Capacitance Reference Line Updating for Low-Jitter Event Detection
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Solution Overview
Problem
Existing capacitance detection systems face challenges in accurately updating the capacitance reference value in real time, leading to noise jitter and delayed responses, which can result in misrecognition or missed recognition of events such as human approach or movement.
Innovation Solution
A method for updating the capacitance reference value that involves determining a feature value from raw capacitance data and using threshold-based conditions to select appropriate reference values, thereby reducing noise jitter and delayed responses.
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 smoothness of the reference signal is improved, but delayed response increases
Solution Approach 1:
The patent implements dynamic reference signal updating by switching between different updating modes (normal updating and freezing) based on detected event states. The system dynamically adjusts the updating behavior of the reference signal according to whether an event is detected, allowing fast response during events while maintaining smoothness during normal operation.
Solution Approach 2:
The patent changes the updating parameter (filter coefficient or updating frequency) dynamically based on the operational state. During event detection, the system uses a different updating strategy compared to normal operation, effectively changing the parameter to optimize both response speed and smoothness for different conditions.
2Measurement precision
If first-order hysteresis filtering is used to update the reference signal, then noise jitter is reduced, but delayed response increases
Solution Approach 1:
The system dynamically switches between normal reference updating and reference freezing based on event detection state. During events, the reference signal is frozen or updated minimally to avoid noise contamination, while maintaining fast response. During normal operation, normal updating provides noise reduction through filtering.
Solution Approach 2:
The patent extracts and separates the event detection function from the reference updating process. By detecting events first and then conditionally updating the reference signal based on event state, the system removes the harmful interaction where noise during events contaminates the reference signal, achieving both noise reduction and fast response.
3Measurement precision
If the reference signal is not updated in real time, then noise interference is reduced, but misrecognition or missed recognition of events occurs
Solution Approach 1:
The system uses feedback from event detection results to control reference signal updating. The detected event state (whether an event is occurring) feeds back to the reference updating mechanism, which then adjusts its behavior accordingly - freezing during events to prevent misrecognition, and updating normally during non-events to maintain noise reduction.
Solution Approach 2:
The patent performs preliminary event detection before updating the reference signal. By detecting whether an event is occurring first, the system can preliminarily determine the appropriate updating strategy, preventing misrecognition by avoiding reference updates during events before the actual measurement occurs.
Data Source
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AI summary
Embodiments of the present disclosure provide a method for updating a capacitance reference, a chip, and a capacitance detection apparatus. The method is applied to the capacitance detection apparatus, and 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. The method and apparatus provided in the embodiments of the present disclosure can effectively update the capacitance reference value in real time.