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A driving method has been developed for a 2D-3D switchable AMOLED using progressive emission PE or simultaneous emission SE. The proposed method is implemented by selecting PE mode for 2D to improve light emission ratio and SE mode for 3D to reduce left-right crosstalk without sacrificing luminance. This method also improves the contrast ratio by removing unnecessary light emission and can offer better uniformity by increasing the threshold voltage compensation time. A 240Hz-driven 30″ 3D AMOLED display was built and it was confirmed that there is no ELVDD surge current in the SE mode.

Stereoscopic 3D displays are generally operated at 240Hz in order to fully separate left eye and right eye images. New low frequency driving methods are proposed for 3D displays. In addition to reducing driving frequency, the new driving methods can increase luminance and reduce cross-talk and power consumption.

Simultaneous Emission with Active Voltage control (SEAV) is a strong candidate for crosstalk-free driving of 3D Active Matrix Organic Light Emitting Diode (AMOLED) displays. A gate driver for a SEAV 3D AMOLED panel needs two operating modes: the simultaneous switching mode and the progressive scanning mode. However, conventional gate drivers can operate in only progressive scanning mode. In this paper, a new integrated gate driver to support both of these modes is proposed and applied to a prototype 3D AMOLED display panel.

An advanced method for externally compensating the nonuniform electrical characteristics of polycrystalline silicon thin-film transistors (TFTs) and the degradation of organic light-emitting diode (OLED) devices is proposed, and the method is verified using a 14.1-in active matrix OLED (AMOLED) panel. The proposed method provides an effective solution for high-image-quality AMOLED displays by removing IR-drop and temperature effects during the sensing and displaying operations of the external compensation method. Experimental results show that the electrical characteristics of TFTs and OLEDs are successfully sensed, and that the stained image pattern due to the nonuniform luminance error and the differential aging of the OLED is removed. The luminance error range without compensation is from -6.1% to 9.0%, but it is from -1.1% to 1.2% using the external compensation at the luminance level of 120 cd/m2 in a 14.1-inch AMOLED panel.

An 8b source driver for 2.0 inch QVGA active-matrix OLEDs is fabricated using LTPS TFTs. This driver uses an 8b DAC that is separated into two parts, a 1-to-3 DEMUX, and a pre-charge method. This scheme reduces the source driver size by 40%. The maximum DNL is under 1LSB. The output voltage variation of the source driver is less than 1 LSB even though the variation of the threshold voltage is plusmn0.5V

In this paper, the conventional voltage drop compensation methods are reviewed and the novel design and driving scheme, the advanced power de-coupled (aPDC) driving method, is proposed to effectively compensate the voltage IR drop of active matrix light emitting diode (AMOLED) displays. The advanced PDC driving scheme can be applied to general AMOLED pixel circuits that have been developed with only minor modification or without requiring modification in pixel circuit. A 14-in. AMOLED panel with the aPDC driving scheme was fabricated. Long range uniformity (LRU) of the 14-in. AMOLED panel was improved from 43% without the aPDC driving scheme, to over 87% at the same brightness by using the scheme and the layout complexity of the panel with new design scheme is less than that of the panel with the conventional design scheme.

— Large-sized active-matrix organic light-emitting diode (AMOLED) displays require high-frame-rate driving technology to achieve high-quality 3-D images. However, higher-frame-rate driving decreases the time available for compensating Vth in the pixel circuit. Therefore, a new method needs to be developed to compensate the pixel circuit in a shorter time interval. In this work, image quality of a 14-in. quarter full-high-definition (qFHD) AMOLED driven at a frame rate of over 240 Hz was investigated. It was found that image degradation is related to the time available for compensation of the driving TFT threshold voltage. To solve this problem, novel AMOLED pixel circuits for high-speed operation are proposed to compensate threshold-voltage variation at frame rates above 240 Hz. When Vth is varied over ±1.0 V, conventional pixel circuits showed current deviations of 22.8 and 39.8% at 240 and 480 Hz, respectively, while the new pixel circuits showed deviations of only 2.6 and 5.4%.

14.1” qFHD quarter Full High Definition Transparent Active Matrix Organic Light Emitting Display AM OLED was developed with the well known and reliable technology based on LTPS Low Temperature Poly Silicon backplane. The key concept of the transparent AM OLED display lies on the seethrough window on each pixel so that the objects across the device can be seen. In the design of pixel structure, functional separation of light emitting area and seethrough area was realized on the different regions. The features of transparency and transmitted image quality were investigated and optimized in the design of the pixel structure. Up to 38% transparency of the prototype panel was accomplished with the high transparent cathode material which transmittance was more than 75%. LTPS based Active Matrix and Top emission OLED structure was used for the prototype to provide wide range of color expression, more than 100% of color gamut.

— To comparatively evaluate various driving methods of an electronic display in respect to image sticking, a consistent and reliable quantification method is required. For proper evaluation, the entire area of a display is often monitored by using a chessboard pattern, and long-range gradual luminous variation in the background is eliminated. Estimation in terms of a single number is also preferred for simple comparison of image sticking. However, the prior method that uses the initial luminance for normalization and estimates the range-to-maximum ratio is not well-suited for the driving methods that relieve image sticking by restoring luminance uniformity. We have developed a method of extracting reference values for normalization and introduced the relative standard deviation (RSD) into our estimation. The resulting method is insensitive to the temporal change in the long-range gradual luminous variation and sufficiently indicative to allow driving methods to be compared effectively. The reference extraction method and the indicative capability of the RSD have been assessed by experiments using a real active-matrix organic light-emitting-diode (AMOLED) display cell.

With an excimer laser annealing (ELA) process, maximum display size is limited by the laser beam length because performance variations of the transistors in the overlapped regions cannot be sufficiently compensated to remove the brightness non-uniformity. In this paper, a redundant pixel line design is proposed to remove overlap mura. A 4.82″ AMOLED was successfully fabricated in order to verify the panel design method.

A new estimation method for image sticking has been developed that can effectively eliminate the influence by the difference in long-range non-uniformity pattern. An 8×8 chessboard pattern was used for selective degradation, and normalization based on extracted reference and coefficient of variation were adopted for better results.

— Early loss of image uniformity has been a critical drawback of active-matrix organic light-emitting-diode (AMOLED) displays operated in time-ratio gray-scale mode. This problem is addressed with an analog calibration technique which measures the voltage across each OLED for a given current and subsequently controls the supply voltage of pixels and the voltage drop across the driving th in-film transistor (TFT) of each OLED. The uniformity of test cells, which were aged to produce image sticking in a chessboard pattern, were improved. A measure of image sticking, called the extracted image-sticking value (EISV), was formulated, which is developed and used for the quantitative evaluation of the calibration method. OLED voltages over a range of about 0.35 V were compensated to produce more uniform OLED currents than those before aging. The variation of luminance associated with image sticking was reduced by about 40% for a full-white image after between 2 and 10 hours of accelerated aging with a constant voltage of 8 V across an OLED.

We propose a new hybrid pixel driving method that combines conventional digital driving with analog compensation for the declining electrical performance that occurs as OLEDs age. Image uniformity, and thus display lifetime, is improved by directly measuring the variation in OLED voltage at each pixel for a given OLED current level and then controlling the voltage drop across its driving TFT of an individual pixel.

RGB adjustable gamma compensation circuit to choose one of the three different gamma characteristics for each color has been integrated by LTPS TFT for AMOLED. A timing controller to generate all timing signals for a 6-bit data driver and a scanning driver has also been integrated by the TFT on the AMOLED panel.