GB1454106A - Photo-optical method for drawing lines and apparatus therefor - Google Patents

Abstract

1454106 Photographic draughting H BERTHOLD AG 12 Nov 1973 [27 Nov 1972] 52359/73 Heading G2A A photographic draughting machine for producing substantially uniform horizontal or vertical lines employs a rectangular diaphragm through which a rectangular point of light is projected on to photo-sensitive recording material with relative horizontal or vertical fractional stepwise movement of the diaphragm, the projection to form each straight line being started and terminated, respectively, before and after relative movement of the diaphragm by means of a shutter, in the form of a slotted rotary disc, the opening and closing of which is at a stepwise rate such that the quantity of light projected on to the recording material at each end position of the diaphragm, as well as therebetween, is substantially constant. As shown, light from a source 11 passes through a line element diaphragm 13 having an adjustable dia- phragm edge 18 (determining the thickness of the draughted line), a slotted shutter disc 26 and a rotary prism 22, having two limiting positions, for rotation of the projected image through a right angle. The whole projection assembly is capable of stepwise horizontal motion along bars 32 by means of a motor 33 for draughting horizontal lines and the recording material, which is supported on a drum 42, is capable of stepwise longitudinal movement by means of a motor 44 for draughting vertical lines. The shutter disc 26 is driven by a motor 28 and the diaphragm edge 18 is adjusted by means of a motor 17. Prism 22 is rotated from one end position to the other by means of a magnet against a spring bias. Operation may be by means of a programmed computer.