Patent ID: 7271432

Claim:
An image-sensing apparatus comprising: a plurality of pixels, the pixels each including a photoelectric conversion portion that outputs an electric signal produced in accordance with amount of incident light and converted natural-logarithmically and a lead-out path by way of which the electric signal output from the photoelectric conversion portion is fed to an output signal line, the photoelectric conversion portion comprising: a photosensitive element having a first electrode and a second electrode to which a direct-current voltage is applied; a first switch having one contact connected to the first electrode of the photosensitive element; a first transistor having a first electrode, a second electrode connected to another contact of the first switch, and a control electrode; and a second transistor having a first electrode to which a direct-current voltage is applied, a second electrode from which an electric signal is output, and a control electrode connected to the second electrode of the first transistor; and a controller that makes the individual pixels perform image sensing by turning on the first switch so that the first transistor operates in a subthreshold region and that detects variations in sensitivity of the individual pixels by turning off the first switch and varying a voltage fed to the first electrode of the first transistor.