Projection television display tube and device having band pass interference filter
AssigneeNorth American Philips Corporation
InventorAndre Van der Voort
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Abstract
Projection-television display tube includes a band pass or Fabry-Perot interference filter between the display window and the luminescent screen, resulting in the elimination of undesirable luminescent emissions both above and below the wavelength region of interest. A three-tube color projection display device includes such a filter in at least the green emitting display tube.
Claims14
A projection television display tube comprising in an evacuated envelope a display screen on the inside of a display window in the wall of the envelope, said display screen comprising a layer of a luminescent material and an aluminum backing layer, the tube further comprising multilayer interference filter between the luminescent material layer and the display window, the filter comprising a number of layers having a high (H) refractive index and a low (L) refractive index, characterized in that the interference filter is a band pass filter in which the filter layers are arranged in the sequence
- 1 2 2 1 . . . 2 1 2 2 1
- where 1 and 2 are high (H) and low (L), or low (L) and high (H) refractive index layers, respectively.
A three-tube color projection television display device having red, blue and green emitting display tubes, the tubes each comprising in an evacuated envelope a display screen on the inside of a display window in the wall of the envelope, said display screen comprising a layer of a luminescent material, characterized in that at least one of the tubes comprises a band pass or filter between the luminescent material layer and the display window, in which the filter layers are arranged in the sequence
- 1 2 2 1 . . . 2 1 2 2 1
- where 1 and 2 are high (H) and low (L), or low (L) and high (H) refractive index layers, respectively.
Dependencies are inferred from the claim text.