Choosing the Right System

In addition to the pixel pitch, a number of factors go into specifying the optimal LED display for a given project.

While cost is always a noted consideration, the level of available product support and the extent of the warranty are perhaps equally important to architects and building owners.

Another important factor is the speed at which the product can be assembled. “Time is money, especially on a building site or for installations where disruption to ongoing business operation needs to be kept to a minimum,” states the audiovisual integrator Corporate Initiatives Australia in an LED display white paper for architects and designers. “The best LED products for permanent installation are therefore designed to be easy to put together in a precise manner.”

Maintenance is another issue that must be evaluated. The majority of LED display systems are serviced from the front, which enables easy accessibility. For those that are serviced from the rear, the design will require that additional space be incorporated between the display and the wall for maintenance access, or a complex mount structure is required that allows the display to extend out from the wall for service.

“The ease at which the servicing can be carried out is also a cost factor,” states Corporate Initiatives Australia. “Display systems that are well designed for access make such servicing simpler to accomplish.”

Facility maintenance teams should consider the LED manufacturer's replacement parts and training for the control system. In cases where maintenance to the face of the display is required with a module replacement, it is essential to replace the module with a spare specifically made for that display. The team must then know how to adjust the calibration software, in order to correctly adjust the settings for the new module to disappear into the matrix of the display.

The AV integrator also points out that a typical product procurement process involves developing a series of specifications and drawings, documenting what is required, and putting the whole thing out to bid. However, due to the nature of LED displays as an emerging technology, it is preferable to treat the display as a separate package and make the call on specification much closer to the realization date.

“Nothing is sadder than an LED screen being installed that is effectively already out of date on the day of installation, especially when it happens on a very large scale,” states the white paper.

To better ferret out the LED needs of the project, the following questions should be addressed:

• What is the desired display dimension?
• Where will the display be located, i.e., indoors versus outdoors?
• What is the distance between the display and the viewing audience?
• How bright is the surrounding environment?
• How high off the ground is the bottom of the display?
• What type of content will be displayed, i.e., still images, presentations, video?
• What is the resolution of the native content being sent to the display? Is a scaler required to convert video signals from one display resolution to another?

In determining the size, an indoor LED display is made of interlocking cabinets. These cabinets have traditionally been square shaped measuring 500 millimeters. In the past several years, cabinets measuring roughly 600 millimeters wide by 340 millimeters tall have been introduced, representing a 16:9 aspect ratio. So each increase in size is done by adding modules of these dimensions.

Incidentally, the 600-millimeter by 340-millimeter dimension produces a 27¹⁄₂-inch diagonal cabinet. By doubling both dimensions, this yields a 55-inch cabinet, which is the same size as an LCD video wall cabinet. Consequently, an LCD video wall comprised of 55-inch LCD cabinets can easily be retrofitted with an LED display using these 27¹⁄₂-inch LED cabinets.

On the issue of placement, it is important to consider the fact that the LEDs on the face of the modules are very fragile. While the LEDs can be encapsulated with an optically clear coating to improve their ruggedness, this compromises the display’s ability to vent off heat. Further, if an electrical connection comes loose within the encapsulation, the entire module will require replacement, whereas with non-encapsulated LEDs, like DIP and SMD LEDs, it is possible to solder and reconnect individual connections within a module.

In any case, it is best practice to locate the display out of reach from the general public.

Photo courtesy of Draper Inc.

The modular nature of LED cabinets means a video wall can be in any configuration; it does not have to conform to traditional formats, such as 16:9. It can be 2 high and 10 across, or taller than it is wide.