Transparent Fingerprint Sensor Crosstalk Reduction
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Solution Overview
Problem
Existing transparent fingerprint recognition sensors face challenges in minimizing crosstalk between driving signal lines and data reception lines, which affects the accuracy and efficiency of fingerprint recognition and touch sensing functions, especially when integrated into touch screen devices.
Innovation Solution
The design incorporates a fingerprint recognition sensor with a combined area featuring a sensing area, a bezel area, and a tracer area, where the signal lines are disposed at different levels and misaligned to minimize parasitic capacitance, and the use of transparent materials and conductive plugs for electrical connections, reducing light loss and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If signal lines are disposed close together to reduce device area, then device complexity is reduced, but crosstalk between driving signal lines and data reception lines increases
Solution Approach 1:
The patent applies dimensionality change by disposing signal lines at different levels (first level and second level) rather than the same plane. The first signal lines are disposed at a first level while second signal lines are disposed at a second level, creating vertical separation that reduces crosstalk while maintaining compact horizontal layout. This multi-level configuration allows closer spacing without increasing interference.
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between signal lines at different levels. This insulating layer acts as a mediator that electrically isolates the first signal lines from the second signal lines, preventing direct crosstalk while allowing the lines to be disposed in close proximity. The insulating layer enables dense packing without sacrificing signal integrity.
2Illumination intensity
If transparent materials are used to maintain transparency, then visual clarity is improved, but electrical connection reliability may deteriorate
Solution Approach 1:
The patent employs composite materials by combining transparent conductive materials for electrodes with transparent insulating materials for the insulating layer. This composite structure maintains overall transparency while providing both electrical conduction (through the transparent conductive material) and electrical isolation (through the transparent insulating material). The composite approach resolves the contradiction between transparency and electrical connection reliability.
Solution Approach 2:
The patent segments the electrical connection structure into distinct functional components: transparent conductive material segments for electrical conduction and transparent insulating material segments for electrical isolation. This segmentation allows each material to perform its specific function optimally while maintaining transparency, with the transparent conductive material providing reliable electrical paths and the transparent insulating material ensuring proper isolation between signal lines.
3Measurement precision
If misalignment is introduced to reduce parasitic capacitance, then signal quality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent resolves the alignment precision challenge by moving the misalignment strategy to the vertical dimension rather than requiring precise horizontal alignment. By disposing signal lines at different levels (first level and second level) with intentional horizontal misalignment, the patent reduces parasitic capacitance through increased separation distance while the vertical stacking provides a clear manufacturing reference structure that simplifies the alignment process compared to planar approaches.
Data Source
AI summary
Provided are a transparent fingerprint recognition sensor and a touch screen device including the transparent fingerprint recognition sensor. The transparent fingerprint recognition sensor includes: a substrate; a plurality of first electrodes disposed on the substrate in a sensing area; an insulating layer disposed on the substrate and covering the plurality of first electrodes; a plurality of second electrodes disposed within the insulating layer in the sensing area; a plurality of first signal lines disposed within the insulating layer in the bezel area; and a plurality of second signal lines disposed on a top surface of the insulating layer, in the bezel area.