Method for producing a linear image sensor having multiple outputs
View Patent ↗A Charge-Coupled Device (CCD) image sensor includes a linear array of photodetectors. The photodetectors in the linear array are arranged into distinct sub-arrays with each sub-array including two or more photodetectors. An output channel is connected to each sub-array of photodetectors. Each output channel includes a horizontal CCD shift register and an output structure connected to an end of the horizontal CCD shift register in a linear arrangement with respect to each other. Each successive output channel is disposed on an alternate side of the linear array. Every other output channel is disposed on an alternate side of the linear array. One or more dark reference pixels can be connected to one or more additional shift register elements in the horizontal CCD shift registers.
1. A method for producing multiple outputs for a linear array image sensor, the method comprising:
providing a first plurality of output channels on one side of a linear array of photodetectors, wherein the output channels in the first plurality of output channels are each connected to a distinct sub-array of photodetectors in the linear array of photodetectors;
providing a second plurality of output channels on another side of the linear array of photodetectors, wherein the output channels in the second plurality of output channels are each connected to a distinct sub-array of photodetectors in the linear array of photodetectors, and wherein each successive output channel in the first and second plurality of output channels is disposed on an alternate side of the linear array and each output channel in the first and second plurality of output channels includes a horizontal shift register and an output structure connected to an end of the horizontal shift register in a linear arrangement such that a path of charge transfer through the horizontal shift register and the output structure is substantially linear;
providing one or more additional shift register elements in each horizontal shift register; and
providing a dark reference pixel electrically connected to each additional shift register element, each dark reference pixel being spaced from the linear array of photodetectors.
2. The method as in claim 1 , further comprising providing a transfer mechanism between the horizontal shift registers and respective sub-arrays of photodetectors.
3. The CCD image sensor as in claim 2 , further comprising another transfer mechanism disposed between each shift register element and respective dark reference pixel.
4. The method as in claim 1 , wherein the additional shift register elements are at an end of the horizontal shift register farthest from the output structure.
5. The method as in claim 1 , wherein the additional shift register elements are at an end of the horizontal shift register immediately adjacent to the output structure.
6. The CCD image sensor as in claim 1 , wherein each output structure includes a charge sensing node.
7. The CCD image sensor as in claim 6 , wherein each output structure further includes an output buffer connected to the charge sensing node.
8. The CCD image sensor as in claim 1 , wherein the dark reference pixel and the linear array are disposed on opposite sides of the output channel.
9. The CCD image sensor as in claim 1 , wherein each output channel is disposed between the linear array and the respective dark reference pixel.