LED unilateral side into the network design of light guide plate

1 introduction

LED light guide plate type surface light source are widely used in the flat display, household lighting, advertising, decoration, and many other fields, in the side into the light module technology, as the media of the light source of light guide plate, the network configuration, shape and material composition determines the surface illumination and uniformity of the guide plate and the light efficiency. Design and manufacture of light guide plate is a backlight module and one of the key technology of large area lighting. Commonly used edge-lit backlight module is to use the light guide will be made by the light of the light source from side of light guide plate input into uniform output from the front surface light. According to the different shapes of light guide plate can be divided into flat and wedge-shaped plate, the bottom scattering network design method can be divided into different printing type and the printing type. Experiments show that dot the shape of the light scattering effect is not big, and network configuration rule is largely affects the uniformity of the output light and brightness. Backlight system is the main light source cold cathode fluorescent lamp ( CCFL) And the light emitting diode ( 领导) Such as [ 1] 。 LED compared with the traditional light source, it has high efficiency, small volume, long service life, the use of flexible, no mercury pollution, dimming performance is good, no stroboscopic, low heat radiation of many advantages. Unilateral side into the guide plate can reduce the design cost and production cost, in order to obtain the surface of the uniform illumination [ 2] , this paper introduces a kind of to the side of the LED lamp as light source the light plate type, the design method of the node configuration rule of light guide plate and by using TracePro software simulation analysis, intensity of illumination distribution uniformity in meeting the requirements of the business results.

unilateral side into the guide plate in only one side put LED lamp bead, due to the LED lamp bead are discrete, was laid so desirable one star LED, establish corresponding point source model, as shown in figure 1.

where N to the number of total in the side of light guide plate LED.

lambert body type is an ideal light LED [ 3] For the round, light distribution curve. To substantiate the LED light is a sphere, the volume of a sphere can be expressed as the LED total luminous flux, luminous flux set unit volume is 1, as shown in figure 2, figure on both sides of the fan in the plane into the volume of the sphere cut to the luminous flux is LED out of the fan-shaped small Angle shot.

3 results and analysis in the design, the article 3528 LED lamp, luminous flux of each lamp is 6 lumens, 36 star LED lamp is uniformly distributed in the side of the guide plate. Select guide plate size of 0. 6m × 0. 6 m, the emergence of surface illumination of light guide plate is set to B = 420 lx. Formula ( 10) The k of undetermined coefficients, by changing k value, the software simulation to get the illuminance distribution ( As shown in figure 5) K value, intensity of illumination distribution evenly. Unilateral side into the grid point of light guide plate of fill rates three dimensional diagram is shown in figure 3. Can see from the table, the grid point fill rates at the side of the LED light source value is low, the LED light source opposite side value is higher, and in both sides of the LED light source the highest value, and increased with the increase of x coordinate increased significantly, in the x and y coordinates a maximum filling rate and maximum.

site map of guide plate as shown in figure 4.

surface illumination simulation using Tracepro software [ 5] , first of all, in Tracepro site map of a channel plate, when modeling, attribute set of light guide plate for plastic categories of PMMA, and in addition to the smooth surface and a smooth surface, light guide plate of the surface of the other property is set to the mirror. Above the smooth surface of light guide plate to set up a viewing screen, set to PerfectAbsorber observation under the screen surface. Establish a reflective screen at the bottom of the guide plate, reflect on screen surface is set to the mirror, reflecting light transmission under the surface of light guide plate. In the corresponding position of the insertion into the smooth place of light guide plate 36 leds simplified model.

take k = 70, elected to get uniform illumination output distribution and horizontal and vertical illuminance distribution graph, as shown in figure 5.

9 measurement method is used to measure [uniformity of light guide plate 6] , the guide plate from top to bottom, from left to right into 9 portions, on average every part of the diagonal intersection point of illuminance measured. Illumination analysis available options in the profile curve of illumination analysis and measured the intensity of illumination of each point. Nine point illuminance value 425 lx, respectively 420 lx, 420 lx, 435 lx, 419 lx, 420 lx, 440 lx, 400 lx, 448 lx, average for 425. 2lx。 Intensity of illumination evenness refers to the regulation on the surface of minimum intensity of illumination and the ratio of the average illuminance. So can get uniformity for 94. 1%.

according to the distribution of points of light guide plate is shown in figure 4, adopt PMMA ( Acrylic) Light guide plate production, making use of the illumination meter measuring the intensity of illumination evenness were better than 90% in real terms, accord with the requirement of commercial uniformity of light guide plate is more than 80%.

4 conclusions in this paper, the LED unilateral side into the theory of light guide plate model, deduced the grid point fill rate function, using Tracepro optical software simulation, on the basis of experiments and produced a 0. 6m ×0. 6m PMMA ( Acrylic) Guide plate. Simulation and experimental results show that the elected take k = 70, emergent must guide plate surface illumination uniformity for 94. 1%, the measured intensity of illumination evenness were better than 90% in real terms, proved that the described in this article the LED unilateral side into the correctness of the model and design method of light guide plate.

edit: Steve