Bistable LCD Overlay for Electronic Writing Pad
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Solution Overview
Problem
Electronic writing tablets are vulnerable to damage and their protective overlays often obscure the written image, providing low resolution and poor pen-to-image registration.
Innovation Solution
An LCD touch screen overlay with a reversible attaching mechanism and bistable display technology that maintains image visibility without power consumption, allowing for pressure-activated image display and auto-erase functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent overlay is used to protect the writing surface, then the writing surface is protected from damage, but the overlay masks the image displayed beneath it, making it difficult to read
Solution Approach 1:
The patent introduces a liquid crystal overlay as an intermediary layer between the protective cover and the display. This liquid crystal layer acts as a optical mediator that can switch between transparent and opaque states, allowing the protective overlay to mask the display when not in use while becoming transparent when writing occurs, thus resolving the contradiction between protection and visibility
Solution Approach 2:
The patent changes the optical parameter (transparency) of the protective overlay by incorporating liquid crystal material that can alter its transparency state based on applied voltage or pressure. When voltage is applied or pressure is detected during writing, the liquid crystal transitions from opaque to transparent, allowing the display to be visible while maintaining protection
2Extent of automation
If a pixel-driven LCD display is used to show written images, then the writing can be displayed digitally, but the resolution is lower than actual writing and pen tip to displayed ink dots registration is inaccurate
Solution Approach 1:
The patent uses the liquid crystal overlay to create a direct optical copy of the writing surface. The liquid crystal molecules align with the underlying writing, allowing the display to replicate the exact position and shape of written elements without the resolution loss inherent in pixel-based displays, thereby achieving accurate pen-to-image registration while maintaining digital display capabilities
3Reliability
If a protective overlay is added to the writing tablet, then the writing surface is protected, but the device complexity increases
Solution Approach 1:
The patent merges the protective overlay function with the display function by integrating liquid crystal material directly into the overlay structure. This combination eliminates the need for separate protective cover and display components, reducing overall device complexity while maintaining both protection and visibility functions
Solution Approach 2:
The liquid crystal overlay serves multiple functions simultaneously: it provides physical protection for the writing surface, acts as a transparent barrier when not in use, and enables display visibility when writing occurs. This multi-functionality reduces the need for additional components, thereby reducing device complexity while achieving comprehensive protection
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 effectively protects the writing surface while maintaining high-resolution image visibility and accurate pen-to-image registration, enabling easy replacement and reducing the overall cost of ownership.
Implementation Method 1
initially display an image drawn or written upon the upper surface by application of pressure on the upper surface
Implementation Method 2
continue display of the image without the consumption of electrical power
Data Source
AI summary
An overlay for covering the writing surface of an electronic writing tablet includes (a) an LCD touch screen adapted to (i) initially display an image drawn or written upon the upper surface by application of pressure on the upper surface without requiring a transfer of matter to the upper surface and (ii) continue display of the image without the consumption of electrical power; (b) a source of electrical power; and (c) a reversible attaching mechanism for reversibly attaching the LCD touch screen over the writing surface of the writing tablet.