Patent ID: 6912003
Filing Date: 2005-06-28
Classification: H04N

Abstract:
1. Method of compensating variations induced by temperature, strain and manufacturing technology in CMOS video sensors exposed to radiation and generating electrical output signals as a function of the irradiation energy, which output signals are subject to a logarithmic characteristic, characterised in that at least two reference CMOS sensors are used, which are held at the same temperature level as the CMOS video sensors to be compensated and which are not irradiated, however, to generate two reference signals whereof one corresponds to a reference dark value whilst the other one, in response to the application of an electric current, corresponds to a reference illumination value, that said reference signals so generated are amplified separately of each other such that the amplifying conditions are identical with the amplification of the output signals to be compensated, that said reference signals, which display a temperature response identical with the response of the electric output signals of the CMOS video sensors to be compensated, are supplied to an A/D converter, that at least one correction value is stored in a memory unit for each CMOS video sensor point to be compensated, which correction value is suitable to compensate variations induced by manufacturing technology and which is applied to the respective output signal to be compensated such that output signals corrected by FPN (=fixed pattern noise) will be obtained, and that the FPN-corrected output signals as well as the reference signals so obtained are supplied to said A/D converter where the output signals of the CMOS video sensor are compensated and converted into digital signals.