Device and method for extending dynamic range in an image sensor

Abstract

An image sensor comprises a pixel array having a plurality of pixel regions, wherein the pixel array is adapted to generate at least one signal from each pixel region and a separate signal from a subset of pixels within each pixel region, both during a single exposure period. In one embodiment, the sensor is in communication with a shift register which accumulates the separate signal and transfers the separate signal to an amplifier. The shift register further accumulates the at least one signal from the pixel region after the separate signal has been transferred to the amplifier and transfers the at least one signal to the amplifier.

The invention claimed is: 
     
       1. An image sensor, comprising:
 a pixel array comprising a plurality of pixel regions, wherein the pixel array is adapted to generate at least one signal from each pixel region and a at least one separate signal from a subset one or more subsets of pixels within each pixel region, both during one or more exposure periods; 
 at least one first shift register in communication with the pixel array for receiving charges generated by the pixel regions; 
 at least one second shift register in communication with the first shift register, wherein the at least one second shift register is adapted to separately transfer a at least one first signal generated by the subset one or more subsets of pixels and a second signal generated by remaining pixels of the pixel array; and 
 at least one amplifier for collecting the charges from the at least one second shift register, wherein the at least one amplifier is adapted to collect the at least one first signal to define a low one or more lower sensitivity image images and the second signal to define a high sensitivity image, and to generate an output comprising the combined first signals and second signals from each of the plurality of pixel regions for one or more exposure periods. 
 
     
     
       2. The image sensor of  claim 1 , further comprising a plurality of shift registers, wherein the at least one separate signal is accumulated in a first shift register and transferred to a first output amplifier and the at least one signal is accumulated in at least one second shift register and transferred to a second output amplifier. 
     
     
       3. The image sensor of  claim 1 , wherein each pixel region comprises a (n×n) (n×m) pixel area, wherein n is any integer and m are integers and each pixel generates a charge. 
     
     
       4. The image sensor of  claim 1 , wherein the subset of pixels comprises one pixel. 
     
     
       5. The image sensor of  claim 1 , wherein each pixel region comprises a plurality of unit cells, each unit cell having a size and including one subset of pixels, and further comprising an anti-aliasing filter for each unit cell, the filter adapted for generating blur having a width corresponding to the size of the unit cell. 
     
     
       6. The image sensor of  claim 1 , wherein the one or more exposure periods comprises a single exposure. 
     
     
       7. The image sensor of  claim 1 , wherein the one or more exposure periods comprises multiple exposures, wherein each exposure has a different exposure period and different binning. 
     
     
       8. The image sensor of  claim 7 , wherein a first exposure period is used for bright objects and a one or more second exposure period is periods are used for faint objects. 
     
     
       9. The image sensor of  claim 1 , wherein the pixel array is a charge-coupled device. 
     
     
       10. The image sensor of  claim 1 , wherein the number of pixels in the subset of pixels is selectable by separately accessing signals from each pixel. 
     
     
       11. An image sensor, comprising:
 a plurality of super-pixels, each a super-pixel comprising an array of pixels, each pixel adapted to generate a charge upon exposure to light, wherein the super-pixel has defined therein a subset one or more subsets of pixels comprising one or more pixels; 
 at least one first shift register in communication with the super-pixel for receiving charges generated by the pixels; 
 at least one second shift register in communication with the first shift register, wherein the at least one second shift register is adapted to separately transfer a at least one first signal generated by the subset one or more subsets of pixels and a second signal generated by remaining pixels of the super-pixel; and 
 at least one amplifier for collecting the charges from the at least one second shift register, wherein the at least one amplifier is adapted to collect the at least one first signal to define a low one or more lower sensitivity image images and the second signal to define a high sensitivity image, and to generate an output comprising the combined first signals and second signals from each of the plurality of super-pixels for one or more exposure periods. 
 
     
     
       12. The image sensor of  claim 11 , wherein the at least one first shift register is a horizontal shift register and the at least one second shift register is a vertical shift register, wherein the at least one first signal is defined by executing a first shift from the horizontal shift register to the vertical shift register. 
     
     
       13. The image sensor of  claim 11 , wherein the at least one first shift register is a plurality of horizontal shift registers and the at least one second shift register comprises a plurality of vertical shift registers and a single horizontal shift register, wherein the at least one first signal is defined by selecting a first selected horizontal shift register of the plurality of horizontal shift registers and a first vertical shift register of the plurality of vertical shift registers. 
     
     
       14. The image sensor of  claim 11 , wherein the at least one first shift register comprises a first horizontal shift register adapted for accumulating charges from the subset one or more subsets of pixels and transferring the charges to a first amplifier and a second horizontal shift register for accumulating charges from the remaining pixels of the super-pixel and transferred transferring the charges to a second amplifier, wherein first and second two or more output images having different spatial resolutions are generated. 
     
     
       15. The image sensor of  claim 11 , wherein each super-pixel comprises a plurality of unit cells, each unit cell having a size and including one subset of pixels, and further comprising an anti-aliasing filter for each unit cell, the filter adapted for generating blur having a width corresponding to the size of the unit cell. 
     
     
       16. The image sensor of  claim 11 , wherein each super-pixel comprises a 4×4 (n×m) pixel area, wherein n and m are integers. 
     
     
       17. The image sensor of  claim 11 , wherein the subset one or more subsets of pixels comprises one pixel. 
     
     
       18. The image sensor of  claim 11 , wherein the one or more exposure periods comprises a single exposure. 
     
     
       19. The image sensor of  claim 11 , wherein the one or more exposure periods comprises multiple exposures, wherein each exposure has a different exposure period and different binning. 
     
     
       20. The image sensor of  claim 19 , wherein a one or more first exposure period is periods are used for bright objects and a one or more second exposure period is periods are used for faint objects. 
     
     
       21. The image sensor of  claim 11 , wherein the number of pixels in the subset one or more subsets of pixels is selectable by separately accessing signals from each pixel. 
     
     
       22. A method for extending a dynamic range of an image sensor comprising:
 defining a plurality of pixel regions within the image sensor; 
 defining a subset one or more subsets of pixels within each pixel region comprising a plurality of pixels having like sensitivities, wherein each pixel generates a charge in response to exposure to light and the pixel region generates a set of charges; 
 first binning the set of charges to collect one or more subsets of charges generated by the subset one or more subsets of pixels to generate a at least one first image signal; 
 second binning the set of charges generated by the pixel region to generate a second image signal; 
 separately transferring each of the at least one first signal and the second signal to at least one amplifier to define a low one or more lower sensitivity image images and a high sensitivity image; 
 repeating the steps of first binning, second binning and separately transferring for all pixel regions within the image sensor; and 
 combining the low one or more lower sensitivity images and the high sensitivity images from all pixel regions for one or more exposure periods to generate an output image. 
 
     
     
       23. The method of  claim 22 , wherein the at least one first images are signal is accumulated in a first amplifier and the second images signals are accumulated in a second amplifier to generate separate images having different spatial resolution resolutions. 
     
     
       24. The method of  claim 22 , wherein the number of pixels in the subset one or more subsets of pixels is selectable by separately accessing signals from each pixel. 
     
     
       25. The method of claim 22, wherein the one or more subsets of pixels comprises any one or a combination of pixels within the pixel region. 
     
     
       26. The method of claim 22, wherein the one or more subsets of pixels comprises a plurality of subsets, and wherein the step of first binning is repeated for each subset to generate a first signal corresponding to each subset. 
     
     
       27. The method of claim 26, wherein each subset of pixels is associated with a different sensitivity. 
     
     
       28. The method of claim 26, wherein each subset of pixels is associated with a different color channel. 
     
     
       29. The method of claim 22, wherein the at least one first signal and the second signal are generated in a single exposure period. 
     
     
       30. The method of claim 22, wherein the at least one first signal and the second signal are generated in multiple exposure periods. 
     
     
       31. The method of claim 22, wherein the image sensor comprises a charge-coupled device. 
     
     
       32. The method of claim 22, further comprising applying spatially adaptive clocks to different pixel regions, wherein different readout schemes are defined for different portions of a field of view of the image sensor. 
     
     
       33. The method of claim 22, further comprising, prior to the steps of first binning and second binning, separating color channels and separately binning the separated color channels. 
     
     
       34. The method of claim 22, wherein the steps of first binning and second binning comprise determining an optimal binning combination for each portion of a field of view of the image sensor. 
     
     
       35. A method for extending a dynamic range of an image sensor comprising an array of pixels, the method comprising:
 defining a plurality of first pixel regions within the array of pixels, each first pixel region corresponding to a first spatial resolution wherein the pixels in the array have like sensitivities;   defining one or more second pixel regions, each comprising a subset of the first pixel region, the one or more second pixel regions corresponding to at least one second spatial resolution higher than the first spatial resolution;   accumulating charges over at least one exposure period from the first pixel region;   binning the accumulated charges associated with the first pixel region to generate a lower spatial resolution image signal and at least one higher spatial resolution image signal associated with the one or more second pixel regions;   separately transferring the lower spatial resolution image and the at least one higher spatial resolution image to an amplifier; and   combining within the amplifier the lower spatial resolution image signal and the at least one higher spatial resolution image signal to generate an output image.   
     
     
       36. The method of claim 35, wherein the at least one exposure period comprises a single exposure period. 
     
     
       37. The method of claim 35, wherein the at least one exposure period comprises multiple exposure periods. 
     
     
       38. The image sensor of claim 35, wherein one or more first exposure periods are used for bright objects and one or more second exposure periods are used for faint objects. 
     
     
       39. The method of claim 35, further comprising repeating the step of accumulating charges for all pixel regions within the array before the combining step. 
     
     
       40. The method of claim 35, wherein the one or more second pixel regions comprises any one or a combination of pixels within the first pixel region. 
     
     
       41. The method of claim 35, wherein the one or more second pixel regions comprises a plurality of second pixel regions, and wherein the step of binning generates an image signal corresponding to each second pixel region. 
     
     
       42. The method of claim 41, wherein each second pixel region is associated with a different sensitivity. 
     
     
       43. The method of claim 41, wherein each second pixel region is associated with a different color channel. 
     
     
       44. The method of claim 35, further comprising, prior to the step of accumulating, separating color channels and separately binning the separated color channels. 
     
     
       45. The method of claim 35, wherein the step of accumulating comprises determining an optimal binning combination for each portion of a field of view of the image sensor. 
     
     
       46. The method of claim 35, further comprising applying spatially adaptive clocks to different pixel regions, wherein different readout schemes are defined for different portions of a field of view of the image sensor.