High dynamic range pixel using light separation

Abstract

An image sensor may include pixels having nested sub-pixels. A pixel with nested sub-pixels may include an inner sub-pixel that has either an elliptical or a rectangular light collecting area. The inner sub-pixel may be formed in a substrate and may be immediately surrounded by a sub-pixel group that includes one or more sub-pixels. The inner sub-pixel may have a light collecting area at a surface that is less sensitive than the light collecting area of the one or more outer sub-pixel groups. Microlenses may be formed over the nested sub-pixels, to direct light away from the inner sub-pixel group to the outer sub-pixel groups in nested sub-pixels. A color filter of a single color may be formed over the nested sub-pixels. Hybrid color filters having a single color filter region over the inner sub-pixel and a portion of the one or more outer sub-pixel groups may also be used.

What is claimed is: 
     
         1 . An image sensor, comprising:
 an inner photosensitive area;   an outer photosensitive area group that immediately surrounds the inner photosensitive area; and   a color filter of a single color that overlaps the inner photosensitive area and the entire outer photosensitive area group.   
     
     
         2 . The image sensor defined in  claim 1 , wherein the outer photosensitive area group has a higher sensitivity to light than the inner photosensitive area. 
     
     
         3 . The image sensor defined in  claim 1 , further comprising:
 at least one microlens that overlaps the outer photosensitive area group.   
     
     
         4 . The image sensor defined in  claim 3 , wherein the at least one microlens comprises a toroidal microlens that overlaps the outer photosensitive area group. 
     
     
         5 . The image sensor defined in  claim 4 , wherein the toroidal microlens has a hole that overlaps the inner photosensitive area. 
     
     
         6 . The image sensor defined in  claim 1 , wherein the outer photosensitive area group comprises a first outer photosensitive area on a first side of the inner photosensitive area and a second outer photosensitive area on a second side of the inner photosensitive area. 
     
     
         7 . The image sensor defined in  claim 1 , wherein the inner photosensitive area has a first light sensitivity, wherein the outer photosensitive area group has a second light sensitivity, and wherein the second light sensitivity is at least four times greater than the first light sensitivity. 
     
     
         8 . The image sensor defined in  claim 1 , wherein the outer photosensitive area group has a first geometric center and wherein the inner photosensitive area has a second geometric center that is the same as the first geometric center. 
     
     
         9 . An image sensor, comprising:
 an inner photosensitive area group that includes at least a first photosensitive area;   an outer photosensitive area group that surrounds the inner photosensitive area group, wherein the outer photosensitive area group includes at least a second photosensitive area; and   a toroidal microlens that overlaps the outer photosensitive area group.   
     
     
         10 . The image sensor defined in  claim 9 , wherein the toroidal microlens has a hole that overlaps the inner photosensitive area group. 
     
     
         11 . The image sensor defined in  claim 9 , further comprising:
 a color filter formed over the inner photosensitive area group and the outer photosensitive area group, wherein the color filter comprises:
 a first filtering region formed over the inner photosensitive area group; and 
 a second filtering region formed over the outer photosensitive area group, wherein the first and second filtering regions transmit different respective light spectrums. 
   
     
     
         12 . The image sensor defined in  claim 9 , further comprising:
 a color filter of a single color that overlaps the entire inner photosensitive area group and the entire outer photosensitive area group.   
     
     
         13 . The image sensor defined in  claim 9 , wherein the outer photosensitive area group has a higher sensitivity to light than the inner photosensitive area group. 
     
     
         14 . The image sensor defined in  claim 9 , wherein the inner photosensitive area group has first and second opposing sides, wherein the second photosensitive area is formed on the first side of the inner photosensitive area group, wherein the outer photosensitive area group comprises a third photosensitive area on the second side of the inner photosensitive area group. 
     
     
         15 . An image sensor, comprising:
 an array of imaging pixels, wherein each one of the imaging pixels comprises:
 an inner sub-pixel; and 
 an outer sub-pixel group including a first outer sub-pixel and a second outer sub-pixel, wherein the inner sub-pixel is nested within the outer sub-pixel group. 
   
     
     
         16 . The image sensor defined in  claim 15 , wherein each one of the imaging pixels comprises:
 color filtering material of a single color that overlaps the inner sub-pixel and the outer sub-pixel group.   
     
     
         17 . The image sensor defined in  claim 15 , wherein each one of the imaging pixels comprises:
 color filtering material of a single color that overlaps all of the outer sub-pixel group.   
     
     
         18 . The image sensor defined in  claim 15 , wherein the outer sub-pixel group of each imaging pixel has a first geometric center and wherein the inner sub-pixel of each imaging pixel are has a second geometric center that is the same as the first geometric center. 
     
     
         19 . The image sensor defined in  claim 15 , wherein each one of the imaging pixels comprises:
 a toroidal microlens that overlaps the outer sub-pixel group.   
     
     
         20 . The image sensor defined in  claim 19 , wherein the toroidal microlens of each imaging pixel has a hole that overlaps the inner sub-pixel of that imaging pixel.