| 摘要 |
A device for viewing a motion picture film strip held within a cassette includes a film strip drive wheel, turned at a constant speed by a battery-powered motor, having an outer cylindrical surface from which a pin section extends radially. The film strip is held, by guiding surfaces in the cassette, so that it extends in an arc around a portion of the outer cylindrical surface. The pin section engages a sprocket hole in the film strip at the beginning of this arc, and is disengaged from the sprocket hole at the end of this arc. During continued revolution of the drive wheel, the film is held in place as a single frame is viewed through the lens. The lens is focussed by sliding a tab extending from the lens housing within an oblique slot in a cover of the viewing device, as the lens is both rotated about its optical axis and translated along its optical axis.
|
