Front Light Guide Module Refractive Index Gradient for Electrophoresis Contrast

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Solution Overview

Problem

Electrophoretic display panels face a significant decrease in contrast ratio when a front light guide module is turned on in dark environments, leading to unsatisfactory image quality.

Innovation Solution

A front light guide module comprising a light guide plate, a light source, a functional material layer, and adhesive layers with specific refractive indices is designed to enhance contrast ratio, where the light guide plate has a higher refractive index than the adhesive layer, and the adhesive layer has a higher refractive index than the functional material layer, which is made of materials like poly(methyl methacrylate) or polycarbonate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a front light guide module is turned on in dark environments, then the display visibility is improved, but the contrast ratio significantly decreases

Engineering Contradiction:

Improvedisplay visibilityVSAvoidcontrast ratio

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the refractive indices of different layers in the light guide module. The light guide plate has a refractive index of 1.4-1.7, the adhesive layer has 1.3-1.6, and the functional material layer has 1.2-1.5, creating a specific gradient that optimizes both visibility and contrast ratio when the light source is activated

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials with different refractive indices arranged in specific layers. The combination of light guide plate material, adhesive layer material, and functional material layer creates a composite structure that manages light propagation effectively, maintaining high contrast ratio while enabling good visibility in dark environments

Inventive Principle:

Principle #40Composite materials

2Device complexity

If the light guide plate and functional material layer are directly adhered, then the structure is simplified, but the refractive index mismatch causes light scattering and reduces contrast ratio

Engineering Contradiction:

Improvestructure complexityVSAvoidcontras1t ratio

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an adhesive layer as an intermediary between the light guide plate and the functional material layer. This intermediate layer with refractive index of 1.3-1.6 serves as a transition medium that reduces the refractive index mismatch, minimizing light scattering at the interface while maintaining structural integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The adhesive layer is specifically positioned at the critical interface where refractive index transition is needed. This localized application of a material with intermediate refractive index properties addresses the light scattering problem at the specific location without requiring changes to the entire structure

Inventive Principle:

Principle #3Local quality

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 module significantly increases the contrast ratio of the electrophoretic display without undesirably decreasing it, even when the light source is turned on, thereby improving image quality in dark environments.

Implementation Method 1

The light guide plate has a first refractive index, and the first adhesive layer has a second refractive index. The first refractive index is greater than the second refractive index

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The light guide plate has a first refractive index, the first adhesive layer has a second refractive index, and the functional material layer has a third refractive index. The first refractive index is greater than the second refractive index, and the second refractive index is greater than the third refractive index

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

The first adhesive layer is interposed between the light guide plate and the functional material layer, and the first adhesive layer is configured to adhere the light guide plate with the functional material layer, in which the first adhesive layer has a second refractive index. The first refractive index is greater than the second refractive index, and the second refractive index is greater than the third refractive index

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS9612388B2Front light guide module and electrophoresis display having the same

Publication Date: 2017.04.04 E INK HLDG INC

AI summary

A front light guide includes a light guide plate, a light source, a functional material layer and a first adhesive layer. The light guide plate has a side surface, a first surface and a second surface opposite to the first surface. The light guide plate has a first refractive index. The light source faces the side surface and configured to emit light into the light guide plate. The functional material layer is disposed at a side adjacent to the first surface, and has a third refractive index. The first adhesive layer is interposed between the light guide plate and the functional material layer so as to adhere the light guide plate with the functional material layer. The first adhesive layer has a second refractive index. The first refractive index is greater than the second refractive index, and the second refractive index is greater than the third refractive index.