| 摘要 |
PURPOSE:To perform stable zooming operation by mounting a lens barrel to be used and a zoom lens barrel, and providing a mutual engagement part which engages the main lens barrel side of this lens barrel and the nonrotation member side of a projection lens assembly correspondingly and inhibits the main zoom lens barrel from rotating. CONSTITUTION:A helicoid male cylinder 70 is rotated clockwise or counterclockwise relatively to a female cylinder 60 to make a focus adjustment. An external projecting lateral shaft 91c engages the longitudinally long groove 39 of a lens unit on the side of an upper main frame 30 as a fixed member, so even when the male cylinder 70 is rotated, the zoom lens barrel 90 does not rotate. The focus is adjusted by operating the male cylinder 70 and then the variable power ring rotary knob 94c of the zoom lens barrel 90 is rotated clockwise or counterclockwise. In this case, the zoom lens barrel 91 engages the longitudinally long groove 39 and is stopped from rotating, so the variable power ring 94 is rotated easily and stably to and away from the main lens barrel 91 and the mutual distance between lens units 92 and 93 of the front group and rear group in the main lens barrel 91 varies, thereby zooming a projection image.
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