Under-Display Fingerprint Sensor Light Path Directing Structure
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Solution Overview
Problem
Traditional capacitive fingerprint identification technologies face limitations in penetrating ability, making them unsuitable for under-display applications, while optical fingerprint identification technologies struggle to maintain imaging quality with reduced thickness.
Innovation Solution
A fingerprint identification apparatus featuring a light path directing structure with a micro-lens array and light shielding layers that directs obliquely incident light signals to an optical fingerprint sensor, improving imaging contrast ratio and reducing thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the light path directing structure is reduced to meet terminal device thinness requirements, then the overall thickness of the optical fingerprint identification apparatus is reduced, but the imaging effect of the optical fingerprint sensor deteriorates
Solution Approach 1:
The patent transforms the traditional vertical light path into an oblique light path by introducing a light path directing structure with specific angular geometry. This dimensional change in light propagation direction enables the system to achieve both thinness and effective imaging by utilizing oblique incidence reflection from the finger surface, which provides sufficient optical path length and imaging contrast within a reduced thickness configuration
Solution Approach 2:
The patent optimizes specific geometric parameters of the light path directing structure, including the oblique angle (preset between 5° to 35°), hole apertures in light shielding layers, and distances between layers. By carefully adjusting these parameters, the system achieves the dual goal of reduced thickness while maintaining or improving imaging effect through optimized oblique light path geometry
2Device complexity
If a traditional capacitive fingerprint identification technology is used, then the structure is simple, but the penetrating ability is limited and it cannot be applied to under-display fingerprint identification systems
Solution Approach 1:
The patent replaces the capacitive sensing mechanism with an optical detection system. Instead of measuring electrical capacitance changes, the system uses light emission, oblique incidence reflection from the finger surface, and optical detection to capture fingerprint information. This substitution enables under-display application by utilizing optical properties that can penetrate through the display screen and glass layers
Solution Approach 2:
The patent introduces a light path directing structure as an intermediary component between the light source and the optical fingerprint sensor. This intermediary structure, containing oblique light pipes or prisms and light shielding layers with holes, mediates the light path to achieve oblique incidence reflection, enabling the system to overcome the limitations of direct vertical transmission and achieve effective fingerprint detection under the display
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 enhances imaging contrast and reduces the thickness of the fingerprint identification apparatus, enabling effective under-display fingerprint detection while maintaining improved imaging quality.
Implementation Method 1
a micro-lens array including a plurality of micro-lenses, where each of the plurality of micro-lenses is configured to converge the received light signal
Implementation Method 2
directing a light signal that is obliquely incident on a finger above the display screen at a preset angle and reflected by the finger to the optical fingerprint sensor
Data Source
AI summary
The embodiments of the present application provide a fingerprint identification apparatus, which has a smaller thickness and a better imaging effect at the same time. The fingerprint identification apparatus includes: a light path directing structure disposed between a display screen and an optical fingerprint sensor for directing a light signal that is obliquely incident on a finger above the display screen at a preset angle and reflected by the finger to the optical fingerprint sensor; and the optical fingerprint sensor disposed below the light path directing structure for detecting the received light signal.