Papers by Keyword: Backlight

Abstract: To replace the color filter in the conventional display, we describe a color-separation backlight consisting of three modules: the light collimation module, the light guide and the micro-lens array. With angularly positioned color LEDs, the displaying method requires only two two-color filter layers to display color images. In the light collimation module, the angular rays of two colors from each LED are collimated by a reflective cup and a collimation lens. After entering the light guide, which is composed of V-groove structures at the bottom above a reflective layer, the angular collimated color beams are redirected to the normal of the top surface of light guide. Finally, the output rays are converged by a micro-lens array and mapped into corresponding sub-pixel positions for efficiently displaying color image. The three main advantages of such technology are the reduction of the dye color filter layers from conventional 3 to 2, the gain factor of transmission efficiency two times more than that of conventional color filters, and the larger color gamut.

Abstract: A new algorithm is proposed to adjust backlight luminance for local dimming of liquid crystal display (LCD) devices. PSNR (the peak signal-to-noise ratio) =30 is acted as the lowest standard to guarantee the quality of image in the algorithm. Based on the formula of PSNR=30, the square error value of the image distortion is gained. Then, luminance of backlight is gained dynamically by that the maximum gray level minus 1 into the formula proposed in the paper and decreases by one after each trial if the image quality requirement is not satisfied. In order to simplify the calculation, three important gray level values are selected to meet the requirements. The results show that the algorithm can greatly reduce the power consumption with guaranteeing the image quality and furthermore save much time in calculation and be better applied in hardware.

Abstract: The paper proposes a global backlight dimming algorithm for CR enhancement and power reduction. S-shaped function is involved to help improve CR. Both the backlight dimming level and the turning point grayscale of the s-shaped curve are determined by the histogram of the input image. The pixels with the grayscales more than the turning point are compensated to become brighter and the pixels less than turning point become darker. The simulation results show that the proposed dimming algorithm can improve CR by average 34.95% and reduce power consumption by 11.30%.

Abstract: Different from common commercial liquid crystal displays (LCDs), LCDs in military applications have some special requirements including high luminance, wide operating temperature, and night vision compatibility. This paper designs a direct-lit LED backlight for a 5 in×5 in LCDs and puts forward three solutions for heat dissipation. The simulation results show that the solution of 17×17 LED array on common opening FR4 PCB can satisfy the requirement.

Abstract: At present, the large backlight modules, used in illuminating advertising pictures, are designed and developed in various specifications, whose common goal is to try to manufacture thinner backlight modules and produce more uniform illumination. The currently well developed backlighting technology for liquid crystal displays (LCDs) can be transformed and used in such an area. However, the design of edge-lit backlight with size of over 1 square meter has great difficulties in eliminating the phenomenon of non-uniform illumination. In this paper, the application of Bezier curve in the simulating the dot pattern on the bottom of light guide is presented, which directly determines the final light extraction efficiency and illuminating uniformity. Taking the RMS deviation of illuminance values at several sample positions as the merit function, the shape of Bezier curves can be smoothly changed, so that the dot radius can be optimized in a fast and efficient way. Such an optimization procedure uses only two variables and has a fast convergence. As an example, a large light guide, 800mm×1000mm in size, was designed by applying the Bezier method, and the final uniformity of 70% was achieved. The most prominent feature in such a method is that the thickness of designed light guide can decrease to 5 mm. In sum, the large sized edge-lit backlight can be designed in a short optimization period by simulating the dot radius distribution in a shape of the Bezier curve.

Abstract: This paper proposes a backlight system that generates the regular dot pattern on the bottom of light guide to achieve uniform luminance. The simulation program employs the variable r-cut technique combined with some regular dot pattern such as shift-rectangular, hexagonal and so on. The r-cut technique based on molecular-dynamic method, was first bought up to apply in the random dot pattern. By using such a technology, we could easily evaluate the right range of radius within each cell to get the general dot distribution according to the specific position away from light sources and the sources properties, after we divided the total effective domain into several sections of cells. In the end we made some fine-tuning on the boundaries to obtain the final result. It has been revealed in the simulation that the light guide can achieve a uniformity of more than 90% and optical efficiency about 26%. What we have more interest in are the optical properties that have much influence on both the uniformity and the optical efficiency. Particularly when it comes to larger size backlight products used in PC screen for instance, it will have a great impact. Several figures in this paper also illustrate the dots distribution and the illuminance distribution.

Abstract: A wide angle light-deflected lens combining collimation and total internal reflection (TIR) optical mechanics for LED package is proposed. Utilizing angle-dividing method the angle of emitting distribution of LED chip was cut into several angular zones and then a light-collimating curve surface with corresponding declined plane performing TIR for the collimated incident ray was designed. Thereby, the light-deflected lens, consisting of multi pairs of collimating curve surfaces and declined planes, can achieve wide-angle deflection of light emitting from LED chip. The design rule and experiment results of the lens with optimization optical design are demonstrated and discussed in this paper.

Abstract: MEM (Micro-Electro-Mechanical System) is the integration system of mechanical elements, sensors, actuators, and electronics on a silicon substrate using the micro fabrication technology, in general. A new MEMS formation technology is proposed in this paper. The improved drop-on-demand ink jet was used and the MEMS was formed on the plastics and silicon substrate. The plastics resins were injected from the drop-on-demand head on the substrate and the dropped resins were cured using ultraviolet rays. Thus micro lenses were formed.

Abstract: Generally, the light guiding plate is fabricated by injection molding. Polymethyl methacrylate (PMMA) material is used to fabricate the light guiding plate. In order to reduce the space of backlight, the light guiding plate is based on double-side microstructures by using MEMS and hot-embossing technologies. From the experimental results, the minimal illumination is 355 lux and the average illumination is 368.1 lux, the uniformity of illumination is 0.08. The novel integrated light guiding plate is achieved a uniformity of distribution, without any optics sheets. In this paper, non-prism LGPs, micro-prism LGPs, and the double-side hot embossing LGPs are fabricated.