Patent ID: 7301511
Filing Date: 2007-11-27
Classification: G09G,H01L,H05B,Y02B

Abstract:
1. A method of driving an EL illumination device that includes a plurality of EL elements producing lights of different colors, wherein an EL element within the plurality of EL elements includes at least one organic layer containing a luminescent layer and a pair of electrodes arranged opposite to each other with the organic layer provided therebetween, and a voltage-or-current applying device that applies a voltage or current to the pair of electrodes of the EL element, the method comprising: separately setting a magnitude of the voltage or current applied to each of different color EL elements during driving the EL illumination device so that the luminous efficiency of all the different color EL elements is 80% or more of a maximum luminous efficiency of the EL element; setting the voltage or current, at which luminance is maximum, in the range of a higher voltage or higher current than the voltage or current at which luminous efficiency reaches the maximum luminous efficiency; wherein in setting the magnitude of the applied voltage or current, a relationship between a value of the applied voltage or current and the luminous efficiency obtained with the value of the applied voltage or current, is previously determined for the EL elements.