Capacitive Sensor Array Sampling for Low-Power Touch Detection
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Solution Overview
Problem
Existing touch-based interfaces in electronic devices, such as smart cards and IoT devices, face challenges in accurately capturing touch events while minimizing power consumption, especially when covered by insulating layers, which affects sensor sensitivity and increases power consumption when trying to compensate with higher supply voltage.
Innovation Solution
A sensor system comprising an array of sensor elements and a processing unit that identifies and sequentially steps through sets and subsets of sensor elements, concurrently sampling them to increase sensitivity while keeping power consumption low, using sensor capacitors and switching elements like GPIO pins, and implementing a 2-out-of-3 or 3-out-of-4 sampling scheme to reduce redundant steps and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If higher supply voltage is used to compensate for reduced sensor sensitivity due to insulating layers, then sensor sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic sampling of sensor elements by dividing them into sets and subsets that are sequentially activated. Instead of continuously powering all sensor elements, the system periodically selects specific subsets (e.g., 2-out-of-3 or 3-out-of-4 schemes) for sampling, thereby reducing overall power consumption while maintaining adequate sensitivity through strategic selection of active sensor groups
Solution Approach 2:
The sensor array is segmented into multiple sets and subsets of sensor elements. By organizing sensors into discrete groups that can be independently activated, the system can sample only necessary portions of the array at any given time, reducing total power consumption while maintaining measurement capability through systematic coverage of all segments over multiple sampling cycles
2Measurement precision
If all sensor elements are sampled simultaneously to maximize sensitivity, then measurement accuracy is improved, but power consumption and processing complexity increase
Solution Approach 1:
The sensor array is divided into multiple sets and subsets, allowing the processing unit to handle smaller groups of sensors sequentially rather than processing all sensors simultaneously. This segmentation reduces the computational burden at each processing step while ensuring complete coverage through systematic progression through all subsets
Solution Approach 2:
The system employs periodic sampling sequences where different subsets of sensor elements are activated in alternating cycles. This approach distributes the processing load over time, allowing the processing unit to handle manageable portions of data sequentially while maintaining comprehensive monitoring capability through repeated cycles covering all sensor elements
3Productivity
If all sensor elements are sampled simultaneously to reduce sampling time, then productivity is improved, but power consumption increases
Solution Approach 1:
The patent implements a periodic sampling scheme where sensor elements are activated in sequential subsets rather than all at once. By carefully designing the sampling sequence to cycle through different subsets (e.g., using 2-out-of-3 or 3-out-of-4 schemes), the system achieves adequate sampling rates for touch detection while significantly reducing peak power consumption compared to simultaneous activation of all sensors
Solution Approach 2:
The system dynamically adjusts which sensor elements are active at any given moment, transitioning between different subsets in a coordinated sequence. This dynamic reconfiguration allows the system to maintain responsive touch detection capability while optimizing power consumption by keeping only necessary sensors active during each sampling interval
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
The solution enhances sensor sensitivity and reduces power consumption by concurrently sampling sensor elements, allowing for accurate touch event capture with lower power usage, suitable for devices like smart cards, IoT devices, and wearable devices, while also reducing position noise and improving sampling rates.
Implementation Method 1
the sensor elements comprise sensor capacitors, and concurrently sampling the sensor elements comprises measuring the accumulated capacitance of said sensor capacitors
Data Source
AI summary
In accordance with a first aspect of the present disclosure, a sensor system comprising a processing unit and an array of sensor elements, wherein the processing unit is configured to: identify mutually different sets of sensor elements within the array and step sequentially through said sets; identify mutually different subsets of sensor elements within said sets and step sequentially through said subsets; concurrently sample the sensor elements within said subsets. In accordance with a second aspect of the present disclosure, a corresponding sensing method is conceived. In accordance with a third aspect of the present disclosure, a corresponding computer program is provided.