(A) novel adaptive dimming LED backlight system with X-Y channel drivers for LCD TVs

Abstract

Electronic display devices play an important role as an information display for a man-to-machine interface. With the rapid progress in the information industry, there has been a continuous increase in the demand for new electronic display devices with a large size, high resolution, and high information capacity. Among many hitherto developed display devices, a thin film transistor liquid crystal display (TFT-LCD) has become one of the most popular display devices in small and middle sized applications such as PDA, notebook and monitor, since a TFT-LCD has many advantages such as high resolution, low power consumption, light weight, slim size and so on. Recently, with the large sized TFT-LCD panel over 100 inches being developed, a TFT-LCD is expected to be one of the most promising digital displays of the next generation. When looking into an LCD used in monitor or TV applications, a backlight unit (BLU) is usually required. The BLU supplys light to the LCD panel and consumes the most power. The backlight lamp and inverter takes great part of production cost. Therefore, the backlight unit is a very important part of an LCD. Recently, as the screen size of the TFT-LCD increases the BLU becomes more important. Multiple fluorescent lamps such as cold cathode fluorescent lamp (CCFL), external electrode fluorescent lamp (EEFL) and flat fluorescent lamp (FFL) have generally been used as a LCD backlight source. However, the RoHS Directive’s limited permission of mercury (Hg) use forces a new LCD employed with an environmentally friendly backlight system. Therefore, the most promising substitutive device is now the light emitting diode (LED). Although, high cost and low light efficiency of LED make it difficult to be widely adopted as a backlight source, LED satisfies the RoHS Directive and has many other merits such as long lifetime, wide color gamut, fast response, etc. compared to fluorescent lamps. Moreover, light efficiency of LED has been continuously improved...