Flexible Cholesteric Liquid Crystal Display with Elastic Back Structure
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Solution Overview
Problem
Cholesteric liquid crystal writing tablets without a casing lack pressure support, making them not very rugged for handling and prone to delamination under abusive use.
Innovation Solution
A liquid crystal display device with a flexible front substrate and an elastic back structure, which can deform under pressure to display images without the need for a rigid casing, and can be erased by applying an electric field or flexing the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid casing is used to protect the liquid crystal panel, then the panel is protected from damage and pressure support is provided, but the device complexity increases and the device becomes more prone to delamination under abusive use
Solution Approach 1:
The patent replaces the rigid casing with a flexible thin film structure. The liquid crystal panel itself is made flexible through the use of flexible substrates and elastic back structures, eliminating the need for a rigid protective casing while maintaining durability and resistance to abusive handling.
Solution Approach 2:
Instead of using a rigid casing to protect a rigid panel, the invention inverts the approach by making both the panel and its support structure flexible. This inversion allows the device to withstand abuse better while reducing structural complexity.
2Force
If a rigid back structure is used to support the stylus, then pressure is supported effectively, but the device cannot be flexed and is more prone to delamination
Solution Approach 1:
The rigid back structure is replaced with a flexible thin film structure that includes an elastic layer. This flexible structure maintains the ability to support stylus pressure while allowing the entire device to flex without delamination.
Solution Approach 2:
The back structure uses composite materials including flexible substrates and elastic layers that combine to provide both pressure support and flexibility. The composite structure allows localized deformation under pressure while maintaining overall structural integrity during flexing.
3Ease of operation
If the liquid crystal panel is made flexible to allow local deformation for writing, then clear writing is achieved, but the device becomes more susceptible to damage without a rigid casing
Solution Approach 1:
The entire liquid crystal panel assembly is made flexible using flexible substrates and elastic back structures. This allows localized deformation for clear writing while the overall flexible construction provides damage resistance by allowing the device to flex without breaking.
Solution Approach 2:
The mechanical properties of the panel are changed by using flexible materials with appropriate elastic moduli. The elastic back structure provides localized compliance for writing while maintaining overall structural integrity, changing the parameter of rigidity to flexibility throughout the device.
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 device is more resistant to abusive handling and can form images through local deformation of the elastic back structure, while the erasing mechanism allows for repeated use.
Implementation Method 1
Pressure applied on the flexible front substrate changes a texture of the cholesteric liquid crystal material from a focal conic texture to a planar texture, which displays an image
Implementation Method 2
Application of an electric field to the liquid crystal layer erases an image on the flexible front substrate by transitioning the liquid crystal from the planar texture back to the focal conic texture
Implementation Method 3
The elastic back structure, when present, locally deforms in response to the applied pressure and returns to its original shape, enabling repeated writing and erasing
Data Source
AI summary
A liquid crystal display device includes a flexible front substrate, a liquid crystal layer comprising cholesteric liquid crystal material, and: i) a flexible back substrate and an elastic material layer; or ii) an elastic back substrate. The flexible front substrate is located more proximal to a person viewing the liquid crystal display device than is the liquid crystal layer. The i) flexible back substrate and the elastic material layer; or ii) the elastic back substrate, when present, are located in back of the liquid crystal layer. Pressure on the flexible front substrate changes a texture of the cholesteric liquid crystal material which displays an image. The pressure is from at least one of: i) impact of a projectile, a corresponding image including an impact mark; ii) a writing instrument, a corresponding image including writing or drawing; and iii) an imprinting instrument, a corresponding image including an imprinted image. Application of an electric field to the liquid crystal layer or flexing of the liquid crystal layer erases at least a portion of the image. Another aspect is a liquid crystal display device that includes a flexible front substrate, a liquid crystal layer comprising cholesteric liquid crystal material, and an elastic back structure that makes the liquid crystal display device elastic.