Multi-color, single gun, single grid/cathode beam index CRT display system

A beam indexing system for a cathode ray tube, said tube having a plurality of vertical disposed color stripe phosphor triads upon which the beam of said tube is caused to impinge, comprising means for generating respective binary addresses corresponding to linear x and y beam positions definitive of a repetitive raster scan of a plurality of horizontal lines defining a raster frame, means for generating a reference pulse train comprising a train of pulses corresponding to successive x addresses along a predetermined single-line defining sequence of x addresses definitive of video red on-time intervals for that horizontal line, a sample beam detecting means responsive to impingement of said beam on successive ones of said red phosphor stripes in said color stripe triads along said predetermined single horizontal line to generate a beam sample pulse train;

• means for comparing the horizontal displacement of a beam center defining one of said beam sample pulses with a center defining one of said video reference pulses to develop a phase error correction signal;
• means comparing the horizontal displacement between successive pairs of respective ones of sample and reference pulses to develop a timing error signal for each said successive pulse pair, means for storing successive ones of said timing error signals at binary addresses corresponding to the linear x position sweep address for that pulse pair, means responsive to each x address in successive lines of said frame to address the stored tuning error signal at that address, means for adding said addressed timing error signal to the linear x address signal, and means for adding a correction signal defined by said phase error signal to the x deflection signal for said beam during successive ones of raster lines for the remainder of said frame.

In a multicolor cathode ray tube display system wherein said tube comprises a single gun and single beam, said tube having a plurality of paralleled color stripe phosphor triads on the face thereof and means for developing a raster deflection system for said single beam whereby said beam is caused to be scanned perpendicular to said phosphor triads across the tube face;

• a clock pulse source, means to apply said clock pulse source to a binary counting means to develop clock synchronous linear horizontal and vertical digital counts collectively definitive of x and y deflection signals to effect a raster scan of said beam;
• means for developing a first correction signal for said horizontal and vertical digital counts as a function of the deflection angle of the beam from a center beam position where said beam is normal to the face of said cathode ray tube;
• means for developing a clock-defined reference pulse train the pulses of which correspond to successive horizontal count address defined positions of successive ones of red stripes of each of said stripe triads, means for developing a sample detected pulse train respective pulses of which correspond to successive beam impingement upon red stripes of said stripe triads, means for developing a second correction signal proportional to the phase displacement between a center one of said reference red pulses and a center one of said detected pulses;
• means for developing a third correction signal proportional to the time discrepancy between like sequential ones of said reference and detected red pulses, means for storing said third correction signals at the horizontal digital count defined address for that pulse-pair;
• first means for summing each successive horizontal binary count with that one of said third correction signals developed for that horizontal count;
• first means for multiplying said vertical digital count by said first correction signal and applying the product to effect vertical deflection of said cathode ray tube beam;
• second means for multiplying said horizontal binary count by the output of said first means for summing;
• and second means for summing the output of said second means for multiplying with said second correction signal and applying the product to effect horizontal deflection of said cathode ray tube beam.