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Canon Patent Application: Diagonal Cross Sensor AF
Dual Pixel and Quad Pixel sensor arrangements are pretty commonplace in patent applications for the last few years but this is a more novel approach. As Canon mentions the lack of AF sensitivity when you are aligning with the pixel, doesn't disappear when you move to quad pixel (which the AF can detect phase difference on both horizontal and vertical lines of contrast, instead, you'll still have two areas in which the AF sensitivity will dip. This patent application attempts to reduce this by going back to what DSLRs had which was a diagonal cross arrangement of AF sensors.
I'm not exactly how the pixels work, that could be because I'm still suffering from COVID, or it could be entirely way beyond my paygrade. I'll take it from Canon, that the pixel designs "just work", but they look quite inventive to me.
Also interesting is that this sensor mentioned is not a standard Bayer array but an RGBW sensor arrangement. I don't think I've seen that mentioned much in Canon's patent literature.
In Canon's patent language (and machine-translated terms) that comes out as;
Generally, the focus of the phase difference method In the detection, there is a problem that the accuracy of the focus detection is lowered when the brightness pattern of the subject, that is, the direction in which the brightness changes is close to the division direction of the pupil division signal. 0006
Even if an image sensor that divides the pupil division signal in a total of four directions by combining the pixels described in Patent Document 1 in order to increase the division direction, the characteristics are not aligned between the pixels having different division directions, and the pupil The image signal obtained by adding the divided signals for each pixel will vary.
The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to increase the division direction of the pupil region while suppressing variations in the sensitivity of image signals.
Japan Patent Application 2022-002383
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