Projection television display tube and projection television apparatus having the same

摘要

A projection television display tube comprising in an evacuated envelope a display screen on the convexly curved inside of a display window in the wall of the envelope, which display screen comprises a layer of luminescent material and a multilayer interference filter between said material layer and the display window, the filter comprising a number of layers which are alternately high refractive index (H) and low refractive index (L). The filter is composed of at least 6 layers, each having an optical thickness nd, wherein n is the refractive index of the material of the layer and d is the thickness, which optical thickness is between 0.2 lambda f and 0.3 lambda f, wherein lambda f is equal to p x lambda , wherein lambda is the desired central wavelength which is selected from the spectrum emitted by the luminescent material and p is a number between 1.18 and 1.32.