Patent ID: 7755017

Claim:
An image pickup device comprising: a plurality of pixels arranged in matrix form with rows and columns, the plurality of pixels configured to convert an incident-light amount into respective electric signals; a plurality of analog-to-digital converters arranged to convert analog signals output from a group of rows and/or columns of the pixels into digital signals, one analog-to-digital converter comprising a first comparator and a first counter coupled in series, another analog-to-digital converter comprising a second comparator, an inversion circuit and a second counter coupled in series, the inversion circuit being effective to invert the output of the second comparator; and a reference voltage generator which generates a ramping voltage signal as a reference signal, wherein, each comparator compares the analog signal output from a pixel against the reference signal, each counter counts a signal output from its respective comparator during a reset counting period and a data counting period, the first comparator counts during a portion of the reset counting period and a portion of the data counting period from the beginning of the respective period until the reference signal is equal to the voltage of the analog signal, and the second comparator counts during a portion of the reset counting period and a portion of the data counting period from when a voltage of the analog signal becomes equal to the voltage of the reference signal until the end of the respective period.