Ambient light trapping filter for cathode ray tubes

Claim 1

THE COMBINATION OF A VIEWING SCREEN FROM WHICH IMAGE LIGHT EMANATES WITH A SPACE LATTICE TYPE AMBIENT LIGHT TRAPPING FILTER MOUNTED IN FRONT OF AND IN PROXIMITY TO SAID SCREEN, THE GENERAL PLANES OF SAID SCREEN AND SAID FILTER BEING SUBSTANTIALLY PARALLEL; SAID SCREEN, WHEN ACTIVATED, PRESENTING A SERIES OF ALTERNATING LIGHT AND DARK HORIZONTAL LINES CONSTITUTING A HORIZONTAL RASTER; SAID FILTER COMPRISING A THIN, TRANSPARENT PANEL BEARING, THROUGHOUT ITS THICKNESS, A PLURALITY OF DEPTHWISE SPACED TIERS OF FILTER ELEMENTS, EACH IN THE FORM OF A LIGHT TRAPPING GRID PATTERN OF HIGHLY LIGHT ABSORBENT MATERIAL; SAID GRID PATTERN CONSISTING OF NARROW LINES ARRANGED TO FORM A MULTIPLICITY OF ADJOINING POLYGONAL FRAMES, EACH ENCLOSING A TRANSPARENT AREA SERVING AS A LIGHT PASSAGE; EACH FRAME BEING ORIENTED SO THAT ALL OF ITS SIDES ARE AT SUFFICIENT ANGLES TO THE HORIZONTAL LINES OF THE RASTER PATTERN TO PREVENT FORMATION OF A MOIRE EFFECT BETWEEN THE GRID LINES AND THE RASTER LINES; THE LIGHT PASSAGES OF SUCCESSIVE GRID PATTERNS BEING IN DEPTHWISE REGISTRY TO PROVIDE A MULTIPLICITY OF DEPTHWISE DIRECTED VIEWING CELLS; SAID DEPTHWISE SPACED GRID LINES ACTING INDIVIDUALLY TO TRAP AND ABSORB OFF-AXIS AMBIENT LIGHT RAYS ENTERING SAID CELLS AT VARIOUS ANGLES AND STRIKING SAID GRID LINES AT NEARLY NORMAL ANGLES.