| 摘要 |
PURPOSE:To attain the simplification and the conversion to a high performance of a title system by placing a convex lens and a glass lens whose at least one surface is aspherical, and a convex lens and a glass concave lens whose at least one surface is aspherical, in order from a screen side, and making the fourth lens and a cathode ray tube adhere closely to each other, or packing a gap bteween them with a transparent medium. CONSTITUTION:In order from a screen side, a plastic convex lens 11 whose at least one surface is adpherical, a glass lens 12 having a large positive power, a plastic convex lens 13 whose at least one surface is aspherical, and a glass concave lens 14 whose screen side is a concave surface having a large curvature are placed, and the lens 14 and a projection type cathode ray tube are made to adhere closely to each other, or its gap is packed with a transparent medium whose refractive index is >=1.4. The glass lens 12 is made to have a large posi tive power, and the concave lens 14 is constituted of glass, therefore, the deterio ration of the reliability caused by a temperature rise is prevented, and the simplification and the convension to a high performance of the title sytem are realized.
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