Capacitive Proximity Circuit With Reference Electrode Validation
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Solution Overview
Problem
Capacitive proximity sensors in electronic devices suffer from false judgments due to the influence of ambient factors such as temperature and humidity, leading to inaccurate detection of human proximity.
Innovation Solution
A proximity detection method and circuit that generates a proximity signal based on detection data, baseline data, and proximity thresholds, and judges signal validity using reference data and valid thresholds to reduce false judgments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive proximity sensors are used to detect human proximity, then the detection function is achieved, but false judgment occurs due to ambient factors such as temperature and humidity
Solution Approach 1:
The patent introduces a reference electrode as an intermediary element that experiences the same ambient conditions as the sensing electrode but does not detect human proximity. By comparing the capacitance values from both electrodes, the system can isolate and eliminate the portion of capacitance change caused by ambient factors, thereby improving detection reliability without sacrificing the original detection function
Solution Approach 2:
The system continuously monitors the capacitance values from both sensing and reference electrodes, compares them in real-time, and uses this feedback to determine whether a detected change is due to human proximity or ambient factors. This feedback mechanism enables dynamic adjustment and validation of detection results, reducing false judgments caused by temperature and humidity variations
2Measurement precision
If the sensing electrode capacitance is monitored continuously, then proximity detection is achieved, but ambient factors cause false judgments
Solution Approach 1:
A reference electrode is introduced as a mediator that experiences identical ambient conditions (temperature, humidity) but does not interact with human bodies. By comparing the capacitance changes between the sensing electrode and reference electrode, the system can precisely measure the portion of change attributable to human proximity while filtering out ambient factor influences, thereby improving both measurement precision and judgment accuracy
Solution Approach 2:
The patent converts the harmful effect of ambient factors into a beneficial comparison mechanism. By placing a reference electrode in the same ambient environment, the system uses the ambient-induced capacitance changes as a reference signal that can be subtracted from the sensing electrode readings, transforming the previously harmful ambient influence into a useful calibration reference
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
Effectively reduces the occurrence of false judgments by accurately determining the proximity of a human body to an electronic device, despite ambient factor fluctuations.
Implementation Method 1
The electronic device includes a sensing electrode, which is equivalent to a capacitor. The equivalent capacitance of the sensing electrode will be influenced and changed by human bodies and objects.
Implementation Method 2
By sensing the variation of the equivalent capacitance of the sensing electrode, whether a human body or an object is proximate to the electronic device may be detected by the proximity sensor.
Data Source
AI summary
The present application provides a proximity detection method and circuit thereof. The circuit includes a detection circuit, a baseline generating circuit, and a proximity sensing circuit. The proximity sensing circuit generates a proximity signal according to a detection data generated by the detection circuit, a baseline data generated by the baseline generating circuit and a proximity threshold, and judges whether the proximity signal is valid according to the detection data, a reference data, and a valid threshold. The validity of the proximity signal may be judged according to the reference data and the valid threshold and thus avoiding false judgement caused by the influences of the ambient factors.