Transparent TFT Fingerprint Area for Under-Display Optical Sensing
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Solution Overview
Problem
The existing OLED display screens have low light transmittance due to metal electrodes, which affects the accuracy of fingerprint recognition by optical fingerprint modules, leading to poor user experience.
Innovation Solution
Incorporating an array of transparent thin film transistors and a transparent medium in the fingerprint recognition area of the display screen, allowing lights to pass through and increasing light transmittance for improved fingerprint recognition accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal electrodes are used in the display screen, then electrical conductivity is improved, but light transmittance deteriorates
Solution Approach 1:
The patent changes the material parameter of the electrodes from metal to transparent conducting oxide (TCO) materials such as ITO, IZO, or AZO. This parameter change maintains electrical conductivity while fundamentally improving light transmittance, allowing the electrodes to be optically transparent and enabling the optical fingerprint module to function properly through the display screen.
Solution Approach 2:
The patent employs composite material structures including transparent conducting oxide layers combined with organic transparent hole injection layers (such as TAPC, TCTA, or TTDATA). This composite approach ensures both electrical conductivity and optical transparency are achieved simultaneously, resolving the contradiction between these two properties.
2Area of stationary object
If the optical fingerprint module is placed under the display screen, then screen-to-body ratio is improved, but fingerprint recognition accuracy deteriorates
Solution Approach 1:
The patent changes the optical parameters of the display screen by using transparent electrodes and optimizing layer structures to maximize light transmittance. This allows sufficient light to reach the fingerprint sensor underneath, improving recognition accuracy while maintaining the space-saving under-screen configuration.
Solution Approach 2:
The patent introduces transparent organic hole injection layers as intermediary layers between the transparent electrodes and the fingerprint sensor. These layers enhance light transmission and provide optimal optical coupling, acting as a mediator that improves the fingerprint recognition accuracy without compromising the under-screen layout.
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
Enhances the intensity of light emitted and reflected by the fingerprint patterns, thereby improving the accuracy of fingerprint recognition and user experience by increasing light transmittance through the display screen.
Implementation Method 1
The transparent thin film transistors and the transparent medium are configured to allow lights transmitted or received by an optical fingerprint module to pass through
Implementation Method 2
The optical fingerprint module is configured to recognize fingerprint signals by emitting lights to patterns of a finger and collecting lights reflected by the patterns
Data Source
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AI summary
Provided are a display screen (100), a display device (200), and a mobile terminal (300). The display screen (100) includes a display layer (110). The display layer (110) has a fingerprint recognition area (111). The fingerprint recognition area (111) is provided with an array of transparent thin film transistors (112) and a transparent medium (113) among the transparent thin film transistors (112). The display device (200) includes the display screen (100) described above, and further includes an optical fingerprint module (202) and a frame (201). The display screen (100) and the optical fingerprint module (202) are fixed on the frame (201). The optical fingerprint module (202) is on one side of the display screen (100) intended to away from a user and located in a position corresponding to the fingerprint recognition area (111), so as to allow lights transmitted and received to pass through the fingerprint recognition area (111). By fingerprint recognition area (111), which is provided with the transparent thin film transistors (112), in the display screen (100), and by disposing the optical fingerprint module (202) below the fingerprint recognition area (111), light transmittance of the display screen (100), and accuracy of fingerprint recognition of the optical fingerprint module (202) can be improved.