Backlight Module Segmentation for Fingerprint Imaging
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Solution Overview
Problem
Current display devices with integrated fingerprint identification suffer from poor fingerprint imaging and identification due to excessive stray light generated by the backlight module.
Innovation Solution
A backlight module comprising a first light emitting unit, a second light emitting unit, a first optical layer, and a second optical layer, where the first optical layer collimates light and the second optical layer scatters the first light but not the second light, improving light intensity distribution and reducing stray light for enhanced fingerprint identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight module emits strong light for display, then the display brightness is improved, but the stray light increases causing poor fingerprint imaging
Solution Approach 1:
The light emitting unit is divided into two independent parts: a first light emitting unit for display illumination and a second light emitting unit for fingerprint sensing. This segmentation allows each unit to be optimized for its specific function, with the second unit emitting light only when fingerprint sensing is needed, thereby reducing stray light during display operation.
Solution Approach 2:
The second light emitting unit operates periodically or selectively only when fingerprint sensing is required, rather than continuously. This periodic activation reduces the overall stray light in the system while maintaining display brightness when needed.
2Device complexity
If the backlight module uses a single light emitting unit, then the device structure is simple, but the fingerprint identification effect is poor due to stray light
Solution Approach 1:
The backlight module is segmented into two functional units: a first light emitting unit for general display illumination and a second light emitting unit specifically for fingerprint sensing. This segmentation enables the second unit to provide targeted illumination for fingerprint imaging without the stray light interference that occurs with a single unified light source.
Solution Approach 2:
A second optical layer acts as an intermediary component that selectively scatters light from the first light emitting unit while allowing light from the second light emitting unit to pass through. This intermediary structure enables the two light sources to coexist without mutual interference, improving fingerprint imaging quality.
3Stability of the object's composition
If the optical layer scatters all light uniformly, then the light distribution is homogeneous, but the fingerprint imaging clarity deteriorates
Solution Approach 1:
The second optical layer is designed with local quality differentiation: it has regions that scatter light from the first light emitting unit to achieve uniform display illumination, while simultaneously having regions that allow light from the second light emitting unit to pass through with minimal scattering to maintain fingerprint imaging clarity.
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 provides improved fingerprint identification and display quality by controlling light intensity and direction, reducing stray light and enhancing imaging clarity during fingerprint sensing.
Implementation Method 1
the first optical layer collimates light
Implementation Method 2
the second optical layer is configured to scatter the first light emitted from the first light emitting unit
Data Source
AI summary
An electronic device including a first light emitting unit, a second light emitting unit, a first optical layer and a second optical layer is disclosed. The first light emitting unit emits a first light. The second light emitting unit emits a second light. At least one of the first light and the second light passes through the first optical layer. The second optical layer is overlapped with the first optical layer. The second optical layer is configured to scatter the first light emitted from the first light emitting unit. When the first light emitting unit emits the first light, the second light emitting unit selectively emits the second light.