Improved method and apparatus for hand-held portable illumination. A
flashlight and corresponding method are described. The flashlight includes
a housing, a plurality of LEDs, and an electrical circuit that selectively
applies power from the DC voltage source to the LED units, wherein the
flashlight is suitable for handheld portable operation by a user. In one
embodiment, the first electrical circuit further includes a control
circuit for maintaining a predetermined light output level of the LED
units as a charge on a battery varies. In another embodiment, the control
circuit maintains an average predetermined light output level of the LED
units as the charge on the battery cell varies by changing a pulse width
or frequency as the charge on the battery cell varies to maintain a given
average light output. Another aspect provides an illumination source that
includes a light-emitting diode (LED) housing including one or more LEDs,
and a control circuit that selectively applies power from a source of
electric power to the LEDs, the control circuit substantially maintaining
a light output characteristic of the LEDs as a voltage of the voltage
source varies over a range that would otherwise vary the light output
characteristic. Still another aspect provides an illumination source
including a light-emitting diode (LED) housing including one or more LEDs;
and a control circuit that selectively applies power from a source of
electric power to the LEDs, thus maintaining or controlling a light output
color spectrum of the LEDs.
