Abstract

We propose an optical design process that significantly reduces the time and costs in direct backlight unit (BLU) development. In it, the basic system specifications are derived from the optical characteristics of RGB light-emitting diodes (LEDs) comprising the BLU. The driving currents are estimated to determine the theoretical RGB flux ratio for a desired white point. The number of LEDs needed to produce the target luminance is then calculated from the combined optical efficiencies of the components. Last, an appropriate array configuration is sought based on the illuminance distribution function for meeting the target uniformity. To showcase the design process we built two 42-inch triangular cluster arrays of 40 × 16 LED elements. When a flat reflective sheet was used, the minimum thickness required of the system to satisfy the target uniformity was 30 mm. Introducing a patterned reflective sheet removed hotspots that resulted from reducing the system thickness without the aid of additional optical components. Using an optimized patterned reflective sheet, reduction in system thickness as much as 5 mm was possible.

© 2010 OSA

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  1. D. M. Brown, R. Dean, and J. D. Brown, “LED backlight: design, fabrication, and testing,” Proc. SPIE 3938, 180–187 (2000).
  2. E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
    [CrossRef]
  3. M. Anandan, “Progress of LED backlights for LCDs,” J. Soc. Inf. Disp. 16(2), 287–310 (2008).
    [CrossRef]
  4. G. Wyszecki and W. S. Stiles, Color Science 2nd Edition (Wiley, New York, 1982).
  5. K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
    [CrossRef]
  6. S. Muthu and J. Gaines, “Red, green and blue LED-based white light source: Implementation challenges and control design,” in Proc. IEEE IAS Annu. Meeting 1 515–522 (2003).
  7. P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).
  8. Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).
  9. W. Robert, Boyd, Radiometry and Dectection of Optical Radiation (Wiley, New York, 1983).
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    [CrossRef]
  11. I. Moreno, M. Avendaño-Alejo, and R. I. Tzonchev, “Designing light-emitting diode arrays for uniform near-field irradiance,” Appl. Opt. 45(10), 2265–2272 (2006).
    [CrossRef]
  12. P. C.-P. Chao, L.-D. Liao, and C.-W. Chiu, “Design of a Novel LED Lens Cap and Optimization of LED Placement in a Large Area Direct Backlight for LCD-TVs,” Proc. SPIE 6196, 61960N (2006).
  13. Yankun Zhen, Zhenan Jiaa, and Wenzi Zhang, “The Optimization of Directly-Under-Light Type Backlight Module Structure for Brightness Uniformity,” Key Engineering Materials 364 – 366, 166–171 (2008).
  14. B. Kim, M. Choi, H. Kim, J. Lim, and S. Kang, “Elimination of flux loss by optimizing the groove angle in modified Fresnel lens to increase illuminance uniformity, color uniformity and flux efficiency in LED illumination,” Opt. Express 17(20), 17916–17927 (2009).
    [CrossRef]

2009 (2)

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

B. Kim, M. Choi, H. Kim, J. Lim, and S. Kang, “Elimination of flux loss by optimizing the groove angle in modified Fresnel lens to increase illuminance uniformity, color uniformity and flux efficiency in LED illumination,” Opt. Express 17(20), 17916–17927 (2009).
[CrossRef]

2008 (2)

M. Anandan, “Progress of LED backlights for LCDs,” J. Soc. Inf. Disp. 16(2), 287–310 (2008).
[CrossRef]

Yankun Zhen, Zhenan Jiaa, and Wenzi Zhang, “The Optimization of Directly-Under-Light Type Backlight Module Structure for Brightness Uniformity,” Key Engineering Materials 364 – 366, 166–171 (2008).

2007 (1)

2006 (3)

I. Moreno, M. Avendaño-Alejo, and R. I. Tzonchev, “Designing light-emitting diode arrays for uniform near-field irradiance,” Appl. Opt. 45(10), 2265–2272 (2006).
[CrossRef]

Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).

P. C.-P. Chao, L.-D. Liao, and C.-W. Chiu, “Design of a Novel LED Lens Cap and Optimization of LED Placement in a Large Area Direct Backlight for LCD-TVs,” Proc. SPIE 6196, 61960N (2006).

2005 (2)

P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[CrossRef]

2000 (1)

D. M. Brown, R. Dean, and J. D. Brown, “LED backlight: design, fabrication, and testing,” Proc. SPIE 3938, 180–187 (2000).

Anandan, M.

M. Anandan, “Progress of LED backlights for LCDs,” J. Soc. Inf. Disp. 16(2), 287–310 (2008).
[CrossRef]

Ansems, J.

P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).

Avendaño-Alejo, M.

Berkeley, Brian

Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).

Bierhuizen, S. J.

Brown, D. M.

D. M. Brown, R. Dean, and J. D. Brown, “LED backlight: design, fabrication, and testing,” Proc. SPIE 3938, 180–187 (2000).

Brown, J. D.

D. M. Brown, R. Dean, and J. D. Brown, “LED backlight: design, fabrication, and testing,” Proc. SPIE 3938, 180–187 (2000).

Chao, P. C.-P.

P. C.-P. Chao, L.-D. Liao, and C.-W. Chiu, “Design of a Novel LED Lens Cap and Optimization of LED Placement in a Large Area Direct Backlight for LCD-TVs,” Proc. SPIE 6196, 61960N (2006).

Chiu, C.-W.

P. C.-P. Chao, L.-D. Liao, and C.-W. Chiu, “Design of a Novel LED Lens Cap and Optimization of LED Placement in a Large Area Direct Backlight for LCD-TVs,” Proc. SPIE 6196, 61960N (2006).

Choi, M.

Dean, R.

D. M. Brown, R. Dean, and J. D. Brown, “LED backlight: design, fabrication, and testing,” Proc. SPIE 3938, 180–187 (2000).

Deurenberg, P.

P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).

Han, D. J.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Harbers, G.

Hoelen, C.

P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).

Jiaa, Zhenan

Yankun Zhen, Zhenan Jiaa, and Wenzi Zhang, “The Optimization of Directly-Under-Light Type Backlight Module Structure for Brightness Uniformity,” Key Engineering Materials 364 – 366, 166–171 (2008).

Kang, S.

Kim, B.

Kim, H.

Kim, J. K.

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[CrossRef]

Kim, Sang-Soo

Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).

Krames, M. R.

Lee, Ki-Chan

Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).

Li, W.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Liang, K.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Liao, L.-D.

P. C.-P. Chao, L.-D. Liao, and C.-W. Chiu, “Design of a Novel LED Lens Cap and Optimization of LED Placement in a Large Area Direct Backlight for LCD-TVs,” Proc. SPIE 6196, 61960N (2006).

Lim, J.

Liu, X. L.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Moon, Seung-Hwan

Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).

Moreno, I.

Ren, H. R.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Schubert, E. F.

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[CrossRef]

Tzonchev, R. I.

van Meurs, J.

P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).

Wang, W. J.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Yang, R.

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

Zhang, Wenzi

Yankun Zhen, Zhenan Jiaa, and Wenzi Zhang, “The Optimization of Directly-Under-Light Type Backlight Module Structure for Brightness Uniformity,” Key Engineering Materials 364 – 366, 166–171 (2008).

Zhen, Yankun

Yankun Zhen, Zhenan Jiaa, and Wenzi Zhang, “The Optimization of Directly-Under-Light Type Backlight Module Structure for Brightness Uniformity,” Key Engineering Materials 364 – 366, 166–171 (2008).

Appl. Opt. (1)

Displays (1)

K. Liang, W. Li, H. R. Ren, X. L. Liu, W. J. Wang, R. Yang, and D. J. Han, “Color measurement for RGB white LEDs in solid-state lighting using a BDJ photodetector,” Displays 30(3), 107–113 (2009).
[CrossRef]

J. Display Technol. (1)

J. Soc. Inf. Disp. (1)

M. Anandan, “Progress of LED backlights for LCDs,” J. Soc. Inf. Disp. 16(2), 287–310 (2008).
[CrossRef]

Key Engineering Materials (1)

Yankun Zhen, Zhenan Jiaa, and Wenzi Zhang, “The Optimization of Directly-Under-Light Type Backlight Module Structure for Brightness Uniformity,” Key Engineering Materials 364 – 366, 166–171 (2008).

Opt. Express (1)

Proc. SPIE (3)

P. C.-P. Chao, L.-D. Liao, and C.-W. Chiu, “Design of a Novel LED Lens Cap and Optimization of LED Placement in a Large Area Direct Backlight for LCD-TVs,” Proc. SPIE 6196, 61960N (2006).

D. M. Brown, R. Dean, and J. D. Brown, “LED backlight: design, fabrication, and testing,” Proc. SPIE 3938, 180–187 (2000).

P. Deurenberg, C. Hoelen, J. van Meurs, and J. Ansems, “Achieving color point stability in RGB multi-chip LED modules using various color control loops,” Proc. SPIE 5941, 59410C (2005).

Science (1)

E. F. Schubert and J. K. Kim, “Solid-state light sources getting smart,” Science 308(5726), 1274–1278 (2005).
[CrossRef]

Sens, Actuators A (1)

Ki-Chan Lee, Seung-Hwan Moon, Brian Berkeley, and Sang-Soo Kim,“Optical feedback system with integrated color sensor on LCD,” Sens, Actuators A 130–131, 214–219 (2006).

Other (3)

W. Robert, Boyd, Radiometry and Dectection of Optical Radiation (Wiley, New York, 1983).

S. Muthu and J. Gaines, “Red, green and blue LED-based white light source: Implementation challenges and control design,” in Proc. IEEE IAS Annu. Meeting 1 515–522 (2003).

G. Wyszecki and W. S. Stiles, Color Science 2nd Edition (Wiley, New York, 1982).

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