SCADA Control Room Wall Display
Choosing a Display Type
Whether you are updating an existing system or building one from scratch, you need to choose a display wall setup that fits your organization’s needs and budget. While both LCD?and?LED?displays are flat panel screens that exhibit a bright, high-definition picture, knowing the features and benefits, considerations, and typical use cases is key to making an informed decision. Let’s explore the most popular options.
General Control Room Requirements
Control Rooms monitor and control various processes, applications and networks. In most applications, Control Room operators are responsible for recognizing potential problems and initiating responsive actions. The return on investment for a control room video wall is correlated to the fulfilment of a set of key criteria, and a few details can easily determine the success or failure of a project. For example, the size of the characters relative to the operators’ distance are to be carefully considered when designing a control room environment according to ergonomic principles. The choice of the right video wall display technology is a major decision, but also, for a given technology, the video wall design has to provide the standard of quality that will make a control room project successful in the long-term. The most valued features for control room video walls include
LCD
LCD panels (Liquid Crystal Displays) are composed of two polarized pieces of glass surrounding a layer of liquid crystals. Liquid crystals themselves aren’t light-emitting, so standard LCDs feature their own backlighting array that shines through the arrangement of liquid crystals to create the display’s picture.
Since it's introduction in the late 2000s, tiled LCD has proven to be a viable video wall solution for control rooms. The main benefit is simplicity to implement and service, as well as its small footprint. Major disadvantages are larger bezels and a shorter lifetime. The power consumption for tiled LCD per sqm and for a given brightness is higher than the other video wall technologies. This is inherent to LCD technology where LED backlight is filtered by polarizers. Off-Board Electronics Design Since its public launch in 2009, the Clarity? Matrix? LCD Video Wall System’s advanced design seeks to make the best of the tiled LCD technology for control room applications. Thanks to its external power supply and video controller, the advanced design of Clarity Matrix addresses most of the concerns with LCD technology for control room applications.
Advantages
Due to their high pixel density, LCD panels provide some of the highest total resolutions of any of today’s display technology. LCD video walls can display text, images, and video in extremely sharp detail.
LCD displays are extremely reliable and support 24/7 operations for years on end with no downtime. These panels are composed of solid-state electronics and have no consumable parts so they’re also very resilient to environmental stressors like vibration, humidity, and UV light.
This type of technology requires minimal maintenance and boasts both low power consumption as well as long lifespans. These factors mean LCDs offer a very low total cost of ownership. When considering a long-term investment, they are one of the most affordable display options.
Disadvantages
LCD display panels require a thin outside edge called a bezel. When LCDs are tiled together to create a video wall, these bezels form seams that are visible between the individual panels. They may be distracting in certain situations like digital simulations, or in cases where highly detailed content such as charts or graphs are required.
Fortunately, manufacturers reduce bezel width with each new generation of displays.?LCD displays?with bezels as narrow as 1.8mm are available today.
In applications where static images are displayed for an extremely long time, LCDs can experience?image retention. This occurs when the liquid crystals develop a “memory” for the position they’ve been holding and fail to shift again when the image is finally changed. Thankfully image retention is minor and/or temporary in most cases.
LED
LED (Light Emitting Diode) or Direct View LED (DvLED) panels are similar to LCDs. However, unlike LCDs, LEDs use an array of light-emitting diodes as individual pixels across the entire display. Hundreds and hundreds of light-emitting diodes across the display are grouped in clusters of red, green, and blue which provide their own light while producing the required image.
Direct view LED?is typically called “LED” for short, which stands for light-emitting diodes. LED has emerged as an exciting new indoor video wall display type in recent years. However, LED technology isn’t actually new. It's been around for decades in large, outdoor signage. In the past they lacked the resolution needed for close-proximity indoor visualization. All of this changed with the development of very small diodes that allowed manufacturers to produce much higher-resolution LED display panels. Today, direct view LED is one of the most desired display options for indoor video wall systems.
How Do LEDs Works?
An LED display consists of hundreds of tiny light emitting diodes mounted directly on a flat panel. Each LED is basically a miniature lightbulb that emits colored light when a particular voltage is applied to it. Clusters of red, green, and blue diodes are grouped to create the full-color pixels needed to produce an image. Since the LEDs themselves produce the pixels, the size of the LEDs and the distance between them (known as “pixel pitch”) determines the resolution of the display. Displays with very small LEDs and a fine pixel pitch will produce higher resolutions than displays with bigger LEDs and a large pixel pitch. However, these higher-resolution displays are also dramatically more expensive.
LED video walls?are built from a tiled array of LED displays. Some displays come with a mounting system built in, while others require the use of a separate mount. The narrow profile of LED displays allows for virtually limitless mounting options, including freestanding, wall-mounted, ceiling mounted, curved, and more.
Direct view LED technology is gaining interest in the control room environment and is rapidly growing market share over the other two technologies. The main benefit of LED technology is the total absence of visible separation between the displays, providing a truly seamless and uniform video wall canvas.
Common Applications of Direct View LED
Advantages
Direct view LED offers the highest maximum brightness of all leading display technologies. This makes LED an excellent solution for spaces with significant ambient light.
These displays are very robust and reliable. They can withstand a wide range of temperatures and humidity levels and expected lifespan of most LED displays is similar to that of LCDs.
Since LED displays have no bezels, they can be tiled together to create a completely seamless display canvas. Therefore an LED video wall provides an immersive, high-impact visual experience.
Disadvantages
While current indoor LED panels provide far higher resolutions than older models, they are still much lower-resolution than other display options like LCD or rear projection. These higher-res display types are therefore still preferable for situations where highly-detailed content must be viewed at close-proximity.
Although prices have dropped in recent years, the price-point of higher-resolution LED displays is currently several times the price of LCDs. The upfront cost difference puts this technology out of reach for many customers.
Rear Projection Video Walls
Like LCDs, rear projection displays, or "cubes," are an enduringly popular display option. This display type has existed for many years and is available in a range of sizes and resolutions. Rear projection is the historical video wall solution for control rooms. It has benefited from many improvements over 20 years of existence and is now a very mature technology. Among the critical milestones of the evolution of rear projection that are now widely accepted as absolute standards.
How Do Rear Projection Cubes Work?
A rear projection display consists of a projection system and mirror encased in a sealed cube. The cube enclosure is used to limit the effects of ambient light and improve the brightness and contrast levels of the displays. Inside the cube the projector shines light onto a mirror, which then reflects it onto the display screen to produce an image.
A projection cube video wall is built by stacking multiple cubes on top of each other in a tiled array. Cubes can be arranged in flat, curved, and even non-rectangular arrays. While they are generally too heavy to be wall-mounted, they can be built into a recessed space so that the display surface is flush with the surrounding wall.
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Common Applications of Rear Projection Cubes
Blended Projection Systems
Blended projection systems combine the output of multiple projectors to produce an image that is larger and/or displayed at a higher-resolution than could be generated by a single projector. These systems can display content on a completely seamless surface of virtually any size and shape.
How Blended Projection Works
Blended projection works by overlapping two or more projected images and gradually cross-fading their edges to produce a single, seamless image. A blended projection system can be designed with rear or front projection. In a rear blended projection system, the projectors are placed behind the screen in an enclosed room, where they either project light directly onto the screen, or onto mirrors that then reflect it onto the screen. In a front blended projection system, the projectors are mounted in front of the screen surface and reflect light directly onto it.
Instead of tiling together multiple displays like an LCD or LED video wall, a blended projection system blends the output of multiple projectors to create a large display surface.
Common Applications of Blended Projection
Advantages
Blended projection systems produce a completely seamless display surface. This makes them an excellent solution for immersive applications such as during high-resolution simulations.
A blended projection system can produce images on curved, angular, or even spherical surfaces with some additional image mapping and processing.
When using several very bright projectors, these systems produce extremely large display surfaces that still appears bright and sharp. Since the size and resolution of the image depends only on the type of projectors and number used, the display surface can theoretically be as large as desired.
Disadvantages
Ambient light heavily impacts the brightness and contrast ratios of a blended projection system. Systems designed with front projection are especially vulnerable to any light in the space and may require very bright projectors to produce sufficient contrast ratios.
Rear projection systems take up a lot of space. They require a large, enclosed room to house projectors that require up to 14 feet of floor space. Space is not an issue with front blended projection systems since the projectors are mounted in front of the display screen and don’t need to be enclosed.
Compared to tiled systems like LCD, LED, and cubes, blended projection is costly and labor-intensive. This makes it difficult and costly to scale over time. Significant changes must be made to projector placement and lens alignment, and the projectors often need to be replaced completely. The screen must also be replaced since a larger display surface will be required.
Laser Phosphor Display
Like OLED, Laser Phosphor Display (LPD) technology combines traditional technology with new components. First brought to the market by Prysm, Inc. in 2010, LPD employs a variation on cathode ray tube (CRT) technology, the system used in traditional tube televisions. LPD adapts this technology by using lasers instead of an electron gun to excite phosphors and produce an image. In an enclosed arrangement similar to a projection cube system, a set of movable mirrors reflects light from ultra-violet lasers onto a screen. The screen is made of a plastic and glass hybrid material and is coated with colored phosphor stripes. As the reflected lasers scan the screen from top to bottom, the energy from their light activates the phosphors, which emit photons, producing an image (Greene, 2010). Multiple LPD cubes, or tiles, can be stacked and arranged in various configurations to create a large scale video wall.
Like projection cubes, LPD tiles feature narrow seams, which measure only 0.5 mm in some models. However, unlike cube displays, which may measure up to 80” diagonally, LPD tiles offer a surface area of only 25”. Thus, while an LPD video wall will have narrower seams, it will also have many more seams than competing technologies. The pixel density of LPD displays is lower than many competing technologies, with a 25” display surface providing a maximum resolution of 427 x 320 (Prysm, 2013).
In terms of visual performance, LPD offers some notable advantages. LPD displays provide far better color reproduction than competing technologies. The unusually wide color gamut produced by this technology enables LPD panels to display 98% of the 24-bit color available from graphics cards. As a reflective technology, LPD displays are not as bright as LCD or emissive technologies like direct view LED and OLED. Some amount of ambient light control will be necessary to prevent images from being washed out. However, because the speed of the lasers enables pixels to be shut off individually, LPD provides excellent contrast ratios and black levels. LPD technology also 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 LED-based projection cube system. Because current LPD tiles are only rear-serviceable, a minimum clearance of 31.5 inches is required behind the displays to enable maintenance (Prysm, 2013). One positive aspect of this rear-serviceable design is that it enables the tiles to be more easily configured for touch interactivity. Like LED-based 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 solid-state electronics, so??regular downtime should not be necessary. Provided that no maintenance issues arise, the long-term cost of ownership for an LPD video wall may be quite low. However, because the first LPD systems were installed only four years ago, there is little information available thus far on the long-term performance and maintenance requirements of this technology. In terms of life span, LPD technology has not yet been thoroughly time-tested.
While similar phosphor-based display systems like CRT have proven durable and long lasting, the longevity of the laser component in LPD has not yet been established. The latest LPD tiles advertise an MTBF of 60,000 hours at 24/7 operation, a shorter life span than LED-LCD and LED projection cube technologies, which may offer MTBFs of up to 100,000 hours at 24/7 operation. Because laser phosphor technology is still quite new, little is known about long-term performance and the range of options available to consumers is limited. However, as LPD continues to be tested and refined, it may emerge into the mainstream to compete more closely with LCD and cube technologies.
Conclusion
Selecting the ideal video wall display type can be a challenging task. An enormous range of display technologies are available, each with their own unique characteristics, strengths, and weaknesses. Neither option is uniformly better than the other, and your specific use case will be a major factor in what you ultimately choose. It’s important to partner with the right?video wall solutions?provider to help guide you down the right path.
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