BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image pickup element and an image pickup apparatus.

Description of the Related Art

As an image pickup element used in an image pickup apparatus such as a camera or a video, an image pickup element that converts photons incident to a photodiode (PD) into electric charges, accumulates the converted charges, and outputs an amount of the electric charges to serve as an analog amount has been proposed. When the photons are incident to the PD, the PD generates electric charges substantially linearly in accordance with the number of incident photons, and accumulates the electric charges. The electric charges accumulated in the PD are transferred to a floating diffusion (FD) and converted into a voltage. The voltage converted by the FD is amplified by a source follower and input to an A/D conversion circuit located around a pixel array in the form of analog signals.

In recent years, an image pickup element that uses an avalanche photodiode (APD) has been studied. When photons are incident to the APD in a state in which a reverse voltage, which is close to a breakdown voltage, is applied to the APD, avalanche breakdown (electron avalanche) occurs, the APD operates in Geiger-mode, and thereby electric charges caused by avalanche amplification are generated. The number of voltage pulses corresponding to a potential change of the APD in accordance with the generation and discharge of the electric charges is counted, and subsequently, it is possible to treat the number as a digital value. Japanese Unexamined Patent Application, First Publication No. 2010-91378 discloses an image acquisition apparatus that converts the incidence of photons into pulse signals and counts the converted pulse signals by using the APD that operates in Geiger-mode and a quench circuit having a resistance corresponding to the APD.

In the image acquisition apparatus disclosed in Japanese Unexamined Patent Application, First Publication No. 2010-91378, when the APD is operated in Geiger-mode, an electric power that has been consumed in the quench circuit becomes heat to be transmitted to the APD, and thermal noise such as dark current occurs easily.

SUMMARY OF THE INVENTION

An image pickup apparatus according to an embodiment of the present invention comprises: a first substrate configured to be provided with a plurality of light receivers that have a light receiving element that generates electric charges due to avalanche amplification in accordance with the incidence of photons; a second substrate configured to have a first circuit corresponding to each of the light receiving elements; and a connector configured to electrically connect the light receiving element and a first circuit that corresponds to the light receiving element.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

