KR100393203B1 - Method for controlling servo in cd-rom drive - Google Patents

Abstract

PURPOSE: A method for controlling servo in a CD-ROM drive is provided to stably operate a drive system even in an eccentric disk or an equipment causing eccentricity by controlling a gain of a sled motor based on an error in track movement. CONSTITUTION: If a disk is secured on a turntable, a spindle motor is driven at a constant linear velocity(21). Tracking servo is turned off in a track on state, and is maintained in a focus mode(22). A tracking error signal is detected(23). A first maximum track width point is checked based on the detected tracking error signal(24). It is judged whether a second maximum track width point is checked succeeding to the first maximum track width point(25). If so, it is judged whether the number of tracks between the first maximum track width point and the second maximum track width point exceeds a reference track number(26). If so, a sled motor gain is set higher than a reference gain(27). If not, the sled motor gain is set up as the reference gain(28).

Description

Servo control method in CD-ROM drive

The present invention relates to a compact disc-read only memory (CD-ROM) drive, and more particularly, to a servo in a CD-ROM drive capable of stably operating a drive system even when playing an eccentric disk. It relates to a control method.

CD-ROM refers to a large-capacity storage medium with a diameter of 12cm and 680MB that can only be played using laser light like a CD for general music. A CD-ROM drive, which is a device that substantially drives such a CD-ROM, usually controls the data access of the pickup by four servo controls. That is, the focus position is controlled so that the focus of the laser beam that reads the signal recorded on the disk surface is always aligned with the pit position of the disk, and follows the up and down vibration of the disk surface. A focus servo to allow the laser beam to follow the disc's eccentricity while controlling the position of the laser beam so that the laser beam follows the track on the disc surface; and a pickup servo to track the disc from the inner circumference. A sled servo that controls the motor of the sled drive mechanism to move up to and follow the spiral track on the disk surface, and controls the rotation speed and phase of the disk, and the constant linear velocity By the spindle servo which controls the rotation of the disk at a fixed speed, the pickup is controlled so that the data access of the pickup can be made accurately.

1 is a schematic diagram of a system of a general CD-ROM dry apparatus.

Referring to this, the CD-ROM drive reads the spindle motor 12 for rotating the compact disc 11 seated on the turntable 12t and the information recorded on the disc 11 by using a laser beam. Receives a predetermined control command from the pickup 13, the sled drive shaft 14 for linearly moving the pickup 13 in a reciprocating manner, the microcomputer 15 for controlling the system as a whole, and the microcomputer 15 DSP (Digital Signal Processor: 16) for outputting a signal for driving the spindle motor 12, and SSP (Servo Signal Processor) for receiving a predetermined signal from the pickup 13 and delivering it to the microcomputer (15) And a ROM decoder 18 for transmitting the information received from the DSP 16 to a separate host computer (not shown) through the PC interface 19.

On the other hand, in the CD-ROM drive having the above configuration, conventionally, even in the case of an eccentric disc, the servo gain is set by finding an appropriate servo gain value within the range in which the servo can be controlled as in the case of a normal disc. It was. However, this method does not transfer the pickup to a desired position in the case of a large eccentric disc or a CD-ROM drive deck that causes the eccentricity, and thus the drive system cannot be stably operated. There is this.

The present invention has been made in view of the above problems, and an object thereof is to provide a servo control method for a CD-ROM drive capable of stably operating a drive system even when playing an eccentric disc.

Servo control method in the CD-ROM drive according to the present invention to achieve the above object,

(a) driving the spindle motor at a predetermined speed when the disk is seated on the turntable;

(h) turning off the tracking servo in the tracking on state by driving the spindle motor and maintaining only in focus mode;

(c) detecting a tracking error signal in said step (b) and state;

(d) checking a first maximum transistor width point based on the detected tracking error signal;

(e) determining whether a second maximum track width point is checked subsequent to the first maximum track width point;

(f) returning the system flow to continue checking if the second maximum track width point is not checked in step (e), and if checked, the number of tracks between the first maximum track width point and the second maximum track width point ( Determining whether N) exceeds a predetermined reference track number; And

(g) setting the sled motor gain higher than the reference gain if the track number N exceeds a predetermined reference track number, and setting the sled motor gain as the reference gain if the track number N exceeds the predetermined reference track number. There is a characteristic in that.

According to the method of the present invention as described above, an error in the track movement of the pickup due to the disk eccentricity is detected, and the gain of the sled motor is adjusted based on this and reflected in the servo control. The device has the advantage of operating the drive system stably.

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

2 is a flowchart showing the execution of the servo control method in the CD-ROM drive according to the present invention.

Reference will also be made to FIG. 1 for better understanding in the description of the servo control method according to the present invention.

Referring to FIG. 2, first, when the compact disk 11 is seated on the turntable 12t, the spindle motor 12 is driven at a predetermined speed (step 21). Then, the tracking servo is turned off in the tracking on state by the drive of the spindle motor 12 and maintained only in the focus mode (step 22). Then, in such a state, a tracking error signal (TES) as shown in FIG. 3 is detected (step 23). Then, the first maximum track width point A is checked based on the detected tracking error signal (step 24). Then, it is determined whether the second maximum track width point B is checked following the first maximum track width point A (step 25).

If the second maximum track width point B is not checked in step 25, the system flow is returned to continue checking, and if the second maximum track width point B is checked, the first maximum track width point A and the second maximum track width point B are checked. It is determined whether the track number N (corresponding to the disc eccentricity) of the liver exceeds a predetermined reference track number, for example, 300 (step 26). Here, the reference track number set to 300 is based on arbitrary experimental data focused on the relationship between the disk eccentricity and the sled servo, and the reference track number may be set to a different value in some cases.

On the other hand, if the track number N exceeds 300 in step 26, the sled motor gain is set higher than the reference gain (step 27). If the track number N is 300 or less, the sled motor gain is set as the reference gain and reflected in the sled motor control (step 28).

As described above, the servo control method in the CD-ROM drive of the present invention detects an error in the track movement of the pickup due to disc eccentricity, and adjusts the gain of the sled motor based on it to reflect the servo control. Therefore, there is an advantage that the drive system can be stably operated even in the eccentric disk or the drive device causing the eccentricity.

1 is a schematic diagram of a general CO-ROM drive system.

2 is a flowchart showing the execution of the servo control method in the CD-ROM drive according to the present invention.

3 is a waveform diagram of a tracking error signal generated when playing an eccentric disc.

* Explanation of symbols for the main parts of the drawings

11 ... compact disc 12 ... spindle motor

12t ... turn table 13 ... pickup

14 ... sled drive shaft 15 ... microcomputer

16 ... DSP 17 ... SSP

18 ... ROM decoder 19 ... PC interface

Claims (3)

(a) driving the spindle motor at a predetermined speed when the disk is seated on the turntable; (b) turning off the tracking servo in the tracking on state by the drive of the spindle motor and maintaining only the focus mode; (c) detecting a tracking error signal in the state of step (b); (d) checking a first maximum track width point based on the detected tracking error signal; (e) determining whether a second maximum track width point is checked subsequent to the first maximum track width point; (f) returning the system flow to continue checking if the second maximum track width point is not checked in step (e), and if checked, the number of tracks between the first maximum track width point and the second maximum track width point ( Determining whether N) exceeds a predetermined reference track number; (g) setting the sled motor gain higher than the reference gain if the track number N exceeds the predetermined reference track number, and setting the sled motor gain as the reference gain if the track number N exceeds the predetermined reference track number. Servo control method for a CD-ROM drive, characterized in that. The method of claim 1, Servo control method in a CD-ROM drive, characterized in that the reference track number in the step (f) is set to 300. The method of claim 1, The increase in the sled motor gain in the step (g) is made in a multi-step according to the amount of eccentricity of the disk servo control method in a CD-ROM drive.