Led Accelerator and Peter Lowrie

LED-FX

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As some of you may have noticed I have been a vocal critic of Mr Lowrie and his claimed LED Accelerator.

In sci.engr.lighting I offered to send Mr Lowrie, with return postage paid,a disposable camera to take photographs of this development.

Mr Lowrie retains copyright of his photographs but I have licence to use them with appropriate credit in any commentary I may have on the device.

Mr Lowrie has accepted this offer and has told me that the photographs will include Voltage, Current Lux and nM meter readings with his device connected.

I remain very very sceptical about this device but will make whatever photographs I obtain available to sci.engr.lighting, sci.electronics.design and www.candlepowerforums.com

Adam
 

TheFire

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nobody has any information other than what's posted on his website. He's trying to sell it for $960,000USD, though... I think the general opinion is that it's not really much of anything, otherwise he'd be more willing to provide more technical details, pictures, etc. As it is, all we've heard is a bunch of hot air and lots of "you might steal my idea if I tell you anything other than it's name" from this guy.
 

evan9162

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If he is actually serious about this product, he would have taken loans and gone through the patent process. Once the preliminary application is complete, and the patent application has been filed through the USPTO, then he has locked himself in as the inventor of the technology. By having a dated lab notebook noting his findings and experiments, and having a trusted and neutral third party sign off on the notebook (indicating verification of the date of the entry, and that the recorded information is valid and reasonable), he has established what is known as "prior art". Demonstrating prior art is an important tool in defending intellectual property rights if it comes down to that.

I have just gone through the patent process this year. Before we even had a full implementation of our idea, we had a patent lawyer do the preliminary patent research, draw up the paperwork, and submit it to the USPTO. Our application is now on file, and we have plenty of lab notebooks describing our invention and other aspects/applications thereof. We have revealed the invention and how it works already too. We did this to get possible licensees of the technology interested in using our invention.

This smells of another "I can't tell you because the big bad corporation will steeel my idea" tinfoil hat super invention scams that have been thrown out a zillion times.

Simply by avoiding the patent process, Peter has lost credibility in my mind.
 

MR Bulk

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Harumphhh...I already made an LED accelerator long ago, during my childhood. Didn't even have it patented. It accelerates lots of other small objects, too. It's called a -- slingshot! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif
 

Stanley

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[ QUOTE ]
MR Bulk said:
Harumphhh...I already made an LED accelerator long ago, during my childhood. Didn't even have it patented. It accelerates lots of other small objects, too. It's called a -- slingshot! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

[/ QUOTE ]

/ubbthreads/images/graemlins/grin.gif LMAO!
 

Steelwolf

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I have heard that one of the big problems facing inventors with shallow pockets is that if anyone infringes on your patent, it is difficult to sue them or get adequate compensation, mainly because you can't afford the big time lawyers that big businesses can. Heck, you may not even be able to afford small time lawyers unless you can convince them to take you on pro bono. And pro bono would eat away easily half of any settlement anyway.

A side effect of this (or so I heard) is that some people are unwilling to submit patents until after they have secured an investor with deep enough pockets. And sometimes, it is possible for a bright enough chap to redesign your idea so that it doesn't quite fall in the bounds of your patent and so doesn't technically infringe anyway.

Anyone able to comment on this?
 

evan9162

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That's why you have any potential investors sign NDAs, strictly forbidding them from divulging ANY information about your invention. If they suddenly come up with a similar device, you can then nail them for breach of contract (and possibly industrial espionage).

My company (HP) strictly forbids us from using other competitors trade secrets if we have been exposed to them. So any reputable company will forbid their employees from using anothers trade secrets.

Patents only cost $10K-$12K to research and file. If you're serious about your invention, you will accept that risk, take a loan for the amount, and secure yourself with the USPTO. It's a risk inventors must be willing to take, or they will banish themselves to the "supar sekret invention, but the bad guys will steal it" crowd, which often has little credibility in anyone's mind.
 

Jonathan

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Led-FX,

Thanks for the links, I followed them, and I think that Peter actually has a nugget of an original idea. He has also 'spilled the beans' on the basic concept of the idea, and by 'offering to sell' without having done the patenting work, he has greatly reduced the value of the patent rights that an investor could get.

His comment "1 LED = Diode = 1/2 thermocouple, how can I say much about how it works without giving the game away." is the kicker.

You correctly mention the difference between a thermocouple and a peltier effect device, but they are in essence the same things, simply optimized differently. If you place a temperature difference across a peltier effect device, you obtain a voltage difference that you can measure and use to evaluate the temperature difference. If you power a thermocouple, then one pair will heat up and the other will cool down (or heat up less...as I^2R heating might overwhelm the cooling effect).

I believe that what Mr. Lowrie is trying to sell is the idea of alternately operating the LED in an overpowered pulse mode, and then operating as the heat absorbing junction of a thermoelectric heat pump. The goal is to operate at higher average power while improving the heat dissipating capability of the LED. If he can successfully get the LED to 'refrigerate itself' then he does have something novel and interesting.


I would call the above concept plausible technobabble /ubbthreads/images/graemlins/smile.gif I have grave reservations about the technical viability of the concept, and I also have reservations about the economic value of the concept even if it does work. However it is enough that I can't simply dismiss Lowrie's claims as simply impossible.

If his device works as I suggest, then during the pulse period you are operating the LED at higher power and (slightly) lower efficiency. I say slightly because most of the efficiency lost when an LED is operated at higher power comes from the fact that the junction temperature is increased...if he is holding the junction temperature constant, then the efficiency loss is reduced. Then during the 'refrigeration' period, still more power is consumed pumping the heat away from the LED, presumably heating up a junction elsewhere in the driver circuit. Net result: more light output from a given LED, with more power consumption, and more heat dissipated, but with the LED itself running cooler and a mythical 'other junction' getting hotter.

I question the technical viability of the LED as a thermoelectric junction because the potential barriers are all wrong. The energy of a visible light photon is lots more than the energy of a thermal electron at room temperature. I simply don't think that an LED junction would make a good thermoelectric junction. Current flow and heat transport would be very small, and IMHO the resistance heating effects in the package would swamp any cooling effects.

I question the economic viability because LEDs themselves are already 'bright enough'. You can already purchase LEDs that are far too bright to look at. This means that for indicator and direct viewing applications, you don't need the 'LED accelerator'; simply select a brighter LED and use a normal constant current supply. For illumination applications, brighter LEDs would be potentially useful, but for illumination you are fighting the availability of things like compact florescent lights which are cheaper and more efficient. Any system which makes LEDs _less_ efficient will diminish their ability to compete. Finally the cost of this driver circuit will have to be lower than simply using _more_ LEDs. Why but 1 '4x accelerated' LED if I could buy 4 normal LEDs?

-Jon
 

Steelwolf

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Tough road to travel. I do hope that Peter Lowrie is able to convincingly prove that his design works. Real inventors are few and far between and need all the encouragement they can get. OTOH, scammers need to be put down hard.
 

jtr1962

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I happen to know something about thermoelectrics, and I can state emphatically that even materials optimized for thermoelectric effect are very inefficient compared to either conventional refrigeration or the theoretical maximum Carnot efficiency. Bismuth Telluride is currently the best material available for thermoelectric junctions, although there are test materials in the lab that are at least twice as efficient. Furthermore, not matter how you drive a T-1 or T-1 3/4 LED, the simple fact is that as you put more power to the junction, whether to cool the emitter or to emit light, this heat has only one way out-through the leads. A large amount of power applied to "cool" the LED will cause more of a temperature rise on average than just overdriving the LED due to the inefficiency of thermoelectirc material. Some experiments done here involving cooling LEDs show that the efficiency increase is more than offset by the power required to run the thermoelectric cooler. Since an LED is an even less efficient thermoelectric material than bismuth telluride, this fact would be even more true trying to use the LED to cool itself.

I'm rapidly coming to one of two conclusions here. Either this is pseudoscientific nonsense that won't work as claimed, or Mr. Lowrie has discovered some novel way of driving LEDs so that the thermoelectric properties are increased by many times over what they would be using DC current. If the latter is the case, then I would think driving conventional thermoelectric materials in the same manner might allow them to approach maximum theoretical efficiency. BTW, no theoretical reason why the idea wouldn't work in principle. If you want to cool something producing, say, 300 mW of heat down to 0° and your hot side temperature is 100° C, then the maximum(Carnot) COP(coefficient of performance) is Tc/(Th-Tc)=273K/100K=2.73. This means you would only need an additional 110 mW to power the cooling engine, or a total of 410 mW. For a T 1 3/4 LED this would cause a temperature rise of maybe 75°C(hence the reason I chose 100°C as my hot side temperature).

Needless to say, no current thermoelectric material even comes close to Carnot efficiency.

I also second the hope that this invention isn't some sort of scam. If Mr. Lowrie has really come up with something novel, he is the kind of person we need more of.
 

Gransee

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Another approach he might be taking is to use the thermocouple to generate electricity "from the heat" of the LED. Of course this is not a very good idea since current is generated from the heat flow and not the heat itself. Restricting the heat flow would cause the LED to become less efficient which would loose more power than that recaptured by the junction.

I wish Mr. Lowrie luck in his future endeavors.
 

Badbeams3

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The concept of useing die-electric cooling for the led was discussed more than a year ago right here on CPF...more than a year ago. The conclusion was it would use more power than there would be benefit...at least in portable lighting...like flashlights...but maybe we were all wrong way back then.

I still say...direct die liquid cooling is the ticket! Has to do with removing the special flip up lens and pi$$ing straight on the led when it gets hot /ubbthreads/images/graemlins/grin.gif

I`d tell you more, but I know you guy`s just want to steal my $$$$$$ idea. I will consider doing a pass-around...no need to return it /ubbthreads/images/graemlins/smoker5.gif

Ken
 

Entropy

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Even if you can get thermoelectric effects to cool the LED across the PN junction (or the metal-semiconductor lead junction), that doesn't remove heat from the immediate area of the die.

In other words: It's snake oil. In fact, any thermoelectric effects are likely to increase the temperature of some portions of the die (the portions where heat is being pumped.)

Thermoelectric cooling of an LED with an independent thermoelectric cooler makes sense if you want incredible brightness in a small package (See the threads about 1W Luxeons driven at 1.5-2A+ with a Peltier), but that requires a seperate TEC and is not going to increase overall system efficiency.
 
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