| 摘要 |
PURPOSE:To raise brightness of a projection type cathode-ray tube by providing a concave mirror of such an oval form that the longitudinal direction coincides with the low- or high-speed scanning direction and forming a vacuum outer case into an oval form matching the shape of the concave mirror. CONSTITUTION:The inside of a vacuum outer case, consisting of the funnel 1 and the face plate 2, is provided with an oval form of the concave mirror 5 so arranged that the longitudinal direction coincides with the low-speed scanning direction, and also the vacuum outer case is formed into such a shape that little clearance is produced between the funnel 1 and the periphery of the concave mirror 5, having an oval section with the same longitudinal and diametrical directions as the concave mirror 5. Thus, when a screen having a screen gain on a three-tube type projection cathode-ray tube is used, brightness can be raised without damaging the uniformity of color image with regard to the viewing angle as well as the hue by arranging the cathode ray tube in the diametrical direction of the funnel 1. |
