| 摘要 |
Projection television display device includes three monochrome projection television display tubes (20, 21, 22) each having a display screen (24, 25, 26) which is provided on the inside of the display window (23) and luminesces in a different color. Each tube has an optical axis extending perpendicularly from the center of the display screen, the optical axes (33, 34, 35) of the three display screens being co-planar. The axes (34, 33) of the display screens of the first and second tubes (20, 22) coincide and the axis (35) of the display window of the third tube (21) constitutes the main axis of the device, the axis being perpendicular to the two coincident axes (33, 34). Two flat dichroic intersecting reflective mirrors (27, 29) extend perpendicularly of the plane and through the point of intersection of the axes, each at an angle of 45 DEG with the main axis. The first mirror (27) reflects the image of the first display screen and the second mirror (29) reflects the image of the second display screen into the direction of the main axis and away from the third display screen, interference filters being disposed between the display screens and mirrors for passing the desired color of light. With interference filters disposed between the luminescent material of the display screens and the display windows, the reflection greatly increases for light rays constituting an angle of more than 20 DEG to 35 DEG with the normal of the filter. When there is substantially no transmission up to 90 DEG , there is a gain in brightness by a factor of 1.5 to 2, a gain in contrast by more than a factor of 2 and also a considerable color improvement and reduction of color errors when the conventional green and blue phosphors are used. |
