Capacitance Sensor Proximity Correction Using Radial Distance
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Solution Overview
Problem
Capacitance sensors in touchpads struggle to accurately detect the proximity of objects due to inconsistencies in proximity value sensitivity caused by non-planar surfaces and varying distances between the sensor and the touch surface, leading to misinterpretation of touch and hover inputs.
Innovation Solution
A system that includes a capacitance sensor, an overlay with a touch surface, and a controller that determines the planar radial distance of an object from a predetermined location on the touch surface, adjusting the proximity value using offset coefficients based on this distance and optionally the object's angular position, to differentiate between touch and hover states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance sensor is used to detect object proximity, then touch and hover inputs can be detected, but proximity value sensitivity becomes inconsistent due to non-planar surfaces and varying distances
Solution Approach 1:
The patent applies local quality by determining the planar radial distance of the object from a predetermined location on the touch surface and using this distance to adjust the proximity value. Different regions of the touch surface have different proximity value sensitivities, so the system compensates by applying location-specific corrections to maintain consistent proximity detection across the entire surface.
Solution Approach 2:
The patent changes the proximity value parameter based on the planar radial distance of the object. By modifying the proximity value according to the object's position on the touch surface, the system compensates for variations in capacitance response caused by non-planar surfaces and varying distances, thereby improving measurement precision while maintaining reliability.
2Reliability
If proximity values are adjusted based on planar radial distance, then proximity value sensitivity is stabilized, but processing complexity increases
Solution Approach 1:
The patent segments the touch surface into regions based on planar radial distance from a predetermined location. By dividing the surface into concentric zones, the system can apply different proximity value adjustments to different regions, stabilizing sensitivity while keeping the processing logic structured and manageable through spatial segmentation.
Solution Approach 2:
The patent introduces a new dimension of processing by calculating the planar radial distance from the object's position on the touch surface. This additional dimensional information (radial distance) is used to adjust proximity values, transforming a one-dimensional proximity detection into a two-dimensional corrected proximity measurement, which stabilizes sensitivity without requiring complex three-dimensional modeling.
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 enhances the accuracy of input detection by stabilizing proximity values regardless of angular direction, reducing processing complexity and improving user input interpretation.
Implementation Method 1
Touchpads may operate using capacitive sensing, a technology that senses the change of capacitance where a finger touches the pad.
Implementation Method 2
Styluses or other types of electrically conductive objects may also be detectable with capacitance sensing.
Data Source
AI summary
A device may include a capacitance sensor; an overlay positioned near the capacitance sensor, the overlay including a touch surface opposite to an underside of the overlay, where the underside is positioned near the capacitance sensor; a controller; memory in communication with the controller and including programmed instructions that, when executed, cause the controller to detect a proximity value of an object with a capacitance sensor, where a touch surface is located between the capacitance sensor and the object; determine a planar radial distance of the object away from a predetermined location on the touch surface; and change the proximity value based, at least in part, on the planar radial distance.