Touch Orientation Calculation Using Ellipse Fitting on Capacitive Arrays

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Solution Overview

Problem

Conventional capacitance-sensing systems struggle to accurately calculate touch orientations beyond 0° and 90°, and fail to report aspect ratios, limiting their capability in gesture recognition and other applications.

Innovation Solution

A method and device for determining touch orientation on a capacitive sense array by calculating the major axis length, centroid position, and aspect ratio, using techniques such as ellipse fitting and eigenvalues/eigenvectors to compute touch orientation, aspect ratio, and report these values for advanced gesture recognition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional capacitance-sensing systems are used to detect touch events, then basic touch detection is achieved, but accurate calculation of touch orientations beyond 0° and 90° and aspect ratios cannot be performed

Engineering Contradiction:

Improvetouch orientation calculation accuracyVSAvoidgesture recognition capability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent transforms the touch event data from simple capacitance values into geometric parameters by fitting an ellipse model to the touch coordinates. This parameter transformation enables the system to extract orientation angles and aspect ratios that were previously inaccessible, directly resolving the limitation of conventional systems that could only detect basic touch presence.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces ellipse fitting as an intermediary mathematical model between the raw capacitance data and the desired touch orientation parameters. By using the ellipse geometry as a mediator, the system can accurately represent arbitrary touch orientations and shapes, enabling advanced gesture recognition while maintaining compatibility with existing capacitance-sensing hardware.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If advanced touch orientation calculation methods are implemented, then accurate gesture recognition is enabled, but computational resources increase

Engineering Contradiction:

Improvetouch orientation and aspect ratio accuracyVSAvoidcomputational energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the computational task into distinct phases: data collection from the sense array, ellipse parameter fitting, and orientation calculation. This segmentation allows the system to perform computations efficiently by processing only the necessary touch coordinates through the ellipse model, reducing overall computational energy consumption compared to full image processing methods.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces complex image processing mechanical systems with a streamlined mathematical approach using ellipse fitting. By substituting heavy computational image analysis with elegant geometric parameter extraction, the system achieves accurate touch orientation and aspect ratio calculation with significantly reduced computational energy requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If conventional touch sensing is used, then system simplicity is maintained, but touch orientation and aspect ratio information is lost

Engineering Contradiction:

Improvesensing system complexityVSAvoidtouch orientation and aspect ratio data

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent makes the existing capacitance-sensing system multi-functional by adding ellipse fitting capability. The same hardware that detects basic touch events now also provides orientation and aspect ratio information through mathematical processing, eliminating the need for additional specialized sensors and maintaining system simplicity while preventing information loss.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent performs preliminary mathematical processing of the touch coordinates by fitting an ellipse model before the data is used for gesture recognition. This preliminary action extracts all necessary geometric information (orientation, aspect ratio, center position) in advance, ensuring no touch-related information is lost while keeping the sensing hardware simple.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9965090B2Determination of touch orientation in a touch event

Publication Date: 2018.05.08 PARADE TECHNOLOGIES LTD

AI summary

A process determines touch orientation of touches on a sense array of a touch-sensing device. The process obtains first touch data and second touch data of a conductive object proximate to the sense array at two temporally proximate times. The first and second touch data are then used to determine a first touch orientation, and the second touch data is used to determine a touch area and a provisional touch orientation. A touch orientation change is then determined as an absolute difference between the first touch orientation and the provisional touch orientation. The touch orientation change is compared with a threshold change, and the touch area is compared with a threshold area. In accordance with comparison results, the first touch orientation, the provisional orientation, or a weighted combination of them is designated as a second touch orientation corresponding to one of the two temporally proximate times.