direction of the detrack can be known by the sign of alpha. In other words, it can be seen which way the track center deviates from when the disc is in a normal state.

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. In other words, the detrack may be compensated in such a manner that the value of the two potential differences Vp1 and Vp2 are the same, for example, α is zero.

Here, since the values of the tracking error signals detected in the headers 1 and 2 and the headers 3 and 4 are different for each disk, the ratio of the two signals is normalized and applied as in Equation 4 below.

That is, if the equation (4) is satisfied, it is determined that there is no detrack. If the equation (4) is not satisfied, it is determined that a detrack has occurred, and the amount of detrack is detected by the magnitude of Vp1-Vp2, and the sign Detects the direction of the detrack.

Accordingly, the detrack detection unit 204 calculates α in the above-described process, outputs the detrack error signal corresponding to α to the servo control unit 205 using the detrack error signal, and outputs the detrack error signal to the servo control unit 205. The signal 205 converts the detrack error signal into a tracking drive signal by outputting the detrack error signal to the tracking driver 206. That is, the potential difference between the tracking error signal detected in the header 1 and 2 areas and the reference level (Vp1 = | V _HD12 -V _TE |) and the potential difference between the tracking error signal detected in the header 3 and 4 areas and the reference level. The tracking drive signal is generated and outputted to the tracking driver 206 such that (Vp2 = | V _HD34 -V _TE |) is symmetrical.

The tracking driver 206 drives the tracking actuator of the optical pickup 202 and the disk 201 by driving the tracking actuator in the optical pickup 202 according to the tracking drive signal, that is, in the + or-direction by the size of the detrack. Control it to match.

In this case, the present invention shortens the time for determining and compensating for the presence or absence of a de-track during actual data recording and reproduction by setting the threshold values in advance, thereby enabling real time recording with fast stabilization of the tracking servo.

As described above, according to the recording / reproducing method of the optical recording medium according to the present invention, since the level of the tracking error signal detected in the header area staggered from the track center varies depending on the detrack offset, By detecting and compensating for the detrack by the level change of the tracking error signal during actual data recording / reproducing, it prevents the deterioration of the data due to the detrack during recording and playback, and stabilizes the tracking servo quickly to enable real time recording. At the same time, there is an effect of 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 (9)

A method of detecting and recording a tracking error signal in an optical recording medium in which a plurality of non-recording areas having different phases are arranged between the recordable data areas to distinguish shapes of the data area. Determining whether each of the tracking error signals detected from the sections having different phases in the non-recorded region has a symmetrical relationship with respect to a reference level; Determining a track center if the relationship is symmetrical and de-tracking if the relationship is asymmetric, and outputting the result value; And performing a tracking servo from the resultant value. The method of claim 1, wherein the reference level of the step is And a tracking error signal detected in said data area. The method of claim 2 wherein the reference level of the step And a center level of the tracking error signal. The method of claim 1, wherein said tracking servo step is And a tracking servo such that the two tracking error signals having different phases have a symmetrical relationship with respect to a reference level. A method of detecting and recording a tracking error signal in an optical recording medium in which a plurality of non-recording areas having different phases are arranged between the recordable data areas to distinguish shapes of the data area. Obtaining a difference between a tracking error signal detected in the non-recorded area and a reference level and outputting the difference as a first difference signal; Obtaining a difference between the tracking error signal detected in the non-recorded region having a phase different from the non-recorded region and the reference level and outputting the difference as the first difference signal; Obtaining a second difference signal between each first difference signal of said steps; Determining the track center when the second difference signal is equal to or less than a predetermined reference value, and determining the track to output a result value when the second difference signal is equal to or greater than a predetermined reference value; And performing a tracking servo from the resultant value. The method of claim 5, wherein the reference level of the step And a center level of a tracking error signal detected in said data area. The method of claim 5, wherein performing the tracking servo is performed. And detecting the detrack size from the result of the second difference signal. The method of claim 5, wherein performing the tracking servo is performed. And detecting the detrack direction from the sign of the second difference signal. The method of claim 5, wherein performing the tracking servo is performed. And compensating for the detrack in the direction in which the magnitudes of the first difference signals obtained in the above steps become equal.