Solid-state imaging element, imaging device, and method for controlling solid-state imaging element

An imaging device, comprising:

• a photoelectric conversion element;
• a front-stage charge holding region;
• a rear-stage charge holding region, wherein a capacity of the rear-stage charge holding region is different from a capacity of the front-stage charge holding region;
• a front-stage transfer transistor configured to transfer a first charge from the photoelectric conversion element to the front-stage charge holding region and the rear-stage charge holding region;
• a rear-stage transfer transistor configured to transfer the first charge from the rear-stage charge holding region to a floating diffusion region;
• an intermediate transfer transistor configured to transfer a second charge, which remains in the front-stage charge holding region after the first charge has been transferred from the rear-stage charge holding region to the floating diffusion region, to the floating diffusion region via the front-stage charge holding region;
• a light-shielding wall configured to prevent the first charge to leak from the photoelectric conversion element to the rear-stage charge holding region;
• and
• a signal processing circuit configured to:
• compare, between a first pixel signal corresponding to an amount of charge transferred from the rear-stage charge holding region and a second pixel signal corresponding to an amount of charge transferred from the front-stage charge holding region and the rear-stage charge holding region, the first pixel signal with a specific threshold;
• select one of the first pixel signal or the second pixel signal based on a comparison result;
• and
• process the selected one of the first pixel signal or the second pixel signal.

A method, comprising:

• in a solid-state imaging element comprising:
• transferring a first charge from a photoelectric conversion element to a front-stage charge holding region and a rear-stage charge holding region which have different capacities;
• transferring the first charge from the rear-stage charge holding region in which leakage of the first charge to the photoelectric conversion element is prevented by a light-shielding wall to a floating diffusion region;
• transferring a second charge, which remains in the front-stage charge holding region after the first charge has been transferred from the rear-stage charge holding region to the floating diffusion region, to the floating diffusion region via the front-stage charge holding region;
• comparing, between a first pixel signal corresponding to an amount of charge transferred from the rear-stage charge holding region and a second pixel signal corresponding to an amount of charge transferred from the front-stage charge holding region and the rear-stage charge holding region, the first pixel signal with a specific threshold;
• and
• selecting one of the first pixel signal or the second pixel signal based on a comparison result.