Journal of the Institute of Electronics Engineers of Korea SD (대한전자공학회논문지SD)

The Institute of Electronics and Information Engineers (대한전자공학회)
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Design of LCD Backlight Driver IC to improve the Brightness Uniformity

LCD Backlight의 휘도 균일성을 개선한 인버터 드라이버 IC 설계

  • Oh Myeong-Woo (R&D center, Silicon Works Co., Ltd.) ;
  • Yang Sung-hyun (SIC DNI Group, LG Electronics) ;
  • Cho Kyoung-Rok (Dept. of Computer Communication Engineering and Research Institute for Computer and Information Communication, Chungbuk National University)
  • Published : 2005.04.01
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Abstract

This work Proposes and describes an LCD backlight driver IC using a voltage feedback circuit which improves the brightness uniformity. The proposed circuit controls the brightness of a backlight by amplifying of sampling voltage at a lamp. To keep the uniformity of brightness, the circuit has a reference lamp. The output voltage of the reference lamp is supplied commonly to each lamp that reduces a resistance deviation of the lamps. As a result, the proposed circuit shows brightness uniformity improvement of about $40\%$ compared to the conventional ones.

본 논문에서는 LCD 판넬 밝기의 균일성을 향상시키기 위하여 램프간의 저항 차이를 검출하는 회로를 사용한다. 기준 loop와 비교 loop의 feedback 전압을 나누어 검출된 저항의 차이는 PWM duty를 결정하는 제어 모드와 연결하여 램프 저항에 맞는 전압을 램프에 인가한다. 기준 loop의 feedback 전압은 모든 loop의 기준 전압이 되며, 하나의 IC에 램프의 수만큼 외부 기판을 연결하여 사용할 수 있다. 모든 비교 loop의 램프들은 기준 램프와 같은 밝기를 유지하기 위해 에러를 보상하며, 결과적으로 제안된 회로는 기존의 회로에 비해 약 $40\%$ 밝기 균일성을 재선한다.

Keywords

References

  1. T.-H. Yu, L.-M. Wu, and T.-F. Wu, 'Comparisons among self-excited parallel resonant, series resonant and current-fed push-pull electronics ballasts,' in Proc. 9th Apec, vol .1, pp. 421-426, 13-17 Feb. 1994 https://doi.org/10.1109/APEC.1994.316368
  2. R. L. Steigerwald, 'A comparison of half-bridge resonant converter topologies,' IEEE Trans. Power Electronics, vol. 3, no. 2, pp. 174-182, Apr. 1988 https://doi.org/10.1109/63.4347
  3. J. Adams, T. J. Ribarich, and J. J. Ribarich, 'A new control IC for dimmable high-frequency electronic ballasts,' in Proc. Apec, vol. 2, pp. 713-719, Mar. 1999 https://doi.org/10.1109/APEC.1999.750439
  4. J. A. Donahue, P. E., and M. M. Jovanovic, 'The LCC inverter as a cold cathode fluorescent lamp driver,' in Proc. 9th Apec, vol .1, pp. 427-433, 13-17 Feb. 1994
  5. S. W. Lee, D. Y. Ko, D. Y. Huh, and Y. I. Yoo, 'Simplified control technique for LCD backlight inverter system using the mixed dimming method,' in Proc. 16th Apec, vol. 1, pp. 447-453, 4-8 Mar. 2001
  6. D. Ghosh, D. Patranabis, 'A simple analog divider having independent control of sensitivity and design conditions,' IEEE Trans. Instrumentation and Measurement, vol. 39, no. 3, pp. 552-556, June 1990