Modern control rooms will have to deal with a wider range of requirements than in the past. Process control will be accompanied by video streaming from CCTV and VC systems. Traditional video surveillance will be enhanced by analytical (PC type) data. Professional display solutions have to provide an optimum visual performance for both static images as well as video and in a variety of environments. AV News explores the factors which will influence your customers’ choice.
NEC’s Hiperwall visualises information from multiple data sources via video walls, projection solutions, large format displays and LED walls, in real-time. Thanks to its modularity and scalability, software upgrades and re-configurations of the display technology is done with minimum additional cost and time.
When your customers need to create a focal point of information for a control room team, in a format that allows operators to view multiple feeds of content clearly and simultaneously, “The entire design of control rooms has to support both the individual work of the operators, as well as collaboration and team work,” explains Dietmar Salewski, Sales Director – Energy, Utilities & Security at NEC Display Solutions GmbH.
“Complex situations require immediate access to all relevant information, in order to quickly analyse a situation, to maximise situational awareness and to take the appropriate swift action. Efficient decision-making is paramount. Information is increasing in volume, speed and variance. New types of automatic sensors and scanners deliver new types of inputs under real-time conditions. Big Data analytics is becoming more-and-more important.”
“Supervision, team work and collaboration are supported by video walls. These provide the necessary display canvas to reflect all relevant aspects of complex situations. Ultra-narrow bezels or even seamless screen surfaces, reliable and exact colour reproduction and perfect brightness adaption to the light conditions, support an optimum visual perception. The efficient work of every operator is supported by perfect working space ergonomics. The correct installation of the work place monitors are major drivers to ensure health conscious working environments.”
In essence, there are three primary categories of solid-state screen technology used for control room video walls: LCD panels, LED-lit DLP projection cubes and LED display walls (LED tiles). Today, you can add to this solid-state projection. While each of the available screen technologies can be a good choice for use in control room video wall displays, determining which type is most appropriate for a specific installation, or user, depends on what solution attributes are rated as top priorities for the project.
Selection criteria
There are a number of factors in recommending a control room technology for a project. The first is the viewing angle. Most video wall solutions are designed to maximize the view of information when the user is not directly in front of the display screen.
As you move further off-angle from the display, brightness and colour may be affected to varying degrees. It is important to verify the product performance specifications in advance, to understand how viewing angles will impact an operator’s interaction with the content.
For cubes, optical screens are typically used and each type has its own unique characteristics. For LCD panels, visibility can vary with each manufacturer. When referencing LED video walls, there are no hard and fast rules; nevertheless, there are recommended optimal viewing distances depending on the pixel pitch.
All solutions can provide very good viewing characteristics, but during product selection it is important to ensure the actual characteristics for a selected product meets the design requirements set for the application.
Brightness
Brightness requirements for video wall applications depend on the specific application and operating environment. Higher brightness may be necessary to improve overall contrast in environments where ambient light is very high – such as rooms with walls of windows. However, for many control room applications, too much brightness could be considered a downside if people are working in front of the display wall for a full working shift.
If the wall is very bright, those people may suffer from headaches or eye strain over time. On the other hand, if the wall is not bright enough, contrast will likely be too low, making it difficult to quickly and accurately discern information. For typical control room applications, a nominal brightness of 250 cd/m2 is considered adequate and reasonable. Above 500 cd/m2 may be too bright, necessitating lowering, or at least management of the brightness.
If you’re looking for brightness and uniformity across a tiled array, LED tiles offer the best performance for these attributes. Outdoor LED display walls can achieve peak brightness of up to 12,000 nits (1 nit = 1 cd/m2), although levels for indoor models are typically less than 2,000 nits.
LED-tiled video walls are highly regarded for their ability to display content clearly even in high ambience light environments. This is a consequence not only of the high-brightness typical of LED tiles but also of high contrast ratios. The result is an enhanced perceived level of black, resulting in a high contrast image even in elevated levels of indoor ambient light.
Uniformity
If brightness is not uniform within each screen, the overall video wall may exhibit a “checkerboard” appearance – obviously undesirable. Most cubes offer uniformity of 95% or better which is desirable, while LCD panel uniformity is not typically as high.
Because uniformity is not measured right to the edge of the bezel on LCD panels, it is recommended to test and view the solution in advance with content that is similar to that to be displayed, to ensure that the uniformity meets expectations. Brightness uniformity for LED displays is typically >97% or better, depending on the manufacturer’s specification for its LED chip.
When multiple displays are used together in a tiled display array or video wall, it is critical that brightness and colour, from display to display, are well matched and remain that way over time. Eyes are very sensitive to even subtle differences in colour across multiple displays and so video wall display products include capabilities to finely adjust the colour for best matching performance.
Over time colour or brightness may drift, requiring re-adjustment. A major benefit of cubes is that projection technology allows colour sensors and monitoring to be embedded within the design. Colour values and brightness can be constantly monitored, and automatically re-adjusted, without human intervention. This occurs continuously and is transparent to the user.
Consistency and contrast
The red, green and blue LEDs, used in LED display walls, emit a much narrower range of wavelengths than a broad-spectrum, white-light source like a lamp. This allows more deeply saturated colours to be reproduced, as well as increasing the range of reproducible colours.
Salewski adds: “LCD offers highly accurate colour consistency with hardware calibration bringing precise colour fidelity and uniformity. Thanks to laser light source technology, long lasting colour accuracy and brightness consistency can be achieved through projection. That advantage enables the new generation of installation projectors to become part of the display equipment portfolio in modern control rooms.”
Dietmar Salewski, Sales Director – Energy, Utilities & Security at NEC Display Solutions GmbH: “Complex situations require immediate access to all relevant information, in order to quickly analyse a situation, to maximise situational awareness and to take the appropriate swift action.”
Higher contrast enables easier and faster recognition of the information displayed, and reduces eye strain. For control room design, the overall system contrast ratio is critical. This takes into account ambient lighting within the room as well as the imaging within the video wall display. Typically, a system contrast ratio of >100:1 is required.
Display products themselves have their own contrast ratio which is used to help determine the overall system contrast ratio. Fortunately, the contrast ratios are typically 1500:1 for LCD panels, 5000:1 for LED video walls, and 2100:1 for cubes and so acceptable in most control room applications.
Seamlessness
Ideally, a video wall display should be completely seamless so that viewers do not notice a transition from one display screen unit to the next in a tiled array. In reality, this is not 100% achievable with emissive display products and technologies currently on the market.
Salewski explains: “14 years ago, NEC was the first vendor to market LCD Public Displays, at this time with quite thick bezels. Accordingly, Rear Projection Cubes had a significant advantage compared to LCD. Meanwhile, we have seen the wide introduction of Ultra-Narrow bezel displays for Video Wall applications. The trend in favour of even thinner bezels and LED backlights reducing heat emission will support that change of technology. “
“Today, Fine Pixel Pitch LED displays offer an additional alternative to rear projection. Whilst high resolution projectors have also started entering the control room display mix. As a hardware agnostic manufacturer, NEC provides its customers tailor made solutions according to their requests – no matter if it’s LFD Video Walls, LED walls or Laser projection. All technologies offer specific advantages and meet the needs of different applications.”
Cubes have the ability to minimize this transition by offering a gap between screens of only 1mm. This 1mm space is typically required to allow for expansion/ contraction of the screen materials during temperature or humidity fluctuations. For large display walls where operators and users are typically at 3 meters (10 feet) away, 1mm is considered negligible.
LED tiles achieve seamlessness and are designed in such a way that they touch each other without increasing the distance between the pixels from one tile to the next. Moreover, the nature of the area surrounding LEDs in a typical tiled array makes it difficult to see where the tiles join from a normal viewing distance.
Constraints
When choosing a control room display technology, the physical depth of the solution may be a key deciding factor. Generally, most LCD panels can be installed requiring only 4-8″ of space front to back. If space is at a premium, but the benefits of DLP/LED projection can be the right solution. Christie MicroTiles or LED display tiles then may be the best option. MicroTiles offer the benefits of DLP/LED projection cubes with a 10″ depth. LED tiles are typically quite thin, often with a depth of less than 4″ or 10mm.
Depending on the location of your project, you might find (for example in the United States or Canada) that there are safety regulations governing the extent to which displays can protrude from the wall. With their minimal profile depth, LCD panels, MicroTiles and LED tiles can offer ease of deployment and conformity with regulations. The ability to mount tile along a curve, or to create any size or shape of display, is an increasingly popular solution where customers want their control room to make an impression.
Investment
But no-one can describe these impressive displays as cheap. Perhaps the biggest benefit of LCD panels is their low initial price. For a given display surface area, LCD panels can be less than 60% of the initial cost of an equivalent cube-based system. Although operational lifetime is lower and there are other performance compromises, LCD panels could be the most appropriate solution for the application at hand when budgets are tight.
There are other factors to consider when looking at the Total Cost of Ownership and the Return on Investment. If image performance factors such as colour uniformity, brightness uniformity and imaging quality are not the highest priorities for the application, then the use of LCD panels may be acceptable and the most cost-effective solution – especially if the application does not require 24/7 operation.
However, if quality of the image is important at all times for five years or more, then DLP/LED-based displays might be the best choice. For instance, in many operation centres, it is not only critical that a high level of performance is maintained for the benefit of the normal operators and users, but it is also important that visitors and customers who tour the operations see an engaging and impressive video wall display.
Operational costs
Considering the on-going operational costs such as power consumption, HVAC and maintenance is also important in determining the right solution for your application. In a 24/7 or 20/7 control room you can expect cubes and LED tiles to have a useful life of approximately six years or more. These solutions are designed for high reliability, very low maintenance and minimal performance degradation over time.
All displays consume power and require cooling, but not all display technologies are the same in this regard. LED tile video walls consume energy more efficiently than most other display technologies. The improvement in efficiency can be as high as 400% or more, depending on which displays are being compared.
Another strength of LED tile video walls is the long life of the LED pixels themselves. The useful lifetime of a display’s light source is often defined as ‘the number of hours to reach half of the initial brightness’. By this measure, LEDs typically last much longer than lamps, whether used only as a light source or employed directly as pixels in an LED video wall.
Readability
For close-up viewing (proximity viewing), resolution is key. 4K UHD is highly recommended for short viewing distances for detail rich content and pixel-free viewing.
The Ultra High resolution is available either with UHD Large Format Displays or naturally with LFD Video Walls. Of course, it is highly recommended to equip operators’ desks with desktop monitors which also support UHD.
Projection also now offers an alternative technology with 4K resolutions now being achieved and offering benefits over LCD technology by delivering larger image areas with no bezels.
LED modules are providing pixel pitches that are getting smaller and smaller and which are also perfectly suited for indoor use and relatively short viewing distances as often realized in large Theatre-style Control Rooms.
Whatever the display technology is, only an excellent visual performance in terms of resolution, stable and consistent brightness, smooth gradation of grey tones and colours in image reproduction will suffice in this mission critical environment.
Even at short viewing distances, NEC doesn’t only provide more pixels, but also better pixels, and being in the unique position to be able to offer all display technologies, NEC can advise on the most appropriate according to the application.
Completing the solution
Any control room involves a complex system where visualisation is a vital part, but Salewski argues that this must be supported in order to achieve the best result: “In order to support our customers to get the most outstanding visual performance from our display solutions, we offer additional options which are designed and tested for maximum compatibility to our display products.”
“Wall and ceiling mount solutions, a wide range of OPS option slot modules and the excellent connectivity of our display products offer our partners and end customers maximum flexibility in design and realization of control room solutions. The proven flexibility in terms of easy adaption to future needs is an additional advantage.”
Ian Abernethy, Director of Sales, UK, Peerless-AV says: “Mounts are a vital part of an installation and specifying the right mount with the required functionality for the project is even more important since it will very often save time and money on site. Our full service quick release mounts also allow for unlimited video wall configurations and their long life-time means that when it’s time to upgrade the screens, the mounts can remain.”
“A further invaluable feature of our full service mounts is their handy keyhole slot wall plate design, which simplifies video wall mounting even further, resulting in decreased costs through reduced manpower and time spent on site. Using this tool, installers can have a 3×3 video wall set up in under 30 minutes, presenting obvious advantages in terms of location flexibility and adaptability to change.”
Since control room operations are mission or business-critical environments, AV technology needs to meet strict standards for 24/7 reliability, flexibility, ease of maintenance and long-term performance. Installers are looking for products that have a consistent design and work perfectly first time. In such large-scale, complex application environments where there is no room for error, downtime must be kept to an absolute minimum. Products must be installer-friendly, offering easy installation, and convenient access for servicing and maintenance.
