<p>An image sensor has an array of operative bipolar transistors (7) for effecting photo-electric conversion of incident light. An array of dummy bipolar transistors (11) optically shielded from the incident light are disposed adjacent and corresponding to the operative bipolar transistors (7) to constitute pairs of operative and dummy bipolar transistors. Pairs of re-set switches (8, 12) are connected to the corresponding pairs of transistors (7, 11) at their base regions to re-set concurrently each pair of the operative and dummy bipolar transistors. <IMAGE></p>
