KR100521921B1 - Method and apparatus for measuring axial vibration of a disk - Google Patents

Abstract

The present invention relates to a method and apparatus for determining the surface vibration of a rotating disk in a disk apparatus, wherein the method for determining the surface vibration of the present invention comprises a predetermined interval (45 degrees to 120 degrees) on a circumference of an optical recording medium. Fig. 3), and perform a focusing operation at each of the selected positions, measure a focusing time from the start of each focusing operation to the correct focusing, and then measure the deviation of each measured focusing time. On the basis of this, the amount of surface vibration of the optical recording medium is detected. By this method, the amount of surface vibration of the rotating disk can be obtained accurately.

Description

Method and apparatus for discriminating the surface vibration of optical disk {Method and apparatus for measuring axial vibration of a disk}

The present invention relates to a method and apparatus for determining the surface vibration of a rotating disk in a disk device.

The optical disk device rotates an optical disk such as a CD or DVD inserted into the apparatus at a high speed by using a spindle motor, and performs focusing and tracking operations of the objective lens of the optical pickup to the optical disk. A reproduction operation of reading out and reproducing the signal recorded on the recording surface of the optical disc is performed.

During the reproducing operation, the servo operation is performed so that the signal is optimally read while adjusting the focusing and tracking of the objective lens according to the focusing error and the tracking error signal generated from the beam reflected from the disk.

However, when the optical disk rotated at a high speed by the spindle motor as described above vibrates up and down, that is, when the surface vibration component is present, focusing is not performed properly. Therefore, it is necessary to adjust the gain of the focusing servo to increase the sensitivity of the focusing.

In addition, when the surface vibration component is considerably large and tracking cannot be performed by gain adjustment of the focusing servo, since the normal regeneration operation is impossible at high speed, the rotational speed of the spindle motor must be slowed down or ejected.

For this reason, it is necessary to accurately measure the surface vibration of rotating disks.

The present invention has been made by the necessity as described above, and provides a method for accurately measuring the surface vibration component of an optical disk to be reproduced.

It is still another object of the present invention to provide a method for causing the focusing servo to be followed in correspondence with a disk having a surface vibration.

It is still another object of the present invention to provide a method of determining the surface vibration amplitude for each disk phase and subdividing and adjusting the focusing for each phase.

In accordance with an aspect of the present invention, there is provided a method for determining the surface vibration of an optical disc, wherein a point on which a focusing operation is to be performed is performed at a predetermined interval on a circumference of an optical recording medium, and the focusing operation is performed at each of the selected positions. And measuring the focusing time from the start of each focusing operation to the correct focusing, and then determining whether the optical recording medium is oscillated on the basis of the measured focusing time.

According to another aspect of the present invention, there is provided a method for determining the surface vibration of an optical disk, wherein the position of the optical recording medium on the circumference is checked, and when the identified position corresponds to each position on the predetermined circumference, the surface vibration is performed at that position. After the respective sizes are detected, when the optical recording medium is reproduced, the characteristics of the focusing servo may be adjusted to match the next position of the current reproduction position based on the magnitude of the surface vibration at each detected position.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the method for determining the surface vibration of an optical disk according to the present invention will be described in detail.

Fig. 1 shows a configuration of an optical disk apparatus to which the surface vibration discrimination method of the optical disk according to the present invention is applied.

1 includes an optical pickup 11 for reading out a signal recorded on an optical disc 10 such as a CD or DVD; The RF signal read by the optical pickup 11 is converted into a binary signal, and outputs a focus error (FE) signal, a tracking error (TE) signal, and accurate focusing from the RF signal. An RF unit 12 for outputting a FOK (Focusing OK) signal at a time point; A digital signal processor (13) for signal-processing the binary signal converted through the RF unit (12) and restoring the original data; A servo that performs a focusing operation and a tracking operation for moving an object lens provided in the optical pickup 11 up, down, left, and right based on a focusing error signal and a tracking error signal output from the RF unit 12. Part 14; A spindle motor (15) for rotating the optical disc (10) under the control of the servo unit (14); A sled motor (16) for horizontally moving the optical pickup (11) on the optical disc; A motor driver 17 for driving the spindle motor 15 and the sled motor 16; An FG signal generator 19 for outputting a pulse signal (hereinafter referred to as an 'FG signal') when the spindle motor 15 rotates; And a microcomputer 18 for determining the amount of surface vibration of the disk and controlling the focusing servo based on the focusing time in each phase of the disc.

FIG. 2 is an operation flowchart according to a preferred embodiment of the method for determining the surface vibration of an optical disk according to the present invention performed in the apparatus of FIG.

When the optical disk 10 is inserted and seated in the optical disk device configured as shown in FIG. 1, the microcomputer 18 operates the servo unit 14 to control the optical disk to be rotated by the spindle motor 15 (S10). Meanwhile, the objective lens provided in the optical pickup 11 is controlled to focus on the optical disk. At the same time, the pulses of the FG signal output from the FG signal generator 19 are counted (S11). The initial rotational speed of the disc is set to a low speed, and a speed at which three or more times of focusing can be repeatedly performed during at least one rotation of the disc is preferable.

Then, the time from the start of focusing to when the focus is completed and the FOK signal is output from the RF unit 12 (S12) is measured and stored through the internal timer (S13).

Then, it is judged from the number of pulses output from the FG signal generator 19 whether the disk has been completed one revolution (S14). If the FG signal generator 19 outputs six pulses during one revolution of the disc, it is checked whether the number of pulses counted is six.

If it is not six, since one rotation has not yet been made, the objective lens is returned to the corresponding focusing position (S15), and then the focusing operation is performed again (S16). The time interval for resuming the focusing operation is 1/3 of the time required for one revolution of the disc. That is, if one rotation period is T, the focusing interval that is performed again becomes the time elapsed T / 3 from the start of the previous execution. Instead of a predetermined time interval, the number of pulses may be checked for each pulse of the FG signal, and the focusing operation may be performed when the number is 1, 3, or 5.

After resuming focusing, the time until the FOK signal is output (S12) is measured and stored again (S13), and the above operation is performed until the disc is rotated once.

3 shows waveforms of related signals when the above process is performed.

When the disk is rotated once (S14), the microcomputer 18 calculates the deviation of the measured three times (T1, T2, T3 in Fig. 3) (S17). The magnitude of this deviation is the amount of surface vibration of the disk.

The microcomputer 18 increases the focusing servo gain of the servo unit 14 in proportion to the obtained surface vibration (variation magnitude), increases the sensitivity of the focusing servo by increasing the amplification of the FE signal, or lowers the playback speed lower than the maximum speed. The speed is set (S18). In this way, it is possible to maintain an accurate focusing distance with the recording surface of the disk which vibrates up and down when rotating at a high speed (or a speed lower than the maximum speed) for reproduction of the recording data.

If the obtained amount of surface vibration (deviation magnitude) is an unacceptable amount, the microcomputer 18 discharges the mounted disk 10 without adjusting the focusing servo.

In the embodiment of Fig. 2, the disk oscillation is measured in three parts. The measurement of the surface vibration amount can be more accurately measured by calculating the deviation of the focusing time by further subdividing the phase of the disk.

To get focusing time in more phases, the physical time required for focusing at a given low speed must be shortened, but this is a limitation.

4 is a flowchart of a method of measuring the surface vibration of a disc by obtaining the focusing time in many disc phases.

In this embodiment, it is assumed that eight pulses of the FG signal are output in one rotation of the disc. In addition, the microcomputer 18 has an interrupt routine performed every time a pulse input of the FG signal is performed.

This interrupt routine counts the number of pulses at every pulse input (S20) and the number of pulses is 8n, 8 (n + k) +1, 8 (n + 2 * k) +2, 8 (n + 3 * k) + Whenever 3, 8 (n + 4 * k) +4, 8 (n + 5 * k) +5, 8 (n + 6 * k) +6, 8 (n + 7 * k) +7 (S21 In step S22, the above-described focusing operation is performed and the focusing time obtained thereby is measured and stored. Where n is an arbitrary number and k represents a measurement rotation interval. That is, if k is set to 1, it is measured in the next phase after one revolution, and if k is 2, it is measured in the next phase after two revolutions of the disc. This approach eliminates the need to rotate the disk at a slow speed to measure the focusing time in each phase.

5 schematically shows the measurement interval when k is 2. Once measured, increase the number of measurements (S23), and measure repeatedly until the number of measurements is eight (S24).

If a predetermined number of times is measured, the deviation of each measured focusing time is obtained (S25). This deviation is indicative of the amount of surface vibration of the disk. According to the obtained amount of surface vibration (variation), the speed of the disk is lowered, the sensitivity of the focusing servo is adjusted (S26) or the disk is ejected, and the interrupt by the FG pulse is disabled (S27).

Instead of adjusting the focusing servo characteristics globally, they can be individually adapted and adjusted for each disc phase. To this end, the microcomputer 18, in addition to each focusing time measured in the above-described embodiment, displays the measured phase, that is, the number of pulses counted as 'the number of pulses of the FG signal outputted at one rotation of the disc' (FIG. In the embodiment 2, the remaining values divided by 6 and 8) in the embodiment of FIG. 4 are recorded together.

That is, the table shown in FIG. The average Tabg of each focusing time is obtained, and the difference 602 between each measurement time and the average value Tabg is obtained and recorded.

When the data reproduction operation is performed, the gain of the focusing servo is predicted and adjusted in advance for each phase according to the obtained difference value.

For example, if the DT _M value of the calculated difference value DTi is the smallest, the servo gain is slightly increased before moving from the M phase to the M + 1 phase to correspond to the surface vibration magnitude in the M + 1 phase. .

As mentioned above, preferred embodiments of the present invention are disclosed for the purpose of illustration, and those skilled in the art can improve and change various other embodiments within the spirit and technical scope of the present invention disclosed in the appended claims below. , Replacement or addition would be possible.

The surface vibration discriminating method of the optical disk according to the present invention as described above enables the signal to be reproduced without the focusing failure in the optical disk which is oscillating and prevents unnecessary playback attempts on the disk which cannot be reproduced by vertical vibration.

1 shows a configuration of an optical disk apparatus to which the method for determining the vibration of the surface of the optical disk according to the present invention is applied.

Figure 2 shows the flow of an embodiment of the surface vibration determination method of the optical disk according to the present invention,

3 illustrates an example in which a deviation occurs in focusing time in proportion to surface vibration.

Figure 4 shows the flow of another embodiment of the surface vibration determination method of the optical disk according to the present invention,

FIG. 5 illustrates a process of performing focusing on an optical disc according to the embodiment of FIG. 4.

6 is a diagram of an example of the time of focusing measured at each phase of an optical disc in accordance with the present invention.

※ Explanation of code for main part of drawing

10: optical disc 11: optical pickup

12: RF unit 13: digital signal processing unit

14: servo unit 15: spindle motor

16: sled motor 17: motor drive unit

18: microcomputer 19: FG signal generator

Claims (22)

Selecting a point at which a focusing operation is to be performed at a predetermined interval on the circumference of the optical record carrier; Performing a focusing operation at each of the selected positions; Measuring a focusing time from the start of each focusing operation to correct focusing; And And determining the surface vibration of the optical recording medium based on the measured time required for focusing. The method of claim 1, wherein the predetermined interval is an angle smaller than 120 degrees. The method of claim 1, wherein the step (3) determines whether to focus correctly based on a signal generated by the intensity of light reflected from the optical recording medium during each focusing operation. The method of claim 1, further comprising the step of setting the reproduction speed of the optical recording medium at a low speed according to the degree of surface vibration. The method of claim 1, further comprising: adjusting a characteristic of a focusing servo according to the degree of surface vibration. The method of claim 1, wherein the step (4) calculates the amount of surface vibration of the optical recording medium in proportion to the measured deviation of the focusing time. Performing a focusing operation at each position equal to n (n is 3 or more) on the circumference of the optical record carrier; And Measuring the time from the start of the focusing operation to the output of the focusing completion signal during each of the focusing operations, and determining the amount of surface vibration of the optical recording medium based on the measured time. Method for determining surface vibration of recording media. Rotating the mounted optical record carrier; Performing a focusing operation at respective positions equal to n (n is 3 or more) on the circumference of the optical recording medium during one rotation of the optical recording medium; A third step of detecting a time required from the start of a focusing operation to the output of a focusing completion signal during each focusing operation; And And detecting a surface vibration amount of the optical recording medium from the detected deviation of the focusing time. Rotating the mounted optical record carrier; During a rotation of the optical record carrier, performing a focusing operation at each position equal to n (n is three or more) on the circumference of the optical record carrier; Detecting the time from the start of the focusing operation to the output of the focusing completion signal during each focusing operation, and storing the focusing information together with information for identifying the focusing position; And And a fourth step of detecting the magnitude of the surface vibration at each position based on the stored information. 10. The method of claim 9, wherein each position identification information is a residual value obtained by dividing the number of pulses output during the rotation of the optical recording medium by the number of pulses output during one rotation. 10. The method of claim 9, wherein steps 2 and 3 are performed during one rotation of the optical recording medium. 12. The method of claim 11, wherein the rotation speed of the first step is lower than a reproduction speed for data reproduction of the optical recording medium. 10. The method of claim 9, wherein steps 2 and 3 perform focusing operations at only one position at the equal n positions during one rotation of the optical recording medium and detect a focusing completion time thereof. A method of determining the surface vibration of an optical record carrier. Confirming a circumferential position of the rotating optical record carrier; If the identified positions correspond to respective positions on a predetermined circumference, respectively detecting the magnitude of the surface vibration at the positions; And And during the reproduction of the optical recording medium, adjusting the characteristics of a focusing servo to match the next position of the current playback position based on the magnitude of the surface vibration at each detected position. Method for Discrimination of Surface Vibration 15. The method of claim 14, wherein the position is divided by a residual value obtained by dividing the number of pulses output during the rotation of the optical recording medium by the number of pulses output in one rotation. . Drive means for rotating the mounted optical record carrier; Servo / detecting means for performing a focusing operation on the optical recording medium rotated by the driving means and outputting a predetermined signal when correct focusing is performed; And On the circumference of the optical record carrier, a point for performing a focusing operation is selected at a predetermined interval, and the servo / detecting means is controlled to perform a focusing operation at each of the selected positions, and from the start of each focusing operation A surface of an optical recording medium comprising control means for measuring a time required from the servo / detection means to the predetermined signal output and determining whether the optical recording medium is vibrated on the basis of each measured time required Vibration discrimination device. delete 17. The apparatus of claim 16, wherein the predetermined interval is an angle smaller than 120 degrees. delete Drive means for rotating the mounted optical record carrier; Servo means for performing a focusing operation on the optical recording medium rotated by the driving means; And By controlling the servo means, the focusing operation is performed at each position equal to n (n is 3 or more) on the circumference of the optical recording medium, and the time required from the start of each focusing operation to the focusing completion signal output is measured. And control means for discriminating whether or not the optical recording medium is vibrated on the basis of the measured time required for the surface vibration of the optical recording medium. Drive means for rotating the mounted optical record carrier; An encoder for outputting a pulse signal of a predetermined period when the optical recording medium is rotated; Servo means for performing a focusing operation on the optical recording medium rotated by the driving means; And Check the circumferential position of the rotating optical recording medium based on the pulse signal of the encoder, and if the identified position corresponds to each position on a predetermined circumference, control the servo means to perform focusing. Characteristics of the focusing servo of the servo means for detecting the magnitude of the surface vibration at each position and then fitting the next position of the current playback position based on the magnitude of the surface vibration at each detected position during playback of the optical record carrier Apparatus for determining the vibration of the surface of the optical recording medium comprising a control means for adjusting the. 9. The method of claim 8, further comprising the step of adjusting a characteristic of a focusing servo in proportion to the detected surface vibration amount.