Polar Sensor Patterns for Radial Position Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional round touchpads face issues with accurately measuring both radial distance and angular position due to unequal sensor element lengths, leading to inconsistent capacitance measurements and sensitivity.
Innovation Solution
A polar sensor pattern featuring sensor elements arranged in spirals, both clockwise and counterclockwise, ensuring equal surface area, length, and sensitivity for each element, allowing for balanced and symmetrical capacitance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a truncated rectangular sensor grid is used in a round touchpad, then two-dimensional position measurement is enabled, but sensor elements have unequal lengths causing inconsistent capacitance measurements and sensitivity
Solution Approach 1:
The patent applies asymmetry by designing sensor elements with unequal lengths in a truncated rectangular grid configuration. This intentional asymmetry allows the sensor elements to fit within the circular boundary of the touchpad while maintaining uniform capacitance values through compensating design. The shorter sensor elements are positioned at the edges of the circular touchpad surface, creating an asymmetric layout that resolves the contradiction between achieving 2D position measurement and maintaining measurement consistency.
2Shape
If sensor elements of unequal length are used, then the touchpad can fit within a circular boundary, but background capacitance varies across different sensor elements
Solution Approach 1:
The patent applies local quality by making each sensor element unique in its length and position within the circular boundary. Each sensor element is locally optimized to have equal capacitance value despite having different lengths. The shorter sensor elements at the circular edges are designed with specific dimensions to compensate for their reduced area, ensuring that local variations in geometry do not result in variations in electrical properties.
3Ease of operation
If a rectangular sensor grid is truncated to fit a circular touchpad, then the touchpad achieves a compact circular form factor, but some sensor elements become shorter and less sensitive
Solution Approach 1:
The patent applies parameter changes by systematically varying the length and width parameters of individual sensor elements to maintain uniform capacitance values. Instead of using uniform sensor elements, the design changes the geometric parameters locally to compensate for position-dependent effects. This allows the touchpad to achieve a compact circular form factor while maintaining reliable and consistent sensor response across all elements.
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 design enables accurate two-dimensional position sensing, providing consistent sensitivity across all sensor elements and effectively overcoming the limitations of conventional touchpads by allowing for precise radial and angular position detection.
Implementation Method 1
When a user's finger (or some other type of object) is placed on the sensing surface, a capacitance is induced in the sensor elements.
Data Source
AI summary
Patterns of sensor elements that can be used in capacitance sensing devices are described. A plurality of sensor elements extends in a radial direction from a shared center. A first subset of the sensor elements extend like spirals in a clockwise direction, and a second subset of the sensor elements extend like spirals in a counterclockwise direction.