Time-delay-and-integrate image sensors having variable integration times

1. An imaging system comprising:

a time-delay-and-integrate (TDI) image sensor comprising (i) a plurality of identical integrating CCDs (ICCDs), arranged in parallel and abutting each other, that accumulate photocharge in response to exposure to light, (ii) electrically coupled to the plurality of ICCDs, a readout CCD (RCCD) for receiving photocharge from the plurality of ICCDs, and (iii) electrically coupled to the RCCD, readout circuitry for converting charge received from the RCCD into voltage;

an optical system for receiving light from a scene to be imaged and projecting it on the plurality of ICCDs; and

wherein each ICCD comprises (i) a plurality of independently controllable stages, (ii) a photosensitive channel for containing photocharge and a channel stop to produce a barrier to separate each ICCD from adjacent ICCDs, (iii) for each of a plurality of charge collection regions, a sense node located between the photosensitive channel and the channel stop for measuring photocharge received thereby from the photosensitive channel, and (iv) for each of the plurality of charge collection regions, a gate for controlling flow of photocharge from the photosensitive channel to the sense node, and

the imaging system comprises, for each charge collection region, a spillover charge measurement circuit to alternatively reset the sense node and measure a charge in the sense node of an associated charge collection region.

2. The imaging system of claim 1 , further comprising a plurality of clock lines (i) disposed substantially perpendicular to the ICCDs and (ii) each controlling a particular stage common to all of the ICCDs.

3. The imaging system of claim 1 , further comprising a control system configured to (i) measure spillover charge received by the sense node from the channel and (ii) reset the sense node by applying a bias thereto to remove the spillover charge therefrom.

4. The imaging system of claim 3 , further comprising a control system configured to measure photocharge received by the sense node from the channel.

5. The imaging system of claim 4 , wherein the control system is configured to reset a selected stage based at least in part on a previously captured image.

6. An imaging device comprising:

a time-delay-and-integrate (TDI) image sensor comprising a plurality of integrating CCDs (ICCDs) arranged in parallel in a first direction, each of the plurality of ICCDs moving charge from a plurality of charge collection regions to corresponding adjacent charge collection regions in a second direction using a plurality of phase clock signals, comprising a plurality of phase clock signal conductors extending across the plurality of ICCDs in the first direction; and

a readout CCD (RCCD) for receiving photocharge from the plurality of ICCDs,

wherein each of the plurality of ICCDs further comprises, for each of the plurality of charge collection regions:

a channel region;

a sense node located between the charge collection region and a channel stop for measuring photocharge received thereby from the channel region;

a gate for controlling flow of photocharge from the channel region to the sense node; and

a spillover charge measurement circuit to alternatively reset the sense node and measure a charge in the sense node.

7. The imaging device of claim 6 , wherein the sense node comprises a floating diffusion.

8. The imaging device of claim 6 , wherein each of the plurality of ICCDs further comprises, under a corresponding phase clock signal conductor:

a first barrier region at a first side of the channel region; and

a second barrier region at a second side of the sense node.

9. The imaging device of claim 8 , wherein the second barrier region of a first one of the plurality of ICCDs forms the first barrier region of a second one of the plurality of ICCDs.

10. The imaging device of claim 6 , further comprising:

a readout CCD (RCCD) coupled to outputs of the plurality of ICCDs; and

a charge measurement and amplifier circuit coupled to the output of the RCCD.

11. The imaging device of claim 6 , further comprising:

an optical system for receiving light from a scene to be imaged and projecting it on the plurality of ICCDs.

12. A method of image capture utilizing a time-delay-integrate (TDI) image sensor comprising a plurality of integrating CCDs (ICCDs) arranged in parallel in a first direction, each of the plurality of ICCDs moving charge from a plurality of charge collection regions to corresponding adjacent charge collection regions in a second direction using a plurality of phase clock signals, the method comprising:

routing a plurality of phase clock signal conductors corresponding to the plurality of phase clock signals across the plurality of ICCDs in the first direction used in the TDI image sensor, thereby forming rows of charge collection regions;

reading out charge from the plurality of ICCDs using a readout CCD (RCCD); and

for each of the plurality of charge collection regions in the plurality of ICCDs:

resetting a sense node;

collecting charge in a charge collection region of a first row of a first ICCD;

transferring spillover charge from the charge collection region to the sense node; and

converting the spillover charge in the sense node to a voltage.