OLED Display Fingerprint Block TFT Reduction
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Solution Overview
Problem
OLED display devices with fingerprint on display (FOD) technology face low transmittance and accuracy issues due to the need for light to pass through multiple film layers for fingerprint recognition, resulting in reduced brightness and recognition accuracy.
Innovation Solution
The OLED display device incorporates a fingerprint recognition module under the display panel with a reduced number of thin film transistors (TFTs) in the fingerprint recognition block, minimizing the number of films in the stack and enhancing transmittance and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light passes through multiple film layers in the display area for fingerprint recognition, then the fingerprint recognition function is achieved, but the transmittance is very low and recognition accuracy is reduced
Solution Approach 1:
The patent divides the display area into two distinct regions: a first display area with a first number of TFTs and a second display area with a second number of TFTs, where the second number is less than the first. This segmentation allows the fingerprint recognition block to have fewer film layers, thereby improving light transmittance and recognition accuracy while maintaining the fingerprint recognition function.
Solution Approach 2:
The patent applies different structural configurations to different regions of the display. The fingerprint recognition block uses a reduced number of TFTs and corresponding film layers compared to the normal display area. This local quality adjustment optimizes the specific region for light transmission and fingerprint recognition while preserving the functionality of the overall display.
2Illumination intensity
If the number of TFTs is reduced in the fingerprint recognition block, then the number of films in the stack is reduced and transmittance is improved, but the display functionality may be affected
Solution Approach 1:
The patent segments the display into a first display area with complete TFT structures for normal display functionality and a second display area with reduced TFT structures for fingerprint recognition. This segmentation ensures that the reduced film stack in the fingerprint area does not compromise the overall display functionality, as the first display area maintains full display capabilities.
Solution Approach 2:
The patent makes the display device multi-functional by integrating both normal display functionality and fingerprint recognition within the same display area. The first display area handles display tasks while the second display area handles fingerprint recognition, allowing the device to perform multiple functions without compromising either capability.
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 improves the transmittance and accuracy of fingerprint recognition by reducing the number of films in the stack, allowing higher light transmission and better fingerprint image capture.
Implementation Method 1
The semiconductor and organic light emitting materials are driven by an electric field to emit light through injection and recombination of carriers. In greater detail, the OLED display device usually uses an ITO pixel electrode and a metal electrode as the anode and the cathode of the device, respectively. When being driven by a certain voltage, electrons and holes are respectively injected from the cathode and the anode to the electron transport layer and the hole transport layer. The electrons and holes migrate to the light emitting layer respectively through the electron transport layer and the hole transport layer, and meet in the light emitting layer to form excitons and excite the light emitting molecules. The latter emit visible light through radiation relaxation.
Implementation Method 2
The fingerprint recognition sensor captures light to form photogenerated carriers and form the fingerprint image.
Data Source
AI summary
The present disclosure proposes an OLED display device with FOD that includes an OLED display panel and a fingerprint recognition module disposed under the OLED display panel. Sub-pixels arranged in an array on a substrate are located in an effective display area of the substrate. A fingerprint recognition block is disposed in the effective display area. The fingerprint recognition module is disposed corresponding to the fingerprint recognition block. A number of TFTs in each of the sub-pixels located in the fingerprint recognition block is less than a number of TFTs in each of the sub-pixels outside the fingerprint recognition block. Through decreasing the number of the TFTs in each of the sub-pixels in the fingerprint recognition block, the number of films in the stack of the fingerprint recognition block is reduced. Accordingly, the transmittance of the fingerprint recognition block and the accuracy of fingerprint recognition are improved.