Journal of the Semiconductor & Display Technology (반도체디스플레이기술학회지)

The Korean Society Of Semiconductor & Display Technology (한국반도체디스플레이기술학회)
권호 표지

OLED Lighting System Integrated with Optical Monitoring Circuit

광 검출기가 장착된 OLED 조명 시스템

  • 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)
  • 신동균 (한국기술교육대학교 전기.전자.통신공학부) ;
  • 박종운 (한국기술교육대학교 전기.전자.통신공학부) ;
  • 서화일 (한국기술교육대학교 전기.전자.통신공학부)
  • Received : 2013.04.29
  • Accepted : 2013.05.31
  • Published : 2013.06.30
Download PDF
⟨ Previous Next ⟩

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

References

  1. C. W. Tang and S. A. Vanslyke, "Organic electroluminescent diodes," Appl. Phys. Lett., Vol. 51, pp. 913-915, 1987. https://doi.org/10.1063/1.98799
  2. K. Leo, "Organic LEDs Combined With Inorganic LEDs," Science, Vol. 310, pp.1762-1763, 2005. https://doi.org/10.1126/science.310.5755.1762
  3. 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. https://doi.org/10.1038/nature04645
  4. 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. https://doi.org/10.1016/j.tsf.2009.09.188
  5. 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. https://doi.org/10.1063/1.126275
  6. J. Kido, "High Performance OLEDs for Displays and General Lighting," SID, Vol. 08, pp. 931-932, 2008.
  7. 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
  8. 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 https://doi.org/10.1109/JDT.2008.921771
  9. 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 https://doi.org/10.1889/1.2012595
  10. 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 https://doi.org/10.1063/1.1858875
  11. Prathyusha Narra and Donald S. Zinger, "An Effective LED Dimming Approach," IEEE Conference Publications, Vol. 3, pp. 1671-1676, 2004