Source: http://www.google.com/patents/US4581662?dq=7,328,163
Timestamp: 2016-09-29 18:58:51
Document Index: 315649937

Matched Legal Cases: ['art 96', 'art 95', 'art 96', 'art 96', 'art 95', 'arts 95', 'arts 95', 'arts 95']

Patent US4581662 - Position control apparatus for controlling positions of rotary heads with ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA position control apparatus for controlling positions of rotary heads with respect to a recording medium, comprises a pulse generating circuit and a head displacing mechanism. A rotary body is mounted with the rotary heads, and two or more rotary heads simultaneously scan over the recording medium at...http://www.google.com/patents/US4581662?utm_source=gb-gplus-sharePatent US4581662 - Position control apparatus for controlling positions of rotary heads with respect to a recording mediumAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS4581662 APublication typeGrantApplication numberUS 06/636,282Publication dateApr 8, 1986Filing dateJul 31, 1984Priority dateAug 3, 1983Fee statusPaidAlso published asDE136785T1, DE3472179D1, EP0136785A1, EP0136785B1Publication number06636282, 636282, US 4581662 A, US 4581662A, US-A-4581662, US4581662 A, US4581662AInventorsFumiaki SatoOriginal AssigneeVictor Company Of Japan, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (4), Non-Patent Citations (6), Referenced by (17), Classifications (31), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetPosition control apparatus for controlling positions of rotary heads with respect to a recording medium
US 4581662 AAbstract
A position control apparatus for controlling positions of rotary heads with respect to a recording medium, comprises a pulse generating circuit and a head displacing mechanism. A rotary body is mounted with the rotary heads, and two or more rotary heads simultaneously scan over the recording medium at one time. The pulse generating circuit is responsive to a rotation detection pulse signal which is in phase with a rotation of the rotary body, and generates a pulse signal having a phase and pulse width essentially equal to a recording or reproducing time period in which one corresponding rotary head among the rotary heads records or reproduces a signal on or from the recording medium, with respect to each of the rotary heads. The displacing mechanism is provided in correspondence with each of the rotary heads, and separates from a recording surface of the recording medium rotary heads excluding one rotary head which is to carry out a recording or reproduction during essentially the entire time period in which the one rotary head scans over the recording medium, responsive to output pulse signals of the pulse generating circuit.
1. A position control apparatus for controlling positions of rotary heads with respect to a recording medium in a recording and/or reproducing apparatus, said recording and reproducing apparatus comprising a rotary body on which a recording medium in the form of a tape is wrapped around an outer peripheral surface of said rotary body over a predetermined angular range which is greater than or equal to 180�, a plurality of rotary heads mounted in a rotating plane of said rotary body for recording and/or reproducing signals on and/or from said recording medium as said recording medium moves, two or more rotary heads among said plurality of rotary heads simultaneously scanning over said recording medium at one time, said position control apparatus comprising:a pulse generating circuit responsive to a rotation detection pulse signal which is in phase with a rotation of said rotary body, for generating a pulse signal having a phase and pulse width essentially equal to a recording or reproducing time period in which one corresponding rotary head among said plurality of rotary heads records or reproduces a signal on or from said recording medium, with respect to each of said plurality of rotary heads; and head displacing means provided in correspondence with each of said plurality of rotary heads, for separating from a recording surface of said recording medium rotary heads excluding one rotary head which is to carry out a recording or reproduction during essentially the entire time period in which said one rotary head scans over said recording medium, responsive to output pulse signals of said pulse generating circuit. 2. A position control apparatus as claimed in claim 1 in which said pulse generating circuit generates a pulse signal having a sloping leading edge and a sloping trailing edge, only with respect to said head displacing means which displaces said one rotary head which is to carry out the recording or reproduction, so that said one rotary head gradually makes contact with the recording surface of said recording medium and gradually separates from the recording surface of said recording medium.
5. A position control apparatus for controlling positions of rotary heads with respect to a recording medium in a recording and/or reproducing apparatus, said recording and reproducing apparatus comprising a rotary body on which a recording medium in the form of a tape is wrapped arpund an outer peripheral surface of said rotary body over a predetermined angular range which is greater than or equal to 180�, a plurality of rotary heads mounted in a rotating plane of said rotary body for recording and/or reproducing signals on and/or from said recording medium as said recording medium moves, two or more rotary heads among said plurality of rotary heads simultaneously scanning over said recording medium at one time, said position control apparatus comprising:a pulse generating circuit responsive to a rotation detection pulse signal which is in phase with a rotation of said rotary body, for generating a pulse signal having a phase and pulse width essentially equal to a recording or reproducing time period in which one corresponding rotary head among said plurality of rotary heads records or reproduces a signal on or from said recording medium, with respect to each of said plurality of rotary heads; head displacing means using piezoelectric elements and provided in correspondence with each of said plurality of rotary heads, for separating from a recording surface of said recording medium rotary heads excluding one rotary head which is to carry out a recording or reproduction during essentially the entire time period in which said one rotary head scans over said recording medium, responsive to output pulse signals of said pulse generating circuit, said piezoelectric elements expanding and contracting in a direction perpendicular to the recording surface of said recording medium responsive to peak values of the output pulse signals of said pulse generating circuit; oscillator means using surface elasticity waves of said piezoelectric elements, for producing signals having different oscillation frequencies responsive to expanding and contracting quantities of said piezoelectric elements; and compensating means for compensating the peak values of the output pulse signals of said pulse generating circuit responsive to output signals of said oscillator means. 6. A position control apparatus as claimed in claim 5 in which said compensating means comprises variable frequency oscillator means for generating signals having repetition frequencies responsive to the peak values of the output pulse signals of said pulse generating circuit, means for producing compensation signals having levels responsive to respective frequency differences between output signal frequencies of said oscillator means and output signal frequencies of said variable frequency oscillator means, and mixing means for adding said compensation signals to the output pulse signals of said pulse generating circuit.
7. A position control apparatus for controlling positions of rotary heads with respect to a recording medium in a recording and/or reproducing apparatus, said recording and reproducing apparatus comprising a rotary body on which a recording medium in the form of a tape is wrapped around an outer peripheral surface of said rotory body over a predetermined angular range which is greater than or equal to 180�, a plurality of rotary heads mounted in a rotating plane of said rotary body for recording and/or reproducing signals on and/or from said recording medium as said recording medium moves, two or more rotary heads among said plurality of rotary heads simultaneously scanning over said recording medium at one time, said position control apparatus comprising:a pulse generating circuit responsive to a rotation detection pulse signal which is in phase with a rotation of said rotary body, for generating a pulse signal having a phase and pulse width essentially equal to a recording or reproducing time period in which one corresponding rotary head among said plurality of rotary heads records or reproduces a signal on or from said recording medium, with respect to each of said plurality of rotary heads; head displacing means using first piezoelectric elements and provided in correspondence with each of said plurality of rotary heads, for separating from a recording surface of said recording medium rotary heads excluding one rotary head which is to carry out a recording or reproduction during essentially the entire time period in which said one rotary head scans over said recording medium, responsive to output pulse signals of said pulse generating circuit, said first piezoelectric elements expanding and contracting in a direction perpendicular to the recording surface of said recording medium responsive to peak values of the output pulse signals of said pulse generating circuit; first oscillator means using surface elasticity waves of said first piezoelectric elements, for producing signals having different oscillation frequencies responsive to expanding and contracting quantities of said first piezoelectric elements; second oscillator means using a surface elasticity wave of an independent second piezoelectric element; frequency converter means for obtaining respective frequency differences between an output signal frequency of said second oscillator means and output signal frequencies of said first oscillator means; and compensating means for compensating the peak values of the output pulse signals of said pulse generating circuit responsive to output signal frequencies of said frequency converter means. 8. A position control apparatus as claimed in claim 7 in which said second piezoelectric element is mounted on the rotating plane of said rotary body.
The present invention generally relates to position control apparatuses for controlling positions of rotary heads with respect to a recording medium, and more particularly to a position control apparatus for controlling relative positions of a plurality of rotary heads with respect to a magnetic surface of a magnetic tape, in a recording and/or reproducing apparatus wherein there exists a time period in which two or more rotary heads among the plurality of rotary heads simultaneously scan over the magnetic tape.
Generally, an existing helical scan type recording and reproducing apparatus (VTR) records a video signal by rotary heads on tracks which are formed obliquely to the longitudinal direction of a magnetic tape upon recording, and reproduces the recorded signal from the tape upon reproduction. Amcng this type of a helical scan type VTR, there is a known 4-head type VTR in which four rotary heads are equally spaced apart and mounted on a rotary body such as a rotary drum and a rotary plate, so that adjacent rotary heads are spaced apart by 90�. In this 4-head type VTR, two mutually opposing rotary heads have gaps of the same azimuth angle. In addition, the adjacent rotary heads have gaps of mutually different azimuth angles. Certain conditions must be satisfied in order to form a tape pattern on the tape by the 4-head type VTR, so that the tape pattern is identical to a tape pattern which is formed on the tape by the existing VTR (hereinafter referred to as a 2-head type VTR) which carries out the recording and reproduction by use of two rotary heads which are mounted diametrically on a rotary body. One condition which must be satisfied, is to select the azimuth angles of the gaps in the four rotary heads to the same azimuth angles as the gaps in the two rotary heads of the 2-head type VTR. Another condition to be satisfied, is to wrap the tape around the peripheral surface of the rotary body over an angular range of approximately 270�. Still another condition which must be satisfied, is to select the tape traveling speed so that the tape travels by one track pitch during one field period in which one rotary head rotates by 270�.
Among the four rotary heads in the 4-head type VTR, one field of video signal is recorded on or reproduced from one video track in a time period in which one of the four rotary heads rotates over approximately 270�. During this time period in which one rotary head which is recording or reproducing rotates over approximately 270�, a rotary head which lags the one rotary head by 90� in the rotating direction and a rotary head which lags the one rotary head by 180� in the rotating direction successively scan over a part of the one video track. Accordingly, at the time of the recording, it is necessary to successively switch and supply the video signal to only one of the four rotary heads which is to carry out the recording. Further, at the time of the reproduction, it is necessary to successively switch and obtain a reproduced signal from only one of the four rotary heads which is to carry out the reproduction.
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Accordingly, it is a general object of the present invention to provide a novel and useful position control apparatus for controlling positions of rotary heads with respect to a recording medium, in which the problems described heretofore have been eliminated.
FIG. 1 shows an example of an arrangement of heads in a 4-head type recording and reproducing apparatus which is applied with a position control apparatus according to the present invention;
First, description will be given with respect to the arrangement of heads, the angle over which a magnetic tape is wrapped around the outer peripheral surface of a rotary body, the scanning loci of the heads, and the like, in a 4-head type recording and reproducing apparatus (VTR) which may be applied with a position control apparatus according to the present invention. In FIG. 1, a rotary body 11 which may assume the form of a rotary drum or a rotary plate, for example, has a diameter D. This diameter D of the rotary body 11, is selected to 2/3 the diameter of the rotary drum in the existing 2-head type VTR. The rotary body 11 is rotated counterclockwise (the direction indicated by an arrow X2) at a rotational speed (45 rps, for example) which is related to the field frequency of the video signal which is to be recorded and reproduced, by a motor (not shown). Recording and reproducing magnetic heads (rotary heads) HA, HB, HC, and HD are equally spaced apart and mounted on the rotary body 11, so that adjacent rotary heads are spaced apart by 90�. The rotary heads HA and HC have gaps of the same azimuth angle, and the rotary heads HB and HD have gaps of the same azimuth angle. The rotary heads HA and HB have gaps of mutually different azimuth angles.
By taking into account the angle required to carry out the overlap recording described before, a magnetic tape 12 is guided by guide poles 13a and 13b and wrapped obliquely around the peripheral surface of the rotary body 11 over an angular range which is greater than 270� and less than 360�. This angular range over which the tape 12 is wrapped around the peripheral surface of the rotary body 11, is selected so as not to interfere with the tape travel, and so that the tape 12 can be loaded automatically. The diameter D of the rotary body 11 is equal to 2/3 the diameter of the rotary body in the existing 2-head type VTR, and is small. The tape 12 is driven in a state where the tape 12 is pinched between a capstan (not shown) and a pinch roller (not shown), to travel in the direction of an arrow X1. The traveling speed of the tape 12 is selected so that the tape 12 travels by one track pitch while one of the rotary heads HA, HB, HC, and HD rotates by an angle which is slightly larger than 270� at a rotational speed of 45 rps.
The scanning loci of the four rotary heads HA, HB, HC, and HD in the 4-head type VTR described heretofore, are shown in FIG. 2. As clearly seen from FIG. 2, the scanning loci of the four rotary heads HA, HB, HC, and HD are different from the scanning loci of the two rotary heads in the existing 2-head type VTR. If the rotary head HA assumes a location near the guide pole 13a and starts to scan over the tape 12, a scanning locus indicated by a solid line 14A in FIG. 2 begins to be formed. When the rotary head HA scans over approximately 1/3 the scanning locus 14A, the rotary head HD which lags the rotary head HA by 90� with respect to the rotating direction of the rotary body 11 starts to make contact with the tape 12. Further, when the rotary head HA scans over 2/3 the scanning locus 14A, the rotary head HC starts to make contact with the tape 12. At a point when the rotary head HA completes scanning over the scanning locus 14A, the rotary head HB starts to make contact with the tape 12. Accordingly, as the rotary head HA scans over the scanning locus 14A, the rotary head HD scans over a scanning locus indicated by a two-dot chain line 14D in FIG. 2 with a predetermined time lag, and the rotary head HC scans over a scanning locus indicated by a one-dot chain line 14C in FIG. 2 with a further predetermined time lag. The rotary head HB starts to scan over a scanning locus indicated by a broken line 15B at the point when the rotary head HA completes scanning over the scanning locus 14A.
In order to form a tape pattern which is identical to the tape pattern shown in FIG. 3 which is formed by the existing 2-head type VTR, the video signal is only supplied to the rotary heads which are scanning over the scanning loci 14A, 15B, 16C, 17D, 18A, . . . The reference numerals of these scanning loci 14A, 15B, 16C, 17D, 18A, . . . are encircled in FIG. 2. As a result, a track t1 shown in FIG. 3 is formed by the rotary head HA. Similarly, by switching the recording head in a sequence HB→HC→HD→HA→. . . for every period which is approximately equal to one field, video tracks t2, t3, t4, t5, . . . are formed in this sequence.
The stationary lower drum 34 comprises therein a part of the motor shaft 21, the flywheel 26, the bearings 27 and 28, the head mount 29, the set screws 30 and 31, the rotary core 32, and the stationary core 33. A tape guiding groove 45 is spirally formed in the outer peripheral surface of the stationary lower drum 34. The magnetic side of the magnetic tape 12 makes contact with the outer peripheral surfaces of both the rotary upper drum 23 and the stationary lower drum 34, in a state where the lower edge of the tape 12 is guided by the tape guiding groove 45. As described before in conjunction with FIG. 1, the tape 12 is spirally wrapped around the outer peripheral surfaces of both the rotary upper drum 23 and the stationary lower drum 34, over an angular range which is greater than 270� and less than 360�.
A rotation detection pulse signal a is shown in FIG. 6(A). As shown in FIG. 6(A), the rotation detection pulse signal a is a square wave having a duty cycle of approximately 50%. Thus, the repetition frequency of the rotation detection pulse signal a is equal to 45 Hz when the rotary body 11 rotates at 45 rps. In other words, 3/4 the period of the rotation detection pulse signal a corresponds to a time period in which the rotary body 11 rotates over 270�, and is equal to a time period of one field of the video signal which is to be recorded and reproduced. The rotation detection pulse signal a is supplied to a counter 62 wherein the pulses are counted. The counter 62 produces a pulse signal b shown in FIG. 6(B) through a first bit output terminal O1, and produces a pulse signal c shown in FIG. 6(C) through a second bit output terminal O2. A pulse signal d shown in FIG. 6(D) which is obtained by passing the output pulse signals b and c of the counter 62 through an AND circuit 63, is applied to a reset terminal R of the counter 62 so as to reset the counter 62. As may be seen from FIGS. 6(A) and 6(D), the repetition frequency of the pulse signal d is equal to 15 Hz. One reset pulse of the pulse signal d is supplied to the counter 62 and to an output terminal 88, every time the rotary body 11 undergoes three revolutions. This means that the reset pulse is produced for every time period of four fields.
A common terminal of a switch 83 is coupled to the open-collector AND circuits 65 through 68, through respective resistors R1 through R4. Four switching terminals of the switch 83, are independently coupled to respective power source voltages V1 through V4. The switch 83 is switched over according to the hardness of the magnetic tape 12, so as to vary the peak values of the pulse signals m through p. Accordingly, as will be described later on in the specification, the quantities that the rotary heads HA through HD project by the operation of piezoelectric bases 90A through 90D, that is, the head projecting quantities, are selected to optimum values which are in accordance with the hardness of the magnetic tape 12. The existing standard type magnetic tape has a thickness of approximately 20 μm. For example, when using a thin type magnetic tape having a thickness of 15 μm, the head projecting quantities must be reduced compared to the head projecting quantities with respect to the standard type magnetic tape. This is because the hardness of the thin type magnetic tape in this case is softer than the hardness of the standard type magnetic tape, and the level of the reproduced signal will be low and unsatisfactory unless the head projecting quantities are reduced. Hence, when carrying out the recording or reproduction with respect to the thin type magnetic tape, the switch 83 is switched over so as to reduce the average head projecting quantity compared to the average head projecting quantity in the case where the recording or reproduction is carried out with respect to the standard type magnetic tape, by adding small voltages to the output pulse signals m through p of the AND circuits 75 through 78.
Next, description will be given with respect to the construction of the piezoelectric bases 90A through 90D. In the position control apparatus of the present invention, the arrangement of the rotary heads HA through HD and the head rotating mechanism are basically the same as those of the 4-head type VTR described before. However, as shown in FIG. 7, the rotary heads HA, HB, HC, and HD are mounted on tip ends of the respective piezoelectric bases 90A through 90D. The ends of the piezoelectric bases 90A through 90D opposite to the ends having the respective rotary heads HA through HD, are fixed to the rotary body. The piezoelectric bases 90A through 90D are equally spaced apart by an angular separation of 90�. In FIG. 7, those parts which are the same as those corresponding parts in FIG. 1 are designated by the same reference numerals. As will be described later on in the specification, the rotary body 11 is also mounted with a dummy piezoelectric base 91.
The expanding and contracting directions of the piezoelectric base 90 and the displacing directions of the rotary head 101, are in the radial direction of the rotary body 11 as may be seen from FIG. 7. Further, the expanding and contracting directions of the piezoelectric base 90 and the displacing directions of the rotary head 101, are perpendicular to the magnetic surface of the magnetic tape 12 which is wrapped around the outer peripheral surface of the rotary body 11 over an angular range larger than 270� inclusive of the overlap recording part (in the order of 10� before and after the recording or reproducing time period of one field) under the guidance of the guide poles 13a and 13b. Thus, when the piezoelectric base 90 expands, the rotary head 101 projects from the outer peripheral surface of the rotary body 11 towards the magnetic surface of the magnetic tape 12, and makes positive contact with the magnetic tape 12. On the other hand, when the piezoelectric base 90 contracts, the rotary head 101 is drawn back towards the center of the rotary body 11.
As shown in FIG. 8A, the electrode 95a of the electrode part on the piezoelectric base 90 is grounded, while the other electrode 95b is coupled to an output terminal 100 of a feedback amplifier 98. On the other hand, the electrode 96a of the electrode part 96 on the piezoelectric base 90 is grounded, while the other electrode 96b is coupled to an input terminal of the amplifier 98. Hence, the surface elasticity wave transmitted from the electrode part 95 to the electrode part 96, is converted into an electrical signal in the electrode part 96. This electrical signal is passed through the amplifier 98 and is produced through the output terminal 100. In addition, this electrical signal is also positively fed back to the electrode part 95. Accordingly, the piezoelectric base 90 shown in FIGS. 8A and 8B not only constitutes a head displacing mechanism for the rotary head 101, but also constitutes an oscillator which uses the surface elasticity wave of the piezoelectric base 90. An oscillation frequency fo of this oscillator is determined by a ratio of a transmission speed VS of the surface elasticity wave and a wavelength λo of the surface elasticity wave. For example, when pitches P of the electrode parts 95 and 96 are equal to 15 μm, the wavelength λo of the surface elasticity wave becomes equal to 30 μm. Since the transmission speed VS of the surface elasticity wave is approximately equal to 3�103 m/sec, the oscillation frequency fo becomes approximately equal to 100 MHz by calculating the ratio VS/λo.
The oscillation frequency fo changes depending on the expanding and contacting quanitities of the piezolelectric base 90, that is, depending on a distance L between the electrode parts 95 and 96. By taking into account the diameter D of the rotary body 11, the distance L is set to 10 mm, for example. A sensitivit KSAW of the oscillation frequency change of the piezoelectric base 90 itself, can be described by a formula KSAW =(Δf-fo)(ΔL/L), where Δf is the frequency change and ΔL is the change in the distance L. Hence, when the piezoelectric base 90 having the sensitivity KSAW of 10 undergoes an expansion or contraction of 1 μm, for example, the frequency change Δf becomes equal to 100 kHz from the above formula. Thus, when the head projecting quantity changes by 1 μm, there is a frequency change of 100 kHz. When the head position control pulse signal (voltage) is applied to the input terminal 99 shown in FIGS. 8A and 8B, an electrical field is generated between the electrode parts 95 and 96, and the piezoelectric base 90 becomes distorted by this electrical field. As a result, the piezoelectric base 90 expands or contracts in a direction parallel to an imaginary line connecting the electrodes 95 and 96, and the rotary head 101 is accordingly displaced so as to perpendicularly make contact with the magnetic surface of the magnetic tape 12 or perpendicularly separate from the magnetic surface of the magnetic tape 12. In addition, the output oscillation frequency which is obtained through the output terminal 100 changes, due to the distortion in the piezoelectric base 90.
Accordingly, in the embodiment shown in FIG. 9, measures are taken so that the desired head projecting quantity is obtainable. In other words, since the surface elasticity wave changes proportionally to the distortion in the piezoelectric base 90, the sensitivity KSAW (=(Δf/fo)/(ΔL/L)) of the oscillation frequency change of the piezoelectric base 90 itself is obtained, and the peak value of the head position control pulse signal applied to the input terminal 99 is compensated based on the oscillation frequency change. In addition, in order to perform a temperature compensation, the dummy piezoelectric base 91 is mounted on the rotary body 11 as shown in FIG. 7, and the temperature compensation is performed by use of the oscillation frequency change of the dummy piezoelectric base 91. The construction of the dummy piezoelectric base 91 is basically the same as the constructions of the other four piezoelectric bases 90A through 90D (90), except in that the electrodes 97 and 102 are not provided on the dummy piezoelectric base 91.
The application of the position control apparatus according to the present invention is not limited to the 4-head type VTR described heretofore. The position control apparatus according to the present invention may be applied to any recording and reproducing apparatus in which a magnetic tape is wrapped around the outer peripheral surface of a rotary body over a predetermined angular range which is greater than 180�, two or more rotary heads among a plurality of rotary heads mounted on the rotary body simultaneously scan over the magnetic tape at one time, and the recording and reproduction are carried out by use of the plurality of rotary heads. In addition, the head projecting quantities may be controlled by using output oscillation frequency signals of oscillators which use surface elasticity waves of piezoelectric bases.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4251838 *Mar 2, 1979Feb 17, 1981Sony CorporationAuto-tracking control system for use in apparatus for reproducing a video signal recorded in successive parallel tracks on a recording mediumFR2536893A1 * Title not availableJPS581844A * Title not availableJPS5473616A * Title not available* Cited by examinerNon-Patent CitationsReference1 *Patent Abstracts of Japan, vol. 6, No. 18, Feb. 2, 1982, (P 100) (896).2Patent Abstracts of Japan, vol. 6, No. 18, Feb. 2, 1982, (P-100) (896).3 *Patent Abstracts of Japan, vol. 6, No. 92, May 29, 1982, (P 119) (970).4Patent Abstracts of Japan, vol. 6, No. 92, May 29, 1982, (P-119) (970).5 *Patent Abstracts of Japan, vol. 7, No. 113, May 18, 1983, (P 197) (1258).6Patent Abstracts of Japan, vol. 7, No. 113, May 18, 1983, (P-197) (1258).* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5191491 *Nov 9, 1990Mar 2, 1993Exabyte CorporationMethod and apparatus for reading distorted helical stripesUS5206770 *Jul 10, 1992Apr 27, 1993Matsushita Electric Industrial Co., Ltd.Apparatus with arrangement for keeping rotating head in optimal contact with magnetic tapeUS5255140 *Dec 28, 1989Oct 19, 1993Samsung Electronics Co., Ltd.VCR magnetic recording head for both digital and VHS formatUS5289323 *Feb 14, 1992Feb 22, 1994Datatape IncorporatedAutotracking for a helical scan magnetic tape recorderUS5373404 *Oct 26, 1993Dec 13, 1994Kabushki Kaisha Sankyo Seiki SeisakushoHelical scan type rotary head drum unitUS6246551Oct 20, 1998Jun 12, 2001Ecrix CorporationOverscan helical scan head for non-tracking tape subsystems reading at up to 1X speed and methods for simulation of sameUS6307701Oct 20, 1998Oct 23, 2001Ecrix CorporationVariable speed recording method and apparatus for a magnetic tape driveUS6308298Nov 16, 1998Oct 23, 2001Ecrix CorporationMethod of reacquiring clock synchronization on a non-tracking helical scan tape deviceUS6364234Mar 10, 2000Apr 2, 2002Michael Donald LangianoTape loop/slack prevention method and apparatus for tape driveUS6367047Oct 20, 1998Apr 2, 2002EcrixMulti-level error detection and correction technique for data storage recording deviceUS6367048Nov 16, 1998Apr 2, 2002Mcauliffe RichardMethod and apparatus for logically rejecting previously recorded track residue from magnetic mediaUS6381706Oct 20, 1998Apr 30, 2002Ecrix CorporationFine granularity rewrite method and apparatus for data storage deviceUS6421805Nov 16, 1998Jul 16, 2002Exabyte CorporationRogue packet detection and correction method for data storage deviceUS6603618Nov 16, 1998Aug 5, 2003Exabyte CorporationMethod and system for monitoring and adjusting tape position using control data packetsUS6624960Mar 10, 2000Sep 23, 2003Exabyte CorporationCurrent sensing drum/cleaning wheel positioning method and apparatus for magnetic storage systemUS7277842Apr 3, 2001Oct 2, 2007Tandberg Data CorporationOverscan helical scan head for non-tracking tape subsystems reading at up to 1X speed and methods for simulation of sameUS20010022711 *Apr 3, 2001Sep 20, 2001Blatchley Michael A.Overscan helical scan head for non-tracking tape subsystems reading at up to 1X speed and methods for simulation of same* Cited by examinerClassifications U.S. Classification360/75, 360/77.16, G9B/15.08, G9B/15.018, G9B/20.061, G9B/21.021, G9B/21.024, G9B/5.175International ClassificationG11B15/14, G11B21/18, G11B15/61, G11B5/588, G11B20/22, G11B21/12, G11B5/53, H01L41/09, G11B5/54Cooperative ClassificationG11B20/22, G11B15/61, G11B21/12, G11B5/531, G11B15/14, G11B21/18, H01L41/0825European ClassificationH01L41/08S, G11B21/12, G11B21/18, G11B20/22, G11B15/14, G11B5/53D, G11B15/61Legal EventsDateCodeEventDescriptionJul 31, 1984ASAssignmentOwner name: VICTORY COMPANY OF JAPAN LTD. NO 12, 3-CHOME, MORIFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SATO, FUMIAKI;REEL/FRAME:004295/0750Effective date: 19840726Sep 25, 1989FPAYFee paymentYear of fee payment: 4Sep 20, 1993FPAYFee paymentYear of fee payment: 8Sep 22, 1997FPAYFee paymentYear of fee payment: 12RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services