Patent ID: 6881944

Claim:
A solid state image sensor comprising: an imaging circuit having a plurality of unit cells arranged in an array, each unit cell including a photo-detection section which photoelectrically converts incident light and outputs a signal charge corresponding to the incident light, and a first reference potential generating section which generates a first reference potential; a selection circuit which selects the unit cell; a signal line which is supplied with a signal potential corresponding to the signal charge from the unit cell selected by the selection circuit in a read-out operation, and supplied with the first reference potential in a reset operation; and an adjustment circuit which operates in response to an adjustment instruction signal which is asserted in an adjustment operation following the reset operation, and applies a second reference potential to the signal line in accordance with a potential of the signal line, the adjusting circuit including: a detection section which connects a first node and a ground potential node when the potential of the signal line is higher than a predetermined value, and disconnects the first node and the ground potential node when the potential of the signal line is lower than the predetermined value; a voltage substitute section which connects the first node and a second node supplied with a control potential in the reset operation, during a time period when the adjustment instruction signal is asserted, and disconnects the first node and the second node during a time period when the adjustment instruction signal is negated; and a second reference potential generating circuit which operates in response to a potential of the second node, is set in an inoperative state when the potential of the second node is equal to the ground potential, and is set in an operative state and applies the second reference potential to the signal line when the potential of the second node is equal to the control potential.