Light Spectra for the LCD Tablets    

The Backlights for the LCD Tablets are white LEDs, which are made by using a Blue LED together with a yellow phosphor to transform some of the light for the Red and Green primaries. We thought it would be interesting to compare the light spectra of the LCD Tablets with the OLED display in the Samsung Galaxy S Smartphone.

The spectrum of an LCD display is just the spectrum of its white LED Backlight filtered through the individual Red, Green and Blue sub-pixel filters within the LCD panel. OLEDs are emissive devices so their spectra is just the sum of the individual Red, Green and Blue OLED spectra, modified slightly by the touchscreen layer and anti-reflection absorption layer through which their light must pass.

As expected the OLED RGB spectra are relatively narrow because of their high color saturation. The LCD RGB spectra are a broader filtered broadband spectrum from the White LEDs, which results in less saturated colors. If more saturated colors were desired, then the LCD light output and brightness would simply decrease, which is why this isn't done with mobile displays because brightness and power are precious resources.

Light Spectra for each of the Tablets
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