VIDEO TECHNOLOGY: for large-venue applications
Jan 1, 2000 12:00 PM, Josh Kairoff
Such large venues as arenas and stadiums pose unique and demandingrequirements on large image display equipment. Most of the events depictedare fast moving, colorful and have lots of detail, and it is difficult tomake this kind of material look good, considering ambient light levels aregenerally high, and the distance, positions and viewing angle of theaudience often conflict with the capabilities of many display technologies.On the facilities side, the need for acceptable purchase and maintenancecosts, good manufacturer support, high reliability, flexibility and imagequality are of paramount importance. With most major capitol expensesexpected to be in use for at least five years, there has been little desireto take a chance on new and unproven technologies. Additionally, all of theequipment in most arenas and public venues needs to be flexible enough towork well with whatever event happens to be in the facility.
A bit of image history
In the past, content and applications of that content were limited byinferior display technologies. Animated lights, fireworks, mechanical flipboards and all sorts of attention-grabbing visuals were used to keep theentertainment level of events as high as possible. Professionals in thosedays resorted to keeping images simple by using film, transparencies andprint for large images. All the material had to be pre-produced for eachevent, making changes labor intensive and extremely difficult. Real-timeimage processing meant having a spare lamp or paint can always available.Meanwhile, people were getting bigger, nicer televisions at home, and theydemanded comparable visual experiences when they went out. Being mindful ofthe entertainment competition from the family television, facilitiesmanagers and event promoters were constantly looking for ways to stayahead. There were, however, no practical methods to display large-format,high-quality electronic moving video or video-like images.
Identifying the need to provide more advanced visuals, manufacturers ofestablished electronic signage began to improve their technologies. Lightbulb displays became more complex and versatile. Light signs in both monoand multicolor began to be able to show rudimentary graphics, images and,in some, cases "spud" video. The idea of using a center-hung scoreboard forsomething other than scores began to take hold.
The tide really turned in 1985 when Sony and Mitsubishi took a new approachand used a matrix of small CRT displays instead of light bulbs. Sony'sJumbotron and Mitsubishi's DiamondVision were both able to produce imageswith a superior image quality and light output. These technologies set anew benchmark for large screen video displays. They fit perfectly in thecenter scoreboard and could be installed on all four sides. Facilitiesquickly realized the benefits of electronic image display. People in theback row could see the performers; everyone in the arena could see thereplays. The entertainment experience was enhanced for everyone, no matterwhere they sat. With a starting price of close to $1 million and the costof high maintenance needs, however, only a small number of facilitiesinstalled them. The market needed a display technology with similar qualityand features at a manageable cost.
The videowall concept
Some time earlier, the technology for videowalls was introduced as a uniquemultimedia display technology. Video-walls began as multimedia displaydevices at tradeshows, retail stores and large events. Eventually,advancements in display and processing technology improved the large imagereproduction capabilities of videowalls, and this led to their use as alower cost alternative to Jumbotron-type devices.
In its most basic form, a videowall is an array of individual displaysarranged to create a large video screen. On it, a variety of sources can bedisplayed to resemble one large image or a mixture of smaller images andcolors. Although there are both rear-projection cube and CRT monitorvideowalls, almost all of the large image applications are done with cubes.The space between CRT monitors (mullions) are usually too big for anacceptable large image, unless there are a large number of monitors and theimage is viewed from a greater distance away.
Among the unique features videowalls offer are the ability to increasesize, brightness and potential resolution without increasing depth. Tochange image size, all you need to do is change the number of matrixeddisplays instead of changing lens or throw distances. This capability,along with the minimizing of mullion size, was the solution to manyapplications problems, ultimately leading to widespread use of videowallsin many different environments. Although videowalls are still in widespreaduse, it was not until the development of DSP technology that the newtechnologies entered the scene, specifically plasma display panels and LEDlight signs.
LEDs: An accident waiting to happen
In electronic terms, a diode is an electronic component through whichcurrent can flow in only one direction. When the diode is manufactured in aspecial way, some of the energy going through it is converted to visiblelight. LEDs are efficient light sources and, thus, are often used asindicator lights. They are also good for displays because they arerelatively small and inexpensive, and they have a lifetime of more than50,000 hours. Unlike incandescent light sources, LEDs do not suffer fromthe light smear problems of thermal inertia.
LEDs have found their way into an ever-increasing variety of products.Because of their wide base of application, there has been significantdevelopment and improvement on their color quality and light output. LEDsigns became viable with the introduction of Super-bright LED's andadvancement in image processing technology.
Currently LED displays have become the preferred technology for large videodisplays in high ambient light levels. Although the image quality is not asgood as the videowall, many clients can overlook this for such benefits asthe ability of some LED displays to be used in direct sunlight.
The rise of plasma
Large-screen plasma displays (PDPs) are ultra-slim, extremely light inweight, and will hang flat on a wall. PDPs use pulse width modulation (PWM)to make the perception of intensity, and because they are completelydigital displays, they are compatible with video computer, and HDTV feeds.Although a completely digital display is not as important in a largelyanalog world, every indication is that our world will soon evolve into onethat relies upon digital distribution. When the entire process is digitalfrom capture to display, analog components will become the weakest link.
In operation, the electronics of the PDP produce controlled pulses ofenergy, causing an inert gas to convert to plasma. Upon conversion,ultraviolet light is produced and is then channeled in the direction ofred, green and blue phosphor, which then glows, producing visible light.PDPs have an effective visual field angle of more than 160 degree bothhorizontally and vertically, making them ideal for the wide imagesnecessary at distance, and because PDPs are free from magneticinterference, they are not affected by magnetic fields from loudspeakers.
Another great feature of PDPs is their ability to provide accurate imagesbecause of their flat panel screen. The information displayed is alwaysaligned and distortion-free all the way to the corners of the screen. Thereis no setup of convergence and nothing to fall out of alignment. There areno projection throw distance limitations because the image is notprojected, and the high ambient light tolerance of PDPs make them suitablefor many daylight applications.
Advertising vs. entertainment
An important thing to consider in sports venues and other public areas isthe trend to mix advertising with entertainment and information. Whiletelevision newspapers and radio have always used commercials to producerevenue, the idea of selling brand presence in public gathering places hasmostly been limited to static signage. Now that we have the technology andability to have electronic signage, the game of being paid to show thingsto people is changing fast. Soon, the same power of the Internet will allowmanagement and control of images and information.
With displays producing revenue, facilities managers will be looking toincrease the quantity of displays. Many of these new displays will need tobe flexible enough to be retrofitted into existing areas. The demand forthis ability will require that facilities install display technology thatcomplements electronic signage.
Videowalls and direct-view CRTs are far from obsolete. They are simply nolonger the only technology available to show electronic images in largevenues. When size and viewing angles are not as important as cost,direct-view CRTs are still viable. When environmental limitations can becontrolled, and high video image quality is demanded, videowall systems maybe the preferred medium. For the highest amount of light output, LEDdisplays are it. For high-tech versatile minimal depth distortion-freedisplays, PDPs are a good choice.
The benefit of all this development is an overall increase in displayoptions. The biggest problem, however, is that all of these options requireunderstanding. As always, focusing on understanding and fulfilling theneeds of a client and not just on a particular technology is the key to asuccessful installation. The question is not how; it is which one. Theanswer lies in finding the appropriate technology that satisfies a balanceof price, reliability, features, image quality, environment andcapabilities.