Asymmetric angular response pixels for singl sensor stereo

Abstract

Depth sensing imaging pixels include pairs of left and right pixels forming an asymmetrical angular response to incident light. A single microlens is positioned above each pair of left and right pixels. Each microlens spans across each of the pairs of pixels in a horizontal direction. Each microlens has a length that is substantially twice the length of either the left or right pixel in the horizontal direction; and each microlens has a width that is substantially the same as a width of either the left or right pixel in a vertical direction. The horizontal and vertical directions are horizontal and vertical directions of a planar image array. A light pipe in each pixel is used to improve light concentration and reduce cross talk.

What is claimed: 
     
         1 . An image sensor comprising:
 a pixel pair that includes a first pixel and a second pixel, wherein the first pixel and the second pixel have asymmetrical angular responses to incident light and wherein the first and second pixels are covered by color filter element material of a single color;   a microlens that spans the pixel pair, wherein the color filter element material is interposed between the microlens and the first and second pixels; and   image processing circuitry configured to:
 obtain an image depth signal by using subtraction to determine a difference between an output signal from the first pixel of the pixel pair and an output signal from the second pixel of the pixel pair; and 
 determine a distance to an imaged object based on the image depth signal. 
   
     
     
         2 . The image sensor defined in  claim 1 , further comprising:
 additional pixels having symmetrical angular responses to the incident light.   
     
     
         3 . The image sensor defined in  claim 1 , wherein the first and second pixels are positioned in the same row of pixels. 
     
     
         4 . The image sensor defined in  claim 1 , wherein the microlens has a width and a length that is longer than the width. 
     
     
         5 . The image sensor defined in  claim 1 , wherein the microlens has a width and a length that is substantially twice as long as the width. 
     
     
         6 . The image sensor defined in  claim 1 , wherein the microlens covers only the first and second pixels. 
     
     
         7 . The image sensor defined in  claim 1 , further comprising:
 a first light pipe formed over the first pixel; and   a second light pipe formed over the second pixel.   
     
     
         8 . An image sensor comprising:
 first and second adjacent photosensitive areas having asymmetrical angular responses to incident light, wherein the first and second photosensitive areas are covered by color filter element material of a single color;   a microlens that covers the first and second photosensitive areas, wherein the microlens has a width and a length that is longer than the width; and   image processing circuitry configured to obtain an image depth signal by using subtraction to determine a difference between an output signal from the first photosensitive area and an output signal from the second photosensitive area.   
     
     
         9 . The image sensor defined in  claim 8 , further comprising:
 additional photosensitive areas having symmetrical angular responses to the incident light.   
     
     
         10 . The image sensor defined in  claim 8 , wherein the first and second photosensitive areas are positioned in the same row of photosensitive areas. 
     
     
         11 . The image sensor defined in  claim 8 , wherein the length is substantially twice as long as the width. 
     
     
         12 . The image sensor defined in  claim 8 , wherein the microlens covers only the first and second photosensitive areas. 
     
     
         13 . The image sensor defined in  claim 8 , wherein the image processing circuitry is further configured to:
 determine a distance to an imaged object based on the image depth signal.   
     
     
         14 . The image sensor defined in  claim 8 , further comprising:
 a first light pipe formed over the first photosensitive area; and   a second light pipe formed over the second photosensitive area.   
     
     
         15 . An image sensor comprising:
 a pixel pair that includes a first pixel and a second pixel, wherein the first pixel and the second pixel have asymmetrical angular responses to incident light;   at least one color filter element of a single color, wherein the at least one color filter element covers both the first and second pixels in the pixel pair;   a microlens that spans the pixel pair, wherein the microlens is formed over the at least one color filter element; and   image processing circuitry configured to:
 obtain an image depth signal by using subtraction to determine a difference between an output signal from the first pixel of the pixel pair and an output signal from the second pixel of the pixel pair; and 
 determine a distance to an imaged object based on the image depth signal. 
   
     
     
         16 . The image sensor defined in  claim 15 , further comprising:
 additional pixels having symmetrical angular responses to the incident light.   
     
     
         17 . The image sensor defined in  claim 15 , wherein the first and second pixels are positioned in the same row of pixels. 
     
     
         18 . The image sensor defined in  claim 15 , wherein the microlens has a width and a length that is longer than the width. 
     
     
         19 . The image sensor defined in  claim 15 , wherein the microlens has a width and a length that is substantially twice as long as the width. 
     
     
         20 . The image sensor defined in  claim 15 , wherein the microlens covers only the first and second pixels.