Brightness management in a direct LED backlight for LCD TVs

— A method of calculating the luminance and luminance uniformity of a bottom LED backlight is proposed and demonstrated. Both the power consumption and brightness uniformity as a function of screen brightness, screen size, backlight thickness, transmittance of the LCD panel, reflective cavity efficiency, gain, cone angle of the enhancement films, LED array configuration, and the average luminous flux, radiation pattern, and input power of individual LEDs. Moreover, a 42-in. LCD TV using this backlight design approach was fabricated. The bottom backlight incorporates an array of RGGB 4-in-1 multi-chip LEDs within a highly reflective box behind a diffuser and a dual brightness-enhancement film. The brightness uniformity can be predicted within an accuracy of 94% and the luminance level within an accuracy of 96%.

[1]  Oliver Dross,et al.  High-efficiency LED backlight optics designed with the flow-line method , 2005, SPIE Optics + Photonics.

[2]  Jee-Gong Chang,et al.  A generalized model for luminance prediction in a bottom-lit backlight with cold cathode fluorescent lamps , 2006 .

[3]  Yun Woo Lee,et al.  Fast ray-tracing methods for LCD backlight simulation using the characteristics of the pattern , 2005 .

[4]  Ivan Moreno,et al.  Modeling the radiation pattern of LEDs. , 2008, Optics express.

[5]  Yourii Martynov,et al.  43.4: High Brightness Direct LED Backlight for LCD-TV , 2003 .

[6]  Jee-Gong Chang,et al.  Photometric quantity analysis of backlight for a dual-panel display , 2006 .

[7]  Wei-Chung Cheng,et al.  Viewing direction-aware backlight scaling , 2007, GLSVLSI '07.

[8]  Ching-Cherng Sun,et al.  Precise optical modeling for LED lighting verified by cross correlation in the midfield region. , 2006, Optics letters.

[9]  Chai Wah Wu,et al.  25.4: Color and Luminance Management for High-Resolution Liquid-Crystal Displays , 2003 .

[10]  M. Krames,et al.  Performance of High Power Light Emitting Diodes in Display Illumination Applications , 2007, Journal of Display Technology.

[11]  Ian Ashdown.  Solid-State Lighting:A Systems Engineering Approach , 2007 .

[12]  P. Hall.  Radiometry and the Detection of Optical Radiation , 1984 .

[13]  Ching-Cherng Sun,et al.  Simple function for intensity distribution from LEDs , 2007, SPIE Optical Engineering + Applications.

[14]  Shin-Tson Wu,et al.  Color shift reduction of a multi-domain IPS-LCD using RGB-LED backlight. , 2006, Optics express.

[15]  Chai Wah Wu,et al.  Color and Luminance Management for High-Resolution Liquid-Crystal Displays , 2003 .

[16]  Wiep Folkerts.  41.3: Invited Paper: LED Backlighting Concepts with High Flux LEDs , 2004 .

[17]  Ivan Moreno,et al.  Color distribution from multicolor LED arrays. , 2007, Optics express.