Three-Lens Fingerprint Module with Aspherical Surfaces
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Solution Overview
Problem
Existing optical fingerprint identification modules based on collimated light have limited resolving power, especially at low temperatures, and struggle to meet the increasing size restrictions and field of view requirements of electronic devices, leading to reduced accuracy and identification speed.
Innovation Solution
A lens assembly comprising three lenses with at least one aspherical surface, arranged with different optical power distribution, is integrated into a fingerprint identification module to enhance resolving power, meet size restrictions, and improve accuracy and speed of optical fingerprint identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a collimated light optical system is used, then the structure is simple and easy to manufacture, but the resolving power is limited especially at low temperatures
Solution Approach 1:
The optical system is divided into three separate lens elements with different optical powers (positive, negative, positive) arranged in sequence. Each lens element contributes to the overall resolving power while maintaining manufacturability through standardized lens design and assembly processes.
Solution Approach 2:
The patent employs a composite lens system combining multiple lens elements with different optical properties (different optical powers and aspherical surfaces) to achieve superior resolving power that cannot be obtained with a single collimated light system, while still using conventional optical materials that are easy to manufacture.
2Volume of moving object
If the lens assembly size is reduced to meet electronic device size restrictions, then the device becomes more compact, but the field of view and resolving power deteriorate
Solution Approach 1:
At least one lens element incorporates an aspherical surface instead of a traditional spherical surface. This aspherical design allows for better control of light rays, improving resolving power and field of view while maintaining a compact lens assembly size suitable for modern electronic devices.
Solution Approach 2:
Different lens elements are assigned different optical powers (positive, negative, positive) to optimize specific regions of the optical path. This localized optimization of optical properties allows the compact assembly to achieve high resolving power across the entire field of view.
3Volume of moving object
If the lens assembly size is reduced to meet electronic device size restrictions, then the device becomes more compact, but the field of view becomes narrower
Solution Approach 1:
The three-lens segmented design with alternating optical powers enables the compact assembly to capture and focus light from a wider angular range, expanding the field of view while maintaining small overall dimensions suitable for mobile devices.
Solution Approach 2:
The aspherical surfaces in at least one lens element correct for off-axis ray deviations, enabling a wider field of view to be captured and properly focused onto the sensor plane within the compact lens assembly volume.
4Productivity
If identification speed is increased, then the user experience is improved, but accuracy may be compromised
Solution Approach 1:
The mechanical collimated light system is replaced with a lens-based imaging system that provides superior resolving power. This enables faster identification speeds through more efficient light gathering and imaging, while the enhanced optical resolution maintains or improves identification accuracy even at higher speeds.
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 lens assembly improves the resolving power of optical fingerprint identification, enhances accuracy, and accelerates identification speed while maintaining a large field of view, even under tight size constraints, effectively addressing the limitations of existing modules.
Implementation Method 1
a lens assembly comprising three lenses 110, 120, 130... The first lens 110 with negative optical power... The second lens 120 with positive optical power... The third lens 130 with positive optical power
Implementation Method 2
three lenses with at least one aspherical surface... 1:1 magnification in a paraxial region... improve a resolving power of existing optical fingerprint identification
Data Source
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AI summary
Embodiments of the present application relate to a lens assembly and a fingerprint identification module. The lens assembly includes a first lens, a second lens, and a third lens in sequence from an object side to an image side, and at least one of two surfaces of the first lens, two surfaces of the second lens, and two surfaces of the third lens is aspherical. The first lens is a negative optical power lens; the second lens is a positive optical power lens; and the third lens is a positive optical power lens. The lens assembly satisfies: 0.5 < |Y'(f ∗ TTL)| < 0.8, where Y' represents the maximum image height on a surface of the image side, f represents a focal length of the lens assembly, and TTL represents a distance from the object side to the image side. The lens assembly and the fingerprint identification module in the embodiments of the present application can effectively improve accuracy and identification speed of optical fingerprint identification.