Holographic Optical Element for Fingerprint Sensor Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fingerprint sensors integrated with liquid crystal displays face challenges due to the structure of the backlight unit, which results in reduced reception efficiency and makes it difficult to place the sensor below the screen area, while existing solutions that integrate sensors within the viewing area of electroluminescent displays often compromise on bezel area reduction and design flexibility.
Innovation Solution
A fingerprint sensor is integrated into an electroluminescent display using a directional light source device with a holographic optical element, where a light entering element and a light exiting element are used to refract and diffuse light within a transparent substrate, allowing for fingerprint detection without visible interference, and a recording and reconstruction method for the holographic optical element enables efficient visual information reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fingerprint sensor is disposed between a display panel and a backlight unit of a liquid crystal display, then the fingerprint sensor can be integrated into the display structure, but the fingerprint sensor becomes visible in the screen area and reception efficiency is reduced due to air gaps in the prism sheet
Solution Approach 1:
The patent transitions from a liquid crystal display structure to an electroluminescent display structure, fundamentally changing the dimensional arrangement of components. The fingerprint sensor is positioned on the display panel surface rather than between the panel and backlight, eliminating the visibility and reception efficiency issues caused by the prism sheet air gaps.
Solution Approach 2:
The patent introduces a holographic optical element as an intermediary component that reconstructs visual information while allowing the fingerprint sensor to function effectively. This intermediary element enables both the display function and the fingerprint sensing function to coexist without interfering with each other's performance.
2Reliability
If a fingerprint sensor is disposed on the display panel surface, then the sensor is not visible in the screen area and reception efficiency is improved, but the bezel area increases and design flexibility is reduced
Solution Approach 1:
The patent makes the display panel surface serve multiple functions: it acts as both the display surface and the fingerprint sensing surface. By integrating the fingerprint sensor into the display panel structure and using the holographic optical element to manage light paths, the system eliminates the need for separate bezel areas or home buttons, achieving multi-functionality in a single component.
Solution Approach 2:
The holographic optical element creates a virtual image that copies the visual information, allowing the display to maintain its visual output while the physical sensor surface is used for fingerprint detection. This copying mechanism enables the sensor to be effectively 'hidden' within the display surface without requiring additional bezel space.
3Productivity
If a holographic optical element is used to reconstruct visual information, then light extraction efficiency is improved and the fingerprint sensor can be integrated, but the device complexity increases
Solution Approach 1:
The patent changes the optical parameters by introducing the holographic optical element, which modifies light extraction efficiency and enables the fingerprint sensor integration. The holographic element alters the light propagation characteristics, allowing for improved efficiency while managing the complexity through optimized optical design.
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
This solution allows for efficient fingerprint sensing on the display screen, reducing bezel area requirements and enhancing design flexibility, while maintaining the aesthetic and functional integrity of the display by utilizing holographic optical elements to reconstruct visual information and improve light extraction efficiency.
Implementation Method 1
a light entering element irradiating light from a light source onto the transparent substrate
Implementation Method 2
A recording and reconstruction method of a holographic optical element for the fingerprint sensor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A fingerprint sensor integrated display using a holographic optical element and a recording and reconstruction method of the holographic optical element are disclosed. The fingerprint sensor integrated display includes a display panel on which an input image is displayed, a transparent substrate disposed on the display panel, and a light entering element configured to irradiate light from a light source onto the transparent substrate. A particular type of visual information is reconstructed through a holographic element at a location of the light entering element.