KR100267224B1 - servo apparatus and method for rotating playback with maximum multiple speed - Google Patents

Abstract

PURPOSE: Servo device and method for reproducing rotation at maximum speed are provided to reproduce a disk at the maximum speed of a PLL(Phase Locked Loop) and to vary reproducing speed of the disk for reducing data accessing time. CONSTITUTION: A 1/M divider(26) divides a clock from a correction oscillator(24) into 1/M for outputting to a phase compare unit(28). A 1/N divider(27) divides a clock from a VCO(Voltage Controlled Oscillator)(29) for outputting to the compare unit. The compare unit compares phases of the divided signals for outputting to a phase error to the VCO. The VCO outputs a clock according to the phase error. Herein, N and M of the dividers are decided in a microcomputer(24). The clock from the VCO is divided in a divider(30) for being outputted to a frequency error detect unit(31). The detect unit receives a WFCK signal from a synchronization detect unit(23), the clock from the VCO, and a divided clock from the divider for outputting a frequency error of the WFCK to an LPF(Low Pass Filter)(32). The LPF low pass filters the frequency error of the WFCK signal. A drive unit(33) controls a spindle motor(21) according to the filtered signal.

Description

Servo apparatus and method for rotating playback with maximum multiple speed

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc reproducing system, and more particularly, to a maximum double speed reproducing rotary servo device corresponding to a wideband phase locked loop (PLL).

In general, an optical disc such as a compact disc (hereinafter referred to as a CD) or a digital video disc (hereinafter referred to as a DVD) records information by a series of pits formed in a track direction on an information recording surface. .

In other words, the optical disc records information in the length of the pit and the interval between the pit.

It has a length between 3T and 11T in the case of a CD and between 3T and 14T in the case of a DVD, depending on the information on the length of the pit and the interval between the pit.

The information signal expressed by the length of the pits and the interval between the pits is obtained by using the amount of light reflected from the recording surface of the optical disc after being irradiated by a single wavelength light source such as laser light.

In detail, when the laser light is irradiated onto the recording surface without a pit, most of the irradiated light is reflected by the recording surface to generate a large amount of reflected light. Only positive reflected light will be generated. At this time, the reflected light is converted into an electrical signal by the pickup device to become a read signal.

FIG. 1 is a block diagram illustrating the structure of an optical disc revolving rotation servo device according to the prior art, and the optical disc revolving rotation servo device shown in FIG. 1 is a spindle motor 11 generating power for rotation of an optical disc 10. And an optical pickup 12 for converting the reflected light by scanning a light beam to the optical disc 10 into an electrical signal and outputting the signal as an EFM (Eight-to-Fourteen Modulation) signal, and output from the optical pickup 12. The RFCK (dividing the frequency output from the crystal oscillator 14), the crystal oscillator 14 for generating a constant clock, and the crystal oscillator 14 for generating a WFCK (Write Frame Clock) which is a synchronization signal from the EFM signal. Read Frame Clock) A phase error detector for comparing the phase of the WFCK generated by the synchronization signal generator 13 with the phase of the RFCK output from the divider 15 by outputting the phase error of the two clocks. (16), WFCK generated by the synchronization signal generator 13 and The frequency error detector 17 outputs the frequency error of the two clocks by comparing the frequency of the RFCK output in the period 15, and the phase error and frequency error detector 17 output from the phase error detector 16. The seapin motor using an adder 18 that adds a frequency error, a low pass filter 19 for lowpass filtering the value added by the adder 18, and a signal filtered by the LPF 19 It consists of the drive part 20 which drives 11.

In the conventional optical disc revolving rotation servo device configured as described above, the method of recording information on the optical disc is a CLV (Constant Linear Velocity) method for recording information at a constant bit rate while the rotational speed of the optical disc 10 is changed according to the position of the track. Use

Therefore, when the information is written to the optical disk 10, since the constant linear velocity and frequency are written as the clock of the crystal oscillator 14 having a constant, the normal reproduction can be performed by using the constant crystal oscillator 14 clock and the constant linear velocity even when reading.

Referring to the operation of the conventional optical disk regeneration rotation servo device as described above, first, the optical pickup 12 scans the light beam to the optical disk 10 rotated by the spindle motor 11 to electrically transmit the light reflected from the optical disk 10 The EFM signal is converted to the signal and equalized, and output to the synchronization signal generator 13.

The synchronizing signal generator 13 generates a synchronizing signal WFCK from the input EFM signal, and the divider 15 divides a clock output constant from the crystal oscillator 14 to generate an RFCK.

In addition, the phase error detection unit 16 receives the WFCK output from the synchronization signal generation unit 13 and the RFCK output from the divider 15 and compares phases to add a phase error that becomes an error of a predetermined linear velocity. Output to (18).

The frequency error detector 17 receives the WFCK output from the synchronization signal generator 13 and the RFCK output from the divider 15, compares frequencies, and outputs a frequency error to the adder 18.

The frequency error is present to prevent the rotating servo system from becoming unstable when the phase error is 180 °.

The adder 18 adds a phase error and a frequency error to the LPF 19 and outputs the LPF 19 to the driving unit 20 for driving the spindle motor 11 by low pass filtering the added error. .

In other words, the conventional optical disc reproducing rotation servo device enables the normal reproduction of the disc by controlling the constant linear velocity after detecting the error and the frequency error of the synchronization signals WFCK and RFCK.

The optical disc revolving rotation servo device according to the prior art requires a constant linear speed control since the disc can be reproduced only when the synchronous signal WFCK maintains a constant frequency, and a constant time is required to accelerate the spindle motor to this constant linear speed. During the time, a problem arises in that disc normal playback is impossible.

Disclosure of Invention The present invention has been made to solve the above problems, and an object thereof is to provide a maximum double speed regenerative rotation servo device and method capable of reading disc information at a maximum rotation speed corresponding to a wideband PLL.

1 is a block diagram illustrating a configuration of an optical disk reproducing rotation servo device according to the prior art.

2 is a block diagram illustrating a configuration of a maximum double speed regenerative rotation servo device according to the present invention.

Explanation of symbols for main parts of the drawings

201: optical disk 21: spindle motor

22: optical pickup 23: synchronization generating unit

24: crystal oscillator 25: micom

26: 1 / M divider 27: 1 / N divider

28: phase comparison unit 29: VCO

30: divider 31: frequency error detection unit

32: LPF 33: drive unit

A feature of the maximum double speed regeneration rotary servo device according to the present invention is that the maximum double speed clock generation unit generates a clock at the maximum double speed allowed by the locking range of the PLL with respect to the current disc reproducing position, and the servo control unit synchronizes the signal of the signal that picked up the disc. And above maximum speed

It is to control the spindle motor for rotating the disk by detecting the frequency error of the signal generated by the clock generator.

In addition, a feature of the maximum double speed regeneration rotation servo method according to the present invention generates a clock at the maximum double speed allowed by the locking range of the PLL with respect to the current disc reproducing position, and a synchronization signal for the signal picked up from the disc and the maximum generated signal. It is to control the rotation of the optical disc by detecting the frequency error of the double speed clock.

Hereinafter, a maximum speed regenerative rotation servo device and method according to the present invention will be described with reference to the accompanying drawings.

2 is a block diagram illustrating a configuration of a maximum speed regenerative rotation servo device according to the present invention, wherein the maximum speed regenerative rotation servo device includes a spindle motor 21 for generating power for rotation of an optical disc 201, and In the optical pickup 22 for scanning the light beam to the optical disk 201 to convert the reflected light into an electrical signal and output as an EFM (Eight-to-Fourteen Modulation) signal, and the EFM signal output from the optical pickup 22 A microcomputer that outputs double speed information for each track of the optical disc 201, a synchronization signal generator 23 for generating a WFCK (Write Frame Clock), a crystal oscillator 24 for oscillating a predetermined clock, and an optical disk 201. 25), a 1 / M divider 26 which divides a predetermined frequency oscillated by the crystal oscillator 24 into M according to the double speed information output from the microcomputer 25, and outputs an input clock from the microcomputer 25. 1 / N divider 27 which dispenses with N according to the assigned speed information, and 1 / N A phase comparator 28 for comparing the phases of the clocks output from the period 26 and the 1 / N divider 27 and outputting a phase difference, and a clock according to the voltage with respect to the phase difference output from the phase comparator 28 VCO (Voltage Controlled Oscillator) 29 outputting a 1 / N divider 27, a divider 30 for dividing and outputting a clock output from the VCO 29, and an output from the divider 30. The frequency error detection unit 31 and the frequency error detection unit 31 detect the frequency of the WFCK using the frequencies of the clocks output from the WFCK and the VCO 29 output from the synchronization generator 23 according to the divided signal. A low pass filter (LPF) 32 for low-pass filtering the detected frequency error, and a drive unit 33 for driving the spindle motor 21 by using the signal filtered by the LPF (32).

Before describing the operation of the maximum double speed regenerative rotation servo device according to the present invention configured as described above, a method of recording information on the optical disc will be described.

In the method of recording information on an optical disc, the information is recorded at a constant bit rate while maintaining a constant rotation speed of the optical disc, and the CAV (Constant Angular Velocity) can reproduce data at the same rotation speed without distinguishing between the outer and inner tracks of the optical disc. CLV (CLV: Constant), which records information at a constant bit rate while the rotation speed of the optical disc is converted according to the method of track and track, and the rotation speed becomes faster toward the inner track direction. Linear Velocity).

In order to reproduce an optical disc on which information is recorded in the CLV method, the rotation speed of the inner and outer tracks of the optical disc must be different. This is to maintain a constant linear velocity, which means that the rotational speed on the inner track should be faster than on the outer track.

For example, in the case of a compact disc, the speed of rotating the optical disc in the playback device is about 500 rpm in the innermost track and about 200 rpm in the outermost track when the data is played back at standard speed. do.

Recently, CD-ROM discs play data at four times the standard, 4 times, 8 times, 10 times, 12 times, 16 times, 20 times, and 24 times higher than the standard, and 2 times and 3 times the standard for DVD-ROM. Techniques for reproducing at high speeds, such as times and times, have been developed.

For example, in case of 10x CD-ROM disc using CLV method, to read data at 10x speed (1500KB / Sec) constantly, optical disc is about 5000rpm at innermost track of optical disc and about 2000rpm at outermost track. It must be rotated.

At this time, when the pickup is moved from the outermost track of the optical disk to the innermost track in order to reproduce data from the outermost track of the optical disk, the rotation speed of the optical disk should be increased from 2000 rpm to 5000 rpm. do.

However, it takes considerable time to raise the optical disk to 5000 rpm, which is the target rotational speed, and data cannot be read during this time.

This means that in the state of accelerating the rotation speed, since the rotation speed of the optical disc is lower than the reference speed, data cannot be read out of the range of a phase locked loop (PLL) that detects a sync pulse of an accurate playback signal.

In order to solve this problem, recently, the PLL method can be used to look up the PLL when the disk rotation speed is slower or faster than the reference speed.

Referring to the operation of the maximum double speed regenerative rotation servo device of the present invention using such a wideband PLL method, first, the optical pickup 22 outputs an EFM signal which is disk information from the optical disc 201, and the synchronization generator 23 It receives the EFM channel and outputs the synchronization signal WFCK.

Meanwhile, the 1 / M divider 26 divides the clock generated by the crystal oscillator 24 into 1 / M and outputs it to the phase comparator 28, and the 1 / N divider 27 outputs the VCO 29. The oscillated clock is divided by 1 / N and output to the phase comparator 28.

The phase comparator 28 compares the phases of the signals divided by 1 / N and 1 / M to output a phase error to the VCO 29, and the VCO 29 outputs a clock according to the phase error.

Here, the N and M of the 1 / M divider 26 of the crystal oscillator 24 and the 1 / N divider 27 of the VCO 29 are determined by the microcomputer 25.

N and M are determined as values corresponding to the maximum double speed within the locking range of the PLL using the double speed information of the current track, that is, the locking range of the wideband PLL.

The clock output from the VCO 29 is divided by the divider 30 and output to the frequency error detector 31.

The frequency error detector 31 inputs the WFCK signal detected by the synchronization generator 23, the clock output from the VCO 29, and the divided clock output from the divider 30 to be detected by the synchronization generator 23. The frequency error of the generated WFCK signal is output to the LPF 32.

The LPF 32 low-pass filters the frequency error of the WFCK signal detected by the frequency error detection unit 31, and the driving unit 33 controls the spindle motor 21 in accordance with the filtered signal.

If this operation is described in detail, if the frequency of the clock output from the VCO (29) is called fsysclk, and the frequency of the clock output from the crystal oscillator 24 is called fxtal, fsysclk becomes (N / M) * fxtal, N and M for determining the fsysclk are set to the values corresponding to the maximum double speed within the locking range of the PLL using the information of the locking range of the wideband PLL in the microcomputer 25.

If the locking range of the PLL is + 50% of 8x speed, the disc can be played normally even if the disc is rotated up to 12x speed.

In consideration of the inertia of the disk rotation and the like, if the margin of about 10% is allowed, playback at 11 times speed is possible.

Therefore, if the frequency of the crystal oscillator 24 is 34 MHz based on 8 times speed, the 11 times speed sets the M and N values of the microcomputer 25 to 8 and 11, respectively, to generate (11/8) * 34 = 46.8MHz fsysclkFMF. .

The frequency error detection unit 31 counts one cycle of the synchronization signal WFCK output from the synchronization generator 23 as a clock having a fsysclk of 46.8 MHz output to the VCO 29 and a reference corresponding to one frame in the CD standard. This result is compared with 579 clocks, and the result is output with the frequency error of WFCK.

The frequency error detected by the frequency error detector 31 maintains a constant linear speed of the spindle motor 21.

That is, the maximum double speed regenerative rotation servo device and method of the present invention can read the information of the disc at the maximum speed by controlling the rotation servo up to the maximum double speed so as to correspond to the wideband PLL.

The maximum speed regenerative rotation servo device and method according to the present invention uses a VCO for a signal using constant crystal oscillation as a CLV corresponding to a wideband PLL, and sets a variable at a maximum speed allowed by the locking range of the PLL by using a microcomputer to set variables. In addition to reproducing, depending on the locking range of the PLL, discs can be replayed at any speed, resulting in the fastest data access time, and the linear speeds of each track can be used for CAV control.

Claims (4)

A reproducing synchronous signal detector for detecting a reproducing synchronous signal of a signal reproduced from the recording medium; A reference signal generator for generating a reference signal for reading the reproduction signal; A frequency divider for dividing the frequency of the reference signal output from the reference signal generator to the predetermined value for quick synchronization between the reference signal and the playback signal at the target position when the track is jumped from the current playback position; And a servo control unit which compares the reference signal divided by the divider with the reproducing synchronous signal and controls a motor for rotating the recording medium accordingly. The method of claim 1, wherein the predetermined value is And a frequency for maintaining the maximum value within a locking range of the PLL corresponding to the current playback position. Detecting a reproduction synchronous signal of a signal reproduced from the recording medium; Generating a reference signal for reading the reproduction signal; Dividing the frequency of the reference signal output from the reference signal generator by dividing the reference signal frequency into a predetermined value to quickly synchronize the reference signal with the reproduction signal at the target position when the track is jumped from the current reproduction position; And comparing the reference signal divided by the frequency divider with the reproduction synchronization signal, and controlling rotation of the recording medium accordingly. The method of claim 3, wherein the predetermined value is And the frequency of the reference signal is a value for maintaining a maximum value within a locking range of a PLL corresponding to a current playback position.

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