Sensor de imagem de obturador global avançado aprimora os sistemas de monitoramento de driver

Advanced Global Shutter Image Sensor Enhances Driver Monitoring Systems

STMicroelectronics, a global semiconductor supplier serving customers across the spectrum of electronics applications, is improving vehicle safety with its latest global shutter image sensors for driver monitoring systems (DMSs).

DMS continuously monitors the driver's head movements to recognize signs of drowsiness and distraction, allowing vehicle systems to generate warnings that can preserve occupant safety.

Transit agencies estimate that about 95 percent of traffic accidents result from human error, many of which could be avoided using systems like DMS.

With nearly 19,000 crash deaths in Europe in 2020, recently enacted legislation will require DMS for all new car platforms in Europe by 2024 and for existing model platforms by 2026. With the number of traffic deaths twice as high in the U.S. , the National Transportation Safety Board (NTSB) recommended DMS for all semi-autonomous vehicles.

“Drivers may not realize they are unsafe to drive due to fatigue or distraction. DMS eliminates uncertainty by automatically detecting the problem, which protects all occupants as well as others traveling on the road,” said Eric Aussedat, executive vice president and general manager of the imaging subgroup at STMicroelectronics. “Our latest global shutter sensors offer sensitivity and compactness, simplifying DMS hardware and reducing overall system cost. This enables our customers and partners to deliver reliable, high-performance DMS systems while meeting regulatory expectations.”

The new global shutter sensor, VB56G4A, leverages ST's internal investment in manufacturing advanced 3D stacked back-illuminated (BSI-3D) image sensors. They are more sensitive, smaller, and more reliable than conventional front-side illuminated (FSI) sensors typically used in first-generation DMSs.

ST is providing samples of its new sensor to leading customers now and mass production is scheduled for early 2023 for adoption in 2024 model year vehicles.

Technical information

The global shutter sensor offers major advantages over shutter imagers. By simultaneously exposing all image pixels, a global shutter sensor enables simple synchronization with NIR lighting, improving the lighting subsystem's power budget.

Furthermore, the new sensor achieves high Quantum Efficiency (QE), reaching 24 percent at the near-infrared wavelength of 940 nm, with a linear dynamic range of up to 60 dB. This allows a simple, low-power, non-visible LED emitter to provide adequate illumination for the sensor. Operating outside the visible spectrum also ensures consistent response during day or night driving and in bright 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. Additionally, integrated automatic exposure control facilitates use and simplifies application software design by minimizing system-sensor interaction.

The sensor also offers flexible operating modes that help optimize system resources and performance. These include programmable sequences of four-frame contexts, lighting control outputs synchronized with sensor integration periods, an input for an external frame start signal, automatic dark calibration, dynamic correction of defective pixels, image cropping and a mirror/inverted image reading.

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

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