Optical Fingerprint Sheet with Light Guide Plate
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Solution Overview
Problem
Existing optical fingerprint recognition methods face challenges in providing high contrast and compatibility with portable devices, especially due to issues with light scattering and total reflection, which affect the accuracy and size of the device.
Innovation Solution
A sheet with a specific interlayer laminate structure featuring a first light control part for total reflection and a second light control part that adjusts light reflection based on the fingerprint pattern, allowing for high contrast fingerprint recognition without interference from adjacent fingerprints, and enabling a large-area sensor without increasing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scattering method is used for optical fingerprint recognition, then fingerprint pattern detection is enabled, but the light quantity is insufficient and contrast is lowered
Solution Approach 1:
The patent introduces a light guide plate as an intermediary component between the light source and the fingerprint contact portion. This light guide plate guides and concentrates light to the fingerprint contact area, ensuring sufficient light quantity reaches the sensor while enabling effective fingerprint pattern detection through the scattering method
Solution Approach 2:
The patent modifies the optical parameters by using a light guide plate with specific refractive index and optical properties. This changes the light propagation characteristics, allowing sufficient light to be delivered to the fingerprint contact portion while maintaining the scattering method's ability to detect fingerprint patterns
2Measurement precision
If the scattering method is used for optical fingerprint recognition, then fingerprint pattern detection is enabled, but the light path overlaps with the original light source path causing contrast reduction
Solution Approach 1:
The patent segments the optical path into distinct components: the light guide plate handles light delivery, while the fingerprint contact portion and sensor handle light detection. This segmentation separates the illumination path from the detection path, preventing overlap and maintaining contrast for accurate fingerprint pattern detection
3Illumination intensity
If the total reflection method is used, then greater light quantity is secured, but adjacent fingerprint lights interfere with each other lowering contrast
Solution Approach 1:
The patent applies local quality by using a light guide plate that provides localized light control. The light guide plate directs light specifically to the contacted fingerprint area, ensuring sufficient light quantity while preventing light from adjacent fingerprints from interfering with each other's detection, thus maintaining high contrast
4Reliability
If conventional total reflection method is used, then fingerprint recognition is achieved, but device size increases due to separate sensor or prism installation
Solution Approach 1:
The patent merges the light guide function and the fingerprint sensing function into a single integrated structure. The light guide plate serves both as the illumination element and as the fingerprint contact surface, eliminating the need for separate sensors or prisms and thereby reducing device size while maintaining reliable fingerprint recognition
5Reliability
If conventional total reflection method is used, then fingerprint recognition is achieved, but compatibility with large area display portable devices is poor due to limited input and output structures
Solution Approach 1:
The patent creates a universal structure where the light guide plate serves multiple functions: it acts as the fingerprint contact surface, the light delivery mechanism, and the structural interface for both input (fingerprint placement) and output (light detection). This multi-functional design improves compatibility with various portable devices including those with large area displays
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 provides high contrast fingerprint recognition, supports multiple fingerprint patterns without interference, and maintains light quantity irrespective of contamination, allowing for a compact and efficient optical fingerprint recognition system.
Implementation Method 1
a first light control part which provides light which is always totally reflected only in a specific interlayer laminate structure among sheet constructions
Implementation Method 2
a second light control part which provides light whose total reflection is determined according to a fingerprint pattern in contact with the surface layer of the sheet by changing a part of the light provided from the first light control part and totally reflected in the specific interlayer laminate structure at a predetermined angle
Data Source
Figure 1~2
AI summary
The present application relates to a sheet used for optical fingerprint recognition, and a device comprising the same. According to one example of the present application, it is possible to provide a sheet which has excellent user identification or authentication capability through a fingerprint and can be applied to a large area display device to recognize a plurality of fingerprint patterns without being influenced by each other, and a device thereof.