Optical Fingerprint Module Using Total Internal Reflection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fingerprint identification technologies face challenges in integrating capacitive fingerprint identification modules into display regions of devices due to high touch precision and dimensional requirements, leading to increased costs and process difficulties, which degrade user experience by reducing the proportion of fingerprint identification regions.
Innovation Solution
A fingerprint identification module incorporating a transparent substrate with emission and receiving parts, where light sources emit light at specific angles for total reflection, allowing the module to be moved in synchronization, enabling accurate fingerprint detection without interfering with display functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a capacitive fingerprint identification module is integrated into a display region, then the fingerprint identification area proportion is improved, but the touch precision requirement and dimensional constraint increase
Solution Approach 1:
The patent replaces the capacitive sensing mechanism with an optical detection system. Light sources emit light that undergoes total internal reflection within the transparent substrate, and receivers detect the reflected light patterns to identify fingerprints. This optical approach eliminates the need for high-precision capacitive touch sensing while enabling fingerprint identification across the entire display region.
Solution Approach 2:
The patent changes the detection parameter from electrical capacitance to optical properties (light reflection and transmission). By utilizing the optical characteristics of the transparent substrate and the finger's interaction with light, the system achieves fingerprint identification without the dimensional and precision constraints of capacitive sensing.
2Area of stationary object
If a capacitive fingerprint identification module is integrated into a display region, then the fingerprint identification area proportion is improved, but the process difficulty and cost increase
Solution Approach 1:
The transparent substrate serves multiple functions: it acts as the display cover, the optical waveguide for fingerprint detection, and the structural component. This multi-functionality eliminates the need for separate capacitive sensing layers and complex integration processes, thereby reducing manufacturing difficulty and cost while enabling full-display fingerprint identification.
Solution Approach 2:
The optical system replaces the complex capacitive sensing infrastructure, simplifying the manufacturing process. The same transparent substrate used for display protection also serves as the optical medium for fingerprint detection, reducing the number of manufacturing steps and associated costs.
3Measurement precision
If light is incident at a specific angle for total reflection, then the optical detection accuracy is improved, but the structural complexity increases
Solution Approach 1:
The patent creates an optical environment where total internal reflection occurs uniformly across the transparent substrate by controlling the incident angle of light. This uniform optical condition enables accurate fingerprint detection without requiring complex structural modifications, as the optical properties of the substrate itself are utilized.
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 solution allows for effective fingerprint identification in the display region, enhancing user experience by increasing the proportion of fingerprint identification area while maintaining low costs and process simplicity through optical principles.
Implementation Method 1
light emitted from the light sources is incident in the transparent substrate at a first angle θ1 so as to be propagated in the transparent substrate in a total reflection form
Implementation Method 2
θ2 satisfies: sinθ2＝sinθ1/n wherein L is a width of a finger, D is a thickness of the transparent substrate, and the second angle θ2 is an angle between the light incident into the transparent substrate and before a first total reflection is occurred and a normal line of the incident surface
Data Source
AI summary
A fingerprint identification module, a fingerprint identification device and a display device are provided. The fingerprint identification module includes a transparent substrate, an emission part, a receiving part and a moving part, wherein the emission part and the receiving part are provided adjacent to opposite edges of the transparent substrate, and the emission part and the receiving part are fixed on the moving part, wherein, light emitted from the light sources is incident in the transparent substrate at a first angle θ1 so as to be propagated in the transparent substrate in a total reflection form; the transparent substrate is provided with an adjusting structure configured to allow the light to exit; the receiving part is configured to receive the light exiting through the adjusting structure; and the moving part is configured to allow the emission part and the receiving part to be moved.