Linearly polarized light‐emitting backlight

Abstract

Abstract— A new polarized backlight system for liquid‐crystal displays (LCDs) is presented in which one linear polarization is preferentially coupled out by anisotropic scattering. The lightguide consists of a polymeric polarization‐dependent scattering film adhered to a transparent polymeric substrate. By changing the scattering power of the film, the polarized light outcoupling angles can be influenced and optimized to achieve a maximum outcoupling centered along the normal direction. The other linear polarization is mainly trapped in the lightguide and is shown to be recycled to enhance the overall light and/or energy efficiency. With a proper substrate choice, the achieved local contrast exceeds 14 over a 50‐mm range. A collimated light input further enhances the polarized contrast to well over 17.

Diffractive backlight grating array for mobile displays

“…Additional efficiency has been sought by studying polarizing backlights [19][20][21][22] and diffractive backlights. [3][4][5][6]11,23 Integration of several films in the backlight is now a trend, and hybrid functionality is employed in a single film, giving good potential to thinner display backlights.…”

Review: Progress in liquid crystal displays by new developments in functional polymers

“…Scattering of polarized light in a stretched polyester film provided with isotropic, index-matched particles. The SEM pictures show cross-sections of the films perpendicular (left) and parallel (right) to the stretching direction [22,23] Rather than recycling wrongly polarized light by reflection, another way to improve the backlight efficiency is by using the direct generation of polarized light using anisotropic light out-coupling structures applied on a waveguiding slab [24,25]. Unpolarized light, e.g.…”

“…High information displays such as in notebook computers require higher contrasts, which can be achieved by clean-up polarizers (dichroic, absorbing) without too much additional light loss. [24,25]. The red area resembles high intensity or contrast, the blue area low intensity or contrast values Another major energy consumer in a display is the color filter.…”

LED polarization conversion and angular shaping module for LCD backlighting

“…In order to increase the light utilization efficiency of illumination source, most of the current commercial products use the concept of polarization recycling where the light bounces back and forth within the backlight module in between a reflective polarizer and a diffusive reflector [1][2]. If single pass of light is desirable, a polarization conversion system in between the light source and liquid crystal layer is then required.…”