WO2001052251A1 - Appareil de detection d'erreur de poursuite - Google Patents

Appareil de detection d'erreur de poursuite Download PDF

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Publication number
WO2001052251A1
WO2001052251A1 PCT/JP2001/000123 JP0100123W WO0152251A1 WO 2001052251 A1 WO2001052251 A1 WO 2001052251A1 JP 0100123 W JP0100123 W JP 0100123W WO 0152251 A1 WO0152251 A1 WO 0152251A1
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WO
WIPO (PCT)
Prior art keywords
signal
error detection
light receiving
phase error
tracking error
Prior art date
Application number
PCT/JP2001/000123
Other languages
English (en)
Japanese (ja)
Inventor
Toshinori Okamoto
Original Assignee
Matsushita Electric Industrial 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
Application filed by Matsushita Electric Industrial Co., Ltd. filed Critical Matsushita Electric Industrial Co., Ltd.
Publication of WO2001052251A1 publication Critical patent/WO2001052251A1/fr

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only

Definitions

  • the present invention relates to an optical recording / reproducing apparatus for optically recording / reproducing a signal from an information recording medium by an optical pickup, and to a tracking error detecting apparatus for generating a tracking error signal for controlling tracking of the optical pickup and an offset signal.
  • the present invention provides specific means for realizing miniaturization and low power consumption of the circuit.
  • a method for obtaining a tracking control signal from an optical disk in which information is recorded in a recording medium with uneven pits there is a method called a phase difference method or a DPD (Differential Phase Detection) method.
  • This method utilizes the fact that when a light spot irradiated on a disk passes over the pits, the mapping (diffraction pattern) of the pits on the light receiving element changes due to the deviation of the light spot from the center of the pits.
  • the manner of change is as follows. The light spot will differ depending on the direction and amount of deviation from the pit center.After binarizing the output of the photodetector at a predetermined level, the phases of the binary signals are compared, and the respective values are compared. Which shows the direction and amount of deviation of the light spot by looking at the force ⁇ and the time difference (phase difference) between the level change and the level of the received light from the light receiving element in the area This makes it possible to obtain an error signal.
  • 3 to 5 show the intensity of the amount of reflected light received by the light receiving areas 24, 25, 26, and 27 of the four-split sensor 21 when the light spot 23 passes over the information pits 22.
  • the distribution pattern far-field pattern
  • (a) in each of these figures shows the positional relationship between the light spot 23 and the information pit 22, and (b) the light spot.
  • 23 shows the far field patterns of the amount of reflected light when 23 passes over the information pit 22.
  • the far field pattern has uniform brightness.
  • the far field pattern changes symmetrically as shown in FIG. Also, as shown in FIGS. 3 and 5, when the optical spot 23 passes off the center, the symmetry of the left and right of the far-field pattern is broken, and the time difference (phase difference) As shown in FIG. 3, when the optical spot 23 passes rightward from the center of the information pit 22, the light spot 23 changes to rotate clockwise, and conversely, the optical spot 23 becomes Information When passing from the center of pit 22 to the left, it changes so as to rotate counterclockwise as shown in FIG. This change in the pattern becomes clearer as the light spot 23 is shifted from the center of the information pit 22.
  • the tracking error signal as shown in FIG. 7 can be obtained by converting the light amount into an electric signal and detecting the time difference.
  • the tracking error signal receives the reflected light amount in the light receiving areas 24, 25, 26, 27 of the 4-split sensor 21 and is located at each diagonal. If the signal difference is calculated from the sum of the light receiving areas, the tracking error signal becomes zero, and the optical spot 23 is in an on-track state just above the track. On the other hand, when the light spot 23 deviates from the information pit, the symmetry of the intensity distribution of the far field pattern is broken according to the light quantity, and a tracking error signal is generated. However, even if the light spot 23 is formed on the information track, the center of the far field pattern and the dividing line of the quadrant sensor may be displaced. In this case, the tracking error signal is in an on-track state.
  • FIG. 6 shows the relationship between the light receiving area of the split sensor 31 and the far field pattern of the optical spot 32 when an offset error occurs.
  • the far field pattern of the optical spot 32 is related to the depth of the information pit. If the wavelength to be used is selected, the depth of the information pit is reduced as shown in FIGS. In the case of ⁇ / 4 in 2), the diagonal pattern is the same even if the lens moves, and the time difference (phase difference) becomes zero.
  • Figs. 6 (3) and (4) when the distance is different from ⁇ / 4, there is a level difference in the diagonal pattern, which causes a time difference (phase difference). An offset occurs in the tracking error signal.
  • FIG. 9 is a diagram showing a configuration of a conventional tracking error detection device.
  • a conventional tracking error detection device will be described with reference to FIG.
  • the diffraction pattern (far-field pattern) of the light when the light spot passes over the information pit is detected using a photodetector 60 whose light-receiving area is divided into four parts.
  • the photodetector 60 has light receiving elements 70 a, 70 b, 70 c, and 70 d divided into four crosses, and irradiates a light spot on a track of an information recording medium.
  • the reflected light is received from the information tracks obtained as described above, and the amount of light corresponding to the amount of light incident on each is converted into an electric signal.
  • the output signals of the light receiving elements 70a and 70c are output by the adder 61a, and the output signals of the light receiving elements 70b and 70d are output by the adder 61b. Is added. That is, the output signals from the light receiving elements located on the diagonal lines are added by the adders 61a and 61b.
  • the phase between the added signals output from the adders 6 1 a and 6 lb is compared by a phase error detection circuit 62 as first phase error detection means, and a phase error signal corresponding to the difference is A tracking error signal is obtained through a low-pass filter 63, which is a first low-pass means.
  • the output signals of the light receiving elements 70a and 70b are added by the adder 61c, and the output signals of the light receiving elements 70c and 70d are added by the adder 61d.
  • the phase between the added signals output from the adder 61C61d is compared by a phase error detection circuit 64, which is a second phase error detection means, and the phase error signal corresponding to the difference is obtained.
  • an offset signal is obtained through a low-pass filter 65, which is a second low-pass filter.
  • the tracking error signal is obtained by using the phase error detection circuit 62 and the low-pass filter 63, and the off-set of the tracking error signal is obtained by using the phase error detection circuit 64 and the low-pass filter 65.
  • Circuit is configured to detect each signal separately. It was not effective in reducing the size and power consumption.
  • the present invention has been made to solve the above-described problems.
  • a phase error which has existed for generating a tracking error signal and for generating an offset signal has been present.
  • An object of the present invention is to reduce the size and power consumption of a circuit by sharing a detection circuit and a single-pass filter and using the shared phase error detection circuit and low-pass filter in a time-sharing manner. Disclosure of the invention
  • the invention according to claim 1 is directed to a method of irradiating a reflected light of an optical spot formed by irradiating a light beam on an information track of an information recording medium with the information track direction and its information.
  • a light receiving unit that receives light by the light receiving element divided into four in the track direction and the vertical direction and outputs four electric signals corresponding to the respective light receiving amounts, and a diagonal direction among the four electric signals output from the light receiving element
  • First and second adding means for adding the electric signals from the light receiving elements of the first and second light receiving elements, and the electric signals from the light receiving elements of the preceding and succeeding stages perpendicular to the track direction among the four electric signals output from the light receiving elements
  • Third and fourth adding means for adding signals
  • first phase error detecting means for detecting detecting a phase error signal that changes according to a time difference between the added signals output from the first and second adding means.
  • phase error detection means for detecting a phase error signal that changes in accordance with a time difference between the addition signals output from the four addition means, and a phase error signal output from the first phase error detection means.
  • a first low-pass filter for removing a high-frequency component and detecting a tracking error signal indicating a relative position between the information track and the light beam; and a phase error signal output from the second phase-error detector.
  • a second low-pass means for generating an offset signal in the tracking error signal, wherein the first phase error detecting means and the second phase error are removed. Detection means, and the first low-pass means and the second low-pass means are shared, and the tracking error signal and the offset signal are shared. Characterized by using the phase error detector and a low pass means in time division manner.
  • the invention according to claim 2 is the invention according to claim 1.
  • the four electric signals output from the light receiving means are controlled, and the output signals of the light receiving elements in the diagonal directions among the four electric signals are added, or the front stage perpendicular to the track direction is added.
  • selecting means for selecting whether to add the output signal of the light receiving element at the subsequent stage.
  • the invention according to claim 3 is the tracking error detection device according to claim 2, wherein the selection unit determines whether to detect a tracking error signal or an offset signal. This is characterized by being controlled by a DSP that outputs a switching signal to be changed.
  • the invention according to claim 4 irradiates a light beam onto an information track of an information recording medium, and reflects reflected light from the information track at least in an information track direction and a direction intersecting the information track direction.
  • a light receiving means having a light receiving area divided into two, and outputting an electric signal according to an irradiation light amount to each light receiving area; and at least two first light receiving means obtained by a predetermined first combination of the light receiving areas.
  • a phase error detection circuit that detects a phase error signal that changes in accordance with a time difference; receives a phase error signal output from the phase error detection circuit; removes a high-frequency component from the signal; And low-pass means for generating a tracking error signal indicating the relative position or generating an offset signal in the tracking error signal.
  • the first phase error detection means and the first low-frequency band which are means for detecting the tracking error signal
  • the second phase error detection section and the second low-pass means which are means for detecting the offset signal
  • the shared phase error detection means and the low-pass means are used in a time-division manner.
  • FIG. 1 is a block diagram of a tracking error detection device according to Embodiment 1 of the present invention.
  • FIG. 2 is an operation waveform diagram of the tracking error detection device according to the first embodiment of the present invention.
  • FIG. 3 is a diagram showing a change in a far-field pattern in tracking error detection.
  • FIG. 4 is a diagram showing a change in a far-field pattern in tracking error detection.
  • FIG. 5 is a diagram showing a change in a far field pattern in tracking error detection.
  • FIG. 6 is a diagram showing a change in a far field pattern in detecting an offset signal.
  • FIG. 7 is a waveform diagram of a tracking error signal.
  • FIG. 8 is a waveform diagram of a tracking error signal having an offset.
  • FIG. 9 is a block diagram of a conventional tracking error detection device. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a diagram showing a configuration of a tracking error detection device according to a first embodiment of the present invention.
  • the tracking error detecting device according to the first embodiment will be described with reference to FIG.
  • a light diffraction pattern when a light spot passes over an information pit is detected by using a photodetector 10 having a light-receiving area divided into four parts.
  • the photodetector 10 has light-receiving elements la, lb, lc, and 1d divided into four crosses in the shape of a cross, and obtains information obtained by irradiating a light spot on a track of an information recording medium.
  • Receiving the reflected light from the truck The light amount corresponding to the incident light amount is converted into an electric signal.
  • the converted signals are converted from analog signals to digital signals by the AD converters 16a, 16b, 16c and 16d, respectively.
  • the adder 12a calculates the sum of the output signals of the light receiving elements 1a and 1c
  • the adder 12b calculates the sum of the output signals of the light receiving elements 1b and Id.
  • the selectors 11a and 11b select the output signals from the light receiving elements based on the switching signal from the DSP (Digital Signal Processor) 17 so that the output signals from the light receiving elements can be obtained. That is, the adders 12a and 12b add the output signals obtained from the light receiving elements in the diagonal directions.
  • the obtained addition signals are input to a phase error detection circuit 13, where the phases are compared to obtain a phase error signal, and the obtained phase error signal is subjected to low-pass means (one-pass filter). By passing the signal through 4, a tracking error signal is obtained.
  • the adder 12a obtains the sum of the output signals of the light receiving elements 1a and lb, and the adder 12b obtains the sum of the signals of the light receiving elements 1c and Id.
  • the selectors 11a and 11b select output signals from the light receiving elements based on the switching signal from the DSP 17, respectively. That is, the adders 12a and 12b add signals obtained from the front and rear light receiving elements perpendicular to the track direction.
  • the obtained addition signals are input to a phase error detection circuit 13, where the phases are compared to obtain a phase error signal, and the obtained phase error signal is passed through a single-pass filter 14. Find the offset signal.
  • the low-pass filter 14 because of the digital configuration, it is possible to assign or set filter coefficients to each of the tracking error signal and the offset signal.
  • the switching signal is an output signal from the DSP 17 and determines whether to detect a tracking error signal or an offset signal.
  • the tracking error signal must always detect whether the light spot is on the track, but the offset signal detects the offset of the tracking error signal due to the lens shift when the light spot is on track. Therefore, the offset signal need not always be detected. Therefore, once every certain number of inspections It is possible to adjust the offset deviation even if it is output, and it is possible to determine whether to detect the tracking error signal or the offset signal based on the switching signal.
  • Fig. 2 (a) shows the signal inside the DSP 17, which detects the tracking error signal with the TE pulse or the offset signal with the TG pulse to the DSP 17 side.
  • TG pulse signal appears between TE pulses at certain intervals.
  • the switching signal is generated so that the switching signal is the pulse immediately before the TG pulse in (a), and the switching signal is HI GH; otherwise, it is LOW. Is done.
  • the tracking error signal device 15 detects an offset signal when the switching signal is HIGH, and detects a tracking error signal when the switching signal is LOW.
  • the switching signal output from the DSP 17 detects the tracking error signal in a time division manner in the signal detection, or detects the offset signal. Can be switched, the circuit can be shared, and the circuit can be reduced in size and power consumption can be reduced.
  • the tracking error detection device includes a first phase error detection unit and a first low-pass unit that detect the tracking error signal in detecting the tracking error signal and the offset signal.
  • the second phase error detection section and the second low-pass means which are means for detecting the offset signal, are shared, and the shared phase error detection means and the low-pass means are used in a time-division manner. It is suitable for miniaturization of the circuit of the tracking error detection device and low power consumption.

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  • Optical Recording Or Reproduction (AREA)

Abstract

On décrit un appareil de détection d'erreur de poursuite dans lequel une des diverses combinaisons des sorties des photodétecteurs (1a-1d) est sélectionnée par des sélecteurs (11a,11b) et envoyée à un circuit (13) de détection des erreurs de poursuite à l'étage suivant, et la sortie du circuit de détecteur des erreurs de poursuite est envoyée à un filtre passe-bas (14) à l'étage suivant du circuit (13) de détection des erreurs de phase. Dans un tel appareil de détection des erreurs de poursuite, un dispositif de détection des erreurs de poursuite servant à détecter un signal d'erreur de poursuite et un dispositif de filtre passe-bas peuvent également être utilisés en tant que dispositif de détection des erreurs de poursuite détectant un signal décalé et en tant que dispositif de filtre passe-bas, respectivement. Par conséquent un signal d'erreur de poursuite et un signal décalé sont détectés au moyen d'un dispositif de détection d'erreur de poursuite et d'un dispositif de filtre passe-bas partagé suivant un mode à répartition dans le temps. Il est ainsi possible de réduire la taille et de réduire la consommation d'énergie du circuit utilisé pour commander la poursuite d'un détecteur optique d'un appareil d'enregistrement et/ou de reproduction optique.
PCT/JP2001/000123 2000-01-13 2001-01-12 Appareil de detection d'erreur de poursuite WO2001052251A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2000004701A JP2001195754A (ja) 2000-01-13 2000-01-13 トラッキング誤差検出装置
JP2000-4701 2000-01-13

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JP4512594B2 (ja) * 2003-05-21 2010-07-28 コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ 光ディスクドライブにおけるラジアルトラッキング方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10198995A (ja) * 1996-12-27 1998-07-31 Victor Co Of Japan Ltd トラッキングエラー信号生成回路及び位相差検出回路
JPH10269592A (ja) * 1997-03-19 1998-10-09 Hitachi Ltd 光ディスク再生装置及びかかる装置におけるトラッキング誤差信号評価方法とトラッキング誤差信号生成装置
JPH11203693A (ja) * 1998-01-16 1999-07-30 Mitsubishi Electric Corp 光学的情報再生方法および装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10198995A (ja) * 1996-12-27 1998-07-31 Victor Co Of Japan Ltd トラッキングエラー信号生成回路及び位相差検出回路
JPH10269592A (ja) * 1997-03-19 1998-10-09 Hitachi Ltd 光ディスク再生装置及びかかる装置におけるトラッキング誤差信号評価方法とトラッキング誤差信号生成装置
JPH11203693A (ja) * 1998-01-16 1999-07-30 Mitsubishi Electric Corp 光学的情報再生方法および装置

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TW498322B (en) 2002-08-11

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