Prism-Based Optical Unit for Fingerprint Sensor Light Filtering
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Solution Overview
Problem
Conventional fingerprint sensors in electronic devices face challenges in accurately identifying fingerprints due to the need for precise extraction of light rays incident at specific angles from ridges, while existing optical units fail to effectively filter out light rays from valleys and angles outside the detection target range.
Innovation Solution
The optical unit incorporates multiple layers of prisms with inclined surfaces of different angles to block light rays outside the detection target incident angle range, using light-absorbing layers and a specific arrangement of prisms to transmit only light rays within the 43-47 degree range, ensuring accurate fingerprint recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical units are used to filter light rays, then light rays from valleys can be blocked, but light rays at non-target angles cannot be effectively filtered
Solution Approach 1:
The optical unit is divided into multiple prisms (first prism, second prism, third prism) with different inclination angles. Each prism segment handles a specific angle range: the first prism blocks light at angles greater than the detection target angle, the second prism blocks light at angles less than the detection target angle, and the third prism supports the structure. This segmentation allows precise filtering of light rays at different angles to improve both measurement precision and reliability.
2Measurement precision
If multiple layers of prisms with different inclination angles are used, then light rays at non-target angles are blocked, but device complexity increases
Solution Approach 1:
Each prism in the optical unit is designed with specific local qualities - different inclination angles tailored to their functional requirements. The first prism has inclination angles suited for blocking high-angle light, the second prism has angles for blocking low-angle light, and the third prism provides structural support. This local quality approach achieves high angle selectivity while managing complexity through functional specialization.
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 enables the accurate extraction of light rays from fingerprint ridges, improving fingerprint identification accuracy by filtering out light rays from valleys and angles outside the detection target range, enhancing the overall fingerprint recognition process in electronic devices.
Implementation Method 1
an optical unit for a fingerprint sensor disposed under the display panel to transmit only light rays incident at a detection target incident angle, wherein the optical unit comprises at least one prism having multiple inclined surfaces, which are alternately disposed and have different inclination angles
Implementation Method 2
at least one first inclined surface and at least one second inclined surface, the at least one first inclined surface and the at least one second inclined surface are alternately disposed and have different inclination angles
Implementation Method 3
the optical unit may further include a light-absorbing layer provided on the at least one first inclined surface to absorb light rays incident thereon
Data Source
AI summary
An optical unit and a display device including same. The optical unit is for a fingerprint sensor of the display device, and the optical unit includes a first prism to block light rays incident at an angle greater than a detection target incident angle; and a second prism disposed under the first prism to block light rays incident at an angle less than the detection target incident angle.