FIELD: physics.
SUBSTANCE: invention provides a method and apparatus for controlling thermal gradient and therefore thermal stress in light-emitting elements in which the light-emitting elements are exposed to temperature gradients caused by varying drive current under operating conditions. The method and apparatus can reduce thermal stress in a light-emitting element by adaptively determining a drive current transient for a required change in the drive current from a first drive current state to a given second drive current state, wherein the drive current transient is adaptively determined in order to substantially minimise the change in applied voltage over time, during the transition time period.
EFFECT: longer service life of light-emitting elements.
14 cl, 10 dwg
