Fingerprint Sensor Under Display Panel for Ultrasonic Sensing
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Solution Overview
Problem
Conventional display devices with fingerprint recognition capabilities face challenges such as reduced display area ratio due to the placement of fingerprint sensors, sensitivity issues with ultrasonic signals, electromagnetic interference, and image quality degradation, including shadow-mura and heat radiation problems.
Innovation Solution
An electroluminescence display panel with an ultrasonic fingerprint sensor placed under the rear surface, utilizing a support substrate, light-shield member, and adhesive members to minimize bezel width, enhance signal sensitivity, and reduce electromagnetic interference while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fingerprint sensor is attached to the periphery of the liquid crystal display panel, then the fingerprint recognition function is supported, but the display area ratio is reduced due to the increased bezel width
Solution Approach 1:
The fingerprint sensor is relocated from the peripheral bezel area (2D plane) to the rear surface of the display panel (3D space), allowing the display area to be maximized while maintaining fingerprint recognition functionality through ultrasonic signal transmission through the display panel
2Area of stationary object
If the ultrasonic fingerprint sensor is placed under the rear surface of the electroluminescence display panel, then the display area ratio is maximized, but the sensitivity of the ultrasonic signal is reduced due to electromagnetic interference and stress on the substrate
Solution Approach 1:
A light-shield member is introduced as an intermediary component between the ultrasonic fingerprint sensor and the electroluminescence display panel. This light-shield member serves dual functions: shielding the sensor from light that could cause image retention, and providing mechanical support to reduce stress on the display panel substrate, thereby maintaining ultrasonic signal sensitivity
3Length of stationary object
If the fingerprint sensor is disposed on the rear surface of the electroluminescence display panel, then the bezel width is minimized, but image quality degradation occurs due to shadow-mura and heat radiation issues
Solution Approach 1:
The light-shield member acts as a mediator that prevents harmful light from reaching the display panel, thereby preventing shadow-mura and image retention defects while allowing the fingerprint sensor to be positioned on the rear surface for minimal bezel width
Solution Approach 2:
The light-shielding function is extracted from the display panel structure itself and implemented as a separate light-shield member, allowing the display panel to maintain its image quality characteristics while the fingerprint sensor is positioned on the rear surface
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 increases the display area ratio, improves fingerprint recognition speed and sensitivity, and minimizes image quality degradation by shielding electromagnetic interference and optimizing the placement of components.
Implementation Method 1
an ultrasonic sensor is disposed under the rear surface of the electroluminescence display panel... an ultrasonic signal can be used for recognizing a fingerprint through an electroluminescence display panel
Implementation Method 2
a light-shield member between the support substrate and the fingerprint sensor, the light-shield member configured to shield the fingerprint sensor from light
Implementation Method 3
an electroluminescence display panel including an electroluminescence element... capable of displaying a superior image quality
Data Source
AI summary
Disclosed is a display device. The display device comprising an electroluminescence display panel including an area capable of sensing a fingerprint, a display area, and a non-display area adjacent to the display area, a support substrate configured to support the electroluminescence display panel, a fingerprint sensor under the support substrate, and a light-shield member, under the support substrate, configured to light shield the fingerprint sensor.