Side-Type Backlight Module Microstructures for Fingerprint Recognition
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Solution Overview
Problem
The poor light transmittance of liquid crystal displays (LCDs) and limitations in light transmission properties lead to reduced light intensity reaching the fingerprint recognition layer, resulting in poor fingerprint recognition due to diffused and reduced light intensity.
Innovation Solution
A side-type backlight module is introduced, comprising a light guide plate, a reverse prism sheet, and a reflective sheet, with specific microstructures and optical films to enhance light diffusion and uniformity, reducing the thickness of the backlight module while improving light-exit brightness and reducing interference from optical films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional backlight modules with multiple optical films are used, then light diffusion is achieved, but light intensity is reduced and module thickness increases
Solution Approach 1:
The patent combines the light diffusion function and light guiding function into a single integrated light guide plate with microstructures, eliminating the need for separate diffusion films and reducing the number of optical layers. This merging approach maintains light diffusion capability while reducing overall module thickness and preserving light intensity.
Solution Approach 2:
The light guide plate is designed to perform multiple functions simultaneously: it guides light from the edge source, diffuses light through integrated microstructures (prism structures and strip-shaped microstructures), and maintains uniform light distribution. This multi-functionality reduces the need for additional specialized optical films, thereby reducing thickness while maintaining brightness.
2Illumination intensity
If multiple optical films are stacked to improve light diffusion, then uniformity is enhanced, but light intensity reaches the fingerprint recognition layer with reduced strength
Solution Approach 1:
The patent integrates light diffusion microstructures directly into the light guide plate, combining what would traditionally require separate diffusion films into a single component. This reduces the total number of optical films from multiple stacked layers to a more compact integration, preserving light intensity while achieving uniform diffusion.
Solution Approach 2:
The patent extracts the light diffusion function from separate optical films and integrates it into the light guide plate structure itself. By taking out the diffusion function and embedding it in the light guiding component, the system reduces the number of discrete optical films while maintaining effective light diffusion to the fingerprint recognition layer.
3Measurement precision
If conventional prism structures are used, then light direction control is achieved, but light leakage occurs and fingerprint recognition accuracy deteriorates
Solution Approach 1:
The patent employs different microstructure types (prism structures and strip-shaped microstructures) at different locations and orientations within the light guide plate. These local variations in microstructure geometry and arrangement are optimized to control light direction precisely and prevent light leakage in specific areas, thereby improving fingerprint recognition accuracy without causing harmful light leakage.
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 enhances light-exit brightness and uniformity, improving fingerprint recognition accuracy by maintaining a reduced module thickness and minimizing light leakage, thus achieving better recognition effects.
Implementation Method 1
The reverse prism sheet includes a first prism. A surface of the first prism proximate to the light guide plate includes a plurality of prism structures
Implementation Method 2
mainly uses principles of refraction and reflection of light to achieve fingerprint recognition
Implementation Method 3
a side-type backlight module, comprising a light guide plate, a reverse prism sheet, and a reflective sheet
Data Source
AI summary
A side-type backlight module includes a light guide plate and a reverse prism sheet that are stacked. The reverse prism sheet includes a first prism. A surface of the first prism proximate to the light guide plate includes a plurality of prism structures substantially parallel to each other. Each prism structure protrudes toward a direction approaching the light guide plate. A surface of the light guide plate proximate to the reverse prism sheet includes a plurality of strip-shaped microstructures substantially parallel to each other. Each strip-shaped microstructure protrudes toward a direction approaching the reverse prism sheet. An extending direction of the prism structure crosses an extending direction of the strip-shaped microstructure.