JP2001184804A - Clock generation circuit of optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clock generation circuit for an optical disk drive capable of being constructed without using a plurality of PLL circuits, a plurality of VCOs or delay lines, suppressing the power consumption of the entire drive low without considering a temperature characteristic, variation, etc., that are generated and simplifying circuit mounting. SOLUTION: A reproduced clock signal pattern is subjected to A/D conversion, a phase difference detector 6 detects phase difference between the sampling clock of an A/D converter 5 and a signal obtained by performing frequency dividing of the sampling clock with a prescribed frequency division ratio, a PLL loop consists of a loop filter 7, a D/A converter 8 and a VCO 9, the output clock of the VCO 9 is made to synchronize with the reproduced clock signal pattern, an A/D converter 12 performs A/D conversion of the data of a reproducing and recording area on the basis of a sampling clock from the output clock of the VCO 9, a phase difference detector 14 detects phase difference between the data of the reproducing and recording area and the output clock of the VCO 9, and a signal accumulatively added by an integrator 15 is added to the output of the detector 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus which uses a clock signal pattern formed in advance on an optical disk such as a sample servo, and generates a sample servo pattern of the optical disk and a clock for detecting reproduced data in a recording area. The present invention relates to a clock generation circuit.

[0002]

2. Description of the Related Art In recent years, a so-called magneto-optical disk is often used as a recording medium, for example, because data recorded with a large recording capacity can be stored semi-permanently and the recorded data can be easily rewritten. It is becoming. As a tracking servo method for the magneto-optical disk, there is a sample servo method using a clock signal pattern (clock pit) formed in advance on an optical disk such as a so-called sample servo in an optical disk device.

FIG. 2 shows an example of a magneto-optical disk employing the above-described sample servo system.
That is, in this example, data is recorded using one sector as one recording unit. One sector includes a plurality of predetermined segments, and one segment includes a servo area 41 and a data area 43. In the servo area 41, a pair of so-called wobble pits for obtaining a tracking error signal and a clock pit for synchronizing the segment are previously recorded as a sample servo pattern.

As shown in FIG. 2, one sector is composed of a predetermined number of segments, and one segment is composed of a servo area 41 and a data area 42 (in the first segment of the sector, information such as addresses is recorded). Header area 43). The servo area 41
Are provided in advance with a so-called pair of wobble pits for obtaining a tracking error signal and clock pits for synchronizing recording data as a sample servo pattern, and the data area 42 utilizes a magneto-optical effect. Then, the recording data is recorded. The data area 42 of the second segment is a reference clock pattern area in which a reference clock, which is a synchronization signal used for accurately reproducing the recording data recorded in the sector, is recorded. That is, in the reference clock pattern area 42, a signal (reference clock) of the highest recording frequency is recorded as a fixed pattern. The recording in the data area 42 is performed continuously as a series of operations. That is, recording is performed at the same time and under the same conditions.

The magneto-optical disk described below is
The disk surface is divided into a plurality of areas (zones), and the angular velocity at the time of disk rotation differs for each zone, so-called zone CA.
The V method is employed, and therefore, the phase difference between the phase of the sample servo clock and the phase of the reference clock differs for each zone. When recording data on such a magneto-optical disk, the magneto-optical disk is rotated at a constant angular velocity (CAV) by a spindle motor, for example. Then, a tracking error signal is formed from the wobble pits of the sample servo pattern, tracking servo is performed based on the tracking error signal, and one of the magneto-optical disks is synchronized while synchronizing with the sample servo clock formed from the clock pit. A laser beam is applied to the magneto-optical disk from one surface side, and a magnetic field modulated with recording data is applied to a location irradiated with the laser beam from the other surface side of the magneto-optical disk.

The portion irradiated with the laser beam is heated to the so-called Curie temperature and loses coercive force.
Since a magnetic field modulated with the recording data is applied thereto, the recording data is recorded as a pit row in a spiral or concentric shape at a location irradiated with the laser beam. When the pits are formed by irradiating the laser beam onto the recording surface of the magneto-optical disk and heating the pits, the irradiation point of the laser beam is slightly increased to the Curie temperature, but the time ΔT is small. is necessary. At the same time, at the time of this recording, the magneto-optical disk is rotated. Therefore, during the recording, the time ΔT
The irradiation position of the laser beam will move during
Therefore, the positions of the formed pits are also shifted.

For this reason, when reproducing the magneto-optical disk, the phase of the sample servo clock obtained by reproducing the sample servo pattern and the phase of the reproduction data in the recording area are shifted. Therefore, when the reproduction signal is sampled using only the sample servo clock during reproduction of the magneto-optical disk,
As described above, since the phase of the servo clock is different from the phase of the reproduction signal, accurate reproduction cannot be performed.

When reproducing a magneto-optical disk, the phase of the sample servo clock corresponding to the sample servo pattern and the data to be reproduced also depend on, for example, a temperature difference or individual differences in a drive (magneto-optical disk device). A difference (phase difference) occurs between the phase and the phase. As a method for solving such a problem, a method in which pits are formed by performing correction in advance during recording based on the surrounding environment (temperature, power of a laser light source, and the like) can be considered.

However, in this case, it is difficult to obtain detailed recording conditions for performing the correction, and the difference in characteristics (individual difference) of the magneto-optical disk and the difference between the data recording device and the data reproducing device. For this reason, the correction at the time of recording alone is not sufficient. Therefore, conventionally, at the time of reproduction, a delay amount corresponding to the difference (phase difference) between the phase of the reproduction clock (sample servo clock) of the sample servo pattern obtained in advance and the phase of the reproduction data of the recording pit is used.
The phase correction (read clock phase correction) is performed such that the reproduced sample servo clock is delayed using a delay line.

As a result, the above-described servo clock having undergone phase correction, that is, a master clock (read clock) is obtained. When reproducing the magneto-optical disk, the reproduction clock of the recording area is sampled using the master clock. Next, as a clock generating circuit of a conventional optical disk device that does not use a delay line, Japanese Patent Laid-Open No.
243589 “Clock generation circuit and optical disk device”
Are known.

FIG. 3 shows a configuration of a clock generating circuit of a conventional optical disk device. In FIG. 3, the input clock is supplied to an input terminal 51. This input clock is sent to a first PLL circuit 52 that obtains an output phase-synchronized with the input wave using a negative feedback loop of an integral control type relating to frequency by combining a phase comparator and a voltage controlled oscillator, for example. Output (clock) from the PLL circuit 52
Becomes the servo clock and the second PLL circuit 5
Sent to 3.

The second PLL circuit 53 includes a normal PLL circuit.
Like the L circuit, the circuit includes a loop filter 56, a voltage controlled oscillator (VOC) 57, and a phase comparator 54. The second PLL circuit 53 of this conventional example additionally includes: An adder 55 is provided. This adder 5
5 is for the output (voltage value) from the phase comparator 54,
It is provided to add a predetermined phase difference offset (voltage value) supplied via the input terminal 59.

That is, in the PLL circuit 53, an input signal (clock from the first PLL circuit 52)
And the oscillation frequency and phase of the voltage controlled oscillator 57 are compared by the phase comparator 54. The phase comparator 54 outputs a DC voltage proportional to the error between the frequency and phase of the clock from the first PLL circuit 52 and the oscillation frequency and phase of the voltage controlled oscillator 57.

After adding a predetermined phase difference offset (voltage value) to the error voltage by an adder 55, the error voltage is sent to a voltage controlled oscillator 57 via a loop filter 56 which is a low-pass filter. In the second PLL circuit 53, the first PLL circuit
The frequency of the voltage controlled oscillator 57 is changed in a direction to reduce an error between the frequency and the phase of the clock from the circuit 52 and the oscillation frequency and the phase of the voltage controlled oscillator 57.

With such a configuration, the first PLL circuit 5 is connected to the output terminal 58 of the conventional clock generation circuit.
Thus, an output clock can be obtained in which the phase of the input clock to 2 is delayed by an amount corresponding to the phase difference offset.

[0016]

However, as described above, in the conventional method in which the sample servo clock is delayed by the delay line to obtain the master clock (read clock), the reproduction is performed based on, for example, the temperature characteristics of the delay line. An error may occur in the clock phase correction, and data may not be able to be reproduced.
For example, there is a problem that attention must be paid to the accuracy of the temperature characteristics of the delay line.

Further, in the conventional example of FIG. 3, at least two VCOs are necessary in the two PLL circuits 52 and 53, and the latter PLL circuit 53 is difficult to digitize. However, there is a problem that the analog component is required and the circuit scale is increased. Here, the preceding PLL circuit 52 is used for the servo clock. In general, the servo clock requires a wide variable range and quick response, while the data recording / reproducing clock is used for data recording / reproducing. Therefore, stable phase lock and low jitter characteristics are required for the clock pit, and these two PLLs are required to have conflicting performances.
If the clock for data recording and reproduction is later configured in series,
The jitter with respect to the clock pit of the previous PLL is
There was also a problem of affecting L.

Further, in the above two conventional examples, the sample servo clock and the master clock (read clock) have the same frequency and differ only in phase. However, it is general that the sample servo clock and the read clock have different frequencies. If the frequency is forced to be equal, there is also a problem that the arrangement of the sample servo clock on the optical disk and the conditions for recording in the recording area are greatly restricted.

The present invention solves the above-mentioned conventional problems, and comprises a plurality of PLL circuits or a plurality of V
It can be configured without using CO or delay line, and can eliminate the temperature characteristics and variations caused by them, can reduce the power consumption of the whole device, and can implement circuit mounting. And a clock generation circuit for the optical disk device that can be simplified.

[0020]

In order to solve the above-mentioned problems, a clock generating circuit of an optical disk apparatus according to the present invention is formed in advance on an optical disk based on phase difference information from a first phase difference detecting means. Based on a phase shift caused by a temperature at the time of writing to an optical disk, an individual difference of a drive, etc., between a signal pattern of a clock generated in synchronization with a clock signal pattern and a signal pattern of a data read clock, The phase difference offset is detected by the phase difference information detected by the phase difference detecting means of
In addition to the phase difference information from the phase difference detection means, the output of the second phase difference detection means is converged to zero phase difference to remove the offset, and is synchronized with the reproduced clock signal pattern at a predetermined frequency ratio, In addition, by obtaining an output clock whose phase matches the data of the reproduced recording area, the clock from one analog VCO can be used without using a delay line and without passing through a PLL for servo clock. It is characterized in that the phase is accurately synchronized with the reproduced data while the frequency is locked with respect to the clock pit.

As described above, the configuration can be made without using a plurality of PLL circuits, a plurality of VCOs, or a delay line as in the related art, and it is possible to eliminate the temperature characteristics and variations caused by them. At the same time, the power consumption of the entire device can be reduced, and the circuit mounting can be simplified.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A clock generating circuit for an optical disk device according to the first aspect of the present invention records at least a clock signal pattern, a sample servo pattern, and a digital signal corresponding to various information including data. In an optical disk device that records and reproduces the various types of information in and from the optical disk provided with each recording area for recording, a clock generation circuit of the optical disk device that generates a clock based on a reproduction signal based on the clock signal pattern is used. A clock generating means for generating the clock; and converting the reproduced clock signal pattern and the analog signal of the sample servo pattern into a digital signal at a sampling timing by a sampling clock based on the clock from the clock generating means. First A / D to be converted Conversion means; first phase difference detection means for detecting a phase difference between the reproduced clock signal pattern and an output clock from the clock generation means from an output signal of the first A / D conversion means; Control means for giving a predetermined low-pass reactor wave characteristic to the output from the first phase difference detection means, and synchronizing the reproduced clock signal pattern with the output clock from the clock generation means at a predetermined frequency ratio; A second A / D converter for converting an analog signal of data in the reproduced recording area into a digital signal at a sampling timing based on a sampling clock based on a clock from the clock generator;
Second phase difference detection means for detecting a phase difference between phase information of the data in the reproduced recording area and an output clock from the clock generation means from an output signal of the second A / D conversion means; Multiplying means for multiplying the output from the second phase difference detecting means by a predetermined coefficient and integrating the result; adding the output of the integrating means to the output of the first phase difference detecting means and inputting the result to the control means And an adder for synchronizing the frequency and phase of the output clock from the clock generator with the reproduced data in the recording area.

According to this configuration, the signal pattern of the clock generated in synchronization with the clock signal pattern previously formed on the optical disk based on the phase difference information from the first phase difference detecting means, and the signal of the data read clock A phase difference offset between the pattern and the pattern is detected based on phase difference information detected by the second phase difference detecting means based on a phase shift caused by a temperature at the time of writing to an optical disc, an individual difference of a drive, and the like. Is added to the phase difference information from the first phase difference detection means, the output of the second phase difference detection means is converged to zero phase difference to remove the offset, and the reproduced clock signal pattern is added to the reproduced clock signal pattern at a predetermined frequency ratio. By obtaining an output clock that is synchronized and in phase with the data in the reproduced recording area, the delay clock can be used without using a delay line. Not through the Bokurokku for PLL, a clock from a single VCO analog configuration,
While the frequency is locked with respect to the clock pit, the phase is accurately synchronized with the reproduced data. In the offset detection, the phase is automatically converged to an optimum value by an auxiliary control loop having an integrating means.

According to a second aspect of the present invention, there is provided a clock generating circuit for an optical disk device, wherein a phase of each pit signal included in a sample servo pattern with respect to a sampling clock at the time of conversion by the first A / D conversion means according to the first aspect. Each pit corresponding to the phase value detected by the pit phase detecting means is obtained by using a pit phase detecting means for detecting a value and a data group around each pit signal from the first A / D converting means. A calculating means for calculating a signal level, wherein an output clock from a clock generating means whose frequency and phase are synchronized with reproduction data in a recording area of an optical disk is also used as a clock for detecting the sample servo pattern. I do.

According to a third aspect of the present invention, there is provided a clock generating circuit for an optical disk apparatus, wherein the pit phase detecting means according to the second aspect is obtained as a phase value with respect to a sampling clock based on an output clock from the clock generating means, and is determined in advance. The phase value of each pit signal in the sample servo pattern, which is determined by the relationship between the cycle of the clock signal pattern, the cycle of the sample servo pattern, and the cycle of the output clock from the clock generating means,
The clock signal pattern converted into a digital signal with an offset by the A / D conversion means of
Based on the difference value between the two data, the correction is performed by the offset phase amount obtained by the proportional operation.

According to a fourth aspect of the present invention, there is provided a clock generating circuit for an optical disk device, wherein the pit phase detecting means according to the second aspect is provided based on a predetermined period of a clock signal pattern, a period of a sample servo pattern, and a clock generating unit. The approximate position of the pit in the sample servo pattern is predicted from the relationship with the cycle of the output clock of the sample servo pattern, and the approximate position of the pit of the sample servo pattern data in the sample servo pattern data converted into a digital signal by the first A / D conversion means is estimated. The phase value at the peak position of the pit signal obtained by the proportional calculation based on the difference value between the maximum value or the minimum value and the two data before and after the maximum value is defined as the phase value of the pit signal in the sample servo pattern. The configuration is as follows.

According to a fifth aspect of the present invention, in the clock generating circuit of the optical disk device, the level of each pit signal is set to the first A level according to the first aspect, assuming that the shape of the pit signal is a predetermined function.
A calculating means for performing an approximate calculation using a data group around each pit signal from the / D converting means, wherein an output clock from the clock reproducing means whose frequency and phase are synchronized with reproduction data in a recording area of the optical disk; Is also used as a clock for detecting the sample servo pattern.

According to these configurations, the phase difference between the read clock pattern and the reproduced sample servo pattern is detected, and the level of the sample servo pit is calculated according to the phase difference, thereby reproducing the recording area of the optical disk. A clock from a clock generation unit whose frequency and phase are synchronized with data can be used also as a clock for detecting a sample servo pattern.

Hereinafter, a clock generation circuit of an optical disk device according to an embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a clock generation circuit of the optical disk device according to the present embodiment. In FIG. 1, a pit detector 2 of a recording / reproducing system 1
For example, by receiving reflected light from a magneto-optical disk irradiated with a laser beam, a clock pit for synchronizing each segment on the magneto-optical disk and a tracking error signal as a sample servo pattern are obtained. A pair of wobble pits is detected. The output from the pit detector 2 is sent to an A / D converter 5 which is a first A / D converter, after the gain is automatically adjusted by an AGC (auto gain control) circuit 4, and converted into a digital signal. Is converted.

The digital signal from the A / D converter 5 is sent to a servo system detector 21 and also sent to a first phase difference detector 6 which is a first phase difference detecting means, and the digital signal of the clock pit is output. The phase is detected. An output from the first phase difference detector 6 is supplied to an adder 16 serving as an adding unit, and a loop filter 7 serving as a low-pass filter forming a control unit.
The signal is sent to a VCO 9 as a clock generating means via a D / A converter 8 and controls the frequency and phase of the VCO 9. Here, the output of the VCO 9 is used as a sampling clock of the A / D converter 5 and sent to the timing generator 10 and the output terminal 17.

VCO 9-timing generator 10 (A / D
Converter 5) -First phase difference detector 6-Loop filter 7-D / A converter 8-VCO 9 constitutes a PLL control loop, and this PLL control loop has an integral control type negative feedback characteristic with respect to frequency. , An output whose phase is synchronized with the input signal, that is, the clock pit is obtained. Next, a recording data reproducing system will be described. Note that the optical disk device of the present embodiment employs an example of performing NRZI demodulation when reproducing recorded data on a magneto-optical disk.

The data detector 3 in the recording area of the recording / reproducing system 1 receives light reflected from the disk surface of the magneto-optical disk irradiated with the laser beam and photoelectrically converts the light to record on the magneto-optical disk. The recorded data is detected. The reproduction signal from the data detector 3 in the recording area is AG
After the gain is automatically adjusted by the C circuit 11, the second A
Is sent to the A / D converter 12 which is the
It is converted into a digital signal based on the read clock (master clock) generated from the output of CO9.

The digital signal from the A / D converter 12 is equalized in waveform by an equalizer (EQ) 13, and is subjected to NRZI encoder / decoder 20 by an NRZI encoder / decoder circuit 20.
The signal is demodulated and sent to the subsequent stage. At the time of signal recording, the NRZI encoder / decoder circuit 20 has the NR
The ZI modulation data is sent to the recording / reproducing system 1. Based on the data, a laser driver for driving the laser diode of the recording / reproducing system 1 and a magnetic head driver for modulating the magnetic field operate. At the time of recording, the laser driver causes the laser diode to emit a pulse with high power, and recording data is input to the driver for the magnetic head to perform high-speed magnetic field modulation. During reproduction, the laser driver causes the laser diode to emit light continuously at low power. Further, at the time of recording, recording position control including the width of the laser pulse and the phase of the magnetic field data is performed.

The output of the A / D converter 12 is sent to a second phase difference detector 14 as a second phase difference detecting means via an equalizer 13 and reproduced data of a recording area (here, reproduced data ) And the read clock, that is, the output clock of the VCO 9 is detected. The phase difference signal output from the second phase difference detector 14 is cumulatively added by an integrator 15 which is an integrating means, and further added to the output of the first phase difference detector 6 by an adder 16 to form a loop filter. 7 is input. Here, the second phase difference detector 14-integrator 15-loop filter 7-D / A converter 8-VCO 9-timing generator 10 (A / D converter 12) -second phase difference detector 14 Construct a phase difference offset detection (correction) loop.

That is, in the optical disk of the present embodiment, a phase error at the time of reproduction is detected using the fixed pattern in the reference clock pattern area, and this phase error is integrated by the integrator 15, and no phase error is detected. At this time, by holding the integration result, the output of the second phase difference detector 14 converges to 0, that is, the reproduced data (reference clock) and the read clock phase coincide with each other. Holds the value corresponding to the phase offset amount, and the output of the first phase difference detector 6 stores the phase offset amount of the output of the integrator 15 by the low-pass reactor wave characteristic (integration characteristic) of the loop filter 7. A phase difference signal to cancel out is output, that is, a phase difference corresponding to the offset amount is generated between the clock pit and the output clock of the VCO 9, and the PLL control loop is stabilized, Raw data (the reference clock) and the read clock phase matches.

Here, the offset correction speed is calculated by the integrator 1
5 can be changed by a coefficient multiplier provided at the input of 5,
The response is slow enough not to affect the response of the PLL loop.
When the LL becomes stable, it is desirable to make a response as quickly as possible. In the present embodiment, the cycle (sector cycle) in which the reference clock is arranged is longer than the cycle (segment cycle) of the clock pit. However, the reference clock is output in a cycle that is close to the output clock of the VCO 9 for about one segment period. Therefore, the mutual interference is small and the response can be determined almost independently.

The clock from the VCO 9 is also sent to the timing generator 10. The timing generator 10 generates a timing clock for each unit based on the clock from the VCO 9. Timing generator 1
0 includes a frequency divider, and sets a frequency ratio between the frequency of the sample servo clock and the master clock. Since this frequency ratio differs depending on the zone, it is controlled by the zone controller 22.

The zone controller 22 identifies the zone of the disk on which recording and reproduction is being performed based on information from the servo system detector 21 and the like. Here, basically, the output data of the A / D converters 5 and 12 already have clock pits, phase difference information between the reproduction data of the recording area and the output clock of the VCO 9. The timing generator 10 generates timing information of each unit based on the clock from the VCO 9 and the zone signal from the zone controller 22, and the like.
The phase difference detectors 6 and 14 provide timing information for extracting phase difference information in the output data of the A / D converters 5 and 12, and calculate phase difference signals from the extracted phase difference information.

Since the magneto-optical disk of this embodiment employs the zone CAV as described above, the phase difference between the phase of the sample servo clock and the phase of the reference clock differs for each zone. Therefore, in this apparatus, the zone controller 2 that controls each unit for each zone
2, the timing generator 10 is controlled. As a result, P
The LL circuit is controlled. In this PLL circuit, the phase is corrected for each zone, and an optimum read clock (master clock) is output.

Each time the zone changes, the integrator 15
The response can be expedited by holding each output value of the above and setting the held value of each zone as the initial value of the offset amount. Eventually, the frequency of the output of the VCO 9 is frequency-synchronized with the clock pit, and the phase finally matches the reference clock in the reproduced data. Thus, the output clock of the VCO 9 of the clock generation circuit can be used as the read clock. This master clock is sent to the subsequent configuration via the A / D converters 5 and 12, the servo system detector 21, and the clock output terminal 17.

The sampling clocks of the A / D converters 5 and 12 are not always equal, and each or one of them may be produced by dividing the output clock of the VCO 9. The D / A converter 8 is for converting the output of the loop filter 7 which is a digital signal into an analog signal in order to control the VCO 9 which is an analog circuit.

The servo system detector 21 uses the digital signal from the A / D converter 5 to generate various servo signals such as focus servo and position servo. This servo signal is sent to the drive system 23. The drive system 23 includes various actuators and the like. The servo system detector 21 compares the relative levels of the pair of wobble pits detected by the pit detector 2 to obtain a tracking error signal, sends this tracking error signal to the drive system 23, and outputs the pair of wobble pits. Are controlled so that the reproduction levels of the.

The arrangement period of the wobble pits is 1 / integer of the clock pit period, but is not necessarily in an integer ratio with the period of the read data read clock, and the relationship differs for each zone. The output clock frequency of the clock generation circuit is synchronized with an integer multiple (N times) of the clock signal pattern frequency. The sample servo patterns are arranged at positions where the clock signal pattern is divided at equal intervals (M division).

Here, when N> M, where N ÷ M is an integer, the phase of each pit signal included in the clock signal pattern and the sample servo pattern for the output clock of the clock generation circuit becomes equal. When ÷ M is not an integer, the phases are different. Further, the above-described embodiment provides a method for accurately detecting the level of a sample servo pattern (such as a wobble pit) using a clock signal whose period does not match the clock signal pattern, and detecting the sample servo pattern using a read clock of reproduced data. It is intended to provide a means for making it possible to also use a common clock.

That is, the A / D converter 5 shown in FIG.
The phase of the pit signal with respect to the sampling clock of
The pit phase detection means provided in the servo system detector 21 detects from the output signal of the A / D converter 5 and various information of the servo system, and detects this phase from the data group around each pit signal of the output of the A / D converter 5. Of each pit signal is calculated. For this calculation, a transversal filter that approximates an ideal low-pass filter can be used. The number of taps of the transversal filter is determined from the required approximation accuracy (resolution in the phase direction, bit accuracy in the amplitude direction), The required number of peripheral data is determined.

Next, the specific configuration of the pit phase detecting means in the present invention is as follows: (1) From the relationship between the clock signal pattern and the determined arrangement of each pit signal included in the sample servo pattern,
The phase of each pit when the output clock of the clock generation means is accurately synchronized with the clock signal pattern is calculated in advance, and the clock pit data having the offset of the output of the A / D converter 5 is equal to the clock pit data having the same time difference before and after. 2
The offset phase amount is calculated by performing a proportional calculation from the difference value between the two data, and the previously calculated phase amount is corrected. (2) The peak value of each pit signal is set as the pit signal level. A rough pit position is predicted from the relationship between a predetermined clock signal pattern cycle, a sample servo pattern cycle, and a cycle of an output clock of the clock generation means, and a maximum value (or a minimum value) of data near the rough pit position is estimated. Approximately calculates the phase of the pit peak position by performing a proportional calculation from the difference between the two data before and after that.
The pit phase is assumed.

Since the reproduced pit signal is band-limited, a large error does not occur near the extreme value even when approximating a sinusoidal waveform. Assuming a sine wave waveform, the differential value near the peak becomes substantially a straight line, and the differential value at the peak becomes zero.
Therefore, the phase of the peak position with respect to the sampling clock can be calculated by the proportional calculation from the differential values of the two points before and after the peak position. The differential value is obtained from a difference value between adjacent data.

Assume that three data continuous at equal time differences around the clock pit are a, b, and c in time order. Since the pit waveform is a left-right symmetrical positive pulse and band-limited, the vicinity of the peak can be regarded as a part of a sine waveform. If this peak timing is used as a reference for the pit phase, and it is assumed that the data b in the middle of the pit peripheral data is selected so as to always take the maximum value, a = c for the reference, ie, zero phase, and a for the phase −π = B, b = c at phase + π. The phase φ at an arbitrary point is represented by φ = π × (ca) / (2ba-c), where the differential value is regarded as a straight line.

The number of bits of φ is equal to the resolution in the phase direction. For example, if the required resolution is to resolve the sampling period into eight, φ is 3 bits, and the division operation of φ can be realized by three subtractions and sign discrimination. The same applies to the phase detection of the maximum value of the reproduced sample servo pattern.

As described above, the conditions for the approximation to be satisfied are that the data on both sides of the pit peripheral peak is the pit pulse level of 1
/ 2 points or more. Next, the peak value of the pit signal can be directly calculated from the pit peak peripheral data group. For example, assuming a sine wave around the pit peak, it is set as p + qCOSθ. For example, for continuous data a, b, and c, p + qCOS (Δθ−θ1) = ap + qCOS (Δθ) = bp + qCOS (Δθ + θ1) = c Is found.

Here, since θ1 can be estimated from the waveform of the pit signal and the cycle of the clock signal, if θ1 is known (different for each zone), the variable becomes 3, and can be obtained from at least three points. The operation looks complicated at first glance,
It can be simplified by limiting the value of the parameter and replacing it with an approximate value.

For example, the approximate calculation of the ratio of Δθ to θ1 has been described above. Also, the value of p is obtained by converting the pit signal to A / D
It changes depending on the DC value and pit level of the input signal at the time of conversion, but when these are within a range necessary for practical use, they can be replaced with predetermined values. Although common to all of the above, the sampling clock of the A / D comparator 5 can be increased to lower the calculation accuracy. For example, A /
If the sampling clock of the D converter 5 is doubled that of the A / D converter 12 and the sampling period of the pit signal is halved, the required operation resolution is halved, the required operation accuracy is reduced, and the transversal filter is used. Is reduced, the approximation function can be approximated by a simpler function, and the operation itself is simplified.

In the above-described embodiment, the reference clock recorded under the same conditions as general data is used to detect the phase of the data in the reproduced recording area. If the system is devised, it is possible to directly obtain the phase information from the edge component of a general data signal. In addition, in the above-described embodiment, the case where a magneto-optical disc is used as the optical disc is described. However, the present invention is not limited to this. For example, a phase-change optical disc may be used. However, the same effect as described above can be obtained.

[0054]

As described above, according to the present invention, a clock signal pattern generated in synchronization with a clock signal pattern previously formed on an optical disk based on the phase difference information from the first phase difference detecting means. And a signal pattern of the data read clock, based on phase difference information detected by the second phase difference detecting means based on a phase shift caused by a temperature at the time of writing to an optical disk, an individual difference of a drive, and the like. The phase difference offset is detected, and the phase difference information is added to the phase difference information from the first phase difference detection means. The output of the second phase difference detection means is converged to zero phase difference to remove the offset. By obtaining an output clock synchronized with the pattern at a predetermined frequency ratio and in phase with the data in the reproduced recording area, the delay line can be used. Without, and PLL servo clock
The clock from one analog-structured VCO can be frequency-locked with respect to the clock pits, and the phase can be accurately synchronized with the reproduced data without going through.

As a result, it is possible to configure the apparatus without using a plurality of PLL circuits, a plurality of VCOs, or a delay line as in the related art, and it is possible to eliminate the need to consider the temperature characteristics and variations generated by the circuits. , The power consumption of the entire device can be kept low,
In addition, circuit mounting can be simplified. In the offset detection, the auxiliary control loop in which the integrating means is introduced can automatically converge to the optimum value, and can accurately synchronize the phase with the reproduction data.

Further, the phase difference between the read clock pattern and the reproduced sample servo pattern is detected, and the level of the sample servo pit is calculated according to the phase difference. The clock from the clock generating means whose phases are synchronized can also be used as the clock for detecting the sample servo pattern.

Therefore, even if the sample servo pattern and the read clock are asynchronous in frequency and phase, a special servo clock for detecting servo data is not required and the mounting can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a clock generation circuit of an optical disc device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of a recording format of a magneto-optical disk;

FIG. 3 is a block diagram showing a configuration of a clock generation circuit of a conventional optical disk device.

[Explanation of symbols]

 Reference Signs List 1 recording / reproducing system 2 pit detector 3 data detector 4, 11 AGC circuit 5, 12 A / D converter 6, 14 phase difference detector 7 loop filter 8 D / A converter 9 VCO 10 timing generator 13 equalizer 15 integration Device 16 adder 17 clock output terminal 20 NRZI encoder / decoder circuit 21 servo system detector 22 zone controller 23 drive system

Claims (5)

[Claims] 1. At least a clock signal pattern;
In an optical disc apparatus having a recording area for recording a digital signal corresponding to a sample servo pattern and various kinds of information composed of data, an optical disc apparatus for recording and reproducing the various kinds of information in the recording area is provided. What is claimed is: 1. A clock generating circuit for an optical disk device for generating a clock based on a reproduced signal based on a signal pattern, comprising: a clock generating means for generating the clock; and an analog signal of the reproduced clock signal pattern and the sample servo pattern. A first A / A converter for converting a digital signal into a digital signal at a sampling timing based on a sampling clock based on the clock from the generating unit;
D conversion means for detecting a phase difference between the reproduced clock signal pattern and an output clock from the clock generation means from an output signal of the first A / D conversion means.
A predetermined low-pass reactor wave characteristic to the output from the first phase difference detecting means, and the reproduced clock signal pattern and the output clock from the clock generating means, Control means for synchronizing at a frequency ratio, and a second A / D for converting an analog signal of reproduced data in a recording area into a digital signal at a sampling timing by a sampling clock based on a clock from the clock generating means. Conversion means, and the second A / D
Second phase difference detection means for detecting a phase difference between phase information of the reproduced recording area data and an output clock from the clock generation means from an output signal of the conversion means, and the second phase difference detection An integrating means for multiplying an output from the means by a predetermined coefficient to integrate the output, and an adding means for adding an output of the integrating means to an output of the first phase difference detecting means and inputting the output to the control means, A clock generating circuit for an optical disk device, wherein an output clock from said clock generating means is synchronized in frequency and phase with data in a reproduced recording area. 2. A pit phase detecting means for detecting a phase value of each pit signal included in a sample servo pattern with respect to a sampling clock at the time of conversion by a first A / D converting means, and said first A / D converting means. Calculating means for calculating the level of each pit signal corresponding to the phase value detected by the pit phase detecting means, using a data group around each pit signal from the means for reproducing the recording area of the optical disk. 2. The clock generation circuit according to claim 1, wherein an output clock from a clock generation unit whose frequency and phase are synchronized with data is also used as a clock for detecting the sample servo pattern. 3. The pit phase detection means is obtained as a phase value with respect to a sampling clock based on an output clock from a clock generation means, and a predetermined cycle of a clock signal pattern, a predetermined cycle of a sample servo pattern, and the clock generation means are provided. The first A / D converter converts the clock signal pattern into a digital signal with an offset with respect to the phase value of each pit signal in the sample servo pattern determined from the relationship with the cycle of the output clock from 3. The clock generation circuit of an optical disk device according to claim 2, wherein correction is performed by an offset phase amount obtained by performing a proportional operation based on a difference value between two data before and after the data. 4. The pit phase detecting means is configured to calculate the outline of pits in the sample servo pattern based on a relationship between a predetermined cycle of a clock signal pattern, a cycle of a sample servo pattern, and a cycle of an output clock from the clock generating means. The position is predicted, and the maximum value or the minimum value near the approximate position of the pit of the sample servo pattern data converted into the digital signal by the first A / D conversion means and the difference value between the two data before and after the maximum value are obtained. 3. The clock according to claim 2, wherein a phase value at a peak position of the pit signal obtained by performing a proportional operation is set as a phase value of the pit signal in the sample servo pattern. Generator circuit. 5. Assuming that the shape of the pit signal is a predetermined function, the level of each pit signal is approximately calculated using a data group around each pit signal from the first A / D converter. 2. The apparatus according to claim 1, further comprising an operation unit, wherein an output clock from the clock reproduction unit having the same frequency and phase as the reproduction data in the recording area of the optical disk is also used as the sample servo pattern detection clock. A clock generation circuit for the optical disk device according to the above.