Each control room requires a certain videowall: how to choose the most suitable?

There are three main categories of solid state technology used in control room video walls: LCD panels, DLP projection cubes of Led lighting and Led display walls. In this article, Mark Fernandez, Christie director for Spain and Portugal, explains the functionalities of each of them and which one best suits each specific application or user, taking into account the characteristics of each environment.

Receive information, do analysis, collaborate to maintain normalcy or respond to emergency situations: that's the day-to-day of control room environments. To carry out these tasks, the challenge is how to visualize in real time and efficiently the follow-up tasks, verification and communication that these tasks require. To establish with what technology to support people who manage and monitor the continuity of work and respond to actual or potential breaches of protocol, it is critical to determine where and how the information will be displayed.

If what is needed is to create an information focal point for a control room equipment, especially in large formats, that allows operators to clearly and simultaneously view multiple feeds of content, videowalls are the general solution.

There are three main categories of solid state technology used in control room video walls: LCD panels, DLP projection cubes of Led lighting (Christie MicroTiles cubes) and Led display walls (Led cubes).

Any of the three technologies can be an excellent option for use in video wall displays, but to decide which category will be best suited for a particular application or user, we will have to look at which characteristics of each solution meet the main priorities of the application. Among the usual priorities of control room displays are: the viewing angle, brightness, brightness uniformity, contrast, autobrillo and color balance, absence of divisions, image retention, space occupied, initial cost, total cost of ownership, ease of assembly, power, service life and compliance with AD standards.

In this column we will discuss which technology categories offer above-average compatibility in terms of their features to help choose the most appropriate option for each application.

Viewing angle

Most videowall solutions have been designed to maximize the viewing of information when the user is not located right in front of the screen. However, by distancing ourselves from the viewing angle of the display we verify that brightness and color can be affected at various levels. It is important to consult the product's operating specifications in advance to understand the impact of viewing angles on the interaction between a person and the content..

With cubes, the usual thing is to use optical screens, and each has its own characteristics. In the case of LCD panels, visibility may vary depending on who the manufacturer is. In the case of Led videowalls there are no clear rules; that said, there are viewing distances recommended as optimal according to the pixel pitch (pixel distance). All solutions offer excellent display features, but when selecting the product it is important to ensure that the actual characteristics of the selected product meet the design requirements raised for the application.

brightness

The brightness needs of a videowall will vary depending on what the real application will be. An environment with excess ambient lighting—for example,, a space with glazed walls—will surely require a high brightness that improves overall contrast. nevertheless, in many control room applications an excess of brightness could be harmful to 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 time, having headaches or vision problems. On the other hand, if it has low brightness the contrast could be poor, hindering the speed and accuracy needed to process information. In typical control room applications, what is indicated and reasonable is a nominal brightness of 250 cd/m2. Exceed the 500 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 throughout a mosaic matrix, Led cubes are the ones that offer the best performance. Led display walls located outdoors reach brightness peaks of up to 12.000 Nits (1 nt = 1 cd/m2), although in indoor models the levels do not usually exceed 2.000 Nits.

Another advantage of led video walls in mosaic is its ability to clearly display the content, even in conditions of high ambient light. And that is achieved not only by the high brightness characteristic of Led cubes, but also because of the high contrast ratios. The result is an extraordinary perception of the black level that causes a high image contrast, even indoors with high levels of ambient lighting.

Brightness uniformity

When the brightness of each of the individual screens is not uniform the global vision of the videowall could show an unwanted appearance of 'chessboard'. Most cubes offer a uniformity rate of 95% Or more, what is desirable. instead, on the LCD panel uniformity is usually not so high.

In addition, since in LCD panels uniformity is not measured fairly at the level of the bezel, it is recommended to do a test and view in advance the solution with content equal to or similar to the one we are going to show, thus ensuring that the product meets the expectations in terms of uniformity. The average brightness uniformity in Led displays is >97% or higher, depending on the manufacturer's Led chip specification.

Autobrillo and color balance

When in an array of mosaic displays or in a video wall multiple displays are combined, it is essential that the brightness and color between them are well coupled and remain stable.
In a set consisting of several displays, our eyes are extremely sensitive to color differences, however minimal they may be. That is why the products for videowall displays incorporate capabilities aimed at adjusting the color with precision. However, over time both color and brightness may become misadjusted or changed and need readjustments..

A great advantage of the cubes is that the projection technology allows sensors and color monitoring to be incorporated as standard into the design.. With it, can constantly track color and brightness, that readjust automatically without human intervention, something that takes place continuously and without the user noticing it.

Led videowalls also offer the possibility of achieving a wide spectrum of color, understanding by such the chromatic range and purity that a display is able to reproduce. On a Led display, the reds, greens and blues emit a much narrower range of wavelengths than a broad-spectrum, white light source, like a lamp, resulting in the reproduction of much more deeply saturated colours as well as an ever wider range of reproducible colours.

Contrast

High contrast facilitates easier and faster recognition of displayed information and reduces detrimental effects on eyesight. An essential aspect in the design of a control room is the contrast ratio of the overall system., that must take into account the ambient light inside the room as well as the type of images to be shown on the videowall. The contrast ratio that 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 are usually 1500:1 on LCD panels, of 5000:1 in led videowalls and 2100:1 in cubes, in all cases suitable for most control room applications.

Absence of divisions

In a videowall display, the ideal is that it is totally free of divisions to ensure that in a mosaic matrix the viewer does not notice the transitions between the different screen units. The truth is that with the emissive products and technologies currently on sale in the market it is not a requirement that can be met when 100%.

In cubes it is possible to minimize these transitions with distances between screens of only 1 Mm. This space of 1 mm is the one that usually needs the materials that make up the screens to expand and contract due to fluctuations in temperature and humidity. On large display walls, compared to which operators and users are usually placed at 3 meters away, that space of 1 mm is considered insignificant.

With Led cubes it is feasible to achieve that absence of divisions, because its design allows physical contact between them without that resulting in an increase in the distance of pixels between one cube and the next. In addition, the characteristics of the environment of the Led cubes of a typical matrix do not allow to appreciate with precision, from a normal viewing distance, the point of attachment between cubes.

Image retention

Most likely, a new videowall system seems brilliant to us, but, Will it be able to maintain that same level of brightness over time?? If performance factors such as color uniformity and brightness, and image quality are not among the top priorities of the application, the use of LCD panels can be an acceptable solution and the best in terms of value for money, especially if the application does not require operation 24/7.

However, whether it is the quality of the image that matters and the maintenance of that quality for five or more years, DLP displays based on Led are the most suitable solution. For example, in many operations centers it is not only essential to maintain operation at a high level so that operators and regular users work at ease and safely, it is also important that the videowall display is attractive and impactful for visitors and for customers who come through the facilities.

Occupied space and ease of assembly

When there are spatial limitations in the location of the videowall, the thickness of the solution could be a decisive factor. In general, most LCD panels require a space between 10 and 20 cm. depth. If space is scarce and the advantages of DLP/Led projection are also desired, DLP cubes or displays based on Led cubes will be the best option.

The Christie MicroTiles solution offers the advantages of DLP/Led projection cubes with a depth of 10 inches or 250 Mm., because it has a screen size of 20 diagonal inches. The usual thing is that the Led cubes are quite thin, often with thicknesses less than 4 inches or 100 Mm.

The same, for its minimum depth profile and intelligent design, LCD panels, DLP cubes and Led cubes are also easy to assemble. An interesting aspect in both is the possibility of installing them in curve or creating a display with any type of size or shape.

Initial cost and total cost of ownership

A great advantage of LCD panels is their low initial cost.. On a display surface the cost of LCD panels may be lower than 60% of the initial cost of an equivalent cube-based system. When there are budget constraints, LCD panels can be the most appropriate solution even if their operating life is shorter and some operating sacrifice has to be made..

Fixed costs, such as those derived from energy consumption, cooling or maintenance, are also important when deciding on the most suitable solution for the application. In a control room 24/7 or 20/7 led cubes and mosaics can be expected to have a service life of six or more years. These solutions are designed for high reliability, low maintenance and minimal performance deterioration over time.

All displays consume energy and require cooling, needs that not all technologies solve in the same way. The energy consumption of Led cube video walls is more efficient than that of almost all other display technologies, with efficiency improvements that may exceed 400% depending on which team we make the comparison with.

Another strong point of led cube video walls is the long life of the Led pixels themselves. Many times the lifespan of a light source model is given by the number of hours it takes to drop to half its initial brightness.. Taking into account that parameter, Leds last much longer than lamps, whether they are used as a light source or directly as pixels in a video wall.

Compliance with barrier-free guidelines

If you want to make sure your display meets the safe spaces guidelines, accessible and barrier-free from your country and the principles of Universal Design, the best thing will be that it opts for a display of low impact and thin thickness.

In Canada and the United States, displays cannot be mounted to more than 4 inches or 100 mm of the wall if they aspire to be certified as barrier-free by the CSA (Canadian Standards Association) and the ADA (Americans with Disabilities Act), respectively. LCD panels and Led cubes are solutions that fit well in spaces where the requirements established by CSA have to be met, ADA or similar regulations.

By informing yourself about how each solution works in relation to the most common priorities in control rooms, you can get a clearer idea of which solution will work best in your own room.. Once you have reduced the list of candidates to a minimum, we recommend you to do a thorough investigation of the main brands to find the technological solution that best suits your needs.

Mark Fernandez

Director of Christie for Spain and Portugal

 

 

 

 

 

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