Travis said:
I need some advice. I'm looking for a 20" or larger widescreen LCD. I
do not need speakers built-in. I would like to have a DVI connection on
it at minimum. I'm looking for a rather high-quality monitor that will
last me for no less than 4 years. It might be my luck, but I've had two
Acer AL2016W widescreen monitors, and they both failed with an
inverter/backlight problem. My first one failed in two weeks and my
replacement one failed in two months. Thanks for any advice.
I found this article, by searching for LED based backlights. This article
is actually about professional monitors, and the NEC one here appears
to use the traditional CCFL/inverter backlight method. They compare it
to a Samsung LED illuminated one. The Samsung fares worse, because of
their implementation details, but the technology is promising.
I believe NEC also makes raw panels with LED illumination, but I don't
know if they use them yet in the monitors they make or not.
http://www.xbitlabs.com/articles/other/print/professional-monitors.html
(Another nice article here...)
http://www.xbitlabs.com/articles/other/display/lcd-parameters.html
http://www.samsung.com/ca/products/monitor/lcd_highresolution/ls20edbebxaa.asp?page=Specifications
The LED modules are shown in pictures here.
http://web.archive.org/web/20070225...Products/Monitor/LCD_Digital/LS20EDBEBXAA.asp
If that archived page won't render properly, just the picture of the LED modules is here.
A red, green, and blue LED are present in the module and adjusted to give white light.
Many modules are used to get enough contrast.
http://monitor.syncsight.com/upload/Code_Management/SF/CCFL vs LED/img_CCFL vs LED_02.jpg
Based on the specs of the monitors, the NEC using 50W and the Samsung using
85W, it looks like LEDs use more power. Working against the LED design, is
the sheer number of modules involved. The LEDs need to be individually
controlled and calibrated, which means the LED would likely have a monitor
photodiode, to monitor the level of light output. LED output drops to 50%
of original intensity, over a period of a couple years, so closed loop
feedback via monitoring each LED, helps keep the intensity uniform. (It
means when the monitor is new, the LEDs might be fed 30% of full power, and
near end of life might receive 60% of full power, leaving a bit of room to
account for differences between LED module units.) To do that, the LEDs
would be pulsed at a rate above human eyesight, and the on-time of the pulse
is controlled to give the desired intensity. By doing it that way with a LED,
you can vary the intensity, but keep a constant color output.
So, that means there is a bit of complexity in each LED module. The
advantage of the LEDs, is they are solid state and reliable as any other
integrated circuit. It means no need for high voltage, like in the CCFL
lamps. But there are quite a few of them, and only one has
to go bad, to give a dimmed patch on the screen.
I hope to seem more monitors designed that way, but only time will tell
whether LED backlighting will trickle down into the economy market. The
price of the LED modules would drop, as the quantity made went up, and
with the price of the above monitor, they aren't going to sell very many.
(Especially when so much of the advertising copy, is not noting the use
of the superior backlight technology.)
Samsung XL20 $1500+
http://computers.pricegrabber.com/flat-panel-lcd-monitors/m/32832527/
In looking at the Newegg reviews for monitors, I notice quite a few
entries where the reviewer has nothing critical to say about the product.
Which makes me wonder why they'd even bother to write one. The monitor
is the most critical part of the computer, in terms of everyday experience,
eyestrain and general enjoyment. I would expect every "real" reviewer, to
have something to say about the monitor he/she bought, no matter what
price was paid for it.
Good luck in your search. Reliability is a hard thing to measure,
especially when models don't stick around long enough for all their
faults to become apparent.
Paul
