Patent US3695767A successfully refreshed from Google Patents.
US3695767A
Expired / Lapsed
US
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Apparatus for measuring magnetic head angle of a magnetic disc file
Assignee: Unisys Corp
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Filing: 1970-11-18
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Granted: 1972-10-03
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Expires: 1990-11-18
Abstract
Abstract There is described apparatus for measuring the flying angle of a pneumatically supported magnetic head relative to a recording disc in which a laser beam is directed toward a transparent rotating disc. The beam is split by the rotating disc into a reflected beam and an incident beam which falls on an adjacent surface of the recording head associated with the disc. A second reflected beam is formed by the recording head. By measuring the distance between the two reflected beams on a screen, the angle between the disc and the magnetic head can be determined.
Inventors
- 👤 David J George
- 👤 Wilfred D Iwan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:37
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/60; G11B5/6005; G11B5/54
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
124 words
The method of measuring the flying angle between a rotating recording disc and a magnetic head held in spaced relation to the disc by a cushion of air, the method comprising the steps of: rotating the disc past the head to form an air cushion between the disc and the head, directing a collimated incident beam of light toward the disc at a point adjacent the head, a portion of the beam passing through the disc and striking the adjacent air cushion forming surface of the head, forming separate images of the light reflected from the surface of the disc and reflected from the surface of the head at the same light path distance from the disc, and measuring the separation between the images.
Claim 2
Independent Claim
124 words
The method of measuring the flying angle between a rotating recording disc and a magnetic head held in spaced relation to the disc by a cushion of air, the method comprising the steps of: rotating the disc past the head to form an air cushion between the disc and the head, directing a collimated incident beam of light toward the disc at a point adjacent the head, a portion of the beam passing through the disc and striking the adjacent air cushion forming surface of the head, forming separate images of the light reflected from the surface of the disc and reflected from the surface of the head at the same light path distance from the disc, and measuring the separation between the images.
Claim 3
Dependent Claim
29 words
The method of claim 1 wherein said separate images are formed in synchronism with the rotation of the disc during a small fraction of each revolution of the disc.
Claim 4
Dependent Claim
200 words
Apparatus for measuring the flying angle of a magnetic head relative to a rotating recording disc where the head has a flat surface forming an air bearing with the disc surface, comprising a disc made of transparent material, a source of a collimated light beam, means directing the light beam from the source through the transparent disc toward said flat surface of the head adjacent the disc at a small angle of incidence from the normal relation to the surface of the disc, a portion of the beam being reflected by the disc along a first angle of reflection, a portion of the beam being reflected by the surface of the head at a second angle of reflection, a screen positioned a known distance from the adjacent surfaces of the head and disc, the distance being very large relative to the spacing between the disc and said surface of the head, and means directing the two reflected portions of the beam at the screen to form spaced images from the reflected beam portions on the screen, the distance between the images being a direct measure of the angle between the surface of the head and the surface of the disc.
Claim 5
Dependent Claim
200 words
Apparatus for measuring the flying angle of a magnetic head relative to a rotating recording disc where the head has a flat surface forming an air bearing with the disc surface, comprising a disc made of transparent material, a source of a collimated light beam, means directing the light beam from the source through the transparent disc toward said flat surface of the head adjacent the disc at a small angle of incidence from the normal relation to the surface of the disc, a portion of the beam being reflected by the disc along a first angle of reflection, a portion of the beam being reflected by the surface of the head at a second angle of reflection, a screen positioned a known distance from the adjacent surfaces of the head and disc, the distance being very large relative to the spacing between the disc and said surface of the head, and means directing the two reflected portions of the beam at the screen to form spaced images from the reflected beam portions on the screen, the distance between the images being a direct measure of the angle between the surface of the head and the surface of the disc.
Claim 6
Dependent Claim
16 words
The apparatus of claim 3 wherein the source of the collimated light beam is a laser.
Claim 7
Dependent Claim
40 words
The apparatus of claim 3 further including a mask between the light source and the disc, the mask having an opening therein for passing the light beam from the source to the magnetic head, the mask rotating with the disc.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-03 | 1976-04-03 | 1976-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-03 | 1980-04-03 | 1980-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-03 | 1984-04-03 | 1984-10-03 | $7700.00 | Window Closed / Lapsed |