Patent ID: 7629751

Claim:
An apparatus comprising a plurality of light emitting elements grouped in at least a string and connected in series; wherein each said light emitting element comprising a first end and a second end; each of said light emitting element operating to emit light at or above a first onset voltage by conducting an electrical current; wherein said apparatus further comprises at least a voltage control device; wherein said voltage control device operates in a low impedance state or a high impedance state according to the terminal voltage difference between said first end and second end of at least one said light emitting element; wherein said voltage control device operates in the high impedance state when said voltage difference is between zero and a first breakover voltage, and operates in the low impedance state when said terminal voltage difference reaches or exceeds said first breakover voltage; wherein said voltage control device conducts negligible amount of current in said high impedance state compared to the current in said light emitting element; and wherein said voltage control device provides at least a current path parallel to at least said light emitting device when in its low impedance state.