Gate Driver On Array Research Articles

80‐3: Distinguished Paper: 47.5 inch 8K Inkjet Printing AMOLED MNT with Local Boosting GOA Design

In this paper, we presented a 47.5 inch 8K2K AMOLED MNT employing a LTPS backplane, top emissive inkjet printing (IJP) OLED devices and gate driver on array (GOA) supporting independent 32*9 zone control and internal compensation driving. It is so far the first prototype AMOLED MNT integrating inkjet printing process and local high frame rate (up to 960Hz) driving. Thanks to the high resolution, local frame rate data processing and superior IJP OLED EL, it shows a brand new approach to deliver a premium display.

P‐247: Late‐News Poster: Integrated Gate Driver Circuit with Self‐compensation Function Using Oxide TFTs for AMOLED Displays

In this paper, we demonstrate a novel GOA (gate driver on array) circuit which has a self‐compensation function. This circuit not only reduces the number of TFTs but also improves the reliability characteristics of AMOLED panels. Meanwhile there is no additional cost compared to conventional structure. The proposed GOA circuit in 5‐inch experiment panel had passed 1000 hours of high temperature (60°C;) reliability test.

39‐4: An Innovative Decoder‐type GOA for Intelligent Split‐Screen and External Compensation Technology

In this paper, an innovative decoder‐type gate driver on array (GOA) model employing IGZO TFTs is proposed, which is suitable for intelligent split‐screen (ISS) and external compensation technology. At the same time, we explored a new multi‐frequency driving method through this model, and through the verification of panel actual measurement, this new multi‐frequency driving almost eliminates the Mura caused by different frequencies in split‐screen. Finally, we successfully used this model to light up a 5‐inch AMOLED display with 170PPI bottom emission, and achieved a border of only 5mm.

Realization of Dynamic Local Refresh on Liquid Crystal Display with Novel Partial Scan Gate Driver on Array

AbstractIn this paper, a novel partial scan Gate Driver on Array (GOA) architecture with gate and cascade scan separated output (GCSS‐GOA) is proposed. Combined with a newly designed timing controller (TCON) IC and IP, dynamic local refresh at any position and with different refresh rate at different area on liquid crystal display (LCD) panel are achieved. The driving schemes for dynamic local refresh and the display image quality evaluation results are also presented. For power consumption, it can be reduced by up to 50% respectively for GOA and data drivers in dynamic local refresh mode under 60 Hz benchmark refresh rate. This technology is also applicable to OLED, LED, e‐paper and other display products.

47.5‐inch 8K inkjet printing AMOLED monitor with local boosting gate driver on array design

AbstractIn this paper, we presented a 47.5 in. 8K2K AMOLED MNT employing a low temperature poly‐silicon (LTPS) backplane, top emissive inkjet printing (IJP) OLED devices, and gate driver on array (GOA) supporting independent 32 * 9 zone control and internal compensation driving. By combining printed RGB units with a common evaporative blue stack, we proposed the hybrid tandem IJP devices that improved both device efficiency and operation load balance. In the local boosting GOA design, a novel architecture for independent display partition control was developed. The GOA cascading and timing scheme was carefully considered by reusing several clock signals to support both TFT internal compensation and display zone control. It is so far the first prototype AMOLED MNT integrating inkjet printing process and local high frame rate (up to 960 Hz) driving. Thanks to the 8K2K high resolution, local frame rate data processing, and IJP OLED EL reaching HDR brightness up to 580 nits with superior optical performance, it shows a brand‐new approach to deliver a premium display.

Adjusting Ag deposition power to improve corrosion resistance of ITO/Ag/ITO film for gate driver on array

Gate Driver on Array (GOA) can fulfil narrow-frame full screen of display device, but may encounter through-hole burnout during operation due to electrochemical corrosion under high-temperature and high-humidity environments. Through-hole burnout originates from vapor that penetrates display sealant and invades signal-conducting through-hole in GOA, and results from action of electrochemistry and Joule heat. In this work, ITO/Ag/ITO films were deposited by direct current (DC) sputtering using ITO and Ag targets. This work attempts to reduce electrical resistivity, while limiting electrochemical corrosion of film by adjusting Ag deposition power. We found that high crystallinity and smooth morphology can inhibit vapor accumulation for Ag film prepared at a power of 8 kW, along with favorable sheet resistance and etching slope angle as low as 0.31 Ω/sq and 73.1°, respectively. Such film can run normally for 200 h in field test at a temperature of 85 °C and a humidity of 85 % with absence of through-hole corrosion. The outcomes of this work pave the way for industrial application of the narrow-frame full screen with virtues of both low resistance value and electrochemical corrosion resistance.

Highly reliable a‐Si:H gate driver on array with complementary double‐sided noise‐eliminating and dual voltage levels for TFT‐LCD applications

AbstractIn this work, we present a high‐reliability gate driver on array (GOA) for a 10.7‐in. HD (1,280 × RGB × 720) TFT‐LCD panel, featuring an alternatively double‐sided noise‐eliminating function. The gate driver circuit is designed with 12‐phase clock signals that exhibit 75% signal overlapping, threshold voltage recovering, and double‐sided driving schemes. The double‐sided driving scheme reduces the number of mental wires and TFTs in the gate driver circuit, resulting in a smaller layout area for GOA. By utilizing dual levels of voltage, we implemented a negative gate bias method to mitigate threshold voltage shifts for the noise‐eliminating and driving TFTs. This prevents the noises from clock signals effectively. The reliability test of the proposed GOA with 720 stages passed a strict testing condition (90°C and −40°C) for simulation and exhibited good performance over 800 hours at 90°C for measurement.

56‐1: Invited Paper: Ultra‐high Frame Rate ADS LCDs

In recent years, LCD end‐users are putting forward higher and higher requirements for dynamic picture display realism. With the increase of display panel refresh rate, dynamic picture fidelity has a significant improvement. The extremely high refresh rate has become one of the most important indicators of high‐end display panels, especially for video game usage scenarios. However, the increase in refresh rate is a challenge to the drive capability of LCD semiconductor TFTs (Thin Film Transistor), the response time of liquid crystal, and the transmission of high‐frequency signals, resulting in the maximum refresh rate of high‐refresh‐rate displays currently on the market still at 240 ~ 300 Hz. In this paper, we solve the display distortion due to low charging ratio at ultra‐high refresh rate by improving GOA（Gate Driver on Array） driver circuit and applying high stability and high mobility bilayer oxide semiconductor technology. At the same time, the 1ms GTG (Gray to Gray) response time is achieved by testing and optimizing the pixel slit angle and cell gap of ADS (Advanced Super Dimension Switch) LCD, ensuring no image trailing at refresh rates up to 600 Hz. Then the anti‐electromagnetic interference ability of high‐speed signal is improved by high‐speed signal transmission quality enhancement technology. Through the application of the above technologies, we have developed the ultra‐high refresh rate IT display panel products such as 600Hz frame rate FHD NB LCD and 500 Hz FHD MNT LCD. And the 16.0” WUXGA 600Hz ADS LCD achieves the highest CMR 9000 rating in VESA latest dynamic picture CMR certification.

38.3: Compact Gate Driver on Array for Progressive‐mode PWM Micro‐LED Display using LTPS TFTs

A compact gate driver on array (GOA) was proposed for Micro‐Light Emitting diodes (Micro‐LED) display based on progressive‐mode pulse‐width modulation (PWM) using low‐temperature‐polysilicon (LTPS) thin‐film transistors (TFTs). Thanks to outputting line‐by‐line scanning (Scan) and emission control signals (EM) to address switching‐and emission‐transistors in Micro‐LED pixel circuit, the proposed GOA circuit enables an increased emission time by 60% with the frame rate of 120 Hz, compared with the conventional GOA circuit of simultaneous operating mode. Furthermore, the pulse‐width of EM signals are programmable simply by adjusting the number of input pulses.

Gate Driver on Array With Multiple Outputs and Variable Pulse Widths for Low-Temperature Polysilicon and Oxide (LTPO) TFTs Driven AMOLED Displays

A gate driver on array (GOA) circuit was proposed for low-temperature polysilicon and oxide (LTPO) thin-film transistor (TFT) hybrid-driven active matrix organic light-emitting diode (AMOLED) displays with both high and low refresh rate operation. The GOA generates multiple types of scanning signals by reusing shift registers so that three signal pulses are output parallelly within a single stage to scan p- and n-type switching TFTs and emission TFT of the AMOLED pixels, respectively, leading to a 30% reduction in the layout area. Furthermore, the pulse-width of the scan signals for the emission TFT can be programed simply by changing the number of input pulses to vary refresh rates. The fabricated GOAs work well even with the pulse width reduced to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.9 \mathbf {\mu }\text{s}$ </tex-math></inline-formula> .

50.3: MPRT Enhancement Gate Driver Circuit Employing IGZO TFTs for Image‐Quality Improvement

50.3: MPRT Enhancement Gate Driver Circuit Employing IGZO TFTs for Image‐Quality Improvement

P‐44: MPRT Enhancement Gate Driver Circuit Employing IGZO TFTs for Image‐Quality Improvement

We present a novel gate driver circuit using IGZO TFTs which can decrease the MPRT (Motion Picture Response Time) value from 6.8ms to 3.4ms at the frequency of 120Hz. And this means the OLED panels’ image quality can be greatly improved through motion blur reduction. The MPRT enhancement GOA (Gate driver on array) can output three kinds of waveforms for normal display, black data insertion and external compensation within one frame. We save 14 TFTs and 2 capacitors through sharing sense input and hold unit, black data inserting input unit and leakage prevention unit between two adjacent rows which greatly simplify our multifunction GOA structure. This circuit is verified at high temperature (50℃) companied with high humidity (80% RH) during 500 hours with no problem through 15.6 inch experiment panels which resolution is 768 columns by 2160 rows. Besides, the proposed structure can make our future 30inch 4K2K panel to achieve a narrow bezel smaller than 7mm.

Adjusting indium-tin-oxide film thickness to improve electrochemical corrosion resistance of gate driver on array

Common narrow-bezel display suffers from the abnormal display in the high-temperature and high-humidity environments, resulting in an early device failure. Improving electrochemical corrosion resistance of gate driver on array (GOA) may overcome the drawback of the display. Adjusting film thickness of indium tin oxide (ITO) on GOA through-hole is proposed to in situ improve the electrochemical corrosion resistance. Nano-ITO film with four different thicknesses were deposited in a direct-current magnetron sputter system. A systematic investigation was conducted on their microstructure and photoelectric performances, and a high-temperature and high-humidity display test was employed for field test. The 80.1-nm film exhibited superior surface smoothness and photoelectric performance, and the assembled GOA unit presented the best electrochemical corrosion resistance. We demonstrated that adjusting ITO film thickness may prevent the intrusion from water vapor and reduce the generation of resistance heat.

Failure analysis of ESD damage on interconnects in LCD GOA

Liquid crystal display (LCD) is likely to accumulate charge and incur ESD events due to the insulating glass plate. In our study, an ESD induced failure of interconnects in LCD gate driver on array (GOA) was analyzed. The monochrome pattern test was conducted to locate the failure site. The morphology of the failure site was characterized by SEM, EDS and FIB. Charge accumulation on long interconnects in the VUV-cleaning process, and subsequent discharging damage at narrow interconnect gaps were analyzed to be the root cause of failure. Furthermore, some specimens were designed to validate the analysis, design of experiments was performed to study the effects of the gap space and the interconnect length on the failure severity. Based on the experimental data, a logistic model was developed to model the failure severity, which can help to provide suggestions for designs to reduce the incidence of failures.

4.2: External compensation Type OLED Panel Using Novel Gate Driver Circuit with Depletion‐Mode IGZO TFTs

A novel gate driver circuit was shown in this paper which was prepared for 55inch 8K4K OLED panel. The new schematic can realize display images and sensing TFT characteristics for external compensation. At high temperature (50 °C) companied with high humidity (80% RH) this circuit could work normally for more than 500 hours based on 5 inch experiment panels. And at very low temperature (‐20 °C) our panel also had a well performance. Besides, this novel GOA (Gate driver on array) circuit can make our future 55inch panel to achieve a narrow bezel smaller than 8mm

2.1: Invited Paper: 16.9‐Inch Flexible AMOLED Display with High Performance Top Gate Oxide TFT

We have fabricated top‐gate IGZO TFTs on PI substrate, which exhibit excellent electrical properties and high mechanical reliabilities to meet the demand for large area flexible display. The ΔVth under PBTS and NBTIS for 10 hours are only +0.26 V and −0.34 V, respectively. The mechanical bending properties of the TFT backplane is investigated. There are almost no change after 200,000 bending cycle test at a curvature radius of 20mm. To improve flexible capability and reduce cost of flexible OLED display, integrated gate driver on array (GOA) circuits with spilt channel structure has been investigated. Finally, we successfully realize 16.9‐inch rollable OLED display with high performance top gate IGZO TFT and GOA circuits

47.1: Invited Paper: Development of 55inch 8k AMOLED TV by Inkjet Printing Process

In this paper, we presented 55 inch 8K4K AMOLED TV employing coplanar Oxide TFT backplane, top emissive inkjet‐printing OLED device, Gate Driver on Array(GOA) and compensation technologies. It is so far the largest prototype AMOLED TV fabricated by using inkjet printing process with 8K resolution. It shows the stunning display quality thanks to the high resolution and fast refresh frequency. It proves that the inkjet printing process is not only cost competitive but also can deliver premium display.

34‐2: Distinguished Paper: Development of 55inch 8K AMOLED TV by Inkjet Printing Process

In this paper, we presented 55 inch 8K4K AMOLED TV employing coplanar Oxide TFT backplane, top emissive inkjet‐printing OLED device, Gate Driver on Array(GOA) and compensation technologies. It is so far the largest prototype AMOLED TV fabricated by using inkjet printing process with 8K resolution. It shows the stunning display quality thanks to the high resolution and fast refresh frequency. It proves that the inkjet printing process is not only cost competitive but also can deliver premium display.

38‐3: A Novel Gate Driver Circuit Employing IGZO TFTs for External Compensation

We present a novel gate driver circuit which has been applied in 55inch 8K4K printing OLEO panel not only for display images but also for sensing TFT characteristics for external compensation. This circuit is verified at high temperature (50°C) companied with high humidity (80% RH) during 500 hours with no problem through 5 inch experiment panels. And it also can work normally at very low temperature (−20°C). Meanwhile, this novel GOA (Gate driver on array) circuit helps our panel achieve a narrow bezel smaller than 8mm.

Development of 55‐in. 8K AMOLED TV based on coplanar oxide thin‐film transistors and inkjet printing process

AbstractIn this paper, we presented 55‐in. 8K4K AMOLED TV employing coplanar oxide thin‐film transistor (TFT) backplane, top emissive inkjet‐printing organic light‐emitting diode (OLED) device, gate driver on array (GOA), and compensation technologies. It is so far the largest prototype AMOLED TV fabricated by using inkjet printing process with 8K resolution. It shows the stunning display quality, thanks to the high resolution and fast refresh frequency. It proves that the inkjet printing process is not only cost competitive but also can deliver premium display.