Yen-Hsing Lu

Design and Evaluation of Light Spread Function for Area-Adaptive LCD System

A methodology, based on two-dimensional super-Gaussian light spread functions (LSFs), was studied for the light-emitting-diode (LED) backlighting system in the high dynamic range (HDR) liquid crystal displays (LCDs). We proposed a novel LED-based optomechanical configuration to implement the desirable luminous pattern. A dual-liquid-crystal-panel system was constructed as a pseudo-HDR LCD to evaluate the super-Gaussian illumination. The proposed HDR scheme was verified via the current platform: overall luminance uniformity, contrast ratio and processing speed could be improved by factors of 1.55, 1.95-4.15, and 4.82, respectively. The design flexibility made the methodology applicable to any panel dimension and backlight division of the HDR LCDs, and to the conventional full-on backlighting LCDs as well.

Tandem Light-Guides With Micro-Line-Prism Arrays for Field-Sequential-Color Scanning Backlight Module

An optically partitioned backlight system consisting of tandem wedge-shaped light-guides (LGs) with micro-line-prism arrays was developed for scanning field-sequential-color (FSC) liquid crystal display (LCD) in large size. The unit of wedge-shaped LG combined with a light-emitting diode (LED) light-bar was designed and fabricated to collimate the extraction light within a narrow angular extent. Based on the edge lighting approach, the volume of backlight system can be reduced down to 25 mm without sacrifice of the optical behavior. As a result, 2750 nits average luminance subject to 50% duty cycle and 83% uniformity can be achieved. The leakages into the consecutive adjacent blocks were well suppressed to 11.86%.

64.3: Super-Gaussian Light Spread Function for High Dynamic Range Displays

Super-Gaussian light spread function was designed for high dynamic range liquid crystal displays. A dual-liquid-crystal-panel system was constructed to simulate an HDR display, and to evaluate the implementation of the proposed super-Gaussian and a general Gaussian distributions. According to the results, luminance uniformity and processing time of super-Gaussian LSF are superior to those of Gaussian LSF by factors of 1.55 and 178, respectively. Contrast ratio is improved by a factor about 2 to 4.15 as well. In addition, the undesired artifact, grid lines, can be suppressed to be invisible.

P-69: A Localized Partition Approach for High-Dynamic-Range Display

A mosaic-form backlight system for high-dynamic-range display was introduced. The backlight unit consisting of a side-emitting LED, a quadratic light guide, and a concentric prism sheet can form an isolated square super-Gaussian distribution over the local area of liquid crystal panel. By means of our approach, high-dynamic-range display system can reduce the time required for processing compensated image signal.

44.2: A Novel Direct-LED-Backlight Unit Using Grooved Hexagonal Light-Guide Plate

A novel large size backlight unit (BLU) which consists of modulized hexagonal light guide plate (LGP) based on micro-groove structures of polymethyl methacrylate (PMMA) material with a side emitting light emitting diode (LED) was developed. The grooved features expand the angular distribution from LED toward the exiting surface of the LGP. Therefore, the BLU with the optimum based angle of grooves can be thinner in volume, and can reduce the half number of LEDs (from 96 to 42) to yield the competitive uniformity of 81% compared with those of commercial Cold Cathode Fluorescent Lamp (CCFL) backlight and conventional LED backlight.

Principal Component Analysis of Multi-Pigment Scenario in Full-Color Electrophoretic Display

In this paper, we present a methodology to characterize the colorimetric performance of a full-color electrophoretic display (EPD) with multiple pigment formation. We use the principal component analysis to formulate the composite hybrid color-mixing system by using a single eigen-spectral component for each sub-pixel channel. Proposed model was validated to predict the chromatic features with high accuracy (ΔE AVE_CIEDE2000 <;0.2) for both micro-cup type and micro-encapsulated type EPD samples. This study is effective to uncover the underlying physical features from only colorant-mixture information in a novel color system.

P-118: Colorimetric Characterization of Monochromatic Microcup® Electrophoretic Display

The colorimetric characterization plays an important role in communicating color information across different image media. In this study, the specific color model is proposed for monochrome Microcup® electrophoretic display (EPD). Through the scalable absorptance spectrum and the corresponding scalars found out with Allens algorithm and colorimetric density, the proposed model can achieve the reliable accuracy that the average CIEDE 2000 value of prediction is below 1.

75.5: Evaluating Procedure of Color Rendering Property on Reflective LCD

An evaluating procedure was introduced and demonstrated to reveal the impact of color appearance induced by ambient illumination for reflective-type LCDs. The concepts of Color Rendering Index and Color Quality Scale were cooperated to account for the differences of color rendering between LED lightings with identical correlated color temperature but various spectra. The results showed that the colorimetric performance of reflective LCD was strongly dependent on various LED spectra and light level. And the proposed assessments, CRI and CQS, can effectively describe how well LED lighting renders the reflective-type LCD.

P‐114: A Scanning Backlight Module for FSC‐LCD Using Tandem Light‐Guides with Micro Line‐Prism Structures

A spatially partitioned backlight system composed of tandem wedge-shaped light-guides with micro line-prism arrays was developed for scanning field-sequential-color (FSC) LCD in large size. The light-guides combined with LED light-bars have been designed and fabricated to well distinguish each region and decrease the light leakage. By means of our approach, the volume of backlight system can be reduced down to 25 mm without sacrifice of the optical performance. As a result, 2750 nits average luminance subject to 50% duty cycle and 83% uniformity can be achieved. The leakages into the continuous adjacent blocks are well suppressed to 11.86%.