In 1992, the Timex IRONMAN watch got its first major technology update since its introduction six years earlier. A new and innovative electro-luminescence back-light technology which would replace the current corner back-light. Indiglo was integrated into some of the IRONMAN watch models and was an immediate and resounding success.
The basic technology behind Indiglo is called electro-luminescence. Electro-luminescence is the conversion of electricity directly into light and is distinct from an incandescent bulb which uses electricity to generate heat, which then produces light. Because electro-luminescence converts electricity directly into light and not heat, it is far more efficient.
The Indiglo lamp uniformly lights the surface of the Timex’s watch dials. In some newer watches, only the numbers are lit up, rather than the entire LCD display. This is achieved by means of a specialized film that inverts the LCD transmissivity
When Indiglo came out, the same 1986 design of the original Timex IRONMAN watch was used, but with an altered color scheme and a Silver/Stainless steel full-size version added to the mix. The ladies/mid-size IRONMAN would not receive Indiglo until 1994.
Today Indigo is a standard feature in almost every Timex IRONMAN Watch and has been licensed and used in many other devices, including cell phones, clock radios, electronic personal organizers, and night lights.
Head to the following link for a more technical description on how Timex Indiglo works.