Transreflective LCD with Embossing Polarizer for Dual-Side Display

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Solution Overview

Problem

Existing liquid crystal display devices (LCDs) cannot bidirectionally display images in front and rear directions effectively, as reflective panels lack transmissive properties and dual-sided displays suffer from light pollution.

Innovation Solution

A transreflective liquid crystal display device with a moth-eye type embossing polarizer and a front light unit, allowing for bidirectional image display using both reflected and transmitted light, and minimizing surface reflection for enhanced brightness and contrast.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If a touch screen display device is thinned by reducing the number of components or simplifying their structures, then the overall thickness is reduced, but the strength and durability of the display device deteriorate

Engineering Contradiction:
Improvethickness of display deviceVSAvoidstrength and durability of display device
Core Design Contradiction:
Length of stationary objectVSStrength

Solution Approach 1:

The display device is divided into multiple functional layers including a flexible substrate, reflective layer, liquid crystal layer, and touch sensor layer. Each layer performs a specific function, allowing the overall structure to be thinned while maintaining strength through the distributed architecture of these segmented components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs composite material structures, particularly the flexible substrate composed of multiple layers including a base film and protective films. This composite structure provides both the flexibility needed for thinning and the mechanical strength required for durability, resolving the contradiction between reduced thickness and maintained strength.

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If a flexible display device is bent or folded to fit in a small space, then the space requirement is reduced, but the liquid crystal may be damaged due to internal stress

Engineering Contradiction:
Improvespace occupied by display deviceVSAvoidintegrity of liquid crystal
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The display device is designed with flexible components that allow dynamic bending and folding. The flexible substrate and encapsulation structures enable the device to change its shape adaptively, reducing the space it occupies while maintaining liquid crystal integrity through controlled flexibility that prevents excessive stress.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent incorporates protective films and encapsulation structures that are applied beforehand to cushion and protect the liquid crystal layer during bending or folding operations. These protective elements prevent direct stress on the liquid crystal, allowing the device to be folded into compact spaces without damaging the liquid crystal material.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Use of energy by moving object

If the display device uses a transmissive type liquid crystal display, then the light utilization efficiency is improved, but the response time increases due to light absorption by the liquid crystal

Engineering Contradiction:
Improvelight utilization efficiencyVSAvoidresponse time of liquid crystal
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent employs parameter changes in the liquid crystal material properties and layer thicknesses to optimize both light utilization efficiency and response time. By adjusting the molecular structure parameters of the liquid crystal and controlling the thickness of various layers, the device achieves high light efficiency while maintaining fast response characteristics.

Inventive Principle:
Principle #35Parameter changes

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

Enables bidirectional image display in LCDs and slim mobile stations with improved brightness, contrast, and reduced light interference, facilitating dual-sided image display without light pollution.

Implementation Method 1

a liquid crystal layer (314) formed on the lower substrate (301)

Methodology Applied
Scientific EffectLiquid crystal electro-optic effect: Electro-Optic Effects

Data Source

PatentEP1869523B1Liquid crystal display device and mobile station having the same
Publication Date: 2014.02.26 LG DISPLAY CO LTD
  • EP1869523B1 patent drawingFigure 1~3
  • EP1869523B1 patent drawingFigure 4
  • EP1869523B1 patent drawingFigure 5~6

AI summary

A liquid crystal display device includes: a transreflective liquid crystal panel; a front light unit supplying light to the transreflective liquid crystal panel; and a polarizer disposed on the transreflective liquid crystal panel and having an upper surface where fine protrusions are formed. In another aspect of the present invention, a liquid crystal display device includes: a transreflective liquid crystal panel; a first retardation compensation film formed under the transreflective liquid crystal panel; a first polarizer formed under the first retardation compensation film; a second retardation compensation film formed on the transreflective liquid crystal panel; and a second polarizer formed on the second retardation compensation film and having an upper surface where fine protrusions are formed. In a further another aspect of the present invention, a mobile station includes: a liquid crystal display device including a transreflective liquid crystal panel, a front light unit supplying light to the transreflective liquid crystal panel, and a polarizer disposed on the transreflective liquid crystal panel and having an upper surface where fine protrusions are formed; a communication unit performing communication with external devices; and a controller controlling the communication unit and an image display operation of the liquid crystal display device.