CMOS automotive camera sensor reduces LED flicker

CMOS automotive camera sensor reduces LED flicker

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Sony (Tokyo, Japan) has disclosed details of a commercially-available CMOS image sensor for automotive cameras: at 2.45 (effective) megapixels, the IMX390CQV type 1/2.7 will begin sample shipping in May 2017.
By Rich Pell

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This image sensor is equipped with an LED flicker mitigation function that reduces flickering when imaging LED signs and traffic signals, as well as an HDR function capable of 120 dB wide dynamic range imaging. Sony believes this is the first time both attributes have been available together, enabled by Sony’s pixel structure and exposure method. It also offers high-sensitivity performance capable of producing high-quality colour images even in light conditions as low as 0.1 lux, 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 this fiscal year. With this new product, Sony also introduced a development process that complies with ISO26262 functional safety standards.

The sensor also meets the functional safety requirement level ASIL C. 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.

LED signs and the LED lights of cars in front and behind the vehicle can be accurately recognised while enabling wide dynamic range image capture with no highlight blowout or loss of shadow detail in situations of dramatic contrast, such as when entering or exiting tunnels.

LEDs are widely used for traffic signs and signals as well as automobile headlights and taillights. This means that automotive cameras must be able to capture these elements accurately, although they are in fact being driven with a fast pulse waveform.

When caught on camera they can “strobe” or generate an effect known as LED flicker. This image sensor has addressed this issue by making the exposure time longer than the LED flicker frequency, thereby minimising the likelihood of flicker; it mitigates LED flicker from LED light sources (frequency > 90 Hz) stipulated in EN12966. A video clip is here; www.youtube.com/watch?v=UPdlt59krEc

The image sensor features a Sony pixel structure and exposure method that delivers an HDR function capable of 120 dB wide dynamic range shooting with low noise. A video clips is at; www.youtube.com/watch?v=CuvTQS2pEtw

Sensitivity is claimed to be approximately 1.5x that of conventional image sensors for 2.0 megapixel class automotive cameras (according to Sony research). This capability enables the sensor to capture high-quality colour images even in light conditions as low as 0.1 lux, which is equivalent to moonlight, enhancing camera reliability in rendering obstacles and persons.

 

Model name

IMX390CQV

Number of effective pixels

2017 (H) × 1217 (V), approx. 2.45 megapixels

Image size

Diagonal 6.67 mm (type 1/2.7)

Unit cell size

3.0 µm (H) × 3.0 µm (V)

Frame rate

Full-HD1080p

AD10bit 60fps, AD12bit 40fps

Sensitivity (F5.6 standard value, 1/30 second storage time)

1,953mV (green pixel)

Dynamic range (EMVA1288 standard)

120 dB
110 dB (When HDR function and LED flicker mitigation function are used simultaneously)

Saturation signal (minimum value)

700mV

Power supply

Analog

2.9 V

Digital

1.2 V

Interface

1.8 V

Interface

MIPI CSI-2 serial output (4 lane / 2 lane)

Package

96pin plastic BGA

Package size

10.0mm x 10.6mm

Sony: www.sony-semicon.co.jp

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