Piezoelectric Sensor Matrix Wake-Up Detection for Low-Power Touch Sensing
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Solution Overview
Problem
Existing touch user interfaces with piezoelectric sensor elements face high energy consumption and complexity due to the need for multiple monitoring apparatuses and extensive wiring, especially in configurations with many discrete touch points, leading to increased manufacturing costs and limited reliability.
Innovation Solution
A matrix of piezoelectric sensor elements with measuring circuits configured for rows and columns, along with a wake-up trigger that activates the system only when a touch is detected, reducing energy consumption and complexity by maintaining a low-power mode until triggered, using a single activity detecting and touch recognition circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one monitoring apparatus per piezoelectric sensor element is used, then touch detection reliability is improved, but current consumption increases linearly with the number of sensor elements
Solution Approach 1:
Multiple piezoelectric sensor elements are electrically connected in parallel to a single monitoring apparatus, merging their signals for simultaneous detection. This reduces the number of monitoring apparatuses from N (one per sensor) to 1, dramatically reducing current consumption while maintaining reliable touch detection across all sensor elements.
2Device complexity
If many piezoelectric sensor elements are connected to one monitoring apparatus through a multiplexer, then wiring complexity is reduced, but continuous polling increases current consumption even in inactive stage
Solution Approach 1:
The monitoring apparatus operates in periodic cycles, alternating between active detection mode and low-power inactive mode. During inactive periods, no polling occurs and current consumption is minimized. When a touch event occurs, the piezoelectric sensors generate signals that trigger the monitoring apparatus to switch to active mode, ensuring reliable detection only when needed.
3Reliability
If polling speed is accelerated to improve signal detection reliability, then touch detection reliability is improved, but power consumption and performance requirements increase
Solution Approach 1:
Instead of continuous high-speed polling, the system uses periodic monitoring with variable speed. During inactive stages, polling is suspended or slowed to minimize power consumption. When touch events occur, the piezoelectric sensors naturally generate signals that trigger high-speed detection only at the moment needed, achieving reliable detection without sustained high power consumption.
4Reliability
If matrix detection method with continuous active signal feeding is used, then touch detection capability is improved, but electrical power consumption becomes too high for typical requirements
Solution Approach 1:
The piezoelectric sensor elements serve dual functions: they act as both sensors and signal sources. When touched, they automatically generate electrical signals through the piezoelectric effect, eliminating the need for external active signal feeding. The monitoring apparatus only needs to detect these self-generated signals, dramatically reducing power consumption compared to methods requiring continuous signal injection.
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 significantly reduces energy consumption and complexity by minimizing active power usage and wiring, enabling efficient and reliable touch detection with reduced manufacturing costs and improved reliability for touch keypads.
Implementation Method 1
Piezoelectric sensing based on charge accumulated by deforming the piezoelectric sensor element
Data Source
AI summary
A detection of piezoelectric sensor elements is provided. According to a first aspect, a device comprises: a matrix of piezoelectric sensor elements comprising rows of the piezoelectric sensor elements and columns of the piezoelectric sensor elements; measuring circuits configured to detect at least one touch, wherein the measuring circuits are configured to the rows and to the columns; and a wake-up trigger configured to detect the at least one touch and further configured to trigger the matrix to an operation mode when the at least one touch is detected. The device is configured for detecting a press event of a plurality of piezoelectric sensor elements, using, for example only a single activity detecting and touch recognition circuit. Complexity and energy consumption may be reduced.