Study on LED backlight dimming technique and high step-up DC/DC converter for LED TV

Abstract

As IT develops every year, new IT products are replacing the conventional ones. Along with it, there are over three to five hundred million IT trash being dumped. Hidden toxin from the tech trash causes severe environmental pollution and this has become an arising matter. European developed countries have published a RoHS directive forbidding the usage of noxious materials. They will refuse to import the products which do not comply with the platform as a means to suppress the companies which use them. RoHS has brought a great change in the production of electronics. LCT TV, for instance, has been us-ing mercury to enhance the light efficiency for a must-have component, fluorescent lamp type backlight. However, its usage is limited under the directive of RoHS. Thus, LCD companies are granted a grace period and embark upon the development of environmentally-friendly LCD. As a result, fluorescent lamp backlight is being replaced by LED backlight. LED backlight is an eco and a semiconductor device whose life-span is longer than fluorescent type. Since LED backlight is produced through the assembly of spread point light sys-tem, light source will have its freedom when positioning, enabling 0D, 1D, 2D dimming. LCD TV with so many benefits has brought a huge change to this market. LCD TV which used LED backlight is now called LCD TV and has been differentiated. In 2012, LCT TV with fluorescent lamp is taking over 50% of the TV market and within five years it is expected to take over 90% of it. Many LED TV system related research, especially ways to reduce power consumption are being con-ducted. First, power consumption was reduced through backlight dimming method. It is clear that the conven-tional system which does not use backlight dimming lose a great deal of energy. In order to show a dark im-age, backlight is on bright, and with the information from the image, the transmittance of liquid crystal is then adjusted to determine the brightness of the pixels. On t...