1 Introduction
With the rise of global environmental awareness, energy saving has become a trend of development today [1]. In recent years, the market share of liquid crystal display products using LED backlights has gradually increased. Compared with traditional fluorescent tubes, LED products have the advantages of energy saving, high efficiency, fast response, long life, strong environmental adaptability and good impact resistance [2]. In 2004, SONY launched the world's first 116.9cm (46in) LCD TV with LED as the backlight. Subsequently, AUO, Samsung, LG, Phillips and other companies also launched their own LED-backed large Size LCD TVs, LED backlights have since become a hot spot for research and development.
The LED photoelectric conversion rate is low, and a large amount of electric energy is converted into heat energy during operation. If the generated heat cannot be exported, the junction temperature of the LED will be too high, which will affect the life cycle, luminous efficiency and stability of the LED. At the same time, too high temperature will change the electro-optical performance of the LCD screen, affecting the whole product. use. Therefore, how to improve the heat dissipation capability is one of the key technologies to be solved by LED backlight [3-4]. LED backlights are available in both direct and side-lit configurations. The direct-type backlight has a simple process and does not require a light guide plate. The LED array is placed at the bottom of the light box, and the light emitted from the LED is reflected by the bottom surface and the side surface, and then uniformly emitted through the diffusion plate and the optical module on the surface. The edge-lit LED backlight uses fewer LEDs. It sets the point source on the side of the specially designed light guide and then evenly emits the light through the optical module. Large-size LCDs require the use of larger power LEDs, and the issue of heat dissipation becomes even more important. Because of the heat dissipation problem involving a series of problems such as light, electricity and color, it is necessary to perform thermal analysis on the LED backlight [5-6].
In the heat dissipation of LEDs, especially the heat dissipation of high-power LEDs, there have been many studies at home and abroad [7-8]; however, these studies mainly focus on the LED light strip itself, and the heat dissipation performance of the LED itself is improved by adopting new materials and new technologies. [9-10], thereby improving the light-effect conversion of LEDs [11], while the research on the backlight as a whole is rare. In this paper, the general finite element software ANSYS is used to establish a LED backlight model for 119.4cm (47in) edge-lit LED backlight. The temperature field distribution of the backlight is analyzed in several cases and compared with the actual measurement results. . The error between the calculated result and the measured temperature is only 1.65%, which proves that the analytical method proposed in this paper is feasible.