At this time, no pulse voltage is applied to the storing portion, and the charges stored in (1,1) - (1,4) during exposure are held in [4,1] - [4,4].
The charges stored in two rows, i.e., (1,1) - (1,4) and (2,1) - (2,4) of the image sensing portion, are added to [4,1] - [4,4].