How Head-up Displays Work

The 2012 GMC Acadia's heads-up display allows drivers to safety merge onto the highway using technology similar to what fighter pilots use to guide precise movements at supersonic speeds.
The 2012 GMC Acadia's heads-up display allows drivers to safety merge onto the highway using technology similar to what fighter pilots use to guide precise movements at supersonic speeds. See more car safety pictures.
© General Motors

Two of the most important parts of driving are being able to see well and knowing where you're going. Head-up display technology works with both of those ideas in mind -- and it's going to change the way we see the road forever.

The days of looking away from the road, missing a turn because you didn't understand the GPS or driving blind in the fog may soon be a thing of the past.


Heads-up display (HUD) systems can project information on the windshield, tell you where to turn, notify you of lane markings, identify how close the car in front of you is and even give you restaurant information all right in front of your eyes -- and while you're actually able to see those objects or places.

Believe it or not -- and yes, you should believe it -- head-up displays are not a new technology.


Head-up Display Technology

Fighter jets have used a rudimentary HUD system since the 1950s to display altitude, speed and even targeting systems on the front of the cockpit canopy. So if you grew up playing fighter jet video games, you know what we're talking about. Driving is about to get a lot more fun.

So what exactly is a heads-up display? It's best to think of your windshield as a transparent screen for information. Instead of taking your eyes off the road to see your speed, navigation directions or other info, the HUD system projects the information at eye level onto the windshield. No more glancing down and away at a small GPS screen. It's all right in front of you.


The tech for HUD varies on the system. Some cars use transparent phosphors on the windshield that reacts when a laser shines on it. When the laser is off, you don't see anything, but when the light is on the information is projected on the glass. Others use a similar system but incorporate mirrors to project the images on the windshield.

If you think heads-up displays are only available for high-end vehicles, you're going to be pleasantly surprised. In 2012 Pioneer released an aftermarket head-up display unit that mounts to the top of a car's cabin and can project information on the windshield. The system connects to a smartphone app through Bluetooth wireless technology and displays navigation instructions, points of interest and even road hazards.

So why do we need this, anyway? Well, not only because it's a cool technology to have and use, but also because the information, pictures, symbols and other gadgets we're adding to our vehicles are distracting us from the road. We need a new way to display this information that keeps our eyes up and on the road -- hence, the heads-up display.


The Evolution of Head-Up Displays

GM's full windshield head-up display technology, combined with night vision technology, allows for objects, such as deer, to be highlighted for the driver, preventing potential accidents.
GM's full windshield head-up display technology, combined with night vision technology, allows for objects, such as deer, to be highlighted for the driver, preventing potential accidents.
© General Motors

General Motors introduced the first heads-up display in a car in 1988 and the systems were originally used for showing speed, tachometer and other basic readings from the dashboard. But as the technology advanced, much more sophisticated and critical information is being displayed.

The original head-up displays are being replaced with newer technology called augmented reality (AR). These AR systems are the new version of head-up displays, but are far more advanced. ARs can integrate with GPS systems, infrared cameras, the Internet and mobile apps to turn your car's windshield into an on-board information screen. Think of the movie "Minority Report" without all the swiping hand gestures.


So what does this mean? Well, imagine you're taking a long road trip and you have no idea where you're going. There's going to be lots of turns in an unfamiliar city. If your car is equipped with a heads-up display, your car's windshield will highlight the lane you need to be in and when you need to turn.

The directions won't be on a small screen you'll have to glance down at. Instead, they'll be overlaid on top of what you're actually seeing in the real world. Your mobile app will be able to send information about gas prices and restaurant ratings and display that information on the windshield as you drive past the businesses. Imagine seeing customer ratings hovering over a restaurant as you drive past it, or seeing the store's business hours without having to drive up to the front door to take a look.


Safety Benefits of Head-Up Displays

Head-up displays are much more than just a novelty or a new way of viewing navigation directions. If the HUD system is paired with on-board cameras and adaptive cruise control it could very well be one of the best safety systems your car has ever seen. You know, aside from your seat belts, brakes, airbags, ABS and so on.

Why is an HUD system in the same category as these? Well, let's take a common weather problem that causes major safety hazards for drivers as an example -- fog. Newer HUD systems can use infrared cameras to detect where the lines on the road are and project them on the windshield exactly where they appear in real life. Take a minute to process that. Heads-up displays can project objects that are there, but that you can't see!


The same can be done to display a car ahead of you that you can't see. The HUD system will use cameras and GPS to locate the car and then display an image of it on your windshield, complete with information about its distance from your vehicle.

Now let's take it one step further. Not only can head-up displays tell you how far ahead the car in front of you is, it'll also be able to show you how to maneuver around another car to avoid an accident or other road hazards. Some adaptive cruise control systems already make safety calculations to determine the best route for a car around a certain situation, but the next step is to actually project that information, in real-time, on the car's windshield.

We won't be driving blind in the fog, rain or snowstorms anymore. Our cars will see what we simply can't, and then show us as if we're seeing it ourselves. HUD is here, and we may never see driving the same way again.


Author's Note

As I researched head-up displays I wondered if having all this information on our windshields is too much for us to handle. But as I saw the systems that are in development, I began to understand how HUDs will someday allow all of us to become better drivers. It can be available when we need it and we can turn it off when we don't want it.

Most of us are accustomed to having information at our fingertips all day long, so it makes sense to bring that same idea into our cars in more ways than just for music or entertainment. If HUD systems continue to develop at the rate they are right now, it won't be long before we're able to reduce accidents, assist drivers with vision impairments and see our surroundings a little clearer.


Related Articles


  • Borroz, Tony. "GM Makes Your Entire Windshield a Head-Up Display." Mar. 17, 2010. (April 2, 2012)
  • "BMW Group Developing Augmented Reality Window Displays." Oct. 12, 2011. (April 2, 2012)
  • Spinelli, Mike. "How fighter jet technology makes its way into cars." Oct. 28, 2011. (April 6, 2012)
  • Ulanoff, Lance. "Pioneer AR Heads Up Display Augments Your Driving Reality." Jan. 11, 2012. (April 3, 2012)