本研究為研究一套PWM（Pulse Width Modulation）調光技術驅動白光LED之發光效率分析系統，此系統可應用於LED各種背光模組上，一般被廣泛使用之固態照明設備驅動電路為供應直流電源和交流電源驅動，為了提高 LED發光效益，我們設計可調變之PWM脈波電路驅動LED。
PWM調光技術驅動白光LED之發光效率分析系統是依照發光二極體特性設計出的驅動電路，目的為提高白光LED亮度，本系統是利用PWM脈波供應白光LED更高的正向電流驅動發光，此方法所驅動白光LED可在相同功率時，其亮度大於一般由直流電路驅動時之LED照度。系統以PWM脈波驅動電路持續供應定電流脈衝，控制脈波的頻率高於閃光臨界融合頻率，人眼將無法辨識出閃光變化，調整脈波寬度於整個週期所占的比例，LED的平均照度也隨之改變，經由量測數據得出最佳負載週期 (duty cycle)及頻率，使用此方法驅動可提高LED發光效率。

This thesis seeks to research an “analysis for luminous efficiency of white LEDs with pulse width modulation” system, the system used in all kinds of backlight module, Solid State Lighting apparatus which general used in lighting is driven by DC and AC power supply, in order to improve the luminous efficiency, we design the pulse-width modulation (PWM) circuit to drive the LED.
Circuit design of “analysis for luminous efficiency of white LEDs with pulse-width modulation” system in accordance with the characteristics of light-emitting diode, with the objective to improve the brightness of white LED, this system use PWM pulse to supply of a higher forward current to drive white LED, use this method to drive a white LED in same power can get higher brightness better then driven by DC power supply. This system use PWM dimming method driving LED with constant current, control the frequency of PWM pulse below the critical flicker fusion frequency, then the flashing points of light can’t be aware by human, adjust the proportion of the entire cycle then LED average illumination also changes. Measurement data obtained by the best duty cycle and frequency, use this method to drive a white LED can get higher brightness.

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