Optical Fingerprint Module Lateral Lighting Design
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Solution Overview
Problem
Conventional optical fingerprint identification modules are costly and bulky, with impaired imaging quality due to inefficient light utilization and larger sensitive areas required for pressing-type designs, which affects their competitiveness in the market.
Innovation Solution
An optical fingerprint identification module with a multilevel design featuring a light-guiding diffusion layer, a light-collecting reflective layer, and an optical tunnel structure that enhances light utilization efficiency by diffusing, reflecting, and guiding light beams to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pressing-type optical fingerprint identification module is used to provide intuitive operation, then ease of operation is improved, but device thickness and cost increase due to larger sensitive area requirements
Solution Approach 1:
The patent transitions from conventional top-down lighting to lateral (side) lighting geometry. The light source is positioned at the side of the module rather than above, changing the spatial dimension of light delivery. This geometric transformation enables more efficient light utilization within a thinner profile while maintaining the pressing-type operation interface.
Solution Approach 2:
The patent introduces a light guide plate as an intermediary component between the lateral light source and the fingerprint sensing area. This mediator distributes light laterally through the module thickness, enabling uniform illumination of the fingerprint ridge/valley structure without requiring a large sensitive area, thus reducing overall module thickness.
2Ease of manufacture
If conventional light sources are used in optical fingerprint modules, then manufacturing is simple, but light utilization efficiency is poor leading to impaired image quality
Solution Approach 1:
The light guide plate serves as a mediator that transforms direct light from simple LED sources into distributed lateral illumination. This intermediary component efficiently directs light through the module, improving light utilization and enhancing the contrast between fingerprint ridges and valleys without requiring complex or expensive light sources.
Solution Approach 2:
The patent replaces conventional top-down optical paths with a lateral lighting mechanism guided by the light guide plate. This substitution optimizes the optical path geometry to improve light distribution and fingerprint image contrast while maintaining manufacturing simplicity through the use of standard LED components.
3Measurement precision
If a larger sensitive area is used to capture complete fingerprint images in one press, then imaging completeness is improved, but module size and cost increase
Solution Approach 1:
The patent employs lateral lighting that illuminates the fingerprint structure from the side, enabling effective imaging within a smaller footprint. This geometric change in light delivery allows complete fingerprint capture without requiring a proportionally larger sensitive area, thus reducing overall module size.
Solution Approach 2:
The light guide plate mediates light distribution to enhance imaging efficiency within a compact area. By laterally distributing light through the module thickness, it maximizes the utilization of the sensitive area, enabling complete fingerprint capture without increasing module dimensions.
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 module achieves enhanced light utilization and fingerprint image quality, reducing thickness and cost while maintaining intuitive operation, thus improving competitiveness.
Implementation Method 1
the light beams are guided or refracted to the press plate 10 by the light diffusion plate 13
Implementation Method 2
the light beams are guided or refracted to the press plate 10 by the light diffusion plate 13
Implementation Method 3
collected and reflected by the light-collecting reflective layer
Data Source
AI summary
An optical fingerprint identification module includes a casing, an image pickup assembly, a light-guiding diffusion layer, a light-collecting reflective layer, a press plate, a light source and an optical tunnel structure. The optical tunnel structure is located under the press plate and located over the image pickup assembly. The optical tunnel structure is penetrated through the light-collecting reflective layer and a part of the light-guiding diffusion layer. After a light beam emitted by the light source is introduced into the light-guiding diffusion layer, the light beam is guided and diffused by the light-guiding diffusion layer and collected and reflected by the light-collecting reflective layer. Consequently, the light beam is transferred between the light-guiding diffusion layer and the light-collecting reflective layer. After the light beam is irradiated on the press plate through the optical tunnel structure, the light beam is reflected to the image pickup assembly.