What Are LED Signs?

LED signs, made up of thousands of LED bulbs, are an extremely effective advertising method. In this guide, we will focus on how LEDs are used in outdoor digital signage.

But what are LEDs?

LED is an acronym that stands for light-emitting diode. An LED is a semi-conductor of electricity that emits a bright light. LEDs contain three colors within it – red, green, and blue. These three colors make up every LED. These primary colors can be combined to create any number of other color variations, including white light.


Outdoor LED Displays

Outdoor LED displays use a large collection of bulbs to emit light in the form of an image and are used in outdoor advertising, especially on freeways, roads, and buildings. Advances in LED technology means that nearly anything can be displayed on an LED screen, including pictures, videos, and custom slides. 


Although the usage of LEDs has become more prevalent in recent years, LED technology has been around for more than 50 years.

The history of LED signs begins with the invention of the LED bulb.

Nick Holonyak, Jr., first invented a red LED while working for General Electric in 1962. After red, the next bulbs to develop were yellow and green. LED bulbs were bright and more efficient than their incandescent counterparts, and thus the technology continued to be developed further. 

The first LED display was made by Hewlett-Packard in 1968. Because the blue bulb was not invented until 1980, the first displays were monochromatic. 

The LED bulb has come a long way since 1962. Now LED bulbs are used in digital displays to make stunning, high-resolution images. From the creation of one red LED bulb, to using red, green, and blue bulbs, to including three colors in one bulb, technology continues to rapidly advance and become even more efficient. 



An LED display is made up of a number of different components. All of these components function together to make up an LED display. Each of these components can differ in quality and standard according to the LED manufacturer. 

LED Bulb Types

LED displays today use two different types of bulbs to create their images: the DIP and SMD.


DIP stands for “Dual Inline Package”. DIP LEDs are made up of three distinct bulbs – one red, one green, and one blue. These three bulbs together make up one pixel

Every DIP bulb is attached to the circuit board of the LED sign in a manufacturing method called “through the hole”.


SMD stands for “Surface Mount Diode”. SMD bulbs contain all three colors within a single bulb – so, every bulb is one pixel or LED. SMD bulbs are soldered directly onto the circuit board of an LED sign. They take up less space than DIP bulbs and release much less heat. Because of these factors, SMD bulbs are used in high resolution LED displays where the pixel pitch is much smaller.




The brightness of an LED sign is measured in nits.

Signs using DIP bulbs typically have a higher brightness than those using SMD. However, DIP bulbs use more energy and generate more heat than their SMD counterparts.

The standard brightness for DIP LED is 18,000 nits, while the standard for SMD is 5,500 nits.


Pixel Pitch

What is pixel pitch?

Pixel pitch refers to the distance between pixels on an LED display, measured in millimeters. Pixel pitch is measured from the center of one pixel to the center of the next.

Why does pixel pitch matter? Pixel pitch directly affects the resolution of an LED sign.



The smaller the pixel pitch, or the closer together the bulbs on an LED display are, the higher the resolution of the sign will be. Resolution is important to LED signage because it affects how visible the image displayed on the sign will be to those viewing it. A sign with a higher resolution picture will be more clear than a sign with a low resolution. 



A PCB, or printed circuit board, connects electronic components. For an SMD LED sign, the bulbs are mounted on the PCB. 

The typical PCB is 2 to 3 layers thick. The more layers a PCB has, the more sturdy and stable it is.



Modules are the building blocks of an LED sign. Each display is made up of a number of modules, containing the PCB fitted with the LED bulbs. These modules can vary in size depending on the manufacturer. Modules are fitted together and connected in order to form the display in a specific size.

LED modules can be made from many different materials, from plastic and silicone to high quality aluminum.



A cabinet is a metal frame that houses the modules in an LED sign. LED cabinets are typically made from some sort of sheet metal and, like modules, can also be fabricated in a variety of sizes.

High-quality cabinets are made from durable metals, such as aluminum. 



LED bulbs generate heat as a natural result of operating. Industry standard LED signs will have a system of fans that cool the inside components of the sign. Without this cooling, the display could overheat and lead to burnt out bulbs and even complete failure.

More advanced LED signs use a heat sink to cool the components. But what is a heat sink?

A heat sink is a device that absorbs the heat radiating from the LED display through conduction and effectively dissipates the heat from the sign. Heat sinks are generally made with high-quality aluminum, since aluminum is a conductive and durable metal.



Outdoor LED signage should have some sort of waterproofing rating that will ensure they are protected from the elements. LED signs are rated on the IP scale for waterproofing and dust resistance. The highest ranking that an LED sign has achieved is IP68 waterproofing — this means that the sign can still function while it is submerged in water, and that it is resistant to dust. 


Refresh Rate

Refresh rate refers to how frequently the image on a digital display is cycled through, referred to in terms of hertz. The higher the refresh rate, the better the image on the screen screen will appear. Hertz refers to one cycle per second; for example, 3950 Hz would be 3950 refreshes every second. The refresh rate of an LED sign can usually be adjusted, but it ranges between manufacturers. 


LED Lifetime

LED lifetime is how long you can expect the bulbs in a display to last. No bulb can be illuminated indefinitely, but with LED displays, the lifetime of a bulb can be quite long (as long as they are cooled effectively). Many high-resolution LED manufacturers aim for a lifetime of 100,000 hours.


Energy Usage

Energy usage refers to how much energy is needed to power the LED sign. Energy usage varies based on what type of bulb is used, the pixel pitch, and the dimensions of the sign. However, since LED bulbs are naturally more energy efficient than incandescent bulbs, many LED signs are energy efficient. 

Companies that have especially energy efficient signage typically have an energy rating or certification from their state or from another outside organization.



The size of an LED sign depends on the needs of the business and the capabilities of the modules. Some businesses decide on the size of a sign based on pricing or on the city or county code restrictions in their location. 

Some questions to consider with size are:

  • What is the budget available?
  • What size are the modules? What can the dimension of the sign be? 
  • How far away is traffic? How fast are the cars driving? 
  • An LED expert can help with deciding what size sign is right for your business. 


Viewing Distance

In the early days of LED, manufacturers would provide an ideal viewing distance for each sign based on their pixel pitch. LED sign companies would argue that signs located farther away from traffic, such as a sign on the side of a freeway or on a large building, could be a larger pixel pitch and still be visible.

However, now that LED technology has advanced to the point where high resolution is a reality, suggesting higher pixel pitch signs for further viewing distances is becoming a thing of the past. In the age of decreasing pixel pitch, we argue that LED viewing distance will soon become a metric of the past and that the focus will turn to the quality of the display.



LED sign placement is extremely important to efficiently advertising with LED. Sign placement will determine who will be able to see your sign. Whether your sign is on your building or on the street, make sure it is in a place that is visible to traffic and not blocked by any power lines, trees, or other structures. 

The best placement is on a busy road with a lot of traffic, in a location that can be easily seen from many angles and distances. 


Cloud Software

Using cloud software means that you can upload and change the content of your LED sign from any location. This can be done through a remote or through a personal computer. Many companies even have mobile apps that allow you to control and upload content to your sign. 



LED is a powerful tool with the capability for displaying dynamic messages.

What is the best way to create impactful content for LED signs?

The best display messages are clear — this means that the messaging is not too wordy or confusing, that the colors are not clashing, and the image is not too fuzzy.

LED signs can be used to increase brand awareness and tell the story of your business. Include content on your display that represents who your business is and what is important to you. Don’t be afraid to use images of your employees, customers, or your products. Make it personal and specific to you.  




According to the Small Business Administration, businesses using LED technology can expect to see their revenue increase by a minimum of 15% and up to as much as 150%. Some businesses see an even greater revenue increase by purchasing a high resolution LED sign. This means that although LED displays have high up-front costs, they offer businesses a high return on their investment. 


Cost Per Impression

Advertising methods are often evaluated through their cost per thousand impressions. This means that marketers evaluate how much it will cost to get one thousand people to view the advertising method. 

For LED, the cost per thousand impressions is only $0.74. LED signs can communicate with people driving by while keeping operating costs low. Compared to other advertising methods such as television, radio, or newspaper, LED is much more cost-effective, according to the Small Business Administration. 


Testing and Listening

Once you have bought and installed an LED sign, the work doesn’t stop there. Just as with any other marketing method, LED signs need to be tested and optimized. Try out different images and messages to see what works best for drawing in new customers. Ask your customers how they found out about you and if your sign played a role in their discovery. 


GDTech – Your Guide to High Resolution LED Signs

Global Dynamic Technology, or GDTech, specializes in high resolution LED signage for business. Our LED displays feature a small pixel pitch, advanced aluminum heat sink technology, and world-class support

We are passionate about seeing our customers succeed and grow with LED. Feel free to send us your questions and concerns about outdoor LED signage.

For more information about our technology or the buying process for an LED sign, contact us today!


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