Chun Da Tu

Low-Power Gate Driver Circuit for TFT-LCD Application

This paper presents a novel low-power gate driver circuit fabricated from glass by using hydrogenated amorphous silicon (a-Si:H) technology and a standard five-mask process. The tolerance of the threshold voltage shift of the proposed gate driver circuit can be estimated as 30 V by using an H-SPICE simulator. Measurement results indicate that the rising and falling times of the output waveform are equal to those in the initial state. Moreover, the proposed gate driver circuit can operate reliably at a high temperature (T = 120 °C) for over 360 h. Furthermore, the proposed gate driver circuit reduces power consumption by 77.3% over that of a conventional gate driver circuit.

Position Estimation and Smooth Tracking With a Fuzzy-Logic-Based Adaptive Strong Tracking Kalman Filter for Capacitive Touch Panels

This paper presents a novel 7-in capacitive touch panel (CTP) system with a smooth tracking algorithm that accurately estimates the position where the panel is touched and tracks the trajectory of touch. The proposed CTP system consists of a microcontroller unit, a sensor IC, and an interface board. When a user draws at different speeds, the measurement noise caused by the sensor IC induces an error in the touched position and zigzag trajectory, especially when the motion is slow. The fuzzy-logic-based adaptive strong tracking Kalman filter method is implemented in a CTP system to mitigate the effect of measurement noise and provide a smooth tracking trajectory at different speeds. Moreover, the approach effectively measures and quantifies the “smoothness” of the touched trajectory. Experimental results indicate that the proposed method reduces the measurement noise and decreases the mean tracking error by 85.4% over that achieved using the moving average filter.

LTPS-TFT Pixel Circuit to Compensate for OLED Luminance Degradation in Three-Dimensional AMOLED Display

A new low-temperature polysilicon thin-film-transistor pixel circuit for 3-D active-matrix organic light-emitting diode (OLED) display and its driving scheme that is based on simultaneous emission at a frame rate of 240 Hz are proposed. The proposed circuit can compensate for the threshold voltage deviation of TFTs and power-line IR-drops. Moreover, the degradation of OLED luminance is reduced using a feedback structure. The measurement results of the relationship between the luminance degradation and the threshold voltage shift of the OLED confirmed the stability of the luminance of the proposed circuit.

Driving Scheme Using Bootstrapping Method for Blue-Phase LCDs

We present a new pixel circuit on glass using hydrogenated amorphous silicon (a-Si:H) for driving polymer-stabilized blue-phase liquid crystal displays (BPLCDs). Different from conventional nematics, BPLC demands a large dielectric anisotropy in order to lower the operation voltage. As a result, the pixels capacitance is increased by ~ 10×, which seriously limits the charging capability and optical efficiency. Simulation results show that the average error rate of storage voltage in pixel circuit is below 5.14% for 180 Hz operating frequency.

Highly Reliable Integrated Gate Driver Circuit for Large TFT-LCD Applications

This letter presents a novel integrated hydrogenated amorphous silicon thin-film transistor (a-Si:H TFT) gate driver circuit using ac driving (33% duty) to prevent the floating of row lines and reduce the bias voltage of pull-down TFTs to suppress the threshold voltage (VTH) shift of a-Si:H TFTs. The VTH shift of the TFTs in this design is reduced by 49.93% from that achieved using the 25%-duty ac-driving structure. In a reliability test, the new circuit operates stably at a high temperature (T = 60°C) for more than 240 h.

2-D–3-D Switchable Gate Driver Circuit for TFT-LCD Applications

This paper presents a novel 2-D-3-D switchable gate driver circuit for active-matrix liquid crystal displays (AMLCDs) applications using the hydrogenated amorphous silicon (a-Si:H) technology. While consisting of 12 thin-film transistors (TFTs), the proposed gate driver circuit includes a pull-up circuit, two alternative circuits, and a key pull-down circuit. To provide a stable output waveform for switching between the 2-D and 3-D modes in AMLCD panel, the proposed circuit can improve the threshold voltage shift of a-Si:H TFT using reversed bias stress. Based on a real circuit integrated on glass with a standard five-mask process applied to a large-sized FHD TFT-LCD panel, the layout area of each gate driver circuit is 359.25 μm × 2296.25 μm. In addition, the power consumption of a 12-stage gate driver circuit is 3.25 and 7.21 mW, while operating at 2-D and 3-D modes, respectively. Measurement results indicate that the output waveform, including output voltage, rising time, and falling time can be stabilized and made almost equal to the initial state after the reliability test at 100 °C over 240 h.

Low-Power a-Si:H Gate Driver Circuit With Threshold-Voltage-Shift Recovery and Synchronously Controlled Pull-Down Scheme

This paper presents a new low-power gate driver circuit designed by hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs). An attempt is also made to reduce the power consumption resulting from the high-frequency pulldown structure, in which a pair of 0.25-Hz clock signals is used to implement a low-frequency and synchronously controlled pull-down scheme for recovering the threshold voltage shifts of a-Si:H TFTs under the negative gate-to-source voltage and decreasing the used TFTs. Measurement results indicate that the proposed gate driver circuit consumes 98.7 μW/stage, and the output waveforms are very stable without distortion when the proposed circuit is operated at 100 °C for 840 h. Furthermore, the feasibility of the proposed gate driver circuit is demonstrated for the quad-extended-video-graphics-array resolution.

Novel Dual-Coupling Pixel Circuit to Achieve High Transmittance of Blue-Phase Liquid Crystal

A new pixel circuit for in-plane switching blue-phase liquid crystal displays (IPS BPLCDs) is developed. The dual-coupling method enables the proposed circuit to generate twice the maximum output voltage of source driver integrated circuits (ICs) for the BPLC with a simple structure, so the achievable transmittance is about four times that of the BPLC that is simply driven using practical source driver ICs. A 10.1-in prototype IPS BPLC panel (720 × 360) and simulation results demonstrate the feasibility of the proposed circuit for practical BPLCD applications, and the tone rendering distortion index is as low as 0.11.

Design of Pixel Circuits for Blue-Phase Liquid Crystal Displays

This work reviews pixel circuits for blue-phase liquid crystal displays (BPLCDs) and presents two novel pixel circuits for the BPLC. With respect to the high-operating-voltage BPLC, the first developed pixel circuit comprises practical source driver integrated circuits (ICs) and an additional signal with three voltage levels to widen the voltage range from a data line in order to enable the BPLC to achieve high transmittance. For the low-operating-voltage BPLC with a large dielectric anisotropy, the second pixel circuit boosts the gate voltage of the switch thin-film transistor (TFT) to enhance its driving capability to deal with the large equivalent capacitance of the BPLC. Simulation results verify the functions of both new pixel circuits with Full High Definition (FHD, 1920 ×1080) resolution and a frame rate of 120 Hz.