Image Sensor Reset Circuit for Foreign Matter Afterimage

The patent applies preliminary action by resetting the photodiode during the standby period before the reading period begins. The reset signal is output continuously from when the power source is turned on until the reading period starts, ensuring that any conductive foreign matters on the light receiving surface have already caused their potential to stabilize at the substrate potential before actual image reading commences. This preliminary resetting action prevents afterimage phenomena without requiring complex additional control mechanisms.

The patent extracts the problem of foreign matter prevention from the structural domain and relocates it to the control signal domain. Instead of sealing the light receiving surface with resin (structural solution), the invention outputs a reset signal during the standby period to electrically reset the photodiode potential, thereby eliminating the need for physical sealing structures while still preventing afterimage effects caused by conductive foreign matters.

The patent applies continuity of useful action by maintaining the reset signal output continuously during the entire standby period from power-on until the reading period begins, rather than executing discrete idle cycles. This continuous resetting action ensures the node C potential is reliably reset to the reset potential Vrst without requiring multiple repetitive cycles, thereby reducing the start-up period while maintaining reset completeness.