PROJECTION-TYPE TELEVISION DISPLAY TUBE

摘要

PURPOSE: To provide a projection type television display tube having a multi- layered interference filter which can achieve significant improvement in color and contrast compared to known display tubes. CONSTITUTION: A projection type television display tube is provided with a display screen 7 having a phosphor layer 13 which is provided on an interior surface of a convexly curved display window 2 and a multi-layered interference filter 12 having a plurality of layers (HL) composed of alternately stacked material having high index of refraction (H) and material having low index of refraction (L) in an evacuated envelope 1. The filter 12 comprises six layers or more, wherein the optical thickness nd of each layer is in the range from 0.2λf to 0.3λf , preferably 0.23λf to 0.27λf , whereλf =p×λ,λdenotes a desired central wavelength which is selected from an emission spectrum of a phosphor, and (p) is a value between 1.18 and 1.32.