Simple pixel circuits for high resolution and high image quality organic light emitting diode-on-silicon microdisplays with wide data voltage range

Abstract

-Two simple pixel circuits are proposed for high resolution and high image quality organic light-emitting diode-on-silicon microdisplays. The proposed pixel circuits achieve high resolution due to simple pixel structure comprising three n-type MOSFETs and one storage capacitor, which are integrated into a unit subpixel area of 3 × 9 μm 2 using a 90 nm CMOS process. The proposed pixel circuits improve image quality by compensating for the threshold voltage variation of the driving transistors and extending the data voltage range. To verify the performance of the proposed pixel circuits, the emission currents of 24 pixel circuits are measured. The measured emission current deviation error of the proposed pixel circuits A and B ranges from À2.59% to +2.78%, and from À1.86% to +1.84%, respectively, which are improved from the emission current deviation error of the conventional current-source type pixel circuit when the threshold voltage variation is not compensated for, which ranges from À14.87% to +14.67%. In addition, the data voltage ranges of the proposed pixel circuits A and B are 1.193 V and 1.792 V, respectively, which are 2.38 and 3.57 times wider than the data voltage range of the conventional current-source type pixel circuit of 0.501 V.

P‐27: A Novel Pixel Circuit with Threshold Voltage Variation Compensation in Three‐Dimensional AMOLED on Silicon Microdisplay

“…With the advantages of high contrast ratio, fast optical response time, wide view angle, low power consumption and portable feature, organic light emitting diode on silicon (OLEDoS) is an advantageous choice to achieve high image quality microdisplays [1][2][3][4][5][6]. 0.5-inch Quad-VGA and 1.25-inch wide-Quad-XGA OLEDoS microdisplays were developed in recent years [6].…”

P‐47: An OLEDoS Pixel Circuit with Extended Data Voltage Range for High Resolution Micro‐Displays

“…To realize the same luminance, the OLED emission current decreases as the pixel circuit area becomes smaller. Therefore, due to the restrictions of small pixel circuit area and requirements of low power consumption, the OLED emission current generally ranges from tens of pico-amperes (pA) to a few nano-amperes (nA) [2]- [5]. In order to precisely control the emission current of circuits with high resolution, it is necessary to extend the data voltage range [3], [5].…”

“…Therefore, due to the restrictions of small pixel circuit area and requirements of low power consumption, the OLED emission current generally ranges from tens of pico-amperes (pA) to a few nano-amperes (nA) [2]- [5]. In order to precisely control the emission current of circuits with high resolution, it is necessary to extend the data voltage range [3], [5]. Furthermore, the threshold voltage (Vth) variation [2]- [5] of driving transistors, which is caused by the process, should also be compensated to realize high image quality OLEDoS micro-displays.…”

“…In order to precisely control the emission current of circuits with high resolution, it is necessary to extend the data voltage range [3], [5]. Furthermore, the threshold voltage (Vth) variation [2]- [5] of driving transistors, which is caused by the process, should also be compensated to realize high image quality OLEDoS micro-displays.…”

“…Thus, the current programming method is not suitable for OLEDoS with high resolution and low power consumption. It seems that the voltage programming method is better [2], [5]. Several pixel circuits with Vth variation compensation function were proposed, yet with narrow data voltage range [6], [8].…”