Trapezoidal smooth grooves for video disc
AssigneeRCA Corporation
InventorsRichard William Nosker, Leonard Pincus Fox
Life of this patent
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Abstract
A method of forming a disc having an information recording groove of regular cross-sectional shape by forming a preliminary spiral groove of trapezoidal cross-section in a disc having a relatively flat surface, and then flowing an excess of viscous material on the groove surface of the disc while rotating the disc rapidly and long enough to flow off the excess viscous material so as to leave a continuous coating of viscous material over the surface of the disc, the trapezoidal regions being covered by a coating having a relatively constant radius of curvature.
Claims3
A disc record suitable for recording information thereon comprising:
- a disc substrate having a spiral groove of trapezoidal cross-sectional shape formed therein;
- and
- a surface material coating said trapezoidal spiral groove, said coated spiral groove having a surface of regularly curved cross-sectional shape including inflection points on each wall of said coated groove located closer to the peaks than to the valley of said coated groove, the surface curvature in said valley between said inflection points substantially corresponding to an arc of a circle.
Dependencies are inferred from the claim text.