Luminance Enhancement Structure with Wavy-Edged Columns

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Solution Overview

Problem

Electrophoretic display devices face reduced brightness due to total internal reflection and the Moiré effect when using luminance enhancement structures, which requires costly customization based on display cell size and shape.

Innovation Solution

A luminance enhancement structure with wavy-edged columns and triangular grooves, optically flat surfaces, and a refractive index of 1.4 to 1.7, designed to reduce Moiré patterns and enhance brightness uniformly across different display cell sizes and shapes, with the ability to change brightness uniformly with viewing angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a luminance enhancement structure is applied to enhance brightness, then the brightness of the display device is improved, but the Moiré effect occurs which significantly affects image quality

Engineering Contradiction:

ImprovebrightnessVSAvoidMoiré effect

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by designing columns with wavy edges instead of straight edges, and using triangular grooves with specific apex angles. This asymmetric geometry disrupts the periodic patterns that cause Moiré effects while maintaining the light-scattering properties needed for brightness enhancement. The wavy edges create irregular light diffusion paths that prevent Moiré pattern formation.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent implements local quality by creating columns with varying wavy edge patterns and triangular grooves with specific local geometries. Each column and groove has optimized local characteristics (wavy edge amplitude, groove apex angle) that are tailored to scatter light effectively while avoiding Moiré effects at specific locations across the display surface.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If different luminance enhancement structures are designed for different display devices to avoid Moiré effect, then the Moiré effect is reduced, but the manufacturing cost increases significantly

Engineering Contradiction:

ImproveMoiré effectVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent achieves universality by designing a single luminance enhancement structure with wavy-edged columns and triangular grooves that can be applied to various display devices with different cell sizes and shapes. This universal design effectively reduces Moiré effects across multiple display types without requiring customization, thereby maintaining low manufacturing costs while achieving the Moiré reduction goal.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses parameter changes by optimizing the wavy edge characteristics and triangular groove geometry (apex angles) to create a robust design that performs effectively across different display configurations. These parameter optimizations enable the same structure to adapt to various display cell sizes and shapes without requiring redesign, reducing manufacturing complexity and cost.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If a luminance enhancement structure is used to enhance brightness, then light scattering is improved, but total internal reflection causes loss of 30-50% of scattering light

Engineering Contradiction:

ImprovebrightnessVSAvoidlight loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent applies curvature principles through wavy edges on columns instead of straight edges. This curved geometry creates multiple light scattering angles and paths, reducing the likelihood of total internal reflection by distributing light more uniformly in different directions. The triangular grooves also contribute to light redirection, minimizing energy loss from total internal reflection.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The structure effectively reduces the Moiré effect and enhances brightness uniformly across various display devices, regardless of cell size and shape, while minimizing total internal reflection, thus improving image quality and reducing costs.

Implementation Method 1

some of the scattering light from the display panel may reflect back to the display device by total internal reflection

Methodology Applied

Scientific EffectLight scattering: Scattering

Implementation Method 2

Total internal reflection would occur with electrophoretic display devices due to the fact that the display device usually has components of a high refractive index

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

The surface of the grooves is optically flat and optionally coated with a metal layer

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS8441414B2Luminance enhancement structure with Moiré reducing design

Publication Date: 2013.05.14 E INK CORP

AI summary

The present invention is directed to luminance enhancement structure for reflective display devices. The structure not only can enhance the brightness of a display device, but also can reduce the Moiré effect of the display device. The present invention is also directed to a display device comprising an array of microcups and a luminance enhancement structure.