Abstract: An electrostatic clutch operable by the Johnsen-Rahbek effect, which may be used to operate, e.g., a print hammer device, is described, said clutch comprising a rotatable drum and a band engagable therewith, wherein the engagable surface of the drum is a semiconductive surface prepared by sputtering or vapor depositing a layer of substantially pure silicon carbide onto a conductive substrate.

Abstract: An impact printing mechanism is disclosed having an electrostatic clutch assembly, including a rotatively mounted semiconductive coated drum and a conductive band wrapped around the circumference thereof. The printing mechanism includes a printing hammer and a print spring for actuating the printing hammer. When a print command is issued, a voltage is applied to the band to create a field between the band and the drum coating. An electrostatic force is therefore generated when the drum is rotating slowly or synchronous with the drum step motion. That motion will pull the band and compress the print spring. The potential energy stored in the spring is then ready to fire the hammer. A hammer firing command turns off the voltage pulse and discharges the field, releasing the electrostatic holding force instantaneously and firing the hammer by the compressed spring.

Abstract: A versatile microsecond multiple framing camera generates a switched beam of illumination derived from a laser and switched by an acousto-optic modulator. The illumination is focused on a subject, and illumination from the subject is caused to scan over a predetermined field by a mechanical or electromechanical scanner. Located in the field is an image recording device for recording the illumination directed over the field by the scanner. The image recording device, in one embodiment, includes a vidicon tube, for short term storage, and a video recorder for longer term storage. A video monitor may be driven from the video recorder. The versatility of the camera is exemplified by the ability to vary exposure times or frame rates by adjusting operator controls which drive the acousto-optic modulator and/or the electromechanical scanner. In other embodiments, the vidicon tube and video recorder can be replaced or supplemented by photographic film.