Patent ID: 7636119

Claim:
A method for summing charge packets generated in an image sensor that includes a plurality of vertical charge-coupled devices, a first horizontal charge-coupled device, and a second horizontal charge-coupled device electrically connected to the first horizontal charge-coupled device, the method comprising the steps of: transferring a line of charge packets from the plurality of vertical charge-coupled devices to the first horizontal charge-coupled device, wherein the charge packets represent two different colors; transferring the charge packets representing only one color from the first horizontal charge-coupled device to the second horizontal charge-coupled device; summing together charge packets in the first and second horizontal charge-coupled devices by horizontally shifting a portion of the charge packets in the first and second horizontal charge-coupled devices, wherein charge packets of the same color are summed together in the first horizontal charge-coupled device and in the second horizontal charge-coupled device; horizontally shifting the summed charge packets in one horizontal charge-coupled device and then transferring the summed charge packets from the first horizontal charge-coupled device to the second horizontal charge-coupled device so that the entire line of charge packets is included in the second horizontal charge-coupled device; transferring another line of charge packets from the plurality of vertical charge-coupled devices to the first horizontal charge-coupled device, wherein the charge packets represent two different colors; and summing together charge packets in the first horizontal charge-coupled device by horizontally shifting a portion of the charge packets in the first horizontal charge-coupled device, wherein charge packets representing the two different colors are summed together.