Patent ID: 8653747

Claim:
A light emitting device coupled to a voltage source, the light emitting device comprising: a plurality of light emitting modules; and a plurality of voltage controlling circuits that are independently controlled, each voltage controlling circuit coupled to a group of corresponding light emitting modules of the plurality of light emitting modules, the group having a first terminal coupled to the voltage source, the voltage controlling circuit comprising: a dynamic voltage controlling module comprising a first input terminal coupled to a second terminal of the group of corresponding light emitting modules, and a second input terminal for receiving a reference voltage, the dynamic voltage controlling module comparing voltage level at the second terminal of the group with the reference voltage for outputting a first voltage; a current controlling module coupled to the dynamic voltage controlling module for adjusting a bias current flowing through the group of corresponding light emitting modules according to the first voltage; and a luminance controlling module coupled to the dynamic voltage controlling module for comparing the first voltage with a clock signal, and generating a pulse width modulation (PWM) signal according to a result of the comparison for dynamically controlling a duty cycle of the group of corresponding light emitting modules.