Abstract: A method for enhancing the contrast of a latent electrostatic image on a dielectric surface is disclosed which includes positioning a photoconductive electrode adjacent the dielectric surface; and applying an electrical potential between the photoconductive member and the dielectric surface, while irradiating selected portions of the photoconductive electrode, to cause electrical charge formation on selected portions of the dielectric surface corresponding to the selected photoconductive electrode portions. Thereafter, the applied electrical potential is reduced to essentially zero. In accordance with this invention, during such reduction to essentially zero potential, the entire surface of the photoconductive member is briefly flooded with light to obtain an improvement of the intensity and contrast of the latent electrostatic image formed on the dielectric surface.

Abstract: A slide projector adapted to alternately receive at least two slide trays having different shapes and different indexing configurations is provided. The projector comprises a slide tray receiving groove having tray guide means for slidably engaging corresponding support surfaces formed on the slide trays, and a reversible slide tray indexing mechanism having an indexing lever mounted for slidable and pivotable movement and including a pair of pawls for sequential engagement with the respective indexing racks of the alternate trays, to incrementally advance either of said trays from one slide position to the next. A reciprocal slide carrier for transporting the slides from the trays to the viewing position is provided with a camway in operative engagement with the indexing lever to impart the required movement thereto during each slide changing cycle.

Abstract: An audio-visual unit includes a disc mounting a plurality of discrete image transparencies arranged in a continuous pattern for successive visual display; a record co-axially mounted on the disc includes separate recorded messages corresponding to respective transparencies on the disc. The projector includes an advance mechanism manually operable successively for intermittently rotating the disc thereby to present the transparencies in seriatim for visual display. An indexing mechanism is operated in response to actuation of the advance mechanism for intermittently moving a tone arm to successive positions corresponding to the starting grooves of respective messages on the record.

Abstract: A slide projector adapted to alternately receive at least two slide trays having different shapes and different indexing configurations is provided. The projector includes a slide tray receiving groove having tray guide means for slidably engaging corresponding support surfaces formed on the slide trays, and an indexing mechanism having suitable drive gears for engagement with either of the alternate trays, to incrementally advance either of said trays from one slide position to the next. The projector also includes in one embodiment slidable tray retainer means normally biased into the tray receiving groove to support the edge of one said trays to maintain the same in engagement with the indexing mechanism, and means to urge such retainer out of the tray receiving groove upon insertion therein of the other of said trays.

Abstract: The invention is directed to a method of and machine for loading a scroll of film and take-up spool into a cartridge and assembling and sealing the cartridge. It includes the steps of supplying a web of film and backing paper to a scrolling mechanism and winding the webs into a scroll. A single guide track guides and assists in advancing the webs of film and backing paper to a winding spindle. Severing mechanisms are located along the guide track to cut the webs into the desired lengths. The winding spindle is engaged by the webs for scrolling within a socket on a first transport carrier. When scrolling is complete the spindle is withdrawn and the scroll is retained in the socket. An ultrasonic securing device is used to secure a free end of the scroll to a take-up spool carried in another socket of the carrier.