| 摘要 |
The present invention is directed to a transparency projector, such as a slide or motion picture projector including a compact focusing mechanism having an objective lens carried within a lens barrel supported within a sleeve which is carried within the projector housing for axial reciprocal displacement along the optical axis. The sleeve is provided with means for engaging a guide rod supported within the projector housing for limiting movement of the sleeve to axial movement. A reversible electric motor is supported on the sleeve for movement therewith and is energized in response to slide position error signals received from an automatic focusing system of the type well known in the art. The electric motor operates to drive a disc rotatably carried on the sleeve. The disc is provided with a spiral groove on one face. A pin fixedly supported on the projector housing is arranged for engagement with the spiral groove so that upon rotation of the disc, engagement of the pin within the spiral will produce axial movement of the lens barrel supporting sleeve along the guide rod.
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