Microprism Structure Research Articles

Two-dimensional distribution design of micro-prism for partial integrated light guide plate

The microstructure distribution on the bottom surface of the partial integrated light guide plate (PILGP) is the key to affecting the uniformity of the output light from the backlight module (BLM), which is one of the important factors in the BLM design. Based on the development trend of the BLM in light-weight and integration, many research institutes have realized the requirement for high luminance and luminance uniformity in the BLM by setting micro-prism structure on the surface of the light guide plate (LGP). In most of these studies, the length of the micro-prism structure is the same as the width of the LGP, and the optimization of the micro-prism distribution is performed only in the length direction of the LGP, which is a one-dimensional distribution. So, the long strip micro-prism structure cannot modulate the light in the axial direction, resulting in large area identity in the width direction of the LGP, thereby the luminance uniformity of the BLM is affected. In this paper, a design idea of two-dimensional distribution of the micro-prism on the bottom surface of the PILGP, which improves the luminance uniformity of the BLM, is proposed to solve the problem that the luminance uniformity is affected by large area identity caused by one-dimensional distribution design of the micro-prism. The small length micro-prism structure is used to break the limit of the axial distribution of the long strip micro-prism structure, and it can modulate the light in the axial direction. The Lighttools software is used to optimize the two-dimensional distribution of the micro-prism on the bottom surface of a 5.0-inch PILGP. Comparing with the PILGP with one-dimensional distribution of the micro-prism on the bottom surface, the simulation results show that the utilization of light energy, illuminance uniformity and luminance uniformity in the BLM with optimized two-dimensional distribution of the micro-prism on the bottom surface of the PILGP respectively reach 92.03%, 87.07% and 91.94%, which meet industry standards. And the illuminance uniformity increases by 10%. Meanwhile, the luminance diagram shows that the overall luminance uniformity of the BLM is improved effectively. Moreover, the distribution principle of the micro-prism on the bottom surface of the PILGP is analyzed and the physical mechanism is reasonably explained . The simulation results above show that the design concept of the two-dimensional distribution of micro-prism is feasible. The study results have a certain referential value for the development of the BLM in light-weight and integration.

An Iterative Method for the Uniformity Improvement of Edge-Lit Backlight

A simple iterative optimization method is developed to improve the exiting light uniformity of the edge-lit backlight module. The method uses the relative deviation of the average luminous flux of the entire light guide plate (LGP) and the luminous flux of each region as constraint criterion and the ratio of the luminous flux of each region to the average luminous flux of the LGP as adjustment coefficient to adjust the density of the microstructures in each region. This process loops until the relative deviations of all regions meet a prespecified threshold value. A LGP based on microprism structure is presented to validate the method. The initial values, which represent the size of the microstructures manufactured on the bottom surfaces of the LGP, d0-dependent luminous fluxes, microstructure size distributions, iterations of the LGP, and the relative deviation of each region are discussed. The simulation results show that it is a very practical method for the uniformity improvement of the backlight when an appropriate initial value is selected and the final uniformity is better than 90% after optimization.

Effect of Ultrasonic Electroforming Process Parameters on Reflective Performance of Nickel Casting Layer

In order to improve the reflection coefficient of nickel electroforming layer with microprism structure effectively, controlling electroforming process strictly and adjusting different process parameters are needed for achieve the best electroforming effect. Nickel casting layer was prepared by ultrasonic direct current electroforming on the microprism nickel plate. Surface reflective coefficient of nickel casting layer was measured by retroreflectometer, and the morphology was observed by 3D laser scanning microscopy system. The effects of ultrasonic power, frequency and average current density on the surface reflective performance were studied, experimental results were verified by measuring microprism side surface roughness. The results show that reflective coefficient of nickel casting layer prepared by high frequency ultrasonic electroforming was greater than that by low frequency with other experimental conditions remaining unchanged. It was increased first and then decreased with ultrasonic power and average current density increasing gradually, and the surface roughness measurement also verified this conclusion.

Design and fabrication of a novel prism for micro-optical system

This study presents a special k-type (45°, 135°) microprism structure design for the lateral-type semiconductor laser of optical systems. This study combines front- and back-side inclined exposure technology to develop a k-type microprism structure and replaces the optical prism manufactured through traditional machine processing or injection molding with a new polymer (thick-film negative photoresists) micro-optical prism structure. To obtain the optimal structural surface roughness (12-15 nm at 400 μm×400 μm area), the percentage of polymer material loss caused by the solvent was controlled. This roughness level meets Blu-ray specifications (λ/10, λ=405 nm).

Edge-Lighting Light Guide Plate Based on Micro-Prism for Liquid Crystal Display

We designed an edge-lighting light guide plate (LGP) based on a micro-prism structure for liquid crystal display. Its top and bottom surfaces have micro-prisms, and a layer of high reflection film is coated on the bottom surface. The principle of the LGP was analyzed. The optical simulation tool ASAP was used to calculate the apex angle and height of the micro-prism on the top of the LGP, the apex angle of the micro-prism on the bottom of the LGP and the emitting angle dependent luminous flux of the LGP. By adjusting the width of micro-prisms on the bottom, the LGP achieved uniform luminance. A 12-in LGP based on a micro-prism structure as an example was designed. The results proved that the LGP based on a micro-prism structure is thin and simple with uniform luminance and high efficiency.

Fabrication of a novel integrated light guiding plate by microelectromechanical systems technique for backlight system

A backlight panel (BLP) with a cold cathode fluorescent lamp (CCFL) light source, which is referred to as the backlight unit (BLU) is considered in the light module of a thin film transistor (TFT) LCD. A typical BLP is comprised of a light-guiding plate (LGP) and some optical components, such as reflective sheets, diffusive sheets, and prism sheets. We propose an integrated LGP that combines three functions of optical components by using microelectromechanical systems (MEMS) and hot-embossing techniques. The microprism structure, the micropyramid structure, and an aluminum thin film are used for the integrated LGP not only to eliminate the five optical components, but also to save the space and the cost of the BLU. From experimental illumination results, the maximum illumination is 426.1 lux and the minimum illumination is 370.4 lux. Thus, the integrated LGP achieves a uniformity of illumination of 86.9%. The new BLU could be simplified as only one integrated LGP and only one white LED light source without using any optical components. We anticipate that the integrated LGP could make the displays thinner and brighter for thin LCD application.