System for determining a video offset from dark photosensors in an image sensor array

A photosensitive device, comprising:

• a set of photosensors, each photosensor outputting a voltage signal representative of light intensity thereon;
• a video line, adapted to receive voltage signals from the set of photosensors;
• an averaging circuit in parallel with the video line,
• means for reading, within a cycle of operation, a signal from a photosensor a first time to the averaging circuit, and reading a signal from the photosensor a second time to external circuitry and not reading the signal to the averaging circuit.

A method of controlling a photosensitive device, the photosensitive device comprising:

• a set of active photosensors, each active photosensor outputting a voltage signal representative of light intensity thereon,
• a dark photosensor, the dark photosensor being adapted to receive no light thereon,
• a video line, adapted to receive voltage signals in sequence from the dark photosensor and each active photosensor of the set of photosensors, and
• a correction capacitor associated with the video line, the correction capacitor adapted to retain a correction charge thereon to influence the voltage signals from the active photosensors,
• the method comprising the steps of:
• reading a signal from the dark photosensor a first time, not reading the signal through the correction capacitor;
• and
• reading a signal from the dark photosensor a second time through the correction capacitor.

A method of operating a photosensitive device, the photosensitive device comprising:

• a set of photosensors, each photosensor outputting a voltage signal representative of light intensity thereon,
• a video line, adapted to receive voltage signals from the set of photosensors, and
• an averaging circuit in parallel with the video line;
• the method comprising the steps of
• within a cycle of operation, reading a signal from a photosensor a first time to the averaging circuit, and reading a signal from the photosensor a second time to external circuitry and not reading the signal to the averaging circuit.