First high-sensitivity CMOS image sensor

Louise Smyth

Sony has launched a commercial version of a 2.45 megapixel CMOS image sensor for automotive cameras that is the first with a LED flicker mitigation function that reduces flickering when shooting LED signs and traffic signals, as well as an HDR function capable of 120dB wide dynamic range shooting.

The e IMX390CQV type 1/2.7 uses Sony’s original 3.0μm (H) × 3.0μm (V) pixel structure and exposure method to capture high-quality colour images even in light conditions as low as 0.1lux, which is equivalent to moonlight.

In recent years, LEDs have been widely adopted for traffic signs and signals, and also for car components such as headlights and brake lights.

Another trend has been the need for automotive cameras to be able to capture high-quality images with a wide dynamic range, even in situations of dramatic contrast, such as when entering or exiting tunnels during daylight hours.

This image sensor simultaneously uses both the LED flicker mitigation and HDR functions to deal with these types of situations, providing more precise recognition in the diverse real-world traffic environments that drivers encounter.

The IMX390CQV is planned to meet the requirements of the AEC-Q100 Grade 2 automotive electronic component reliability tests, and has been developed with ISO26262 automotive functional safety standards and ASIL C.

By meeting these standards and quality requirements for automobile components, the product is ready for use in forward-sensing cameras for Advanced Driver Assistance Systems (ADAS) and cameras for Camera Monitoring Systems (CMS) that show persons and obstacles on an in-car monitor with clear visibility, an application expected to grow as a substitute for conventional rearview mirrors.

Automotive cameras also have to be able to capture clear overall images with minimal noise, no loss of shadow detail, and no highlight blowout, even in situations of dramatic contrast, such as when entering or existing tunnels in the daytime, or driving in urban areas at night.

The 120dB wide dynamic range shooting with low noise allows this.

The sensor is also equipped with circuits possessing improved efficiency when converting electronic signals received from photodiodes to voltage signals. This delivers the high sensitivity, approximately 1.5x that of conventional image sensors for 2.0 megapixel class automotive cameras to capture high-quality colour images even in light conditions as low as 0.1 lux.

Euro NCAP has decided to include night time pedestrians as targets for automatic braking collision avoidance systems in 2018 which will drive increased demand for high-sensitivity, high-quality image capture capabilities in the automotive camera market.

The 10.0 x 10.6mmsensor includes a MIPI CSI-2 serial output (4 lane / 2 lane) and is packaged in a 96pin plastic BGA. Samples are available this month with volume production in 2018.