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PostPosted: Fri Oct 17, 2014 11:32 pm 
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Whilst reading the Manchester Metro last week, I came across this little article. Considering the technological advances that have been made in LED lighting recently (and how it is seeing off our traditional streetlighting heritage), I didn't realise that it was 50 years ago that the first practical red LED was invented. As well as the little "power on" indicator on your telly, the red LED also paved the way to other applications.

Understandably, the inventor of the first LED is feeling snubbed by the Nobel panel because the Prize for Physics went to three engineers who co-created the "blue" version. Without this, it is unlikely that energy efficient, white LED lighting would have been practical.

According to online sources however, he felt that the blue LED was simply an evolution of a technology that already existed - thanks to him.

Interesting to think that if it wasn't for the invention of the red LED, theoretically no electronic appliance would have a "standby mode".


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PostPosted: Sat Oct 18, 2014 7:01 am 
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The physics and material in blue LEDs are completely different to red (and amber and green), hence why it took so long for blue LEDS to be available.


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PostPosted: Mon Oct 20, 2014 7:50 pm 
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If I had invented the LED I would be a bit annoyed too. Yes, whilst the chemical compositions may be more difficult, at the end of the day the blue LED was a development of something that already existed. If the LED didn't already exist, would the inventors of the blue LED have developed the blue LED? Yes, the blue LED has revolutionised things, but I do find it sad that no thank you was given to the red and green LED pioneers.


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PostPosted: Mon Oct 20, 2014 8:59 pm 
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The blue LED is so fundamentally different to the red and green devices that there are practically no links to the earlier technology. Whole new areas of technology needed to be developed.

Its a bit like saying that jet powered aircraft are the same as piston propeller driven ones, both fly but their method of propulsion (and many other systems) are completely different, with the newer technology sharing little in common with the older technology.

It is the dumbing down of reporting of technology and science which has failed to make this distinction in the case of the blue LED. The technological break through was different to that of the earlier devices.


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PostPosted: Mon Oct 20, 2014 10:32 pm 
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Phosco152 wrote:
Its a bit like saying that jet powered aircraft are the same as piston propeller driven ones, both fly but their method of propulsion (and many other systems) are completely different, with the newer technology sharing little in common with the older technology.


An valid analogy, however regardless of the motive power used, the basic aircraft owes its existence down to the invention and successful demonstration of the "three axis control" by the Wright Brothers in 1903. This control system is acknowledged to be what made "fixed wing powered flight" possible. A piston-prop or jet engine is no good to nobody unless it is strapped down to something!

As I'm not into aviation (but can quote wiki), I'm trying to think of a lamp / streetlighting related analogy - any ideas?

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PostPosted: Tue Oct 21, 2014 4:41 am 
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SOX and SON, both are sodium discharge lamps, but the newer technology of SON owes practically nothing to the earlier technology.

"Inventing" the low pressure lamp won't develop the technology to allow a SON lamp to be made.

Like blue LEDs following decades after red/green ones, SON lamps took similar timescales to develop to a commercially viable product following development of low pressure SO.

Even for SOX, it is quite a technology jump from the first SO lamps. The use of a reflective semi conductor thermal barrier in the mid 1960s and the technology required to produce it could have not been foreseen in the 1930s when the first commercial lamps were produced.

Similarly SLI lamps are "low pressure" but are significantly different that they required a technology leap and you wouldn't credit their invention to the same inventor of the low pressure sodium discharge.


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PostPosted: Tue Oct 21, 2014 6:30 pm 
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But fundamentally, there are the following light source types:

Incandescent - passing an electric current through a filament to produce light
Arc - passing an electric current through a pressurised gas to produce light
LED - passing an electric current through a semiconductor that emits light

The roots of all incandescent lamps go back to the invention of the first incandescent lamp. The roots of all arc lamps go back to the invention of the first arc lamp. Similarly, the roots of all LEDs go back to the invention of the first LED. Without having the first, you cannot develop the technology.

Halogen lamps are far more efficient and longer life than the first carbon-filament incandescent lamp, but I would give more credit to the person who discovered that passing electricity through an object to make it glow so hot that it produces useful light than to somebody who took the idea and made it better. There's a big difference between invention and development. It is easier to develop "the known" than to invent "the unknown". And that's the thing, had the red or green LED not been invented, I very much doubt these scientists would have developed the blue LED as the first LED. Like the original inventors, they would have most likely invented the red LED first, assuming they ever had the lightbulb above the head moment in the first place.

EDIT: incidentally, the fact that red and green LEDs already existed meant that trying to develop a blue LED was a completely obvious thing to do, to complete the trio. The keyword is "complete", not "invent".


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PostPosted: Tue Oct 21, 2014 10:57 pm 
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This is getting to be quite a topical subject and I'm pleased it seems to be arousing lots of interest. I am mindful that there is a danger it could go wildly off topic, but I have popped in a couple of observations anyway

First of all, I am inclined to agree with the view that whilst invention need not imply a totally unique product or process, (wiki has lots of examples of what an invention is, both in theory, in practice and in law) there are less and less things being invented today compared to the those in the past ie the lightbulb, phonograph, dishwasher, polaroid camera etc.

These days however, is it not more a case of "evolution, not revolution"? A reasonable example could be the Urbis ZX1, which I understand was the first IP65 rated lantern due to its revolutionary "sealsafe" system. Beyond that, I think it was no better or worse than an Alpha 8. (Do you remember the advertising bumf which showed it lit up, whilst dunked in a fish tank?). Was this lantern a result of invention in its own right, or did it evolve from earlier designs and a need for improvement.

I suppose the main view I have on the LED story is, whether the search for the high power, high efficiency white LED is pushed on by the following needs. (Nb: I'm not into any of that "conspiracy theory" stuff).

Will the huge financial and energy investment currently being made into white LED technology...

1. Conserve the Earth's finite resources? OR

2. Reduce the demand for electricity and thus reduce CO2 emissions? OR.

3. Reduce the demand for electricity, thus causing redundant assets to be closed and providing real savings for generators, due to reduced overheads which could be passed on to consumers in the form of lower bills? OR

4. Reduce demand for electricity, allowing redundant assets to be closed and providing real savings for generators, due to reduced overheads which could be passed onto shareholders in the form of higher dividends? OR

5. Provide a valuable and intellectually controllable / chargeable technology, which could in theory be licensed to LED manufacturers - like GM bio-technology?

Answers on a postcard...


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