數位電路系統之有機半導體衰減偵測研究

The Study of Measuring and Detecting Degradation of Organic Light-Emitting Devices by Digital Circuitry

楊道興(daoxing Yang)

指導教授 ： 楊恆隆

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2008年)

摘要

本論文主要在探討利用交流訊號驅動OLED時，亮度衰減時會得到跨壓上升的特性。由於實驗採用方波電流驅動OLED會得到方波跨壓訊號，我們利用外部偵測數位系統來量測跨壓，並利用取樣的概念將電壓訊號鎖定在高電壓位準，也就是峰值訊號，使獲得的資料不會因為交流而產生錯誤，也減少了多餘的資料儲存。當跨壓值升高時代表OLED元件亮度正在衰減，所以我們可以藉由偵測跨壓訊號作為判斷OLED亮度是否衰減的依據。外部偵測數位系統以定電流IC MBI5026驅動有機發光二極體，作為我們交流驅動的訊號源，它控制實驗所需要的電流方波頻率以及振幅大小，通過8位元ADC0804轉換成數位訊號，再以FPGA作為數位訊號處理的平台，去擷取通過有機發光二極體產生的跨壓訊號，最後透過通訊介面卡把訊號傳至電腦中儲存分析。在外部數位偵測系統的驗證方面，先使用數值模擬的方法設計程式功能，再使用邏輯分析儀驗證FPGA的輸出波形，判斷功能是否正確，最後透過與數位示波器當做基準參考值，去比對外部偵測數位系統所量到的偵測值，求得相對準確度誤差。實驗結果顯示A型紅光元件1跨壓從7.5000V上升至7.6562V，A型綠光元件1從8.3223V上升至9.0898V，的確有跨壓上升的現象，而跨壓上升的圖形有類似線性上升的趨勢，符合我們預期的量測結果，代表元件亮度正在衰減。我們使用數位示波器去驗證外部偵測數位系統量測的誤差，最後量測的系統誤差範圍為-3∼5%，在誤差範圍內外部偵測數位系統可以準確的量測OLED跨壓值的變化。

關鍵字

有機發光二極體元件 ； 電流方波驅動 ； 外部偵測數位系統 ； 衰減偵測 ； 可程式化邏輯閘陣列

並列摘要

This thesis is to investigate the characteristic of voltage increment as OLED undergone alternating current (AC) driving condition. The voltage signals are detected in our experiment as OLED driven by square-wave current by using an external digital detecting system and the technique of digital sampling in which the voltage signal can be locked in peak level. The phenomenon of degradation can be determined from detecting voltage signals due to the fact that the voltage across OLED increases as OLED degraded. The square-wave current for driving OLED in our experiment is provided by a MBI5026 chip as amplitude and frequency controller. The acquired voltage signals pass an 8-bit analog/digital converter (ADC0804) and then FPGA for digital signal processing. The magnitude of voltage increment across OLED is calculated by the control PC. Our experimental results revealed that the voltage across a type-A red OLED was increased from 7.5000V to 7.6562V and successfully detected by external digital detecting system. The voltage across a type-A green OLED was detected from 8.3223V to 9.0898V. Our external digital detecting system can effectively detect the magnitude of voltage increment across an OLED undergone square-wave current driving within the system percentage error -3~5%.

並列關鍵字

Organic Light Emitting Device (OLED) ； Square-Wave Driving Current ； External Digital Detecting System ； Detection of Degradation ； FPGA

參考文獻

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