Image signal sensing process including altering charges of capacitances

Abstract

In a method for detecting an image signal by means of an array (,) of photosensitive devices (,) with each of which the charge of a capacitance (,) can be altered, an optical signal (,) of each photosensitive device is first detected by means of the following substeps: creating a charge condition of the capacitance with a predetermined voltage (+U_DD), changing the charge of the capacitance (,) either with a photocurrent generated in the photosensitive device (,) by the optical signal (,) or with a quantity derived from the same and detecting the voltage across the capacitance (,) after a predetermined time period, deciding whether the detected voltage lies within a valid range and, if this is so, determining on the basis of the detected voltage a valid signal which characterizes the detected optical signal, and, if this is not so, repeating the cited steps with a time period which differs from the predetermined time period either a predetermined number of times or until it is determined that the detected voltage lies in a valid range. Subsequently the optical signal detected for each photosensitive device (,) is stored together with the time period for which a valid signal has been detected. Finally the image signal is obtained from the stored optical signals for the individual photosensitive devices and the respective assigned time periods.