Abstract: A tone-arm generally in the form of a unitary right-angle member has first and second arms extending at approximately 90.degree. to each other. A needle is supported by one of the arms, the other arm being connected to a stem which is in turn connected to the speaker diaphram for vibrating the latter when the tone-arm is vibrated in its own plane as a consequence of the needle engaging the grooves of a phonograph record. A fulcrum supports the tone-arm for pivoting movement in its own plane; this fulcrum also permits the arm supporting the needle to move in a second plane parallel with the record. Spring means hold the tone-arm in engagement with the fulcrum and at the same time maintain the needle in engagement with the record. A camming means operated by advancing mechanism for a transparency holder separates the needle from the record during indexing of the needle to the separate successive messages on the record.

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: 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.