Normally Black Display Panel Using Orthogonal Polarization

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Solution Overview

Problem

Existing liquid crystal display panels in intelligent wearable devices operate in a normally white mode, resulting in low-contrast images due to light transmission when no voltage is applied, which is not ideal for modern demands.

Innovation Solution

A display panel design featuring a liquid crystal layer between substrates, an orthogonal polarization layer, and an absorbent layer that converts light polarization direction when an electric field is applied, allowing the panel to present a normally black state by absorbing light when unpowered, and enabling high contrast and dual display functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a liquid crystal display panel operates in normally white mode, then light transmission is maintained when no voltage is applied, but image contrast deteriorates due to the white state presentation

Engineering Contradiction:

Improvelight transmissionVSAvoidimage contrast

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The patent inverts the traditional normally white mode operation to normally black mode by positioning the absorbent layer on the first substrate side facing away from the liquid crystal layer. This inversion allows the panel to present black when unpowered and white when powered, thereby improving image contrast while maintaining adequate light transmission through the liquid crystal layer.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces an orthogonal polarization layer as an intermediary component between the liquid crystal layer and the absorbent layer. This polarization layer selectively transmits or blocks light based on polarization direction, working in conjunction with the liquid crystal's voltage-dependent polarization rotation to control the final light output state and enhance contrast.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If an orthogonal polarization layer and absorbent layer are added to achieve normally black mode, then image contrast is improved, but device complexity increases

Engineering Contradiction:

Improveimage contrastVSAvoidpanel structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines the orthogonal polarization layer and absorbent layer into a integrated optical stack on the first substrate side. The absorbent layer is positioned in direct contact with or adjacent to the orthogonal polarization layer, creating a compact configuration that achieves normally black operation without requiring separate complex control mechanisms for each layer.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The orthogonal polarization layer serves multiple functions: it acts as a polarization filter for the liquid crystal operation, provides structural support for the absorbent layer positioning, and contributes to the overall optical path control. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enhances image contrast by maintaining a black state when unpowered and allows for both normal and mirror display modes, meeting the increasing functional demands of intelligent wearable devices.

Implementation Method 1

the liquid crystal layer is configured to transmit light with a first polarization direction when no electric field is loaded and to convert incident light with the first polarization direction into emergent light with a second polarization direction which is orthogonal to the first polarization direction when an electric field is loaded

Methodology Applied

Scientific EffectLiquid crystal polarization rotation: Liquid Crystals

Implementation Method 2

the orthogonal polarization layer is configured to transmit the light with the first polarization direction and reflect the light with the second polarization direction

Methodology Applied

Scientific EffectPolarization filtering: Polarisation

Implementation Method 3

the first absorbent layer is configured to absorb light incident on the first absorbent layer

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS10409106B2Display panel, operating method thereof and display device

Publication Date: 2019.09.10 BOE TECHNOLOGY GROUP CO LTD

AI summary

The present disclosure provides a display panel, an operating method thereof and a display device. The display panel includes first substrate and second substrate disposed opposite to each other, liquid crystal layer disposed between first substrate and second substrate, orthogonal polarization layer disposed on a side of first substrate facing towards liquid crystal layer, and first absorbent layer disposed on a side of first substrate facing away from liquid crystal layer. When no electric field is loaded, both liquid crystal layer and orthogonal polarization layer transmit light with first polarization direction. When electric field is loaded, liquid crystal layer converts incident light with first polarization direction into emergent light with second polarization direction which is orthogonal to first polarization direction, and the orthogonal polarization layer reflects the light with the second polarization direction. The first absorbent layer absorbs the light incident thereon.