臺灣博碩士論文加值系統

本論文提出一種適用於高解析度畫素驅動電路的新式方法－『Sentinel
Voltage Control Method』，其主要應用於主動式發光二極體顯示器。藉由在
躍升的電壓訊號讓畫素驅動電壓，並在訊號到達所求訊號時，實時停止訊號
攀升。這樣的畫素電路外的外部補償方式能夠以三顆薄膜電晶體及一顆儲存
電容來驅動畫素電路，製程上相對簡易，亦可輕易實現高開口率之顯示器。
除此之外，由於主動式發光二極體顯示器之亮度，係取決於流經有機發
光二極體的電流大小，而其驅動電流會隨有機發光二極體之發光面積縮減，
而跟著降低，甚至降低至薄膜電晶體之次臨界電流區間。由於此操作區間電
流變化相當劇烈，視訊電壓操控上極為不易，導致實現高PPI 顯示器面臨極
大的挑戰。因此，本研究所提出之補償方式，不僅可以有效解決目前高解析
度主動式有機發光二極體面板驅動電路，在小電流控制之問題，亦能避免傳
統有機發光二極體之老化及臨界電壓飄移問題。有別於傳統的外部補償電路，
本技術所提出之外部補償方式為真實時間的補償，在Driver IC 上不需有記
憶體的設置, 因此可節省了外部IC 板並降低Driver IC 研發成本。
隨著各種使用行動顯示器的產品，逐漸成為我們生活中不可或缺的工具，
如智慧型手機、平板電腦、穿戴試裝置、擴增實境及虛擬實境…等，此技術
必將更加廣泛地被使用。

In this paper, we present a [novel sentinel voltage control method] of
external compensating driving circuit which could mainly be applied to the
active-matrix organic light-emitting diode displays (AMOLED). The pixel driving
current is gradually increased by the ramp voltage at gate and converted to voltage in
real time. When the sensed voltage is equal to the sentinel voltage, the gate voltage
stops changing. Thus, the gate voltage is pinched at the value corresponding to the
target driving current. The pixel contains only three thin-film transistors (TFTs) and
one capacitor, which is suitable for high PPI display. Owing to the small area of the
high PPI pixel, the operation current of driving TFT may drop down to an extremely
low level. However, this compensation circuit can work for low current level, even
when the TFT is operated in the subthreshold where the current exponentially varies
III
with its gate voltage.
Although the compensation circuit can be successfully operated, there are still
some issue needs to solve when it works. Hence, we proposed an advanced version of
this external compensation circuit in the following chapter. Regarding to different
issue, we present multiply approaches to overcome them and make the circuit design
complete.
Thus, using these compensation circuit can conquer the operation difficulty of high
PPI AMOLED and make external driver IC work simple by pinching off signal at
expected value. Along with display panels in mobile devices, wearable devices,
Augmented Reality (AR) products and Virtual Reality (VR) products being
indispensable tools in recent years, these techniques are sure to be widely used.

Contents
Chinese Abstract ............................................................I
English Abstract ............................................................II
Acknowledgements......................................................IV
Contents .........................................................................V
Figure Captions ........................................................VIII
Table Captions ..............................................................X
Chapter 1 Introduction……………………….........1
1.1 Background and Motivation………………...….…..1
1.2 Paper Review………………...….………………….2
1.3 Specification………………...….…..………………3
1.4 Thesis Organization………………………....……...3
Chapter 2 Proposed Pixel Circuit………….…….10
2.1 Scheme and Operation…………………………….10
2.1.1 Circuit Design…………………………………...10
2.1.2 Circuit Operation………………………………..11
2.2 Simulation………………………..……………..…12
2.2.1 Transient Analysis & TFT Variation………….…12
VI
2.2.2 IOLED vs. Isense……………………………………13
2.2.3 Vdata vs. IOLED………………………...……...…..13
2.3 Verification…………………...……….…………...14
2.3.1 Experiment Setup…...………….…………….….14
2.3.2 Experiment Result.……….……………...……...14
2.4 Summary………………………………...……..…15
Chapter 3 Discussion……………...……………...23
3.1 Subthreshold Operation…….……...………......23
3.1.1 Issue……………………………….....………23
3.1.2 Solution………..……………...…..………....24
3.2 Double Pin Counts…...……………...…………25
3.2.1 Issue of Previous Version………….....………25
3.2.2 Propose Solution of Pin Counts…....................26
3.2.3 Circuit Operation………………………………..26
3.2.4 Simulation Result………………………………..27
3.3 Feedback Delay………………………......…...28
3.3.1 Issue ………………….................................28
3.3.2 Delay Compensation Approach Ver.1………....29
3.3.3 Delay Compensation Approach Ver.2…….……..29
VII
3.3.4 Delay Compensation Approach Ver.3………....30
3.4 Summary………………….…………….……31
Chapter 4 Conclusions and Future Works...........44
4.1 Conclusion........................................................44
4.2 Futures Works...................................................45
References................................................................46

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