Versatile, energy efficient, and attention grabbing, light-emitting diode (LED) displays are growing in popularity as an effective signage option in a wide variety of applications. An emerging technology, tens of thousands of LEDs combine to present a bright, beautiful, eye-catching display in pictures, videos, and other formats.

Photo courtesy of Draper Inc.

The versatility of LED means it can work in nearly any space—inside or out. Uses include wayfinding and advertising.

From advertising the latest sales to restaurant menus to corporate branding to public information messaging, LED displays are an effective way to communicate key information.

To optimally design, size, and mount these displays, an in-depth understanding of LED display technology, mounting systems, installation parameters, and project planning is essential. Further, the LED display will only show the highest visual quality if it is mounted with a high quality structure capable of offering very high level of precision while also providing micro adjustments for installation alignment.

Comparing LED to LCD and Projection

In analyzing LED, the technology offers a number of advantages in the realm of lifespan, brightness, power use, and configurability.

For starters, LED displays are capable of operating 80,000 to 100,000 hours before reaching their half-life. In comparison, the half-life of liquid crystal display (LCD) is 50,000 hours, and with laser projection, it is 20,000 hours.

Putting this into perspective, an LCD video wall lasts approximately five years and needs to be serviced annually to calibrate color and brightness, whereas an LED display can last for approximately 10 years and can be re-calibrated at the pixel level, helping the display to look like new its entire life. Consequently, when calculating the initial setup, lifespan, and maintenance, any LCD/LED cost gap quickly closes.

In addition to longevity, LED technology has the ability to be exceptionally bright, with levels ranging between 800 and 10,000 nits. Nits is the measured intensity of visual light emitted from the display, with one nit equaling one candela per square meter. In contrast, LCD video wall displays range from 350 nits to 700 nits, and projection offers a range from 1,000 to 40,000 lumens of projected light onto the screen.

These brighter outputs allow LED displays to compete with direct sunlight, which is a noted advantage for outdoor and window displays.

“The most obvious advantage with direct-view LED is the largest and brightest video images without the noticeable seams that you see with LCD video walls and with contrast ratios that you just cannot achieve with projectors,” states Scott Simpson, CTS-D, DMC-D-4K, audiovisual consultant, associate, PAE, Portland, Oregon.

Contrast ratio is key to LED performance. Contrast ratio is usually measured in a dark room. A projector and screen system can have a very high contrast ratio; however as ambient light is added to the environment, the contrast ratio goes down due to the reflection of the ambient light on the screen. Eventually, the contrast ratio winds up being so low that the image can no longer be seen. The ambient light on the screen is brighter than the light from the projector.

The design of most modern LED displays that utilize SMD LED solutions reduces the amount of reflective ambient light from the face of the display. The SMD which houses the RGB LED's typically has a dark gray face with a matte finish to reduce reflection and remain dark in color when the LED is in the off state. Additionally, the space between the LEDs is typically filled with a black sub-straight that also has a mat finish. The black color helps to improve contrast in bright ambient conditions and the matte finish helps to reduce reflections from the surface.

Additionally, LED displays specifically designed for outdoor usage in direct sunlight have a substrate surrounding the LEDs that incorporate small shading elements to prevent sunlight from shining on the LED and reflecting back to the viewer.

To better qualify a display’s brightness, it is important to understand emissive, transmissive, and reflective technologies. LED displays emit light directly from the display. This emitted light helps create sharp and high contrast visual appearance because the LED’s light can be easily calibrated to be brighter than surrounding ambient light and the light emitted is not diffused in any way.

LCD displays use a transmissive display technology, which means light is emitted from a backlight and transmitted through the LCD layer to create a visible image. The LCD layer diffuses the light which results in a much more subtle appearance and lower contrast.

Projection uses a reflective technology that does not perform well in bright ambient light conditions. This is due to the reflection of the surrounding ambient light on the surface of the screen, which washes out the image and results in very poor contrast.

As opposed to LED displays, which can selectively brighten or darken each pixel, , LCD and projection technologies historically use a light source projecting a constant brightness over the entire active image area, although some LCDs have a dynamic backlight that works similarly to an LED display which helps reduce power consumption. Because of this, the power consumption will be fairly constant regardless of the content being shown. Further, commercial applications are typically set at the brightest available setting, which also consumes the most power.

Because LED is an emissive technology where light is emitted directly from each LED or pixel, the power consumption is directly related to the brightness of the content shown on each pixel. So, with proper content creation, focusing on darker backgrounds with higher contrast, an LED display can yield lower power consumption.

In typical indoor applications, LEDs are generally set to a level that is below 50 percent of the display’s capable brightness. If content is created with power saving in mind, and an ambient light sensor is employed to manage the brightness throughout the day and night, the overall power consumption will be even lower, as the black areas will remain unpowered, and the overall display will dim and brighten as ambient conditions allow.

Regarding configurability, LED offers a high level of flexibility since the video walls do not need to fit within a certain standard aspect ratio, such as 4:3 or 16:9. The LED display uses LED panels which are often a quarter of the size or smaller of a traditional 55-inch LCD video wall and allow for a modular display configuration, so arrays can be 2x2, 2x4, 2x8, or any number of configurations. The LED video wall can also be quite large and still deliver a high-quality image.

Another advantage is the way in which the LED cabinet are designed to fit together seamlessly. This allows for content to be displayed without any visual interruptions of seams between displays, as is seen in LCD walls. While both LED and LCD can display the same content from multiple sources, the seams in an LCD video wall can interrupt or cover over text in the content.

Whereas LED has traditionally been a costly technology, this has been changing. In recent years, a narrow pixel pitch (NPP) LED display would have cost the end user roughly five times or more than LCD or projection for the same size video wall display. But today, the price gap is getting closer to equal.

In making a cost comparison, this depends on the pixel pitch of the LED display, which is the spacing of the pixels. LCDs and projectors typically have a fixed pixel quantity of roughly 2 million or 8 million depending on full high-definition or 4K, which is a horizontal display resolution of about 4,000 pixels, so the cost per pixel is not directly related to the number of pixels. An LED display has a varying quantity of LEDs (pixels) based on the total size of the display and the pixel pitch, which is defined as the space between pixels. If a display has a pixel pitch of 1.9 millimeters as opposed to another display of the same size using a 2.5-millimeter pixel pitch, the 2.5-millimeter display will have roughly 24 percent fewer LEDs and cost roughly 24 percent less even though the display size is the same.

Overall, the total cost of LED ownership is typically lower because LEDs last much longer.

Photo courtesy of Courtesy of Planar

The Plaza Coral Gables - Coral Gables, FL., DirectLight X LED - 26 x 26 Video Wall with custom Draper support structure, Developer: Agave Ponce, LLC, Integrator & Installer: Pro Sound & Video