Force Sensor with Flexure Elements for Directional Detection
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Solution Overview
Problem
Existing force sensors in hand-held input devices, such as computer mice, face challenges in providing accurate directional movement detection without mechanical or optical contact with a surface, while also needing to withstand extended use and varying user tendencies, while maintaining a compact form factor and cost-effectiveness.
Innovation Solution
A force sensor design featuring two structural members with relative displacement allowed by flexure elements, incorporating capacitance sensors to detect displacement between these members, which provides signals representative of relative displacement, enabling directional movement detection within a compact and durable form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is designed to detect lateral force applied to the input device, then directional movement detection accuracy is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The force sensor assembly is segmented into multiple independent force sensing elements arranged in a bridge configuration. Each element detects force in a specific direction, and their combined output provides comprehensive directional movement detection. This segmentation allows the complex sensing function to be divided into simpler, manufacturable components while maintaining high measurement precision.
Solution Approach 2:
Multiple force sensing elements are merged into a single integrated sensor assembly that functions as one cohesive unit. The elements are positioned and connected to collectively detect lateral forces applied to the input device housing, providing accurate directional movement detection without requiring separate sensor assemblies for each axis.
2Volume of moving object
If the force sensor assembly is made compact to fit within hand-held device form factors, then ease of operation and portability are improved, but manufacturing precision and reliability may worsen
Solution Approach 1:
The force sensor assembly is designed with a nested structure where force sensing elements are positioned within the housing of the input device in a space-efficient arrangement. The elements are integrated into the existing device architecture, allowing the compact sensor assembly to fit within conventional hand-held device form factors while maintaining adequate spacing and alignment for manufacturing precision.
3Reliability
If the force sensor is designed to withstand extended use and varying user tendencies, then reliability and durability are improved, but device complexity and cost increase
Solution Approach 1:
The force sensing elements are designed with specific local properties optimized for their function - using materials and geometries that provide the necessary force sensitivity and durability. The bridge configuration provides structural support and protection to the sensing elements, allowing them to withstand extended use and varying user tendencies while maintaining a relatively simple overall construction.
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 enables accurate directional movement detection with minimal hysteresis and sensitivity, maintaining stability and cost-effectiveness, suitable for extended use and multiple user tendencies within a conventional input device form factor.
Implementation Method 1
incorporating capacitance sensors to detect displacement between these members
Implementation Method 2
two structural members with relative displacement allowed by flexure elements
Data Source
AI summary
The disclosure addresses a force sensor that is scalable in size and adaptable to a variety of form factors, including those suitable for use in an input device for a computer or other processing system, and in some cases including those of the configuration normally referred to as a computer mouse. The force sensor will include at least two structural members that are cooperatively attached one another as to be displaced from one another in response to a force acting upon one of the structural members. In some examples, the engagement between the two structural members will be specifically configured to allow such displacement in response to forces acting laterally on the force sensor. The force sensor will also include one or more sensing mechanisms to provide a measurement of the sensed deflection.