Source: http://www.google.com/patents/US6728192?dq=U.S.+patent+number+7,325,728
Timestamp: 2017-05-30 04:10:03
Document Index: 219610901

Matched Legal Cases: ['art 873', 'art 892', 'art 892', 'art 874', 'art 875', 'arts 874', 'arts 874', 'art 893', 'art 893', 'arts 836', 'arts 874', 'arts 874', 'arts 874', 'arts 874', 'art 893', 'art 893', 'art 872', 'art 892', 'art 892', 'arts 832']

Patent US6728192 - Tracking error signal detection system for optical recording medium - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsIn a magnetic recording medium to detect tracking error signals optically where an optical head and a magnetic head scan different tracks, two signals having phases different by π/2 are generated and added or subtracted. By changing the amplitude of the two signals with a changeable gain amplifying...http://www.google.com/patents/US6728192?utm_source=gb-gplus-sharePatent US6728192 - Tracking error signal detection system for optical recording mediumAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS6728192 B1Publication typeGrantApplication numberUS 09/421,025Publication dateApr 27, 2004Filing dateOct 19, 1999Priority dateJul 10, 1995Fee statusLapsedPublication number09421025, 421025, US 6728192 B1, US 6728192B1, US-B1-6728192, US6728192 B1, US6728192B1InventorsShin-ichi Kadowaki, Shinichi Tanaka, Seiji Nishiwaki, Kousei Sano, Seiji NishinoOriginal AssigneeMatsushita Electric Industrial Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (14), Non-Patent Citations (1), Referenced by (4), Classifications (20), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetTracking error signal detection system for optical recording medium
When a beam 70 from the optical system has a displacement x from the center of a guiding groove such as Gn on a magnetic recording medium 40, voltage signals v21, v22 outputted from the I-V converting portions 851, 852 become sine waves having opposite phases which can be approximately represented by the below mentioned formulae (1) and (2). The signals v21, v22 can be illustrated as FIG. 3(a) and (b). v21 = - A · sin   ( 2   π   x / pt ) + B ( 1 ) v22 = A · sin   ( 2   π   x / pt ) + B ( 2 ) In the formulae (1) and (2), A is an amplitude and B is a DC component.
A signal outputted from the differential operation part 873 is, after being adjusted to a favorable amplitude by the changeable gain amplifying portion 833, inputted to an operation part 892. The operation part 892 adds an inputted signal to output a tracking error signal v4 to an output terminal 802. The signal v4 has a wave form represented by the below mentioned formula (7). v4 =  K1 · A1 · sin   ( 2   π   x / pt ) + K2 · A2 · cos   ( 2   π   x / pt ) =  K1 · A1 · sin   ( 2   π   x / pt ) + K2 · A2 · sin   ( 2   π   x / pt + π / 2 ) ( 7 ) In the formula (7), K1, K2 are gains of the changeable gain amplifying portions 832, 833, respectively. A signal v4 can be a signal capable of setting an optional phase and an amplitude by selecting appropriate gains K1, K2. For example, when K1·A1=K2·A2, the signal v4 becomes a signal out of phase with respect to a signal v1 by π/4. Signals v1, v3, v4 can be illustrated as in FIGS. 8(a) to 8(c).
The configuration of an photodetector 51 and a signal processing portion 82 are illustrated in FIG. 11. The photodetector 51 comprises three sensing portions 503 to 505 for sensing beams 71 to 73. respectively. Electric signals outputted from the sensing portions 503 to 505 of the photodetector 51 are inputted to the signal processing portion 82 to be converted to voltage signals by I-V converting portions 853 to 855, respectively. Signals v5 to v7 outputted from the I-V converting portions 853 to 855 are inputted to the signal processing portion 82 to be converted to voltage signals. The signals v5 to v7 outputted from the I-V converting portions 853-855 are signals represented by the below mentioned formulae (8) to (10). In the formulae (8) to (10), A3 denotes an amplitude, and B2 denotes a DC component. v5 = A3 · cos   ( 2   π   x / pt ) + B2 ( 8 ) v6 = A3 · sin   ( 2   π   x / pt ) + B2 ( 9 ) v7 = - A3 · sin   ( 2   π   x / pt ) + B2 ( 10 ) Signals v5, v6 are inputted to a differential operation part 874, and signals v5, v7 are inputted to a differential operation part 875, respectively for subtraction. Signals v8, v9 outputted from the differential operation parts 874, 875 are signals represented by the below mentioned formulae (11) and (12). In the formulae (11) and (12), A4 denotes an amplitude. v8 = A4 · sin   ( 2   π   x / pt + π / 4 ) ( 11 ) v9 = A4 · sin   ( 2   π   x / pt - π / 4 ) ( 12 ) Signals v8, v9 are sine waves out of phase by π/2. The signals v8, v9 outputted from the differential operation parts 874, 875 are inputted to the changeable gain amplifying portions 834, 835, respectively to be adjusted to a favorable amplitude, and inputted to the operation part 893. The operation part 893 conducts addition of inputted signals, and outputs a tracking error signal v10 to an output terminal 803. The signal v10 has a wave form represented by the below mentioned formula (13). v10 =  K3 · A4 · sin   ( 2   π   x / pt + π / 4 ) + K4 · A4 · sin   ( 2   π   x / pt - π / 4 ) =  K4 · A4 · sin   ( 2   π   x / pt + φ   1 ) + K3 · A4 · sin   ( 2   π   x / pt + π / 2 + φ   1 ) ( 13 ) In the formula (13), K3, K4 are gains of the changeable gain amplifying portions 874, 875, respectively, and φ1 is −π/4. A signal v10 can be a signal capable of setting optional phase and amplitude by selecting appropriate gains K3, K4. This can be easily understood in the comparison between the formula (13) and the formula (7) described in the first embodiment.
The configuration of a photodetector 52 and a signal processing portion 84 are illustrated in FIG. 14. The photodetector 52 comprises five sensing portions 506 to 510 for sensing beams 71 to 75, respectively. Five electric signals outputted from the sensing portions 506 to 510 are inputted to the signal processing portion 84 to be converted to voltage signals by I-V converting portions 853 to 856, respectively. Signals outputted from the sensing portions 509 and 510 are added at the input side of the I-V converting portion 856. The signals v11 to v14 outputted from the I-V converting portions 853 to 856 are signals represented by the below mentioned formulae (14) to (17). In the formulae (14) to (17), A5 to A7 denote an amplitude, and B3 to B5 denote a DC component. v11 = - A5 · sin   ( 2   π   x / pt ) + B3 ( 14 ) v12 = - A6 · cos   ( 2   π   x / pt ) + B4 ( 15 ) v13 = A7 · sin   ( 2   π   x / pt ) + B5 ( 16 ) v14 = A6 · cos   ( 2   π   x / pt ) + B4 ( 17 ) Signals v11 to v14 are inputted to changeable gain amplifying parts 836 to 839 respectively, and after being adjusted to a favorable amplitude, inputted to differential operation parts 874, 875 to conduct subtraction. The reason why the changeable gain amplifying portions 836 to 839 are arranged at the input side of the differential operation parts 874, 875 is the same as the reason why the changeable gain amplifying portions 836 to 839 are similarly arranged in the third embodiment.
Signals v15, v16 outputted from the differential operation parts 874, 875 are signals represented by the below mentioned formulae (18) and (19). In the formulae (18) and (19), A8 and A9 denote an amplitude. v15 = A8 · sin   ( 2   π   x / pt ) ( 18 ) v16 =  A9 · cos   ( 2   π   x / pt ) =  A9 · sin   ( 2   π   x / pt + π / 2 ) ( 19 ) Signals v15, v16 are sine waves out of phase by π/2. The signals v15, v16 outputted from the differential operation parts 874, 875 are inputted to the changeable gain amplifying portions 834, 835, respectively to be adjusted to a favorable amplitude, and inputted to the operation part 893. The operation part 893 conducts addition of inputted signals, and outputs a tracking error signal v17 to an output terminal 805. As in the first to third embodiments, the signal v17 can be a signal capable of setting optional phase and amplitude by adjusting the gain of the changeable gain amplifying portions 834. 835.
Signals outputted from the differential operation part 872 are sampled and held by the sample and hold portions 811, 812 with the timing of the timing signals Sa3, Sa4, respectively. Signals v18, v19 outputted from the sample and hold portions 811, 182 are signals represented by the below mentioned formulae (20) and (21). In the formulae (21) and (22), A10 denotes an amplitude. v18 = A10 · sin   ( 2   π   ( x - Δ   pt ) / pt ) ( 20 ) v19 = A10 · sin   ( 2   π   ( x + Δ   pt ) / pt ) ( 21 ) Signals sampled and held by the sample and hold portions 811, 812 are, after being adjusted to a preferable intensity by the changeable gain amplifying portions 832, 833, inputted to the operation part 892. The operation part 892 adds the inputted signals and outputs tracking error signals v20 to the output terminal 806. The signals v20 have a wave form represented by the below mentioned formula (22). v20 = K1 · A10 · sin   ( 2   π   ( x - Δ   pt ) / pt ) + K2 · A10 · sin   ( 2   π   ( x + Δ   pt ) / pt ) ( 22 ) In the formula (22), K1, K2 are gains of the changeable gain amplifying parts 832, 833, respectively. Optional phase and amplitude can be set for a signal v20 by selecting appropriate gains K1, K2 as in the first embodiment. However, in order to tolerate all the phase dislocations with small Δpt, K1, K2 need to be changed drastically, and thus it is not practical. Tracking error signal detection apparatus of the fourteenth embodiment are suitable for optical disk apparatus having a phase dislocation of tracking error signals smaller than pt/2.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4125859 *Nov 1, 1976Nov 14, 1978Hitachi, Ltd.Videodisc play-back apparatus with variable width beamUS4446548Oct 21, 1981May 1, 1984U.S. Philips CorporationApparatus for the point-by-point scanning of an objectUS4775968Oct 3, 1985Oct 4, 1988Sony CorporationTracking error detecting system for optical headUS4958245Apr 7, 1988Sep 18, 1990Insite Peripherals, Inc.Apparatus and method for optical servo control with media having information storage and servo control regions of different reflectivitiesUS5065387Jun 12, 1990Nov 12, 1991Insite Peripherals, Inc.Method and apparatus for generating tracking error signals by means of an optical servo systemUS5287338May 27, 1992Feb 15, 1994Teac CorporationError signal generation for light beam reflected from optical disk with plurality of light detecting elementsUS5341353Aug 4, 1993Aug 23, 1994Pioneer Electronic CorporationActuator position detector, actuator position controller and track search controllerUS5406545Jul 30, 1993Apr 11, 1995Matsushita Electric Industrial Co., Ltd.Servo pattern in an optical data storage medium for obtaining a tracking error signalUS5587985Sep 25, 1995Dec 24, 1996Matsushita Electric Industrial Co., Ltd.Signal processing device for an optical information reproducing apparatusUS5633846Feb 1, 1996May 27, 1997Hitachi, Ltd.Positioning device for optical disc apparatusUS5974011 *Feb 28, 1995Oct 26, 1999Mitsubishi Denki Kabushiki KaishaLight beam condensing apparatus and method of driving optical recording medium by applying the apparatusUS6016300 *Jul 13, 1998Jan 18, 2000Sankyo Seiki Mfg. Co., Ltd.Optical pickup head apparatusEP0457567A2May 15, 1991Nov 21, 1991Sony CorporationTracking error signal generatorJPS6182388A Title not available* Cited by examinerNon-Patent CitationsReference1Communication from European Patent Office and attached Search Report, Apr. 24, 1998.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS20040081048 *Oct 23, 2002Apr 29, 2004Wilhelmson UlfLocal track pitch measuring apparatus and methodUS20050117471 *Nov 24, 2004Jun 2, 2005Hideaki YamaneOptical disc deviceUS20090086599 *Sep 25, 2008Apr 2, 2009Kabushiki Kaisha ToshibaOptical disc apparatus and tracking control methodUS20090092030 *Sep 10, 2008Apr 9, 2009Nec Electronics CorporationOptical disk device* Cited by examinerClassifications U.S. Classification369/112.01, G9B/5.226, G9B/5.194, 369/118, G9B/21.018International ClassificationG11B5/55, G11B21/10, G11B7/09, G11B5/596, G11B5/016Cooperative ClassificationG11B5/016, G11B5/5556, G11B7/0941, G11B7/0903, G11B21/10, G11B5/5565, G11B5/59677European ClassificationG11B21/10, G11B5/596L, G11B5/55D2FLegal EventsDateCodeEventDescriptionSep 17, 2007FPAYFee paymentYear of fee payment: 4Sep 14, 2011FPAYFee paymentYear of fee payment: 8Dec 4, 2015REMIMaintenance fee reminder mailedApr 27, 2016LAPSLapse for failure to pay maintenance feesJun 14, 2016FPExpired due to failure to pay maintenance feeEffective date: 20160427RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services