Capacitive Sensor Air Swipe Detection via Dynamic Baseline
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Capacitive sensing devices are limited in detecting input objects that are not at or near the surface, leading to reduced flexibility and usability due to low signal-to-noise ratios and reliance on static baseline capacitance.
Innovation Solution
A processing system employing differential detection methods with filtering techniques and a sliding window of object position estimates to discriminate between valid and invalid air swipes, using a dynamic baseline capacitance value for improved positional information extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional baseline capacitance methods are used for detecting objects away from the surface, then the device structure remains simple, but detection accuracy and signal-to-noise ratio deteriorate
Solution Approach 1:
The patent applies dynamics by transitioning from static baseline capacitance to dynamic baseline capacitance that adapts to changing environmental conditions. The system continuously updates the baseline capacitance value based on recent measurements, allowing the detection threshold to dynamically adjust to ambient noise levels and environmental variations, thereby maintaining high detection accuracy for objects away from the surface.
Solution Approach 2:
The patent introduces an intermediary processing layer that includes filtering mechanisms and differential detection algorithms. This intermediary layer processes the raw capacitance signals between the sensor electrodes and the final detection output, using bandpass filters and differential comparisons to enhance the signal-to-noise ratio and accurately detect objects at distances greater than traditional capacitive sensors can handle.
2Adaptability or versatility
If the sensing region is extended to detect objects away from the surface, then detection capability is improved, but false positive and false negative rates increase due to low signal-to-noise ratio
Solution Approach 1:
The patent applies preliminary action by performing baseline capacitance measurement and filtering operations before actual object detection. The system pre-establishes the environmental baseline and applies filtering algorithms in advance to remove noise components, so that when an object is detected, the comparison is made against a already-optimized reference, reducing false positives and negatives.
Solution Approach 2:
The patent implements feedback mechanisms where detection results and signal characteristics are continuously fed back to adjust the baseline capacitance and filtering parameters. The system monitors the signal-to-noise ratio and dynamically adjusts detection thresholds based on recent measurement history, improving reliability by adapting to changing conditions in real-time.
3Measurement precision
If differential detection with filtering techniques is employed, then positional information accuracy is improved, but processing time and computational load increase
Solution Approach 1:
The patent applies partial action by implementing selective filtering that processes only the relevant frequency bands and signal components necessary for object detection. Rather than applying comprehensive filtering to all signal aspects, the system focuses computational resources on the specific frequency ranges where object-induced capacitance changes occur, maintaining accuracy while reducing unnecessary processing time.
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
Enables reliable detection of positional information for objects both at and away from the surface, enhancing user interface flexibility and accuracy by avoiding inaccuracies associated with traditional baseline capacitance methods.
Implementation Method 1
a sensor electrode array positioned beneath the surface and configured to capacitive sense input objects in the sensing region
Data Source
AI summary
Methods, systems and devices are described for determining positional information for objects using an input device. The various embodiments provide improved user interface functionality by facilitating user input with input objects that are at the surface and objects that are away from the surface. The input device includes a processing system and an array of sensor electrodes adapted to capacitively sense objects in a sensing region. The processing system is configured to determine first positional information for an input object in a first portion of the sensing region based on a difference between a first frame of the first plurality of frames and a filtered frame even when the input object is determined to be in the sensing region when the first plurality of frames are acquired, wherein the filtered frame is based on one or more of the first plurality of frames.