| 摘要 |
<p>PHQ 85.007 18 1985-4-22 : "Projection television display tube and projection television device having at least one such tube". A projection television display tube comprising in an evacuated envelope (1) a display screen (7) which is provided on the inside of a curved display window (2) in the wall of the envelope (1), which display screen (7) comprises luminescent material (13) and a multilayer interference filter (12) is provided between said material and the display window, and comprises a number of layers (HL) which are manufactured alternately from a material having a high refractive index (H) and a material having a low refractive index (L). If the filter (12) 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 f and preferably is between 0.23 .lambda.f and 0.27 .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 (13) and p is a number between 1.18 and 1.32, a display tube is obtained in which the luminous efficiency on the projection screen and in particular at the edge of the projection screen has proved to be considerably larger than the sum of the effects of the individual measures, namely the curved display window and the provision of an interference filter, would give.</p> |
