Canon Patent Application: Quad Pixel Auto Focus sensor
This patent application from Canon deals with a quad pixel autofocus sensor. Right now Canon is using dual pixel auto focus sensors, but if you ever tried to use an EOS R or an EOS M in landscape orientation to focus on a horizontal line you'll quickly realize that the phase detect sensors just go in one direction, and have little sensitivity in the other 90 degrees offset direction.
This patent application indicates that Canon has split the pixel into 4 pieces, and also offsets the microlenses as you go further out from the center.
About this sensor;
Therefore, there is the object of this invention in providing the image sensor which can always perform focus detection by an image surface phase difference system with high precision, and the imaging device using this image sensor.
In order to achieve the above-mentioned object, the image sensor by the present invention, A plurality of optical waveguides which a unit pixel part provided with a plurality of pixels is the image sensor arranged by two-dimensional matrix form, and draw light to said plurality of pixels, respectively, It has the segregant formed among said plurality of waveguides, the height and position of the aforementioned segregant are changed according to image height, and the pupil distance of said plurality of pixels is changed in each of the aforementioned unit pixel part.
The sensor they are describing in this document seems to be a 20.7MP sensor, with 83 million focus detection points! The pixel size seems to be 4 micrometers, which would make that approximately 22mm on the width (5575x3725) or in other words an APS-C sized sensor.
A unit pixel has the 1st focus detection pixel 201, the 2nd focus detection pixel 202, the 3rd focus detection pixel 203, and the 4th focus detection pixel 204, and these pixels are arranged by two lines x two rows. In the illustrated example, although the pixel structure of four lines x four rows is shown, the many pixel is actually arranged by two-dimensional matrix form. For example, the image sensor is 4 micrometers in the cycle P of a pixel, and is side [ of 5575 lines ] x [ 3725 rows ] long = about 20,750,000 pixels in the pixel number N. The image sensor is 2 micrometers in the line writing direction cycle PAF of a focus detection pixel, and is side [ of 11150 lines ] x [ 7450 rows ] long = about 83,060,000 pixels in the focus detection pixel number NAF.
Could Canon be looking at decreasing the pixel density, and coming out with a new Quad pixel AF sensor (QPAF)? It's certainly possible.
Canon we know is using 180nm technology for its APS-C sensors that also can incorporate copper wiring. This is most likely good enough for a 20MP sensor. The increased efficiency loss because of splitting up the pixels, would most likely cause Canon to consider going from 24MP dual pixel AF down to 20MP quad pixel AF.
How do we know Canon is using 180nm for certain? Actually from a newly found TechInsights summary on the 80D sensor:
This report is a partial Circuit Analysis of the CMOS image sensor (CIS) of the Canon LC1480B, extracted from the Canon EOS 80D DLSR camera. The Canon LC1480B features a 24.2 MP sensor. The Canon LC1480B is fabricated using a four metal, single polysilicon, 180 nm CMOS process, with a die seal size of 27.8 mm by 18.8 mm.
Japan Patent Application 2019041178
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