What is a Head Up Display? HUDs Explained

For most car manufacturers, dashboard dials are so passé. Many of them have replaced physical readouts with touchscreens, which appears not to be very beneficial for safety, as our accompanying blog reveals.

While the cynic may argue that marketing is responsible, it is fair to reason that drivers have to absorb far more information now than they did fifty years ago. Greater traffic density, additional road furniture and increased signage have seen to that. To help drivers, engineers took Head-up Display (HUD) technology, which originated from 1940s fighter aircraft, and transplanted it into passenger cars.

What is a Heads Up Display (HUD)?

A head-up display is a projection of vital information onto a flat surface near to, or on the windscreen.

The idea is to improve safety, by reducing distraction. HUDs help the driver to avoid looking downwards at the fascia, or centre console, when their primary focus should be on the road.

What can a HUD Display show you?

Much depends on the vehicle and its specifications. Vehicle speed, speed sign recognition reminders, satellite navigation instructions, distance countdowns and sudden warning messages tend to be the most common displays.

Types of Head-Up Displays: Windscreen vs. Pop-up

HUDs require a projection surface, which, in HUD technology-speak, is called the 'Combiner.' A combiner is a surface that transmits light from outside the vehicle but reflects light from the HUD. This BMW has a Windscreen HUD, where the windscreen fulfils the combiner role

When a separate pop-up plastic panel is fitted between the driver and the HUD's projector, the system is defined as a Combiner HUD, such as fitted to this MINI.

How do Head-Up Displays work?

As is the case with modern cars, the HUD is networked with other components, meaning that the technology does not work in isolation. Even so, the system comprises a trio of main parts - the combiner (as discussed earlier), the optics module and the imaging unit.

The optics module is a precision device that directs the LED light it receives. As the unit must be very compact, so it can be positioned beneath the fascia, it employs multiple lenses and mirrors. These have to be manufactured precisely, otherwise, the projected information would be unclear.

The imaging unit contains a processor that receives the required information and interprets it into simple graphics. It also includes the Light Emitting Diode light source, the beams from which travel into the optics unit.

Benefits of using HUDs whilst driving

Many car manufacturers offer HUDs as standard equipment. The safety benefits of HUDs cannot be ignored, especially when they are integrated with other systems, such as satellite navigation and road sign recognition technology.

These include:

• Fast access to information

• The ability to prioritise information

• Allows certain systems to be more effective, such as satellite navigation in complex road designs.

How HUDs improve road safety

The main advantage is reduced distraction. HUDs help the driver absorb and prioritise information quickly, without removing their focus from the road.

Disadvantages and limitations of HUDs

Despite being intriguing devices, HUDs add both cost and complexity. Poorly designed graphics can make head-up displays more distracting. Very bright sunlight can also make readings almost impossible to decipher. A further issue can be the need to keep the windscreen and pop-up combiners clean, otherwise message clarity can be compromised.

How can you look after your HUD?

As the Heads-up Display components are solid-state, they require virtually no maintenance.

The main task is to keep the exposed parts clean. Consult your vehicle's handbook for more information on this. Should you not have one, or the literature provides no information, wipe the display and combiner carefully with a microfibre cloth. While some installations can tolerate a water-moistened cloth, never use cleaning chemicals, or glass cleaner.

Generally, HUDs are very reliable. Most damage is caused by physical interference. The most common problems stem from careless cleaning, or impact damage, due to property being placed on the dashboard top.

What is the future of Head-Up Displays?

HUD technology is here to stay. Today, 10% of cars possess HUDs. By 2030, this figure is predicted to approach 40%, with windscreen HUDs being the dominant type. Augmented Reality HUDs are expected to become more popular and will incorporate more information, as both driver assistance and autonomous technologies develop.

Keep up to date with GEM Motoring Assist at:

X: @motoringassist

Facebook: @gemmotoringassist

Instagram: @gem_motoringassist

LinkedIn: @gem-motoring-assist

Share this on socials below: