Browsing by Author "Lee, Kuei-Yu"

Now showing 1 - 6 of 6

A New 4T0.5C AMOLED Pixel Circuit With Reverse Bias to Alleviate OLED Degradation
(2012-07-01)
Lee, Kuei-Yu
;
Hsu, Yen-Ping
;
Chao, Paul C. -P.
;
交大名義發表
;
National Chiao Tung University
A new 4T0.5C circuit is proposed to achieve a high-resolution active-matrix organic light-emitting diode (OLED) display with the capability of alleviating OLED degradation, while the panel nonuniformity is compensated by an already-proposed system. The designed circuit is built on two adjacent pixels with eight transistors and one capacitor, thus equivalently as a 4T0.5C pixel circuit in occupied layout area. In this circuit, a single storage capacitor is shared by the two adjacent pixels to minimize the entire layout area. The minimized pixel size is compatible to a conventional 2T1C pixel circuit. Along with this 4T0.5C circuit, a new alternative drive scheme is developed to address the panel. The scheme offers the function of automatic reverse biasing on OLEDs to alleviate degradation. The designed circuit is fabricated, and the performance of OLED degradation is successfully validated.
A New AMOLED Pixel Circuit With Pulsed Drive and Reverse Bias to Alleviate OLED Degradation
(2012-04-01)
Lee, Kuei-Yu
;
Chao, Paul C. -P.
;
電機工程學系
;
Department of Electrical and Computer Engineering
This paper proposes a new pixel circuit for an active matrix organic light-emitting diode (OLED) display, which consists of five thin-film transistors (TFTs) and one capacitor. This circuit develops techniques of pulsed drive and reverse bias to achieve desired emitted brightness levels and elongate OLED life times, respectively. A current mirror is also adopted in the circuit to minimize emission nonuniformity of the OLED panel. The required input data voltages for varied displayed gray levels are calculated based on analytically known TFT and OLED models and the designed circuit architecture. The designed pixel circuit is simulated with realistic TFT models for validating expected performance to realize 256 gray levels and minimizing nonuniformity. The designed circuit is implemented in a 2.4-in quarter video graphics array panel, which shows favorable performance for minimizing display nonuniformity and alleviating OLED degradation. In addition, a closeness is clearly observed among analytical predictions, simulations, and experimental measurements.
A New Compensation Method for Emission Degradation in an AMOLED Display Via an External Algorithm, New Pixel Circuit, and Models of Prior Measurements
(2014-03-01)
Lee, Kuei-Yu
;
Hsu, Yen-Ping
;
Chao, Paul C. -P.
;
Chen, Wei-Dar
;
電機工程學系
A new external algorithm with sensing circuit are proposed to compensate AMOLED display degradation. The compensation is enabled by first evaluating degradation level of OLEDs based on the OLED anode voltages detected by a newly-designed sensing subcircuit. According to sensed voltages, the external algorithm selects appropriate built-in models to compensate OLED degradation with the aim to achieve expected OLED emitted luminance. The models are established based on prior measurements to prescribe the relations between luminance and current and luminance and voltage of each OLED. In this way of compensation, the proposed method is able to incorporate negative effects of OLED degradation aggravation while increasing driving current to compensate the original decay in OLED luminance. Moreover, another algorithm along with the 4T0.5C pixel circuit as presented in prior studies are adopted to compensate process variation in among pixels for improving the emission uniformity of an AMOLED panel. Experiments are conducted by combining the external algorithm with sensing circuit and the pixel circuit to validate the performances of compensating and alleviating OLED degradation.
A new prediction model on the luminance of OLEDs subjected to different reverse biases for alleviating degradation in AMOLED displays
(2015-12-01)
Yu, Ming-Hung
;
Tran, Trong-Hieu
;
Hsu, Yen-Ping
;
Chao, Paul C. -P.
;
Lee, Kuei-Yu
A new prediction model for estimating luminance degradation of an OLED subjected to varied combinations of forward and reverse biases is proposed. To this end, the known increase in the voltage of OLEDs under long-time operation versus degraded emitted luminance is first-time ever considered to identify the degradation exponent as logarithm functions of elapsed time. With the identified degradation versus time, the degraded OLED luminance can be well predicted even subjected to varied combinations of forward and reverse biases. The established model is particularly useful for achieving required lifetime of modern AMOLED displays. Based on the model in terms of equations, the OLED parameters including forward, reverse bias stresses, and initial luminance can be applied to the model to accurately estimate the luminance variation during long-time operation. The estimation error between model predictions and experimental measurements is less than 1.6 %.
A New Prediction Model on the Luminance of OLEDs Subjected to Different Reverse Biases for Alleviating Degradation in AMOLED Displays
(2014-01-01)
Chao, Paul C-P
;
Hsu, Yen-Ping
;
Kao, Yung-Hua
;
Lee, Kuei-Yu
;
電機工程學系
Sensing TFT V-th by an External Algorithm to Compensate Non-uniformity on AMOLED Panel
(2012)
Lee, Kuei-Yu
;
Chao, Paul C. -P.
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The study proposes an external algorithm to compensate non-uniformity on AMOLED panel. With the method of sensing TFT V-th variation, this external algorithm is designed to correct the data line voltage, V-data, in order to maintain the required OLED luminance even though every Vth variation of driving TFTs are different. The algorithm and sensing method are realized on the already proposed 4T0.5C pixel circuit, which is investigated to show the performance of panel non-uniformity compensation in the experiment results. Moreover, the original merits of 4T0.5C pixel circuit like OLED degradation alleviation can be maintained.