Method for improving the white field uniformity of a projection color TV using CRTs having interference filters, projection color TV and CRTs resulting from the method
AssigneeNorth American Philips Corporation
InventorsMatthew S. Brennesholtz, Raymond G. Greene
Life of this patent
Estimating the term…
Abstract
The white field uniformity of a projection color TV employing three monochrome cathode ray tubes is improved by matching the center-to-edge luminance gradient of the red-emitting and/or blue-emitting tube to that of the green-emitting tube having an interference filter. In a preferred embodiment, such matching is achieved by applying an optical filter of varying density on the outside surface of the display window of the tube.
Claims28
A method for improving the white field uniformity of a projection color television display device incorporating red, blue and green monochrome cathode ray tubes, at least one tube having an interference filter, the method comprising altering the center-to-edge luminance gradient of at least one of the tubes to match the center-to-edge luminance gradient of the tube to that of at least one of the other tubes.
A three-tube color projection television display device having red, blue and green emitting monochrome cathode ray 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, and at least one of the tubes also comprising an interference filter between the luminescent material layer and the display window, characterized in that means are included for altering the center-to-edge luminance gradient of at least one of the tubes in order to match the luminance gradient of the tube to that of at least one of the other tubes, and thereby improve white field uniformity of the display.
A monochrome cathode ray tube for projection television 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 means are included for altering the center-to-edge luminance gradient of the tube comprising a single layer optical filter.
A monochrome cathode ray tube fort projection television 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 means are included for altering the center-to-edge luminance gradient of the tube comprising a layer of an electron beam attenuating material.
Dependencies are inferred from the claim text.