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> Replacing the fluorescent blue with phosphorescent blue will mean a more balanced pixel structure and could enable higher-resolution displays in the future. I
by tromp 3y ago
> Replacing the fluorescent blue with phosphorescent blue will mean a more balanced pixel structure and could enable higher-resolution displays in the future. In the near term, the switch will lead to an approximate 25 percent gain in efficiency
I would have expected a 50% gain. According to the quoted efficiencies, the blue fluorescent subpixel needs 4x more power (at 25% efficency) than the phosphorescent red and green subpixels (at near 100% efficiency).
So making the blue phosphorescent as well should reduce 1+1+4 to 1+1+1 power, a 50% reduction (technically a 100% gain in efficiency). Why is the near term gain only 25% ?
- deleted 3y ago[deleted]
- manwe150 3y agoI don’t know the answer, but I think there is usually 2 green subpixels, so 1+1+1+4 to 1+1+1+1 for that facet
- anderskaseorg 3y agoYou’re thinking of the Bayer pattern for sensors, which have four equal RGGB squares. When an RGGB pattern is used for displays, the more numerous green subpixels need to be smaller to maintain the correct white balance, resulting in the same 1+1+4 power profile.
- kurthr 3y agoYes, for cameras it is called Bayer. For displays Samsung coined Pentile. It is by far the most common array of mobile OLED subpixel designs (RGGB), used in mobile devices (eg iPhone, Galaxy, Pixel, Huawei, Oppo, Xiaomi).
- ska 3y agoGP's point was that it's not the number of pixels, but the power draw that matters here (for power consumption) and while there are more greens they are smaller and draw less. This design pattern happens because humans are more sensitive to greens, but that doesn't mean you need more green output.
- kurthr 3y agoExactly, for a white balanced screen you need the same number of photons whether they are at a higher resolution (like Pentile) or not. Adding a White (or Yellow or Cyan) subpixel for RGBW can improve efficiency for the less saturated part of the color gamut, but obviously not the pure red green or blue colors.
- rowanG077 3y agoIf I understand correctly you don't want the same number of photons. You need more blue photons.
- kurthr 3y agoI'm saying photons here, because there are so many words that have very specific meanings that are not typically understood (Nits, Candela, Lumens, Luminance, Brightness, Illuminance, Luminous Flux (Lux), and Luminous intensity) by the lay person. However, just looking at the 5500K black body the power density of any Blue is well below that of any Green or Red, and since the energy per photon is higher at shorter wavelengths (blue) that means the photon flux is significantly lower (about half the number of photons/sec/m2 of green). http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/coltemp.html http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/coltemp.ht... Just for the plot. The reason that Cyan (between Blue&Green) and Yellow (between Red&Green) subpixels added to the full pixel can be more efficient for white (or unsaturated colors) is that they are detected better by the eye (perceived brightness) for an amount of power or photons than a primary Blue or Red.
- kurthr 3y agoMy professional experience is that blue sub-pixels for a 5500K balanced white use about 50% of total power (rather than the 66% you show). My understanding is that this is because even though Blue 460nm is shorter wavelength (higher photon energy) than RG(530&610nm) it is also less significantly less bright (in photons/sec/solid angle). I've struggled to find a good webpage, but roughly in subpixel power% it comes to 45%+35%+4x(20%)=160%. By improving blue efficiency it could become 45%+35%+20%=100% and require only ~2/3 of the original power and total display power efficiency by ~50% (ignoring all the computation, RC losses, coms, etc). White balanced power is independent of the number of pixels (or pixel arrangement) such as RGB vs RGGB, but RGBW or RGBY or RGBC can improve efficiency (and reduce this relative improvement %).