May 31, 2009 NEC Electronics America is set to show an important new white LED-based LCD module this week at the Society for Information Display (SID) Display Week 2009 in San Antonio, Texas. The amorphous-silicon color thin-film-transistor (TFT) liquid crystal display (LCD) module achieves an ultra-wide color gamut for 100 percent of the Adobe RGB color range by incorporating a newly developed LED light-source unit into the backlight system and a newly developed color filter.
The white LED that serves as the light source for the backlight unit in this LCD module achieves its white light by mixing light generated through the irradiation of red, green, and blue (RGB) phosphors with light from a near-ultraviolet LED chip (excitation), making it superior to traditional white LEDs in terms of color-rendering properties. Combining these newly developed white LEDs with newly developed color filters optimized for this application makes it possible to reproduce a wider range of colors covering 100 percent of the Adobe RGB color range, which is generally beyond the reach of conventional standard white LEDs.
In recent years, there has been an increase in demand for LCD displays using white LEDs as light sources in backlight units due to the many benefits achieved with LED backlight systems versus cold-cathode-fluorescent-(CCFLs)-based backlights. Such benefits include smaller module dimensions, lighter-weight designs, and reduced power consumption. The LEDs are also mercury free and do not require the use of high-voltage circuitry, allaying concerns related to safety and the generation of harmonic currents and high-frequency noise. The LEDs offer superior vibration and shock resistance as well as superior characteristics with respect to low-temperature startup and a wider dimming range.
The white LEDs currently in widespread use typically have weaker output in their red and green wavelength components than CCFLs, since they create white light by exciting the yellow phosphors that cover the blue LED chips. For this reason, when used as backlight light sources, traditional white LEDs, even when combined with color filters having a wide color gamut, impose limits on the expansion of the red and green color reproduction range, making it difficult to cover the Adobe RGB color range.
Developed by NEC LCD Technologies in Japan, the module will be marketed in the Americas by NEC Electronics America.