Force Sensor Shear Detection via Staggered Protrusions
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Solution Overview
Problem
Current force sensors primarily detect forces applied in the thickness direction, limiting the recognition of diverse and realistic user interfaces that require sensing forces in various directions as separate inputs.
Innovation Solution
A force sensor design featuring a first and second surface with protrusions and electrodes, where the protrusions are staggered and partially overlapping, allowing for contact between force sensing layers and electrodes when a force is applied, enabling the detection of shear forces by varying resistance based on applied pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If force sensors detect only forces in the thickness direction, then the sensor structure remains simple, but the capability to recognize diverse user interfaces is limited
Solution Approach 1:
The force sensing capability is segmented into multiple independent sensing elements arranged in a matrix pattern. Each sensing element detects force in the thickness direction, and by combining signals from multiple elements, the system can recognize shear forces and diverse input patterns without requiring complex individual sensor structures.
Solution Approach 2:
The force sensor is designed to perform multiple functions: it can detect normal forces in the thickness direction, shear forces in lateral directions, and various input patterns (tap, drag, pinch, etc.). This multi-functionality is achieved through the matrix arrangement of sensing elements that can detect both magnitude and direction of applied forces.
2Area of stationary object
If protrusions are fully overlapped to maximize sensing area, then more force can be detected, but manufacturing precision requirements increase due to alignment complexity
Solution Approach 1:
The first and second protrusions are designed with asymmetric offset positioning rather than perfect overlap. The first protrusions extend in a first direction while the second protrusions extend in a second direction perpendicular to the first direction, creating an interlocked pattern that achieves sufficient sensing area without requiring high-precision alignment.
Solution Approach 2:
Instead of requiring complete overlap of all protrusions, the design uses partial overlap with gaps between adjacent protrusions. This partial action approach maintains adequate sensing area while significantly reducing manufacturing precision requirements, as the gaps provide tolerance for alignment variations.
3Ease of manufacture
If protrusions are spaced apart to avoid overlap, then manufacturing is easier, but the sensing precision for shear forces decreases
Solution Approach 1:
The solution transitions from a single-layer protrusion design to a multi-layer interlocked design. First protrusions extend in a first direction from the first substrate, while second protrusions extend in a second perpendicular direction from the second substrate. This dimensional arrangement allows moderate spacing between protrusions while maintaining shear force sensing precision through the interlocked configuration.
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
Enables the accurate sensing of shear forces in multiple directions, enhancing the capability of user interfaces to recognize and respond to forces applied in different planes, thereby providing a more diverse and realistic input experience.
Implementation Method 1
a first force sensing layer on the first electrode; wherein the first protrusion and the second protrusion are not overlapped with each other or are partially overlapped with each other... enabling the detection of shear forces by varying resistance based on applied pressure
Data Source
Figure 1(a)~1(c)
Figure 2
Figure 3(a)~3(c)
AI summary
A force sensor including a first surface and a second surface facing each other in a first direction; a first protrusion protruded from the first surface toward the second surface; a first electrode on the first protrusion; a first force sensing layer on the first electrode; a second protrusion protruded from the second surface toward the first surface; and a second electrode on the second protrusion, wherein the first protrusion and the second protrusion are not overlapped with each other or are partially overlapped with each other.