As an important trend in future display technology, Micro-LED has significant advantages in brightness and contrast, as well as better color performance and response speed. Micro-LED and related display technologies have attracted increasing attention from the academic community in recent years. However, Micro-LEDs with Lambertian emission patterns cannot be directly used in projection displays. Therefore, complex relay optics are often required to collimate the emission light, increasing the system complexity. This paper proposes a novel Micro-LED structure that combines with meta surfaces on top of the Micro-LED. This structure can optically control the light field of Micro-LED into a highly collimating one from the originally Lambertian distribution. Compared with the initial Micro-LED structure, this configuration has good light emission characteristics with primary light concentration between 10 degree intervals. The designed structure has the light distribution with the full width at half maximum (FWHM) angle ±5.48°. At the same time, compared with the traditional Micro-LED structure, its center light intensity is increased to 21.98 times the original. This structure optimizes and improves the performance of Micro-LED in the field of projection display.
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.
Mini-LED backlight and quantum-dot color conversion (QDCC) technology are the research hotspots of emerging display technology. When they are combined together, the luminance uniformity issue may occur because of traditional QDCC film (QDCCF) with uniform thickness. This paper designs and optimizes QDCCFs with non-uniform thickness of cone and circular truncated cone, respectively. The illuminance uniformity is analyzed by simulation. Results show that the illuminance uniformity of the optimized cone and circular truncated cone with a single structure can reach 73.97% and 74.72%, respectively. The single structure with uniform thickness is only 35.84%. After that, the single structure with nonuniform thickness is arrayed with a basic substrate added at the bottom, which is matched with the mini-LED backlight. By optimizing the array configuration and the basic substrate, the illuminance uniformity of the backlight reaches 73.55% and 79.25%, respectively. This QDCCF with non-uniform thickness distribution can effectively improve the illuminance uniformity when mini-LED is combined with QDCCF. This work proposes a new strategy for uniform color conversion of mini-LED display backlights.
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.
In order to improve high efficiency for light-color conversion, this paper studies a high-efficiency light recycled structure for quantum dot color conversion (QDCC) based on a distributed Bragg reflector (DBR). The difference of optical performance is discussed between the QDCC structure employing a DBR and an absorptive color filter (ACF). Traditional quantum dot color conversion layer (QDCCL) has inherent limitations of blue light leakage and low light utilization rate. To solve this, an optical structure of QDCCL is proposed and discussed in detail, which uses a DBR instead of the traditional color filter and realizes efficient light-color conversion. Different structures are compared via experimental preparation and measurement, such as light-emitting intensity, color gamut, and light utilization rate. Results show that the structure of QDCCL combining a DBR can not only achieve a high color gamut of 124 NTSC%, but also increase the light utilization rate over twice than the traditional ACF structure. More importantly, the light emission intensity of red and green sub-pixels is increased by 2.2 and 2.3 times, respectively. In general, the structure proposed in this paper is of great significance to the development of the display industry.
Light guide plate (LGP) plays an irreplaceable role in backlight module of liquid crystal display (LCD) systems. Based on interactive design of Gtools and Tracepro, we propose an effective design method of scattering dots array for LCD backlight in this paper. This method first initializes the scale of the scattering dots in Gtools, then evaluates illumination distribution in Tracepro, and finally determines the array layout of the scattering dots from the interactive optimization between Gtools and Tracepro. This method can flexibly adjust the light emission in each sub-area of the LGP, which has scientific significance and practical value in some ways.
Light Guide Plate (LGP) plays an irreplaceable role in Liquid Crystal Display (LCD) backlight. LGP with quantum-dot (QD) shows promise in the development of next-generation displays because of QDs’ beneficial characteristics. In this paper, we present a novel QD LGP for LCD backlight based on QD scattering microstructure array (SMA), in which the QD net dots are located discretely and arranged in arrays on the bottom surface of LGP. The paper first introduces the QD backlight briefly, then discusses the preparation and fabrication process of the proposed prototype, and finally presents a systematic photometric approach to reveal the remarkable advantages of QD backlight. The white-balance is achieved by adjusting the proportion of the QDs in the mixture and optimizing the R-QD / G-QD ratio. The apparent morphology of QD SMA is characterized by OLYMPUS laser microscope, while the optical properties of QD backlight are investigated by F-4600 fluorescence spectrophotometer and SRC-200M spectrum color luminance meter, respectively. Experimental results show that the white balance can be achieved when the QDs account for a certain proportion about 7% within the mixture, and the ratio of R-QD / G-QD is optimized to about 1:12. The proposed system offers an alternative and feasible method for fabricating QD backlight, which may have great application prospects in the future.
Field of view (FOV) of the fisheye lens is close to or even higher than 180°, which brings about extraordinary imaging effect that the visual range would be far wider than the human eye perspective. However, the wide visual range of the fisheye lens is always at the expense of image quantity, so that the images obtained by fisheye lens would inevitably show a large degree of distortion aberration. In this paper, we propose an improved distortion calibration algorithm of longitude-latitude mapping to eliminate the image distortion aberration caused by fisheye lens. This method does not need to depend on a specific physical camera and has general and universal significance. By using Matlab as a mathematical analysis tool, the verified experiment and the corresponding write code is performed to correct a specific fisheye lens’ image based on the previously proposed algorithm. A reverse mapping is used to avoid cross-border problems, and comparative experiments are also analyzed to show the difference between the image processing with the traditional and the proposed algorithm. Experimental results demonstrate that the proposed algorithm can better achieve the correction of fisheye lens distortion. The twisted lines that are not expected can be well corrected into the straight lines. This method can not only reduce the problem of horizontal stretching of the image, but also make the processing results visually consistent with people's viewing habits.
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