KR100698105B1 - Method and apparatus for judging land/groove track of optical recording medium - Google Patents

Abstract

The present invention relates to a land / groove track discrimination method and apparatus for an optical record carrier having a land and groove structure. The present invention relates to a method of detecting a phase of a wobble signal formed on each land / groove track, and then, By checking whether the phase relationship is in phase or reverse, and determining whether the track in which the light beam is currently located is a land track or a groove track, accurate L / G discrimination is possible without detecting the header area.

Land, groove, wobble

Description

FIELD AND APPARATUS FOR JUDGING LAND / groove track of optical recording medium

1 (a) is a general diagram showing an example of a wobble signal detected in a groove track

FIG. 1B is a general diagram showing an example of a wobble signal detected in a land track

2 is a block diagram illustrating land / groove track determination of an optical recording medium according to an embodiment of the present invention;

3A to 3E are operation waveform diagrams of each part of FIG. 2 for land / groove determination

4 is a block diagram illustrating land / groove track determination of an optical record carrier according to another exemplary embodiment of the present invention.

5A to 5D are operation waveform diagrams of each part of FIG. 4 for land / groove determination.

Explanation of symbols for main parts of the drawings

201: band pass filter 202,203: comparator

204: exclusive ora gate 205: PLL unit

206: D flip flop

The present invention relates to a rewritable optical record carrier system, and more particularly, to a method and apparatus for determining land and groove tracks in a wobble structure land / groove recording method.

Generally, 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).

의 깊이차를 갖는다.At this time, the above-described rewritable optical disc, particularly DVD-RAM, has a signal track having a structure of land and groove, so that data can be recorded not only on the track of the land or groove, but also on the track of the land and groove. Can play. Here, the land and groove tracks have different depths in the light incident direction. For example, a DVD-RAM

Has a difference in depth.

The tracks of the rewritable optical disc are divided into unit sections having a predetermined size (hereinafter referred to as sectors), and the plurality of sectors (for example, 16 sectors) constitute one block, and information is provided in block units. Recording / playback is performed. In this case, the sector consists of an identification information area (hereinafter referred to as a header area) located at the head and a user information area located in succession to the header area. The user information area is also called a 'recording area' and records information desired by a user. In the header area, control information for sector address, random access, rotation control, and the like are recorded by pre-formatting, thereby enabling tracking control even on a blank disc in which no information signal is recorded.

In this case, the control information 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.

1, it can be seen that the track boundary of the user information area disposed between the header areas is wobbled. That is, Fig. 1A shows an example of a wobble signal in a groove track, and Fig. 1B shows an example of a wobble signal in a land track. Here, the wobble signal is not recorded in the header area.

At this time, the header area is composed of a plurality of header fields (eg, header 1 field to header 4 field), and the plurality of header fields are alternately arranged from the track center.

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, in order to accurately access the optical disk in which the track is formed in the structure of land and groove as described above, the light beam must accurately follow the center of the land and groove track. It must be controlled.

That is, the tracking error signals in the lands are inverted relative to each other (i.e., reversed phase) as compared with the tracking error signals in the grooves. However, in order to track normally in both lands and grooves, the tracking error signal obtained in the lands and grooves must be in phase. In addition, there is a difference in the DC offset (that is, the signal generated by the L / G depth difference) that the land and the groove basically have due to the depth difference between the land and the groove.

Therefore, in the land track, the tracking servo should be performed with the tracking error signal offset and adjusted to the land, and in the groove track, the tracking servo should be performed with the tracking error signal offset and adjusted for the groove.

For this purpose, it is necessary to quickly and accurately determine whether the track on which the light beam is currently located is a land or a groove.

At this time, a conventional method of determining whether the land or the groove track is a header area is used. That is, since the tracking error signal in the header area appears in an inverted form when following the land track and following the groove track, this characteristic is used. However, this method must always correctly detect the header area, and if the header area is not properly detected, the land / groove track discrimination will also be inaccurate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for determining land / groove tracks of an optical recording medium for accurately determining land / groove tracks from a wobble signal in a land / groove recording method having a wobble structure.

According to an aspect of the present invention, there is provided a land / groove track determination method of an optical recording medium, the method comprising: detecting a phase by slicing a wobble signal formed in each of the land / groove tracks; And checking the phase inversion of the wobble signal from the reference signal to determine the type of the current track and outputting a land / groove determination signal as a result of the determination, wherein the reference signal is the wobble signal and the determination. It is characterized in that the signal generated by applying the PLL using the signal.

The determining may include exclusively arranging a wobble signal sliced to a center level and a land / groove discrimination signal fed back, generating a reference signal by applying a PLL to the exclusive oralized wobble signal, and generating the reference signal; And determining whether the current track is a land track or a groove track by checking whether a phase relationship with the sliced wobble signal is in phase or inverse.

An apparatus for determining land / groove tracks of an optical record carrier according to the present invention includes a first comparator for detecting a wobble signal formed at each land / groove track and slicing to a first slice level, and being fed back to an output of the first comparator. A reference signal generator that generates a reference signal by applying a PLL after exclusively ringing the land / groove discrimination signal, and checks the phase reversal of the sliced wobble signal from the reference signal to determine the type of the current track And a land / groove discrimination unit for outputting an in-land / groove discrimination 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.

Referring to FIG. 1, the wobble signal in the groove track starts with rising and ends with rising as shown in the original portion of FIG. 1 (a) when referring to the header area, and the wobble signal in the land track is shown in FIG. You can see that it starts with polling and ends with polling like the circle of).

The present invention is to determine the L / G track by using the phase of the wobble signal is different in the land track and groove track, that is, 180 degrees inversion relationship.

FIG. 2 is a block diagram illustrating land / groove track determination of an optical record carrier according to the present invention.

Referring to FIG. 2, a band pass filter (BPF) 201 for bandpass filtering an input read channel 2 signal to detect a wobble signal, and slices the detected wobble signal to a first slice level A. A first comparator 202, a second comparator 203 that slices the detected wobble signal to a second slice level B, and a land / groove discrimination signal fed back to the output of the first comparator 202 ( An exclusive oar gate 204 for exclusively ringing L / G SW), a PLL unit 205 for applying a phase locked loop (PLL) to the output of the exclusive oar gate 204, and the PLL wobble The D flip-flop 206 receives a signal as a data signal and receives the output of the second comparator 203 as a clock signal and outputs a land / groove discrimination signal L / G SW.

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

At this time, the optical pickup causes the light beam focused on the objective lens to be placed on the signal track of the optical disk, and further condenses the light reflected by the signal recording surface into the objective lens and then enters the optical detector. The read channel 2 signal, the focus error signal, and the RF signal may be generated from the electrical signals output in proportion to the amount of light from the plurality of photodetectors of the photo detector. Processing the lead channel 2 signal results in a tracking error signal.

The present invention detects a wobble signal using the read channel 2 signal. That is, when the read channel 2 signal is bandpass filtered by the BPF 201, a wobble signal as shown in FIG. 3A is detected. At this time, the first comparator 202 slices the wobble signal using the center level of the wobble signal as a slice level and outputs the wobble signal as shown in FIG. 3B, and the second comparator 203 outputs the center level of the wobble signal. The wobble signal is sliced using the lower level as the slice level and then output as shown in FIG.

The output of the first comparator 202 is input to the exclusive OR gate 204, and the exclusive OR gate 204 is fed back with the original wobble signal sliced to the center level and the land / groove determination signal L is fed back. / G SW) is output exclusively to the PLL unit 205.

The PLL unit 205 applies a PLL to the output of the exclusive OR gate 204 and outputs the D flip-flop 206 as shown in FIG.

The reason why the PLL is applied to the wobble signal is to prevent the phase from changing according to the land / groove track. That is, the PLL wobble signal is always a constant frequency in phase regardless of land / groove track or header area. At this time, although the wobble signal is not originally recorded in the header area, if it is held in the header area with a signal before the header area, the frequency becomes constant in phase even in the header area as shown in FIG.

In particular, since the wobble signal in the land and groove tracks is 180 degrees out of phase, the wobble signal may flicker at the instant of L / G switching, which can be prevented. Therefore, the wobble signal of the same phase is always input to the data terminal of the D flip-flop 206.

If the groove track is set low in the land / groove discrimination signal (L / G SW) and the land track is set high, the PLL wobble signal is always in phase with the original wobble signal in the groove track. It is out of phase with the original wobble signal on the track.

In addition, if the land track is set low and the groove track is set high in the land / groove discrimination signal (L / G SW), the original wobble signal and the PLL wobble signal in the land track It is in phase.

Accordingly, the present invention uses this property to determine whether the track on which the current light beam is located is a land track or a groove track.

In the present invention, it is assumed that the groove track is set as the low signal and the land track is set as the high signal in the land / groove discrimination signal (L / G SW).

At this time, the output of the second comparator 203 is input to the clock terminal of the D flip-flop 206.

The D flip-flop 206 outputs a low signal when the signal input to the data terminal at the rising edge of the clock signal is low, and a high signal when the signal is high through the Q output terminal. ) Is a land / groove discrimination signal (L / G SW). In this case, the rising edge of the clock signal is an embodiment, and the land / groove track may be determined based on not only the rising edge but also the falling edge or the state of the wobble signal PLLed in the high or low state.

In FIG. 3, it can be seen that the wobble signal PLL at the rising edge of the clock signal is low in the groove track, and the wobble signal PLL is high in the rising edge of the clock signal in the land track.

In this case, the present invention uses the D flip-flop as the L / G determination unit for the L / G determination, but any flip-flop that can perform the same role as the D flip-flop.

In addition, the present invention may perform L / G determination using the exclusive OR gate 405 as shown in FIG. 4 instead of the D flip-flop. That is, even when the WLL signal PLL as shown in FIG. 5 (c) and the original wobble signal sliced to the center level as shown in FIG. 5B are exclusively ORed, the land / groove discrimination signal as shown in FIG. (L / G SW) can be obtained. Also in this case, the exclusive oragate is one embodiment, and any combination of gates capable of performing the exclusive ora function may be used.

Here, the difference between using the D flop flop and the exclusive OR gate is that the former is more stable than the latter because the clock signal is generated and used for discrimination.

Therefore, the servo controller (not shown) is offset after the land / groove determination signal L / G SW indicates a land track, that is, when the land / groove determination signal L / G SW is high, A tracking drive signal is generated with an inverted tracking error signal to perform tracking servo, and when the groove track is indicated, that is, when the land / groove discrimination signal (L / G SW) is low, tracking is performed with a tracking error signal offset adjusted to the groove. The drive signal is generated to perform tracking servo.

Although the present invention has been exemplified when a groove track is converted from a groove track to a land track for convenience of explanation, the same applies to the reverse case.

As described above, according to the method and apparatus for determining the land / groove track of the optical recording medium according to the present invention, the current light beam is made by using a relationship in which the phase of the wobble signal in the land track and the phase of the wobble signal in the groove track are inversed to each other. By determining whether the track to be located is a land track or a groove track, accurate L / G discrimination can be performed without detecting the header area. Therefore, accurate tracking control can be performed on a rewritable optical disc having a track structure of land and groove, and recording / reproducing on the optical disc is also performed accurately.

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 (8)

A land / groove track discriminating method of an optical recording medium having a structure in which adjacent signal tracks have different depths in a light incident direction and having lands and groove tracks, Detecting a phase of a wobble signal formed in each of the land / groove tracks; And Checking the phase inversion of the wobble signal from a reference signal to determine the type of the current track and outputting a land / groove determination signal as a result of the determination; Wherein the reference signal is a signal generated by applying a PLL by using the wobble signal and the discrimination signal. The method of claim 1, wherein the phase detection step And slicing the wobble signal to a center level. The method of claim 2, wherein the determining step Generating a reference signal by applying a PLL to the wobble signal sliced to the center level and a signal exclusively divided by the determination signal; And Determining whether a current track is a land track or a groove track by checking whether a phase relationship between the reference signal and the sliced wobble signal is in phase or reverse phase; and determining a land / groove track of an optical recording medium. . A land / groove track discriminating apparatus of an optical record carrier having a structure in which adjacent signal tracks have different depths in the direction of light incidence and groove tracks, A first comparator for detecting a wobble signal formed in each of the land / groove tracks and then slicing to a first slice level; A reference signal generator generating a reference signal by applying a PLL using a land / groove discrimination signal fed back to the output of the first comparator; And And a land / groove discrimination unit for checking the phase inversion of the sliced wobble signal from the reference signal to determine the type of the current track and outputting a land / groove discrimination signal as a result of the determination. Land / groove track discrimination device. The method of claim 4, wherein And the first slice level is a center level of a wobble signal. The method of claim 4, wherein the land / groove determination unit A second comparator that slices a wobble signal formed in each of the land / groove tracks to a second slice level; The output of the second comparator is input to the clock terminal, the reference signal is input to the data terminal, and then the phase of the signal input to the data terminal is checked from the signal input to the clock terminal to output a land / groove discrimination signal. And a land / groove track discrimination apparatus for an optical record carrier. The method of claim 6, And the second slice level is lower than the center level.  The method of claim 4, wherein the land / groove determination unit And an exclusive oar gate configured to output a land / groove discrimination signal by exclusively ORing the reference signal and the sliced wobble signal.

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