Fingerprint Detection Electrode Asymmetry for Display Clarity
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Solution Overview
Problem
Fingerprint detection devices integrated with display devices often suffer from unintended patterns such as moire and light reflecting patterns due to the arrangement of electrodes, which can interfere with the detection process and visual clarity.
Innovation Solution
A fingerprint detection device with a substrate featuring drive electrodes arranged in one direction and detection electrodes intersecting them, including zigzag line portions and bent connections, which are designed to reduce the occurrence of these patterns by optimizing the arrangement and intersection of electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are arranged in a regular grid pattern for fingerprint detection, then detection function is achieved, but unintended patterns (moire and light reflecting patterns) occur
Solution Approach 1:
The detection electrodes are designed with an asymmetric zigzag pattern instead of a regular grid arrangement. This asymmetric configuration disrupts the periodicity that causes moire patterns and light reflecting patterns, while still maintaining the electrode intersections necessary for capacitance-based fingerprint detection.
Solution Approach 2:
The detection electrodes incorporate curved zigzag portions rather than straight lines. These curved segments change the light reflection characteristics and eliminate the regular geometric patterns that interfere with display quality, while preserving the electrode's electrical function for fingerprint detection.
2Ease of manufacture
If detection electrodes are made as straight lines for simple manufacturing, then manufacturing ease is improved, but unintended patterns occur that reduce visual clarity
Solution Approach 1:
The detection electrodes incorporate curved zigzag portions rather than straight lines. These curved segments change the light reflection characteristics and eliminate the regular geometric patterns that interfere with display quality, while preserving the electrode's electrical function for fingerprint detection.
Solution Approach 2:
The detection electrodes are divided into multiple segments (first line portions, second line portions, and bent portions) that can be fabricated using standard photolithography processes. This segmentation allows the complex zigzag pattern to be manufactured with existing techniques while achieving the desired optical properties.
3Measurement precision
If electrodes are arranged to maximize detection accuracy, then fingerprint detection precision is improved, but moire patterns and light reflecting patterns increase
Solution Approach 1:
The detection electrodes are designed with an asymmetric zigzag pattern instead of a regular grid arrangement. This asymmetric configuration disrupts the periodicity that causes moire patterns and light reflecting patterns, while still maintaining the electrode intersections necessary for capacitance-based fingerprint detection.
Solution Approach 2:
The detection electrodes incorporate curved zigzag portions rather than straight lines. These curved segments change the light reflection characteristics and eliminate the regular geometric patterns that interfere with display quality, while preserving the electrode's electrical function for fingerprint detection.
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 minimizes the occurrence of unintended patterns like moire and light reflecting patterns, enhancing the accuracy of fingerprint detection and visual clarity in display devices.
Implementation Method 1
A fingerprint sensor of Japanese Patent Application Laid-open Publication No. 2001-52148 detects a capacitance change corresponding to a recess or protrusion of a fingerprint to detect the shape of a fingerprint of a finger being in contact with the display device.
Implementation Method 2
Electrodes in a fingerprint detection region reflect light entering from the cover glass side. When the fingerprint detection region is arranged at a position overlapping with a display region of the display device, the reflection of light by the electrodes in the fingerprint detection region may lead to unintended patterns (e.g., moire and a light reflecting pattern) that can be visually recognized.
Data Source
AI summary
According to an aspect, a fingerprint detection device includes: a substrate; a plurality of drive electrodes provided on one surface side of the substrate and arranged in a first direction; and a plurality of detection electrodes provided on the one surface side and arranged in a second direction intersecting the first direction. The detection electrodes intersect the drive electrodes in a normal direction of the substrate. Each of the detection electrodes includes: a plurality of first line portions; a plurality of second line portions extending in a direction intersecting the first line portions; and a plurality of bent portions each connecting one of the first line portions and one of the second line portions adjacent to the one of the first line portions to each other.