Papers by Keyword: Light Guide Plate

Abstract: To solve the problem of nonuniform indoor illumination by sunlight and to meet the need of energy conservation, we design a kind of cuneiform light guide plate to transmit sunlight from outside to rooms relying on the law of total reflection. Theoretical deductions and numerical simulations are used to obtain a preliminary plan, and some issues on applications and feasibility are discussed.

Abstract: Micro injection molding is used widely owing to its high accuracy, high production efficiency, low cost and can fabricate products with complex structures. For optical components, the residual stress is a main element for quality. In this research, the light guide plate is used as the study object. The light guide plate was designed by software Pro-E, and was simulated by Moldflow for filling process. Orthogonal method was used in this research. The most important factor that affects residual stress level is mold temperature. The level of the different process parameters on residual stress are mold temperature, packing time, packing pressure and melt temperature.

Abstract: Defects such as black spots and yellow surfaces appeared in the process of injection molding light guiding plate as a result of the failure surfaces of the screw and screw tip. To choose and optimize the solutions of different surface treatments of the special screw for light guiding plate, the stripping performance testing platform was established. The experimental results showed that TiN and TiAlN or similar coatings by physical vapor deposition could significantly reduce the adhesion force between polycarbonate (PC) and different coatings. Through surface topography analysis of diversified coatings with SEM and AFM, TiAlN coatings represented the excellent surface quality of its smoothness, continuum, and low surface wave. To enhance the bonding force between the molding screw and coatings, TiAlN/Cr and TiAlN/Ti multi-films was developed which owned much more firm bonding force than TiAlN and good surface quality to be suitable for the special screw for manufacturing light guiding plate.

Abstract: Sticking problems in injection molds are a significant challenge in product quality control. Molds are usually coated with a surface ceramic layer to prevent sticking problems. This study presents two films deposited on light-guide plate microinjection molds using an unbalanced magnetron sputtering process to investigate the anti-sticking property of molds. The deposited film materials include chromium nitride (Cr-N) and zirconium containing diamond-like carbon (Zr-DLC). The anti-stick film properties examined here include water contact angles, the coefficients of friction, as well as product flatness for the practical injection process. The results show that the performance of Cr-N films involve water contact angles at 111.4 degrees and a coefficient of friction at 0.742, respectively. The performances of Zr-DLC films involve water contact angles at 86.2 degrees and a coefficient of friction at 0.106, respectively. For the practical injection process, the deposited Cr-N films have better anti-sticking property than do the deposited Zr-DLC films.

Abstract: To improve the quality of the light guide plate (LGP) made by injection molding, a fabrication method based on hot embossing was proposed. The silicon mold of the LGP with micro pyramid array was fabricated by wet chemical etching. The experiments of embossing the LGP were performed with a self-designed hot embossing machine. Orthogonal method was used to analyze the imprint pressure, the holding time, the imprint temperature and the width of pyramid with respect to the accuracy of replication (AOR). The experimental results show that the imprint temperature has the greatest effect on the AOR, followed by the imprint pressure and the holding time, while the width of micro pyramid has the minimal effect on the AOR. The increase of imprint temperature can obviously improve the pattern filling quality in the lower imprint pressure (0.7MPa). At last the optimal process parameters were obtained with the imprint pressure of 0.9MPa, the holding time of 5min and the imprint temperature of 130°C.

Abstract: The light guide plate is an important element of the LCD backlight module which demands a certain degree of transparency and uniformity of gray. The defects such as black spots and yellow surface appeared when the light guide plate was processed by domestic equipments. The main problem was caused by the plasticization unit. The Influencing factors of performance for polycarbonate (PC) special screw were discussed in this paper. The conveyance capacity of melt in the metering zone of injection screws with different flight width and channel depth was analyzed by POLYFLOW software. In order to obtain high surface hardness, corrosion resistance and smoothness of PC special screw, surface coating processing was the key point for injection molding light guide plate. Moreover, the peel strength of PC with different coating processing metallic block was tested and measured. he experimental results of the analysis showed that the nickel-tungsten alloy plating and physical vapor deposition can significantly improve stripping properties, corrosion resistance and smoothness. The influencing factors of coating and PC materials’ stripping were analyzed. Through industrial testing, the defective rate of light guide plate had been greatly reduced with physical vapor deposition compared to the screw with hard chromium plating.

Abstract: A novel light guide plate (LGP) with sub-micron gratings (SMGs) on its upper surface is proposed to control the illumination angle and its initial structure of LGP is given. The periods of SMGs are 0.651μm, 0.516μm and 0.433μm for the LED light sources transmit out vertically with the incidence angle 45º under the total internal reflection condition. The transmission efficiencies vary between 2% and 43% when the depth of grooves of SMGs changes between 0.05 μm and 0.9 μm by using rigorous coupled-wave theory (RCWT). The results show that the LGP utilizing the characteristics of the SMGs can control the transmission angle and get homogeneous output.

Abstract: This study develops a highly-efficient light-guide plate for edge lighting backlight module that has no optical films. The light guide plate is designed to control the angle of the incident rays to the top surface from light source, to get the highest uniformity of intensity for thin edge lighting backlight system applications. The micro-prisms of pyramidal shape on the top surface can highly-efficient collimate with the light rays. Another micro-prism of v-cut shape on the bottom surface can reflect the incident light into the front direction and mixing the rays in the lightguide plate with the high uniformity. A novel design concept of the v-cut is the regular density varies of the cut in the LGP. The modeling simulation program, employing a Monte Carlo method based on TracePro software, has optimized the shape of the pyramidal micro-prisms on the top surface and the density distribution condition of the v-cut micro-prisms on the bottom surface, also the multiple scattering characteristics. The two types of the micro-prisms at the top and bottom surface can be highly recommended for the uniformity of the brightness via the optimal design process. Future work is warranted on improving the optical efficiency by using light-emitting diodes as a light source. The backlight module will allow us to increase the optical efficiency and to lower the total cost in portable LCD applications. The study confirms that a uniformity of brightness can be achieved without using any optical films, resulting in a high uniformity of 84%.