With the increase of intelligent perception configurations such as high-performance CMOS imaging and lidar in automobiles, the level of automatic driving of automobiles is constantly improving, while reducing traffic accident casualties and improving road safety. Onsemi, a leader in intelligent power supply and intelligent sensing technology, provides a full range of intelligent sensing solutions, including image sensors, ultrasonics, lidars and sensor fusion. Its image sensors have more than 80% market share, and has the advantages of high resolution, high dynamic range (HDR), LED anti-flicker (LFM), safety and reliability, etc., and supports a comprehensive product portfolio, including power management, lighting solutions, motor drivers, system design specialists. Knowledge, reference designs, powerful and flexible development kits, experienced application support, key ISO-26262/ASIL compliant devices, and a broad partner ecosystem to support safe ADAS and Level 2+ autonomous driving 9 lives saved, with the potential to save 81,000 lives annually.
Scalable Image Sensor Platform: Reduce Development Time, Reduce Design Risk, and Meet Evolving Automotive Safety Requirements
ON Semiconductor’s scalable image sensor family includes products ranging from 1.3 megapixels to 8.3 megapixels, with excellent low-light performance and >140 dB high dynamic range, Clarity+ realizes the fusion of perception + vision, and all are AEC compliant -Q100 vehicle specification and ISO26262 ASIL-C, with a common architecture, enabling automotive OEMs to make full use of existing device software and algorithms for efficient development. Among them, the 4.2 um AR0138 is an ideal choice for a cost-effective 720P ADAS camera, with ultra-low illumination, in line with the European New Car Assessment Program (Euro NCAP); the 4.2 um AR0220 has a slightly higher resolution than AR0138; AR0820 has a resolution of up to 8.3 million Pixel for night-time forward-looking ADAS and higher levels of autonomous driving.
AR0820 High Resolution DR-Pix
High resolution is important for autonomous driving. Because the higher resolution enables the system to detect and identify smaller objects. This improves driving safety by detecting objects and other hazards at greater distances, alerting the driver and taking action faster. This is driven by the need for self-driving cars to see farther and have the ability to detect objects of all sizes and shapes. The AR0820 is an 8.3-megapixel, 2.1 um DR-Pix wafer-stacked automotive sensor with 100 times the perception capability of the human eye under all conditions, and wafer stacking technology enables compact camera designs.
High Dynamic Range (HDR) is a key and important parameter of a camera sensor, and is the sensor’s ability to see between the darkest and brightest parts of a scene in the same frame without oversaturation or undersaturation. In other words, the sensor needs to be immune to changes in ambient light conditions, such as sudden exposure to bright sunlight or reflections, or driving in/out of tunnels during the day. The AR0820 offers a high dynamic range of >140 dB up to 185 meters for the harshest lighting conditions and can be used safely and reliably in autonomous driving applications. NIR+ technology enables enhanced near-infrared imaging to provide best-in-class low-light performance for excellent nighttime performance.
With the development of the Internet of Vehicles, it is also important to increase cybersecurity at the sensor level. AR0820 integrates hardware security module, secure boot video authentication and control encryption to ensure reliable and safe operation.
It is worth mentioning that AutoX, the leader of China’s L4-level driverless taxi (RoboTaxi), has adopted 28 AR0820s in its fifth-generation RoboTaxi to fuse with other sensors to achieve high-resolution cameras.
Hayabusa Series: Super Exposure Technology Solves the Challenges of the Automotive Imagery World
The world of automotive imagery often faces the following challenges: real-world scenes typically reach 120-140 dB, extreme conditions in the temperature range below -40C to +105C, to be able to detect pedestrians or cyclists on streets at night to comply with new European cars Assessment Plan (NCAP), and flashing traffic lights/LED street signs.
Hayabusa addresses the above challenges of extreme temperature conditions, high dynamic range, LED anti-flicker, functional safety, and NCAP evaluation criteria, and is a breakthrough technology for automotive image perception systems. This family has a common architecture and pixels to provide >140 dB ultra-high dynamic Range (HDR) while suppressing LED flicker, Backside Illuminated (BSI) technology, AEC-Q100 Grade 2 and ISO26262 ASIL-B compliant, suitable for ADAS, Surround View (SVS), Reverse Vehicle (RVC), Mirror, Auto driving and many other market segments.
Among them, AR0233AT is a 2.6-megapixel 1/2.5-inch BSI HDR automotive sensor, using super-exposure 3.0 um BSI pixels (the HDR pixel technology previously used in the high-end film industry), with excellent low-light performance and programmable flexibility for exposure control , Single exposure dynamic range > 95 dB, multiple exposures can make dynamic range > 140 dB, 1080p image at 60 fps in 120 HDR+LFM mode, on-chip HDR reduces system cost, in addition, with low noise, low power consumption Architecture system, functional safety is in a leading position, and the output interface reaches 24-bit RAW.
Hayabusa Super Exposure Pixel Concept
More power-efficient pulsed LED lighting is usually used in automotive headlights, taillights, and traffic signs. In bright scenes, short-term exposure of the sensor will cause the light pulse to be lost and the image to flicker. ON semiconductor develops and owns the intellectual property (IP) for super-exposure pixels and large and small pixel architectures, which the company believes are the best choice for vision and ADAS functions, by testing actual products in automotive application environments and exposure time ranges. Determine the right balance to ensure superior super-exposure pixel image/video quality (noise, color, sharpness, and detail) with the required ability to suppress LED flicker. Super-exposure pixels are easier to scale to smaller sizes and do not have the severe pixel crosstalk drawback of large and small pixel structures, providing more advantageous manufacturing costs for camera design, reducing lens costs and production accuracy requirements.
Hayabusa Super Exposure Pixels have 5 times the electronic capacity of ordinary pixels, long exposure to capture pulsed light without oversaturation, and optimized for human vision + machine vision, supporting >95 dB dynamic range while avoiding flicker or motion artifacts (>100ke-full well capacity) up to 60 fps and by adding very short T2 (~1/64 –~1/256 ratio) to achieve over 120 dB dynamic range and minimize HDR+LFM motion artifacts .
Performance Evaluation: AR0233 VS Competing Devices
The SNR of the multi-frame merge transition area: The noise in the image fusion transition area, that is, the V-minimum value of the SNR drop, is an important factor when evaluating HDR performance. This signal-to-noise minimum is sensitive to temperature and decreases further with increasing temperature. Competitors have higher noise in low light. AR0233 shows higher dynamic range; competitors are limited by fixed optical PD ratios. Due to higher sensitivity, AR0233 has higher SNR in low light, and can maintain SNR > 30dB in bright HDR scenes; competing products are limited by small pixel noise, which has dropped to 20 dB, and the higher the temperature, the more the SNR declines. more, the dynamic range is reduced, resulting in performance degradation.
HDR+LFM: Dynamic range, the range, expressed in decibels, from low noise in low light (SNR = 1) to the signal saturation point of the HDR frame. Flicker is defined as the on and off of the pulsed light source; the flicker can be suppressed by limiting the minimum exposure time to longer than the minimum pulse period. To measure the ability to suppress LED flicker, the modulation results of the image sensor output when inputting LED pulses of different frequencies can be measured. In testing, the competitor had a smaller dynamic range (saturated traffic lights and headlights) and no on/off flickering in both sensor images (speed limit signs and tail lights).
Motion Artifacts: Differences in the smearing of objects in moving scenes and the timing of HDR multi-frame captures, resulting in the degree of motion “ghosting” in the image. Unlike the previous generation 3-exposure HDR, SuperExposure+T2 offers minimal motion artifacts and natural blur with a short exposure time of just 1 microsecond. Schemes based on large and small pixels do not exhibit this tiny ghosting, but produce artifacts as described earlier.
Focus on real-time functional safety
Image sensors are the eyes of the vehicle, and functional safety detection is critical to system evaluation and response, and real-time safety mechanisms allow the system to evaluate every frame of response, enabling safer designs. ON Semiconductor’s automotive image sensors put real-time functional safety first. During more than ten years of accumulation, ON Semiconductor has collected more than 8,000 failure images and built a failure image library. The algorithm platform can perform fault modeling, simulation enabling algorithm verification and system behavior analysis based on this database.
Summarize
Intelligent perception schemes are at the core of advanced safety and autonomous capabilities, and as vehicles evolve toward more advanced safety and autonomy, improved performance in perception schemes is opening the way for higher levels of safety and autonomous driving capabilities. As the largest supplier of automotive image sensors, ON Semiconductor provides sensors with industry-leading high dynamic range, LED anti-flicker (LFM) and low-light sensitivity, complying with automotive regulations and focusing on functional safety, such as the latest AR0820 and AR0233, Automotive imaging challenges, coupled with perception solutions such as ultrasonic, lidar, and sensor fusion, make roads safer, and highly scalable imaging platforms, plus power management, lighting solutions, motor drivers, reference designs and development kits, etc. Developing new products is more flexible and efficient.
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