Transflective LCD Phase Retardation via Uniform LC Layer

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Solution Overview

Problem

Transflective liquid crystal display devices face challenges due to optical path differences between transmissive and reflective regions, leading to unmatched phase delays and display issues, which existing solutions attempt to address through complex manufacturing processes like double cell thickness structures that complicate the rubbing process.

Innovation Solution

A transflective liquid crystal display device with liquid crystal layers of equal thickness in both regions, utilizing an Advanced Dimension Switch (ADS) mode with strategically placed surface and pixel electrodes to control birefringence differences and achieve balanced phase retardation, eliminating the need for organic insulating layers and simplifying the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a double cell thickness structure is adopted to balance phase delays between transmissive and reflective regions, then phase delay consistency is improved, but manufacturing complexity increases due to the need for organic insulating layers and difficult rubbing processes

Engineering Contradiction:
Improvephase delay consistencyVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the optical parameters by introducing a retarding film with specific retardation value (50-200nm) in the reflective region, rather than changing the physical thickness of the liquid crystal layer. This parameter adjustment balances the optical path difference without requiring complex double cell thickness structure, thus resolving the contradiction between phase delay consistency and manufacturing simplicity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a retarding film as an intermediary optical element in the reflective region to compensate for the optical path difference. This intermediary component adjusts the phase delay of reflected light to match the transmissive region, avoiding the need for complex structural modifications and simplifying the manufacturing process

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If a double cell thickness structure is implemented to achieve matched phase delays, then display effect is improved, but ease of manufacture deteriorates due to uneven substrate surface complicating the rubbing process

Engineering Contradiction:
Improvephase delay matchingVSAvoidrubbing process ease
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of changing the liquid crystal layer thickness through complex structural modifications, the patent changes the optical retardation parameter by adding a retarding film with controlled retardation (50-200nm) in the reflective region. This maintains a uniform liquid crystal layer thickness across the substrate, ensuring the rubbing process can be performed easily on a flat surface while achieving the required phase delay matching

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If different liquid crystal layer thicknesses are used in transmissive and reflective regions to balance optical paths, then phase retardation consistency is improved, but device structure becomes more complex

Engineering Contradiction:
Improvephase retardation consistencyVSAvoidliquid crystal layer structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent maintains a uniform liquid crystal layer thickness across both transmissive and reflective regions, and instead achieves phase retardation consistency by adjusting the optical parameters through a retarding film in the reflective region. This approach simplifies the liquid crystal layer structure while still achieving the required optical balance

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of adjusting the thickness dimension of the liquid crystal layer (which would create structural complexity), the patent introduces a new dimensional element - a retarding film with specific optical retardation properties - to compensate for the optical path difference. This dimensional addition achieves phase retardation consistency without complicating the liquid crystal layer structure

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 approach ensures consistent phase retardation in both regions, improving display effects while reducing manufacturing difficulties by maintaining a flat substrate surface and simplifying the driving scheme, thus enhancing processing efficiency.

Implementation Method 1

utilizing an Advanced Dimension Switch (ADS) mode with strategically placed surface and pixel electrodes to control birefringence differences and achieve balanced phase retardation

Methodology Applied
Scientific EffectBirefringence: Birefringence

Data Source

PatentEP3153918B1Transflective type liquid crystal display device and driving method thereof
Publication Date: 2024.09.25 BOE TECHNOLOGY GROUP CO LTD
  • EP3153918B1 patent drawingFigure 1~2
  • EP3153918B1 patent drawingFigure 3~4

AI summary

Disclosed are a transflective liquid crystal display device and a driving method thereof. The transflective liquid crystal display device includes: a first surface electrode (103), a first pixel electrode (107), a second surface electrode (113) and a second pixel electrode (112) located in transmissive regions (A); the first surface electrode (103) and first pixel electrode (107) are located between a first substrate (102) and a liquid crystal layer (110), the second surface electrodes (113) and the second pixel electrodes (112) are located between a second substrate (104) and the liquid crystal layer (110). The device further includes: a third surface electrode (104), a reflection layer (105) and a third pixel electrode (108) located in reflective regions (B); the third surface electrode (104), the reflection layer (105) and the third pixel electrode (108) are located between the first substrate (102) and the liquid crystal layer (110). The liquid crystal layer (110) in both the transmissive region (A) and the reflective region (B) of the display device have an equal thickness, thereby drastically reducing the process difficulty of the device while guaranteeing the same phase retardations in both transmissive region and reflective region.