Optical Sensing Device Fabrication Using OLED Shading Electrode
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Solution Overview
Problem
The manufacturing process of fingerprint recognition modules is complex and recognition accuracy is a challenge, particularly in integrating fingerprint recognition into display panels for electronic devices, where space is limited and user privacy is a concern.
Innovation Solution
A method for fabricating an optical sensing device using a thin film transistor, an organic light emitting diode as a light source, and an optical sensor, where the second metal electrode provides shading to the channel layer, eliminating the need for a shading component and increasing the photosensitive area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate shading component is added to block light from reaching the channel layer, then the light detection accuracy is improved, but the device complexity and manufacturing process become more complex
Solution Approach 1:
The patent combines the shading function with the existing second metal electrode of the OLED structure. Instead of adding a separate shading component, the second metal electrode is extended or designed to overlap with the channel layer, providing both electrical functionality for the OLED and optical shading to prevent light from reaching the TFT channel layer. This merging eliminates additional components while maintaining both functionalities.
Solution Approach 2:
The second metal electrode of the OLED is given dual functionality: it serves as an electrical electrode for the organic light emitting diode operation and simultaneously acts as a shading component to block light from reaching the channel layer. This multi-functionality reduces the overall device complexity by eliminating the need for dedicated shading structures.
2Measurement precision
If the photosensitive area is increased to improve recognition accuracy, then the fingerprint detection capability is enhanced, but the device area occupied increases
Solution Approach 1:
The patent utilizes vertical layering and spatial overlap in the third dimension to resolve the area conflict. The OLED is positioned above the TFT, and the second metal electrode extends vertically and horizontally to provide shading over the channel layer. This three-dimensional arrangement allows the photosensitive area to be maximized without proportionally increasing the planar device footprint, as components are stacked rather than purely lateral.
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 simplifies the manufacturing process, enhances recognition accuracy by increasing the detecting area, and improves security through precise fingerprint detection, while saving costs by omitting the shading component fabrication.
Implementation Method 1
an organic light emitting diode as a light source
Implementation Method 2
the light reflected by the finger and received by the optical sensor is transformed into a light current
Data Source
AI summary
An optical sensing device includes a thin film transistor disposed on a substrate, an optical sensor, a planar layer, and an organic light emitting diode. The optical sensor includes a metal electrode disposed on a gate dielectric layer of the thin film transistor and connecting to a drain electrode of the thin film transistor, an optical sensing layer disposed on the metal electrode, and a first transparent electrode disposed on the optical sensing layer. The planar layer covers at least a part of the thin film transistor and the optical sensor. The organic light emitting diode is disposed on the planar layer. The anode electrode and the cathode electrode of the organic light emitting diode are electrically coupled to a gate line and a data line respectively.