1. Field of the Invention
The present invention relates to a liquid crystal display (“LCD”) device, and more particularly, to a backlight unit for an LCD device which uses a light emitting diode (“LED”) as a light source.
2. Description of the Related Art
LCD devices are a type of display device which forms an image by receiving external light instead of using self-emitted light to form the image, as is the case in plasma display panels (“PDPs”) and field emission displays (“FEDs”), for example. Thus, the LCD device requires a backlight unit for emitting light at a back surface of the LCD device.
A conventional backlight unit for an LCD device typically uses a cold cathode fluorescent lamp (“CCFL”) as a light source. However, when the CCFL is used as a light source, it is difficult to secure uniformity of brightness of light supplied from the CCFL. In addition, color purity deteriorates as a screen size of the LCD device increases. As a result, a backlight unit which uses three color LEDs as a light source has been developed recently. Since the backlight unit using the three color LEDs as the light source produces an improved color purity, as compared to the backlight unit using the CCFL, and the backlight unit which uses the three color LEDs is therefore used in a high quality display device, for example.
However, the backlight unit which uses the three color LEDs as the light source is more costly as compared to the backlight unit which uses the CCFL as the light source. To mitigate this problem, a white LED which emits light by changing a light output from a single color LED chip to a white light has been proposed. However, although using the white LED is not as expensive as using the three color LEDs, a color purity and a color reproducibility is reduced, as compared to a color purity and color reproducibility of an LCD device including the three color LEDs. Accordingly, various attempts for developing a light source which has improved color purity and color reproducibility while maintaining price competitiveness in comparison with other light sources, have been made.
USPTO Backgrounds
USPTO Backgrounds