Abstract

We report light collimation from a point source without the space normally needed for fan-out. Rays emerge uniformly from all parts of the surface of a blunt wedge light-guide when a point source of light is placed at the thin end and the source’s position determines ray direction in the manner of a lens. A lenticular array between this light-guide and a liquid crystal panel guides light from color light-emitting diodes to designated sub-pixels thereby removing the need for color filters and halving power consumption but we foresee much greater power economies and wider application.

© 2009 OSA

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References

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  1. A. Travis, F. Payne, J. Zhong, and J. Moore, “Flat panel display using projection within a wedge-shaped waveguide,” presented at the 20th International Display Research Conference of the Society for Information Display, 292–295 (2002).
  2. S. Kobayashi, S. Mikoshiba, and S. Lim, LCD Backlights (John Wiley & Sons, 2009).
  3. M. Anandan, “Progress of LED backlights for LCDs,” J. Soc. Inf. Disp. 16(2), 287–310 (2008).
    [CrossRef]
  4. C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
    [CrossRef]
  5. M. Albrecht, A. Karrenbauer, and C. Xu, “A Clipper-Free Algorithm for Efficient HW-Implementation of Local Dimming LED-Backlight,” presented at the 28th International Display Research Conference of the Society for Information Display, 286–289 (2008), http://www.sidmembers.org/proc/IDRC2008/redist/docs/15_3.pdf
  6. R. Hoskinson and B. Stoeber, “High-dynamic range image projection using an auxiliary MEMS mirror array,” Opt. Express 16(10), 7361–7368 (2008), http://www.opticsinfobase.org/oe/viewmedia.cfm?URI=oe-16-10-7361&seq=0 .
    [CrossRef] [PubMed]
  7. K. Sekiya, “Design Scheme of LED Scanning Backlights for Field-Sequential-Color LCDs,” SID Symposium Digest of Technical Papers, 47(2), 1026–1029 (2009).
  8. J. Kimmel, T. Levola, A. Giraldo, N. Bergeron, S. Siitonen, and T. Rytkönen, “Diffractive Backlight Light Guide Plates in Mobile Electrowetting Display Applications,” SID Symposium Digest of Technical Papers, 47(2), 826–829 (2009).

2008

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

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

R. Hoskinson and B. Stoeber, “High-dynamic range image projection using an auxiliary MEMS mirror array,” Opt. Express 16(10), 7361–7368 (2008), http://www.opticsinfobase.org/oe/viewmedia.cfm?URI=oe-16-10-7361&seq=0 .
[CrossRef] [PubMed]

Anandan, M.

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

Chien, W.-T.

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

Chung, S.-H.

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

Hoskinson, R.

Hsieh, C.-T.

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

Moreno, I.

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

Stoeber, B.

Sun, C.-C.

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

Yang, T.-H.

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

J. Soc. Inf. Disp.

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

C.-C. Sun, I. Moreno, S.-H. Chung, W.-T. Chien, C.-T. Hsieh, and T.-H. Yang, “Brightness management in a direct LED backlight for LCD TVs,” J. Soc. Inf. Disp. 16(4), 519–526 (2008).
[CrossRef]

Opt. Express

Other

A. Travis, F. Payne, J. Zhong, and J. Moore, “Flat panel display using projection within a wedge-shaped waveguide,” presented at the 20th International Display Research Conference of the Society for Information Display, 292–295 (2002).

S. Kobayashi, S. Mikoshiba, and S. Lim, LCD Backlights (John Wiley & Sons, 2009).

M. Albrecht, A. Karrenbauer, and C. Xu, “A Clipper-Free Algorithm for Efficient HW-Implementation of Local Dimming LED-Backlight,” presented at the 28th International Display Research Conference of the Society for Information Display, 286–289 (2008), http://www.sidmembers.org/proc/IDRC2008/redist/docs/15_3.pdf

K. Sekiya, “Design Scheme of LED Scanning Backlights for Field-Sequential-Color LCDs,” SID Symposium Digest of Technical Papers, 47(2), 1026–1029 (2009).

J. Kimmel, T. Levola, A. Giraldo, N. Bergeron, S. Siitonen, and T. Rytkönen, “Diffractive Backlight Light Guide Plates in Mobile Electrowetting Display Applications,” SID Symposium Digest of Technical Papers, 47(2), 826–829 (2009).

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Figures (5)

Fig. 1
Fig. 1

Plan view: rays fan out to the thick end where they are reflected in parallel.

Fig. 2
Fig. 2

Cross-section: ray angle is increased by reflection off facets at the thick end so rays emerge as they return towards the thin end.

Fig. 3
Fig. 3

Rays travel as if through a stack of wedges. The curvature of the thick end collimates the rays and the facets slew the direction of collimation so that rays illuminate the whole of the surface as they reach the critical angle.

Fig. 4
Fig. 4

The wedge collimates rays from each source in a direction determined by its position (a). Hence a cylindrical image of the sources is formed by each lenticule on the adjacent column of pixels in the liquid crystal display (b).

Fig. 5
Fig. 5

Rays from LED’s either side of the center will leave a shadow.

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