标签: LEDs

Solar-based energy is often associated with electricity-generating solar cells; solar-based heating systems using a working fluid; solid-state thermoelectric-based conversion; or perhaps a solar-concentrator which liquefies some salt-based compound for storage .   Now there's a new entrant in the photon-to-electron race: an optical rectifying antenna, or rectenna. This highly experimental device, discussed here , was developed at the Georgia Institute of Technology (better known as "Georgia Tech"). It captures and rectifies photons to produce electricity directly; they claim this the first time this has been done. You can read a more-detailed technical discussion in this academic paper in Nature , as well. This optical rectenna developed at Georgia Tech uses advanced physics principles and materials, and is claimed to be the first to achieve direct optical-to-RF conversion.   Rectennas are not new: they have been used for forty-plus years in highly specialized situations to direct RF-to-electron conversion (and Google "Nikola Tesla" for even earlier efforts). Another recent story " Rectenna Serves 2.45-GHz Wireless Power Transmission " gives full details on one version which claims 63% conversion efficiency; certainly impressive. Looking at the RF article and all the details, you see that as in so many advanced ideas, the concept is straightforward but the actual implementation is quite complicated with many subtleties. Similarly, reading the Georgia Tech paper in Nature , you get a good sense of the technical challenges of capturing and converting photons. The low efficiency of around 1% is certainly not marketable yet, as conventional solar cells are running in the 10-20% range, but you never know where these things will go, what breakthroughs may occur, or when they may happen (please, let's NOT see a roadmap yet, that's way too premature).   One other point is apparent looking at the optical rectenna: it is made possible due to advances in nanomaterials. I recently attended the annual conference of the Materials Research Society , where 5,000+ attendees discussed, explored, and demonstrated the latest in materials along with their creation, applications, and test at temperatures from near 0 K to thousands of degrees; the test aspect, even at room temperature, is a major challenge for many of these nanomaterials. There's certainly lots of fascinating things happening that may have a significant impact on technology in ways we can't foresee yet. When we casually use packaged devices and products, it’s easy to not realize how much basic materials science are the now-routine enablers, in terms of new materials, ultrapure elemental and created materials, and understanding of their electrical, chemical, physical, optical, and mechanical properties. Even if you see little need to follow developments in material science (we can't do everything ), it's probably a good idea to at least follow developments in optical-related science, engineering, and test. Laser Focus World and Photonics (both available online and in print) are valuable and readable resources with insight, ideas, and even inspiration. Given the major role that optical concepts and components have in so many electronics systems, including LEDs, lasers, photodetectors, optical fiber links, filters, displays, and instrumentation, it's a worthwhile use of precious time.

A few days ago, I was watching TV with my 16-year-old son. He's got me hooked on all the antiques-based reality TV shows that are on at the moment, such as Pickers (two guys driving across the country seeing what treasures they can find in peoples' attics and old barns and suchlike) and Pawn Stars (the items that roll into a 24/7 pawn shop in Las Vegas). The most recent program of this ilk that we've started watching is Storage Wars , in which a bunch of folks go to storage complexes where the contents of sheds that are no longer being paid for are auctioned off (their owners may have moved away, passed away, been sent away , or whatever). The regulars on the program are Darrell (the "gambler"), Barry (the "collector"), Jarrod (the "young gun"), and Dave (the "pain in everyone's backside"). The idea is that when a shed is opened (which involves cutting off the lock), the bidders can look inside but they cannot cross the threshold and they cannot touch anything. In some cases, you can see quite a lot inside the shed; in other cases, the shed is full floor-to-ceiling and you have to take a guess as to what might be in there; and sometimes it's in-between, but one of our experts might spot a hint of a sniff of an item of interest – perhaps a curved corner of something peeking out from behind a box... So then there is the auction for this particular shed. The highest bidder wins and puts his own lock on it. And then they all move on to the next shed. Later in the program we watch them rooting through the sheds they purchased seeing what they have acquired. Sometimes a shed that looks like it might contain real treasures ends up containing dross. Alternatively, a shed that looks like it's worth only a hundred dollars or so may end up containing valuable works of art, antiques, jewellery, and sometimes even cold hard cash (the contents of one shed ended up selling for $30,000). The thing is that, in last night's program, Barry purchased a locker in which he discovered an old (circa 1950s) television set. Initially he thought it might be worth some money, but he was quickly disillusioned. Later, one of Barry's friends removed the non-working electronics (CRT, vacuum tubes, etc.) and replaced them with a three-dimensional miniature model. I thought to myself "That's a really good idea – this would look very tasty in the corner of my office." I also thought to myself "I could do this much better than that guy!" I'm sort of thinking that a caveman diorama might look interesting – something vaguely like the following:     Of course I'm over-engineering things already. I'm thinking that this could be computer-controlled such that when it's daylight in the real world it could be daylight in the diorama. When dusk falls in the real world, dusk also falls in the diorama, and so forth. I could also have a camp fire flickering away (using LEDs), maybe some nights it would be storming in both the real world and the diorama and you'd see the occasional flash of lightning. Hold me back!!! Of course the first thing I need is an old television. I already have a real nice 1950s one in my study at home, but that one looks good just the way it is. (I found in in an antique shop when I was visiting my cousins in Edmonton, Canada, about 15 years ago. It cost me 50 Canadian dollars, which was a really good deal, but don't ask me how much it cost to ship it back to Alabama!) I keep on thinking that if I could get it working it would look great playing old "I Love Lucy" type programs in the background, but we digress... So, this morning when I came into work, I started asking the other guys in the office if they had seen an old-fashioned TV recently. One of the guys mentioned that there was a TV repair shop in a dingy strip mall in the seedy part of town, so I drove over there this lunchtime. My initial thought was that the repair guy might see this sort of thing on his travels. He went one better, because he actually had a 1953 set in the shop. He'd picked it up a few years ago with the idea of using it for something or other, but had never gotten around to doing anything with it. So I ended up buying it off him... ...that was the happy part... ...the sad part was that we ended up chatting and I asked how business was going and he told me that things really aren't very good. This guy is getting on in years; he learned everything he knows about electronics from his dad; all he knows is how to repair TVs and VCRs; and very few people are bringing them in to be repaired these days (instead they chuck them away and but a new one). He told me that even as recently as 10 years ago he would see an average of three TVs a day (he also mentioned "80 TVs a month") coming into his shop for repair. Now it's just one TV every now and then. Fortunately, his house is paid for as is his truck. He lives about 40 miles away in Tennessee. The truck has 340,000+ miles on the clock. He can barely afford the gas to come into his shop. When the truck fails he doesn't know what he's going to do. It's getting close to the stage where he's going to have to shut up shop and find some other employment. But he's never worked for anyone else (apart from his father) and he doesn't know how he would manage. He's also a very shy person who finds it difficult to interface with people and strike up conversations, let alone friendships. His wife works with him and she expressed amazement that he was talking to me (people do – I don't know why – maybe it's just to stop me talking to them ). The end result is that I'm really happy I have my old TV to play with, but I'm really sad thinking about this guy. Also, I realise how amazingly lucky I am to be an engineer who can write (or maybe a writer who used to be an engineer), because it's a cold, cold world out there when the skill you have is no longer required...  

Younger people are not much interested in electronic-circuit design and hands-on engineering. That's because active and passive components are too small to handle, probe, swap, and generally do much with—unless you are a pick-and-place machine or bed-of-nails prober. Yes, we have seen articles explaining how a skillful amateur can load and solder those high-density PC boards with ICs whose leads are under the package and passives almost too small to see. But reality is that it is fairly hard and unforgiving, and even if you are successful, it's pretty much impossible to poke and probe. And if you decide you want to try a different resistor in that circuit. . . well, good luck on removing and replacing the grain-of-pepper one that is soldered down. But there's still hope out there. The other day, I received a printed—yes, printed—catalog from a company that provides all sorts of electronic and electromechanical components for hobbyists and professional prototypes. Some of these components were new, while others (such as motors and gearboxes) were likely removed from equipment or a supplier's overstock; almost all were interesting. This particular catalog was from All Electronics Corp. (click here ) but there are many other supply houses out there with similar offerings. And what joy it was, to thumb through the pages. There were small and fractional-horsepower motors (AC and DC), gearbox assemblies, rocker and toggle switches, multipole relays, LEDs in various configurations, specialty items such as a switch which trips a tiny amount of air pressure, and much more. The joy wasn't just nostalgia, which is a non-starter in our industry. All the items displayed and detailed on the pages combined to stimulate ideas and remind me of the possibilities of what you could actually build, touch, adjust, poke around in, reconfigure, and more. Almost everything could actually be handled, soldered or wired to, resoldered and rewired, reconfigured, and in general, be real and tangible. So go ahead, go to the web site of this company or others like it, or even better, get your hands on a paper catalog. It will confirm that there is still an opportunity for the joy of discovery. You can plan do-it-yourself construction of circuits and systems with human-sized parts, with motors and switches and lights than do and mean something, and which provide a hard-to-explain—but very real—sense of satisfaction. Just looking at those motors and switches, I could see some potential projects might want to try. Is my point valid? Or am I just longing for a time and type of hands-on project that is gone, and no longer realistic? Do you have a similar supply house/source you use?  

An advanced technical development can seem so simple, and becomes so common, that even engineers—as well as the general public—believe it just happened and was always so. So it is with the now-ubiquitous bar code, used on products and so much more—and which first saw commercial use in 1974. I thought about this because of two recent items: one is the passing of the champion of bar codes and coding, Alan Haberman a few weeks ago; you can read an interesting New York Times obituary here (free, but registration may be required); and the other was an article in The Wall Street Journal here about a hot new trend of so-called "designer" bar codes—and some of them are quite creative, despite (or may due to) the confines of the bar-code standard. The point which the obituary makes clear, and that we know but sometimes forget, is that it is not enough to just have a better idea or a working model to achieve success and market penetration. It takes a champion, an evangelist, a tireless promoter (I mean "promoter" in the positive sense, not a scam artist). Today, bar codes are used for much more than just store checkout; I am sure you can make your own list of unusual places you have seen them. Many times, it takes a lot of back and forth effort, to resolve the "which came first", so-called chicken-and-egg dilemma: why should I use bar codes if there are no scanners in place, versus why should I put scanners in place if there are no bar codes? It's the challenge of the evangelist to find those early adopters who are willing to take a chance, and also to get wider buy-in and help set standards where needed. In the case of the bar code, adoption was eased by the fact that the production cost of putting it on a product package is pretty much zero, since every product or box gets something printed on it anyway. Even today, as bar codes are used for "special" purposes such as making wrist tags for hospital patients, the cost to print that tag and wrist bracelet is pretty low. Plus, the bar code has an advantage over all-electronic tags in that the numbers that the bars represent are printed underneath, so the coding is human-readable as well. What bar codes also did, though we don't often acknowledge it, is also drive scanning technology. While the first scanners were large and crude—though effective—today's standard store scanner is usually a rugged, well-designed package of laser beam, scanning mirror assembly, and light sensor. Other scanners are in use, too, including close-in hand-held ones which use LEDs, lightweight wireless ones, ones which scan at a far distance, or which can work in harsh industrial applications. Certainly, scanning of bar codes has driven a lot of mass-market electromechanical and electrooptical design, much of then gets adopted and modified by unrelated applications. There is one aspect of bar codes which is very different from many new information and data-transfer technologies. TV, for example, required development of complex new components, circuits, systems, production techniques, and overall infrastructure for both its transmit and receive ends of the link, and these two ends are very different in almost all respects. Bar codes, in contrast, had the benefit that the technical issues of the "encoding side" were relatively simple, and most of the technical work (as distinct from the industry adoption) had to be done only on the decode side, in developing scanners coupled with low-cost computers, and with database and lookup software. Then there's RFID. Yes, in some ways, it is an alternative to the printed bar code, and has seen success in some areas where the benefits are enough to justify the cost. I'm not dismissing RFID, and it certainly has its place, but I don't think we'll be seeing an RFID tag on every pack of gum at the store for a very long time, if ever. What intrigues me about printed bar codes is how they have become so much more to us than what they were originally intended for, and how they have spurred scanner and related technologies as well. There are a lot of lessons to be learned and re-learned here for anyone with a "better" idea, by looking at how the technology was developed, adopted, and popularized. Further, it's a good reminder of the laws of unintended and unforeseen consequences, in both the markets and technologies. Can you think of any others which have similar ripples?

An advanced technical development can sometimes appear so simple, and becomes so common, that even engineers—not to mention the general public—think it just happened and was always so. So it is with the now-ubiquitous bar code, used on products and so much more—and which first saw commercial use in 1974. I thought about this because of two recent items: one is the passing of the champion of bar codes and coding, Alan Haberman a few weeks ago; you can read an interesting New York Times obituary here (free, but registration may be required); and the other was an article in The Wall Street Journal here about a hot new trend of so-called "designer" bar codes—and some of them are quite creative, despite (or may due to) the confines of the bar-code standard. The point which the obituary makes clear, and that we know but sometimes forget, is that it is not enough to just have a better idea or a working model to achieve success and market penetration. It takes a champion, an evangelist, a tireless promoter (I mean "promoter" in the positive sense, not a scam artist). Today, bar codes are used for much more than just store checkout; I am sure you can make your own list of unusual places you have seen them. Many times, it takes a lot of back and forth effort, to resolve the "which came first", so-called chicken-and-egg dilemma: why should I use bar codes if there are no scanners in place, versus why should I put scanners in place if there are no bar codes? It's the challenge of the evangelist to find those early adopters who are willing to take a chance, and also to get wider buy-in and help set standards where needed. In the case of the bar code, adoption was eased by the fact that the production cost of putting it on a product package is pretty much zero, since every product or box gets something printed on it anyway. Even today, as bar codes are used for "special" purposes such as making wrist tags for hospital patients, the cost to print that tag and wrist bracelet is pretty low. Plus, the bar code has an advantage over all-electronic tags in that the numbers that the bars represent are printed underneath, so the coding is human-readable as well. What bar codes also did, though we don't often acknowledge it, is also drive scanning technology. While the first scanners were large and crude—though effective—today's standard store scanner is usually a rugged, well-designed package of laser beam, scanning mirror assembly, and light sensor. Other scanners are in use, too, including close-in hand-held ones which use LEDs, lightweight wireless ones, ones which scan at a far distance, or which can work in harsh industrial applications. Certainly, scanning of bar codes has driven a lot of mass-market electromechanical and electrooptical design, much of then gets adopted and modified by unrelated applications. There is one aspect of bar codes which is very different from many new information and data-transfer technologies. TV, for example, required development of complex new components, circuits, systems, production techniques, and overall infrastructure for both its transmit and receive ends of the link, and these two ends are very different in almost all respects. Bar codes, in contrast, had the benefit that the technical issues of the "encoding side" were relatively simple, and most of the technical work (as distinct from the industry adoption) had to be done only on the decode side, in developing scanners coupled with low-cost computers, and with database and lookup software. Then there's RFID. Yes, in some ways, it is an alternative to the printed bar code, and has seen success in some areas where the benefits are enough to justify the cost. I'm not dismissing RFID, and it certainly has its place, but I don't think we'll be seeing an RFID tag on every pack of gum at the store for a very long time, if ever. What intrigues me about printed bar codes is how they have become so much more to us than what they were originally intended for, and how they have spurred scanner and related technologies as well. There are a lot of lessons to be learned and re-learned here for anyone with a "better" idea, by looking at how the technology was developed, adopted, and popularized. Further, it's a good reminder of the laws of unintended and unforeseen consequences, in both the markets and technologies. Can you think of any others which have similar ripples?