Integral Spacer Dots for Resistive Touch Screen
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Solution Overview
Problem
Existing resistive touch screens face issues with spacer dots being loose, reducing accuracy and causing device failure, and the use of additional materials like adhesives diminishes clarity and increases manufacturing costs.
Innovation Solution
A flexible cover sheet with integral compressible spacer dots, where the spacer dots are formed as part of the sheet material, providing a variable height and shape to maintain separation between conductive layers and prevent unintended contact, allowing for robust and accurate touch detection without additional adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spacer dots are formed by screen printing, spraying, or sputtering with additional adhesive materials, then spacer dots can be created to separate conductive layers, but manufacturing complexity and cost increase, and display clarity is diminished
Solution Approach 1:
The spacer dot material is merged with the flexible cover sheet material into a single integrated component. The spacer dots are formed as protrusions directly from the flexible cover sheet material itself, eliminating the need for separate adhesive materials and complex multi-step deposition processes. This integration resolves the contradiction by maintaining the separation function while dramatically simplifying manufacturing.
Solution Approach 2:
The flexible cover sheet material serves multiple functions simultaneously: it provides the flexible substrate, contains the spacer dots for separation, and eliminates the need for additional adhesive materials. This multi-functionality resolves the contradiction by consolidating multiple components into one, reducing manufacturing complexity while maintaining reliability.
2Manufacturing precision
If photolithography is used to form spacer dots, then precise placement can be achieved, but spacer dots may come loose and move, causing unintended actuations and reducing robustness
Solution Approach 1:
The spacer dots are merged with the flexible cover sheet into a single integral structure. The protrusions are formed directly from the cover sheet material itself, ensuring they cannot come loose or move during operation. This integration simultaneously achieves precise placement through controlled formation and guarantees long-term stability, resolving the contradiction between manufacturing precision and reliability.
3Reliability
If traditional spacer dot materials are used, then separation function is provided, but stress at spacer dot locations causes device failure after multiple actuations
Solution Approach 1:
The material parameters of the spacer dots are changed by using the same elastomeric material as the flexible cover sheet, ensuring matched mechanical properties. This parameter matching allows the spacer dots to flex and compress uniformly with the cover sheet during actuation, distributing stress evenly and preventing localized failure, thereby extending device lifespan while maintaining separation function.
Solution Approach 2:
The spacer dots and flexible cover sheet form a composite structure with matched material properties. Both are made from the same or compatible elastomeric materials, creating a unified mechanical system that responds uniformly to stress and strain during repeated actuations, preventing delamination or failure at the interface.
4Reliability
If spacer dots are made visible by mismatched index of refraction, then spacer dot function is clear, but display quality is reduced
Solution Approach 1:
The optical properties of the spacer dots are matched to the flexible cover sheet by using the same material with identical index of refraction. This makes the spacer dots optically invisible, allowing light to pass through uniformly without distortion or visible artifacts, thereby maintaining high display clarity while the spacer dots remain functional for separation and touch actuation.
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 manufacturing simplicity, accuracy, and clarity while improving the robustness and durability of the touch screen by ensuring consistent and reliable electrical contact between conductive layers.
Implementation Method 1
when a minimum required activation force is applied to the touch screen at the location of one of the compressible spacer dots, the compressible spacer dot is compressed to allow electrical contact between the first and second conductive layers
Implementation Method 2
integral compressible spacer dots formed thereon, each integral compressible spacer dot having a base closest to the substantially planar surface and a peak furthest from the substantially planar surface
Data Source
AI summary
A touch screen comprising a flexible sheet comprising a substantially planar surface and integral compressible spacer dots formed thereon, where each spacer dot comprises a base cross section in the substantially planar surface of the flexible sheet defined by a first point or set of connected points intersecting an axis in the substantially planar surface, a second opposed point or set of connected points intersecting the axis, and first and second continuous edge segments connecting the first and second points or end points of the first and second sets of points on opposite sides of the axis, wherein the spacer dot has a variable height perpendicular to the substantially planar surface along the axis, and wherein the surface of the spacer dot extending above the base cross section is not equidistant from the mid-point of the axis between the intersections of the first and second points or sets of connected points and the axis.