GB1299990A - Self-luminous light-source and assembly thereof - Google Patents

Abstract

1299990 Uses of luminescence BRANDHURST CO Ltd 7 Dec 1970 58036/70 Heading C4S A light source consists of a sealed glass tube internally coated with phosphor (e.g. ZnS) containing a radio nucleide (e.g. tritium) to excite the phosphor, and having one or more transparent synthetic polymeric collars 2 serving as locating members in an eventual assembly but leaving the major portion of the tube length uncovered, the tube extending completely through the central hole in the or each collar. The tube may be arcuate and shaped as a letter (e.g. Fig. 4, not shown) or as a digit. The tube may be within internally smooth and reflective annular channel 3 and in a straight instrument dial or telephone dial, and a tube or tubes may extend along an approximate optical centre, the groove being semicircular, a true optical centre being applied to a parabolic section. Straight instrument dials or illuminated signs with light sources defining letters or digits are mentioned. In Fig. 4 (not shown), the collar is distorted at (5) and (6) to be mechanically held without adhesives, the cover (4) with frosted surface (7) ensuring protection against breakage and loss of radioactive material. The above construction also reduces the probability of cracking due to thermal expansion differences. One or more sources may be held by a cover in a channel, usually metal or plastic, and made reflective by metallizing or painting. A diffusing screen or instrument dial may have a frosted backing and the use of collars reduce the risk of the frosted material irregularities becoming partially filled with synthetic material. Safety sign applications are also instanced.