Force Touch Sensor Piezoresistive Layer Bending Interference
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Solution Overview
Problem
Force touch sensors based on the piezoelectric effect face misrecognition issues when applied to flexible display devices due to bending, which generates electrical signals that interfere with pressure sensing.
Innovation Solution
Incorporating a piezoresistive material layer between the driving and sensing electrodes, along with a piezoelectric material layer, to differentiate between touch and bending-induced signals, ensuring accurate pressure sensing by maintaining resistance and preventing false electrical signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric material layer is used for pressure sensing, then pressure sensitivity is improved, but bending-induced false signals increase
Solution Approach 1:
A piezoresistive material layer is introduced as an intermediary between the piezoelectric material layer and the electrodes. This intermediary layer selectively transmits electrical signals: it allows signals from pressure-induced deformation to pass through while blocking signals from bending deformation, thereby eliminating bending interference while preserving pressure sensing capability
Solution Approach 2:
The force touch sensor employs a composite structure combining piezoelectric material layer and piezoresistive material layer. The piezoelectric layer provides pressure sensitivity through charge generation, while the piezoresistive layer provides selective signal transmission based on deformation type, achieving both functions simultaneously
2Measurement precision
If the piezoresistive material layer is added to differentiate touch and bending signals, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The sensor uses a composite of piezoelectric and piezoresistive material layers with distinct functional properties. The piezoelectric layer generates charge under pressure, while the piezoresistive layer modulates electrical resistance based on deformation type, enabling signal differentiation through material property differences rather than complex circuitry
Solution Approach 2:
The patent replaces complex signal processing mechanisms with a passive material-based filtering approach. The piezoresistive layer inherently differentiates between pressure and bending signals through its resistance characteristics, eliminating the need for additional active components or complex control circuits
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 effectively prevents misrecognition in pressure sensing by maintaining resistance and accurately determining touch and pressure positions, even when the sensor is bent, thereby enhancing the reliability of force touch functionality in flexible display devices.
Implementation Method 1
a force touch sensor based on piezoelectric effect is typically used to achieve multi-point touch and pressure sensing functions
Implementation Method 2
Incorporating a piezoresistive material layer between the driving and sensing electrodes, along with a piezoelectric material layer, to differentiate between touch and bending-induced signals
Data Source
AI summary
The present disclosure provides a force touch sensor, a display device and a driving method thereof. The force touch sensor comprises a driving electrode, a sensing electrode, a piezoelectric material layer and a piezoresistive material layer, wherein the piezoelectric material layer and the piezoresistive material layer are disposed between the driving electrode and the sensing electrode.