Fingerprint Sensor Light Guide Structures for Image Quality
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Solution Overview
Problem
The quality of fingerprint images obtained in electronic devices with image sensors for fingerprint recognition can be varied or lowered due to changes in the field of view (FOV) and distance from the fingerprint recognition target, affecting the accuracy of fingerprint recognition.
Innovation Solution
An electronic device with a display panel, an image sensor, a first guide structure, and a second guide structure that change the direction of incident light, allowing the image sensor to obtain image information and biometric data from a fingerprint recognition region, which includes multiple sub-fingerprint recognition regions, while the image sensor size is smaller than or equal to the fingerprint recognition region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the image sensor size is increased to cover the entire fingerprint recognition region, then the field of view coverage is improved, but the device size and complexity increase
Solution Approach 1:
The fingerprint recognition region is divided into multiple sub-regions, each equipped with its own light source and guide structure. This segmentation allows the image sensor to capture multiple fingerprint regions simultaneously without requiring a single large sensor, thus reducing device complexity while maintaining comprehensive coverage.
Solution Approach 2:
The patent introduces a vertical stacking arrangement where multiple sub-fingerprint recognition regions are positioned at different locations on the display panel, and light is guided through the display panel thickness to reach the image sensor. This dimensional approach allows multiple regions to be captured using a single smaller image sensor rather than requiring a larger sensor to cover the entire area.
2Area of moving object
If the field of view is increased to cover more fingerprint regions, then the coverage area is improved, but the depth of field becomes shallower causing quality degradation
Solution Approach 1:
By segmenting the fingerprint recognition into multiple sub-regions with dedicated light sources, each sub-region can be optimized for its specific depth range. This allows the system to maintain shallow depth of field characteristics for high-quality imaging within each sub-region while collectively covering a larger overall area.
Solution Approach 2:
Each sub-fingerprint recognition region has its own light source and guide structure optimized for that specific location, allowing each region to achieve optimal imaging quality for its local depth range. This local optimization ensures high fingerprint image quality across different positions without compromising the overall coverage area.
3Adaptability or versatility
If multiple light sources are added to cover sub-fingerprint recognition regions, then the imaging coverage is improved, but the device complexity and light path management become more difficult
Solution Approach 1:
The guide structures are designed to serve multiple functions: they guide light from each light source through the display panel to the image sensor, and they can be configured to work with different light source positions and orientations. This multi-functionality simplifies the overall system by using a single guide structure design for multiple sub-regions.
Solution Approach 2:
The guide structures are positioned within the display panel layers, utilizing the existing display panel structure as a container for the optical path. This nested arrangement allows multiple light sources and guide structures to be integrated within the display panel thickness without adding external complexity, effectively hiding the light path management within the display panel itself.
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 configuration improves the accuracy of fingerprint recognition and allows for a wider range of imaging using a smaller image sensor, reducing misrecognition due to changes in depth of field and maintaining image quality across different positions and distances.
Implementation Method 1
a first guide structure that is disposed between the display panel and the image sensor and that changes a direction of the incident light incident through a fingerprint recognition region of the display panel
Implementation Method 2
a second guide structure that is disposed between the first guide structure and the image sensor and that changes the direction of the incident light incident through the first guide structure
Implementation Method 3
an image sensor disposed to receive incident light incident thereon by reflection of light emitted through the at least one light source by an object external to the electronic device
Data Source
AI summary
An electronic device is provided. The electronic device includes a display panel including an image sensor arranged to receive incident light reflected by an external object, a first guide structure arranged between the display panel and the image sensor and configured to change the direction of the incident light which is introduced through a fingerprint recognition area of the display panel, a second guide structure arranged between the first guide structure and the image sensor and configured to change the direction of the incident light which is introduced therein after passing through the first guide structure, and a processor operatively connected to the display panel and the image sensor. According to an embodiment, the electronic device performs fingerprint recognition by acquiring image information through the image sensor on the basis of at least a part of the incident light introduced through the first guide structure and the second guide structure.