- In terms of display technologies, the one thing that we are confident of is that flat panel displays will continue to grow in size, performance and popularity.
- Both plasma and LCD displays will be around for at least the next five years regardless of rumblings about OLED, SED, and others who are supposedly entering the fray. Since there have been so many advances in both plasma and LCD flat panels over the last two years it is time to see exactly where we are and attempt to pick a current winner.
Both plasma and LCD displays are coming out in larger sizes and the size gap is closing rapidly in the mainstream market. Plasma displays typically come in larger sizes, with Panasonic being the most prolific offering 37-, 42-, 50-, 58-, 65-inch and the biggest plasma at this time, a mind boggling 103-inch size (pictured).
Both plasma and LCD flat panels are fixed matrix displays that feature a thin profile and thin mullions or borders to frame the picture. Each one produces excellent pictures in their most recent iterations, but this is where the similarity stops. Plasma is an emissive display that simply means it creates and emits its own light, not unlike the venerable CRT. TFT-LCD, as used in flat panel displays, is a transmissive technology and uses white light transmitted through its layers to create the images we see.
Plasma technology is based around red, green, and blue sub pixels each filled with a gas and then each sub pixel is ignited by an electrical charge most analogous to how a florescent light works. LCD on the other hand is a flat panel with a matrix of tiny pixels with the core of each one comprised of a layer of liquid crystal material and a thin film transistor (TFT) with a capacitor in each pixel. As video information reaches the transistor, the capacitor is charged and discharged, the pixel is excited and this is how the detailed information gets to the screen. The liquid crystal modulates the amount of light passing through each pixel to provide the gray scale needed to give us the picture we see on screen.
Suffice it to say they both perform very well indeed and the following observations illustrate where we stand as of this point in time and who may have an advantage in a certain area.
Size And Price
Till recently the whole issue of size in plasma versus LCD displays would show LCD dominating in the sub 40-inch categories and plasma getting the nod in the 50-inch and larger sizes. The battle ground has been in the 37- to 50-inch range of products but as they say, "times, they are a changin'."
Both plasma and LCD displays are coming out in larger sizes and the size gap is closing rapidly in the mainstream market. Plasma displays typically come in larger sizes, with Panasonic being the most prolific offering 37-, 42-, 50-, 58-, 65-inch and the biggest plasma at this time, a mind boggling 103-inch size. As a side note, they are delivering the 103-inch display and it is not just a prototype to wonder at. Other manufacturers of plasma displays such as Samsung, Pioneer, Hitachi, and LG offer various models in 42-, 43-, 50-, 55-, 60-, and 63-inch formats.
Just as LCD have lived happily in the smaller sizes, the major plasma manufacturers were born and raised at the larger end of the spectrum and their sizes and prices reflect this. This is not to say that the LCD camp has remained in their own "little" world. Using Sharp as an example, they have large flat panel LCD displays in 32-, 37-, 42-, 45-, 46-, 52-, 57-, and the class-leading 65-inch formats. Companies like Sony, NEC, and Samsung are not far behind in the sizes they offer with various models in 32-, 40-, 46-, 52-, and 57-inch sizes.
When it comes to comparing plasma versus LCD displays, both technologies are available in sizes to meet most applications. You do have more available options when it comes to plasma displays for screen sizes greater than 50-inch at the current time and there is still a considerable price advantage in the 50" and larger sizes when comparing plasma to LCD. The current battle ground for price supremacy is in the 40-inch category with several off-brand LCD manufacturers selling their 40-inch LCD displays near the price of name brand 42-inch standard definition plasmas. The immediate aim of LCD panel manufactures is to lower the production costs further to render 50-inch LCD displays more competitive against same-sized plasma displays. Evidence of these cost savings has been seen in the rapid decline in LCD panel prices this winter. Ultimately this will shift the plasma vs. LCD size battle even further up the size scale.
As we dig a little deeper into the plasma vs. LCD comparison, we must turn our attention to resolution. Plasma displays in the 42-inch inch size come in 852 x 480 standard definition and 1024 x 768 extended definition models. Increasing the size to 50-inch plasmas and larger, we see resolution at 1366 x 768 and 1920 x 1080 addressing the HDTV standards of 720P and 1080P.
For the large flat panel LCD displays in 32-, 37-, 40-, and 46-inch sizes we typically see a resolutions of 1366 x 768 escalating to 1920 x 1080 in sizes 50 inches and above. It should be noted that some manufacturers like Samsung and Sharp have 40- and 45-inch displays respectively in the 1080 category as well.
The question at hand involves whether higher resolution by itself is always superior or even required. The answer depends on the application and the specific display under consideration. Each display is made up of the panel plus the electronics that process and drive the images on screen. A high-resolution panel by itself without correspondingly high quality in the electronics and processors will be inferior to a somewhat lower resolution display that has high quality electronic processing.
The second issue in terms of resolution is whether we really need the highest resolution panel. From a visual acuity point of view, once we are 6 feet to 8 feet from a 50-inch flat panel display, if the display is properly calibrated, it is difficult to see the resolution difference between 1366 x 768 and 1920 x 1080. There may be other reasons to go to the higher resolution model but this is a decision that relates to other factors than native resolution alone.
A comparison of picture dynamics is one of those areas that is becoming increasingly difficult to determine who is "best". The latest generation plasmas and LCD displays are both capable of producing excellent picture quality.
We first turn out attention to contrast and black levels. Plasma displays are emissive in nature and produce their own light. By their panel design, there is no light leaking between adjacent cells or pixels. This renders plasma displays capable of displaying deeper blacks and improved contrast helping to enhance those difficult-to-define quality attributes like picture depth of field, scene detail and color richness. In today's plasma displays the image can be as dark as a fraction of a candela. We are seeing manufacturers advertising contrast of some plasma displays at 10,000:1 and soon even higher.
In comparison, LCD technology is transmissive by design where light shines through the LCD layers to produce the image we see. Since the light must pass between pixels it is harder for it to achieve true blacks or absence of light, since there is some degree of light "leakage" from adjacent pixels present. In the case of some LCD displays, the darkest picture scenes can be as high as two to three candelas or higher if viewed off axis. Recently there have been huge strides in new diffusion layers for LCD displays that minimize the effect of light "leakage." Similar to plasma we have started to see LCD panels that are capable of displaying very deep blacks. Some of the latest LCD displays have a quoted contrast ratio of 4000:1.
One other variable to consider is reflectivity or the amount of reflection coming from the display surface itself. By design, there is more reflectivity in plasma displays so in high ambient light conditions or where lighting cannot be controlled, LCD displays may be less susceptible to stray reflections.
In the search for color accuracy, plasma display use rare earth phosphors to create color and brightness not unlike the CRT. On the other hand, LCD panels produce color by filtering white light through micro color filters built into the sub-pixels. The LCD transmissive method of controlling color is inherently difficult for maintaining color accuracy and vibrancy, even though most LCD displays manage quite well. The big break for LCD is the introduction of LED backlighting to replace the CCFL illumination that has been the norm. LED arrays provide much better color space and more even illumination. In general, plasma displays still have the edge when it comes to richness in color information and more natural color reproduction but the playing field is being leveled by the latest in LCD developments as we speak.
Response time of a display technology is important in several ways but the most important is the image "lag" on screen in fast moving video or graphics. LCD displays have been the main focus of this criticism. Typical plasma displays respond similar to CRTs in nanoseconds compared to the longer milliseconds for LCD. A slower response time causes the "lag" we see when viewing fast moving video on an LCD screen, but this gap between plasma and LCD is closing to the point that in the best LCD displays "lag" becomes unnoticeable. The newest versions of LCD displays are rated at 8ms or 6ms and some as fast as 3ms in their rise and fall response time. The remaining problem here is that the response time numbers can be misleading. It depends on how the manufacturer measures the rise and fall of the LCD response as to how it actually affects the fast moving images on screen. All things being equal, plasma displays still have the edge when it comes to response times.
In terms of power requirements for LCD displays versus plasma, the advantage goes to LCD. They typically require 20 to 30 percent less energy than does comparably sized plasma. It is interesting to note that it takes more energy for LCD displays to display dark scenes and for plasma displays to show bight scenes. In addition, current research in energy conservation is showing that displays that are properly calibrated will provide greater than 20 percent energy savings irrespective of the panel type you use.
One of the other obfuscations out there regards the lifetime of the display. In fact the latest plasma and LCD both will last 50,000 to 60,000 hours to half brightness. It is true that quoted half-life brightness figures tend to be somewhat exaggerated, but still; these new displays will outlast the requirements in most applications. If we do simple math, either a plasma or LCD display in use eight hours a day for five days per week for 50 weeks a year gives us 2000 hours of use a year. If we reduce the manufacturer's claim of display life in half we still get 15 years of use. The bottom line is that both plasma and LCD displays make use of extremely stable and reliable display devices. As such, panel lifetime is not an issue when it comes to comparing plasma versus LCD display technologies.
The Final Assessment
There you have the comparisons as they exist today. There are other issues to be taken into consideration such as inputs, processors, built-in tuners, and aesthetics, but both plasma and LCD flat panel displays are excellent in terms of size, resolution, picture dynamics, and panel life. All this taken into consideration, the argument comes down to which "look" one prefers. Plasma displays look "smoother" and the most like color film and CRTs. LCD displays provide a "crisper" digital look yet both are making huge strides in looking like one another. Which one to choose? My vote is for video and HDTV plasma gets the nod and for computer graphics and static images being displayed for lengths of time, LCD is the choice. Let the war of words begin!
DisplaySearch's TFT LCD Materials Report
SAN JOSE, CA-DisplaySearch has released its TFT LCD Materials Report, a comprehensive technical and market research report covering all aspects of TFT LCD materials and components. It summarizes the current status of the industry as well as provides market forecasts for 25 separate materials and components through 2009. The report is useful for anyone directly involved in the TFT LCD supply chain such as materials and component producers, TFT LCD panel manufacturers and equipment makers, as well as anyone interested in evaluating the industry from financial analysts all the way to retailers.
LCD TV panels are expected to total more than 81 million units in 2007 with the 40- to 42-inch segment growing at more than 100 percent. Components and materials are expected to contribute more than 75 percent to the cost structure of these LCD TV panels. Future technology and market trends of these and other important components and materials are expected to have a major impact on the growth of LCD TV and other LCD markets.
One of the most hotly contested debates in the display industry involves the subjects of plasma burn in and conversely image retention for LCD displays. The reality is that plasma displays are susceptible to burn-in produced by static images just like any phosphor based technology This is primarily caused after static images have been left on screen for extended periods of time (as little as 30 minutes for some models) creating an after-image or ghost which remains permanently on the screen. This typically occurs more frequently in the early life (100 to 200 hours) of a plasma display and new and improved phosphor materials as well as new burn-in reduction technologies have minimized this to a significant degree in all but the most extreme circumstances.
LCD displays do not burn-in, but can have a "retained pixel charge" which may also produce ghosting. This phenomenon is not a part of the design of the technology rather a manufacturing defect that can occur. If it does occur, there are three possibilities: the first is that you turn off the display and turn it back on and the "ghost" will disappear. The second is that the "ghost" will take several rotations of on and off to disappear. The last possibility is that the "ghost" will remain permanently on the display.
Every major manufacturer of plasma and LCD displays recommends that static images not be left on the screens for hours on end. Finally, none of the plasma and LCD flat panel manufacturers provide a full warranty against burn-in or image retention. With sensible use this debates is "much ado about nothing."
The Right Support
Installing flat panels for entertainment, information display or advertising isn't quite as simple as purchasing a few screens and placing them where there is available space. When taking on a digital signage project there are several important decisions that need to be made-and one of the most important is choosing the very best mounting solution available to achieve the ultimate screen placement.
After you choose the right screen, the mounts become the priority. At McDonald's flagship site in downtown Chicago, Peerless mounts were strategically placed at angles that are easy for customers to view the signage.
Obstacles such as windows, shelving, ceiling height, corners or columns may stand in your way of getting that just-right screen placement. Today's mounts equip you with the tools to accommodate the most unaccommodating workspaces.
When a close-to-the-wall, ultra-slim look is needed to achieve the ideal screen placement, flat and tilt wall mounts are the simplest and best way to go. Flat wall mounts hold the screen tight to the wall and the tilt wall mounts enable up to 15 degrees of angle adjustment for the perfect viewing position and reduces glare. Some tilt wall mounts include a fixed angle setting that is used to easily align all the screens within a multi-screen installation.
In a situation where the perfect placement position requires the screen to be in a corner between two adjacent walls or around the corner, pivoting and articulating wall mounts are your best choices. Pivoting wall mounts enable the screen to be turned left or right and tilted up or down. Articulating mounts offer the most versatility, providing up to 2.5 feet of extension. They can even be used in around the corner applications. Articulating wall mounts also feature tilt functionality to reduce glare and achieve the perfect screen-viewing angle.
Ceiling mounts are a great solution where wall space is limited or simply not available. They offer swivel and tilt features that allow 360-degree viewing at virtually any angle. The key to ceiling mounts is accessory availability.
Accessories such as extension columns, vibration dampeners and stabilizers, and ceiling attachments enable you attachment to various ceiling surfaces such as wood, wood beam, I-beam, truss, concrete, and Uni-strut, to mention a few.
Outdoor flat panel environmental enclosures enable screens to be installed outdoors, protecting them from dust, dirt, moisture, and humidity. They are environmentally sealed and come equipped with heating, AC units, and/or fans that maintain the ideal flat panel operating conditions. There are three options for mounting the environmental enclosure-on the wall, on the ceiling or on a pedestal attached to the ground.
With the variety of mounting solutions available today, virtually any obstacle can be overcome easily and cost effectively, giving your customer the perfect screen placement.
Night And Day
One caveat about those "fantastic" advertised contrast ratios for any display; there are no industry wide agreed upon standards in measuring or more correctly marketing contrast specifications. Where there may appear to be a significant difference in contrast between these two technologies or display types, it is difficult for the human eye to perceive any difference in contrast between an "advertised" contrast ratio of 4,000:1 versus another at 10,000:1, even in total darkness. Do not forget that the perceived level of brightness or contrast ratio depends on the ambient light in the room and there is not a perceived 2X improvement in contrast when we go from 1000:1 to 2000:1.
Keeping Screens Secure
Choosing the best screen for your application is vital, but once you've made the important decision, the end-user is going to expect those expensive pieces to be around and in good shape for a while. A main consideration must be how to protect displays from theft, vandalism, and the elements.
"We're seeing more and more plasma and LCD displays being used in various locations," said John Spangler, president, ITSEnclosures. "Left unprotected, this equipment is subject to destruction."
ITSEnclosures has worked to develop a complete product line specifically for large format displays that protects these investments and helps to extend their useful life. The Viewstation family of products, which includes the Viewstation, the Double-Sided ViewStation, and the Coverstation, together are designed to meet indoor and outdoor applications and protect displays from various forms of unwanted degradation in commercial applications.
ViewStation, the anchor product of the line, was the first enclosure of its kind on the market designed specifically to protect standard size, large format plasma or LCD displays. These standard or customized models are available to protect displays 32 inches and larger. In addition, the Viewstation offers pole, wall, ceiling, or custom mounting solutions. ViewStation is sealed, lockable, and secure, ideal for both indoor and outdoor use. These have an Anti-Reflective Window option and can be customized with a variety of thermal management options to meet the needs of the display's environment. Easily installed by two people, the ViewStation can be maintained by just one person.
ITSEnclosures also offers the Double-Sided ViewStation. Available with ceiling or custom mounting options, it contains two LCD displays and all the features of the standard ViewStation, including complete thermal management analysis.
Coverstation, the latest addition to the ViewStation family of products, offers protection for indoor displays from vandalism, splashing fluids, and "button pushers." Constructed of aluminum, the lightweight Coverstation will fit most plasma and LCD displays and offers an Anti-Reflective Window option.
TV Or Monitor?
How To Distinguish Between Commercial And Consumer Flat Panels
A disturbing trend has been developing over the last several months as flat panel displays have become almost ubiquitous and the digital signage market has been growing at such a rapid pace. We are seeing digital signage purveyors simply buying the least expensive flat panel display from any source and utilize them in their systems. After all, conventional wisdom suggests that flat panel displays are basically alike, or so it is assumed.
Contrary to popular belief, the incorporation of a flat panel display in a digital signage environment is not just a plug-and-play scenario. There are numerous design aspects to take into consideration such as, for example, internal scalers/algorithms. Commercial displays recognize all PC resolutions, including wide formats and different refresh rates (1024x768 at 60, 72, 75, 85 Hz) in addition to TV/video resolutions. Consumer displays are designed specifically for TV/video formats with very limited PC resolutions.
One important differentiator is the connector interface. Commercial displays incorporate the standard RS-232 external control/connector with PC and video loop-through connector capability, facilitating multiple display configurations from a single PC or video source. In addition, they include industrial BNC locking connectors. Consumer displays typically do not offer RS-232 external display control/connector, video loop-through capability, or multiple display configuration capability, and they do not offer BNC connectors.
From a picture dynamics point of view there is a difference between consumer and commercial displays as well. Each type of display uses a different backlight configuration for addressing grayscale. Commercial displays will produce a full grayscale with good linear color tracking from black to white, showing all 256 different levels of luminance (brightness.) This is necessary for the diversity of PC applications. For consumer televisions, grayscale is skewed for more of the bright white end of the scale relative to the narrow broadcast standards that they must meet.
There are a few other issues to consider. First of all, commercial displays are designed to operate in both landscape and portrait modes. In terms of mounting capabilities, commercial displays typically utilize VESA compliant standard mounting connections to complement standard industry mounting devices. This makes for easier installations and less unique inventory to carry. Consumer displays typically need special mounting brackets and sometimes cannot use third-party mounts.
Last but not least, we have the issue of public display security features.