公开(公告)号：FR2290724A1

公开(公告)日：1976-06-04

申请号：FR7529325

申请日：1975-09-19

Applicant: IBM

Inventor： HART GARY A

IPC: H04N5/7826 ,  G05D3/12 ,  G05D13/62 ,  G11B15/18 ,  G11B15/467 ,  G11B15/60 ,  G11B15/61 ,  G11B5/58

Abstract: 1474012 Automatic control of position INTERNATIONAL BUSINESS MACHINES CORP 14 Aug 1975 [7 Nov 1974] 33824/75 Heading G3R [Also in Division G5] In magnetic tape apparatus, a rotating head scans a pair of servo marks on the tape which are angularly inclined to each other. The system adjusts the post of the tape accordingly so as to correct alignment between the head and data tracks on the tape. In the embodiment shown, the servo marks 38, 111 correspond to read and erase gaps 101, 103 of the rotating head 13. As each gap passes a respective mark, a threshold circuit 124 produces an output 136 or 138. After a time delay on one output, if necessary, counter 142 counts clockpulses from 146 for the time difference between these outputs, which difference depends upon the head-servo mark i.e. data track alignment. The output of counter 142 is compared with a reference number, the result at 33 being used to adjust the tape position so as to correct any alignment error. The clock or reference number may be varied in accordance with tape or head speed. The servo tracks can be appplied, as Fig. 5, (not shown) to both ends of a data track, so as to allow for measurement and correction of skew between the head path and the data track. The system which may be digital or analogue, is used in apparatus as Fig. 1 (not shown), with tape tension control using a vacuum buffer, the tape being moved in steps, with the measurement or control of alignment before the read-write functions being made with the tape stationary or moving slowly past the rotating head.

公开(公告)号：CA1064611A

公开(公告)日：1979-10-16

申请号：CA235839

申请日：1975-09-18

Applicant: IBM

Inventor： HART GARY A

IPC: H04N5/7826 ,  G05D3/12 ,  G05D13/62 ,  G11B15/18 ,  G11B15/467 ,  G11B15/60 ,  G11B15/61 ,  G11B21/10 ,  G11B21/04

Abstract: A SERVO INFORMATION PATTERN FOR ROTATING HEAD MAGNETIC TAPE UNIT INDEPENDENT OF AMPLITUDE The position of a length of magnetic recording tape, adjacent a rotating head device, is servo controlled to accurately position a transverse tape data track in alignment with the head path. The tape includes two distinctive servo indicia. The first indicia is a magnetic flux transition which is oriented substantially parallel to the edge of the tape. The second indicia is a magnetic flux transition which is oriented at an angle to the edge of the tape. This second indicia is parallel to the magnetic flux transitions which comprise the data track, and said distinctive second indicia is provided for each data track to define the physical location thereof. The rotating head includes two head gaps, one of which is parallel to the first indicia, and the other of which is parallel to the second indicia. The head gaps angular relationship insures that the respective head gaps will read only that indicia which is parallel therewith. The time of crossing of each head gap with its readable indicia is a measure of head-track to data-track alignment.

公开(公告)号：CA949656A

公开(公告)日：1974-06-18

申请号：CA135661

申请日：1972-02-28

Applicant: IBM

Inventor： HART GARY A ,  WILSON MELVIN G

IPC: G06G7/24 ,  G06K9/20 ,  H03F1/56

Abstract: Small current signals (0.5 ua and less) such as the output of a photodiode are direct current coupled to a preamplifier which also passes an impedance reducing injection current to a pair of amplifiers. A voltage output proportional to the logarithm of the signal current is produced by passing the amplified current through a log producing junction of a transistor. However, to produce the logarithm function accurately, the injected or impedance reducing current is precisionally removed so that only a very minute portion (one part out of 5000) passes through the log producing junction.

公开(公告)号：CA1074443A

公开(公告)日：1980-03-25

申请号：CA321218

申请日：1979-02-08

Applicant: IBM

Inventor： HART GARY A

IPC: G11B5/56 ,  G11B15/18

Abstract: HEAD TO TRACK ALIGNMENT IN A ROTATING HEAD MAGNETIC TAPE UNIT The position of a length of magnetic recording tape, adjacent a rotating head device is servo controlled to accurately position a transverse tape data track in alignment with the head path. The tape includes a longitudinal servo track. A portion of the servo track is read by the rotating head as it sweeps transversely across the tape. The servo track is formed as a constant frequency pattern having periodic sync marks which define the center of a data track. The rotating head signal constitutes a clock which is used to drive an up/down counter as the head sweeps across the servo track. The counter's counting state changes as the head sweeps the servo track, such that the residual count, which remains after the head leaves the servo track, is a measure of the magnitude and direction of head-to-track alignment.

公开(公告)号：CA1074442A

公开(公告)日：1980-03-25

申请号：CA321217

申请日：1979-02-08

Applicant: IBM

Inventor： HART GARY A

IPC: G11B5/56 ,  G11B15/18

Abstract: HEAD TO TRACK ALIGNMENT IN A ROTATING HEAD MAGNETIC TAPE UNIT The position of a length of magnetic recording tape, adjacent a rotating head device is servo controlled. to accurately position a transverse tape data track in alignment with the head path. The tape includes a longitudinal servo track. A portion of the servo track is read by the rotating head as it sweeps transversely across the tape. The servo track is formed as a constant frequency pattern having periodic sync marks which define the center of a data track. The notating head signal constitutes a clock which is used to drive an up/down counter as the head sweeps across the servo track. The counter's counting state changes as the head sweeps the servo track, such that the residual count, which remains after the head leaves the servo track, is a measure of the magnitude and direction of head-to-track alignment.

公开(公告)号：CA1071325A

公开(公告)日：1980-02-05

申请号：CA212824

申请日：1974-11-01

Applicant: IBM

Inventor： HART GARY A

IPC: H04N5/7826 ,  G05D13/62 ,  G11B5/48 ,  G11B15/18 ,  G11B15/467 ,  G11B15/60 ,  G11B15/61 ,  G11B21/10

Abstract: HEAD TO TRACK ALIGNMENT IN A ROTATING HEAD MAGNETIC TAPE UNIT The position of a length of magnetic recording tape, adjacent a rotating head device is servo controlled to accurately position a transverse tape data track in alignment with the head path. The tape includes a longitudinal servo track. A portion of the servo track is read by the rotating head as it sweeps transversely across the tape. The servo track is formed as a constant frequency pattern having periodic sync marks which define the center of a data track. The rotating head signal constitutes a clock which is used to drive an up/down counter as the head sweeps across the servo track. The counter's counting state changes as the head sweeps the servo track, such that the residual count, which remains after the head leaves the servo track, is a measure of the magnitude and direction of head-to-track alignment.

公开(公告)号：CA1039846A

公开(公告)日：1978-10-03

申请号：CA186740

申请日：1973-11-26

Applicant: IBM

Inventor： HART GARY A ,  KOLLAR ERNEST P ,  LUHRS OTTO R

IPC: G11B15/00 ,  G11B15/18 ,  G11B15/43 ,  G11B15/60 ,  G11B15/61 ,  G11B27/10 ,  G11B27/19 ,  H04N5/78 ,  H04N5/7826 ,  G11B27/30

Abstract: METHOD AND APPARATUS FOR SENSING RELATIVE POSITION BETWEEN HEAD AND TRACK IN TRANSVERSE MAGNETIC RECORDING When transverse or slant tracks are recorded on magnetic tape, control of the position of the transverse transducer relative to the transverse track is critical in reading out the information in the transverse tracks. This control has facets--finding a predetermined slant track and aligning the transducer and the slant track. The transverse track position sensing system shown herein provides control signals for these two functions. The position sensing is accomplished by use of a fixed head positioned relative to the path of the transverse transducer. The fixed head scans an area of the magnetic tape where each transverse track ends. Signals from the fixed head are analyzed to determine the track end position of each slant or transverse track. This information is, in turn, operated on to derive tape movement control information for the purposes of finding a slant track and aligning the track with the path of the slant track head. For greater accuracy in alignment, a second fixed head is provided for monitoring the other end of the transverse track to determine the angle of the slant track relative to the path of the slant track head. If the angles are not the same, corrections may be made by adjusting tape movement.