| 摘要 |
<p>1,244,336. Photographic draughting apparatus; optical filters. G. CORADI A.G. Aug. 19, 1968 [Aug. 25, 1967], No. 39624/68. Headings G2A and G2J. In a photographic draughting machine of the type in which a spot of light is focused upon a photographic film and moves across it so that a design may be recorded means is provided for varying the intensity of the spot in accordance with the speed of movement of the spot by means of a servosystem which moves an optical wedge across the light beam. The system also comprises means to adjust the spot diameter according to the width of the line required and means to adjust the intensity of the light with optical wedges to effect the same exposure of the film for different spot diameters. Light from a lamp 1 is focused by condenser lens 2a, 2b on to an aperture 4, an image of which is formed by a movable lens 10 at a second aperture 16. A semi-reflecting mirror 14, which may be spectrally selective, is placed between the lens 10 and aperture 16 at 45 degrees to the optical axis. The transmitted light falls on a photo-cell 15 the output of which, together with information on the drawing speed, is fed to a computer (not shown) which adjusts the position of a wedge filter 6 by means of an electric motor 7. The computer also receives information on the size of aperture 16, which determines the width of the line drawn, and positions the movable lens 10 accordingly by means of a motor 11, so that the beam is not attenuated by the aperture 16. The diaphragm aperture 16 may be of the rotary drum or iris type and is provided with a filter or filters the transmission of which decreases as the aperture increases.</p> |
