WO2012161009A1 - Procédé de reproduction et dispositif de reproduction - Google Patents

Procédé de reproduction et dispositif de reproduction Download PDF

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Publication number
WO2012161009A1
WO2012161009A1 PCT/JP2012/062268 JP2012062268W WO2012161009A1 WO 2012161009 A1 WO2012161009 A1 WO 2012161009A1 JP 2012062268 W JP2012062268 W JP 2012062268W WO 2012161009 A1 WO2012161009 A1 WO 2012161009A1
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WO
WIPO (PCT)
Prior art keywords
track
reproduction
tracks
pitch
recording
Prior art date
Application number
PCT/JP2012/062268
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English (en)
Japanese (ja)
Inventor
紀彰 西
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ソニー株式会社
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Publication date
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Publication of WO2012161009A1 publication Critical patent/WO2012161009A1/fr

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
    • G11B7/0903—Multi-beam tracking systems
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
    • G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
    • G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/2407—Tracks or pits; Shape, structure or physical properties thereof
    • G11B7/24073—Tracks

Definitions

  • the present disclosure relates to a reproduction method and a reproduction apparatus, and more particularly to a technique for performing proper reproduction on a recording medium on which high-density recording has been performed with a narrow track pitch.
  • reproduction-only discs and recordable discs belonging to the categories such as CD (Compact Disc), DVD (Digital Versatile Disc), Blu-ray Disc (Blu-ray Disc (registered trademark)) have been developed. ing.
  • CD Compact Disc
  • DVD Digital Versatile Disc
  • Blu-ray Disc Blu-ray Disc (registered trademark)
  • next-generation disc further increase in capacity by high-density recording is required.
  • the directionality of high-density recording in a disk-shaped recording medium includes multiple recording layers, increasing the recording density in the track line direction, increasing the recording density in the track pitch direction (narrow track pitch), It is conceivable to increase the recording capacity by signal processing such as data compression processing.
  • the present disclosure focuses on increasing the recording density in the track pitch direction.
  • a laser spot is irradiated onto the information recording track, and data is reproduced from the reflected light information.
  • the track pitch on the optical disc is narrower than the pitch corresponding to the optical cutoff, good reflected light information cannot be obtained.
  • tracking direction information cannot be obtained.
  • the laser spot cannot be appropriately traced on the information recording track by the tracking servo control. Therefore, even if the track pitch is narrowed unnecessarily, reproduction cannot be performed properly, and the recording / reproduction system cannot be realized.
  • pitch equivalent to the optical cutoff here means the reciprocal of the optical cutoff spatial frequency
  • pitch equivalent to the optical cutoff means that the pitch This represents a state in which the corresponding optical spatial frequency is higher than the cutoff spatial frequency
  • the information recording track has a plurality of tracks with a track pitch shorter than the track pitch corresponding to the optical cutoff defined by the wavelength of the laser beam to be irradiated and the NA of the irradiation optical system.
  • a plurality of tracks in the track group are irradiated with at least two reproduction laser spots, and a difference signal of each radial contrast signal obtained from each reflected light information of the two reproduction laser spots is used as a tracking error signal. Then, by tracking servo control using the tracking error signal, at least one reproduction laser spot is on-track controlled to any information recording track, and data is reproduced from the reflected light information.
  • the information recording track has a plurality of tracks with a track pitch shorter than the track pitch corresponding to the optical cutoff defined by the wavelength of the laser beam to be irradiated and the NA of the irradiation optical system.
  • the track group pitch in the unit of the track group is at least two for reproduction with respect to the recording medium longer than the track pitch corresponding to the optical cut-off.
  • An optical head that irradiates a laser beam through an objective lens so that the laser spot is irradiated, and obtains reflected light information related to each laser spot, and each radial obtained from each reflected light information of two reproduction laser spots
  • the difference signal of the contrast signal is used as a tracking error signal, and the tracking signal using the tracking error signal is used.
  • a servo circuit unit that causes the optical head to perform a tracking operation in which at least one or more reproduction laser spots are on-tracked to any one of the information recording tracks by the control, and a reproduction laser spot that is on-track controlled to the information recording tracks
  • a reproducing circuit unit for reproducing data from the reflected light information.
  • the information recording track further includes a crosstalk cancellation unit that performs crosstalk cancellation processing on the reflected light information of the reproduction laser spot controlled on track, and the reproduction circuit unit performs crosstalk cancellation processing in the crosstalk cancellation unit. Data may be reproduced from the reflected light information.
  • the recording medium is formed with a track group in which a plurality of tracks are adjacent at a track pitch shorter than the track pitch corresponding to the optical cutoff, and the adjacent track groups are
  • the track group pitch is longer than the track pitch corresponding to the optical cutoff. That is, the track pitch is narrowed within the track group, and the density in the track pitch direction is increased as a whole.
  • the track group pitch is a pitch when a track group formed of a plurality of tracks is assumed to be one track. That is, this is the pitch between the center position in the radial direction when viewed from the whole track group and the center position of the adjacent track group.
  • a signal used for tracking servo can be obtained from the periodic structure of the track groups. Specifically, when at least two reproduction laser spots are irradiated to a plurality of tracks in the track group, radial contrast signals are obtained as reflected light information of the two reproduction laser spots. Tracking servo control can be performed using the difference signal of the radial contrast signal as a tracking error signal.
  • an appropriate tracking servo is applied to a recording medium that realizes high-density recording by forming an information recording track with a track pitch shorter than the track pitch corresponding to the optical cutoff. Can be played back. As a result, a high-density recording / reproducing system can be realized.
  • the recording medium of the embodiment is assumed to be an optical disk having a diameter of 12 cm, such as a CD, a DVD, a Blu-ray disc (BD), and the like.
  • FIG. 1 schematically shows an example of a cross-sectional structure of a recording medium (optical disc) 90 according to the embodiment.
  • FIG. 1A shows a structural example in which the optical disc 90 includes a substrate 93, a bulk layer 91, and a cover layer 92.
  • a recording layer (layer L 0) is formed at a predetermined depth position in the bulk layer 91.
  • the “depth” refers to a distance from the surface of the cover layer 92 in the thickness direction.
  • the structure of FIG. 1A is an example of a single layer disc having a single recording layer.
  • the surface side of the cover layer 92 is a laser light incident surface. The laser light is incident from the surface side of the cover layer 92, is focused on the layer L0, forms a spot, and is recorded or reproduced.
  • FIG. 1B shows an example of a multi-layer disc in which a large number of recording layers (layers L0... Ln) are formed in the bulk layer.
  • the laser beam is incident from the surface side of the cover layer 92 and is focused on the target layer to form a spot, and recording or reproduction is performed.
  • FIG. 1C is an example in which a reference surface RL is provided.
  • the reference surface RL is formed, for example, at the joint surface portion between the bulk layer 91 and the cover layer 92.
  • the reference surface RL has a land / groove structure.
  • the groove is formed in a spiral shape and serves as a tracking guide when recording information recording tracks formed in the layers L0... Ln in the bulk layer 91.
  • the reference surface RL may be a pit row instead of a groove.
  • the absolute position information may be recorded by wobbling (meandering) the groove or pit row based on the address information.
  • each example in FIG. 1 is merely an example.
  • the layer structure of the optical disc 90 of the embodiment examples other than these structures are also conceivable.
  • the cover layer 92 may be formed on the substrate 93, and the layer L0 may be formed on the bonding surface between the substrate 93 and the cover layer 92.
  • the bulk layer 91 may have a laminated film structure, and the layers L0... Ln may be formed on each laminated film.
  • the layer L0 in the case of a single layer as a recording layer and the multi-layers L0... Ln are collectively referred to as “layer L”.
  • a read-only disc or a recordable disc (a write-once disc or a rewritable disc) is assumed.
  • an emboss pit row is formed in each layer L.
  • the emboss pit row may be formed by stamping using a stamper formed from the disk master for each layer L.
  • the optical disc 90 As a recordable disc, recording laser light is irradiated while being rotated by a recording device, and a mark row corresponding to the recording information is formed on the layer L.
  • a mark row corresponding to the recording information is formed on the layer L.
  • a phase change mark, a pigment change mark, an interference fringe mark, a void (hole) mark, a refractive index change mark, and the like are assumed.
  • the reproduction laser beam is irradiated to the reproduction target layer L in a state where the optical disk 90 is rotationally driven by the reproduction apparatus. Then, the reflected light information corresponding to the pit row or mark row formed in the layer L is detected, and the data is reproduced.
  • the optical disk 90 of the present embodiment is intended to increase the capacity by performing high-density recording by narrowing the information recording track formed by the mark row (or embossed pit row) in the layer L. It is.
  • FIG. 2 shows an example in which a track is formed with a double spiral structure.
  • the “information recording track” means a track structure formed by a spiral continuous mark row (or embossed pit row). When simply called “track”, it means a track portion of one round.
  • FIG. 2A schematically shows an information recording track formed on the layer L with a mark row (or an embossed pit row, which will be described below as an example of the mark row).
  • FIG. 2B schematically shows a track trajectory when the information recording track formed by the mark row is viewed in the disk plane direction.
  • the information recording track has a double spiral structure in which two independent track tracks TKa and TKb are formed in a spiral shape.
  • FIG. 2A is an enlarged view of eight tracks (TK1 to TK8) adjacent in the radial direction in the information recording track having the double spiral structure.
  • the tracks TK1 to TK8 have (a) or (b) at the end of the reference numerals.
  • the tracks TK1, TK3, TK5, TK7 with (a) are tracks on the track trajectory TKa, Tracks TK2, TK4, TK6, and TK8 marked with (b) are assumed to be tracks on the track trajectory TKb.
  • This information recording track forms a track group with two adjacent tracks, a track on the track orbit TKa and a track on the track orbit TKb.
  • the tracks TK1 and TK2 are a track group
  • the tracks TK3 and TK4 are a track group.
  • the track group refers to a set of adjacent tracks adjacent at a track pitch Tp1.
  • the track pitch Tp1 is a first track pitch that is shorter than the track pitch corresponding to the optical cutoff defined by the wavelength of the laser beam to be irradiated and the NA of the irradiation optical system.
  • the track pitch Tp1 between the tracks TK1 and TK2 is shorter than that corresponding to the optical cutoff.
  • tracks that are adjacent to each other between adjacent track groups are separated by a track pitch Tp2.
  • the track pitch Tp2 is, for example, a second track pitch that is longer than the track pitch corresponding to the optical cutoff.
  • the tracks TK2 and TK3 and the tracks TK4 and TK5 are adjacent to each other between adjacent track groups, and these pitches are the track pitch Tp2.
  • the pitch between the track groups is shown as a track group pitch TpG.
  • a track group in which two tracks are adjacent is formed at a track pitch Tp1 shorter than the track pitch corresponding to the optical cut-off, and the track group pitch between the adjacent track groups is formed.
  • TpG is longer than the track pitch corresponding to the optical cutoff.
  • the information recording track has a double spiral structure in which two independent track tracks TKa and TKb are formed in a spiral shape as shown in FIG. 2B, and corresponds to an optical cutoff by the track tracks TKa and TKb.
  • a track group having a track pitch Tp1 shorter than the track pitch is formed.
  • the track group pitch TpG between the adjacent track groups which are circulated by the double spiral structure is made longer than the track pitch corresponding to the optical cutoff.
  • the track pitches Tp1 and TpG will be described in detail later.
  • a signal capable of tracking control is obtained by adopting a periodic structure in which a track group formed by a plurality of tracks adjacent to each other with such a track pitch Tp1 has a track group pitch TpG longer than that corresponding to the optical cutoff. Can be extracted.
  • the track pitch Tp2 may be shorter than that corresponding to the optical cutoff.
  • the track group pitch TpG is longer than the pitch corresponding to the optical cutoff.
  • the track group pitch TpG Tp1 + Tp2. Therefore, even if the track pitches Tp1 and Tp2 are both shorter than the optical cutoff, it is only necessary that Tp1 + Tp2 is longer than the optical cutoff. If the track pitch Tp2 is made shorter than that corresponding to the optical cut-off, it is advantageous for higher density. On the other hand, if the track pitch Tp2 is longer than that corresponding to the optical cutoff, it is advantageous in terms of extraction of the tracking error signal TE, crosstalk during reproduction, and crosswrite during recording.
  • the information recording track of the disk 90 of the embodiment may have a multiple spiral structure such as a triple spiral structure or a quadruple spiral structure in addition to the double spiral structure of FIG.
  • FIG. 3A and 3B schematically show the structure of the information recording track in the same format as FIGS. 2A and 2B.
  • the information recording track has a triple spiral structure in which three independent track orbits TKa, TKb, and TKc are formed in a spiral shape.
  • FIG. 3A is an enlarged view of nine tracks (TK1 to TK9) adjacent in the radial direction in the information recording track of the triple spiral structure. Note that (a), (b), and (c) at the end of the codes of the tracks TK1 to TK9 indicate the track trajectories TKa, TKb, and TKc in which the tracks are included.
  • This information recording track forms a track group of three adjacent tracks, a track on the track orbit TKa, a track on the track orbit TKb, and a track on the track orbit TKc.
  • tracks TK1, TK2, and TK3 are track groups
  • tracks TK4, TK5, and TK6 are track groups.
  • the tracks in the track group are adjacent at a track pitch Tp1. Further, adjacent track groups are separated by a track group pitch TpG2.
  • a track group in which three tracks are adjacent is formed at a track pitch Tp1 shorter than the track pitch corresponding to the optical cut-off, and the track group pitch between the adjacent track groups is formed.
  • TpG is longer than the track pitch corresponding to the optical cutoff.
  • the information recording track has a triple (triple) spiral structure in which three independent track tracks TKa, TKb, and TKc are formed in a spiral shape as shown in FIG. 3B.
  • the track tracks TKa, TKb, and TKc thus, a track group having a track pitch Tp1 is formed.
  • the track group pitch TpG between adjacent track groups that are circulated in a triple spiral structure is longer than the track pitch corresponding to the optical cutoff.
  • the track group pitch TpG Tp1 + Tp2 + Tp1. Therefore, if the track pitch Tp2 of adjacent tracks (for example, tracks TK3 and TK4) between adjacent track groups is made longer than the track pitch corresponding to the optical cutoff, the track group pitch TpG is inevitably generated. Is longer than the track pitch corresponding to the optical cutoff. Of course, the track pitch Tp2 may be shorter than the track pitch corresponding to the optical cutoff.
  • FIGS. 4A and 4B also schematically show the structure of the information recording track in the same format as FIGS. 2A and 2B.
  • the information recording track has a quadruple spiral structure in which four independent track orbits TKa, TKb, TKc, and TKd are formed in a spiral shape.
  • FIG. 4A is an enlarged view of twelve tracks (TK1 to TK12) adjacent in the radial direction in the information recording track having the quadruple spiral structure. Note that (a), (b), (c), and (d) at the end of the codes of the tracks TK1 to TK12 indicate the track trajectories TKa, TKb, TKc, and TKd in which the tracks are included.
  • This information recording track forms a track group of four adjacent tracks, which are a track on the track orbit TKa, a track on the track orbit TKb, a track on the track orbit TKc, and a track on the track orbit TKd.
  • tracks TK1, TK2, TK3, and TK4 are track groups
  • tracks TK5, TK6, TK7, and TK8 are track groups.
  • the tracks in the track group are adjacent at a track pitch Tp1. Further, adjacent track groups are separated by a track group pitch TpG.
  • a track group in which four tracks are adjacent is formed at a track pitch Tp1 shorter than the track pitch corresponding to the optical cutoff, and the track group pitch between the adjacent track groups is formed.
  • TpG is longer than the track pitch corresponding to the optical cutoff.
  • the information recording track has a quadruple spiral structure in which four independent track tracks TKa, TKb, TKc, and TKd are formed in a spiral shape as shown in FIG. 4B, and the track tracks TKa, TKb, TKc, A track group having a track pitch Tp1 is formed by TKd.
  • the pitch between adjacent track groups that are circulated by the quadruple spiral structure becomes a track group pitch TpG that is longer than the track pitch corresponding to the optical cutoff.
  • the track group pitch TpG Tp1 + Tp1 + Tp1 + Tp2. Therefore, if the track pitch Tp2 of adjacent tracks (for example, tracks TK4 and TK5) between adjacent track groups is made longer than the track pitch corresponding to the optical cutoff, the track group pitch TpG is inevitably generated. Is longer than the track pitch corresponding to the optical cutoff. Of course, the track pitch Tp2 may be shorter than the track pitch corresponding to the optical cutoff.
  • Configuration example of disk drive device The configuration of the disk drive device (recording / reproducing device) of this embodiment will be described with reference to FIG.
  • the disk drive apparatus according to the embodiment reproduces or records in correspondence with a reproduction-only disk or a recordable disk (write-once disk or rewritable disk) as the disk 90 of the embodiment having the information recording track structure as described above. Can be performed.
  • the optical disk 90 is loaded on a turntable (not shown) when loaded in the disk drive device, and is rotationally driven by the spindle motor 2 at a constant linear velocity (CLV) or a constant angular velocity (CAV) during a recording / reproducing operation.
  • CLV linear velocity
  • CAV constant angular velocity
  • the mark information (or embossed pit information) recorded on the information recording track on the optical disk 90 is read out by the optical pickup (optical head) 1.
  • user data is recorded as a mark row on a track on the optical disc 90 by the optical pickup 1.
  • 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, a laser beam is irradiated onto the disk recording surface via the objective lens, and An optical system or the like for guiding the reflected light to the photodetector is formed.
  • the objective lens is held so as to be movable in the tracking direction and the focus direction by a biaxial mechanism.
  • the entire optical pickup 1 can be moved in the radial direction of the disk by a thread mechanism 3.
  • the laser diode in the optical pickup 1 is driven to emit laser light when a drive current is passed by the laser driver 13.
  • Reflected light information from the disk 90 is detected by a photo detector, converted into an electrical signal corresponding to the amount of received light, and supplied to the matrix circuit 4.
  • the matrix circuit 4 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 reproduction information signal (RF signal) corresponding to reproduction data, a focus error signal for servo control, a tracking error signal, and the like are generated.
  • the reproduction information signal output from the matrix circuit 4 is supplied to the data detection processing unit 5 via the crosstalk cancellation circuit 6.
  • the focus error signal and tracking error signal output from the matrix circuit 4 are supplied to the optical block servo circuit 11.
  • the crosstalk cancellation circuit 6 performs a crosstalk cancellation process on the RF signal.
  • the optical disk 90 of the present embodiment has adjacent tracks with a very narrow track pitch Tp1, as illustrated in FIGS.
  • Tp1 very narrow track pitch
  • the narrower the track pitch the more crosstalk components are mixed in adjacent tracks during playback. Therefore, a crosstalk cancel circuit 6 is provided to perform processing for canceling the RF signal component of the adjacent track.
  • the crosstalk cancel circuit 6 may not be provided. Further, the crosstalk cancel circuit 6 may control the operation of the matrix circuit in order to generate a tracking error signal.
  • the data detection processing unit 5 performs binarization processing of the reproduction information signal. For example, the data detection processing unit 5 performs an A / D conversion process on the RF signal, a reproduction clock generation process using a PLL, a PR (Partial Response) equalization process, a Viterbi decoding (maximum likelihood decoding), and the like, and a partial response maximum likelihood decoding process A binary data string is obtained by (PRML detection method: Partial Response Maximum Likelihood detection method). Then, the data detection processing unit 5 supplies a binary data string as information read from the optical disc 90 to the subsequent encoding / decoding unit 7.
  • PRML detection method Partial Response Maximum Likelihood detection method
  • the encode / decode unit 7 performs demodulation of reproduction data during reproduction and modulation processing of recording data during recording. That is, data demodulation, deinterleaving, ECC decoding, address decoding, etc. are performed during reproduction, and ECC encoding, interleaving, data modulation, etc. are performed during recording.
  • the binary data string decoded by the data detection processing unit 5 is supplied to the encoding / decoding unit 7.
  • the encoding / decoding unit 7 performs demodulation processing on the binary data string to obtain reproduction data from the optical disc 90.
  • data recorded on the optical disk 90 is subjected to run length limited code modulation (RLL: Run Length Limited, PP: Parity preserve / Prohibit rmtr (repeated minimum transition run length)) such as RLL (1, 7) PP modulation.
  • RLL Run Length Limited
  • PP Parity preserve / Prohibit rmtr (repeated minimum transition run length)
  • RLL (1, 7) PP modulation PP modulation
  • the demodulating process for such data modulation is performed, and the error correction is performed by the ECC decoding process, so that reproduced data from the optical disk 90 is obtained.
  • the data decoded to the reproduction data by the encoding / decoding unit 7 is transferred to the host interface 8 and transferred to the host device 100 based on an instruction from the system controller 10.
  • the host device 100 is, for example, a computer device or an AV (Audio-Visual) system device.
  • recording data is transferred from the host device 100, and the recording data is supplied to the encoding / decoding unit 7 via the host interface 8.
  • the encoding / decoding unit 7 performs error correction code addition (ECC encoding), interleaving, sub-code addition, and the like as recording data encoding processing.
  • ECC encoding error correction code addition
  • the data subjected to these processes is subjected to run-length limited code modulation such as the RLL (1-7) PP method.
  • the recording data processed by the encode / decode unit 7 is supplied to the write strategy unit 14.
  • the write strategy section as a recording compensation process, laser drive pulse waveform adjustment is performed with respect to the characteristics of the recording layer, the spot shape of the laser beam, the recording linear velocity, and the like. Then, the laser drive pulse is output to the laser driver 13.
  • the laser driver 13 Based on the laser driving pulse subjected to the recording compensation process, the laser driver 13 causes a current to flow through the laser diode in the optical pickup 1 to execute laser light emission driving. As a result, a mark corresponding to the recording data is formed on the optical disc 90.
  • the laser driver 13 includes a so-called APC circuit (AutoPower Control), and the laser output is not dependent on temperature or the like while monitoring the laser output power by the output of the detector for monitoring the laser power provided in the optical pickup 1. Control to be constant.
  • the target value of the laser output at the time of recording and reproduction is given from the system controller 10, and control is performed so that the laser output level becomes the target value at the time of recording and reproduction.
  • the optical block servo circuit 11 generates various servo drive signals for focus, tracking, and thread from the focus error signal and tracking error signal from the matrix circuit 4 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 biaxial driver 18 drives the focus coil and tracking coil of the biaxial mechanism in the optical pickup 1. As a result, the pickup 1, the matrix circuit 4, the optical block servo circuit 11, the biaxial driver 18, the tracking servo loop and the focus servo loop by the biaxial mechanism are formed. The optical block servo circuit 11 turns off the tracking servo loop in response to a track jump command from the system controller 10 and outputs a jump drive signal to execute a track jump operation.
  • the optical block servo circuit 11 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 10, and the like.
  • the sled mechanism 3 has a mechanism including a main shaft that holds the pickup 1, a sled motor, a transmission gear, and the like.
  • the sled mechanism 3 drives the sled motor according to a sled drive signal. Slide movement is performed.
  • the spindle servo circuit 12 performs control to rotate the spindle motor 2 at CLV.
  • the spindle servo circuit 12 obtains the current rotation speed information of the spindle motor 2 as a clock generated by the PLL process for the RF signal, and obtains this as a predetermined CLV (or CA).
  • V) A spindle error signal is generated by comparing with the reference speed information.
  • the spindle servo circuit 12 outputs a spindle drive signal generated according to the spindle error signal, and causes the spindle driver 17 to execute CLV rotation or CAV rotation of the spindle motor 2.
  • the spindle servo circuit 12 generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 10, and also executes operations such as starting, stopping, acceleration, and deceleration of the spindle motor 2.
  • the spindle motor 2 is provided with, for example, FG (Freqency Generator) and PG (Pulse Generator), and the output is supplied to the system controller 10. Thereby, the system controller 10 can recognize the rotation information (rotation speed, rotation angle position) of the spindle motor 2.
  • a system controller 10 formed by a microcomputer.
  • the system controller 10 executes various processes in accordance with commands from the host device 100 given via the host interface 8. For example, when a write command (write command) is issued from the host device 100, the system controller 10 first moves the pickup 1 to a logical or physical spatial address to be written. Then, the encoding / decoding unit 7 causes the encoding process to be performed on the data (for example, video data, audio data, etc.) transferred from the host device 100 as described above. Recording is executed by the laser driver 13 driving to emit laser light according to the data encoded as described above.
  • the system controller 10 when a read command for requesting transfer of certain data recorded on the optical disc 90 is supplied from the host device 100, the system controller 10 first performs seek operation control for the instructed address. That is, a command is issued to the optical block servo circuit 11, and the access operation of the optical pickup 1 targeting the address specified by the seek command is executed. Thereafter, operation control necessary for transferring the data in the designated data section to the host device 100 is performed. That is, the data is read from the disk 90, the reproduction processing in the data detection processing unit 5 and the encoding / decoding unit 7 is executed, and the requested data is transferred.
  • FIG. 1 has been described as a disk drive device connected to the host device 100, but the disk drive device may not be connected to other devices.
  • 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.
  • various other configuration examples of the disk drive device are possible.
  • FIG. 6 shows a recording operation example and a reproduction operation example when the information recording track has a double spiral structure as shown in FIG. In each figure, the information recording track is indicated by a solid line or a broken line.
  • FIG. 6A shows an example in which the layer L of the optical disk 90 is irradiated with two reproduction laser spots SPp1 and SPp2 by a reproduction power laser and two recording laser spots SPr1 and SPr2 by a recording power laser.
  • this is an example in which double spiral track tracks are formed simultaneously.
  • the reproduction laser spots SPp1 and SPp2 are servo laser beams for detecting a tracking error signal. Then, the tracking control is performed so that the reproduction laser spots SPp1 and SPp2 trace the double spiral tracks TKx and TKx + 1. For example, tracking control is performed at the center of the tracks TKx and TKx + 1.
  • the track pitch Tp1 between the tracks TKx and TKx + 1 is a track pitch shorter than that corresponding to the optical cut-off. A tracking error signal can be obtained. This will be described later.
  • the optical pickup 1 irradiates the recording laser spots SPr1 and SPr2 so as to be separated from each other by the track pitch Tp1 in the disc radial direction. Further, the reproduction laser spot SPp2 and the recording laser spot SPr1 are irradiated in a state of being separated by a track pitch Tp2 in the disk radial direction. In this way, while performing tracking control on the inner track group (tracks TKx, TKx + 1), the outer track TKx + 2 is recorded along the tracks TKx, TKx + 1 by the recording laser spots SPr1, SPr2. , TKx + 3 can be recorded at the track group pitch TpG. In addition, recording with a high transfer rate can be realized by simultaneously forming a double spiral track orbit.
  • adjacent tracking servo In such a recording operation, recording is performed with the recording laser spot on the outer circumferential side while tracking control is performed on the inner circumferential side track with the reproducing laser spot.
  • adjacent tracking servo When this adjacent tracking servo is performed, it is first necessary that a first round track exists.
  • a reference surface RL is provided and a groove or the like of the reference surface RL can be used as shown in FIG. . From the second round onward, recording can be executed with the adjacent tracking servo as shown in FIG. 6A.
  • FIGS. 9A to 9D operation examples as shown in FIGS. 9A to 9D can be considered.
  • guide tracks TKG1 and TKG2 that are a perfect circle of one round are recorded on the layer L of the optical disc 90. This can be formed by rotating the optical disc 90 once with the optical pickup 1 fixing the laser spot position.
  • the guide track TKG1 is first formed, and then the adjacent tracking servo is applied to the guide track TKG1 to form the guide track TKG2.
  • the interval (track pitch) between the concentric guide tracks TKG1 and TKG2 is set equal to the track group pitch TpG.
  • a jump pulse is learned so that the track jump from the guide track TKG1 to TKG2G is exactly one rotation. That is, the jump pulse forms a trajectory indicated by a broken line in FIG. 9B.
  • the first spiral spiral track is recorded as shown in FIG. 9C.
  • the recording laser spots SPr1 and SPr2 gradually shift to the outer periphery side for each angular position in the first round of the double spiral tracks TKa and TKb. That is, a double spiral track for one round can be formed. From the second round onward, the double spiral track can be recorded by the adjacent tracking servo described with reference to FIG. 6A as indicated by the broken line in FIG. 9D.
  • FIG. 6B shows a case where two reproducing laser spots SPp1 and SPp2 by a reproducing power laser and one recording laser spot SPr by a recording power laser are irradiated onto the layer L of the optical disk 90 to thereby each track of the double spiral.
  • the tracks are formed separately.
  • the track of the track orbit TKa is already recorded in a spiral shape.
  • the track on the track trajectory TKa is recorded so that the track pitch is Tp1 + Tp2.
  • a track of the track orbit TKb indicated by a broken line is recorded.
  • the reproduction laser spots SPp1 and SPp2 are subjected to tracking control with respect to the track of the solid track orbit TKa. For example, tracking control is performed so that the middle of the reproduction laser spots SPp1 and SPp2 is positioned on the track of the track trajectory TKa.
  • the recording laser spot SPr is irradiated from the track on the track trajectory TKa so as to be separated by a track pitch Tp1 in the disc radial direction.
  • tracks of the track trajectory TKb forming a double spiral adjacent to the track trajectory TKa are recorded.
  • this recording operation also performs adjacent tracking servo.
  • a track of track orbit TKa whose track pitch is Tp1 + Tp2 is first recorded. It will be.
  • a reference surface RL is provided as shown in FIG. 1C and a groove or the like of the reference surface RL can be used, the groove or the like of the reference surface RL is used as a guide, and the track orbit TKa of the track pitch Tp1 + Tp2 as shown in FIG. A spiral track may be formed.
  • the recording of the spiral track of the track trajectory TKb can be executed as shown by the broken line in FIG. 9F by performing the adjacent tracking servo as shown in FIG. 6B.
  • a spiral track as the track trajectory TKa can be formed as shown in FIG. 9E.
  • the recording of the spiral track of the track trajectory TKb can be executed as shown by the broken line in FIG. 9F by performing the adjacent tracking servo as shown in FIG. 6B.
  • the reproducing operation will be described with reference to FIG. 6C.
  • This is an example of the reproducing operation when the information recording track having the double spiral structure as shown in FIG. 2 is formed by the recording operation (or the reproduction-only disc) as shown in FIG. 6A or 6B.
  • the layer L of the optical disk 90 is irradiated with two reproduction laser spots SPp1 and SPp2 by a laser having a reproduction power.
  • the reproduction laser spots SPp1 and SPp2 are irradiated so as to be separated from each other by a track pitch Tp1 in the disc radial direction.
  • the reproduction laser spots SPp1 and SPp2 are on-tracked to the tracks TKx and TKx + 1 having the track pitch Tp1, respectively.
  • the track pitch Tp1 is shorter than that corresponding to the optical cutoff, but a tracking error signal can be obtained as a difference signal between the radial contrast signals obtained from the reflected light information of the two reproduction laser spots SPp1 and SPp2. .
  • the tracking laser control using the tracking error signal causes the reproduction laser spots SPp1 and SPp2 to be on-track on the tracks TKx and TKx + 1, respectively. Then, the data of the tracks TKx and TKx + 1 can be reproduced from the reflected light information of the reproduction laser spots SPp1 and SPp2. Also, by reproducing the double spiral track orbit at the same time, reproduction with a high transfer rate can be realized.
  • FIG. 7A shows an example in which the layer L of the optical disk 90 is irradiated with a servo laser spot SPp45 by a laser having a reproducing power and two recording laser spots SPr1 and SPr2 by a laser having a recording power.
  • double spiral track tracks are formed simultaneously.
  • Tracking control is performed so that the servo laser spot SPp45 is traced to the track group of the double spiral tracks TKx and TKx + 1.
  • tracking control is performed at the center of the tracks TKx and TKx + 1.
  • the track pitch Tp1 between the tracks TKx and TKx + 1 is a track pitch shorter than that corresponding to the optical cut-off.
  • the optical pickup 1 irradiates the recording laser spots SPr1 and SPr2 so as to be separated from each other by the track pitch Tp1 in the disc radial direction. Also, the servo laser spot SPp45 and the recording laser spot SPr1 are irradiated in a state separated by a track pitch Tp2 + (Tp1 / 2) in the disk radial direction.
  • the servo laser spot SPp45 by the reproduction power laser and one recording laser spot SPr by the recording power laser are irradiated to the layer L of the optical disk 90, and each track trajectory of the double spiral is separated. It is an example of forming.
  • the track of the track orbit TKa is already recorded in a spiral shape.
  • TpG the track pitch
  • a track of the track orbit TKb indicated by a broken line is recorded.
  • the servo laser spot SPp45 is subjected to tracking control so as to be on-track with respect to the track of the solid track orbit TKa.
  • the recording laser spot SPr is irradiated from the track on the track trajectory TKa so as to be separated by a track pitch Tp1 in the disc radial direction. By doing so, tracks of the track trajectory TKb forming a double spiral adjacent to the track trajectory TKa are recorded.
  • FIG. 7C This is an example of the reproducing operation when the information recording track having the double spiral structure as shown in FIG. 2 is formed by the recording operation (or the reproduction-only disc) as shown in FIG. 7A or 7B.
  • the layer L of the optical disk 90 is irradiated with a servo laser spot SPp45 by a laser having a reproduction power and two reproduction laser spots SPp1 and SPp2.
  • the tracking control is performed so that the servo laser spot SPp45 traces the track group TKx, TKx + 1.
  • tracking control is performed at the center of the tracks TKx and TKx + 1.
  • the reproduction laser spots SPp1 and SPp2 are separated from each other by a track pitch Tp1 in the radial direction, and the reproduction laser spot SPp1 is separated from the servo laser spot SPp45 by Tp2 + (Tp1 / 2) in the radial direction. Irradiate.
  • the reproduction laser spots SPp1, SPp2 are on-tracked to the tracks TKx + 2, TKx + 3 by the adjacent tracking servo using the tangential push-pull signal as reflected light information of the servo laser spot SPp45.
  • the data of the tracks TKx + 2 and TKx + 3 can be reproduced from the reflected light information of the reproduction laser spots SPp1 and SPp2.
  • FIG. 8A shows an example in which the layer L of the optical disk 90 is irradiated with three reproduction laser spots SPp1, SPp2, and SPp0 by a reproduction power laser and three recording laser spots SPr1, SPr2, and SPr3 by a recording power laser. .
  • this is an example of simultaneously forming a triple spiral track orbit.
  • the reproduction laser spots SPp1, SPp0, SPp2 are servo laser beams for detecting a tracking error signal. Then, tracking control is performed so that the reproduction laser spots SPp1, SPp0, and SPp2 trace the triple spiral tracks TKx, TKx + 1, and TKx + 2. Note that the track pitch Tp1 between each of the tracks TKx, TKx + 1, and TKx + 2 is a track pitch shorter than the optical cutoff, but is obtained from the reflected light information of two of the three reproduction laser spots SPp1 and SPp2.
  • a tracking error signal can be obtained as a differential signal of each radial contrast signal. This will be described later.
  • the optical pickup 1 irradiates the recording laser spots SPr1, SPr2, and SPr3 so as to be separated from each other by the track pitch Tp1 in the disk radial direction. Further, the reproduction laser spot SPp2 and the recording laser spot SPr1 are irradiated in a state of being separated by a track pitch Tp2 in the disk radial direction.
  • the recording laser spots SPr1, SPr2, SPr3 Tracks TKx + 3, TKx + 4, and TKx + 5 can be recorded. That is, it is possible to form a track group having a track group pitch TpG longer than that corresponding to the optical cutoff while forming a track having a track pitch Tp1 shorter than that corresponding to the optical cutoff. Further, by simultaneously forming a triple spiral track orbit, recording with a high transfer rate can be realized.
  • the recording using the reference surface RL, the recording operation described with reference to FIGS. 9A to 9D, and the like are performed. Just do it.
  • FIG. 8B is an example in which the track tracks TKa, TKb, and TKc of the triple spiral are formed separately.
  • the recording of the track trajectories TKa and TKb may be performed by the method described in FIG. 6B.
  • FIG. 8B shows the case where the track (broken line) of the track trajectory TKc is recorded as the third spiral track after the tracks of the track trajectories TKa and TKb are formed as shown by the solid line.
  • the optical pickup 1 irradiates the layer L of the optical disc 90 with two reproducing laser spots SPp1 and SPp2 by a reproducing power laser and one recording laser spot SPr by a recording power laser.
  • the reproduction laser spots SPp1 and SPp2 are subjected to tracking control with respect to the two tracks of the solid track orbits TKa and TKb.
  • at least the reproduction laser spot SPp2 only needs to be on-tracked with respect to the track of the track orbit TKb.
  • tracking control is performed so that the middle of the reproduction laser spots SPp1 and SPp2 is located in the middle of the track trajectories TKa and TKb. That's fine.
  • the recording laser spot SPr is irradiated so as to be separated from the reproduction laser spot SPp2 by the track pitch Tp1 in the disc radial direction.
  • the reproducing operation will be described with reference to FIG. 8C.
  • This is an example of the reproducing operation when the information recording track having the triple spiral structure as shown in FIG. 3 is formed by the recording operation (or the reproduction-only disc) as shown in FIG. 8A or 8B.
  • the layer L of the optical disk 90 is irradiated with three reproduction laser spots SPp1, SPp0, SPp2 by a laser having a reproduction power.
  • the reproduction laser spots SPp1, SPp0, and SPp2 are irradiated so as to be separated from each other by a track pitch Tp1 in the disk radial direction.
  • the reproduction laser spots SPp1, SPp0, SPp2 are set to on-track to the tracks TKx, TKx + 1, TKx + 2 having the track pitch Tp1, respectively.
  • the track pitch Tp1 is shorter than the optical cut-off equivalent, but a tracking error signal is used as a difference signal of each radial contrast signal obtained from the reflected light information of two of the three reproduction laser spots SPp1 and SPp2. Obtainable.
  • the tracking servo control using this tracking error signal the reproduction laser spots SPp1, SPp0, SPp2 are on-tracked to the tracks TKx, TKx + 1, TKx + 2, respectively. Then, the data of the tracks TKx, TKx + 1, and TKx + 2 can be reproduced from the reflected light information of the reproduction laser spots SPp1, SPp0, and SPp2.
  • a high transfer rate can be realized.
  • the recording operations exemplified in FIGS. 6A, 6B, 7A, 7B, 8A, and 8B described above form a track group in which a plurality of tracks are adjacent at the track pitch Tp1, and the adjacent track groups are separated from each other.
  • information recording tracks are formed on a recording medium by performing tracking control of recording laser light so as to be separated by a track group pitch TpG.
  • the recording laser beam forms an information recording track having a multi-spiral structure in which a plurality of independent track tracks are formed in a spiral shape, and a track group having a track pitch Tp1 is formed by the plurality of track tracks.
  • the tracking control of the recording laser spot is performed so that the adjacent track groups that are circulated by the multi-spiral structure have the track group pitch TpG.
  • TpG track group pitch
  • each of the plurality of tracks in the track group is irradiated with at least two reproduction laser spots, and each of the information obtained from the reflected light information of the two reproduction laser spots.
  • the difference signal of the radial contrast signal is used as a tracking error signal.
  • This is a reproduction method in which at least one reproduction laser spot is on-track controlled to any information recording track by tracking servo control using the tracking error signal, and data is reproduced from the reflected light information.
  • data reproduction can be realized from the optical disk 90 having a track pitch Tp1 (or Tp1 and Tp2 in some cases) equal to or less than the optical cutoff.
  • the reproduction operation illustrated in FIGS. 7C and 7D includes a servo laser spot SPp45 having astigmatism that forms an angle of approximately 45 ° with respect to the tangential direction of the information recording track, and one or more reproduction laser spots. Irradiate. Then, a tangential push-pull signal obtained from reflected light information of the servo laser spot SPp45 is used as a tracking error signal, and at least one or more reproduction laser spots are recorded by tracking servo control using the tracking error signal.
  • This is a reproduction method in which data is reproduced from reflected light information by performing on-track control on a track. This also realizes data reproduction from the optical disc 90 having a track pitch Tp1 (or Tp1 and Tp2 in some cases) equal to or less than the optical cutoff.
  • High density with narrow track pitch> As can be understood from the above description, in the present embodiment, high-density recording is realized as the optical disc 90 having a track pitch Tp1 or the like equivalent to or less than the optical cutoff. Further, data reproduction can be realized from such an optical disk 90, and it can be appropriately established as a recording / reproduction system.
  • FIG. 10 shows signal waveforms found in a conventional Blu-ray disc system.
  • recording and reproduction are performed under the condition of a combination of a laser having a wavelength of 405 nm (so-called blue laser) and an objective lens having an NA of 0.85, and the track pitch is 0.32 ⁇ m.
  • a spiral groove is formed on the recording surface, and the groove serves as a recording track.
  • FIG. 10A shows the difference between the RF signal observed in the so-called traverse state (the laser spot crossing the track in the radial direction) and the push-pull signal P / P (the difference between the photodetectors divided in two along the track line direction). Push-pull signal).
  • the RF signal, the SUM signal, and the push-pull signal P / P signal modulation corresponding to the groove / land that traverses during traverse is observed. It is understood that the position information (tracking error signal) in the radial direction of the laser spot can be detected by the push-pull signal P / P.
  • FIG. 11 shows the SUM signal and the push-pull signal P / P observed when the track pitch Tp is changed from 0.32 ⁇ m to 0.27 ⁇ m and 0.23 ⁇ m.
  • “G” is the groove center position
  • “L” is the land center position.
  • the modulation components of both the SUM signal and the push-pull signal P / P decrease.
  • the track pitch is 0.23 ⁇ m
  • no modulation component is observed.
  • the track pitch of 0.23 ⁇ m is shorter than the optical cutoff in the case of a laser having a wavelength of 405 nm and an optical system having an NA of 0.85.
  • FIG. 12 shows 0th-order light and diffracted light (+ 1st-order light and ⁇ 1st-order light) of laser light.
  • the shift amount of the diffracted light is shown as an arrow SF in the figure.
  • the periodic structure is a period of a structure such as a land / groove.
  • the overlapping portion of the 0th-order light and the ⁇ 1st-order light is a modulation component.
  • the larger the area of the overlapping portion shown as the hatched portion the greater the difference between light and dark on the detection by the photodetector, and the greater the signal modulation.
  • the track pitch is limited to 0.25 ⁇ m, and in reality, almost no modulation component can be obtained at 0.25 ⁇ m. It becomes pitch.
  • the optical disc 90 of the present embodiment does not form a groove / land structure in the layer L.
  • the reason why the groove / land structure is not formed in each layer L is that it is advantageous for multilayering.
  • the track itself as the mark row or the embossed pit row has a periodic structure that affects the signal modulation in the radial direction. Then, if the information recording track is formed only with the track pitch Tp1 equal to or less than the above-described optical cutoff, the modulation component cannot be obtained and the tracking servo cannot be applied.
  • the cycle p> ⁇ / (2NA) the track group should be configured so that That is, as a periodic structure of track groups, the track groups may be formed with a track group pitch TpG that is larger than the optical cutoff. That is, by forming an information recording track having the structure illustrated in FIGS. 2, 3, and 4, a modulation component can be obtained as reflected light information even if the track pitch Tp1 is less than or equal to the optical cutoff. Can do.
  • a modulation component is observed as a SUM signal. That is, a modulation component corresponding to the detrack amount is obtained.
  • the track group pitch TpG 0.50 ⁇ m.
  • the notation of detrack in the case of having a track group structure is 360 ° means a track group period. If the layer L has a mirror surface structure without a groove / land structure, the push-pull signal P / P cannot be obtained unless the recorded mark has a phase difference.
  • FIG. 14 shows the further narrowing of the track pitch.
  • the track group pitch TpG 0.46 ⁇ m, which means that sufficient modulation is obtained even when the average value of the track pitch is 0.23 ⁇ m, that is, the track pitch is equal to the track pitch at which no modulation component is observed in FIG. Is meant to be.
  • the modulation component of the signal corresponding to the radial direction can be obtained by having the track group with the pitch TpG.
  • FIG. 15 shows a tracking error signal calculation method applicable to the recording operation of FIG. 6A or FIG. 8B and the reproduction operation of FIG. 6C.
  • FIG. 15A shows an information recording track having a double spiral structure.
  • the reproduction laser spots SPp1 and SPp2 are servo laser beams for detecting a tracking error signal.
  • tracking control is performed so that the reproduction laser spots SPp1 and SPp2 trace with respect to the double spiral tracks TKx and TKx + 1.
  • the center of the tracks TKx and TKx + 1 is set to a position with a detrack amount of 270 °. (360 ° is the period of the track group: the same applies to FIGS. 16 to 22 below)
  • the reflected light amount signals of the reproduction laser spots SPp1 and SPp2 are denoted by S1 and S2.
  • the tracking error signal TE can be generated by calculating the reflected light amount signal S2-S1 by the differential operation circuit 31, as shown in FIG. 15B.
  • modulation components as radial contrast signals are obtained as shown in FIG. 15C.
  • the reproduction laser spots SPp1 and SPp2 are shifted to the right in FIG. 15A, the reflected light amount signal S1 becomes dark (the signal level decreases) and the reflected light amount signal S2 becomes bright (the signal level increases).
  • the SUM signal in this case is a signal when a virtual spot is considered at an intermediate position in the disk radial direction of the reproduction laser spots SPp1 and SPp2.
  • a tracking error signal TE corresponding to the detrack amount in units of track groups is obtained as S2-S1 which is the difference between the radial contrast components.
  • the reflected light amount signals S1 and S2 are input to the crosstalk cancel circuit 6, and the operation of the differential arithmetic circuit 31 is adjusted by the balance control signal TK-BL from the crosstalk cancel circuit 6.
  • the crosstalk cancel circuit 6 detects the crosstalk component of the adjacent track, it is possible to correct the deviation of the light quantity balance between the tracks TKx and TKx + 1. Therefore, the crosstalk cancellation circuit 6 outputs a balance control signal TK-BL so that the crosstalk components of adjacent tracks are balanced with each other.
  • the differential calculation circuit 31 performs a balance adjustment calculation by applying a correction coefficient corresponding to the recording state of each track to each of the reflected light amount signals S1 and S2 in accordance with the balance control signal TK-BL.
  • the tracking error signal TE that is not easily affected by the recording state is generated by performing the calculation of S2-S1 and appropriately adding an offset bias to the calculation result.
  • the reflected light amount signals S1 and S2 subjected to the crosstalk cancellation processing by the crosstalk cancellation circuit 6 are supplied to the data detection processing unit 5 shown in FIG. That is, when the reproduction of FIG. 6C is performed, the reflected light amount signals S1 and S2 are used for data reproduction as RF signals for the tracks TKx and TKx + 1.
  • FIG. 16 shows a tracking error signal calculation method applicable to the recording operation of FIG. 6B.
  • the reproduction laser spots SPp1 and SPp2 are servo laser beams for detecting a tracking error signal, and the reproduction laser spots SPp1 and SPp2 sandwich one track TKx of the double spiral. Tracking control is performed so that tracing is performed. In this state, the adjacent tracking servo is performed, and the adjacent track TKx + 1 is recorded by the recording laser spot SPr.
  • the tracking error signal TE can be obtained by calculating S2-S1 of the reflected light amount signal in the differential calculation circuit 31, as shown in FIG. 16B. Also in this case, the reflected light amount signals S1 and S2 may be adjusted by the balance control signal TK-BL from the crosstalk cancel circuit 6.
  • the track pitch is wide at the time of recording, most of the RF outputs from the reproduction laser spots SPp1 and SPp2 are from the track TKx, and the comparison result of the RF output and output signal from the reproduction laser spots SPp1 and SPp2 Can be used to obtain the signal reproduction of the track TKx and the balance control signal TK-BL.
  • FIG. 17 shows a tracking error signal calculation method applicable to the recording operation of FIG. 7A and the reproduction operation of FIG. 7C or 7D.
  • a servo laser spot SPp45 with astigmatism that forms an angle of about 45 ° with respect to the tangential direction of the information recording track is irradiated onto the layer L of the optical disk 90.
  • tracking control is performed so that the servo laser spot SPp45 traces the track group of tracks TKx and TKx + 1.
  • the reflected light of the servo laser spot SPp45 is received by the quadrant photodetector 33 shown in FIG. 17B.
  • Each signal obtained from the light receiving surfaces A, B, C, and D is supplied to the arithmetic circuit 34.
  • the arithmetic circuit 34 subtracts the signal of the light receiving surface B + C from the signal of the light receiving surface A + D and outputs this as a tracking error signal TE. That is, the tangential push-pull signal, which is the difference signal of each photodetector divided in the direction perpendicular to the track line direction, becomes the tracking error signal TE.
  • FIG. 17C shows a signal waveform.
  • Tp1 0.20 ⁇ m
  • Tp2 0.30 ⁇ m
  • TpG 0.50 ⁇ m
  • Z6 Z6 in Fringe-Zernike aberration polynomial
  • a signal corresponding to the detrack amount is obtained as the tracking error signal TE by the tangential push-pull signal.
  • FIG. 18 shows a tracking error signal calculation method applicable to the recording operation of FIG. 7B.
  • the servo laser spot SPp45 is irradiated onto the layer L of the optical disc 90 to trace the track TKx already formed in the double spiral.
  • the adjacent tracking servo is performed, and the adjacent track TKx + 1 is recorded by the recording laser spot SPr.
  • FIG. 18B the tangential push-pull signal obtained by calculating (A + D) ⁇ (B + C) by the arithmetic circuit 34 becomes the tracking error signal TE.
  • FIG. 19 shows a tracking error signal calculation method applicable to the recording operation of FIG. 8A and the reproducing operation of FIG. 8C.
  • FIG. 19A shows an information recording track having a triple spiral structure.
  • the reproduction laser spots SPp1, SPp0, SPp2 are servo laser beams for detecting a tracking error signal.
  • tracking control is performed so that the reproduction laser spots SPp1, SPp0, and SPp2 trace the triple spiral tracks TKx, TKx + 1, and TKx + 2.
  • the reflected light amount signals of the reproduction laser spots SPp1, SPp0, SPp2 are denoted by S1, S0, S2.
  • the tracking error signal TE can be generated by calculating the reflected light amount signal S2-S1 by the differential operation circuit 31.
  • modulation components as radial contrast signals are obtained as shown in FIG. 19C.
  • a tracking error signal TE corresponding to the detrack amount is obtained as S2-S1 which is the difference between the radial contrast components.
  • the reflected light quantity signals S1, S0, S2 are input to the crosstalk cancel circuit 6, and the operation of the differential arithmetic circuit 31 is adjusted by the balance control signal TK-BL from the crosstalk cancel circuit 6.
  • the differential operation circuit 31 applies a correction coefficient corresponding to the recording state of each track to each of the reflected light amount signals S1 and S2 in accordance with the balance control signal TK-BL.
  • the tracking error signal TE that is not easily affected by the recording state can be generated by performing the calculation of S2-S1 after performing the balance adjustment calculation to be applied, and adding an appropriate offset bias to the calculation result.
  • the reflected light quantity signals S1, S0, S2 subjected to the crosstalk cancellation processing by the crosstalk cancellation circuit 6 are supplied to the data detection processing unit 5 shown in FIG. That is, when the reproduction of FIG. 8C is performed, the reflected light amount signals S1, S0, and S2 are used for data reproduction as RF signals for the tracks TKx, TKx + 1, and TKx + 2.
  • FIG. 20 shows a servo laser to which astigmatism is given when the third track orbit TKc is recorded in a state where tracks of track orbits TKa and TKb are already formed as shown in FIG. 8B, for example.
  • tracking is performed using a spot SPp45.
  • the tracking servo method may be executed using the two reproduction laser spots SPp1 and SPp2 as described above with reference to FIG. 15, but here, one servo laser spot SPp45 is used. An example is shown.
  • tracking control is performed so that the servo laser spot SPp45 traces the tracks TKx and TKx + 1 of the already formed track trajectories TKa and TKb.
  • the tracking error signal TE As shown in FIG. 20B, by obtaining the tangential push-pull signal by the arithmetic circuit 34 as shown in FIG. 20B, it can be used as the tracking error signal TE.
  • a signal corresponding to the detrack amount is obtained as the tracking error signal TE.
  • tracking control for tracing the servo laser spot SPp45 on the tracks TKx and TKx + 1 as shown in FIG. 20A becomes possible.
  • the track of the third track orbit TKc can be recorded by the recording laser spot SPr by the adjacent tracking servo in this state.
  • FIG. 21 is a servo system similar to the tracking servo system described in FIG. 19, but the track orbits TKa and TKc of the triple spiral information recording track are already formed, and the middle track orbit TKb is not yet formed.
  • the tracking servo system in the recording state is shown.
  • the track pitch Tp2 0.26 between the track groups is set.
  • the generation method g of the tracking error signal TE in FIG. 21B is the same as that in FIG. 19B.
  • FIG. 21C shows the waveform of each signal.
  • the polarity of the tracking error signal TE is reversed from the case of FIG. 19 because there is no middle spiral, but tracking servo as shown in FIG. It becomes.
  • the servo control can be performed to perform recording or reproduction.
  • the track pitch Tp1 may be a track pitch equivalent to or less than the optical cutoff.
  • the track pitch Tp2 is longer than the optical cutoff, and in this case, the track group pitch TpG is necessarily longer than the optical cutoff.
  • FIG. 22 shows that the tracking error signal TE can be obtained if the track group pitch TpG is longer than the optical cutoff even if the track pitches Tp1 and Tp2 are less than or equal to the optical cutoff. Yes.
  • FIG. 22A, 22B, and 22C show the case where the tracking error signal TE is obtained from the radial contrast signals of the reproduction laser spots SPp1 and SPp2 with respect to the information recording track having the double spiral structure, as in FIG. Yes.
  • the track group pitch TpG is 0.38 ⁇ m.
  • S1 and S2 modulation components as radial contrast signals are obtained as shown in FIG. 22C.
  • a tracking error signal TE corresponding to the detrack amount is obtained as S2-S1 which is the difference between the radial contrast components.
  • Example of optical system configuration> A configuration example of the optical system of the optical pickup 1 for realizing the recording operation and the reproducing operation of the above embodiment will be described.
  • FIG. 23 shows an example in which a plurality of laser spots are used for tracking servo as shown in FIGS.
  • a multi-beam LD (Lasordiode) 41 As an optical system in the optical pickup 1, a multi-beam LD (Lasordiode) 41, a collimator lens 42, a beam splitter 43, an objective lens 44, a multi-lens 45, a light receiving element unit 46, and a biaxial mechanism 47 are provided.
  • a multi-beam LD Laserdiode
  • the laser light emitted from the multi-beam LD 41 is converted into parallel light by the collimator lens 42, passes through the beam splitter 43, is condensed by the objective lens 44, and is irradiated onto the optical disk 90.
  • the objective lens 44 is held by a biaxial mechanism 47 so as to be displaceable in the focus direction and the tracking direction. When the biaxial mechanism 47 is driven by the biaxial driver 18 shown in FIG. 5, tracking servo and focus servo are executed.
  • Reflected light from the optical disk 90 is reflected by the beam splitter 43 through the objective lens 44 and reaches the multi lens 45. Then, the light is condensed by the multi lens 45 and is incident on the light receiving element portion 46.
  • the configuration of the light emitting surface as Example 1 to Example 4 in the figure can be considered, and as a photo detector configuration of the light receiving element unit 46 corresponding to the example of the multi-beam LD 41, an example Examples 1 to 4 are possible.
  • the multi-beam LD 41 is configured to have a read-only two-beam light emitting surface
  • the light receiving element unit 46 is configured to include two quadrant photodetectors PD1 and PD2.
  • This is a configuration example in the case where the reproduction apparatus can perform the reproduction operation described with reference to FIGS. 6C and 15, for example.
  • the two reproduction laser spots SPp1 and SPp2 are irradiated, and the reflected light is detected by the photodetectors PD1 and PD2.
  • the sum signal of the four-divided light receiving surfaces of the photodetectors PD1 and PD2 becomes reflected light amount signals S1 and S2 in FIG. Further, other necessary signals such as a focus error signal are generated by calculating each signal on the four-divided light receiving surface.
  • the multi-beam LD 41 is configured to have a reproduction-only three-beam light emitting surface, and the light receiving element unit 46 includes two photodetectors PD3 and PD5 and a four-divided photodetector PD4.
  • the reproduction apparatus can perform the reproduction operation described with reference to FIGS. 8C and 19, for example.
  • the three reproduction laser spots SPp1, SPp0, and SPp2 are irradiated, and these reflected lights are detected by the photodetectors PD3, PD4, and PD5.
  • the reflected light amount signals S1 and S2 shown in FIG. 19 are obtained from the photodetectors PD3 and PD5.
  • the sum signal of the four-divided light receiving surface of the photodetector PD4 becomes the reflected light amount signal S0. Further, other necessary signals such as a focus error signal are generated by calculating each signal of the four-divided light receiving surface of the photodetector PD4.
  • Example 3 is a configuration in the case where the recording operation of FIG. 6A is performed, in which the multi-beam LD 41 has a two-beam reproduction surface and a two-beam emission surface for recording.
  • the multi-beam LD 41 has a two-beam reproduction surface and a two-beam emission surface for recording.
  • two photodetectors PD6 and PD7 are provided for the reproduction laser spots SPp1 and SPp2
  • two photodetectors PD8 and PD9 are provided for the recording laser spots SPr1 and SPr2.
  • Example 4 is a configuration in the case where the recording operation of FIG. 8A is performed, in which the multi-beam LD 41 has a light emitting surface of three beams for reproduction and a light emitting surface of three beams for recording.
  • the light receiving element section 46 is provided with three photodetectors PD10, PD11, PD12 for the reproduction laser spots SPp1, SPp2, SPp3, and three photodetectors PD13, PD14 for the recording laser spots SPr1, SPr2, SPr3.
  • PD15 is provided.
  • FIG. 24 shows, as an example, a configuration having the above-described Example 2, that is, a read-only three-beam light emitting surface and a light receiving element portion 46 (photodetectors PD3, PD4, and PD5) corresponding to the three laser spots on the optical disc 90.
  • the multi-beam light beam to be formed is shown.
  • the three lasers from the multi-beam LD 41 form three spots on the information recording track on the disk 90 through the optical system by the collimator lens 42, the beam splitter 43, and the objective lens 44. This is the reproduction laser spots SPp1, SPp0, and SPp2 described in FIGS. 8C and 19.
  • Example 2 Reflected light related to these three laser spots is incident on the photodetectors PD3, PD4, and PD5 of the light receiving element section 46 through the optical system of the objective lens 44, the beam splitter 43, and the multilens 45.
  • Example 2 Reflected light related to these three laser spots is incident on the photodetectors PD3, PD4, and PD5 of the light receiving element section 46 through the optical system of the objective lens 44, the beam splitter 43, and the multilens 45.
  • FIG. 25 shows an example of a reproducing optical system when a plurality of laser spots are used for tracking servo, but the multi-beam LD 41 is not used.
  • an LD 51, a collimator lens 42, a beam splitter 43, a grating 52, a QWP (1 ⁇ 4 wavelength plate) 53, an objective lens 44, a multilens 45, a light receiving element unit 46, and a biaxial mechanism 47 Provided.
  • Laser light emitted from the multi-beam LD 41 is converted into parallel light by the collimator lens 42, passes through the beam splitter 43, and reaches the grating 52.
  • the grating 52 can be a polarization grating that diffracts only in the forward path, or a liquid crystal grating that can be diffracted on / off.
  • a three-beam optical system for reproduction can be formed by zero-order light and ⁇ first-order light obtained by the grating 52. Thereby, the reproduction laser spots SPp1, SPp2 in FIG. 6C or the reproduction laser spots SPp1, SPp2, SPp3 in FIG. 8C can be obtained.
  • the zero-order light and the ⁇ first-order light are condensed by the objective lens 44 through the QWP 53 and irradiated onto the optical disc 90.
  • the reflected light from the optical disk 90 passes through the QWP 53 and the grating 52 through the objective lens 44, is reflected by the beam splitter 43, and reaches the multi lens 45. Then, the light is condensed by the multi lens 45 and incident on the light receiving element portion 46.
  • a photodetector corresponding to the reproduction laser spots SPp1, SPp2, and SPp3 by the zero order light and the ⁇ first order light may be configured.
  • FIG. 25 shows a reproducing optical system having a one-beam LD 51, it is also possible to form an optical system capable of recording and reproducing using a two-beam LD, a three-beam LD, or the like.
  • FIG. 26 shows an example of an optical system corresponding to the multilayer optical disk 90 as shown in FIG. 1B.
  • the basic configuration is the same as in the example of FIG. 25, but an expander lens 54 for correcting spherical aberration is provided.
  • the expander lens 54 includes a fixed lens 54a and a movable lens 54b.
  • the movable lens 54b can be displaced in the arrow V direction, that is, in the optical axis direction.
  • the expander lens 54 is driven in accordance with the target layer L so that spherical aberration correction is performed.
  • the grating 52 may be provided between the expander lens 54 and the QWP 53. Alternatively, the grating 52 may be provided between the collimator lens 42 and the beam splitter 43 as shown by a broken-line grating 52A. . When the grating 52 is employed, the polarization dependency is necessary, but when the grating 52A is employed, the polarization dependency is not necessary.
  • FIG. 27 shows a multi-beam light beam in the case where three laser spots are formed on the optical disc 90 in the configuration of FIG.
  • the grating 52A is used.
  • the laser light output from the LD 51 is converted into zero-order light and ⁇ first-order light by the grating 52A, and a multi-beam forming three spots is formed.
  • the reproduction laser spots SPp1, SPp2, and SPp3 described with reference to FIG. 8C can be obtained as the three laser spots with which the layer L of the disk 90 is irradiated.
  • the reflected light related to these laser spots is incident on the light receiving element portion 46 with the illustrated light flux. Accordingly, the light receiving element unit 46 only needs to be configured to detect the reflected light by using a photodetector configuration as shown as Example 2 in FIG.
  • the LD 51 and the light receiving element unit 46 may be configured as shown in FIGS. It is also conceivable that the reproducing laser diode and the recording laser diode are provided independently in each of the examples shown in FIGS.
  • FIG. 28 shows an example of the optical system configuration corresponding to the optical disc 90 provided with the reference surface RL as shown in FIG. 1C.
  • the LD 51, the collimator lens 42, the grating 52A, the beam splitter 43, the objective lens 44, the expander lens 54, the multi lens 45, and the light receiving element unit 46 are the same as those in FIG.
  • an optical system for condensing laser beams having different wavelengths on the reference surface RL is provided. That is, an LD 65, a collimator lens 66, a beam splitter 67, an expander lens 60, a dichroic prism 61, a wavelength QWP, and a wavelength selective aperture limiting element 62 are added.
  • the LD 65 outputs laser light having a wavelength different from that of the LD 51.
  • the LD 51 is a blue laser with a wavelength of 405 nm
  • the LD 65 is a red laser with a wavelength of 650 nm, for example.
  • the laser light emitted from the LD 65 is converted into parallel light by the collimator lens 66 and guided to the expander lens 60 via the beam splitter 67.
  • the expander lens 60 includes a fixed lens 60a and a movable lens 60b, and corrects the focal position so that the laser spot of the red laser light is focused on the reference surface RL.
  • the light is reflected by the dichroic prism 61, is subjected to ⁇ / 4 polarization and aperture restriction by the two-wavelength QWP and the wavelength selection aperture limiting element 62, and then irradiated to the reference surface RL of the optical disc 90 through the objective lens 44.
  • the reflected light from the reference surface RL follows the system of the objective lens 44, the two-wavelength QWP and wavelength selection aperture limiting element 62, the dichroic prism 61, and the expander lens 60, is reflected by the beam splitter 67, and is received by the multi-lens 68. The light enters the portion 69.
  • the laser light from the LD 51 which is a blue laser passes through the collimator lens 66, the grating 52A, the beam splitter 43, the expander lens 54, the dichroic prism 61, the wavelength QWP, the wavelength selection aperture limiting element 62, and the objective lens 44.
  • the target layer L of the optical disc 90 is irradiated.
  • the reflected light is incident on the light receiving element portion 46 through the system of the objective lens 44, the two-wavelength QWP / wavelength selection aperture limiting element 62, the dichroic prism 61, the expander lens 54, the beam splitter 43, and the multilens 45.
  • the red laser light from the LD 65 and the blue laser light from the LD 51 are combined by the dichroic prism 61 and guided to the objective lens 44.
  • the focusing of the objective lens 44 is controlled so that the blue laser is focused on the target layer L.
  • the movable lens 60b of the expander lens 60 is used so that the red laser is focused on the reference surface RL. Is adjusted in the optical axis direction V2.
  • the laser spot is focused on the reference surface RL by adjustment by the expander lens 54 and aperture restriction by the two-wavelength QWP and the wavelength selection aperture limiting element 62.
  • information such as a groove formed on the reference surface RL can be obtained from the reflected light information obtained by the light receiving element unit 69. Accordingly, the tracking servo operation of the objective lens 44 can be executed using this as tracking guide information, and recording or reproduction on the layer L by the blue laser can be executed.
  • FIG. 29A shows a configuration example of an optical system in the case of using the servo laser spot SPp45 to which astigmatism is given as described in FIG.
  • a multi-beam LD 41 As an optical system for irradiating the reproduction laser spots SPp1 and SPp2, a multi-beam LD 41, a collimator lens 42, a beam splitter 43, an expander lens 54, a QWP 53, and an objective lens 44 are provided.
  • a multilens 45 and a light receiving element portion 46 are provided for receiving the reflected light.
  • an LD 70, a collimator lens 71, a 45 ° astigmatic beam diffraction element 72, and an optical path combining prism 73 are provided for irradiation with the servo laser spot SPp45.
  • the laser beam from the multi-beam LD 41 is applied to the target layer L of the optical disc 90 through the collimator lens 42, the optical path synthesis prism 73, the beam splitter 43, the expander lens 54, the QWP 53, and the objective lens 44.
  • the reflected light is incident on the light receiving element portion 46 through the system of the objective lens 44, QWP 53, expander lens 54, beam splitter 43, and multi lens 45.
  • the laser light from the LD 70 is collimated by the collimator lens 71 and then enters the 45 ° astigmatic beam diffraction element 72.
  • the 45 ° astigmatic beam diffractive element 72 has a hologram pattern that causes astigmatism, and the polarities of the pair of sub-beams ( ⁇ first-order light) are opposite to each other. Astigmatism that gives an angle of about 45 ° with respect to the tangential direction of the information recording track formed in the direction and on the layer L of the optical disk 90 is given.
  • the servo laser spot SPp45 described in FIG. 7 and the like is a laser spot having astigmatism of 45 °.
  • the + 1st order light or the ⁇ 1st order light obtained from the 45 ° astigmatic beam diffraction element 72 may be used as the laser light for forming the servo laser spot SPp45.
  • the laser beam for forming the servo laser beam spot SPp45 from the 45 ° astigmatic beam diffraction element 72 is the optical path synthesis prism 73, and the laser beam from the LD 70 (laser for forming the reproduction laser spots SPp1 and SPp2). And the optical disc 90 is irradiated through the same route.
  • the reflected light of the servo laser spot SPp45 is guided to the light receiving element portion 46 through the same path as the reproduction laser spots SPp1 and SPp2.
  • a tangential push-pull signal obtained from reflected light information of the servo laser spot SPp45 having astigmatism having an angle of about 45 ° is used as a tracking error signal, and the tracking error signal is obtained.
  • the reproduction laser spots SPp1 and SPp2 can be controlled on track to information recording tracks, and data can be reproduced from the reflected light information.
  • the recording operation as shown in FIGS. 7A and 7B can be performed by emitting laser light of recording power from the multi-beam LD 41 (or LD 51 instead thereof).
  • the recording operation as shown in FIGS. 7A and 7B can be performed by emitting laser light of recording power from the multi-beam LD 41 (or LD 51 instead thereof).
  • LD 41 or LD 51 instead thereof.
  • the information recording track of the optical disc 90 has a multi-spiral structure such as a double spiral structure or a triple spiral structure, but may have a structure with concentric tracks. That is, as a concentric track, a plurality of adjacent track groups are formed at the track pitch Tp1, and the track groups are separated from each other by the track pitch Tp2. Thereby, an information recording track as shown in FIGS. 2A, 3A, and 4A may be formed.
  • FIG. 2 shows a double spiral structure with 2 tracks as a track group, a triple spiral structure with 3 tracks as a track group, and a quadruple spiral structure with 4 tracks as a track group.
  • FIG. 30 shows an example as shown in FIG. 30 .
  • the track trajectories TKa, TKb, TKc, and TKd have a quadruple spiral structure.
  • the track pitch of each track on the track trajectories TKa and TKb is Tp1
  • the track pitch of each track on the track trajectories TKc and TKd is also Tp1.
  • the track pitch of each track of the track trajectories TKb and TKc is Tp2.
  • a track group in which a plurality of tracks are adjacent at a track pitch Tp1 shorter than the track pitch corresponding to the optical cut-off refers to a set of tracks of the track trajectories TKa and TKb, and the track trajectories TKc and TKd.
  • the track group pitch TpG is a pitch between the track group on the track orbits TKa and TKb and the track group on the track orbits TKc and TKd.
  • This example has a quadruple spiral structure, but is an example in which two tracks each form a track group. When viewed in the disk radial direction, the information recording track structure is the same as in FIG. 2A.
  • the track pitch within the track group is not always constant.
  • a track group is formed by four tracks, and each track in the track group is separated by a track pitch Tp1.
  • the track pitch Tp1 is between tracks TK1 and TK2, between tracks TK2 and TK3, and between tracks TK3 and TK4.
  • the track pitch (Tp1) between the tracks TK1 and TK2, between the tracks TK2 and TK3, and between the tracks TK3 and TK4 is not necessarily the same.
  • the distance between the tracks TK1 and TK2 is 0.15 ⁇ m
  • the distance between the tracks TK2 and TK3 is 0.20 ⁇ m
  • the distance between the tracks TK3 and TK4 is 0.15 ⁇ m, and the like.
  • FIG. 31A is a modification of FIG. 6A
  • FIG. 31B is a modification of FIG. 7A
  • FIG. 31C is a modification of FIG. 8A.
  • the reproduction laser spots SPp1 and SPp2 used for servo use precede the recording laser spots SPr1 and SPr2 in the track line direction. This may be such that the recording laser spots SPr1 and SPr2 precede the track line direction as shown in FIG. 31A.
  • the servo laser spot SPp45 precedes the recording laser spots SPr1 and SPr2.
  • FIG. 31A is a modification of FIG. 6A
  • FIG. 31B is a modification of FIG. 7A
  • FIG. 31C is a modification of FIG. 8A.
  • the recording laser spots SPr1 and SPr2 may precede the recording laser spot SPr1 and SPr2.
  • the reproduction laser spots SPp1, SPp0, SPp2 used for servo are set in a state preceding the recording laser spots SPr1, SPr2, SPr3 in the track line direction.
  • the laser spots SPr1, SPr2, and SPr3 may be in a state preceding the track line direction.
  • an optical disk is given as an example of a recording medium
  • the recording medium is not limited to a disk-shaped recording medium.
  • the track structure and tracking servo system described in the embodiment can be applied to a card-like recording medium such as an optical card.
  • the technique of this indication can also take the following structures.
  • a track group in which a plurality of tracks are adjacent to each other with a track pitch shorter than the track pitch corresponding to the optical cutoff defined by the wavelength of the laser beam to be irradiated and the NA of the irradiation optical system is formed.
  • the track group pitch seen in the track group unit is longer than the track pitch corresponding to the optical cutoff, Irradiating a plurality of tracks in the track group with at least two reproduction laser spots;
  • the difference signal of each radial contrast signal obtained from each reflected light information of two reproduction laser spots is used as a tracking error signal, and at least one reproduction laser spot is selected by tracking servo control using the tracking error signal.
  • Method for reproducing data from the reflected light information by performing on-track control on the information recording track (2) Irradiate n reproduction laser spots corresponding to the number n of tracks in the track group, By performing tracking servo control using a difference signal of each radial contrast signal obtained from each reflected light information of two laser spots out of n as a tracking error signal, the n reproduction laser spots are placed in the track group.
  • the information recording track of the recording medium has a multi-spiral structure in which independent n track tracks are formed in a spiral shape, and the track group is formed by the n track tracks,
  • the track group pitch between the adjacent track groups that are circulated in a multi-spiral structure is longer than the track pitch corresponding to the optical cutoff, While irradiating n reproduction laser spots corresponding to the number n of tracks in the track group, Tracking servo control is performed using the difference signal of each radial contrast signal obtained from each reflected light information of two laser spots of n as a tracking error signal, and the above-mentioned n reproducing laser spots are set to the respective track trajectories.
  • the reproduction method according to (1) wherein the n tracks in the track group are irradiated in a traced state, and the information of each track is reproduced from the reflected light information of the irradiated reproduction laser spot.
  • the reproducing method according to (3), wherein the information recording track has a double spiral structure in which two independent track tracks are formed in a spiral shape, and n 2.
  • the reproducing method according to (3), wherein the information recording track has a triple spiral structure in which three independent track tracks are formed in a spiral shape, and n 3.

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  • Optical Recording Or Reproduction (AREA)
  • Optical Record Carriers And Manufacture Thereof (AREA)

Abstract

L'invention concerne un support d'enregistrement dans lequel sont formés des groupes de pistes comportant une pluralité de pistes d'enregistrement d'informations adjacentes formées en utilisant un pas de piste plus court (Tp1) qu'un pas de piste correspondant à une coupure optique spécifiée par la longueur d'onde d'une lumière laser rayonnée et le NA d'un système optique rayonnant. Un pas de groupe de pistes (TpG) des groupes de pistes est plus long que le pas de piste correspondant à la coupure optique. Des signaux de différence pour chaque signal de contraste radial obtenu par chacune des informations de lumière réfléchies pour deux points laser de reproduction rayonnés sur les groupes de pistes sont utilisés en tant que signaux d'erreur de suivi. Au moins un point laser de reproduction est amené à être sur piste sur l'une des pistes d'enregistrement d'informations et des données sont reproduites à partir des informations de lumière réfléchies à partir de celui-ci, par un asservissement de suivi au moyen de ces signaux d'erreur de suivi.
PCT/JP2012/062268 2011-05-20 2012-05-14 Procédé de reproduction et dispositif de reproduction WO2012161009A1 (fr)

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Citations (6)

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Publication number Priority date Publication date Assignee Title
JPH01140428A (ja) * 1987-11-27 1989-06-01 Victor Co Of Japan Ltd 光ディスク及びその製造方法
JPH04325934A (ja) * 1991-04-25 1992-11-16 Nec Home Electron Ltd 光ディスク記録方法および光ディスク装置
JPH07121876A (ja) * 1993-10-25 1995-05-12 Olympus Optical Co Ltd 光学的情報再生装置
JP2006012301A (ja) * 2004-06-25 2006-01-12 Sony Corp 光記録再生方法、光ピックアップ装置、光記録再生装置、光記録媒体とその製造方法及び半導体レーザ装置
JP2008542963A (ja) * 2005-05-31 2008-11-27 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 不均等な間隔で配されたトラックを伴う光情報担体フォーマットのための半径方向トラッキング方法および装置
JP2009505322A (ja) * 2005-08-22 2009-02-05 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 高周波中央開口トラッキング

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01140428A (ja) * 1987-11-27 1989-06-01 Victor Co Of Japan Ltd 光ディスク及びその製造方法
JPH04325934A (ja) * 1991-04-25 1992-11-16 Nec Home Electron Ltd 光ディスク記録方法および光ディスク装置
JPH07121876A (ja) * 1993-10-25 1995-05-12 Olympus Optical Co Ltd 光学的情報再生装置
JP2006012301A (ja) * 2004-06-25 2006-01-12 Sony Corp 光記録再生方法、光ピックアップ装置、光記録再生装置、光記録媒体とその製造方法及び半導体レーザ装置
JP2008542963A (ja) * 2005-05-31 2008-11-27 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 不均等な間隔で配されたトラックを伴う光情報担体フォーマットのための半径方向トラッキング方法および装置
JP2009505322A (ja) * 2005-08-22 2009-02-05 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 高周波中央開口トラッキング

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