Method for driving image pickup device, method for correcting digital signal, image pickup device, method for driving image capturing system, and image capturing system

A method for correcting a digital signal that is generated as a result of an analog-to-digital conversion unit performing analog-to-digital conversion on an analog signal, comprising:

• generating, using the analog-to-digital conversion unit, a first digital signal on the basis of a result obtained by comparing a first analog signal with a first reference signal whose potential changes by a first amount per unit time;
• generating, using the analog-to-digital conversion unit, a second digital signal on the basis of a result obtained by comparing the first analog signal with a second reference signal whose potential changes by a second amount per unit time, the second amount being greater than the first amount;
• and
• correcting the digital signal generated using the analog-to-digital conversion unit, on the basis of the first digital signal and the second digital signal.

A method for driving an image capturing system, the image capturing system including

• an image pickup device including
• a pixel configured to output a pixel signal, and
• an analog-to-digital conversion unit configured to convert an analog signal into a digital signal, the analog-to-digital conversion unit including
• a comparison unit configured to output a comparison result signal obtained by comparing an analog signal with a reference signal whose potential changes with time, and
• a signal processing unit configured to process a signal output from the image pickup device, the method comprising:
• generating, using the analog-to-digital conversion unit, a first digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing a first analog signal with a first reference signal whose potential changes by a first amount per unit time;
• generating, using the analog-to-digital conversion unit, a second digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing the first analog signal with a second reference signal whose potential changes by a second amount per unit time, the second amount being greater than the first amount;
• generating, using the analog-to-digital conversion unit, a third digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing a signal based on the pixel signal with the first reference signal or the second reference signal;
• and
• correcting the third digital signal on the basis of the first digital signal and the second digital signal.

An image pickup device comprising:

• a pixel configured to output a pixel signal;
• an analog-to-digital conversion unit configured to convert an analog signal into a digital signal, the analog-to-digital conversion unit including
• a comparison unit configured to output a comparison result signal obtained by comparing an analog signal with a reference signal, and
• a memory unit configured to hold
• a first digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing a first analog signal with a first reference signal whose potential changes by a first amount per unit time,
• a second digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing the first analog signal with a second reference signal whose potential changes by a second amount per unit time, the second amount being greater than the first amount, and
• a third digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing a signal based on the pixel signal with the first reference signal or the second reference signal;
• a reference signal supply unit configured to supply a reference signal whose potential changes with time to the analog-to-digital conversion unit;
• and
• a correction unit configured to correct the third digital signal on the basis of the first digital signal and the second digital signal.

An image capturing system comprising:

• an image pickup device including
• a pixel configured to output a pixel signal,
• an analog-to-digital conversion unit configured to convert an analog signal into a digital signal, the analog-to-digital conversion unit comprising
• a comparison unit configured to output a comparison result signal obtained by comparing an analog signal with a reference signal, and
• a memory unit configured to hold
• a first digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing a first analog signal with a first reference signal whose potential changes by a first amount per unit time,
• a second digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing the first analog signal with a second reference signal whose potential changes by a second amount per unit time, the second amount being greater than the first amount, and
• a third digital signal on the basis of the comparison result signal output by the comparison unit as a result of the comparison unit comparing a signal based on the pixel signal with the first reference signal or the second reference signal, and
• a reference signal supply unit configured to supply a reference signal whose potential changes with time to the analog-to-digital conversion unit;
• a signal processing unit configured to process a signal output from the image pickup device;
• and
• a correction unit configured to correct the third digital signal on the basis of the first digital signal and the second digital signal.