Capacitance Edge Positioning with Dynamic Gain
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Solution Overview
Problem
Conventional capacitance proximity/touch sensing systems face challenges in achieving linearity and accuracy at the edges of the sensing area, particularly when dealing with varying object shapes and sizes, leading to 'scalloping' responses and poor accuracy.
Innovation Solution
The system determines a final edge position by locking the object size to a previously determined value and dynamically varying metrics based on object size, using virtual sensor values that adjust according to finger size to improve accuracy and linearity at edge locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional curvature compensation methods are used, then edge positioning is improved, but linearity deteriorates due to scalloping responses
Solution Approach 1:
The patent applies dynamics by making the gain factor dynamic rather than static. The gain factor is adjusted based on the detected object size, allowing the system to adapt to varying finger sizes and maintain both accuracy and linearity at edge positions. This resolves the contradiction by enabling the system to respond flexibly to different touch conditions.
Solution Approach 2:
The patent changes the parameter of gain factor from a fixed value to a variable value that depends on object size. By adjusting the gain factor according to the detected finger size, the system can compensate for curvature effects while maintaining linear response characteristics, thus resolving the trade-off between positioning accuracy and linearity.
2Device complexity
If constant finger size determination is used, then processing is simplified, but accuracy deteriorates at edge locations
Solution Approach 1:
The patent applies local quality by determining object size locally at edge positions rather than using a constant global size. The system detects the actual finger size at the edge location and uses this local information to adjust the gain factor, improving accuracy without requiring complex processing throughout the entire sensing area.
Solution Approach 2:
The patent performs preliminary action by determining the object size before using it to adjust the gain factor for position calculation. This preliminary size detection enables the system to prepare appropriate compensation values in advance, improving accuracy while keeping the overall processing flow simple and structured.
3Device complexity
If uniform circular shapes are used for compensation, then calculation is simplified, but adaptability deteriorates for varying finger shapes
Solution Approach 1:
The patent applies self-service by having the system determine the actual finger size from the touch signal and use this self-measured size for compensation. Instead of relying on predetermined uniform circular shapes, the system adapts to the actual finger geometry detected during the touch event, maintaining simplicity while improving adaptability.
Solution Approach 2:
The patent changes the compensation parameter from a fixed uniform circular model to a variable model that adapts to detected finger sizes. By adjusting the gain factor based on the actual object size detected in the touch signal, the system maintains calculation simplicity while becoming adaptable to varying finger shapes and sizes.
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 provides more accurate and linear responses at edge locations, including corners, by stabilizing object size determinations and adjusting virtual sensor values for precise position calculations.
Implementation Method 1
capacitance proximity/touch sensing systems
Data Source
AI summary
A method can include determining an initial position of an object with respect to a sensing region formed by a plurality of sensors and having a core region bounded by at least one edge; if the initial position is proximate to the edge and a size of the object was previously calculated, determining a final edge position of the object using the previously calculated object size; and if the initial position is proximate to the edge and the size of the object was not previously calculated, determining a size of the object.