Advanced global shutter image sensor for affordable, reliable driver safety systems

STMicroelectronics enhances vehicle safety with its latest global shutter image sensors for driver monitoring systems (DMS).

DMS constantly monitors the movements of the driver’s head to detect signs of drowsiness and distraction, which allows in-vehicle systems to generate warnings that can keep passengers safe. Road agencies estimate that about 95% of road accidents are the result of human error, many of which can be avoided with systems such as DMS. With almost 19,000 people killed in accidents in Europe in 2020[1]recently adopted legislation will impose a DMS on all new car platforms in Europe in 2024 and on existing platform models in 2026. With twice as many traffic deaths in the US[2]The National Transport Safety Council (NTSB) has recommended a DMS for all semi-autonomous vehicles.

The new global prison sensor, VB56G4A, uses ST’s internal investment in the production of advanced 3D-arranged backlit (BSI-3D) image sensors. These are more sensitive, smaller and more reliable than conventional front light sensors (FSI), which are commonly used in first generation DMS.

ST is delivering samples of its new sensor to leading customers now and mass production is planned for early 2023 for acceptance in vehicles from the 2024 model year.

The global shutter sensor offers great advantages over moving shutter images. By simultaneously exposing all pixels of the image, the global shutter sensor allows easy synchronization with NIR lighting, improving the power budget of the lighting subsystem. In addition, the new sensor achieves high quantum efficiency (QE), reaching 24% at 940nm near infrared wavelength, with a linear dynamic range of up to 60dB. This allows a simple invisible low power LED emitter to provide adequate lighting for the sensor. Working outside the visible spectrum also provides a constant response during day or night driving and in light or cloudy conditions.

The sensor’s high QE, combined with a pixel size of just 2.6 µm, helps optimize overall power consumption and camera size. In addition, the integrated automatic exposure control simplifies the use and simplifies the design of the application software by minimizing the interaction of the system with the sensor.

The sensor also provides flexible modes of operation that help optimize system performance and performance. These include programmable sequences of 4-frame contexts, lighting control outputs synchronized with sensor integration periods, external frame start signal input, automatic dark calibration, dynamic defect pixel correction, image cropping and reading. mirror / back image.

External connections include eight programmable general-purpose I / O pins (GPIO) and a dual-band MIPI CSI-2 transmitter interface running up to 1.5 Gbps per bandwidth. The sensor can operate at up to 88 frames per second (fps) at full resolution, and the typical power consumption is 145 mW at 60 frames per second.