GB1111927A - Self-lighting apparatus - Google Patents

Abstract

A self-luminous light-transmitting unit comprises a transparent body having a cavity formed therein, a sealed bulb (24b, 24d) containing radio-active gas (e.g. tritium or krypton-85) with a phosphoric acid layer on its inner surface. The sealed bulb is held in shock-absorbing transparent elastomer in a cavity in transparent body 22b, 22d (of polymethylmethacrylate), aluminium casing 28b, 28d, legend 29b, 29d and in Fig. 5 white paint 33b is around the bulb outer surface excepting a 60 degrees segment. Light-diffusing flat planes 31b, 32b, 40 to 43d are at an angle up to 6 degrees (preferably 3 to 5 degrees) with the front face; white <PICT:1111927/C4-C5/1> <PICT:1111927/C4-C5/2> paint 25b, 25d is on the entire outer surface of 22b, 22d excepting emitting windows 26b, 26d; a shutter is formed in Fig. 5 by white paint 23b, in Fig. 8 by indentation 35d of base angle 84 degrees or less covered by transparent or translucent plate 34d which may have crest 36d extending into but not filling 35d. Alternatively the shutter may be formed by an opaque screen on the forward portion of the source cavity or merely by the translucent plate if the emitting windows are narrow; diverging surfaces 32b, 42d and 43d may be omitted with 31b, 40d and 41d extending to the corners, and the legends may be on plate 34d interior surface. The open side of the source cavity is preferably covered by polyethylene terephthalate sheet but is not required when this side is forward facing and against 34d. The units can have a second emitting window on the rear part. Zinc-cadmium sulfide, cadmium sulfide, cadmium tungstate, zinc sulfide and zinc silicate phosphors are mentioned; the coating may be formed by pouring through the bulb a 1 1/2 to 1 3/4 % phosphoric acid solution in methanol or acetone and with a wetting agent, evaporating the solvent until interference colors indicate desired phosphoric acid layer thickness and pouring in excess phosphor particles of size in the range 3 to 30 microns with an average size 8 to 12 microns to produce a single particle thickness, and baking at 450 DEG C. for 20 minutes.ALSO:In a self-luminous light emitting unit comprising a sealed bulb of cerium glass for instance, coated internally with a phosphoric acid layer and particulate phosphor adhering thereto, the coating is formed by rinsing the bulb with hydrofluoric acid and drying at 110 DEG C.; pouring into the bulb a solution of 1 1/2 to 1 1/4 % phosphoric acid in a solvent such as methanol or acetone and a wetting agent; allowing the solvent to evaporate the required thickness of phosphoric acid being determined by the interference colors; pouring into the ampule an excess of particulate phosphor of particle size in the range 3 to 30 microns, preferably 8 to 12 microns to produce a layer of single particle thickness. The bulb is then baked at 450 DEG C. for 20 mins.