WO2008044212A1 - Disque optique et procédé de détermination de puissance d'enregistrement - Google Patents

Disque optique et procédé de détermination de puissance d'enregistrement Download PDF

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Publication number
WO2008044212A1
WO2008044212A1 PCT/IB2007/054125 IB2007054125W WO2008044212A1 WO 2008044212 A1 WO2008044212 A1 WO 2008044212A1 IB 2007054125 W IB2007054125 W IB 2007054125W WO 2008044212 A1 WO2008044212 A1 WO 2008044212A1
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WO
WIPO (PCT)
Prior art keywords
radiation beam
recording power
power
recording
record carrier
Prior art date
Application number
PCT/IB2007/054125
Other languages
English (en)
Inventor
Yu Zhou
Original Assignee
Koninklijke Philips Electronics N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics N.V. filed Critical Koninklijke Philips Electronics N.V.
Publication of WO2008044212A1 publication Critical patent/WO2008044212A1/fr

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Classifications

    • 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
    • G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
    • G11B7/0045—Recording
    • 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
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
    • G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
    • G11B7/1267—Power calibration

Definitions

  • the subject matter relates to an optical disc recording device, and more specifically to the determination of the recording power of a radiation beam for recording data on an optical disc.
  • a method of determining an optimum recording power of a radiation beam for recording data onto a record carrier determines a first recording power of the radiation beam based on Jitter and a second recording power of the radiation beam based on block error rate.
  • the method further comprises determining the optimum recording power of the radiation beam based on a difference between the first recording power of the radiation beam and the second recording power of the radiation beam.
  • the drive comprises an optical pick up unit arranged to generate a radiation beam and focus the radiation beam on a record carrier.
  • the drive further comprises a control unit arranged to control the optical pick up unit, wherein the control unit further comprises a first recording power determining unit arranged to determine a first recording power of the radiation beam based on Jitter.
  • the control unit further comprises a second recording power determining unit arranged to determine a second recording power of the radiation beam based on block error rate.
  • the control unit further comprises an optimum recording power determining unit arranged to determine the optimum recording power of the radiation beam based on a difference between the first recording power of the radiation beam and the second recording power of the radiation beam.
  • the method that accurately determines an optimum recording power of a radiation beam for recording data onto a record carrier can be implemented with a computer program.
  • Fig. 1 schematically illustrates an exemplary drive
  • Fig. 2 schematically illustrates laser power plotted against Jitter and block error rate (BLER) for an exemplary TDK- R8x DVD+R disc;
  • Fig. 3 shows an exemplary flow chart illustrating steps of the method of determining optimum recording power of a radiation beam according to the present subject matter
  • Fig. 4 schematically illustrates results obtained for an exemplary TDK-R8x DVD+R disc according to the present subject matter
  • Fig. 5 schematically illustrates the selection of an exemplary power calibration range according to the present subject matter
  • Fig. 6 schematically illustrates a full optimum power control procedure as a function of disc radius for an exemplary DVD+R/-R disc.
  • a record carrier e.g. DVD
  • the record carrier can be of a Recordable (R) or Rewritable (RW) type, where information may be stored or recorded, such as DVD+RW, DVD-RW, DVD+R, BD-RE (single layer and multi-layer).
  • the information is generally recorded using radiation beams such as laser beams.
  • Fig. 1 is a block diagram showing structures of an exemplary drive 100.
  • a record carrier 10 is constant angular velocity (CAV) controlled or constant linear velocity (CLV) controlled by a spindle motor 12.
  • CAV constant angular velocity
  • CLV constant linear velocity
  • An optical pick up unit 14 records data onto the record carrier 10 by using laser light (at a recording power value) emitted from a laser diode.
  • the data to be recorded is supplied to an encoder unit 18 and the data encoded by the encoder unit 18 is supplied to a laser diode-driving unit 16.
  • the laser diode-driving unit 16 generates a drive signal based on the encoded data and supplies the drive signal to the laser diode of the optical pickup unit 14.
  • a control signal from a control unit 24 is supplied to the laser diode-driving unit 16 so that the recording strategy and recording power are determined by the control signal.
  • the laser diode of the optical pickup unit 14 When, on the other hand, data is read, the laser diode of the optical pickup unit 14 emits laser light of a read power (read power ⁇ record power), and the reflected light is received. The received reflected light is converted into an electrical signal and a read RF signal is obtained.
  • the read RF signal is supplied to an RF signal processing unit 20.
  • the RF signal processing unit 20 comprises an equalizer, a binarizing unit, a phase lock loop (PLL) unit, and binarizes the read RF signal, generates a synchronous clock, and supplies these signals to a decoder unit 22.
  • the decoder unit 22 decodes data based on these supplied signals and outputs the decoded data as read data.
  • the read RF signal from the RF signal processing unit 20 is also supplied to the control unit 24 for evaluating the read signal quality.
  • the drive 100 also includes a circuit (for data readout) for controlling the focus servo or tracking servo by producing respectively, a tracking error signal or a focus error signal and a wobble signal formed on the record carrier 10 (e.g., for use in address demodulation or for controlling the number of rotations).
  • the servo control structures are identical to those in conventional drive systems and hence are not described in detail.
  • test data is repeatedly recorded in a pre-determined area (i.e., power calibration area) of the record carrier 10 while the recording power is varied.
  • the test data is replayed and a recording power at which the quality of the replayed signal is maximized is selected as the optimum recording power.
  • Data is recorded using the optimum recording power (a process generally referred to as optimum power control (OPC)).
  • OPC optimum power control
  • the control unit 24 executes the optimum power control (OPC) procedure by driving the laser diode-driving unit 16, evaluating the quality of recorded test data, and determining the optimum recording power.
  • the method disclosed in US 2003/0053386 uses error rates to judge whether the calibrated writing power based on Jitter is abnormal. If, using the calibrated writing power, the error rate is higher than the pre-determined level, even if the Jitter is small, the calibration point is abnormal and is not used in determining the optimum writing power. In other words, the error rate is used to determine the validation of the Jitter power calibration point.
  • This determination of optimal write laser power may result in a good Jitter HF recording quality.
  • a good/lower Jitter HF signal could still have a read-back problem due to a very high block error rate (BLER), which could be caused by the variation of the record carrier quality.
  • BLER block error rate
  • the minimum Jitter point corresponds to the minimum block error rate (BLER).
  • BLERb block error rate before recording and represents the amount of errors in the pre-pit signal before recording and R b means groove reflectivity before recording
  • Fig. 2 shows the laser power plotted against the Jitter and the block error rate (BLER).
  • the vertical axis shows the Jitter and the BLER values and the horizontal axis shows the laser power values.
  • the record carrier considered here is a TDK- R8x DVD+R disc which is bad. It is clear from Fig. 2 that the minimum Jitter does not correspond to the minimum BLER values. Using the laser power corresponding to low Jitter for recording data will result in recording and reproducing problems.
  • a method 300 that determines an optimum recording power of a radiation beam for recording data onto a record carrier is shown in Fig. 3.
  • a first recording power of the radiation beam based on Jitter is determined.
  • a second recording power of the radiation beam based on the block error rate (BLER) is determined.
  • the optimum recording power of the radiation beam based on a difference between the first recording power of the radiation beam and the second recording power of the radiation beam is determined.
  • Jitter is a very low-level/ physical indication of HF signal quality. Usually, if the HF signal Jitter is low, the signal quality is guaranteed and thus results in better data accuracy. BLER is the rate of blocks or frames per second having at least one incorrect bit. BLER represents the actual quality of the data that needs to be read. Usually it is assumed that low Jitter means low BLER, and that is why most recorders or players use Jitter as an index for almost all the calibrations. Studies have shown a clear correlation between BLER and Jitter. When Jitter is not all that high, a lower Jitter could result in a high BLER and vice- versa. This could be due to the nature of media and/or the characteristics of the optical disc device system.
  • BLER or Jitter according to the media and system characteristics will guarantee that the corresponding media and the system reach the best performance. Choosing a corresponding power calibration index according to the media and the system characteristics gives the best recording power suitable for those media (i.e., best media recording quality is achieved). With changes of the environment, like temperature and humidity, the media stability and characteristics of DVD+R/RW could change, and the BLER will give a better indication of this change and of the correlation with the uncorrectable error than Jitter. Hence, in the disclosed method BLER is used.
  • determining the optimum recording power of the radiation beam based on the difference between the first recording power of the radiation beam and the second recording power of the radiation beam includes determining the optical recording power of the radiation beam based on calibration steps. This condition helps to decide which calibration power is to be used.
  • the calibration steps are determined based on the resolution of the power of the radiation beam used for recording data onto the record carrier.
  • the number of calibration steps depends upon the calibration power resolutions.
  • the calibration step may correspond to 0.75 mW each. Another way of interpreting this is to use the calibration power difference of 0.75 mW instead of a detailed representation of the calibration power steps.
  • determining the optimum recording power of the radiation beam based on the calibration steps includes determining whether the difference between the first recording power of the radiation beam and the second recording power of the radiation beam is substantially greater than 2 calibration steps. If the difference is greater than 2 calibration steps, it is determined whether the BLER count at the first recording power of the radiation beam is greater than the BLER count at the second recording power of the radiation beam a predetermined number of counts, and if so, the second recording power of the radiation beam is selected as the optimum recording power of the radiation beam.
  • the predetermined number of counts can be around 15.
  • data is recorded on the record carrier using the determined optimum recording power of the radiation beam. This ensures good recording quality and improves overall recording performance.
  • the determination of the first recording power of the radiation beam based on Jitter and of the second recording power of the radiation beam based on BLER includes the following steps and a possible result of this procedure is shown in Fig. 4,
  • test power value reaches a minimum test power which corresponds to Pw ⁇ - 25%. 6. Curve fit the test power values and the corresponding Jitter and BLER values.
  • the power calibration based on Jitter is conducted on the basis of the power calibration result on Beta. That means, the system conducts the beta-OPC first and obtains the calibration light power Pw ⁇ that corresponds to the target beta value required by the media.
  • the starting power for fine-tune calibration based on Jitter will be Pw ⁇ - 25%.
  • the maximum calibration power for Jitter will be Pw ⁇ + 25%. In this calibration power range, 15 steps of power are chosen as shown in Fig. 5.
  • the recording of 8 ADIP frames compensates for possible errors such as eccentricity, when carrying out the measurement of Jitter and BLER, so that the Jitter and BLER read-out measurement takes place during one disc revolution.
  • the recording is performed from outer edge to inner edge of the record carrier.
  • the starting power is derived from the power of Pw ⁇ of beta OPC as shown in Fig 5.
  • the laser power will go from Pw ⁇ + 25 % until Pw ⁇ - 25% in 15 power levels (30 ECC blocks). At each power level, Jitter and BLER are measured during one revolution and the averages are calculated.
  • FS correction refers to the Forward Sense correction.
  • Fig. 6 schematically illustrates a full optimum power control procedure as a function of disc radius for an exemplary DVD+R/-R disc.
  • the procedure includes performing: i) Beta-OPC ii) Jitter & BLER - OPC iii) forward sense correction and iv) Write check.
  • a correction of beta is introduced to compensate for the optical feedback in the laser.
  • the forward sense will be read while writing a blank area on the disc. Therefore 1.5 ECC blocks are written in the inner disc test zone using the actually determined optical power Pw.
  • the forward sense value is read for these 1.5 ECC blocks.
  • a corrected beta value is calculated based on the measured beta value.
  • the delta difference between corrected beta value and measured beta value should be within a certain window, for example 10%, or else, retries are performed till the delta difference is within the allowable window.
  • Fig. 4 is a graph, schematically illustrating an example of results obtained for a good TDK R8x DVD+R disc using the above listed steps.
  • the Jitter, block error rate (vertical axis) is plotted against the test power values (horizontal axis).
  • the boxes indicate the measured results.
  • the point X m is calculated and the first recording power of the radiation beam is set to an optimal value corresponding to the minimum Jitter value.
  • the second recording power of the radiation beam is set to an optimal value corresponding to the minimum block error rate (BLER).
  • the optimum recording power is determined using the first recording power and the second recording power of the radiation beam. The determination of the minimum Jitter or block error rate (BLER) is based on the polynomial regression and hence the optimum recording power obtained is accurate and reliable.
  • the first recording power of the radiation beam and the second recording power of the radiation beam are determined simultaneously. It is to be noted that the BLER measurement should take place along with the Jitter measurement during one disc revolution to compensate for errors such as eccentricity. Jitter and BLER OPC are performed at the same time to reduce the overall OPC time. Averaging over one revolution can filter out random measurement noise and also periodic disturbances introduced by disc deviation and turntable motor wobble.
  • recording test data on the record carrier for each variation of the test power value includes recording the test data in concentric circles with increasing radii from the center of the record carrier to an outer edge of the record carrier. Due to variation in media (such as dust, fingerprints, scratches, dye thickness, manufacturing variation) and the environmental changes, dynamic power calibration is needed to compensate for the deviations found while recording. This ensures good recording quality across the whole record carrier.
  • recording test data on the record carrier for each variation of the test power value includes recording the test data in concentric circles with decreasing radii from outer edge of the record carrier to the center of the record carrier. This ensures good recording quality across the whole record carrier and compensates for media variations.
  • the drive 100 can be adapted to perform the method of determining the optimum recording power of a radiation beam for recording data onto the record carrier 10 as disclosed in the embodiments.
  • the control unit 24 comprises a first recording power determining unit 24A arranged to determine a first recording power of the radiation beam based on Jitter.
  • the control unit 24 further comprises a second recording power determining unit 24B arranged to determine a second recording power of the radiation beam based on block error rate (BLER).
  • BLER block error rate
  • the control unit 24 further comprises an optimum recording power determining unit 24C arranged to determine the optimum recording power of the radiation beam based on a difference between the first recording power of the radiation beam and the second recording power of the radiation beam.
  • a recorder having the drive 100 can perform optimum power calibration and determine the optimum recording power of the radiation beam as disclosed in the embodiments, thereby improving the overall recording performance of the recorder.
  • DVD-RW write-once media and write-many recordable types
  • It is not limited to a two-layer one sided record carrier, i.e. a dual layer record carrier, or to a two-layer double sided record carrier, i.e. a dual layer double sided record carrier.
  • a person skilled in the art can implement the described embodiments of the method of determining optimum recording power of a radiation beam for recording data in software or in both hardware and software.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Abstract

L'invention concerne un procédé (300) de détermination d'une puissance d'enregistrement optimale d'un faisceau de rayonnement pour enregistrer des données sur un support d'enregistrement. Le procédé comporte la détermination d'une première puissance d'enregistrement du faisceau de rayonnement sur la base du gigue et d'une seconde puissance d'enregistrement du faisceau de rayonnement sur la base d'un taux d'erreur sur les blocs (BLER). Le procédé comporte en outre la détermination de la puissance d'enregistrement optimale du faisceau de rayonnement sur la base de la différence entre la première puissance d'enregistrement du faisceau de rayonnement et la seconde puissance d'enregistrement du faisceau de rayonnement. La technique est utile pour les dispositifs d'enregistrement sur disque optique.
PCT/IB2007/054125 2006-10-11 2007-10-10 Disque optique et procédé de détermination de puissance d'enregistrement WO2008044212A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06122059.6 2006-10-11
EP06122059 2006-10-11

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WO2008044212A1 true WO2008044212A1 (fr) 2008-04-17

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030053386A1 (en) * 2001-09-20 2003-03-20 Teac Corporation Optical disk device
US20040008594A1 (en) * 2002-07-10 2004-01-15 Teac Corporation Optical disk apparatus
EP1492117A2 (fr) * 2003-06-26 2004-12-29 Sony Corporation Support de stockage, dispositif et procédé d'enregistrement/de reproduction

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030053386A1 (en) * 2001-09-20 2003-03-20 Teac Corporation Optical disk device
US20040008594A1 (en) * 2002-07-10 2004-01-15 Teac Corporation Optical disk apparatus
EP1492117A2 (fr) * 2003-06-26 2004-12-29 Sony Corporation Support de stockage, dispositif et procédé d'enregistrement/de reproduction

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
S. HARA ET AL: "Write Laser Power Normalization Method for Magneto-Optical Disk Drives", JAPANESE JOURNAL OF APPLIED PHYSICS (REGULAR PAPER & SHOIRT NOTES), vol. 35, no. 1B, January 1996 (1996-01-01), Japan, pages 476 - 480, XP002465688 *

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