On-chip dead pixel correction in a CMOS imaging sensor

A method for correcting for dead pixels in a CMOS imaging array, said imaging array including a plurality of pixels arranged in a matrix of rows and columns, said CMOS imaging array formed using a CMOS manufacturing process and formed on a single integrated circuit, said method comprising the steps of:

• precharging said plurality of pixels to a fixed voltage;
• sequentially examining the signals from each pixel in the imaging array to determine if each pixel is a dead pixel;
• storing a location number of each dead pixel in a memory formed using said CMOS manufacturing process and formed on said single integrated circuit;
• after all of the dead pixels have been determined and their location numbers stored, proceeding with normal image processing of the imaging array, during which as the signal from each pixel is read out, using a location comparator circuit to compare the location number of each pixel with the stored location numbers for dead pixels, and the signal from any pixel with a location number that corresponds to the stored location number of a dead pixel is compensated for, said location comparator circuit formed using said CMOS manufacturing process and formed on said single integrated circuit.

A method for correcting for dead pixels in a CMOS imaging array, said imaging array including a plurality of pixels arranged in a matrix of rows and columns, said CMOS imaging array formed using a CMOS manufacturing process and formed on a single integrated circuit, said method comprising the steps of:

• (a) reading out a pixel signal from a pixel in the pixel array;
• (b) determining if the pixel signal from the pixel indicates that the pixel is a dead pixel;
• (c) storing a location number of a dead pixel in a memory formed using said CMOS manufacturing process and formed on said single integrated circuit;
• (d) repeating steps (a) to (c) for each pixel in the pixel array until all of the pixels have been read out;
• and
• (e) thereafter using a location comparator circuit to compare the location number of each pixel that is being read out with the stored location numbers of dead pixels and compensating for the signal from a pixel whose location number corresponds to the stored location number of a dead pixel, and said location comparator circuit formed using said CMOS manufacturing process and formed on said single integrated circuit.

A method for correcting for dead pixels in a CMOS imaging array, said imaging array including a plurality of pixels arranged in a matrix of rows and columns, said CMOS imaging array formed using a CMOS manufacturing process and formed on a single integrated circuit, said method comprising the steps of:

• (a) generating a location number for a pixel in the pixel array and reading out the signal from the pixel;
• (b) determining if the signal from the pixel indicates that the pixel is a dead pixel;
• (c) if the signal from the pixel indicates that the pixel is a dead pixel, storing the location number of the dead pixel in a storage area formed using said CMOS manufacturing process and formed on said single integrated circuit;
• (d) repeating steps (a) to (c) until all of the pixels have been read out;
• (e) after all of the pixels have initially been read out and the dead pixel location numbers have been stored, reading out a signal from a pixel in the pixel array;
• (f) using a location comparator circuit to compare the location number of the pixel that is currently being read with the stored location numbers of the dead pixels, said location comparator circuit formed using said CMOS manufacturing process and formed on said single integrated circuit;
• (g) compensating for a pixel whose location number corresponds to a stored location number of a dead pixel;
• and
• (h) repeating steps (e) to (g) for all of the pixels in the pixel array to produce each frame of the image signal.

A CMOS image sensor formed using said CMOS manufacturing process and formed on said single integrated circuit comprising:

• a pixel array formed from a plurality of pixels arranged in a matrix of rows and columns and formed using said CMOS manufacturing process and formed on said single integrated circuit;
• signal processing circuitry for reading out signals from the pixel array and outputting processed pixel signals and formed using said CMOS manufacturing process and formed on said single integrated circuit;
• a location shift register for incrementing location numbers for pixels in the pixel array and formed using said CMOS manufacturing process and formed on said single integrated circuit;
• and
• dead pixel comparator circuitry for receiving the processed pixel signals from the signal processing circuitry and examining the processed pixel signals to see if they are indicative of dead pixels, and for indicating when the location number of a pixel that is determined to be a dead pixel should be stored and formed using said CMOS manufacturing process and formed on said single integrated circuit.