A display’s output is greatly affected by ambient light reflections. Contrast filters improve the signal to noise ratios of a display by suppressing internal reflections, creating a display that is easier to read.
Contrast filters attenuate the ambient light internal reflections or background luminance by the square of the filters transmittance because the ambient light must pass through the filter twice. Contrast enhancement is thus created by suppressing ambient light reflections more than the display’s output that passes the filter once, yielding a darker background.
Contrast filters can also modify a display’s reflectance curves by eliminating various sections of the emitted spectrum, thus creating a better system and viewing environment compatibility. The filtering process also means that the amount of reflected light from the surface of the display is limited, so that the mechanical components and electronics that lie behind the filter are partly or fully hidden.
Function and Design
In cases where a monochromatic display is sufficiently bright, it is possible to use a dark, grey or smoked broad-band filter. This results in the information from the display appearing clearly on a dark, almost black, background. This can make it easier to read and, at the same time, provide an elegant design function.