Diffusive-sheetless Backlight for Mobile Phone

Liquid-crystal-display backlight units have developed in their conventional configuration into very efficient and uniform components that allow the display to present a high-quality image to the user. Developing the backlight unit itself further faces a challenge of diminishing returns to the investment in innovation. A system-level redesign is required for the entire display module, and diffractive alternatives to the backlight design can allow a more-energy-efficient design for the display. This review concentrates on small-to-medium displays because diffractive backlight studies have also centered in this class of displays. The state of the art of backlight design is summarized and the motivation for energy-efficient system design is outlined. The theoretical basis of diffractive backlights is given, and key research studies in the area of diffractive backlights are reviewed. Finally, a discussion on the performance and future outlook of diffractive backlights completes the paper.

Section: State Of the Art In Mobile-display Backlightsmentioning

confidence: 99%

Review Paper: Diffractive backlight technologies for mobile applications

Kimmel

2012

“…Launching the light into the light guide requires careful engineering of the incoupling region to provide for minimal loss of light, 11 and already systems with adequate luminance for lighting a mobile display from only one LED have been proposed. 12 The light guide itself is a molded piece of transparent plastic that guides the light emitted by the light sources inside the light guide itself by total internal reflection (TIR). Outcoupling is generally distributed throughout one of the surfaces of the light guide in order to provide an efficient and uniform way for the light to enter the display component, in most cases the LCD.…”

Section: State Of the Art Of Backlight Light Guidesmentioning

confidence: 99%

Diffractive backlight grating array for mobile displays

Kimmel¹,

Levola²,

Laakkonen³

2008

Abstract— The display backlight unit (BLU) is the most power‐consuming subunit in mobile liquid‐crystal displays. The state‐of‐the‐art BLUs utilize scattering, refractive, and reflective microstructures to generate a uniform distribution of white light through the display. More effective means of transmitting light through the display color filters could be obtained by using diffraction, but previously proposed diffractive backlights do not fully utilize all the possibilities to design gratings effectively for optimal color separation and outcoupling. This paper presents a new pixelated diffractive backlight grating array as an approach for overcoming these obstacles in BLU design. A model array was fabricated to couple out red, green, and blue primary colors from the respective subpixel locations. The results show that it is possible to manufacture such an array and that the light couples out as intended, giving a starting point to design mobile‐display modules with low light‐transmission losses.

“…To resolve this issue, several research groups reported technologies allowing for thinner lightguides, 1 and some other groups reported technologies that can reduce the number of required optical sheets. [2][3][4][5] In this paper, we describe a backlight system without separate optical sheets using a newly developed multi-layered lightguide (MLL) to satisfy both the high light output and the thin profile requirements.…”

Section: Introductionmentioning

confidence: 99%

A novel ultra‐thin backlight system without optical sheets using a multi‐layered lightguide

Ishida¹,

Yuki²

2011

Abstract— A backlight system using a newly developed multi‐layered lightguide (MLL) is described. The MLL can function as a backlight without additional optical sheets such as prism sheets or diffusers. It was developed as a multi‐layered sheet featuring different refractive indexes for different layers. A prototype was built, and the principles were confirmed by comparison with theory. With a thickness of 0.414 mm, the prototype is the thinnest backlight in the world, using only a MLL and a reflector.