Nikon patent application for phase detect auto-focus
Reading through this patent, this patent seems to be an over-arching patent for phase detect autofocus for both mirrorless (1-2 embodiments) and also DSLR's (fourth embodiment).
The patent describes lines of phase detect pixels that can be used to calculate distance and defocus amounts.
In the first series of embodiments, these phase detect pixels are part of the image sensor, in the forth embodiment, it's packaged up into a specific "focus detection module" as part of the normal DSLR phase detect sub assembly.
Instead of lines of phase detect pixels, the DSLR phase detect assembly has all phase detect pixels as shown below;
Nikon shows phase detect pixels as either being half masked, or even full dual pixel phase detect pixels. In the above illustration, it appears as if Nikon is using a small image sensor with all dual pixel AF pixels.
From what I gather from this patent, this is a good method of re-using technology between mirrorless and DSLR's - possibly also making it much easier for firmware development as well.
Patent Application 2019-148817