Optical Fingerprint Sensor Package With Integrated LED Reflection
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Solution Overview
Problem
Optical fingerprint sensors often require additional auxiliary light sources for active illumination, increasing the cost and complexity of device design and assembly.
Innovation Solution
The optical fingerprint sensor package incorporates a light-emitting diode (LED) light source with an optically clear molding compound that includes a surface to reflect and direct light into a light guide, eliminating the need for auxiliary light sources by using the LED light to illuminate the sensing area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If additional auxiliary light sources are used for active illumination, then the illumination capability is improved, but the device complexity and cost increase
Solution Approach 1:
The patent combines the illumination function and sensing function into a single integrated optical sensor package. The LED light source is positioned to illuminate the sensing area while the image sensor detects reflected light, eliminating the need for separate auxiliary light sources. The molding compound integrates multiple functions including structural support, optical guidance, and reflective surfaces, reducing overall device complexity.
Solution Approach 2:
The molding compound serves multiple functions simultaneously: it provides structural encapsulation for the LED and image sensor, acts as a light guide to direct illumination, creates reflective surfaces to enhance light direction, and protects the internal components. This multi-functionality eliminates the need for separate auxiliary illumination components.
2Illumination intensity
If additional auxiliary light sources are used for active illumination, then the illumination capability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent merges the illumination source and sensing elements into a single integrated package, reducing the total component count and assembly steps. The molding compound is formed in a single manufacturing process that simultaneously creates structural and optical functions, eliminating the need for separate auxiliary light source assemblies and reducing manufacturing cost.
Solution Approach 2:
The molding compound performs multiple functions including structural support, light guidance, and reflection, replacing what would traditionally require multiple separate components. This integration simplifies the manufacturing process and reduces the bill of materials cost while maintaining effective illumination capability.
3Volume of moving object
If the device size is reduced to maintain compact form factor, then the portability is improved, but the optical path length and light guidance become more difficult
Solution Approach 1:
The patent integrates the light guide function directly into the molding compound that encapsulates the LED and image sensor. This eliminates the need for separate light guide components and reduces the overall device volume while maintaining effective light guidance. The optical paths are optimized within the compact integrated structure.
Solution Approach 2:
The molding compound simultaneously provides structural encapsulation and optical guidance functions in a single component. By integrating these functions, the patent achieves compact form factor without requiring additional optical elements that would increase device volume or complexity.
4Illumination intensity
If more components are added for active illumination, then the assembly process becomes more complex, but the illumination performance is improved
Solution Approach 1:
The patent combines the illumination source (LED), the light guidance structure, and the sensing element (image sensor) into a single integrated package. The molding compound is formed in one manufacturing step that encapsulates the LED and creates the light guide and reflective surfaces, eliminating multiple separate assembly operations for auxiliary light sources.
Solution Approach 2:
The molding compound serves as both the structural housing and the optical guidance system, replacing what would traditionally require separate light guides, reflectors, and housing components. This integration dramatically simplifies the assembly process while maintaining effective illumination performance.
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
This solution reduces the complexity and cost of the device by integrating the light source and light guide within the sensor package, providing effective illumination for fingerprint imaging without additional light sources.
Implementation Method 1
the optically clear molding compound is coupled to the light guide and comprises a surface positioned to reflect light emitted from the light source and direct the reflected light into the light guide
Implementation Method 2
a light guide disposed over the light filter
Implementation Method 3
the image sensor die comprises a photodetector array
Data Source
AI summary
Disclosed are optical sensors, optical fingerprint sensor packages, and methods for forming same. An optical sensor comprises: a substrate; an image sensor disposed over the substrate; a light source disposed over the substrate; a light guide disposed over the image sensor; and, an encapsulant disposed over the light source, wherein the encapsulant is coupled to the light guide and comprises a surface positioned to reflect light emitted from the light source and direct the reflected light into the light guide.