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US 4,528,448 AGranted
Plane linear grating for optically encoding information
AssigneeBenson, Inc.
InventorDavid E. Doggett
Life of this patent
Estimating the term…
Abstract
An encoding disk including a multiplicity of linear gratings placed accurately on the disk to diffract a light beam to a fixed point in space accurately does so independently of the centering of the disk on its axis of rotation.
Claims13
A device for decoding the angular position of a rotating member comprising:
- a substrate of material rotatably mountable in a position other than its center to rotate about a defined axis of rotation in a predetermined relationship to the rotation of said rotating member;
- at least one linear diffraction grating formed on or in said substrate;
- means for directing incident radiation onto said substrate at a position to impinge upon said at least one linear diffraction grating during rotation of said substrate, whereby at least a portion of said incident radiation is diffracted by said linear diffraction grating through an elongated path during rotation of said substrate;
- detector means positioned at a discrete location along a segment of said elongated path to receive said diffracted portions of said incident radiation and produce an output signal in response thereto, whereby the angular position of said rotating member is decoded independent of the centration of said axis of rotation through said substrate.
1 more element
Dependencies are inferred from the claim text.