Apparatus for making electro-luminescent screens for color cathode-ray tubes of continuous phosphor stripes

Claim 1

Apparatus for making an electroluminescent screen for a color cathode-ray tube comprising a plurality of separate color fields of continuous vertical stripes disposed on the viewing panel of said electroluminescent screen, each of said color fields being defined by exposing said panel to light from a linear light source through a concave shadow mask attached to said panel, said shadow mask having a number of beam-passable apertures arranged in rows parallel with each other, the light projected from said light source through said mask apertures onto said panel producing a developable image on said panel, the apertures along the length of each of said rows being separated from each other by beam-intercepting bridge portions, comprising: a. means for locating said light source at a predetermined position on the opposite side of said shadow mask for irradiating said shadow mask and projecting light from said source on an area of said panel in a pattern comprising images defined by the apertures of said shadow mask, said light source having a sufficient effective length in the lengthwise direction of the rows of the apertures to produce on said panel an image of each aperture so expanded in the lengthwise direction of the rows of the apertures as to overlap the image of each adjacent aperture in the lengthwise direction of each of the rows; b. means for limiting the irradiated area on the shadow mask to a length covering a portion of the length of the rows of the apertures, the apertures within said lighted area having a nearly equal angle of inclination with respect to the vertical axis of said screen; c. means cooperating with said limiting means for moving said irradiated area on the shadow mask along the length of the rows of the apertures; and, d. means for controlling the inclination of said light source to keep the longitudinal axis thereof substantially parallel to a line drawn tangent to the shadow mask apertures in the irradiated area.