The past year has seen a quantum leap in the evolution of the digital signage market. To paraphrase an old TV ad, "We've come a long way, baby" in growing the industry.
From a growing and often times disjointed "buzz" in the industry over the last couple of years it is now a recognized market mover, albeit still in its infancy. As with all infants it has and will continue to have growing pains in numerous areas for the foreseeable future. The most common questions about digital signage range from the viability of the various business models to the integration of various software packages that will provide a real solution to the end user.
With all of these and numerous other issues to consider, there is one area that we can shed some light and provide specific help in your decision making process. Let's take a close look at display technologies that are most appropriate in digital signage applications.
In the digital signage arena it is important to understand and clearly differentiate one display technology from another. Of course each type of technology will render a picture or image but the characteristics of the display i.e. the quality and size of the image, the networkability as well as the serviceability and last but not least the total cost of ownership must be taken into consideration. In the end we have the responsibility to properly address the application, taking into consideration all the parameters mentioned above and match the "best" display type to that application.
The most common digital signage display technologies in use today are plasma and LCD flat panel displays, DLP Cubes, and LED or light emitting diodes. Let's examine each one for their proper applications and limitations. In terms of image quality, 35MM film is the "holy grail" of moving pictures. People need a common point of reference to understand high quality and for over 100 years the picture on the big screen is still revered as the "best."
Second only to film in terms of the ultimate video quality is the CRT. While there are some CRT monitor/television based digital signage installations out there, these are rapidly being replaced by the various flat panel technologies. The reason for the decline of the CRT is fundamental to the design of the technology.
They are for the most part large and bulky displays that are not particularly bright and the rapidly decay in image quality in continuous 24/7/365 use.
Next in the line of succession in "picture" quality is the plasma display because it most closely replicates the rich appearance of the film and CRT experience and should be used in applications requiring this type of picture impact. Being a digital technology, plasma displays can also be used to show continuously moving computer generated images with text and computer aided design in a larger and more viewable format. Plasma displays come in numerous sizes but typically in 42-inch and 50/55-inch versions for digital signage at resolutions of 852x480 at the entry level and going up to 1366x768 on the larger sized displays. Recently larger plasma displays have entered the market with 61-, 63-, 70- and soon an 80- inch version available in late 2005.
Significant improvements have been made in plasma display technology in terms of brightness, contrast, networkability, and cost of ownership. The bottom line is that if you use mostly full motion wide screen video or continuously moving computer text and graphics then consider plasma in your digital signage applications.
LCD, THE VIABLE ALTERNATIVE
Although by most accounts, still not as "film like" in terms of picture quality as plasma, LCD represents a viable alternative to other technologies and provides a "digital look" that some prefer to plasma. In comparison most LCD advocates will state the crisp/sharp images on an LCD versus the soft/filmlike images of plasma. Inherent in the design of LCD panels is the ability to display text with the most clarity and definition of any of the most commonly available display technologies today.
This makes it ideal for status displays and digital signage requiring static images. LCD displays are getting larger, currently coming in 30-, 32-, 37-, 40- and 46-inch diagonal sizes with a 55- and even a 65-inch in 2005! Like plasma, LCD technology has seen many improvements over the last 2 years, the most notable of which is improved contrast and the availability of faster panels below 16 milliseconds response time permitting a much improved video picture.
The bottom line is that if you use mostly static text and graphics with some full motion video in any application and especially 24/7/365 then utilize large panel LCD. There are some design caveats to consider in both LCD and plasma when making your final selection. In consideration of which technology to use be aware that several plasma and LCD manufacturers are incorporating what is known as an "open architecture" design.
This permits modules to be changed out in the connectivity panel of the display facilitating the integration into a total digital signage system.
With plasma, you are typically limited in most models to performance at altitudes of 6,000 ft. or below. In addition, if an image on the screen remains static or not in motion for extended lengths of time, the plasma technology may "burn in" and retain the static image on the screen. Most manufacturers provide anti burn technologies to reduce this effect but it is still a factor to consider. There is a new technology in the plasma arena called Zero Burn that claims to eliminate the burn-in effect so stay tuned for more information as this comes to market in late 2005. Last but not least is the life of the panel. In previous versions of plasma technology the life cycle of the panel was in question.
Most plasma displays had a "claimed" lifetime of 30,000 hours if properly setup but new panels from manufacturers like Samsung, Pioneer, Panasonic, Hitachi, and LG are now providing 50,000-hour panel life estimates. The life of the panels must be taken into consideration in the life cycle cost of the system.
With LCD displays, the panel size limitations are currently 40 inches and 46 inches diagonal with a few larger sizes available by late 2005. LCD displays also have an advantage in higher altitude applications and may be acceptable for lower temperature environments in outdoor projects. Be aware that although many LCD manufacturers have improved their panel response times, some displays still have a slower response time and may not provide the most dynamic replication of video signals.
Last but not least, LCD flat panel displays are about twice as expensive in size for size comparisons with plasma displays but last about 60,000 hours at which time the lamp in the display can be replaced making life cycle cost an advantage.
A GROWING CATEGORY
A growing category of displays is the rear screen "cube" design with LCD or more recently DLP chips providing the imaging engine. The new designs typically come in 50-inch and 61-inch configurations with customized designs up to 84 inches or even 100 inches diagonal. The newest designs come in what is called a thin profile configuration and a 61-inch display is <20 inches deep.
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