Solid-state image sensor, control method for the same, and electronic device

A control method for a solid-state image sensor, the solid-state image sensor including

• a plurality of unit pixels each including
• a photoelectric transducer which generates a charge corresponding to an amount of incident light and accumulates the charge therein,
• a first transfer gate which transfers the charge accumulated in the photoelectric transducer,
• a charge holding region in which the charge transferred from the photoelectric transducer by the first transfer gate is held,
• a second transfer gate which transfers the charge held in the charge holding region,
• a floating diffusion region in which the charge transferred from the charge holding region by the second transfer gate is held to be read out as a signal,
• a charge discharging gate which transfers the charge received from the photoelectric transducer, to a charge discharging part, and
• a structure including an overflow path formed in a boundary portion between the photoelectric transducer and the charge holding region, the overflow path being formed at a potential for determining a predetermined charge amount and transferring a charge exceeding the predetermined charge amount as a signal charge from the photoelectric transducer to the charge holding region,
• the method comprising:
• as a channel electric-potential of the charge discharging gate, setting an electric-potential lower than an electric-potential of the overflow path, or setting an electric-potential higher than the electric-potential of the overflow path and lower than an electric-potential causing the photoelectric transducer to be completely depleted.

An electronic device having a solid-state image sensor mounted thereon, the solid-state image sensor including

• a plurality of unit pixels each including
• a photoelectric transducer which generates a charge corresponding to an amount of incident light and accumulates the charge therein,
• a first transfer gate which transfers the charge accumulated in the photoelectric transducer,
• a charge holding region in which the charge transferred from the photoelectric transducer by the first transfer gate is held,
• a second transfer gate which transfers the charge held in the charge holding region,
• a floating diffusion region in which the charge transferred from the charge holding region by the second transfer gate is held to be read out as a signal,
• a charge discharging gate which transfers the charge received from the photoelectric transducer, to a charge discharging part, and
• a structure including an overflow path formed in a boundary portion between the photoelectric transducer and the charge holding region, the overflow path being formed at a potential for determining a predetermined charge amount and transferring a charge exceeding the predetermined charge amount as a signal charge from the photoelectric transducer to the charge holding region,
• wherein as a channel electric-potential of the charge discharging gate, an electric-potential lower than an electric-potential of the overflow path is set, or an electric-potential higher than the electric-potential of the overflow path and lower than an electric-potential causing the photoelectric transducer to be completely depleted is set.