Patent ID: 7339323

Claim:
A circuit for driving light emitting diodes, comprising: a voltage source; a plurality of light emitting diodes coupled in series, wherein said voltage source is coupled to one end of said plurality of light emitting diodes; a plurality of switches, each of which is coupled in parallel with a corresponding light emitting diode in said plurality of light emitting diodes for individually controlling brightness of said corresponding light emitting diode; a plurality of PWM signals coupled to said plurality of switches, respectively, for individually controlling each of said plurality of switches; and a switch coupled in series with said plurality of light emitting diodes for controlling brightness of said plurality of light emitting diodes, wherein said switch is either on or off; wherein one of said plurality of PWM signals has a duty cycle ratio to modulate current through said corresponding light emitting diode, and wherein said current through said corresponding light emitting diode is modulated from 0 to a predetermined value.