Capacitive Touch Sensor with Force Detection
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Solution Overview
Problem
Current touch sensors can only determine the location of a touch on a surface and lack the capability to sense the force applied, limiting their functionality in providing additional control options and recognizing complex gestures.
Innovation Solution
A capacitive touch sensor system incorporating a substrate with conductive electrode rows and columns, combined with force sensors at each corner, which measures changes in capacitance to detect both touch location and force, enabling three-dimensional gesturing and enhanced gesture recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional capacitive touch sensors are used, then touch location detection is achieved, but force detection capability is lost
Solution Approach 1:
The patent combines traditional capacitive touch sensors with force sensors (such as piezoresistive or piezoelectric sensors) into a single integrated sensing system. The capacitive sensors detect touch location through changes in capacitance, while the force sensors simultaneously measure applied pressure. This merging of different sensing mechanisms allows the system to achieve both precise touch location detection and force detection capability without compromising either function.
2Adaptability or versatility
If force sensors are added to the substrate, then force detection capability is improved, but device complexity increases
Solution Approach 1:
The patent designs the substrate to serve multiple functions: it acts as both the structural support for the touch sensor and the sensing element for force detection. Force sensors are integrated at the corners of the substrate, allowing the same structural component to perform both mechanical support and force sensing functions. This multi-functionality approach reduces overall device complexity by eliminating separate structural and sensing components.
Solution Approach 2:
The force sensing capability is segmented into discrete force sensors positioned at specific locations (corners) of the substrate rather than distributing sensing elements across the entire surface. This segmentation allows for simplified sensor placement and signal processing, as each corner sensor independently measures force components, making the overall system easier to implement and process compared to a fully distributed sensing array.
3Adaptability or versatility
If multiple sensors are used for both touch and force detection, then sensing capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the touch sensing and force sensing functions into a single integrated sensor assembly where capacitive sensors and force sensors work together. This combination allows for shared manufacturing processes, common substrate materials, and unified signal processing circuits, thereby reducing overall manufacturing costs compared to using completely separate touch sensor and force sensor systems that would require independent assembly and calibration.
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
This solution allows for the determination of individual touch forces and pressure biases, increasing the bandwidth and complexity of gesture commands on touch screens without affecting visual clarity, enabling more sophisticated interactions with two-dimensional touch interfaces.
Implementation Method 1
the capacitance value will change of a capacitor formed by an intersection of an electrode row and column proximate to the location of the touch
Implementation Method 2
a force or pressure sensor at each corner of the substrate
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A force sensing touch sensor comprises a substrate having a plurality of conductive electrode rows and a plurality of conductive electrode columns substantially perpendicular to and over the plurality of conductive electrode rows on a surface of the substrate, and a force sensor at each corner of the substrate. When a touch is applied to the surface of the touch sensor, the capacitance value will change of a capacitor formed by an intersection of an electrode row and column proximate to the location of the touch to the surface of the touch sensor. These force sensors detect total and proportional force on the touch sensor substrate. This force information is then combined with the touch location(s) previously determined, and the individual touch force(s) can then be interpolated with sufficient resolution for three dimensional (3D) gesturing applications.