Following some on-line research, I found out that:
- Some TVs use AMOLED technology (active-matrix organic light-emitting diode), where the sub-pixels actually emit light.
- Our displays are highly likely to use LCD sub-pixels which do not emit light, so need some form of backlighting.
Backlighting is generally of four types (
http://www.en-touch.com/comparing-the-different-types-of-lcd-backlights/):
- Cold Cathode Fluorescent Lamps (CCFL)
- Edge-lit LED (EL-WLED)
- WLED –with WLED, the rear panel of the LCD display is lit with a vast array of white-colored LEDs, all of which are placed behind a diffuser. one of the benefits of WLED is its ability to dim the brightness of the LED in certain areas. Much like EL-WLED, this boosts the contrast ratio of the display. WLED backlights are commonly use in big-screen LCD TVs and select computer monitors.
- RGB LED — a fourth type of backlight display use in LCDs is RGB LED. This technology is similar to WLED but with one major defining characteristic: it uses an array of red-green-blue (RGB) LEDs instead white LEDs. This results in higher color gamuts and better overall picture quality than its counterpart.
There is another type: GBr-LED, which uses green and blue LEDs with a red phosphor to provide whiter light.
There is also a relatively recent technology called quantum dot, but I won't go into this.
This site provides good analysis of the benefits of WLED vs RGB:
https://pcmonitors.info/articles/the-evolution-of-led-backlights/From this I conclude that:
- W-LED are not actually white, but strongly blue and use a yellow phosphor to broaden the spectrum. However, they still have a strong peak in blue and a shoulder in yellow, green and red. The blue must be flitered out. This technology is typically used in sRGB screens
- RGB-LED have three peaks, but are presumably easier to filter out to produce a more easily controlled white light. This technology is used in wide-gamut displays
- GBr-LED seems to fall in between.
EL-LED displays have the advantage of being thinner.
RGB-LEDs are much thicker and typically (much) more expensive.
It also seems that the quality of the display will depend on the quality of the LEDs, the filters and the TFT LCD matrix.
However, it seems that RGB-LED will produce a wider gamut than W-LEDs, and that GBr-LED is also better than W-LED (everything being equal).
It is not clear to me why the PA-243 has gone to W-LED from the 242's GBr-LED. I speculate that this is driven by a desire to reduce the thickness of the display and possibly to reduce costs.
As it appears to me that the PA-243 has moved backwards, I will purchase a PA-242.
PS: I'm a dumb biologist, not an electronics engineer and probably have lots wrong in here!