Polarized backlight with constrained angular divergence for enhancement of light extraction efficiency from wire grid polarizer

Abstract

Efficiency of liquid crystal displays highly depends on the amount of polarized light emerging from the backlight module. In this paper, a backlight architecture using a nanoimprint wire grid polarizer for polarization recycling is proposed and studied, in which the extraction efficiency of polarized light is the major concern. The backlight module is composed of the stack of a wire grid polarizer, a lenticular array and a light guide plate. The light guide plate features interleaving v-groove and trapezoidal ridge coated with aluminum on the top surface, and scattering dot array on the bottom. The angular divergence of emerging light from the light guide plate can be well constrained so as to exploit the angular range with the best transmission of polarized light for the wire grid polarizer. The prototype of a 2.5-inch module has demonstrated an angular divergence of 48°. The overall extraction efficiency of polarized light enhanced by 21% and uniformity of 76% have been achieved.

An Iterative Method for the Uniformity Improvement of Edge-Lit Backlight

“…For uniform illumination, the luminous flux of each region Φ should approximate the average luminous flux of LGP Φ ave, , and the degree of this approximation can be represented by the relative deviation shown in (2). When the relative deviation of a region is greater than a small preset value, such as 1% used in this study, the microstructure size of this region will be adjusted by , +1 = .…”

“…Particularly for small and medium sized LCD panels, a high performance light guide plate (LGP) is the most important component of the LCD backlight module. In the past few years, researchers have made efforts to propose new structures of LGPs to increase the efficiency of the LCD backlight module [1][2][3][4] or develop useful methods to improve the uniformity of the backlight. Lee et al [5] first used experiments to design the incoupling part of LGP and then a density based approach with progressive quadratic response surface modeling was used to optimize the dot patterns; the uniformity reached 82%.…”

Preparation and Characterization of Ag Nanoparticle/SiO2 Composite for Optical Application

“…Each component has different function in light guide plate. There are various types of LGP that have been designed from researchers to increase its efficiency [2][3][4][5]. Basically, LGP is expected to have high intensity of light from light source to manage light to the front of LGP.…”

Integrating Backlight With Color-Filter-Free Panel for Enhancing Performance of LCD

“…In a similar way, stacking a layer composed of birefringent material on microstructures of the light guide plate (LGP) surface to make them selectively reflect the light linearly polarizing in one direction out of the LGP (p-wave or s-wave only) [4]- [7]. The second concept involves forming a subwavelength grating with double-layer materials on the surface of an LGP or on a film substrate to induce the light to emerge in a linearly polarized state [8]- [13]. However, fabricating subwavelength gratings on a large area of a substrate or LGP surface is extremely difficult.…”