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| I.N. Galidakis... |
 Posted: Sat Oct 10, 2009 4:40 pm |
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Guest
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After looking carefully at the Nichia-type cheap bright white LED whose spectrum
was added to my web page lately, I projected the beam against a white wall and
can discern a mini purple/blue discharge at the center and yellow fluorescence
around it.
My question about these LEDs now is: Is there an actual "discharge" taking place
at the very center of this LED?
The reason I am asking is because in older LEDs I examined the core long time
ago and could see only a very thin wire connecting the diode electrodes.
On this LED, when I point it at the wall, I see a very faint discharge. Are my
eyes playing tricks or is there an actual discharge taking place there?
Thanks,
--
Ioannis |
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| Victor Roberts... |
| Posted: Sat Oct 10, 2009 6:55 pm |
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On Sun, 11 Oct 2009 01:40:30 +0300, "I.N. Galidakis"
<morpheus at (no spam) olympus.mons> wrote:
[quote:ee3c53ecd9]After looking carefully at the Nichia-type cheap bright white LED whose spectrum
was added to my web page lately, I projected the beam against a white wall and
can discern a mini purple/blue discharge at the center and yellow fluorescence
around it.
My question about these LEDs now is: Is there an actual "discharge" taking place
at the very center of this LED?
The reason I am asking is because in older LEDs I examined the core long time
ago and could see only a very thin wire connecting the diode electrodes.
On this LED, when I point it at the wall, I see a very faint discharge. Are my
eyes playing tricks or is there an actual discharge taking place there?
Thanks,
[/quote:ee3c53ecd9]
Is this the real Ioannis?
There are no discharges (as we know them) inside LEDs.
The LED chip projects a narrow blue beam. Some of this
comes right through the phosphor, while the rest of the
light is scattered, absorbed, and reemitted at various
longer wavelengths. This probably accounts for the spot of
bluish light that you see when the beam is projected on the
wall.
--
Vic Roberts
http://www.RobertsResearchInc.com
http://www.cflfacts.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.
This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission. |
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| I.N. Galidakis... |
| Posted: Sat Oct 10, 2009 9:40 pm |
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Guest
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Victor Roberts wrote:
[quote:b69495d80a]On Sun, 11 Oct 2009 01:40:30 +0300, "I.N. Galidakis"
morpheus at (no spam) olympus.mons> wrote:
After looking carefully at the Nichia-type cheap bright white LED whose
spectrum was added to my web page lately, I projected the beam against a
white wall and can discern a mini purple/blue discharge at the center and
yellow fluorescence around it.
My question about these LEDs now is: Is there an actual "discharge" taking
place at the very center of this LED?
The reason I am asking is because in older LEDs I examined the core long time
ago and could see only a very thin wire connecting the diode electrodes.
On this LED, when I point it at the wall, I see a very faint discharge. Are
my eyes playing tricks or is there an actual discharge taking place there?
Thanks,
Is this the real Ioannis?
[/quote:b69495d80a]
Of course. I don't know whatever gave you the idea that just because I happen to
know a couple of things about lamps, I also, automatically understand p-n-p
junctions or their operation. I am very far behind on LED basics. I need to do
more homework :-)
[quote:b69495d80a]There are no discharges (as we know them) inside LEDs.
The LED chip projects a narrow blue beam. Some of this
comes right through the phosphor, while the rest of the
light is scattered, absorbed, and reemitted at various
longer wavelengths. This probably accounts for the spot of
bluish light that you see when the beam is projected on the
wall.
[/quote:b69495d80a]
So the difference seems to be that in classic discharges we have plasma emitting
photons, while on diode junctions we have solid matter emitting photons?
Is that why you say "no discharges (as we know them)?
Thanks,
--
Ioannis |
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| Victor Roberts... |
| Posted: Sun Oct 11, 2009 10:57 am |
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On Sun, 11 Oct 2009 06:40:46 +0300, "I.N. Galidakis"
<morpheus at (no spam) olympus.mons> wrote:
[quote:bc6d61cc74]Victor Roberts wrote:
On Sun, 11 Oct 2009 01:40:30 +0300, "I.N. Galidakis"
morpheus at (no spam) olympus.mons> wrote:
After looking carefully at the Nichia-type cheap bright white LED whose
spectrum was added to my web page lately, I projected the beam against a
white wall and can discern a mini purple/blue discharge at the center and
yellow fluorescence around it.
My question about these LEDs now is: Is there an actual "discharge" taking
place at the very center of this LED?
The reason I am asking is because in older LEDs I examined the core long time
ago and could see only a very thin wire connecting the diode electrodes.
On this LED, when I point it at the wall, I see a very faint discharge. Are
my eyes playing tricks or is there an actual discharge taking place there?
Thanks,
Is this the real Ioannis?
Of course. I don't know whatever gave you the idea that just because I happen to
know a couple of things about lamps, I also, automatically understand p-n-p
junctions or their operation. I am very far behind on LED basics. I need to do
more homework :-)
There are no discharges (as we know them) inside LEDs.
The LED chip projects a narrow blue beam. Some of this
comes right through the phosphor, while the rest of the
light is scattered, absorbed, and reemitted at various
longer wavelengths. This probably accounts for the spot of
bluish light that you see when the beam is projected on the
wall.
So the difference seems to be that in classic discharges we have plasma emitting
photons, while on diode junctions we have solid matter emitting photons?
Is that why you say "no discharges (as we know them)?
Thanks,
[/quote:bc6d61cc74]
In a light emitting diode, photons are emitted from the
junction between the P-type and N-type material. I didn't
want to get into a battle of words with some person who felt
that the free electrons and holes in this region constituted
a "discharge."
--
Vic Roberts
http://www.RobertsResearchInc.com
http://www.cflfacts.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.
This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission. |
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| I.N. Galidakis... |
| Posted: Sun Oct 11, 2009 2:56 pm |
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Guest
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Victor Roberts wrote:
[snip]
[quote:22a725aece]In a light emitting diode, photons are emitted from the
junction between the P-type and N-type material. I didn't
want to get into a battle of words with some person who felt
that the free electrons and holes in this region constituted
a "discharge."
[/quote:22a725aece]
Sorry for the confusion. The way I understand it, seems that the only difference
between a "classic" discharge and what happens in a LED, is the "medium" inside
which the electrons bounce around. In a classic discharge they bounce around in
plasma. In a LED they seem to be bouncing around in solid matter. In both cases,
photons are emitted. Hence my strange terminology in terms of "discharge".
--
Ioannis |
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| Don Klipstein... |
| Posted: Mon Oct 12, 2009 10:05 am |
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Guest
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In article <1255214442.59241 at (no spam) athprx03>, I.N. Galidakis wrote:
[quote:dc052ad10b]After looking carefully at the Nichia-type cheap bright white LED whose
spectrum was added to my web page lately, I projected the beam against a
white wall and can discern a mini purple/blue discharge at the center and
yellow fluorescence around it.
My question about these LEDs now is: Is there an actual "discharge"
taking place at the very center of this LED?
The reason I am asking is because in older LEDs I examined the core long
time ago and could see only a very thin wire connecting the diode
electrodes.
On this LED, when I point it at the wall, I see a very faint discharge.
Are my eyes playing tricks or is there an actual discharge taking place
there?
[/quote:dc052ad10b]
There is no discharge. The blue is from the blue LED chip. The area of
glowing phosphor may be larger than the chip, with the central portion of
a mound of phosphor showing light that is more bluish than surrounding
areas. The phosphor may cover the chip unevenly in some cheaper LEDs,
leading to a small especially bluish spot or streak.
BTW, most blue LED chips have nondonductive substrates (artificial
sapphire), and have 2 wires going to the chip. Sometimes the connections
leave an odd-shaped area of the chip exposed.
- Don Klipstein (don at (no spam) misty.com) |
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| TKM... |
| Posted: Mon Oct 12, 2009 4:15 pm |
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Guest
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"Don Klipstein" <don at (no spam) manx.misty.com> wrote in message
news:slrnhd730r.ctf.don at (no spam) manx.misty.com...
[quote:2040b754f9]In article <1255214442.59241 at (no spam) athprx03>, I.N. Galidakis wrote:
After looking carefully at the Nichia-type cheap bright white LED whose
spectrum was added to my web page lately, I projected the beam against a
white wall and can discern a mini purple/blue discharge at the center and
yellow fluorescence around it.
My question about these LEDs now is: Is there an actual "discharge"
taking place at the very center of this LED?
The reason I am asking is because in older LEDs I examined the core long
time ago and could see only a very thin wire connecting the diode
electrodes.
On this LED, when I point it at the wall, I see a very faint discharge.
Are my eyes playing tricks or is there an actual discharge taking place
there?
There is no discharge. The blue is from the blue LED chip. The area of
glowing phosphor may be larger than the chip, with the central portion of
a mound of phosphor showing light that is more bluish than surrounding
areas. The phosphor may cover the chip unevenly in some cheaper LEDs,
leading to a small especially bluish spot or streak.
BTW, most blue LED chips have nondonductive substrates (artificial
sapphire), and have 2 wires going to the chip. Sometimes the connections
leave an odd-shaped area of the chip exposed.
- Don Klipstein (don at (no spam) misty.com)
[/quote:2040b754f9]
Remember too that blue wavelengths of light are not handled well in the eye
from the optical standpoint. Blue light sources, for example, appear
optically larger than they are physically.
Terry McGowan |
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