Patent ID: 9294699
Filing Date: 2016-03-22
CPC Classification: H03M,H04N

Claim Text:
1. A method for driving an image pickup device, the image pickup device comprising: 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 comprising: the method comprising: generating, a first digital signal having the count value generated by the counting unit as a result of counting the clock signal during a period from when the counting unit starts counting the clock signal in response to a timing at which a potential of a first reference signal (Vr1) starts changing at the counting unit by a first amount per unit time, to when a signal value of the comparison result signal obtained by comparing a first test signal being the analog signal with the first reference signal changes; generating, a second digital signal having the count value generated by the counting unit as a result of counting the clock signal during a period from when the counting unit starts counting the clock signal in response to a timing at which a potential of a second reference signal (Vr2) starts changing at the counting unit by a second amount per unit time which is greater than the first amount, to when a signal value of the comparison result signal obtained by comparing the first test signal with the second reference signal changes; and generating, a third digital signal having the count value generated by the counting unit as a result of counting the clock signal during a period from when the counting unit starts counting the clock signal in response to a timing at which a potential of at least one of the first reference signal and the second reference signal starts changing, to when a signal value of the comparison result signal obtained by comparing a signal of the analog signal based on the pixel signal with at least one of the first reference signal and the second reference signal changes, wherein the third digital signal is corrected on the basis of the first digital signal and the second digital signal, so as to reduce an offset which is included in the third digital signal, and arises from a difference between the timing at which the potential of at least one of the first reference signal (Vr1) and the second reference signal (Vr2) starts changing with time, and the timing at which the counting unit starts counting the clock signal.