However, despite their similarities, how they produce and display images is quite different. Plasma TV technology is based loosely on the fluorescent light bulb. Plasma TVs can be made thin. However, even though the need for the bulky picture tube and electron beam scanning of those older CRT TVs is not required, Plasma TVs still employ burning phosphors to generate an image. LCD TVs use a different technology than plasma to display images. There is no radiation emitted from the screen.
Although it was possible to incorporate 4K resolution display capability into a Plasma TV, it was prohibitively expensive. Plasma has a distinguished place in TV history as the technology that popularized the flat panel, hang-on-the-wall TV.
Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance.
Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. The move is a death knell for plasma, and a blow to the once dominant Japanese television industry as giants like Sony, Sharp and Pioneer increasingly cede the leader board in worldwide sales to Korean brands like Samsung and LG, as well as manufacturers in China and Taiwan.
Technology The Ode: The plasma television The best doesn't always win. Photo: courtesy Panasonic. Joseph Communications uses cookies for personalization, to customize its online advertisements, and for other purposes. Learn more or change your cookie preferences. In addition, at this scale the materials used to make the device are not perfectly homogeneous.
In particular, in the piezoelectric layer there are intrinsic variations in the crystal structure. Because of the ample amount of scandium doping, conical clusters of cubic crystals form randomly within the matrix of hexagonal crystals that make up the aluminum nitride grains.
The random positioning of those tiny cones creates significant differences in the resonances that arise in seemingly identical tags.
Random variations like these can give rise to troublesome defects in the manufacture of some microelectronic devices. Here, though, random variation is not a bug—it's a feature! It allows each tag that is fabricated to serve as a unique marker. That is, while the resonances exhibited by a tag are controlled in a general way by its geometry, the exact frequencies, amplitudes, and sharpness of each of its resonances are the result of random variations.
That makes each of these items unique and prevents a tag from being cloned, counterfeited, or otherwise manufactured in a way that would reproduce all the properties of the resonances seen in the original. For discretely labeling something like a batch of medicine to document its provenance and prove its authenticity, it's just what the doctor ordered.
You might be wondering at this point how we can detect and characterize the unique characteristics of the oscillations taking place within these tiny tags. One way, in principle, would be to put the device under a vibrometer microscope and look at it move.
While that's possible—and we've done it in the course of our laboratory studies—this strategy wouldn't be practical or effective in commercial applications. But it turns out that measuring the resonances of these tags isn't at all difficult. That's because the electronic scanner that excites vibrations in the tag has to supply the energy that maintains those vibrations.
And it's straightforward for the electronic scanner to determine the frequencies at which energy is being sapped in this way. The authors directly measured the surface topography of a tag using a digital holographic microscope, which is able to scan reflective surfaces and precisely measure their heights top.
The authors also modeled various modes of oscillation of the flexible parts of such a tag bottom. Each mode has a characteristic resonant frequency, which varies with both the geometry of the tag and its physical composition.
University of Florida; Bottom: James Provost. The scanner we are using at the moment is just a standard piece of electronic test equipment called a network analyzer. The word network here refers to the network of electrical components—resistors, and capacitors, and inductors—in the circuit being tested, not to a computer network like the Internet.
The sensor we attach to the network analyzer is just a tiny coil, which is positioned within a couple of millimeters of the tag. With this gear, we can readily measure the unique resonances of an individual tag. We record that signature by measuring how much the various resonant-frequency peaks are offset from those of an ideal tag of the relevant geometry.
We translate each of those frequency offsets into a binary number and string all those bits together to construct a digital signature unique to each tag. The scheme that we are currently using produces bit-long identifiers, which means that more than 2 billion different binary signatures are possible—enough to uniquely tag just about any product you can think of that might need to be authenticated.
Relying on subtle physical properties of a tag to define its unique signature prevents cloning but it does raise a different concern: Those properties could change. For example, in a humid environment, a tag might adsorb some moisture from the air, which would change the properties of its resonances. That possibility is easy enough to protect against by covering the tag with a thin protective layer, say of some transparent polymer, which can be done without interfering with the tag's vibrations.
But we also need to recognize that the frequencies of its resonances will vary as the tag changes temperature. We can get around that complication, though. Instead of characterizing a tag according to the absolute frequency of its oscillation modes, we instead measure the relationships between the frequencies of different resonances, which all shift in frequency by similar relative amounts when the temperature of the tag changes.
This procedure ensures that the measured characteristics will translate to the same bit number, whether the tag is hot or cold. A tag is characterized by the differences between its measured resonant frequencies dips in red line and the corresponding frequencies for an ideal tag dips in black line.
These differences are encoded as short binary strings, padded to a standard length, with one bit signifying whether the frequency offset of positive or negative right. Concatenated, these strings provide a unique digital fingerprint for the tag bottom University of Florida.
The RF network analyzer we're using as a scanner is a pricey piece of equipment, and the tiny coil sensor attached to it needs to be placed right up against the tag. While in some applications the location of the tag on the product could be standardized say, for authenticating credit cards , in other situations the person scanning a product might have no idea where on the item the tag is positioned.
So we are working now to create a smaller, cheaper scanning unit, one with a sensor that doesn't have to be positioned right on top of the tag. We are also exploring the feasibility of modifying the resonances of a tag after it is fabricated. That possibility arises from a bit of serendipity in our research.
You see, the material we chose for the piezoelectric layer in our tags is kind of unusual. Piezoelectric devices, like some of the filters in our cellphones, are commonly made from aluminum nitride. But the material we adopted includes large amounts of scandium dopant, which enhances its piezoelectric properties.
Unknown to us when we decided to use this more exotic formulation was a second quality it imparts: It makes the material into a ferroelectric , meaning that it can be electrically polarized by applying a voltage to it, and that polarization remains even after the applied voltage is removed. That's relevant to our application, because the polarization of the material influences its electrical and mechanical properties.
Imparting a particular polarization pattern on a tag, which could be done after it is manufactured, would alter the frequencies of its resonances and their relative amplitudes. But the applications of the tiny tags we've been working on will surely be of interest to many other types of companies as well. Even governments might one day adopt nanomechanical tags to authenticate paper money.
Just how broadly useful these tags will be depends, of course, on how successful we are in engineering a handheld scanner—which might even be a simple add-on for a smartphone—and whether our surmise is correct that these tags can be customized after manufacture. But we are certainly excited to be exploring all these possibilities as we take our first tentative steps toward commercialization of a technology that might one day help to stymie the world's most widespread form of criminal activity.
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Flat-screen TVs were a sci-fi staple until Fujitsu made them real.
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