Resilient Cholesteric Liquid Crystal Writing Device
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Solution Overview
Problem
Cholesteric liquid crystal writing tablets lack ruggedness for abusive use without a casing, leading to delamination and damage, and existing solutions that provide ruggedness, such as rigid casings, compromise flexibility and add weight.
Innovation Solution
A flexible writing device with a thin, transparent front writing surface layer and a multilayered back support layer that provides pressure support and resilience, allowing the device to be bent repeatedly without delamination, and includes a seal to confine the cholesteric liquid crystal material, enabling erasure with voltage waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid casing is used to protect the writing panel, then the panel is protected from damage and delamination, but the device loses flexibility and increases in weight
Solution Approach 1:
The patent replaces the rigid casing with a flexible back support layer that provides mechanical support while allowing the device to be bent. This flexible layer maintains the protective function against delamination and damage while enabling flexibility that the rigid casing prevented.
Solution Approach 2:
The patent changes the mechanical properties of the support structure from rigid to flexible by using a flexible back support layer with appropriate material properties. This parameter change allows the device to maintain protection while gaining flexibility for bending and rolling.
2Reliability
If a rigid casing is used to protect the writing panel, then the panel is protected from damage, but the device increases in weight
Solution Approach 1:
The flexible back support layer serves as a thin, lightweight protective structure that replaces the heavy rigid casing. This flexible layer provides necessary mechanical support and protection against damage while keeping the device weight minimal.
Solution Approach 2:
The flexible back support layer uses lightweight materials that provide adequate protection without the weight penalty of rigid casings, effectively replacing heavy protective structures with lighter alternatives that maintain sufficient durability.
3Adaptability or versatility
If the front substrate is made thin for flexibility, then the device can be bent repeatedly, but the substrate may not provide sufficient pressure support
Solution Approach 1:
The patent divides the pressure support function between the thin front substrate (which provides flexibility) and the flexible back support layer (which provides pressure support). This segmentation allows each layer to specialize in its primary function without compromise.
Solution Approach 2:
The flexible back support layer acts as an intermediary that transmits and distributes stylus pressure to the liquid crystal layer while allowing the front substrate to remain thin and flexible. This intermediary layer ensures sufficient pressure support without requiring a thick front substrate.
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 remains functional after repeated bending, erasing images completely and initializing the surface for new writing, maintaining flexibility and resistance to damage, similar to a Post It Note, while being thin and lightweight.
Implementation Method 1
The cholesteric liquid crystal material changes in texture by application of pressure to the front writing surface layer to create an image
Implementation Method 2
pressure sensitive cholesteric liquid crystal writing panel
Implementation Method 3
Erasure can be accomplished with the writing panel being cleared by a press button switch that applies voltage waveforms to transparent conducting electrodes that drives the cholesteric liquid crystal from its color reflective state back to its focal conic transparent state
Data Source
AI summary
A writing device includes a liquid crystal layer including cholesteric liquid crystal material. There are electrically conductive layers between which the liquid crystal layer is disposed. There is a front writing surface layer that is transparent and a back support layer between which the electrically conductive layers and the liquid crystal layer are disposed. The cholesteric liquid crystal material changes in texture by application of pressure to the front writing surface layer to create an image. A seal confines the cholesteric liquid crystal material between the front writing surface layer and the back support layer. The electrically conductive layers are adapted to enable a voltage waveform to be applied thereto that erases the image. In one aspect, the resilience to bending the writing device is defined by enabling the writing device to be bent to a radius of curvature of 100.0 millimeters for 10 repetitions of the bending and after each of the repetitions of the bending the voltage waveform completely erases the image. In another aspect, the back support layer comprises a first sublayer formed of a flexible polymeric material adjacent to the back electrically conductive layer, a second sublayer comprising a backer that is flexible and thicker and of a different material than the first sublayer and a bonding layer located between the first sublayer and the second sublayer. In yet another aspect, the seal includes an elastomeric material and wherein the front writing surface layer has a thickness in a range of 0.5 to 4.5 mils and the back support layer has a thickness in a range of 0.6 to 34.5 mils.