Solid-state image pickup element having a control circuit for controlling the operation period of a transfer circuit and method for controlling the same

A method for controlling a solid-state image pickup element comprising a plurality of pixel circuits, wherein

• each of said pixel circuits includes a light detector element generating a signal charge in response to light reception;
• an accumulating region accumulating the signal charges generated by said light detector element;
• a floating diffusion region;
• a transfer circuit configured to transfer the signal charges in said accumulating region to said floating diffusion region when being operated, while being configured to stop the transfer when not being operated;
• and
• a reset switch for electrically connecting a power supply node supplying a reset potential to said floating diffusion region prior to an operation of said transfer circuit,
• said control method comprises the steps of:
• accumulating said signal charges generated by said light detector element in said accumulating region while said transfer circuit is not operated;
• operating said transfer circuit during a complete transfer period required for said transfer circuit to transfer a maximum signal charge accumulative quantity in said accumulating region from said accumulating region to said floating diffusion region, and
• additionally transferring said signal charge generated by said light detector element after said step of operating, to said floating diffusion region by continuing the operation of the transfer circuit during a first period after said complete transfer period,
• said reset switch is controlled so as to keep an electrically separated condition between said floating diffusion region and said power supply node while said transfer circuit is operated, and
• a capacitance value of said floating diffusion region is not less than a sum of a first capacitance value required to receive said maximum signal charge accumulative quantity, and a second capacitance value required to receive said signal charges generated by said light detector element during said first period.

A solid-state image pickup element comprising:

• a pixel circuit including a light detector element generating a signal charge in response to light reception, an accumulating region accumulating the signal charges generated by said light detector element, a floating diffusion region and a transfer circuit configured to transfer the signal charges in said accumulating region to said floating diffusion region when being operated, while being configured to stop the transfer when not being operated;
• and
• pixel controlling means for controlling the transfer of said signal charges, wherein
• said pixel controlling means controls said transfer circuit based on a light receiving level of said pixel circuit so as to extend an operation period of said transfer circuit in a case where a light receiving quantity is not lower than a predetermined quantity, contrary to a case where said light receiving quantity is lower than the predetermined quantity.