The Method to Compensate IR-Drop of AMOLED Display Jongwoong Park*, Mitsuru Fujii*, Jiye Moon*, Insu Wang* Donghwan Lee*, Wonju Shin*, Wonjun Choe* * OLED Development Center, Samsung Display Co., Ltd. Giheung-Gu, Yongin-City, Gyeonggi-Do, Korea Abstract In this paper, we propose the method to compensate IR-Drop of AMOLED display. To drive AMOLED display, each pixel circuit should drive each OLED. In this case, by the loading effect and IR-drop, the LRU (Long Range Uniformity) and color accuracy characteristic could be worse. To avoid this problem, IR-Drop map was simulated for each loading condition. And compensation algorithm was developed and implemented in driver IC. By this technology, gamma accuracy range ( △ gamma) by loading condition was improved from 1.1 to 0.15. And skin color accuracy (△xy) by loading condition was improved from 0.0294 to 0.0020. Author Keywords AMOLED, Compensation, IR-drop, Loading effect, Gamma, Color accuracy 1. Introduction AMOLED Display has grown rapidly, and its application is expanded to much larger size application from its smartphone application. Also, even if it is smartphone application, the display size is bigger and bigger. So, IR-drop has become much important factor to AMOLED display. Figure 1 explains about OLED Pixel Circuit and ELVDD power layout. Because ELVDD power layout is a mesh structure, for each pixel point, IR-drop happens by the pixel current. If the loading condition is changed in this OLED display, the brightness and color accuracy characteristic is changed. Figure 1. OLED Pixel Circuit and ELVDD Power Layout In Figure 2, IR-Drop was simulated base on this pixel circuit, explained in Figure 1. In this Figure 2, many images and loading conditions were explained and IR-Drop was simulated. In the simulation result image, the red color means that IR-Drop is big, and the blue color means that IR-Drop is small. The green color is the medium level of IR-Drop. In case of white images, much bigger IR-Drop happens. However, in case of dark images, IR- Drop is very small. In this paper, based on this IR-Drop simulation, IR-drop compensation method is introduced and the result of this compensation is analyzed. Figure 2. IR-Drop Simulation Results 2. Methods To compensate IR-drop in each case of loading condition, the IR- drop characteristic and gamma should be analyzed. Figure 3. Gamma Difference by Loading Condition 8-1 / J. Park SID 2019 DIGEST • 81 ISSN 0097-996X/19/4801-0081-$1.00 © 2019 SID