AMOLED Panel Research Articles

P‐204: Simulation Study of Temperature Profile on AMOLED Panel Under High Brightness Mode

In this paper, we present a thermal simulation model designed to accurately predict the temperature distribution of AMOLED panel when operating in high brightness mode (HBM). The model incorporates panel geometric parameters, taking into account stacking configuration and material properties of actual OLED panel module. The simulation results demonstrate excellent agreement with the measured temperature distribution, with a maximum temperature difference of less than 1.5°. This thermal simulation model holds significant potential for evaluating OLED display performance and reliability risks associated with temperature increases. It can also serve as a valuable tool for guiding panel wiring design.

P‐4: The Technology of High‐Mobility Oxide TFT for 14inch AMOLED Display

In this paper, the technology of high‐mobility Oxide TFT, which is over 50 cm2/Vs within the whole panel, was introduced. The 14 inch AMOLED panel with the resolution of 2880*1800 and the refresh frequency of 1~144Hz was driven by oxide TFT including pixel circuits and Gate driver circuits, to decrease the cost of panel. In addition, the OLED was designed as Tandem structure to reduce the power consumption of panel.

14‐2: Development of High Mobility and Reliability Metal Oxide TFT for 13.2 inch AMOLED Display

The 13.2 inch AMOLED panel with 262 ppi has been fabricated with the high mobility metal oxide TFTs (thin film transistors). The high mobility oxide TFTs have high mobility ~34cm2 /Vs. On Gen. 6 glass, a small Vth variation with channel length 3.5um has been obtained. Moreover, the high mobility oxide TFT shows small Vth shift under positive/negative bias temperature stress (PBTS/NBTS).

P‐136: Simulation study on the lifetime of Rollable AMOLED Module

Different materials and stacking structures of multi‐layer will be arranged and combined when AMOLED panels are in rollable form. Many problems such as residual stress of deformation recovery, peeling of multi‐layer are usually happen during dynamic process and repeat motion, which can influence module lifetime directly. In this paper, we standardize the method of rollable simulation modeling, and then analyze related equivalent strain data of different multi‐layer structure in rollable form, derive the whole lifetime mapping of single material, predict the fatigue lifetime of rollable module after using kriging fitting. At last, we find that the accuracy of lifetime prediction is more than 80% by using these ways, which can greatly improve design efficiency.

Advanced hybrid process with back contact IGZO‐TFT

AbstractWe propose a new structure hybrid backplane technology with back contact IGZO‐TFT and LTPS. In this structure, IGZO is directly connected with intermediate metal to reduce the number of layers. The patterning process of IGZO and intermediate metal was optimized to realize superior IGZO/metal contact structure. The uniformity of contact resistance over a large area has been address for hybrid backplane. The characteristics of IGZO‐TFTs with high uniformity and reliability were confirmed. High‐quality AMOLED panels with new structure backplane have been adopted at smartphone with 6.6 in. display after severe reliability tests. We believe that the proposed structure would be useful for the mass‐production of OLED display with high quality and low cost.

A New IR-Drop Model That Improves Effectively the Brightness Uniformity of an AMOLED Panel

A New IR-Drop Model That Improves Effectively the Brightness Uniformity of an AMOLED Panel

A Mutual Capacitance Touch Readout IC with Synchronization in Touch and Mobile Display Driving for High Refresh Rate AMOLED Panels.

This paper presents a mutual capacitance touch readout IC architecture for 120 Hz high-refresh-rate AMOLED displays. In high-refresh-rate AMOLED panels, whole pixels in a horizontal line should be updated without any time-sharing with each other, leading to an amplified display noise on touch screen panel (TSP) electrodes. The proposed system architecture mitigates severe display noise by synchronizing the driving for the TSP and AMOLED pixel circuits. The proposed differential sensing technique, which is based on noise suppression in reference to mutual capacitance channels, minimizes common-mode display noise. In the front-end circuit, intrinsic circuit offset is cancelled by a chopping scheme, which correlates to the phase of the driving signals in the TSP driver and operating clocks of the front-end. Operating at a 120 Hz scan-rate, it reduces display noise by more than 11.6 dB when compared with the conventional single-ended TSP sensing method. With a built-in 130-nm CMOS, a prototype IC occupies an area of 8.02 mm2 while consuming 6.4-mW power from a 3.3 V analog voltage supply.

Reliability improvement of IGZO‐TFT in hybrid process with LTPS

AbstractAn AMOLED panel using hybrid backplane technology based on p‐type low temperature polycrystalline silicon (p‐LTPS) and n‐type indium–gallium–zinc–oxide (n‐IGZO) thin‐film transistors (TFTs) has been successfully manufactured. New pixel and Gate‐on‐Array (GOA) circuits were designed and fabricated using this technology. GOA with CMOS inverter is realized by utilizing both IGZO and p‐LTPS. The hybrid backplane AMOLED panel can operate between 1 and 120 Hz, which enables both high refresh rate and low standby power display applications. Furthermore, the AMOLED panel lifetime has markedly enhanced by improving IGZO TFT's uniformity and reliability.

7‐1: Distinguished Paper: Reliability Improvement of IGZO‐TFT in Hybrid Process with LTPS

An AMOLED panel using hybrid backplane technology based on p‐type LTPS and n‐type oxide has been successfully manufactured. New pixel and Gate‐on‐Array (GOA) circuits were designed and fabricated using this technology. CMOS operation of the GOA is realized by utilizing both IGZO and p‐LTPS. The hybrid backplane AMOLED panel can operate between 1 Hz and 120 Hz, which enables both high refresh rate and low standby power display applications. Furthermore, the AMOLED panel lifetime has markedly enhanced by improving IGZO TFT's uniformity and reliability.

P‐13: IGZO‐TFT Pixel Circuits Compensating Threshold Voltage and Mobility Variations in AMOLED Displays

This paper proposes two novel AMOLED pixel circuits for high‐quality AMOLED panels with the features of high refresh rate and high‐resolution: the 4T1C VPPC and the 6T2C VPPC. The proposed 4T1C pixel circuit can compensate for variation in threshold voltage of TFT, and simplify the working cycle of pixel circuit. The proposed 6T2C pixel circuit maintains the advantages of the 4T1C circuit and adds the compensation function for the mobility change of TFT.

P‐13.11: A 5.5 inch AMOLED Mirror Display

AMOLED mirror display, with a mirror integrated on the AMOLED panel, was fabricated for the first time. The metal mirror structure, aluminum layer as an example, was developed on the top of encapsulation layer using lithography technology. High quality of mirror effect was represented on a 5.5 AMOLED panel without degradation of display characteristics.

RGB-to-RGBG conversion by direct assignment with accurate feedback correction

ABSTRACT RGB-to-RGBG conversion is a critical step to enable the image display on AMOLED panel. RGB-to-RGBG conversion by direct assignment with accurate feedback correction (DAFC) is proposed in this paper. Firstly, direct assignment is executed to realise rough conversion. Subsequently, the grey level difference between the original pixel and the roughly converted pixel is computed, which will be regarded as the evidence to classify the present pixel as A, B or C-type and each type will correspond to a specific correction strategy. Finally, correction is executed to optimise the conversion quality. The conversion speed is greatly increased and the conversion quality is improved. The proposed conversion method is designed to an integrated circuit and downloaded to a FPGA. The experimental results show that MSE of DAFC is 16.96% and 3.68% lower than that of the DA and WF respectively. The value of PSNRU and PSNRV is 6.67% and 7.87% larger than that of DA respectively and nearly equal to that of EDMSE and WF. The conversion time of the proposed DAFC is 38.55% and 49.07% lower than that of EDMSE and WF respectively. Therefore, a high-speed and high-quality RGB-to-RGBG conversion method is realised in this paper.

15‐1: Invited Paper: Manufacturing Technology of LTPO TFT

Low‐Temperature Poly‐Si and Oxide (LTPO) thin‐film transistors (TFTs) have been successfully manufactured and the AMOLED panels with LTPO TFTs are adapted to Apple Watch. The manufacturing technology of LTPO TFT such as stack‐up structure, device characteristics, panel image quality with LRR driving, and degradation of reliability in oxide TFT is explained and discussed.

24‐4: Distinguished Paper: High Refresh Rate and Low Power Consumption AMOLED Panel Using Top‐gate n‐Oxide and p‐LTPS TFTs

A Pixel Circuit and a Gate Driver on Array for light‐emitting display are presented. By simultaneously utilizing Top‐Gate n‐type Oxide and p‐type LTPS TFTs, the circuits provide high refresh rate and low power consumption. An AMOLED panel with proposed circuits is fabricated and driving at various refresh rate ranging from 1Hz to 120Hz could be achieved.

84‐3: Invited Paper: Advanced Cover Window and Thin‐film Encapsulation Technologies for Foldable AMOLED Display

Foldable AMOLED enable some component technologies integration and continuously improvement. A roll to roll process integrated cover window with circular polarizer show the high mechanical strength and R3mm folding ability with AMOLED panel. And also, the advanced solution‐coated gas barrier is proposed to OLED thin film encapsulation for new flexible AMOLED form factor applications.

Effect of OCA properties on foldable AMOLED panel with a module structure

Effect of OCA properties on foldable AMOLED panel with a module structure

Effect of OCA properties on foldable AMOLED panel with a module structure

Effect of OCA properties on foldable AMOLED panel with a module structure

P‐168: Picture Quality and Uniformity Study on High Resolution Top Emission OLED Display Fabricated by Ink Jet Printing Process

To realize a middle size OLED panel (10~20 inch) manufactured by ink jet printing process. A high resolution OLED panel is needed. Because of high resolution, the top emission OLED is requirement to increase the pixel aperture ratio, lifetime and color gamut. The pixel resolution in our study is 167ppi, which meets the requirement for automotive vehicle application. We discuss the film quality and picture quality from ink jet printing process to address which pixel arrangement design can meet the demand of products. Finally, a 12 inch AMOLED panel is realized in our study.

P‐1.8: External Compensation for TFT Vth&Mobility Using Linear Charge Sense Method in AMOLED Display

A new method for Sense and Calculate TFT characteristics is simulated with 3T1C structure of AMOLED display. By using data programming compensation, it can correct both Vth and Mobility. The proposed method uses Linear Charging Method which has faster charging speed than Source Follower Method. By increasing the Vgs of driving TFT, we can even reduce the charging time to 0.5ms. And fast charging make it possible to achieve real‐time detection in higher and higher resolution display. The principle of the method will be described in detail and giving out the simulation data. The experiments are carried out in a 31‐inch AMOLED panel.

A novel algorithm for selective current limit used in AMOLED panel

AbstractA selective current limit algorithm based on color space conversion is proposed in this paper. There are mainly two advantages for this algorithm. Firstly, only the luminance component Y is decreased, and the color component Cb or Cr is not changed; thus, the color distortion is avoided in the process of current limit. Secondly, the current of pixels with high luminance is limited while that of those pixels with low luminance is not, which means current limit is executed selectively. For the same value of mean square error, the simulation results show that the ratio of pixels with high luminance of the image processed by the proposed algorithm is zero, and that processed by the net power control and the algorithm based on color space conversion is 0.081 and 0.0854, respectively. This algorithm is implemented on a field‐programmable gate array to drive the image display on the AMOLED panel.