An Engineer in Wonderland – LCDs get ‘greener’
I have been agonising over buying a new computer monitor for ages.
There is a bewildering array available and the questions that need answering include:
- 22″ 1280×1024 or 24″ 1680×1050?
- Twisted nematic, in-plane switched, or some other technology?
- A brand or a cheapie?
- HD-ready just in case I ever watch DVDs?
So many questions, and so little decisiveness.
But I may have a way to cut the choice down – Alice’s Razor is to be energy consumption.
LCD monitors are already significantly less wasteful of power than CRT types and 22″ types are supposed to waste disproportionately less than those 2″ bigger.
It is claimed to use only half the operating power compared with others of the same size, and reviews seem to agree – getting its power somewhere between 18 and 22W compared with 40W plus for competitors.
This is quite an achievement as the only obvious specification limitation is a reduction in maximum brightness from 300 to 250cd/m2.
I have no idea how it is done, but there is some clever engineering somewhere.
As most power is eaten by the backlight, I am thinking that some better way to get light from CCFL tube to the screen has been employed.
Reports do not talk of washed out colours, which suggests its RGB filters have not been compromised.
If someone knows how it is done, do tell.
Standby power, according to this report is a creditable 300mW.
So the question is now: Get one of these, or stick with my old 17″ LCD?
Thinking about the last point – stand-by power – reminded me of an article in Electronics Weekly about a zero stand-by power monitor.
By coincidence, a range based on the Fujitsu Siemens technology covered has just hit the shelves.
There are quite a few ways to cut stand-by power to a few mW.
Some fine examples were submitted to Electronics Weekly’s own February 2007 ZigBee power supply competition – where the winner and runner up consumed 1mW and 2mW stand-by respectively.
At this point, purveyors of 7W-stand-by set-top boxes and their like should view this and hang their heads with shame.
Fujitsu’s undisclosed ‘switching element’ in the power supply is controlled by the PC connection and apparently cuts monitor consumption to zero when the PC is shut down.
I am thinking a photo-triac, or back to back mosfets controlled by an opto-isolator – there are many ways of doing it.
Two monitors have appeared: the 20″ P20W-5 ECO and 22″ P22W-5 ECO; with 24 and 26″ models following in September.
Unless the Fujitsu monitor also has low operating dissipation, it will not make my shortlist as within the walls of Chateau Alice everything gets turned off at the mains when it is not needed.
And prices start at €419 for the smallest one, which is a bit steep unless the display is not a simple twisted nematic type.
The good thing is, huge power savings are available for those motivated enough to look for them, and skilled enough to find them.
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