Under-Display Fingerprint Sensor Light Blocking for Stray Light Control
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Solution Overview
Problem
Existing under-screen fingerprint identification technologies face challenges in effectively filtering stray light, which affects the performance of fingerprint imaging and requires larger space for lens supports, making it difficult to improve fingerprint identification accuracy while maintaining device size constraints.
Innovation Solution
An optical fingerprint apparatus with a light blocking layer above the edge region of the fingerprint sensor chip is used to block stray light, while maintaining a thin design by using a hollow structure with an opening to allow useful light signals to reach the sensing array, and a filter layer is applied to reduce interference light, enhancing fingerprint identification performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lens support is disposed above a fingerprint sensor to block stray light, then fingerprint identification performance is improved, but the device volume increases and space requirements are higher
Solution Approach 1:
The patent employs a thin film light blocking layer with light blocking patterns formed directly on the fingerprint sensor chip. This thin film structure effectively blocks stray light while maintaining a compact form factor, eliminating the need for bulky lens supports and reducing overall device volume.
Solution Approach 2:
The patent extracts the light blocking function from a separate lens support structure and integrates it directly into the fingerprint sensor chip through light blocking patterns. This integration removes the need for additional supporting structures, reducing device volume while maintaining stray light blocking effectiveness.
2Measurement precision
If a lens support is used to block stray light, then fingerprint imaging quality is improved, but the structural complexity increases
Solution Approach 1:
The patent merges the light blocking function with the fingerprint sensor chip structure by forming light blocking patterns directly on the chip. This integration combines multiple functions into a single component, reducing structural complexity while maintaining imaging quality.
Solution Approach 2:
The fingerprint sensor chip is designed to serve multiple functions: fingerprint sensing and stray light blocking. The light blocking patterns are integrated into the chip structure, making the chip a multi-functional component that eliminates the need for separate light blocking structures.
3Length of stationary object
If the optical fingerprint apparatus is designed to be thin, then device thickness is reduced, but the ability to filter stray light is compromised
Solution Approach 1:
The patent uses a thin film light blocking layer with optimized light blocking patterns that provide effective stray light filtering within a minimal thickness. The thin film structure maintains the compact design while the patterned configuration ensures adequate light blocking performance.
Solution Approach 2:
The light blocking patterns are strategically positioned in specific regions where stray light interference occurs most. By concentrating light blocking material only where needed rather than using a uniform thick layer, the patent achieves effective stray light filtering while maintaining thin overall device profile.
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 filters stray light, improves fingerprint identification accuracy, and reduces the overall thickness of the optical fingerprint apparatus, addressing the space constraints and performance issues of existing technologies.
Implementation Method 1
a light blocking layer 321 formed on an upper surface of an edge region of the optical fingerprint chip 310, where the light blocking layer 321 partially blocks the edge region of the optical fingerprint chip 310
Implementation Method 2
a filter layer is applied to reduce interference light, enhancing fingerprint identification performance
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~6
AI summary
Provided are an optical fingerprint apparatus and an electronic device, applied to an electronic device having a display screen, where the optical fingerprint apparatus is configured to be disposed under the display screen, and the optical fingerprint apparatus includes: an optical fingerprint chip including a sensing array having a plurality of optical sensing units, where the sensing array is configured to receive a fingerprint light signal returned from a finger above the display screen, and the fingerprint light signal is used to obtain a fingerprint image of the finger; and a light blocking layer formed on an upper surface of an edge region of the optical fingerprint chip, where the light blocking layer partially blocks the edge region of the optical fingerprint chip and does not block a sensing region of the optical fingerprint chip, and the light blocking layer is configured to block interference light entering the sensing array from the edge region of the optical fingerprint chip, where the sensing region is a region where the sensing array is located.