Privacy Display Liquid Crystal Stabilization for Touch Artifact Reduction
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Solution Overview
Problem
Existing privacy displays lack electrically switchable off-axis optical output control, leading to limited functionality and visibility issues, and touch screens experience luminance and reflectivity artifacts due to mechanical stress.
Innovation Solution
A display device with a cured polymer material in the liquid crystal layer, comprising acrylate or thiol materials, reduces luminance and reflectivity artifacts by aligning liquid crystal molecules with applied voltage, providing stable operation across modes and mechanical resilience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If micro-louvre optical films are used for privacy display, then image visibility to primary user is improved, but electrically switchable control is lost
Solution Approach 1:
The patent uses liquid crystal materials that change their optical properties (birefringence, alignment) in response to electrical voltage changes. By adjusting the voltage applied to the liquid crystal layer, the display can dynamically switch between privacy mode (restricted viewing angles) and public mode (wide viewing angles), providing electrically switchable control while maintaining image visibility.
2Ease of operation
If liquid crystal layer is subjected to mechanical force during touch input, then touch sensitivity is improved, but luminance and reflectivity artifacts increase
Solution Approach 1:
The patent incorporates a polymer stabilizing network within the liquid crystal layer that is formed in advance through photopolymerization. This pre-formed network structure provides mechanical support and stabilizes the liquid crystal molecules against displacement caused by touch forces, thereby preventing luminance and reflectivity artifacts before they occur during touch input operation.
Solution Approach 2:
The patent creates a composite structure by combining liquid crystal material with a polymer stabilizing network. The liquid crystal provides the desired optical switching functionality while the polymer network provides mechanical stability. This composite material approach allows the system to withstand mechanical forces during touch input without generating visual artifacts.
3Strength
If liquid crystal molecules are stabilized with polymer network, then mechanical resilience is improved, but optical uniformity may deteriorate
Solution Approach 1:
The patent uses photomasks during the photopolymerization process to create spatially selective polymer networks. By controlling the exposure pattern, the polymer network is formed only in specific regions or at controlled densities, allowing different areas of the liquid crystal layer to have different levels of stabilization. This local quality approach maintains optical uniformity in viewing areas while providing mechanical resilience where needed.
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 visual security in privacy mode and uniformity in public mode while maintaining mechanical stability and reducing artifacts during touch input.
Implementation Method 1
a liquid crystal layer arranged between a first polariser and a second polariser, wherein the liquid crystal layer comprises a liquid crystal material with a positive dielectric anisotropy
Implementation Method 2
The liquid crystal material may further comprise a polymerisation photo-initiator. The step of curing the curable liquid crystal material comprises illumination by ultraviolet radiation
Implementation Method 3
at least one polar control retarder arranged between the reflective polariser and the additional polariser
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A display comprises a polarised output spatial light modulator, switchable liquid crystal retarder, absorbing polariser and touch panel electrodes. The switchable liquid crystal layer is stabilised by a cured reactive mesogen material during application of an applied voltage. Light scatter in privacy mode is reduced and visual security level enhanced. Visibility of disclinations during application of applied pressure, for example from a finger on a touch screen is minimised.