We propose a new and effective Light Guide Plate, called Empty Chamber Fresnel Lens Light Guide Plate (ECFL-LGP), to provide the merits of thin, lightweight, low-cost and high effect of light rays guiding for a medium or large LED-sourced Edge Lighting Backlight Module. It consists of a simple Empty Chamber and two sets of linear irregular Fresnel lenses. Due to the reasons that the structure of the Empty Chamber is simple and a Fresnel lens is thin and cheap, our ECFL-LGP will possess lower cost than the traditional hard LGP. On the other side, the irregular Fresnel lens in ECFL-LGP will be better than the traditional mesh-like dot about the effect of light rays guiding because its irregular linear groove angles can be evolved in terms of the optimization requirements of light rays guiding. As for the uniform problem of light rays guided to the LCD panel, we will design a double-deck linear irregular Fresnel lenses to act as a prismatic film according to the uniformity requirement. To overcome some problem caused by designing linear irregular Fresnel lenses, we propose an idea of dividing the designed Backlight Module into several sections to reduce the number of evolved groove angles, and dividing the design procedure into two stages: first, evolve two sets of linear irregular Fresnel lenses in the designed ECFL-LGP, then evolve four sets of linear irregular Fresnel lenses between the ECFL-LGP and the LCD panel. As a result, the thickness of the designed LED-sourced Edge Lighting Backlight Module will be 4.85 mm only (the LCD panel is not included).
We propose a Linear Irregular Fresnel Lens (denoted as LIFL) to replace the diffusion sheet and prism sheet in a
rectangular LED-based Direct-type Backlight Module. The aim is to improve the illuminance and uniformity of LCD
panel, as well as to reduce the cost of Backlight Module and make the Module thin. Here "Linear" means the grooves of
a Fresnel lens are arranged linearly and "irregular" means that the sequence of all groove angles is not increasing or
decreasing. To let the designed LIFL possess good effects of light ray guiding, two layers of LIFLs are needed. The first
layer LIFL consists of x-axis grooves, whereas the second layer LIFL consists of y-axis grooves to guide all light rays
guided by the first layer LIFL. The groove angles of the designed LIFL are evolved by a Genetic Algorithm which is
developed in terms of the performance requirement on illuminance and uniformity of LCD panel in a rectangular
LED-based Direct-type Backlight Module. In this paper, we will simulate a simple fifteen-LED Direct-type Backlight
Module to demonstrate the performances on illuminance and uniformity of the designed LIFL.
To design the layout of LED light sources(called as LEDs) in a medium or large LED-based lighting
system to optimize the system's performance in illuminance, uniformity and heat dissipation by
developing a Genetic Algorithm, the searching space formed by x,y, z coordinates and rotation angles of
an LED light source will be rather huge as to paralyze the evolution program. Hence, we propose the idea
of representative LED sources (called as representatives), which are parts of LEDs. In this paper, we will
develop some a Genetic Algorithm to search for suitable representatives to make the evolutional design of
a programmable Fresnel lens for the mentioned lighting system feasible. Based on the designed
programmable Fresnel lens, develop another Genetic Algorithm to arrange the layout of LEDs, including
locations and orientations of LEDs, to let the lighting system's performance be further enhanced.
A typical Fresnel lens is not suitable to a reading light system with multiple light sources since it is designed in such a way that each groove is at a slightly different angle from the next but with the same focal length. Therefore, a Fresnel lens with suitably designed groove angles is needed for this kind of light system. In this paper, a more efficient three-layered Hierarchical Genetic Algorithm (3LHGA) is proposed to find an optimal set of groove angles for a designed Fresnel lens to optimize both the illuminace and uniformity for a reading light system with multiple light sources. The groove angles of a designed Fresnel lens are directly derived from a Fresnel lens database by two layers of control genes in the proposed 3LHGA. The proposed 3LHGA not only makes it possible to evolve a lot of groove angles as parametric genes but also further improve the performance of a Fresnel lens and increase the speed of evolution. From the simulation results we can demonstrate that the designed Fresnel lens indeed offers improvement of light-guiding performance for a multiple-LED reading light system.
The main function of a Fresnel lens is to provide light guidance. Since the current LED sources cannot provide enough flux for reading lamps to be designed with a single LED, instead systems must use multiple LEDs. We present an optimal design of a Fresnel lens for a reading light system with multiple light sources of white light LEDs. The groove angles of the Fresnel lens are chosen as design parameters and the design goal is to maximize the illuminance in a specified reading surface while maintaining the distribution uniformity of the light rays. We develop a series of genetic algorithms that are implemented with SCHEME language and macros supported by the commercially available nonimaging optical simulation tool to search for a set of optimal groove angles for the Fresnel lens. From the simulation results we can see that the optimally designed Fresnel lens indeed offers better light-guiding performance than typical Fresnel lenses for a multiple-LED reading light system.
The main function of a Fresnel lens is to provide light guidance. In this paper, we present an optimal design of Fresnel lens for a reading light system with multiple light sources of white light LEDs. The groove angles of Fresnel lens are chosen as design parameters and the design goal is to maximize the illuminace in a specified read surface while maintaining the distribution uniformity of the light rays. We develop a series of genetic algorithms which are implemented with SCHEME language and macros supported by TRACEPRO package to search for a set of optimal groove angles for Fresnel lens. Simulation results show that the optimally designed Fresnel lens indeed offers better light-guiding performance than typical Fresnel lens for a multiple-LED reading light system.
This paper presents the design of a reading light system consisted of multiple R, G, and B white light LEDs with Fresnel lens located before the light source. First, we use a general Fresnel lens and a Genetic Algorithm (phaseΙ) to search the best arrangement of multiple LEDs, then use another Genetic Algorithm (phaseΠ) to the result obtained before to get a better Fresnel lens of width-varied grooves. Experimental results show that the special arrangement of LEDs and the special structure of Fresnel lens make the reading light system more efficient in illuminance than the reading light system of no Fresnel lens.
A new method, using genetic algorithms, for constructing a tri-state neural network is presented. The global searching features of the genetic algorithms are adopted to help us easily find the interconnection weight matrix of a bipolar neural network. The construction method is based on the biological nervous systems, which evolve the parameters encoded in genes. Taking the advantages of conventional (binary) genetic algorithms, a two-level chromosome structure is proposed for training the tri-state neural network. A Matlab program is developed for simulating the network performances. The results show that the proposed genetic algorithms method not only has the features of accurate of constructing the interconnection weight matrix, but also has better network performance.
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