All of the LED back-lit displays I have purchased have arrived with the back-light set too high, and the colors out of whack. I have a colorvision spyder that I run on them, which sets them up right.
Once setup, I much prefer them to the CCFL back-lit displays.
the LED backlit displays ive seen (and have) take for fking ever to turn on. really a PITA. im talking like 15-25 seconds before the screens are fully on and displaying a signal. other than that i have no comment. for a computer screen i dont think the difference would be very noticeable for general computing
Yeah I bought a Benq LED and the picture was horrible and the montior was hard on my eyes. It was like the brightness was different all over the screen. I wanted a 300 brightness so it would be the same as my older ACER AL1913 but it seemed way brighter. I didn't think 300 for one would be brighter than 300 for another. I couldn't be sure why exactly my eyes didn't like the benQ but I ended up taking it back.
the LED backlit displays ive seen (and have) take for fking ever to turn on. really a PITA. im talking like 15-25 seconds before the screens are fully on and displaying a signal
When I was in high school in the mid-1960s, the vast majority of TVs took a minute or longer for the tubes to "warm up" before you got a picture. Color sets could take as long as 5 minutes before the picture was completely clear. It was a huge deal when "solid state" sets arrived giving "instant-on" picture and sound.
the LED backlit displays ive seen (and have) take for fking ever to turn on. really a PITA. im talking like 15-25 seconds before the screens are fully on and displaying a signal
When I was in high school in the mid-1960s, the vast majority of TVs took a minute or longer for the tubes to "warm up" before you got a picture. Color sets could take as long as 5 minutes before the picture was completely clear. It was a huge deal when "solid state" sets arrived giving "instant-on" picture and sound.
I still don't get instant on. My LCD TV takes like 10 seconds to show a picture.
That's the electronics syncing up, not anything to do with the LEDs though I wouldn't be surprised if there was something to do with the power supply needing to settle.
60 seconds for a LED monitor or TV to turn on is ridiculous. Even my 60-inch plasma TV doesn't take that long (about five).
LED monitors and TVs are better than LCD for even lighting across the screen.
Optically, an LED can produce more distinct wavelengths of light than a tube with a coating (fluorescent) and since it is direct radiation rather than radiation-absorption-re-emission (of a different wavelength), since that is what fluorescence IS, it can be more electrically and physically efficient, cooler, longer lived, and potentially even brighter/better contrast if the LEDs are advanced enough.
CFLs will become passe in 5 years hopefully, for all applications, their time in the sun will be brief. LEDs are more environmentally friendly, IMO, as well.
Optically, an LED can produce more distinct wavelengths of light than a tube with a coating (fluorescent) and since it is direct radiation rather than radiation-absorption-re-emission (of a different wavelength), since that is what fluorescence IS, it can be more electrically and physically efficient, cooler, longer lived, and potentially even brighter/better contrast if the LEDs are advanced enough.
While there were some LED backlit LCD displays built with RGB LEDs, the majority nowadays are edge lit with white LEDs, and the great majority (all?) of those white LEDs are blue LEDs with phosphor that re-emits the absorbed blue at a longer wavelength.
OH! So a phosphor is still used! Are the LEDs themselves coated?
I know with LASERs only specific colors/wavelengths can be made, based upon metastable states of energy levels, that is conducive to making a LASE. I would think that diodes produce specific wavelengths, so maybe they need the phosphor in order to modify the spectrum, or broaden the spectrum?
Indeed, with fluorescence, the shorter wavelength is absorbed and longer is re-emitted. Same thing in some LASERs, such as where Xenon Flashes are used.
At some point I've got to update my edumakashun, thank you very much for correcting me. I would imagine that the color spectrum of the LED with phosphor is still better than with a CFL...
I think most white LEDs are coated, but some has the phosphor embedded in the resin. »en.wikipedia.org/wiki/Li ··· sed_LEDs One thing to note, white LEDs can and do change their color as they age. (this was discussed in a electronics a while ago)
One thing to note, white LEDs can and do change their color as they age. (this was discussed in a electronics a while ago)
They indeed change color. Where I work there are several vision inspection systems and there is one in particular that uses white LEDs for illumination. The LEDs are mounted in a series of bars and each bar contains something like 12 LEDs. When one of those bars needs to be replace you can notice a slight color variation among the new and the older LEDs. They tend to become "warmer" as they age if I am not mistaken.
Another thing with CFL backlit monitors is that, as is true with many fluorescent lights, they start relatively dim and take a couple of minutes to reach full brightness. Different brands of monitors may show this to different degrees and it will also depend on age. Older lights take longer to warm up. CFLs dim with age too. A CFL lit monitor will get dimmer as it age although it takes many years to be noticeable and will probably fail due to another cause first. I had one CFL monitor at home that was 5 years old when it failed but it was not noticeably dimmer. Another one at work was replaced after 7 years and it was fine.