GB568840A - Improvements in or relating to a photographic copying apparatus - Google Patents

Abstract

568,840. Control systems for discharge lamps. KODAK, Ltd., and DAVIES, E. R. Nov. 3, 1943, No. 18234. [Class 38 (iv)] [Also in Group XX] In apparatus for conveying documents into an exposure aperture of the same height as the document area to be copied, means operated. when the document area registers with the aperture initiate a single condenser-discharge through a gas-filled discharge lamp and thereby produce a document-illuminating lightflash of such short duration (e.g. 1/1000 to 1/100,000 second) that the image recorded in a camera will not be blurred owing to movement of the document and/or the camera film through the apparatus at the instant of exposure. The mask aperture 12, 13 is illuminated by one or a pair of tubular coldcathode discharge lamps 11, each housed in a reflector 16, the flash discharge through which is initiated, when the document area to be copied is in register with the mask aperture, by the engagement of the leading edge of the document with a, pivoted finger 20, Fig. 4, normally engaging a groove in the drum 5. The resulting rotation of the finger actuates the button 19 of a micro-switch 17 mounted, for angular adjustment by a screw 24, on a pin 23 carried by side plates 18 which are adjustably mounted as a unit in slots 43 so that the position of the finger 20 with respect to the aperture 12, 13 may be varied. The switch 17, together with a voltage source 30, is in the primary circuit of an induction coil 29, Fig. 5, the secondary of which is in circuit with a triggering electrode 28 furnishing several kilovolts when switch 17 is opened, which electrode is associated with the lamp 11, whose end electrodes 26 are connected to a H.T. supply of, e.g. 2000 volts, bridged by a storage condenser 27, e.g. of 2 mfd.