KR100245603B1 - Servo device for setting up high speed position - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed positioning servo device for moving an optical head to a target track in a short time without errors in order to read or write desired data on a disc in an optical disc drive system. The reference tracking error value is stored in the ROM table, and the actual error signal generated when the optical head moves to the target track and the reference tracking error signal value are compared to correct the position error as much as the error occurs. By correcting the error every time the optical head passes through the track, the position and speed are precisely controlled so that the optical head can be accurately positioned at a desired target track at high speed. Therefore, the performance of the drive system can be improved by precisely fast positioning by compensating the error for each track by comparing the error value predicted and the error at the actual position when positioning to the desired target track in the optical disc drive system. The manufacturing cost can be reduced because a separate position and speed sensor or circuit for detecting position and speed errors is not used.

Description

High speed positioning servo device

1 is an overall configuration diagram of a high speed positioning servo device of the present invention;

2 is a detailed circuit diagram of the tracking error signal generator of FIG. 1;

3 is a detailed circuit diagram of the fine tracking servo compensation circuit and the coarse tracking servo compensation circuit of FIG.

(A) of FIG. 4 is a track structure diagram of an optical disc, (b) is a tracking error signal output waveform diagram of FIG.

(A) is a tracking error signal diagram, (b) is a tracking error reference signal waveform diagram, (c) is a signal waveform diagram when positioning acceleration / deceleration signals,

6 is a speed characteristic diagram with respect to the speed at the position setting,

7 is an operational flow diagram for the present invention.

* Explanation of symbols for main parts of the drawings

1 Optical part 2 Preamplification part

3: Tracking error signal generator 4: Fine tracking servo compensation circuit

5: Fine Tracking Power Amplifier 6: Fine Tracking Actuator

7: Track position error signal generator 8: Core tracking servo compensation circuit

9: Cores tracking power amplifier 10: Cores tracking actuator

3A: Photodetector 3B: Operational Amplifier

3C: Low Pass Filter 3D: Automatic Gain Control

The present invention relates to a high-speed positioning servo device for moving an optical head to a desired target track in a short time without error in order to record information on a target track on a disc having a track structure and reproduce the recorded information in an optical disc drive system. .

In the conventional optical disc drive, the positioning servo device applies actuator driving voltage as many as the number of tracks to the target track to be moved to the actuator when positioning to the desired target track, and feeds back the tracking error signal generated when moving the track. After converting it into a pulse signal, the number of tracks moved is calculated by calculating this pulse signal. The driving voltage of the actuator accelerates by 1/2 track of the number of moving tracks and the next 1/2 track decelerates to move the optical head to the desired target track. Since this method calculates the feedback tracking error signal and controls the position, the number of track positions controlled by the number of tracks to be moved and the position and error of the track to which the actual actuator has moved are large, and the optical head must be moved by the number of error tracks again. It takes a lot of time to position the target track and cannot compensate for the track error caused by the run-out or disturbance of the optical disc itself, so the reliability of the device is very low, and the positioning servo is the target track. When setting the position, attach the sensor to the actuator to calculate the tracking error signal generated by the actuator's movement when setting the position and move it to the desired target track.This method attaches a position sensor circuit that allows the actuator to detect the position. Move the optical head by increasing the weight of the actuator It takes a long time to perform, and also has the disadvantage of expensive manufacturing by adding a circuit.

SUMMARY OF THE INVENTION In view of such a conventional problem, the present invention provides an optical head system in which an optical head is a desired target track when an optical disc system records information on a target track on a disc having a track structure and positions the target track on the disc to reproduce recorded information. It is characterized in that to move without error in a short time.

That is, the reference tracking error value (computer simulation value for the number of tracks to be moved) according to the number of tracks to be positioned (sampling time, acceleration / deceleration position and speed, disk track structure, actuator constant) is stored in the ROM table. The error is corrected by applying the normal tracking error signal when the desired number of tracks are set, the tracking error signal generated when the land / groove of the actual track is moved, and the speed characteristics and acceleration / deceleration signals corresponding to the number of actuator moving tracks. It reads the reference tracking error information stored in the ROM table, samples the input tracking error signal each time the optical head passes each track, corrects the error every time the track moves, and accurately locates the target track without accumulating errors. To be set.

When described in detail with reference to the drawings as follows.

The high speed positioning servo device according to the present invention includes a preamplifier 2 for detecting and amplifying a laser light amount as shown in FIG. A tracking error signal generator (3) which receives the amount of laser light from the power amplifier (2) and generates an error signal as much as it leaves the track when tracking the actual disc track; A ROM 11 storing a reference tracking error signal value, a digital / analog converter 12 converting a reference tracking error signal read from the ROM 11 into an analog signal, and an analog signal from the digital / analog converter 12. An amplifier 13 that receives and amplifies a reference tracking error signal, an analog reference tracking error signal b amplified by the amplifier 13, and a tracking error signal a output from the tracking error signal generator 3; A fine tracking servo compensation circuit unit 4 comprising an amplifier 14 for compensating for the position error as compared with the actual error and compensating for the tracking error signal; A fine tracking power amplifier (5) for generating power to receive the error signal (c) compensated by the fine tracking servo compensation circuit (4) for fine tracking operation; A fine tracking actuator 6 that receives power from the fine tracking power amplifier 5 and performs fine tracking; and a fine tracking actuator 6 and a coarse tracking actuator (6) after the optical head is moved using a track position signal. A track position error signal generator 7 for generating a tracking error signal to correct as much as another position when the positions of 10) are different; ROM 11 for storing reference tracking error signal values, digital / analog converter 12 for converting the reference tracking error signal read from ROM 11 into an analog signal, and analog reference in the digital / analog converter 12. An amplifier 13 that receives and amplifies a tracking error signal, an analog reference tracking error signal b amplified by the amplifier 13, and a tracking error signal a output from the track position error signal generator 7; A coarse tracking servo compensation circuit unit 8 including an amplifier 14 compensating for the position error as compared with the actual error and compensating for the tracking error signal; A coarse tracking power amplifier (9) for generating electric power to receive coarse tracking operations by receiving the error signal (c) compensated by the coarse tracking servo compensation circuit (8); The coarse tracking power amplifier 9 receives power from the coarse tracking actuator 10 to perform coarse tracking.

The tracking error signal generation section 3 includes a photodetector 3A for detecting the photocurrent coming from the disk as shown in FIG. An operational amplifier section 3B for amplifying a signal input from the photodetector 3A; A low pass filter 3C which selects only a predetermined frequency range among the signal frequencies amplified by the operational amplifier 3B; The low pass filter 3C receives a signal selected only from a predetermined frequency range and configures an automatic gain adjuster 3D that adjusts a gain of a signal required for a tracking error signal.

Referring to the operation and effects of the present invention configured as described above in detail.

When positioning the target track / sector area of the optical disc of the optical disc drive system, the high-speed positioning servo device for moving the optical head at high speed without error to the desired track / sector without error and tracking the track accurately in the positioned area is first performed by the optical unit. When the amount of light input through (1) is amplified to the required signal level in the power amplifier 2 and outputted, the tracking error signal generator 3 receives the signal output from the power amplifier 2 and actually outputs the signal. When the disc track is tracked, an error signal that is out of the track is output to the fine tracking servo compensation circuit section 4.

Then, the fine tracking servo compensation circuit unit 4 receives the error signal output from the tracking error signal generator 3, compensates for the error signal, and outputs the error signal to the fine tracking power amplifier 5. The fine tracking power amplifier 5 receives the compensated error signal and outputs power to the fine tracking actuator 6 to perform fine tracking.

Subsequently, the fine tracking actuator 6 receives the power output from the fine tracking power amplifier 5 and performs a fine tracking operation.

On the other hand, the track position error signal generator 7 corrects the other position when the position of the fine tracking actuator 6 and the coarse tracking actuator 10 differs after the optical head moves using the track position signal. A tracking error signal is generated to the coarse tracking servo compensation circuit section 8.

Then, the coarse tracking servo compensation circuit unit 8 receives the error signal output from the track position error signal generator 7, compensates the error signal, and outputs the coarse tracking power amplifier 9 to the coarse tracking power amplifier 9. The coarse tracking power amplifier 9 receives the compensated error signal and outputs power to the coarse tracking actuator 10 to perform coarse tracking.

Subsequently, the coarse tracking actuator 10 receives a power output from the coarse tracking power amplifier 9 and performs a coarse tracking operation.

The tracking error signal is compared with a tracking error signal value as shown in FIG. 4 (b) in which the optical head occurs in the land / groove area of a track on the disc as shown in FIG. 4A, and a reference error value at the track position. The difference is compensated for by the error.

In this case, the operation of the above-described fine tracking servo compensation circuit unit 4 and coarse tracking servo compensation circuit unit 8 will be described with reference to FIG. 3, where the tracking error reference signal is read from the ROM 11. Is converted into an analog signal through the digital analog converter 12 and amplified by the amplifier 13 by the required signal level, and then added to the tracking error signal (a) that is actually generated. The signal a and the predicted error signal b are compared and amplified by the amplifier 14. The tracking error reference signal generation circuit estimates the tracking error value at the track position when moving to the target track (pre-computer simulated error value) and the error value at the actual moving position (actual tracking generated in FIG. 1). The difference is corrected by comparing with the error value (a).

The principle of high speed operation is as follows.

First, when the controller receives the information about the target track (moving track) through the microprocessor, the high-speed positioning servo device operates as shown in the first embodiment of the present invention, and the acceleration / deceleration voltage data of the number of tracks to be moved is stored in the ROM 11. Output the value to the digital / analog converter 12, the actuator moves to the target track according to the output value, and the position tracking error of the track where the actual optical head is located (FIG. 3a) and the reference tracking error read from the ROM table. Compare to the signal. The output signal value (FIG. 3C) of FIG. 3 becomes the actual position error of the optical head, and the error value is corrected to position the target track. At this time, a tracking error signal as shown in FIG. 5 (a) and a reference tracking error signal as shown in FIG. 5 (b) obtained from the ROM table, and velocity characteristics for acceleration / deceleration as shown in FIG. 5 (c). The table is shown in FIG.

When the optical head is positioned at the target track at high speed, the switching circuit switches the voltage driven to the actuator to select the sampling time, and the positioning is performed at the target track at high speed by simultaneously performing the positioning by the fine actuator or the coarse actuator. Set it. At the time of positioning, the output signal is sampled, and then inputted to an adder through a phase compensation circuit, followed by analog conversion, followed by a tracking error signal and a reference tracking error signal, and then input to an amplifier and fine actuator 6 or coarse actuator 10. Input to the drive head to position the target track.

Receiving a positioning command such as the positioning direction, the number of tracks to be positioned, and the like as shown in FIG. 7 when the entire operation during the high-speed movement of the optical head to the target track is shown in a flow chart (A1); Applying (A2) a voltage corresponding to the track to be positioned with the fine or coarse actuator by the received command; Generating an acceleration or deceleration signal for the number of tracks to be positioned by the applied voltage to confirm whether the target track is correctly positioned in the target track (A3); Confirming the position setting and retrying even when the positioning fails, and correcting the position of the fine and coarse actuators with the track position error occurrence value after setting the position (A4); In order to keep the position at the position, the micro-jump continues to be executed while the next operation is waited for (A5).

As described in detail above, the present invention stores the predicted reference tracking error value for the desired target track position in the ROM table and stores the actual error signal and the reference tracking error signal value generated when the optical head moves to the target track. Comparing the position and speed errors for each position of the error as compared to each track, the performance and access time of the disc drive can be improved, and the error is corrected every time the optical head of the target track passes each track. By precisely controlling the position and speed, the optical head can seek precisely and quickly to the desired target track, so that the manufacturing cost can be reduced because a separate position and speed sensor or circuit is not used as in the conventional optical disc. have.

Claims (1)

A preamplifier 2 for detecting and amplifying the laser light amount; A tracking error signal generator (3) which receives an amount of laser light from the power amplifier (2) and generates an error signal as much as it leaves the track when tracking the actual disc track; A ROM 11 storing a reference tracking error signal value, a digital / analog converter 12 converting a reference tracking error signal read from the ROM 11 into an analog signal, and an analog signal from the digital / analog converter 12. An amplifier 13 which receives and amplifies a reference tracking error signal, an analog reference tracking error signal b amplified by the amplifier 13 and a tracking error signal a output from the tracking error signal generator 3; A fine tracking servo compensation circuit unit 4 comprising an amplifier 14 compensating for the position error as compared with the actual error and compensating for the tracking error signal; A fine tracking power amplifier (5) for generating power to receive the error signal (c) compensated by the fine tracking servo compensation circuit (4) for fine tracking operation; A fine tracking actuator 6 for receiving power from the fine tracking power amplifier 5 to perform fine tracking; A track position error signal generator for generating a tracking error signal to correct a different position when the positions of the fine tracking actuator 6 and the coarse tracking actuator 10 are different after the optical head is moved using the track position signal ( 7); ROM 11 for storing reference tracking error signal values, digital / analog converter 12 for converting the reference tracking error signal read from ROM 11 into an analog signal, and analog reference in the digital / analog converter 12. An amplifier 13 that receives and amplifies a tracking error signal, and an analog reference tracking error signal b amplified by the amplifier 13 and a tracking error signal a output from the track position error signal generator 7. A coarse tracking servo compensation circuit unit 8 comprising an amplifier 14 for compensating for the position error as much as an actual error occurs by compensating for the tracking error signal; A coarse tracking power amplifier 9 configured to receive an error signal c compensated by the coarse tracking servo compensation circuit unit 8 to generate coarse tracking operations; And a coarse tracking actuator (10) for receiving coarse tracking by receiving power from the coarse tracking power amplifier (9).