WO1999017280A1 - Appareil de lecture de disque optique et procede de recherche de piste - Google Patents

Appareil de lecture de disque optique et procede de recherche de piste Download PDF

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Publication number
WO1999017280A1
WO1999017280A1 PCT/KR1998/000278 KR9800278W WO9917280A1 WO 1999017280 A1 WO1999017280 A1 WO 1999017280A1 KR 9800278 W KR9800278 W KR 9800278W WO 9917280 A1 WO9917280 A1 WO 9917280A1
Authority
WO
WIPO (PCT)
Prior art keywords
track
target track
address
virtual target
optical disc
Prior art date
Application number
PCT/KR1998/000278
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 KR1019970049167A external-priority patent/KR100256644B1/ko
Priority claimed from KR1019970049142A external-priority patent/KR19990026828A/ko
Application filed by Daewoo Electronics Co., Ltd. filed Critical Daewoo Electronics Co., Ltd.
Publication of WO1999017280A1 publication Critical patent/WO1999017280A1/fr

Links

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
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08505—Methods for track change, selection or preliminary positioning by moving the head
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/102—Programmed access in sequence to addressed parts of tracks of operating record carriers
    • G11B27/105—Programmed access in sequence to addressed parts of tracks of operating record carriers of operating discs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
    • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
    • G11B27/11—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information not detectable on the record carrier
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
    • G11B2220/2537—Optical discs
    • G11B2220/2545—CDs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
    • G11B2220/2537—Optical discs
    • G11B2220/2562—DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/20—Disc-shaped record carriers
    • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
    • G11B2220/2537—Optical discs
    • G11B2220/2587—Laser Discs; Optical disc using analog recording
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B2220/00—Record carriers by type
    • G11B2220/60—Solid state media
    • G11B2220/65—Solid state media wherein solid state memory is used for storing indexing information or metadata

Definitions

  • the present invention relates to a system for reproducing programs recorded on an optical disc and a method for searching a track, and more particularly to, in the event that a readability of identifying information of a target track read out from a disc is poor due to a surface defect of the target track on the disc, an optical disc reproducing apparatus and a method for searching a track that seek an adjacent track where track identifying information read out from the disc is readable and that reproduce the data from the sought adjacent track.
  • an optical disc such as a compact disc (CD), an laser disc (LD), a digital video disc (DVD) and the like
  • digital information is recorded first in the shape of a prominence and depression on the base plate of the optical disc, a reflection film is coated next, and then a transparent protection layer is formed. Therefore, after applying a beam to the optical disc, information recorded on the optical disc can be read out by detecting the difference of beam intensity caused by the phase difference of the beam reflected from the prominence and depression. Accordingly, if the surface of the optical disc is scrubbed or contaminated, the readability of the optical disc becomes poor.
  • the optical disc reproducing apparatus guarantees the recovering function of data by detecting and correcting the errors on signal processing. If the status of the surface defect, however, is beyond the capability of error correction of an applied apparatus or a method, the desired recovery of the damaged data will fail.
  • a method for searching a track can randomly access to the data recorded on the optical disc.
  • Such a track search can be performed by reading out track addresses, calculating the difference between a target address and the readout address, and moving a beam toward reducing the difference between these addresses. Accordingly, if the address of the target track is not readable due to surface defects of the optical disc, the track search will not be completed perfectly, which results in the impossibility of reproducing information on the optical disc.
  • the United States Patent No. 4,845,697 entitled “METHOD OF TIME LIMITED SEARCHING FOR A TRACK ADDRESS ON AN OPTICALLY READ INFORMATION DISC” discloses a reproducing apparatus and a method of disc information .
  • This patent relates to a method that finds out the position of information adjacent to a target track when the readability of the address code of the target track goes below a desired reference to perfect data reproduction.
  • the control algorithm of the patent is complex since a zigzag scan over the area around the target track is needed to find the neighboring location of recorded information.
  • the apparatus comprises an optical pick-up for moving toward a radius of the optical disc, irradiating an optical beam in the information recording area, and transforming a beam reflected from the optical disc into a high frequency signal to output; a data restoring part for restoring a track address and data from the high frequency signal provided by the optical pick-up; a tracking servo part for controlling a tracking servo of the optical pick-up; a memory for storing at least one or more position information about a first and a second virtual target tracks; an input part for selecting a program of the optical disc; and a control part for controlling the tracking servo part to move the optical beam toward reducing a difference between a track address informed by the data restoring part and a target track address selected by the input part and, in the event that the provision of the target track address is not available from the data restoring part, to reproduce selected program information by taking a closest track, which is searchable toward an outer track after passing the target track, to the original track, as a new virtual target track
  • the first method of this invention comprises six steps: the first step is to move an optical beam toward the position of a target track to reduce the difference between a track address reproduced from an optical disc and a position value of a selected target track; the second step is to newly set a first adjacent track, as a first virtual target track, which passes the position of the selected target track at a first predetermined distance from the target track, in the event that the selected target track fails to be reproduced within the predetermined time; the third step is to repeat the second step until an address of this first virtual target track is searched; the fourth step is, once this first virtual target track is searched, to newly set a second adjacent track apart from the searched position toward an inner radius by a second predetermined distance which is shorter than the first predetermined distance, as a second virtual target track; the fifth step is to repeat the fourth step until a search for an address of this second virtual target track fails; and the sixth step is, in the event that a search for the address of the second virtual target track as set in the fourth step fails in the fifth step, to set the first
  • the second method of this invention comprises six steps: the first step is to move an optical beam toward a target track position to reduce the difference between a track address reproduced from an optical disc and a position value of a selected target track; the second step is, in the event that the reproduction of the selected target track fails despite a predetermined number of repetition, to newly set a first adjacent track passing this target track by a first predetermined distance as a first virtual target track; the third step is to repeat the second step until an address of the first virtual target track is searched; the fourth step is, once the virtual target track is searched, to newly set a second adjacent track apart from the searched position toward an inner radius by a second predetermined distance that is shorter than the first predetermined distance, as a second virtual target track; the fifth step is to repeat the fourth step until a search for an address of the second virtual target track fails; and the sixth step is, in the event of the failure of searching for the address of the second virtual track in the fifth step, to set the address of the just searched second virtual target track as a modified target track and to
  • FIG. 1 is a block diagram showing the first embodiment of an optical disc reproduction apparatus according to the present invention
  • FIG. 2 is an illustration of a relationship between a target track and a virtual track on the optical disc during a track search of the optical disc reproduction apparatus according to the present invention
  • FIG. 3 is a flow chart explaining the first embodiment of a method for searching a track that uses the optical disc reproduction apparatus according to the present invention.
  • FIG. 4 is a flow chart illustrating the second embodiment of the method for searching the track that uses the optical disc reproduction apparatus according to the present invention.
  • the optical disc reproduction apparatus includes a spindle motor 20 for rotating an optical disc 10, an optical pick-up 30, a data restoration part 40, a data precess part 50, a servo part 60, an input part 70, a memory 80, and a control part 90.
  • a coarse adjusting motor moves the optical pick-up 30 toward a radius of the optical disc 10.
  • the optical pick-up 30 irradiates an optical beam onto the recording side of the optical disc 10, receives the beam reflected from the recording side, and generates a high frequency signal corresponding to an amount of the received beam. Accordingly, the optical pick-up 30 is focus-controlled to focus the optical beam onto a recording side and tracking-controlled to search and follow the tracks of the recording side.
  • the data restoration part 40 includes a high frequency amplifier 42, a wave former and decoder 44, and an error detection and correction part 46.
  • the high frequency amplifier 42 amplifies the high frequency signal that is input to the data restoration part 40 and the amplified signal is restored into a digital signal through the wave former and decoder 44.
  • the error detection and correction part 46 an operation for detecting errors included in the decoded digital signal is implemented and, then, the detected errors are corrected and yielded as a track address and data.
  • the data process part 50 processes the data provided by the data restoration part 40 in a predetermined data-processing way and results in reproducing audio signals or audio-video ones.
  • the servo part 60 includes a spindle servo 62, a focusing servo 64, and a tracking servo 66.
  • the spindle servo 62 servo-controls the spindle motor 20.
  • the focusing servo 64 servo-controls a focusing actuator which actuates up and down an object lens installed in the optical pick-up to control the focusing of the optical beam onto a recording side.
  • the tracking servo 66 servo-controls a coarse adjusting motor that moves the optical pick-up 30 toward a radius of the optical pick-up and a tracking actuator that actuates the object lens left and right for the optical beam to be focused precisely onto a target track.
  • the input part 70 responds to the signals of a remote controller or of a key and generates a command signal that is the same as a selection signal of a recorded program on the optical disc.
  • the memory 80 consists of a semiconductor such as a read only memory
  • ROM read only memory
  • RAM random access memory
  • TXn, TXm location data
  • the control part 90 includes a microcomputer or a microprocessor and its peripheral circuits.
  • One aspect of the control part 90 is that it controls these elements to be provided by the data restoration part with a table of content (TOC) information reproduced from the TOC area of the optical disc 10 and that it obtains position information about the target track of the selected program with reference to the provided TOC information.
  • the TOC contains this track address information that corresponds to the starting positions of various programs recorded on the optical disc 10. Accordingly, when searching a track, the control part 90 sets position information of the selected target track with reference to the reproduced TOC and moves the optical pick-up toward a radius through the tracking servo 66 in the servo part 60.
  • control part 90 compares position information of the predetermined target track with a track address in which the current optical beam obtained by the data restoration part 40 is located, and controls the optical pick-up to move toward reducing the difference. If the optical beam reaches the target track, this searching operation ends.
  • FIG. 2 depicts a relationship of the target and virtual tracks on an optical disc during the searching operation of the optical disc reproduction apparatus according to the present invention.
  • TP target track
  • Position information of one or more virtual tracks for example a first and a second virtual tracks (TXn and TYm respectively), is stored in the memory 80 in advance, and the value of the original target track is replaced with the values of those virtual tracks acting as new target tracks in the event that it is difficult to search target tracks due to surface defects on the disc. Further, the positions of the searched virtual tracks are reset as altered target tracks with which the reproduction of the selected program begins.
  • Position information of the first virtual track (TXn) is set toward the outer- radius over the target track (TP) by a predetermined distance. This means that, to find a searchable adjacent track, position information of the first virtual track (TXn) is determined by escaping the defect area 100, with jumping every predetermined track.
  • Position information of the second virtual track (TYm) is set toward the inner-radius by a predetermined distance, for example by a distance of every track, to find a track that is searchable and close to the TP from the searched first virtual track (TXn).
  • FIG. 3 illustrates a flow chart to explain the first embodiment of a method for searching a track with an optical disc reproduction apparatus of the present invention.
  • this reproduction apparatus is set onto a tray
  • the optical disc 10 is loaded by a loading mechanism (302).
  • the loaded optical disc 10 is rotated by the spindle motor 20 and, from a lead-in-area of the optical disc 10, TOC information is read out to be provided to the control part 90 (304).
  • position information of the target track (TP) corresponding to a starting position of the selected program is set by referring to the TOC (306, 308) in the control part 90. After this, the search operation of the selected target track is implemented in the control part (310).
  • control part 90 compares track addresses read out during the optical beam's movement toward the outer-radius with position information of the target track which was set previously to check the completion of the search operation.
  • the control part 90 continuously checks whether the predetermined search time (tl) has elapsed (314).
  • the reproduction operation can be implemented by reading the program data from the searched target track (TP) (342).
  • step 314 the control part 90 concludes that the search of the target track (TP) is not possible, and takes position information (TX1) of the first virtual target track from the memory 80 to assign the target track (TP) with the TX1 (316).
  • the search for the TX1 is executed (318), and its completion is checked (320). If the completion of the search is not successfully checked, it is checked whether or not the predetermined search time (t2) has elapsed (322). If not, the lapse of the search time (t2), the step 318 should be carried out. In step 322, if the search of the TX1 is not completed within the search time
  • step 316 the TX1 is changed to the TX2 (324) and step 316 is initiated. If the track search is performed by resetting the TX2 in step 316 and the search of TX2 is completed in step 320, then it can be regarded as that the currently searching track is out of the defect area 100. However, if the TX2 is not searched, the same searching operation as above that position information of the first virtual track is changed to next one should be repeated until the track search is completed successfully.
  • step 320 If the search of the TX2 is achieved in step 320, then a new search for the unsearchable position is implemented with moving the optical beam reversely, namely, toward the inner-radius.
  • the control part 90 changes the TX2 with the TY1 (326) by taking position information of the second virtual target track (TY2) from the memory 80.
  • the newly reset TY1 is searched (328) and the completion of the search is checked (330). If the completion of the search is checked in step 330, it is checked whether a preset search time (t3) has elapsed (334) or not. If not, the step 328 is implemented.
  • step 330 If the TY2 is searched by the search time (t3) in step 330, the TY1 is changed to TY2 (332) and step 326 is executed. In step 326, a track search operation is performed by resetting the TY2. If the TY2 is completed in step 330, then the TY2 is altered with the TY3 in step 332 and the search operation is repeatedly implemented. If the search of the TY3 fails to be completed within the search time (t3) in step 334, then it can be understood that the optical beam has moved into the defect area 100. Unlike the above case, if the TY3 is sought, the same searching operation as above that changes position information of the second virtual track with next one should be repeated until the track search fails.
  • step 334 If the TY3 is not sought within the search time (t3) in step 334, the previously found TY2 is taken as an amended target track (ATP) (336) and then the ATP becomes a target for the search. In step 338, it is checked whether the ATP is searched or not (340), and, in the event of the completion of the search for the ATP, the program data selected from the ATP is reproduced (342).
  • ATP amended target track
  • a search operation passing a searchable adjacent track toward the outer-radius from a current beam position is primarily performed by a coarse search. Then, the next step of the search operation to seek an unsearchable location is performed in a reverse direction, that is, toward an inner-radius from the position determined by the coarse search, and, just before the discovery of an unsearchable position, the position of a searchable track is taken as an amended target position.
  • FIG. 4 a flow chart explains the second embodiment according to a method for searching a track, which employs an optical disc reproduction apparatus of the present invention. Comparing the first embodiment with the second one, as every step is identical, it is numbered as same as that of FIG. 3, except for step 315 that the searchability of the target track corresponding to the starting point of the selected program is not decided by the elapse of time but by the number of trials for the search, and that it treats the situation where the target track cannot be searched by more than a predetermined number of trials as an unsearchable state.

Landscapes

  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)

Abstract

L'invention se rapporte à un appareil de lecture de disque optique et à un procédé de recherche de piste. Un capteur optique se déplace suivant un rayon du disque optique, émet un faisceau optique dans la zone d'enregistrement des informations et transforme le faisceau optique réfléchi par le disque optique en un signal de sortie haute fréquence. Une unité de restauration des données permet la restauration d'une adresse de piste et de données par le signal haute fréquence délivré par le capteur optique. Un servomécanisme de guidage commande un servomécanisme de guidage du capteur optique. Des informations de position relatives à au moins une des première et seconde pistes cibles virtuelles sont stockées dans une mémoire. Une section d'entrée et une section de commande sélectionne un programme enregistré sur le disque optique. En outre, un organe de commande commande le servomécanisme de guidage de façon à déplacer le faisceau optique dans le but de réduire la différence entre une adresse de piste obtenue à partir de la mémoire et une adresse de piste cible sélectionnée par la section d'entrée. Dans l'éventualité où il est impossible de fournir l'adresse de piste cible à partir de la section de restauration des données, l'organe de commande commande au servomécanisme de guidage de lire les informations relatives au programme sélectionné en prenant la piste la plus proche qu'il est possible d'atteindre en direction d'une piste externe après avoir dépassé la piste cible, vers la piste originale, en tant que nouvelle piste cible virtuelle, par référence à des informations de position relatives à au moins une des première et seconde pistes cibles virtuelles.
PCT/KR1998/000278 1997-09-26 1998-09-11 Appareil de lecture de disque optique et procede de recherche de piste WO1999017280A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
KR1019970049167A KR100256644B1 (ko) 1997-09-26 1997-09-26 광디스크 플레이어의 트랙 탐색 방법
KR1019970049142A KR19990026828A (ko) 1997-09-26 1997-09-26 광디스크 플레이어의 트랙 탐색 방법
KR1997/49142 1997-09-26
KR1997/49167 1997-09-26

Publications (1)

Publication Number Publication Date
WO1999017280A1 true WO1999017280A1 (fr) 1999-04-08

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ID=26633097

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR1998/000278 WO1999017280A1 (fr) 1997-09-26 1998-09-11 Appareil de lecture de disque optique et procede de recherche de piste

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1492097A3 (fr) * 2003-06-27 2007-10-31 Teac Corporation Disque optique de haute densité et dispositif de disque optique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0380323A1 (fr) * 1989-01-25 1990-08-01 Sony Corporation Disque pouvant avoir une écriture optique avec information numérique et appareil d'enregistrement à cet effet
EP0482645A2 (fr) * 1990-10-25 1992-04-29 Pioneer Electronic Corporation Système d'enregistrement optique
WO1994014159A1 (fr) * 1992-12-17 1994-06-23 Samsung Electronics Co., Ltd. Support d'enregistrement a disque, et procede et appareil de reproduction associes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0380323A1 (fr) * 1989-01-25 1990-08-01 Sony Corporation Disque pouvant avoir une écriture optique avec information numérique et appareil d'enregistrement à cet effet
EP0482645A2 (fr) * 1990-10-25 1992-04-29 Pioneer Electronic Corporation Système d'enregistrement optique
WO1994014159A1 (fr) * 1992-12-17 1994-06-23 Samsung Electronics Co., Ltd. Support d'enregistrement a disque, et procede et appareil de reproduction associes

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1492097A3 (fr) * 2003-06-27 2007-10-31 Teac Corporation Disque optique de haute densité et dispositif de disque optique

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