Image sensors with color, panchromatic and infrared pixels
View Patent ↗A high sensitivity image sensor with panchromatic and color pixels arranged to enable high sensitivity, efficient binning and minimize aliasing is disclosed. Efficient binning is enabled by composing the color filter array of tiles containing pixels of at most two types, one panchromatic and the other colored, so that like color pixels to be binned are adjacent to each other. Aliasing is minimized by the twin methods of evenly spacing out tiles containing pixels of like color over the image sensor, and optimizing the arrangement of panchromatic and color pixels within each tile if the tile contains both panchromatic and colored pixels. An image sensor with these color filter arrays can be used to realize cameras with high sensitivity and a plurality of resolutions, with the lower resolutions consuming less power, while minimizing alias artifacts in each supported resolution. A variant of this image sensor with both infrared and color pixels is also disclosed.
1. An image sensor for capturing a color image, comprising:
a two-dimensional array having four groups of pixels denoted by P, A, B, C, each with a unique photoresponse to the electromagnetic spectrum; and
said pixels are arranged in tiles of two pixels wide and two pixels high such that each tile contains two pixels of one type arranged along one diagonal and two pixels of a second type arranged along the other diagonal, where one of the pixel types is P and the other is one of either A, B or C, so that not all tiles have pixels of type P along the diagonals oriented in the same direction.
2. The image sensor of claim 1 wherein two pixels of like color in a tile are configured so as to combine by binning the charge from the pixels, or by converting the charge to voltage and summing the voltages of the pixels, or by digitizing the voltages and adding the digital outputs of the pixels.
3. The image sensor of claim 2 wherein the charges from the pixels to be binned are summed by connecting the said pixels' photodiodes to a common floating diffusion, and the resulting voltage at the floating diffusion is measured.
4. The image sensor of claim 2 with the following minimal repeating unit:
A
P
B
P
P
A
P
B
P
C
P
A
C
P
A
P
or its reflection or rotation, or a combination thereof.
5. The image sensor of claim 4 , wherein pixels from the group P have wider spectral photoresponses than pixels from groups A, B, C, and A is green, B is red and C is blue.
6. The image sensor of claim 4 , wherein one group of P, A, B, C pixels has photoresponse predominantly in the infrared spectrum while the other three are red, green and blue.
7. The image sensor of claim 2 with the following minimal repeating unit:
P
A
B
P
A
P
P
B
C
P
P
A
P
C
A
P
or its reflection or rotation, or a combination thereof.
8. The image sensor of claim 7 , wherein pixels from the group P have wider spectral photoresponses than pixels from groups A, B, C, and A is green, B is red and C is blue.
9. The image sensor of claim 7 , wherein one group of P, A, B, C pixels has photoresponse predominantly in the infrared spectrum while the other three are red, green and blue.
10. The image sensor of claim 2 with the following minimal repeating unit:
A
P
B
P
P
A
P
B
C
P
P
A
P
C
A
P
or its reflection or rotation, or a combination thereof.
11. The image sensor of claim 10 , wherein pixels from the group P have wider spectral photoresponses than pixels from groups A, B, C, and A is green, B is red and C is blue.
12. The image sensor of claim 10 , wherein one group of P, A, B, C pixels has photoresponse predominantly in the infrared spectrum while the other three are red, green and blue.
13. An image sensor for capturing a color image, comprising:
a two-dimensional array having four groups of pixels denoted by P, A, B, C, each with a unique photoresponse to the electromagnetic spectrum; and
said pixels are arranged in tiles of k pixels wide and k pixels high, with k>1, such that all k 2 pixels of each tile are of one group P, A, B or C and arranged in the following minimal repeating unit:
T B
T P
T C
T P
T P
T A
T P
T A
T C
T P
T B
T P
T P
T A
T P
T A
where T P is a tile k pixels wide and k pixels high of pixel type P, T A is a tile k pixels wide and k pixels high of pixel type A, T B is a tile k pixels wide and k pixels high of pixel type B, and T C is a tile k pixels wide and k pixels high of pixel type C.
14. The image sensor of claim 13 wherein the k 2 pixels of like color in a tile are configured so as to combine by binning the charge from the pixels, or by converting the charge to voltage and summing the voltages of the pixels, or by digitizing the voltages and adding the digital outputs of the pixels, or any combination thereof.
15. The image sensor of claim 14 wherein the charges from the pixels to be binned are summed by connecting the said pixels' photodiodes to a common floating diffusion, and the resulting voltage at the floating diffusion is measured.
16. The image sensor of claim 13 with a minimal repeating unit formed by reflection, rotation, or a combination thereof, of the minimal repeating unit of claim 13 .
17. The image sensor of claim 16 with k=2 so that its minimal repeating unit is the following:
B
B
P
P
C
C
P
P
B
B
P
P
C
C
P
P
P
P
A
A
P
P
A
A
P
P
A
A
P
P
A
A
C
C
P
P
B
B
P
P
C
C
P
P
B
B
P
P
P
P
A
A
P
P
A
A
P
P
A
A
P
P
A
A
or its reflection or rotation, or a combination thereof.
18. The image sensor of claim 17 , wherein pixels from the group P have wider spectral photoresponses than pixels from groups A, B, C, and A is green, B is red and C is blue.
19. The image sensor of claim 17 , wherein one group of P, A, B, C pixels has photoresponse predominantly in the infrared spectrum while the other three are red, green and blue.
20. The image sensor of claim 16 with k=3 so that its minimal repeating unit is the following:
B
B
B
P
P
P
C
C
C
P
P
P
B
B
B
P
P
P
C
C
C
P
P
P
B
B
B
P
P
P
C
C
C
P
P
P
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
C
C
C
P
P
P
B
B
B
P
P
P
C
C
C
P
P
P
B
B
B
P
P
P
C
C
C
P
P
P
B
B
B
P
P
P
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
P
P
P
A
A
A
or its reflection or rotation, or a combination thereof.
21. The image sensor of claim 20 , wherein pixels from the group P have wider spectral photoresponses than pixels from groups A, B, C, and A is green, B is red and C is blue.
22. The image sensor of claim 20 , wherein one group of P, A, B, C pixels has photoresponse predominantly in the infrared spectrum while the other three are red, green and blue.