When there are budgetary constraints, LCD panels may be the most appropriate solution although its operational life is smaller and has to do some other operating sacrifice.
By Juan Carlos Chavez *
Receive information, analyze, collaborate to maintain normalcy or respond to emergency situations: that is the day-to-day control room environments. To carry out these tasks, the challenge is how to visualize in real time and efficiently the work of monitoring, checking and communication that those tasks require.
To establish which technology to support the people who manage and monitor the continuity of the work and respond to actual or potential protocol breaks, it is essential to determine where and how the information is displayed.
If what is needed is to create a focal point of information for a control room equipment, especially in large formats that allow operators clear and simultaneously watch multiple feeds of content, video walls are the generalized solution.
There are three main categories of solid state technology used in control room video walls: LCD panels, projection cubes DLP® LED lighting and walls LED display (LED cubes).
Any of the three technologies can be an excellent choice for use in displays for video walls, but to decide which category will be most suitable to a particular application or user will have to look at what features of each solution meets the top priorities of the application. Among the usual priorities of the control room displays are the following:
• Vision angle
• Brightness Uniformity
• self-polishing and color balance
• Absence of divisions
• Image retention
• Space occupied
• Initial cost
• Total Cost of Ownership
• Easy assembly
• Useful life
• Compliance with standards AD
We intend to discuss here what categories of technology offer above average compatibility in terms of their characteristics and thus help you choose the most convenient option for your application.
Most videowall solutions are designed to maximize the viewing information when the user is not located directly in front of the screen. However, the distancing of the viewing angle of the display found that the brightness and color can be affected at various levels. It is important to check in advance the performance specifications of the product to understand the impact of viewing angles in the interaction between a person and content.
Cubes, it is usual to use optical screens, and each screen type has its own characteristics. In the case of LCD panels, visibility could vary depending on who is the manufacturer. In the case of LED videowalls no clear rules; That said, there viewing distances recommended as best response to the pixel pitch (pixel distance). All solutions offer excellent viewing features, but selecting the product is important to ensure that the actual characteristics of the selected product meet the design requirements set for the application.
Brightness needs a videowall will vary depending on which will be the actual application. An environment with excess ambient lighting for example, a space with walls acristaladas- surely require high brightness that improves the overall contrast. However, in many applications control room too bright could be harmful for someone who spends a full working day in front of the display.
If the videowall is very bright, the operator could with the passage of suffering headaches or vision problems time; on the other hand, low gloss videowalls the contrast could be deficient, hindering the speed and precision needed to process information. In typical control room applications as indicated and reasonable is a nominal brightness of 250 cd / m². 500 exceed cd / m² could lead to an excess of brightness that we will be forced to reduce and manage.
If what we want is a stable brightness and uniformity across a tiled matrix, LED cubes are those that offer the best performance. LED display walls located outdoors reach peak brightness up 12.000 nits (nt = 1 1 cd / m²), although indoor models usually not exceed levels 2.000 nits. Another advantage of LED video wall tile is its ability to show clearly the content, even in high ambient light conditions.
And that is achieved not only by the high brightness of the LED characteristic cubes, but also by high contrast ratios. The result is an extraordinary perception of black level that causes a high-contrast image even indoors with high levels of ambient light.
When the brightness of each of the individual screens is not uniform global view of videowall could show an appearance of unwanted "chessboard". Most cubes provide a rate uniformity 95% or more, which is desirable; instead on the LCD panel uniformity is usually not as high.
In addition, since in LCD panels uniformity is not measured just at the level of the bezel, it is recommended to test and view in advance the solution with equal or similar to that content will show, and of ensuring that the product meets expectations in terms of uniformity. Average brightness uniformity in LED displays is> 97% or higher, depending on the specification of LED chip manufacturer.
Self-polishing and color balance
When in a tiled matrix displays or multiple displays in a video wall are combined, it is essential that the brightness and color between them are tightly coupled and remain stable. In an assembly of several displays, our eyes are extremely sensitive to color differences, however small they are.
That's why products for videowall displays incorporate aimed at precisely adjust color capabilities. However, with the passage of time both color and brightness may change and need of adjustment or readjustment. A great advantage of the cubes is that projection technology allows design series incorporate sensors and color monitor; with it, you can constantly monitor color and brightness, automatically readjusted without human intervention, which takes place continuously and without the user noticing.
The LED video walls also offer the possibility of achieving a broad spectrum of color, meaning the range and chromatic purity that a display is capable of playing. In an LED display, red, green and blue LEDs emit a range of wavelengths much smaller than that of a white light source and broad spectrum, like a lamp, which results in the reproduction of some colors much more deeply saturated as well as an increasingly wide range of reproducible colors.
A high contrast facilitates easier and faster recognition of the information displayed and reduces harmful effects on the eyes. An essential aspect in the design of a control room is the contrast ratio of the overall system, which should take into account the ambient light inside the room and the type of images that will show in the videowall. The contrast ratio is usually needed in a system is> 100: 1.
Display products have their own contrast ratio, used to determine the overall contrast ratio of the system. Fortunately, contrast ratios tend to be 1500: 1 in LCD panels, 5000: 1 2100 LED and videowalls: 1 cubes, all suitable for most applications control room cases.
Absence of divisions
In a display videowall ideally is completely free to make divisions in a matrix mosaic the viewer does not notice the transitions between different display units. The truth is that with emissive products and technologies currently for sale on the market is not a requirement that can be met to 100%.
In the cubes it is possible to minimize these transitions with distances between screens just 1 mm. That space is 1 mm which typically require materials that make up the screens to expand and contract by fluctuations in temperature and humidity. In large display walls, against which operators and users are placed usually about 3 meters away, that space 1 mm is considered negligible.
LED cubes if feasible get that absence of divisions, because its design allows physical contact between them without that result in an increase of the distance of pixels between a cube and the next. In addition, the environmental characteristics of a typical LED array cubes do not demonstrate accurately from a distance normal viewing, the junction between cubes.
Most likely a new videowall system we seem bright, but would be able to maintain that same level of brightness with time? If performance factors such as color consistency, uniformity of brightness and image quality are not among the top priorities of the application, the use of LCD panels may be an acceptable solution and the best in terms of value- price, especially if the application does not require operation 24 / 7.
However, if what matters is the quality of the image and maintaining that capacity for five or more years, LED DLP® based displays are the most appropriate solution. For example, in many operations centers is not only essential to keep functioning at a high level so that the usual operators and users to work at ease and safety, it is also important that the display videowall attractive and impressive for visitors and for customers who come for the facilities.
occupied space and ease of assembly
When there are space limitations at the site of videowall, the thickness of the solution could be a decisive factor. Usually most LCD panels required for installation of a space between 10 and 20 cm. deep. If space is scarce and also want the advantages of projection DLP / LED, DLP cubes or displays based on LED cubes will be the best option. Typically, the LED cubes are quite thin, often with thicknesses less than 4 "or 100 mm.
Similarly, its minimum depth profile and intelligent design, LCD panels, DLP LED cubes and cubes are also easy to assemble. An interesting aspect of both DLP LED cubes and cubes, is the ability to install curved or create a display with any size or shape.
initial and total cost of ownership
A big advantage of LCD panels is their low initial cost. In a display area of the cost of LCD panels may be less than 60% of the initial cost of an equivalent system based on cubes.
Fixed costs, such as derivatives of energy consumption, cooling or maintenance, are also important when deciding the most appropriate solution for our application. In a room 24 / 7 or 20 / 7 Control can be expected in cubes and LED tiles a shelf life of six or more years. These solutions are designed to deliver high reliability, low maintenance and minimal deterioration of performance over time.
All displays consume energy and require refrigeration needs that not all technologies solved the same way. The energy consumption of LED video walls cubes is more efficient than most other display technologies, with efficiency gains that can exceed 400% depending on what display do the comparison.
Another strong point of LED video walls cubes is the long life of the LED pixels themselves. Many times the life of a display light source is given by the number of hours it takes to fall to half its original brightness. Given that parameter, LEDs last much longer than the lamps either be used as a light source or directly as pixels on a LED videowall.
Compliance with the guidelines of the absence of barriers
If you want to make sure that your display complies with the guidelines of safe, accessible and barrier-free spaces of their country and the principles of Universal Design, it is best to decant for low-impact display and thin thickness.
In Canada and the United States can not be mounted displays more than 4 "or 100 mm wall if they are to be certified as free of barriers by the CSA (Canadian Standards Association) and ADA (Americans with Disabilities Act) respectively. LCD panels and LED cubes are solutions that fit well into spaces that have to comply with the requirements established by CSA, ADA or similar regulations.
Learning about the operation of each solution against the most common priorities in control rooms may get a clearer idea of what will work best in your own living solution. Once you have minimized the list of candidates, we recommend a thorough investigation of major brands to give the technology solution that best suits your needs.
* Juan Carlos Chavez Christie's director for Latin America.