The optical lens model which is constructed by the method of luminous flux mapping and reshaped according to the
target grids modification is demonstrated in this study. The design method was tried on designing LED road lighting
devices which were further confirmed by optical simulations and verified by experiments.
We propose a recessed pyramid microstructure (PYM) to be used on the base of the light guide as micro-optical components to replace the conventional diffuser dot made by direct etching on the steel stamper. The PYM is made by microelectromechanical systems technology, which uses a silicon wafer for the original PYM mold, which is replicated on a Ni micromold using the electroforming method. An effective optical design tool is used to find the optimal PYM distribution integrating the random microstructure generation scheme based on the molecular dynamics method into optical commercial software. The scanning electron microscopy images show intact PYMs can be produced on the Si micromold and then replicated fully on the Ni micromold by the electroforming process. An intact PYM on the base of the light guide can then be produced by injection molding, completing the transformation of the Ni micromold for use in the light guide. The luminance measurement of a 2.4-in. backlight module with four LEDs shows an average luminance of 4769 nit with 86.3% uniformity for the PYM on the base of light guide, 10% higher than that of the diffuser dot microstructure.
We propose a molecular dynamics method dot generation scheme incorporating the periodic boundary and fixed-cell boundary geometrical conditions to generate random dot distribution on the order of several million dots for use in the base of a thin light guide. In addition, the generation scheme can be used to easily adjust the dot density at any local region from illuminance causing feedback in the optical design phase. Based on the incorporation of these two geometrical conditions, the generation of the random dots for the whole LED light guide can be simplified to just three subdomains, one domain represented by the periodic boundary condition, and the other two domains represented by the fixed-cell boundary condition. Employing these conditions significantly shortens the computational time necessary to obtain optimal random dot distribution and subsequent optical optimization on a PC using optical commercial software.
This study proposes a generation scheme for the light guide of the edge-lit backlight using a microstructure with a
pattern combining variable aspect ratio and a variable microstructure orientation, based on the molecular dynamics
method of a generalized force model. This generation scheme is necessary to accommodate the need for the subsequent
optical design phase, and allows for easier optical optimization for the microstructure distribution in order to reach the
equal luminance condition. These needs are met by the cell division, which allows the adjustment of the microstructure
density in each sub-domain, or cell. The boundary treatments allow the precise control of the microstructure density in
each cell and the ability to smooth the microstructure distribution across the cell boundary. Finally, the performance of
this generation scheme, as well as a practical example combining this scheme with the optical design, is shown and
discussed.
This paper presents a molecular dynamics (MD) scheme for the automatic generation of dot patterns for the light guides
used in LCD backlight modules. Several MD computational techniques are integrated with the conventional MD scheme
to enable the adjustment of the dot density in specific regions of the light guide in order to create a dot distribution with a
high dot density variation and a high spatial uniformity. These techniques include the cell division technique, the
variable r-cut technique, the boundary smoothing technique and the reflective boundary condition. The reflective
boundary condition enables a precise control of the dot density within each cell, and is instrumental in achieving a dot
distribution with both a high dot density variation and a high spatial uniformity. The performance of the proposed dot generation scheme is verified by considering the practical example of the dot pattern design of a light guide with a single LED light source located in the lower-right corner. The numerical results confirm the ability of the proposed method to achieve an even luminance condition by establishing a dot pattern whose density increases concentrically with an increasing distance from the light source.
This paper employs a regional partition approach to establish the optimal distribution of the diffuser dots in the light guide of an edge-lit backlight. The proposed approach commences by dividing the light guide into a number of partitions and assigning an equal radius to every dot. An iterative optimization procedure is then performed in which the illuminance in each partition is calculated and the dot radius in each partition progressively adjusted until uniform luminance is obtained over the entire light-guide surface. To simplify the geometry construction process and improve the efficiency of the optimization procedure, a simple optical model is proposed for the diffuser dots and the bare surface of the light guide, and an analytical procedure is implemented to take account of the diffuser-film and brightness-enhancement-film effects. The simulation results confirm the ability of the proposed approach to accurately reflect the fine regulation of the dot radius required to obtain uniform luminance for typical light-emitting diode configurations used in practical backlight modules.
The random dot pattern generation by the use of molecular dynamics (MD) is proposed to the light guide design used for the backlight. Several numerical techniques are developed to provide the great advantage for the combination the subsequent optical optimization for the dot density adjustment satisfy the uniformity requirement demanded by the LCD display. The cell divisions technique is proposed, which allows the dot density adjustment within each cells dividing from the light guide. In addition, the technique is developed to account for different cells to localize the repulsive force acting within the cell to achieve high dot density gradient in the dot distribution. Moreover, the average force control technique is developed to handle the uniformity of dot distribution across the cell boundary. Finally, several illustrations are included to show the validity the robustness of the proposed MD dot generation algorithm.
This paper presents a mathematical method to estimate luminous flux and luminance of single panel and dual panel light guides based on photometric calculations under various design requirements. The distribution of dot pattern or micro-prism was computed according to those estimated luminous flux on the illuminant surface. The effects of light source efficiency, angular distribution of luminance of light guide, luminous flux ratio and area ratio of main panel with sub panel on luminance of light guide are discussed. The relationship between luminous flux and luminance was derived for single panel and dual panel light guides. For single panel light guide, the result reveals that the angular distribution of luminance of light guide affects the luminance obviously. The luminance increases as the cone angle (the range of angular distribution of luminance) decreases. For dual panel light guide, the luminous flux of three different areas, two located at main panel and one located at sub panel, are the functions of angular distribution, luminous flux ratio and area ratio. The luminance of main panel and sub panel were estimated and computed from mathematical functions. The optical properties of dot pattern and micro prism or other optical objects were used to determine the luminous flux ratio and then the difference luminance between main panel and sub panel was estimated. This estimation strategy provides a fast initial design and the solution to predict the luminance of single panel and dual panel of light guide.
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