LED Backlight Research Articles

A Test Method to Determine the Optimum Position for the Wi-Fi Module in a Smart TV

Internal Wi-Fi modules are extensively utilized in Smart LED TV sets, as they are a key component in ensuring reliable wireless connectivity. Interference caused by various electronic components, such as the power supply unit (PSU), system on chip (SoC), LED backlighting circuits, HDMI and USB ports, as well as internal speakers located inside the TV cabinet, needs to be minimized. This minimization is crucial to maintain a robust and uninterrupted Wi-Fi connection between the TV set and the Access Point. This study provides a detailed and comparative analysis of how to properly position Wi-Fi modules for optimal performance and maximum efficiency. The focus is on determining the most suitable location within the TV cabinet to reduce signal interference. Through experiments conducted on nine Android OS-based LED TVs, the areas with minimal signal disruption were identified. Furthermore, the study illustrates how strategic placement of the Wi-Fi module can significantly optimize overall connectivity.

Research on the aperture angle-matched collimated illumination method for the dark-state light leakage of LCD target simulators.

Aiming at the problem of overbrightness of the target simulator background for LED backlight panel illumination, a 5° aperture angle-matched collimated illumination method for the target simulator is proposed based on the study of the dark-state leakage of the LCD display device and the scattered stray light of the system. After simulation analysis the method can make the display contrast increase by 3.1 times and solve the problem of dark targets being drowned by the background bright light, which exists in the LED illumination target simulator. It is experimentally verified that the target simulator using the aperture angle-matched collimated illumination method shows a 2.8 times improvement in SNR and effectively reduces the energy of the dark-state background.

Hybrid-Protected Perovskite Quantum Dot Films with Ultra-High Efficiency and Stability for LED Backlighting.

All-inorganic lead halide perovskite quantum dots (PQDs) have emerged as highly promising materials for photonic and optoelectronic devices, solar cells, and photocatalysts. However, PQDs encounter instability and color separation issues because of ion diffusion. Current strategies mainly address stability in green CsPbBr3 PQDs, with limited focus on the red-mixed halide PQDs because of their inferior stability compared with green PQDs. Our study provides a new dual-protection methodology for synthesizing high-efficiency green and red mixed-halide PQD films. Red CsPb(Br0.4I0.6)3 and green CsPbBr3 PQDs are embedded with silicone resin and then incorporated with poly(methyl methacrylate) (PMMA) matrix to form red and green PQDs@silicone/PMMA films. The high photoluminescence quantum yield (PLQY) and great stability are recorded for the pure-red PQD polymer film. The ultrabright green CsPbBr3 PQDs@silicone/PMMA film was also successfully fabricated with an outstanding PLQY beyond 94%. These films exhibited enhanced stability against thermal and environmental degradation, attributed to the dense protective layer of silicone resin and PMMA matrices by the formation of Si-halide and Pb-O bonds, thereby reducing surface defects. Theoretical calculations reveal that combining silicone resin and PMMA improves Pb-O interactions, eliminating uncoordinated Pb2+ and enhancing PQD stability. Applied to white light-emitting diodes (WLEDs), these films demonstrated a broad color gamut of 143.4%, indicating their potential for efficient WLED backlighting.

Phase–Change Liquid Encapsulated Quantum Dot Color Conversion Film for Wide Color Gamut LCDs

AbstractQuantum dot (QD) color conversion films encapsulated with high barrier films are being applied to wide color gamut liquid crystal displays (LCDs). However, besides the expensive cost of barrier films, the aging of QD films under high temperature and high‐intensity blue light remains unresolved. Here, a QD color conversion film is developed using phase‐change liquid encapsulation suitable for roll‐to‐roll film fabrication. In this method, the QDs are encapsulated in the phase‐change material octadecane, which switches between solid and liquid states in response to temperature changes corresponding to standby and operation of the display, respectively. This process endows the self‐healing of QD ligands (liquid state) and effectively increases the lifespan of QDs under ultraviolet (UV) light. This novel phase‐change liquid encapsulation method significantly improves the UV light resistance and long‐term stability of QD color conversion films compared to conventional solid‐state encapsulation. Under conditions of 60 °C, 90% humidity, and 40 mW cm−2 blue LED backlighting, the phase‐change liquid encapsulated QD color conversion film maintains less than 10% brightness degradation for 680 h. This phase‐change liquid encapsulation technology opens new possibilities for manufacturing more durable QD color conversion films.

Development of single-sided structure collimation film for direct-lit collimated backlight module.

In this paper, we proposed an optical structure to enhance the collimation and uniformity of 405 nm LED backlight modules. The structure is called a single-sided structure collimation film (SSSCF), which consists of a lenticular lens array, slit apertures, and a highly reflective coating surface. A lenticular lens array with slit apertures converts the angle of diffusive incident light into collimated light. The high-reflective coating of the collimation film can reflect back the light that does not enter the slit aperture to the backlight module for energy recycling. Finally, we have developed a direct-lit backlight module with optimized collimation properties (FWHM = ±3.4°, gain = 2.3%, NSR = 0) and great uniformity (uniformity > 83.5%). We also demonstrated good consistency between our simulation results with optical measurement. The collimated backlight module developed in this study has great potential for future applications, including high-precision 3D printing objects, liquid crystal displays with high contrast ratio or narrow viewing angles, and telecentric illumination devices used in precision machine vision systems.

Bi3+-activated Na3Ca2TaO6: A novel narrow-band blue-emitting phosphor towards backlight display applications

Bi3+-activated Na3Ca2TaO6: A novel narrow-band blue-emitting phosphor towards backlight display applications

P‐64: Research on Displayable Scheme of Camera Under Panel Based on Automobile Display

CUP (Camera Under Panel) is applied to the automobile and can identify the driver's identity, monitor the driver's fatigue, attention, and monitor dangerous driving behaviors. The commonly used blind hole technology now leads to the inability to display the camera hole area. Therefore, we proposes a scheme for camera under panel applied to automobile, which is based on the Mini LED backlight structure design to achieve full screen display. At the same time, optical simulation analysis and related experiments were conducted to verify the feasibility of the scheme.

65‐4: Patterned Glass Diffusers (PGDs) for Automotive White LED Backlights

Patterned glass diffusers (PGDs) have been demonstrated to reduce backlight thickness and LED count, and increase luminance when used with an optimal film stack in blue mini‐LED backlights. However, they encounter challenges when used in automotive white LED backlights. We report our PGD solution to dimensionally and thermally stable automotive white LED backlight that has an LED pitch of 13 mm.

Pulse-width modulation as a new hygienic factor determining the visual comfort of modern screens

The information revolution and intensive development of electronic devices take place in the recent decades. Furthermore, not so long ago such a hygienic factor, as the display luminance pulse-width modulation (PWM) capable of causing visual discomfort (PWM symptoms) in individuals with increased sensitivity to visual load, has become relevant. The main complaints include eye pain, headache, sometimes nausea, up to the inability to use such screens. Moreover, this characteristic can be peculiar not only to LED (AMOLED, etc.), but also to IPS displays due to the presence of the LED backlight layer. No regulation of the issue has led to the emergence of online resources on PWM and the problem of visual impairment, where users verify the data on their own, which suggests the relevance of the subject selected. The paper reports theoretical aspects of PWM, technical characteristics of displays with PWM; the approaches to PWM measurement are described; the possible ways to reduce visual discomfort are discussed. Furthermore, the paper describes the method to measure PWM of displays using a photo camera with the exposure time set to 1/20 s, along with the method testing results. It has been shown that further research focused on assessing the effects of PWM on vision and the development of the method for hygienic assessment of monitors and smartphone screens with PWM are required.

Introducing the Video In Situ Snowfall Sensor (VISSS)

Abstract. The open-source Video In Situ Snowfall Sensor (VISSS) is introduced as a novel instrument for the characterization of particle shape and size in snowfall. The VISSS consists of two cameras with LED backlights and telecentric lenses that allow accurate sizing and combine a large observation volume with relatively high pixel resolution and a design that limits wind disturbance. VISSS data products include various particle properties such as maximum extent, cross-sectional area, perimeter, complexity, and sedimentation velocity. Initial analysis shows that the VISSS provides robust statistics based on up to 10 000 unique particle observations per minute. Comparison of the VISSS with the collocated PIP (Precipitation Imaging Package) and Parsivel instruments at Hyytiälä, Finland, shows excellent agreement with the Parsivel but reveals some differences for the PIP that are likely related to PIP data processing and limitations of the PIP with respect to observing smaller particles. The open-source nature of the VISSS hardware plans, data acquisition software, and data processing libraries invites the community to contribute to the development of the instrument, which has many potential applications in atmospheric science and beyond.

U2-Net and ResNet50-Based Automatic Pipeline for Bacterial Colony Counting.

In this paper, an automatic colony counting system based on an improved image preprocessing algorithm and convolutional neural network (CNN)-assisted automatic counting method was developed. Firstly, we assembled an LED backlighting illumination platform as an image capturing system to obtain photographs of laboratory cultures. Consequently, a dataset was introduced consisting of 390 photos of agar plate cultures, which included 8 microorganisms. Secondly, we implemented a new algorithm for image preprocessing based on light intensity correction, which facilitated clearer differentiation between colony and media areas. Thirdly, a U2-Net was used to predict the probability distribution of the edge of the Petri dish in images to locate region of interest (ROI), and then threshold segmentation was applied to separate it. This U2-Net achieved an F1 score of 99.5% and a mean absolute error (MAE) of 0.0033 on the validation set. Then, another U2-Net was used to separate the colony region within the ROI. This U2-Net achieved an F1 score of 96.5% and an MAE of 0.005 on the validation set. After that, the colony area was segmented into multiple components containing single or adhesive colonies. Finally, the colony components (CC) were innovatively rotated and the image crops were resized as the input (with 14,921 image crops in the training set and 4281 image crops in the validation set) for the ResNet50 network to automatically count the number of colonies. Our method achieved an overall recovery of 97.82% for colony counting and exhibited excellent performance in adhesion classification. To the best of our knowledge, the proposed "light intensity correction-based image preprocessing→U2-Net segmentation for Petri dish edge→U2-Net segmentation for colony region→ResNet50-based counting" scheme represents a new attempt and demonstrates a high degree of automation and accuracy in recognizing and counting single-colony and multi-colony targets.

In situ precipitation of high efficiency and high thermostability CsPbBr3 quantum dots in borosilicate glass for wide color gamut display

In situ precipitation of high efficiency and high thermostability CsPbBr3 quantum dots in borosilicate glass for wide color gamut display

Ligand-Enhanced Neodymium Doping of Perovskite Quantum Dots for Superior Exciton Confinement.

In this study, all-inorganic perovskite quantum dots (QDs) for pure blue emission are explored for full-color displays. We prepared CsPbBr3 and Cs3NdCl6 QDs via hot injection methods and mixed in various ratios at room temperature for color blending. Nd-doped CsPb(Cl/Br)3 QDs showed a blueshift in emission, and the photoluminescence quantum yields (PLQY, ΦPL) were lower in the 460-470 nm range due to surface halogen and Cs vacancies. To address this, we introduced a silane molecule, APTMS, via a ligand exchange process, effectively repairing these vacancies and enhancing Nd doping into the lattice. This modification promotes the PLQY to 94% at 466 nm. Furthermore, combining these QDs with [1]Benzothieno[3,2-b][1]benzothiophene (BTBT), a conjugated small-molecule semiconductor, in a composite film reduced PLQY loss caused by FRET in solid-state QD films. This approach achieved a wide color gamut of 124% National Television System Committee (NTSC), using a UV LED backlight and RGB perovskite QDs in a BTBT-based organic matrix as the color conversion layer. Significantly, the photostability of this composite was enhanced when used as a color conversion layer (CCL) under blue-LED excitation.

Using (Ba,Ca)ScO2F:Bi3+,K+ phosphor with great performance and strong heating stability for LED backlight screens

diodes emit illumination (LED) display study is focused on straitband green phosphor samples yielding significant effectiveness as well as heating consistency. The cation substitution design technique was used to create Ba1-xCaxScO2F:0.001Bi3+,0.001K+ with x of 0-0.12) perovskite phosphors that emit strait green illumination when activated by a 415 nm chip. The impact of Ca2+ replacement for Ba2+ in the crystal structures of Ba1- xCaxScO2F:0.001- Bi3+,0.001K+ and photoluminescence characteristics were examined. In the space group Pm3m, all of the phosphors have a cubic perovskite-type structure. The development of cell characteristics and the lengthiness of the Ba/ Ca/K/Bi-O bonds were studied. Beneath 415 nm chip stimulation, the phosphors with an interior quantum effectiveness of 77.4 percent produce strong green radiation reaching the peak at 510 nm. The increase of luminous effectiveness and heating steadiness in response to local structural change was thoroughly addressed. The cation substitution design technique discussed here might be a significant way to realizing spectrum modulation by regulating the micro-surrounding within the latticework to achieve outstanding LED backlighting screens.

Optimized Design with Artificial Intelligence Quantum Dot White Mini LED Backlight Module Development

This study delves into the innovation of mini light-emitting diode (mini-LED) backlight module designs, a significant advancement in display technology. The module comprises a substrate, a receiving plane, and an LED structure, which uses a blue light with specific spectral characteristics. When combined with a red-green quantum dot (QD) film, it produces white light. For improved illumination uniformity, the Mini-LED structure was optimized with a focus on the thickness and concentration of layers, especially the TiO2 diffusion layer. A comprehensive design methodology using LightTools (8.6.0) optical simulation software was employed, linked with MATLAB (R2022a) for varied parameters and using the double deep Q-network (DDQN) algorithm via Python as a reinforcement learning agent. This approach facilitated optimal architecture design based on illumination uniformity. Also, the bidirectional scattering distribution function (BSDF) was employed to calculate the scattering properties of the backlight module’s surface, providing accurate simulation results. The DDQN algorithm enhanced the learning design, reducing simulation runs by 76.7% compared to traditional methods. The optimized solution achieved an impressive illumination uniformity of 83.8%, underscoring the benefits of integrating advanced algorithms into display technology optimization.

Low complexity local dimming algorithm for high quality head up displays in automotive vehicles

We present a high image quality head up display (HUD) based on the local dimming liquid crystal display (LCD). The proposed HUD provides high white luminance to improve day-time visibility and low black luminance to cope with the postcard effect during the night by the local dimming technique. To reduce the computational complexity, the pixel-based boosting values for the pixel compensation are computed by simple bi-linear interpolation, complex power functions are implemented by look-up tables, some multiplications are replaced with the sums of shifted values, and the numbers of look-up tables and multipliers are reduced by sequential process. The simulation results of the proposed local dimming algorithm for 640×1280 LCD panel and 10×22 LED backlight ensure higher peak signal-to-noise ratio than 40 dB and larger power reduction performance than 73% over 7 HUD images. In addition, the postcard effect improvement is verified over images on LCD panel as well as windshield. Maximum luminance and contrast ratio on the windshield of the prototype HUD system are measured as 16,088 cd/m 2 and 342 × 10 6 :1.

63‐3: A Small Aspect Ratio High Voltage Mini LED Solution for Glass‐Based MLED Backlighting

In order to improve the cost‐effectiveness of COG Mini LED backlight products, this paper proposes a small aspect ratio high‐voltage Mini LED solution. This solution reduces the Cu thick traces of the glass substrate by means of high‐voltage driving, thereby reducing the cost of BP. At the same time, with the structure design of 1:1 aspect ratio, it can effectively reduce the die‐bonding skew and improve the product yield. At present, the solution has been verified many times with MNT products, which proves the feasibility of the solution and plays an important role in promoting COG Mini LED products to seize the MLED industry opportunities.

59‐3: Application of 3D printing in the reflector of glass‐based Mini LED Backlight

This paper mainly introduces a method of making Mini‐LED backlight reflective layer by 3D printing technology. Compared with the conventional method, this method improves the optical brightness and the yield of the product while simplifying the technological process.

Preview the Products on Display at Display Week 2023

Preview the Products on Display at Display Week 2023

P‐12.5: Optical film microstructure design for ultra‐thin MiniLED backlight modules

The backlight module is a key component for providing a light source for a Liquid Crystal Display (LCD), and its thickness has a direct impact on the thickness of the display. In order to reduce the thickness of the display product, it can be realized by reducing the thickness of the backlight module. In order to solve this problem, this paper proposes a design method for the microstructure of the optical film applied to the mini LED backlight module. The microstructured optical film designed in this paper can effectively improve the uniformity of brightness and realize the ultra‐thinning of the backlight module. Based on the principle of total reflection, the optical film microstructure is designed for the miniLED Lambertian light source. Under the assumption that the point light source is established, the extended light source is discretized into point light sources, and then the light energy that can be used for circulation is calculated for each point light source, and all point light sources The cyclic energy of is accumulated as the cyclic energy corresponding to the extended light source, and when its value is the largest, the best shape of the microstructure is obtained. The simulation results show that after adding the microstructured optical film, the illumination uniformity of the backlight module reaches 91.2%, which meets the uniformity requirements of the backlight module. The method of designing microstructured optical film proposed in this paper can effectively realize the ultra‐thinness of the backlight module and has strong practicability.