Slide tray and slide positioning mechanism for a rear-screen projector

Claim 1

Apparatus for projecting slides comprising: a slide projector; a slide tray, including a plurality of indexing pins depending therefrom, removably mounted on said projector and adapted to contain a plurality of slides for projection by said projector; said projector including: a gate; said gate including a flat shutter member rotatably mounted near one end thereof about an axis in a plane substantially normal to the optical path of said projector; said shutter having a first position blocking hte optical path of said projector and a second position for which the optical path of the projector is not blocked; indexing means adapted to rotate said slide tray relative to said gate for successively bringing slides in said slide tray, one at a time, into substantially vertical registration with said projector gate; and first means operating in time relation with said indexing means for successively feeding said slides substantially vertically from said tray into said gate under the influence of gravity, for projection, and from said gate substantially vertically back into said tray; said indexing means including: a driven indexing bar having a slide tray indexing element at one end thereof; pivoted means including a rotatably pivoted, substantially flat, member having a slot therein a distance from said pivot coupled to said indexing bar by means of a pin depending from said driven indexing bar and extending into said slot in said pivoted member; said pivoted member guiding said indexing element to a position between two adjacent pins depending from said slide tray and then rotating said indexing bar around the pivot of said pivoted means tO rotate said slide tray as said indexing bar is driven; and second means in time relation with said indexing for causing said shutter to be in its first position in response to the absence of a slide to said gate and for causing said shutter to be in its second position in response to the presence of a slide in said gate; said second means including: means biasing said shutter in said second position; means for rotating said shutter around said rotational axis to said first position in opposition to said biasing means and for enabling counter-rotation of said shutter around said rotational axis to said second position under the urging of said biasing means; said means for rotating said shutter including an elongated member having a camming surface thereon in contact with the flat surface of said shutter member; said elongated member adapted to be reciprocated in a direction transverse to the optical axis of said projector and in a plane substantially parallel to the rotational axis of said shutter with said camming surface to contact with the flat surface of said shutter to rotate said shutter to said first position; means for sensing the absence of a slide in said gate for latching said elongated member in a position wherein said shutter is at said first position and for sensing the presence of a slide in said gate for enabling the return of said shutter to said second position; a stationary slide guide located at said projector gate; a slide clamp rotatably mounted on an axis in a plane substantially normal to the axis of said optical path; and means biasing said slide clamp toward said slide guide.