Display-Surface Fingerprint Recognition With Organic Phototransistors
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Solution Overview
Problem
Conventional in-screen optical fingerprint recognition technologies suffer from low accuracy due to significant light loss as light penetrates through the display panel, affecting the amount received by the photosensitive element.
Innovation Solution
Integrate a fingerprint recognition module on the display panel's light-emitting surface, comprising phototransistors and switch transistors with shared manufacturing processes, to receive reflected light without penetrating through structural film layers, reducing light loss and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light penetrates through the display panel to reach the photosensitive element, then fingerprint recognition can be implemented, but light loss increases significantly
Solution Approach 1:
The patent inverts the conventional arrangement by placing the fingerprint recognition module on the light-emitting surface rather than behind the display panel. This allows reflected light from the finger to be detected directly without penetrating through the display panel structure, thereby eliminating light loss through multiple film layers while maintaining recognition functionality
2Measurement precision
If the fingerprint recognition module is placed on the light-emitting surface, then light transmission distance is shortened and accuracy improves, but structure complexity increases
Solution Approach 1:
The patent merges the phototransistor and switch transistor into an integrated fingerprint recognition unit that shares common electrode structures and manufacturing processes with the display panel. This integration approach reduces overall structural complexity despite placing the module on the light-emitting surface, as the transistors utilize the same film layers and fabrication steps already present in the display device
3Reliability
If phototransistor and switch transistor are manufactured separately, then device performance can be optimized, but manufacturing process complexity increases
Solution Approach 1:
The patent designs the phototransistor and switch transistor to share common manufacturing processes, including the same active layer formation, gate electrode structures, and contact layer fabrication. This universal manufacturing approach allows both transistor types to be produced simultaneously using identical process steps, reducing manufacturing complexity while maintaining the distinct functional characteristics of each transistor type through different structural configurations
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 approach enhances fingerprint recognition accuracy by shortening the transmission distance of reflected light, simplifies the structure and process complexity, and reduces the overall thickness of the display assembly.
Implementation Method 1
the phototransistor converts an optical signal into an electrical signal
Data Source
AI summary
The present disclosure relates to display assemblies, display apparatuses, and fingerprint recognition methods. One example display assembly includes a display panel and a fingerprint recognition module located on a light-emitting surface of the display panel. The fingerprint recognition module includes multiple fingerprint recognition units. Each fingerprint recognition unit includes at least one phototransistor and one switch transistor. The phototransistor includes a first active layer, a first gate, a first source, and a first drain. A material for making the first active layer includes an organic semiconductor material. The first drain and the first gate partially overlap to form a first capacitor. The switch transistor includes a second active layer, a second gate, a second source, and a second drain. The fingerprint recognition module includes a first metal layer. The first source, the first drain, the second source, and the second drain are all located at the first metal layer.