Phase locked loop circuit, reproduction apparatus and phase locking method

A reproduction apparatus which drives a disk type recording medium, on which run length limited codes are recorded in advance, to rotate at a constant linear velocity, comprising:

• a reproduction means for reproducing the run length limited codes from the disk type recording medium;
• a reference signal generation means for generating a reference signal having a predetermined frequency;
• a first counting means for counting a frequency of an output clock of voltage controlled oscillation means based on the reference signal generated by said reference signal generation means;
• a second counting means for counting a frequency of the run length limited codes reproduced by said reproduction means based on the reference signal generated by said reference signal generation means;
• a calculation means for calculating difference information between the frequency of the output clock of said voltage controlled oscillation means counted by said first counting means and the frequency of the run length limited codes counted by said second counting means;
• an extraction means for extracting a phase error low frequency component between the output clock of said voltage controlled oscillation means and the run length limited codes reproduced by said reproduction means;
• a change-over means for selectively changing over between the phase error low frequency component supplied from said extraction means and the difference information supplied from said calculation means;
• an integration means for integrating an output of said change-over means;
• a phase comparison means for performing phase comparison between the output clock of said voltage controlled oscillation means and the frequency of the run length limited codes reproduced by said reproduction means and outputting phase comparison information;
• an addition means for adding an integration output of said integration means and the phase comparison information from said phase comparison means to produce an oscillation control signal and outputting the oscillation control signal to said voltage controlled oscillation means;
• a lock discrimination means for discriminating whether or not a phase locked loop is locked;
• and
• a change-over control means for controlling such that, when it is discriminated by said lock discrimination means that said phase locked loop is locked, the phase error low frequency component supplied from said extraction means is selected so as to be inputted to said integration circuit, or when it is discriminated by said lock discrimination means that said phase locked loop is not locked, the difference information supplied from said calculation means is selected so as to be inputted to said integration circuit.

A phase locking method for driving a disk type recording medium, on which run length limited codes are recorded in advance, to rotate at a constant linear velocity, comprising the steps of:

• counting a frequency of an output clock of a voltage controlled oscillation circuit based on a reference signal having a predetermined frequency;
• counting a frequency of the run length limited codes based on the reference signal;
• calculating difference information between the counted frequency of the output clock of said voltage controlled oscillation circuit and the counted frequency of the run length limited codes;
• extracting a phase error low frequency component between the output clock of said voltage controlled oscillation circuit and the run length limited codes;
• selecting between the extracted phase error low frequency component and the calculated difference information and integrating the selected one of the extracted phase error low frequency component and the calculated difference information;
• performing phase comparison between the output clock of said voltage controlled oscillation circuit and the frequency of the run length limited codes to produce phase comparison information;
• adding the integrated output signal and the phase comparison information to produce an oscillation control signal;
• and
• discriminating whether or not a phase locked loop is locked and selecting, when it is discriminated that said phase locked loop is locked, the extracted phase error low frequency component so as to be integrated by the integrating step, or selecting, when it is discriminated that said phase locked loop is not locked, the calculated difference information so as to be integrated by the integrating step.

A reproduction method which drives a disk type recording medium, on which run length limited codes are recorded in advance, to rotate at a constant linear velocity, comprising the steps of:

• reproducing the run length limited codes from the disk type recording medium;
• generating a reference signal having a predetermined frequency;
• counting a frequency of an output clock of a voltage controlled oscillator based on the reference signal;
• counting a frequency of the reproduced run length limited codes based on the reference signal;
• calculating difference information between the counted frequency of the output clock of said voltage controlled oscillator and the counted frequency of the run length limited codes;
• extracting a phase error low frequency component between the output clock and the reproduced run length limited codes;
• selectively changing over between the phase error low frequency component and the difference information;
• integrating the selected one of the phase error low frequency component and the difference information;
• performing phase comparison between the output clock and the frequency of the reproduced run length limited codes and outputting phase comparison information;
• adding the integration and the phase comparison information to produce an oscillation control signal and outputting the oscillation control signal to said voltage controlled oscillator;
• discriminating whether or not a phase locked loop is locked;
• and
• controlling the step of selectively changing over such that, when it is discriminated by said lock said phase locked loop is locked, the phase error low frequency component is selected so as to be integrated, or when it is discriminated that said phase locked loop is not locked, the difference information supplied is selected so as to be integrated.

A phase locked loop circuit, comprising:

• a reference signal generator for generating a reference signal having a predetermined frequency;
• a first counter for counting a frequency of an output clock of a voltage controlled oscillator based on the reference signal generated by said reference signal generator;
• a second counter for counting a frequency of inputted run length limited codes based on the reference signal generated by said reference signal generator;
• a calculator for calculating difference information between the frequency of the output clock of said voltage controlled oscillator counted by said first counter and the frequency of the run length limited codes counted by said second counter;
• a filter for extracting a phase error low frequency component between the output clock of said voltage controlled oscillator and the inputted run length limited codes;
• a switch for selectively changing over between the phase error low frequency component supplied from said filter and the difference information supplied from said calculator;
• an integrator for integrating an output of said switch;
• a phase comparator for performing phase comparison between the output clock of said voltage controlled oscillator and the frequency of the inputted run length limited codes and outputting phase comparison information;
• an adder for adding an integration output of said integrator and the phase comparison information from said phase comparator to produce an oscillation control signal and outputting the oscillation control signal to said voltage controlled oscillator;
• a lock discriminator for discriminating whether or not a phase locked loop is locked;
• and
• a switch controller for controlling such that, when it is discriminated by said lock discriminator that said phase locked loop is locked, the phase error low frequency component supplied from said filter is selected so as to be inputted to said integration circuit, or when it is discriminated by said lock discriminator that said phase locked loop is not locked, the difference information supplied from said calculator is selected so as to be inputted to said integration circuit.

A reproduction apparatus which drives a disk type recording medium, on which run length limited codes are recorded in advance, to rotate at a constant linear velocity, comprising:

• a reproducer for reproducing the run length limited codes from the disk type recording medium;
• a reference signal generator for generating a reference signal having a predetermined frequency;
• a first counter for counting a frequency of an output clock of a voltage controlled oscillator based on the reference signal generated by said reference signal generator;
• a second counter for counting a frequency of the run length limited codes reproduced by said reproducer based on the reference signal generated by said reference signal generator;
• a calculator for calculating difference information between the frequency of the output clock of said voltage controlled oscillator counted by said first counter and the frequency of the run length limited codes counted by said second counter;
• a filter for extracting a phase error low frequency component between the output clock of said voltage controlled oscillator and the run length limited codes reproduced by said reproducer;
• a switch for selectively changing over between the phase error low frequency component supplied from said filter and the difference information supplied from said calculator;
• an integrator for integrating an output of said switch;
• a phase comparator for performing phase comparison between the output clock of said voltage controlled oscillator and the frequency of the run length limited codes reproduced by said reproducer and outputting phase comparison information;
• an adder for adding an integration output of said integrator and the phase comparison information from said phase comparator to produce an oscillation control signal and outputting the oscillation control signal to said voltage controlled oscillator;
• a lock discriminator for discriminating whether or not a phase locked loop is locked;
• and
• a switch controller for controlling such that, when it is discriminated by said lock discriminator that said phase locked loop is locked, the phase error low frequency component supplied from said filter is selected so as to be inputted to said integration circuit, or when it is discriminated by said lock discriminator that said phase locked loop is not locked, the difference information supplied from said calculator is selected so as to be inputted to said integration circuit.