Apparatus for making electroluminescent screens for color cathode ray tubes

Claim 1

An apparatus for preparing a developable pattern comprising continuous vertical stripes on a panel for a cathode ray tube having a film comprising photosensitive material having a predetermined response to incident light, said panel having a concave shadow mask attached thereto, said shadow mask having on its concave face a number of beam-passable apertures separated by bridge members and arranged in rows parallel with each other, comprising: a. a light source placed at a predetermined position with respect to said panel on the opposite side of said mask from said panel for projecting light on said film on said panel in a pattern comprising images defined by the apertures of said shadow mask, said light source having an effective length in the lengthwise direction of the rows of the apertures greater than the length of one of the beam-passable apertures in the shadow mask to extend the image of each aperture on said panel in the lengthwise direction to reduce the effects of the shadow cast by said bridge members on said film and form said continuous vertical stripes; and b. means for vibrating said light source at least along a direction perpendicular to the longitudinal axis of said light source and parallel to said panel with predetermined amplitude and frequency to create a superposed image on said screen from said light source through each of said apertures and thereby substantially reduce diffraction phenomena effects created by the edges of each such aperture on the pattern of radiation on said screen.

Claim 2

An apparatus for preparing a developable pattern comprising continuous vertical stripes on a panel for a cathode ray tube having a film comprising photosensitive material having a predetermined response to incident light, said panel having a concave shadow mask attached thereto, said shadow mask having on its concave face a number of beam-passable apertures separated by bridge members and arranged in rows parallel with each other, comprising: a. a light source placed at a predetermined position with respect to said panel on the opposite side of said mask from said panel for projecting light on said film on said panel in a pattern comprising images defined by the apertures of said shadow mask, said light source having an effective length in the lengthwise direction of the rows of the apertures greater than the length of one of the beam-passable apertures in the shadow mask to extend the image of each aperture on said panel in the lengthwise direction to reduce the effects of the shadow cast by said bridge members on said film and form said continuous vertical stripes; and b. means for vibrating said light source at least along a direction perpendicular to the longitudinal axis of said light source and parallel to said panel with predetermined amplitude and frequency to create a superposed image on said screen from said light source through each of said apertures and thereby substantially reduce diffraction phenomena effects created by the edges of each such aperture on the pattern of radiation on said screen.

Claim 3

An apparatus for preparing a developable pattern comprising a plurality of light absorbing stripes and light emitting electroluminescent stripes each separated by one of the light absorbing stripes on a panel for an electroluminescent screen of a color cathode ray tube, the panel having a film thereon comprising a photosensitive material having a predetermined response to incident light, the screen having a shadow mask attached thereto, said shadow mask having on its concave face a number of beam-passable apertures arranged in rows parallel with each other and with said electroluminescent stripes, said apertures in each of said rows being separated from each other by beam-intercepting bridging portions in each of the rows, comprising: a. a light source placed at a predetermined position with respect to said apertures in said screen and on the opposite side of said screen from said panel for projecting light on said panel through the apertures of said shadow mask, said light source having an effective length in the lengthwise direction of the rows of the apertures greater than the length of one of said apertures plus the length of the bridge portions at either end of said one aperture to produce on said panel bright images of each said aperture so expanded in the lengthwise direction of the rows of the apertures as to be connected with the adjacent bright images of the apertures along the length of each of the rows; b. means for limiting the irradiated area on the shadow mask to a short length covering a part of the length of the rows of the apertures, the length of said irradiated area having substantially the same angle of inclination with respect to the vertical axis of said screen; c. means for moving said irradiated area on the shadow mask along the length of the rows of the apertures; d. means for vibrating said light source with predetermined frequency in a direction perpendicular to the axis of said light source and parallel to said panel to eliminate diffraction phenomena effects caused by the edges of each said one aperture; and e. means for inclining said light source to keep it always substantially parallel to tangents to the rows of apertures in said irradiated area.

Claim 4

An apparatus for preparing a developable pattern comprising a plurality of light absorbing stripes and light emitting electroluminescent stripes each separated by one of the light absorbing stripes on a panel for an electroluminescent screen of a color cathode ray tube, the panel having a film thereon comprising a photosensitive material having a predetermined response to incident light, the screen having a shadow mask attached thereto, said shadow mask having on its concave face a number of beam-passable apertures arranged in rows parallel with each other and with said electroluminescent stripes, said apertures in each of said rows being separated from each other by beam-intercepting bridging portions in each of the rows, comprising: a. a light source placed at a predetermined position with respect to said apertures in said screen and on the opposite side of said screen from said panel for projecting light on said panel through the apertures of said shadow mask, said light source having an effective length in the lengthwise direction of the rows of the apertures greater than the length of one of said apertures plus the length of the bridge portions at either end of said one aperture to produce on said panel bright images of each said aperture so expanded in the lengthwise direction of the rows of the apertures as to be connected with the adjacent bright images of the apertures along the length of each of the rows; b. means for limiting the irradiated area on the shadow mask to a short length covering a part of the length of the rows of the apertures, the length of said irradiated area having substantially the same angle of inclination with respect to the vertical axis of said screen; c. means for moving said irradiated area on the shadow mask along the length of the rows of the apertures; d. means for vibrating said light source with predetermined frequency in a direction perpendicular to the axis of said light source and parallel to said panel to eliminate diffraction phenomena effects caused by the edges of each said one aperture; and e. means for inclining said light source to keep it always substantially parallel to tangents to the rows of apertures in said irradiated area.