Apparatus and method for l.e.d. illumination

A user-portable illumination source system, comprising:

• a housing;
• a plurality of light-emitting diodes (LEDs) attached to the housing;
• a source of DC electric power, attached to the housing, that has a voltage that decreases as electrical energy is removed;
• and
• a control circuit that selectively applies a plurality of pulses from the source of DC electric power to the plurality of LEDs, wherein the control circuit has a feedback signal input, and wherein the control circuit changes a characteristic of the plurality of pulses to control a light output characteristic of the LEDs, to a value that is independent of the voltage decrease, based on the feedback signal.

A portable apparatus, comprising:

• a housing;
• one or more light-emitting diodes (LEDs) attached to the housing and configured to emit light to illuminate an object other than the housing;
• a camera imaging device attached to the housing;
• a source of DC electric power attached to the housing;
• a control circuit that selectively applies a plurality of pulses from the source of DC electric power to the one or more LEDs;
• and
• a feedback signal coupled to the control circuit, wherein the control circuit changes a characteristic of one or more of the plurality of pulses to control a light output characteristic of the one or more LEDs based on the feedback signal.

An apparatus, comprising:

• a housing;
• a plurality of light-emitting diodes (LEDs) attached to the housing and configured to emit light;
• an image processor attached to the housing, the image processor configured to receive a video signal;
• a control circuit that selectively applies a plurality of pulses from a source of electric power to the plurality of LEDs;
• and
• a feedback signal coupled to the control circuit, wherein the control circuit changes a characteristic of one or more of the plurality of pulses to control a light output characteristic of the LEDs based on the feedback signal.