Ten Tips for Designers Creating Digital Signage Hardware

June 7, 2012
Digital signage is much more than just billboards or posters. John Schilling delivers to digital signage designers ten tips on hardware design.

Digital signage is much more than just billboards or posters. Digital signage combines content from virtually any source and connects to a wide variety of displays for a highly impactful interactive communications experience. It can inform and influence audiences to promote products, provide directions, explain corporate benefits, reinforce branding, manage key performance indicators and much more.

Over the years, digital signage has become an effective tool for marketers and corporate communications professionals to reach consumers, employees and other stakeholders in multiple environments. One of the big drivers in growth of the digital signage market has been decreasing hardware costs. Prices of digital displays, players and other hardware components have gone down considerably and sparked adoption. Research from Intel projects there will be 10 million media players and a corresponding 22 million digital signs worldwide by 2015 (see 22 Million Digital Signs By 2015). The same research calls out retail, corporate and transportation as the top three sectors for digital signage expansion with healthcare and hospitality experiencing significant growth.

A typical digital signage hardware deployment includes digital displays, content management servers and digital signage players. These digital signage players run digital signage software and are responsible for transmitting information from content management servers to multiple displays. It is important to have good stable software on your players, but it's also important to have rock solid hardware.

This is where hardware designers come into the picture. A digital signage player is the heart of the hardware configuration which pumps content from servers to the screen. Here are ten tips designers can keep in mind while creating digital signage products:

Talk to Customers and Software Developers: A great starting point for a designer is to have conversations with customers and software developers to understand their requirements and objectives with digital signage installations. This process is critical to designing customer-centric products that align with the latest software developments.

Use Quality Components: Stability of hardware goes hand in hand with stability of software. Digital signage software is only effective if the supporting hardware runs without glitches. It is essential for designers to use high- quality, stable components in digital signage players. Cutting costs with low- quality, unreliable parts that result in system failures just shift expenses to later in the product lifecycle.

Graphics Quality Matters: The ability of digital signage to command attention is greatly dependent on the graphics capability of the digital signage player. This means the graphics systems of the players need to be sophisticated enough to display an MPG or H264 movie and do an overlay of alpha-blended, semi- transparent anti-alias text on top of that video. To deliver such a complex display, designers need to use quality, stable graphics components specifically manufactured for digital signage players.

Serviceability: It's critical for designers to keep in mind the serviceability of the digital signage player once it has been deployed. For instance, from a design perspective, centrifugal blowers mounted so as to be easily removed, in combination with heat-pipes and thermal spreaders, make for highly reliable cooling solutions that are generally better than using axial fans. We have seen instances where designers have buried smaller axial modular fans in a chassis in such a way as to require the removal of 25 screws and so can be cumbersome to deal with while servicing! Centrifugal blowers provide better quieter airflow cooling to the player and are also easier to service.

Another significant aspect of serviceability that designers need to keep in mind is related to hard disk drives. Hard disk drives are a major part of the digital signage player. That's where the digital software and the media files, which display content on the screens, are stored. In an event where the hard disk drive fails, it should be easy to remove the drive from the chassis of the player for servicing purposes. Most laptop hard disk drives are fitted in " caddies" with one or two screws for easy serviceability and a similar approach should be incorporated into the design of digital signage players.

Power Supply: If the power supply is internal, it needs to be built for reliability under the actual customer environment where it will be deployed. A digital signage player will oftentimes be placed in a 10 centimeter gap between a 550 watt plasma screen and a wall or the player will go into a tight little equipment closet. In both cases, there is limited airflow and elevated temperatures for the players. To address this environment, designers should use solid polymer caps over electrolytic capacitors. Solid polymer caps may be more expensive but have much better behavior over time under elevated thermal conditions.

If the power supply is external, friction fit connections from the power supply to the player are not really acceptable. The better approach is to have a positive interlock, which will help keep the connectors in place under stress or vibration.

Efficient Use of Graphics Processing Units (GPUs): A digital signage player is very similar to a gaming console which plays video games like Halo™ or Doom™. However, a key distinction is that those games are producing tens of thousands of polygons per second in 3D space. A typical digital signage would use a maximum of four polygons per 2D text character on the screen, so there are never more than a couple of thousand polygons on the screen. Designers can install a good quality GPU and downclock it for digital signage use. If you downclock the GPU by even 30 percent, you reduce the power consumption by 50 percent and more importantly you reduce the heat output by 50 percent. Taking this step can reduce the thermal design challenges for building the player.

USB Dongles: A large number of digital signage products today use USB security dongles to keep their software from being pirated. I recently came across a design for a digital signage player where the USB connecter for the dongle was on the inside the box instead of outside. It's a great design element, especially since the dongles are meant for security and nothing says "security" better than the connecter being inside the box in a secure location.

RS232 Port: Many players today only come with USB ports and have no support for RS232 connectors. In the commercial screen space, RS232 is still the dominant mechanism to control screens and video switchers. Designers should include the RS232 adapters in their players along with USB, as these connectors are much more reliable than the USB to RS232 converters that are available on the market.

Thin Player Design: There seems to be a general trend to make digital signage players too small. These players are usually fitted at the back of big plasma screens and making them small really doesn't help performance. Another idea designers should consider is using existing laptop design for players. Consumer laptops are built in volume and have the capacity for heavy graphics utility. Designers could save on tooling costs by using a standardized player VESA-mount chassis and adapting laptop printed circuit board assemblies (PCBA) to the stock chassis using mounting jigs and ribbon cables for the connectors. This way new PCBAs can be accommodated without substantial re-tooling work. Purchasing found a new PCBA? Just make a new set of jigs and cable harness!

Cable Traps: Digital signage players have a great number of cables going in and out of them. Using a cable trap is a simple but elegant design approach because they can hold the cables together in an organized fashion and also provide strain relief. This way cables don't get entangled, friction-fit connectors do not get pulled out, and the entire assembly is easy to work with if anything needs to be changed.

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