Patterned Compliant Layer for Shear Force Absorption in Capacitive Sensors
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Solution Overview
Problem
Capacitive force sensors in electronic devices are rendered inoperable or break when subjected to significant shear forces during drops, due to lateral movement of substrates, which compromises their functionality.
Innovation Solution
A patterned compliant layer with angled elements is positioned between substrates, providing isotropic behavior under shear forces and anisotropic behavior under compressive forces, enhancing deformability and compressibility, and configured as a transversely isotropic compliant layer to absorb forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a force sensor uses rigid substrates to maintain structural stability, then manufacturing precision and structural integrity are improved, but the sensor becomes vulnerable to damage from shear forces during drops
Solution Approach 1:
The patent introduces a compliant layer with a patterned structure between the substrates, allowing the sensor to flex and deform under shear forces rather than remaining rigid. This compliant layer acts as a flexible element that absorbs lateral movement during drops, preventing substrate damage while maintaining sensor functionality.
Solution Approach 2:
The compliant layer is designed to dynamically respond to applied forces by deforming in controlled ways. Under normal operation, it maintains sensor functionality, but under extreme shear forces during drops, it allows substrate movement to prevent damage, thus adapting the structural behavior based on force conditions.
2Reliability
If a compliant layer is added to absorb shear forces, then reliability under drop conditions is improved, but device complexity increases
Solution Approach 1:
The compliant layer features a patterned structure with repeating geometric elements that create a porous-like configuration. This patterned design provides the necessary compliance and shear force absorption while maintaining a relatively simple manufacturing process and avoiding the need for complex multi-layer constructions.
3Reliability
If the compliant layer is made highly deformable to absorb shear forces, then protection against damage is improved, but measurement precision may deteriorate
Solution Approach 1:
The compliant layer is positioned specifically between the substrates where shear forces are transmitted, while the force-sensitive structures remain in locations optimized for measurement. This localized compliance provides protection where needed without interfering with the precision measurement zones.
Solution Approach 2:
The sensor is divided into distinct functional zones: the compliant layer for shear force absorption and the force-sensitive structures for precise measurement. This segmentation allows each component to optimize its function independently, with the compliant layer handling protection and the sensing structures maintaining measurement 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 patterned compliant layer allows the force sensor to operate across a range of forces, distinguish different inputs, and maintain functionality even when subjected to shear forces, preventing damage and enabling continuous operation.
Implementation Method 1
The patterned compliant layer can deform when one or more of a compressive force and/or a shear force is/are exerted on the sensor layer
Implementation Method 2
a capacitive force sensor that can be used to detect a touch or force input applied to a surface of the electronic device. In some instances, a capacitive force sensor includes one or more pairs of conductive electrodes. The capacitance of each capacitor can vary based on an applied force
Data Source
AI summary
A sensor layer, such as a force sensor layer, can be in included in an electronic device. The sensor layer includes a patterned compliant layer that is positioned between a first substrate and a second substrate. The patterned compliant layer includes multiple angled compliant elements that are angled at one or more angles with respect to the first and second substrates.