Electronic message centers and the technologies they are built on continue to evolve at a tremendous pace. Fundamental shifts in LED diode technology as they relate to applications within the sign industry are as relevant as ever to industry practitioners. Technology is driving changes at the component level, but simultaneously—and in a more impactful way—broader trends in system and software engineering are impacting the world of digital screens and the commercial environments we inhabit. In the process these trends are making displays more compelling and interconnected than ever.
LED Diode Fundamentals
There are two fundamental types of LED diodes that are used in an LED screen. The first is the traditional lamp type or DIP diode. This diode is a PTH (plated through hole) component. The circuit board this component is assembled onto has holes with a copper plating covering the edges of the hole so that contact can be made between the component and the proper circuit. A technician inserts the diode into the holes and solders it together to complete the assembly. Each of the colors that make up a pixel (red, blue and green) are separate components, therefore each pixel is a cluster of the three. PTH technology was an amazing technological breakthrough at the time it came online. That was, of course, in the 1950s. Go into any modern electronics manufacturer today and ask if they have the equipment required to assemble PTH components and they will probably laugh at you, unless they happen to be an LED display manufacturer where these components are still commonly used.
SMD Diode Technology
The second type is the SMD (surface mount device) diode. This is newer to the LED display industry but the technology itself has become the standard of electronics assembly since the 1980s. Circuit boards have copper contacts on the surface that are covered with a solder paste. Machines automatically place components on top of those contacts. The boards are then fed through an oven that solders everything together. Assembly is quick and almost fully automated. The LEDs themselves come in a package that combines the red blue and green LEDs together to form a full pixel in just one component. SMD technology has improved in recent years to solve problems like UV degradation and contrast (old diodes used to be bright white in a powered-off state but now they are black as they should be for optimal visual effect).
SMD diodes are new; lamp type diodes are old. So why keep old lamp type diodes around? The problem is that no one has fundamentally come up with a better and more cost-effective way to assemble the thousands of diodes required to make an LED display. The oval lenses that compose the top of a lamp type component focuses the light coming off the diode inside, making them shine brighter with less power. SMD diodes don’t have that luxury and therefore require up to about three times as much power to deliver the same level of brightness. This causes them to burn hotter, and possibly burn out quicker. Lamp type diodes are inexpensive, reliable and power efficient. Viewed from a distance, there isn’t a compelling enough difference in how the end product looks in many outdoor applications. Consider that many large billboard operators don’t employ SMD displays simply because their customers don’t notice the difference in brightness, and the increased power consumption adds to their bills unnecessarily.
However, from a closer vantage point, SMD is the only option. We measure display resolution in terms of pixel pitch. That’s the physical distance between each pixel. The smaller the pitch, the more LEDs we can get on the same surface area. Lamp type diodes bottom out at around 10mm pitch. The three separate lamps that make up a single pixel takes up so much space on the surface of the screen that it’s impossible to squeeze them any closer together. There just isn’t enough room.
SMD diodes can be assembled onto high-resolution indoor display screens at extremely high resolutions down to 4mm pitch or less to achieve a spectacular effect.
Simple, Clean, Enclosed
Moving beyond the component level, to full displays, there is a clear trend toward simpler, cleaner, enclosed modules. An LED display module can mean a couple of things. The term is used to describe sections of the face of a screen that are manufactured separately and then tiled onto a structure of some kind to form a screen.
In the old days, this would mean a sealed module face with exposed electronics on the backside. The exposed electronics would be covered by the cabinet that they were bolted onto. Inside the cabinet, a series of fans would blow air sucked in from outside the cabinet onto the exposed electronics to keep them cool. In between each module and power supply was a network of wires that fed power and data to the modules themselves.
The issues that arose were clear. Outside air is filled with contaminants and moisture, which are particularly deleterious to electronics. Service is difficult unless someone were to study the complexities associated with the nest of wires in one of these systems and the overall product ended up being bulky and cumbersome.
While many screens are still made using the same antiquated design of decades past, more forward-thinking manufacturers have been implementing sealed units, which are completely self-contained. There are no visible wires and no blowing fans. Highly efficient systems produce less heat and therefore can be passively cooled via heat sinks rather than fans. Sealed components and higher efficiencies mean fewer failures or complications.
Think of the difference between an incandescent light bulb and a new LED bulb. Newer, more efficient LED bulbs are cool to the touch and use less energy. That’s not a coincidence. Inefficient light sources tend to heat up as energy is converted to produce that heat instead of being fully converted to light. In the case of displays, a more efficient screen means one with less of a cooling requirement because less heat is being generated in the first place.
Software and The Cloud
Display software opens up a world of possibilities. Much has been written about the “Internet of things.” The networking of displays in the real world enables a crossover potential between the digital and brick and mortar worlds unlike any other. Displays that are not connected through a cloud server of some kind have become critically limited. Already technology is allowing for faster and better servicing of displays.
As an example, at Cirrus, we can detect issues on our screen in real time and troubleshoot them. Even individual modules on our screens are monitoring themselves and reporting back to our servers with updates on a perpetual basis. This is just the beginning though. Imagine messages being tailored to precisely the individuals passing by a screen or customers being able to interact with that screen in real time. These things are happening today through networks operating between the smartphone in your pocket, cameras and cloud-connected displays. The integration of these technologies has the potential to change the essence of what a sign is, revolutionizing the sign industry.
From the most basic component that composes an LED display—the way those displays are designed and fabricated—to the software engines that drive them and engage the people who view them, displays are changing every day. Staying abreast of the latest developments and trends can mean opening up worlds of new business and opportunities for you and your organization.