Multi-Layer Sensing Device with Resilient Dielectric for Force and Fingerprint
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Solution Overview
Problem
Current touch sensing technologies face challenges in integrating force measurement, touch control, and fingerprint identification due to limitations in sensing accuracy, cost, and product integration, particularly with the capacitance type fingerprint identification method, which suffers from weak sensing signals and strong background noise, and the need for expensive sapphire films for protection.
Innovation Solution
A sensing device and method that incorporates a plurality of switch circuits, switch control lines, sensing signal lines, a capacitance detection and switch array control circuit, and a switch control signal generating circuit, allowing for the use of individual electrodes for fingerprint detection or combining them for touch sensing, with a resilient dielectric layer for force measurement, and applying in-phase reflection signals to enhance sensing sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor electrodes and sensing circuit are implemented in one IC chip with package for protecting conductive lines, then the sensing circuit is protected, but an additional 10 μm distance is introduced between sensor electrode and finger, negatively influencing sensing accuracy
Solution Approach 1:
The patent transitions from planar 2D electrode arrangement to 3D stacked architecture with multiple layers (first electrode layer, second electrode layer, third electrode layer) separated by resilient dielectric layers. This vertical dimensionality change allows the sensing circuit to be integrated in the same layer as the sensor electrode, eliminating the need for protective packaging that would increase distance, while maintaining circuit protection through the resilient dielectric material.
2Measurement precision
If sapphire film with high dielectric is used to reduce distance between sensor electrode and finger, then sensing accuracy is improved, but cost increases and product integration difficulty increases
Solution Approach 1:
The patent replaces expensive sapphire film with a resilient dielectric layer that can be manufactured using standard flexible display fabrication processes. The resilient dielectric layer serves multiple functions: protecting the sensing circuit, maintaining appropriate distance for capacitance sensing, and enabling the 3D stacked structure. This substitution significantly reduces material cost and simplifies integration while maintaining sensing accuracy.
3Force
If electromechanical force sensor is arranged at corner of display panel, then force sensing is achieved, but sensor cost increases and adhesion with display panel becomes difficult
Solution Approach 1:
The patent integrates force sensing electrodes, touch sensing electrodes, and fingerprint sensing electrodes into a unified multi-layer capacitive sensing structure. The same resilient dielectric layers and electrode patterns serve multiple functions: force measurement through capacitance change, touch control through capacitive coupling, and fingerprint identification through capacitive mapping. This eliminates the need for separate electromechanical force sensors and their associated adhesion challenges.
4Force
If deformable resilient micro-structure with complicated process is provided, then relation between force and deformation degree is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent uses a resilient dielectric layer with specific mechanical properties (resilience, appropriate thickness) that naturally provides the force-deformation relationship needed for sensing. By changing the material parameters of the dielectric layer rather than creating complex micro-structures, the patent achieves force sensitivity through standard thin-film deposition and lamination processes, avoiding complicated manufacturing steps.
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 improves sensing sensitivity, signal-to-noise ratio, and stability, reducing the sensing distance and enhancing the accuracy of touch and fingerprint identification while reducing costs and complexity in product integration.
Implementation Method 1
an resilient dielectric layer arranged between the first electrode layer and the force electrode layer, wherein the resilient dielectric layer is deformed when a force is applied thereto, and is restored to its original volume and shape when the force is removed therefrom
Implementation Method 2
by measuring the capacitance variation between the force sensing electrode and the touch electrode, the force can be calculated
Data Source
AI summary
A sensing device is provided with functions of force measurement, touch control and fingerprint identification. A first electrode layer has plural first electrodes. A switch and wire layer includes plural switch circuits, plural switch control lines and plural sensing signal lines. Each switch circuit is corresponding to an adjacent first electrode and electrically connected to the corresponding first electrode through a contact. Each switch control line includes two control wires and is electrically connected to two switch circuits. Each sensing signal line includes one sensing wire and is electrically connected to the two switch circuits. A force electrode layer has a force electrode. A compressible dielectric layer is arranged between the first electrode layer and the force electrode layer. The compressible dielectric layer is deformed when a force is applied, and restored to the original shape after the force is removed.