Image sensor and imaging device

Abstract

In an image sensor, if a pixel for focusing has a structure having a light-shielding layer for performing pupil division, between the micro lens and the photoelectric conversion unit, the pixel may be configured such that the focal position of the micro lens is positioned further on the micro lens side than the light-shielding layer, and the distance from the focal position of the micro lens to the light-shielding layer is greater than 0 and less than nFΔ, where n is the refractive index at the focal position of the micro lens, F is the aperture value of the micro lens, and Δ is the diffraction limit of the micro lens. This enables variation in the pupil intensity distribution of the pixel for focusing due to positional production tolerance of components to be suppressed.

The invention claimed is: 
     
       1. An image sensor in which a plurality of pixels are two-dimensionally arranged, comprising:
 a micro lens provided on a light-receiving side of each of the plurality of pixels; and 
 a plurality of photoelectric conversion units provided in each of the plurality of pixels, and for receiving light collected by the micro lens, 
 wherein the plurality of photoelectric conversion units are disposed such that central points thereof are eccentric relative to a central point of a single light-receiving surface combining light-receiving surfaces of the plurality of photoelectric conversion units, 
 a focal position of the micro lens is positioned further on the micro lens side than the light-receiving surfaces of the plurality of photoelectric conversion units, and 
 a distance from the focal position of the micro lens to the light-receiving surfaces of the plurality of photoelectric conversion units is greater than 0 and less than nFΔ, where n is a refractive index at the focal position of the micro lens, F is an aperture value of the micro lens, and Δ is a diffraction limit of the micro lens. 
 
     
     
       2. An imaging device comprising an image sensor according to  claim 1 . 
     
     
       3. The image sensor according to claim 1, wherein the focal position of the micro lens is determined according to a wavelength region corresponding to spectral sensitivity of the pixel at which the micro lens is located.  
     
     
       4. The image sensor according to claim 1, wherein the focal position of the micro lens is determined according to a wavelength region corresponding to spectral sensitivity of visible light.  
     
     
       5. The image sensor according to claim 1, wherein the plurality of photoelectric conversion units respectively receive light from different pupil areas which are a part of an exit pupil of an image-forming optical system.  
     
     
       6. The image sensor according to claim 5,
 wherein the plurality of pixels are two-dimensionally arranged in a horizontal direction and a vertical direction, and   wherein, in the exit pupil, the different pupil areas are positioned in the horizontal direction and/or the vertical direction.    
     
     
       7. The image sensor according to claim 1,
 wherein the plurality of pixels have a predetermined pixel pitch, and   wherein the diffraction limit Δ of the micro lens is smaller than the predetermined pixel pitch.    
     
     
       8. The image sensor according to claim 1, wherein the distance from the focal position of the micro lens to the light-receiving surfaces of the plurality of photoelectric conversion units is larger than 0.2 nFΔ.  
     
     
       9. The image sensor according to claim 1, wherein each of the plurality of pixels includes at least four photoelectric conversion units.  
     
     
       10. The image sensor according to claim 1,
 wherein the focal position of the micro lens is determined according to a wavelength region corresponding to spectrum sensitivity of the pixel at which the micro lens is located, and   wherein the distance from the focal position of the micro lens to the light-receiving surfaces of the plurality of photoelectric conversion units is less than nFΔ in the wavelength region.    
     
     
       11. The image sensor according to claim 1, wherein the focal position of the micro lens is positioned so that a light collection spot of the micro lens on the light-receiving surfaces is to be less than 1.13 Δ.  
     
     
       12. The image sensor according to claim 1, further comprising a micro lens array includes a plurality of the micro lens,
 wherein focal positions of the plurality of the micro lens included in the micro lens array are offset by a predetermined amount to the micro lens array from the light-receiving surfaces of the plurality of photoelectric conversion units.    
     
     
       13. An image sensor in which a plurality of pixels are two-dimensionally arranged, comprising:
 a plurality of micro lenses respectively provided on a light-receiving side of the plurality of pixels; and   a plurality of photoelectric conversion units provided in each of the plurality of pixels, for receiving light collected by the micro lens,   wherein the plurality of photoelectric conversion units are disposed such that central points thereof are eccentric relative to a central point of a single light-receiving surface combining light-receiving surfaces of the plurality of photoelectric conversion units, and   wherein focal positions of the plurality of micro lenses are offset by a predetermined amount to the micro lens from the light-receiving surfaces of the plurality of photoelectric conversion units.    
     
     
       14. The image sensor according to claim 13, wherein distances between the focal positions of the plurality of micro lenses and the light-receiving surfaces of the plurality of photoelectric conversion units are less than a focal depth of the plurality of micro lenses corresponding to the predetermined region of wavelengths.  
     
     
       15. The image sensor according to claim 14, wherein the distances between the focal positions of the plurality of micro lenses and the light-receiving surfaces of the plurality of photoelectric conversion units are less than a focal depth of the micro lenses in a case where a diffraction limit Δ of the micro lenses in the predetermined wavelength region is a permissible circle of confusion.