Row Column Strain Sensing Architecture
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Solution Overview
Problem
Conventional resistance-based strain sensors in electronic devices face scaling issues when multiple sensors are used, leading to time delays or complex circuitry due to the need for multiple voltage sources and bridges, which complicates the detection of touch inputs on input surfaces.
Innovation Solution
A parallel current-based sensing configuration using multiple resistance-based strain sensors connected in parallel, where a source signal is applied to each sensor, and current sensing circuitry measures the currents from each sensor to estimate physical parameters like strain, allowing for simpler processing and reduced circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple voltage sources and bridges are used to measure multiple strain sensors, then measurement accuracy is maintained, but circuit size and complexity become unacceptable
Solution Approach 1:
The patent combines multiple Wheatstone bridge circuits into a single shared bridge circuit. Instead of dedicating separate voltage sources and bridge circuits to each strain sensor, the invention uses one common bridge circuit that can sequentially or simultaneously serve multiple sensors through multiplexing, thereby reducing the overall number of circuit components while maintaining measurement accuracy.
Solution Approach 2:
The single Wheatstone bridge circuit is designed to perform multiple functions by measuring strain across multiple sensors. The bridge circuit acts as a universal measurement platform that can adapt to different sensor configurations and positions, eliminating the need for dedicated circuits for each sensor and reducing system complexity.
2Device complexity
If a single voltage source and bridge are applied sequentially to multiple sensors, then circuit complexity is reduced, but time delays occur in measuring touch inputs
Solution Approach 1:
The patent implements periodic scanning of multiple strain sensors using the single Wheatstone bridge circuit. By rapidly cycling through sensors in a systematic sequence, the system achieves near-simultaneous measurement capability, reducing perceptible time delays while maintaining the simplicity of using a single bridge circuit.
Solution Approach 2:
The system dynamically allocates the single bridge circuit to different sensors based on measurement priorities and timing requirements. The circuit can switch between sensors adaptively, optimizing measurement speed for critical touch inputs while maintaining comprehensive coverage of all sensors.
3Area of stationary object
If strain sensors are arranged in an array to cover larger input surfaces, then detection coverage is improved, but scaling problems arise due to increased circuit requirements
Solution Approach 1:
The patent organizes strain sensors in a two-dimensional array configuration and uses row-column multiplexing with a single Wheatstone bridge circuit. By addressing sensors through row and column intersections, the system can efficiently scan large arrays without proportionally increasing circuit complexity, enabling scalable expansion to cover larger input surfaces.
Solution Approach 2:
The large array of strain sensors is divided into manageable segments or groups that can be sequentially accessed by the single bridge circuit. This segmentation allows the system to handle large numbers of sensors by processing them in organized batches, reducing the computational and circuit complexity burden compared to handling all sensors simultaneously.
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 enables efficient detection of strain and other physical parameters across multiple sensors with fewer current receivers, reducing circuit size and complexity while maintaining accurate strain measurement, even in large arrays of sensors.
Implementation Method 1
When the film is attached to a deformable surface, deflection of the surface alters or stretches the conductive path, changing its resistance. The change in resistance correlates with the force on the deformable surface
Implementation Method 2
Resistance-based sensors may detect a resistance value or changes in the resistance value
Data Source
AI summary
Disclosed herein are structures, devices, and methods for sensing physical parameters, such as strain in a surface, using resistance-based parameter sensors and current sensing. An applied strain can cause a differential change in one or more currents from two resistors configured in parallel in the sensor. Strain can be inferred from a ratio of the difference of the two currents to a sum of the two currents. These structures and methods can be adapted to measure strain or other parameters using an array of sensors, with common voltages applied to rows of the array, and currents being summed in column in the array so that fewer receivers are needed.