LED is by far one of the hottest technologies to hit the market in years. The concept of using LEDs in lieu of conventional filament bulbs basically impacts every electronic device that features any form of visual indicator – from simple power indicators to the fog lamps on most new cars. As a result, the demand for LED has skyrocketed in recent years, drawing a host of companies into the market. The problem is that some of these LED suppliers are pushing inferior goods, mainly in an attempt to keep costs down.
As a result, some low-grade LEDs are finding their way into what some display companies are promoting as high quality LED displays. Overall, the professional display industry recognizes that Nichia and Cree lamps deliver high quality LED products. Moreover, there are new LED lamp suppliers entering the market with excellent products that now provide a viable alternative for manufacturing premier performance LED display systems.
Just stroll down Las Vegas Boulevard on any given night and compare the quality of the LED displays from one venue to the next. Given our growing exposure to HDTV and higher technologies, it’s quite easy to spot tired, substandard LED displays. The eye simply doesn’t lie. Although overall image quality is determined by a number of factors that include content, processing, fill factor, resolution and pitch among other aspects, which I’ve covered in earlier articles, your LED lamp quality is truly what determines how long your display is going to look good.
Take a Close Look under the Hood!
To really get a good feel for the quality and performance of an LED display system, you need to see what is driving the system. The LED lamps at the heart of any LED display basically consist of just two elements: the die, which is the LED chip that actually produces light output and color, and the packaging, which includes the cathode leads, reflective lens and encapsulate. There are a large number of off-shore companies that manufacturer just LED chips in their simplest form and sell them to various companies that then engineer them into various products. Although the die itself may be of top quality, the quality of its output and color rendition can be compromised when packaged. When used for display systems, this can result in irreparable performance issues as there is simply no way to make these systems look good regardless of the software and content driving them.
The problem users face is that it is difficult to determine the quality of the LED packaging. LED chips are cut from a wafer that is initially cored from an immense slag of material. It is then processed into layers to create the final wafer from which LED chips are cut. A single full-cut 2-inch wafer can produce up to 6000 LED chips, which, when integrated into the lamp package, are then sorted into as many as 79 quality-inspected bin sorts. These lamps are measured in terms of color intensity, brightness and voltage handling. The best dies will only come from the 2” center-cut, which are the best of the lot – and in most demand from best-in-breed LED display manufacturers. These are obviously also the most expensive LED chips – and the ones you want in your display for the best quality imaging.
When salespeople tell you that their company “only uses the best bin sorts” from one brand or another; they really mean they are hopefully buying LED chips that are as close to the center as possible. Do the math: 2,000 dies divided into 79 bin sorts produce an average of 25 LED chips per bin, and this will vary from wafer to wafer. Obviously, only the best LED display manufacturers with the strongest purchasing power are getting LED chips from the higher end bin sorts.
So it’s easy to understand why there are great, good and mediocre LED lamps out there. Some business practices can be pretty shocking; one of the premier LED die makers only cuts LED chips from the 2” center and trashes the rest of the lot, and unscrupulous LED chip suppliers have been caught dumpster-diving and cutting the remainder of the discarded wafers into LED chips. It’s one thing to use the lowest quality LED lamps in toys – but it’s a real problem if these inferior chips find their way into your LED display systems.
Be wary and ask tons of questions when evaluating LED display systems! Potential buyers need to rely on references, preferably from those 24/7/365 users who see the lamp degradation faster than anyone else, and have trust in the company they are dealing with. Don’t take an aggressive salesperson’s statements at face value. Ask for the color intensity/wavelength of the LED lamps they are using; voltage capacity; the amount of voltage pushing their lamps; who made the LED chips and who manufactures the packaging. LED displays are not cheap and if you are shelling out big bucks for an LED display system, kick the tires and look under the hood.
Recently, a facility purchased an LED display system from another company that used a poorly packaged LED lamp. Unfortunately, the LED diodes were coming loose and falling apart inside the encapsulate. Obviously this was due to bad packaging. The customer had no idea. There simply wasn’t any viable cost-efficient means of repairing this problem, and the customer wound up replacing the entire display system after a relatively short time following the initial installation.
When evaluating LED display systems, it is imperative that buyers specifically inquire as to the source of the LED chips, as well as the technique with which they are being packaged. Just because the LED display supplier claims to be using a recognized brand of LED chips, that doesn’t mean you are getting the same quality packaging you expect. And that will make all the difference in the performance and quality of your new LED display system.