透過壽命分析預測高功率藍色發光二極體之最佳PWM操作模式

Decision of PWM Operating Parameters for High Power LEDs by Lifespan Test

劉育昇(Yu-Sheng Liu)

指導教授 ： 林俊良

崑山科技大學/工程學院/電子工程研究所/碩士(2009年)

摘要

以脈波電流驅動操作模式下的LED，具有發熱少、壽命長的優點，因此在許多應用上頗受歡迎，但目前仍缺乏脈波驅動電流操作模式下LED操作的有效評估方式，因此本論文透過不同的電流驅動方式，包括調變驅動電流的頻率、振幅、負載週期等，在初始相同亮度條件下，進行壽命測試，透過分析輸入功率與光輸出功率、波長飄移之關係，獲得脈波電流驅動操作模式的合適操作條件，並找出直流電流驅動操作模式與脈波電流驅動操作模式間的關係，進而透過直流電流驅動操作模式的壽命測試，進行脈波電流驅動操作模式的壽命預估。
以脈波電流驅動之LED元件，其脈波頻率越低，為了達具有相同光輸出通量，則所需之電流越高，光輸出特性也衰減較快，其中又以負載週期為60%、驅動頻率60 Hz 之元件衰減最快速，最後發現壽命測試與輸入功率有直接的關係，可以藉由輸入功率的大小來預測壽命的趨勢。

關鍵字

脈波電流驅動 ； 發光二極體 ； 壽命分析

並列摘要

Using pulsing power to drive light-emitting diodes is popular for many applications due to which has less heat and longer life. However, there is no effective assessment method for the operation in the pulsing power driving of light-emitting diodes at present. In this paper, the life testing of light-emitting diodes by various conditions of driving current were investigated, which included frequency, current amplitude, and duty cycle. Here, all light-emitting diodes have the same brightness in the initial state. By the analysis of optical output power and relationship of wavelength shift in light-emitting diodes, we have found the appropriate conditions of operation for the pulsing power driving and the relationship between the DC current-driving mode and pulsed current-driving mode. Furthermore, we estimate the life-time of light-emitting diodes under the pulsing current-driving mode according to the life testing of DC current-driving mode.
For pulsing current-driving mode of the light-emitting diodes, in order to achieve the same light output of flux, the higher current was required in the lower frequency of pulse. However, higher current resulted in the worse characteristics of light output in light-emitting diodes. As the load cycle 60% and driving frequency of 60 Hz, the decay in performance of light-emitting diodes was the worst. Finally, we found the direct relations between the life testing and input power, and therefore to forecast the tendency of life by the input power.

並列關鍵字

Pulsing Current-driving ； Light Emitting Diodes ； Life-time

參考文獻

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