| 摘要 |
<p>An image input system which comprises a solid-state pickup device and a preprocessing circuit (3) for subjecting the output signals of the solid-state pickup device to correlation double sampling amplification and outputting video signals. The preprocessing circuit comprises a correlation double sampling amplifier circuit (30) for outputting signal information corresponding to the differential voltage between the black level of the feed-through period of the solid-state pickup device and the signal level during a charge signal output period, and offset canceling means (38) for feeding an input terminal of the correlation double sampling amplifier circuit with an offset canceling voltage for canceling an offset voltage corresponding to the differential voltage in a state where the solid-state pickup device is optically shielded. The correlation double sampling amplifier circuit offsets the offset voltage and the offset canceling voltage as signal components having mutually opposite polarities. Therefore, no circuit after the correlation double sampling amplifier circuit is affected by the offset voltage, and high definition image input is possible even if the capacitive noise characteristic of the solid-state pickup device is poor.</p> |
