Lighting: Safety lights

Osram laser modules are incorporated in the BMW i8 series

Mark Patrick, technical marketing manager for Mouser Electronics. explains how to make roads safer by implementing the latest automotive lighting technology

Studies have shown that light conditions can have a profound effect on the likelihood of road accidents occurring. In EU member states, an average of over 10,000 such accidents each year take place during the night. This is effectively double the figure in the day, relative to the number of road users at that time.

Driving in darkness or low light conditions can mean there is less time to identify and subsequently react to a situation on the road ahead. It also has a detrimental effect on the ability of vehicle drivers to estimate distances accurately, thus making it more challenging to judge what the best course of action will be or to execute difficult manoeuvres correctly.

The automotive industry is consequently keen to upgrade the lighting capabilities of car models, so that visibility levels can be improved and road users can be subject to a higher degree of protection. Pivotal to this will be replacing the halogen and high-intensity discharge (HID) lamps that have traditionally been the source of illumination in vehicle designs with modern solid-state alternatives.

Over the course of the last decade, there have been significant advances in LED technology with improvements in performance and reductions in the associated unit price both being witnessed. As a result, car manufacturers are now looking to use it throughout vehicle designs. No longer just restricting it to interior lighting, side lights and such like, but going for wholesale implementation, including front lights, brake lights and so on.

Analyst firm TrendForce expects that, based on this, there will be a significant ramp in LED demand within the automotive sector. Its research suggests that the automotive LED market will grow by almost 12.5 per cent between the end of 2017 and the end of 2018.

It is widely recognised that LED-based illumination has numerous benefits within an automotive context. As well as being extremely reliable and supporting extensive operational lifespans with minimal change in their output characteristics over time, such devices are able to exhibit high energy efficiency levels, which means they have less impact on vehicle fuel consumption and help support greater fuel economy.

Since more energy is converted into light and less into heat, they require less thermal management, with cost and space saving benefits therefore being derived. In addition, they can deal with extreme temperatures and switch on and off at high speeds.

Crucially, they can also support a much more expansive array of functionality than conventional automotive lighting components. One of the key ways in which this is being realised is through pixel-light technology, where areas of the front light can be blocked out to prevent the drivers of vehicles travelling in the opposite direction, pedestrians and even wildlife from being dazzled by front light beams, thereby lowering the chance of an accident occurring.

LEDs also offer the possibility to change the shape of the beam produced, so as to respond to the environment that the car is travelling through, but without the need for motors, actuators or other electromechanical elements to be incorporated.

The method used for making such changes to the beam shape is referred to as adaptive front lighting technology. This enables the beam to be adjusted in accordance with the contours of the road, changing the angle of the beam vertically when the vehicle is either going uphill or downhill, or if it is negotiating its way over bumps. Likewise, the direction of the beam can be changed in relation to the horizontal axis in response to bends in the road, to ensure that light is always directed to where it is most needed. Furthermore, the range of the beam can be extended as the vehicle’s speed increases, so as to give the driver more time to identify any obstacle that may require an evasive manoeuvre, for example.

To do all this, data concerning the vehicle’s speed, its pitch relative to the road and its turning rate must be acquired. This is done using a multitude of sensors that are positioned all over its chassis and fed back via Can or Ethernet network infrastructure.

The latest Mercedes-Benz E Class models feature adaptive front lighting capabilities. Each of their headlamps comprises 84 individually activated high performance LEDs arranged into a matrix that delivers precision-controlled, high brightness illumination. Through four ECUs, the vehicle can calculate the most appropriate light pattern at any given time. This pattern can be updated at a rate of 100 times per second.

 

Opportunities

Opportunities for optoelectronics in automotive are continuing to open up. Osram, for example, has been heavily involved in laser-based front lighting. Its laser modules are already incorporated into the BMW i8 series allowing a 600m illumination range to be realised and are now starting to be designed into other luxury car models.

There are still engineering challenges to face though. Solid-state lighting needs to become more cost effective if it is to witness further proliferation. Despite the fact that LEDs are cheap to produce, the surrounding electronics assembly can still demand a relatively high price tag.

Things are going in the right direction, however, and bill of material costs are steadily falling. So it is no longer a question of whether LED front lighting will make it into mid-range and economy vehicles, it is just how quickly it will happen. 

Mark Patrick is technical marketing manager for Mouser Electronics

www.mouser.com

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