Transparent instrument cover and instrument incorporating same

Claim 1

A transparent coverglass adapted to be fitted to an instrument above a dial on the instrument to enable legends or characters on the dial to be viewed externally of the instrument, said coverglass comprising a pair of transparent laminates and an electroluminescent area sandwiched between the laminates, the electroluminescent area occupying a relatively small portion of the area between the transparent laminates to provide a viewing window through the major portion of the area, and transparent adhesive securing the laminates together with the electroluminescent area therein to form a unitary coverglass sandwich with spaced apart transparent laminates to be fitted to an instrument, said electroluminescent area comprising a plurality of layers disposed in adjacency and including a first electrode layer of transparent electrically conductive metal oxide film, said first electrode layer being applied to an inner surface of one of said laminates, a layer of light emitting phosphor, an insulating layer and a second electrode layer, said second layer comprising a copper film applied to said insulating layer, and means for connecting said electroluminescent area to an electrical supply so that, when energised, light is projected from an inner surface of the coverglass to illuminate at least part of a dial of an instrument on which the coverglass is fitted through the inner one of said transparent laminates and the illuminated dial is viewable through both the inner and outer transparent laminates.