Under-Display Sensor Light Transmittance via Pixel Removal
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Solution Overview
Problem
In borderless electronic devices with full-face displays, sensors such as cameras and ambient light sensors face significant performance limitations due to low light transmission through the display stack, which is exacerbated by the presence of dense thin-film transistors and other layers.
Innovation Solution
The implementation of a pixel removal region under the display where thin-film transistors, additional layers like the cathode and polyimide layers, and the polarizer are selectively removed or patterned to increase light transmittance, including the use of laser ablation and bleaching techniques to create openings in these layers, thereby enhancing light transmission to underlying sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display covers the entire front face of the electronic device to achieve a borderless full-face display, then the display area is improved, but the light transmission through the display stack deteriorates (transmission less than 20% in the visible spectrum)
Solution Approach 1:
The patent removes thin-film transistors and other display components from specific regions (pixel removal regions) to create openings that allow light to pass through to the sensors. This extraction of unnecessary components from the display stack directly addresses the light transmission problem while maintaining the full-face display appearance.
Solution Approach 2:
The patent applies different structural configurations to different regions of the display. Pixel removal regions are created in specific locations where sensors are positioned, allowing these local areas to have high light transmission properties while the rest of the display maintains its normal structure and full-face coverage.
2Adaptability or versatility
If thin-film transistors are densely packed to control more pixels, then the pixel control capability is improved, but the light transmission through the display stack deteriorates
Solution Approach 1:
The patent selectively removes thin-film transistors from pixel removal regions where sensors are located. This extraction eliminates the obstruction caused by dense TFT packing in those specific areas, allowing light to reach the sensors while TFTs remain in other regions to maintain pixel control capability.
Solution Approach 2:
The display is segmented into different functional regions: pixel regions with full TFT control and pixel removal regions with removed TFTs for sensor access. This segmentation allows the system to maintain overall pixel control capability while creating localized areas optimized for light transmission to sensors.
3Illumination intensity
If additional layers (cathode, polyimide, substrate) are removed to increase light transmittance, then the light transmission is improved, but the display structure complexity increases
Solution Approach 1:
The patent removes additional layers (cathode, polyimide, substrate) from pixel removal regions to create a clear path for light transmission. This extraction of layers simplifies the display structure in those specific regions, allowing sensors to receive light while the overall display structure remains intact in other areas.
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 significantly improves the light transmission through the display stack, enhancing the sensing performance of under-display sensors by allowing more light to reach them, thus overcoming the limitations of traditional display configurations.
Implementation Method 1
The cathode layer may be removed using laser ablation with a spot laser or blanket illumination
Implementation Method 2
A polarizer may be bleached in the pixel removal region for additional transmittance gains
Data Source
AI summary
An electronic device may include a display and an optical sensor formed underneath the display. A pixel removal region on the display may at least partially overlap with the sensor. The pixel removal region may include a plurality of non-pixel regions each of which is devoid of thin-film transistors. The plurality of non-pixel regions is configured to increase the transmittance of light through the display to the sensor. In addition to removing thin-film transistors in the pixel removal region, additional layers in the display stack-up may be removed. In particular, a cathode layer, polyimide layer, and/or substrate in the display stack-up may be patterned to have an opening in the pixel removal region. A polarizer may be bleached in the pixel removal region for additional transmittance gains. The cathode layer may be removed using laser ablation with a spot laser or blanket illumination.