KR100240333B1 - Digital phase locked loop device of an optical disc system - Google Patents

Abstract

The present invention relates to a digital phase synchronizer of an optical disc system, comprising: a first phase comparator (200) for comparing a phase of a standardized pulse signal with a predetermined feedback signal and detecting and outputting a phase difference thereof; A loop filter 220 that selects and counts a counter according to a phase difference signal provided from the first phase comparator 200 and outputs a carry CA or a borough BO signal; A microcomputer 210 generating a control signal to the loop filter 220 and setting a count size value according to the phase difference signal provided from the first phase comparator 200; A second phase comparator 230 for detecting a phase difference between the shaped pulse signal and a predetermined reference frequency signal; A low pass filter 240 for detecting a high frequency noise component from an output signal of the second phase comparator 230; An analog voltage controlled oscillator (VCO) 250 for generating a reference frequency signal corresponding to the phase difference signal of the second phase comparator 230 in which the noise component is removed from the low pass filter 240; A digital VCO 260 generating a clock signal having a predetermined frequency by increasing or decreasing the frequency of the reference frequency signal provided from the analog VCO 250 according to the output signal of the loop filter 220; And a divider 270 which divides the output signal of the digital VCO 260 at a predetermined division ratio and provides the divided clock signal to the data determination unit 50 as a synchronization signal for data determination.

Description

Digital Phase Synchronizer in Optical Disc System

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital phase synchronization device of an optical disc system, and more particularly, to continuously control a reference frequency signal in performing digital phase synchronization in an optical disc system, thereby improving the waveform of the synchronization signal and achieving phase synchronization more quickly. A digital phase synchronizer in an optical disc system.

With the development of audio and video media, optical disc systems have been developed for recording and reproducing video and audio data on semi-permanent optical discs.

Such an optical disc system reproduces an image and / or an audio recorded on an optical disc and outputs it through a screen and / or a speaker, and has a higher signal-to-noise ratio than conventional image and / or audio reproducing apparatus, resulting in better image quality and / or Or it can reproduce the signal with sound quality, it does not generate noise due to irregular reproduction and modulation, very low distortion, no ghost and random access, so it is rapidly developed and widely distributed. There is a trend.

Such optical disk systems also include compact disk players (CDPs), laser disk players (LDPs), compact disk graphic players (CDGPs), and video compact disk players (VCDPs). video compact disk player) has been developed and widely used. Also, recently, a digital video disk (DVD) using MPEG-2 moving picture compression technology and a digital video disk player for playing the same have been developed. It can record and play back gigabytes (GB) of data including moving images on a 12cm optical disc such as a CD, and it is also designed to be compatible to play current CDs and VCDs.

1 is a schematic block diagram of an optical disk system as described above.

As shown in FIG. 1, a general optical disc system includes an optical pickup unit 10, an amplifier unit 20, a waveform equalizing unit 30, a waveform shaping unit 40, a data discriminating unit 50, and a decoder 60. And a digital phase synchronizer 100.

The optical pickup unit 10 performs optical pickup on a predetermined disk chucked from a disk tray (not shown) and outputs the light reflected and picked up on the disk as an RF (radio frequency) signal. Then, the amplifier unit 20 amplifies the RF signal provided from the optical pickup unit 10 to a predetermined level and provides it to the waveform equalizer 30.

Accordingly, the waveform equalizing unit 30 modifies the waveform of the RF signal amplified by the amplifier unit 20 to a predetermined level, thereby making the interference between the waveforms small and increasing the density, and then providing the waveform to the waveform shaping unit 40. The waveform shaping unit 40 then transforms the output signal of the waveform equalizing unit 30 into a pulse signal, and provides the converted pulse signal to the data discriminating unit 50.

Then, the data determination unit 50 determines the presence or absence of the reproduction pulse in the preset detection window. That is, the pulse signal shaped in the detection window is identified as '0' or '1' and output to the decoder 60 as a code string. Then, the decoder 60 decodes the output signal of the data determination unit 50 and outputs it as a data bit string so that the video and audio signals can be processed later.

On the other hand, in order to determine the pulse signal shaped by the data determination unit 50 as '0' or '1', an apparatus for generating a synchronization signal every basic period of the recording code is required. As shown in FIG. A general optical disk system includes a digital phase synchronizer 100. That is, the digital phase synchronizer synchronizes an RF signal and an output signal of an oscillator (not shown) to convert the RF signal passing through the waveform equalizer 30 and the waveform shaper 40 into a digital signal, and input signal. Noise reduction, and extracts the reference clock from the input signal.

On the other hand, in performing the digital phase synchronization for data determination, the digital phase synchronization of the optical disk system is made to adaptively control the digital phase synchronization according to the magnitude of the phase error so that the synchronization time is increased and the pulse width of the synchronization signal is uniform. The device has been filed by the applicant with the application number Korean Patent No. FIG. 3 is a block diagram of a digital phase synchronizing apparatus of an optical disk system filed by the present applicant in Korean Patent No.

As shown in Fig. 3, the above-described digital phase synchronization device of the conventional optical disk system performs optical pickup for a predetermined disk and outputs the light reflected and picked up on the disk as an RF (radio frequency) signal. The waveform is corrected by modifying the waveform of the unit 10, the amplifier unit 20 that amplifies the RF signal provided from the optical pickup unit 10 to a predetermined level, and the RF signal amplified to the predetermined level by the amplifier unit 200. Waveform equalization unit 30 to reduce the interference between the high density and the waveform equalizer 30, the waveform shaper 40 for shaping and outputting the output signal of the waveform equalizer 30 to a pulse signal, and the waveform shaping unit 40 A data discrimination unit 50 for determining the presence or absence of a pulse in a predetermined detection window based on the output signal of the data stream, and outputting the data signal as a data bit string by decoding the output signal from the data determination unit 50. Decoder In the optical disc system including the optical disc system 60, the optical disc for providing data for phase discrimination in the data discriminating unit 50 to the data discriminating unit 50 so that data discrimination can be performed. 1. A digital phase synchronizer of a disk system, comprising: a phase comparator (300) for comparing a phase of a shaped pulse signal provided from the waveform shaping section (40) with a predetermined feedback signal and detecting and outputting a phase difference thereof; (up counter) and down counter (down counter), and selects and counts one of the up counter and the down counter according to the phase difference signal provided from the phase comparator 300 to carry (CA) or borough (BO) A loop filter 310 for outputting a signal, and a plurality of reference frequency generators each generating one preset reference frequency signal, The reference frequency generating unit 330 for generating a frequency signal; a multiplexer for selecting and outputting one of the reference frequency signal of the reference frequency signal provided from the reference frequency generator 330 (MUX: 340) and; Digital voltage control for generating a clock signal having a predetermined frequency by increasing or decreasing the frequency of the reference frequency signal provided from the reference frequency generator 330 through the MUX 340 according to the output signal of the loop filter 310. An oscillator (VCO) 350; According to the phase difference signal provided from the phase comparator 300, a control signal is generated by the loop filter 310 to set count magnitude values of the up counter and down counter, and to generate a selection control signal to the MUX 340. A microcomputer 320 for the MUX 340 to select one reference frequency signal among the reference frequency signals output from the reference frequency generator 330 and to provide it to the digital VCO 350; The output signal of the digital VCO 350 is divided at a predetermined division ratio and provided to the data determination unit 50 as a synchronization signal for data determination, and the divided clock signal is used as the predetermined feedback signal. And includes a divider 360 that provides a comparator 300.

However, the phase synchronizer in the conventional optical disk system as described above can control the reference frequency of the digital VCO in several stages, but since the clock of the reference frequency signal is divided into stages, There was an unstable factor, and the digital VCO output waveform also had the problem of not being smoothed.

Accordingly, the present invention has been made to solve such a problem in the prior art, and an object of the present invention is to continuously control the frequency of the reference frequency signal of the digital VCO to improve the output waveform and response speed of the digital VCO. It is to provide a digital phase control device of a disk system.

According to a preferred embodiment of the present invention for achieving this object, an optical pickup for outputting the light picked up and reflected on the disk as a radio frequency (RF) signal by performing optical pickup for a predetermined disk, and the optical pickup An amplifier for amplifying the RF signal provided from the unit to a predetermined level, a waveform equalizer for reducing the density of the interference between waveforms by increasing the density of the RF signal amplified by the amplifier by a predetermined level, and outputting the waveform equalizer. A waveform shaping unit for shaping a signal, converting the signal into a pulse signal, and outputting the pulse signal; a data discriminating unit for determining the presence or absence of a reproduction pulse in a predetermined detection window based on the output signal of the waveform shaping unit; In the optical disk system including a decoder for decoding the output signal of the determination unit and outputs as a data bit string, A digital phase synchronizer of an optical disk system for providing a phase synchronizing signal for data discrimination in the other determining unit to the data discriminating unit so that data discrimination can be performed smoothly. A phase difference signal provided from the first phase comparator, comprising a first phase comparator configured to compare a phase of a signal with a predetermined feedback signal, and detect and output a phase difference thereof; an up counter and a down counter; A loop filter for selecting and counting one of the up counter and the down counter and outputting a carry (CA) or borough (BO) signal to the loop filter according to the phase difference signal provided from the first phase comparator My to generate a control signal to set the count size value of the up counter and down counter A second phase comparator for detecting a phase difference between the shaped pulse signal provided from the waveform shaping unit and a predetermined reference frequency signal, a low pass filter for detecting a high frequency noise component from an output signal of the second phase comparator; And generating a reference frequency signal corresponding to the phase difference signal of the second phase comparator from which the noise component is removed from the low pass filter, and providing the reference frequency signal as the predetermined reference frequency signal to the second phase comparator. A digital VCO generating a clock signal having a predetermined frequency by increasing or decreasing a frequency of a reference frequency signal provided from the analog VCO according to a voltage controlled oscillator (VCO) and an output signal of the loop filter, and an output signal of the digital VCO. Is divided by the preset division ratio to determine the divided clock signal. And a divider which provides a pre-signal to the data discriminating unit and provides the divided clock signal as the predetermined feedback signal to the first phase comparator.

1 is a schematic block diagram showing a general optical disk system;

2 is a block diagram showing a digital phase synchronization device of an optical disk system according to a preferred embodiment of the present invention;

3 is a block diagram showing a digital phase synchronization device of a conventional optical disk system.

* Description of the symbols for the main parts of the drawings *

200,230: phase comparator 210: microcomputer

220: loop filter 240: LPF

250: Analog VCO 260: Digital VCO

270: frequency divider

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

2 is a block diagram illustrating a digital phase synchronization device of an optical disk system according to a preferred embodiment of the present invention.

As shown in FIG. 2, the digital phase synchronizer according to the present invention includes first and second phase comparators 200 and 230, a loop filter 220, a microcomputer 210, a low pass filter (LPF: 240), and analog voltage control. And include a voltage controlled oscillator (VCO) 250, a digital VCO 260, and a divider 270.

The first phase comparator 200 compares a phase of a shaped pulse signal provided from the waveform shaping unit 40 with a predetermined feedback signal, that is, a phase of a synchronization signal fed back from the digital VCO 260 through the divider 270. The phase difference is detected and output to the loop filter 220.

The loop filter 220 includes an up counter and a down counter. The loop filter 220 includes an up counter and a down counter. The loop filter 220 is configured in accordance with a phase difference signal provided from the first phase comparator 200 to the input terminal D / U (down / up). Selecting and driving one of the counter and the down counter causes one counter to perform a count, and outputs a carry CA or bore BO signal accordingly to the digital VCO 260. That is, in detail, the loop filter 310 outputs CA and BO by driving one counter according to the driving clock signal provided to the clock input terminal CLK and the output signal of the first phase comparator 200. The CA signal is provided to the input terminal INCR of the digital VCO 260, and the BO signal is provided to the input terminal DECR.

In addition, the count size of the up counter and the down counter constituting the loop filter 220, that is, the count value is determined according to the control signal of the microcomputer 320 based on the phase difference signal of the first phase comparator 200 as described below. Is determined. That is, the microcomputer 210 generates a control signal to the loop filter 220 according to the phase difference signal provided from the first phase comparator 200 to adaptively set count values of the up counter and the down counter.

In other words, if the phase difference signal, which is the output signal of the phase comparator 200, is large, the microcomputer 210 may follow the phase difference quickly by decreasing the count value of each counter of the loop filter 220, and if the phase difference is almost '0'. The counter's count is increased so that it is adaptively controlled so as not to be affected by noise.

Meanwhile, the second phase comparator 230 compares the phase of the standardized pulse signal provided from the waveform shaping unit 50 with the reference frequency signal fed back from the analog VCO 250 and outputs the phase difference signal to the LPF 240. The LPF 240 removes the high frequency noise component from the phase difference signal provided from the second phase comparator 230 and provides it to the analog VCO 250.

On the other hand, by providing a reference frequency to the analog VCO 250 digital VCO 350, the reference frequency continuously changing in accordance with the phase difference signal of the second phase comparator 230 from which the high frequency noise component is removed from the LPF 240 A signal is generated to the digital VCO 260, and the reference frequency signal is fed back as a reference signal of the second phase comparator 230, so that the second phase comparator 230 receives the reference frequency signal and the waveform shaper 50. The phase difference of the output signal can be obtained.

When the reference frequency signal is provided from the analog VCO 250, the digital VCO 260 according to the reference is based on the output signal of the loop filter 220 whose magnitude of the count value is determined according to the control of the microcomputer 210. The frequency of the frequency signal is increased or decreased to provide a clock signal of a predetermined frequency to the divider 360. In other words, when the CA signal is input to the input terminal INCR, the digital VCO 260 increases the frequency by generating a half cycle clock in a predetermined pulse period of the reference frequency signal provided from the analog VCO 250. When the BO signal is provided to the input terminal DECR, the frequency is reduced to the frequency of the pulse by reducing the number of pulses by deleting the half cycle pulse within a predetermined pulse period of the reference clock signal.

Then, the divider 270 divides the output signal of the digital VCO 260 at a predetermined division ratio, and provides the divided signal to the data determination unit 50 as a synchronization signal for data determination, and feeds back the divided clock signal. The signal is provided to the first phase comparator 200 so that feedback control is performed.

As described above, the present invention provides a reference frequency signal of a digital VCO by using an analog VCO in performing digital phase synchronization for data determination in an optical disk system, thereby continuously controlling the frequency of the reference frequency signal to perform digital phase synchronization. This has the effect of improving the output waveform and response speed of the VCO.

Claims (1)

An optical pickup section 10 that performs optical pickup for a predetermined disk and outputs the light reflected and picked up on the disk as a radio frequency (RF) signal; and an RF signal provided from the optical pickup section 10 at a predetermined level. The waveform equalizer 30 for amplifying the amplifier unit 20 and the waveform of the RF signal amplified by the amplifier unit 200 at a predetermined level to reduce the interference between the waveforms and thereby increase the density, and the waveform equalizer 30. The waveform shaping unit 40 converts the output signal of the wave form into a pulse signal and outputs the pulse signal within the predetermined detection window based on the output signal of the waveform shaping unit 40. In the optical disc system comprising a data discriminating unit 50 for discriminating and a decoder 60 for decoding the output signal of the data discriminating unit 50 and outputting the data signal as a data bit string. Data determination In the digital phase-lock device of an optical disk system for allowing a subject to said phase-locked signal to provide a data discrimination unit 50 performs data discrimination Hi smoothly, A first phase comparator (200) for comparing the phase of the shaped pulse signal provided from the waveform shaping unit (40) with a predetermined feedback signal to detect and output a phase difference thereof; An up counter and a down counter are configured to select and count one of the up counter and the down counter according to the phase difference signal provided from the first phase comparator 200 to carry and carry a CA. Or a loop filter 220 for outputting a borough (BO) signal; A microcomputer (210) for generating a control signal to the loop filter (220) according to the phase difference signal provided from the first phase comparator (200) to set count magnitude values of the up counter and the down counter; A second phase comparator (230) for detecting a phase difference between the shaped pulse signal provided from the waveform shaping unit (40) and a predetermined reference frequency signal; A low pass filter 240 for detecting a high frequency noise component from an output signal of the second phase comparator 230; The low pass filter 240 generates a reference frequency signal corresponding to the phase difference signal of the second phase comparator 230 from which the noise component is removed, and uses the reference frequency signal as the predetermined reference frequency signal as the second phase. An analog voltage controlled oscillator (VCO) 250 provided to the comparator 230; A digital VCO 260 generating a clock signal having a predetermined frequency by increasing or decreasing the frequency of the reference frequency signal provided from the analog VCO 250 according to the output signal of the loop filter 220; The output signal of the digital VCO 260 is divided at a predetermined division ratio, and the divided clock signal is provided to the data determination unit 50 as a synchronization signal for data determination, and the divided clock signal is supplied to the predetermined feedback. Digital phase synchronizing device of an optical disk system including a divider (270) provided as a signal to the first phase comparator (200).

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