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The following is sponsored by OMNIVISION, a leading global developer of semiconductor solutions, including advanced digital imaging, analog and touch, and display technology. OMNIVISION has launched its new OX08D10 CMOS image sensor with TheiaCel™ technology for superior image quality regardless of the lighting conditions.
SOLUTION
OX08D10 8 Megapixel CMOS Image Sensor w/ TheiaCel™ Technology
DESIGNED & ENGINEERED BY
OMNIVISION TECHNOLOGIES
KEY FEATURES
Low-Light Performance, High Dynamic Range, LED Flicker Mitigation, Small Size
APPLICATIONS
Exterior Cameras for ADAS and Autonomous Driving
SAMPLING
AVAILABLE NOW
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To address these challenges for OEM customers, OMNIVISION has launched its OX08D10 8MP CMOS image sensor with TheiaCel™ technology at AutoSens Brussels 2023. The OX08D10 with TheiaCel™ combines essential features for safety-critical applications, including HDR, low-light performance, LFM, small size, and low power consumption. The OX08D10 with TheiaCel™ eliminates unnecessary “trade-off” situations for OMNIVISION customers concerned about sacrificing one performance attribute for the other.
“For example, you might be able to see clearly inside the tunnel, but everything will be saturated outside,” explained Tomas Geurts, Senior Director of the OMNIVISION European R&D Centers, pointing to the challenges of LED flicker after emerging from the tunnel. “Conversely, the outside may be clear, but inside the tunnel, everything will be dark. Neither situation works, so you need technology that addresses this.”
“The new OX08D10 image sensor provides automotive OEMs with one device that combines all of the most important features, eliminating the need for our customers to make performance and design compromises to address LED flicker, as they have in the past,” said Dr. Paul Wu, Automotive Product Marketing Manager at OMNIVISION.
To offer OEM customers the most advanced solution, the OX08D10 with TheiaCel™ builds upon prior OMNIVISION innovations, including Dual Conversion Gain (DGC) HDR Technology.
OMNIVISION’s proprietary DGC HDR technology extends the dynamic range in a single exposure to reproduce motion-artifact-free and ultra-low-noise images in challenging and low-light conditions, like the tunnel example Geurts used. In DCG pixels, photoelectrons from a photodiode are read out twice in different gains: low-conversion gain (LCG) for higher light environments and high-conversion gain (HCG) to capture clear images in low-light situations, both resulting in up to 140 dB of dynamic range. OMNIVISION extends the dynamic range without introducing motion blurs and, with its split-pixel technology and very short exposure, achieves 140 dB of dynamic range.
“OMNIVISION is a pioneer in the automotive industry for split-pixel technology, but the OX08D10 is our next-generation product that improves on HDR and LED flicker mitigation,” Dr. Wu said. “We have introduced TheiaCel™ because it improves HDR and LED flicker mitigation performance, two key specs for automotive applications.”
Flicker from LED traffic lights is still a serious challenge for imaging solutions, often preventing ADAS and automated driving systems from correctly detecting and identifying lighted traffic signs. Pulse-width modulation (PWM) in LED light sources creates issues in short exposure time conditions. If that short exposure timing falls between the LED pulses, the sensor misses detecting the LED light. The video stream flicker is created by frames missing the “on” pulse when the sensor tries to capture bright LED light with a short exposure time; however, increasing exposure time to capture the LED pulse causes excess pixel saturation.
“LEDs flicker at a frequency that is not standardized,” Geurts said regarding the challenges of LED flicker, adding that just a short exposure approach will miss essential LED flickers, causing traffic signs to appear incomplete. “You need a substantially long exposure to capture the LEDs during their on-cycle without saturation,” Geurts continued. “That’s the key relationship between OMNIVISION’s TheiaCel™ technology and LFM.”
Ideally, the automotive market needs an LED flicker solution that is easily integrated into a CMOS image sensor, which the OX08D10 with TheiaCel™ finally provides. OMNIVISION also found in its research before the launch of the OX08D10 that some previous approaches, while achieving satisfactory LFM performance, have lacked in other vital areas, such as low-light sensitivity, SNR (signal noise ratio) drop, and split-pixel crosstalk. In other words, existing HDR imaging techniques still struggle to provide consistent performance in terms of the total package: dynamic range, flicker mitigation, and low-light performance.
To ensure its OEM customers have a robust, total package solution, OMNIVISION expanded upon its prior DGC HDR innovations with the introduction of TheiaCel™ technology.
The OX08D10 is the first image sensor that features OMNIVISION’s new 2.1‑micron (µm) TheiaCel™ technology, which harnesses the capabilities of next-generation lateral overflow integration capacitors (LOFIC) alongside DGC HDR technology. TheiaCel™ enables the OX08D10 to achieve an HDR image capture at up to 200 meters, the “sweet spot” for delivering the best balance between SNR1 and dynamic range, and is optimal for automotive exterior camera applications. The combined solution achieves a wider dynamic range than earlier split-pixel HDR architectures.
As noted in OMNIVISION’s research before the launch of the OX08D10, several technologies have been explored for single-exposure HDR for LFM applications, including a DCG and split-diode (large/small photodiode) architecture with attenuation in the small photodiode, or a combination of these. Together, these approaches can achieve a dynamic range of around 100 dB, making them useful for such automotive applications as in-vehicle cameras. Introducing LOFIC enables the creation of 2.1µm LFM sensors with a higher total dynamic range, allowing OMNIVISION’s customers to achieve optimal object detection across a wide range of applications and temperature ranges.
“We have seen challenging high-temperature use cases, especially for front-vision ADAS cameras,” Dr. Wu explained. “For example, in the summer, when the vehicle just starts, the ambient temperature is high, leading to a potential sacrifice of the image quality or the image sensor may stop functioning altogether. Because of TheiaCel™ and its high SNR and low power consumption, we can solve this.”
Compared to its non-LOFIC-based predecessor, the OX08D10 with TheiaCel™ technology has a 3.3x higher LFM dynamic range and a nearly three times higher total dynamic range.
HDR imaging has entered an era in which existing solutions cannot address some key requirements, such as LED flicker and image quality. As the leading provider of CMOS image sensors for the automotive market, OMNIVISION is building on its proven solution portfolio with the new TheiaCel™ LFM sensor family. The technology’s advanced LFM range will enable HDR imaging to address challenging sensor use cases, mitigating LED flicker regardless of the lighting conditions.
The OX08D10 with TheiaCel™ technology will be in mass production in the second half of 2024. Sampling is available now. For more information, contact an OMNIVISION sales representative.
The OX08D10 features OMNIVISION’s a‑CSP package technology for the smallest possible solution (50 percent smaller than other exterior cabin sensors in its class) and features upgraded cybersecurity measures to comply with the latest MIPI CSE version 2.0 standards.
