JP3661893B2 - Optical disk playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk reproducing apparatus that facilitates pulling of a phase locked loop for clock reproduction by detecting a linear velocity period from a reproduction signal of a digitally recorded optical disk medium and controlling a phase locked loop or a waveform equalizer. About.
[0002]
[Prior art]
As a method of making the most effective use of the capacity of an optical disc, a recording method is used in which the linear velocity is constant and the recording density on the recording medium is uniform, as is seen in a compact disc (Compact Disk). When performing phase-synchronization for an optical disk playback signal digitally modulated and recorded with mark width modulation so that the linear recording density is constant, the frequency of the clock component of the playback signal and the clock generation circuit of the phase-locked loop circuit If the pull-in is not started in the state where the frequencies are close to each other, there is a high possibility of pseudo pull-in to a frequency different from the clock frequency of the reproduction signal. To avoid this, normal phase detection is possible by detecting the playback linear velocity of the optical disc, detecting the pulse width or pulse interval included in the modulation signal, and controlling the disc rotational speed and the free-running frequency of the phase-locked loop. Synchronous pull-in is possible.
[0003]
For example, there is a disc playback system as shown in FIG. Data as shown in FIG. 17A is recorded on the optical disk 28 so that the linear recording density is constant. It is assumed that the recorded data is data in which continuous 0 or 1 is restricted to 3 or more and 11 or less. For example, it is a modulation method such as EFM (Eight to Fortene Modulation). Since the reproduced signal obtained by reproducing by the reproducing means 29 exhibits low-pass filtering characteristics and the amplitude decreases as the frequency component becomes higher, the waveform equalizing means 1 emphasizes the high frequency range in order to correct this. The reproduction signal (FIG. 17B) emphasized by the high frequency is binarized at a predetermined slice level by the binarizing means 2 and converted to a binarized signal (FIG. 17C). Here, the optimum value of the slice level is automatically adjusted according to the DC component of the reproduction signal, although it varies depending on the recording mark size variation.
[0004]
When a binarized signal is input, the phase with the output of the voltage controlled oscillator 21 is compared by the phase comparator 22 and a phase error voltage corresponding to the phase difference between the two is generated. The charge pump 23 discharges or sucks a constant current according to the phase error voltage, and the loop filter 24 converts the output current of the charge pump 23 into a voltage and simultaneously limits the band. Further, by varying the output clock frequency of the voltage controlled oscillator 21 with the output voltage of the loop filter 24, a phase-locked loop is formed and phase-synchronized with the clock component of the input binary signal (FIG. 17 (c)). A clock (FIG. 17 (d)) is generated. Then, the synchronizing means 6 synchronizes the binarized signal (FIG. 17C) with the synchronizing clock (FIG. 17D), and outputs the binarized signal data synchronized with the synchronizing clock and the synchronizing clock.
[0005]
However, with the above-described phase-locked loop alone, there is a possibility that pseudo-pulling may occur if the free-running frequency of the voltage-controlled oscillator 21 is far from the clock frequency of the input binarized signal at the start of synchronous pull-in. Normally, if the clock frequency of the binarized signal is approximately ± 5% with respect to the free-running frequency of the voltage controlled oscillator 21, the phase synchronization can be reliably pulled in. If it is out of this range, normal pull-in may not be possible. Therefore, the 11T period detection means 25 is provided outside the phase-locked loop as the first pulling assist means, and the time period of the 11 consecutive 0 recordings or 1 recording pattern existing in the binarized signal (FIG. 17C). When the measured value is longer than the steady value, the oscillation frequency of the voltage controlled oscillator is lowered, and conversely, when the measured value is shorter, the predetermined current from the charge pump is increased so that the oscillation frequency of the voltage controlled oscillator 21 is increased. Do infusion or inhalation. By performing this until the oscillation frequency of the voltage controlled oscillator substantially matches the frequency of the clock component included in the binarized signal, phase synchronization can be obtained without pseudo-synchronization.
[0006]
Further, the 6T period detection means 26 is provided as the second pulling assist means, and the time period of the (000111) or (111000) recording pattern existing in the binarized signal (FIG. 17C) is measured, and the measured value If the value is larger than the steady value, the motor rotation speed is increased, and if it is shorter, the motor rotation speed is decreased to approach the steady linear speed so that the frequency of the clock component of the binarized signal is the free-running oscillation frequency of the voltage controlled oscillator. The pseudo pull-in is canceled so as to substantially match the above. Here, the (000111) or (111000) recording pattern period corresponds to the period of the rising interval or falling interval of the binarized signal, and even if the binarized slice level in the binarizing means 2 varies, the detection cycle Can be detected against disturbances such as search seek. On the other hand, the 11T period detecting means 25 as the first pulling assist means detects the period from the rising edge to the falling edge or from the falling edge to the rising edge. Since the cycle is long, the deterioration of accuracy is small.
[0007]
When data recorded on an optical disk medium is retrieved at high speed and data reproduction is performed, it is required to increase the phase synchronization pull-in for the disk reproduction signal.
[0008]
[Problems to be solved by the invention]
However, in the method of detecting the linear velocity period of the optical disc and controlling the disc rotational speed like the 6T period detection described above, it takes time until the rotational speed is settled, and until the phase synchronization is pulled in for clock reproduction. It will take time. Further, as in the 11T period detection described above, the pulse width or pulse interval included in the modulation signal is detected and compared with a steady value, and a predetermined current is injected or sucked into the loop filter from the charge pump to generate a voltage. In the method of controlling the free-running frequency of the controlled oscillator, the control is a binary control of increasing or decreasing the frequency, and the accuracy is not good.
[0009]
The object of the present invention is to solve the above-mentioned drawbacks, quantitatively detect the linear velocity period of the optical disk, and based on this, the free-running frequency of the synchronous clock generator of the phase synchronization means binarizes the reproduction signal. The phase synchronization pull-in is performed easily and at high speed by controlling so that the frequency of the clock component of the obtained signal is substantially the same, and both the rising and falling intervals are used as detection information. Thus, the present invention provides an optical disc reproducing apparatus that increases the detection frequency and detects the absence of a reproduction signal and holds the linear velocity detection output to increase the reliability.
[0010]
[Means for Solving the Problems]
The optical disk reproducing apparatus of the present invention Re Binarization means for converting the raw signal into a digital signal by binarizing at a predetermined level; Said Specific patterns included in digital signals The length of itself with a high-frequency fixed clock It has a cycle detection means that detects and outputs and a free-running cycle An optical disk reproducing apparatus comprising phase locked loop means for controlling the free-running period to be substantially proportional to the reciprocal of the length of the specific pattern itself and reproducing and outputting a clock component of the digital signal. The period detection unit counts a first interval between first rising edges of the digital signal and a second interval between second falling edges of the reproduction signal. And calculating a minimum value or a maximum value including both the first interval and the second interval every predetermined period, and outputting the calculated value as a cycle of the specific pattern. Do .
[0016]
The optical disk reproducing apparatus of the present invention also has binarization means for binarizing a reproduction signal at a predetermined level to convert it into a digital signal, and fixing the length of the specific pattern itself included in the digital signal at a high frequency. A period detection means for detecting and outputting with a clock; and a free-running period, and the free-running period is controlled to be substantially proportional to the reciprocal of the length of the specific pattern itself, and the clock component of the digital signal An optical disk reproducing device comprising phase-locked loop means for reproducing and outputting The period detecting means is a pulse width of the digital signal. and Pulse interval Pattern Counting means for continuously counting and within a predetermined period Said Counting means Counted in This Total number Value Large value Inspect Out Every time update Hold Maximum value storage means; When the update is done The maximum value held by the maximum value storage means and Said Counting means so Next Counted Add count value Hold You Ruka Calculation means, Said Every predetermined period Held in the adding means A maximum value detecting means for outputting an added value as the length of the specific pattern. It is characterized by .
[0017]
The optical disk reproducing apparatus of the present invention also has binarization means for binarizing a reproduction signal at a predetermined level to convert it into a digital signal, and fixing the length of the specific pattern itself included in the digital signal at a high frequency. A period detection means for detecting and outputting with a clock; and a free-running period, and the free-running period is controlled to be substantially proportional to the reciprocal of the length of the specific pattern itself, and the clock component of the digital signal An optical disk reproducing device comprising phase-locked loop means for reproducing and outputting The period detecting means is a pulse width of the digital signal. and Pulse interval Pattern Counting means for continuously counting Said Holding means for holding the counting result obtained immediately before by the counting means; Said Two successive pulse widths of the digital signal by adding the output of the counting means and the output of the holding means and Adding means for obtaining the sum of pulse intervals, and every predetermined period Said First determining means for calculating a minimum value of the output of the adding means; Said Every predetermined period Said Second determining means for calculating the maximum value of the output of the counting means; Said Based on the output of the first determining means, Said Estimating means for estimating the output range of the second determining means, and the output of the second determining means is Said Estimated The In range In If there is Said Output of second determining means Out Force Said Estimated The Out of range In In some cases, the output of the second decision means is prohibited and obtained immediately before Output of the second determining means And holding means for holding It is characterized by .
[0023]
With the above configuration, the linear velocity period at the time of reproducing the optical disk is detected, and the free-running frequency of the phase-locked loop means is controlled to substantially match the frequency of the clock component of the digitized signal obtained by binarizing the reproduced signal. Thus, phase synchronization can be reliably and rapidly performed, and reliability can be improved by having a function of detecting a missing reproduction signal and holding a linear velocity detection output.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an optical disk reproducing apparatus according to the present invention will be described with reference to the drawings.
[0025]
(Embodiment 1)
Embodiment 1 of an optical disk reproducing apparatus according to the present invention will be described with reference to the block diagram of FIG.
[0026]
In FIG. 1, the optical disk reproduction signal is corrected by the waveform equalizing means 1 so as to emphasize the high frequency range. This signal is binarized at a predetermined level in the binarizing means 2 and converted into a digital signal.
[0027]
Next, the period of the specific pattern of the digital signal binarized by the binarizing means 2 is counted by the period detecting means 4 with a high frequency clock. It can be measured with a time resolution of one cycle of the high frequency clock. When counting is performed at both edges of the high-frequency clock, time resolution of a half cycle is possible.
[0028]
Since the result obtained by the period detection means 4 has information inversely proportional to the linear velocity, that is, clock period information possessed by the reproduction signal, the free-running frequency of the phase-locked loop means 5 becomes the clock frequency possessed by the reproduction signal based on this information. Set to match.
[0029]
Here, the phase-locked loop means 5 includes the phase comparator 22, the charge pump 23, the loop filter 24, and the voltage controlled oscillator 21, as described in the conventional example. In general, the input / output characteristics of the voltage controlled oscillator 21 are designed to be variable within a range of ± Δf according to the input voltage, with the oscillation frequency at the time of steady playback of the optical disk as the center frequency f0, as shown by the solid line in FIG. The In this case, the frequency of the clock component included in the digital signal obtained from the binarizing means 2 and the oscillation frequency of the voltage controlled oscillator 21 are greatly separated when the disk rotation is not settled, such as when the optical disk starts playing or immediately after seeking. For this reason, the phase is not synchronized (hereinafter referred to as a pseudo pull-in state). Therefore, it has been necessary to wait for the motor to be controlled and to settle in the vicinity of steady rotation before the phase synchronization is pulled.
[0030]
However, since the detection result obtained by the period detection means 4 has clock period information included in the reproduction signal, the reciprocal is obtained and converted into frequency information so that the center frequency f0 of the voltage controlled oscillator 21 is proportional to this. If the control is adaptively performed as shown by the broken line in FIG. 19 so that the oscillation frequency substantially matches the frequency of the clock component of the digital signal obtained from the binarization means 2, the motor rotation is settling. It is possible to complete the synchronous pull-in without any high speed.
[0031]
In this way, the frequency of the clock component possessed by the digital signal obtained from the binarizing means 2 and the free-running frequency of the phase-locked loop means 5 are close to each other and can be normally drawn without being pseudo-drawn. Since the self-running frequency is set electrically, it is possible to shorten the time from the start of the synchronous pull-in compared to the synchronous pull-in after the rotation of the disk motor is adjusted. Since the free-running frequency is set with high resolution, the free-running frequency of the phase-locked loop means 5 almost coincides with the clock frequency of the reproduction signal, so that the time required for the frequency pull-in process can be shortened.
[0032]
The digital signal obtained from the binarizing means 2 is synchronized by the synchronizing means 6 with the reproduced clock signal obtained by the phase locked loop means 5 and outputted as reproduced data.
[0033]
Note that the cycle detection means 4 may stop the detection operation by stopping the clock and perform the detection value holding operation.
[0034]
For example, as shown in FIG. 2, the supply of the high-frequency clock may be turned on / off by a disk dropout detection signal. Thereby, it is possible to prevent the detection value from being disturbed due to a defect of the disk.
[0035]
The period detecting means 4 described in the first embodiment is composed of a specific pattern counting means 106 and an output holding means 7 as shown in FIG. 3, and the output holding means 7 monitors the count value output of the specific pattern counting means 106. While the detection result is outside the predetermined range, the output is output as it is, the output is held when the detection result is within the predetermined range, and thereafter, the output is continuously held regardless of the detection result of the period detection means 4. It's okay. For example, immediately after seeking on the inner circumference side, the period detection value outputs a large value as shown in FIG. 4, but the free-running frequency of the phase-locked loop means 5 is changed in accordance with this value and the reproduction signal has a clock. By making it substantially coincide with the frequency, synchronization pull-in is performed immediately after seek. Then, when the disk motor rotation falls to a steady state after the synchronous pull-in is performed and the value detected by the period detecting means 4 falls within the predetermined value, the output of the period detecting means 4 is fixed.
[0036]
This prevents erroneous detection of the period due to a disturbance such as a disk defect during steady playback and prevents the free-running frequency of the phase-locked loop 4 from changing and the synchronous clock output frequency from fluctuating. Can be improved.
[0037]
Note that a continuous pattern of 11T and 11T called a sync pattern (where T is the minimum recording unit) is recorded on a CD or the like in order to synchronize at regular intervals. This pattern is a maximum length pattern that does not exist elsewhere in the data, and has a feature that it always exists once every fixed period. In such a case, the disk playback linear velocity information can be obtained by measuring the rising time from the rising edge of the data edge or the falling time to the falling edge at every predetermined detection time and obtaining the maximum value.
[0038]
Therefore, the period detecting means 4 described in the first embodiment includes a first counting means 8 for counting the interval of the reproduction signal rising portion of the digital signal output from the binarizing means 2 as shown in FIG. The second counting means 9 that counts the interval between the parts, and the determination to output the minimum value (or the maximum value) including both the output result of the first counting means 8 and the counting result of the second counting means 9 every predetermined period It may be constituted by the means 10 to obtain the minimum value (or maximum value) of the sum of two consecutive pulse widths or pulse intervals. As a result, the counting frequency can be doubled compared to counting only the rising edge interval or the falling edge interval.
[0039]
The period detecting means 4 described in the first embodiment includes a counting means 11 for synchronizing digital signals with a high frequency clock as shown in FIG. 6, and continuously counting the pulse width or pulse interval. 11, the holding means 12 holding the counting result obtained immediately before, the count result output of the counting means 11 and the holding data output of the holding means 12 as inputs, and two consecutive pulse width or pulse interval results counted are input. An adding means 14 for adding, and a judging means 10 for obtaining the minimum value (or maximum value) of the adding means output for each predetermined period, and the minimum value (or maximum value) of the sum of two consecutive pulse widths or pulse intervals. ). The configuration shown in FIG. 5 requires two counting means. However, this method requires only one counting means, so the circuit scale is reduced.
[0040]
The period detecting means 4 described in the first embodiment includes a counting means 11 for synchronizing a digital signal with a high-frequency clock and continuously counting the pulse width or pulse interval as shown in FIG. The holding value is reset every period and updated every time the maximum value of the counting value of the counting means is detected from the beginning of the predetermined detection period, and the maximum value storage means 13 for holding this, and the maximum storage value of the maximum value storage means When the value is updated, the value held in the maximum value storage means 13 and the count value counted next by the counting means 11 are added, and the addition means 14 for holding and outputting this value, and the addition means at the end of the predetermined detection period The maximum period output means 15 outputs 14 output values as the period detection result, and may be output by adding the maximum pulse width or pulse interval and the next maximum pulse width or pulse interval. When a specific pulse width or pulse interval is located after the maximum pulse width or maximum pulse interval, it is possible to improve detection accuracy.
[0041]
As shown in FIG. 8, every time the maximum pulse width appears, the maximum value storage means 13 holds the maximum value, and this value and the count value of the next pulse width are added by the adding means 14 to hold this value. The value held at a constant cycle is output, and the held value is reset at the same time.
[0042]
For example, when the maximum pulse width or pulse interval included in the reproduction signal has a width of 14T and the next pattern is always determined to be 4T, the detection accuracy is 18/14 times by adding these detections. become.
[0043]
The period detecting means 4 described in the first embodiment includes one counting means 11 that synchronizes a digital signal with a high frequency clock and continuously counts the pulse width or pulse interval as shown in FIG. The holding means 12 for holding the previous counting result, and the adding means 14 for inputting the counting result output of the counting means 11 and the holding data output of the holding means 12 and adding the two consecutive pulse widths or pulse interval results counted. A first determination means 16 for obtaining a minimum value of the output of the adding means 14 for each predetermined period, a second determination means 17 for obtaining a maximum value of the output of the counting means 11 for each predetermined period, The estimation means 18 for estimating the output range of the second determination means 17 using the output of the determination means 16 as an input, and the output of the second determination means 17 and the output of the estimation means 18 as inputs are usually the second determination means. 17 out If the output of the second determination means 17 is outside the range estimated by the estimation means 18, the output of the second determination means 17 is prohibited and the immediately preceding output value is retained, When the output of the judging means 17 falls within the range estimated by the estimating means 18, it is constituted by a prohibiting means 19 that bypasses the output of the second judging means 17 again. Usually, the output of the second judging means with high detection accuracy is provided. The output may be held when it is determined based on the first determination means output with few detection errors that the second determination means output may be erroneous. The first determination means 16 has a lower detection error rate than the second determination means 17, but the detection accuracy is higher when the second determination means is higher. Strong period detection is possible.
[0044]
For example, assume that an EFM modulation is recorded on an optical disk, that is, a pattern having a width of 3T to 11T is recorded in T increments. Then, it is assumed that the first determination unit detects the [3T, 3T] pattern that is the minimum value of the recording pattern, and the second determination unit detects the [11T] pattern that is the maximum value of the recording pattern. Both of the determination means are used to obtain disc reproduction linear velocity information. The first detection means has low detection accuracy but high reliability, while the second detection means has high detection accuracy but low reliability. If there is such a feature, the output value of the second determination means is always predicted from the highly reliable first determination means (eg, obtained by calculating a value multiplied by 11/6), and the second determination means If the output value is close to the predicted value, the output value of the second determination means is output as it is, and if it is out of the predicted value, it can be regarded as a detection error and the previous value is held, so that both accuracy and reliability can be achieved. .
[0045]
In this example, the method of adding two consecutive pulse widths or pulse interval results to obtain the minimum value every predetermined period is used. However, as shown in FIG. May be counted independently, and a minimum value including both may be obtained every predetermined period. Further, the second determination means 17 input may be for obtaining the maximum value of the output of the addition means 14 every predetermined period.
[0046]
(Embodiment 2)
A second embodiment of the optical disk reproducing apparatus according to the present invention will be described with reference to the block diagram of FIG. The optical disk reproduction signal is corrected by the waveform equalizing means 1 so as to enhance the high frequency. The binarized means 2 binarizes the high-frequency emphasized signal at a constant level and converts it to a digital signal.
[0047]
Next, the period of the specific pattern of the digital signal binarized by the binarizing means 2 is counted by the period detecting means 4 with a high frequency clock. Here, the time length of the specific pattern can be measured with the minimum resolution of one period of the high frequency clock. When counting at both edges of the high-frequency clock, the resolution is one-half cycle.
[0048]
During reproduction of an optical disk, the reproduction signal band increases in proportion to the reproduction linear velocity, and conversely decreases if the linear velocity is slow. Further, the output of the cycle detection means 4 is cycle information of the linear velocity, and is a value inversely proportional to the linear velocity. As shown in FIG. 10, the reciprocal number of the linear velocity period detection result output from the period detection unit 4 is calculated by the reciprocal number calculation unit 20, converted into frequency information and output, and the waveform equalization unit 1 is proportional to this. The waveform equalization can be optimized by changing the high frequency emphasis band.
[0049]
Further, since the result obtained by the period detecting means 4 has linear velocity information, that is, clock frequency information possessed by the reproduction signal, the free-running frequency of the phase locked loop means 5 is almost equal to the clock frequency possessed by the reproduction signal. Set to match. In this way, since the frequency of the clock component possessed by the digital signal obtained from the binarizing means 2 and the synchronized clock frequency of the phase locked loop means 5 are close to each other, it is possible to draw in normally without pseudo pull-in. In this way, the digital signal obtained from the binarizing means 2 is synchronized by the synchronizing means 6 with the reproduced clock signal obtained by the phase locked loop means 5 and outputted as reproduced data.
[0050]
The phase-locked loop means 5 receives the calculation output of the reciprocal number calculating means 20, and sets the free-running frequency of the phase-locked loop so as to be proportional to it, so that it substantially matches the clock frequency of the binary digital signal. It may be what you want.
[0051]
Further, in the first or second embodiment, when the frequency characteristic of the high frequency emphasis of the waveform equalizing means 1 shows the characteristic as shown in FIG. 11A, if the linear velocity of the optical disk is faster than the steady state, There is a possibility that the band of the signal frequency exceeds the pass band of the waveform equalization means (state of CLV speed in FIG. 11). Since the disk rotation is not in a steady state at the start of disk reproduction, the frequency band of the reproduction signal may exceed the pass band of the waveform equalization means. Therefore, the waveform equalizing means 1 obtains the reproduction start signal as an external signal as shown in FIG. 12, thereby forcing the high frequency enhancement band to be higher than that during normal reproduction as shown in FIG. It is possible to prevent the loss of signal frequency components by shifting to the band side.
[0052]
Further, in the first or second embodiment, when the frequency characteristic of the high frequency emphasis of the waveform equalizing means 1 shows the characteristic as shown in FIG. 11A, if the linear velocity of the optical disk is faster than the steady state, There is a possibility that the frequency band of the reproduction signal may exceed the pass band of the waveform equalization means (state of CLV speed in FIG. 11). In particular, when seeking from the inner periphery of the disk to the outer periphery, it takes time for the motor rotation to converge to steady rotation, so the signal frequency band may exceed the pass band of the waveform equalization means immediately after seeking. Is expensive. Therefore, the waveform equalizing means 1 compulsorily obtains a high frequency enhancement band as shown in FIG. 11B by obtaining a seek signal from the inner circumference to the outer circumference of the optical disc as an external signal as shown in FIG. In addition, the signal frequency component may be prevented from being lost by shifting to a higher frequency side than during normal reproduction.
[0053]
Further, the period of the specific pattern of the digital signal binarized by the binarizing means 2 is counted by the period detecting means 4 with a high frequency clock. Here, the time length of the specific pattern is measured with the lowest resolution (= 1 LSB) of one cycle of the high-frequency clock. However, when counting is performed at both edges of the high-frequency clock, the resolution is one-half cycle.
[0054]
In FIG. 14, the relationship between the time length of the specific pattern that is the input of the cycle detection unit 4 and the detection output of the cycle detection unit 4 is indicated by a solid line. If the detection method of the period detection means 4 is a method of counting with a high frequency clock, it changes in a stepped manner in this way. A broken line is an ideal detection curve. The error from the solid line and the broken line is caused by 1 LSB corresponding to the least significant bit of the counter at the maximum. On the other hand, by adding an offset of (1/2) LSB to the output value as shown in FIG. 15, the error from the broken line can be suppressed to the maximum (1/2) LSB. As long as the offset amount is 1 LSB or less, it may be other than (1/2) LSB.
[0055]
As shown in FIG. 18, the dropout detecting means 3 described in the first and second embodiments binarizes a tracking error signal generated when traversing the recording portion of the optical disk at a predetermined level and traverses the signal non-recording portion. The time may be determined and used as part of the missing information of the reproduction signal.
[0056]
In the above embodiment, the case where a disk recorded at a constant linear velocity is reproduced at a constant linear velocity has been described. However, if the method of the present invention is used, the oscillation frequency of the phase-locked loop means 5 depends on the reproduction rate. Since the change can be made adaptively, the reproduction may not be a constant linear velocity.
[0057]
【The invention's effect】
According to the present invention, the linear velocity period during reproduction of the optical disk is detected, and the free-running frequency of the phase-locked loop means is controlled so as to substantially match the frequency of the clock component of the digitized signal obtained by binarizing the reproduction signal. By doing so, it is possible to perform the phase synchronization pull-in reliably and at high speed, and it is possible to improve the reliability by having the function of detecting the lack of the reproduction signal and holding the linear velocity detection output.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a first embodiment of an optical disc playback apparatus according to the present invention.
FIG. 2 is a block diagram showing a configuration of period detection means 4 in the first embodiment.
FIG. 3 is a block diagram showing another configuration of the cycle detection means 4 in the first embodiment.
4 is a graph showing an output value of period detection means 4 in Embodiment 1. FIG.
FIG. 5 is a block diagram showing another configuration of the cycle detection means 4 in the first embodiment.
FIG. 6 is a block diagram showing another configuration of the cycle detection means 4 in the first embodiment.
FIG. 7 is a block diagram showing another configuration of the cycle detection means 4 in the first embodiment.
FIG. 8 is a timing chart showing the operation of the cycle detection means 4 shown in FIG.
FIG. 9 is a block diagram showing another configuration of the cycle detection means 4 in the first embodiment.
FIG. 10 is a block diagram showing a configuration of a second embodiment of an optical disk reproducing device according to the present invention.
11 is a graph showing frequency characteristics and signal frequency bands of the waveform equalizing means 1. FIG.
12 is a block diagram showing a configuration of waveform equalizing means 1. FIG.
13 is a block diagram showing another configuration of the waveform equalizing means 1. FIG.
FIG. 14 is a graph of normal output values of the cycle detection means 4;
FIG. 15 is a graph in which an offset is given to the output value of the cycle detection means 4;
FIG. 16 is a diagram showing a configuration of a conventional optical disc playback apparatus.
FIG. 17 shows recording data and waveforms of a conventional optical disc playback apparatus.
FIG. 18 shows the presence / absence of signal recording and a tracking error signal.
FIG. 19 is a diagram showing input / output characteristics of a voltage controlled oscillator 21 according to the present invention.
[Explanation of symbols]
1 Waveform equalization means
2 Binarization means
3 Dropout detection means
4 Period detection means
5 Phase-locked loop means
6 Synchronization means
21 Voltage controlled oscillator
22 Phase comparator
23 Charge pump
24 loop filter
27 Disc motor drive means
28 Optical disc
29 Reproduction means

Claims (3)

Binarization means for converting the reproduction signal into a digital signal by binarizing at a predetermined level;
Period detection means for detecting and outputting the length of the specific pattern itself contained in the digital signal with a high-frequency fixed clock;
Phase-locked loop means having a free-running period, controlling the free-running period to be substantially proportional to the reciprocal of the length of the specific pattern itself, and reproducing and outputting a clock component of the digital signal; An optical disc playback apparatus comprising:
The period detecting means includes a first counting means for counting a first interval between successive rising edges of the digital signal, and a second count for counting a second interval between successive falling edges of the reproduction signal. Means,
An optical disc reproducing apparatus , wherein a minimum value or a maximum value including both the first interval and the second interval is calculated for each predetermined period and output as a period of the specific pattern . Binarization means for converting the reproduction signal into a digital signal by binarizing at a predetermined level;
Period detection means for detecting and outputting the length of the specific pattern itself contained in the digital signal with a high-frequency fixed clock;
Phase-locked loop means having a free-running period, controlling the free-running period to be substantially proportional to the reciprocal of the length of the specific pattern itself, and reproducing and outputting a clock component of the digital signal; An optical disc playback apparatus comprising:
The period detecting means includes
Counting means for continuously counting the pulse width and pulse interval pattern of the digital signal;
Maximum value storage means for updating and holding the maximum value of the count value counted by the counting means within a predetermined period; and
Adding means for adding and holding the maximum value held by the maximum value storage means when the update is performed and the count value counted next by the counting means;
Optical disk reproducing apparatus according to claim Rukoto a maximum value detecting means for outputting a sum value held in said adding means for each of the predetermined time period as the length of the specific pattern. Binarization means for converting the reproduction signal into a digital signal by binarizing at a predetermined level;
Period detection means for detecting and outputting the length of the specific pattern itself contained in the digital signal with a high-frequency fixed clock;
Phase-locked loop means having a free-running period, controlling the free-running period to be substantially proportional to the reciprocal of the length of the specific pattern itself, and reproducing and outputting a clock component of the digital signal; An optical disc playback apparatus comprising:
The period detection means is a counting means for continuously counting the pulse width and pulse interval pattern of the digital signal;
Holding means for holding the counting result obtained immediately before by the counting means;
Adding means for obtaining a sum of two consecutive pulse widths and pulse intervals of the digital signal by adding the output of the counting means and the output of the holding means;
First determining means for calculating a minimum value of the output of the adding means for each predetermined period;
Second determining means for calculating a maximum value of the output of the counting means for each predetermined period;
Estimating means for estimating the output range of the second determining means based on the output of the first determining means;
When the output of the second determining means is within the estimated range, the output of the second determining means is output. When the output of the second determining means is outside the estimated range, the output of the second determining means is output. prohibited, and an optical disk reproducing apparatus according to claim Rukoto a prohibiting means for holding an output of said second determining means obtained immediately before.

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