US 6,151,191 AGranted

Helical scan recording with a self-acting negative air bearing

AssigneeMassachusetts Institute of Technology

InventorsSinan Muftu, Hans F Hinteregger

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Abstract

A flat head and a tape transport arrangement impart a wrap angle to the tape at the upstream corner of the head. The wrap angle, corner sharpness and tape stiffness are sufficient to cause a moving tape to form a hollow bump at the upstream corner, thereby creating a hollow into which entrained air can expand, causing a subambient pressure within and downstream of the bump. This pressure keeps the tape in contact with the head. It is created without the need for a groove or complex pressure relief slot(s). No contact pressure arises at the signal exchange site due to media wrap. The highest contact pressures are developed at a wrapped upstream corner. For a tape drive, traveling in both forward and reverse, the wrap can be at both the upstream and downstream (which is the "reverse upstream") corners. Heads that are not flat can also be used, if the wrap angle relative to a main surface is sufficient and not too large. The wrapped head can also be used with rotating media, such as disks (floppy and hard) and rotating heads, such as helical wound heads for video recording. Multiple flat tape bearing surfaces can be separated by grooves and/or angles. Each flat can carry heads along one or more gap lines. Multiple adjacent narrow tracks can thus be written for extreme high track density recording.

Claims10

Dependent claims

A helical scan head assembly for use with magnetic tape that is wrapped helically around a rotating drum of said head assembly, and moves, relative to a stationary reference in the same direction that said drum is rotating, but at a slower speed, so that, from the perspective of the rotating drum, the tape is observed to be moving along a circumferential machine dimension from an upstream direction to a downstream direction, said head assembly comprising:

a. a first circular cylindrical drum that is rotatable around an axis;
b. fixed to said rotatable drum, a head, having a signal exchange surface that comprises:
i. a signal exchange site;
ii. an upstream corner upstream of said signal exchange site;
and
iii an upstream signal exchange surface, defined by an upstream main signal exchange surface curve, located along said machine dimension between said upstream corner and said signal exchange site, which signal exchange surface meets said upstream corner at a main slope discontinuity and has an upstream main tangent .tau..sub.main at said main slope discontinuity;
and
said head being located at a radial position and said upstream corner being sufficiently sharp and said upstream main tangent being such that, if any said tape is wrapped helically around said drum and contacts said head and said drum is rotating relative to said tape, then;
i. an upstream portion of said tape contacts said upstream corner;
ii. a portion of said tape that is downstream and adjacent to said upstream corner contacting portion, is spaced away from said signal exchange surface adjacent to and downstream from said main slope discontinuity, forming a hollow bump between said tape and said signal exchange surface;
and
iii. a portion of said tape downstream from and adjacent said hollow bump contacts said signal exchange surface along the full extent from said bump to and including said signal exchange site.

9 more elements

Dependencies are inferred from the claim text.