Tilted Light Guide Wall for Uniform Fingerprint Illumination
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Solution Overview
Problem
Conventional optical fingerprint identification apparatuses are complex and costly to assemble, with uneven light distribution from point light sources leading to blurry fingerprint images due to the difficulty in accurately adjusting the relative position of optical components.
Innovation Solution
A fingerprint identification apparatus featuring a light guide device with a tilted side wall that directs light emitted by multiple light-emitting devices to the center, ensuring uniform illumination of the finger, combined with a reflecting device and a protection layer to enhance image clarity and simplify assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a point light source is used without optical processing, then the device structure is simple, but the light distribution is uneven causing blurry fingerprint images
Solution Approach 1:
A light guide device is introduced as an intermediary component between the point light source and the finger. This light guide device includes a light guide plate with a tilted side wall that redirects light, and a light concentrating member that focuses the light. This intermediary structure transforms the simple point light source into a system that provides uniform light distribution across the fingerprint area, improving image clarity without significantly complicating the overall device structure.
Solution Approach 2:
The light guide device changes the spatial parameters of light propagation by using a tilted side wall at a specific angle (30-60 degrees) to redirect light at controlled angles. This parameter change in light direction, combined with the light concentrating member, transforms the concentrated point source light into a distributed illumination pattern that uniformly covers the fingerprint area, thereby improving image quality.
2Reliability
If conventional optical assembly with multiple components is used, then light can be directed to the finger, but the assembly process is complex and costly
Solution Approach 1:
The patent merges multiple optical functions into a single integrated light guide device. The light guide plate, tilted side wall, and light concentrating member are combined into one component that performs light guiding, light redirecting, and light focusing simultaneously. This integration eliminates the need for separate optical components and their complex alignments, significantly simplifying the assembly process while maintaining reliable light transmission to the finger.
Solution Approach 2:
The light guide device serves multiple functions: it guides light from the point source, redirects light at controlled angles through the tilted side wall, concentrates light onto the fingerprint area, and provides structural support. This multi-functionality reduces the number of separate components needed, thereby simplifying manufacturing and assembly while ensuring reliable light transmission.
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 results in a clear fingerprint image and reduces assembly complexity and cost by using a light guide device with a tilted side wall to focus light uniformly onto the finger, improving identification accuracy and ease of manufacturing.
Implementation Method 1
at least a part of the light is refracted by the side wall of the light guide device for propagating to the finger
Implementation Method 2
combined with a reflecting device and a protection layer to enhance image clarity
Data Source
AI summary
A fingerprint identification apparatus including an image capture device, at least one light emitting device and a light guide device is provided. The image capture device has a light reception surface. The at least one light emitting device is disposed beside the image capture device. The light guide device shields the at least one light emitting device and has an opening. The opening of the light guide device exposes the light reception surface of the image capture device. The opening of the light guide device is defined by a side wall of the light guide device. The side wall of the light guide device is tilted relative to the light reception surface of the image capture device. Moreover, a manufacturing method of the fingerprint identification apparatus is also provided.