Analysis of Color Uniformity of White LED Lens Packages for Direct-lit LCD Backlight Applications

This paper proposes an algorithm for recovering the colors of objects from multiple near-infrared (near-IR) images. The International Commission on Illumination (CIE) color coordinates of objects are recovered from a series of gray images captured under multiple spectral near-IR illuminations using polynomial regression. The feasibility of the proposed algorithm is tested experimentally by using 24 color patches of the Color Rendition Chart. The experimental apparatus is composed of a monochrome digital camera without an IR cut-off filter and a custom-designed LED illuminator emitting multiple spectral near-IR illuminations, with peak wavelengths near the red edge of the visible band, namely at 700, 740, 780, and 860 nm. The average color difference between the original and the recovered colors for all 24 patches was found to be 11.1. However, if some particular patches with high value are disregarded, the average color difference is reduced to 4.2, and this value is within the acceptability tolerance for complex image on the display.

Section: Discussionmentioning

confidence: 99%

Recovering the Colors of Objects from Multiple Near-IR Images

Kim¹,

Oh²,

Kim³

et al. 2015

“…Usually 1-3 MLA films are adopted in a backlight, and a moiré pattern may be formed when the number of the MLA films is at least two. In this study, several approaches for avoiding moirés between two HA-MLA films were investigated by optical simulation based on the ray-tracing technique [12]. In general, moiré formation between the MLA and the LCD pixel array is regarded as a more serious problem in LCD.…”

Section: Introductionmentioning

confidence: 99%

Simulation Study on the Minimization of Moiré Patterns Caused by Microlens Array Films for Backlight Applications

Joo

2014

Self Cite

Microlens array (MLA) films have been used as brightness-enhancement components in many illumination systems, such as a backlight, which should meet the industrial needs of low cost and high brightness performance. A hexagonally-arranged MLA (HA-MLA) was chosen due to its high filling factor, which was a prerequisite for achieving high brightness-enhancement capability. The moiré fringes produced in a film stack composed of two HA-MLA were investigated, under four different lens configurations, by optical simulation. It was found that randomizing the lens configuration, while keeping the filling factor high, was effective way to develop high-gain MLA films for backlight applications.

“…Therefore optical films are generally employed when LED lighting devices are assembled and packaged. Their role is to redistribute the light rays coming out from the point LED sources and uniformly radiate onto the forward direction without sacrificing illuminance [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Viewing Angle Direction Brightness-Enhancement Optical Films using Surface Textured Silicon Wafers

Jang

Shim

Lee

et al. 2014

We demonstrate a low-cost, superbly efficient way of etching for the nano-, and micro-sized pyramid patterns on (100)-oriented Si wafer surfaces for use as a patterned master. We show a way of producing functional optical films for the viewing angle direction brightness-enhancement of Lambertian LED (light emitting diode)/OLED (organic light emitting diode) planar lighting applications. An optimally formulated KOH (Potassium hydroxide) wet etching process enabled random-positioned, and random size-distributed (within a certain size range) pyramid patterns to be developed over the entire (100) silicon wafer substrates up to 8" and a simple replication process of master patterns onto the PC (poly-carbonate) and PMMA (polymethyl methacrylate) films were performed. Haze ratio values were measured for several film samples exhibiting excellent values over 90% suitable for LED/OLED lighting purposes. Brightness was also improved by 13~14% toward the viewing angle direction. Computational simulations using LightTools™ were also carried out and turned out to be in strong agreement with experimental data. Finally, we could check the feasibility of fabricating low-cost, large area, high performance optical films for commercialization.