Advanced Concepts and Applications

Mobile display backlight light guide plates based on slanted grating arrays

[+] Author Affiliations
Jyrki Kimmel

Nokia Research Center, Tampere Laboratory, P. O. Box 1000, 33721 Tampere, Finland

Tapani Levola

Nokia Research Center, Tampere Laboratory, P. O. Box 1000, 33721 Tampere, Finland

J. Photon. Energy. 2(1), 024501 (Mar 12, 2012). doi:10.1117/1.JPE.2.024501
History: Received June 9, 2011; Revised October 27, 2011; Accepted December 1, 2011
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Abstract.  Modern mobile communication devices have user interfaces that are dominated by high-quality displays. Increased multimedia use imposes high demands on the design of display modules, as the content available for mobile use becomes visually richer. Especially the power dissipation of the display can limit the amount of time available for multimedia consumption and interaction. In the mobile liquid-crystal display (LCD), the energy efficiency is determined by the backlight design. State-of-the-art backlights direct white light through a display subpixel array, with high uniformity and up to 90% efficiency in white light output. Therefore, it is difficult to obtain system-level energy savings by improving the backlight design alone. Diffractive backlights have recently been proposed to reduce the power dissipation of the display module, and slanted grating arrays are among the enabling optical features that allow for reduction in power dissipation beyond what is available in the state of the art. By the use of diffractive grating arrays, the required primary color (red, green, or blue) is directed through the LCD subpixel array with geometrical registration, instead of flooding the whole LCD with white light and filtering the primary colors through the subpixel color filter array. We present a study on grating structures based on slanted grating arrays fabricated in high refractive index materials. The grating design principles and grating outcoupling results are provided, and an outline of a new embedded system design is given. Emphasis is on grating array design aspects for future energy-efficient display system design. The results show that savings in power consumption can be expected with advanced display system design based on embedded slanted grating array backlight light guide plates.

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© 2012 Society of Photo-Optical Instrumentation Engineers

Citation

Jyrki Kimmel and Tapani Levola
"Mobile display backlight light guide plates based on slanted grating arrays", J. Photon. Energy. 2(1), 024501 (Mar 12, 2012). ; http://dx.doi.org/10.1117/1.JPE.2.024501


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