Driving an image sensor with reduced area and high image quality
An image sensor includes a set of at least two pixels each sensing light of a same color coupled to a signal converter. A driver simultaneously turns on a respective switching element for transferring a respective photocurrent from a respective photodiode within each of such pixels to the signal converter, for capturing a moving image. Alternatively, the driver separately turns on the respective switching element for sequentially transferring a respective photocurrent from a respective photodiode within each of such pixels to the signal converter, for capturing a still image.
1. An image sensor comprising:
a first set of at least two pixels each sensing light of a same first color;
a signal converter coupled to the first set of pixels; and
a driver for turning on a respective switching element within each pixel of the first set for simultaneously coupling a respective photocurrent from a respective photodiode for each pixel of the first set to the signal converter,
wherein each pixel of the first set has a transfer transistor, and wherein at least two transfer transistors of the first set are electrically connected to a common floating diffusion node.
2. The image sensor of claim 1 , wherein the first set of pixels is within a same column of an array of pixels of the image sensor.
3. The image sensor of claim 2 , wherein the first set is comprised of two pixels that are non-adjoining in the column.
4. The image sensor of claim 3 , wherein another one pixel for sensing a different color is disposed between the two pixels.
5. The image sensor of claim 4 , wherein only the two pixels of the first set for sensing light of the same first color are coupled to the signal converter.
6. The image sensor of claim 4 , further comprising:
a second set of at least two pixels each for sensing a same second color and each coupled to the signal converter, and wherein the driver turns on a respective switching element within each pixel of the second set for simultaneously coupling a respective photocurrent from a respective photodiode for each pixel of the second set to the signal converter.
7. The image sensor of claim 6 , wherein the array of pixels of the image sensor have a Bayer color pattern, and wherein a pixel from the first set and a pixel from the second set alternate along a column of the array.
8. The method of claim 4 , further comprising:
coupling simultaneously a respective photocurrent from a respective photodiode for each pixel of a second set of at least two pixels to the signal converter, for capturing the moving image;
wherein each pixel of the second set is for sensing light of a same second color; and
coupling separately the respective photocurrent from the respective photodiode for each pixel of the second set to the signal converter, for capturing the still image.
9. The method of claim 8 , wherein the array of pixels of the image sensor have a Bayer color pattern, and wherein a pixel from the first set and a pixel from the second set alternate along a column of the array.
10. The image sensor of claim 1 , further comprising:
a second set of at least two pixels each for sensing a same second color and each coupled to the signal converter, and wherein the driver turns on a respective switching element within each pixel of the second set for simultaneously coupling a respective photocurrent from a respective photodiode for each pixel of the second set to the signal converter.
11. The image sensor of claim 1 ,
wherein the driver simultaneously couples the respective photocurrent from the respective photodiode for each pixel of the first set to the signal converter, for capturing a moving image;
and wherein the driver separately couples the respective photocurrent from the respective photodiode for each pixel of the first set to the signal converter, for capturing a still image.
12. The image sensor of claim 1 , wherein the image sensor is a CMOS image sensor, and wherein each pixel of the CMOS image sensor includes only a photodiode and a transfer transistor.
13. A method of driving an image sensor comprising:
coupling simultaneously a respective photocurrent from a respective photodiode for each pixel of a first set of at least two pixels to a signal converter, for capturing a moving image;
wherein each pixel of the first set has a transfer transistor, and wherein at least two transfer transistors of the first set are electrically connected to a common floating diffusion node;
and wherein each pixel of the first set is for sensing light of a same first color; and
coupling separately the respective photocurrent from the respective photodiode for each pixel of the first set to the signal converter, for capturing a still image.
14. The method of claim 13 , wherein the first set of pixels is within a same column of an array of pixels of the image sensor.
15. The method of claim 14 , wherein the first set is comprised of two pixels that are non-adjoining in the column.
16. The method of claim 15 , wherein another one pixel for sensing a different color is disposed between the two pixels.
17. The method of claim 16 , wherein only the two pixels of the first set for sensing light of the same first color are coupled to the signal converter.
18. The method of claim 13 , further comprising:
coupling simultaneously a respective photocurrent from a respective photodiode for each pixel of a second set of at least two pixels to the signal converter, for capturing the moving image;
wherein each pixel of the second set is for sensing light of a same second color; and
coupling separately the respective photocurrent from the respective photodiode for each pixel of the second set to the signal converter, for capturing the still image.
19. The method of claim 18 , wherein the respective photocurrent for each pixel of only one of the first or second sets of pixels is simultaneously coupled to the signal converter, for capturing the moving image.
20. The method of claim 13 , wherein the image sensor is a CMOS image sensor, and wherein each pixel of the CMOS image sensor only includes a photodiode and a transfer transistor.