Comparison of the output voltage Vout according to the present embodiment as indicated in FIG. 4(a) and the output voltage Vout in the comparison example indicated in FIG. 4(c) reveals that a value closer to the ideal average value is achieved through the present embodiment. In addition, the output voltage Vout in the comparison example takes a value close to VoutA over the range of VfdB<V2 (=VfdA), instead of a value with a greatest weight applied to VoutB from the pixel 10 (2, 1) at the central position. In contrast, an output voltage Vout with a weight applied to the pixel signal from the pixel 10 (2, 1) at the central position can be obtained through the present embodiment.
Next, examples of combination processing in which pixel signals from four or more pixels disposed consecutively along the column direction are combined will be explained. While pixel signals from three pixels 10 disposed consecutively along the column direction are combined through the combination processing in the example presented in FIG. 3, any number of pixels 10 may be designated as combination-target pixels. FIG. 5 schematically illustrates combination processing through which pixel signals from a plurality of pixels 10 arranged along the column direction are combined. FIG. 5(a) presents a chart schematically illustrating the relationship among three pixels 10, the pixel signals from which are combined as shown in FIG. 3, the first and second vertical signal lines VL1 and VL2 and the first and second electric current sources 25 and 26.
