Directional Light Unit for Fingerprint Recognition in Display Devices
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Solution Overview
Problem
Conventional optical fingerprint sensors require bulky and complex devices for accurate fingerprint recognition, making them unsuitable for integration with portable display devices and limiting their ability to recognize fine fingerprints due to the use of diffuse light with low directionality.
Innovation Solution
A display device incorporating a directional light unit that refracts and reflects light at specific angles for total internal reflection, allowing for accurate fingerprint recognition without a bulky optical apparatus, and is suitable for display panels with reduced bezel areas by positioning light-incident elements and sources outside the display area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional optical fingerprint sensor uses diffuse light, then the structure can be simplified, but the fingerprint recognition accuracy deteriorates
Solution Approach 1:
The patent changes the light parameter from diffuse to directional by introducing a directional light unit with specific refractive indices and total internal reflection angles. This parameter change enables accurate fingerprint pattern detection while maintaining a simple integrated structure without bulky optical devices.
Solution Approach 2:
The display device integrates multiple functions: the display panel serves as both the display area and the fingerprint recognition area. The directional light unit is integrated into the display structure, allowing the same device to perform both display and biometric authentication functions without requiring separate bulky optical components.
2Measurement precision
If bulky optical device is used for accurate fingerprint recognition, then the recognition accuracy is improved, but the device size increases
Solution Approach 1:
The patent merges the fingerprint sensor with the display panel structure. The directional light unit, light source, and optical sensor are integrated into the display device layers, eliminating the need for separate bulky optical devices while maintaining accurate fingerprint recognition capability.
Solution Approach 2:
The patent transitions from a three-dimensional bulky optical device to a two-dimensional planar integration within the display panel. The directional light unit and optical sensor are arranged in layers within the display structure, reducing the overall device volume while maintaining functionality.
3Area of stationary object
If conventional optical fingerprint sensor is integrated into display device, then the display area can be increased, but the fingerprint recognition accuracy deteriorates
Solution Approach 1:
The patent applies local quality by introducing a directional light unit with specific optical properties (refractive index, total internal reflection angle) at the fingerprint recognition area. This localized optimization ensures high-resolution fingerprint pattern detection while the rest of the display panel maintains its display function with maximized area.
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
Enables accurate recognition of fine fingerprints using a directional light unit and optical sensor, allowing for integration with display panels having increased display areas and reduced bezel areas without the need for complex structures.
Implementation Method 1
refracting the light supplied from the light source at a first angle to travel from the non-display area to the display area in total internal reflection
Implementation Method 2
reflecting some of the totally internally reflected light at a second angle, and then supplying a light reflected by an object having biometric information to the display panel
Data Source
AI summary
Disclosed herein is a display device capable of recognizing a fine fingerprint without a complicated construction such as a bulky optical device. The display device comprises a display panel having a display area and a non-display area outside the display area; a light source disposed below the non-display area of the display panel to irradiate the display panel with light; a directional light unit disposed on an upper portion of the display panel, refracting the light supplied from the light source at a first angle to travel from the non-display area to the display area in total internal reflection, reflecting some of the totally internally reflected light at a second angle, and then supplying a light reflected by an object having biometric information to the display panel; and an optical sensor disposed below the display panel and receiving the light exited from the directional light unit.