Pressure Sensor Matrix Single ADC Readout
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Solution Overview
Problem
Existing pressure sensor sheets require significant time and resources to read out sensor values, increasing costs due to the need for extensive electronics and software to manage multiple sensor points.
Innovation Solution
A method and pressure sensor unit utilizing a grid-like structure with perpendicular conductor tracks, where an electric voltage is applied to individual lines and columns to detect changes at intersection points, using a single analog-to-digital converter and switch units to efficiently read out values without the need for multiplexers or additional ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple ADCs and multiplexers are used to read out sensor values from each intersection point, then measurement precision is improved, but device complexity increases significantly
Solution Approach 1:
The patent merges multiple ADC functions into a single ADC by time-multiplexing the reading of sensor values from different intersection points. Instead of having one ADC per sensor point, a single ADC sequentially reads values from all intersection points by switching between different conductor track pairs, thereby reducing electronics complexity while maintaining measurement capability
Solution Approach 2:
The patent implements periodic scanning of the conductor track grid by systematically activating different line-column pairs in sequence. The reading process follows a periodic pattern where each intersection point is read at regular intervals, allowing a single ADC to capture all sensor values over time without missing any measurements
2Productivity
If all sensor points are read out simultaneously, then productivity is improved, but device complexity and cost increase due to required electronics
Solution Approach 1:
The patent applies preliminary action by pre-activating one conductor track (either line or column) before reading sensor values. This allows the reading process to proceed efficiently by having one track continuously active while the other track is systematically switched, optimizing the reading sequence and reducing idle time in the measurement process
Solution Approach 2:
The patent segments the reading process into discrete steps where sensor values are read point by point or in small groups rather than all at once. The conductor track grid is divided into manageable segments that can be read sequentially, allowing a single ADC to handle the entire array through systematic segmentation of the measurement task
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 cost-effective acquisition of sensor values, reducing the complexity and cost of electronics while maintaining high data quality, enabling efficient patient monitoring and early detection of health issues or bed exit risks.
Implementation Method 1
A piezoresistive third fabric layer is arranged between the two fabric layers. This third fabric layer changes its resistance and thus its electrical conductivity depending on the pressure force action.
Implementation Method 2
If a measurement current is applied to the electrically conductive threads and the mat is subjected to a pressure, the electrical resistance changes at the intersection areas.
Data Source
AI summary
A pressure sensor sheet (3) comprises a first layer (31) with first conductor paths (310) forming rows of a matrix and a second layer (32) with second conductor paths (320) forming columns of a matrix. The matrix has intersection points (30) being separated by a central layer (33) and forming sensor points (30). The rows and columns are cyclically sampled by a counter unit in order to determine the values at all of the intersection points (30). An electric voltage is applied to a single conductor path of the first conductor paths (310) and changes in the second conductor paths (320) are individually determined one after the other. All of the changes determined on the second conductor paths (320) are converted by a single analog-digital converter (ADC). This is repeated until all the rows and all the columns of the matrix have been cyclically sampled.