| 摘要 |
A microfiche reader provided with a pair of lenses of different powers selectively and simultaneously shiftable into and out of alignment with the fiche projecting light beam. The lens in use rests by gravity on an X-Y fiche transport supported on a turn table. The lens shifting mechanism includes a device holding the lens in use firmly stationary despite both rotary and linear movement of the fiche transport. Simple linear movement of the lens shifting mechanism functions to elevate one lens while lowering the other gradually into contact with the fiche transport. The lens support assembly includes components for automatically adjusting the intensity of the light beam to provide the same lighting intensity on the image viewing surface for each lens. The lens support assembly is readily removable as a unit for servicing and the substitution of another assembly while the first is undergoing repair.
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