Sony Develops 7.42-Mpixel Automotive Image Sensor (4)
Continued from Sony Develops 7.42-Mpixel Automotive Image Sensor (3)
The new image sensor can switch between the standard mode, in which images are taken with a pixel count of 7.42 million, and the binning mode for each frame. For example, at night, it is possible to use the binning mode to recognize an object in the dark for a frame and use the standard mode to recognize a bright object such as an illuminated billboard for another frame.
Sony's previous automotive image sensor changes exposure time and gain for each frame to deal with the problem. When exposure time is increased, the image of a fast-moving object is blurred (motion blur). Also, in the case of low-illuminance imaging, gain cannot be increased much. Therefore, the company employed the method of switching between the standard and binning modes for each frame.
Sony also improved the sensitivity by applying an "RCCC (R: red, C: colorless)" filter for the imaging part. Image recognition is possible with Mobileye's chip without using all of the RGB (red, green and blue) colors. Only the red color was employed probably to increase recognition rate for objects crucial for safety such as red traffic lights and traffic signs.
Detection of image manipulation
The IMX324 is the industry's first automotive image sensor that supports security functions against image manipulation. For example, when an IMX324 different from the IMX324 originally connected to Mobileye's image recognition chip is connected, the chip can detect it.
Also, when a malicious third party transmits an image different from images taken with the IMX324 to Mobileye's image recognition chip, it can be detected. This function was realized by employing a method that uses message authentication codes (MACs).
The new image sensor measures 13.23 x 8.97mm and is contained in a 108-pin BGA package. Sony plans to support "Grade2" of "AEC-Q100" before volume production starts. The sensor complies with "ASIL-B (D)" of the ISO26262 automotive functional safety standard.