Capacitive Force Sensor for Touch Location and Magnitude Detection
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Solution Overview
Problem
Current touch devices can only detect the location of a touch but not the force applied, limiting user interaction to binary inputs and lacking the ability to differentiate between varying force levels, which is advantageous for applications like virtual reality, augmented reality, and simulated interactions.
Innovation Solution
A capacitive force sensor integrated with touch devices, utilizing a compressible element and capacitive plates to measure displacement and determine the magnitude and location of applied force, allowing for the detection of force vectors and centroids, enabling multiple levels of input based on force variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional touch sensors are used to detect touch location, then the device can identify touch position, but it cannot detect the force or magnitude of the touch
Solution Approach 1:
The patent combines the touch location detection function and force detection function into a single integrated sensor structure. The same capacitive sensing elements that detect touch position also measure force magnitude by detecting changes in capacitance caused by displacement of the touch-sensitive surface, eliminating the need for separate force sensing components.
Solution Approach 2:
The touch sensor is designed to perform multiple functions simultaneously: it detects both the location of touches and the force applied. By measuring capacitance changes that result from surface displacement, the sensor provides both positional information and force magnitude information from the same structural elements.
2Adaptability or versatility
If only touch location is detected, then the device structure remains simple, but user interaction is limited to binary inputs without force differentiation
Solution Approach 1:
The patent replaces traditional mechanical force sensing mechanisms with an electrical field-based capacitive sensing system. Instead of using mechanical springs, levers, or pressure-sensitive materials, the system uses changes in electrical capacitance caused by displacement of the touch-sensitive surface to infer force magnitude, enabling more precise and versatile measurement.
3Measurement precision
If capacitive sensing is used to measure force, then force magnitude can be detected, but the device requires additional capacitive plates and compressible elements
Solution Approach 1:
The capacitive sensing system is divided into multiple discrete sensing zones or electrodes arranged in patterns across the touch surface. This segmentation allows the system to detect both the position of touches (by determining which segments are activated) and the force magnitude (by measuring the degree of capacitance change in each segment), providing comprehensive information from modular components.
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 users to provide nuanced input by varying the force of touch, enhancing interaction capabilities in applications such as virtual reality and augmented reality by accurately measuring and interpreting force applied to touch devices.
Implementation Method 1
the capacitive sensor can be used to measure the displacement of the touch-sensitive surface and thereby determine a force applied to the touch-sensitive surface
Implementation Method 2
In one example, the touch device includes a capacitive force sensor that includes a compressible element and capacitive plates
Data Source
AI summary
A device configured to determine the location and magnitude of a touch on a surface of the device. The device includes a transparent touch sensor that is configured to detect a location of a touch on the transparent touch sensor. The device also includes a force-sensing structure disposed at the periphery of the transparent touch sensor. The force sensor includes an upper capacitive plate and a compressible element disposed on one side of the upper capacitive plate. The force sensor also includes a lower capacitive plate disposed on a side of the compressible element that is opposite the upper capacitive plate.