KR0155871B1 - Tracking control method of optical disk drive - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control method for an optical disc drive, and more particularly, to a track inlet servo control method for an optical disc drive. In order to achieve the object of the present invention, it is determined whether the search operation is completed by comparing the difference between the target track and the current track. If the search operation is completed, the speed control operation is performed and the result is output. After the first step of performing the track follow-up control, and the first step of attempting to enter the track, it is determined whether the off-track has occurred, and outputs the track follow-up control value by setting the track follow-up control signal to 0 when the off-track is generated. And a third step of outputting a track following control signal after completing the track retry attempt. According to the present invention, there is an advantage that stable track insertion into adjacent tracks can be made even when an off track occurs during track entry after the track search operation of the optical disc drive.

Description

Tracking Control of Optical Disc Drive

1 is a block diagram showing an apparatus for performing a tracking control method of an optical disk drive of the present invention.

2A is a graph showing the command speed and the actual speed at the time of track search.

(b) is a waveform diagram at the track insertion operation.

(c) is a track cross pulse (TCP) generation degree.

(d) is a waveform diagram at off-track.

(e) is a waveform diagram at off-track.

(f) is an off-track control waveform diagram of the present invention.

3 is a flow chart showing a tracking control method of the optical disk drive of the present invention.

The present invention relates to a tracking control method for an optical disc drive, and more particularly, to a track input servo control method for an optical disc drive.

The conventional tracking control method is as follows. That is, track seek control is performed so that the current track and the designated target track are the same.

When the current track and the designated target track are the same, a track pull-in operation is performed. Even if off-track occurs after the track is entered, the track following control device continues to operate and waits for the track in to be made within a certain period. If the track retracting operation is not performed within a certain period, the track controller is opened and the track search operation is performed again.

However, in the conventional method, if an off track occurs after the track is drawn in, it is easy to diverge (congestion) because it becomes a positive feedback while the controller is operating. In addition, the optical focus is far from the target track even when entering the adjacent track of the target track without diverging, thereby requiring another remote search operation.

Accordingly, an object of the present invention is to provide a method for preventing congestion and attempting to reenter the nearest track when an aft track occurs during track retraction after a track search operation.

In the track retracting servo control method of the optical disk drive according to the present invention for achieving the above object, it is determined whether the search operation is completed by comparing the difference between the target track and the current track to perform a speed control operation during the search operation. And outputting the result, and when the search operation is completed, attempting track insertion to perform track following control: after the first step of attempting to enter the track, it is determined whether an off track has occurred, A second step of outputting a track following control value by setting the track following control signal to 0 may include a third step of outputting a track following control signal after completion of the track inlet retry in the second step.

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

FIG. 1 is a block diagram showing an apparatus for performing a tracking control method of an optical disk drive according to the present invention. The first subtractor 90 and the command speed generator 100 for comparing the target track Ndt with the current track Nct are shown in FIG. , Digitally with a speed controller 110, a second subtractor 114 that compares the commanded speed with the actual speed, a differentiator 120, a track following controller 190, and a switch 210 having contacts A, B, and C. Digital signal processor 300 for processing signals, D / A converter 140, tracking actuator and transfer motor 150, sensor and head amplifier 160, signal generator 170, track counter 180, A / D converter 200.

2 is a waveform diagram of tracking control of the optical disk drive of the present invention, (a) is a graph showing the command speed and the actual speed at the time of track search, and section (A) is the track lead-in section, and (b) is the track lead-in. Waveform diagram during operation, horizontal axis is time axis (t) and consists of track error signal (TES), track entry time (F), off track comparison level, track entry comparison level, and track cross pulse (TCP) comparison level. , (c) is a track cross pulse (TCP) occurrence rate, (d) is a waveform diagram when the off track occurs but is stabilized again from (d), the horizontal axis is the time axis (t) and the track error signal ( TES), track entry time (a), and off track comparison level, and (e) is a waveform diagram when an off track is generated and congested. The horizontal axis is a time axis (t) and a track error signal (TES), Track entry time (b), off track comparison level, (f) A waveform chart for stabilization during when the track is generated, (c) is a track lead-point, comprises a segment K, I, G, J.

3 is a flowchart of an interrupt routine showing a tracking control method of an optical disk drive according to the present invention, and includes a first step of performing search operations 300, 310, 330, and track following control 320, 340, 360, and 380. The second step (320, 340, 370, 380) outputting a track following control value of 0 when the off track is generated by determining whether an off track has occurred during the track following control, and outputting a track following control signal after completion of the track intake retry. It consists of a third step (320, 340, 360, 380). The interrupt routine is repeated every time at intervals of the sampling period Ts.

Specific embodiments of the present invention will be described in detail with reference to FIG.

The subtractor 90 in the digital signal processor 300 of FIG. 1 generates a difference signal between the target track Ndt to which the optical focus should move and the current track Nct. Here, the difference signal is the number of tracks (Nt) to be moved, and is input to the command speed generator 100 to generate the command speed. In addition, the subtractor 114 outputs a difference signal between the command speed generated by the command speed generator 100 and the actual speed output by the differentiator 120, and the difference signal is input to the speed controller 110 so that the optical pick up is performed. Let the speed of follow the commanded speed. Next, i _s , which is data output from the speed controller 100, is converted into an analog signal and output to the switch 210 contact A which is an output of the digital signal processor 300. The D / A converter 140 is applied to the tracking actuator and the transfer motor 150 to move the picket in the track crossing direction according to the control signal. A track error output signal from the sensor and head amplifier 160 is input to the signal generator 170 to generate a track cross pulse TCP and an off track signal. The track generator 180 counts the number of track cross pulses TCP that are track crossing signals using the track error signal TES in the signal generator 170.

Meanwhile, the track error signal TES output from the sensor and the head amplifier 160 is input to the analog-to-digital converter 200, and the track error signal, which is the input analog signal, is converted into a digital signal to convert the digital signal processor 300. It will be on the data bus. Next, the control unit in the digital signal processor 300 recognizes this and commands the track estimation controller 190 to generate a control signal i _{t such} that the optical focus of the optical picket tracks the disk eccentricity.

FIG. 2 (a) shows the command speed and the actual speed of the light output during the search operation. FIG. 2 (b), (c), ( d), (e) and (f). That is, the difference between the target track Ndt to be moved in the digital signal processor 300 and the current track Nct is compared (step 3300), and if the difference is not 0, the speed control operation is performed (FIG. 310 310). And outputs the data value i _s to the D / A converter 140 (process 300 in FIG. 3), and the i _s value is applied to the tracking actuator and the transfer motor 150. In the search section, switch C of FIG. 1 is connected to A, and the track traversal speed of the optical focus tracks the trapezoidal command speed in FIG. 2 (a).

The track counter also counts the track cross pulse TCP in FIG. When the current track is called Nct and the target track is called Ndt, when Nct = Ndt (search completion state), the contact point C of the switch 210 of FIG. 1 is switched to B to perform the track retracting operation. FIG. 2B shows the signal waveform when the track inlet operation is successful. Here, the TCP comparison level is used to generate a track cross pulse (TCP) by comparing with the track error signal (TES), and the track incomparison comparison level is set to determine the track in point. It is the level set to determine.

In this case, when the track insertion operation has occurred due to disturbance or some cause at the time of track insertion (Fig. 2 (d), (e) (a) and (b)), that is, the track error signal TES is off track. If it is out of the comparison level, the tracking controller is completely out of control as shown in (e) of FIG. 2 and becomes out of control, or stabilizes after several tracks as shown in FIG. The cause of the off-track during the track lead-in of FIG. 2 is a change in the track lead-in speed due to a speed error in the search section, a scratch of a disk, an external shock, and the like. Accordingly, when the off track occurs and enters the positive feedback region as shown in the section I of FIG. 2 (f), the digital signal processor 300 determines whether the off track is generated (step 340 of FIG. 3). If the off track does not occur, the track tracking control operation is performed (FIG. 3) to output a normal control signal to the D / A device 140. On the other hand, when the off track occurrence is detected, the track following control signal i _t is set to 0 (370 in FIG. 3) to output a signal having the track tracking control signal of 0 to the D / A device 140 (FIG. 3 380). . Therefore, the system does not diverge (runaway) in section G of FIG. 2 (f). The track traversal speed in section G of FIG. section J of (f). That is, the track reentry is retried in the section J (d) of FIG. 2 (f), the time point at which the tracking is stabilized (step 350 in FIG. 3). subject to _t D / a conversion is applied to the tracking actuator and a feed motor 150 (the third process ° 360).

As described above, according to the present invention, there is an advantage that stable track insertion into adjacent tracks can be made by adjusting the track control signal even when an off track occurs during track entry after the track search operation of the optical disc drive.

Claims (1)

In the track input servo control method of an optical disk drive, a difference between a target track and a current track is determined to determine whether a search operation is completed, and if a search operation is performed, a speed control operation is performed to output a result and the search operation is completed. The first step of performing track follow-up by performing track injecting: after the first step of attempting to inject the track, it is determined whether an off track has occurred, and the track follow-up control signal is zero when the off-track is generated. And a second step of outputting a value: a third step of outputting a track following control signal after completion of the track retreading in the second step.