Automatic Extended High Dynamic Range Image Sensor from Melexis focuses on Driver Assistance and Night Vision Systems

On-chip automatic HDR control function simplifies camera design

June 21, 2011 - Tessenderlo, Belgium. Melexis announces the launch of a new image sensor in the “Avocet” series, the MLX75412 extended HDR Image Sensor. The MLX75412 includes two on-chip functions: a high performing fully automatic Extended HDR and exposure control function named “Autobrite®” and an adaptive histogram remapping function named “Autoview™”. With these functions, a full feature set is offered which greatly simplifies building HDR cameras.

Focus applications include automotive driver assistance and night vision applications, security/surveillance applications, fleet safety cameras, truck blind spot cameras, transportation/heavy vehicle cameras, and other outdoor and all weather cameras.

The Avocet series are wide-VGA image sensors with a 1024x512 pixels resolution. They feature an extended high dynamic range (Extended HDR) up to 154dB in every single frame with a full resolution frame rate up to 60fps. Sensitivity in terms of SNR10 is 25nW/cm2 @ 25degC @ 535nm.

This low light performance combined with the extended HDR offers excellent picture quality during day and night time and thus enhances safety for driver assistance systems.

Lane Departure Warning and Forward Collision Warning

In the US, the National Highway Traffic Safety Administration (NHTSA) has changed New Car Assessment Program (NCAP) requirements for the 2011 model year. The familiar five-star crash test ratings score shown on the window sticker will also designate the presence of camera based Lane Departure Warning (LDW) and Forward Collision Warning (FCW) features.

Cliff De Locht, Product Line Manager at Melexis comments: “In side by side tests with other automotive imagers, we have seen situations where – depending on the position of the sun – the Avocet imager was able to distinguish faded lane markings where other image sensors failed.”

“Technically speaking, because the Extended HDR technology is based on 6 partial pixel resets within an exposure period, the Avocet allows tight control of the response curve to maximize picture details at all light intensities. Fully automatic Autobrite uses this capability at maximum to dynamically and automatically optimize the image sensor response on a frame-by-frame basis.”

“The bottom line is that Autobrite is able to swiftly and automatically adapt to any lighting condition, including extreme light conditions like when you are driving towards the sun. This results in improved detection performance for lanes, vehicles and pedestrians.”

Night Vision

Dynamic range at dawn or at night is most important. During nighttime, the brightest lights, like an approaching car’s headlights, come close to sunlight intensities while the dark areas go much lower in light intensity The result is a stretching of the dynamic range of low light scenes to 120dB and higher.

The MLX75412 Avocet with Autobrite function is perfectly fit to cope with these extended HDR requirements. On top of that, the Avocet features enhanced responsivity for near infrared light (800-1000nm). Last but not least, an anti-reflective coating on the Glass-BGA is specially designed for night vision, featuring minimal light reflectivity in the range 400-1000nm, to minimize stray light for visible and for near-infrared light.

Cliff De Locht, Product Line Manager at Melexis comments: “We did extensive night drive testing with the MLX75412 and are thrilled with the (monochrome) night sensitivity and behavior of the Autobrite Extended HDR function. We are confident this offer gives an adequate response to the many low light and HDR requirements out there.”

Samples

The MLX75412 “Avocet” image sensor is available in 4 versions: monochrome, RCCC, color RGBG and color RGBi..