Imaging device, imaging system, and drive method of imaging device

A drive method of an imaging device comprising

• a pixel unit including a plurality of pixels that are arranged in a matrix and each output a pixel signal in accordance with a received light amount,
• a reference signal circuit that outputs a first reference signal and a second reference signal, wherein voltages of the first and second reference signals respectively change in dependent on time and a voltage change per unit time of the first reference signal is different from a voltage change per unit time of the second reference signal, and
• a plurality of column circuits each of which is provided on a corresponding column signal line of the pixel unit and includes a selector circuit that selects either the first reference signal or the second reference signal and a comparator that outputs a comparison signal indicating a result of comparison between the pixel signal and a reference signal selected by the selector circuit,
• wherein the plurality of column circuits include a first column circuit that operates in a first drive mode and a second column circuit that is driven by a smaller current than a current of the first column circuit,
• the drive method comprising:
• at the column circuits, operating selectively in the first drive mode to output the comparison signal or a second drive mode to acquire a correction value of a ratio between the voltage change per unit time of the first reference signal and the voltage change per unit time of the second reference signal;
• and
• at the selector circuit of the second column circuit, selecting the same reference signal out of the first reference signal and the second reference signal in the first drive mode and the second drive mode.

An imaging system comprising:

• an imaging device;
• and
• a signal processing device that processes a pixel signal output from the imaging device,
• wherein the imaging device includes
• a pixel unit including a plurality of pixels that are arranged in a matrix and each output a pixel signal in accordance with a received light amount;
• a reference signal circuit that outputs a first reference signal and a second reference signal, wherein voltages of the first and second reference signals respectively change in dependent on time and a voltage change per unit time of the first reference signal is different from a voltage change per unit time of the second reference signal;
• and
• a plurality of column circuits each of which is provided on a corresponding column signal line of the pixel unit and includes a selector circuit that selects either the first reference signal or the second reference signal and a comparator that outputs a comparison signal indicating a result of comparison between the pixel signal and a reference signal selected by the selector circuit,
• wherein the column circuits operate selectively in a first drive mode to output the comparison signal or a second drive mode to acquire a correction value of a ratio between the voltage change per unit time of the first reference signal and the voltage change per unit time of the second reference signal,
• wherein the plurality of column circuits include a first column circuit that operates in the first drive mode and a second column circuit that is driven by a smaller current than a current of the first column circuit, and
• wherein the selector circuit of the second column circuit selects the same reference signal out of the first reference signal and the second reference signal in the first drive mode and the second drive mode.