Television receiver comprising an optical filter

Claim 1

FOR USE IN CONNECTION WITH A TELEVISION RECEIVER HAVING A PICTURE TUBE AND A VIEWING SCREEN PRODUCING A PRINCIPAL RADIATION WITH AT LEAST TWO PRINCIPAL SPECTRAL MAXIMA EXCITED UPON THE ASSOCIATED FLUORESCENT LAYER OF SAID VIEWING SCREEN BY THE ELECTRON BEAM OF THE TUBE, AN OPTICAL FILTER DISPOSED IN THE PATH OF RADIATION EMANATING FROM SAID SCREEN AND CONSTRUCTED TO PASS PREDOMINANTLY THE WAVELENGTHS OF SAID PRINCIPAL RADIATION OF SAID FLUORESCENT SCREEN WHILE WEAKENING RADIATION OF OTHER WAVELENGTHS AND RADIATION CONTAINED IN EXTRANEOUS LIGHT SOURCES IMPINGING UPON SAID SCREEN, SAID FILTER HAVING A TRANSMISSIBILITY CHARACTERISTIC INCLUDING A MAXIMUM GENERALLY CORRESPONDING TO A SPECTRAL MAXIMUM OF SAID SCREEN BUT OCCURRING AT A WAVELENGTH DISPLACED THEREFROM WHEREBY THE TRANSMISSIBILITY OF SAID FILTER EFFECTS WITHIN THE WAVELENGTH OF ONE EMISSION MAXIMUM SHIFTING OF THE COLOR TINT FOR A DESIRED AMOUNT IN THE DIRECTION OF ANOTHER EMISSION MAXIMUM.