Dual Light-Shielding Layer Pin-Hole Fingerprint Sensor
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Solution Overview
Problem
In OLED display devices, the accuracy of fingerprint recognition is compromised due to air gaps between the fingerprint valleys and the contact surface, causing beams with angles greater than the critical angle of total reflection to be directly reflected and interfere with the fingerprint recognition element, leading to reduced accuracy.
Innovation Solution
A display panel design that includes a first light-shielding layer with imaging pin-holes and a second light-shielding layer with corresponding pin-holes, where the second layer shields beams that are totally reflected without fingerprint information, preventing them from reaching the light-sensing sensor and improving recognition accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light-shielding layer with imaging pin-holes is used, then the device structure is simple, but beams with angles greater than the critical angle are directly reflected and cause strong interference, reducing fingerprint recognition accuracy
Solution Approach 1:
The single light-shielding layer is divided into two separate layers: a first light-shielding layer with imaging pin-holes and a second light-shielding layer with shielding portions. This segmentation allows each layer to perform a specific function - the first layer enables pin-hole imaging while the second layer blocks interfering reflected beams, thereby resolving the contradiction between maintaining simple structure and improving recognition accuracy.
Solution Approach 2:
The second light-shielding layer acts as an intermediary between the imaging pin-holes and the light-sensing sensor layer. It selectively blocks beams that are totally reflected at the protective layer interface (which would otherwise reach the sensor and cause interference) while allowing the imaging function to proceed through the first light-shielding layer's pin-holes.
2Measurement precision
If the light-sensing sensor layer is fully attached onto the back side using optical adhesive, then the device structure is simplified, but air gaps between fingerprint valleys and contact surface cause total reflection of beams, leading to strong interference and reduced recognition accuracy
Solution Approach 1:
The harmful totally reflected beams are extracted and blocked by the second light-shielding layer with shielding portions. This layer specifically targets and removes the interfering beams that result from total reflection at the protective layer interface, preventing them from reaching the light-sensing sensor layer and thus improving recognition accuracy.
Solution Approach 2:
The second light-shielding layer converts the harmful effect of total reflection into a beneficial filtering mechanism. By strategically placing shielding portions, the system uses the naturally occurring total reflection phenomenon to define which beams should be blocked, turning a source of interference into a means of selective beam control that enhances fingerprint recognition.
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
The solution effectively enhances fingerprint recognition accuracy by blocking interfering beams, thereby improving the overall performance of the pin-hole imaging principle in OLED display devices.
Implementation Method 1
beams emitted from pin-hole imaging light sources pass through the first imaging pin-holes of the first light-shielding layer and strike onto the light-sensing sensor layer, so that fingerprint images are generated on the light-sensing sensor layer according to a pin-hole imaging principle
Implementation Method 2
beams incident on the contact surface of the display device with an angle greater than the critical angle of total reflection will be directly reflected
Implementation Method 3
the second light-shielding layer is used for shielding beams emitted from pin-hole imaging light sources and totally reflected through a touch surface of the protective layer
Data Source
AI summary
A display panel includes a base substrate, an array layer located at one side of the base substrate, a display layer located at one side of the array layer away from the base substrate, a protective layer located at one side of the display layer away from the array layer, first and second light-shielding layers and a light-sensing sensor layer. The display layer includes multiple light-emitting elements. The first light-shielding layer includes multiple first imaging pin-holes. The second light-shielding layer includes multiple second imaging pin-holes corresponding to the first imaging pin-holes. The light-sensing sensor layer is located at one side of the display layer away from the protective layer, for detecting images generated via the first imaging pin-holes. The second light-shielding layer shields beams emitted from pin-hole imaging light sources and totally reflected through a touch surface of the protective layer.