COLOR CATHODE RAY TUBE

摘要

The specification describes a method, in the manufacture of a color cathode ray tube having an envelope including a funnel and a faceplate having a predetermined three-dimensional curvature, the method comprising: providing an electrically conductive shadow mask blank having a curved central portion with a curvature closely related to the curvature of the faceplate, and having a stiffening peripheral portion; providing a single mask master and a set of screening masters, including a red, blue and green phosphor pattern master, the mask and screening masters having thereon interregisterable master stencil patterns, the screening masters each having a curvature corresponding to that of the faceplate, the mask master having a curvature corresponding to that of the mask blank; by operations including a photoexposure step, photochemically forming in the central portion of the mask blank from the concave side only a pattern of electron-transmissive apertures using the mask master as a photographic stencil, the mask master being supported during the involved photoexposure step in very close, but non-contacting relationship to the central portion of the mask blank on the concave side thereof, and the exposing light having a directional characteristic which simulates the directional characteristic of electron trajectories in the mask-faceplate region of an endproduct tube to enhance the fidelity of the patterns of mask apertures formed; using the screening masters as photographic stencils, and by operations involving a photoexposure step, photochemically depositing on a concave inner surface of the faceplate interleaved patterns of red-emissive, blue-emissive and green-emissive phosphor elements, the screening masters each being supported during the involved photoexposure step in very close, but non-contacting relationship to the inner surface of the faceplate, and the exposing light having a directional characteristic which simulates the directional characteristic of electron trajectories in the mask-faceplate region of an end-product tube to enhance the fidelity of the screen patterns formed; and suspending the mask adjacent the faceplate with the pattern of mask apertures registered with the patterns of phosphor elements on the faceplate.