>
>- Their claims re colours, colour change with time, light quality and
>similar between CFLs, LEDs and ESL are extremely suspect. You can make poor
>low life poor spectrum CFL and LED products. Or, rally very good ones. ESL
>relies on phosphor luminescence and their claim re better spectrum would
>need to be checked. A modern phosphor LED DOES have a poor two peak spectrum
>due to the mixing of the LED blue with phosphor yellow - but better can be
>achieved. Recent moves to higher power RGB LEDs in commercial use and you
>could easily go to 4 emitters if desired.

The human eye does an auto color balance anyhow. Photographs can be 
misleading.

>- The above makes their claim about the basic technology of LEDs making them
>energy inefficient, and thus hot, so much hot air. A top class white LED
>currently radiates about 1/3 of its energy input as light !!!! and this
>figure will increase/ LEDs do indeed employ large radiators and do have heat
>dissipation challenges, but the spin put on this makes the fact seem
>different than it is.

Glass (or quartz) bulbs have the advantage they can run quite hot to the touch
and thus eliminate wasted power without requiring an expensive and heavy heat
sink, but as yhou say, it's not an efficiency issue per se.

>- They provide a list of CFL and LED 'disadvantages' but mix the two
>together and fail to note that LEDs effectively do not have twp of the 3
>listed. ie LEDs have instant startup and for practical purposes are 100%
>dimmable. (ie it doesn't matter what the LED does to produce the optical
>result - it's what you see that matters. A LED can be dimmed as deeply as
>you wish by PWM ing.) They also imply that LEDs have a massive recycling
>problem and that ESL somehow doesn't. Current compact high energy LEDs have
>substantial radiator structures - but these can have net disposal value and
>do not need to be a recycling overhead. They also imply that LEDs have a
>mercury problem.

Maybe an arsenic problem. ;-)


>- The ESL unit *apparently* uses a high temperature glass envelope to
>radiate unused energy, but one wonders about the energy transformer which
>produces the electrons which drive the electroluminesence.
>- And the cost of what probably involves driver electronics (presumably with
>no mercury content).

Not necessarily much different from a CFL. It really looks like an unfocused,
CRT without a deflection system, IOW pretty much a white Jumbotron(tm)
pixel. They may have a small filament in the base.

>- And one might wonder whether there is an actual electron beam in there
>and, if so, what sort of voltages are involved and whether XRay generation
>may be an issue. (I don't know).

I doubt it's remotely an issue- you need to get up into the tens of kV to
get significant X-rays.

>- The video footage of light bulbs in production was impressive - but the
>prototype light on the bench did not seem to match the production images wrt
>completeness or what you'd expect to see in a demo - I suspect the two may
>have been 'creatively linked'.
>
>And more ... .
>
>So: ESL MAY prove to be a promising lighting technology and MAY have
>advantages over LED and CFL, but, given all the issues I've noted, if I was
>an investor I'd probably be looking elsewhere at present.
>
>                 Russell McMahon

Unless you have the power to mandate their use (or the phasing out, or
taxation of CFLs) through government dictat..

What kind of LED lamps are you using? The LED elements are getting quite
high in power (>100W), but they are still pretty pricey. Still-- LED
streetlights are now possible.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com



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