Security has always been closely associated with light – in our everyday life, as well as in driving safety. Today, increasingly more intelligent and autonomously operating applications with visible and invisible light are providing more comfort and driving safety. LEDs and optoelectronics are taking on crucial importance in this respect, says Osram Opto Semiconductors.
Light contributes to driving safety
Today, we can find a wide range of solutions based on visible light in automotives: from intelligent headlights, where new multi-pixel LED technology is shaking up the industry, to efficient interior lighting or head-up displays.
In addition to much discussed topics such as adaptive driving beam (ADB) or adaptive front lighting systems (AFS), there are numerous applications that contribute to improving automotive safety – these include solutions such as adaptive cruise control, pre-crash sensing, automatic emergency braking, pedestrian protection, active NIR night vision, driver monitoring, occupancy detection and many more.
Many safety-related automotive systems are based on invisible light from infrared LEDs (IREDs). Depending on the wavelength, these light sources are used in different applications. A main application field for IREDs with a wavelength of 850 nanometres (nm) are, for example, infrared lighting units for camera systems that monitor the outside environment of a car. These systems include night vision systems and forward collision detection systems such as pre-crash sensing and pedestrian protection solutions that work with camera images. Flooding the scene in front of the vehicle with infrared light enables the vehicle environment to be reliably detected even in the dark. Unlike laser-based assistance systems which work with pulsed light, the above-mentioned systems tend to use permanent light sources. In the last years, there have been major improvements in the efficiency, brightness, a decreased size and lower system costs for such IRED solutions, helping to accelerate the implementation of these safety systems into the automotive market.
IREDs with a wavelength of 850 nm are predominantly used for exterior applications. The reason lies in human perception of infrared light at a wavelength range lower than 900 nm: It appears as red glow to the human eye. While this is not problematic in exterior systems, it would be disturbing for interior applications. In these areas of applications infrared light with 940 nm is used, as this spectral range is no longer perceived as red glow. A typical application for IREDs with 940 nm is driver monitoring: a camera system with infrared lighting monitors the driver’s face and line of vision. The system can direct drivers’ attention back to the traffic when they are not looking directly at the road. It can also detect when drivers are tired and alert them – a well-recognised improvement for road safety. Passenger occupation detection systems can also improve safety by adjusting the deployment of the airbag according to the passengers’ position, while gesture recognition improves the easy of operating car systems, hence reducing the time the driver takes his eyes off the street.
In addition to efficiency and performance, the development progress for the latest generation of 940 nm IRED components, such as the Oslon Black family, includes advancements in high optical pulse outputs and a wide range of integrated lens options. These allow system designers to select the right IRED for virtually any application without having to install secondary optics.
Paving the way to (semi-)autonomous driving
Another automotive technology using invisible light is called LiDAR (Light Detection And Ranging). LiDAR works on the principle of radar but uses light pulses emitted by an infrared laser diode. The latest developments have seen various multi-beam LiDAR systems, which generate an accurate, three-dimensional image of the vehicles’ surroundings. This information is used to initiate the appropriate driving manoeuvres.
Biometrics enter the automotive industry
Applications in mobile and consumer technology have triggered a spurt in the development progress for biometrics technology. The automotive industry could be the next to see a surge in uptake as the latest concept car “Snap” by Rinspeed has demonstrated at CES and the Geneva Motor Show 2018. Biometrics technology – from fingerprint scanning to facial recognition or iris-scan – is largely considered to offer a high degree of security and is extremely user-friendly. Automotive manufacturers are considering the use of these systems for car access, driver recognition or access to in-car data systems.
Bright and complete illumination of the user’s face or eyes is particularly important for facial recognition and also for eye-tracking systems in vehicles. The latest IRED solutions with typical wavelengths of 810 nm to 940 nm are key in achieving the high level of quality and contrast needed for biometrical systems. The progress in miniaturisation as well as reduced power consumption and lower costs accelerate the uptake.