Under-Display Fingerprint Module Light Shielding
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Solution Overview
Problem
Optical under-display fingerprint recognition technologies face interference from stray light, which degrades the definition of fingerprint images due to additional light sources used for recognition, causing reflections that do not carry fingerprint information and affect the accuracy of the recognition process.
Innovation Solution
A fingerprint recognition module is introduced, featuring a light emitting diode (LED), an image sensor, and a light shielding member positioned between them to block stray light, ensuring that only fingerprint-related optical signals are received, thereby reducing interference and improving image definition. The light shielding member is strategically placed to control the emergent angle of optical signals, balancing energy reception at the sensor and the finger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional light source with strong penetration force is provided below the screen to enable optical under-display fingerprint recognition, then fingerprint recognition capability is achieved, but reflected light interference is generated which degrades fingerprint image definition
Solution Approach 1:
A light shielding member is introduced as an intermediary component between the light source and the sensor. This member selectively blocks harmful reflected light while allowing useful transmitted light to pass through, thereby resolving the interference problem without compromising the fingerprint recognition capability
Solution Approach 2:
The harmful reflected light is extracted and removed from the optical path by the light shielding member, which is positioned to intercept and block these interfering rays before they reach the sensor, thereby improving image definition while maintaining recognition functionality
2Measurement precision
If a light shielding member is added to block reflected light and improve fingerprint image definition, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The light shielding member is designed as a thin film or shell structure that can be easily integrated into the existing module without adding significant bulk or complexity. This thin-film approach provides effective light blocking while minimizing the increase in device complexity
Solution Approach 2:
The light shielding function is merged with the existing module structure, where the light shielding member is integrated into the housing or assembly framework. This combining approach allows the shielding function to be achieved without adding separate, independent components, thereby limiting the increase in device complexity
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 significantly enhances the definition of fingerprint images by minimizing interference from stray light, leading to improved recognition accuracy and efficiency.
Implementation Method 1
A light emitting surface of the LED is opposite to a lower surface of the screen assembly and is used to emit an optical signal
Implementation Method 2
a photosensitive surface of the image sensor is opposite to the lower surface of the screen assembly and is used to receive an optical signal
Implementation Method 3
The light shielding member is partially or entirely located between the LED and the image sensor, to block a part of optical signals emitted by the LED
Data Source
AI summary
A fingerprint recognition system is disposed below a screen assembly of an electronic device and includes a light-emitting diode (LED), an image sensor, and a light shielding member. A light emitting surface of the LED faces the screen assembly and is configured to emit an optical signal. A photosensitive surface of the image sensor faces the screen assembly, where the optical signal received by the image sensor includes a fingerprint optical signal returned after being emitted by the LED to a finger, to generate a fingerprint image. The light shielding member is located between the LED and the image sensor, to block a part of signal light emitted by the LED.