When was flat screen tv invented

Here's a description of the physical principles on which these devices are based and a brief overview of what would be involved in their production and operation. The slices of bread are two nanometer-thick conductive layers of indium tin oxide, a material commonly used to make transparent electrodes, such as those for the touch screen on your phone. The filling is a nm-thick piezoelectric film composed of a scandium-doped aluminum nitride, which is similarly transparent.

With lithographic techniques similar to those used to fabricate integrated circuits, we etch a pattern in the sandwich that includes a ring in the middle suspended by four slender arms. That design leaves the circular surface free to vibrate. The material making up the piezoelectric film is, of course, subject to the piezoelectric effect : When mechanically deformed, the material generates an electric voltage across it. More important here is that such materials also experience what is known as the converse piezoelectric effect—an applied voltage induces mechanical deformation.

We take advantage of that phenomenon to induce oscillations in the flexible part of the tag. To accomplish this, we use lithography to fabricate a coil on the perimeter of the tag. This coil is connected at one end to the top conductive layer and on the other end to the bottom conductive layer.

Subjecting the tag to an oscillating magnetic field creates an oscillating voltage across the piezoelectric layer, as dictated by Faraday's law of electromagnetic induction. The resulting mechanical deformation of the piezo film in turn causes the flexible parts of the tag to vibrate. This vibration will become most intense when the frequency of excitation matches the natural frequency of the tiny mechanical oscillator.

This is simple resonance, the phenomenon that allows an opera singer's voice to shatter a wine glass when the right note is hit and if the singer tries really, really hard. It's also what famously triggered the collapse of the Broughton suspension bridge near Manchester, England, in , when 74 members of the 60th Rifle Corps marched across it with their footsteps landing in time with the natural mechanical resonance of the bridge. After that incident, British soldiers were instructed to break step when they marched across bridges!

In our case, the relevant excitation is the oscillation of the magnetic field applied by a scanner, which induces the highest amplitude vibration when it matches the frequency of mechanical resonance of the flexible part of the tag. These electron micrographs show some of the tags the authors have fabricated, which can take various forms. The preferred geometry top is a circular tag containing a piezoelectric ring suspended by four beams. It includes a coil lighter shade , which connects with electrode layers on the top and bottom of the ring.

Voltages induced in this coil by an external scanner set up mechanical oscillations in the ring. In truth, the situation is more complicated than this.

The flexible portion of the tag doesn't have just one resonant frequency—it has many. It's like the membrane on a drum, which can oscillate in various ways.

The left side might go up as the right side goes down, and vice versa. Or the middle might be rising as the perimeter shifts downward. Indeed, there are all sorts of ways that the membrane of a drum deforms when it is struck.

And each of those oscillation patterns has its own resonant frequency. We designed our nanometer-scale tags to vibrate like tiny drumheads, with many possible modes of oscillation. The tags are so tiny—just a few micrometers across—that their vibrations take place at radio frequencies in the range of 80 to 90 megahertz.

At this scale, more than the geometry of the tag matters: the vagaries of manufacturing also come into play. For example, the thickness of the sandwich, which is nominally around nm, will vary slightly from place to place. The diameter or the circularity of the ring-shaped portion is also not going to be identical from sample to sample. These subtle manufacturing variations will affect the mechanical properties of the device, including its resonant frequencies.

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. Develop and improve products.

List of Partners vendors. Share Flipboard Email. Mary Bellis. Inventions Expert. Mary Bellis covered inventions and inventors for ThoughtCo for 18 years. She is known for her independent films and documentaries, including one about Alexander Graham Bell.

Updated October 24, Featured Video. Cite this Article Format. Bellis, Mary. History of Plasma Television. The Inventors Behind the Creation of Television.

Television History and the Cathode Ray Tube. Brief History of the Declaration of Independence. There we didn't. It come in you know and — it was just a different way of life, really. The popular children's show of the decade was "The Howdy Doody Show. The first color television system began broadcast in The first TV remote was introduced to consumers in One invention that failed to catch consumers' attention though, Spigel said, is the TV stove in the s.

The hybrid invention allowed housewives to watch television in the TV "window" and watch her chicken roast in the other oven window. Catering to housewives, Spigel said the networks decided to conform to their routine and planned their broadcasting as a result.

Made in West Germany, the Kuba Komet seen above was meant to fulfill all a consumer's entertainment needs. Reminscent of a sailboat in design, the Kuba Komet included both a phonograph and television tuner. The s was also a revolutionary time for the power of television in the public's consciousness. From the coverage of the Vietnam War to the Watergate scandal, TV held a magnifying glass up to what was happening in the world.

Cable networks became popular in the mid-'70s as the number of channels at a person's disposal expanded from a few to many. This expansion seen in the '70s and even today creates new opportunities, Spigel said. The Keracolor was a TV meant for the future. Though the company closed in , there were plans to release an updated model back in Spigel said, "For older generations, TV meant a box in the living room and a broadcast schedule with shows on at predictable times.

Today TV is much less defined as a material thing and a schedule. If Clive Sinclair had his way, this would have came a couple decades sooner. The Sinclair Microvision offered television on the go.

It even took the spy world by storm, featuring in the James Bond film, "Octopussy. The invention of video games and VHS tapes in the '70s became even more popular over the next two decades. Americans celebrated pop culture together through the creation of channels like MTV and witnessed national tragedies like the Challenger explosion. High definition replaced standard definition. Smart TVs offered a combination of both traditional television and the plethora of growing streaming services.

Another rising technology, Spigel said, streaming services and mobile platforms in the s have changed the way people interact with screens. A person no longer needs a TV now to watch "television. Many people believe traditional television is on its death bed, but Spigel doesn't think so.

She believes broadcast and cable television will survive by evolving with the medium.