JP2005158239A - Optical disk apparatus, clock signal generation method, program, and control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk apparatus, a clock signal generation method, and a program, which detect a wobble signal from a reproduced signal of an optical disk and generate a clock signal in synchronism with the wobble signal, and a control apparatus for generating a clock signal. <P>SOLUTION: The optical disc apparatus is provided, which comprises a signal detection means for detecting a wobble signal from a reproduced signal of an optical disc, and a generation means for generating a clock signal in synchronization with the wobble signal. The generation means comprises: a first difference signal generation means for generating a first difference signal indicating a difference between a frequency of the wobble signal and a frequency of the clock signal; a period detection means for detecting a modulation period of the wobble signal based on the first difference signal; and an adjustment means for adjusting the frequency of the clock signal based on a predetermined signal other than the first difference signal during a modulation period, and for adjusting the frequency of the clock signal based on the first difference signal during a period other than the modulation period. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical disk apparatus that detects a wobble signal from a reproduction signal of an optical disk and generates a clock signal so as to be synchronized with the wobble signal, a clock signal generation method, a program, and a control apparatus for generating a clock signal.

  In many recordable optical disks, a recording groove for tracking control of the optical head is formed. When the recording groove is formed in a meandering manner on the optical disk, the rotation speed of the optical disk can be detected from the reproduction signal of the optical disk, a clock is generated based on the detected rotation speed, and the motor is controlled.

  Patent Document 1 discloses a technique related to an optical disc apparatus that reproduces digital information based on a single frequency of a recording groove formed on an optical disc. The reproduction signal of the optical disc includes a component (wobble signal) due to the meandering of the recording groove. This technique detects an error between the frequency of the wobble signal and the frequency of the reproduction clock (referred to as “channel clock”), and realizes the PLL synchronization operation. Furthermore, this technique adjusts the frequency of the wobble clock so that the recording clock (referred to as “wobble clock”) is synchronized with the wobble signal by the PLL.

  FIG. 14 shows a conventional wobble clock generation circuit 300 described in Patent Document 1.

  The wobble clock generation circuit 300 is configured to be able to insert the optical disc 1. The wobble clock generation circuit 300 includes an optical head 2, a preamplifier 3, a band pass filter 4, and a binarization circuit 5.

  The optical head 2 generates a light detection signal based on the reflected light reflected by the optical disc 1. The preamplifier 3 generates a tracking error signal (TE signal) and an RF signal by adding and subtracting the light detection signal. For example, when the optical head 2 includes a two-divided detector (including two detectors), the TE signal indicates the difference between the output of one detector of the two-divided detector and the output of the other detector, and the RF signal is The sum of the output of one detector of the two-divided detector and the output of the other detector is shown. The band pass filter 4 extracts a wobble signal from the TE signal. The binarization circuit 5 binarizes the wobble signal and generates a binarized signal.

  The wobble clock generation circuit 300 further includes a PLL circuit 10. The PLL circuit 10 includes a phase / frequency comparison circuit 6, a low pass filter (LPF) 7, a voltage controlled oscillator (VCO) 8, and a frequency divider 9.

  The phase / frequency comparison circuit 6 detects the phase difference between the phase of the binarized signal and the phase of the clock signal output from the dividing period 9. The LPF 7 limits the phase error signal indicating the detected phase difference to a necessary band, and controls the oscillation frequency of the VCO 8. The VCO 8 generates an N multiplied clock of the frequency of the wobble signal. The frequency divider 9 divides the N-multiplied clock by N to generate a clock signal.

  As described with reference to FIG. 14, the PLL circuit 10 generates a clock signal synchronized with a wobble signal having a single frequency.

  Patent Document 2 discloses in more detail a technique for generating a clock signal from a reproduction signal of an optical disc. In a form in which a signal is reproduced before the disk motor reaches a predetermined number of revolutions, or in a form in which a signal is reproduced at CAV (constant angular velocity) from a medium on which the signal is recorded at CLV (constant linear velocity), A circuit for effectively generating a clock using a modulator is described in detail.

  A technique for recording address information on an optical disc by modulating a wobble signal having a constant period is also common. Since it is not necessary to form pits on the optical disk in order to record address information on the optical disk, high format efficiency can be realized. The modulation of the wobble signal is, for example, frequency modulation and phase modulation.

  Patent Document 3 discloses a technique for recording address information on an optical disc by modulating the phase of a wobble signal having a constant period. Further, Non-Patent Document 1 discloses a technique for recording address information on an optical disc by performing MSK (Minimum Shift Keying) modulation of a wobble signal having a fixed period. On this optical disc, a wobble signal containing a frequency component of 1.5 times the fixed period is recorded. Address information is reproduced by detecting the modulation.

Patent Document 4 discloses a technique for superimposing a prepit signal component on a wobble signal by forming prepits with high reflectivity on an optical disk in synchronization with a continuous groove.
Japanese Patent Laid-Open No. 2000-100083 (FIG. 1) Japanese Patent No. 3323824 (FIGS. 11 and 14) Japanese Patent Laid-Open No. 10-69646 (FIG. 1) Japanese Patent Laid-Open No. 10-154332 (FIG. 1) Jung-Bae Park, et al. , "A New Address Decoder using Digital MSK Demonstration Technology for the HD-DVD System" Technical Digest of ISOM / ODS 2002, 2002. 114-116

  As described with reference to FIG. 14, the phase / frequency comparator 6 compares the phases of the output of the binarization circuit 5 and the output of the frequency divider 9, and the phase / frequency comparator 6 indicates a frequency error. A signal and a signal indicating a phase error are output. When address information is recorded on an optical disc by modulating the phase of a wobble signal with a fixed period or by modulating the frequency of a wobble signal with a fixed period, the reproduced wobble signal has a single frequency component. Includes frequency components other than. Therefore, the frequency error or phase error cannot be detected correctly based on the reproduced wobble signal. As a result, the jitter of the recovered clock signal is deteriorated. Further, when the reproduced clock signal is used as a recording clock, the accuracy of the mark position formed on the optical disk is deteriorated.

  The problem that the jitter of the regenerated clock signal is deteriorated can be solved by further providing the wobble clock generation circuit 300 with a bandpass filter having a sharp pass characteristic. This is because a band-pass filter having a sharp pass characteristic passes a clock signal having only a single frequency. However, since the wobble clock generation circuit 300 includes a bandpass filter for address detection, the scale of the wobble clock generation circuit 300 increases.

  The problem that the jitter of the recovered clock signal deteriorates can also be solved by lowering the pass band of the LPF 7. However, the response speed of the wobble clock generation circuit 300 becomes slow, and the access performance of the wobble clock generation circuit 300 deteriorates.

  The present invention has been made in view of the above problems, an optical disc apparatus that detects a wobble signal from a reproduction signal of an optical disc, and generates a clock signal so as to be synchronized with the wobble signal, a clock signal generation method, a program, and a clock An object is to provide a control device for generating a signal.

  An optical disc apparatus according to the present invention comprises signal detection means for detecting a wobble signal from a reproduction signal of an optical disc, and generation means for generating a clock signal so as to be synchronized with the wobble signal, wherein the generation means comprises the wobble signal First difference signal generating means for generating a first difference signal indicating a difference between the frequency of the clock signal and the frequency of the clock signal; and period detecting means for detecting a modulation period of the wobble signal based on the first difference signal; The frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal during the modulation period, and the frequency of the clock signal is adjusted based on the first difference signal during a period other than the modulation period. And adjusting means for adjusting the above, thereby achieving the above object.

  The adjusting means may adjust the frequency of the clock signal so that the value of the first difference signal is minimized during a period other than the modulation period.

  The generation unit generates a second difference signal indicating a difference between a phase of the wobble signal and a phase of the clock signal, and a determination unit that determines whether the value of the first difference signal is larger than a predetermined value. A second difference signal generating unit, and in a period other than the modulation period, the adjustment unit is configured to reduce the clock value so that the value of the first difference signal is minimized based on a determination result of the determination unit. The frequency of the clock signal may be adjusted such that the frequency of the signal is adjusted, or the value of the second difference signal is minimized.

  In the optical disc, address information is represented by phase modulation of the wobble signal, and the period detection unit may detect a phase modulation period of the wobble signal based on the first difference signal.

  In the optical disc, address information is represented by minimum shift keying modulation of the wobble signal, and the period detection unit detects a minimum shift keying modulation period of the wobble signal based on the first difference signal. Also good.

The generating means includes
An analog-digital converter that samples the wobble signal with an N-multiple clock of the clock signal, a band-pass filter that extracts the clock signal from the output signal of the analog-digital converter, and an output signal of the band-pass filter A rate converter that converts a data rate to 2 M / N of the data rate of the clock signal (M is an integer equal to or greater than 1, M is a wobble clock period, and N is a channel clock period); A phase comparator that generates a phase difference signal indicating a difference between the phase of the clock signal and the phase of the wobble signal based on an output signal, and a phase control loop that removes a predetermined signal band component from the phase difference signal And a phase control digital signal for converting an output signal of the phase control loop filter into an analog signal An analog converter, a frequency control loop filter for removing a predetermined signal band component from the first difference signal output from the first difference signal generating means, and an output signal of the frequency control loop filter as an analog signal The frequency control digital-analog converter to be converted into a frequency control, the output signal of the phase control digital-analog converter and the output signal of the frequency control digital-analog converter are added at a predetermined ratio, and the control signal is When the value of the output signal of the oscillation frequency controller to be generated, the voltage controlled oscillator that generates an N-multiplied clock of the clock signal based on the control signal, and the output signal of the phase control loop filter is outside a predetermined range , Modulating the output signal of the frequency control loop filter for a predetermined interval to change the oscillation frequency of the voltage controlled oscillator It, so that the value of the output signal of the phase control loop filter is within the predetermined range, controlling the output signal of the phase control loop filter may comprise a delta-sigma modulator.

  The clock signal generation method of the present invention includes a detection step of detecting a wobble signal from a reproduction signal of an optical disc, and a generation step of generating a clock signal so as to be synchronized with the wobble signal. Generating a first difference signal indicating a difference between the frequency of the wobble signal and the frequency of the clock signal; detecting a modulation period of the wobble signal based on the first difference signal; and Adjusting the frequency of the clock signal based on a predetermined signal other than the first difference signal, and adjusting the frequency of the clock signal based on the first difference signal in a period other than the modulation period; This achieves the above object.

  The program of the present invention is a program for causing a computer to execute a clock signal generation process, wherein the clock signal generation process is synchronized with a detection step of detecting a wobble signal from a reproduction signal of an optical disc and the wobble signal. Generating a clock signal, wherein the generating step generates a first difference signal indicating a difference between the frequency of the wobble signal and the frequency of the clock signal, and the first difference signal. And detecting a modulation period of the wobble signal based on the frequency, and adjusting the frequency of the clock signal based on a predetermined signal other than the first difference signal during the modulation period, and during the period other than the modulation period. Adjusting the frequency of the clock signal based on the first difference signal, thereby There is achieved.

  A control device according to the present invention is a control device for generating a clock signal so as to be synchronized with a wobble signal included in a reproduction signal of an optical disc, wherein a difference between the frequency of the wobble signal and the frequency of the clock signal is calculated. A first difference signal is generated, and a modulation period of the wobble signal is detected based on the first difference signal. In the modulation period, the clock signal is detected based on a predetermined signal other than the first difference signal. The frequency is adjusted, and during the period other than the modulation period, the frequency of the clock signal is adjusted based on the first difference signal, thereby achieving the above object.

  According to the optical disc device, the clock signal generation method, the program, and the control device of the present invention, the frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal during the modulation period of the wobble signal. Thus, since the frequency of the clock signal can be adjusted in the modulation period of the wobble signal without being based on the first difference signal that is erroneously detected due to the modulation of the wobble signal, Even during a period other than the modulation period, a clock signal having a stable frequency can be generated.

  According to the present invention, when address information is recorded on an optical disc, a clock signal synchronized with the wobble signal is generated based on a reproduction signal of the optical disc by performing MSK modulation or phase modulation on a wobble signal having a fixed period. Therefore, when detecting the difference signal indicating the difference between the frequency of the wobble signal and the frequency of the clock signal, a stable clock is obtained by holding (masking) the output of the difference signal erroneously detected due to the modulation. A signal can be generated. As a result, when a clock signal is used as a recording clock, an accurate recording mark can be formed on the optical disc. Furthermore, since the difference signal erroneously detected due to modulation is not input to the control loop in order to hold (mask) the output of the difference signal erroneously detected due to modulation, the loop gain is increased. Access performance is improved. Further, an optical disc apparatus having the same configuration can be used for an optical disc (for example, DVD-R, DVD-RAM) on which a wobble signal having a constant period is recorded. As a result, it is possible to realize an inexpensive and high-performance optical disk apparatus compatible with many types of optical disks.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
The first embodiment for generating a clock signal from the reproduction signal of the optical disc 101 will be described below. Address information is recorded on the optical disc 101 by MSK modulating a wobble signal with a fixed period.

  FIG. 1 shows a wobble signal (I) that is not frequency-modulated and a wobble signal (II) that is frequency-modulated. Signal (I) represents a wobble signal having a single frequency that is not frequency modulated. The period is 69 channel clock. Signal (II) represents a wobble signal that has been subjected to MSK modulation. For example, the frequency of an MSK modulated wobble signal is 1.5 times the frequency of an unmodulated wobble signal.

  FIG. 2 shows the optical disc apparatus 100 according to Embodiment 1 of the present invention.

  The optical disc apparatus 100 is configured so that an optical disc 101 can be inserted. The optical disc apparatus 100 includes an optical head 102, a preamplifier 103, an AGC 110, a wide band pass filter 111, an A / D converter 112, a band pass filter 113, and a VCO 121.

  The optical head 102 generates a light detection signal based on the reflected light reflected by the optical disc 101. The optical head 102 includes a two-divided detector (including two detectors). The preamplifier 103 generates a TE signal based on the difference between the output of one detector of the two-divided detector and the output of the other detector. The TE signal is input to the AGC 110. The AGC 110 feedback-controls the output of the wide band pass filter 111 so that the amplitude of the output signal of the wide band pass filter 111 is constant. The wide band-pass filter 111 has a low-pass filter characteristic for passing an address-modulated wobble signal and preventing aliasing. The output of the wide band pass filter 111 is input to the A / D converter 112. The A / D converter 112 samples the output of the wide band pass filter 111 at the oscillation frequency of the VCO 121 (69 times the wobble clock), and generates a wobble signal. The bandpass filter 113 filters the wobble signal and outputs a signal component necessary for detecting the MSK modulation period and generating the clock signal. Details of the function of the VCO 121 will be described later.

  The optical disc apparatus 100 further includes a rate converter 114, an offset correction unit 115, a phase comparator 116, a phase control loop filter 117, and a phase control D / A converter 118.

  The band pass filter 113 outputs a signal including a signal component necessary for generating a clock signal to the rate converter 114. The rate converter 114 converts the rate of this signal to 2 / N (N = 69). The output signal of the rate converter 114 is input to the offset correction unit 115. The offset correction unit 115 removes a DC component included in the output signal of the rate converter 114. The phase comparator 116 detects a phase error signal indicating a phase error based on the output signal of the offset correction unit 115. The phase comparator 116 outputs the detected phase error signal to the phase control loop filter 117. The phase control D / A converter 118 converts the output signal of the phase control loop filter 117 into an analog signal.

  Details of the rate converter 114, the offset correction unit 115, the phase comparator 116, and the phase control loop filter 117 will be described later.

  Hereinafter, comparison of frequencies of wobble signals will be described.

  The optical disc apparatus 100 further includes an MSK modulation detector 123, a frequency control loop filter 119, a frequency control D / A converter 120, a delta-sigma modulator 122, and a VCO 121.

  The output signal of the band pass filter 113 is input to the MSK modulation detector 123. The MSK modulation detector 123 detects an MSK modulation portion included in the wobble signal. When the MSK modulation portion is detected, the MSK modulation detector 123 outputs a frequency error signal as 0 and holds control. Details of the MSK modulation detector 123 will be described later.

The frequency error signal output from the MSK modulation detector 123 is input to the frequency control loop filter 119. If the frequency error indicated by the frequency error signal is y _n (n is an integer), the output of the frequency control loop filter 119 can be expressed as βΣy _n . Here, β is a positive constant that determines the frequency control characteristic.

  The output signal of the frequency control loop filter 119 is input to the frequency control D / A converter 120. The output signal of the frequency control D / A converter 120 and the output signal of the phase control D / A converter 118 are added.

  The output signal of the phase control loop filter 117 is also input to the delta-sigma modulator 122. The delta-sigma modulator 122 is a frequency control loop that changes the input to the frequency control D / A converter 120 by 1 LSB when the output signal of the phase control loop filter 117 exceeds a predetermined range. The filter 119 is controlled. The output signal of the frequency control D / A converter 120 has a large frequency change per 1 LSB. Therefore, there is a possibility that the oscillation frequency of the VCO 121 changes rapidly and the control loop cannot follow. For this reason, the output signal of the frequency control loop filter 119 is subjected to pulse width modulation for a predetermined period using delta-sigma modulation. As a result, the control loop can follow, and for example, even when CAV reproduction is performed on an optical disk recorded with CLV, a clock synchronized with the wobble signal can always be generated.

  Thus, the phase control loop filter 117, the frequency control loop filter 119, the frequency control D / A converter 120, and the delta-sigma modulator 122 cooperate to modulate the modulation period of the wobble signal (for example, MSK detection). During the period when the result is Low, the frequency of the clock signal is adjusted based on a predetermined signal other than the frequency error signal (for example, 0 signal, hold signal), and the period other than the modulation period of the wobble signal (for example, MSK detection) During the period when the result is High), the frequency of the clock signal is adjusted based on the frequency error signal. Further, the phase control loop filter 117, the frequency control loop filter 119, the frequency control D / A converter 120, and the delta-sigma modulator 122 cooperate to generate a frequency error in a period other than the modulation period of the wobble signal. The frequency of the clock signal is adjusted so that the value of the signal is minimized, and the frequency of the clock signal is adjusted so that the value of the frequency error signal is minimized.

  In general, since the range of the D / A converter is finite, the frequency control D / A converter 120 performs rough control, and the phase control D / A converter 118 performs fine control.

  FIG. 3 shows the rate-converted wobble signal.

  FIG. 3A shows a wobble signal having a phase that is not different from the phase of the clock signal.

  FIG. 3B shows a wobble signal having a phase that is ahead of the phase of the clock signal.

  FIG. 3C shows a wobble signal having a phase that is behind the phase of the clock signal.

  3A to 3C, a wobble signal having a value indicated by a white circle is output when the clock signal rises and falls.

  FIG. 4 shows the configuration of the rate converter 114. The rate converter 114 will be described with reference to FIG.

  The rate converter 114 operates a 69 period counter with a 69 times clock of the wobble clock. When the count values are “0” and “34”, the rate converter 114 outputs an enable signal. When the count value is “0”, the rate converter 114 outputs the signal input from the A / D converter, and when the count value is “34”, the rate converter 114 receives the signal from the A / D converter. The signal input from the A / D converter is added to the signal obtained by delaying the input signal by one clock, and a signal that is halved is output. That is, the rate converter 114 extracts the interpolation signal from the wobble signal sampled with the 69-fold clock. The output of the rate converter 114 is input to the offset correction means 115.

  FIG. 5 shows the configuration of the offset correction means 115. The offset correction means 115 will be described with reference to FIGS.

  The offset correction means 115 includes an adder / subtracter and a flip-flop circuit. The offset correction means 115 detects the DC component from the value of the signal (indicated by a white circle) obtained by sampling the wobble signal with the wobble clock, and performs control so that the DC component becomes zero (FIG. 3A). reference). The offset correction means 115 performs feedback control using an adder / subtractor and a flip-flop. Since the input signal has a 2's complement, the input signal is corrected so that the average value of the output of the offset correction means 115 becomes zero.

  Hereinafter, the phase comparator 116 will be described in detail.

  The phase comparator 116 detects a phase error signal indicating a phase error based on the signal output from the offset correction unit 115.

  The signal sampled at the rising edge of the wobble clock takes a positive value, and the signal sampled at the falling edge takes a negative value (see FIG. 3B). The phase error can be obtained by multiplying the input signal by a cosine wave (COS (nπ), n is an integer, n is an even number at the rising edge of the wobble clock, and n is an odd number at the falling edge of the wobble clock). . When the phase of the wobble clock is delayed, a positive phase error is output so as to increase the oscillation frequency (see FIG. 3B). Similarly, when the phase of the wobble clock is advanced, a negative phase error is output so as to lower the oscillation frequency (FIG. 3C).

  FIG. 6 shows the configuration of the phase control loop filter 117.

Assuming that the phase error input to the phase control loop filter 117 is x _n (n is an integer), the output of the phase control loop filter 117 can be expressed as αx _n + βΣx _n . Here, α and β are positive constants that determine the phase control characteristics.

  FIG. 7 shows the configuration of the MSK modulation detector 123.

  FIG. 8 shows signals (a) to (g) processed by a plurality of components included in the MSK modulation detector 123.

  The MSK modulation detector 123 generates a frequency error (first difference signal) indicating a difference between the frequency of the wobble signal and the frequency of the clock signal. Further, the MSK modulation detector 123 detects the modulation period of the wobble signal based on the frequency error.

  Hereinafter, the function of the MSK modulation detector 123 will be described in detail with reference to FIG. 7 and FIG.

  When the output of the bandpass filter 113 is greater than 0, a signal having a value of 0 is input to the MSK modulation detector 123, and when the output of the bandpass filter 113 is less than 0, a signal having a value of 1 is output. This is input to the MSK modulation detector 123. Only the sign bit of the bandpass filter 113 is input to the MSK modulation detector 123.

  When the MSK modulated wobble signal (signal (a)) is input to the MSK modulation detector 123, the MSK modulation detector 123 detects only the rising edge of the wobble signal and outputs the edge pulse (signal (b)). Output.

  The interval between the edge pulses is measured, and an addition result (signal (c)) is obtained. When the wobble signal has an ideal single frequency, the value of the addition result is 69. When the wobble signal has an MSK-modulated frequency, the value of the addition result is 69 or less. This is because the frequency of the wobble signal subjected to MSK modulation is 1.5 times the single frequency of the wobble signal not subjected to MSK modulation.

  The addition result is stored in six registers that are enabled for each edge pulse. The difference between the register values is taken, and if at least one of the absolute values is larger than a predetermined value, it is determined that the MSB modulation component is included in the wobble signal (signal (e)). The addition result (signal (f)) of the six registers measures the time corresponding to six cycles of the wobble signal. When the wobble signal has an ideal single frequency, the time corresponding to 6 cycles of the wobble signal is 414 cycles, so the difference between the expected 414 cycles and the addition result is the frequency error. The MSK modulation detector 123 outputs the detected frequency error when the MSK detection result (signal (e)) is High, and outputs the detected frequency error as 0 when it is Low. By detecting the MSK modulation component included in the wobble signal, an erroneous frequency error can be removed.

  Note that the number of registers included in the MSK modulation detector 123 is not limited to six. The number of registers included in the MSK modulation detector 123 is arbitrary. For example, when the number of registers included in the MSK modulation detector 123 is three and the wobble signal has an ideal single frequency, the time corresponding to three cycles of the wobble signal is 207 cycles. Therefore, the difference between the expected 207 periods and the addition result is the frequency error.

  Further, the number of registers can vary between 6 and 3. The addition results of the three registers measure the time corresponding to three cycles of the wobble signal, and the addition results of the six registers measure the time corresponding to six cycles of the wobble signal. A larger number of registers has a merit that the detection accuracy of the MSK modulation detector 123 becomes higher, but there is a demerit that a response speed of the MSK modulation detector 123 becomes slower at the same time. When the number of registers can be changed, the user can determine the number of registers according to the quality of the reproduction signal of the optical disc 101 in consideration of the advantages and disadvantages depending on the number of registers. For example, when the quality of the reproduction signal of the optical disk 101 is good, the user sets the number of registers to three so as to measure the time corresponding to three periods of the wobble signal in order to emphasize the response speed of the MSK modulation detector 123. To do. When the quality of the reproduction signal of the optical disc 101 is poor, the user switches the number of registers to six so as to measure the time corresponding to six periods of the wobble signal in order to place importance on the detection accuracy of the MSK modulation detector 123. The switching of the number of registers can be realized when the user inputs a switching signal from the outside of the optical disc apparatus 100.

(Embodiment 2)
The second embodiment for generating a clock signal from the reproduction signal of the optical disc 201 will be described below. Address information is recorded on the optical disc 201 by phase-modulating a wobble signal having a fixed period.

  FIG. 9 shows a wobble signal (III) not subjected to phase modulation and a wobble signal (IV) subjected to phase modulation. Signal (III) is a single signal having one cycle of 32 times the channel clock cycle. The signal (IV) is a wobble signal whose phase is inverted at two places.

  When the lengths of the six periods of the wobble signal are compared with reference to the signal (III) and the signal (IV), the length of the six periods of the single signal (III) is 192 periods and the phase is 2 The length of 6 cycles of the wobble signal (IV) that is inverted at the location is 208 cycles. This is because the rising edge interval is 48 periods in the section where the phase is reversed.

  FIG. 10 shows a configuration of the optical disc device 200 according to the second embodiment of the present invention.

  The optical disc device 200 is configured so that the optical disc 201 can be inserted. Address information is recorded on the optical disc 201 by phase-modulating a wobble signal having a fixed period.

  The optical disk apparatus 200 includes an A / D converter 212 instead of the A / D converter 112, a rate converter 214 instead of the rate converter 114, a VCO 221 instead of the VCO 121, and an MSK modulation detector 123. The optical disk apparatus 100 includes the same components as the optical disk apparatus 100 except that the phase modulation detector 223 is included instead. 10, the same components as those of the optical disc apparatus 100 shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted.

  The A / D converter 212 samples the output of the wide band pass filter 111 at the oscillation frequency of the VCO 221 (32 times the wobble clock) to generate a wobble signal. The rate converter 214 converts the rate of this signal to 2 / N (N = 32).

  FIG. 11 shows the configuration of the phase modulation detector 223 according to the second embodiment of the present invention.

  The configuration of the phase modulation detector 223 is the same as that of the MSK modulation detector 123 according to the first embodiment of the present invention except for the subtraction circuit. The subtraction circuit of the MSK modulation detector 123 is configured such that the difference from the 414 period is a frequency error. On the other hand, the subtraction circuit of the phase modulation detector 223 is configured such that the difference from the 192 period is a frequency error.

  FIG. 12 shows the rate converter 214 according to the second embodiment of the present invention.

  The rate converter 214 operates a 32-cycle counter with a 32 times clock of the wobble clock. When the count values are “0” and “16”, the rate converter 214 outputs an enable signal. When the count value is “0” or “16”, the rate converter 214 outputs the signal input from the A / D converter. Thus, the rate converter 214 can generate a wobble clock synchronized with the wobble signal even when the wobble signal is phase-modulated. The output of the rate converter 214 is input to the offset correction means 115.

  FIG. 13 is a diagram for explaining the operation of the optical disc apparatus 200 according to the second embodiment of the present invention.

  For example, the optical disc apparatus 200 controls the optical disc 201 with CAV and performs a seek operation from the inner periphery to the outer periphery of the optical disc 201. In this case, since the rotation speed of the spindle motor is constant, when the optical head reaches a predetermined position and tracking control is applied after focus control, a wobble signal having a high frequency is input.

  Immediately after seeking, the control signals (signal (B) and signal (C)) are low, and the control mode is frequency control. The frequency error detected inside the phase modulation detector 223 is a large positive value immediately after seeking (signal (D)). Since the frequency error is positive, the output of the frequency control loop filter 119 gradually increases (signal (G)). Therefore, the oscillation frequency of the VCO 221 is also increased (signal (H)).

  Signal (E) indicates that a phase modulation portion has been detected in the wobble signal. A section in which phase modulation is detected is High. When a frequency error (signal (D)) is output as a frequency error 0 in the phase modulation detection section, a frequency error output (signal (F)) is obtained. It can be seen that the oscillation frequency of the VCO 221 is controlled without erroneously reducing the frequency excessively by phase modulation. When the oscillation frequency of the VCO 221 approaches the input wobble signal, the phase control is activated and the frequency control is stopped. When the signal (B) is High and the signal (C) is Low, α and β of the phase control loop filter 117 are set to high values (gain is high).

  The signal (I) indicates the detected phase error, and the signal (J) indicates the output of the phase control loop filter 117. The frequency control section is set to an initial value that is the center of the range, and when phase control is started, a control signal is output.

  When the signal (B) and the signal (C) become High, α and β of the phase control loop filter 117 are set to low values, the loop gain is lowered, and control is performed so as not to be affected by some disturbance. Generate a stable wobble clock.

  The first embodiment and the second embodiment of the present invention have been described above with reference to FIGS.

  For example, as described with reference to FIG. 2, the A / D converter 112 corresponds to “signal detection means for detecting a wobble signal from a reproduction signal of an optical disk”, and includes a bandpass filter 113, a rate converter 114, , Offset correction means 115, phase comparator 116, phase control loop filter 117, phase control D / A converter 118, frequency control loop filter 119, and frequency control D / A converter 120 , VCO 121, VCO 121, delta-sigma modulator 122, and MSK modulation detector 123 correspond to “a generating means for generating a clock signal so as to be synchronized with a wobble signal”. Further, the MSK modulation detector 123 performs “the first difference signal generating means for generating the first difference signal indicating the difference between the frequency of the wobble signal and the frequency of the clock signal” and “the first difference signal based on the first difference signal. The frequency control loop filter 119, the frequency control D / A converter 120, and the delta-sigma modulator 122 correspond to “period detection means for detecting the modulation period” and “a predetermined period other than the first difference signal is included in the modulation period”. It corresponds to “adjustment means that adjusts the frequency of the clock signal based on the signal and adjusts the frequency of the clock signal based on the first difference signal during a period other than the modulation period”.

  However, the optical disc apparatus of the present invention is not limited to the one shown in FIG. 2 or FIG. As long as the functions of the respective means described above are achieved, an optical disc apparatus having an arbitrary configuration can be included in the scope of the present invention.

  Furthermore, each unit described in the embodiment shown in FIGS. 2 and 10 may be realized by hardware, may be realized by software, or may be realized by hardware and software. . Whether it is realized by hardware, software, or hardware and software, the optical disk device 100 or the optical disk device 200 detects “detects a wobble signal from an optical disk reproduction signal”. "Step", "Generating step for generating a clock signal so as to be synchronized with the wobble signal", "Step for generating a first difference signal indicating a difference between the frequency of the wobble signal and the frequency of the clock signal" and "No. “Detecting the modulation period of the wobble signal based on one difference signal” and “Adjusting the frequency of the clock signal based on a predetermined signal other than the first difference signal in the modulation period and in the period other than the modulation period” And adjusting the frequency of the clock signal based on the first difference signal " Lock signal generating process may be performed. The clock signal generation process of the present invention may have an arbitrary procedure as long as the above-described steps can be executed.

  For example, the optical disc apparatus of the present invention stores a clock signal generation processing program for executing the functions of the optical disc apparatus. The clock signal generation processing program executes the function of the optical disc apparatus.

  The clock signal generation processing program may be stored in advance in storage means included in the optical disc apparatus when the computer is shipped. Alternatively, the clock signal generation processing program may be stored in the storage means after the computer is shipped. For example, a user may download a clock signal generation processing program from a specific website on the Internet for a fee or free of charge, and install the downloaded program in a computer. When the clock signal generation processing program is recorded on a computer-readable recording medium such as a flexible disk, CD-ROM, or DVD-ROM, access processing is performed on the computer using an input device (for example, a disk drive device). You may make it install. The installed clock signal generation processing program is stored in the storage means.

  Further, a control device (bandpass filter 113, rate converter 114, offset correction means 115, phase comparator 116, phase control loop filter 117, phase control D / A converter 118, frequency control Loop filter 119, frequency control D / A converter 120, VCO 121 VCO 121, delta-sigma modulator 122, and MSK modulation detector 123) are formed on a single chip LSI (semiconductor integrated circuit) or a part thereof. Can be manufactured as When the control device is manufactured as a one-chip LSI, the manufacturing process of the optical disc device 100 or the optical disc device 200 can be facilitated.

  As mentioned above, although this invention has been illustrated using preferable embodiment of this invention, this invention should not be limited and limited to this embodiment. It is understood that the scope of the present invention should be construed only by the claims. It is understood that those skilled in the art can implement an equivalent range based on the description of the present invention and the common general technical knowledge from the description of specific preferred embodiments of the present invention. Patents, patent applications, and documents cited herein should be incorporated by reference in their entirety, as if the contents themselves were specifically described herein. Understood.

  The optical disk device, clock signal generation method, program, and control device of the present invention have a function of masking erroneous frequency errors, and are useful for reproducing carrier waves for communication.

  According to the optical disc device, the clock signal generation method, the program, and the control device of the present invention, the frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal during the modulation period of the wobble signal. Thus, since the frequency of the clock signal can be adjusted in the modulation period of the wobble signal without being based on the first difference signal that is erroneously detected due to the modulation of the wobble signal, Even during a period other than the modulation period, a clock signal having a stable frequency can be generated.

A wobble signal not frequency-modulated and a wobble signal frequency-modulated are shown. 1 shows an optical disc device 100 according to a first embodiment of the present invention. The rate-converted wobble signal is shown. The rate-converted wobble signal is shown. The rate-converted wobble signal is shown. The structure of the rate converter 114 is shown. The structure of the offset correction means 115 is shown. The configuration of the phase control loop filter 117 is shown. The configuration of the MSK modulation detector 123 is shown. Signals (a) to (g) processed by a plurality of components included in the MSK modulation detector 123 are shown. The wobble signal which is not phase-modulated and the wobble signal which is phase-modulated are shown. The structure of the optical disk apparatus 200 of Embodiment 2 of this invention is shown. The structure of the phase modulation detector 223 of Embodiment 2 of this invention is shown. 4 shows a rate converter 214 according to the second embodiment of the present invention. It is a figure for demonstrating operation | movement of the optical disk apparatus 200 of Embodiment 2 of this invention. A conventional wobble clock generation circuit 300 described in Patent Document 1 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Optical disk apparatus 101 Optical disk 102 Optical head 103 Preamplifier 110 AGC
111 Wide band pass filter 112 A / D converter 113 Band pass filter 114 Rate converter 115 Offset correction means 116 Phase comparator 117 Phase control loop filter 118 Phase control D / A converter 119 Frequency control loop filter 120 Frequency Control D / A converter 121 Voltage controlled oscillator 122 Delta sigma modulator 123 MSK modulation detector

Claims (9)

Signal detection means for detecting a wobble signal from the reproduction signal of the optical disc;
Generating means for generating a clock signal so as to be synchronized with the wobble signal,
The generating means includes
First difference signal generating means for generating a first difference signal indicating a difference between the frequency of the wobble signal and the frequency of the clock signal;
Period detecting means for detecting a modulation period of the wobble signal based on the first difference signal;
During the modulation period, the frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal, and during the period other than the modulation period, the frequency of the clock signal is adjusted based on the first difference signal. An optical disc apparatus comprising: an adjusting means for adjusting.   2. The optical disc according to claim 1, wherein the adjustment unit adjusts the frequency of the clock signal so that the value of the first difference signal is minimized during a period other than the modulation period. The generating means includes
Determination means for determining whether a value of the first difference signal is greater than a predetermined value;
A second difference signal generating means for generating a second difference signal indicating a difference between the phase of the wobble signal and the phase of the clock signal;
In a period other than the modulation period, the adjustment unit adjusts the frequency of the clock signal so that the value of the first difference signal is minimized based on the determination result of the determination unit, or the first The optical disk apparatus according to claim 1, wherein the frequency of the clock signal is adjusted so that the value of the two-difference signal is minimized. In the optical disc, address information is represented by phase modulation of the wobble signal,
The optical disc apparatus according to claim 1, wherein the period detection unit detects a phase modulation period of the wobble signal based on the first difference signal. On the optical disc, address information is represented by minimum shift keying modulation of the wobble signal,
The optical disc apparatus according to claim 1, wherein the period detection unit detects a minimum shift keying modulation period of the wobble signal based on the first difference signal. The generating means includes
An analog-to-digital converter that samples the wobble signal with an N multiplied clock of the clock signal;
A bandpass filter for extracting the clock signal from the output signal of the analog-digital converter;
Rate conversion for converting the data rate of the output signal of the bandpass filter to 2M / N of the data rate of the clock signal (M is an integer of 1 or more, M indicates a wobble clock period, and N indicates a channel clock period) And
A phase comparator that generates a phase difference signal indicating a difference between a phase of the clock signal and a phase of the wobble signal based on an output signal of the rate converter;
A phase control loop filter for removing a predetermined signal band component from the phase difference signal;
A phase-control digital-analog converter that converts an output signal of the phase-control loop filter into an analog signal;
A frequency control loop filter for removing a predetermined signal band component from the first difference signal output from the first difference signal generating means;
A digital-analog converter for frequency control that converts an output signal of the frequency control loop filter into an analog signal;
An oscillation frequency controller that adds the output signal of the phase control digital-analog converter and the output signal of the frequency control digital-analog converter at a predetermined ratio to generate a control signal;
A voltage controlled oscillator that generates an N-multiplied clock of the clock signal based on the control signal;
When the value of the output signal of the phase control loop filter is outside a predetermined range, the output signal of the frequency control loop filter is modulated for a predetermined interval, and the oscillation frequency of the voltage controlled oscillator is changed, thereby The optical disc apparatus according to claim 1, further comprising: a delta-sigma modulator that controls an output signal of the phase control loop filter so that a value of an output signal of the phase control loop filter falls within the predetermined range. A detection step of detecting a wobble signal from the reproduction signal of the optical disc;
Generating a clock signal so as to be synchronized with the wobble signal,
The generating step includes
Generating a first difference signal indicating a difference between a frequency of the wobble signal and a frequency of the clock signal;
Detecting a modulation period of the wobble signal based on the first difference signal;
During the modulation period, the frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal, and during the period other than the modulation period, the frequency of the clock signal is adjusted based on the first difference signal. A method of generating a clock signal, comprising the step of adjusting. A program for causing a computer to execute clock signal generation processing,
The clock signal generation process includes:
A detection step of detecting a wobble signal from the reproduction signal of the optical disc;
Generating a clock signal so as to be synchronized with the wobble signal,
The generating step includes
Generating a first difference signal indicating a difference between a frequency of the wobble signal and a frequency of the clock signal;
Detecting a modulation period of the wobble signal based on the first difference signal;
During the modulation period, the frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal, and during the period other than the modulation period, the frequency of the clock signal is adjusted based on the first difference signal. A program comprising the steps of adjusting. A control device for generating a clock signal so as to be synchronized with a wobble signal included in a reproduction signal of an optical disc,
Generating a first difference signal indicating a difference between the frequency of the wobble signal and the frequency of the clock signal;
Detecting a modulation period of the wobble signal based on the first difference signal;
During the modulation period, the frequency of the clock signal is adjusted based on a predetermined signal other than the first difference signal, and during the period other than the modulation period, the frequency of the clock signal is adjusted based on the first difference signal. The control device to adjust.

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