Shear Wave Touch Sensor with Echelon Arrays
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Solution Overview
Problem
Existing touch sensors, such as acoustic and projected capacitance sensors, face challenges with sensitivity to water and contaminants, electromagnetic interference, difficulty in scaling to large sizes, and integration complexity, limiting their commercial success and versatility.
Innovation Solution
A touch panel design incorporating shear wave transducers and echelons on a substrate, with redundant sensing modes and arrays, allows for residue detection and easy integration, enabling bezel-free operation and enhanced reliability through redundancy and flexibility in sensing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If projected capacitance touch sensors are used, then touch sensitivity and multi-touch capability are improved, but sensitivity to water and contaminants increases, requiring special gloves and reducing reliability
Solution Approach 1:
The touch sensor system is divided into multiple independent acoustic arrays that can operate separately. Each array generates and detects acoustic waves independently, allowing the system to segment the sensing function across multiple channels that can be individually managed for redundancy and reliability.
Solution Approach 2:
The system changes the operating parameters by using acoustic wave modes (shear waves, surface waves, Lamb waves) instead of electromagnetic capacitance fields. This fundamental parameter change transforms the sensing mechanism from one that is sensitive to water/contaminants to one that is impervious to such factors while maintaining touch sensitivity.
2Object-affected harmful factors
If acoustic touch sensors are used, then resistance to water and contaminants is improved, but device complexity and integration difficulty increase
Solution Approach 1:
The acoustic array system is designed to perform multiple functions: it can detect different types of waves (shear, surface, Lamb), operate in multiple modes (source wave mode, sensing wave mode), and provide both primary and redundant sensing capabilities. This multi-functionality reduces the need for separate systems and simplifies integration.
Solution Approach 2:
Multiple acoustic arrays are merged into a single integrated touch sensor system that shares common substrates, edge mount locations, and signal processing pathways. The first and second acoustic arrays are combined in one system with shared resources, reducing overall complexity compared to separate systems.
3Measurement precision
If acoustic arrays are used, then touch sensitivity is improved, but display viewing area is reduced due to array mounting requirements
Solution Approach 1:
The acoustic arrays are mounted on the edges of the substrate rather than being embedded in the display surface. This dimensional relocation moves the arrays from the 2D display plane to the 3D edge space, allowing the display surface to remain fully available for viewing while the arrays are positioned in the peripheral dimension.
Solution Approach 2:
The arrays are positioned asymmetrically at the edges of the substrate, utilizing the peripheral regions rather than central areas. This asymmetric placement optimizes the viewing area by keeping the symmetric display surface clear while positioning the functional arrays at the boundaries where they are least intrusive to the viewing experience.
4Object-affected harmful factors
If shear wave transducers are used, then resistance to water is improved, but manufacturing precision requirements increase
Solution Approach 1:
The echelon structures are formed as repeating geometric patterns that can be manufactured using standard photolithography and etching processes. The patterned echelons are created as copies of a master design, allowing for precise reproduction through conventional semiconductor manufacturing techniques rather than requiring custom precision machining.
Solution Approach 2:
The mechanical precision requirements are reduced by substituting mechanical echelon structures with acoustic wave propagation through patterned substrates. The acoustic functionality is achieved through the geometric patterning and material properties rather than requiring precisely machined mechanical components, allowing standard fabrication processes to achieve the necessary precision.
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 design provides resistance to contaminants, low electromagnetic interference, scalability, and ease of integration, while maintaining touch sensitivity comparable to projected capacitance sensors, suitable for mission-critical applications.
Implementation Method 1
a first shear transducer assembly mounted on the edge of the substrate, the first transducer assembly configured to generate a shear wave in a source wave mode in a first direction along the first centerline
Implementation Method 2
the shear wave is reflected at the first angle by the one or more of the plurality of echelons in the first array to a first sensing wave
Implementation Method 3
the shear wave is converted to a different wave mode than the source mode
Implementation Method 4
a first shear transducer assembly mounted on the edge of the substrate, the first transducer assembly configured to generate a shear wave
Data Source
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AI summary
A touch panel has a substrate having first and second surfaces, and defines a touch surface. A first portion of a touch system includes a first plurality of echelons on the first surface in a first array along a first centerline. Each echelon is formed at an angle to the first centerline, and a first shear transducer assembly on the edge of the substrate that generates a shear wave in a source wave mode in a first direction along the first centerline. A second portion of the touch system includes a second plurality of echelons on the first surface in a second array along a second centerline, each echelon at a second angle to the second centerline. The second centerline is orthogonal to the first. A second shear transducer assembly is mounted on the edge and generates a shear wave in a source wave mode in a second direction along the second centerline. The first sensing mode is different from the second sensing mode.