Optical Fingerprint Sensor Substrate Integrating Light Guide
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Solution Overview
Problem
Existing optical fingerprint imaging systems have a bulky structure due to the presence of a light guide plate, which occupies a significant portion of the system's thickness and complexity, necessitating a thinner and more simplified design.
Innovation Solution
The optical fingerprint imaging system integrates a substrate with a photosensitive layer as both a light guide and sensor surface, eliminating the need for an additional light guide plate, and incorporates a reflecting element, such as dots or a film, to enhance light utilization without increasing thickness or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a light guide plate is used to guide light from the light source to the sensor surface, then light guidance function is achieved, but the system thickness increases significantly
Solution Approach 1:
The patent merges the light guide function with the sensor substrate by integrating light guide structures directly into the substrate. The substrate serves dual purposes: as the sensor base and as the light guide medium, eliminating the need for a separate light guide plate and thereby reducing overall system thickness while maintaining light guidance efficiency
Solution Approach 2:
The substrate is designed to perform multiple functions simultaneously: it acts as both the sensor substrate and the light guide plate. By making the substrate multi-functional, the patent eliminates the need for additional components, reducing system thickness without compromising the light guidance function
2Device complexity
If a separate light guide plate is used, then light guidance is achieved, but the device structure becomes more complex
Solution Approach 1:
The patent combines the light guide function with the sensor substrate into a single integrated structure. The substrate incorporates light guide structures directly, merging two previously separate components (substrate and light guide plate) into one, thereby simplifying the overall device structure while maintaining effective light guidance
Solution Approach 2:
The substrate is designed to serve multiple functions: as the sensor substrate and as the light guide medium. This multi-functionality reduces the number of components needed, simplifying the device structure without sacrificing the light guidance function
3Area of stationary object
If the light source is placed on the lateral side of the light guide plate, then light entry is achieved, but the system requires more space
Solution Approach 1:
The patent transitions from a lateral placement configuration to a vertical stacking configuration. The light source is positioned below the substrate and emits light upward through the integrated light guide structures in the substrate, changing the spatial arrangement from lateral to vertical dimension, thereby reducing space occupation while maintaining light emission efficiency
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 reduces the system's thickness, simplifies the structure, and improves light use efficiency, enabling effective fingerprint imaging without the need for additional components, thus enhancing performance.
Implementation Method 1
light emitted from the light source is guided by the substrate to the first surface of the substrate
Implementation Method 2
a reflecting element for reflecting light reaching the second surface of the substrate to the first surface of the substrate
Implementation Method 3
the reflected light may be received by a sensor where the intensity information thereof is converted into electrical signals
Data Source
AI summary
An optical fingerprint imaging system (200) and an optical assembly (300, 400, 500, 600, 700) are provided. The optical fingerprint imaging system (200) includes: a sensor (203, 302, 402, 502, 602, 702) and a light source (202, 301, 401, 501, 601, 701); wherein the sensor (203, 302, 402, 502, 602, 702) comprises a substrate (2031, 3021, 4021, 5021, 6021, 7021) and a photosensitive layer (2032, 3022, 4022, 5022, 6022, 7022), the substrate (2031, 3021, 4021, 5021, 6021, 7021) has a first surface and a second surface which is opposite to and lower than the first surface, and the photosensitive layer (2032, 3022, 4022, 5022, 6022, 7022) is in contact with the first surface of the substrate (2031, 3021, 4021, 5021, 6021, 7021); and wherein the light source (202, 301, 401, 501, 601, 701) is disposed at a position lower than the first surface and higher than the second surface, and light emitted from the light source (202, 301, 401, 501, 601, 701) is adapted to be guided by the substrate (2031, 3021, 4021, 5021, 6021, 7021) to the first surface of the substrate (2031, 3021, 4021, 5021, 6021, 7021). Accordingly, an optical fingerprint imaging system (200) with a reduced thickness, and a simplified structure is provided.