JPH08287623A - Optical disk reproducing device - Google Patents

Abstract

PURPOSE: To surely perform phase synchronization pull-in at a high speed. CONSTITUTION: This device is provided with a waveform equalization means 1 emphasizing a prescribed frequency band of a regenerative signal, a binarization means 2 converting the emphasized regenerative signal into a digital signal by binarizing the regenerative signal emphasized by the waveform equalization means 1 at a prescribed level, a period detection means 4 detecting and outputting a specified pattern period included in the digital signal and a phase locked loop means 5 having a free-running period. The means 5 controls the free-running period based on the output of the period detection means 4 so that the free-running period matches, with the period of the clock component of the digital signal substantially, and outputs a regenerative clock signal by regenerating the clock component of the digital signal. A synchronization means 6 outputs the digital signal as the regenerative data by synchronizing it with the regenerative clock signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a linear velocity period from a reproduction signal of a digitally recorded optical disk medium and controls a phase locked loop or a waveform equalizer to pull in a phase locked loop for clock reproduction. The present invention relates to an optical disk reproducing device that facilitates the operation.

[0002]

2. Description of the Related Art Compact discs (Compact Di
As shown in sk), a recording method in which the linear velocity is constant and the recording density on the recording medium is uniform is often used. When phase synchronization is performed on an optical disc reproduction signal that is digitally modulated and recorded by performing mark width modulation so that the linear recording density becomes constant, the frequency of the clock component of the reproduction signal and the clock generation circuit of the phase locked loop circuit If the pulling-in is not started in the state where the frequencies are close to each other, there is a high possibility that the pulling-in is performed to a frequency different from the clock frequency of the reproduction signal. To avoid this, 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 rotation speed and the free-running frequency of the phase-locked loop, the normal phase It enables synchronization pull-in.

For example, there is a disc reproducing system as shown in FIG. Data as shown in FIG. 17A is recorded on the optical disc 28 so that the linear recording density becomes constant. The recorded data is data in which consecutive 0s or 1s are regulated to 3 or more and 11 or less. For example, EFM (Eight to Forteen Mo)
modulation). The reproduction signal obtained by reproduction by the reproduction means 29 exhibits low-pass filtering characteristics, and the amplitude decreases as the frequency component becomes higher. Therefore, in order to correct this, the waveform equalization means 1 emphasizes the high frequency range. The reproduction signal (FIG. 17B) emphasized in the high frequency range is set to 2
The binarizing means 2 binarizes the signal at a predetermined slice level and converts it into a binarized signal (FIG. 17C). Here, although the optimum value of the slice level changes due to variations in the recording mark size and the like, it is automatically adjusted according to the DC component of the reproduction signal.

When there is a binary signal input, the phase with the output of the voltage controlled oscillator 21 is compared with the phase comparator 22, and a phase error voltage corresponding to the phase difference between the two is generated. The charge pump 23 extracts or absorbs 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 the input binary signal (see FIG.
7 (c)) generates a clock (FIG. 17 (d)) that is in phase with the clock component. And the synchronization means 6
In, the binary signal (FIG. 17C) is synchronized with the synchronous clock (FIG. 17D), and the synchronous clock and the binary signal data synchronized with the synchronous clock are output.

However, with the above-mentioned phase locked loop alone, 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, there is a possibility of pseudo pull-in. is there. 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, it is possible to reliably pull in the phase synchronization. If it is out of this range, normal retraction may not be possible. Therefore the first
11T outside the phase-locked loop as an auxiliary means for pulling in
A binarized signal is provided by providing the cycle detecting means 25 (FIG. 17 (c)).
Of 11 consecutive 0 recording or 1 recording patterns are measured, the oscillation frequency of the voltage controlled oscillator becomes lower if the measured value is longer than the steady value, and conversely if the measured value is short, the voltage controlled oscillator 21 A predetermined current is injected or drawn into the loop filter from the charge pump so that the oscillation frequency of the signal becomes high. 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, the phase synchronization pull-in can be performed without pseudo synchronization.

Also, 6T is used as a second pull-in assisting means.
A binarized signal is provided by providing the cycle detection means 26 (FIG. 17C).
Existing in (000111) or (111000)
The clock of the binarized signal is obtained by measuring the time period of the recording pattern, and if the measured value is larger than the steady value, the motor rotation speed is increased, and conversely, if the measured value is short, the motor rotation speed is slowed to approach the steady linear speed. The pseudo pull-in is eliminated by making the frequency of the component almost match the free-running oscillation frequency of the voltage controlled oscillator. Where (000111)
Alternatively, the (111000) recording pattern period corresponds to the period of the rising interval or the falling interval of the binarized signal, and even if the binarized slice level in the binarizing means 2 fluctuates, it hardly affects the detection period. Strong detection is possible even for disturbances such as search seek. On the other hand, the 11T cycle detecting means 25, which is the first pull-in assisting means, detects the cycle from the rising edge to the falling edge or from the falling edge to the rising edge, so that correct detection cannot be performed if the binarized level fluctuation occurs, but it is detected. Since the cycle is long, the deterioration of accuracy is small.

When the information recorded on the optical disk medium is searched at high speed to reproduce the data, it is required to speed up the phase synchronization pull-in for the disk reproduction signal.

[0008]

[Problems to be Solved by the Invention] However, the above-mentioned 6
In the method of detecting the linear velocity cycle of the optical disk and controlling the disk rotation speed like the T cycle detection, it takes time to settle the rotation speed, and it takes time to pull in the phase synchronization for clock reproduction. Become. Also,
Like the 11T period detection described above, the pulse width or pulse interval included in the modulation signal is detected and compared with the steady value, and a predetermined current is injected or drawn from the charge pump into the loop filter to obtain a voltage controlled oscillator. The method of controlling the free-running frequency is binary control of increasing or decreasing the frequency, and the accuracy is not good.

An object of the present invention is to solve the above-mentioned drawbacks, to quantitatively detect the linear velocity cycle of an optical disk, and based on this, the free-running frequency of the synchronous clock generator of the phase synchronization means is
The phase synchronization pull-in is performed easily and at high speed by controlling so that the frequency of the clock component of the signal obtained by binarizing the reproduced signal is almost the same. It is an object of the present invention to provide an optical disk reproducing apparatus in which the frequency of detection is increased by using as the detection information and the reliability of the optical disk is improved by detecting the loss of the reproduction signal and holding the linear velocity detection output.

[0010]

An optical disk reproducing apparatus of the present invention comprises a waveform equalizing means for emphasizing a predetermined frequency band of a reproduced signal and a reproduced signal emphasized by the waveform equalizing means at a predetermined level. Binarizing means for converting the emphasized reproduction signal into a digital signal by converting the value into a digital signal, cycle detecting means for detecting and outputting a cycle of a specific pattern included in the digital signal, and a free-running cycle. Phase-locked loop means for controlling the free-running cycle based on the output of the cycle detecting means so that the free-running cycle substantially matches the cycle of the clock component of the digital signal. Phase-locked loop means for outputting a reproduced clock signal by reproducing a clock component, and the same for outputting as reproduced data by synchronizing the digital signal with the reproduced clock signal. And a means, thereby the objective described above being achieved.

The period detecting means may count a pulse width or a pulse interval of the specific pattern of the digital signal by using a clock and hold the counted value by stopping the clock by an external signal. .

The external signal may be a disc defect detection signal.

The cycle detecting means counts a pulse width or a pulse interval of the specific pattern of the digital signal using a clock, and holds the measured value when the counted value falls within a predetermined range. May be.

The cycle detecting means counts a first interval between rising edges of the reproduction signal and a second counting means counts a second interval between falling edges of the reproduction signal. And the minimum value or the maximum value of the sum of the first interval counted by the first counting means and the second interval counted by the second counting means is calculated for each predetermined period, and the specific pattern is calculated. It may be provided with a determining means for outputting as the period.

The cycle detecting means includes a counting means for continuously counting the pulse width or the pulse interval of the digital signal, a holding means for holding the counting result obtained immediately before by the counting means, and a counting means of the counting means. An adding means for obtaining the sum of two consecutive pulse widths or pulse intervals of the digital signal by adding the output and the output of the holding means, and the minimum value or the maximum value of the output of the adding means for each predetermined period. A determining unit that calculates a value and outputs the value as the cycle of the specific pattern may be provided.

The cycle detecting means holds counting means for continuously counting the pulse width or pulse interval of the digital signal, and the maximum value of all the counted values obtained by the counting means within a predetermined period. Maximum value storage means for obtaining the maximum value by the maximum value storage means updated each time a new maximum value is detected, and the maximum value held by the maximum value storage means and the counting means. Adding means for obtaining an added value in response to the update of the maximum value in the maximum value storage means by adding the next count value, and outputting the added value as the cycle of the specific pattern for each predetermined period Maximum value detecting means for

The period detecting means includes a counting means for continuously counting the pulse width or the pulse interval of the digital signal, a holding means for holding the counting result obtained immediately before by the counting means, and a counting means of the counting means. An addition means for obtaining the sum of two consecutive pulse widths or pulse intervals of the digital signal by adding the output and the output of the holding means, and a minimum value of the output of the addition means for each predetermined period. Based on the output of the first deciding means, the second deciding means for calculating the maximum value of the output of the counting means for each predetermined period, and the range of the output of the second deciding means. If the output of the estimating means and the second determining means is within the estimated range of the output of the second determining means, the second
The output of the deciding means is output as it is, and when the output of the second deciding means is outside the estimated range of the output of the second deciding means, the output of the second deciding means is prohibited and the output is obtained immediately before. It may be provided with a prohibition means for holding the value.

The predetermined frequency band emphasized by the waveform equalizing means may vary so as to be inversely proportional to the output of the cycle detecting means.

At the start of the reproducing operation, the predetermined frequency band emphasized by the waveform equalizing means is temporarily shifted so as to be higher than the frequency band emphasized by the waveform equalizing means at the steady reproduction. Good.

When seeking from the inner circumference to the outer circumference, the predetermined frequency band emphasized by the waveform equalizing means is temporarily higher than the frequency band emphasized by the waveform equalizing means during steady reproduction. It may be shifted.

The cycle detecting means may count the cycle of the specific pattern of the digital signal using a clock, and add or subtract an offset value less than the resolution of the counted result to output the offset value.

The frequency of the clock may be set so that the minimum resolution for setting the free-running frequency of the phase locked loop means falls within the pull-in range of the phase locked loop means.

With the above structure, the free running frequency of the phase locked loop means is detected by detecting the linear velocity period during reproduction of the optical disk.
By controlling so that the reproduced signal is binarized and digitized to substantially match the frequency of the clock component, the phase synchronization pull-in can be performed reliably and at high speed, and the lack of the reproduced signal can be detected. The reliability can be improved by additionally having a function of holding the linear velocity detection output.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical disk reproducing apparatus according to the present invention will be described below with reference to the drawings.

(Embodiment 1) Embodiment 1 of the optical disk reproducing apparatus according to the present invention will be described with reference to the block diagram of FIG.

In FIG. 1, the optical disk reproduction signal is corrected by the waveform equalizing means 1 so as to emphasize high frequencies. This signal is binarized by the binarizing means 2 at a predetermined level and converted into a digital signal.

Next, the binarizing means 2 in the cycle detecting means 4
The period of a specific pattern of the binarized digital signal is counted by a high-frequency clock. It can be measured with the time resolution of one cycle of the high frequency clock. When counting is performed at both edges of the high frequency clock, the time resolution of ½ cycle is possible.

Since the result obtained by the cycle detecting means 4 has information inversely proportional to the linear velocity, that is, clock cycle information included in the reproduction signal, the free-running frequency of the phase locked loop means 5 has the reproduction signal based on this. Set so that it almost matches the clock frequency.

Here, the phase locked loop means 5 includes the phase comparator 22, the charge pump 23, and the phase pump 22 as described in the conventional example.
It is composed of a loop filter 24 and a voltage controlled oscillator 21. Generally, the input / output characteristic of the voltage controlled oscillator 21 is designed so that it can be varied within a range of ± Δf depending on the input voltage, with the oscillation frequency at the time of steady reproduction of the optical disk as the center frequency f0 as shown by the solid line in FIG. It In this case, the frequency of the clock component included in the digital signal obtained from the binarizing means 2 and the voltage controlled oscillator 2 in a state where the disk rotation is not settled, such as at the time of starting the reproduction of the optical disk or immediately after the seek.
Since the oscillating frequency of 1 is far apart, it falls into a state where phase synchronization is not possible (hereinafter referred to as a pseudo pull-in state). Therefore, it was necessary to perform motor control and wait for settling near steady rotation before the phase synchronization pull-in.

However, since the detection result obtained by the period detecting means 4 has the clock period information contained in the reproduced signal,
This reciprocal is obtained and converted into frequency information, and the central frequency f0 of the voltage controlled oscillator 21 is adaptively controlled as shown by the broken line in FIG. If the frequency of the clock component of the obtained digital signal is made to substantially match, the synchronous pull-in can be completed at high speed without waiting for the motor rotation to settle.

In this way, since the frequency of the clock component of 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, it is possible to normally pull in without pseudo pulling in. is there. Since the setting of the free-running frequency is performed electrically, it is possible to shorten the time from the synchronization of the rotation of the disk motor to the synchronous pull-in to the start of the synchronous pull-in.
Further, since the free-running frequency is set with high resolution, the free-running frequency of the phase locked loop means 5 almost matches the clock frequency of the reproduced signal, so that the time required for the frequency pull-in process can be shortened.

With the reproduction clock signal obtained by the phase locked loop means 5, the digital signal obtained by the binarization means 2 is synchronized by the synchronization means 6 and output as reproduction data.

The cycle detecting means 4 may stop the detection operation by stopping the clock and hold the detection value.

For example, as shown in FIG. 2, the supply of the high frequency clock may be turned on / off by the dropout detection signal of the disk. As a result, it is possible to prevent the detected value from being disturbed due to a defect of the disk.

The cycle detecting means 4 described in the first embodiment is composed of the specific pattern counting means 106 and the output holding means 7 as shown in FIG. 3, and the output holding means 7 is the count value of the specific pattern counting means 106. The output is monitored, and is output as it is while the detection result is out of the predetermined range, 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 cycle detecting means 4. It may be one. For example, immediately after performing a seek to the inner circumference side, a large cycle detection value is output as shown in FIG. 4, but the free-running frequency of the phase locked loop means 5 is changed according to this value, and the clock included in the reproduction signal is changed. By making the frequency substantially match, the synchronization pull-in is performed immediately after the seek. Then, when the disk motor rotation settles to a steady state after the synchronous pull-in is performed and the value detected by the cycle detecting means 4 falls within a predetermined value, the output of the cycle detecting means 4 is fixed.

As a result, it is possible to prevent an erroneous value from being detected by the cycle detection due to a disturbance such as a disk defect during steady reproduction, and to prevent the free-running frequency of the phase-locked loop 4 from changing so that the sync-clock output frequency fluctuates. Later stability can be improved.

In the case of a CD or the like, a continuous pattern of 11T and 11T (where T is the minimum recording unit) called a sync pattern is recorded in order to synchronize at a constant cycle. This pattern is a maximum length pattern that does not exist elsewhere in the data, and is characterized in that it always exists once in every fixed period. In such a case, the disc reproduction linear velocity information can be obtained by measuring the rising time of the data edge or the rising time or the falling time of the data edge at every constant detection time and obtaining the maximum value.

Therefore, the cycle detecting means 4 described in the first embodiment includes the first counting means 8 for counting the interval between the reproduced signal rising portions of the digital signal output from the binarizing means 2 as shown in FIG. , A second counting means 9 for counting the interval of the falling portion, and an output result of the first counting means 8 for each predetermined period and a second
A determination means 10 for outputting a minimum value (or maximum value) including both of the counting results of the counting means 9, and determining the minimum value (or maximum value) of the sum of two consecutive pulse widths or pulse intervals. May be As a result, the frequency of counting can be doubled compared to counting only the rising edge interval or the falling edge interval.

The period detecting means 4 described in the first embodiment is a counting means 11 for synchronizing a digital signal with a high frequency clock and continuously counting the pulse width or the pulse interval as shown in FIG. The holding means 12 for holding the counting result obtained immediately before by the counting means 11, and the counting result output of the counting means 11 and the holding data output of the holding means 12 are input, and two consecutive pulse widths or pulses counted The adding means 14 for adding the interval results and the judging means 10 for obtaining the minimum value (or maximum value) of the output of the adding means for each predetermined period are constituted by the minimum value of the sum of two consecutive pulse widths or pulse intervals ( Alternatively, the maximum value) may be obtained. The configuration shown in FIG. 5 requires two counting means, but this method requires only one counting means, so the circuit scale becomes small.

The period detecting means 4 described in the first embodiment is a counting means 11 for synchronizing a digital signal with a high frequency clock and continuously counting the pulse width or the pulse interval as shown in FIG. The holding value is reset every predetermined detection cycle and is updated each time the maximum value of the count value of the counting means is detected from the beginning of the predetermined detection cycle, and the maximum value storage means 13 for holding this and the maximum value storage means 13 and the maximum value storage means are held. When the stored maximum 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 adding means 14 holds and outputs this value, and at the end of the predetermined detection cycle. The maximum cycle output means 15 for outputting the output value of the adding means 14 as the cycle detection result, and outputs the maximum pulse width or pulse interval and the next maximum pulse width or pulse interval. There may be. When a specific pulse width or pulse interval is located after the maximum pulse width or maximum pulse interval, the detection accuracy can be improved.

Each time the maximum pulse width appears as shown in FIG. 8, 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 addition means 14 to hold this value. To do. The value held at the fixed cycle is output and the value held at the same time is reset.

For example, when the maximum pulse width or pulse interval included in the reproduced signal has a width of 14T and the next pattern is always determined to be 4T, the detection accuracy is 18 by adding these and detecting. / 14 times.

The period detecting means 4 described in the first embodiment is a counting means 11 for synchronizing a digital signal with a high frequency clock and continuously counting the pulse width or the pulse interval as shown in FIG. The holding means 12 which holds the previous counting result, the counting result output of the counting means 11 and the holding data output of the holding means 12 are input, and two counted pulse widths or pulse interval results are added. The adding means 14, the first determining means 16 for obtaining the minimum value of the output of the adding means 14 for each predetermined period, and the second determining means 17 for obtaining the maximum value of the output of the counting means 11 for each predetermined period.
And an estimating means 18 for estimating the output range of the second determining means 17 by using the output of the first determining means 16 as an input, and an output of the second determining means 17 and an output of the estimating means 18 as inputs and usually the first If the output of the second judging means 17 is out of the range estimated by the estimating means 18, the output of the second judging means 17 is prohibited and the output value immediately before is output. When the output of the second judging means 17 is held, and the output of the second judging means 17 falls within the range estimated by the estimating means 18, the output of the second judging means 17 is bypass-outputted again. A high second judgment means output is output, and the output is held when it is judged that the second judgment means output may be incorrect based on the first judgment means output with few detection errors. May be First
The determination means 16 has a smaller detection error rate than the second determination means 17, but the detection accuracy is higher when the second determination means is higher, and the detection accuracy is high, and the detection accuracy is high. Cycle detection is possible.

For example, it is assumed that the optical disk is EFM-modulated and recorded, that is, a pattern having a width of 3T to 11T is recorded at intervals of T. Then, the first determining unit detects the [3T, 3T] pattern having the minimum value of the recording pattern, and the second determining unit has the maximum value of the recording pattern [1.
It is assumed that the [1T] pattern is detected. Although any of the determination means obtains the disc reproduction linear velocity information, the first detection means has low detection accuracy but high reliability.
When the second detecting means has a characteristic that the detection accuracy is high but the reliability is low, the output value of the second judging means is constantly predicted from the highly reliable first judging means (for example, a value obtained by multiplying by 11/6). If the second judgment means output value is close to the predicted value, the second judgment means output value is output as it is, and if it is outside the predicted value, it is regarded as a detection error. If the previous value is retained, both accuracy and reliability can be achieved.

Further, here, a method of adding two consecutive pulse widths or pulse interval results to obtain the minimum value for each predetermined period is used, but as shown in FIG. It is also possible to independently count the intervals of the falling portions and obtain the minimum value including both for each predetermined period. Further, the input of the second judging means 17 may be one which obtains the maximum value of the output of the adding means 14 every predetermined period.

(Second Embodiment) 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 emphasize the high frequency range. The high-frequency emphasized signal is binarized by the binarizing means 2 at a constant level and converted into a digital signal.

Next, the binarizing means 2 in the cycle detecting means 4
The period of a specific pattern of the binarized digital signal is counted by a high-frequency clock. Here, the time length of the specific pattern can be measured with the minimum resolution of one cycle of the high frequency clock. When counting with both edges of the high frequency clock, the resolution is 1/2 cycle.

When the reproduction linear velocity is high, the reproduction signal band at the time of reproduction of the optical disk is widened in proportion to this.
Conversely, if the linear velocity is slow, it becomes narrow. Further, the cycle detecting means 4
The output of is the linear velocity cycle information and is a value inversely proportional to the linear velocity. As shown in FIG. 10, the reciprocal of the linear velocity cycle detection result output from the cycle detector 4 is calculated as the reciprocal calculator 20.
The waveform equalization can be optimized by calculating the frequency information by converting the high frequency emphasis band of the waveform equalizer 1 so as to be proportional to the frequency information.

Further, since the result obtained by the period detecting means 4 has linear velocity information, that is, clock frequency information contained in the reproduced signal, the free-running frequency of the phase locked loop means 5 is based on this, the clock contained in the reproduced signal. Set it so that it almost matches the frequency. In this way, since the frequency of the clock component of the digital signal obtained from the binarizing means 2 and the synchronous clock frequency of the phase locked loop means 5 are close to each other, it is possible to normally pull in without pseudo pulling in. In this way, the reproduced clock signal obtained by the phase locked loop means 5 synchronizes the digital signal obtained by the binarizing means 2 by the synchronizing means 6 and outputs it as reproduced data.

Further, the phase-locked loop means 5 receives the operation output of the reciprocal number operation means 20 as an input, sets the free-running frequency of the phase-locked loop in proportion to this, and sets the free-running frequency to approximately the clock frequency of the binarized digital signal. It may be a match.

In the first or second embodiment,
When the frequency characteristic of the high frequency emphasis of the waveform equalizing means 1 exhibits the characteristic as shown in FIG. 11A, if the linear velocity of the optical disk is faster than the steady state, the signal frequency band is equal to that of the waveform equalizing means. There is a possibility of exceeding the pass band (Fig. 1
CLV speed of 1). Since the disk rotation is not in a steady state when the disk reproduction is started, the frequency band of the reproduction signal may exceed the pass band of the waveform equalizing means. Therefore, the waveform equalizer 1 obtains the reproduction start signal as an external signal as shown in FIG. 12 to force the high-frequency emphasis band to be higher than that in normal reproduction as shown in FIG. 11B. It is possible to prevent the loss of the signal frequency component by shifting to the band side.

In the first or second embodiment,
When the frequency characteristic of the high-frequency emphasis of the waveform equalizing means 1 exhibits the characteristic as shown in FIG. 11A, if the linear velocity of the optical disk is faster than the steady state, the frequency band of the reproduction signal is equal to the waveform equalizing means. There is a possibility that it will exceed the pass band of (the state of CLV speed in FIG. 11). Especially, when seeking from the inner circumference to the outer circumference of the disk, it takes time for the rotation of the motor to converge to the steady rotation, so that the signal frequency band may exceed the pass band of the waveform equalizer immediately after the seek. Is high. Therefore, the waveform equalizer 1 obtains the seek signal from the inner circumference to the outer circumference of the optical disc as an external signal as shown in FIG. 13 to force the high-frequency emphasis band as shown in FIG. 11 (B). In addition, the loss of the signal frequency component may be prevented by shifting to the higher frequency side than that during normal reproduction.

In the cycle detecting means 4, the cycle of the specific pattern of the digital signal binarized by the binarizing means 2 is counted by a high frequency clock. Here, the time length of the specific pattern is measured with the minimum 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 ½ cycle.

FIG. 14 shows the relationship between the time length of the specific pattern which is the input of the cycle detecting means 4 and the detection output of the cycle detecting means 4 by a solid line. If the detection method of the cycle detecting means 4 is a method of counting with a high frequency clock, such a stepwise change occurs. The broken line is an ideal detection curve. The error from the solid line and the broken line is at most 1 LSB corresponding to the least significant bit of the counter. On the other hand, as shown in Fig. 15, (1/2) L for the output value
The error from the broken line can be suppressed to the maximum (1/2) LSB by adding the SB offset. If the offset amount here is 1 LSB or less, (1/2) LS
Other than B may be used.

The dropout detection means 3 described in the first and second embodiments binarizes the tracking error signal generated when the recording portion of the optical disk is traversed as shown in FIG. It is also possible to determine when the recording unit is traversed and use this as a part of the missing information of the reproduction signal.

In the above embodiments, 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 is reproduced at a reproduction rate. The reproduction does not have to be constant linear velocity because it can be adaptively changed according to

[0057]

According to the present invention, the free-running frequency of the phase locked loop means by detecting the linear velocity period during reproduction of the optical disk is set to the frequency of the clock component of the signal obtained by binarizing the reproduced signal and digitizing it. It is possible to perform the phase lock pull-in surely and at high speed by controlling so that they substantially match, and also to improve reliability by also having a function to detect the loss of the reproduction signal and hold the linear velocity detection output. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of an optical disk reproducing device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a cycle detecting means 4 in the first embodiment.

FIG. 3 is a block diagram showing another configuration of the cycle detecting means 4 in the first embodiment.

FIG. 4 is a graph showing an output value of cycle detection means 4 in the first embodiment.

FIG. 5 is a block diagram showing another configuration of the cycle detecting means 4 in the first embodiment.

FIG. 6 is a block diagram showing another configuration of the cycle detecting means 4 in the first embodiment.

FIG. 7 is a block diagram showing another configuration of the cycle detecting means 4 in the first embodiment.

8 is a timing chart showing the operation of the cycle detecting means 4 shown in FIG.

FIG. 9 is a block diagram showing another configuration of the cycle detecting 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.

FIG. 11 is a graph showing the frequency characteristic and the signal frequency band of the waveform equalizer 1.

FIG. 12 is a block diagram showing a configuration of a waveform equalizing means 1.

FIG. 13 is a block diagram showing another configuration of the waveform equalizing means 1.

FIG. 14 is a graph of a normal output value of the cycle detecting means 4.

FIG. 15 is a graph in which an output value of the cycle detecting means 4 is provided with an offset.

FIG. 16 is a diagram showing a configuration of a conventional optical disc reproducing apparatus.

FIG. 17 shows recording data and waveforms of a conventional optical disc reproducing 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 the voltage controlled oscillator 21 according to the present invention.

[Explanation of symbols]

 1 waveform equalizing means 2 binarizing means 3 dropout detecting means 4 cycle detecting means 5 phase locked loop means 6 synchronizing means 21 voltage controlled oscillator 22 phase comparator 23 charge pump 24 loop filter 27 disk motor driving means 28 optical disk 29 Reproduction means

Claims (13)

[Claims] 1. A waveform equalizer that emphasizes a predetermined frequency band of a reproduced signal, and a reproduced signal that is emphasized by the waveform equalizer is binarized at a predetermined level to obtain the emphasized reproduced signal. To a digital signal, a cycle detecting means for detecting and outputting a cycle of a specific pattern included in the digital signal, and a phase locked loop means having a free running cycle, the free running cycle Output the reproduced clock signal by controlling the free-running period based on the output of the period detecting means so that the clock component substantially matches the period of the clock component of the digital signal and reproducing the clock component of the digital signal. An optical disk reproducing apparatus comprising: a phase-locked loop means for synchronizing the digital signal with the reproducing clock signal to output reproduced data as synchronizing data. 2. The cycle detecting means counts the pulse width or pulse interval of the specific pattern of the digital signal using a clock, and holds the counted value by stopping the clock by an external signal. The optical disc reproducing apparatus according to claim 1. 3. The optical disc reproducing apparatus according to claim 2, wherein the external signal is a disc defect detection signal. 4. The cycle detecting means counts the pulse width or pulse interval of the specific pattern of the digital signal using a clock, and when the counted value falls within a predetermined range, the measured value is output. The optical disk reproducing apparatus according to claim 1, which holds the optical disk. 5. The period detecting means counts a first interval between rising edges of the reproduction signal, and a second counting means counts a second interval between falling edges of the reproduction signal. Counting means, calculating a minimum value or a maximum value of the sum of the first interval counted by the first counting means and the second interval counted by the second counting means at predetermined intervals, The optical disc reproducing apparatus according to any one of claims 1, 2 and 3, further comprising: determining means for outputting the cycle of the specific pattern. 6. The cycle detecting means includes a counting means for continuously counting the pulse width or the pulse interval of the digital signal, a holding means for holding a counting result obtained immediately before by the counting means, and the counting means. Adder means for obtaining the sum of two consecutive pulse widths or pulse intervals of the digital signal by adding the output of the means and the output of the holding means; and the minimum value of the output of the adder means for each predetermined period. The optical disc reproducing apparatus according to any one of claims 1, 2 and 3, further comprising: determining means for calculating a maximum value and outputting it as a cycle of the specific pattern. 7. The period detecting means includes a counting means for continuously counting the pulse width or the pulse interval of the digital signal, and a maximum value of all count values obtained by the counting means within a predetermined period. Is a maximum value storage means for holding
The maximum value is obtained by adding the maximum value storage means updated each time a new maximum value is detected, and the maximum value held by the maximum value storage means and the next count value obtained by the counting means. Due to
The maximum value storage means includes an addition means for obtaining an addition value in response to the update of the maximum value, and a maximum value detection means for outputting the addition value as a cycle of the specific pattern for each predetermined period, The optical disc reproducing apparatus according to claim 1, 2, or 3. 8. The cycle detecting means comprises a counting means for continuously counting the pulse width or the pulse interval of the digital signal, a holding means for holding the counting result obtained immediately before by the counting means, and the counting means. Adder means for obtaining the sum of two consecutive pulse widths or pulse intervals of the digital signal by adding the output of the means and the output of the holding means; and the minimum value of the output of the adder means for each predetermined period. A first determining means for calculating, a second determining means for calculating the maximum value of the output of the counting means for each predetermined period, and an output of the second determining means based on the output of the first determining means. If the output of the estimating means for estimating the range and the second determining means is within the estimated range of the output of the second determining means, the output of the second determining means is output as it is, and the output of the second determining means is output. The output of the determining means is the second The prohibition means for prohibiting the output of the second determination means and holding the value obtained immediately before when the output of the constant means is out of the estimated range. 2. The optical disk reproducing device according to any one of 1. 9. The optical disk reproducing apparatus according to claim 1, wherein the predetermined frequency band emphasized by the waveform equalizing means changes so as to be inversely proportional to the output of the cycle detecting means. 10. When the reproduction operation is started, the predetermined frequency band emphasized by the waveform equalizer is temporarily shifted so as to be higher than the frequency band emphasized by the waveform equalizer during steady reproduction. 9. The optical disc reproducing apparatus according to claim 1, which is performed. 11. When seeking from the inner circumference to the outer circumference, the predetermined frequency band emphasized by the waveform equalizer is temporarily set to be higher than the frequency band emphasized by the waveform equalizer during steady reproduction. 9. The optical disk reproducing apparatus according to claim 1, wherein the optical disk reproducing apparatus is shifted. 12. The cycle detection means counts the cycle of the specific pattern of the digital signal using a clock, and adds or subtracts an offset value less than the resolution of the counted result to output the offset value. 9. The optical disc reproducing device according to any one of 8 and 8. 13. The frequency of the clock is set such that the minimum resolution for setting the free-running frequency of the phase locked loop means is within the pull-in range of the phase locked loop means. 2. The optical disk reproducing device according to any one of 1.