Solid-state imaging element, method of driving the same, and camera system

Abstract

A solid-state imaging element including pixel signal read lines, and a pixel signal reading unit for reading pixel signals from a pixel unit via the pixel signal read line. The pixel unit includes a plurality of pixels arranged in a matrix form, each pixel including a photoelectric conversion element. In the pixel unit, a shared pixel in which an output node is shared among a plurality of pixels is formed, and a pixel signal of each pixel in the shared pixel is capable of being selectively output from the shared output node to a corresponding one of the pixel signal read lines. The pixel signal reading unit sets a bias voltage for a load element which is connected to the pixel signal read line and in which current dependent on a bias voltage flows in the load element, to a voltage causing a current value to be higher than current upon a reference bias voltage when there is no difference between added charge amounts, when addition of pixel signals of the respective pixels in the shared pixel is driven.

What is claimed: 
     
         1 . A solid-state imaging element comprising:
 pixel signal read lines;   a pixel unit including a plurality of pixels in a matrix form, each pixel including a photoelectric conversion element; and   a pixel signal reading unit configured to read pixel signals from the pixel unit via the pixel signal read lines,   wherein,   the pixel unit includes a shared pixel having an output node shared among a plurality of pixels,   each of the plurality of pixels include a pixel signal configured to be selectively output from the shared output node to a corresponding one of the pixel signal read lines,   the pixel signal reading unit includes (a) a load element (i) connected to the pixel signal read line, (ii) configured to function as a current source, and (iii) in which a current dependent on a reference bias voltage flows, and (b) a plurality of comparators (i) arranged to correspond to a column arrangement of the pixel signal read lines and (ii) configured to compare a read signal potential with a reference voltage for judgment and output a judgment signal, and   the bias voltage for the load element is set to a voltage causing a current value to be higher than the current dependent upon the reference bias voltage when (i) pixel signals of the respective pixels in the shared pixel are driven, and (ii) there is no difference between added charge amounts of the pixel signals read by the pixel signal reading unit.