KR100686167B1 - Method and apparatus for track jumping in optical record medium - Google Patents

Abstract

A track jump method and apparatus for an optical recording medium for performing a track jump using a tracking actuator, the method comprising: driving a tracking actuator when a track jump command is input, and a speed and position of the tracking actuator when the tracking actuator is driven; Estimating and feeding back the feedback signal; continuously generating and outputting the tracking actuator driving signal according to the feedback position and the speed information; and continuously driving the tracking actuator according to the continuous control signal to reach a target position. It is possible to move any number of tracks at the time of fine seek.

Fine seek, continuous control

Description

Method and apparatus for track jumping in optical record medium

1 is a block diagram of a general optical record player

2 is a waveform diagram of a TZC signal that is detected and shaped upon fine seek

3 is a block diagram illustrating a track jump method for an optical record carrier according to the present invention;

4A is a waveform diagram of a TZC signal at 30 track forward fine seek in accordance with the present invention.

4B is a waveform diagram of a tracking actuator drive signal using the TZC signal of FIG. 4A.

5A is a waveform diagram of a TZC signal at one track forward fine seek in accordance with the present invention.

5B is a waveform diagram of a tracking actuator drive signal using the TZC signal of FIG. 5A.

Explanation of symbols for main parts of the drawings

301: Subtractor 302: Servo controller

303: switching unit 304: tracking actuator drive unit

305: TZC signal generator 306: position calculator

300: micom

The present invention relates to a track jump method of an optical record carrier, and more particularly, to a track jump method of an optical record carrier configured to perform a fine seek in which a track remaining after a rough seek is completed using a tracking actuator in a closed loop. And to an apparatus.

In general, an optical recording medium system, that is, an optical disc recording and reproducing apparatus, uses an optical disc such as a compact disc (CD), a digital versatile disc (DVD), or the like as a recording medium to reproduce data recorded on the disc or write data to the disc. It is a device for recording.

In order to reach the desired point on the optical disk, the laser beam generated in the pickup must be accurately moved from the current track to the target track and tracked on the target track. This is called seek or search.

This seek operation calculates the number of tracks to the target track, and if the number of tracks to be jumped is hundreds to thousands of tracks or more, the sled motor is moved to move the entire optical pickup near the desired track, and then the remaining tracks are hundreds of tracks. In the following case, a track actuator is used to find a track. At this time, jumping the track by moving the slad motor may be referred to as rough seek, and moving the track by moving only the tracking actuator may be referred to as fine seek.

FIG. 1 is a block diagram of a general optical disk recording / reproducing apparatus, wherein the optical pickup 102 causes a light beam focused on an objective lens to be placed on a signal track of the optical disk 101 by the control of the servo control unit 104, In addition, the light reflected from the signal recording surface is condensed by the objective lens and then incident to the photo detector for detection of the focus error signal and the tracking error signal.

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 103.

The RF and servo error generation unit 103 is an RF signal for reproducing data, a focus error (FE) signal for servo control, a tracking error (TE) signal from an electrical signal output from each photodetector of the photodetector. And the like are output to the western control unit 104.

The servo controller 104 generates a drive signal for focusing control from the FE signal and outputs it to the focus servo driver 105, and generates a drive signal for tracking control from the TE signal and outputs it to the tracking servo driver 106. .

At this time, the focus servo driver 105 moves the optical pickup 102 up and down by driving the focus actuator in the optical pickup 102 in accordance with the focus drive signal, so that the optical disk 101 is rotated up and down. Follow along.

The tracking servo driver 106 corrects the position of the beam by moving the objective lens of the optical pickup 102 in the radial direction by driving the tracking actuator in the optical pickup 102 according to the tracking drive signal. Track a given track. At this time, during the normal recording / reproducing operation or fine seek, the tracking actuator is driven to move the objective lens of the optical pickup in the radial direction.                         

In addition, the servo control unit 104 detects the rotational speed information of the disk from the RF signal and outputs it to the spindle servo 109. The spindle servo 109 rotates the disk 101 by controlling a phase locked loop (PLL) of the spindle motor 110 according to the rotation speed information. That is, the spindle motor 110 gives a rotational force to the spindle (not shown) for the rotation of the disk 101, the spindle transmits the rotational force given by the spindle motor 110 to the disk 101 to convey the disk 101. Rotate at the desired speed.

On the other hand, in the case of rough seek to move the entire optical pickup, the sled servo driver 107 receives a sled control signal from the servo controller 104 and drives the sled motor 108 to drive the optical pickup main body. Transfer directly in the desired direction.

When the optical pickup main body is moved by the above-described process and rough seeking is finished, it is checked whether the current position of the optical pickup is the target track, and if the target track is not the target track, how many target tracks remain to perform fine seek.

Then, the tracking actuator is used to find the target track.

In this case, the conventional fine seek was performed in an open loop manner. In other words, a plurality of track jump commands were tuned in advance, and a combination of them was used to jump tracks several times to find the target track.

For example, if the number of tracks to jump to is 88 tracks and the predetermined track jump command is 1, 5, 10, 50, 100, 50 track jumps 1, 10 track jumps 3, 5 track jumps to jump 88 tracks. A total of eight kick / brake controls were required, including 1 and 1 track jump 3 times.

That is, the conventional fine seek method has a drawback in that it takes a lot of access time because the number of track jumps increases. In addition, if the servo system is not stable, transient response such as leaving the target track is greatly generated. In such a case, it may be the cause of unwanted mechanical noise, track slippage, etc. may occur, and the case where the seek is required once again may occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to perform a track jump by configuring a fine seek closed loop, whereby a track jump method of an optical recording medium searching for a target track with a single track jump and Relates to a device.

In accordance with another aspect of the present invention, there is provided a track jump method of an optical recording medium, the method comprising: driving a tracking actuator when a track jump command is input; and estimating a speed and a position of the tracking actuator when the tracking actuator is driven. Feedbacking, continuously generating and outputting the tracking actuator drive signal according to the feedback position and speed information, and continuously driving the tracking actuator according to the continuous control signal to reach a target position. It is characterized by comprising.

Position and velocity information of the tracking actuator is characterized in that it is estimated from the track zero cross (TZC) signal.

When the number of tracks to be jumped by the track jump command is 2 tracks or less, track jump is performed by kick / brake voltage control.

A track jump apparatus for an optical recording medium according to the present invention includes a position calculator for calculating a current position of a tracking actuator from a track zero cross signal generated at the time of driving a tracking actuator by a track jump command, a reference position and the current position, Servo control unit for generating a control signal through the difference, and characterized in that it comprises a micom for controlling the drive of the tracking actuator in accordance with the control signal of the servo control unit.

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.

That is, during fine seek, since the moving speed of the tracking actuator is not very fast depending on the disc track, the track zero crossing (TZC) signal generated from the TE signal is not attenuated very much. Therefore, by amplifying and shaping the TZC signal, a waveform as shown in FIG. 2 can be obtained. The TZC signal is a signal that is turned on / off at a track cross time point, and may be obtained by slicing the TE signal at a track zero cross position.

At this time, by using the TZC signal as shown in FIG. 2, information on the position and speed of the tracking actuator can be obtained. Here, since one period of the TZC signal corresponds to 0.74 µm for DVD (1.6 µm for CD), the position of the tracking actuator can be obtained by counting the number of pulses. That is, the position is a relative position of the tracking actuator and can be known by counting from the start position of the TZC signal generated after the kick pulse.

At this time, the absolute position information to be controlled from the position information can be obtained. However, since there is currently no information on the movement of the actuator drive system, a speed estimation algorithm is required to detect this.

Accordingly, the speed at which the tracking actuator moves can be obtained by, for example, Equation 1 using a fixed-position velocity estimation method. That is, Equation 1 below is a velocity value estimated at the nth sampling time point.

In Equation 1, T (n) is the nth track cross time, Tp is the track pitch, DVD is constant at 0.74 µm, CD is 1.6 µm, and the actuator movement distance is divided by time. That is, the speed is estimated by the speed estimation algorithm of Equation 1 and fed back every cycle of the TZC signal. For example, the continuous control may be performed by estimating and feeding back a speed every time the TZC signal is detected.

Then, the controller is configured as shown in FIG. 3 to accurately find the target track using the position and velocity feedback obtained through the above process.

Referring to FIG. 3, a subtractor 301 which obtains a position measurement error by subtracting a position measured from a reference position ref, and a servo controller 302 which obtains a transfer function from the position measurement error of the subtractor 301 and outputs a continuous control signal. ), To the output of the switching unit 303 and the output of the switching unit 303, which selectively outputs one of a kick voltage or a brake voltage, which is continuously controlled from the servo controller 302 under the control of the microcomputer 300. The tracking actuator driver 304 for driving the tracking actuator according to the present invention, the TZC signal generator 305 for generating a TZC signal from the TE signal generated when the tracking actuator driver is driven by the tracking actuator driver 304, and the TZC signal generator ( The position calculation unit 306 calculates a position at which the tracking actuator moves from the TZC signal output from the line 305 and feeds it back to the subtractor 301.

In the present invention configured as described above, in the case of fine seek, the position calculation unit 306 estimates the tracking actuator moving speed from the TZC signal by applying Equation 1, calculates the current position, and feeds back the subtractor 301.

The subtractor 301 calculates a position measurement error by subtracting the reference position ref and the measured position fed back, and outputs the position measurement error to the servo controller 302 and the microcomputer 300. Here, when the position measurement error value is 0, since the tracking actuator reaches the target position, the fine seek ends. If the position measurement error value is not 0, since the target position has not been reached yet, the fine seek is continuously performed.

The servo controller 302 sets a gain for moving the tracking actuator, which is mathematically modeled below. That is, the closed loop transfer function C (s) of the servo controller 302 is expressed by Equation 2 below.                     

는 트랙킹 액츄에이터의 질량,

Is the mass of the tracking actuator,

는 트랙킹 액츄에이터의 점성 마찰 계수,

Is the coefficient of viscous friction of the tracking actuator,

는 트랙킹 액츄에이터의 스프링 상수이다.

Is the spring constant of the tracking actuator.

와

을 결정하면,

와

가 결정된다. 본 발명에서는 일 예로,

=0.65,

=2π* 200 rad로 설정하였다. 이는 트랙킹 액츄에이터가 목표 트랙에 도달하는 순간 트랙 추종 제어로의 전환이 용이하도록 즉, 목표 트랙에 도달할 때 트랙킹 액츄에이터의 디스크 트랙에 대한 상대 속도가 충분히 느리도록 하기 위해서 크리티컬 댐핑에 가까운 정도의 댐핑을 설정한 것이다.In Equation 2 described above

Wow

If you decide,

Wow

Is determined. In the present invention, as an example,

= 0.65,

= 2π * 200 rad. This makes it easy to switch to track following control as soon as the tracking actuator reaches the target track, i.e., close to the critical damping in order to make the tracking actuator's relative speed to the disk track slow enough when reaching the target track. It is set.

In this case, in the case of continuous control, the output of the servo controller 302 is output to the tracking actuator driver 304 through the switching unit 303.

는 하기의 수학식 3과 같다.Here, the transfer function of the tracking actuator of the tracking actuator driver 304

Is the same as Equation 3 below.

The microcomputer 300 generates a switching selection signal according to the number of tracks to be tracked by the tracking actuator and outputs the switching selection signal to the switching unit 303.

That is, the microcomputer 300 generates a selection signal to initially select the kick voltage during fine seek, and then calculates the number of tracks to be tracked from the position measurement error value obtained from the feedback position and the speed, and calculates the number of tracks by the calculated number of tracks. When continuous control is required, a selection signal is generated to select the output of the servo controller 303.

Then, the tracking actuator driver 304 first moves the tracking actuator by the kick voltage. Then, the tracking actuator is driven by the continuous control signal output from the servo control unit 303 to reach the target track.

For example, assuming that the number of tracks to be jumped is 30 tracks, the control unit 303 selects and outputs a kick voltage under the control of the microcomputer 300 and then the servo until the position measurement error value approaches zero. The output of the controller 302 is selected. That is, the position measurement error value decreases as the tracking actuator approaches the target position as the number of times of the closed loop of FIG. 3 is repeated.

4 is a waveform diagram at 30 track forward fine seek, FIG. 4A is a TZC signal at this time, and FIG. 4B is a tracking actuator drive signal.                     

Referring to FIG. 4, it is understood that 30 tracks are jumped by a single track jump, and 30 tracks are jumped at a time by a gentle brake operation after a kick voltage is applied. At this time, it can be seen that the switching to the tracking mode is well performed without overshooting.

On the other hand, when the number of tracks to be followed in fine seek is small, for example, when the number of tracks to jump is 1 to 2 tracks, the present invention does not apply. In this case, if the number of tracks to be followed is too small and the present invention is applied, the positional measurement error may be increased and thus the transient response may be increased. Therefore, in this case, the control using the open loop, that is, the kick / break pulse as in the conventional case is performed. FIG. 5 is a waveform diagram of two track forward fine seek, FIG. 5A is a TZC signal, and FIG. 5B is a tracking actuator drive signal at this time.

As described above, according to the track jump method and apparatus of an optical record carrier according to the present invention, by estimating and feeding back position and velocity information using a standardized TZC signal, and continuously driving the tracking actuator according to the feedback information, During fine seek, any number of tracks can be moved at once. This results in faster fine seek access time and less transient response.

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 (4)

In the track jump method of an optical recording medium for performing a track jump using a tracking actuator, Driving a tracking actuator when a track jump command is input; Estimating and feeding back the speed and position of the tracking actuator when the tracking actuator is driven; Continuously generating and outputting the tracking actuator drive signal according to the feedback position and speed information; And And continuously driving the tracking actuator in accordance with the continuous control signal to reach a target position. According to claim 1, wherein the position and speed information of the tracking actuator is A track zero crossing (TZC) signal is generated and estimated from a tracking error signal generated when driving a tracking actuator. The method of claim 1, And if the number of tracks to be jumped by the track jump command is 2 tracks or less, track jump is performed by kick / brake voltage control. In the track jump apparatus of an optical recording medium for performing a track jump using a tracking actuator, A position calculator for calculating a current position of the tracking actuator from a track zero cross signal generated at the time of driving the tracking actuator by the track jump command; A servo controller which generates a control signal based on a difference between a reference position and the current position; And And a micom for controlling the driving of the tracking actuator according to a control signal of the servo control unit.

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