Back in 2003/4/5 I made some posts to this group on the topic of LED lighting,
and I thought it was interesting to come back and reflect on the state of
the art.

Over the past few years, prices of high power LEDs have crashed, and the
efficiency of the lower end of the scale has risen.

http://www.dealextreme.com/details.dx/sku.11809 - for example - 12W LED
for 12 quid - with 620 lumens output or so - about 50lm/w, comparable with
the lower end CFLs.

http://www.dealextreme.com/details.dx/sku.2394 - at the higher end -
if you use 12 of these, you get 12W, but with perhaps twice the brightness.

One of http://www.dealextreme.com/details.dx/sku.13691 - a universal
power supply - 10 of the above, and you get a 1000lm light, that uses maybe
12W - practically as efficient as a linear fluorescant, and much better
than a compact one, as bright as a 100W conventional light, for around
40 quid, and that's not even in volume.
If you're making a few thousand, you could probably sell them for that.

Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

At the moment nice warm white ones are about half the brightness.

So - some way to go, but it's catching up fast to CFL.

The dealextreme site (only a customer) also has other fun stuff.
I plan to take one of the above 12W LEDs, one of
http://www.dealextreme.com/details.dx/sku.1937, and do a starscape of the
brightest 300 or so stars.

Also experimenting with use in steps.

Pour little bit of concrete, put some fibers on top, pour bit more, repeat
until mold is full, then clean off with angle-grinder to expose the ends.

I'm also trying to source high refractive index spheres - as used in
reflective paint - to make a virtual sky light.

In article qIednYzPAu9qFcPVnZ2dnUVZ8j6dnZ2d@plusnet,
(Ian Stirling) writes:
I'm also trying to source high refractive index spheres - as used in
reflective paint - to make a virtual sky light.

They're called ballotini (Italian: "little balls";-) if that
helps you find them. Not sure they're actually high refractive
index though.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Ian Stirling" wrote in message
news:qIednYzPAu9qFcPVnZ2dnUVZ8j6dnZ2d@plusnet...
Back in 2003/4/5 I made some posts to this group on the topic of LED
lighting,
and I thought it was interesting to come back and reflect on the state of
the art.


....


Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

Mary

"Mary Fisher" wrote:

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...


That's more or less what happened with electric street lighting.

First they used incandescent bulbs that gave a reasonable impression
of white light. They weren't very bright, and used quite a lot of
power. Then someone invented/developed the sodium discharge lamp,
which was brighter and used much less power, and street lighting went
horribly yellow.

After that came the mercury discharge lamp (blue/green) and the high
pressure sodium discharge lamp (yellow/pink).

Mary Fisher wrote:
"Ian Stirling" wrote in message
news:qIednYzPAu9qFcPVnZ2dnUVZ8j6dnZ2d@plusnet...
Back in 2003/4/5 I made some posts to this group on the topic of LED
lighting,
and I thought it was interesting to come back and reflect on the state of
the art.


...

Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

Its the discontinuous spectra that is more objectionable that the actual
colour cast.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article qIednYzPAu9qFcPVnZ2dnUVZ8j6dnZ2d@plusnet, Ian Stirling
writes

http://www.dealextreme.com/details.dx/sku.11809 - for example - 12W LED
for 12 quid - with 620 lumens output or so - about 50lm/w, comparable with
the lower end CFLs.

2800mA? That's got to be a misprint, surely?

Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

IMO, it's unusable for room lighting. OK for point work (saw some used
in a museum recently for display case illumination and they were ok
there.)

I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

--
(\__/) Bunny says NO to Windows Vista!
(='.'=) http://www.cs.auckland.ac.nz/~pgut00...ista_cost.html
(")_(") http://www.cypherpunks.to/~peter/vista.pdf

"Mike Tomlinson" wrote in message
...

I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

As you said, it's a personal preference.

We have LEDs on our landing - only used at night of course - and we love it,
it's like the (full) moonlight we get through the windows.

I'm looking forward to more powerful ones for spot lighting in living
rooms - which means every room of course because we're alive :-)

Mary

In article ,
Mary Fisher wrote:
Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

It's not so much the 'cast' of the actual source when looking at *it*, but
more the sort of light it produces. Ie, what it does to other colours. And
the two are very different.

--
*There are two kinds of pedestrians... the quick and the dead.

Dave Plowman London SW
To e-mail, change noise into sound.

In article b6CdnQ0Sh_gkU8PVnZ2dneKdnZzinZ2d@plusnet,
John Rumm wrote:
If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

Its the discontinuous spectra that is more objectionable that the actual
colour cast.

Yup - I recently tried some 'warm white' LEDs which produce an even worse
spectrum than the 'blue' ones.

--
*Eat well, stay fit, die anyway

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Mary Fisher wrote:
I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

As you said, it's a personal preference.

We have LEDs on our landing - only used at night of course - and we love
it, it's like the (full) moonlight we get through the windows.

I doubt you do very much in the landing apart from walk through it.

I'm looking forward to more powerful ones for spot lighting in living
rooms - which means every room of course because we're alive :-)

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy this.

--
*Sorry, I don't date outside my species.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy this.


I'm quite happy with the colour on the monitor I'm using now - and
that's just three colours.

I also see no reason why an LED light shouldn't use many overlapping
phosphors to give a reasonably flat spectrum.

Andy

Dave Plowman (News) wrote:
In article b6CdnQ0Sh_gkU8PVnZ2dneKdnZzinZ2d@plusnet,
John Rumm wrote:
If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

Its the discontinuous spectra that is more objectionable that the actual
colour cast.

Yup - I recently tried some 'warm white' LEDs which produce an even worse
spectrum than the 'blue' ones.

I gather from a mate in the industry that the refrigerated display
sector are pushing development in this area so they can continue to
control how food looks in the supermarket.

"Dave Plowman (News)" wrote:
In article ,
Mary Fisher wrote:
I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

As you said, it's a personal preference.

We have LEDs on our landing - only used at night of course - and we love
it, it's like the (full) moonlight we get through the windows.

I doubt you do very much in the landing apart from walk through it.

I'm looking forward to more powerful ones for spot lighting in living
rooms - which means every room of course because we're alive :-)

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy this.


You'd be wrong - certain classes of warm-white LEDs have a spectrum
insignificantly different from tungsten - apart from IR.
However, these are _lots_ less efficient than normal ones.

"Dave Plowman (News)" wrote in message
...
In article ,
Mary Fisher wrote:
Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

It's not so much the 'cast' of the actual source when looking at *it*, but
more the sort of light it produces. Ie, what it does to other colours. And
the two are very different.

I know and that's what I'm talking about. Coloured light is cast on objects
which appear differently from when light is cast on them from a different
source.

Mary

In article ,
Ian Stirling wrote:
The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy
this.


You'd be wrong - certain classes of warm-white LEDs have a spectrum
insignificantly different from tungsten - apart from IR.
However, these are _lots_ less efficient than normal ones.

Indeed. And without reasonable efficiency there is absolutely no point in
them.

--
*When everything's coming your way, you're in the wrong lane *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andy Champ wrote:
The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy
this.


I'm quite happy with the colour on the monitor I'm using now - and
that's just three colours.

It isn't just three spot frequencies.

I also see no reason why an LED light shouldn't use many overlapping
phosphors to give a reasonably flat spectrum.

They don't use phosphors.

--
*Drugs may lead to nowhere, but at least it's the scenic route *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Andy Champ wrote:
The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy
this.


I'm quite happy with the colour on the monitor I'm using now - and
that's just three colours.

It isn't just three spot frequencies.

I also see no reason why an LED light shouldn't use many overlapping
phosphors to give a reasonably flat spectrum.

They don't use phosphors.

I thought they did - in making (some) white LEDs - using a colour
phosphor to "convert" blue light.

I guess that is sort of outwith the LED part of the LED (IYSWIM).

--
Rod

Hypothyroidism is a seriously debilitating condition with an insidious
onset.
Although common it frequently goes undiagnosed.
www.thyromind.info www.thyroiduk.org www.altsupportthyroid.org

"Dave Plowman (News)" wrote:
In article ,
Ian Stirling wrote:
The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy
this.


You'd be wrong - certain classes of warm-white LEDs have a spectrum
insignificantly different from tungsten - apart from IR.
However, these are _lots_ less efficient than normal ones.

Indeed. And without reasonable efficiency there is absolutely no point in
them.

But I do note that this is a really young field - well under a decade
for decent power LEDs, with an efficiency of over halogen light.

Claiming 'never' is perhaps a little pessimistic.

Rod wrote:
Dave Plowman (News) wrote:
In article ,
Andy Champ wrote:
The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy
this.


I'm quite happy with the colour on the monitor I'm using now - and
that's just three colours.

It isn't just three spot frequencies.

I also see no reason why an LED light shouldn't use many overlapping
phosphors to give a reasonably flat spectrum.

They don't use phosphors.

I thought they did - in making (some) white LEDs - using a colour
phosphor to "convert" blue light.

They do.
99.9% of 'white' LEDs are in fact a blue LED, with a varying sort of
phosphor on the top, that lets some of the blue through.

See page 5 of http://www.cree.com/Products/pdf/XLamp7090XR-E.pdf , for
a typical 'white' LED spectrum - the variants are assorted 'colour
temperatures' - byt these are dramatically misleading as there is a huge
gap at cyan-leafgreen.

The 'red' curve in this is 'warm white'.

There are better - http://www.lumileds.com/pdfs/DS47.pdf , see page 8 fig
2A for a spectrum that looks really quite close to tungsten.

However - these are one fifth as bright as the bluest whites on the first
datasheet.

It'll get better.

Mary Fisher wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
Mary Fisher wrote:
Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

It's not so much the 'cast' of the actual source when looking at *it*, but
more the sort of light it produces. Ie, what it does to other colours. And
the two are very different.

I know and that's what I'm talking about. Coloured light is cast on objects
which appear differently from when light is cast on them from a different
source.

As an aside, there is an argument for tungsten being semi hard-wired into
the brain.
Maybe not a good one.
But as we age, and more significantly as we are exposed to solar UV, the
amount of blue light recieved by the eye drops significantly.

This is just what happens when you use tungsten to illuminate things.

Dave Plowman (News) wrote:
In article ,
Andy Champ wrote:

I'm quite happy with the colour on the monitor I'm using now - and
that's just three colours.

It isn't just three spot frequencies.

True. But the "white paper" I'm typing on right know is a pseudo-white
made from RGB, and I'll be amazed if the spectrum is anything like
continuous.


I also see no reason why an LED light shouldn't use many overlapping
phosphors to give a reasonably flat spectrum.

They don't use phosphors.


Source please. (others have already backed me up)

Andy

On Jun 23, 11:48 am, stuart noble wrote:
Dave Plowman (News) wrote:
In article b6CdnQ0Sh_gkU8PVnZ2dneKdnZzinZ2d@plusnet,
John Rumm wrote:
If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

Its the discontinuous spectra that is more objectionable that the actual
colour cast.

Yup - I recently tried some 'warm white' LEDs which produce an even worse
spectrum than the 'blue' ones.

I gather from a mate in the industry that the refrigerated display
sector are pushing development in this area so they can continue to
control how food looks in the supermarket.

Theres a fluro tube colour called Rosetta that has a boosted red end ,
it dosen`t appear that way but red meat looks all the fresher under
it.

Adam

On Jun 23, 4:33 pm, (Ian Stirling) wrote:
"Dave Plowman (News)" wrote:



In article ,
Mary Fisher wrote:
I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

As you said, it's a personal preference.

We have LEDs on our landing - only used at night of course - and we love
it, it's like the (full) moonlight we get through the windows.

I doubt you do very much in the landing apart from walk through it.

I'm looking forward to more powerful ones for spot lighting in living
rooms - which means every room of course because we're alive :-)

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy this.

You'd be wrong - certain classes of warm-white LEDs have a spectrum
insignificantly different from tungsten - apart from IR.
However, these are _lots_ less efficient than normal ones.

Spectrum not being same as spectral power distribution, Lumileds data
sheet you flag up shows a big peak in deep red , tungsten shows a
realtively straight line, low at blue and rising to red, but no peaks
and troughs.

Adam

On Jun 23, 6:00 pm, "Dave Plowman (News)"
wrote:
In article ,
Andy Champ wrote:

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy
this.

I'm quite happy with the colour on the monitor I'm using now - and
that's just three colours.

It isn't just three spot frequencies.

LED is getting in as LCD backlight on a lot of things , usually with
RGB sources rather than phosphor based lamps.



I also see no reason why an LED light shouldn't use many overlapping
phosphors to give a reasonably flat spectrum.

They don't use phosphors.

Most of them do which was another part of Shuji Nakamura`s discovery
when working for Nichia, whose main business for previous 40 years had
been phosphors for CRT screens.

Adam


--
*Drugs may lead to nowhere, but at least it's the scenic route *

Dave Plowman London SW
To e-mail, change noise into sound.

L

On Jun 23, 5:18 pm, "Mary Fisher" wrote:
"Dave Plowman (News)" wrote in ...

In article ,
Mary Fisher wrote:
Admittedly, at the moment, the light colour from the above is pretty
horrible, and has almost no yellow.

If 'conventional' lighting had always had a blue cast then new, energy
efficient lighting was yellow, I suspect none of us would like it ...

It's not so much the 'cast' of the actual source when looking at *it*, but
more the sort of light it produces. Ie, what it does to other colours. And
the two are very different.

I know and that's what I'm talking about. Coloured light is cast on objects
which appear differently from when light is cast on them from a different
source.

Mary


Colour Appearence as in how the light appears aginst Colour Rendering
Index which tells you how accurately colours will be shown.

Adam

In article
,
Adam Aglionby wrote:
I gather from a mate in the industry that the refrigerated display
sector are pushing development in this area so they can continue to
control how food looks in the supermarket.

Theres a fluro tube colour called Rosetta that has a boosted red end ,
it dosen`t appear that way but red meat looks all the fresher under
it.

Growlux - used for forcing plants - tends to enhance many colours.

--
*I'm not as think as you drunk I am.

Dave Plowman London SW
To e-mail, change noise into sound.

Andy Champ wrote:

It isn't just three spot frequencies.

True. But the "white paper" I'm typing on right know is a pseudo-white
made from RGB, and I'll be amazed if the spectrum is anything like
continuous.

It isn't - there are big gaps in the gamut produced by CRT or LCD RGB
screens.

The rendition from other colour spaces is different again - which is why
it is difficult to get accurate colour representation of material
printed in CMYK from RGB sourced images.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
"Dave Plowman (News)" writes:
In article
,
Adam Aglionby wrote:
I gather from a mate in the industry that the refrigerated display
sector are pushing development in this area so they can continue to
control how food looks in the supermarket.

Theres a fluro tube colour called Rosetta that has a boosted red end ,
it dosen`t appear that way but red meat looks all the fresher under
it.

Growlux - used for forcing plants - tends to enhance many colours.

That's enhanced red for chlorophyll operation, at the expense of
blue and green which chlorophyll can't use. (Some plants need
other specific wavelengths to encourage flower production though.)
2700K warm white is almost as effective for plant growth, and makes
the colours look better to the human eye.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"Adam Aglionby" wrote in message
...
On Jun 23, 11:48 am, stuart noble wrote:
Dave Plowman (News) wrote:
In article b6CdnQ0Sh_gkU8PVnZ2dneKdnZzinZ2d@plusnet,
John Rumm wrote:
If 'conventional' lighting had always had a blue cast then new,
energy
efficient lighting was yellow, I suspect none of us would like it ...

Its the discontinuous spectra that is more objectionable that the
actual
colour cast.

Yup - I recently tried some 'warm white' LEDs which produce an even
worse
spectrum than the 'blue' ones.

I gather from a mate in the industry that the refrigerated display
sector are pushing development in this area so they can continue to
control how food looks in the supermarket.

Theres a fluro tube colour called Rosetta that has a boosted red end ,
it dosen`t appear that way but red meat looks all the fresher under
it.

Trouble is that the best meat isn't that horrid bright red ...

Mary

Adam Aglionby wrote:
On Jun 23, 4:33 pm, (Ian Stirling) wrote:
"Dave Plowman (News)" wrote:



In article ,
Mary Fisher wrote:
I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

As you said, it's a personal preference.

We have LEDs on our landing - only used at night of course - and we love
it, it's like the (full) moonlight we get through the windows.

I doubt you do very much in the landing apart from walk through it.

I'm looking forward to more powerful ones for spot lighting in living
rooms - which means every room of course because we're alive :-)

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy this.

You'd be wrong - certain classes of warm-white LEDs have a spectrum
insignificantly different from tungsten - apart from IR.
However, these are _lots_ less efficient than normal ones.

Spectrum not being same as spectral power distribution, Lumileds data
sheet you flag up shows a big peak in deep red , tungsten shows a
realtively straight line, low at blue and rising to red, but no peaks
and troughs.

Tungsten has a huge amount of energy in the IR, and slopes off towards
the visible - http://www.mtholyoke.edu/~mpeterso/c...r/awgachor.htm - the first graph.

For example - comparing the point at which the LED starts dropping off
at the red - 670nm, the eye has a responsivity of well under 5% of its
peak efficiency.
Over the range 670-400nm, the match is moderateley good - neglecting the
small peak at 470nm or so.
(talking of the warm white LED spectrum on page 8, fig 2A of the luxeon
datasheet)

On 24 Jun, 12:48, (Ian Stirling) wrote:
Adam Aglionby wrote:
On Jun 23, 4:33 pm, (Ian Stirling) wrote:
"Dave Plowman (News)" wrote:

In article ,
Mary Fisher wrote:
I can't stand the light from LEDs or CFLs. Moved into a new house last
year and the place was infested with CFLs. All since consigned to the
bin and replaced with nice incandescents.

As you said, it's a personal preference.

We have LEDs on our landing - only used at night of course - and we love
it, it's like the (full) moonlight we get through the windows.

I doubt you do very much in the landing apart from walk through it.

I'm looking forward to more powerful ones for spot lighting in living
rooms - which means every room of course because we're alive :-)

The requirements for decent lighting are different than just safety
illumination. And it wouldn't surprise me if LED can *never* satisfy this.

You'd be wrong - certain classes of warm-white LEDs have a spectrum
insignificantly different from tungsten - apart from IR.
However, these are _lots_ less efficient than normal ones.

Spectrum not being same as spectral power distribution, Lumileds data
sheet you flag up shows a big peak in deep red , tungsten shows a
realtively straight line, low at blue and rising to red, but no peaks
and troughs.

Tungsten has a huge amount of energy in the IR, and slopes off towards
the visible -http://www.mtholyoke.edu/~mpeterso/classes/phys301/projects2001/awgac...- the first graph.

For example - comparing the point at which the LED starts dropping off
at the red - 670nm, the eye has a responsivity of well under 5% of its
peak efficiency.
Over the range 670-400nm, the match is moderateley good - neglecting the
small peak at 470nm or so.
(talking of the warm white LED spectrum on page 8, fig 2A of the luxeon
datasheet)

Admittedly talking good warm white LEDs, they`re definately not all
equal, compare the Nichia NCCL023 warm white LED; circa. December
2004. with a no brand, graph directly below Nichia, about 1/4 down
page:

http://ledmuseum.home.att.net/specx31.htm

Adam