Patent ID: 8536796

Claim:
A light emitting diode driving apparatus comprising an arrangement for supplying a signal to a group of first and second light emitting diodes, wherein the first light emitting diode comprises a first internal impedance for in response to a parameter of the signal having a first value producing a first light output and for in response to the parameter having a second value different from the first value producing a second light output, the second light emitting diode comprises a second internal impedance different from the first internal impedance for in response to the parameter having the first value producing a third light output and for in response to the parameter having the second value producing a fourth light output, and a first ratio is defined by the first light output divided by the second light output, a second ratio is defined by the third light output divided by the fourth light output, the first ratio being different from the second ratio, wherein the first and second light emitting diodes are stacked organic light emitting diodes forming parts of a serial branch.