Pressure Sensor Matrix Isolation to Prevent Ghosting Errors
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Solution Overview
Problem
Pressure-sensitive protective devices face challenges in rapid evaluation and are prone to 'ghosting' errors, which limit their use in safety-critical applications due to faulty current paths and prolonged measurement times, especially in matrix-like sensors.
Innovation Solution
Adapted measuring electronics apply a defined potential to remaining electrodes during cell measurement, preventing fault currents and reducing measurement duration by isolating the cell from other cells, thus avoiding 'ghosting' and enabling fail-safe spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If sequential measurement of sensor cells is used, then measurement time is reduced per cell, but ghosting errors occur due to fault current paths
Solution Approach 1:
The sensor matrix is segmented into individually addressable sensor cells with separate electrode connections. Each cell can be measured independently by selecting specific row and column electrodes, preventing fault currents from affecting multiple cells simultaneously and eliminating ghosting errors while maintaining rapid sequential measurement
Solution Approach 2:
A switch matrix acts as an intermediary between the electrodes and measurement circuitry. The switch matrix selectively connects specific electrode pairs for measurement while isolating other electrodes, preventing fault current paths and enabling accurate individual cell measurement without ghosting effects
2Measurement precision
If more sensor cells are connected to increase local resolution, then measurement precision improves, but measurement time increases due to sequential querying
Solution Approach 1:
The measurement process uses periodic sequential scanning of sensor cells through row and column electrodes. Each cell is rapidly measured in succession, with the switch matrix enabling quick reconfiguration between measurement pairs. This periodic scanning achieves complete matrix coverage while maintaining high speed through efficient electrode reuse
Solution Approach 2:
Each electrode serves multiple functions by participating in measurements of multiple different sensor cells. Row electrodes and column electrodes are reused across different measurement cycles, allowing the same physical electrodes to measure numerous cells sequentially without requiring dedicated electrodes for each cell, thus maintaining high resolution with limited electrode count
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 allows for rapid and accurate evaluation of individual sensor cells, reducing overall measurement time and power consumption while ensuring reliable detection of load locations, enhancing the device's safety and efficiency in safety-critical applications.
Implementation Method 1
each first electrode in the associated Coupling location is spaced from the associated second electrode by a pressure-sensitive material, so that when a force is applied to the coupling location, an electrical resistance between the associated first and the associated second electrode changes
Data Source
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AI summary
The present invention relates to a protection device (10, 12) with a pressure-sensitive sensor (22) comprising a plurality of first electrodes (46) and a plurality of second electrodes (48). Each of the first electrodes (46a-46h) overlaps one of the second electrodes (48a-48e) in a corresponding coupling site (50), and each of the first electrodes (46a-46h) is spaced apart from the corresponding second electrode by a pressure-sensitive material (56) at the corresponding coupling site (50), in such a way that when a force is applied to the coupling site (50) an electrical resistance (58) between the corresponding first electrode (46g, 52) and the corresponding second electrode (48d, 54) changes. An electronic measurement unit coupled to the plurality of first electrodes (46) and to the plurality of second electrodes (48) is designed to determine successively the electrical resistance (58) at the corresponding coupling sites (50). An evaluation unit (90) is designed to provide an output signal depending on the measured electrical resistances (58), the electronic measurement unit being designed, in order to determine the electrical resistance (58) at a coupling site (50) via the corresponding first electrode (46g, 52) and the corresponding second electrode (48d, 54), to connect the other first electrodes and second electrodes to a connection for receiving a defined potential (72), allowing an isolated measurement of the electrical resistance (58) at the coupling site (50).