Electrophoretic Display Device with Blocking Layers for Contrast

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Solution Overview

Problem

Existing color display devices face challenges in achieving high contrast ratios and efficient pigment particle movement, along with issues like light leakage, which are not adequately addressed by current technologies.

Innovation Solution

The proposed display device features display cells sandwiched between a common electrode and a layer with multiple driving electrodes, including a designated electrode, with blocking layers or brightness enhancement structures on the viewing side to control pigment particle movement and enhance contrast, allowing for improved color display states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple driving electrodes are used to enable pigment particle movement in multiple directions for color display, then the display capability is improved, but the device complexity increases

Engineering Contradiction:

Improvecolor display capabilityVSAvoidelectrode structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The driving electrode layer is segmented into multiple independently controllable driving electrodes arranged in a matrix pattern. Each driving electrode can be independently activated to control pigment particle movement in specific directions, enabling multiple color states without requiring a complex three-dimensional electrode structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A blocking layer is introduced as an intermediary component between the driving electrodes and the viewing side. This blocking layer selectively blocks light from specific regions corresponding to designated electrodes, enabling precise control of color display states without requiring direct complex electrode geometry for each color state.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Illumination intensity

If blocking layers are added to control light leakage and improve contrast ratio, then the contrast ratio is improved, but the device complexity increases

Engineering Contradiction:

Improvecontrasit ratioVSAvoidlayer structure complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The blocking layer is merged with the existing electrode structure by positioning it to correspond with designated electrodes in the driving electrode layer. This integration allows the blocking layer to serve dual purposes: controlling light leakage for improved contrast and defining active display regions, without requiring completely separate structural components.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of controlling light leakage through complex three-dimensional electrode geometries, the solution transitions to a two-dimensional planar blocking layer that selectively blocks light paths. This dimensional simplification achieves the same contrast improvement function with a simpler structural implementation.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Object-affected harmful factors

If the width of blocking layers is increased to fully cover designated electrodes for optimal light blocking, then light leakage is reduced, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvelight leakageVSAvoidalignment precision

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The blocking layer is designed with spatially varying properties: its width and positioning are optimized locally to correspond with designated electrodes rather than uniformly covering all electrodes. This local optimization allows sufficient light blocking where needed while reducing overall manufacturing precision requirements by not requiring uniform high-precision alignment across the entire display surface.

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

This design achieves better control over pigment particle movement, increased contrast ratio, and reduced light leakage, while simplifying the manufacturing process and reducing costs, thereby providing improved performance and functionality.

Implementation Method 1

U.S. Pat. No. 7,046,228 discloses an electrophoretic display device having a dual switching mode which allows the charged pigment particles in a display cell to move in either the vertical (up/down) direction or the planar (left/right) direction.

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Implementation Method 2

The blocking layers are black matrix layers. In one embodiment, the width of the black matrix layers is equal to or greater than the width of the designated electrodes.

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS8169690B2Color display devices

Publication Date: 2012.05.01 E INK CORP

AI summary

The present invention is directed to color display devices. The color display devices comprise display cells which is capable of displaying multiple color states. The display device may also comprise black matrix layers or a brightness enhancement structure on the viewing side. The present invention is directed to a display device comprising a plurality of display cells, wherein each of said display cells is sandwiched between a first layer comprising a common electrode and a second layer comprising a plurality of driving electrodes and at least one of the driving electrodes is a designated electrode, and said display device further comprises blocking layers on its viewing side and said blocking layers are located in positions corresponding to the designated electrodes.