I say that because people assume that it will work with DPAF and I understand DPAF.
I don't know Japanese, but I won't be surprised if the patent says nothing about DPAF at all.
Follow the link. Click on English in the upper right corner. It does go thru the DPAF process in fine detail.
Prior to the part where different amplification is applied to one of the pixels, the pixels are both operating in normal mode with no differential amplification and a DPAF is performed as usual. Then, the additional amplification is applied, the output averaged, and sent to the D/A converter. A 2nd method involves the D/A converter as part of the averaging, its done as a full frame, or individual pixel columns. Lots of things are happening in a very short period, most of them normal things that happen for every digital photo, but they step thru it all.
They have a single transistor switch that switches from averaged output to separate output so its very fast. But as I said, lots of things are happening to make it all work smoothly.
This is the description / chart for DPAF, you need to see the entire patent to see what parts of the circuit they refer to. There is a 2nd figure for how the part works with different ISO for each half of the pixel. Then, there are alternate methods ...
1) AF read mode
Referring to FIG. 3, a reading method (referred to as an "AF reading mode" or an "AF reading") for acquiring phase difference information from an object will be described. In the AF reading, the amplification gains of the 1 read circuit 211 - 1 and the 2 read circuit 211 - 2 are set to be equal. At time t 1, SEL 1 and SEL 2 are set high, and the pixel of the corresponding row is set to the select state. At time t 2, RES 1 and RES 2 are set low to end pixel reset. Thereafter, sampling of the noise level is performed until time t 3. At time t 3, TX 1 and TX 2 are set high, and charge transfer from the photoelectric conversion unit is started. At time t. sub. 4, TX. sub. 1 and TX. sub. 2 are low and charge transfer is terminated. Thereafter, sampling of the signal level is performed until time t 5. At time t 5, RES 1 and RES 2 are set high, and pixel reset is performed. At time t 6, SEL 1 and SEL 2 are turned low, and the pixel selection is canceled. During time t 1 to time t 6, ADD is always low, and the signals corresponding to the photoelectric conversion units 202 1 2 are individually amplified and input to the signal output circuit 106 independently. By simultaneously performing the AF reading by the 2 photoelectric conversion units 202 - 1 and 2 -, it is possible to obtain the phase difference information of the subject. When 2 photoelectric conversion sections 202 - 1 and 2 - are arranged on the left and right sides in a pixel, phase difference information in a horizontal direction is acquired.
When 2 photoelectric conversion units 202 - 1 and 2 - 2 are arranged vertically within a pixel, vertical phase difference information can be acquired.