Capacitive Operation Electrode Grounding for Wire Breakage Detection
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Solution Overview
Problem
Capacitance-type operation detectors fail to detect user operations when wire breakage occurs between the sensor electrode and the controller, as the distinct wires for the sensor and cancel electrodes make it impossible to differentiate between user operations and wire faults.
Innovation Solution
A detector system that applies voltage to a first electrode and a second electrode, using a switch unit to forcibly connect the second electrode to ground, allowing the determination unit to differentiate between user operations and wire breakage by analyzing changes in the detection signal before and after grounding, thereby detecting wire breakage in both electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate wires are used to connect the controller to the sensor electrode and cancel electrode, then the capacitance detection function is improved, but wire breakage detection capability deteriorates
Solution Approach 1:
The system performs preliminary actions by periodically connecting the sensor electrode to ground before normal detection, and preliminarily identifying wire breakage conditions. This preliminary grounding action creates a known reference state that enables subsequent detection of wire integrity without affecting normal capacitance measurement operations.
Solution Approach 2:
The sensor electrode serves dual purposes: it functions as both the detection electrode for capacitance measurement and as the object to be grounded during wire breakage detection. The same electrode that detects user operations is also used to detect wire integrity, eliminating the need for separate test electrodes or additional components.
2Device complexity
If the second electrode is kept at floating potential during detection, then capacitance measurement is simplified, but wire breakage in the second electrode cannot be detected
Solution Approach 1:
The system performs preliminary grounding of the second electrode to identify wire breakage before normal operation. By temporarily connecting the second electrode to ground and monitoring the response, the system can detect wire integrity issues without complicating the ongoing capacitance measurement process.
Solution Approach 2:
The grounding and identification operations are performed periodically at predetermined intervals rather than continuously. This periodic action allows the system to maintain simple detection circuits during normal operation while periodically checking wire integrity, balancing complexity and reliability requirements.
3Productivity
If continuous monitoring of detection signals is performed, then user operations are detected accurately, but wire breakage cannot be distinguished from valid detection signals
Solution Approach 1:
The monitoring process is segmented into distinct phases: normal continuous monitoring for user operations, and periodic grounding phases for wire breakage detection. This segmentation allows the system to maintain high-speed operation detection during normal phases while periodically switching to wire integrity verification, preventing false positives.
Solution Approach 2:
Wire breakage identification is performed periodically by temporarily grounding the sensor electrode at predetermined intervals. This periodic interruption of continuous monitoring allows the system to distinguish wire breakage conditions from valid user operations, as wire breakage will manifest as abnormal responses during the grounding phase rather than during normal detection.
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
Enables accurate detection of user operations while simultaneously identifying wire breakage in the first and second electrodes, ensuring reliable operation determination and improving accuracy by maintaining the capacitance between the electrodes at zero during normal operation.
Implementation Method 1
detects when a human body approaches or contacts an operation surface... based on a change in capacitance of the first electrode
Implementation Method 2
The switch unit forcibly switches the second electrode to a state connected to ground so that the second electrode shifts to ground potential
Data Source
AI summary
A detector applies voltage to a first electrode and a second electrode facing the first electrode to detect a user operation performed on the operation surface based on a change in capacitance of the first electrode to which voltage has been applied. The detector includes a switch unit that forcibly switches the second electrode to a state connected to ground so that the second electrode shifts to ground potential after voltage is applied to the first electrode when a change in the capacitance of the first electrode is being detected. A determination unit determines whether wire breakage is occurring in the first electrode and the second electrode based on a detection signal obtained from the first electrode after the first electrode is connected to ground and a difference in the detection signal obtained from the first electrode before and after the first electrode is connected to ground.