&lt;title&gt;Passive and active matrix addressed polymer light-emitting diode displays&lt;/title&gt;

Biggelaar, Ton van de; Camps, I. G. J.; Childs, M. J.; Fleuster, M.; Giraldo, A.; Godfrey, Sandra; Hunter, I.; Johnson, Mark; Lifka, H.; Los, R.; Sempel, Aad; Shannon, John M.; Trainor, M. J.; Wilks, Richard W.; Young, N. D.

doi:10.1117/12.424868

Cited by 16 publications

(11 citation statements)

References 2 publications

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“…Other current writing circuits have been proposed that directly set the current in the OLED driving transistor 7,8,9 . Equivalent circuit diagrams are shown in figures 3 and 4 incorporating p-Si and a-Si TFT, respectively.…”

Section: Figure 2 Current Mirror Circuit Incorporating Data Currentmentioning

confidence: 99%

4.2: TFT AMOLED Pixel Circuits and Driving Methods

Sanford

Libsch

2003

Symp Digest of Tech Papers

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Active matrix organic light emitting diode (AMOLED) displays are now entering the market place. TFT active matrix allow OLED displays to be larger in size, higher in resolution and lower in power dissipation than is possible using a passive matrix. A number of TFT active matrix pixel circuits have been developed for luminance control while correcting for TFT parameter variations. The circuits and driving methods are reviewed. A new driving method is presented IntroductionThe high brightness and efficiencies of organic light emitting diodes (OLEDs) have created considerable interest for displays 1 . Initial OLED display products were first commercialized incorporating passive matrix addressing 2 . While passive matrix addressing simplifies the display fabrication, the number of rows are limited to few hundred. Since the OLED is on only while being addressed, high peak currents are required to obtain average brightness levels. Row line resistance, column line resistance, OLED resistance, OLED capacitance and OLED off current restrict display luminance, size, and format and reduces efficeincy 3,4 .Incorporating thin film transistors (TFTs), active matrix addressing is used to make large size and high resolution liquid crystal displays (LCDs). The impedance of the liquid crystal materials used is that of a capacitor that varies with applied voltage as the refractive index changes. Applied LC voltages alternate from frame to frame to avoid image sticking due to ion plating. The pixel circuit consists simply of a single transistor and storage capacitor. The data voltages and row signals allow alternating TFT terminal voltages that tend to stabilize transistor characteristics such as threshold voltage.OLEDs are somewhat difficult to drive uniformly with active matrix TFTs. The most important reasons are: (1) luminance is current, not voltage, dependent, (2) OLED capacitance is very high, (3) TFT dimensions are relatively large, (4) effective TFT gate to drain capacitance (Cgd) and gate to source capacitance (Cgs) are high and (5) TFT threshold voltages and mobilities may vary from one device to another. The drive TFT must provide current for an OLED to light up. The large TFT dimensions tend to limit transconductance such that OLED is driven a large percentage of a frame time. The large TFT dimensions also limit the number of TFTs that can fit in the available pixel area. Low temperature polysilicon (p-Si) has an advantage over amorphous silicon (a-Si) since mobility can be one to two orders of magnitude higher. Polysilicon transistor widths can be smaller. In addition, the terminal voltages can be lower giving more power efficient operation. The OLED capacitance is so large that the OLED current and voltage can't be driven in to equilibrium in a row time. This coupled with the large TFT terminal gate to source and drain capacitance may result in luminance that depends upon the previous OLED state. Variations in threshold voltage and mobility depending upon implementation may add to luminance variations. With p-Si, init...

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Section: Figure 2 Current Mirror Circuit Incorporating Data Currentmentioning

confidence: 99%

4.2: TFT AMOLED Pixel Circuits and Driving Methods

Sanford

Libsch

2003

Symp Digest of Tech Papers

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“…For application in AMOLED displays additionally to switching TFTs current driving TFTs are required. These TFTs require good saturation to compensate aging of the OLEDs [7] (the luminance/current characteristic of the OLED is less changed during aging than the I/V characteristic). For this purpose we realized TFTs with a channel geometry of W*L=10µm*40µm.…”

Section: / H Baurmentioning

confidence: 99%

33.4: Distinguished Student Paper: An LTPS Active-Matrix Process without Ion Doping

Baur

Jelting

Benson

et al. 2005

SID Symposium Digest

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A low temperature poly-silicon active matrix process without the need for ion implantation to dope drain and source areas of TFTs has been developed. A doped silicon layer is deposited by PECVD and structured prior to the deposition of the intrinsic silicon for the channel. The dopant is diffused and activated within the excimer laser crystallization step. N-channel test TFTs with different geometries and a 4 inch quarter-VGA AMLCD were realized. The TFT properties (mobility, on/off ratio, saturation, etc.) are suitable to realize AMLCDs, AMOLED displays and to integrate driver electronics on the displays. The substitution of ion doping by PECVD deposition overcomes a major limitation for panel sizes in poly-Si technology and avoids large investment costs for ion implantation equipment.

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“…Organic Light Emitting Diode (OLED) display has drawn much attention due to the advantages over Liquid Crystal Display (LCD) such as high contrast ratio, fast response time, wide viewing angel, light weight and thin module without backlight, etc. Given the limitations of passive matrix-OLED (PM-OLED) [1], the active matrix addressing is preferred for large high-resolution displays. Active-matrix backplanes provide a continuous current flow to the pixel for the entire frame time.…”

Section: Introductionmentioning

confidence: 99%

P-134: Novel Pixel Compensation Circuit for AMOLED Display

Peng

Chang

Tsai

2005

SID Symposium Digest

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A novel pixel circuit for active-matrix OLED has been developed and simulated. The circuitry is voltage-driven which compensates not only the threshold voltage (V th ) for TFT device but also the power voltage (PV dd ) for OLED. In this scheme, only one capacitor (C st ) is required to store the V th of the driving TFT as well as to hold the data during one frame time. The voltage drop of PV dd due to large current flown on the power line can also be cancelled out, which improves the uniformity of the brightness. The circuit operation and simulation results will be described and presented.

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<title>Passive and active matrix addressed polymer light-emitting diode displays</title>

Cited by 16 publications

References 2 publications

4.2: TFT AMOLED Pixel Circuits and Driving Methods

4.2: TFT AMOLED Pixel Circuits and Driving Methods

33.4: Distinguished Student Paper: An LTPS Active-Matrix Process without Ion Doping

P-134: Novel Pixel Compensation Circuit for AMOLED Display

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