HDTV Displays: A Crystal-Clear Future?
By David C. Michaels
Society is always hungry for something better. In attempting to satisfy this hunger, millions of dollars are constantly being devoted to developing better forms of entertainment and communication. Probably the most important factor in all this is the process of replacing analog technology with digital technology. In an age where this technology is growing at such a rapid rate, it is of no surprise that the television sets that have been entertaining us for years would eventually become outdated. Many countries are currently in the process of converting from regular NTSC standard television to High Definition Television (HDTV), but the adoption so far has been flooded with setbacks, hype, disagreements, and all sorts of problems. Creating standards and agreeing on terms may take more time than expected.
The focus of this report is on the visual displays of HDTV and how this new technology works. A brief history of television should be discussed in order to fully understand where HDTV came from, and where it is going. When simple televisions were first introduced to the world in the early 1940's, they were available only in black and white basic formats. The actual set consisted of a primitive picture tube that had a display of 525 lines per frame (scanning 30 lines per second). It wasn't until the end of World War 2 that color TV emerged and helped take television to another level, establishing television as the number one communications media. Technology continued to evolve and a standard for the television screen display was established. Although the actual sizes and shapes of TV's and their screens would change over the years, the basic fundamental technology behind them stayed the same. In time, computers eventually became an intricate part of our society and one trait that they developed was their superior quality display screens. Advanced Television (ATV) ,which is a general term for any system that results in "improved television audio and video quality", was eventually developed and had no set standards. It was a step up from normal television technology and introduced displays of superior quality that varied in pixel count and frame rates. Soon to follow this was the concept of DTV (digital television), which involved the development of HDTV.
HDTV has been under constant development in the U.S. and Europe, but was first introduced in Japan by Dr. Fujio and his staff in the 1970's, at the NHK Research Laboratories. This new form of TV was designed for the basic purpose of creating a better entertainment experience for peoples' homes. HDTV delivers a better picture and sound through digital compression of signals rather than analog signals. For sound, it creates an astounding audio experience by implementing CD-like sound through multiple channels of digital surround sound. The compression scheme used for the picture display is MPEG-2 and it involves increasing pixel count at a higher scanning rate. HDTV can transmit programs at a 1080 x 1920 progressive scan (at 24 frames per second) and have the resolution of about two to four times that of normal TV in both the horizontal and vertical aspects. With a picture ratio of 16:9, compared to a current TV picture ratio of 4:3, this results in a display screen that is much wider than today's TV screen along with being of better quality than most of today's computer displays.
Interlaced scanning is used to create an outstanding, crystal-clear display. Interlaced scanning is when a compressed signal first "paints" the odd lines of an image onto the screen, and then "fills" in the even lines to create a full-imaged display. The actual picture that is viewed has no static, no annoying lines across the screen, resolution comparable to 35mm film, and dimensions like wide-screen movie theater screens. Apart from screen shape, most casual viewers can't see much difference between today's TV and forms of DTV with 19 or 25 inch screens, but the difference becomes very noticeable with 35 inch or larger screens. In addition, the ability to display small text legibly on DTV screens far surpasses that of normal TV sets today; and this is crucial to the possible convergence of digital TV with personal computers and the Internet.
With a television display, on-screen images are created with invisible electrons rapidly scanning across a phosphorescent screen. As noted earlier, displays used in HDTV have much more scanning lines than ordinary television. The digital HDTV signals are also sent, received, and implemented much faster than average TV sets. Using the high-quality capabilities of fiber optics, live broadcast images can be seen clearer than ever and in "real time" because of this instantaneous transferal of digital information.
Many breakthroughs have been made in the transfer of this "digital data" to what you actually see on the display screen as a picture, one such breakthrough is the use of "FELICITA". The development of "Ferroelectric Liquid-Crystal Devices for IT Applications" (FELICITA) started in 1989 in Europe. The objective of FELICITA was to develop liquid crystal technology to be used to create better displays, and for these display screens to be produced for the European market. Ferroelectric liquid crystals combine the advantages of liquid crystals (commonly known in terms of LCD displays used in watches, clocks, etc.) with the abilities of high-speed "switching". The combination results in the capability of high-definition displays operating at video frame rates. After much experimentation, a final project was created that had the ability to perform a 150mm diagonal 320 x 240 pixel color display and a 300 dots per inch shutter array. This experiment ensured that high-quality products could be developed and work well using this technology.
The current problem that has arisen with the on-going development of HDTV is the ability to create a feasible display screen that can handle this transfer of "near-perfect" information. Japan has been hard at work coming up with solutions and they feel that an economically thin display, in the 50-inch range, must be developed in order for the future of HDTV to prosper. Currently, the only feasible options seem to be either direct-view-panels, such as plasma display panels (PDP), or active matrix liquid crystal display (AMCLD) panels. Both these technologies represent different ways of translating digital information into an actual image on a screen. Efforts are being made to develop both, but larger AMLCD panels have been found to be more costly whereas PDP's appear to be less costly- but sacrifice in brightness, contrast, and uniformity. Only AMLCD panels, also referred to as "projectors", seem to have the cost and abilities more suitable for consumer HDTV displays.
For large screen displays, the use of cathode-ray tube projectors is another technology that is being researched and experimented with. However, the AMLCD light-valve projector is a variation that is surpassing the cathode-ray tube projector in terms of meeting cost and performance goals. AMLCD panels are primarily being developed for computer displays, but uses for HDTV displays are also being developed because of how closely related HDTV and computers are.
Compared to the PDP displays that I mentioned, these smaller AMLCD displays have been found to be cheaper and easier to produce. To produce color; PDP's need three times as many addressable sub-pixels as there are pixels in the image. AMLCD projectors use three small panels, but need only one addressable pixel per displayed pixel in each panel....sound confusing?...it is... As a result of all this, the requirements for high resolution displays are much less severe for types of AMLCD projectors, rather than for PDP direct-view color panels. Thinking long-term, producers of HDTV display equipment would like to use these technologies to develop a large, cost-effective, "hang-on-the-wall" panel (TV screen) that promises superior picture. So far AMLCD projectors have proven to be the most efficient.
Using these and other technologies, one company that has devoted a lot of its resources to developing HDTV displays is SHARP. On October 25, 1996 Japan's SHARP Corporation released a new 32-inch HDTV multi-scan Deflection System for a price of 450,000 yen (translation to U.S. currency was unavailable). This product has the ability to reproduce high-definition broadcasts, as well as regular broadcasts, satellite broadcasts, and even computer-generated images- all with outstanding clarity. The product uses the discussed digital technologies and scans at 33.75 kHz for HDTV signals, 15.75 kHz for standard NTSC broadcasts, and 31.5 kHz for personal computers. The use of ultra-fine "mask pitch" and high-contrast glass delivers a picture and allows viewers to see full-motion video reproduced with near-perfect clarity. In addition, it also has a "news function" that allows the viewer to call up information about news and forecasts, even while watching regular programming. Amongst other features, it has connection abilities that allow Internet or CD-ROM messages to be viewed and an automatic "brightness sensor" that adjusts the screen's brightness to match the lighting in the room, making viewing easier on the eyes.
Other manufacturers are also jumping on the HDTV bandwagon. MITSUBISHI says it will introduce at least three models in its 1080 HDTV series in late 1998, all of them being rear-projection sets accommodating the wide-screen 16:9 ratio with screens between 55 and 73 inches. ZENITH also plans to introduce a large-screen digital set, as well as set-top converters capable of receiving digital signals (discussed below). TOSHIBA, RCA/GE, and SONY all plan on introducing ground-breaking, high-definition products- but are keeping lids on the details of their plans.
As far as the marketing of HDTV goes, some problems have arisen. With the upcoming arrival of digital broadcasting, people are wondering if their current sets will be able to carry the new digital signals. Adaptability with current television sets, and if current sets will become obsolete altogether, have become questions that people are starting to ask. All of the current television sets (estimated 250,000,000 in use throughout the U.S. today) will work forever with everything but the new digital broadcast. For broadcast signals, they will work until 2006 and then converters will be made available. These converters will be priced between $100 to $200 and will be the only way to watch broadcast television stations (not cable or satellite) with normal television sets.
HDTV sets have already been licensed in the U.S., but according to one source they will be formally introduced to the market in 1998. The cost will average about $5,000, but can fall anywhere from $2,000 to $20,000. Like past "breakthrough" media systems, the price is expected to lower as production and demand increases. By 2001, manufacturers say sets will cost about $400 to $550 more than a comparable high-end set today.
Another aspect to the development of HDTV is its association with the computer industry. Currently, you can't plug your TV into your personal computer (PC) without depending on extra converting equipment. Yet, the interchangability of these two media tools is considered crucial to many developers of HDTV. Broadcasters, manufacturers, and the PC industries have been involved in the battle over display standards for quite some time. The answers will determine if, and how, the convergence will occur. It is estimated that in about three years there will be total interchangeability between HDTV sets and PC monitors.
This new union of communication technologies is possible due to the fact that HDTV sets are more like computer monitors because of their use of digital compression. The result is a higher-resolution image display, much more than NTSC standard sets. Some of these products are already being made available to the public with an average price of about $350. SONY, for example, has already released its new 24-inch diagonal Trinitron monitor, which has a 16:9 aspect ratio and is capable of HDTV resolution. Other products, such as the Radius Thunder 30/1920 can also produce this kind of resolution in the Windows program. Even though convergence seems to be the theme with many forms of communication these days, some people feel this type of union isn't very necessary. They people claim that televisions and personal computers have two separate roles; TV is used as a passive form of entertainment for individuals or groups, while computers involve a form of interactive work on more of a personal basis.
As far as television goes, what does the switch from analog to digital mean to broadcast stations? The Federal Communications Commission (FCC) initially gave broadcasters a period of nine years in which they have to convert completely to the high definition format. This ultimatum has been altered in many ways, but the goal has remained the same. During this transition, HDTV will face competition with direct broadcast satellite television and other emerging digital video display (DVD) systems. The FCC has also decided to give analog television stations separate frequencies for HDTV broadcasts, mostly in the UHF band (channels 14-69). This move was challenged by some members of the Congress who wanted the FCC to auction off the HDTV bands for large sums of money (going along with Clinton's plan to balance the budget by 2004). In the end, Congress, which relies on broadcasters for air time during political campaigns, accepted broadcasters' claims that they shouldn't have to pay.
Because HDTV has the potential to be very costly to both broadcaster and audience, there is some fear that the promises of HDTV won't live up to what they're supposed to. In the current "battle over bandwidth", an option that is in competition with HDTV is SDTV (Standard Definition Television). SDTV incorporates multicasting, the offering of more than one program per channel, along with a better picture. The picture is actually of the same resolution as plain analog TV, but without the interference that distort a picture during transmission. SDTV, in many ways, is most comparable with digital TV delivered by direct-broadcast satellites. Compared to HDTV's scanning capabilities of 1080 x 1920, SDTV's are only 480 x 704. Ultimately, the difference in display depends on how critical the viewer is. But even more important is the fact that SDTV gives TV stations the ability to transmit four to six signals through a single digital channel. This gives broadcasters more channels with which to attract an audience.
Some people argue that the market majority isn't so wrapped up in having a perfect picture, but instead would be satisfied with a decent picture in addition to having more viewing choices. That is what you get with SDTV: multicasting with truly studio-quality analog picture without any static or lines. Defenders of HDTV claim that, with multicasting, the focus of high-definition research will be misdirected. The ability to create a perfect visual and audio television experience was, and is, the original goal of HDTV. The extra program choices will eventually become available from the different broadcasters, satellites, and cable providers- but as far as technology is concerned, people will demand the highest quality picture and sound sooner or later. The technology is available as we speak, so why don't we use it?
Networks are finding themselves having to choose between these options for their future broadcasting plans. The big networks are becoming more open to multicasting with SDTV because they are uncertain that HDTV will deliver the revenue needed to compensate the money put into it. Many stations are preparing to compromise, for example, by airing multiplexed programs during the day and airing high-definition prime time during the night. Electronic manufacturers have been developing sets that can handle both multicasting SDTV and HDTV, but most are hoping that broadcasters will go for HDTV because of the higher product sales that would result. Ultimately, the popularity of either HDTV or SDTV lies in the hands of each TV station having to choose between dividing up their bandwidth into four to six digital channels in improved-yet-not-quite-high-definition quality (SDTV), or to transmit one channel of wide-screen, high-resolution HDTV with intense CD-like sound.
HDTV is a communication technology that is developing even as we speak, but as a whole has not been introduced to the mass market. The products will be available before you know it, and the major TV stations are currently preparing for the transition from analog to digital television. The FCC has begun issuing digital broadcasting licenses to existing TV stations, who in turn have begun to order millions of dollars worth of new equipment needed to send those signals along their way. Digital television stations will be in full operation in most major cities in time for Christmas 1998. Stations in the 30 largest TV markets are set to begin digital transmission by Christmas 1999. Real, full-scale DTV broadcasting is likely to begin shortly after November 1, 1998 and the end of today's NTSC broadcasting will possibly be as early as 2006.
During this transition, consumers will have to make some basic decisions on which products to buy. If you buy a converter box, you're out about $150, but your current television screen will display a picture that'll look better than you ever thought it could. Your other option will be to buy a HDTV, and experience a widescreen digital picture that is more than four times better than your current set, along with CD-quality Dolby Digital sound and PC compatible capabilities. The choices will be many, but in the end, we are promised superior-quality displays and incredible entertainment experiences.
Bibliography
Sources and text:
Entertainment@Home Vol. 1, No.5 "DTV: The Future is Clear..." pp. 42-47. Summer 1997.
Grant, August E., Communication Technology Update - 5th edition. "High Definition and Advanced Television" pp. 101-112.
Web-sites:
http://albion.ncl.ac.uk/esp-syn/text/2360.html
http://webstar.com/hdtv/hdtvnews1.html
http://www.broadcastingcable.com/
http://www.computer-design.com/Editorial/1997/02/Departments/297swnews2.html
http://www.sharp.co.jp/sc/gaiyou/news-e/
http://www.zdnet.com/products/content/cshp/1706/cshp0104.html