KR100595248B1 - Method for controlling write of phase-change optical disc - Google Patents

Abstract

SUMMARY OF THE INVENTION The present invention provides a method for eliminating offset of a midpoint error signal generated when data is written to an optical disc in an optical disc recording / reproducing apparatus employing a stepping motor as a sled and performing recording using a phase change. It is about. In particular, the present invention measures the offset of the midpoint error signal for the sled servo at the same time as the start of recording. Therefore, it is possible to improve the recording quality and to stabilize the sled servo during recording by eliminating the offset of the midpoint error signal that appears during the recording of the disc using the phase change.

Sled, Stepping Motor, Midpoint Error Signals

Description

Method for controlling write of phase-change optical disc

1 is a conceptual diagram of a general optical disc recording / reproducing apparatus

2 is a block diagram showing a feedback control process of a sled motor during normal normal playback

3 is a view showing an example of sled control by a midpoint error signal during normal normal playback;

4 is a configuration block diagram showing an example of generating a general center error signal

5 is a waveform diagram showing an example of laser power during data recording using a general phase change;

6 is a diagram illustrating a conventional example in which a sled malfunctions due to an offset difference of a midpoint error signal.

Fig. 7 is a flowchart in time showing an embodiment of a recording control method of a phase change type optical disc according to the present invention.

8 is an operation flowchart showing an embodiment of a recording control method for a phase change type optical disk according to the present invention.

9A shows an example of an eccentric disc.

9B is a diagram showing an example of distortion of an offset value according to a midpoint error signal monitoring period in an eccentric disc.

Explanation of symbols for main parts of the drawings

201: Optical pickup 202: Midpoint error signal generator

203: sled servo 204: sled motor

401: calculating unit 402: gain adjusting unit

403: offset compensation unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording / reproducing apparatus employing a stepping motor as a sled, and more particularly, to offset midpoint error signals generated during data recording on an optical disk for recording by using a phase change. It is about how to remove it.

An optical disc recording / reproducing apparatus for recording or reproducing data on an optical disc includes a tracking servo for controlling tracking of an optical disc, a focusing servo for controlling focusing, a spindle servo for controlling a spindle motor, and a sled for controlling sleds. It is composed of a sled servo, and the illustration of each servo is omitted in FIG.

That is, in the optical disk recording / reproducing apparatus of FIG. 1, the optical pickup causes the light beam focused on the objective lens to be placed on the signal track of the optical disk, and also collects the light reflected from the signal recording surface with the objective lens and then returns to the optical detector. Enter.

The photo detector includes a plurality of photo detection elements, and an electrical signal proportional to the amount of light obtained from each photo detection element is output to each servo.

The tracking servo detects a tracking error signal from the electrical signal of the optical pickup and drives the tracking actuator in the optical pickup according to the detected tracking error signal to move the objective lens of the optical pickup in the radial direction to position the beam. Modify and track a given track.

The focusing servo detects a focus error signal from the electrical signal of the optical pickup and moves the optical pickup up and down by driving a focus actuator in the optical pickup according to the detected focus error signal, so that the optical disk follows the vertical movement along with the rotation. Let the sun go down.

The spindle servo detects the rotational speed information of the disk with the RF signal detected from the electrical signal of the optical pickup and controls the spindle motor according to the detected rotational speed information to rotate the optical disk. That is, the spindle motor gives a rotational force to the spindle for the rotation of the disk, the spindle transmits the rotational force given by the spindle motor to the disk to rotate the disk at the desired speed.

On the other hand, when the whole optical pickup needs to be moved, the sled servo operates. In other words, the sled servo drives the optical pickup body directly in the desired direction by driving a sled motor.

)을 넘어서게 되면 슬레드 모터(204)를 움직여 대물 렌즈에 의한 광 스폿이 광 검출기의 중간에 있도록 유도한다.In this case, in an optical disk recording / reproducing apparatus employing a stepping motor to implement the sled servo, in the case where continuous recording generally occurs, as shown in FIG. 2, a center error (center error or lens position error) of the objective lens in the optical pickup. ) Signal. That is, the midpoint error signal generator 202 detects the midpoint error signal from the electrical signal of the optical pickup 201 and outputs the midpoint error signal to the sled servo 203, and the sled servo 203 outputs the midpoint error signal as shown in FIG. 3. Is a constant value (

), The sled motor 204 is moved to induce the light spot by the objective lens to be in the middle of the photo detector.

4 is a block diagram illustrating a general midpoint error signal detection circuit, and a push-pull method is mainly used.

If the optical detector is composed of four optical detection elements A, B, C, and D divided into two in the signal track direction and the radial direction of the optical disk as shown in FIG. The electrical signals A, B, C, and D output from the respective photodetecting elements of (A + B)-(C + D) are generated to generate a midpoint error signal, and then output to the gain adjusting unit 402. The gain adjusting unit 402 adjusts the gain of the midpoint error signal of the calculating unit 401 and outputs the gain to the offset compensating unit 403. The offset compensator 403 compensates the offset of the gain-adjusted midpoint error signal and outputs it to the sled servo 203.

That is, in the case of recording using phase change, recording is performed by using a pulse train as shown in FIG. 5. In the middle erase level, the shape of the previously recorded pit is eliminated and the actual recording pulse is removed. That is, a method of forming pits at the recording level is used.

At this time, since the frequency of the write pulse is relatively high, each error signal for various servos is produced by sampling and holding at a stable erase level. Similarly, the mid-point error signal for the sled servo is detected by sample & hold at the erase level, which is generally much larger than the read level or the bias level.

Therefore, when recording starts, the gain adjusting unit 402 adjusts the gain of the midpoint error signal obtained by A + B- (C + D) the electrical signals A, B, C, D sampled and held at the erase level. Lower to lead level. That is, when recording starts, the sled servo drives the sled motor with a mid-level error signal at the read level.

In this way, the gain value of the sled servo can be adjusted according to the magnitude of the erase level. However, in this case, as shown in FIG. 4, the offset value of the midpoint error signal must also be changed according to the gain value. However, if the offset value of the midpoint error signal is not measured in advance, there is no way to know. The offset value of the midpoint error signal is an offset caused by disc characteristics such as disc eccentricity, and is measured and stored in advance at an erase level at disc manufacture. Then, the offset compensator 403 compensates the offset of the midpoint error signal whose gain is adjusted by the gain adjuster 402 and outputs the result to the sled servo.

That is, the optical disk may be distorted 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 disc track 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, the disk rotates with eccentricity, so that the center axis of the motor and the center of these tracks are difficult to completely coincide. In other words, the original disc center and the track center are shifted. Therefore, it is difficult to read exactly the signal of the desired track, so control the eccentricity.

At this time, a difference occurs between the offset of the midpoint error signal at the read level and the offset of the midpoint error signal at the erase level.

However, since the gain adjusting unit 402 adjusts the gain to the read level, and the offset input to the offset compensating unit 403 is an offset measured at the erase level, a midpoint error signal is changed by the change of the offset value. The result is a phenomenon in which recording is performed with the objective lens biased to one side. In the case of the disc on which data is recorded, the quality of the recorded pit becomes poor, which causes difficulty in reproduction. In some cases, the offset value changes beyond the lens's operating range, causing the servo to fail during recording.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to eliminate the offset of the midpoint error signal according to the erasure level when recording data using phase change, whereby the objective lens is fixed at the intermediate point of the optical pickup. The present invention provides a recording control method of a phase change type optical disk that can be maintained in a stable manner.

The recording control method of the phase change type optical disk according to the present invention for achieving the above object,

(a) when recording data on the phase change type optical disk, determining whether the midpoint error signal is stable before the start of recording;

(b) holding the sled servo at the recording start time when it is determined that the midpoint error signal is stable in the step (a);

(c) monitoring the midpoint error signal for a preset monitoring time while the sled servo is held and outputting the level of the monitored midpoint error signal as an offset value of the midpoint error signal during recording; And

(d) starting the sled servo, starting data recording, and compensating the offset value of the midpoint error signal obtained in step (c) from the midpoint error signal detected during data recording to drive the sled motor; It is characterized by comprising.

In the step (c), the monitoring time is characterized in that the rotational speed of the optical disk in consideration of the eccentricity.

The step (d) is characterized in that if the offset-compensated midpoint error signal exceeds a certain value, the sled motor is controlled to maintain the objective lens constant at an intermediate point of the optical pickup.

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, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described as at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

According to the present invention, when recording on an optical disk using a phase change, for example, an optical disk such as a CD-RW, DVD-RW, DVD + RW, or DVD-RAM, it is necessary to confirm whether the midpoint error signal is stable before starting the recording. In this case, it is characterized by holding the sled for a predetermined time at the same time as the start of recording and using the average level value of the midpoint error signal calculated during the interval as an offset of the midpoint error signal during data recording.

7 is a flowchart illustrating a recording control method of a phase change type optical disk according to the present invention, and FIG. 8 is an operation flowchart of a recording control method of a phase change type optical recording medium according to the present invention.

In other words, if a seek occurs immediately to the position to be recorded, there is a possibility of lens skew due to a track jump. Therefore, the seek point is first stabilized before the position to be recorded.

For example, as shown in Fig. 7, the seek is performed to the target position before the recording start time (step 801). After detecting the midpoint error signal (step 802), it is checked whether the detected midpoint error signal is stable (step 803). If it is not stable, seek again to the other target position before the start of recording to ensure that the midpoint error signal is stable. The above process is repeated until the midpoint error signal is stable.

If it is determined in step 803 that the midpoint error signal is stable, the sled is held at the start of recording and the midpoint error signal is monitored. At this time, exit from firmware so that the host can continue to receive commands.

In other words, when it is determined that the midpoint error signal is stable, it waits for the start of recording, and when it reaches the start time of recording (step 804), it is determined whether the offset of the midpoint error signal has already been calculated (step 805). If not already calculated, the sled is held (step 806) and the midpoint error signal is monitored for a preset monitoring time. After the monitoring time passes, the average level of the monitored midpoint error signal is measured and used as an offset of the midpoint error signal during recording (steps 807 and 808). The offset of the midpoint error signal is output to the offset compensator 403 of FIG. 4.

 That is, when it is determined in step 808 that the offset calculation of the midpoint error signal is completed, the sled servo is started (step 809). The sled servo then monitors the recording state by controlling the sled with the midpoint error signal that compensates for the offset of the midpoint error signal obtained in step 807 (step 810).

In general, there are two methods of recording: Constant Linear Velocity (CLV) recording and Constant Angle Velocity (CAV) recording. In the case of CLV recording, the RPM varies depending on the disc position. In addition, when the disk has an eccentric component, as shown in FIG. 9B, a sine wave form forms a monitoring time. However, in the case of CLV recording, since the RPM is changed as described above, the monitoring during the absolute time Tn may be measured with an incorrect offset value.

Therefore, in the present invention, the monitoring time Tm is set to the number of revolutions of the disk in consideration of the eccentric component of the disk as shown in FIG. 9A.

In this way, as shown in FIG. 9B, an offset error due to monitoring during absolute time can be eliminated. In FIG. 9B, it can be seen that there is a difference between the offset value monitored for the time indicated by Tn and the offset value monitored for the Tm time.

On the other hand, the terms used in the present invention (terminology) are terms defined in consideration of the functions in the present invention may vary according to the intention or practice of those skilled in the art, the definitions are the overall contents of the present invention It should be based on.

In addition, since the present invention has been described through the preferred embodiment of the present invention, in view of the technical difficulty aspects of the present invention, those having ordinary skill in the art can easily and other embodiments of the present invention. Other variations can be made. Therefore, it is apparent that all of the embodiments and variations cited in the above description belong to the claims of the present invention.

As described above, according to the recording control method of the phase change type optical disk according to the present invention, by confirming that the midpoint error signal is stable before starting the recording, by measuring the offset of the midpoint error signal for the sled servo at the same time as the recording start. In addition, by eliminating the offset of the midpoint error signal that appears during recording of the disc using phase change, the recording quality can be improved and the sled servo during recording can be stabilized. In other words, by eliminating the offset of the midpoint error signal according to the erasure level when recording data using phase change, the objective lens can be kept constant at the midpoint of the optical pickup, eliminating the recording failure due to the servo failure during recording. In addition, the quality of the recorded data can be improved to improve the ability to reproduce after recording.

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 (5)

In the recording control method of a phase change type optical disk including a sled servo that drives a sled motor to transfer an entire optical pickup by a midpoint error signal of an objective lens in the optical pickup, (a) holding the sled servo at the start of recording; (b) monitoring a midpoint error signal for a preset monitoring time while the sled servo is held, and then outputting the average level of the monitored midpoint error signal as an offset value of the midpoint error signal during recording; And (c) starting the sled servo and starting data recording, and driving the sled motor with an offset value of the midpoint error signal output in step (b). Record control method. The method of claim 1, wherein before performing step (a), Performing data seek to a target position before the start of recording and detecting a midpoint error signal when recording data on a phase change type optical disk; And repeating the detection of the midpoint error signal after performing seek to another target position before the start of recording, and determining whether the midpoint error signal is stable, to determine the presence or absence of a lens skew phenomenon. Recording control method for a phase change optical disk. The method of claim 1, And (b) the preset monitoring time is set to the number of rotations of the optical disk in consideration of the eccentricity. The method of claim 1, And (b) the offset value of the midpoint error signal is determined as an average level value of the midpoint error signal measured during a preset monitoring time. The method of claim 1, wherein step (c) The method of controlling recording of a phase change type optical disc, characterized in that when the offset-compensated midpoint error signal exceeds a predetermined value, the sled motor is controlled to keep the objective lens constant at an intermediate point of the optical pickup.

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