Canon research publishes paper on global shutter sensor

global shutterCanon’s research division posted a paper named “Development of Gentle Slope Light Guide Structure in a 3.4 μm Pixel Pitch Global Shutter CMOS Image Sensor with Multiple Accumulation Shutter Technology” (Hiroshi Sekine, Masahiro Kobayashi, Yusuke Onuki, Kazunari Kawabata, Toshiki Tsuboi, Yasushi Matsuno, Hidekazu Takahashi, Shunsuke Inoue, and Takeshi Ishikawa).

The paper describes a concept for a global shutter sensor. The paper’s abstract states:

CMOS image sensors (CISs) with global shutter (GS) function are strongly required in order to avoid image degradation. However, CISs with GS function have generally been inferior to the rolling shutter (RS) CIS in performance, because they have more components. This problem is remarkable in small pixel pitch. The newly developed 3.4 µm pitch GS CIS solves this problem by using multiple accumulation shutter technology and the gentle slope light guide structure. As a result, the developed GS pixel achieves 1.8 e− temporal noise and 16,200 e−full well capacity with charge domain memory in 120 fps operation. The sensitivity and parasitic light sensitivity are 28,000 e−/lx·s and −89 dB, respectively. Moreover, the incident light angle dependence of sensitivity and parasitic light sensitivity are improved by the gentle slope light guide structure.

Canon’s approach to the issue is two-fold (see also the picture after the quoted text):

[…] two key techniques to realize superior optical characteristics while suppressing the reduction of saturation more than the conventional GS pixels. The first technique is the multiple accumulation shutter technology. This technique improves pixel saturation. The second technique is the light guide structure. This technique improves optical performance. As a premise of adopting these two techniques, we first explain the idea of saturation allocation that is important in these techniques.

global shutter

The research paper is publicly available here, and was spotted by Image Sensors World.

Another mention of Canon’s 2/3″ global shutter sensor with wide dynamic range

canon rumors

I reported previously about a global shutter sensor Canon is researching and developing. This sensor made it into the news again. Nikkei Technology reports about the Canon 2/3″ sensor with global shutter and wide dynamic range, which was first presented at ISSCC 2017.

From the ISSCC 2017 lecture, Nikkei reports:

The size, pixel count, pixel pitch and power consumption of the sensor are 2/3 inches, 2,592 x 2,054, 3.4μm and 450mW, respectively. In a demonstration after the lecture, the company used the sensor to take a picture of an electric fan whose blades are turning […]

Through […] improvements, Canon doubled the saturated amount of electric charge and widened dynamic range. Specifically, it increased the saturated amount of electric charge from 8,100 electrons with a frame rate of 120fps to 16,200 electrons with a frame rate of 60fps.

The dark temporal noise of the new sensor is 1.8 electronsrms. As a result, its dynamic range is 79dB with a frame rate of 60fps and reaches 111dB when HDR is applied.

Well let’s hope we see such a sensor in a Canon DSLR soon. Besides this utopian wishes, this is another report that shows Canon’s commitment to develop innovative sensor technology.

The slides below are from the ISSCC 2017 presentation.

[via Nikkei Technology]

Canon develops global shutter-equipped sensor that achieves expanded dynamic range through new drive method

Canon's newly developed sensor
Canon’s newly developed sensor

Canon press release:

Canon develops global shutter-equipped CMOS sensor that achieves expanded dynamic range through new drive method

TOKYO, August 31, 2016—Canon Inc. today announced that it has developed a new CMOS sensor equipped with a global shutter function that, because it exposes all of the sensor’s pixels at the same time, enables the capture of distortion-free images even when shooting fast-moving objects. Employing a new signal-readout drive system and new pixel structure that significantly expands the full well capacity and reduces noise, the sensor contributes to high-image-quality video capture by making possible the realization of a wide dynamic range.

Distortion-free image capture when shooting fast-moving objects

Standard CMOS sensors make use of the rolling shutter method, which sequentially exposes the pixels one row at a time. Because rolling shutters can create slight discrepancies in signal-readout timing depending on the location of the pixel, images of fast-moving objects may appear distorted and flash photography may result in the occurrence of the flash band phenomenon, in which the upper and lower portions of images display different levels of brightness. Because Canon’s newly developed CMOS sensor employs a global shutter, when shooting such fast-moving objects as a rotating propeller or a speeding train, subjects are able to retain their proper form to create distortion-free images. Enabling the confirmation of object shapes with a high degree of accuracy, the sensor offers potential benefits in industrial applications, including as a sensor for use in inspection cameras.

Wide dynamic range realized through new proprietary drive method and pixel structure

When the newly developed CMOS sensor converts light into electrical signals and stores the signal charge in memory, the new drive system achieves a significant expansion in full well capacity. Also, because it employs a structure that efficiently captures light and each pixel incorporates an optimized internal configuration, the sensor makes possible increased sensitivity with reduced noise. The expanded full well capacity, realized through the sensor’s new drive system, and substantial reduction in noise, enabled by the new pixel structure, combine to deliver a wide dynamic range, facilitating the capture of high-image-quality, high-definition footage even when shooting scenes containing large variances in brightness.

Canon will explore various industrial and measurement applications for the newly developed CMOS sensor and consider deploying it in the field of video production for cinema production applications, TV dramas, commercials and more.