Patent ID: 9024243
Filing Date: 2015-05-05
Classification: H04N

Abstract:
1. An image sensor comprising a plurality of pixels and comprising, for each pixel: means for converting electromagnetic energy detected by the pixel into an electric current proportional to the energy; a first integrating capacitor and means to cause a charge of the first capacitor to a first electric level and a discharge of the first capacitor to a second electric level, one of the discharge and the charge being controlled by the proportional electric current, the other one of the charge or the discharge being controlled by an electric current flowing through a reset switch; loopback means allowing automatic repetition of charging and discharging of the first capacitor during charging and discharging cycles, the loopback means including a comparator having an input connected to the first capacitor, with the comparator output being connected to the reset switch; counting means configured to count a number of cycles occurring during a given integration time in the first capacitor; means for measuring a residual electric charge present in the first capacitor after a time of integration; processing means configured to provide a digital value representative of electromagnetic energy detected as a function of the number of cycles and the residual electric charge; calibrations means configured to, in a calibration phase: storage means configured to store, during the calibration phase, values specific to each pixel corresponding to the first and second electric levels and/or correction values calculated from the specific values, and configured to use, during a functional phase, the stored values specific to each pixel to correct the digital value representative of the detected electromagnetic energy.