Multi-Axis Force Sensing Stylus for Accurate Input
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Solution Overview
Problem
Typical styli lack multi-axis force sensing capabilities, leading to inaccurate input measurements when held at angles other than perpendicular to the input surface, limiting the variety and accuracy of inputs provided to electronic devices.
Innovation Solution
A stylus equipped with a force sensor, such as a strain gauge, that senses force in three dimensions, allowing for axial and radial vector measurement, which compensates for uneven force vectors to provide uniform input and enhance sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-axis force sensing is used in the stylus, then the device complexity is reduced, but the measurement precision deteriorates when the stylus is held at angles other than perpendicular to the input surface
Solution Approach 1:
The patent transitions from single-axis force sensing to multi-axis (three-dimensional) force sensing by incorporating multiple strain gauges arranged in different orientations. This allows the stylus to measure force components along multiple axes simultaneously, resolving the measurement accuracy issue when the stylus is held at various angles to the input surface.
Solution Approach 2:
The force sensing capability is divided into multiple independent strain gauge elements, each sensitive to force in specific directions. By segmenting the sensing function across multiple axes, the system can accurately capture the full three-dimensional force vector applied by the user, regardless of stylus orientation.
2Measurement precision
If multi-axis force sensing is implemented, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Multiple strain gauge elements are integrated into a single stylus structure, combining their individual force sensing capabilities into a unified multi-axis sensing system. The strain gauges are arranged in specific configurations (such as Wheatstone bridge arrangements) that enable simultaneous measurement of force components along multiple axes while maintaining a compact design.
3Ease of manufacture
If single-component force sensing is used, then the ease of manufacture is improved, but the adaptability deteriorates in terms of the number and variety of inputs provided
Solution Approach 1:
The multi-axis force sensing capability enables the stylus to perform multiple input functions beyond simple touch detection. By measuring force vectors in three dimensions, the system can distinguish between different user intentions (such as pressing hardness, drawing pressure, or activation gestures), providing diverse input types and enhancing the versatility of the electronic device interface.
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 accurate and uniform input on touch-sensitive surfaces by measuring three-dimensional force vectors, reducing measurement errors and improving the quality of lines drawn, and can be used to control device functions like turning the device on/off.
Implementation Method 1
One embodiment utilizes a strain gauge in a stylus to sense force exerted by a user using a stylus in both axial and radial vectors
Data Source
AI summary
Embodiments disclosed herein relate generally to a stylus for use with a portable electronic device. The stylus includes a force sensing device to measure three dimensional force components exerted by the stylus on the portable electronic device. The output of the portable electronic device is adjusted based upon the force components.