Patent ID: 6157119
Filing Date: 2000-12-05
Classification: H01J

Abstract:
A shadow mask for use with a generally rectangular, curved display screen in a color cathode ray tube (CRT) having a plurality of electron beams arranged in an inline array, said display screen having electron beam sensitive phosphor elements on an inner surface thereof for providing a video image, said shadow mask comprising:a thin metal foil generally rectangular in shape and generally spherical in curvature, wherein said thin metal foil is disposed in closely spaced relation to the inner surface of the display screen and includes a horizontal X-axis and a vertical Y-axis each extending through a center of said metal foil and toward opposed lateral edges and opposed upper and lower edges thereof, respectively;means defining a plurality of spaced apertures in said metal foil arranged in vertical columns and horizontal rows, with apertures in one row being in different columns than are apertures in adjacent rows and with the vertical spacing between adjacent apertures within a column being the vertical pitch (P.sub.v) of the apertures, wherein each electron beam is directed through selected ones of said apertures and is incident upon selected ones of said phosphor elements on the display screen to provide one of the primary colors of red, green or blue of the video image, and wherein P.sub.v of said apertures decreases monotonically in proceeding from the Y-axis to a lateral edge of said metal foil and increases monotonically in proceeding from the X-axis to an upper or lower edge of said metal foil,wherein P.sub.v is given by the following expression:P.sub.v (X,Y)=P.sub.vo .times.F(X).times.G(Y)where P.sub.vo =vertical pitch of apertures at Y=0 and X=0;F(X)=1+a.sub.1 X.sup.2 +a.sub.2 X.sup.4 +a.sub.3 X.sup.6 +. . . ;G(Y)=1+b.sub.1 Y.sup.2 +b.sub.2 Y.sup.4 +b.sub.3 Y.sup.6 +. . . ;a.sub.1, a.sub.2, a.sub.3, . . . are real number constants less than zero in value; andb.sub.1, b.sub.2, b.sub.3, . . . are real number constants greater than zero in value.