Abstract

The local-dimming backlight has recently been presented for use in LCD TVs. However, the image resolution is low, particularly at weak edges. In this work, a local-dimming backlight is developed to improve the image contrast and reduce power dissipation. The algorithm enhances low-level edge information to improve the perceived image resolution. Based on the algorithm, a 42-in backlight module with white light-emitting diode (LED) devices was driven by a local dimming control core. The block-wise register approach substantially reduced the number of required line-buffers and shortened the latency time. The measurements made in the laboratory indicate that the backlight system reduces power dissipation by an average of 48% and exhibits no visible distortion compared relative to the fixed backlighting system. The system was successfully demonstrated in a 42-in LCD TV, and the contrast ratio was greatly improved by a factor of 100.

© 2013 IEEE

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  1. C. Chang, S. Peng, LED array employing a lattice relationship U.S. Patent 6??201??353 (2001).
  2. C.-C. Chen, C.-Y. Wu, T.-F. Wu, "LED back-light driving system for LCD panels," Proc. Appl. Power Electron. Conf. (2006) pp. 381-385.
  3. F. C. Lin, C. Y. Liao, L. Y. Liao, Y. P. Huang, H. P. D. Shieh, "Inverse of mapping function method for image quality enhancement of high dynamic range LCD TVs," SID Symp. Dig. Tech. Papers (2007) pp. 1343-1346.
  4. T. W. Lee, J.-H. Lee, C. G. Kim, S. H. Kang, "An optical feedback system for local dimming backlight with RGB LEDs," IEEE Trans. Consum. Electron. 55, 2178-2183 (2009).
  5. L. Y. Liao, C. W. Chen, Y. P. Huang, "Local blinking HDR LCD systems for fast MPRT with high brightness LCDs," J. Display Technol. 6, 178-183 (2010).
  6. C.-C. Lai, C.-C. Tsai, "Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications," IEEE Trans. Consumer Electron. 54, 669-674 (2008).
  7. H. Cho, O. K. Kwon, "A local dimming algorithm for low power LCD TVs using edge-type LED backlight," IEEE Trans. Consumer Electron. 56, 2054-2060 (2010).
  8. Y. H. Liu, Z. Z. Yang, S. C. Wang, "A novel sequential-color RGB-LED backlight driving system with local dimming control and dynamic bus voltage regulation," IEEE Trans. Consumer Electron. 56, 2445-2452 (2010).
  9. W. S. Oh, D. Cho, K. M. Cho, G. W. Moon, B. Yang, T. Jang, "A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs," J. Display Technol. 5, 20-26 (2009).
  10. F.-C. Lin, Y. P. Huang, L. Y. Liao, C.-Y. Liao, H.-P. D. Shieh, T. M. Wang, S.-C. Yeh, "Dynamic backlight gamma on high dynamic range LCD TVs," J. Display Technol. 4, 139-146 (2008).
  11. H. Cho, O. K. Kwon, "A backlight dimming algorithm for low power and high image quality LCD applications," IEEE Trans. Consumer Electron. 55, 839-844 (2009).
  12. H. Chen, J. Sung, T. Ha, Y. Park, C. Hong, "Backlight local dimming algorithm for high contrast LCD-TV," Proc. ASID (2006) pp. 168-171.
  13. R. D. Sasso, D. B. Logan, W. B. Phelan, Means of achieving a Lambertian distribution light source via a light emitting diode array U.S. Patent 20??050??180??134 (2005).
  14. Everlight Electronics Co. Ltd.“0.2 W LED Technical Data Sheet, 5050” http://www.everlight.com.
  15. A. K. Jain, Fundamentals of Digital Image Processing (Prentice-Hall, 1989).
  16. S. C. Hsia, J. M. Kuo, "Cost effective design and implementation of scanning-based LED backlight for LCD module," IEEE Trans. Consumer Electron. 56, 2037-2042 (2010).
  17. S. Palnitkar, Verilog HDL (Prentice-Hall, 1996).
  18. Xilinx Corp. http://www. Xilinx.com.

2010 (4)

H. Cho, O. K. Kwon, "A local dimming algorithm for low power LCD TVs using edge-type LED backlight," IEEE Trans. Consumer Electron. 56, 2054-2060 (2010).

Y. H. Liu, Z. Z. Yang, S. C. Wang, "A novel sequential-color RGB-LED backlight driving system with local dimming control and dynamic bus voltage regulation," IEEE Trans. Consumer Electron. 56, 2445-2452 (2010).

S. C. Hsia, J. M. Kuo, "Cost effective design and implementation of scanning-based LED backlight for LCD module," IEEE Trans. Consumer Electron. 56, 2037-2042 (2010).

L. Y. Liao, C. W. Chen, Y. P. Huang, "Local blinking HDR LCD systems for fast MPRT with high brightness LCDs," J. Display Technol. 6, 178-183 (2010).

2009 (3)

W. S. Oh, D. Cho, K. M. Cho, G. W. Moon, B. Yang, T. Jang, "A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs," J. Display Technol. 5, 20-26 (2009).

T. W. Lee, J.-H. Lee, C. G. Kim, S. H. Kang, "An optical feedback system for local dimming backlight with RGB LEDs," IEEE Trans. Consum. Electron. 55, 2178-2183 (2009).

H. Cho, O. K. Kwon, "A backlight dimming algorithm for low power and high image quality LCD applications," IEEE Trans. Consumer Electron. 55, 839-844 (2009).

2008 (2)

C.-C. Lai, C.-C. Tsai, "Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications," IEEE Trans. Consumer Electron. 54, 669-674 (2008).

F.-C. Lin, Y. P. Huang, L. Y. Liao, C.-Y. Liao, H.-P. D. Shieh, T. M. Wang, S.-C. Yeh, "Dynamic backlight gamma on high dynamic range LCD TVs," J. Display Technol. 4, 139-146 (2008).

IEEE Trans. Consum. Electron. (1)

T. W. Lee, J.-H. Lee, C. G. Kim, S. H. Kang, "An optical feedback system for local dimming backlight with RGB LEDs," IEEE Trans. Consum. Electron. 55, 2178-2183 (2009).

IEEE Trans. Consumer Electron. (5)

C.-C. Lai, C.-C. Tsai, "Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications," IEEE Trans. Consumer Electron. 54, 669-674 (2008).

H. Cho, O. K. Kwon, "A local dimming algorithm for low power LCD TVs using edge-type LED backlight," IEEE Trans. Consumer Electron. 56, 2054-2060 (2010).

Y. H. Liu, Z. Z. Yang, S. C. Wang, "A novel sequential-color RGB-LED backlight driving system with local dimming control and dynamic bus voltage regulation," IEEE Trans. Consumer Electron. 56, 2445-2452 (2010).

H. Cho, O. K. Kwon, "A backlight dimming algorithm for low power and high image quality LCD applications," IEEE Trans. Consumer Electron. 55, 839-844 (2009).

S. C. Hsia, J. M. Kuo, "Cost effective design and implementation of scanning-based LED backlight for LCD module," IEEE Trans. Consumer Electron. 56, 2037-2042 (2010).

J. Display Technol. (3)

Other (9)

S. Palnitkar, Verilog HDL (Prentice-Hall, 1996).

Xilinx Corp. http://www. Xilinx.com.

C. Chang, S. Peng, LED array employing a lattice relationship U.S. Patent 6??201??353 (2001).

C.-C. Chen, C.-Y. Wu, T.-F. Wu, "LED back-light driving system for LCD panels," Proc. Appl. Power Electron. Conf. (2006) pp. 381-385.

F. C. Lin, C. Y. Liao, L. Y. Liao, Y. P. Huang, H. P. D. Shieh, "Inverse of mapping function method for image quality enhancement of high dynamic range LCD TVs," SID Symp. Dig. Tech. Papers (2007) pp. 1343-1346.

H. Chen, J. Sung, T. Ha, Y. Park, C. Hong, "Backlight local dimming algorithm for high contrast LCD-TV," Proc. ASID (2006) pp. 168-171.

R. D. Sasso, D. B. Logan, W. B. Phelan, Means of achieving a Lambertian distribution light source via a light emitting diode array U.S. Patent 20??050??180??134 (2005).

Everlight Electronics Co. Ltd.“0.2 W LED Technical Data Sheet, 5050” http://www.everlight.com.

A. K. Jain, Fundamentals of Digital Image Processing (Prentice-Hall, 1989).

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