When consumers purchase big ticket items such as cars, they often do their homework first. It's common to consult publications like Consumer Reports and websites such as KBB.com to look at the cost to own and repair vehicles, any recalls the manufacturer has issued, safety scores and a history of reliability.
It's not as easy when purchasing a digital sign, which can cost as much or more than a new car and is a crucial marketing tool for businesses.
There is a handy tool, though, that can help business owners gauge the reliability of digital signs and help ensure they make a smart investment. Mean Time Between Failures is a concept that was first developed to measure reliability in the 1940s for military applications. However, in the early stages of the telecommunications field, AT&T didn’t accept the R&D standards for telecommunications that were born in the military. It contracted with an outside firm to design a more applicable reliability standard for their commercial telecommunications products. That standard became known as Mean Time Between Failures, otherwise known as MTBF. This same standard can also be applied to LED signs.
MTBF has become the gold standard for evaluating the design of electronic products and projecting how many hours will pass between failures. A longer time between failures is preferred, so the higher the MTBF score the more reliable the product is expected to be.
Digital signs with high MTBF scores are manufactured with three common traits:
MTBF standards tell us that every single connection in an electronic device is a potential point of failure. When designing for quality and longevity, an electrical engineer looks to reduce connection points, which in turn increases reliability. It's like a teeter-totter: as connection points go down, projected reliability goes up.
Digital signs can vary dramatically in the number of connection points. For example, a 14-inch by 48-inch display by one U.S. manufacturer is made up of 611 modules. Each module has 11 pins, including a data hub that connects multiple modules to the display’s controller. This brings the total number of connections to 6,721 across the entire sign. A different manufacturer of the same size display uses just 552 modules, but the design calls for a complex system of cabling with 71 pins per module, or over 39,000 connections. Using MTBF standards, this increases the number of connection pins fivefold and raises the likelihood for failures in the field by more than 30 percent.
Likewise, the number of cables used by different manufacturers can impact MTBF scores. Designs that send high speed data signals from a receiver card to the module over cables contain more potential points of failure than signs using "smart modules."
The quality of components can also raise or lower MTBF scores. Since digital signs are installed outdoors in harsh elements, signs that use high grade automotive connectors instead of insulation displacement connectors tend to fail less frequently. Insulation displacement connectors are ribbon-type cables like those found in home computers. They are not designed for use in outdoor conditions and can be easily damaged by field service personnel.
Before investing in a digital sign, business owners should ask for an MTBF score for the particular size and model of signs they are considering purchasing. Keep in mind that MTBF increases as the opportunity for failure decreases. Also, consider the entire cost of ownership before deciding. Lower cost displays often use lower grade components and designs with a high number of connection points. Both can lead to costly outages and repairs, and a shorter product life.