JP2006059390A - Disk drive device, and wobble reproduction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To execute appropriate demodulation corresponding to the periodical phase deviation of a wobble signal. <P>SOLUTION: A clock signal WCK (or wobble signal WD) is phase-shifted (14) to cope with the great deviation of the wobble signal phase between modulated sections to a clock signal since the phase of a periodical wobble signal fluctuates, the direction of the phase deviation is opposite between a non-modulated section (monotone wobble section) and a modulated section (MSK modulated section), and a clock signal for demodulating the modulation signal is in synchronization with a signal in the non-modulated section. The relative phases are corrected, and the phase of the wobble signal of the modulated section and that of the clock signal in synchronization with the non-modulated section are matched. In this case, since the wobble signal amplitude also fluctuates with the same period, the relative phase is corrected corresponding to the periodical phase deviation by detecting the amplitude level of the wobble signal and changing the amount of phase-shift of the clock signal or wobble signal accordingly (15). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a disk drive apparatus and a wobble reproduction method for recording or reproducing information on a disk recording medium on which information is recorded by wobbling a recording track such as a wobbling groove.

JP 2003-45028 A

As a technique for recording / reproducing digital data, optical disks (including magneto-optical disks) such as CD (Compact Disk), MD (Mini-Disk), and DVD (Digital Versatile Disk) are used as recording media. There is data recording technology. An optical disk is a generic term for recording media that irradiate laser light onto a disk in which a thin metal plate is protected with plastic, and read signals by changes in reflected light.
The optical disc includes, for example, a read-only type as known as CD, CD-ROM, DVD-ROM, MD, CD-R, CD-RW, DVD-R, DVD-RW, DVD + RW, DVD -There is a type in which user data can be recorded as known in RAM and the like. In the recordable type, data can be recorded by using a magneto-optical recording method, a phase change recording method, a dye film change recording method, or the like. The dye film change recording method is also called a write-once recording method, and can be recorded only once and cannot be rewritten. On the other hand, the magneto-optical recording method and the phase change recording method can rewrite data and are used for various purposes such as recording of various content data such as music, video, games, application programs and the like.
In recent years, a high-density optical disk called a Blu-ray Disc has been developed, and the capacity has been significantly increased.

In order to record data on a recordable disc such as a magneto-optical recording method, a dye film change recording method, a phase change recording method, etc., a guide means for tracking the data track is required. Grooves (grooves) are formed in advance as pregrooves, and the grooves or lands (cross-section plateau-like portions sandwiched between the grooves and the grooves) are used as data tracks.
Further, it is necessary to record address information so that data can be recorded at a predetermined position on the data track, but this address information may be recorded by wobbling (meandering) the groove.

That is, a track for recording data is formed in advance as a pregroup, for example, and the side wall of this pregroup is wobbled corresponding to the address information.
In this way, the address can be read from the wobbling information obtained as reflected light information at the time of recording or reproduction. For example, even if pit data indicating the address is not formed on the track in advance, the desired position can be read. Data can be recorded and reproduced.
By adding address information as a wobbling groove in this way, for example, it becomes unnecessary to provide an address area discretely on a track and record an address as, for example, pit data. Recording capacity can be increased.
The absolute time (address) information expressed by such a wobbled groove is called ATIP (Absolute Time In Pregroove) or ADIP (Address In Pregroove).

In the case of the Blu-ray disc, the groove is wobbled based on a modulation waveform obtained by combining MSK (Minimum Shift Keying) modulation and STW (Saw Tooth Wobble) modulation.
The MSK modulation and STW modulation and ADIP information formed by combining these will be described in detail later. The MSK modulation has a modulation index of 0.5 among FSK (Frequency Shift Keying) modulation in which phases are continuous. It is.
STW modulation is a modulation method that generates a modulation waveform such as a sawtooth waveform by adding or subtracting twice the harmonics to the wobble fundamental wave.
In a disk drive device corresponding to a Blu-ray disc, an MSK demodulator and an STW demodulator are mounted in order to reproduce such ADIP information.

By the way, as the wobbling groove, there are formed a monotone wobble section having a substantially sinusoidal shape as a non-modulation section and a modulation section as, for example, the MSK modulation. Information is recorded by including a modulation section whose phase or period is shifted less frequently than the monotone section. A signal waveform (wobble signal) having a shape substantially matching this wobble pattern is obtained from the optical pickup of the recording / reproducing apparatus.
Since the monotone region is long in time, a clock signal based on the monotone region can be reproduced by a PLL circuit having a sufficiently low band without being affected by the modulation interval. Based on this clock signal, the modulation interval can be reproduced. Thus, the information recorded in the wobbling groove can be detected.

However, the wobble signal deviates from the original phase due to the influence of the adjacent track, particularly the phase condition with the wobble of the adjacent track.
For example, when the wobble wavelength in the monotone region is a constant value wl and the groove pitch is tp, the condition of the phase difference from the adjacent track repeatedly changes every wl / (2 × π × tp) rotation period. In the case of the Blu-ray disc, this corresponds to 2.7 laps as the disc rotation. That is, the condition of the phase difference of the wobbling groove between a certain track and its adjacent track continuously fluctuates during 2.7 laps, and returns to the original phase difference after 2.7 laps.
Since the wobble signal is out of phase depending on the phase condition with the adjacent track, the phase of the wobble signal read from the disk becomes faster or slower than the original phase during 2.7 rounds. .
Furthermore, when the phase is delayed in the modulation section, this phase fluctuation is in a state where the phase advances in the preceding and following monotone wobble sections, and conversely, in the case where the phase advances in the modulation section, the preceding and following monotone wobble sections In this state, the phase is delayed.
Further, there arises a problem that the demodulating process of the modulation signal cannot be performed correctly in the portion where the signal phase is largely shifted from the original phase due to such phase fluctuation.
In general, if wl / (2 × π × tp) is an integer, the phase does not deviate from track to track. Therefore, any track has the same phase relationship and is convenient. This is not the case with various disk systems.

Deterioration of demodulation performance due to the above-described periodic phase shift will be described with reference to FIGS.
9B, 9C, and 9D show wobble signal waveforms having no phase shift and wobble signal waveforms in which the phase shift observed in the period of the 2.7 rounds is generated as the wobble signals I, II, and III. Show. The wobble signals I (thick line), II (broken line), and III (thin line) in FIG. 9A are synthesized and shown for comparison in the wobble signals in FIGS. 9B, 9C, and 9D. It is.
Although details will be described later, on the wobble format of the Blu-ray disc, monotone wobbles with the wobble fundamental frequency are continuous, and MSK marks (MSK modulation signal sections) are present at predetermined positions in three wobble periods (three wave sections of monotone wobbles). Arranged.
The MSK mark has a 1.5th harmonic wave, a −1th harmonic wave, and a −1.5th harmonic wave with respect to a monotone wobble waveform.
In FIG. 9, 11 periods are shown such that the monotone wobble has 4 periods, the MSK mark portion (1.5th harmonic wave, -1th harmonic wave, -1.5th harmonic wave), and the monotone wobble has 4 periods.

The wobble signal I shown in FIG. 9A and the solid line in FIG. 9B is an original wobble signal waveform with no phase shift.
If the actual wobbling shape of the groove on the disk is formed in accordance with the timing of the vertical line in FIG. 9, that is, the period of the wobble basic frequency, the wobble signal waveform read from the groove is as shown in FIG. It becomes like this.
However, as described above, when the phase relationship between the wobble of a certain track and the wobble of an adjacent track fluctuates within a period of 2.7 laps, a wobble signal waveform as shown in FIG. At the time, the wobble signal waveform is as shown in FIG.
For example, in the wobble signal II in FIG. 9C, the monotone wobble has a phase delay, and the phase advance has occurred in the MSK mark period.
Further, in the wobble signal III of FIG. 9D, the monotone wobble has a phase advance, and the MSK mark period has a phase lag.

Here, the clock for performing the MSK demodulation is formed as a clock synchronized with the wobble signal. However, since the frequency of appearance of the MSK portion is low in the wobble signal, the clock is generated as a clock synchronized with the monotone wobble. become.
Then, for example, in the period of FIG. 9C, the MSK mark in which the phase advance has occurred must be demodulated with the clock synchronized with the monotone wobble in which the phase delay has occurred.
Further, for example, in the period of FIG. 9D, the MSK mark having a phase delay must be demodulated with a clock synchronized with the monotone wobble in which the phase advance has occurred.
That is, with respect to the MSK mark, the phase of the demodulation clock is greatly shifted.
FIG. 10A shows the wobble signal waveforms I, II, and III of FIG. 9 with their phases shifted so as to match the timing of the monotone wobble section. This is a waveform with the vertical line in the figure as the clock timing. The clock WCK synchronized with the monotone wobble is as shown in FIG.
When viewed at the clock timing as shown in FIG. 10 (a), the MSK mark portion appears to be severely out of phase within a period of 2.7 rounds. In other words, an ideal state may always be used as in the wobble signal I. However, the phase of the MSK is shifted to the left as in the wobble signal II within 2.7 laps. There is a shift to the right (actually changes continuously in 2.7 laps).

In other words, there is a periodic phase variation of the wobble signal, and the phase shift direction is reversed between the monotone wobble period and the MSK modulation period, and the clock for demodulating the MSK modulation is synchronized with the monotone wobble. As a result, the phase of the MSK modulation section is significantly shifted from the clock.
In the MSK demodulation processing, multiplication processing and integration processing are performed in a period based on the clock that is the wobble basic cycle. Therefore, phase demodulation between the clock and the wobble signal (MSK waveform) occurs, so that proper demodulation cannot be performed. become.
The above-mentioned patent document 1 discloses a technique for correcting the phase of a clock generated in synchronization with a wobble signal. However, as described above, a non-modulation section (monotone wobble section) and a modulation section (MSK mark) There is no disclosure of a technique that can deal with a phase shift in the reverse direction in the section).

  In view of such a problem, the present invention can properly demodulate a wobble signal recorded as a wobbling groove on a disk recording medium and including a non-modulation section and a modulation section in accordance with the periodic phase shift. The purpose is to do.

The disk drive apparatus of the present invention comprises a reading means for reading a wobble signal including a non-modulation section and a modulation section recorded on a disk recording medium as a wobbling track (for example, a wobbling groove or a wobbling pit train), and a non-modulation section A clock generating means for generating a clock signal synchronized with the wobble signal, a demodulating means for demodulating the wobble signal using the clock signal, and a decoding process on the demodulated signal obtained by the demodulating means, Decoding means for obtaining information recorded as the wobbling track, relative phase correction means for correcting the relative phase of the clock signal supplied to the demodulation means and the wobble signal in the modulation section.
In this case, the relative phase correction means corrects the relative phase by shifting the phase of the clock signal or the wobble signal.
The relative phase correction means sets the correction amount of the relative phase based on the amplitude state of the wobble signal.
In particular, the relative phase correction means is configured to detect the amplitude value of the wobble signal in the non-modulation section and the wobble at or above the disk rotation period represented by (one wobble period) / (2 × π × track pitch). The correction amount of the relative phase is set based on a difference from the amplitude average value of the signal.
Alternatively, the relative phase correction means may be configured such that the modulation section in the section equal to or larger than the amplitude value of the wobble signal in the modulation section and the disc rotation period represented by (one wobble period) / (2 × π × track pitch). The correction amount of the relative phase is set based on the difference from the amplitude average value of the wobble signal.

The wobble reproduction method of the present invention is a wobble reproduction method for reproducing information recorded as a wobbling track on a disk recording medium. A step of reading a wobble signal recorded as the wobbling track and including a non-modulation section and a modulation section; a clock generation step of generating a clock signal synchronized with the wobble signal of the non-modulation section; and the clock signal A demodulating step for demodulating the wobble signal, a decoding step for decoding the demodulated signal obtained in the demodulating step, and reproducing information recorded as the wobbling track, and a demodulating step And a relative phase correction step for correcting the relative phase of the wobble signal in the modulation section.
In the relative phase correction step, the relative phase is corrected by shifting the phase of the clock signal or the wobble signal.
In the relative phase correction step, the relative phase correction amount is set based on the amplitude state of the wobble signal.
In particular, in the relative phase correction step, the wobble signal is not less than the amplitude value of the wobble signal in the non-modulation period and the disc rotation period represented by (one wobble period) / (2 × π × track pitch). The correction amount of the relative phase is set based on the difference from the amplitude average value.
Alternatively, in the relative phase correction step, the modulation section in the section equal to or larger than the amplitude value of the wobble signal in the modulation section and the disk rotation period represented by (one wobble period) / (2 × π × track pitch) The correction amount of the relative phase is set based on the difference from the amplitude average value of the wobble signal.

That is, in the present invention, there is a periodic wobble signal phase variation, and the direction of the phase shift is reversed between the non-modulation period (monotone wobble part) and the modulation period (MSK modulation period), and further the modulation. Since the clock signal for demodulating the signal is synchronized with the signal in the non-modulation period, the clock signal or wobble signal is moved to cope with a significant shift in the wobble signal phase in the modulation period with respect to the clock signal. And correct the relative phase. In other words, correction is performed so that the phase of the wobble signal in the modulation section and the phase of the clock signal synchronized with the non-modulation section are matched.
Here, the wobble signal undergoes phase fluctuation in a cycle of (wobble one cycle) / (2 × π × track pitch) round (for example, 2.7 rounds) depending on the wobble phase difference condition with the adjacent track. As the signal fluctuates, the wobble signal amplitude also fluctuates in the same cycle. When a track is formed by a wobbling groove, the “track pitch” in the above (one wobble period) / (2 × π × track pitch) is a groove pitch.
Therefore, for example, the amplitude level of the wobble signal serves as an index indicating the phase shift amount and the shift direction at that time, and therefore the amplitude level is detected and the phase shift amount of the clock signal or the wobble signal is changed accordingly. Thus, the relative phase can be corrected corresponding to the periodic phase shift.

According to the present invention, the relative phase of the modulation interval in the wobble signal and the clock signal for demodulating the modulation signal are periodically shifted, but the relative phase is changed to the periodic amplitude fluctuation of the wobble signal. Accordingly, the relative phase of the modulation signal and the clock signal is always matched, so that the demodulation process can be performed stably and accurately. As a result, the information recorded in the wobbling groove of the disk recording medium can be appropriately decoded, and the recording / reproducing operation performance can be improved.
In addition, this eliminates the need for the configuration of the demodulation circuit system and the component accuracy so as to cope with a large relative phase shift, and thus has the advantage that the cost reduction of the apparatus can be promoted.

Hereinafter, embodiments of the present invention will be described in the following order.

1. MSK modulation, STW modulation, and ADIP
2. 2. Configuration of disk drive device 3. Configuration and operation of MSK demodulation system Modified example

1. MSK modulation, STW modulation, and ADIP

As shown in FIG. 1A, the optical disk 1 corresponding to the embodiment of the present invention is formed with a groove GV serving as a recording track. The groove GV is formed in a spiral shape from the inner peripheral side to the outer peripheral side. Therefore, when the cut surface in the radial direction of the optical disc 1 is viewed, as shown in FIG. 1B, convex lands L and concave grooves GV are alternately formed.

As shown in FIG. 1B, the groove GV of the optical disk 1 is meandered in the tangential direction. The meandering shape of the groove GV is a shape corresponding to the wobble signal. Therefore, in the optical disk drive, both edge positions of the groove GV are detected from the reflected light of the laser spot LS irradiated to the groove GV, and the positions of both edge positions when the laser spot LS is moved along the recording track are detected. By extracting the fluctuation component with respect to the disk radial direction, the wobble signal can be reproduced.
In this wobble signal, address information (physical address, other additional information, etc.) of the recording track at the recording position is modulated. Therefore, in the optical disk drive, address control or the like at the time of data recording or reproduction can be performed by demodulating address information or the like from the wobble signal.

  In the embodiment of the present invention, an optical disk on which groove recording is performed will be described. However, the present invention is not limited to such an optical disk of groove recording, but is applied to an optical disk that performs land recording for recording data on a land. It is also possible to apply to a land-groove recording optical disk for recording data in the groove and land.

  Here, in the optical disc 1 of the present embodiment, the address information is modulated with respect to the wobble signal by using two modulation methods. One is an MSK (Minimum Shift Keying) modulation method. The other is an STW (Saw Tooth Wobble) that modulates by adding an even-order harmonic signal to a sine wave carrier signal and changing the polarity of the harmonic signal in accordance with the sign of the modulated data. Modulation method.

  In the optical disc 1 of the present embodiment, as shown in FIG. 3A, a block in which a reference carrier signal waveform of a sine wave of a predetermined frequency continues for a predetermined period is formed, and MSK-modulated address information is included in this block. Is generated, and a wobble signal provided with an STW modulation unit into which STW-modulated address information is inserted is generated. That is, MSK-modulated address information and STW-modulated address information are inserted at different positions in the block. Further, one of the two sine wave carrier signals used in the MSK modulation and the STW modulation carrier signal are used as the reference carrier signal. In addition, the MSK modulation unit and the STW modulation unit are arranged at different positions in the block, respectively, and a reference carrier signal of one cycle or more is arranged between the MSK modulation unit and the STW modulation unit. Yes.

  A non-modulated portion where no data is modulated and only the frequency component of the reference carrier signal appears is hereinafter referred to as monotone wobble. In the following, it is assumed that the sine wave signal used as the reference carrier signal is Cos (ωt). One period of the reference carrier signal is referred to as one wobble period. The frequency of the reference carrier signal is constant from the inner periphery to the outer periphery of the optical disc 1 and is determined according to the relationship with the linear velocity when the laser spot moves along the recording track.

Hereinafter, modulation methods of MSK modulation and STW modulation will be described in more detail. First, the address information modulation method using the MSK modulation method will be described.
The MSK modulation has a modulation index of 0.5 among FSK (Frequency Shift Keying) modulation in which phases are continuous. FSK modulation is a method of modulating two carrier signals of frequency f1 and frequency f2 by associating “0” and “1” of the code of modulated data with each other. In other words, if the modulated data is “0”, a sine wave waveform of frequency f1 is output, and if the modulated data is “1”, a sine wave waveform of frequency f1 is output. Further, in the case of FSK modulation with continuous phases, the phases of the two carrier signals are continuous at the timing of switching the code of the modulated data.
In this FSK modulation, a modulation index m is defined. This modulation index m is
m = | f1-f2 | T
Defined by Here, T is the transmission rate of modulated data (1 / the time of the shortest code length). The phase continuous FSK modulation when m is 0.5 is referred to as MSK modulation.

The MSK modulation waveform is shown in FIG. FIG. 2A shows a state in which MSK modulation waveforms (MM1, MM2, MM3) are present in a region of three wobble periods sandwiched between monotone wobbles MW.
If the monotone wobble is expressed as Cos (ωt) as described above, one of the two frequencies used for MSK modulation is the same frequency as the reference carrier signal and the other is 1.5 times the frequency of the reference carrier signal. Therefore, one of the signal waveforms used for MSK modulation is Cos (ωt) or -Cos (ωt), and the other is Cos (1.5ωt) or -Cos (1.5ωt).
2A shows two monotone wobbles, an MSK modulation region, and two monotone wobbles. In this case, the signal waveform of the MSK stream is Cos (wt) for each wobble period. , Cos (wt), Cos (1.5wt), -Cos (wt), -Cos (1.5wt), Cos (wt). In the drawing, monotone wobble Cos (ωt) = cos {2π · (fwob) · t} is shown (fwob is a reference carrier frequency). Therefore, the three wobble period as the MSK modulation region is MM1 = cos { 2π · (1.5 · fwob) · t}, MM2 = −cos {2π · (fwob) · t}, and MM3 = −cos {2π · (1.5 · fwob) · t}.
Thus, the first wobble cycle period (MM1) has a frequency 1.5 times that of the monotone wobble, the second (MM2) has the same frequency as the monotone wobble, and the third (MM3) has a frequency of 1.5 of the monotone wobble. The frequency is doubled, and the phase returns in this three wobble period. That is, the phase is continuous with the preceding and following monotone wobbles, and the second wobble (MM2) has a polarity reversed with respect to the monotone wobble.

In the optical disc 1, address information is modulated into the wobble signal by making the wobble signal into the MSK stream as described above, and this MSK modulated signal can be synchronously detected for the following reason.
When the modulated data is inserted into the wobble signal of the optical disc 1 by the MSK modulation method, first, the data stream of the modulated data is differentially encoded in units of clocks corresponding to the wobble period. That is, the difference calculation is performed on the modulated data stream and the delayed data delayed by one period of the reference carrier signal. The data that has been subjected to the differential encoding processing is referred to as pre-coded data. Subsequently, the precoded data is MSK modulated to generate the MSK stream as described above.

  The differential encoded data (precode data) has a bit ("1") at the sign change point of the modulated data. Since the code length of the modulated data is at least twice the wobble period, the reference carrier signal (Cos (ωt)) or its inverted signal (−Cos (ωt) is always included in the latter half of the code length of the modulated data. )) Will be inserted. When the bit of the precode data is “1”, a waveform having a frequency 1.5 times that of the reference carrier signal is inserted, and the waveform is connected in phase at the sign switching point. Therefore, the signal waveform inserted in the latter half of the code length of the modulated data is always the reference carrier signal waveform (Cos (ωt)) if the modulated data is “0”, and the modulated data is “1”. If so, the inverted signal waveform (-Cos (ωt)) is always obtained. The synchronous detection output has a positive value if the phase is in phase with the carrier signal, and a negative value if the phase is inverted. Therefore, the MSK modulated signal as described above is used as the reference carrier. If synchronous detection is performed using a signal, the modulated data can be demodulated.

Next, STW modulation will be described.
In STW modulation, as described above, an even-order harmonic signal is added to a sinusoidal carrier signal, and the polarity of the harmonic signal is changed in accordance with the code of the modulated data to modulate the digital code. Modulation method.
In the optical disc 1, the STW modulated carrier signal is a signal having the same frequency and phase as the reference carrier signal (Cos (ωt)), which is the MSK modulated carrier signal. The even-order harmonic signals to be added are Sin (2ωt) and −Sin (2ωt), which are the second-order harmonics of the reference carrier signal (Cos (ωt)), and the amplitude thereof is relative to the amplitude of the reference carrier signal. The amplitude is −12 dB. The minimum code length of the modulated data is set to twice the wobble period (period of the reference carrier signal).
When the code of the modulated data is “1”, Sin (2ωt) is added to the carrier signal, and when it is “0”, modulation is performed by adding −Sin (2ωt) to the carrier signal.

FIG. 2B shows a signal waveform when the wobble signal is modulated by the above method. FIG. 2B shows the signal waveform of the monotone wobble MW of the reference carrier signal (Cos (ωt)) in the central wobble period. In the previous two wobble periods, a signal waveform in which Sin (2ωt) is added to the reference carrier signal (Cos (ωt)), that is, a signal waveform when the modulated data is “1” is shown. Yes. Further, in the 2 wobble period after the monotone wobble MW, a signal waveform in which −Sin (2ωt) is added to the reference carrier signal (Cos (ωt)), that is, a signal waveform when the modulated data is “0”. Is shown.
In the drawing, monotone wobble Cos (ωt) = cos {2π · (fwob) · t} is shown. Therefore, when the modulated data is “1”, the STW modulated signal is cos {2π · (fwob). ) · T} + a · sin {2π · (2 · fwob) · t}, and when the modulated data is “0”, cos {2π · (fwob) · t} −a · sin {2π · (2 · fwob) · t}.
As can be seen from the figure, this STW signal waveform rises steeply on the outer periphery of the disk and gently returns to the inner periphery, and conversely, rises with a gentle slope on the outer periphery of the disk and returns sharply. Values of “1” and “0” are expressed. In either case, the waveform has a common zero cross point with the monotone wobble MW indicated by a broken line. Therefore, in extracting the clock from the fundamental wave component common to the MSK monotone wobble MW portion, the phase is not affected.

Then, when positive and negative even harmonic signals are added to the reference carrier signal in this way, from the characteristics of the generated waveform, synchronous detection is performed using this harmonic signal, and the code data of the modulated data is It is possible to demodulate the modulated data by integrating the synchronous detection output.
In the optical disc 1, the harmonic signal added to the carrier signal is a second harmonic, but not limited to the second harmonic, any signal may be added as long as it is an even harmonic. Further, in the optical disc 1, only the second harmonic is added, but a plurality of harmonic signals may be added simultaneously such that both the second harmonic and the fourth harmonic are added simultaneously.

An ADIP structure including MSK modulation and STW modulation as described above will be described. One unit (ADIP unit) as ADIP information is composed of 56 wobbles.
FIG. 3B shows eight types of ADIP units. The eight types are a monotone unit, a reference unit, a sync 0 unit, a sync 1 unit, a sync 2 unit, a sync 3 unit, a data 1 unit, and a data 0 unit.
In all eight types of ADIP units, the leading wobble numbers 0, 1, and 2 are MSK marks.
In the monotone unit, the wobble numbers 4 to 55 following the MSK mark are all composed of monotone wobbles.
The reference unit is an STW modulation wobble in which wobble numbers 18 to 54 indicate a zero value.
Each of the sync 0 unit, the sync 1 unit, the sync 2 unit, and the sync 3 unit is an ADIP unit for sync information, and an MSK mark is arranged at a predetermined wobble number position as illustrated.
The data 1 unit represents the value “1”, and the data 0 unit represents the value “0”. In the case of 1 data unit, the MSK mark is arranged in the wobble numbers 12 to 14, and the wobble numbers 18 to 54 are STW modulated wobbles having the value “1”. In the case of data 0 unit, the MSK mark is arranged in the wobble numbers 14 to 16, and the wobble numbers 18 to 54 are STW modulation wobbles having the value “0”.

By collecting 83 such ADIP units, one piece of ADIP information (address information) is formed.
That is, as shown in FIG. 4, one unit of ADIP information is formed by ADIP units 0-82. ADIP unit numbers 0 to 7 are a monotone unit, a sync 0 unit, a monotone unit, a sync 1 unit, a monotone unit, a sync 2 unit, a monotone unit, and a sync 3 unit.
After the ADIP unit number 8, five units as a reference unit and a 4-bit data unit are repeatedly arranged. Each data unit (for example, data [0], data [1], data [2], data [3]... Data [59]) is either one of the data 1 unit or data 0 unit. , A 60-bit value as ADIP information is shown. These 60 bits include an address value, additional information, ECC parity, and the like.

2. Configuration of disk drive device

Next, the disk drive device of the present embodiment that can perform recording / reproduction corresponding to the disk 1 as described above will be described. FIG. 5 shows the configuration of the disk drive device.
The disk 1 is loaded on a turntable (not shown) and is driven to rotate at a constant linear velocity (CLV) by a spindle motor 52 during a recording / reproducing operation.
Then, ADIP information embedded as wobbling of the groove track on the disk 1 is read by the optical pickup (optical head) 51.
On the disk 1, for example, physical information of the disk is recorded as reproduction-only management information by embossed pits or wobbling grooves. Reading of these information is also performed by the pickup 51.
When data is recorded, user data is recorded on the track as a phase change mark by the optical pickup, and at the time of reproduction, the mark recorded by the optical pickup is read.

  In the pickup 51, a laser diode serving as a laser light source, a photodetector for detecting reflected light, an objective lens serving as an output end of the laser light, and a laser recording light are irradiated onto the disk recording surface via the objective lens. An optical system (not shown) for guiding the reflected light to the photodetector is formed. The laser diode outputs a so-called blue laser having a wavelength of 405 nm, for example. The NA by the optical system is 0.85.

The objective lens is held in the pickup 51 so as to be movable in the tracking direction and the focus direction by a biaxial mechanism.
The entire pickup 51 can be moved in the radial direction of the disk by a thread mechanism 53.
The laser diode in the pickup 51 is driven to emit laser light by a drive signal (drive current) from the laser driver 63.

Reflected light information from the disk 1 is detected by a photo detector, converted into an electric signal corresponding to the amount of received light, and supplied to the matrix circuit 54.
The matrix circuit 54 includes a current-voltage conversion circuit, a matrix calculation / amplification circuit, and the like corresponding to output currents from a plurality of light receiving elements as photodetectors, and generates necessary signals by matrix calculation processing.
For example, a high frequency signal (reproduction data signal) corresponding to reproduction data, a focus error signal for servo control, a tracking error signal, and the like are generated.
Further, a push-pull signal is generated as a signal related to groove wobbling, that is, a signal for detecting wobbling.
The reproduction data signal output from the matrix circuit 54 is supplied to the data signal processing circuit 55, the focus error signal and tracking error signal are supplied to the optical block servo circuit 61, and the push-pull signal is supplied to the wobble signal processing circuit 65.

The data signal processing circuit 55 performs binarization processing, reproduction clock generation processing by PLL, and the like on the reproduction data signal, reproduces data read out as a phase change mark, for example, and supplies the data to the data demodulation circuit 56 .
The data demodulation circuit 56 performs a run-length limited code demodulation process based on the reproduction clock as a decoding process during reproduction. The demodulated data is supplied to the ECC encoder / decoder 57.
The ECC encoder / decoder 57 performs an ECC encoding process for adding an error correction code during recording and an ECC decoding process for performing error correction during reproduction.
At the time of reproduction, the data demodulated by the data demodulation circuit 56 is taken into an internal memory, and error detection / correction processing and deinterleaving processing are performed to obtain reproduction data.
Data decoded up to reproduction data by the ECC encoder / decoder 57 is read based on an instruction from the system controller 60 and transferred to an AV (Audio-Visual) system 120.

The push-pull signal output from the matrix circuit 54 as a signal related to groove wobbling is converted into wobble data digitized by the wobble signal processing circuit 65. A wobble clock having a wobble frequency is generated as a clock synchronized with the push-pull signal by the PLL process.
The wobble data is subjected to MSK demodulation and STW demodulation by the ADIP demodulating circuit 66 by a process using a wobble clock or a clock generated by multiplying the wobble clock, demodulated into a data stream constituting an ADIP address, and supplied to the address decoder 59. Is done.
The address decoder 59 decodes the supplied data, obtains an address value, and supplies it to the system controller 60.

At the time of recording, recording data is transferred from the AV system 120. The recording data is sent to a memory in the ECC encoder / decoder 57 and buffered.
In this case, the ECC encoder / decoder 57 performs error correction code addition, interleaving, subcode addition, and the like as encoding processing of the buffered recording data.
Further, the ECC encoded data is subjected to RLL (1-7) PP modulation (RLL: Run Length Limited, PP: Parity preserve / Prohibit rmtr (repeated minimum transition runlength)) in the recording pulse conversion circuit 64. Note that a clock generated from a wobble signal is used as an encoding clock which is a reference clock for the encoding process during recording.

  The recording data generated by the encoding process in the recording pulse conversion circuit 64 is finely adjusted by the laser driver 63 as the recording compensation process for the optimum recording power for the recording layer characteristics, laser beam spot shape, recording linear velocity, etc. Adjustment of the laser drive pulse waveform is performed. The laser driver 63 applies the laser drive pulse subjected to the recording compensation process to the laser diode in the pickup 51 to execute laser light emission driving. As a result, pits (phase change marks) corresponding to the recording data are formed on the disc 1.

  The laser driver 63 includes a so-called APC circuit (Auto Power Control), and the laser output is not dependent on the temperature or the like while monitoring the laser output power by the output of the laser power monitoring detector provided in the pickup 51. Control to be constant. The target value of the laser output at the time of recording and reproduction is given from the system controller 60, and the laser output level is controlled to be the target value at the time of recording and reproduction.

The optical block servo circuit 61 generates various servo drive signals for focus, tracking, and thread from the focus error signal and tracking error signal from the matrix circuit 54, and executes the servo operation.
That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal and the tracking error signal, and the focus coil and tracking coil of the biaxial mechanism in the pickup 51 are driven by the biaxial driver 68. As a result, the pickup 51, the matrix circuit 54, the optical block servo circuit 61, the biaxial driver 68, and the tracking servo loop and the focus servo loop by the biaxial mechanism are formed.
The optical block servo circuit 61 turns off the tracking servo loop and outputs a jump drive signal in response to a track jump command from the system controller 60, thereby executing a track jump operation.
The optical block servo circuit 61 generates a thread drive signal based on a thread error signal obtained as a low frequency component of the tracking error signal, access execution control from the system controller 60, and the like. To drive. Although not shown, the sled mechanism 53 has a mechanism including a main shaft that holds the pickup 51, a sled motor, a transmission gear, and the like, and by driving the sled motor in accordance with a sled drive signal, a required slide of the pickup 51 is obtained. Movement is performed.

The spindle servo circuit 62 controls the spindle motor 52 to perform CLV rotation.
The spindle servo circuit 62 obtains the clock generated by the PLL processing for the wobble signal as the current rotational speed information of the spindle motor 52 and compares it with predetermined CLV reference speed information to generate a spindle error signal. .
At the time of data reproduction, the reproduction clock (clock serving as a reference for decoding processing) generated by the PLL in the data signal processing circuit 55 becomes the current rotational speed information of the spindle motor 52. A spindle error signal can also be generated by comparing with the reference speed information.
The spindle servo circuit 62 outputs a spindle drive signal generated in accordance with the spindle error signal, and causes the spindle driver 67 to execute CLV rotation of the spindle motor 52.
The spindle servo circuit 62 generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 60, and executes operations such as starting, stopping, acceleration, and deceleration of the spindle motor 52.

Various operations of the servo system and the recording / reproducing system as described above are controlled by a system controller 60 formed by a microcomputer.
The system controller 60 executes various processes according to commands from the AV system 120.
For example, when a write command (write command) is issued from the AV system 120, the system controller 60 first moves the pickup 51 to the address to be written. Then, the ECC encoder / decoder 57 and the recording pulse conversion circuit 64 cause the encoding process to be performed on the data transferred from the AV system 120 (for example, video data of various systems such as MPEG2 or audio data) as described above. The laser driver 63 drives to emit light in accordance with the encoded data as described above, and recording is performed.

For example, when a read command for transferring certain data (MPEG2 video data or the like) recorded on the disk 1 is supplied from the AV system 120, seek operation control is first performed for the instructed address. That is, a command is issued to the optical block servo circuit 61 to cause the pickup 51 to access the address specified by the seek command.
Thereafter, operation control necessary for transferring the data in the designated data section to the AV system 120 is performed. That is, data reading from the disk 1 is performed, decoding / buffering in the data signal processing circuit 55, the data demodulation circuit 56, and the ECC encoder / decoder 57 is executed, and the requested data is transferred.

  At the time of data recording / reproducing by these phase change marks, the system controller 60 controls access and recording / reproducing operations using ADIP addresses detected by the wobble signal processing circuit 65, the ADIP demodulating circuit 66, and the address decoder 59. I do.

Incidentally, although the example of FIG. 5 is a disk drive device connected to the AV system 120, the disk drive device of the present invention may be connected to, for example, a personal computer.
Furthermore, there may be a form that is not connected to other devices. In that case, an operation unit and a display unit are provided, and the configuration of the interface part for data input / output is different from that in FIG. That is, it is only necessary that recording and reproduction are performed in accordance with a user operation and a terminal unit for inputting / outputting various data is formed.
Of course, there are various other configuration examples. For example, examples of a recording-only device and a reproduction-only device are also possible.

3. Configuration and operation of MSK demodulation system

Next, the configuration and operation of the MSK demodulation system formed in the wobble signal processing circuit 65 and the ADIP demodulation circuit 66 will be described. The ADIP demodulation circuit 66 is also provided with a demodulation system for STW modulation signals, but illustration and description of the STW demodulation system are omitted.
FIG. 6 shows only the circuit system for obtaining the ADIP information by MSK demodulating the wobble signal in the configuration of FIG. As described above, the push-pull signal P / P from the matrix circuit 54 is supplied to the wobble signal processing circuit 65 as a read signal (wobble signal) corresponding to the wobbling groove.
The wobble signal processing circuit 65 includes a band pass filter 11, an A / D converter 12, a clock generation unit 13, a phase shift unit 14, and a phase shift control unit 15.

  The push-pull signal P / P input from the matrix circuit 54 described above as a wobbling groove modulation signal (wobble signal) is band-limited by the band-pass filter 11 in the wobble signal processing circuit 65 and then converted into an A / D converter. 12 is converted into digital data. The band-pass filter 11 is a filter that passes only the wobble signal band. As a result, the DC component and the noise component in the high frequency band are removed, and A / D conversion is performed.

The output of the band pass filter 11 is also supplied to the clock generation unit 13 and the phase shift control unit 15.
The clock generation unit 13 includes a PLL circuit, and generates a wobble clock WCK synchronized with the wobble signal that is the output of the bandpass filter 11. The wobble clock WCK is a clock having a wobble basic frequency, that is, a monotone wobble frequency, and is generated as a clock synchronized with the monotone wobble timing.
The wobble clock WCK is phase-corrected by the phase shifter 14 and supplied to the ADIP demodulation circuit 66.
The clock generation unit 13 multiplies the wobble clock WCK to generate a clock SCK, and supplies this as a sampling clock for the A / D converter 12.
The phase shift control unit 15 sets the phase shift amount in the phase shift unit 14, that is, the phase shift correction amount. For example, amplitude detection is performed on the input wobble signal, and the phase shift amount in the phase shift unit 14 is set based on the amplitude level.
The phase shift unit 14 performs phase shift of the wobble clock WCK according to the phase shift amount set by the phase shift control unit 15 and supplies it to the ADIP demodulation circuit 66.

The data (wobble data WD) sampled by the A / D converter 12 is supplied to the MSK demodulation circuit 20 in the ADIP demodulation circuit 66, and MSK demodulation processing is performed.
The MSK demodulation circuit 20 demodulates the input wobble data WD using the wobble clock WCK and outputs an MSK demodulated signal. In this MSK demodulation circuit 20, as described with reference to FIG. 3, an internal reference wave (sine wave or cosine wave) having the same frequency as the wobble frequency is multiplied and integrated with respect to the wobble data WD containing the MSK mark. To do. Integration is performed every wobble period. In this case, the integral value moves in the positive direction in the wobble fundamental wave section in the input wobble data, while it moves in the negative direction in the MSK modulated section. An MSK demodulated signal for discriminating the fundamental wave is obtained.
The wobble data WD from the A / D converter 12 is also supplied to an STW demodulation circuit (not shown) in the ADIP demodulation circuit 66, and STW demodulation processing is performed to obtain an STW demodulated signal.

The MSK demodulated signal demodulated by the MSK demodulating circuit 20 of the ADIP demodulating circuit 66 and the STW demodulated signal (not shown) are supplied to the address decoder 59. Then, the address decoder 59 decodes and corrects the error to obtain ADIP information, which is supplied to the system controller 60.
The address decoder 59 establishes synchronization (bit sync) of each unit in FIG. 3B based on the MSK demodulated signal, and then confirms the word sync of the sync 0 unit to the sync 3 unit to establish synchronization. That is, by detecting the MSK mark (wobble number 0, 1, 2) at the head of each unit, after synchronizing each unit, the sync placed at the head of the 83 units of the ADIP information unit shown in FIG. By detecting 0 unit to 3 sync units, synchronization of the entire ADIP address is established. Thereby, the MSK mark position of the data 0 unit and the data 1 unit and the STW modulation position of the data 0 unit, the data 1 unit and the reference unit are established, and the address data is read.

The operations of the phase shift unit 14 and the phase shift control unit 15 in such an MSK demodulation system will be described.
As described above, the wobble signal shifts from the original phase due to the influence of the adjacent track, particularly the phase condition with the wobble of the adjacent track. Assuming that the wobble wavelength in the monotone region is a constant value wl and the groove pitch is tp, the condition of the phase difference from the adjacent track repeatedly varies every wl / (2 × π × tp) rotation period. In the case of the disc 1 (Blu-ray disc format) of this example, this corresponds to 2.7 rotations as the disc rotation.
Since a phase shift occurs depending on the phase condition of the wobble signal with the adjacent track, the phase of the wobble signal read from the disk 1 becomes faster or slower than the original phase during 2.7 rounds. To do.
Furthermore, when the phase is delayed in the MSK modulation section, the phase fluctuation is in a state in which the phase advances in the preceding and following monotone wobble sections, and conversely, in the case where the phase is advanced in the MSK modulation section, the preceding and following monotones. The phase is delayed in the wobble section.
For this reason, as described with reference to FIGS. 9 and 10, the phase of the wobble signal in the MSK mark portion may be greatly shifted with respect to the wobble clock WCK synchronized with the monotone wobble timing, and proper MSK demodulation cannot be performed. .

Therefore, in this example, the phase shift unit 14 corrects the phase of the wobble clock WCK supplied to the MSK demodulation circuit 20, and the relative phase between the wobble clock WCK and the wobble data WD supplied to the MSK demodulation circuit 20 (in the MSK mark period). The relative phase is adjusted to an appropriate level for the demodulation process.
And since the amount of phase shift in the 2.7 round cycle changes continuously, the amount of phase shift in the phase shift section 14 must also be changed continuously. Therefore, the phase shift control unit 15 sets the phase shift amount according to the amplitude of the wobble signal.
The wobble amplitude in the monotone area in the wobble signal is always constant if there is no wobble in the adjacent track, but varies depending on the phase difference condition with the wobble in the adjacent track. Since this phase condition is repeated every wl / (2 × π × tp) rotation period (for example, 2.7 laps), the wobble amplitude is also increased or decreased for each wl / (2 × π × tp) rotation period. Therefore, since the amplitude fluctuation becomes an index of the phase shift amount and the shift direction, by setting the phase shift amount according to the amplitude of the wobble signal, the phase of the MSK modulation section of the wobble signal always matches the phase of the wobble clock WCK. Thus, phase shift can be performed.
The fluctuation of the monotone wobble amplitude is shown in the wobble signal waveforms I, II, and III shown in FIGS.

FIG. 7A shows the same waveform as in FIG. 10A described above. For example, a wobble clock WCK synchronized with a monotone wobble is shown in FIG. 7B. When viewed from the wobble clock WCK in FIG. 7B, the thick wobble signal waveform I in FIG. 7A is in phase, but with respect to the wobble signal waveforms II and III in which a phase shift occurs. There is a large phase shift.
Therefore, when the waveform of the wobble signal becomes the waveform II whose phase is advanced at the MSK mark portion, the phase shift unit 14 shifts the phase so that the phase of the wobble clock WCK advances, and the wobble clock shown in FIG. WCK is supplied to the MSK demodulation circuit 20.
When the wobble signal waveform is a waveform III whose phase is delayed at the MSK mark portion, the phase shift unit 14 shifts the phase of the wobble clock WCK so that the wobble clock shown in FIG. WCK is supplied to the MSK demodulation circuit 20.
By continuously performing such phase shift processing, the MSK demodulation circuit 20 can always supply the wobble data WD and the wobble clock WCK that are relatively in phase with each other, and perform appropriate MSK demodulation.
When phase correction is performed in this way, a phase shift occurs in the monotone region, but the effect of improving the demodulation performance in the MSK mark period is great, which is advantageous as a result.

  As the phase shift amount setting process in the phase shift control unit 15, the following examples (1) and (2) are conceivable.

(1) The amplitude value of the wobble signal in the monotone section and the average amplitude value of the wobble signal in the disk rotation period represented by (one wobble cycle) / (2 × π × groove pitch) or a longer section Set the amount of phase shift based on the difference.
As can be seen from the wobble signal waveforms I, II, and III shown in FIGS. 7A and 9, the amplitude of the monotone wobble varies periodically. Therefore, the difference between (average wobble period) / (2 × π × groove pitch), that is, the average monotone wobble amplitude over 2.7 turns and the monotone wobble amplitude obtained in a short section is Since it can be considered as a signal corresponding to the phase difference from the wobble, an appropriate phase shift amount can be obtained as a value roughly proportional to the difference. That is, the phase shift amount can be set by estimating the phase shift state within 2.7 laps.
In this case, the amplitude value of the wobble signal in the monotone section may be an amplitude value sampled in a certain monotone area or an average amplitude value in a plurality of monotone areas. Alternatively, it may be an amplitude average value in a certain long section including the MSK modulation section.
For example, a section of 1 to several tens of wobbles in which monotone wobbles are continuous in the ADIP unit described with reference to FIG. 3 may be used. Naturally, the average amplitude value in this section indicates the amplitude value in the monotone section.
Further, for example, the average amplitude value of 56 wobble periods at an arbitrary timing corresponding to one ADIP unit length period may be used. The arbitrary 56 wobble period means that it is not necessary to be 56 wobbles as 56 wobbles from the head as an ADIP unit. In other words, it is not limited to 56 wobbles in a synchronized state as an ADIP unit, but simply a 56 wobble period from an appropriate timing. As can be seen from the ADIP structure of FIG. 3, in the 56 wobble period, an MSK mark portion (a section that is not a monotone area) always appears once. However, since the monotone wobble is the majority, the monotone section is considered as an average value. This is because it can be regarded as the amplitude value of the wobble signal.
Of course, the present invention is not limited to these, and various methods may be used to obtain the amplitude value of the wobble signal in the monotone section. That is, it is appropriate to set the amplitude average value in a section sufficiently shorter than the disk rotation period expressed by (one wobble period) / (2 × π × groove pitch) and sufficiently longer than the length of the MSK modulation section.
For the wobble signal, the phase shift control unit 15 first obtains an average amplitude value in a (wobble one cycle) / (2 × π × groove pitch) cycle, that is, a period of 2.7 rounds. Alternatively, it may be a period of 2.7 laps or more. However, an integer multiple of 2.7 rounds is appropriate.
In the MSK mark region, the phase condition is disturbed and the amplitude is also disturbed. However, this effect can be avoided by detecting the amplitude of the monotone region in a band not affected by this. In other words, by performing amplitude detection in a band that corresponds to fluctuations within the 2.7 rotation period and does not correspond to amplitude fluctuations in the MSK mark region, the period of 2.7 periods (or more) An average amplitude value of monotone wobble can be obtained.
Further, the phase shift control unit 15 obtains the amplitude value of the monotone section in the same band. For example, an average amplitude value is obtained every 56 wobble periods and is regarded as an amplitude value in a monotone section.
Then, the phase shift control unit 15 obtains the difference between the amplitude value of the monotone section and the average amplitude value of the monotone wobble for 2.7 periods. This is repeated every 56 wobble periods.
The difference between the obtained average amplitude values is a numerical value corresponding to the relative phase shift amount within 2 to 7 cycles. Therefore, the phase shift amount for relative phase correction can be calculated based on the difference between the amplitude average values.
By this process, for example, the phase shifter 14 changes the amount of phase shift every 56 wobble periods, thereby constantly matching the relative phases of the wobble clock WCK and the wobble data WD.

(2) The amplitude value of the wobble signal in the MSK modulation section and the average amplitude of the wobble signal in the MSK modulation section in the section longer than the disk rotation period expressed by (one wobble period) / (2 × π × groove pitch) The phase shift amount is set based on the difference from the value.
As can be seen from the wobble signal waveforms I, II, and III shown in FIGS. 7A and 9, the amplitude in the MSK modulation section also periodically varies. Therefore, (wobble one cycle) / (2 × π × groove pitch), that is, the average value of the wobble amplitude in the MSK modulation area in a period of 2.7 or more and the difference between the wobble amplitudes in a certain MSK modulation section is also adjacent. Since it can be considered as a signal corresponding to the phase difference from the wobble of the track, an appropriate phase shift amount can be obtained as a value roughly proportional to this difference.
In this case, for the wobble signal, the phase shift control unit 15 firstly has a (wobble one period) / (2 × π × groove pitch) period, that is, a period of 2.7 rounds (or longer period: preferably 2.7). Amplitude average value in the MSK modulation region appearing in a period of an integral multiple of the circumference) is obtained.
Then, for example, the amplitude value of the MSK modulation area that appears at least once every 56 wobble periods is obtained. Then, the difference between the amplitude value of the MSK modulation region and the average amplitude value of the MSK modulation region over 2.7 periods is obtained, and the phase shift amount is set according to the difference. This is repeated every 56 wobble periods.
In this way, for example, the phase shift amount is set for every 56 wobble periods, and the phase shift unit 14 changes the phase shift amount for each 56 wobble periods, thereby constantly changing the relative phase between the wobble clock WCK and the wobble data WD. Match.

However, for the process (2), the MSK modulation section in the wobble signal must be known. Therefore, the processing of (2) can be performed after ADIP synchronization is established in the subsequent address decoder 59.
As described above, the address decoder 59 synchronizes the ADIP unit (bit sync) based on the MSK demodulated signal, and then confirms the word sync of the sync 0 unit to the sync 3 unit to establish synchronization. As a result, the MSK modulation section in the wobble signal can be discriminated. In that case, the phase shift control unit 15 may receive the timing signal from the address decoder 59 and detect the amplitude in the MSK modulation period.
Even after the ADIP synchronization is established, the ADIP demodulation performance can be improved by performing the phase shift correction in the phase shift unit 14.
Note that the method (1) can be executed regardless of before and after the synchronization is established because ADIP synchronization is not possible.

As described above, in the present embodiment, the relative phase between the MSK modulation section in the wobble data WD and the wobble clock signal WCK for demodulating the MSK modulation signal is periodically shifted. Since the correction is made in accordance with the periodic amplitude fluctuation of the wobble signal and the relative phase of the MSK modulation waveform and the clock signal is always matched, the demodulation process can be performed stably and accurately. As a result, the information recorded in the wobbling groove of the disc 1 can be appropriately decoded and the reading accuracy of the ADIP address can be improved, so that the recording / reproducing operation performance can be improved.
Further, this eliminates the need for the configuration of the demodulation circuit system and the component accuracy to cope with a large shift in the relative phase, thereby promoting cost reduction of the apparatus.

4). Modified example

Although the embodiment has been described above, various modifications of the present invention are conceivable.
In the above example, the phase correction unit 14 performs phase correction on the wobble clock WCK, but it may be configured as shown in FIG.
That is, the wobble data WD output from the A / D converter 12 is phase-corrected by the phase shift unit 16 and supplied to the ADIP demodulating circuit 66. The wobble clock WCK from the clock generator 13 is supplied to the ADIP demodulator circuit 66 without performing a phase shift process.
The phase shift amount of the phase shift unit 16 is set by the phase shift control unit 15 by the methods (1) and (2) described above. Naturally, the phase shift direction is opposite to that when the wobble data WD is phase shifted.
Since the MSK modulation section of the wobble data WD and the relative phase of the wobble clock WCK need only be matched, it goes without saying that the wobble data WD may be phase-shifted. Therefore, the same effect as described above can be obtained with the configuration shown in FIG.

Also, in the above example, an example of an information demodulating device using a wobbling groove of a phase change recording disk is given. However, the present invention is not limited to a wobbling groove of a disk of another recording system such as a dye film changing system or a magneto-optical recording system. It can also be applied to demodulation.
The present invention can also be applied to a disc in which a groove is a recording track, a disc in which a land is a recording track, and a read-only disc in which a track is formed by a so-called embossed pit row. For example, the present invention is effective for a disc system in which address information and the like are recorded by wobbling an embossed pit string.

It is explanatory drawing of the wobbling groove of a disk. It is explanatory drawing of the MSK modulation wave and STW modulation wave of a wobble signal. It is explanatory drawing of an ADIP unit. It is explanatory drawing of ADIP information formed from an ADIP unit. 1 is a block diagram of a disk drive device according to an embodiment. It is a block diagram of the MSK demodulation system of an embodiment. It is explanatory drawing of the relative phase correction | amendment operation | movement of embodiment. It is a block diagram of the other MSK demodulation system of an embodiment. It is explanatory drawing of the periodic phase shift of a wobble signal. It is explanatory drawing of the relationship between the periodic phase shift of a wobble signal, and a clock.

Explanation of symbols

1 disk, 11 BPF, 12 A / D converter, 13 clock generation unit, 14, 16 phase shift unit, 15 phase shift control unit, 51 pickup, 52 spindle motor, 53 thread mechanism, 54 matrix circuit, 59 address decoder, 65 wobble signal processing circuit, 66 ADIP demodulation circuit, 60 system controller

Claims (12)

Reading means for reading a wobble signal including a non-modulation section and a modulation section recorded as a wobbling track on a disk recording medium;
Clock generating means for generating a clock signal synchronized with the wobble signal in the non-modulation period;
Demodulating means for demodulating the wobble signal using the clock signal;
Decoding means for performing a decoding process on the demodulated signal obtained by the demodulating means to obtain information recorded as the wobbling track;
Relative phase correction means for correcting the relative phase between the clock signal supplied to the demodulation means and the wobble signal in the modulation section;
A disk drive device comprising:   2. The disk drive device according to claim 1, wherein the relative phase correcting unit corrects the relative phase by shifting the phase of the clock signal.   2. The disk drive device according to claim 1, wherein the relative phase correcting unit corrects the relative phase by shifting the phase of the wobble signal.   2. The disk drive device according to claim 1, wherein the relative phase correction unit sets the correction amount of the relative phase based on an amplitude state of the wobble signal.   The relative phase correction means includes the amplitude value of the wobble signal in the non-modulation section and the amplitude of the wobble signal at or above the disk rotation period expressed by (one wobble period) / (2 × π × track pitch). 2. The disk drive device according to claim 1, wherein the correction amount of the relative phase is set based on a difference from the average value.   The relative phase correction means is configured to detect the amplitude value of the wobble signal in the modulation interval and the modulation interval in the interval equal to or greater than the disc rotation period expressed by (one wobble period) / (2 × π × track pitch). 2. The disk drive device according to claim 1, wherein the relative phase correction amount is set based on a difference from an amplitude average value of the wobble signal. As a wobble reproduction method for reproducing information recorded as a wobbling track on a disk recording medium,
Reading out a wobble signal recorded as the wobbling track, including a non-modulation section and a modulation section;
A clock generation step of generating a clock signal synchronized with the wobble signal in the non-modulation period;
A demodulation step for demodulating the wobble signal using the clock signal;
A decoding step for performing a decoding process on the demodulated signal obtained in the demodulation step and reproducing the information recorded as the wobbling track;
A relative phase correction step for correcting the relative phase of the clock signal supplied to the processing of the demodulation step and the wobble signal of the modulation section;
A wobble reproduction method comprising:   8. The wobble reproduction method according to claim 7, wherein in the relative phase correction step, the relative phase is corrected by shifting the phase of the clock signal.   8. The wobble reproduction method according to claim 7, wherein in the relative phase correction step, the relative phase is corrected by shifting the phase of the wobble signal.   8. The wobble reproduction method according to claim 7, wherein in the relative phase correction step, the correction amount of the relative phase is set based on an amplitude state of the wobble signal.   In the relative phase correcting step, the amplitude value of the wobble signal in the non-modulation section and the amplitude of the wobble signal in the disc rotation period or more represented by (wobble one period) / (2 × π × track pitch) 8. The wobble reproduction method according to claim 7, wherein the correction amount of the relative phase is set based on a difference from the average value. In the relative phase correction step, the amplitude value of the wobble signal in the modulation interval and the modulation interval in the interval greater than or equal to the disc rotation period represented by (one wobble period) / (2 × π × track pitch). 8. The wobble reproduction method according to claim 7, wherein the relative phase correction amount is set based on a difference from an amplitude average value of the wobble signal.

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