HUD and Polarized Sunglasses — No Longer an Issue
Safety vs style. Usability vs design. Compromise vs steadfast. These are decisions that need to be made with the direction we want to take with our solutions. Luckily, we at Faraday Future (FF) want to have a ‘user-first’ mentality where we take the experience and break the established automotive mold to deliver a truly remarkable and innovative automotive experience.
The infotainment industry takes to heart to deliver their solutions for all users at all occasions, not compromising due to difficulty or effort in design. From the beginning, we make the driver’s experience our priority and leave no holes to be filled. Everything about our cutting-edge vehicle and technology was created to make the lives of our users more connected, more engaging, and more effortless.
That’s why we took a simple high-end feature that we felt affected safety, experience, and performance and made it work even better. The HUD (‘heads up display’) has been around for quite some time now, it was first used in high-end cars as an option to make sure the driver kept their eyes on the road. It should be noted that a glance off the road averages around .6 seconds. That means at 70 miles per hour, the automobile will go about 100 feet while your eyes are off the road. At Faraday Future, that 100 feet of distracted time is 100 feet too many. That’s why we made the HUD a standard feature in our vehicle.
The most basic form of a HUD has a PGU (‘picture generator unit’), a series of curved mirrors, and optical filters on its pathway to the windshield. This reflected image off the windshield is what the driver sees. Almost all HUDs available in the market today use an LCD as a PGU. It is cheaper to manufacture and the availability of the components are easily available.
Unfortunately, the light path of LCDs must have a polarizer as it’s last step in order to function. As this polarized light is being reflected off the mirrors to the windshield, the driver can easily see the image. The problem is that the light that is seen is polarized at the same angle as the common polarized sunglasses thus making the HUD difficult, if not impossible to see in some situations.
Polarized sunglasses are designed to reduce glare from surfaces (water, roads, and so forth). When unpolarized light from the sun reflects off a surface, it reflects mostly the horizontal component of the light. If sunglass manufactures can filter out that horizontal component, then they can reduce the glare coming from the surface. They used polarized lenses to increase the visibility outdoors. This is the same reason photographers use a polarizer in camera lenses.
Due to the conventional HUD’s reflection angle off the windshield, the virtual image is polarized at the same angle as the glare coming off the road. This then causes the sunglasses to filter out the HUD image as you can see below. If you place those glasses at a 90-degree angle, you can now see the HUD image.
We saw this as an issue and tried to address it by working with a whole new PGU. One that is not an LCD based, but instead DLP based technology. Instead of using a polarizer structure to act as a shutter for light to pass through, DLP uses very tiny mirrors do direct light in the PGU. Each mirror acts as a pixel while red, green, and blue LEDs are used as a light source. These millions of tiny mirrors in the microarray are switched very slightly to produce the image that is needed.
At Faraday Future, we don’t let convention get in the way of progress. Holding to a higher standard of safety, we were able to provide a HUD that works with and without polarized glasses. Optimum driving experience should not depend on what you wear.
