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US 4,047,204 AGranted
Variable interlace display
AssigneeAmerican Optical Corporation
InventorJames J. Gold
Life of this patent
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Abstract
Apparatus for utilization in driving a raster-type display, such as is used in the familiar television system for producing a selectable (according to a predetermined group) of raster formats of different raster interlace rates.
Claims3
In apparatus for varying according to a predetermined selection range the interlace rate of a rastered display, such as on a cathode ray tube including a horizontal deflection control circuit and a vertical deflection control circuit connected respectively to a horizontal drive and a vertical drive, the improvement comprising:
- variable oscillation means to generate a principal frequency to drive said horizontal and vertical drives, said frequency being a multiple of the horizontal deflection rate and the predetermined interlace rates;
- horizontal counter means for reducing the oscillation frequency to a frequency equal to the horizontal rate for the predetermined interlace rate;
- vertical counter means for reducing the oscillation frequency equal to the vertical rate for the predetermined interlace rate;
- and control means for said vertical counter and said oscillation means which cause the quotient of said horizontal rate divided by said vertical rate to be a fractional number, the fractional portion of which represents the desired interlace rate.
1 more element
Dependencies are inferred from the claim text.