GB653672A - Improvements in or relating to instruments or display devices having markings rendered fluorescent by invisible light rays - Google Patents

Abstract

653,672. Fluorescent scales. SMITH & SONS (ENGLAND), Ltd., S. July 9, 1948, No. 18552. [Class 39 (i)] In an instrument or display device having markings which are rendered fluorescent by a source of invisible light radiations disposed in front of and to one side of the markings, one or more reflectors are so located as to direct the invisible light rays on to the front of the markings without their being obscured to view by the reflectors. In the speedometer 10 shown, the dial plate 11 is marked with graduations near its outer periphery indicating miles per hour, a pointer 12 moving over these to indicate the speed of the vehicle. Mileage recording-drums 13 carry figures which are visible through windows 14, these figures and those on the dial-plate 11 being coated with a composition which is rendered fluorescent by ultraviolet rays. Two ultra-violet lamps 17 are mounted on the instrument board 8. The dial plate is slit and bent outwardly at 18 at such an angle as to reflect the ultra-violet rays from the lamp 17 rearwardly through the window 14 on to the figures on the adjacent drum 13. The dial plate 11 is formed from metal which is polished on the back face, at least along those parts constituting the reflectors 18, while the front face is non- reflecting. The dial plate is also slit and bent outwardly to form flaps 19 making only a small angle with the dial plate so as to obscure to view the slots 20 formed beneath them but permit ultra-violet rays from the adjacent lamps 17 to pass through windows 21 in the casing 15 and through the slots 20 on to the drum 13. The flaps 19 and reflectors 18 may alternatively be formed separately and secured to the dial plate.