US20030123354A1 - Information disk recording/reproducing device, and method for detecting vibration of information disk recording/reproducing device - Google Patents

Information disk recording/reproducing device, and method for detecting vibration of information disk recording/reproducing device Download PDF

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Publication number
US20030123354A1
US20030123354A1 US10/148,808 US14880802A US2003123354A1 US 20030123354 A1 US20030123354 A1 US 20030123354A1 US 14880802 A US14880802 A US 14880802A US 2003123354 A1 US2003123354 A1 US 2003123354A1
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United States
Prior art keywords
information
disc
track
speed
count
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Abandoned
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US10/148,808
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English (en)
Inventor
Yorio Takahashi
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Panasonic Holdings Corp
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Individual
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Assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. reassignment MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: TAKAHASHI, YORIO
Publication of US20030123354A1 publication Critical patent/US20030123354A1/en
Priority to US11/249,309 priority Critical patent/US7161884B2/en
Priority to US11/249,307 priority patent/US7215621B2/en
Priority to US11/249,510 priority patent/US20060028944A1/en
Priority to US11/249,314 priority patent/US20060044963A1/en
Abandoned legal-status Critical Current

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/02—Control of operating function, e.g. switching from recording to reproducing
    • 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
    • G11B7/095—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 specially adapted for discs, e.g. for compensation of eccentricity or wobble
    • G11B7/0953—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 specially adapted for discs, e.g. for compensation of eccentricity or wobble to compensate for eccentricity of the disc or disc tracks
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/02—Control of operating function, e.g. switching from recording to reproducing
    • G11B19/06—Control of operating function, e.g. switching from recording to reproducing by counting or timing of machine operations
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/02—Control of operating function, e.g. switching from recording to reproducing
    • G11B19/12—Control of operating function, e.g. switching from recording to reproducing by sensing distinguishing features of or on records, e.g. diameter end mark
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/20—Driving; Starting; Stopping; Control thereof
    • G11B19/28—Speed controlling, regulating, or indicating
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
    • G11B20/10—Digital recording or reproducing
    • 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
    • G11B2007/0006—Recording, reproducing or erasing systems characterised by the structure or type of the carrier adapted for scanning different types of carrier, e.g. CD & DVD
    • 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
    • G11B7/0946—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 specially adapted for operation during external perturbations not related to the carrier or servo beam, e.g. vibration

Definitions

  • the present invention relates to an information disc recording/playback apparatus having a vibration measurement means for measuring vibrations caused by an eccentricity of a disc, and a vibration detection method for the information disc recording/playback apparatus. More particularly, the invention relates to an information disc recording/playback apparatus having a construction for performing vibration detection using track counting.
  • optical disc playback apparatuses have made a remarkable increase in the recording/playback speed.
  • the optical disc playback apparatuses have achieved the increase in the playback speed by increasing the rotation speed of optical discs.
  • FIG. 8 is a block diagram illustrating a conventional optical disc playback apparatus 800 having a structure for detecting vibration with an acceleration sensor.
  • reference numeral 801 denotes a base
  • numeral 802 denotes a disc motor mounted on the base 801
  • numeral 803 denotes an insulator supporting the base 801
  • numeral 804 denotes a disc mounted on the disc motor 802
  • numeral 805 denotes an acceleration sensor mounted on the base 801
  • numeral 806 denotes a measurement unit for measuring the amount of eccentricity on the basis of the output of the acceleration sensor 805 .
  • the vibration of the base 801 is converted into an electric signal by the acceleration sensor 805 mounted on the base 801 .
  • the measurement unit 806 measures the vibration amplitude of the base 801 on the basis of the electric signal obtained by the acceleration sensor 805 .
  • the measured vibration amplitude is compared with a preset threshold value, thereby determining a maximum rotation speed of the disc mounted on the optical disc device.
  • FIG. 9 is a block diagram illustrating a conventional optical disc playback apparatus 900 performing vibration detection using track counting, which is disclosed in Japanese Published Patent Application No. 2000-113581.
  • the same reference numerals as those shown in FIG. 8 denote the same or corresponding parts
  • reference numeral 901 denotes an optical head which is suspended over the base 801 via an elastic member 902 .
  • Reference numeral 903 denotes a light beam applied to the disc 804 from the optical head 901
  • numeral 904 denotes information recording tracks which are concentrically or spirally formed on an information recording surface 804 A of the disc 804 at a constant pitch.
  • reference numeral 905 denotes a track cross detection unit for generating track cross pulses and a cross direction signal from signals which are reproduced when the light beam 903 crosses the information recording tracks 904 ;
  • numeral 906 denotes a count unit for counting the track cross pulses;
  • numeral 907 denotes a measurement unit for determining the amount of eccentricity from the counting result of the count unit 906 ;
  • numeral 908 denotes a motor control unit for controlling the rpm of the disc motor 802 , and outputting rotation angle information to the measurement unit 907 .
  • the distance between the optical head 901 and the disc 804 is kept constant so that the focus of the light beam 903 is positioned on the information recording surface 804 A of the disc 804 .
  • the position of the optical head 901 relative to the disc 804 in the direction of the radius of the disc 804 (the direction indicated by an arrow R) has vibration characteristics represented by a natural frequency of vibration foA which is determined by the spring constant of the elastic member 902 comprising a material such as metal, resin, or rubber, and the mass of the optical head 901 .
  • the base 801 is supported by the insulator 803 comprising a material such as metal, resin, or rubber.
  • the insulator 803 comprising a material such as metal, resin, or rubber.
  • the base 801 vibrates on the basis of vibration characteristics represented by a natural frequency of vibration foM which is determined by the total mass of the constituents including the base 801 , the optical head 901 mounted on the base 801 , the disc motor 802 , and the disc 804 , and the spring constant of the insulator 803 .
  • the motor control unit 908 rotates the disc motor 802 at a first rpm that is sufficiently lower than the natural frequency of vibration foA.
  • the optical disc 804 mounted on the disc motor 802 is rotated at the first rpm.
  • the optical head 901 vibrates together with the base 801 .
  • the relative position between the optical head 901 and the optical disc 804 hardly changes. Therefore, at the first rpm that is sufficiently lower than the natural frequency of vibration foA, the light beam 903 crosses a number of information recording tracks 904 equivalent to the amount of eccentricity of the information recording tracks 904 .
  • the light beam 903 generates track crosses as many as the information recording tracks 904 the light beam 903 has crossed.
  • the track cross detection unit 905 detects the track crosses corresponding to the information recording tracks 904 the light beam 903 has crossed, on the basis of the playback signals of the optical head 901 , and generates track cross pulses corresponding to the detected track crosses.
  • the track cross detection unit 905 outputs the generated track cross pulses to the count unit 906 .
  • the count unit 906 counts the track cross pulses for one rotation of the disc 804 on the basis of the rotation angle information from the motor control unit 908 .
  • the measurement unit 907 stores a count result N1 of the track cross pulses for one rotation of the disc 804 , which are counted by the count unit 906 .
  • the motor control unit 908 rotates the disc motor 802 at a second rpm that is higher than the natural frequency of vibration foA and lower than the natural frequency of vibration foM. Then, a centrifugal force is generated in the disc 804 due to the eccentricity of the disc 804 .
  • the base 801 vibrates at an amplitude that is determined by the amount of eccentricity of the disc 804 , the total mass of the base 801 and the components mounted on the base 801 , and the spring constant of the insulator 803 .
  • the disc motor 802 rotates at the second rpm that is higher than the natural frequency of vibration foA and lower than the natural frequency of vibration foM, only the base 801 , disc motor 802 , and disc 804 vibrate together while the optical head 901 is in the static state. Therefore, the relative displacement between the disc 804 and the optical head 901 becomes equal to the vibration displacement of the base 801 .
  • the light beam 903 generates track crosses as many as the tracks equivalent to an amount in which the vibration amplitude of the base 801 is added to the amount of eccentricity of the information recording tracks 904 .
  • the track cross detection unit 905 detects the track crosses as many as the tracks equivalent to the amount comprising the amount of eccentricity of the information recording tracks 904 and the vibration amplitude of the base 801 , and generates track cross pulses as may as the tracks equivalent to the amount comprising the amount of eccentricity of the information recording tracks 904 and the vibration amplitude of the base 801 .
  • the track cross detection unit 905 outputs the generated track cross pulses to the count unit 906 .
  • the count unit 906 counts the track cross pulses for one rotation of the disc 804 , on the basis of the rotation angle information from the motor control unit 908 .
  • the measurement unit 907 subtracts the count result N1 from a count result N2 obtained by the count unit 906 , thereby obtaining the vibration amplitude of the base 801 alone.
  • the measured vibration amplitude is compared with a threshold value which is prepared for each disc type, thereby determining a maximum rotation speed of the disc loaded on the optical disc device.
  • an optical disc device disclosed is provided with a PLL circuit for outputting a control frequency according to the moving speed of an optical head when the optical head is moved to a target track position on the surface of an optical disc by a thread motor; an F/V conversion circuit for converting the control frequency into a voltage; and a ripple detection filter for attenuating a noise component included in a ripple signal from an envelope detection circuit, whose filter characteristic is changed according to the voltage from the F/V conversion circuit.
  • the cut-off frequency of the filter is varied according to the moving speed of the optical head.
  • threshold setting varies depending on the loading condition or the like of the disc to be used on the disc device, a large amount of data must be measured, and the amount of data further increases according to the number of disc types, whereby enormous time is required.
  • the present invention is made to solve the above-described problems and has for its object to provide an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus, which can measure vibration amplitudes with reduced cost and space without using an acceleration sensor, perform vibration detection using a single threshold value that is independent of the disc type, and perform accurate vibration detection even when direction detection is difficult.
  • an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track pitch detection means for detecting the track pitch of the information disc from the information disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a count means for counting track cross pulses that are detected by the track cross detection means, and outputting the count; and a control means for determining a maximum rotation speed that is lower than an allowable vibration amplitude of the information disc recording/playback apparatus on the basis of the count and the track pitch, or determining a maximum rotation speed that is lower than an allowable vibration speed or vibration acceleration speed of the information
  • the information disc recording/playback apparatus defined in claim 1 further comprises: a track cross direction detection means for detecting a track cross direction indicating the direction in which the reading means crosses the information tracks; a rotation angle detection means for outputting rotation angle information of the disc rotation means; and the count means for counting the track cross pulses with signs, which are detected by the track cross detection means, on the basis of the result of the detection by the track cross direction detection means, and the rotation angle information outputted from the rotation angle detection means.
  • the information disc recording/playback apparatus defined in claim 1 further comprises: a track cross direction detection means for detecting a track cross direction indicating the direction in which the reading means crosses the information tracks; a track cross speed detection means for detecting the frequency of the track cross pulses; a rotation angle detection means for outputting rotation angle information of the disc rotation means; and the count means for counting the track cross pulses with signs, which are detected by the track cross detection means, on the basis of the result of the detection by the track cross direction detection means and the rotation angle information outputted from the rotation angle detection means, while detecting the track cross direction by the track cross direction detection means when the result of the detection by the track cross speed detection means indicates that the track cross speed is lower than a predetermined value, and counting the track cross pulses with signs, without detecting the track cross direction by the track cross direction detection means, on the basis of the track cross direction that has just previously been detected by the track cross direction detection means, when the result of the detection by the track cross speed detection means indicates that the track cross cross
  • an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track pitch detection means for detecting the track pitch of the information disc from the information disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a track cross direction detection means for detecting a track cross direction indicating the direction in which the reading means crosses the information tracks; a rotation angle detection means for outputting rotation angle information of the disc rotation means, which is divided into n areas for one rotation; a zero cross area detection means for detecting two areas where the track cross speed has a lowest value, from among the n areas; a count means for counting
  • an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track pitch detection means for detecting the track pitch of the information disc from the information disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a track cross direction detection means for detecting a track cross direction indicating the direction in which the reading means crosses the information tracks; a rotation angle detection means for outputting rotation angle information of the disc rotation means, which is divided into n areas for one rotation; a zero cross area detection means for detecting two areas where the track cross speed has a lowest value, from among the n areas; a count means including
  • the rotation angle detection-means divides the rotation angle information of the disc rotation means into six areas for each rotation, and outputs the divided information; and the zero cross area detection means detects, as zero cross areas, an area where the count of the count means has the smallest value, and an area on a diagonal line with respect to the area.
  • an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track pitch detection means for detecting the track pitch of the information disc from the information disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a count means for counting track cross pulses that are detected by the track cross detection means, and outputting the count; and a control means for, using, as the count, a difference between the track cross count that is obtained when the information disc is rotated at a first rotation speed and at least one rotation speed that is higher than the first rotation speed, and a count that is measured with the at least one rotation speed higher than
  • the first rotation speed is a sufficiently low speed at which no vibration occurs between the information disc and the reading means, and the track cross pulses due to the eccentricities of the information disc and the disc rotation means are counted.
  • the count means counts the track cross pulses at the first rotation speed for a predetermined number of times, and counts the track cross pulses with the at least one rotation speed that is higher than the first rotation speed, for the predetermined number of times; and the control means employs, as the count, an average of counts for more than one time, which are selected from among the counts obtained by the above-described repetition, or a value in proportion to the average.
  • the rotation angle detection means outputs the rotation angle information of the disc rotation means, which is divided into six areas for one rotation, and when a difference between the track cross count measured at the first rotation speed with each of the six-divided rotation angles, and the track cross count which is measured with the at least one rotation speed higher than the first rotation speed is as follows:
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • ( Formula ⁇ ⁇ 12 ) vibration ⁇ ⁇ amount ⁇ ⁇ 2 ⁇ [ n ] 2 3 ⁇
  • the rotation angle detection means divides the rotation angle information of the disc rotation means into six areas for one rotation, and outputs the divided rotation angle information; and when a difference between the track cross count which is obtained at the first rotation speed for each of the six-divided rotation angles, and the track cross count which is obtained with the at least one rotation speed higher than the first rotation speed is represented by
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • ( Formula ⁇ ⁇ 14 ) vibration ⁇ ⁇ speed ⁇ ⁇ 2 ⁇ [ n ] 2
  • the rotation angle detection means divides the rotation angle information of the disc rotation means into six areas for one rotation, and outputs the divided rotation angle information; and when a difference between the track cross amount which is measured at the first rotation speed for each of the six-divided rotation angles, and the track cross amount which is measured with the at least one rotation speed higher than the first rotation speed is represented by
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • the track pitch detection means detects the type of the loaded information disc, and selects a track pitch corresponding to the detected disc type, with reference to a table in which standard track pitches corresponding to the respective types of the information discs are described.
  • the information disc recording/playback apparatus as defined in claim 1 further comprises: a move distance detection means for detecting the distance by which the reading means moves; and the track pitch detection means for making the reading means move for a predetermined period of time or by a predetermined distance when the information disc is loaded, counting the number of tracks the reading means crosses while it is moving, and detecting the track pitch on the basis of the move distance and the track cross count.
  • the information recording/playback apparatus defined in claim 1 further comprises: a linear speed detection means for detecting the linear speed of the information disc; a a playback speed detection means for detecting the current playback speed of the information disc; and the track pitch detection means for calculating the track pitch of the information disc, on the basis of the detected type of the information disc, the linear speed of the information disc detected by the linear speed detection means, the playback speed detected at a predetermined rotation speed and a predetermined address, the predetermined rotation speed, the predetermined address, the innermost radius of data area which is unique to the detected type of the disc, and the data rate when the disc is played at the predetermined playback speed which is unique to the type of the disc.
  • an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track cross detection means for generating track cross pulses on the basis of playback signals that are generated when the reading means crosses the information tracks; a variable filter means for preventing counting of pulses whose widths are narrower than a set value, among the track cross pulses; a count means for counting the pulses outputted from the variable filter means; and a control means for determining a maximum rotation speed that is lower than an allowable number of track crosses of the information disc recording/playback apparatus on the basis of the count, or determining a maximum rotation speed that is lower than an allowable track cross speed or track cross acceleration of the information disc recording/playback apparatus on the basis of
  • the information disc recording/playback apparatus defined in claim 19 further comprises: a track cross direction detection means for detecting the track cross direction which indicates the direction in which the reading means crosses the information tracks; a rotation angle detection means for outputting rotation angle information of the disc rotation means; and the count means for counting the track cross pulses with signs, which are detected by the track cross detection means, on the basis of the result of the detection by the track cross direction detection means and the rotation angle information outputted from the rotation angle detection means.
  • an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track cross detection means for generating track cross pulses on the basis of playback signals that are generated when the reading means crosses the information tracks; a variable filter means for preventing counting of pulses whose widths are narrower than a set value, among the track cross pulses; a track cross direction detection means for detecting the track cross direction which indicates the direction in which the reading means crosses the information tracks; a rotation angle detection means for outputting rotation angle information of the disc rotation means; a count means including a first count means for counting the track cross pulses with signs, which are outputted from the filter means, on the basis of the result of the detection by the track cross direction detection means and
  • the count means obtains the count of the first count means when the value of the variable filter is set on the basis of the count and the current rotation speed, the drive means is disabled, and the information disc loaded on the disc rotation means is rotated at a predetermined rotation speed, and repeats the process of obtaining the count of the first count means when the information disc is rotated at the predetermined speed, for a required number of times, thereby obtaining the counts for more than one rotation.
  • the rotation angle detection means divides the rotation angle information of the disc rotation means into six areas for one rotation and outputs the divided rotation angle information
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • the rotation speed of the disc rotation means is Vrpm[rpm]
  • ( Formula ⁇ ⁇ 19 ) maximum ⁇ ⁇ track ⁇ ⁇ cross ⁇ ⁇ speed ⁇ ⁇ 2 ⁇ [ n ] 2 ⁇ ⁇ ⁇ V rpm 60 ⁇ 2 3 ⁇
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • the rotation speed of the disc rotation means is Vrpm[rpm]
  • the control means when setting the maximum rotation speed of the information disc recording/playback apparatus, employs, as the count, a difference between the track cross count that is obtained when the information disc is rotated at a first rotation speed and at least one rotation speed that is higher than the first rotation speed, and the count obtained with the at least one rotation speed that is higher than the first rotation speed.
  • the track cross count is the number of track crosses which is calculated on the basis of an average of counts corresponding to more than one rotation, which counts are selected from among the counts obtained by the repetition.
  • an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a pulse width storage means for holding the pulse width of a just-previous track cross signal; a filter means for comparing the pulse width of the just-previous track cross signal with the pulse width of the current track cross signal, and preventing the current track cross signal from being outputted when the current track cross signal is reduced by a predetermined value or more; a count means for counting the pulses which are outputted from the variable filter means; and a control means for determining a maximum rotation speed that is lower than an allowable number of track crosses of
  • the information disc recording/playback apparatus in the information disc recording/playback apparatus defined in claim 29, the information disc recording/playback apparatus is able to record or play two or more kinds of information discs having different track pitches; and setting of the maximum rotation speed of the information disc recording/playback apparatus is performed by detecting the track pitch of the information disc, and determining a maximum rotation speed that is lower than an allowable vibration amplitude of the information disc recording/playback apparatus on the basis of the count and the track pitch, or determining a maximum rotation speed that is lower than an allowable vibration speed or vibration acceleration of the information disc recording/playback apparatus on the basis of the count, the track pitch, and the current disc rotation speed.
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which method comprises: a step of detecting the track pitch of the information disc; a step of counting track cross pulses on the basis of playback signals which are generated when the information disc fixedly loaded on the apparatus is rotated and a reading unit crosses the information tracks on the information disc, thereby obtaining a count; a step of determining a maximum rotation speed that is lower than an allowable vibration amplitude of the information disc recording/playback apparatus, on the basis of the obtained count and the track pitch; and a step of determining a maximum rotation speed that is lower than an allowable vibration speed or vibration acceleration of the information disc recording/playback apparatus, on the basis of the count, the track pitch, and the current disc rotation speed.
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which method comprises: a step of detecting the track pitch of the information disc; a step of detecting the track cross direction indicating the direction in which a reading means crosses the information tracks; a step of outputting rotation angle information of the information disc, which is divided into n areas for one rotation; a step of detecting two areas wherein the track cross speed has the lowest value, from among the n-divided areas; a step of counting track cross pulses, which are based on playback signals that are generated when the information disc fixedly loaded onto the apparatus is rotated and the reading means crosses the information tracks on the information disc, such that the track cross pulses with signs are counted while detecting the track cross direction in an area where the track cross speed has the lowest value, on the basis of the detected track cross direction and the rotation angle information;
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which method comprises: a step of detecting the track pitch of the information disc; a step of detecting the track cross direction indicating the direction in which a reading means crosses the information tracks; a step of outputting rotation angle information of the information disc, which is divided into n areas for one rotation; a step of detecting two areas wherein the track cross speed has the lowest value, from among the n-divided areas; a step of obtaining a first count on the basis of playback signals which are generated when the information disc fixedly loaded onto the apparatus is rotated and the reading means crosses the information tracks on the information disc; a step of obtaining a second count in which a sign is added to the count, on the basis of the track cross direction which has just previously been detected, when the information disc is rotated; a step of selecting
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which method comprises: a step of detecting the track pitch of the information disc; a step of counting track cross pulses on the basis of playback signals which are generated when the information disc fixedly loaded onto the apparatus is rotated at a first rotation speed and a reading unit crosses the information tracks on the information disc, thereby obtaining a count; a step of calculating a difference between a track cross count which is obtained when the information disc is rotated with at least one rotation speed that is higher than the first rotation speed, and a count which is obtained when the information disc is rotated at the first rotation speed, thereby obtaining a difference count; a step of determining a maximum rotation speed that is lower than an allowable vibration amplitude of the information disc recording/playback apparatus, on the basis of the obtained difference count and the track pitch; and
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which method comprises: a step of counting track cross pulses on the basis of playback signals which are generated when the information disc fixedly loaded on the apparatus is rotated and a reading unit crosses the information tracks on the information disc, thereby obtaining a count; a step of comparing the widths of the detected track pulses with a predetermined value, and invalidating the counts of track pulses whose widths are shorter than the predetermined value; a step of determining a maximum rotation speed that is lower than an allowable number of track crosses of the information disc recording/playback apparatus, on the basis of the count; and a step of determining a maximum rotation speed that is lower than an allowable track cross speed or track cross acceleration, on the basis of the count and the current disc rotation speed.
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which method comprises: a step of counting track cross pulses on the basis of playback signals which are generated when the information disc fixedly loaded on the apparatus is rotated and a reading unit crosses the information tracks on the information disc, thereby obtaining a count; a step of detecting the track cross direction indicating the direction in which the reading means crosses the information tracks; a step of outputting rotation angle information of the information disc; a step of comparing a set pulse width with the pulse width of the current track cross pulse, and invalidating the count of the current track cross pulse when its pulse width is decreased by a predetermined value or more; a first count step of counting the track cross pulses with signs, whose widths are not decreased by the predetermined value or more, on the basis of the track cross direction and the rotation angle information; a second count step of counting the track cross pulses whose width
  • a vibration detection method for an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which method comprises: a step of counting track cross pulses on the basis of playback signals which are generated when the information disc fixedly loaded on the apparatus is rotated and a reading unit crosses the information tracks on the information disc, thereby obtaining a count; a step of storing the pulse width of a track cross pulse which has just previously been detected; a step of comparing the stored track cross pulse width with the pulse width of the current track cross pulse, and invalidating the count of the current track cross pulse when its pulse width is decreased by a predetermined value or more; a step of determining a maximum rotation speed that is lower than an allowable number of track crosses of the information disc recording/playback apparatus, on the basis of the count; and a step of determining a maximum rotation speed that is lower than an allowable track cross speed or track cross acceleration, on the basis of the count and the
  • an information disc recording/playback apparatus capable of recording or playing at least two kinds of information discs having different track pitches, on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track pitch detection means for detecting the track pitch of the information disc from the information disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a count means for counting track cross pulses that are detected by the track cross detection means, and outputting the count; and a control means for determining a maximum rotation speed that is lower than an allowable vibration amplitude of the information disc recording/playback apparatus on the basis of the count and the
  • the vibration amplitude, or vibration speed, or vibration acceleration is evaluated considering the track pitch of the disc, and the maximum rotation speed lower than the allowable vibration amplitude, or vibration speed, or vibration acceleration of the information disc recording/playback apparatus is determined, whereby vibration detection can be carried out using a single threshold value, regardless of the type of the information disc.
  • an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track cross detection means for generating track cross pulses on the basis of playback signals that are generated when the reading means crosses the information tracks; a variable filter means for preventing counting of pulses whose widths are narrower than a set value, among the track cross pulses; a count means for counting the pulses outputted from the variable filter means; and a control means for determining a maximum rotation speed that is lower than an allowable number of track crosses of the information disc recording/playback apparatus on the basis of the count, or determining a maximum rotation speed that is
  • an information disc recording/playback apparatus capable of recording or playing an information disc on which information recording tracks are formed spirally or concentrically, which apparatus comprises: a disc rotation means for rotating the information disc at a predetermined speed; a reading means for reading an information signal from the disc; a drive means for driving the reading means in the direction of the radius of the disc; a track cross detection means for generating track cross signals on the basis of playback signals that are generated when the reading means crosses the information tracks; a pulse width storage means for holding the pulse width of a just-previous track cross signal; a filter means for comparing the pulse width of the just-previous track cross signal with the pulse width of the current track cross signal, and preventing the current track cross signal from being outputted when the current track cross signal is reduced by a predetermined value or more; a count means for counting the pulses which are outputted from the variable filter means; and a control means for determining a maximum rotation speed that is
  • this pulse is judged as one caused by false detection due to noise and is not counted, whereby track counting most suitable for vibration detection can be accurately carried out at all times, without requiring time for excess measurement.
  • FIG. 1 is a block diagram illustrating the construction of a DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to a first or fourth embodiment of the invention are applied to the DVD-ROM player.
  • FIG. 2 is a block diagram illustrating the construction of a DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to a second embodiment of the invention are applied to the DVD-ROM player.
  • FIG. 3 is a block diagram illustrating the construction of a DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to a third embodiment of the invention are applied to the DVD-ROM player.
  • FIG. 4 is a block diagram illustrating the construction of a DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to a fifth embodiment of the invention are applied to the DVD-ROM player.
  • FIG. 5 is a block diagram illustrating the construction of a DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to a sixth, seventh, or eighth embodiment of the invention are applied to the DVD-ROM player.
  • FIG. 6 is a diagram illustrating a graph showing the amount of displacement of the count at every rotation angle, which displacement is caused by vibration or eccentricity, when the present invention is applied to the DVD-ROM player.
  • FIG. 7 is a block diagram illustrating the construction of a DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to a ninth embodiment of the invention are applied to the DVD-ROM player.
  • FIG. 8 is a block diagram illustrating the construction of a conventional optical disc playback apparatus which performs vibration detection using an acceleration sensor.
  • FIG. 9 is a block diagram illustrating the construction of a conventional optical disc playback apparatus which performs vibration detection using track counting.
  • FIG. 10 is a block diagram illustrating the construction of another DVD-ROM player in the case where an information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to the fifth embodiment of the invention are applied to the DVD-ROM player.
  • a DVD-ROM player 101 is able to play various kinds of optical discs 102 .
  • the DVD-ROM player 101 according to this first embodiment is able to play the following discs: CD-ROM (CD-ROM, CD-R, CD-RW), DVD-ROM (DVD-5, DVD-9, DVD-R4.7G), and DVD-R3.9G, and the standard track pitches of these discs are as follows: CD-ROM 1.6 ⁇ m DVD-ROM 0.74 ⁇ m DVD-R3.9G 0.80 ⁇ m
  • Reference numeral 103 denotes a disc rotation means for rotating the optical disc 102 mounted on the DVD-ROM player 101 at a predetermined rpm.
  • Reference numeral 104 denotes a reading means for reading an information signal from the optical disc 102 .
  • the reading means 104 comprises, for example, a laser emission element 105 for emitting two laser beams having different oscillation wavelengths, one for a CD-ROM and the other for a DVD-ROM; an objective lens 106 for converging the laser beams; and a two-element photodetector 107 , one for a CD-ROM and the other for a DVD-ROM.
  • the reading means 104 amplifies the outputs from the photodetector 107 , selects one of the output signals from the photodetector 107 according to the type of the optical disc 102 , generates a tracking error (TE) signal, a focus error (FE) signal, a playback signal (RF), an All Sum signal (AS), an RF envelope signal (RFENV) and the like, and outputs these signals.
  • TE tracking error
  • FE focus error
  • RF playback signal
  • AS All Sum signal
  • RFIDENV RF envelope signal
  • Reference numeral 108 denotes a conversion means for converting the playback signal outputted from the reading means 104 into digital data.
  • Reference numeral 109 denotes a drive means for driving the reading means 104 in the direction of the radius of the optical disc 102 .
  • This drive means 109 comprises, for example, a traverse drive means 110 for driving the whole reading means 104 in the direction of the radius of the optical disc, and a tracking actuator 111 for minutely driving the objective lens 106 included in the reading means 104 , in the direction of the radius of the optical disc.
  • Reference numeral 112 denotes a track cross detection means for generating track cross pulses on the basis of playback signals which are generated when the laser beam outputted from the reading means 104 crosses the tracks on the optical disc 102 .
  • Reference numeral 113 denotes a track cross direction detection means for detecting the direction along which the laser beam from the reading means 104 crosses the tracks on the optical disc.
  • the track cross detection means 112 or the track cross direction detection means 113 binarizes the tracking error signal outputted from the reading means 104 with a hysteresis comparator or a comparator to generate a track count signal TKC.
  • the track cross detection means 112 or the track cross direction detection means 113 generates a non-on track signal OFTR from the envelope of the RF signal, and generates a track cross direction signal according to the phase relationship between the TKC and the OFTR, or generates a track cross detection pulse by directly using the TKC or by latching the TKC with the OFTR.
  • Reference numeral 114 denotes a rotation angle detection means for detecting the rotation angle of the disc rotation means 103 .
  • the rotation angle detection means 114 generally utilizes a signal called an FG pulse that is generated from the output of a Hall element of a disc motor.
  • a method of performing more accurate rotation angle detection by frequency-dividing the FG pulse and a method of detecting the rotation speed at an arbitrarily resolution by providing the disc motor with a rotation speed detection means using an encoder.
  • Reference numeral 115 denotes a count means for counting the number of track crosses including the direction, on the basis of the output from the rotation angle detection means 105 , and the outputs from the track cross detection means 112 and the track cross direction detection means 113 .
  • the rotation angle can be detected at every 60 degrees, one rotation is divided into six areas, and a signed track count is obtained for each area.
  • Reference numeral 116 denotes a control means for processing the signals supplied from the conversion means 108 and the count means 115 , and controlling the disc rotation means 103 , the reading means 104 , the conversion means 108 , and the drive means 109 .
  • a step of detecting the track pitch of the optical disc 102 will be described taking, for example, a method of determining the type of the information disc and selecting a standard track pitch according to the information about the disc type.
  • the DVD-ROM player 101 can play plural types of information discs as described above, and the required light source and the method for generating a detection signal vary among the plural disc types. Therefore, initially, the type of the loaded disc is determined by various methods.
  • the loaded information disc is discriminated between a ROM (CD-ROM/R, DVD-ROM/R) disc and a rewritable disc (CD-RW), from the reflectivity of the information disc, using a CD laser, on the basis of the amplitude of a focus error signal obtained in focus search, and furthermore, it is discriminated between a DVD disc and a CD disc, from the degree of modulation of an RF signal, and thereafter, required light source and signal path are selected. Finally, it is checked whether TOC (TABLE OF CONTENTS) information can be read from the disc or not, and further, it is checked whether the disc type selected from the contents of the TOC information is correct or not. Then, the standard value of the track pitch according to the disc type is selected.
  • TOC TABLE OF CONTENTS
  • a step of obtaining the result of counting by the count means when the disc is rotated at the first rotation speed the drive means 104 is disabled, and the optical disc 102 is rotated at the first rotation speed by controlling the disc rotation means 103 . Then, the result of counting by the count means 115 is captured.
  • the rotation angle is detected at the rising and falling edges of the FG signal, and the counted number of track crosses is obtained at every rotation angle of 60 degrees.
  • the first rotation speed is set at a sufficiently low speed which does not cause vibration between the reading means 104 and the optical disc 102 , and the number of track crosses caused by only the eccentricity between the optical disc 102 and the disc rotation means 103 is measured.
  • the number of track crosses can be counted at every rotation angle of 60 degrees, as in the step of obtaining the count of the count means when the disc is rotated at the first rotation speed.
  • the count is obtained at the maximum rotation speed that is set for every disc type of the DVD-ROM player.
  • each of the counts obtained when the disc is rotated at the first speed and the at least one speed higher than the first speed is multiplied by the track pitch which is detected in the track pitch detection step, thereby obtaining data of the track cross amount.
  • data of the track cross amount at every 60 degrees is calculated from the number of tracks counted at every rotation angle of 60 degrees.
  • the track cross amount detected at the first rotation speed is compared with the track cross amount detected with the at least one rotation speed higher than the first speed, and the vibration amplitude of the information disc with respect to the reading means is calculated on the basis of a difference between the track cross amounts.
  • a difference between the track cross amount detected at the first rotation speed and the track cross amount detected at the maximum rotation speed is obtained at every rotation angle of 60 degrees, thereby calculating a track cross component due to the vibration.
  • the vibration amplitude is obtained on the assumption that the vibration is a sinusoidal wave.
  • a step of determining the maximum rotation speed comparison is carried out as to whether the previously obtained vibration amplitude is lower than a reference value or not. When it is lower than the reference value, the maximum rotation speed that is set for every disc type is employed, and when it is higher than the reference value, a rotation speed lower than the maximum rotation speed is employed.
  • reproduction of data is carried out at a speed lower than the set maximum rotation speed.
  • a CD-ROM disc loaded on the DVD-ROM player 101 is fixed to the disc rotation means 103 .
  • focus search is carried out with a laser beam for CD-ROM, and the amplitude of a focus error signal is measured.
  • the loaded CD-ROM disc is judged as a ROM disc because its reflectivity is relatively high.
  • the CD-ROM disc is rotated at a predetermined speed by the disc rotation means 103 , and the degree of modulation of an RF signal is measured. The measured degree of amplitude is compared with a reference value, whereby the CD-ROM disc is judged as a CD disc, whereby the result of disc judgement is a CD-ROM.
  • the disc is judged as a DVD-ROM disc in the same manner as described above, and then it is checked whether the DVD-ROM disc is a DVD-R4.7G (track pitch: 0.74 ⁇ m) or a DVD-R3.9G (track pitch: 0.8 ⁇ m) by reading the TOC information, whereby the track pitch can be detected.
  • the CD-ROM disc is rotated at a sufficiently low speed, 1200 rpm, which does not cause vibration between the disc and the reading means 104 .
  • the traverse drive means 110 and the tracking actuator 111 are disabled, and the count of the count means 115 is obtained at every rotation angle of 60 degrees. Since no vibration occurs between the disc and the reading means 104 , the count due to only the eccentricity component between them is obtained.
  • the count may be obtained by a method of performing counting for plural rotations with one rotation as a unit, and averaging the obtained counts, or a method of performing counting for plural rotations as described above, and selecting, from the obtained counts, plural counts which are not supposed to be false counts.
  • the CD-ROM disc is rotated at the maximum rotation speed of the CD-ROM disc.
  • the CD-ROM disc is able to perform CAV playback at 24X(maximum)-speed, 12X-speed, and 6X-speed. Since the maximum rotation speed is 5000 rpm, the 12X-speed is 2500 rpm, and the 6X-speed is 1250 rpm, the count when the disc is rotated at 5000 rpm is obtained.
  • the vibration amplitude of this disc is evaluated from this track count and the track pitch, or the vibration speed or vibration acceleration is evaluated from the track count, the track pitch, and the rotation speed of 5000 rpm, and it is decided whether the disc is to be rotated at the maximum rotation speed or not, according to whether the vibration amplitude, or the vibration speed, or the vibration acceleration is lower than the allowable value or not. For example, when it is higher than the allowable value, the maximum rotation speed is reduced to 2500 rpm of the 12X-speed.
  • the vibration amount, or vibration speed, or vibration acceleration is evaluated considering the track pitch of the disc, and a maximum rotation speed that is lower than the allowable vibration amplitude, or vibration speed, or vibration acceleration of the information disc recording/playback apparatus is decided. Therefore, vibration detection can be carried out using a single threshold value, independently of the type of the information disc.
  • counting of the track crosses is carried out at plural rotation speeds while detecting the rotation angle, and a difference between them is calculated to obtain the track count due to vibration.
  • a method of simply counting the track crosses at plural rotation speeds without detecting the rotation angle and then taking a difference between them or a method of counting the track crosses at a single rotation speed without detecting the rotation angle.
  • evaluation of vibration is performed on the basis of a difference between the count obtained at a low speed at which no vibration occurs and the count obtained at the maximum rotation speed, it may be performed on the basis of a difference between the count obtained at a rotation speed at which vibration occurs and the count obtained at the maximum rotation speed. Further, not the maximum rotation speed but a rotation speed lower than the maximum rotation speed may be employed. Furthermore, evaluation may be carried out at two or more rotation speeds, and the playback speed may be set as follows: the maximum rotation speed, a speed lower than the maximum rotation speed, a speed lower than that speed, . . .
  • the counted number of track crosses is multiplied by the track pitch to obtain data of the track cross amount, and the track cross amount due to vibration is calculated by operating the track cross amount, and the vibration amplitude is obtained on the basis of the track cross amount due to vibration.
  • the track pitch of the disc the value of the track pitch itself may be employed, or the ratio of track pitches of plural discs may be employed.
  • the number of track crosses due to vibration is obtained by operating the result of counting, the number of track crosses may be multiplied by the track pitch to obtain the track cross amount due to vibration and, thereafter, the vibration amplitude may be obtained.
  • the vibration amount with the number of track crosses as a unit may be obtained, and the vibration amount may be multiplied by the track pitch to obtain the vibration amplitude.
  • the vibration amplitude is obtained and compared with a reference value, not the vibration amplitude itself but a value in proportion to the vibration amplitude or a value in proportion to the second power of the vibration amplitude may be calculated to be compared with the reference value. Further, the vibration speed or vibration acceleration may be obtained instead of the vibration amplitude.
  • vibrations of discs having different track pitches such as a DVD and a DVD-R3.9G, can be detected in like manner as described above.
  • DVD-ROM player capable of playing CD-ROM, DVD-ROM, DVD-R3.9G, and DVD-R4.7G is described as an example, any information disc player may be employed as long as it can play plural kinds of information discs having different track pitches.
  • the present invention is applicable to a case where a maximum recording speed at recording is set in other writable recording/playback apparatuses such as CD-R, CD-RW, and DVD-R.
  • reference numeral 201 denotes a track cross speed detection means for detecting a track cross speed on the basis of the output from the track cross detection means 112 .
  • the count means 115 counts the track count pulses while detecting the direction when the track cross speed is lower than a predetermined value, and counts the track count pulses without detecting the direction when the track cross speed is higher than the predetermined value, on the basis of the output from the track cross speed detection means 201 .
  • the track cross direction can be known on the basis of the direction obtained when counting with direction detection has been most recently carried out.
  • the maximum speed at which track counting with direction detection can be carried out depends on the track counting method or the disc type.
  • a threshold value for determining as to whether track counting is to be carried out with direction detection or not may be set for each disc type, or it may be set adaptively to a disc of the lowest speed at which track counting with direction detection is possible.
  • the track cross speed detection means 201 is provided, and the track counting method is changed by detecting the track cross frequency. Therefore, even when detection of the track cross direction is difficult because of the change in the track cross speed, track counting can be performed with accuracy, whereby accurate vibration detection can be performed at all times.
  • FIG. 3 the same reference numerals as those shown in FIG. 1 denote the same or corresponding parts, and reference numeral 301 denotes a zero cross area detection means for detecting an area where the track cross speed has the lowest value.
  • the rotation angle detection means 114 usually employs a signal called an FG pulse that is generated from the output of a Hall element of a disc motor. Since the FG signal outputs three pulses for one rotation with a three-phase motor, rotation angle detection in units of 60 degrees can be carried out by counting both of rising and falling edges. In this third embodiment, a description will be given of a case where rotation angle detection is performed in units of 60 degrees using the FG pulses.
  • the zero cross area detection means 301 detects two areas each including a position where the track cross speed has the lowest value. For example, there may be employed a method of detecting areas where the track cross speed has the lowest value by using the track cross speed detection means 112 , or a method of detecting, as zero cross areas, an area where the absolute value of the track count has the lowest value, and an area on a diagonal line with respect to the area from among the six-divided areas.
  • FIG. 6 is a graph illustrating the amount of displacement of the count by the count means 115 at every rotation angle, which displacement is caused by vibration or eccentricity.
  • a count DAT[n] in a zero cross area within a range of ⁇ 0 ⁇ 60°, which is a signed count obtained when performing direction detection, is represented by
  • the optical disc 102 is rotated at a predetermined rotation speed.
  • the count of the count means 115 is obtained for every rotation angle of 60 degrees.
  • the count is obtained by any of the following methods: a method of obtaining the count with direction detection for an area which is judged as a zero cross area by the zero cross area detection means 301 while obtaining the count without direction detection for other areas; a method of obtaining the count with direction detection and the count without direction detection separately, and selecting the count with direction detection for the zero cross area while selecting the count without direction detection for other areas; and a method of obtaining the count with direction detection and the count without direction detection at the same time, and selecting the count with direction detection for the zero cross area while selecting the count without direction detection for other areas.
  • an area that adopts the data without direction detection can obtain the same count as that with direction detection by adding the sign of a just previous area that adopts the data with direction detection, or by adding the sign of a further previous area if the just previous area adopts the data without direction detection.
  • the track cross, detection method is switched between the area where the track cross speed has the lowest value and the other areas, among the areas divided with the rotation angle obtained by the rotation angle detection means 114 , and track counting is carried out with direction detection for the area where the track cross speed has the lowest value while it is carried out without direction detection for the other areas, whereby the optimum track counting method can be selected according to variations in the track cross speed, and accurate vibration detection can be carried out at all times.
  • a DVD-ROM disc loaded on the DVD-ROM player 101 is fixed to the disc rotation means 103 .
  • focus search is carried out with a laser for CD-ROM, and the amplitude of a focus error signal is measured.
  • the DVD-ROM disc is judged as a ROM disc because its reflectivity is relatively high.
  • the DVD-ROM disc is rotated at a predetermined speed by the disc rotation means 103 , and the degree of modulation of an RF signal is measured. The measured degree of modulation is compared with a reference value, whereby the disc is judged as a DVD disc. Consequently, the disc judgement result is a DVD-ROM.
  • the DVD-ROM disc is able to perform 8X-speed playback at 4590 rpm (maximum speed), 5X-speed playback at 2870 rpm, and 2.5X-speed playback at 1435 rpm, and a low speed at which no vibration occurs is 1435 rpm.
  • Vibration detection is carried out at 3000 rpm and 400 rpm, and it is judged whether or not the detected vibration amounts are lower than an allowable vibration amount at the 5X-speed and the 8X-speed, respectively. Further, the allowable vibration amount is 100 ⁇ m.
  • the DVD-ROM disc is rotated at 1435 rpm that is a sufficiently low speed at which no vibration occurs between the disc and the reading means 104 .
  • the count of the count means 115 is obtained at every rotation angle of 60 degrees. Since no vibration occurs between the disc and the reading means 104 , the count due to only the eccentricity component between the disc and the reading means 104 is obtained.
  • the count may be obtained by a method of performing counting for plural rotations with one rotation as a unit, and averaging the obtained counts, or a method of performing counting for plural rotations as described above, and selecting, from the obtained counts, plural counts which are not supposed to be false counts.
  • counting is carried out at 3000 rpm.
  • the counts at 3000 rpm are as follows: TABLE 2 counts at 3000 rpm No. area [0] area [1] area [2] area [3] area [4] area [5] 1 71 49 ⁇ 21 ⁇ 69 ⁇ 48 18 2 71 49 ⁇ 22 ⁇ 69 ⁇ 49 19 3 72 49 ⁇ 22 ⁇ 69 ⁇ 49 18 4 72 51 ⁇ 20 ⁇ 71 ⁇ 50 18 average 71.5 49.5 ⁇ 21.25 ⁇ 69.5 ⁇ 49 18.25
  • the vibration amount is obtained as follows.
  • vibration amount 46 tracks
  • this disc is a DVD-ROM disc
  • the vibration amount is multiplied by the track pitch of 0.74 ⁇ m, whereby the vibration amplitude is obtained as follows.
  • vibration amplitude 34.04 [ ⁇ m]
  • the disc can be rotated at the 5X-speed, i.e., 2870 rpm.
  • the vibration amount is obtained as follows.
  • vibration amount 159 tracks
  • this disc is a DVD-ROM disc
  • the vibration amount is multiplied by the track pitch of 0.74 ⁇ m, whereby the vibration amplitude is obtained as follows.
  • vibration amplitude 117.66 [ ⁇ m]
  • the disc Since the allowable maximum vibration amount of the system is 100 ⁇ m and the obtained vibration amplitude is higher than the allowable value, the disc cannot be rotated at the 8X-speed, i.e., 4590 rpm, and therefore, the maximum rotation speed is set at the 5X-speed.
  • the track cross due to the eccentricity or vibration is represented by a sinusoidal wave as follows, using the Tc, phase angle ⁇ , and angular velocity ⁇ .
  • the vibration amplitude, or vibration speed, or vibration acceleration when the vibration amplitude, or vibration speed, or vibration acceleration is evaluated considering the track pitch of the optical disc 102 , it is calculated at every predetermined rotation angle and an average of the results of calculation is obtained, and a maximum rotation speed that is lower than the allowable vibration amplitude, or vibration speed, or vibration acceleration of the information disc recording/playback apparatus is determined on the basis of the average. Therefore, vibration detection can be carried out more accurately as compared with the first embodiment, using a single threshold value, independently of the type of the information disc.
  • the maximum rotation speeds of other types of discs having different track pitches such as a CD-ROM disc having a track pitch of 1.6 ⁇ m or a DVD-R3.9G disc having a track pitch of 0.8 ⁇ m, can also be obtained by judging as to whether the measured maximum vibration amount is lower than the allowable one, using the standard track pitch of each disc and the vibration amount.
  • the vibration amount is obtained on the basis of the average of 12 pieces of data
  • the vibration amount may be obtained using the average of m pieces of central values selected from the 12 pieces of data which are arranged in the order of size, or using a value in proportion to the average.
  • the maximum playback speed is set on the basis of the vibration amplitude
  • the maximum playback speed may be set using a value in proportion to the vibration amplitude or a value in proportion to the second power of the vibration amplitude.
  • the maximum playback speed may be set on the basis of the vibration speed or a value in proportion to the vibration speed or the second power of the vibration speed, using (Formula 14) and (Formula 15) as well as the disc rotation speed.
  • the maximum playback speed may be set on the basis of the vibration acceleration speed or a value in proportion to the vibration acceleration speed or the second power of the vibration acceleration speed, using (Formula 16) and (Formula 17) as well as the disc rotation speed.
  • the maximum playback speed is set on the basis of the data obtained for four rotations each rotation being divided into six areas, the maximum playback speed may be obtained by measuring data corresponding to continuous two or more areas.
  • reference numeral 116 a denotes a control means having a linear speed detection means 401 and a playback speed detection means 402 .
  • the linear speed detection means 401 detects the linear speed of the disc. For example, the linear speed is detected as follows. An address value at a certain radial position is previously read, one-track jumping is carried out, an address value at the destination of the track jumping is read, and a difference between the address values is obtained as the linear speed.
  • the length of one rotation of the disc is obtained from a radial position, and the linear speed of the disc is obtained on the basis of the radio of the length to the difference between the previously obtained address values for one rotation.
  • the playback speed detection means 402 detects the current playback speed.
  • the current playback speed is obtained from the cycle of a PLL which generates a data playback clock, or it is obtained on the basis of the cycle of a frame clock which is outputted for every frame of data.
  • V 2 2 ⁇ ⁇ ⁇ ⁇ r V 1 ⁇ V rpm 60 ( Formula ⁇ ⁇ 43 )
  • the track pitch Tp can be obtained by further measuring the current playback speed V2 at a certain address Ad.
  • the address Ad at which the current playback speed V2 is obtained may be an arbitrary address, when measurement is carried out at an outer radial position, the accuracy is improved.
  • the track pitch is obtained from the linear speed, address value, and playback speed
  • the track pitch may be obtained as follows.
  • the control means 116 b is provided with a move distance detection means 403 for detecting the move distance of the reading means 104 , and the reading means 104 is moved while counting the number of tracks, and the track pitch is obtained as follows.
  • Tp move distance/number of crossed tracks
  • reference numeral 501 denotes a variable filter means having a function of shaping the track cross pulses detected by the track cross detection means 112 so that the pulses whose widths are narrower than a predetermined value, among the detected pulses, are not counted.
  • variable filter means 501 [0233]
  • a method of actually setting the variable filter means 501 will be described.
  • variable filter means 501 When setting the variable filter means 501 , initially, the total number of track crosses for one or more rotation is counted by the method in which the track cross direction is not detected. At this time, it is necessary to set an initial set value of the variable filter means 501 , and usually, this initial value must be set at such a value that the minimum track count pulse width corresponding to the maximum track cross speed is surely counted when an eccentricity between the disc and the turn table and a maximum vibration amplitude estimated at its rpm occur.
  • the maximum track cross speed can be obtained as follows.
  • cross is represented by (Formula 45 )
  • the maximum track cross speed can be obtained from the value of Tc.
  • the minimum track count pulse width of the variable filter means 501 is set.
  • the maximum track cross speed is represented as follows:
  • Vmax 22.54 kHz
  • the minimum track count pulse width is 22.18 ⁇ s from (Formula 49).
  • variable filter means 501 is set on the basis of this value so that pulses whose widths are narrower than the minimum track count pulse obtained by the above calculation are also counted, considering variations in the duty ratio of the normal pulse width, or the like.
  • variable filter means 501 is set so that a pulse having a width of up to 5.54 ⁇ s, which is one fourth of 22.18 ⁇ s, is counted as a track cross signal.
  • variable filter means 501 may be set so that a pulse having a narrower width is counted if driving at a speed higher than a predetermined value is expected, while in the above example a value obtained by dividing the calculated minimum track count pulse width by a predetermined value is employed as a set value of the filter means 501 .
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • the maximum track cross speed becomes as represented by (Formula 19) or (Formula 20).
  • the minimum track count pulse width may be set similarly by using the average of these data, or the average of m pieces of central values of these data, or the like.
  • setting of the track cross filter by the variable filter means 501 is carried out on the basis of the track cross count and the current rpm, so that the pulses whose widths are narrower than a predetermined value are not counted. Therefore, even when the track cross speed varies significantly due to the eccentricity or vibration of the disc, track counting most suitable for vibration detection can be accurately carried out at all times.
  • setting of the minimum track count pulse width may be carried out only once before obtaining the track count for detecting the vibration amount at each rotation speed, or it may be carried out every time the data (count) for detecting the vibration amount is obtained.
  • a general purpose microcomputer having a relatively small size is employed as a control means for computer peripheral equipment such as a DVD-ROM player.
  • Such microcomputer is basically adaptive to integer arithmetic only, and therefore, floating-point arithmetic or square root trigonometric function must be dealt with by software.
  • DAT[n] DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
  • the maximum track cross speed can be calculated with reduced number of program steps and reduced arithmetic time, and the variable filter means can be set on the basis of the maximum track cross speed.
  • FIG. 6 is a graph illustrating the amount of displacement of the count at every rotation angle, which displacement is caused by vibration or eccentricity.
  • the track cross due to eccentricity or vibration is expressed as a sinusoidal wave, in like manner as described for the sixth embodiment.
  • the Tc calculated from (Formula 21) becomes 0.866 times the original Tc. Accordingly, when the track counting is carried out by the method in which a signed count is outputted because direction detection is carried out, a value smaller than the original Tc, i.e., 0.866 times the original Tc at the worst, is calculated. Considering this effect, when calculating the maximum track cross speed on the basis of the Tc calculated from (Formula 21), (Formula 22) represents the maximum track cross speed including the expected error.
  • the maximum track cross speed including an expected error is calculated on the basis of the signed track cross count and the current rpm, and the track cross filter is set on the basis of the maximum track cross speed. Therefore, track counting most suitable for vibration detection can be accurately carried out at all times, without necessity of performing additional counting without signs or calculating square roots which require many program steps.
  • variable filter means 501 When setting the variable filter means 501 , initially, the total number of track crosses for one or more rotation is counted by the method in which the track cross direction is not detected. At this time, it is necessary to set an initial set value of the variable filter means 501 , and usually, this initial value must be set at such a value that the minimum track count pulse width corresponding to the maximum track cross speed is surely counted when an eccentricity between the disc and the turn table and a maximum vibration amplitude estimated at its rpm occur.
  • setting the minimum track count pulse width is carried out every time the data (count) for performing detection of the vibration amount is obtained.
  • the value of the minimum track count pulse width varies by a predetermined value or more at the same rotation speed, there is a high possibility of false track counting of the previous counts because an optimum track count filter has not been set, and therefore, the value of the minimum track count pulse width is discarded, and only the counts after the change should be adopted as the counts for vibration detection.
  • the counts obtained before the set value of the variable filter means 501 has changed by a predetermined value or more are not used because the possibility of false counting is high. Therefore, track counting most suitable for vibration detection can be accurately carried out at all times.
  • reference numeral 701 denotes a pulse width storage means for holding the width of a pulse that is just previous to the current pulse.
  • Reference numeral 702 denotes a filter means which receives the track cross pulse outputted from the track cross pulse detection means 112 , and outputs it to the count means 115 . At this time, the pulse width is measured, and when the measured pulse width is a predetermined value smaller than the pulse width stored in the pulse width storage means 702 , this pulse is regarded as one due to false count and is not outputted.
  • the measured pulse width should not be counted when it becomes smaller than the just-previous pulse width by a predetermined ratio, for example, 0.5.
  • the pulse width storage means 701 and the filter means 702 are provided, and when the filter means 702 judges that the measured pulse width is a predetermined value smaller than the just-previous pulse width which is stored in the pulse width storage means 701 , this pulse is regarded as one due to false detection caused by noise and is not counted by the count means 115 . Therefore, track counting most suitable for vibration detection can be accurately carried out at all times, without requiring time for excessive measurement.
  • An information disc recording/playback apparatus and a vibration detection method for the information disc recording/playback apparatus according to the present invention are valuable as an information disc recording/playback apparatus having a vibration measurement means for measuring vibrations caused by eccentricity of a disc, and a vibration detection method for the information disc recording/playback apparatus, and particularly, the apparatus and method are valuable as those having a construction for detecting vibrations using track counting.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Rotational Drive Of Disk (AREA)
  • Moving Of The Head For Recording And Reproducing By Optical Means (AREA)
  • Magnetic Record Carriers (AREA)
  • Moving Of Head For Track Selection And Changing (AREA)
  • Optical Recording Or Reproduction (AREA)
US10/148,808 2001-01-24 2001-11-14 Information disk recording/reproducing device, and method for detecting vibration of information disk recording/reproducing device Abandoned US20030123354A1 (en)

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US11/249,309 US7161884B2 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus and method for counting pulses and controlling a rotation speed of an information disc
US11/249,307 US7215621B2 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus and method for counting pulses and controlling a rotation speed of an information disc
US11/249,510 US20060028944A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus
US11/249,314 US20060044963A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus

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US11/249,314 Division US20060044963A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus
US11/249,309 Division US7161884B2 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus and method for counting pulses and controlling a rotation speed of an information disc
US11/249,510 Division US20060028944A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus

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US11/249,307 Expired - Fee Related US7215621B2 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus and method for counting pulses and controlling a rotation speed of an information disc
US11/249,309 Expired - Fee Related US7161884B2 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus and method for counting pulses and controlling a rotation speed of an information disc
US11/249,510 Abandoned US20060028944A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus
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US11/249,309 Expired - Fee Related US7161884B2 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus and method for counting pulses and controlling a rotation speed of an information disc
US11/249,510 Abandoned US20060028944A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus
US11/249,314 Abandoned US20060044963A1 (en) 2001-01-24 2005-10-14 Information disc recording/playback apparatus, and vibration detection method for information disc recording/playback apparatus

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US20070086291A1 (en) * 2005-10-17 2007-04-19 Samsung Electronics Co., Ltd. Focus pull-in control device and method thereof
US20110211434A1 (en) * 2010-02-26 2011-09-01 Sunplus Technology Co., Ltd. Method of recognizing track pitch of optical disk
CN102194484A (zh) * 2010-03-10 2011-09-21 凌阳科技股份有限公司 辨别光碟片轨距的方法
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CN1394334A (zh) 2003-01-29
US20060028943A1 (en) 2006-02-09
US7215621B2 (en) 2007-05-08
US7161884B2 (en) 2007-01-09
US20060028944A1 (en) 2006-02-09
KR100454798B1 (ko) 2004-11-03
TW533409B (en) 2003-05-21
WO2002059886A1 (fr) 2002-08-01
CN1178212C (zh) 2004-12-01

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