Piezoelectric Sensor Element Thermal Signal Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Piezoelectric sensors, such as those made from PVDF, often generate false signals due to thermal changes, which can be problematic in environments with varying temperatures, leading to inaccurate touch or pressure detection.
Innovation Solution
A piezoelectric sensor element is designed with a specific configuration of conductive regions and non-conductive voids to reduce thermally-induced voltage changes, using a force concentrating layer and thermally conductive spreading layers to manage thermal stimuli and mechanical forces, allowing for effective cancellation of pyroelectric signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric materials such as PVDF are used for touch and press detection, then cost effectiveness and detection performance are improved, but thermal response and false signals increase due to large pyroelectric coefficients
Solution Approach 1:
The piezoelectric layer is divided into multiple segments with different conductive region configurations. Each segment has conductive regions arranged to respond differently to thermal stimuli, allowing the combination to cancel out thermal responses while maintaining mechanical detection capability
Solution Approach 2:
Different regions of the piezoelectric layer are given different conductive patterns - some regions have conductive regions configured for thermal response while others are configured for mechanical response. This local differentiation allows simultaneous optimization for both thermal cancellation and mechanical detection
2Temperature
If conductive regions are configured to respond to thermal changes, then thermal detection capability is improved, but mechanical force detection accuracy deteriorates due to false signals
Solution Approach 1:
The pyroelectric effect, which causes harmful false signals during mechanical detection, is converted into a useful feature by configuring conductive regions to deliberately respond to thermal changes. This thermal response is then used to cancel out thermal interference in the mechanical detection channels through differential measurement
Solution Approach 2:
Dedicated conductive regions serve as intermediary elements that specifically respond to thermal stimuli and generate signals used to cancel thermal interference in the main detection channels. These intermediary regions act as thermal sensors that enable common-mode rejection
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 configuration significantly reduces thermal responses in piezoelectric sensors, enhancing their accuracy in detecting touch and pressure inputs while minimizing false signals from temperature changes.
Implementation Method 1
Piezoelectric impact detectors formed from polymeric materials such as polyvinylidene fluoride (PVDF)
Implementation Method 2
many piezoelectric materials such as PVDF have the disadvantage that they also respond to temperature changes, often with pyroelectric coefficients that rival their piezo coefficients
Data Source
AI summary
Certain example embodiments include a press sensor element that includes a piezoelectric layer having a first surface in communication with a first layer, the first layer including a first conductive region, where the first conductive region covers at least a central portion the first surface. The sensor element includes a second surface in communication with a second layer, the second layer including a second conductive region, a third conductive region, and a first non-conductive void region separating the second conductive region and the third conductive region. An area of the first conductive region is configured in size relative to an area of the third conductive region to substantially reduce a thermally-induced voltage change between two or more of the first, second, and third conductive regions responsive to a corresponding temperature change of at least a portion of the piezoelectric layer.