Thin Optical Imaging Module for Biometric Apparatus
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Solution Overview
Problem
Conventional dual-mode biometric modules for fingerprint and vein recognition require two separate image sensors and optical paths, leading to increased module volume, cost, and image distortion, with capacitor-type fingerprint sensors being unreliable and expensive.
Innovation Solution
A thin optical imaging module using a glass substrate with an optical prism film and a single image sensor to capture both fingerprint and vein images simultaneously, reducing the optical path volume and minimizing image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate image sensors are used to capture fingerprint and vein images, then the recognition reliability is improved, but the module volume and cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling a single image sensor to perform both fingerprint and vein image capture through the integration of optical prism films and glass substrates with different refractive indices. The optical system is designed to direct different wavelengths of light to the same sensor, allowing one component to fulfill multiple detection functions that traditionally required separate sensors.
Solution Approach 2:
The patent merges the fingerprint detection path and vein detection path into a single optical system. By combining the optical prism films, glass substrates, and image sensor into an integrated structure, the patent reduces the number of separate components while maintaining the capability to capture both fingerprint and vein images simultaneously or sequentially.
2Adaptability or versatility
If a conventional prism is used to provide different optical paths, then the fingerprint and vein images can be captured, but the module thickness increases and image distortion occurs
Solution Approach 1:
The patent employs thin optical prism films instead of bulky conventional prisms. These thin films are integrated with glass substrates to provide the necessary optical path separation for fingerprint and vein detection. The thin-film approach significantly reduces the module thickness while maintaining the functionality of directing light along different paths for different biometric features.
Solution Approach 2:
The patent uses composite optical structures combining optical prism films with glass substrates of different refractive indices. This composite material approach enables effective optical path separation in a thin profile, as the combination of materials with different optical properties allows for precise control of light propagation without requiring thick conventional prism components.
3Adaptability or versatility
If conventional prisms are used for optical path separation, then dual-mode detection is achieved, but image nonlinear deformation occurs
Solution Approach 1:
The patent controls image quality by carefully selecting and matching the refractive indices of the glass substrates and optical prism films. By adjusting these optical parameters, the patent minimizes nonlinear deformation in the captured images while maintaining the ability to separate optical paths for dual-mode detection. The refractive index matching reduces optical aberrations and distortion.
Solution Approach 2:
The patent applies different refractive index characteristics to different regions of the optical system. Specifically, the glass substrate has a refractive index higher than the optical prism film to optimize light propagation in specific areas. This local optimization of optical properties helps maintain image quality and reduce distortion in the fingerprint and vein detection regions.
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 allows for a compact design with improved image recognition speed and reduced costs by integrating the optical prism film and glass substrate, enabling simultaneous capture of fingerprint and vein images with a single image sensor.
Implementation Method 1
the optical theory of total reflection upon an optic prism shall be utilized so as sufficient to increase the degree of recognition upon the ridges and the valleys on the fingerprint
Implementation Method 2
a glass substrate has an optical prism film (prism sheet) attached thereon... Through the single image sensor, the fingerprint image and the vein image can be captured simultaneously in a single action
Data Source
AI summary
A thin optical imaging module of a biometric apparatus includes a first glass substrate, a first optical prism film, a second optical prism film, and an image sensor. The first glass substrate further includes a fingerprint imaging area, a vein imaging area, a contact surface, a reflective interface, and an attaching surface. The first optical prism film adhered to the attaching surface is located under the fingerprint imaging area. The second optical prism film is adhered to a position under the first optical prism film. The image sensor disposed in correspondence to the first glass substrate is located under the attaching surface.