NEC LCD2180WG User Manual
NEC LCD2180WG-LED
NEC Display Solutions
Technical Background and Feature Overview
Unparalleled display performance for your
COLOR-CRITICAL
applications.
Designed from the ground up with more than 3
years of research and development, and featuring many ground-breaking technologies never
before available on a consumer display, the 21.3”
LCD2180WG-LED represents NEC’s flagship color
reference display. This display is aimed directly
at the professional color market where screen
brightness, color gamut, uniformity, stability and
repeatability are of the utmost importance.
The LCD2180WG-LED is the first commercial
display to feature individual high power red,
green and blue LEDs (Light Emitting Diodes) as a
backlight source for the LCD, instead of the typical CCFL (Cold Cathode Fluorescent Lamp). This
significant change, made possible by the recent
advances in LED light output and efficiency, pro-
vides remarkable increases to the output color
gamut, as well as to the fidelity to which screen
colors can be adjusted.
This increase in displayable color gamut opens up
an entirely new era of color workflow in which the
display screen can be trusted to accurately represent the colors that were captured, edited and
will be output, be it on print, film or other media.
Recent advances in digital image capturing
devices, such as digital cameras, are now capable
of offering expanded color gamuts, such as
AdobeRGB, as a standard color space. At the
same time, ink jet printers are now capable of
reproducing colors from very large color gamuts.
As this technology gets better and becomes more
The need for enhanced color gamut displays
These images were captured on a standard digital camera in AdobeRGB
colorspace. The gray areas in the photographs show the out of gamut
colors when the images are viewed on a typical sRGB display monitor. It
is impossible to display these colors on such a monitor.
accessible, the need for accuracy in viewing and
soft-proofing color is increasing as well.
Whereas traditional displays were typically limited
to a color gamut of sRGB, the color gamut of
the LCD2180WG-LED exceeds that of even the
AdobeRGB colorspace. This means that the display
is no longer the limiting factor for color gamut
within a typical color workflow. The color workflow can be simplified by reducing or even eliminating the need to make color output proofs, as
is typically needed with a traditional display in
order to accurately check colors that are outside
the display’s color gamut. This represents a significant benefit in time and cost savings.
2
Color Gamut of a Display
Light Wavelength (nm)
400
700
500
600
Relative Intensity
Light Wavelength (nm)
400
700
500
600
Relative Intensit
y
Color displays are additive color devices. Color
is formed by adding different proportions of
red, green and blue light. These primary colors
are formed by the glow of different types of
phosphors in the case of a CRT display, or by
filtering white light into red, green and blue
on an LCD.
Red + Green = Yellow
Green + Blue = Cyan
Blue + Red = Magenta
Red + Green + Blue = White
The color gamut of a display is limited by how
pure in color the red, green and blue primaries
are.
When viewed on a CIE xy color chart (a 2
dimensional plot of all colors visible to the human eye), the red, green, and blue primary colors together form a triangle. Colors outside
of this triangle are outside of the displayable
color gamut.
The size and position of the triangle are determined by the purity of the primary colors.
The purer the color, the closer it is to the edge
of the CIE horseshoe. Colors along the edge of
the horseshoe are made up of pure monochromatic light.
The largest possible color gamut using 3 colors
would be obtained by using 3 monochromatic
light sources such as LASERs.
When a light source is viewed as a spectrum, it
is possible to see the relationship between it’s
spectrum and position on the CIE color chart.
Relative Intensity
400
500
Light Wavelength (nm)
600
700
Monochromatic Light lies along the
edge of the CIE horseshoe
Relative Intensity
400
500
Light Wavelength (nm)
600
700
Light made up of a broader spectrum
lies inside the CIE horseshoe.
LCD Operation and Color Gamut
With an LCD display, the color gamut is determined by a combination of the light source
used to illuminate the LCD panel (known as the
backlight) and of the LCD panel itself.
Typical LCD monitors use a broad-band light
source such as CCFLs, which radiate a wide
spectrum of colors, including unwanted colors
such as oranges, yellows, cyans. Only the pure red,
green and blue parts of the backlight spectrum
are wanted in order to maximize the color gamut
of the display.
The LCD2180WG-LED avoids the need for narrower
spectrum color filters by fundamentally changing
the spectrum of the backlight source. By using
red, green and blue power LEDs, which output
a very narrow spectrum of light, a huge gain in
displayable color gamut can be achieved without
the need for using narrower color filters on each
sub-pixel.
It is important to understand that the backlight
for the LED based display is still “white” light,
but it is made up of very narrow-band red, green
and blue light, which when combined together, is
LCD Screen Sub-Pixel Structure
Each pixel on the screen is made up of red, green
Typical CCFL Backlight Spectrum
and blue sub-pixels. The colors of these sub-pixels are made by passing the backlight through
a color filter array. The characteristics of these
color filters in part determine the gamut of the
display.
Backlight
TFT Array
Liquid Crystal
Color Filter Array
In order to achieve a larger color gamut, it would
be necessary to filter the backlight into a narrower spectrum of colors thus producing purer
red, green and blue. However, filtering into a narrower spectrum is a technological challenge and
doing so also reduces the total amount of light
that is transmitted through the filter. This means
that the overall screen luminance is reduced or
must be compensated for by using more CCFL
perceived by the human eye as white light. If this
light were to be shown as a rainbow spectrum using a prism, only the red, green and blue portions
of the rainbow would be seen.
Combined LED Backlight Spectrum
backlights.
LCD Color Filter Array
3
Loading...