Display device with shadowmask CRT
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorTakeo Fujimura
Life of this patent
Estimating the term…
Abstract
A display device with shadowmask CRT comprises an offset scanning means for imparting an offset to the scanning lines. The offset is a shift that gently changes the position of the scanning lines in the Y-axis direction. The offset scanning means imparts the offset in such a way that an interval between neighboring scanning lines is gently changed in accordance with a position in the X-axis direction. The scanning line offset produces some loss in resolution in the Y-axis direction, but since the area which Moire pattern is strongly present coincides with the area of good resolution, even if the offset is imparted in this area, sufficiently high resolution can be obtained.
Claims23
A display device comprising:
- a substantially rectangular phosphor screen having first sides extending in an X-axis direction and second sides extending in a Y-axis direction which is at right angles to the X-axis direction;
- a shadowmask disposed oppositely to said phosphor screen and provided with a plurality of perforations arranged regularly in the X and Y-axis directions;
- an electron gun assembly for emitting an electron beam that passes through said perforations of said shadowmask and impinge on said phosphor screen;
- an X-deflection means for causing said electron beam from said electron gun assembly to scan in the X-axis direction and describe scanning lines on said phosphor screen;
- a Y-deflection means for changing a position of the scanning lines in the Y-axis direction;
- an X-deflection power supply for supplying an X-deflection current to said X-deflection means;
- a Y-deflection power supply for supplying a Y-deflection current to said Y-deflection means;
- and
- an offset scanning means for changing the position of the scanning lines in the Y-axis direction in such a way that directions of offset for neighboring scanning lines are opposite, while directions of the offset for alternate scanning lines are the same.
A method for scanning a display device which includes a substantially rectangular phosphor screen having first sides extending in an X-axis direction and second sides extending in a Y-axis direction which is at right angles to the X-axis direction, and a shadowmask disposed oppositely to said phosphor screen and provided with a plurality of perforations arranged regularly in the X and Y-axis directions, the method comprising:
- emitting an electron beam that passes through said perforations of said shadowmask and impinge on said phosphor screen;
- causing said electron beam to scan in the X-axis direction and describe scanning lines on said phosphor screen;
- changing a position of the scanning lines in the Y-axis direction in such a way that directions of offset for neighboring scanning lines are opposite, while directions of the offset for alternate scanning lines are the same.
Dependencies are inferred from the claim text.