Under-Display Fingerprint Optics With Offset Pixels for Dry Fingers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing under-screen optical fingerprint identification technology faces challenges in reducing the thickness of the optical fingerprint module while improving the identification effect on dry fingers, due to the large size of the micro-lens array affecting the photosensitive regions and increasing the processing difficulty and cost of the light path.
Innovation Solution
The proposed solution involves a fingerprint detection apparatus with a micro-lens array where the optical sensing pixels have their photosensitive regions offset from the center, and a light shielding layer with holes to converge oblique light signals from multiple directions, reducing the thickness and exposure time of the module while enhancing the identification effect, especially for dry fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the micro-lens array is located directly above or obliquely above the optical sensing pixel array with one micro-lens corresponding to one optical sensing pixel, then the duty cycle of the photosensitive region is improved, but the thickness of the optical fingerprint module becomes relatively large and the processing difficulty and cost of the light path increase
Solution Approach 1:
The patent changes the spatial arrangement from a direct one-to-one vertical correspondence to an oblique angular arrangement. Multiple optical sensing pixels are arranged to receive light from different angles through a single micro-lens, transforming the problem from a vertical thickness issue to an angular distribution solution, thereby reducing module thickness while maintaining photosensitive region efficiency
Solution Approach 2:
The patent segments the light reception function by dividing it into multiple angular channels. Instead of one micro-lens focusing to one pixel vertically, a single micro-lens distributes light from multiple angles to multiple pixels, segmenting the optical path processing and reducing the required thickness
2Productivity
If the micro-lens array is located directly above or obliquely above the optical sensing pixel array, then the duty cycle of the photosensitive region is improved, but the processing difficulty and cost of the light path increase
Solution Approach 1:
The patent changes the optical parameters by introducing specific oblique angles for light reception. By defining precise angular relationships between the micro-lens, light source, and sensor array, the system transforms a complex variable light path into a parameterized optical system with fixed angular relationships, simplifying processing while maintaining high duty cycle
3Productivity
If the optical sensing pixel array is arranged with photosensitive regions in center positions, then the duty cycle is improved, but the identification effect on dry fingers becomes poor
Solution Approach 1:
The patent introduces asymmetry in the optical path arrangement to address dry finger detection. By positioning photosensitive regions at offset positions rather than center positions, and arranging light reception at specific oblique angles, the system creates an asymmetric optical configuration that enhances light penetration and scattering effects necessary for detecting dry fingerprint patterns
4Length of stationary object
If the thickness of the optical fingerprint module is reduced, then the processing difficulty and cost are reduced, but the field angle and field of view may be limited
Solution Approach 1:
The patent implements a dynamic angular distribution scheme where multiple optical sensing pixels are configured to receive light from different oblique angles. This dynamic angular arrangement allows the thin module to capture a wide field of view by distributing light reception across multiple angular channels, compensating for the reduced thickness through angular diversity
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 design reduces the thickness and cost of the fingerprint detection apparatus, improves the robustness, field angle, and field of view, leading to enhanced fingerprint identification performance, particularly on dry fingers.
Implementation Method 1
one micro-lens configured to be disposed under the display screen... After being converged by the one micro-lens, oblique light signals in multiple directions reflected from a finger above the display screen are respectively transmitted to photosensitive regions of the plurality of optical sensing pixels
Implementation Method 2
at least one light shielding layer disposed between the one micro-lens and the plurality of optical sensing pixels, each of the at least one light shielding layer being provided with a hole corresponding to the plurality of optical sensing pixels
Implementation Method 3
a center position of a photosensitive region of each of the plurality of optical sensing pixels being offset relative to a center position of the same optical sensing pixel... can further increase an image distance of the one micro-lens in the case that a vertical distance between the one micro-lens and the plurality of optical sensing pixels is constant
Data Source
AI summary
A fingerprint detection apparatus includes a plurality of fingerprint detection units distributed in an array or disposed alternately, and each of the plurality of fingerprint detection units includes: one micro-lens configured to be disposed under the display screen; a plurality of optical sensing pixels, a center position of a photosensitive region of each of the plurality of optical sensing pixels being offset relative to a center position of the same optical sensing pixel; and at least one light shielding layer disposed between the one micro-lens and the plurality of optical sensing pixels, each of the at least one light shielding layer being provided with a hole corresponding to the plurality of optical sensing pixels. By offsetting photosensitive regions of the optical sensing pixels, the thickness of an optical fingerprint module can be reduced on the basis of improving a fingerprint identification effect on a dry finger.