Frequency Modulated Interference Detection for Capacitive Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing display devices face challenges in detecting interfering signals that affect capacitive sensing measurements, as conventional interference detection methods may fail to identify such signals due to phase alignment issues between interference and sensor bursts.
Innovation Solution
The system employs a processing system with sensor module circuitry that operates in both capacitive sensing and interference detection modes, using multiple interference bursts with different frequencies to detect interfering signals by adjusting the phase offset between sensing and interference bursts, ensuring accurate detection even if one burst is aligned with the interfering signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If interference detection is performed using a single frequency burst, then the detection process is simple and fast, but the detection accuracy deteriorates due to phase alignment issues with interfering signals
Solution Approach 1:
The interference detection process is segmented into multiple independent frequency bursts instead of using a single burst. Each burst operates at a different frequency, allowing the system to detect interfering signals by comparing results across multiple frequency segments. This segmentation resolves the phase alignment issue by ensuring that no single interfering signal can align with all bursts simultaneously.
Solution Approach 2:
The system employs periodic interference bursts at different frequencies sequentially. By alternating between multiple frequency bursts in a periodic manner, the system maintains simplicity while improving detection accuracy. The periodic nature allows for systematic comparison of detection results across different frequencies to identify interfering signals.
2Measurement precision
If multiple interference bursts with different frequencies are used, then the interference detection accuracy improves, but the time required for detection increases
Solution Approach 1:
The system performs preliminary interference detection using multiple frequency bursts before conducting capacitive sensing measurements. By completing the interference detection phase in advance with different frequency bursts, the system identifies and flags interfering signals, allowing subsequent sensing operations to avoid contaminated time periods. This preliminary action prevents time loss during actual sensing operations.
Solution Approach 2:
The system dynamically adjusts the timing and frequency of interference bursts based on operational conditions. By making the detection process adaptive rather than static, the system can optimize the balance between detection accuracy and time consumption, performing more frequent or detailed bursts only when necessary.
3Ease of operation
If interference bursts are phase-aligned with sensor bursts, then the detection process is synchronized and simple, but interfering signals may go undetected due to constructive interference
Solution Approach 1:
The system intentionally creates asymmetry in the phase relationships between interference bursts and sensor bursts. Instead of maintaining uniform phase alignment, different interference bursts are deliberately offset by different phases. This asymmetric approach ensures that interfering signals cannot constructively align with all bursts simultaneously, improving detection reliability while maintaining operational simplicity through systematic phase management.
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 effectively reduces the likelihood of failing to detect interfering signals, allowing for precise capacitive sensing by altering the frequency of interference bursts to align differently with the interfering signal, thereby enhancing the accuracy of input device measurements.
Implementation Method 1
The sensor module circuitry is configured to operate, during a first time period, the plurality of sensor electrodes in a capacitive sensing mode to perform capacitive sensing
Implementation Method 2
operate, during a second time period, the plurality of sensor electrodes in an interference detection mode to detect interfering signals using at least first and second interference bursts where a frequency of the first interference burst is different than a frequency of the second interference burst
Data Source
AI summary
This disclosure generally provides embodiments to reduce the likelihood that an input device fails to detect an interfering signal when performing interference detection using interference bursts that are phase offset from sensor bursts used to perform capacitive sensing. In one embodiment, the input device adjusts the frequency of the interference bursts instead of using interference bursts with the same frequency. Doing so adjusts the phases of the interference bursts relative to each other such that even if one of the interference bursts is aligned with the interfering signal in a manner that the signal is not detected, an interference burst with a different frequency has a different alignment relative to the interfering signal. The measurements acquired by the differently aligned interference burst can be used to detect the presence of the interfering signal.