Capacitance Reference Updating for Fast, Low-Jitter Proximity Detection
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Solution Overview
Problem
Existing capacitance detection systems face challenges in accurately updating reference signals in real time, leading to noise jitter and delayed responses due to ambient temperature and noise interference, which can result in misrecognition or missed recognition of human body or conductor approaches/movements.
Innovation Solution
A method for updating capacitance references by determining feature values based on raw capacitance data and using threshold comparisons to adjust reference values, reducing noise impact and enabling real-time tracking of capacitance variations, including specific threshold-based calculations for different stages of conductor approach and departure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If first-order hysteresis filtering is used to update the reference signal, then the reference signal becomes smoother, but the response delay increases
Solution Approach 1:
The patent applies dynamics by making the reference signal updating strategy adaptive rather than static. The system dynamically adjusts between different updating approaches (first-order hysteresis filtering versus direct raw data assignment) based on real-time detection of conductor presence/absence states, allowing the reference signal to be smooth during stable periods but responsive during state transitions.
Solution Approach 2:
The patent changes the parameter of reference signal updating methodology based on system state. When no conductor is detected, the system uses direct assignment of raw capacitance data as reference (fast response). When a conductor is detected, the system switches to first-order hysteresis filtering (smooth signal). This parameter change resolves the contradiction by applying the appropriate smoothing level contextually.
2Speed
If the reference signal is updated in real time to reduce delayed response, then the response speed improves, but noise jitter increases
Solution Approach 1:
The patent applies local quality by applying different processing qualities to different portions of the reference signal based on conductor state. During conductor absence, the reference is updated with high responsiveness (low smoothing). During conductor presence, the reference is updated with high smoothing to reduce noise. This local differentiation of quality resolves the speed-stability contradiction.
Solution Approach 2:
The system changes the updating parameter (filtering intensity) based on the detected state. When conductors are absent, the updating parameter favors speed (direct assignment). When conductors are present, the updating parameter favors stability (hysteresis filtering). This dynamic parameter adjustment resolves the contradiction between response speed and noise reduction.
3Stability of the object's composition
If the filter coefficient Coefx is increased to reduce noise, then the noise jitter decreases, but the delayed response increases
Solution Approach 1:
The patent makes the filter coefficient application dynamic rather than constant. The system dynamically selects whether to apply first-order hysteresis filtering (with its associated delay) or direct raw data assignment (with no filtering delay) based on the conductor detection state. This dynamic approach resolves the contradiction by applying noise reduction only when necessary.
Solution Approach 2:
The patent segments the reference signal updating process into two distinct modes: one for conductor absence (fast updating without heavy filtering) and one for conductor presence (smoother updating with hysteresis filtering). This segmentation allows the system to avoid the trade-off in most conditions by using the appropriate mode for the current state.
4Stability of the object's composition
If the reference signal is not updated to maintain stability, then the noise jitter is reduced, but the misrecognition rate increases
Solution Approach 1:
The patent changes the reference signal updating parameter based on conductor state detection. When conductors are absent, the system maintains stable reference signaling. When conductors are present or transitioning, the system updates the reference signal appropriately to maintain detection accuracy. This contextual parameter adjustment resolves the stability-accuracy contradiction.
Solution Approach 2:
The system uses feedback from the capacitance detection process to determine when reference signal updates are necessary. By monitoring the raw capacitance data and comparing it against the reference, the system can detect state changes and trigger appropriate reference updates, ensuring both stability during normal operation and accuracy during transitions.
Data Source
AI summary
Embodiments of the present disclosure provide a method for updating a capacitance reference, which includes: determining, based on an n-th frame of raw capacitance data and an (n−M)-th frame of raw capacitance data outputted from the capacitance detection apparatus, a feature value corresponding to the n-th frame of raw capacitance data; computing a difference value between the n-th frame of raw capacitance data and a reference value corresponding to an (n−1)-th frame of raw capacitance data outputted from the capacitance detection apparatus, to obtain a capacitance variation; and determining, when the feature value corresponding to the n-th frame of raw capacitance data is less than a first threshold Thr1, and the capacitance variation is less than a proximity threshold Thron, the n-th frame of raw capacitance data or the (n−1)-th frame of raw capacitance data as a reference value corresponding to the n-th frame of raw capacitance data.