Abstract: A portable overhead projector comprising a rigid housing, a collapsible expansion housing, a fold mirror, a fresnel lens, a light source and a projecting head assembly. In the portable configuration of the projector, all of the operational elements of the projector are collapsed into the confines of the rigid housing. The expansion housing is a box-like assembly having two fixed and two hinged sidewalls. The first and second sidewalls are integrally formed with a bottom wall of the expansion housing. The bottom edges of the third and fourth sidewalls are attached via hinges to opposite marginal edges of the bottom wall. The top edges of the third and fourth walls are attached to the underside of the rigid housing by two hinges. The fold mirror is mounted via a hinge to the inner surface of the bottom wall. The projection head assembly which includes a projecting lens and a projection mirror is attached to the rigid housing by a post, a rack and pinion gear mechanism and a mounting arm.

Abstract: A device for feeding letter mail and the like from a stack of such non-uniform sheet-like articles for individual workpiece processing wherein a plurality of friction feeders define a path for the transfer of mail from the stack and are driven in a pulsing mode interdependently under the control of photoelectric cells to facilitate the automatic separation of workpiece doubles.