An EL lamp characterized by non-linear brightness decay is driven to constant brightness for the life of the lamp by an inverter controlled by a microprocessor. The microprocessor controls the inverter in accordance with a table containing data which is the inverse function of the non-linear brightness...http://www.google.fr/patents/US5493183?utm_source=gb-gplus-shareBrevet US5493183 - Open loop brightness control for EL lamp
