OS News

20 Nov 1999


A New Visual Age: The Future of Monitors

By Colin Cordner


 
   
The majority of computer monitors are still based on the principle of slamming electrons into a phosphorecent screen  
CRTs get increasingly heavy and power hungry as the screen size increases, and the time required for every pixel on the screen to be energized goes up  
In response to these very prominent problems, two new technologies were introduced into the mass market some years ago  
You can probaly thank the LCD panel for half the cost of your laptop  
 

Over the last few decades, the information medium has become overwhelmingly visual in context. "A television in every room, and a computer in every home!" has become the new mantra of the post-modern consumerite. Whether, though, you're soaking up the snappy philosopical witticisims of Gilligan's Island or surfing the net for the latest super-IPO rumours, you're likely to be sitting in front of a fine example of yesteryear's technology. As shocking as it may be to the young, budding technocrats of the wired world, the majority of their ultra-swank $3000 Trinitron TVs and computer monitors are still based on the principle of slamming electrons into a phosphorecent screen. CRT technology, as it's known, uses an electron gun mounted in a vacuum tube to paint the images you see. Everytime an electron hits a sub-pixel, the phosphor is energized and emits a coloured photon, with specific colours managed by blending Red, Green, and Blue light.

If you really think about it, the mere fact that this method even works is an eternal credit to the ingenuity of engineers. On the other hand, this really is a fairly clumsy and resource hungry method of displaying images. If you doubt me, turn off your TV, turn it around, look at its profile, and check its recommended power voltage. You'll immediately notice three things: 1)Your televsion is really heavy, 2)It's really large, and 3)It uses a lot of electricity (Probably around 80 watts, depending on the screen size). The vast majority of the power, size, and weight of the device isn't coming from the circuit boards or the audio systems either; it's the result of the huge internal CRT structure. These three features have been a problem for scientists and engineers with their own various goals. CRTs are obviously lousy as a portable medium. Who, after all, wants to lug about a 40 pound laptop that consumes over 80 watts and requires a car battery to operate for more than 10 minutes? Big screens are a problem too; CRTs get increasingly heavy and power hungry as the screen size increases, and the time required for every pixel on the screen to be energized goes up. What you end up with is a large, dim screen that consumes as much power as a space heater and that takes a small army to move about.

In response to these very prominent problems, two new technologies were introduced into the mass market some years ago. One was the LCD (Liquid Crystal Display), and the other the GPD (Gas Plasma Display). The former exploits the property of semiconductive crystals to be either transparent or opaque with the presence or lack thereof of an electrical field. GPDs, on the other hand, use energized gases known as plasma, which in turn sheds light that can be used to draw an image. The low-power LCDs have boomed in areas that require thin profile, energy efficient displays, such as laptop computers, camcorders, and some desktop computing environments such as stock trading floors. GPDs have proven themselves in the realm of jumbo sized television displays, allowing for 42" screens that are as thin as an encyclopedia, and brighter than comparably sized CRT displays.

Unfortunately, both have these new techonlogies have run up against some fairly serious limitations of their own. LCDs have a small problem scaling. They tend to be very difficult to manufacture, with a low tolerence for defects, which makes it very hard to produce very large liquid-crystal displays. It also happens to make LCDs rather expensive; you can probaly thank the LCD panel for half the cost of your laptop. Plasma displays are also tricky to manufacture, and require complicated electronics. A 42" GPD television will often cost $10 000 or better for those reasons, and the price of a plasma-display HDTV would give most people a heart-attack. A few teams working for various companies are also trying to scale-down the size of GPDs for use in PDAs and cellphones, but the operation is tricky, and how cost effective this solution will prove remains to be seen.

Every indutry has a silver lining, though, and in this day and age, why should the display industry prove any different? To the rescue of consumers dreaming of ultra-thin, ultra-large, and ultra-cheap flatpanel displays ride our cavaliers, flying under the banners of such diverse companies as Xerox, Candescent, E-Ink, Lucent Technologies, and Westaim. Their aim is no less than to grab hold of the multi-billion dollar display market with new technologies they hope will supplant CRTs and LCDs forevermore. Improving On The Proven Taking the "embrace and extend" model of invention so popularized by Bill Gates and Microsoft, Candescent has chosen to reinvent CRT technology with their new ThinCRT technology. ThinCRTs use much the same principals as traditional CRTs: light is emitted by sets of coloured phosphors that are energized by the impact of an electron. The difference with Candescent's ThinCRT is the method used to deliver the electron to the pixel. Instead of using a large, bulky electron gun, ThinCRT's employ literaly millions of microscopic pyramid-shaped guns. Every phosphor has a large group of these tiny guns positioned nearby and ready to fire. No need to "aim" the guns is necessary; the tiny electron cannons are so close to the phosphors that they only have to shoot in a straight line to score an impact. Individual phosphors are lit up by regulating the flow of electricity to corresponding groups of electron cannons, rather than aiming and firing at each phosphor in sequence as with traditional CRT displays. The result of this method is a display that is as thin as an LCD, yet as bright and fast as a CRT. The entire package also takes a mere 4.5Watts of power when scaled to 14.1"; easily comparable with the active-matrix LCDs used in high-quality laptops. ThinCRTs also have another thing going for then: Cost. ThinCRTs are considerably easier to manufacture than LCDs. One good reason for this is their much higher tolerence for defects. In LCDs, defects are caused by grits of sand or other unwanted particles that stand the chance of settling on an electode, and cutting off or otherwise disrupting current to one, or an entire group of transistors. This shows up to the user as "off" pixels, which are either dark, or stuck at colours without the ability to change. Due to the way in which LCDs are wired, a few particles in the wrong place are enough to make an LCD visualy unappealing. ThinCRTs, on the other hand, have much wider electrodes that are harder to block by a single grit of dust. Even if that electrode is blocked, though, so many electon guns are positioned relative to each pixel on the screen that a ThinCRT can suffer defects to an average of 20% of its electodes and still work properly, according to Candescent. Not only does that mean fewer units being thrown out due to defects, it means less clean and less costly "clean rooms" in which to produce them. The costs to start-up a new LCD plant capable of producing 1.5 million units a year is estimated at $600 million dollars. In comparison, Candescent estimates the start-up costs of a similar ThinCRT plant to be $400 million. Solid State Solution Another technology coming down the pipe comes curtiousy of Westaim Electronic Displays Technologies (A division of Westaim Inc.). Westaim's Solid State Display (SSD) is a true departure from traditional displays. Rather than firing off electrons, an SSD uses light emitting polymers to produce light. One layer produces cyan light, the other magenta, and together they produce white light that can be filtered into colour with an RGB filter layer. Sub-pixel sized sections of the filters are energized by the intersection of two perpendicular rows of electrodes. The light travels out, meets the RGB filter, and appears Red, Green, or Blue depending on the colour of the sub-pixel it travels through. As with most display technologies, different colours are produced by mixing Red, Green, and Blue shades. SSD displays are also of a thin profile, but are brighter and refresh faster than LCD's. Another thing to note is thier wider viewing angle. LCDs are typically viewable only from narrow range of angles. SSDs, on the other hand, are viewable at wide angles due to their light being emitted near the front of the display itself. Westaim also claims that SSDs are cheaper to produce due to simpler production steps, fewer of them, and less expensive materials. One negative to note, though, SSDs consume somewhat more power than either LCDs or ThinCRTs. On the flip side, SSDs scale much better than either of the former. Solid State Displays have already been demonstrated at sizes of 17", and the team behind it currently estimate it can scale up to 50" without problems - making it ideal for large, flat panel displays for desktop computers and TVs.

Electronic Paper

Other teams in other places have been working on a different kind of display. Teams at Xerox, and at E-Ink have developed display techonolgies that could one day be as ubiquitous as paper. Both displays are flexible enough to roll up, draw less power than the average Walkman, and do away with backlighting altogether.

The Xerox team, headed by Dr. Nicholas K. Sheridon, has come up something Sheridon has dubbed "Gyricon". Gyricon is a marvelously simplistic device, and one that stands no thicker than a stack of seven sheets of paper. Where many flat panel display technologies contain 6 or more layers of often fragile materials - such as glass, and silicon - Gyricon is made up of three layers of flexible polymers in its simplist form, with an optional fourth layer of electodes. What's more, two of those layers exist only two contain the middle layer, which contains the millions of tiny, bicoloured, electicaly charged plastic spheres that are Gyricon's pixels, suspended in pockets of an oil solution.

When an electrical charge is applied to a section of a Gyricon display, these tiny sphere spin around 180 degrees and become "stuck" in the upper region of the layer - effectively turing the pixel "on". Upon applying a second charge, the sphere is released, and spins about another 180 degrees, leaving it in it's original state. Now, if you think about the preceeding two sentances for a moment, you'll realize one thing that seperates a Gyricon display from traditional LCDs and CRTs. That is, Gyricon does not require its pixels to be "refreshed" every few milliseconds; its pixels remain in a given state until they are told to do differently.

LCDs and CRTs, on the other hand, need a nearly constant flow of electricity to refresh the image on screen - even if the image doesn't change, move, or otherwise alter itself. Even if the image does change, though, its usually to render a blinking cursor, or a dancing paperclip; hardly a task worth wasting precious microwatts of electricity redrawing the entire screen. With Gyricon, the onscreen image only changes when its told to. This gives clever programmers the opportunity to target specific areas on the screen for change, and leave the rest untouched. This low power, low bandwidth approach could have big payoffs in the world of portable computing, and large displays; and those displays can be very large indeed. Xerox, in concert with 3M, have successfully printed a Gyricon display over a meter wide, and over ten meters long, and which can be curled up like a roll of wallpaper. This gives the potential for billboard sized displays, and maybe a serious challenger and replacement for the garish neon signs we've come to know and love so much.

E-Ink, in conjunction with Lucent, has taken a similar course in their developments, with thier electophoretic ink displays. While that may be a mouthfull to pronounce, the display technology is fairly eloquet.

The E-Ink display uses transparent, ink-filled capsules as its pixels. Each of these pixels contains a certain amount of positively charged coloured chips, and is sandwitched with with its brethern between two transparent layers of flexible polymers. When an electical current passes over a pixel, the negative charge of the flowing electrons pulls the coloured chips to the front of the display, effectively turing it "on". When the current flows behind the pixel, the chips are pulled back, and the pixel appears to be "off".

Like Gyricon, E-Ink's display benefits from being low power, inexpensive to manufacture, and highly flexible. E-Ink, though, has pulled ahead of Gyricon in that E-Ink's displays are already being made commercialy available. In August, E-Ink announced a deal with the J.C. Penney Corporation to produce its line of Immedia displays for the J.C. Penney chain of retail stores. Already, 6' by 8' foot animated banners can be seen hanging high from the rooves of some outlets, in sizes and a display of aerial acrobatics and flexibility that would make LCD manufacturers blush with inadequacy. An added bonus is the ability to change the display content without pulling out an extendable ladder, and changing every banner in a store. New advertisments need only be uploaded via a pager device attached to the display; a feature that is sure to be popular with employees with a well tuned sense of vertigo.

A Bright New World

With all the developments being made in the field, the display industry may come up with a few new tricks to shock and amaze couch potatoes and computer scientists both. On the one hand, you would have to wonder the effect of wall-sized, flat-panel TVs in the home will have on the increasingly sedentary cultures of the developed world. On the other, new technologies could serve to signifigantly reduce the cost of computers, and drasticly improve the dissemination of information in the coming decades as a result.

To boot, we may spare the environment a good deal of wear and tear by replacing our gas guzzling CRT displays with electron-pinching flat panels. Considering the hundreds of millions of CRTs active today in North America, replacing the with single-diget Watt flat panels could save the expense of a number of coal buring, and nuclear fission electric plants. Also, the cost of trashing large, heavy metal CRTs is an additional problem when technology inevitablely hits the landfills.

However you wish to look at it all, a new wave in big screen, flat panel, digital displays would make a big splash in the tepid waters of the display industry. If, and when these new technologies hit the mainstream, we can expect big savings in space, elctricity, dollars, and cents. The big challenge, when it does, will be resisting the added temptation to sit back, relax, and pass the potato chips.

Colin Cordner is a suspected human (of sorts) who's rarified version of reality (such as it is) has sometimes been known to coincide with our own (for the most part). On those rare occasions when it does, he is most often found at his day job at Fall's Edge, or else moonlighting at The High-Performance PC Guide.

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