Transparent Fingerprint Sensor Pattern Using Composite Electrodes
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Solution Overview
Problem
Current sensors used in display active areas for touch and fingerprint sensing lack the necessary electrical properties and spatial density to effectively capture fingerprint information while maintaining transparency, making them unsuitable for integration within display active areas.
Innovation Solution
The development of transparent fingerprint sensor patterns utilizing a grid of sensor electrodes with a combination of metal traces and transparent conductive segments, arranged to provide a high enough spatial density for fingerprint sensing while maintaining transparency, allowing for integration within display active areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent electrodes (e.g., ITO) are used to minimize impact on visible graphics, then transparency is improved, but electrical properties suitable for capturing fingerprint information are not achieved
Solution Approach 1:
The patent combines transparent conductive segments (ITO) with opaque metal traces (copper) to form a composite sensor electrode structure. The transparent segments maintain visual clarity while the metal traces provide the necessary electrical conductivity and signal strength for fingerprint sensing, resolving the contradiction between transparency and electrical performance.
Solution Approach 2:
The sensor electrodes are segmented into discrete transparent conductive segments interconnected by metal traces. This segmentation allows each component to perform its specialized function - the transparent segments maintain visibility while the metal interconnects provide robust electrical pathways, enabling both transparency and reliable fingerprint sensing.
2Reliability
If opaque metals (e.g., copper) are arranged in a fine grid to create larger sensor electrodes, then electrical properties are improved, but transparency is reduced
Solution Approach 1:
The continuous metal grid is segmented into discrete interconnection traces that only bridge between transparent conductive segments. This reduces the total metal area occupying the display region, maintaining transparency while preserving the electrical connectivity needed for sensor function.
Solution Approach 2:
The sensor structure uses a composite arrangement where transparent ITO segments form the primary electrode areas and thin copper traces provide interconnections. This composite design optimizes both optical transparency (through the ITO segments) and electrical conductivity (through the copper traces).
3Measurement precision
If spatial density of sensing elements is increased to capture fingerprint information, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent transitions from traditional planar electrode layouts to a multi-dimensional structure where transparent conductive segments and metal traces operate in different functional dimensions. The segments provide sensing areas while the traces provide electrical connectivity in a layered architecture, enabling high spatial density without proportionally increasing manufacturing complexity.
Data Source
AI summary
A transparent sensor pattern suitable for sensing fingerprint information in a display area is disclosed. The sensor pattern includes a receiver electrode extending in a first direction and a transmitter electrode extending in a second direction different from the first direction. The receiver electrode includes a conductive trace made from an opaque metal material and the receiver electrode is substantially free of transparent conductive material. The transmitter electrode includes a conductive segment made from a transparent conductive material. A dielectric material is disposed between the receiver electrode and the transmitter electrode, and the dielectric material electrically insulates the receiver electrode from the transmitter electrode.