Patent attributes
An image sensor comprises a first circuit board and a second circuit board stacked so as to overlap each other. The first circuit board comprises a pixel region in which first pixels shielded from light and second pixels not shielded from light are arranged in a matrix. Each pixel has a photoelectric conversion unit and a circuit that outputs a pulse signal indicative of incidence of photon. The second circuit board comprises a counter region in which first counters that counts pulse signals from the first pixels and second counters that count pulse signals from the second pixels are arranged in a matrix, and a peripheral circuit region including a circuit that controls driving of the pixels and counters. At least part of the peripheral circuit region is arranged in a region that overlaps with the first pixels.