Under-Display Biometric Sensor Layout for Higher Light SNR
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Solution Overview
Problem
Conventional biometric sensors in electronic devices face challenges with signal-to-noise ratio degradation due to stray and ambient light interference, leading to reduced sensitivity and accuracy in fingerprint recognition, especially in limited device housing where space is a constraint.
Innovation Solution
The integration of an optical sensor under a display panel with a light conditioning layer that includes a collimator and an optical filtering film, which filters out stray light and ambient light interference, enhancing the signal-to-noise ratio of incident light and improving image resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If biometric sensors are stacked with other components (e.g., display panels) inside device housing, then surface space utilization is improved, but signal-to-noise ratio of received light deteriorates due to increased distance from biometric objects and stronger interference from stray light and ambient light
Solution Approach 1:
A light conditioning layer is introduced as an intermediary component between the optical sensor and the display panel. This layer includes a collimator structure with microlens arrays that conditions the light path, filtering and directing light to improve the signal-to-noise ratio while allowing the stacked configuration to maintain surface space efficiency
Solution Approach 2:
The light conditioning layer applies localized optical processing at different positions. The collimator structure has varying lens densities and focal lengths in different regions to selectively enhance signal from the biometric object while suppressing stray light and ambient light interference in specific directional zones
2Ease of manufacture
If conventional integration methods are used, then device housing integration is simplified, but image quality deteriorates due to blurred fingerprint images from degraded signal-to-noise ratio
Solution Approach 1:
The light conditioning layer is integrated with the display panel structure, merging the optical conditioning function with the existing display components. The collimator microlens arrays are formed using the same thin-film deposition and patterning processes as the display panel, enabling combined manufacturing without separate assembly steps
Solution Approach 2:
The light conditioning layer serves as an intermediary that bridges the conventional display panel structure and the optical sensor requirements. It maintains compatibility with standard manufacturing processes while introducing the necessary optical filtering and collimation functions to improve image quality
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 configuration enhances the signal-to-noise ratio of incident light, resulting in sharper and more accurate biometric images, effectively addressing the limitations of conventional biometric sensors in electronic devices by improving light conditioning and reducing noise interference.
Implementation Method 1
an optical filtering film, which filters out stray light and ambient light interference, enhancing the signal-to-noise ratio of incident light
Implementation Method 2
a light conditioning layer that includes a collimator and an optical filtering film
Data Source
AI summary
A display apparatus includes a display layer including a plurality of light emitting pixels, a blocking layer including a plurality of openings disposed under the sensing region, a light conditioning layer under the blocking layer, and an image sensing layer under the light conditioning layer. In a top view of the display apparatus, the portion of the light emitting pixels within the sensing region are arranged in columns, the openings of the blocking layer are arranged in columns, and the columns of the openings are interleaved with the columns of the light emitting pixels.