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A COMPARISON OF VIDEO WALL TECHNOLOGIES

A COMPARISON OF VIDEO WALL TECHNOLOGIES 31
VISUAL INTELLIGENCE FOR CRITICAL DECISIONS A CineMassive Technical White Paper A COMPARISON OF VIDEO WALL TECHNOLOGIES A Guide to Key Fea tures and Benefits Issued April 2015 Release 1.0 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Table of Contents Abstract 4 Introduction 5 Why A Video Wall 5 Choosing a Video Wall Display 5 LCD Video Walls 6 How It Works 6 Characteristics and Performance 7 Visual Performance 7 Spatial, Environmental, and Aesthetic Concerns 8 Ease of Deployment 9 Reliability and Resilience 9 Cost of Ownership 10 Plasma Display Panel Video Walls 10 How It Works 10 A Technology in Decline 10 Projection Cube Video Walls 11 How It Works 11 Characteristics and Performance 12 Visual Performance 12 Spatial, Environmental, and Aesthetic Concerns 13 Ease of Deployment 13 Reliability and Resilience 14 Cost of Ownership 14 Blended Projection Video Walls 15 How It Works 15 Characteristics and Performance 17 Visual Performance 17 Spatial, Environmental, and Aesthetic Concerns 18 Ease of Deployment 19 Reliability and Resilience 19 Cost of Ownership 20 PAGE 2 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, A CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANT TLANTA, GA 30324 1.800.792.5975 WWW A, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COM .CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Table of Contents, Cont. Emerging Technologies 20 Indoor Direct View LED 20 Direct View OLED 22 Laser Phosphor Display 22 Conclusions 24 Searching for the Ideal System 24 Concluding Thoughts 24 References 25 Disclaimer 27 PAGE 3 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, A CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANT TLANTA, GA 30324 1.800.792.5975 A, GA 30324 1.800.792.5975 WWW WWW.CINEMASSIVE.COM .CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Selecting the ideal video wall solution can be bewildering. A complete video wall system requires ABSTRACT a number of components, and a wide range of options are available for each of them. Of all of the decisions that must be made when planning for a video wall system, perhaps the most deceptively simple is selecting the display type. An enormous range of video wall display technologies are available on the market today, each with their own unique characteristics, advantages, and disadvantages. Many potential buyers, architects, and engineers become quickly overwhelmed by the sheer variety of display types. Worse, manufacturers provide a plethora of promotional materials that often make conflicting claims and use widely inconsistent terminology and systems of measurement to describe their products. It is unsurprising that organizations often struggle to compare competing technologies or even to define CURVE, Georgia State University Library which characteristics are most valuable and relevant for them. This white paper aims to demystify the video wall display selection process by providing an unbiased guide to the most popular display technologies available today. It introduces four of the currently most popular display types and three emerging display technologies that may also merit consideration. Each display discussion provides a basic explanation of the technology behind the display type and describes some of the common advantages and disadvantages of that technology with regards to physical performance, aesthetics, maintenance, and cost of ownership. The information presented in this document has been collected from internal subject matter experts along with external sources, including industry research papers, dissertations, journals, and more. While the writers have made every effort to provide current, accurate, and useful information, it should be noted that individual products and user experiences will vary. In addition, video wall technology is advancing rapidly and the characteristics of a particular display type may shift over time. Ultimately, only the customer can determine the ideal video wall system for his or her own application and environment. The information that follows is simply intended as a framework to introduce available technologies and present considerations that may be useful in refining the selection process. PAGE 4 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Choosing a Video Wall Display INTRODUCTION The exploding popularity of video walls in recent years A video wall is a largescale visual display consisting has generated an intensely competitive market and a of multiple monitors, projectors, or other display tech large selection of video wall options. For many organi nologies that are tiled or overlapped to form a sin zations, it is an excellent, and even necessary, time to gle, expansive display surface. Today, video walls are invest in a video wall system. However, selecting the transforming the way people communicate, learn, and ideal video wall can be a confusing and overwhelming solve problems around the world. At their best, these task due to the enormous variety of display technolo largescale visual displays are engaging and powerful gies available in today’s market. An internet search for tools that enhance users’ ability to see, understand, and “video wall” yields a range of terms, including “LCD,” share information with others. “LED,” “LPD,” “cubes,” and “projectors,” to name only a few. Each of these terms represents a distinct type of display technology and even within each of these cate Why A Video Wall gories, there are a number of nuances and options. In many cases, video walls offer significant advantag The materials provided by video wall manufacturers es over the use of a single, large display. Perhaps often claim that the display technology of their spe most importantly, video walls can provide much larger, cialty is the ideal solution for any application. In reality, higherresolution images than single displays. A large, however, every application is unique and each type of highresolution central display enables all of the users display offers a distinct set of advantages and disad in a space to clearly view, interact with, and share infor vantages. A particular display type may be excellently mation. Teams can unite their resources on a central suited to some activities and environments, but poorly ized platform and engage in collaborative monitoring, suited to others. In order to select the ideal video wall exploration, and problemsolving. Video walls can also for a particular application and environment, it is critical offer far more flexibility of shape and dimension than to first develop an understanding of the technology single displays. Video walls can be curved, nonrect behind each display type, its inherent strengths and angular, or even threedimensional. Far more versatile weaknesses, and the options available. than a single display, a video wall can function as an im mersive research environment, a 3D simulation system, or even an element of architectural design. When integrated with effective processors and soft ware, video walls can provide benefits for virtually any application and environment. Video wall systems can provide enormous advantages in control room environ ments, from military command centers to utility control rooms and security operations centers. Functioning as largescale, highresolution dashboards, they can increase situational awareness, enhance collaboration, and facilitate agile incident response. In universities and research facilities, video walls enable the interactive ex U.S. Army ploration of big data and research content and can dis play highresolution material at extraordinary scale and detail. In corporate boardrooms and conference rooms, video walls can provide engaging, interactive presenta tion platforms and enhance unified communications. In public spaces, video walls can create visually stunning platforms for promotional media or public information boards for critical messages. PAGE 5 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Most LCD displays on the market today utilize TFT (thinfilmtransistor) LCD technology, an activematrix LCD VIDEO scheme in which each pixel is controlled by one to four transistors. The two major varieties of TFT LCD panels that are typically used in LCD video walls are TN WALLS (Twisted Nematic) and IPS (InPlane Switching). These two technologies differ in the way that their liquid crystal molecules move in relationship to the panel plane. In TN panels, crystal molecules move parallel to the plane, while in IPS, they move perpendicular to it (Matuszczyk, 2000). This distinction creates a number of differences in the way that TN and IPS LCD displays perform and may be an important factor in selecting the ideal LCD video wall. The nuances of TN and IPS LCD performance will be further explored below. In fullarray backlighting, common in early LEDLCDs, rows of LEDs were spread across the entire back panel of the display and divided into a number of zones that LCD Video Wall (CURVE, Georgia State University Library) were controlled individually by a local dimming feature, enabling portions of the backlight to be dimmed while others remained illuminated. This feature helped to improve contrast and black ratios in early LEDLCDs, How It Works but resulted in the displays being relatively thick and quite expensive (Wilcox, 2012). LCD is one of the most popular video wall technologies available today. LCD technology will already be Directlit (sometimes simply “backlit”) LEDLCDs were familiar to most due to its widespread use in personal developed as a more affordable alternative to expen computer monitors and televisions. An LCD, or liquid sive fullarray displays. They feature fewer total LEDs crystal display, is a flat panel display that uses the light across the back of the display and some lack the local modulating properties of liquid crystals to display dimming function. Directlit displays are frequently an image. Each pixel of an LCD is composed of a even thicker than their fullarray predecessors because layer of liquid crystal molecules aligned between two since fewer LEDs are used, they must be moved farther transparent electrodes and two polarizing filters. When back from the screen to provide the necessary light an electric field is applied, the liquid crystals twist or coverage. However, they are advantageous in terms reorient, allowing light to pass through and produce of brightness uniformity, and models that feature local images in color or monochrome (Matuszczyk, 2000). dimming offer excellent contrast ratios. Because liquid crystals do not emit their own light, Edgelit LEDLCDs light the display from the edges LCD panels must utilize a backlight located at the back of the panel instead of the back. Light signals then of the LCD glass. CCFL (cold cathode fluorescent), transfer across the panel to display an image. Edgelit an older backlighting technology, may still be used in LEDLCDs can be extremely thin compared to directlit laptop computer monitors. However, most of the large models. However, they may lack the excellent bright scale LCDs used in video walls are LEDbacklit. In this ness uniformity and contrast levels of directlit displays system, LEDs (light emitting diodes) shine through the since the LEDs are not arranged evenly across the back liquid crystals to produce an image. An LCD video wall of the display (Wilcox, 2012). is built from an array of commercialgrade, narrowbezel LCD panels that create a largescale visual display. The individual panels used in LCD video walls typically measure from 42” to 60” diagonally. PAGE 6 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 black regions appear greyish. However, this issue has Characteristics and Performance been improved significantly over the years. Current highquality LCD displays, particularly IPS, can provide Visual Performance high contrast levels and deep blacks.   Resolution LCD video walls offer a number of advantages in Viewing Angle terms of visual performance. One major advantage is LCD technology can also offer extremely wide viewing resolution. LCD panels can provide some of the highest angles. IPS LCD panels provide a particularly excellent total resolutions of any technology available today, with viewing angle with minimal color and light dropoff, making most displays between 47 and 55 inches offering at images easier to see from a distance or from offaxis. least 1920x1080 (full HD) and some displays providing TN LCD displays provide a more limited viewing angle, resolutions as high as 3840x2160 (4K) or even 7680x4320 causing pixel colors to invert at extreme angles. This (8K). These ultrahigh resolutions are made possible by makes IPS LCD a superior choice for large control room the high pixel density, or PPI (pixels per inch) that LCD environments in which many operators will need a clear technology can provide. view of the video wall. Due to its high pixel density, of LCD can produce a Appearance on Camera sharply detailed image that allows viewers to discern text When viewed on camera, older display technologies like and images with minimal eye fatigue. This high PPI also CRTs (cathode ray tubes) often appeared to flicker or show enables LCD video walls to be approached and viewed scan lines. This issue was caused by disparities between at extremely close proximity with no perceived loss of the refresh rates of the cameras and the refresh rates of image quality. On display types with lower PPI, text and the displayed images that the cameras were recapturing. images can be difficult to discern at close range. Because many older displays had fixed refresh rates, they could not be adjusted to match the cameras filming them. LCD video walls may be said to have a “stacked” However, most modern display technologies, including resolution as each additional panel increases the LCD, do not suffer from this issue because the refresh rate total resolution of the video wall. This represents a of the displays can be synched to the refresh rate of the significant advantage over projectionbased systems, in camera. Therefore, LCDs appear solid and steady and do not which the projected image is simply stretched across a show scan lines or other artifacts when viewed on camera. larger surface, diminishing the pixel density.   Color Reproduction and Uniformity Brightness Regarding color reproduction, or how well colors can be Many LCD panels can provide high brightness, and accurately displayed, LCD video walls vary depending brightness levels can be adjusted quickly and easily. For this upon whether TN or IPS panels are used. Most TN panels reason, LCD is a popular display choice for environments only display 6bits per RGB color, and as such can only with significant ambient light that would wash out a represent 70 (18 bits total) of the 24bit color available projectionbased display. Maximum LCD brightness from graphics cards. To compensate, TN panels display decreases gradually over time, but higher brightness interpolated 24bit color by using dithering or Frame settings may be used to compensate for this if the displays Rate Control (FRC) adjacent pixels to create the missing were not initially running at their full brightness potential. desired shade (Artamonov, 2004). Due to using 8 bit or even 10 bit panels, professional IPS LCD displays have a much wider color gamut, enabling them to provide highly Contrast Ratios and Black Levels accurate color reproduction without dithering (although Early LCD displays were not able to provide the dithering may still be found on certain models). For this excellent contrast ratios and black levels available in reason, video walls that use IPS LCD panels may be the technologies like Direct View LED and plasma. This was preferred choice for marketing groups or any users that because some of the light produced by the backlight require excellent color reproduction. was still visible behind pixels that were fully off, making PAGE 7 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Color uniformity is typically excellent within individual is rarely considered a disadvantage for most video LCD panels, although color may initially need to be wall applications. TN and IPS technology once varied calibrated when a video wall is built to ensure precise significantly in response time, with TN LCDs having uniformity across multiple panels. While the brightness far faster response times than IPS LCDs. However, this of LCD panels will decline over time, color generally disparity has been reduced in recent years and there is remains consistent. This represents an advantage over now little practical difference in most use cases. projectionbased systems, which may experience heavy color changes over time. Touch Interactivity LCD displays can be configured to provide multi Visual Artifacts touch control, enabling users to interact directly with LCD displays may experience some minor issues display content. While most display technologies can with image retention, although they are not nearly as be modified for touch, LCD is unique in that touch can susceptible as plasma displays. In applications where typically be provided by the manufacturer, eliminating a static image is displayed for an extended period of the additional installation time and expense of a third time, pixels may lose their ability to return to a relaxed party integration. Touch provides increased interactivity state. This image persistence is generally minor and and can be a valuable asset for presentation, research, temporary. and education applications. Dead and stuck pixels may also occur in LCD displays, Bezels typically due to transistor error. Stuck pixels may cause One frequentlycited disadvantage of LCD video walls is a single subpixel to appear “stuck” on a certain color, bezel width. Compared to projection cubes or blended while dead pixels may appear permanently white or projection systems, LCD panels have thicker bezels, black. Stuck pixels can sometimes be corrected by or seams, appearing around each panel in the array. software or physical methods, or may eventually correct For applications in which detailed charts or graphs are themselves. Dead pixels are more difficult to correct. displayed, bezels may be seen as disruptive. They may However, most LCD manufacturers will replace a display also diminish the effect of 3D content in virtual reality with a certain number of subpixel defects and some and simulation applications. In some cases, customers manufacturers have zerotolerance policy for these may simply find them unattractive. defects. Dead or stuck pixels are generally a minor concern unless the video wall will be viewed at close However, LCD manufacturers are well aware of this proximity and such defects will be easily noticed. In complaint and have made significant progress in larger environments, individual pixel defects are rarely reducing bezel width with each new generation of noticeable during regular use.  display. Some current LCD displays offer bezel widths as low as 3.5mm, a dramatic reduction from previous 5mm Response Time and 7mm models. Response time, measured in milliseconds, is a measurement of the amount of time a pixel in a display takes to change. Displays with lower response times can Spatial, Environmental, and Aesthetic perform faster transitions and show fewer image artifacts. Concerns While response time for LCD has been improved significantly over the years, it is still somewhat slower Footprint than many competing technologies. The minimum Bezels aside, LCD video walls can offer a number of response time for the latest LCD displays is around aesthetic and spatial advantages. Perhaps the most 1 millisecond, while some DLP projectors offer evident of these is their minimal footprint. LCD video response times in the low microseconds. However, walls have an extremely shallow depth, which can be this distinction may be imperceptible to the human as narrow as 4” deep when wallmounted. LCD video eye, so the response time of today’s LCD displays walls are extremely spaceefficient when compared PAGE 8 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 to projection cube systems, which require a minimum Scalability of 24” and cannot be wallmounted, or blended rear LCD video walls are easily extensible over time, projection systems, which may take up 14’ or more and making them an excellent solution for organizations require their own rooms or enclosed spaces. with budget constraints that may want to expand their systems in the future. However, it is always recommended to plan for such expansions in Size and Shape advance, taking into account the increased spatial and LCD video walls offer a wide range of options in terms electrical requirements of an expanded system so as of size and shape. They are extremely scalable and to minimize construction later. In addition, because can be easily expanded by simply adding additional LCD displays are constantly being developed and LCD panels to the array. In addition, because of improved by manufacturers, it is advisable to undertake the narrow profile of LCD panels, a wide range of expansions as soon as possible in order to guarantee mounting options are available. LCD video walls can the availability of the original displays and minimize be freestanding, wallmounted, recessed into a wall, or brightness discrepancies between the older displays even mobile. They can also be built on a curved radius and the new additions. to accommodate unusual architecture, save space, or create an immersive environment. Reliability and Resilience Ease of Deployment Reliability LCD video walls can provide extreme reliability and Weight are capable of 24/7 performance with no downtime LCD panels are easy to mount and align, and because needed. This gives LCD a tremendous advantage over little maintenance is necessary after installation, re lampbased projection systems, which require regular alignments are rare. However, while individual LCD system downtime to replace and cool lamps. displays are lightweight, total weight can become substantial depending on the size of the video wall. A The reliability of LCD technology is due in part to structural wall may be required to safely hold the weight the long lifespan of the LED light source and the of a large wallmounted LCD video wall. Similarly, the absence of consumable parts that would need regular supports of large freestanding systems may need to be maintenance. Some premium LCD displays even offer mounted to the building structure for extra stability. redundant power supplies for each individual display, ensuring continuous operation even if a power supply is compromised. In addition, modern LEDLCD panels Location of Power Supplies generate relatively little heat, particularly in contrast to One variable affecting the installation of LCD video early CCFLLCD and plasma panels. LCD displays that walls is the location of the power supplies. Displays use remote power are superior in this regard because using local power supplies may require electrical the power supplies are located away from the display additions or modifications to be made to the wall. panels, reducing heat levels. Displays with remote power supplies will require electrical circuits to be available at the equipment location. However, these circuits are frequently available Resilience, Serviceability, and Lifespan in a nearby data center or IT closet, making them less LCD video walls enjoy an extremely long lifespan, expensive to connect. Remote power supplies are also with some systems having an MTBF (mean time advantageous in that they reduce the depth of the between failures) of over 100,000 hours when used video wall, lower the thermal footprint of the system, 24/7 (CineMassive, 2014). Because LCDs are composed and enable easier serviceability than local power of solidstate electronics with no moving parts, they supplies. are very resilient to environmental stressors such as vibration, humidity, UV light, and rugged landscapes, and can be easily transported with minimal risk. PAGE 9 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 If they are mounted properly, LCD panels are quick and easy to service. Some models even include replaceable PLASMA DISPLAY modular electronics, enabling certain components to be replaced without replacing the entire panel. The resilience and easy serviceability of LCD video walls PANEL VIDEO makes LCD an excellent solution for mobile displays and rugged, suboptimal environments. WALLS Cost of Ownership How It Works Initial Cost Plasma display panels (PDP) are a flat panel display The initial cost of LCD video walls is moderate. They technology that uses small cells containing electrically are generally much less expensive than projection charged ionized gases, or plasmas, to produce an cubes and rear blended projection systems, while image. A plasma display consists of millions of tiny initially more expensive than traditional front projection gasfilled compartments, or cells, between two panels systems. The main economic advantage of LCD video of glass. walls is in their low total cost of ownership (TCO). PDPs produce an image by applying high voltage to trigger a series of reactions in the gasfilled cells. Total Cost of Ownership When voltage is applied to a cell, the gas inside forms As previously discussed, LCD systems include a plasma, causing a reaction that increases the energy no consumable parts and do not require regular level of the atoms until that excess energy is shed maintenance, both factors that make traditional front as ultraviolet photons. The UV photons then strike projection and blended projection systems costly to phosphor molecules that are painted on the inside maintain over time. LEDLCD displays have a much of the cell, resulting in a second reaction that causes lower power consumption than many competing the phosphor molecules to shed a photon at a lower technologies, particularly when compared to projection, energy level than the UV light. This energy is shed plasma, and legacy CCFLLCD systems. With minimal mainly as infrared heat, but also produces some visible maintenance requirements, low power consumption, light. Different phosphors are employed to produce and a typical lifespan of around 6.8 years to half various colors of light and each pixel is comprised of brightness, LCD video walls offer an extremely low total three cells to provide the primary colors of visible light. cost of ownership and are one of the most affordable Varying the voltage of the signals applied to these cells video wall options in the long term. results in different visible colors. Like LCD video walls, plasma video walls are built from an array of multiple plasma panels (Harris, 2000).   A Technology in Decline When plasma technology entered the mainstream display market in the mid1990s, it offered a number of advantages over the CCFLLCD and CRT (cathode ray tube) displays of the time. Plasma provided larger screen sizes than traditional tube TVs and ushered in an era of wide format, highdefinition displays. Although plasma displays were still somewhat heavy, they were lighter and thinner than comparable CRTs at the time. Plasma also provided superior contrast ratios, viewing PAGE 10 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 angles, and response times when compared to many early CCFLLCD displays. This excellent image quality PROJECTION along with the availability of displays up to and over 100” enabled plasma to enjoy broad popularity, particularly in the television and home cinema markets, CUBE VIDEO for some time. Throughout the years, however, plasma has continued WALLS to suffer from some significant disadvantages. Perhaps the most widelyrecognized of these issues is image retention. When a static image is displayed for some time, phosphors in the cells overheat, losing their luminosity and producing permanent “shadows” that persist even with the power off. In addition, when very bright images are displayed, pixels may build up a charge, producing “ghost images” that linger temporarily on the display. Plasma also consumes far more power and gives off much more heat than LCD, particularly when displaying bright content. In the mid2000s, as the thinner and lighter LCD technology began to see significant improvements in contrast ratio, viewing angles, and response times, plasma gradually lost market share. Eventually, plasma’s Projection Cube Video Wall advantages over LCD were minimized and could no longer outweigh the issues of screen retention and How It Works power usage. In addition, the price of plasma displays failed to decrease as rapidly as LCD prices throughout the 2000s. At the time of this writing, most major Like LCD, projection cubes are a popular variety of manufacturers no longer produce plasma displays, and video wall technology. Projection cubes consist of a while some existing inventory may still be available, rear projection system that is housed in a sealed cube the technology is rapidly becoming obsolete. Because to increase contrast levels and limit ambient light from plasma technology is vanishing quickly and may not be washing out the projected image. In a projection cube supported much longer, it is not recommended as a system, images are produced by projecting light onto video wall solution. a mirror that then reflects the image onto a screen for viewing. While legacy projection systems used lamps as a light source, most contemporary projection cubes employ LED backlighting. The adoption of LED backlighting has reduced maintenance requirements, eliminated expensive consumable parts, and lowered operating temperatures, making projection cubes a much more competitive and versatile option than they were previously. Projection cube video walls are constructed from a series of projection cubes that are stacked on top of each other. Individual cube sizes vary widely. While most cubes currently measure between 50” and 80” diagonally, some cubes may be as small as 20”. PAGE 11 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 While not altogether seamless, projection cubes feature Brightness extremely narrow bezels, enabling cubebased video The sealed casing of projection cubes limits the effects walls to appear virtually seamless from a typical viewing of ambient light and increases contrast levels, enabling distances. For this reason, projection cube video walls cubes to produce images that are easier to discern may be chosen for applications that require a near and cause less eye fatigue than most standard front seamless display, but demand more reliable performance projection systems. However, projection cubes cannot than traditional projectionbased systems can offer. provide as much brightness as LCD or Direct View LED technologies. Therefore, some ambient light control is generally required to ensure that display content is clearly visible. While projection cube video walls appear Characteristics and Performance steady and solid on camera, the need for lower ambient light levels may affect photography and filming. Much Visual performance like LCDs, projection cubes gradually lose brightness over time as the LED light engine ages. NearSeamlessness From a visual perspective, the key distinguishing characteristic of projection cube video walls is their Viewing Angle nearseamless appearance. With bezels as narrow as The viewing angle of projection cubes is lower than 0.2 mm or less between screen surfaces as large as that of competing technologies like LCD, LED, and 80” (2032 mm) diagonally, a projection cube video LPD. This is because projection screens focus light wall can appear to be virtually seamless. Projection toward the onaxis viewer, so viewers located at wider cube technology is therefore an excellent solution for angles experience drastic light falloff and color applications in which more perceptible bezels could uniformity issues. Due to this limitation, projection cube compromise display content and distract viewers. technology may not be ideal for environments where viewers will be distributed across a wide viewing area. Resolution The resolution of projection cube technology varies, but Color Uniformity can be relatively high. Like LCD video walls, projection Like LCD displays, individual projection cubes have cube video walls have a “stackable” resolution, excellent color uniformity but a projection cube video meaning that the total resolution of the video wall wall will need to be calibrated during assembly to is increased with each additional cube. A number of ensure uniformity across all of the cubes. Some cube different aspect ratios are available, including 4:3, technologies feature auto calibration which reduces the 16:9, and 16:10. Typical resolutions include 1024x768 ongoing need to calibrate displays. DLPLED projection (XGA), 1400x1050 (SXGA+), 1920x1080 (Full HD), and cubes experience no image retention issues and are 1920x1200 (WUXGA). preferable to emissive technologies for displaying static images over extended periods of time. Projection cubes can provide higher total resolutions than some other technologies, such as direct view LED and LPD. Compared to LCD or plasma systems however, Refresh Rates projection cube systems have a lower pixel density, Refresh rates for rear projection cubes are typically so larger displays must be used to create a video wall comparable to those of LCD displays of similar canvas of a certain resolution. For example, an 80” 1080P resolutions (Mitsubishi, 2014). Expressed with a frequency projection cube is comparable in height to two stacked rating of Hertz (Hz), refresh rates indicate the number 47” 1080P LCD panels, but provides only half the vertical of times the screen redraws or refreshes to form a fluid resolution of the LCD panels. This reduced resolution video image. Refresh rates may also be expressed as and increased pixel spacing may not be an issue if the scanning frequency per the given resolution, i.e. 60Hz at video wall will be viewed from some distance. However, if 1920x1080, or simply listed alone as a maximum rate, i.e. viewers will be seated in close proximity or will be able to 120Hz Refresh. walk up to the wall, this factor may be of more concern during the system design. PAGE 12 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 In cases when only the maximum refresh rate is listed, Like LCD panels, projection cubes are tileable, and if additional research may be necessary to determine large cubes are used, they can be a more costeffective whether the display will accept the intended input solution than LCD for very large video walls. The large resolution and frequency. Typically, displays are also dimensions of each cube allow a large video wall to be capable of displaying lower resolution and refresh rate built using fewer individual cubes, although the weight standard combinations than the specified maximum. of the cubes places certain limitations on the number of If only the full pixel clock rate is listed, it will be necessary cubes that can be stacked on top of each other.   to calculate the pixel clock or bandwidth for the intended input. A basic formula may be used to determine this information: (Horizontal Pixels + Horizontal Blanking) x Footprint (Vertical Pixels + Vertical Blanking) x Desired Refresh Rate Compared to flat panel technologies like LCD, cube = Total Pixel Clock. For example, if the desired input was video walls have a large footprint. Most cubes are at least a PC with a 1600x1200 image at 60Hz, the formula would 24” deep, and because of their weight must be mounted appear as (1600+560) x (1200+50) x 60 = 162MHz. The on the floor or on a solid platform. In addition, most result, 162MHz, represents the total pixel clock capability basic cube models are rearserviceable, necessitating that the display would need to show the image. Online additional floor space to provide technicians with rear calculators are also available to perform this calculation. access to the cubes. Upgraded models may offer front serviceability, which reduces floor space requirements If refresh rate information is not presented clearly, it is but adds to the initial price of the cubes. always advised to contact the display manufacturer for further clarification. Ease of Deployment Touch Interactivity Unlike LCD displays, projection cubes do not typically Weight offer touch interactivity as a factory option. A projection Cubebased video walls require a significant amount of cube video wall can be configured for touch after assembly during implementation as compared to LCD assembly, but this typically requires the use of rear or other emissive technologies. Because fully assembled serviceable cubes, which demand more floorspace cubes are both heavy and fragile, the projectors, screens, for serviceability. In this case, a glass substrate can be cabinets, and light engines for each cube are typically permanently installed in front of the cube wall. For shipped separately to the building site and cubes are video walls composed of frontserviceable cubes, the assembled onsite during the construction of the video sheet of glass required for touch must be removable so wall. While quite heavy, projection cubes provide the as to not inhibit serviceability. In either arrangement, advantage of an inbuilt mounting system, since cubes the addition of a touch system to a cube video wall can simply be stacked on top of one another. This adds significant complexity and cost. For projects in represents an advantage over LCD panels, which require which touch interactivity is a major focus, LCD displays an external mounting frame or wall. may be a more practical and costeffective option.   Scalability Like LCD video walls, LEDbased projection cubes are scalable over time, enabling customers to expand Spatial, Environmental, and Aesthetic their systems after initial implementation. As with all Concerns scalable systems however, it is advised to consider any plans for future expansion when designing the video Size and Shape wall environment so that an expanded system can be Projection cubes offer an excellent range of options in accommodated in the space. It is also recommended terms of shape and size. Cube video walls can be flat, to implement desired expansions as soon as possible in curved, and even nonrectangular in shape, and the order to guarantee parts availability and consistency in broad range of aspect ratios and cube sizes that are brightness. available increase these options further. PAGE 13 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Reliability and Resilience Cost of Ownership Reliability Initial Cost Today’s LEDbased rear projection cubes offer very In most cases, the initial cost of a projection cube high reliability, particularly in contrast to lampbased video wall is significantly higher than some competing cubes or projection systems. Like LEDLCD video walls, technologies. A small to medium LEDbased cube LEDbased cube walls can provide 24/7 performance wall may be around three times the price of an LED and are suitable for use in critical control room LCD video wall of similar dimensions. However, for environments. Because LEDbacklit cubes do not rely very largescale video walls, projection cubes may be upon consumable parts like lamps, they require no a lessexpensive option than LCD, particularly if large regular maintenance or downtime. In addition, internal individual cubes are used. fans or water pump cooling systems help ensure that operational temperatures are kept within optimal thresholds, increasing the lifespan of the system. Total Cost of Ownership Longterm cost of maintenance for LEDbased cubes is minimal, although, as discussed previously, screens Resilience, Serviceability, and Lifespan may occasionally need to be replaced. The power LEDbased cube video walls can have a very long consumption of LEDbased projection cubes is similar lifespan, typically ranging from 60,000 to 100,000 MTBF to that of LEDLCD systems. While LEDbased cubes (Mitsubishi, 2014). After implementation, LEDbased require more power than lampbased projection cubes require minimal maintenance. However, the systems to produce an image of the same size, lamp presence of moving parts within each cube places this based systems generate far lower resolutions. In order technology at a slight disadvantage against technology to produce an image at the same resolutions as an like LEDLCD, which is composed entirely from solid LEDbased projection system, a lampbased system state electronics, and thus includes fewer potential would require multiple blended projectors, and would points of failure. In LED projection cubes, screens are ultimately draw more power. Therefore, if highresolution the most common component to require maintenance output is required, LEDbased projection cubes are as they can be damaged easily if impacted and may be a more energyefficient solution than lampbased prone to peeling over time. More rarely, a light engine projection systems. or fan may need to be replaced. If maintenance is required for a cube, most components can be replaced Overall, while the initial price of LEDbased cubes with minimal downtime and without requiring the entire is quite high, their minimal maintenance, low power cube to be removed. As discussed above, the method consumption, and long lifespans lower the total cost of of serviceability varies depending upon whether the ownership, making them a far more economical solution cubes are rearserviceable or frontserviceable. than lampbased projection systems in the long term. Total cost of ownership is still higher than LEDLCD While extremely reliable within most climatecontrolled, systems, but the nearseamlessness of cube video walls indoor environments, projection cube video walls may justify this additional expense for some customers. lack the environmental resilience of LCD video walls. Although LEDbacklit cubes are less fragile than lamp based projection systems, they still contain a number of moving parts and cannot withstand a great deal of vibration or instability. They are also sensitive to high levels of humidity and heat, which may cause screen damage and peeling over time. The need for a stable, controlled environment along with the sheer size and weight of each cube make a cubebased video wall an unlikely candidate for use in rugged, temporary, or sub optimal environments. LED Projection Cube PAGE 14 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 onto mirrors that then reflect it onto the screen. This latter arrangement “folds” the image, doubling the BLENDED throw ratio of the projectors so that the desired image size can be produced from half the distance, and the projection room can be smaller. The projection room PROJECTION functions much like a projection cube in controlling light levels on the screen. By minimizing ambient light, VIDEO WALLS rear projection systems can produce high contrast ratios and bright images, so they generally do not require projectors as bright or as costly as those needed for front projection systems. Another advantage of rear projection is that the projection room prevents much of the heat and noise generated by the system from entering the viewing environment. In front blended projection, projectors are mounted from the ceiling or wall in front of a screen surface and light is reflected off of the screen. This method requires much less space than rear projection and is typically selected when there is insufficient room available to house a rear projection system. Brighter, more expensive projectors may be required for front projection because of the presence of ambient light in Blended Projection Video Wall the space. However, front projection arrangements are typically still less expensive overall than rear projection systems due to the less costly screens and mounting How It Works systems that can be used. Similar to projection cubes, but on a larger scale, blended Projectors used for blended projection video walls projection video walls combine two or more projectors typically employ one of three types of light sources: in order to produce an image that is larger or higher lamps, LEDs, or laser. Each light source has unique resolution than could be generated by a single projector. advantages. Traditional lamplit projectors can be Blended projection systems are able to display high extremely bright, making them wellsuited for front resolution images on a completely seamless surface of projection systems. However, lamps will need to virtually any size and shape. This unique capability makes be replaced about twice a year and are expensive, blended projection a popular choice for simulation and leading to high operating costs. LEDbacklit projectors training, virtual environments, and other applications eliminate the maintenance issues caused by lamps, but requiring hyperrealistic or immersive effects. cannot provide the same levels of brightness. Thus, LEDbased projectors may be a preferable choice for In a blended projection system, multiple projected rearprojection systems, but current models are not yet images are overlapped and their edges are gradually bright enough to be ideal for frontprojection. Laser crossfaded or dithered to produce a single, seamless projectors, a relatively new technology, can provide image. Most blended projection systems require some brightness levels comparable to many lampbased amount of external processing to blend and warp the systems. Although not as bright as the brightest lamp image, but some premium projectors have most of based projectors, their high contrast levels may make these functions builtin. Blended projection systems them appear nearly as bright. With no consumable may be designed with either rear or front projection. parts, laser projectors also provide far lower operating costs and maintenance requirements than lamplit In a rear blended projection system, the projectors are projectors (Digital Projection, 2012). located behind the screen, typically in an enclosed rear projection room. The projectors may either project light directly onto the screen, or may project light PAGE 15 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Projectors also vary in their imaging technology. a fixed supporting frame and permanently mounted to DLP and LCD are the most common types of image the wall. The framing device applies uniform tension production technology currently available for to the screen surface to keep the surface taut. Front commercial projects (Morrison, 2013). LCoS (liquid projection systems occasionally use rigid glass or acrylic crystal on silicon) projectors, while popular in the screens, but this is generally not necessary unless the consumer market, are typically too small to be used system is located in a busy public space and must be for commercial video wall projects. DLP and LCD each particularly robust. The most common screen solution offer unique advantages and disadvantages. However, for rear projection systems is a rigid, framemounted it is worth noting that these technologies are in glass or acrylic screen with a layer of projection film constant development, so the characteristic strengths bonded to the surface. These rigid screens provide and weaknesses of each may shift over time. uniform flatness and minimize image distortion. Fabric screens are also available for rearprojection, but DLP (digital light processing) projectors use tiny mirrors are rarely used outside of mobile applications like to reflect light toward or away from the screen. To production staging. create color, most models use spinning color wheels with color filters. Some premium DLP projectors use Both front and rear projection screens use a rating three DLP color chips instead of a color wheel. DLP system called screen gain, or focus, that provides projectors can provide extremely low response times, in specifications about the screen’s visual performance. some cases in the low microseconds. This enables them Gain is the measurement of the amount of light to provide greater sharpness and detail for fast motion reflected off of the screen (in front projection) or passed images than LCD projectors. DLP also often provides through the screen (in rear projection) to the viewers superior contrast ratios and black levels compared to in the space. In this system, a screen gain of 1.0 is a those produced by LCD projection. In addition, models “flat reflection,” or the amount of light reflected by a with color wheels may produce an artifact called a standard white board. “rainbow effect” in which bright objects appear to have a trail of rainbow light when moving rapidly across Screens with a gain higher than 1.0 reflect more than a dark surface (Morrison, 2013). This artifact is not this standard amount of light, increasing brightness perceptible at all to some viewers, but others may find by focusing the light directly at the viewer. Highgain it distracting. LCD projectors use three liquid crystal screens can help enhance the perceived brightness of panels which each create an image using just one smaller, lesscostly projectors. However, this brightness primary color (red, green, or blue). The three images comes at the cost of the viewing angle, which must be are projected simultaneously to produce a fullcolor reduced to focus the light. Thus, highergain screens image. Due to their use of LCD panels, these projectors are bestsuited to narrower spaces where the reduced frequently cannot provide the excellent contrast ratios viewing angle is not noticeable. Highgain screens may and black levels available from DLP projectors and may also suffer from hotspots, or regions near the center of suffer from dead pixels. In addition, LCD projectors are the screen that are brighter than others. Hotspots are susceptible to motion blur when displaying fast motion especially a concern in blended projection systems. content (Morrison, 2013). This may not be noticeable to some viewers, but may bother others. Because Screens with a gain of 1.0 or lower provide little to they use emissive, rather than reflective, technology, no focusing or redirecting of light back to the viewer. LCD projectors may also produce a more visible pixel Often produced in darker colors, these lowgain structure than DLP, creating a “screen door” effect. screens can produce superior contrast ratios and black (“DLP vs. LCD vs. LCOS,” 2014). levels than those produced by highgain screens. In addition, their even distribution of light enables Another variable in blended projection systems is wider viewing angles and produces a more uniform screen technology. Depending upon whether front brightness, reducing the risk of hot spots. For these or rear projection is used, different materials and reasons, lowergain screens are often recommended arrangements may be used for the projection screen. above highgain screens for blended projection The most common screen solution for front projection systems. systems is a lightweight, flexible fabric stretched over PAGE 16 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Image Sharpness Characteristics and Performance There are a number of variables that affect perceived image sharpness in a blended projection system. Because sharpness is largely determined by resolution, Visual Performance the number and resolution of the individual projectors in the system has a large effect. The make and model Absolute Seamlessness of the projectors, lens type, and precision of lens The most striking visual characteristic of blended focusing during the installation process will also have a projection video walls is their absolute seamlessness. significant effect. In addition, as previously discussed, Competing technologies like LCD panels and cubes projectors using DLP imaging technology generally require multiple displays to be tiled together to create provide superior sharpness and detail for fast motion a video wall, which inevitably produces a seamed video than LCD projectors. Finally, the amount of display surface (however narrow the seams may be). processing required to optimize the image may also In a blended projection system however, the size and have an effect on image sharpness. Systems with flat resolution of the display surface depends only upon the projection surfaces produce the sharpest projected type and number of projectors used, so a single video image because minimal correction and processing is wall may, in theory, be as large as desired. needed to produce the image. If a curved projection surface is used, or if the projectors are simply poorly placed, the pixels must be manipulated to compensate, Resolution altering the image from its raw format and reducing The combination of multiple projectors enables the perceived sharpness. While this may be acceptable blended projection systems to produce far higher for general viewing, it is not ideal for applications like resolutions than singleprojector systems. However, marketing or branding, where sharpness, image shape, when compared to LCD or projection cube video walls and uniformity are a primary concern. of similar dimensions, blended projection video walls typically have lowerresolutions. One reason for this is Image Brightness that when multiple projected images are blended, 10 to As with sharpness, the perceived brightness of 20 of the image is lost in the overlapping blend area, blended projection systems depends upon a number lowering the overall resolution to less than the total of factors. The size, light source, and screen type of combined resolution of the independent projectors. the projectors may all have an effect on brightness. The distance between the projectors and the screen In addition, the resolution of blended projection is also an important factor; brightness will decrease systems may be limited due to the sheer number as the projectors are moved farther from the screen. of projectors that would be required to yield the Ambient light in the environment will affect brightness same resolutions produced by tiled display systems. as well. While all blended projection systems require Traditionally, in order to produce resolutions similar to some amount of ambient light control, front projection a 4x4 array of 1080P LCD panels, a blended projection systems are particularly vulnerable to being washed system would have to use sixteen 1080P projectors. out by ambient light and may require particularly bright Such a system would be prohibitively expensive for projectors to produce sufficient contrast ratios. most customers, both initially and over time due to the ongoing costs of the consumable parts. In recent Viewing Angle years, the availability of 4K projectors has increased the Viewing angles for blended projection systems will vary practicality of large, highresolution blended projection depending on the material and shape of the projection systems. If 4K projectors were used in the scenario surface. Please refer back to the discussion of screen described above, only four projectors would be needed materials for a more indepth discussion of how screen to produce resolutions similar to the 4x4 LCD array. technology affects viewing angles. In general, however, However, the projector mounting system and ongoing the viewing angles produced by blended projection are maintenance for multiple 4K projectors may still be too quite narrow and brightness levels drop off sharply as costly for many customers. As 4K and 8K LCD displays the viewer moves offaxis. are now being released, LCD will likely remain a better value than blended projection in terms of resolution. PAGE 17 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Color Reproduction and Uniformity Spatial, Environmental, and Aesthetic Blended projection video walls can provide fairly high Concerns quality color reproduction, but are typically unable to produce the extended color gamut provided by Size and Shape LCD displays and LEDbased cubes. Both LCD and One of the major advantages of blended projection DLP projector types may eventually lose color and systems is their ability to project images onto a brightness uniformity over time. LCD projectors may surface of virtually any shape and size. With additional suffer from gradual degradation of the LCD panels, image mapping software and processing, projectors manifesting in dead pixels and unevenness. In DLP can produce images on curved, angular, or spherical projectors with color wheels, the color wheel may surfaces. The additional processing required to blend collect dust or degrade over time and bearings may multiple images and warp content for display on a non wear and affect the rotation of the wheel, impacting standard surface may be provided externally or by the color uniformity and occasionally producing screen projectors themselves. Blended projection systems can artifacts. Finally, if lamplit projectors are used, the also produce extremely large images, although very lamps will dim at differing rates, resulting in gradual bright projectors must be employed to accomplish this, loss of uniformity until all of the lamps are replaced at resulting in a higher upfront cost. once. Due to these issues, blended projection systems may not be ideal for applications that require exact color reproduction and uniformity. Footprint The space consumed by a blended projection system varies dramatically depending upon whether the system Response Time uses rear or front projection. Rear blended projection Depending on the projectors used, some blended systems have a very large footprint, typically requiring projection systems can provide extremely fast response up to 14 feet or more of enclosed floor space to house times and refresh rates. As mentioned previously, the projectors. In many cases, mirrors are used to “fold” some DLP projectors offer response times in the low the image, doubling the throw ratio of the projectors so microseconds and combined refresh rates as fast as that the desired image size can be produced from half 120Hz or more, making them faster than LCD displays. the distance. The speed, advanced internal processing, and the seamlessness of blended projection systems makes Front blended projection is one of the most space them an excellent option for displaying 3D content. efficient display technologies available. Projectors are mounted to the ceiling or wall, and the display screen is usually quite thin and can be wall mounted. Thus, Touch Interactivity the only floor space required is the space between the Like cubebased systems, rear blended projection projectors and the screen, which must be kept clear to video walls can be modified for smooth and seamless prevent shadows from being cast on the screen. touch interaction. This can be achieved by integrating special glass screens with an inbuilt touch sensor. Heat and Noise However, this modification is not recommended for One environmental disadvantage of blended projection front projection systems, since in this arrangement, the systems is the heat and noise that they produce. user would need to step between the projector and the Most large projectors give off a significant amount of screen to contact the wall, casting shadows and partially heat and their internal fan systems can be quite loud. blocking the projected image. Naturally, heat and noise levels are multiplied when several projectors are used together in the same space. This issue is more noticeable with front projection systems because the projectors are located in the same room as the users. Projector cases with cooling systems and air silencers may be integrated to reduce the heat and noise in front projection systems. PAGE 18 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Heat and sound issues are minimized in rear projection Reliability and Resilience arrangements as the projectors are generally housed in a separate, enclosed space. However, care should Reliability still be taken to ensure that sufficient cooling systems The overall reliability of blended projection systems is are in place in the rear projection room because typically lower than LCD or projection cube solutions. an excessively hot environment can reduce system In general, this technology requires more monitoring, lifespan. maintenance, and part replacement than competing technologies to maintain optimal performance. One issue is that blended projection systems rely upon light sources that require either regular service or Ease of Deployment replacement. In lampbacklit projectors, lamps burn out and typically must be replaced about twice a year with Weight and Complexity moderate to heavy usage. In LEDbacklit projectors, The ease of implementation for blended projection LED light engines usually require replacement within systems depends largely upon whether front or rear three to five years. The laser light source in laser projection is used. The glass or acrylic screens used in backlit projectors will need to be replaced after about rear projection systems are heavier than front projection two years. Color and brightness uniformity will also screens, and rear blended projection systems may decrease as projectors age, causing image quality to involve a more complex implementation process suffer if key components are not replaced regularly. As if mirrors are used. However, when maintenance is previously discussed, large projectors may also produce required, rear projection systems are relatively easy a great deal of heat, which can accelerate system wear to service because their components are closer to the over time. ground and more accessible. Front blended projection systems may be easier to Resilience, Serviceability, and Lifespan install initially because screen materials are much In terms of environmental resilience, blended projection lighter. However, if projectors are mounted on high systems are often more fragile than competing ceilings, installers may need to use ladders or a lift to technologies, even within normal, climatecontrolled install them, increasing the difficulty and expense of the environments. Image stability is very sensitive to installation. High ceilingmounted projectors will also vibration, a vulnerability that is particularly severe in require a more complicated maintenance process, and systems in which the projectors are located far from the space may be unusable while maintenance is being the screen. Over time, environmental vibrations can performed. also cause projector lenses to drift out of alignment, impacting image sharpness. Vibrations can also cause moving parts to rub together, producing heat Scalability and accelerating wear and tear. Because of these When compared to tiled systems like LCD and vulnerabilities, it is critical to be aware of any vibration projection cube video walls, blended projection producing equipment nearby and plan projector systems are not easily scalable over time. To enlarge a placement accordingly. blended projection system, significant changes must be made to projector placement and lens alignment. Most blended projection systems are not wellsuited In some cases, additional projectors may be integrated for transport. However, some manufacturers offer into the existing system, but in many scenarios, the roadready projectors for use in event production and projectors will need to be replaced completely. This trade shows. These travelfriendly projectors can be is especially likely if the current projectors are several packed into cases and projection screens can be simply years old. A new, larger screen will also need to be rolled up for transport. However, this mobile concept implemented to achieve an expanded image. Overall, is more practical for single projection than for blended the expansion of a blended projection system is likely projection systems. If multiple projectors are to be used, to be costly and laborintensive. painstaking mounting and lens positioning will always be required to achieve the correct blending effect. PAGE 19 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Due to this complex assembly process and the high pricepoint of travelfriendly projectors, mobile blended EMERGING projection systems are rarely used outside of large scale, productionlevel event staging. TECHNOLOGIES While system lifespans vary depending on the individual components used, blended projection New video wall technologies are being developed and systems typically have significantly shorter lifespans refined every day. While these new technologies may than LCD and cube video walls. The need for regular spend years in development, once on the market, they maintenance downtime and part replacement may bar may quickly become popular or even disruptive. At the blended projection from environments where reliable time of this writing, three of the most exciting emerging 24/7 performance is critical. In other environments video wall technologies are direct view LED, OLED, and however, these issues may be less of a deterrent. Laser Phosphor Display. Because these technologies are relatively new, some Cost of Ownership aspects of their performance have not yet been thoroughly tested in the video wall industry. However, Initial Cost it is possible to make some preliminary assessments of The initial price of blended projection systems the strengths, weaknesses, and longterm potential of is typically lower than the price of LCD or LED these emerging solutions. based cube systems of similar dimensions except when complex mirror systems are used. After six to twelve months however, the price of regular system maintenance and replacement parts causes the total Indoor Direct View LED cost of ownership to increase significantly. Generally speaking, direct view LED is not a new Total Cost of Ownership technology. It has long been the standard display Light source replacement is a major expense technology used in large outdoor billboards and contributing to total cost of ownership. Lamps may scoreboards as well as simple indoor signage like cost thousands of dollars and must be replaced about “open” and “exit” signs. In a direct view LED display, twice a year. Lasers and LED light engines are also very an array of LEDs is mounted on a flat panel and the expensive and typically require replacement within LEDs themselves produce the visual display. This two years and three to five years, respectively. Other represents an important distinction from LEDbacklit system components like filters, fans, and color wheels technologies like LCDs and rear projection cubes, since may require service or replacement around twice a in those systems, the LEDs serve as a light source only year. Thus, when replacement parts and maintenance and do not produce images on their own. labor are considered, the longterm cost of blended projection systems may be significantly higher than that In direct view LED displays, a particular voltage is of LCD and cubebased video walls. applied to the leads of the LEDs, causing electrons to recombine with electron holes within the device and Blended projection systems can also draw a larger release energy, producing colored light. The color of amount of power than some competing technologies. the light produced is determined by the energy band While they may require less power than LCD or cube gap of the semiconductor in the LEDs. Fullcolor pixels systems to display an image of comparable size, are formed by clusters of red, green, and blue LEDs. blended projection systems require far more power to In some cases, white and yellow LEDs may also be produce an image of comparable resolution. Therefore, incorporated (LED, 2014). blended projection may not be an energyefficient solution for applications that require high resolutions. PAGE 20 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 In traditional outdoor LED displays, individual diodes viewing angle produced by direct view LED because are quite large, producing very large, very bright pixels. of the shape of the individual diodes. Because the Because these displays are designed to be viewed from diodes are rounded and emit more light toward the a distance and must compete with strong sunlight and front, brightness and color uniformity drops off when artificial light sources, extreme brightness is critical. the display is viewed offaxis. Therefore, direct view High resolution is unnecessary in displays that will be LED displays may have somewhat lower viewing angles viewed from afar, so pixel pitch (the distance from the compared to LEDbacklit LCDs, in which the LEDs serve center of one LED clusteror pixelto the center of the only as a light source instead of producing the image next cluster) may range from 10mm to 34mm or wider themselves. in these systems (NanoLumens, 2011). Due to its low resolution and intense brightness, direct view LED has Direct view LED displays have a very small footprint. not traditionally been used for indoor video walls that The latest panels may be less than 4 inches deep and are viewed at close proximity. However, as smaller LEDs lighter per square inch than LCD displays (SiliconCore, have been developed in recent years, direct view LED 2014). This technology also offers great flexibility technology has emerged as a more viable option for of shape. Individual LED panels can be flat, curved, indoor displays. or even formed into custom shapes like cylinders (NanoLumens, 2014). This can enable customers to The latest indoor direct view LED displays are much create striking and unusual video walls or accommodate higherresolution than their outdoor counterparts, architectural elements like curved walls and columns. featuring reduced size LEDs and pixel pitch as low as 1.5mm (SiliconCore, 2014). However, even these Direct view LED is a very robust and reliable technology, displays still produce far lower perceived pixel density as evidenced by its popularity for outdoor displays. than LCD, projection, or other technologies, so their Like their outdoor counterparts, indoor direct view LED resolutions are much lower than competing systems of displays can withstand a wide range of temperatures similar dimensions. Continuing development of direct and high humidity levels. Maintenance issues typically view LED technology will likely produce progressively involve the failure of individual modules, which may smaller LED’s with tighter pixel pitch, so higher result in a “patch” of nonfunctioning LEDs. These resolution displays may be available in the near future. issues may be caused by the display itself, but may In their current form, however, direct view LED displays also be processorrelated. If maintenance is necessary are not ideal for applications in which highly detailed on the display itself, serviceability is relatively easy. content must be viewed in close proximity. Individual panels are typically lightweight and can be easily removed, repaired, and replaced in most cases. One major advantage of direct view LED is its In terms of expected lifespan, individual LEDs may brightness. Although not as bright as outdoor versions, offer up to 100,000 hours MTBF, while the electronics indoor direct view LED can still provide several times MTBF for the entire display may be somewhat less the brightness of competing technologies like LCD, (SiliconCore, 2014) (PixelFLEX, 2014). cubes, and other projection systems. This makes direct view LED wellsuited for environments with significant The pricepoint of the latest higherresolution, indoor ambient light, so long as ultrahighresolution detail is direct view LED panels is currently out of the reach of not required and the display will not be viewed in close most customers. A direct view LED video wall may be proximity. In addition, due to the very high refresh rates many times the price of an LCD or projectionbased that are available for the latest indoor LED displays, this video wall of similar dimensions. Since total resolution technology displays well on camera (SiliconCore, 2014). for direct view LED is still far lower than competing Broadcast studio sets, trading floors, and shopping technologies, current models are not a great value in centers are a few environments for which direct view terms of resolution. However, maintenance costs are LED might be considered. generally low, and for applications where brightness is a major focus, direct view LED may be a more energy Direct view LED may also provide a wider viewing angle efficient solution. Most indoor direct view LED panels than projection technologies due to its direct emission can provide far more lumens (brightness) per watt than of light. However, there are some limitations to the LCD or other competing technologies. PAGE 21 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 individual display currently available is 77”, extremely Direct View OLED large panels may be available in the future due to the light, thin nature of OLED technology (Morrison, 2014). OLEDs, or organic lightemitting diodes, are another In addition, the ability to “print” OLEDs onto a display emerging video wall technology that merits discussion. surface opens a wide range of display possibilities, OLED is a type of indoor direct view LED in which the including flexible displays, rollup screens, transparent emissive electroluminescent layer is a film of organic displays, and even camouflage. compound that emits light in response to an electric current. OLEDs offer a number of advantages over Early OLEDs had limited lifespans due to challenges traditional direct view LEDs. First, OLED technology can of maintaining the organic material. In these early provide much higher resolution and lower pixel pitch prototypes, certain colors, especially blue, tended to than standard direct view LED displays. Standard direct fade quickly, making the technology shortlived and view LED uses diodes housed in small epoxy cases, unviable for 24/7 use. However, recent developments and as discussed above, these diodes are still relatively have reduced these issues and some of the latest OLED large, placing limitations on pixel density for current panels claim an MTBF of up to 100,000 hours, a lifespan LED displays. In contrast, OLED is a flat, lightemitting comparable to LCD and LED projection cube systems. technology made by placing a series of thin organic films between two conductors. OLED screens can be Direct View OLED technology is still quite new and extremely thin, and can even be “printed” on flexible displays are currently very expensive due to high surfaces. High pixel density can be achieved with OLED production costs. While leading manufacturers technology. As of 2014, the latest OLED displays offer have debuted a number of OLED TVs, high prices resolutions as high as 4K (3840 x 2160) for a 65” display and manufacturing limitations have prevented this and a 55” 8K display (7680 x 4320) is reportedly in technology from being adopted in the video wall development (Morrison, 2014)(Cho, 2014). industry thus far (Morrison, 2014). However, provided that development continues and prices begin to fall, In addition to resolution, OLEDs offer several other OLED will become a highly competitive technology in visual advantages. Because OLEDs emit their own the video wall market. light and do not require a backlight, pixels can be shut off individually. This allows OLED displays to produce higher contrast ratios and deeper blacks than backlit technologies like LCD and cubes. OLED displays are also brighter than many competing technologies. The Laser Phosphor Display inclusion of a white OLED in some displays increases Like OLED, Laser Phosphor Display (LPD) technology brightness and contrast levels further. combines traditional technology with new components. First brought to the market by Prysm, Inc. in 2010, The direct emission of light also allows OLED displays LPD employs a variation on cathode ray tube (CRT) to provide wider viewing angles than LCDs. Pixel colors technology, the system used in traditional tube remain unshifted as the viewer moves offaxis, even televisions. LPD adapts this technology by using lasers at angles approaching 180°. Pixel response time and instead of an electron gun to excite phosphors and refresh rates for OLEDs are also significantly faster than produce an image. In an enclosed arrangement similar LCD. OLED displays may provide a response time of to a projection cube system, a set of movable mirrors less than 0.01 milliseconds, enabling a refresh rate up to reflects light from ultraviolet lasers onto a screen. The 100,000 Hz. screen is made of a plastic and glass hybrid material and is coated with colored phosphor stripes. As the If used to create a video wall, OLED displays would reflected lasers scan the screen from top to bottom, likely be comparable or even easier to install than LCD the energy from their light activates the phosphors, displays. With no need for a backlight, OLED panels which emit photons, producing an image (Greene, can be extremely thin and lightweight; some OLED 2010). Multiple LPD cubes, or tiles, can be stacked panels are as thin as 4mm. Like LCD and projection andarranged in various configurations to create a large cube systems, an OLED video wall would likely be scale video wall. a tiled array of multiple panels. While the largest PAGE 22 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Like projection cubes, LPD tiles feature narrow seams, regular downtime should not be necessary. Provided which measure only 0.5 mm in some models. However, that no maintenance issues arise, the longterm cost unlike cube displays, which may measure up to 80” of ownership for an LPD video wall may be quite diagonally, LPD tiles offer a surface area of only 25”. low. However, because the first LPD systems were Thus, while an LPD video wall will have narrower seams, installed only four years ago, there is little information it will also have many more seams than competing available thus far on the longterm performance and technologies. The pixel density of LPD displays is lower maintenance requirements of this technology. than many competing technologies, with a 25” display surface providing a maximum resolution of 427 x 320 In terms of life span, LPD technology has not yet been (Prysm, 2013). thoroughly timetested. While similar phosphorbased display systems like CRT have proven durable and long In terms of visual performance, LPD offers some lasting, the longevity of the laser component in LPD has notable advantages. LPD displays provide far better not yet been established. The latest LPD tiles advertise color reproduction than competing technologies. an MTBF of 60,000 hours at 24/7 operation, a shorter The unusually wide color gamut produced by this life span than LEDLCD and LED projection cube technology enables LPD panels to display 98 of technologies, which may offer MTBFs of up to 100,000 the 24bit color available from graphics cards. As a hours at 24/7 operation. reflective technology, LPD displays are not as bright as LCD or emissive technologies like direct view LED Because laser phosphor technology is still quite new, and OLED. Some amount of ambient light control will little is known about longterm performance and the be necessary to prevent images from being washed range of options available to consumers is limited. out. However, because the speed of the lasers enables However, as LPD continues to be tested and refined, pixels to be shut off individually, LPD provides excellent it may emerge into the mainstream to compete more contrast ratios and black levels. LPD technology also closely with LCD and cube technologies. offers significantly faster response times and refresh rates than LCD displays (Prysm, 2013). Spatially, LPD tiles have a depth of around 16 inches. Depending on the type of frame that is used, the total installed depth of an LPD system will be around 24 to 30 inches, producing a footprint similar to that of an LEDbased projection cube system. Because current LPD tiles are only rearserviceable, a minimum clearance of 31.5 inches is required behind the displays to enable maintenance (Prysm, 2013). One positive aspect of this rearserviceable design is that it enables the tiles to be more easily configured for touch interactivity. Like LEDbased projection cubes, LPD video walls may be extended over time by stacking additional tiles on the array. The small surface area of LPD tiles allows them to be arranged in a wide range of patterns and shapes. The initial price of an LPD video wall may be significantly higher than an LCD video wall of similar dimensions, but is typically less than a rear projection cube system. Typical power usage for LPD is similar to LCD and may be less than some competing technologies like blended projection and cubes (Prysm, 2013). LPD systems have no consumable parts and are mainly composed of solidstate electronics, so PAGE 23 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 development of their system. Some customers hire independent contractors for this purpose. Alternatively, CONCLUSIONS other customers leverage partnerships with video wall companies that provide endtoend solutions, including all system components, integration, and support. Searching for the Ideal System This paper has chosen to focus on video wall display technologies because the selection of a display type Concluding Thoughts is a common starting point in choosing a video wall system. However, there is much more to a video wall As this paper has demonstrated, an enormous variety system than visual displays. Video wall controllers, of video wall display technologies are available today. which process content sources and route them to All of these technologies have value, but their unique be displayed on the video wall, are another critical characteristics may make them better suited to some component of the system. The controller that is applications and environments than to others. In selected will determine the type and number of addition, because display technologies are in constant sources that can be displayed on the video wall, the development, the characteristics and limitations of way that content can be displayed and manipulated, each will inevitably shift over time. This paper has and the stability and reliability of the system as a attempted to provide potential buyers with a clearer whole. Content rendering engines, or controllers with understanding of some of today’s most popular and rendering capabilities, may also be desired to ensure emerging display technologies. fluid, seamless rendering for ultrahighresolution video and big data sets. Video wall software is another It is hoped that in learning about the characteristics of essential system component. It is critical to select a various technologies, the reader has been prompted to software platform that enables users to perform the consider the unique demands of his or her application, desired activities, is easy to learn and operate, and is workflow, and environment. Developing a clearly compatible with user workflow. defined set of goals and requirements is an excellent way to begin researching the ideal video wall display. Beyond these basic system components, additional As a next step, it is recommended to select a trusted elements such as integrated audio, video conferencing, and experienced display solutions expert to begin video streaming and distribution, and external device developing a fullyrealized solution. The ideal solutions control may also be desired. Regardless of the partner can offer a broad range of knowledge and complexity of the video wall system, all components experience, not only with various display types, but must be fully compatible with one another and expertly also with diverse applications and environments. It is integrated to ensure consistent, reliable performance. also advised to seek a partner that takes a customized, solutionsoriented approach and can develop video The process of selecting each component of a video wall systems that are optimized for the unique demands wall system is further complicated by the fact that of each project. most manufacturers do not offer all necessary system components. Many offer only displays, while others can only provide processors and software. In addition, few manufacturers offer integration services for their products. As a result, customers may find themselves selecting components from multiple manufacturers and hiring an independent integrator to assemble their video wall system. To ensure that their video wall system is built from the ideal components and is seamlessly integrated for optimal performance, customers should select a reliable and experienced partner to aid in the Video Wall Installation PAGE 24 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 REFERENCES Artamonov, O. (2004, October). Xbit’s Guide: Contemporary LCD Monitor Parameters and Characteristics. (White paper). Retrieved from www.xbitlabs.com/articles/monitors/display/lcdguide11.html Cho, M. (2014, December). LG to show off new 55inch 8K display at CES 2015. CNET Magazine. Retrieved from www.oledinfo.com/lgshow558koledtvprototypenextmonthces2015 CineMassive (2014). CineView II: The Next Generation Video Wall (Fact sheet). Retrieved from www.cinemassive.com/pdf/cinemassivecineviewiilcdvideowall.pdf DLP vs. LCD vs. LCOS (Internet resource). The Projector Pros. 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Retrieved from www.consumerreports.org/cro/news/2012/05/whatisadirectlitledlcdtv/index.htm PAGE 26 OF 28 CINEMASSIVE 150 OTTLEY DRIVE NE, ATLANTA, GA 30324 1.800.792.5975 WWW.CINEMASSIVE.COMA COMPARISON OF VIDEO WALL DISPLAYS / APRIL 2015 / RELEASE 1.0 Notice: ALL INFORMATION PROVIDED IN THIS WHITE PAPER, INCLUDING COMMENTARY, OPINION, CINEMASSIVE DESIGN SPECIFICATIONS, FILES, DRAWINGS, DIAGNOSTICS, LISTS, AND OTHER DOCUMENTS (TOGETHER AND SEPARATELY, “MATERIALS”) ARE BEING PROVIDED “AS IS.” CINEMASSIVE MAKES NO WARRANTIES, EXPRESSED, IMPLIED, STATUTORY, OR OTHERWISE WITH RESPECT TO MATERIALS, AND EXPRESSLY DISCLAIMS ALL IMPLIED WARRANTIES OF NONINFRINGEMENT, MERCHANTABILITY, AND FITNESS FOR A PARTICULAR PURPOSE. Information furnished is believed to be accurate and reliable. However, CineMassive assumes no responsibility for the consequences of use of such information or for any infringement of patents or other rights of third parties that may result from its use. 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