| 摘要 |
An apertured shadow mask in a color cathode ray tube (CRT) serves as a color selection electrode in permitting each of the three electron beams to be incident only upon its associated color-producing phosphor elements on the CRT's display screen. The apertures are arranged in vertical columns and horizontal rows in the shadow mask with aperture spacing defined by a vertical pitch (Pv) i.e., the vertical spacing between adjacent apertures within the same vertical column where the apertures in one row are in different columns than the apertures in adjacent rows, and a horizontal pitch (Ph), i.e., the horizontal spacing between adjacent apertures in the same horizontal row. To increase the color purity adjustment margin particularly in the corners of the display screen while still maintaining sufficient vertical spacing between adjacent phosphor dot color trios for a high degree of video image resolution, Pv is defined in terms of a monotonic decreasing function in the horizontal direction and a monotonic increasing function in the vertical direction as follows:Pv(X,Y)=PvoxF(X)xG(Y)where Pvo=vertical pitch of apertures at Y=0 and X=0; F(X)=1+a1X2+a2X4+a3X6+. . . ; G(Y)=1+b1Y2+b2Y4+b3Y6+. . . ; a1, a2, a3, . . . are constants and a1<0; and b1, b2, b3, . . . are constants and b1>0.
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