Low-light image quality, power consumption and high operating temperatures remain key challenges facing automotive OEMs today. These will be some of the major discussion topics at AutoSens Europe 2024, taking place this week in Barcelona, Spain.
For low-light image quality, the key challenge is the tradeoff between pixel array resolution and pixel size. The first image sensors developed and offered into the automotive industry about 20 years ago had a 6-µm pixel size and VGA (640 × 480) resolution. Today, 8-MP resolution is the sweet spot for high-end automotive camera systems. To make this boost in resolution possible, the pixel size had to shrink to 2.1 µm. The result is about 8× less light-sensitive area within a pixel to collect photons. Of course, some of this shrink in pixel size has been compensated by better pixel performance, especially by improving the relevant noise figures. But it remains a challenge to resolve some scene-perception corner cases—for example, detecting lost cargo at longer distances in low-light automated-driving (AD) scenarios on highways at night.
Additionally, we understand that power consumption and high-temperature image quality are real pain points for customers today. With the transition to electric mobility, the power consumption of its electronics has an impact on a vehicle’s driving range. However, for image sensors, there are other complications. For one, higher power consumption leads to higher junction temperature of the device, which directly and substantially impacts the image quality because various critical noise sources scale exponentially with temperature. This problem becomes more significant with the trend toward smaller and smaller camera modules, which impairs the heat dissipation behavior. Hence, the mission profile of automotive cameras has shifted to higher temperatures. But the problem is that most image sensors today have not been designed and developed to work well at these higher temperatures, so their overall performance and image quality are severely impacted. This can result in less-than-suitable image quality for advanced driver-assistance systems (ADAS) and AD perception algorithms.
To address these challenges of the automotive camera industry, a new approach to high-dynamic-range (HDR) imaging is required, with new pixel architectures that overcome the inherent performance tradeoffs of the current devices. Ideally, such new HDR architecture must be able to generate a very large signal-range extension from just a single exposure of the pixel.
