| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens apparatus for projection capable of reducing the thickness of a projector without making the diameter of the lens smaller. SOLUTION: The lens apparatus 1 for projection comprises 16 lenses in four groups. Among these groups, the first lens group Gr1 comprises the first lens 11 of the largest diameter, the second lens 12, the third lens 13, and the fourth lens 14, from a screen side. The first lens group Gr1 is fixed to a guide frame 71, and the shafts of gears 73, 74 are rotatably and slidably inserted into a guide slit 72 of the guide frame 71. A ball screw member 75 is intermeshed with the gear 73 and a ball screw member 76 with the gear 74. When the ball screw members 75, 76 are rotated by motors 77, 78, the upper part of the guide frame 71 moves backward and the lower part of the guide frame 71 moves forward. The lens group Gr1 is thereby pushed back downward. COPYRIGHT: (C)2006,JPO&NCIPI
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