KR100718428B1 - Method for controlling tilt servo of optical disk - Google Patents

Abstract

The present invention relates to a tilt servo control method of an optical disc. In particular, when an optical disc is loaded, when the ID of the optical disc is not the same as the previously stored ID, the tilt control information of a plurality of areas of the optical disc is obtained and stored, and the ID of the optical disc is stored. If the ID is stored and the optical disc is not a recordable blank disc, the tilt servo is controlled using the tilt control information corresponding to the area of the previously stored optical disc. If the ID of the optical disc is a pre-stored ID and the optical disc is a recordable blank disc, OPC is performed using the pre-stored tilt control information and the tilt control information having the minimum jitter value is set. Therefore, the present invention can omit the process of dividing the tilt area every time an optical disc is loaded and obtaining an optimal tilt control value for it, and performing the tilt servo using the jitter value, so the tilt servo using the push-pull signal The accuracy can be increased compared to the method.

Optical Disc ID, Tilt Servo Control, Memory, Jitter

Description

Tilt servo control method of optical disc {METHOD FOR CONTROLLING TILT SERVO OF OPTICAL DISK}

1 is a flowchart illustrating a tilt servo control method of an optical disk according to the prior art;

2 is a block diagram showing a system for performing tilt servo control of an optical disk according to the present invention;

3 is a flowchart illustrating a tilt servo control method for an optical disc according to the present invention.

<Description of the code | symbol about the principal part of drawing>

100: optical disk 102: optical pickup

104: light driver 106: encoder

108: RF and servo error generation unit 110: decoder

112: voltage level detection unit of the push-pull signal

114: servo control unit 116: focus servo drive unit

118: tracking servo drive 120: tilt drive

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo control method of an optical disc. In particular, a tilt servo of an optical disc capable of controlling the tilt servo by measuring jitter on the distortion between the recording surface of the disc and the optical pickup lens due to the bending of the optical disc. It relates to a control method.

In general, laser data is incident on the opposite side of the reflective surface having a pit when data is recorded and reproduced on a recordable optical recording medium, i.e., an optical disc. Therefore, in terms of laser incidence, the pit appears as a projection.

Such an optical disk may be warped during the injection and curing of the resin in the manufacturing process, and this may cause an eccentricity even when a central hole is drilled. Further, even if the track of the optical disc is accurately recorded in a spiral shape at a pitch of a predetermined standard, an eccentricity is generated because the center hole is varied. Therefore, since the optical disk rotates with eccentricity, it is difficult for the central axis of the motor and the center of these tracks to completely coincide.

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

On the other hand, when the beam deviates from the track, not only the eccentricity of the disc but also the case where the disc is inclined. This may occur due to mechanical problems such as an error in mounting the disk to the spindle motor. That is, the focusing and tracking do not exactly match vertically, but are distorted. The tilted state of the disc is called tilt.

This tilt reduces the radial tilt margin for jitter in optical discs such as DVDs, where the track pitch is narrowed due to the higher density of the disc. Will occur. In this case, data cannot be read correctly during reproduction of the optical disc, and since data cannot be recorded accurately on the track during recording, distortion occurs when the recorded data is reproduced.

However, the tilt servo control of the conventional optical disc is to control the tilt servo using jitter on the optical disc on which data is recorded, and to control the tilt servo with a push-pull signal of a wobble signal on a blank disc without data.

1 is a flowchart illustrating a tilt servo control method for an optical disc according to the prior art.

Referring to FIG. 1, the tilt servo control method for an optical disc according to the prior art proceeds as follows.

First, when an optical disc is loaded into a drive, the controller recognizes the optical disc and determines whether the optical disc is a recordable blank disc (S10).

As a result of the determination in S10, when the optical disc is not a recordable blank disc, the control unit equally divides the recording area of the optical disc into N areas and measures the jitter amount from the RF signal (reproduction signal) according to the tilt change in each area. (S12 to S14)

The control unit sets an optimal tilt offset value in which jitter of the RF signal is minimized in each region (S16).

The controller regroups the sections having similar tilt values to group N regions into M groups, and controls to perform an optimal tilt servo operation by using a tilt control value that is a tilt offset value of each of the M groups. (S18 to S20)

The control unit reads data from or writes data to the optical disk while performing the tilt servo operation with the tilt control value (S22).

On the other hand, as a result of determination in S10, when the optical disc is a recordable blank disc, the control unit equally divides the recording area of the optical disc into N areas, and push-pull signal (PP Amp) for detecting a tracking error caused by a tilt change in each area. (S24 to S26) That is, the tracking error signal TE is measured from the inner circumference of the optical disk to the outer circumference.

The control unit then sets an optimal tilt offset value that maximizes the push-pull signal in each of the equally divided optical disks (S28).

After setting the tilt offset value in step S28, the controller performs steps S18 to S22 to regroup the optical disc areas to group the N areas into M pieces, and uses the tilt control value, which is the tilt offset value of each of the M groups. Read data from or write data to the optical disc while performing the optimal tilt servo operation.

However, since the tilt servo control method according to the related art performs a process of dividing the tilt area every time an optical disc is loaded and obtaining an optimum tilt offset value for each time, the loading time of the optical disc becomes long and the load of the optical pickup unit is increased. There was a problem to increase. In addition, in case of a blank disc, the method of controlling the tilt servo using the maximum value of the push-pull signal using the wobble signal as the tilt offset has a 10% to 20% or more error in accuracy than the tilt servo method using the jitter value. There is this.

An object of the present invention is to solve the problems of the prior art as described above, and when the optical disc is loaded after storing the optimal tilt control information of the optical disc in the memory, the tilt servo is operated using the tilt control value stored in the memory. In the case of a blank optical disc, a tilt servo control method of an optical disc capable of performing a tilt servo with a tilt control value having a minimum jitter value by finding a jitter value using an OPC is provided.

In order to achieve the above object, the present invention provides a method of controlling a tilt servo of an optical disc, the method comprising: determining whether an ID of the optical disc is the same as a previously stored ID when the optical disc is loaded, and when the ID of the optical disc is not a previously stored ID. Obtaining and storing tilt control information of a plurality of areas of the optical disc, and using the tilt control information corresponding to the area of the previously stored optical disc when the ID of the optical disc is a previously stored ID and the optical disc is not a recordable blank disc. And performing the OPC using the pre-stored tilt control information when the ID of the optical disc is a pre-stored ID and the optical disc is recordable, and setting the tilt control information having the minimum jitter value.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

2 is a block diagram showing a system for performing tilt servo control of an optical disk according to the present invention.

As shown in FIG. 2, a system for performing tilt servo control of an optical disk according to the present invention includes an optical pickup unit 102, an optical driver 104, an encoder 106, an RF and a servo error generator 108. , The decoder 110, the voltage level detection unit 112 of the push-pull signal 112, the servo controller 114, the focus servo driver 116, the tracking servo driver 118, the tilt driver 120, the controller 122, and the memory ( 124) and the like.

The optical pickup unit 102 records and reproduces information on the optical disc 100 so that the beam generated by the laser diode LD under the control of the servo controller 114 is placed on the track of the optical disc 100 through the objective lens. In addition, the beam reflected from the recording surface of the optical disc 100 is focused again by the objective lens and then incident on the photodiode PD to detect the focus error signal FE and the tracking error signal TE. An electrical signal proportional to the amount of light obtained from the photodiode PD is output to the RF and servo error generator 108.

The optical driver 104 converts the recording pulse of the encoder 106 into the recording voltage of the laser diode LD to drive the laser diode in the optical pickup unit 102 to record data on the optical disc 100.

The encoder 106 encodes data to be recorded according to a control signal into recording pulses in a format required by the optical disc 100 and then outputs the data to the optical driver 104.

The RF and servo error generator 108 may include an RF signal for data reproduction, a focus error signal FE for servo control, and a tracking error signal TE from an electrical signal output through the photodiode of the optical pickup unit 102. , Push-pull signal or the like. At this time, the RF signal is transmitted to the decoder 110 for reproduction, and a servo error signal such as a focus error FE and a tracking error signal TE is transmitted to the servo controller 114.

The decoder 110 restores original data from the RF signal detected by the RF and servo error generator 108.

The voltage level detector 112 of the push-pull signal detects (Vpp) the voltage level of the push-pull signal detected by the RF and servo error generator 108 to detect the tilt and the de-track, and transmits it to the servo controller 114. do.

The servo controller 114 processes the focus error signal FE to transmit a driving signal for focusing control to the focus servo driver 116, and processes the tracking error signal TE to signal the driving signal for tracking control. Transfer to tracking servo driver 118. The servo controller 14 processes the push-pull signal and transmits a driving signal for tracking control to the tracking servo driver 118.

The focus servo driver 116 drives the focus actuator in the optical pickup 102 to move the optical pickup 102 up and down so that the optical disk 100 follows the vertical movement along with the rotation.

The tracking servo driver 118 drives the tracking actuator in the optical pickup unit 102 to move the objective lens of the optical pickup unit 102 in the radial direction to correct the position of the beam and follow a predetermined track. do.

The tilt driver 120 controls the tilt servo by moving or adjusting the optical pickup 102 according to the tilt drive signal of the servo controller 114.

The controller 122 stores the optimal tilt control information of the optical disc 100 in the memory 124, and when the arbitrary optical disc 100 is loaded, the previously stored tilt control value when the optical disc is stored in the memory 124. To the tilt driver 120 through the servo controller 114 to perform the tilt servo. When the loaded optical disc 100 is a blank optical disc, the controller 122 sets the maximum value of the push-pull signal stored in the memory 124 as the tilt offset and finds the jitter value by using the OPC (Optimum Power Control). The tilt control value having the minimum value is provided to the tilt driver 120 through the servo controller 114 to perform the tilt servo.

The memory 124 stores ID information of the optical disc 100 and tilt control information of each optical disc 100.

A system for performing tilt servo control of an optical disk according to the present invention having such a configuration is an optical disk in which information is stored in the memory 124 when an arbitrary optical disk 100 is loaded, and the optical disk 100 recorded one or more times. The pre-stored tilt control value is provided to the tilt driver 120 through the servo controller 114 to perform tilt servo. When the loaded optical disc 100 is a blank optical disc in which information is stored in the memory 124, the maximum value of the push-pull signal stored in the memory 124 is used as the tilt offset, and after finding the jitter value using the OPC, the jitter value The minimum tilt control value is provided to the tilt driver 120 through the servo controller 114 to perform tilt servo.

3 is a flowchart illustrating a tilt servo control method for an optical disc according to the present invention.

2 and 3, the tilt servo control method of the optical disk according to the present invention proceeds sequentially as follows.

First, when the optical disc 100 is loaded, the controller 122 extracts a volume ID of the optical disc 100 and compares the volume ID with the optical disc ID previously stored in the memory 124 (S100).

The controller 122 determines whether the ID of the loaded optical disc 100 has the same ID among the optical disc IDs stored in the memory 124. (S102)

As a result of the determination of S102, when the ID of the loaded optical disc 100 has the same ID among the optical disc IDs stored in the memory 124, the controller 122 determines whether the optical disc 100 is a blank disc recordable (S104).

As a result of determination in S104, when the optical disc 100 is not a recordable blank disc and is an optical disc recorded more than once, the controller 122 corresponds to M grouped address information corresponding to the corresponding optical disc ID stored in the memory 124 and corresponds to each area. The optimal tilt control information is read (S106).

The control unit 122 reads the data from the optical disc 100 while moving the optical pickup unit 102 to enter the M grouped areas and automatically performs a tilt servo operation with the tilt control values of the respective areas (S110).

When the optical disc 100 is a recordable blank disc, the controller 122 recognizes the disc as a tilt control offset having the largest push-pull signal PP Amp among the information stored in the memory 124. S112)

The controller 122 performs an OPC process on the test area of the optical disc 100 and sets an optimal recording voltage by reading a signal recorded in the test area of the optical disc 100 (S114).

The controller 122 performs an OPC process on the test area of the optical disc 100 at the optimal recording voltage, reads the signal recorded in the test area of the optical disc 100, and measures the jitter value at this time.

The controller 122 records data from the optical disc 100 while resetting the tilt offset at which the jitter value is minimum and performing a tilt servo operation by the tilt control value of the reset tilt offset. (S118 to S120).

On the other hand, if it is determined in S102 that the ID of the loaded optical disc 100 does not have the same ID among the optical disc IDs stored in the memory 124, the control unit 122 divides the recording area of the optical disc into N areas equally, and each area. The jitter amount and the push-pull signal are measured from the RF signal (playback signal) according to the tilt change at (S122 to S124).

The controller 122 may set an optimal tilt offset value in which the jitter of the RF signal is minimized or the push-pull signal is maximum in each region (S126).

The controller 122 regroups the sections having similar tilt control values to group the N regions into M, and the ID of the optical disc 100, the M grouped address information, and the tilt offset of each of the M grouped regions. After storing the tilt control value, which is a value, in the memory 124, step S104 is performed. (S128 to S130)

Therefore, the tilt servo control method of the optical disc according to the present invention stores the ID of the optical disc 100, address information of the grouped M regions, and optimal tilt control information in each region in the memory 124, and then When the optical disc 100 having the ID stored in the memory 124 is loaded, the tilt servo is performed using the tilt control value stored in the memory 124. In addition, when the optical disc stored in the memory 124 is a blank optical disc, the maximum value of the push-pull signal stored in the memory 124 is the tilt offset, and after finding the jitter value using the OPC, the tilt control value having the minimum jitter value is determined. The servo is provided to the tilt driver 120 through the servo controller 114 to perform tilt servo.

As described above, the present invention stores the tilt control information of the optical disk in the memory and then performs a tilt servo using the tilt control value stored in the memory when the previously stored optical disk is loaded, and in the case of a blank optical disk, Find the jitter value and perform the tilt servo with the tilt control value with the minimum jitter value.

Therefore, the present invention can omit the process of dividing the tilt area every time the conventional optical disc is loaded and obtaining an optimal tilt offset value thereof, thereby greatly reducing the loading time delay of the optical disc and the load of the optical pickup unit, and the jitter Since the tilt servo is performed using the value, the accuracy can be improved compared to the tilt servo method using the push-pull signal.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (2)

In the method of controlling the tilt servo of an optical disk, Determining whether a volume ID of the optical disc is the same as a previously stored volume ID when the optical disc is loaded; Obtaining and storing tilt control information having a minimum jitter value or a maximum push-pull signal (PP AMP) in a plurality of areas of the optical disc when the volume ID of the optical disc is not a previously stored volume ID; Controlling the tilt servo using the tilt control information corresponding to the previously stored area of the optical disk when the volume ID of the optical disk is a previously stored volume ID and the optical disk is not a recordable blank disk; If the volume ID of the optical disc is a pre-stored volume ID and the optical disc is a recordable blank disc, OPC (Optimum Power Control) is performed using tilt control information having the maximum push-pull signal among the stored information, and a minimum jitter value is obtained. Setting the tilt control information Tilt servo control method of an optical disk comprising a. The method of claim 1, The storing of the tilt control information, And a volume ID of the optical disc, an area address of the optical disc, and tilt control information of the optical disc area.

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