BackgroundRecently, micro-light-emitting diode (micro-LED) displays have gained significant interest from both industry and academia due to their exceptional performance. However, the integration of micro-LED with the driver substrate during the fabrication process remains a pressing issue that needs to be addressed.AimWe plan to realize high-yield bonding of micro-LED displays by adopting new materials.ApproachWe opted for a photoresist with conductive properties by incorporating carbon black as the bonding material to fabricate a micron-level bump array.ResultsThis method, using only photolithography, achieves a yield of 99.99% or higher in a single step. It eliminates the need for time-consuming processes such as lift-off and vaporization in the traditional metal bump preparation process. The resulting array can be directly used to establish electrical connections with the micro-LED array. After fabrication of the bump array on the thin film transistor (TFT) driver substrate, the 80×80 micro-LED array was integrated into the TFT substrate, and after baking, a device yield of over 99.9% was attained.ConclusionsThis work presents a streamlined and more effective method for integrating the micro-LED and TFT driver substrate, resulting in significant reductions in both time and economic expenses associated with the production process of micro-LED displays.
Micro light-emitting diode (Micro-LED) has the advantages of high brightness, low power consumption, and long life. It has great potential and broad application prospects. Using micro-LED as the light source and image source of the projection system can greatly reduce the size and power consumption of the system. However, the electrical module and the optical module of the micro-LED pico-projection system cannot be separated. This paper uses image fiber to effectively separate the electrical module and optical module in the optical engine, and designs a micro-LED pico-projection optical engine based on an image fiber. This optical engine is composed of a projection lens group, an image fiber and a micro-LED. The projection lens group is composed of 5 spherical lenses, with the total length of 6.752mm and the focal length of 2.8mm. The modulation transfer function (MTF) is higher than 0.8@32lp/mm, and the distortion is below 2%. The image fiber adopts a multi-core fiber with a diameter of 2mm and a resolution of 32lp/mm. Finally, the overall simulation model of the optical engine is built to prove its feasibility.
This work proposes a research scheme to speed up the design of metasurface skin cloak through low-complexity phase monitoring model and deep learning. This skin cloak conceals a three-dimensional arbitrarily shaped object by complete restoration of the phase of the reflected light at specific wavelength. And the possibility of realizing spectral prediction by deep learning is analyzed. During the study, a phase monitoring system was designed in which the detector, the light source and the monitored nano-antenna were sequentially distributed at equal distances from the emitted wavelength of the light source, so that the monitored phase amount was exactly equal to the phase change before the reflected wave, thus eliminating the need for multiple monitors to measure and calculate the phase change before and after the reflection. The traditional metasurface design is usually constructed by manual library construction based on the phase distribution and the relationship between phase variation and dimensional variation of the cell structure, so this work combines the aforementioned monitoring model with deep learning to generate the database required for modeling. The two variable parameters of device length and width were first defined, and the reflected wavefront phase change used as the optical response, and we reprocessed the original data and finally build and trained an artificial neural network model for forward prediction of optical response. This network can obtain its MSE below 0.001 for the test set after the training is completed. Thus the scheme can replace the role of simulation software to some extent, and its prediction process can be completed in a few milliseconds, improving the efficiency of the design metasurface process.
Micro-LED will probably become the next epochal display technology, which has combined the advantages of liquid crystal display (LCD) and organic light-emitting diode (OLED). Its self-luminous characteristic will greatly compress the volume of the projection optical engine into truly pico-projection level. However, the relevant design and research are still insufficient. In this paper, we design a four-piece sphere lens group with a 5 mm focal length for micro-LED pico-projection, and then a simulation model of self-luminous projection optical engine is built for demonstration. The total length of the projection lens group is only 8.2mm, the modulation transfer function (MTF) is higher than 0.5@66lp/mm, and the distortion is below 1%. The irradiance distribution shows that the light efficiency is 44.9 % and the uniformity reaches 81.3% when the light divergence angle of micro-LEDs is set to 30°. Then, we explore the influence on light efficiency with different light source divergence angles and determine the optimal range of divergence angles. Finally, a R/G/B integrated micro-LED source with blue light and the above red/green quantum-dot color conversion (QDCC) layer is built, proving the feasibility of a full-color pico-projection optical engine with a single-integrated micro-LED chip.
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