Capacitive Sensor Fault Diagnosis via Time-Multiplexed Electrode Control
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Solution Overview
Problem
Conventional capacitive physical quality detection devices face challenges in efficiently performing fault diagnosis, as it often requires displacement of the movable electrode, and distinguishing between a disconnected signal path and zero input physical quantity is difficult, leading to prolonged diagnosis times and incorrect fault detection.
Innovation Solution
The capacitive physical quality detection device employs a control circuit that applies alternating signals to two fixed electrodes facing a movable electrode, allowing for capacitance measurement during normal operation and fault diagnosis without displacing the electrode, by differentiating between connected and disconnected states through differential capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault diagnosis is performed by displacing the movable electrode, then fault detection capability is improved, but diagnosis time is prolonged and acceleration detection is interfered with
Solution Approach 1:
The patent divides the fixed electrodes into multiple groups (first fixed electrode group and second fixed electrode group) positioned at different locations. By applying signals to different electrode groups at different times, the system can perform fault diagnosis on signal paths segment by segment without requiring movable electrode displacement, thereby reducing diagnosis time while maintaining detection capability.
Solution Approach 2:
The control circuit periodically alternates between applying first signals to the first fixed electrode group and second signals to the second fixed electrode group. This periodic switching enables time-multiplexed fault diagnosis, allowing the system to check different signal paths at different time intervals without continuous electrode displacement, thus reducing overall diagnosis time.
2Ease of operation
If conventional capacitive detection is used, then acceleration detection function is maintained, but distinction between disconnected signal path and zero input is difficult
Solution Approach 1:
The patent introduces a control circuit as an intermediary that actively manages signal application to different fixed electrode groups. This control circuit coordinates the timing and configuration of applied signals, enabling the system to differentiate between disconnected signal paths and zero input conditions by observing capacitance changes under controlled signal application, thereby improving fault distinction accuracy without affecting normal detection operation.
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 reduces fault diagnosis time and prevents interference with acceleration detection, enabling continuous operation by distinguishing between signal path integrity and zero input conditions, thus improving diagnostic efficiency and accuracy.
Implementation Method 1
electrostatic force generation means 104 displaces movable electrode 102
Implementation Method 2
capacitive detection means 105 detects the capacitance change between movable electrode 102 and fixed electrodes 103
Data Source
AI summary
A capacitive physical quality detection device includes a sensor part, a control circuit, and a CV conversion circuit. The sensor part includes a movable electrode, a first fixed electrode, and a second fixed electrode. The CV conversion circuit is configured to receive a reference voltage and to output a voltage corresponding to a capacitance change. In a first time period, the control circuit applies a first signal to the first fixed electrode, and applies a second signal, which is opposite in phase to the first signal, to the second fixed electrode. In a second time period, the control circuit applies the reference voltage to the first fixed electrode and applies the second signal to the second fixed electrode.