Capacitive Sensor Position Error Compensation via Velocity Analysis
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Solution Overview
Problem
Capacitive touch input devices experience position errors due to the difference between calculated and actual positions of conductive objects, such as stylus tips, which affects the accuracy and precision of user input, particularly with smaller stylus diameters and larger sensor elements, leading to poor user experience and functionality limitations.
Innovation Solution
The method involves calculating position error by determining the difference between the average velocity of a conductive object over multiple positions and its velocity at a specific calculated position, using a centroid algorithm and periodic function to estimate and adjust for position errors, allowing for accurate positioning without external measurement tools like Cartesian robots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If capacitive sensor elements are made larger to reduce manufacturing complexity, then manufacturing precision is improved, but position measurement precision deteriorates due to increased position error between calculated and actual positions
Solution Approach 1:
The patent applies preliminary action by pre-determining position error values through velocity-based calculations before actual position measurement is needed. The system calculates position errors using velocity differences obtained from sequential position measurements, stores these error values, and then applies them to correct subsequent position measurements, thereby compensating for the inherent inaccuracies of larger sensor elements.
Solution Approach 2:
The patent implements feedback by using measured position data to calculate velocity, then using velocity differences to determine position errors, which are subsequently applied to correct position measurements. This closed-loop feedback mechanism continuously refines position accuracy by compensating for systematic errors introduced by larger sensor element dimensions.
2Measurement precision
If traditional position error determination methods like Cartesian robots are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling the capacitive sensing system to determine its own position errors using only its existing position measurement capabilities. The system uses its built-in centroid algorithm and sequential measurement functionality to calculate velocity, determine position errors, and apply corrections, eliminating the need for external measurement tools like Cartesian robots entirely.
Solution Approach 2:
The patent replaces the mechanical measurement system (Cartesian robot) with an electrical/computational approach. Instead of using physical mechanical tools to measure and map sensor positions, the system uses electrical signal measurements, mathematical calculations (velocity derivation from sequential positions), and computational error compensation to achieve the same goal of determining and correcting position errors.
3Adaptability or versatility
If velocity-based position error determination is implemented, then adaptability to various stylus diameters is improved, but calculation complexity increases
Solution Approach 1:
The patent applies parameter changes by using velocity as an intermediate parameter to determine position error. Instead of directly measuring or calculating position error from geometric relationships (which would be sensitive to stylus diameter variations), the system changes the approach to using temporal parameter (velocity derived from sequential position measurements), making the error determination adaptable to different stylus diameters without requiring recalibration.
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 approach enables quick, cost-effective, and versatile determination of position errors in capacitive sensing systems, improving accuracy and user experience by minimizing storage requirements and adapting to various stylus diameters, thus enhancing the precision of touch input devices.
Implementation Method 1
Capacitive sensing typically involves measuring a change in capacitance associated with the capacitive sensor elements to determine a presence or position of a conductive object relative to a touch input device.
Data Source
AI summary
A method and apparatus receive a plurality of signals that are used to calculate a position of a conductive object relative to a capacitive sensor element and determine an estimated position error through the plurality of signals, the estimated position error to offset a position error of the calculated position.