Research On LED Backlight System Based On Visual Comfort

With the development of technology, mobile phones, tablet computers, televisions and other types of flat-panel displays have been regarded as essential electronic products in daily life, and people have gradually began to concern about the influence of displays to health. It is a very important aspect for the development of the technology to study the degree of the comfort and health of flat panel displays. Nowadays, LED-backlight LCD display occupy the main position of the flat panel display market, but the effect of LED backlighting system on human health, especially the impact of visual comfort, is necessary for us to study.In the dissertation, it has been built two measurement systems of blue light of LED backlight system and analysed the effect of the blue light on the visual safety based on the visual comfortable degree. Moreover, it has been also built the other optical characteristic analysis system to measure and study the visual comfort of LED backlighting system, and designed an optical module of LED backlighting system. The main research contents of dissertation are as follows:Firstly, it has been analysed that LED backlight system caused the main reason of the visual discomfort, and researched that LED backlighting system caused the visual comfort by the following two ways:retinal blue light hazard and visual fatigue. Moreover, two test systems have been built based on the visual comfort test system of LED backlight system. Using the two systems, the optical properties and the blue retina damage of LED backlight system have been measured.Secondly, it has been studied that LED displays caused the influence of visual fatigue for the different color temperature, brightness and brightness uniformity. The result shows that it is extremely different of visual fatigue caused by different color characteristics of LED displays:when the working time is less than one hour, less brightness uniformity of the display will make significantly blink frequency increased. And with the time prolonged, the higher the display brightness made the increased blink frequency reduced; when the working time more than one hour, it is earlier to cause blink frequency increased for watching the lower color temperature of the disFinally, a free curved lens has been designed for LED light source to achieve uniform circular spot, using Sparrow criterion to arrange the LED light source. Then a LED backlight module has been designed and analyzed.These works provides some methods for the study of visual comfort and some new design ideas of LED backlight system.