Capsule endoscope

Abstract

A capsule endoscope is disclosed that includes means for illuminating an object, means for imaging the object, and a transparent cover having a center of curvature. The transparent cover covers the illumination means and the imaging means, and the imaging means includes an objective optical system and an image detecting element. The illumination means is positioned relative to the image detecting element, as viewed axially from the object side of the capsule endoscope, so that an area that is symmetrically positioned about the optical axis of the objective optical system from a light emitting area of the illumination means overlaps an area of the image detecting element, but does not overlap any areas of the image detecting element that are used for image detection.

1. A capsule endoscope, comprising:
 illumination means that includes a light emitting element for illuminating an object;  
 imaging means for imaging the object; and  
 a transparent cover having a center of curvature, said transparent cover covering the illumination means and the imaging means;  
 
       wherein
 the imaging means includes an objective optical system and an image detecting element;  
 an entrance pupil position of the objective optical system is arranged so that its center is located substantially at the center of curvature of the transparent cover; and  
 the illumination means is positioned relative to the image detecting element, when viewing the capsule endoscope from the object side, so that an area that is symmetrically positioned about the optical axis of the objective optical system from a light emitting area of the illumination means overlaps an area of the image detecting element but does not overlap any area of the image detecting element that is used for picture image detection.  
 
     
     
       2. The capsule endoscope according to  claim 1 , wherein an area of the image detecting element that is not used for picture imaging and which is symmetrically positioned, when viewing the capsule endoscope from the object side, about the optical axis of the objective optical system from a light emitting area of the illumination means is a mask area that is treated electrically at the time of the picture image processing. 
     
     
       3. The capsule endoscope according to  claim 1 , wherein
 the transparent cover has an inner surface and an outer surface, the center of curvature of the inner surface being located substantially at the entrance pupil position; and  
 the transparent cover has a thickness that, from a maximum opposite the entrance pupil, decreases toward the periphery of the transparent cover.  
 
     
     
       4. A capsule endoscope, comprising:
 illumination means that includes a light emitting element for illuminating an object;  
 imaging means that includes an objective optical system for imaging the object; and  
 a transparent cover having a center of curvature, said transparent cover covering the illumination means and the imaging means;  
 
       wherein
 the illumination means includes an illumination diverging means having an exit pupil, and a light emitting element, and  
 the center of the exit pupil of the illumination diverging means is arranged to substantially coincide with the center of curvature of the transparent cover.  
 
     
     
       5. The capsule endoscope according to  claim 4 , wherein the imaging means comprises a plurality of lens elements that constitute the objective optical system, and an image detecting element. 
     
     
       6. A capsule endoscope, comprising:
 illumination means for illuminating an object;  
 imaging means for imaging the object; and  
 a transparent cover having a center of curvature, said transparent cover covering the illumination means and the imaging means;  
 
       wherein
 the imaging means includes a plurality of objective optical systems and an image detecting element;  
 the illumination means include illumination diverging means having exit pupils and light emitting elements;  
 one exit pupil of the illumination diverging means is arranged so as to substantially coincide with the center of curvature of the transparent cover, and the remaining exit pupils of the illumination diverging means are positioned relative to the image detecting element, when viewing the capsule endoscope from the object side, so that areas that are symmetrically positioned about the optical axes of the objective optical systems from the exit pupils of the remaining illumination diverging means overlap areas of the image detecting element but do not overlap any area of the image detecting element that is used for picture image detection.  
 
     
     
       7. The capsule endoscope according to  claim 6 , wherein an area of the image detecting element that is not used for picture imaging and which is symmetrically positioned, when viewing the capsule endoscope from the object side, about the optical axes of the objective optical system from a light emitting area of the illumination means is a mask area that is electrically masked at the time of the picture image processing. 
     
     
       8. A capsule endoscope, comprising:
 illumination means for illuminating an object;  
 imaging means for imaging the object; and  
 a transparent cover having a center of curvature, said transparent cover covering the illumination means and the imaging means;  
 
       wherein
 the imaging means includes a plurality of objective optical systems and a plurality of image detecting elements;  
 the illumination means include illumination diverging means having exit pupils, and light emitting elements;  
 the exit pupil of one illumination diverging means is arranged to substantially coincide with the center of curvature of the transparent cover, and the exit pupils of the remaining illumination diverging means are positioned relative to the image detecting elements, when viewing the capsule endoscope from the object side, so that areas that are symmetrically positioned about the optical axes of the objective optical systems from the exit pupils of the remaining illumination diverging means overlap areas of the image detecting elements but do not overlap any area of the image detecting elements that is used for picture image detection.  
 
     
     
       9. A capsule endoscope, comprising:
 illumination means that includes a light emitting element for illuminating an object;  
 imaging means for imaging the object; and  
 a transparent cover which covers the illumination means and the imaging means;  
 
       wherein
 the imaging means includes an objective optical system and an image detecting element,  
 the illumination means is positioned relative to the image detecting element, when viewing the capsule endoscope from the object side, so that an area that is symmetrically positioned about the optical axis of the objective optical system from a light emitting area of the illumination means overlaps an area of the image detecting element but does not overlap any area of the image detecting element that is used for picture image detection.  
 
     
     
       10. The capsule endoscope according to  claim 9 , wherein an area of the image detecting element that is not used for picture imaging and which is symmetrically positioned, when viewing the capsule endoscope from the object side, about an optical axis of the objective optical system from a light emitting area of the illumination means is a mask area that is electrically masked at the time of the picture image processing. 
     
     
       11. The capsule endoscope according to  claim 9 , wherein:
 the objective optical system has an entrance pupil;  
 the transparent cover has an outer surface, the center of curvature of the outer surface being located substantially at the entrance pupil position; and  
 the transparent cover has a thickness that, from a maximum opposite the entrance pupil, decreases toward the periphery of the transparent cover.  
 
     
     
       12. A capsule endoscope, comprising:
   illumination means that includes a light emitting element for illuminating an object;        imaging means for imaging the object; and        a transparent cover having a center of curvature, said transparent cover covering the illumination means and the imaging means;      
       
         wherein  
         
           the imaging means includes an objective optical system and an image detecting element;  
         
         
           an entrance pupil position of the objective optical system is arranged so that its center is located substantially at the center of curvature of the transparent cover; and  
         
         
           the illumination means is positioned off of the center of curvature, whereby light from the illumination means which is internally reflected by the transparent cover does not pass through the center of curvature and does not enter the entrance pupil position of the objective optical system. 
         
       
     
     
       13. The capsule endoscope according to  claim 12 , wherein the illumination means includes a plurality of light emitting elements which are arranged around the center of curvature, near the periphery of the transparent cover. 
     
     
       14. The capsule endoscope according to  claim 12 , wherein the transparent cover has a semi-spherical shape with a uniform thickness. 
     
     
       15. The capsule endoscope according to  claim 14 , wherein the entrance pupil position is arranged so that it is located substantially at the center of curvature, within a specified visual field, of both an inner surface and an outer surface of the transparent cover. 
     
     
       16. The capsule endoscope according to  claim 12 , wherein the transparent cover has a semi- spherical shape.   
     
     
       17. The capsule endoscope according to  claim 16 , wherein the thickness of the transparent cover is thicker on the optical axis of the objective optical system and tapers so as to become thinner toward the peripheral regions of the field of view. 
     
     
       18. The capsule endoscope according to  claim 12 , wherein the illumination means comprises an even number of LEDs arranged around the periphery of the objective optical system. 
     
     
       19. A capsule endoscope, comprising:
   illumination means that includes a light emitting element for illuminating an object;        imaging means for imaging the object; and        a transparent cover having a center of curvature, said transparent cover covering the illumination means and the imaging means;      
       
         wherein  
         
           the imaging means includes an objective optical system and an image detecting element;  
         
         
           an entrance pupil position of the objective optical system is arranged so that its center is located substantially at the center of curvature of the transparent cover; and  
         
         
           the illumination means is positioned somewhere else than the center of curvature, whereby light from the illumination means that is reflected by the inner surface of the transparent cover is not returned to the center of curvature and does not enter the entrance pupil position of the objective optical system. 
         
       
     
     
       20. The capsule endoscope according to  claim 19 , wherein the illumination means includes a plurality of light emitting elements which are arranged around the center of curvature, near the periphery of the transparent cover. 
     
     
       21. The capsule endoscope according to  claim 19 , wherein the transparent cover has a semi- spherical shape with a uniform thickness.   
     
     
       22. The capsule endoscope according to  claim 19 , wherein the entrance pupil position is arranged so that its center is located, within a specified visual field, substantially at the center of curvature of the inner surface of the transparent cover. 
     
     
       23. The capsule endoscope according to  claim 22 , wherein the transparent cover has a semi- spherical shape.