The scan driver 220 may select, for example, the first and the second row lines. The electrical signals, i.e., 2×1 signals of the pixels located at the first and the second row lines are output to the respective readout line s LL. Namely, the electric signals of the pixels located at the first and second row lines of each column line are output together to the readout line LL and averaged so that the 2×1 binning is performed. The 2×1 binning signals generated in this way are transmitted to the read out circuit 230 via the readout line LL.

Next, the first sampling circuit SC1 samples the 2×1 binning signals transmitted through the readout line LL for a first sampling period SP1.

For this, a first sampling control signal SMP1 having a high level as a turn-on level is generated and simultaneously applied to all of the first sampling circuits SC1 for first the sampling period SP1. Accordingly, the first switch SW1 of the first sampling circuit SC1 is turned on, and the 2×1 binning signal is transmitted and stored in the corresponding capacitor C of the first sampling circuit SC1.

Thereafter, if the first switch SW1 is changed from the turn-on state to the turn-off state, the first averaging control signal SMPE_EQ having a high level as a turn-on level is generated and applied to the connecting switch S3 connected to the first sampling circuit SC1. Accordingly, the connecting switch S3 is turned on, and the capacitors C of the two neighboring first sampling circuits SC1 are electrically connected to each other. Thus, 2×1 binning signals stored in the first sampling circuit SC1 are averaged and the 2×2 binning is performed. The 2×2 binning signal generated like this is stored in each capacitor C.