KR100363155B1 - Device for controlling track search by using header signal in land / groove optical disc - Google Patents

Abstract

The present invention relates to an apparatus for controlling track search using a header signal in a land / groove optical disc.

An apparatus for tracking an optical disk recordable in a land / groove structure, comprising: a header section detection section for detecting a header section in which a header signal is recorded from a push-pull signal detected by the optical disk; A polarity valid period detection unit for detecting a header polarity valid period including a header signal within a predetermined range of the magnitude of the push-pull signal detected by the optical disk; A header direction detection unit for detecting whether a current header detection order is a land or a groove from a push-pull signal detected by the optical disc and where the period of increase or decrease of the push-pull signal curve is located; An entry time determination unit for determining a track entry time by comparing the polarity of the header signal of the search start point with the polarity of the header signal of the search destination point from the values detected by the header section detection unit, the polarity valid period detection unit, and the header direction detection unit; And a polarity switching unit for switching the polarity of the track error signal detected by the optical disc at the entry time determined by the entry time determination unit.

According to the present invention, reliability can be greatly improved when a predetermined sector is accessed in an optical disc of a land / groove recording structure.

Description

Device for controlling track search by using header signal in land / groove optical disc

The present invention relates to a land / groove optical disc, and more particularly, to an apparatus for controlling track navigation using a header signal in a land / groove optical disc.

In general, in order to reproduce signals from predetermined sectors and record / reproduce data in predetermined sectors in the optical disk drive, it is necessary to stably and quickly access the predetermined sectors to be recorded / reproduced.

Briefly describing the access operation of the optical disk, the light emitted from the laser diode is incident on the objective lens through the beam shaper. The light passing through the objective lens is focused on the disk so that the information can be recorded on or read from the disk. In order to read or record the information recorded in this process, the optical spot is rapidly moved from the current location to the desired address and the recording or reproducing operation is performed. There is the same.

U.S. Patent No. 5361245 discloses a technique for determining the direction and track entry time of the inner and outer circumferences by using the phase difference between the track cross signal generated while the track is transversely and the sum signal of the light receiver. . Another U.S. Patent No. 5497360 discloses a method of searching for a track of a target sector while performing speed control in accessing the target sector. Here, the direction of acceleration / deceleration is also used by using a track cross signal and a SUM signal in performing speed control. I'm in control.

Looking at the track search operation of these conventional devices, the polarity of the track error signal is reversed due to the spindle motor eccentricity of the disk or the drive. It is important to determine the track entry time for stable track insertion. In a disc for exclusive use in reproduction such as a CD-ROM or a DVD-ROM or a disc for recording and reproducing on one side of a land or groove, the amplitude of the information reproduction signal is maximum as shown in FIG. If the track induction signal is made at the place where the track induction operation is performed and the track induction operation is performed only in the track induction possible region, stable track induction is possible regardless of the polarity inversion of the track error signal due to the disc eccentricity. In FIG. 1, the TES signal represents a track error signal and the RFRP represents a reproduction signal of a pit. Hereinafter, the same applies to FIG. 2.

However, in a disc using both lands and grooves, such as a DVD-RAM, there may be a reproduction signal or unrecorded area in which both lands and grooves are not recorded. At this time, since the track can be input to any land or groove as shown in FIG. 2, the play signal of the pit cannot be used as the track input time determination signal. Therefore, the control of the negative feedback at the track entry point is not controlled, and thus, the sliding of the actuator or the failure of the entry may occur during the entry. In other words, if the polarity of the starting point and the incoming polarity are the same when moving to the destination address, no problem may occur during speed control and track entry, but the optical spot on the disc moves due to the disc eccentricity and the relative direction is reversed. In this case, if there is no device capable of detecting the direction, it is impossible to carry out stable drawing.

Therefore, there has been a demand for an apparatus capable of determining the track servo entry point regardless of the movement state of the spot determined by the disc eccentricity.

An object of the present invention, in order to solve the above problems, the header signal in the land / groove optical disk for controlling the track search operation based on the header signal included in the push-pull track error signal in the land / groove optical disk It is to provide an apparatus for controlling the track search by using.

FIG. 1 is a diagram showing an example of a signal used for determining a track insertion time of a conventional playback-only disc.

2 is a diagram showing an example of a reproduction signal of a pit in a land / groove optical disk.

3A shows the structure of a land / groove optical disc.

FIG. 3B is a diagram showing a track error signal detected from the optical disc shown in FIG. 3A.

4 is a diagram illustrating a push-pull track error signal and a header signal.

5A is a diagram illustrating polarities of a push pull error signal and a header signal when the spot scans from the inner circumference to the outside.

5B is a diagram illustrating polarities of the push pull error signal and the header signal when the spot is scanned from the outer circumference to the inner circumference.

6 is a block diagram of an apparatus for controlling track search using a header signal in a land / groove optical disc according to the present invention.

FIG. 7 is a diagram illustrating a polarity valid section of the push pull track error signal illustrated in FIG. 4.

8A illustrates a structure of a land / groove optical disc according to another embodiment of the present invention.

FIG. 8B is a diagram showing a track error signal detected from the optical disc shown in FIG. 8A.

In order to achieve the above object, a tracking control apparatus of an optical disc recordable in a land / groove structure, comprising: a header section detection unit for detecting a header section in which a header signal is recorded from a push-pull signal detected by the optical disk; A polarity valid period detection unit for detecting a header polarity valid period including a header signal within a predetermined range of the magnitude of the push-pull signal detected by the optical disk; A header direction detection unit for detecting whether a current header detection order is a land or a groove from a push-pull signal detected by the optical disc and where the period of increase or decrease of the push-pull signal curve is located; An entry time determination unit for determining a track entry time by comparing the polarity of the header signal of the search start point with the polarity of the header signal of the search destination point from the values detected by the header section detection unit, the polarity valid period detection unit, and the header direction detection unit; And a polarity switching unit for switching the polarity of the track error signal detected by the optical disc at the entry time determined by the entry time determination unit. An apparatus is provided.

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

6 is a block diagram of an apparatus for controlling track search using a header signal in a land / groove optical disc according to the present invention.

The apparatus shown in FIG. 6 includes an optical disk 602, a spindle motor 604, an objective lens 606, a laser diode 608, a photo diode 610, a push pull signal detector 612, and a header section detector. 614, a polarity valid section detector 616, a header direction detector 618, a low pass filter 620, an entry point determiner 622, and a polarity switch 624.

The optical disc 602 is a land / groove optical disc and includes a header area and a user area. 3A is a diagram showing the structure of a DVD-RAM disc which uses both lands and grooves and has a sector structure composed of a user area and a header area. In the user area, data is recorded or reproduced through the crystallization of the recording film and the phase change of the amorphous state, and the header area is formed of pits having a staggered structure at the center of the land or groove, and contains the address information of the sector and the like.

3A shows that the disc eccentricity occurs when the spot moves. FIG. 3B shows the track error signal and the header signal (both in the land) on which the first header signal is generated at the position where the track error signal slope is increasing, and the later header signal is the track error signal slope. Shows what happened at the decreasing position.

The light beam projected from the laser diode 608 is incident on the optical disk 602 through the objective lens 606. The incident beam is reflected by the optical disk 602 and detected as an electrical signal through the photo diode 610.

The push pull signal detector 612 detects the push pull track error signal (hereinafter, simply referred to as a push pull signal) as shown in FIG. 4 by comparing the electric signal with a predetermined reference signal. The header signal 40 is loaded on the push-pull signal shown in FIG. 4. As can be seen by reference numeral 40, the header signal goes from high to low in the groove and from low to high in the land (see FIGS. 5A and 5B).

The polarity of the push pull signal and the polarity of the header signal will be described in more detail with reference to FIGS. 5A and 5B. FIG. 5A shows the polarity of the push-pull error signal and the header signal when the spot scans from the inner circumference to the outer circumference, and FIG. 5B shows the spot when the spot scans from the outer circumference to the inner circumference. 5A and 5B, each of the above drawings shows an enlarged view of a portion (marked with an ellipse) of the following drawings.

Reference numeral 50 denotes a header signal detected when the push-pull signal changes from the falling edge to the rising edge direction. On the other hand, reference numeral 52 denotes a header signal detected when the push-pull signal changes from the rising edge to the falling edge direction. For example, the polarity (phase) of the header signals 50 and 52 are the same with respect to the land, but the polarity (phase) of the push-pull signal is reversed in FIGS. 5A and 5B. That is, it can be seen that disc eccentricity has occurred during track movement, and the polarity of the track error signal must be switched for accurate track search. As described above, when the polarity of the header signal carried on the push-pull signal is detected, it can be seen that it is possible to determine the track servo entry time regardless of the spot movement state determined by the disc eccentricity.

On the other hand, in such a land / groove type DVD-RAM disc, the polarity of the header signal carried on the track error signal can be used instead of the mirror signal of a general disc.

Returning to the apparatus of FIG. 6 again, the header section detection unit 614 detects the header section in which the header signal is recorded from the push-pull signal detected by the push-pull signal detector 612. The header signal is indicated by 40 at FIG. The header section detector 614 finds a point at which the header signal is recorded, which can be easily detected by differentiating the push-pull signal of FIG. 4 using, for example, a differential circuit.

The polarity valid section detection unit 616 detects the polarity valid section, which is a vertical valid section in which the direction of the header signal is known, from the push pull signal detected by the push pull signal detector 612. This will be explained with reference to FIG. 7. The header signal detected near the maximum or minimum value of the push-pull signal overlaps with the push-pull signal and it is not easy to determine the direction. Therefore, a certain range of values between the maximum value and the minimum value of the push-pull signal is calculated as a header polarity valid period, and the reference point is used to determine the entry point using the header signal included in the range. This polarity valid period can be appropriately determined between the maximum and minimum values of the push-pull signal according to the access speed or the degree of eccentricity. The polarity valid section detection unit 616 may be implemented using, for example, a limiter.

The header direction detector 618 detects the direction of the header signal from the push pull signal detected by the push pull signal detector 612. The direction detection of the header signal detects whether the header detection order is land or groove, and where the push-pull signal curve increases or decreases. Since the moving direction on the disc at the point of entry can be confirmed, stable track entry can be performed. The header direction detector 618 may be implemented using, for example, a comparator.

The entry point determination unit 622 determines the track entry time by combining the values detected by the header section detection unit 614, the polarity valid period detection unit 616, and the header direction detection unit 618. The track entry time will be described taking as an example the case where the header signal of the track search start point is detected as a land at the time when the push-pull signal curve increases. If the header signal of the track search destination point is detected as a land at the push-pull signal reduction point, the polarity of the header is inverted, so the track entry time is determined so that the track entry is performed in the groove. On the other hand, if the header signal of the track search destination point is detected as a land at the push-pull signal increase point, the polarity of the header is the same as the starting point and the destination point, so that the track entry time is determined to be performed in the land.

The LPF 620 low-pass filters the push-pull signal detected by the push-pull signal detector 612 and outputs a track error signal.

The polarity switching unit 624 switches the polarity of the track error signal at the entry point determined by the entry point determining unit 622 and outputs it to the tracking servo. The tracking loop then performs negative feedback control and stable track servo 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. In the above-described embodiment, a DVD-RAM disc using both lands and grooves and a header of which the shape of the header is staggered has been described. However, the same principle applies to a disc in which the shape of the header can be used in both land / groove as shown in FIGS. 8A and 8B. It is possible to perform a stable track insertion operation.

In addition, in the apparatus of the present invention, in order to increase the reliability of track entry time determination, a track servo may be inserted when the plurality of header signals have the same polarity at the time of entry point determination.

In addition, in the present invention, the track input is attempted using the header signal polarity, and the track input is measured during the track search using a conventional microcomputer (not shown), and the track input is attempted when the frequency of the track signal becomes less than a predetermined amount. You can also import a track servo in parallel.

According to the present invention, a track search operation is controlled based on a header signal included in a push-pull track error signal in a land / groove optical disc, thereby increasing reliability when accessing a predetermined sector in an optical disc having a land / groove recording structure. Can be improved. Further, even when the disc is large in eccentricity, it is possible to access the track at high speed and search for the track.

Claims (4)

A tracking control apparatus for an optical disc that can be recorded in a land / groove structure, A header section detection section for detecting a header section in which a header signal is recorded from the push-pull signal detected by the optical disk; A polarity valid period detection unit for detecting a header polarity valid period including a header signal within a predetermined range of the magnitude of the push-pull signal detected by the optical disk; A header direction detection unit for detecting whether a current header detection order is a land or a groove from a push-pull signal detected by the optical disc and where the period of increase or decrease of the push-pull signal curve is located; An entry time determination unit for determining a track entry time by comparing the polarity of the header signal of the search start point with the polarity of the header signal of the search destination point from the values detected by the header section detection unit, the polarity valid period detection unit, and the header direction detection unit; And And a polarity switching unit for switching the polarity of the track error signal detected by the optical disc at the entry time determined by the entry time determination unit. The apparatus for controlling track search using a header signal in a land / groove optical disc . The method of claim 1, wherein the polarity effective period determiner And detecting a predetermined value between the maximum value and the minimum value of the push-pull signal magnitude detected by the optical disc as a valid header polarity section. The method of claim 1, wherein the entry point determination unit An apparatus for controlling track search using a header signal in a land / groove optical disc, characterized in that the track entry point is determined when the polarities of a plurality of header signals continuously match. The method of claim 1, An apparatus for controlling track search by using a header signal in a land / groove optical disc, characterized in that the apparatus further comprises a microcomputer for determining track entry when the frequency of the track signal falls below a certain amount by measuring the track period during track search.