Electroluminescent display

When current flows, the layer of material emits radiation in the form of visible light.

[4][5][6] EL works by exciting atoms by passing an electric current through them, causing them to emit photons.

By varying the material being excited, the colour of the light emitted can be changed.

Electroluminescent (EL) displays have been a niche format and are rarely used nowadays.

Some uses have included the Apollo Guidance Computer 7-segment numerical displays, to indicate speed and altitude at the front of the Concorde, and as floor indicators on Otis Elevators from around 1989 to 2007,[7] mostly only available to high-rise buildings and modernizations.