| 摘要 |
<p>1413281 Facsimile receiver SOC EUROPEENNE DE PROPULSION 1 March 1974 [2 March 1973] 9458/74 Heading H4F In an image signal receiver in which a received video signal modulates 3d a light beam 2 which is focused on to photosensitive film 10 carried on a rotating drum 9 by means of a carriage 11a moved in a stepwise manner parallel to the drums axis of rotation, the drum is supported on magnetic bearings 14 and the carriage 11a has friction means for damping out and rapidly stabilizing the carriage position at the end of each forward step. Specifically the drum is rotated at a speed of at least 800 r.p.m., and each forward step of the carriage is less than 20 microns. The friction means may comprise PTFE shoes integral with the carriage and rubbing on its guide rails 19, or a PTFE ring integral with the rotor of the stepping motor and rubbing on a finger extending from the table 13 on which the carriage moves. The light beam 2 comprises a laser beam, the acousto-optic or electro-optic modulator 3d having a feedback loop 2a including a photoelectric detector 6 connected to the modulator control amplifier 3b. The optical system 7 includes focusing lens, a spatial filter diaphragm and a collimator. Optical system 11c carried by the carriage has variable focal length. At one end of the carriage movement an optical system 17 including a mirror 17a directs the light beam on to a display screen so that focusing of the spot 12 may be monitored.</p> |
