Dual-Mode Sensor Electrode Ohmmeter for Short Detection
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Solution Overview
Problem
Manufacturing defects can cause sensor electrodes in proximity sensor devices to become shorted, making them ineffective for capacitive sensing as it is difficult to measure capacitance between shorted electrodes.
Innovation Solution
The input device is configured to operate in two modes: one for measuring capacitance and another for measuring resistance between sensor electrodes, allowing detection of electrical shorts and determination of strain, using a processing system with ohmmeter circuitry and capacitive sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor electrodes are electrically isolated to enable capacitive sensing, then capacitive sensing capability is improved, but manufacturing defects may cause shorting between electrodes making them ineffective
Solution Approach 1:
The system performs resistance measurements between sensor electrodes before capacitive sensing operations to detect manufacturing defects such as shorting. By conducting this preliminary check, the system identifies problematic electrodes in advance and can exclude them from capacitive sensing, preventing defective electrodes from compromising the reliability of the sensing system.
2Difficulty of detecting and measuring
If resistance measurement is added to detect electrical shorts, then detection capability is improved, but device complexity increases
Solution Approach 1:
The processing system is designed to perform multiple functions: it can measure both capacitance and resistance between sensor electrodes, and it can operate in different modes (first mode for capacitance, second mode for resistance). This multi-functionality allows the system to detect electrical shorts through resistance measurement while maintaining the same hardware infrastructure, thereby improving detection capability without proportionally increasing device complexity.
3Measurement precision
If dual-mode operation (capacitance and resistance measurement) is implemented, then measurement precision is improved, but operation complexity increases
Solution Approach 1:
The processing system dynamically switches between different operational modes based on the measurement task. It can operate in a first mode for capacitance measurement and in a second mode for resistance measurement. This dynamic mode switching allows the system to achieve precise electrode characterization by selecting the appropriate measurement type, while the processing system manages the complexity through automated mode selection and execution.
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 effective detection of electrical shorts and strain on the input device, ensuring accurate capacitive sensing by identifying and potentially bypassing shorted electrodes, thereby improving the reliability of proximity sensor operations.
Implementation Method 1
When operating in the first mode, the processing system is configured to measure a first current across the pair of sensor electrodes and determine a capacitance of the pair of sensor electrodes based on the measured first current. The processing system may be configured to drive a time-varying voltage across the pair of sensor electrodes to produce the first current.
Implementation Method 2
When operating in the second mode, the processing system is configured to measure a second current across the pair of sensor electrodes and determine a resistance of the pair of sensor electrodes based on the measured second current. The processing system may be configured to drive a constant voltage across the pair of sensor electrodes to produce the second current.
Data Source
AI summary
An input device includes a plurality of sensor electrodes and a processing system that is operable in at least a first mode or a second mode. The processing system is configured to receive an input current from a pair of the sensor electrodes. When operating the first mode, the processing system is configured to measure a capacitance across the pair of sensor electrodes based on the received input current. When operating the second mode, the processing system is configured to measure a resistance between the pair of sensor electrodes based on the received input current.