System and method for draining residual charge from charge-coupled device (CCD) shift registers in image sensors having reset drains
AssigneeTruesense Imaging, Inc.
InventorEric J. Meisenzahl
Life of this patent
Estimating the term…
Abstract
One or more charge storage regions in a charge-coupled device (CCD) shift register can contain residual charge that did not transfer to a reset drain during a reset operation. An image sensor drains the residual charge from each charge storage region by shifting the residual charge to an adjacent charge storage region and resetting the CCD shift register one more time. The process of resetting the CCD shift register, shifting the residual non-image charge to an adjacent charge storage region, and resetting the CCD shift register again can be repeated any number of times.
Claims15
An image sensor, comprising:
- a charge-coupled device (CCD) shift register having a plurality of charge storage regions;
- a reset drain;
- a transfer mechanism positioned between the CCD shift register and the reset drain to transfer charge from each charge storage region to the reset drain;
- and
- a timing generator for enabling a first reset of the plurality of charge storage regions such that non-image charges in the plurality of charge storage regions are transferred to the reset drain, and after the first reset is performed, for generating clock signals to shift any residual non-image charge remaining in at least one charge storage region to a respective adjacent charge storage region and then enabling a second reset to transfer the residual non-image charge to the reset drain.
In an image sensor, a method for draining residual non-image charge from a charge-coupled device (CCD) shift register to a reset drain, wherein the CCD shift register includes a plurality of charge storage regions, the method comprising:
- (a) transferring non-image charge from the CCD shift register to the reset drain;
- (b) after transferring the non-image charge to the reset drain, shifting any residual non-image charge remaining in at least one of the charge-storage regions in the CCD shift register to a respective adjacent charge-storage region;
- and
- (c) after shifting the residual non-image charge, transferring the residual non-image charge in the adjacent charge-storage region to the reset drain.
In an image sensor, a method for draining residual non-image charge from a charge-coupled device (CCD) shift register to a reset drain, where the CCD shift register includes a plurality of charge storage regions, the method comprising:
- (a) enabling a transfer mechanism;
- (b) transferring non-image charge from the CCD shift register to the reset drain;
- (c) after transferring the non-image charge to the reset drain, shifting any residual non-image charge remaining in at least one charge storage region in the CCD shift register to a respective adjacent charge storage region;
- and
- (d) after shifting the residual non-image charge, transferring the residual non-image charge in the adjacent charge storage region to the reset drain.
Dependencies are inferred from the claim text.