Patent ID: 7821558

Claim:
An image sensor comprising an assembly of pixels, coding means providing an address for each of said pixels and a generator of a reference voltage having, in pixel detection operations, the shape of a staged voltage ramp, each pixel comprising: a photodetector; a switch controllable by a sampling signal and placed between the photodetector and an internal node; a comparator operable to compare a voltage of the internal node and the reference voltage; a first triggering device capable of activating a vertical request line when the comparator output is at a first predefined “0” or “1” logic level; an AND-type gate receiving the vertical request line and a vertical acknowledgement line; a second triggering device capable of activating a horizontal request line when the output of the AND-type gate is active; and a locking device forcing the output of the comparator to a second predefined level, different from the first predefined level, when the vertical request line and a horizontal acknowledgement line are activated, the locking device further receives an initialization signal enabling unlocking the comparator output.