Browse > Article

OLED Lighting System Integrated with Optical Monitoring Circuit  

Shin, Dong-Kyun (School of Electrical & Electronic & Communication Engineering, Korea University of Technology and Education)
Park, Jong-Woon (School of Electrical & Electronic & Communication Engineering, Korea University of Technology and Education)
Seo, Hwa-Il (School of Electrical & Electronic & Communication Engineering, Korea University of Technology and Education)
Publication Information
Journal of the Semiconductor & Display Technology / v.12, no.2, 2013 , pp. 13-17 More about this Journal
Abstract
In lighting system where several large-area organic light-emitting diode (OLED) lighting panels are involved, panel aging may appear differently from each other, resulting in a falling-off in lighting quality. To achieve uniform light output across large-area OLED lighting panels, we have employed an optical feedback circuit. Light output from each OLED panel is monitored by the optical feedback circuit that consists of a photodiode, I-V converter, 10-bit analogdigital converter (ADC), and comparator. A photodiode generates current by detecting OLED light from one side of the glass substrate (i.e., edge emission). Namely, the target luminance from the emission area (bottom emission) of OLED panels is monitored by current generated from the photodiode mounted on a glass edge. To this end, we need to establish a mapping table between the ADC value and the luminance of bottom emission. The reference ADC value corresponds to the target luminance of OLED panels. If the ADC value is lower or higher than the reference one (i.e., when the luminance of OLED panel is lower or higher than its target luminance), a micro controller unit (MCU) adjusts the pulse width modulation (PWM) used for the control of the power supplied to OLED panels in such a way that the ADC value obtained from optical feedback is the same as the reference one. As such, the target luminance of each individual OLED panel is unchanged. With the optical feedback circuit included in the lighting system, we have observed only 2% difference in relative intensity of neighboring OLED panels.
Keywords
Organic light-emitting diodes (OLEDs); Photodetector; Optical monitoring; Uniform light output;
Citations & Related Records
연도 인용수 순위
  • Reference
1 J. W. Park, D. C. Shin, and S. H. Park, Semicon, "Large-area OLED lightings and their applications," Sci. and Technol., Vol. 26, 034002, 2011
2 J. Yu, J. R. Tischler, C. G. Sodini, and V. Bulović, "Using Integrated Optical Feedback to Counter Pixel Aging and Stabilize Light Output of Organic LED Display Technology," IEEE J. Disp. Technol., Vol. 4, pp. 308-313, 2008   DOI   ScienceOn
3 D. A. Fish, M. J. Childs, S. C. Deane, J. M. Shannon, W. A. Steer, N. D. Young, A. Giraldo, H. Lifka, and W. Oepts, "Improved optical feedback for OLED differential ageing correction," J. Soc. Inf. Display, Vol. 13, pp. 131-138, 2005   DOI
4 Toshitaka Nakamura, Naoto Tsutsumi, Noriyuki Juni, and Hironaka Fujii, "Thin-film waveguiding mode light extraction in organic electroluminescent device using high refractive index substrate," J. Appl. Phys. Vol. 97, 054505, 2005   DOI   ScienceOn
5 Prathyusha Narra and Donald S. Zinger, "An Effective LED Dimming Approach," IEEE Conference Publications, Vol. 3, pp. 1671-1676, 2004
6 C. W. Tang and S. A. Vanslyke, "Organic electroluminescent diodes," Appl. Phys. Lett., Vol. 51, pp. 913-915, 1987.   DOI
7 K. Leo, "Organic LEDs Combined With Inorganic LEDs," Science, Vol. 310, pp.1762-1763, 2005.   DOI   ScienceOn
8 Y. Sun, N. Giebink, H. Kanno, B. Wa, M. E. Thompson, and S. R. Forrest, "Management of singlet and triplet excitons for efficient white organic lightemitting devices," Nature (London), Vol. 440 pp. 908-912, 2006.   DOI   ScienceOn
9 M. Eritt, C. May, K. Leo, M. Toerker, and C. Radehaus, "OLED manufacturing for large area lighting applications," Thin Solid Films, Vol. 518, pp. 3042-3045, 2010.   DOI   ScienceOn
10 G. Parthasarathy, C. Adachi, P. E. Burrows, and S. R. Forrest, "High-efficiency transparent organic lightemitting devices," Appl. Phys. Lett., Vol. 76, pp. 2128-2130, 2000.   DOI   ScienceOn
11 J. Kido, "High Performance OLEDs for Displays and General Lighting," SID, Vol. 08, pp. 931-932, 2008.