WO1999017283A1 - Procede et appareil d'ajustement automatique d'une polarisation de focalisation - Google Patents

Procede et appareil d'ajustement automatique d'une polarisation de focalisation Download PDF

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Publication number
WO1999017283A1
WO1999017283A1 PCT/KR1998/000281 KR9800281W WO9917283A1 WO 1999017283 A1 WO1999017283 A1 WO 1999017283A1 KR 9800281 W KR9800281 W KR 9800281W WO 9917283 A1 WO9917283 A1 WO 9917283A1
Authority
WO
WIPO (PCT)
Prior art keywords
jitter
focus bias
focus
bias voltage
optical disc
Prior art date
Application number
PCT/KR1998/000281
Other languages
English (en)
Inventor
Hong Moon Bae
Original Assignee
Daewoo Electronics Co., Ltd.
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
Priority claimed from KR1019970049149A external-priority patent/KR19990026835A/ko
Priority claimed from KR1019970049165A external-priority patent/KR100253736B1/ko
Priority claimed from KR1019970049173A external-priority patent/KR100253737B1/ko
Priority claimed from KR1019970049174A external-priority patent/KR100253738B1/ko
Application filed by Daewoo Electronics Co., Ltd. filed Critical Daewoo Electronics Co., Ltd.
Publication of WO1999017283A1 publication Critical patent/WO1999017283A1/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
    • G11B7/08—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
    • G11B7/094—Methods and circuits for servo offset compensation
    • 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
    • G11B7/0908—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 focusing only

Definitions

  • the present invention relates to an automatic adjustment of a focus bias in an optical disc system, and more particularly to a method for automatically adjusting a focus bias and an apparatus for performing the method suitable for a focus servo system of an optical disk player, like a compact disc (CD) player, for reading information recorded on a disk in the form of an optical signal.
  • a focus servo system of an optical disk player like a compact disc (CD) player
  • optical disc players which record audio/video signals on semipermanent optical discs and reproduce these recorded audio/ video signals.
  • a compact disc player CDP
  • LDP laser disc player
  • CDGP compact disc graphic player
  • VCDP video compact disc player
  • Such optical disc players can output video and/or audio signals recorded on the optical discs by speakers rather than by video and/or audio reproducing equipments.
  • the optical disc players can reproduce signals with a better quality in a picture and a sound, and prevent noises caused by irregular reproduction and unstable modulation from occurring. They have further advantages that their output signals have little distortion and ghost and that a random access operation is available. Due to the above mentioned preferences-advantages, the optical disc players have been developed rapidly and promulgated widely. Meanwhile, for the precise readout of a program recorded on the optical disc in the optical disc player, a signal surface of the optical disc should be located within a focus depth of a laser beam irradiated from the optical pick-up unit, for which a focus bias adjustment and a focus servo are necessary.
  • SNR signal-to-noise ratio
  • the focus bias adjustment adjusts the signal surface of the optical disc to be located within the focus depth of the laser beam and the focus servo adjusts a beam focus to a minute variation in a disc equilibrium when the signal surface of the optical disc is located within a predetermined focus depth of the laser beam.
  • FIGs. la and lb There are two waveforms in FIGs. la and lb.
  • FIG la shows a waveform in a condition that a focus bias between a reproducing signal and a recorded signal of the optical disc are adjusted and
  • FIG lb shows a waveform that is not adjusted.
  • transition points between the reproducing signal and the recorded signal will have no difference in a time axis. Otherwise, in an out-of-focus state, the transition points between these two signals have a phase difference in the time axis as shown in FIG. lb.
  • This phase difference ( ⁇ t) between the two signals i.e. the reproduction signal and the original signal, causes a jitter to result in an high error ratio of the reproduction signal.
  • the picture displays a false state and/or the sound includes noise.
  • the present invention is intended for overcoming the above described disadvantages.
  • a first object of the present invention is to provide a method for automatically adjusting a focus bias in an optical disc player capable of automatically adjusting the focus bias by using a jitter deviation corresponding to a degree of a focus bias adjustment.
  • a second object of the present invention is to provide a method for automatically adjusting a focus bias value by using experimental data of the focus bias value, which were stored in advance, capable of minimizing a jitter to every range of a jitter.
  • a third object of the present invention is to provide a method for automatically adjusting one focus bias by using an arithmetical mean value of a focus bias voltage when a positive maximum jitter is detected, and adjusting another focus bias voltage when a negative maximum jitter is detected, after detecting a jitter deviation corresponding to a degree of a focus bias adjustment.
  • a fourth object of the present invention is to provide a method for automatically adjusting a focus bias of an optical disc player, capable of adaptively responding to a characteristics of an optical pick-up system, by adjusting the focus bias with a focus bias voltage where a jitter becomes minimized.
  • a fifth object of the present invention is to provide an apparatus for automatically adjusting a focus bias of an optical disc suitable for performing the above-mentioned methods.
  • the first object can be achieved by a method for automatically adjusting a focus bias of an optical disc player, which comprises the steps of:
  • a method for automatically adjusting a focus bias of an optical disc player comprises the steps of:
  • a focus bias value which is a value corresponding to a range of a jitter, capable of minimizing the jitter as a table-up data
  • step (II) detecting the jitter of the optical disk player by reading out a radio frequency signal from a loaded optical disc; (III) obtaining, with reference to the table-up data, the focus bias value corresponding to the jitter detected in step (I); and
  • step (IV) adjusting the focus bias of the optical disk player by using the focus bias value obtained in step (III).
  • a method aiming at the third object for automatically adjusting a focus bias of an optical disc player comprises the steps of:
  • a method for automatically adjusting a focus bias of an optical disc player comprises the steps of:
  • step (c) setting a third focus bias voltage, as a focus bias voltage, which is an addition of half of the predetermined voltage to the second bias voltage in the event that the third jitter, detected in step (b), is greater than the reference jitter and that the second jitter is greater than the third jitter, and setting a fourth focus bias voltage, as a focus bias voltage, which is an subtraction of half of the predetermined voltage from the second bias voltage in the event that the third jitter, detected in step (b), is greater than the reference jitter and that the second jitter is smaller than the third jitter;
  • an apparatus for automatically adjusting a focus bias of an optical disc player comprises: a key input section; an optical disc player, outputting a reproduction signal, including an optical pick-up section for detecting data and a focus servo section for focusing a servo corresponding to a voltage level of a focus error signal after detecting the focus error signal from an electric signal that controls the focus servo section and that is outputted from the optical pick-up section; a jitter detector for detecting a jitter that is an reading error of a data, recorded on an optical disc, triggered by an inaccurate adjustment of a focus bias arising from a voltage for the focus bias for whom the optical disc player provides; a focus bias adjusting section for adjusting the focus bias to locate a surface level of the optical disc within a focus depth of a laser beam of the pick-up section by providing the focus bias voltage for the optical pick-up section; and a system controller for controlling the optical disc player that corresponding to the signals provided by the key input section and
  • FIG. la is a waveform showing that a reproduction signal of and an original signal of an optical disc were adjusted to their focus bias
  • FIG. lb is a waveform indicating that a reproduction signal of and an original signal of an optical disc were not adjusted to their focus bias
  • FIG. 2 is a block diagram illustrating an apparatus for automatically adjusting a focus bias of an optical disc player according to the present invention
  • FIG. 3 is a flowchart describing a method for automatically adjusting a focus bias in an optical disc player according to the first embodiment of the present invention
  • FIG. 4 is a flowchart explaining a method for automatically adjusting a focus bias in an optical disc player according to the second embodiment of the present invention
  • FIG. 5 is a flowchart illustrating a method for automatically adjusting a focus bias in an optical disc player according to the third embodiment of the present invention
  • FIG. 6 is a graph depicting a jitter ?with /corresponding to a variation of a focus bias voltage in the third embodiment of the present invention.
  • FIGs. 7a and 7b are flowcharts illustrating a method for automatically adjusting a focus bias in an optical disc player according to the fourth embodiment of the present invention. Best Mode for Carrying Out the Invention
  • FIG. 2 shows a block diagram of an apparatus according to the present invention.
  • the apparatus includes a key input section 100, a system controller 200, an optical disc player 300, a jitter detecting section 400, a focus bias adjusting section 500, and a data storing section 600.
  • the key input section 100 having a plurality of function keys such as a power key and a program selection key and so on, provides key signals for the system controller 200 by responding to a user's key selections.
  • the system controller 200 controls an operation of the optical disc player 300.
  • the system controller 200 controls the operation of the focus bias adjusting section 500 by responding to the variation of the focus bias that corresponds to a jitter deviation stored in the data storing section 600 and in the jitter provided by the jitter detecting section 400.
  • the optical disc player 300 including a focus servo section 310 and an optical pick-up unit 320, performs a reproducing mode by means of a control of the system controller 200, and provides reproduction signals for the jitter detecting section 400.
  • the jitter detecting section 400 detects jitters from reproduction signals provided by the optical disc player 300, and provides the detected jitters for the system controller 200.
  • the focus bias adjusting section 500 is a sort of bias voltage supplier. By means of the control of the system controller 200, the focus bias adjusting section 500 applies a bias voltage to the optical pick-up unit 320 installed in the optical disc player 300, and adjusts the focus bias for obtaining the just-in focus state between focuses of the object lens and a focusing error signal.
  • the data storing section 600 stores the data of the jitter detected by the jitter detecting section 400.
  • the data storing section 600 stores a focus bias value, with being turned into a table-up data, capable of minimizing the jitter by a predetermined range of the jitter.
  • the variation data of the focus bias voltage related to each range of the jitters should be obtained by a large number of experiments in advance.
  • the system controller 200 controls the focus bias adjusting section 500 to adjust the focus bias to set by a reference focus bias voltage F(P).
  • the focus bias adjusting section 500 provides the reference focus bias voltage F(P) for an actuator coil (not shown) of the optical pick-up unit 320 by means of the control of the system controller 200.
  • the focus bias voltage is provided for an actuator coil of optical pick-up unit 320, but any descriptions about this will be left out (step S104).
  • the system controller 200 controls the optical disc player 300 to reproduce the optical disc, loaded into the optical disc player 300, during a first period . While the first period during which the optical disc player 300 drives the optical disc by means of the control of the system controller 200 reads out a reproduction signal from the optical disc, and provides the reproduction signal to jitter detecting section 400 (step SI 06). At this time, in the referred embodiment of present invention, it is possible to play back of a table of contents (TOC) section to detect jitter.
  • TOC table of contents
  • the jitter detecting section 400 detects a first jitter J(P) from the reproduction signal supplied by the optical disc player 300, and provides information about the detected first jitter J(P) for the system controller 200 (step S108).
  • the system controller 200 stores this information about the detected first jitter J(P) in a memory of the data storing section 600 or in the system controller 200, and controls the focus bias adjusting section 500 to adjust the focus bias to be set at a maximum voltage F(M) out of the range of variable quantities of the focus bias voltages.
  • the focus bias adjusting section 500 provides the maximum focus bias voltage F(M) for the optical pick-up unit 320 installed in the optical disc player 300 by means of the control of the system controller 200 (step SI 10).
  • a second jitter J(M) can be detected by the steps identical with those for the first jitter. Information about the detected second jitter
  • J(M) is provided for the system controller 200 (step SI 12).
  • the system controller 200 subtracts the first jitter J(P), stored in step
  • the system controller 200 refers to a table of a data concerning a variation of the focus bias to the jitter deviation (E) stored in the storing section 600 as shown in following Table 1.
  • the system controller 200 controls the focus bias adjusting section 500 to change the focus bias as much as the variation corresponding to the deviation range in which the jitter deviation E calculated in step SI 14 is included.
  • the focus bias adjusting section 500 provides the optical pick-up unit 320 with a focus bias voltage F(P1) to which the focus bias is updated as much as the variation corresponding to the range of the jitter deviation by means of the control of system controller 200 (step SI 16).
  • the controller 200 controls the optical disc player 300 to play back the optical disc loaded into the optical disc player 300 during a next period.
  • the optical disc player 300 reads out the reproduction signal from the optical disc by the time for the playback, and provides the reproduction signal for the jitter detecting section 400 by means of the control of the system controller 200 (step SI 18).
  • the jitter detecting section 400 detects a third jitter J(P1) through the reproduction signal, and provides information about the detected third jitter J(P1) for the system controller 200 (step SI 20).
  • the system controller 200 compares the third jitter J(P1) provided by the jitter detecting section 400 in step SI 20 with the first jitter J(P) stored in step S108 (step S122).
  • the system controller 200 recognizes the event that the third jitter is greater than the first jitter as a just-in-focus state that the current focus bias is optimally adjusted, and controls the focus bias adjusting section 500 to adjust the focus bias to the present focus bias voltage.
  • the focus bias adjusting section 500 provides the current focus bias voltage F(P1) for the optical pick-up unit 320 loaded into the optical disc player 300 by means of the control of the system controller 200, and maintains this state (step SI 24).
  • step SI 22 if the comparison in step SI 22 results in the event that the third jitter J(P1) is smaller than the first jitter J(P), the system controller 200 recognizes this event as an out-of-focus state that the present focus bias adjustment is not optimal, and controls the control/overall? operations of the optical disc player 300 to repeat steps SI 14 to S122 until the third jitter J(P1) becomes greater than the first jitter J(P).
  • FIG. 4 is a flowchart illustrating a method for automatically adjusting the focus bias of the optical disc player according to the second embodiment of the present invention.
  • the system controller 200 controls the optical disc player 300 to reproduce this disc loaded into the optical disc player during a predetermined time. Then, by means of the control of the system controller 200, the optical disc player 300 reproduces the optical disc during the predetermined time, detects RF signals from the optical disc, and provides the detected RF signal for the jitter detecting section 400 (step S204).
  • the jitter detecting section 400 detects a jitter (Jn) from the RF signals provided by the optical disc player 300, and provides the detected jitter (Jn) for the system controller 200 (step S206).
  • the system controller 200 searches a focus bias value (Fbn) against the jitter (Jn) which is identical with the detected jitter (Jn) from the jitter detecting section 400, and then controls the focus bias adjusting section 500 to perform the bias adjustment by using the searched focus bias value (Fbn) (step S208).
  • each focus bias value is a voltage value capable of minimizing the jitter in each range of jitters.
  • a jitter ⁇ t against a focus bias value (V) can be stored, like following Table 2, by carrying out many experiments. (Table 2)
  • the focus bias adjusting section 500 provides a detected focus bias value from step S208 for the actuator coil that is equipped with the optical pick-up unit 320 by the control of the system controller 200 (step S210). Accordingly, the actuator coil corresponding to the focus bias voltage can reduce the jitter by carrying out the focus servo, while movmg/maintaining the object lens (not shown) close to or remote from a signal surface of the optical disc.
  • the system controller 200 controls the focus bias adjusting section 500 by using the second focus bias value (Fb2).
  • the focus bias adjusting section 500 by means of the control of the system controller 200, provides the second bias value F b2 for the actuator coil (not shown) that is equipped with optical pick-up unit 320.
  • This actuator coil can reduce the jitter by performing the focus servo, while moving the object lens close to or remote from the surface of the optical disc and responding to the focus bias voltage.
  • the focus bias can be adjusted, without detecting the jitter at the variation of the focus bias one by one, by directly searching the focus bias voltage capable of minimizing the jitter in the data storing section and by adjusting the optical disc player's focus bias by the searched focus bias voltage. By doing this, the time for adjusting the focus bias can be shortened.
  • FIG. 5 is a flowchart depicting the third embodiment of a method for auto- adjusting a focus bias of the optical disc player.
  • FIG. 6 is a graph showing a jitter responding to the variation of the focus bias voltage.
  • a and B represent a positive and a negative maximum jitters respectively.
  • A' and B' represent the focus bias voltages of the positive maximum jitter and the negative maximum jitter respectively.
  • the ⁇ A and ⁇ B represent a positive and a negative variable quantities of the jitter respectively.
  • the system controller 200 searches information about a jitter detected from each of the focus bias voltages stored, by being turned into a table, in the data storing section 600, reads out a first focus bias voltage F(A) from which the positive of the maximum jitter (A) is detected and a second focus bias voltage F(B) at/from which the negative of the maximum jitter (B) is detected, and stores the voltages of F(A) and F(B) in the data storing section 600 or in the inner memory (step S304).
  • the system controller 200 controls the focus bias adjusting section 500 to adjust the focus bias to the third focus bias voltage F(A') that is increased as much as a predetermined voltage established in the first focus bias voltage F(A) and stored in step S304.
  • the focus bias adjusting section 500 provides the third focus bias voltage F(A') for the actuator coil by the control of the system controller 200 (step S306).
  • the system controller 200 controls the optical disc player 300 into which the optical disc is loaded to playback the optical disc during a predetermined time.
  • the optical disc player 300 provides the jitter detecting section 400 with the reproduction signals that were read out from the optical disc reproduced during a predetermined time, (step S308).
  • TOC table of contents
  • the jitter detecting section 400 detects a first jitter J(A') by means of the reproduction signal supplied by the optical disc player 300, and provides information about the detected first jitter J(A') for the system controller 200.
  • the system controller 200 after storing information about the first jitter J(A') in the inner memory of the system controller 200 or in the data storing section 600 (step S310), controls the focus bias adjusting section 500 to adjust the focus bias to the fourth bias voltage F(B') increased by a determined voltage from the second focus bias voltage F(B) stored in step S304.
  • the focus bias adjusting section 500 provides the maximum focus bias voltage for the optical pick-up unit loaded into the optical disc player 300 by the control of the system controller 200 (step S312).
  • this system controller 200 controls the optical disc player 300 to reproduce the optical disc during a predetermined time.
  • the optical disc player 300 after reading out a reproduction signal from the optical disc that is reproduced within a predetermined time while adjusting to the focus bias voltage by the control of the system controller 200, provides the reproduction signal for the jitter detecting section 400 (step S314).
  • the jitter detecting section 400 detects a second jitter J(B') by means of the reproduction signal provided by the optical disc player 300, and provides information about the detected second jitter J(B') for the system controller 200 (step S316).
  • the system controller 200 calculates the positive jitter variation ⁇ A by subtracting the third focus bias voltage F(A') from the first focus bias voltage F(A) and the negative jitter variation ⁇ B by subtracting the fourth focus bias voltage F(B') from the second focus bias voltage F(B) (step S318).
  • step S318 the system controller 200 compares between the positive jitter variation ⁇ A and the negative jitter variation ⁇ B each other (step S320).
  • the system controller 200 calculates a focus bias voltage F(M) that is an average value of the first and the second focus bias voltages, i.e. , F(A) and F(B), and then multiplies the average value by a ratio ( ⁇ B/ ⁇ A) of the negative jitter variation ⁇ B to the positive jitter variation ⁇ A.
  • the system controller 200 controls the focus bias adjusting section 500 to adjust the focus bias to a fifth focus bias voltage F(M') which is the production of the average value and the ratio.
  • the focus bias adjusting section 500 provides the fifth focus bias voltage F(M') for the optical pick-up unit 320 by the control of the system controller 200 (step S322).
  • the system controller 200 multiplies the average value of the first and the second focus bias voltages, i.e., F(A) and F(B), by a ratio ( ⁇ A/ ⁇ B) of the positive jitter variation ⁇ A to the negative jitter variation ⁇ B, and controls the focus bias adjusting section 500 to adjust the focus bias to a sixth focus bias voltage F(M"), which is the production of the average value and the ratio.
  • the focus bias adjusting section 500 provides the sixth focus bias voltage F(M") for the optical pick-up unit 320 by the control of the system controller 200 (step S324).
  • FIGs. 7a and 7b are flowcharts illustrating a method for auto-adjusting a focus bias of the optical disc player which is a fourth embodiment of the present invention.
  • the optical pick-up unit 320 After loading the optical disc into the optical disc player 300 (step S402), the optical pick-up unit 320 detects a radio frequency signal from the optical disc, and provides the detected radio frequency signal for the jitter detecting section 400.
  • the jitter detecting section 400 measures a first jitter Jl from the radio frequency signal, and provides the measured first jitter Jl for the system controller 200 (step S404).
  • the system controller 200 stores the first jitter Jl in the inner memory (step S406), and compares the first jitter Jl with a reference jitter T (step S408). As a result of the comparison in step S408, if the first jitter Jl is smaller than the reference jitter T, the system controller 200 finishes a focus bias adjusting mode by regarding the focus bias as being adjusted optimally (step S410). On the other hand, if the first jitter Jl is greater than the reference jitter T, the system controller 200 controls the focus bias adjusting section 500 to apply the first bias voltage VI to the focus servo section 310 (step S412). The focus servo section 310 carries out the focus servo control in the state that the focus bias is adjusted/ set by the first bias voltage VI.
  • the optical pick-up unit 320 detects the radio frequency signal when the focus bias has adjusted at the first voltage, and provides the radio frequency signal for the jitter detecting section 400 (step S414). Accordingly, the system controller 200 stores the second jitter J2 in the inner memory (step S416), and compares the second jitter J2 with the reference jitter T (step S418). From a result of the comparison in S418 showing that the second jitter J2 is smaller than the reference jitter T, the system controller 200 finishes a focus bias adjusting mode by regarding the focus bias as being adjusted optimally.
  • the focus servo section 310 performs the focus servo control by means of the focus bias set by the second bias voltage VI.
  • the optical pickup unit 320 After adjusting the focus bias to the second bias voltage V2, the optical pickup unit 320 detects the radio frequency signal, and provides the detected radio frequency signal.
  • the jitter detecting section 400 measures the radio frequency signal to detect a third jitter J3 which corresponds to the second bias voltage V2, and provides the third jitter J3 for the system controller 200 (step S424).
  • the system controller 200 stores the third jitter J3 in the inner memory (step S426), and then compares the third jitter J3 with the reference jitter T (step S428). From a result of the above comparison showing that the third jitter J3 is smaller than the reference jitter T, the system controller 200 finishes the focus bias adjusting mode by regarding the current focus bias as being adjusted optimally.
  • the system controller 200 compares the second jitter J2 with the third jitter J3 (step S430). If the comparison in step 430 discloses that the third jitter J3 is smaller than the second jitter, the system controller 200 controls the focus bias adjusting section 500 to provide the focus servo section 310 with the third bias voltage that is the addition of half of the predetermined voltage Kl to the second bias voltage V2 (step S432), and finishes the adjustment of the focus bias.
  • the system controller 200 controls the focus bias adjusting section 500 to provide the focus servo section 310 with the fourth bias voltage, which is the subtraction amounting to half of the predetermined voltage Kl from the second bias voltage V2 (step S434), and finishes the adjustment of the focus bias. Meanwhile, in the event that the second jitter J2 is greater than the first jitter
  • the system controller 200 controls the data storing section 600 to provide the fifth bias voltage V5, which is the subtraction of double the predetermined voltage Kl from the first bias voltage VI, for the focus servo section 310 (step S436).
  • the focus servo section 310 performs the focus servo-control with a focus bias set at the fifth bias voltage V5 .
  • the optical pick-up unit 320 detects the radio frequency signal which is provided for the jitter detecting section 400.
  • the jitter detecting section 400 measures the fourth jitter J4, which corresponds to the fifth bias voltage V5, from the radio frequency signal, and provides the fourth jitter J4 for the system controller 200 (step S438).
  • the system controller 200 stores the fourth jitter J4 in the inner memory (step S440), and then compares the fourth jitter J4 with the reference jitter T (step S442). If the comparison in step 442 shows that the fourth jitter J3 is smaller than the second jitter, the system controller 200 finishes the focus bias adjusting mode by treating the focus bias as being optimally adjusted. Otherwise, the system controller 200 performs the comparison of the fourth jitter J4 with the second jitter J2 (step S444).
  • the system controller 200 controls the focus bias adjusting section 500 to provide the sixth bias voltage V6, which is the addition of half of the predetermined voltage Kl to the fifth bias voltage V5, for the focus bias servo section 310 (step S446), and finishes the focus bias adjustment.
  • the system controller 200 controls the focus bias adjusting section 500 to provide the seventh bias voltage V7, which is the subtraction of half of the predetermined voltage Kl from the fifth bias voltage V5, for the focus bias servo section 310 (step S448), and finishes the focus bias adjustment.
  • the focus adjustment can function adaptively to the characteristics of the optical pick-up system by auto-adjusting the focus bias at which the jitter can be minimized with reference to the jitter of the reproduction signal which is read out from an optical disc unit.
  • an auto-adjustment for the just-in-focus state can be achieved, and thereby the original signals can be produced by preventing a false action such as a ghost in the output picture and noise occurring in the output sound.

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  • Optical Recording Or Reproduction (AREA)

Abstract

L'invention se rapporte à un procédé et à un appareil permettant d'ajuster automatiquement une polarisation de focalisation. Une donnée de table de recherche associée à une variation de la polarisation de focalisation correspondant à l'amplitude d'un écart de gigue est stockée en mémoire. Une première valeur de gigue générée par une polarisation de focalisation préétablie est détectée au cours d'un laps de temps préétabli destiné à la lecture des informations du disque optique, et cette première valeur de gigue est stockée. Une deuxième valeur de gigue, générée au cours d'un laps de temps préétabli destiné à la lecture des informations du disque optique est alors détectée après ajustement de la polarisation de focalisation au maximum d'une valeur ajustable. Puis, après avoir calculé l'écart entre la première valeur de gigue et la deuxième valeur de gigue, on détermine une troisième valeur de gigue en se reportant à une donnée de table de recherche après ajustement d'une polarisation de focalisation à une variation de polarisation correspondant à l'écart de gigue calculé. On maintient alors une valeur de polarisation courante pour ajuster la polarisation de focalisation en vue de son application dans des conditions où la première valeur de gigue est supérieure à la troisième valeur de gigue. Dans des conditions opposées, on effectue un retour à l'étape de calcul de l'écart entre la première valeur de gigue et la troisième valeur de gigue. On parvient ainsi à un ajustement automatique amenant à un état de focalisation précise, ce qui permet de produire les signaux originaux en évitant les défauts du type image fantôme dans l'image de sortie et bruit dans le son de sortie.
PCT/KR1998/000281 1997-09-26 1998-09-15 Procede et appareil d'ajustement automatique d'une polarisation de focalisation WO1999017283A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
KR1997/49173 1997-09-26
KR1019970049149A KR19990026835A (ko) 1997-09-26 1997-09-26 광디스크 플레이어의 포커스 바이어스 조정 방법
KR1997/49165 1997-09-26
KR1019970049165A KR100253736B1 (ko) 1997-09-26 1997-09-26 광디스크 시스템의 포커스 바이어스 조정 방법
KR1997/49149 1997-09-26
KR1019970049173A KR100253737B1 (ko) 1997-09-26 1997-09-26 광디스크 플레이어의 포커스 바이어스 조정 방법
KR1019970049174A KR100253738B1 (ko) 1997-09-26 1997-09-26 광디스크 플레이어의 포커스 바이어스 조정 방법
KR1997/49174 1997-09-26

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EP1085508A2 (fr) * 1999-09-16 2001-03-21 Sony Corporation Appareil d'enregistrement et lecture de disque optique, méthode de correction de la mise au point, disque optique

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EP0423731A2 (fr) * 1989-10-16 1991-04-24 Matsushita Electric Industrial Co., Ltd. Dispositif d'accès aux pistes et dispositif de suivi de piste
EP0586084A2 (fr) * 1992-08-04 1994-03-09 Sony Corporation Appareil de reproduction
JPH0944864A (ja) * 1995-07-27 1997-02-14 Kenwood Corp フォーカスサーボの自動調整方法

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EP0423731A2 (fr) * 1989-10-16 1991-04-24 Matsushita Electric Industrial Co., Ltd. Dispositif d'accès aux pistes et dispositif de suivi de piste
EP0586084A2 (fr) * 1992-08-04 1994-03-09 Sony Corporation Appareil de reproduction
JPH0944864A (ja) * 1995-07-27 1997-02-14 Kenwood Corp フォーカスサーボの自動調整方法

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1085508A2 (fr) * 1999-09-16 2001-03-21 Sony Corporation Appareil d'enregistrement et lecture de disque optique, méthode de correction de la mise au point, disque optique
EP1085508A3 (fr) * 1999-09-16 2001-11-21 Sony Corporation Appareil d'enregistrement et lecture de disque optique, méthode de correction de la mise au point, disque optique
US6842408B1 (en) 1999-09-16 2005-01-11 Sony Corporation Optical disk apparatus, focus-value correcting method, and optical disk
KR100718621B1 (ko) * 1999-09-16 2007-05-16 소니 가부시끼 가이샤 광 디스크 장치, 초점값 보정 방법, 및 광 디스크

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