In-Display Fingerprint Module Multi-Layer Light Guide Film Crosstalk Reduction
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Solution Overview
Problem
Existing display apparatuses for in-screen fingerprint recognition suffer from issues such as large-angle crosstalk, film diagonal/moire patterns, and poor reliability due to the limitations of single-layer collimating films and lens alignment, which degrade fingerprint image quality under outdoor lighting conditions and reduce user experience.
Innovation Solution
A fingerprint recognition module with a multi-layer light guide film and microlens structure, where light shielding layers with light transmitting holes are stacked and aligned to form a collimating hole structure, integrated with a bias metal and noise reduction metal layers, and microlenses to enhance collimation and reduce crosstalk, while integrating the light guide film and microlens directly onto the photosensitive device layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer collimating film is used, then the structure is simple, but large-angle crosstalk occurs and fingerprint image quality degrades
Solution Approach 1:
The single-layer collimating film is divided into multiple light shielding layers with light transmitting holes, where each layer contributes to collimation at different stages. This segmentation reduces large-angle crosstalk while maintaining manageable structural complexity through modular design
Solution Approach 2:
Multiple light shielding layers are stacked and integrated with microlens arrays in a nested configuration, with each layer containing light transmitting holes that align with corresponding microlenses. This nested structure enhances collimation effectiveness without proportionally increasing overall device complexity
2Measurement precision
If lens alignment is improved, then fingerprint recognition accuracy increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The light guide film and microlens are merged into an integrated structure where the microlens is directly formed on or combined with the light guide film layer. This merging ensures precise alignment between light transmitting holes and microlenses while reducing the number of separate components and simplifying manufacturing processes
Solution Approach 2:
The light guide film serves multiple functions: it guides light from the display, provides structural support for microlens integration, and maintains precise alignment through its multi-layer design with corresponding hole patterns. This multi-functionality reduces the need for separate alignment mechanisms
3Reliability
If multi-layer light shielding layers are added, then crosstalk is reduced, but manufacturing complexity increases
Solution Approach 1:
The light shielding layers are pre-patterned with light transmitting holes in specific arrangements that correspond to microlens positions before final assembly. This preliminary structuring ensures proper alignment and crosstalk reduction while simplifying the final manufacturing process through pre-prepared components
Solution Approach 2:
The diameters of light transmitting holes are varied across different layers to optimize collimation performance at each stage. By carefully controlling hole diameter parameters in each layer, the patent achieves effective crosstalk reduction while maintaining manufacturability through standard fabrication techniques
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 effectively reduces crosstalk and improves fingerprint recognition accuracy by ensuring precise alignment and reliability, allowing for accurate fingerprint detection even under varying lighting conditions, and reduces the overall thickness of the recognition module.
Implementation Method 1
a microlens layer located on one side of the light guide film layer facing away from the photosensitive device layer, where the microlens layer comprises a plurality of microlenses
Implementation Method 2
enhance collimation and reduce crosstalk
Implementation Method 3
a light guide film layer including at least two light shielding layers arranged in a stacked manner, where each of the light shielding layers is provided with light transmitting holes
Implementation Method 4
the light is reflected by the valley and the ridge of the finger and then is incident on a photosensitive device of the display product. Due to a difference in intensity of light reflected from the positions of the valley and the ridge, the photosensitive device generates different electrical signals
Data Source
AI summary
The disclosure provides a fingerprint recognition module and a display apparatus, including: a base substrate; a photosensitive device layer above the base substrate and including a plurality of photosensitive devices; a bias metal layer and a noise reduction metal layer sequentially on the side of the photosensitive device layer distant from the base substrate; a light guide film layer including at least two light shielding layers arranged in a stacked manner, and a microlens layer on the side of the light guiding film layer facing away from the photosensitive device layer and including a plurality of microlenses. Each of the light shielding layers is provided with light transmitting holes arranged in an array, the light transmitting holes in all the light shielding layers are provided in a one-to-one correspondence manner. An orthogonal projection of the microlens covers the orthogonal projections of the light transmitting holes on the base substrate.