Imaging apparatus and distance measuring apparatus using the same

Abstract

An imaging apparatus in an embodiment includes lens optical systems each including a lens whose surface closest to the target object is shaped to be convex toward the target object, imaging regions which respectively face the lens optical systems and output a photoelectrically converted signal corresponding to an amount of light transmitting the lens optical systems and received by the imaging regions, and a light-transmissive cover which covers an exposed portion of the lens of each of the lens optical systems and a portion between the lens of one of the lens optical systems and the lens of another one of the lens optical systems adjacent to the one of the lens optical systems, the cover having a curved portion which is convex toward the target object. The optical axes of the lens optical systems are parallel to each other.

What is claimed is: 
     
         1 . An imaging apparatus for capturing an image of a target object, comprising:
 lens optical systems each including a lens whose surface closest to the target object is shaped to be convex toward the target object;   light detection cells which respectively face the lens optical systems;   retainers each retaining the lens which is closest to the target object in each of the lens optical systems;   a cover which covers an exposed portion of the lens of each of the lens optical systems, the cover having a curved portion which is convex toward the target object; and   a casing which houses the light detection cells, wherein each of the retainers protrudes from the casing.   
     
     
         2 . The imaging apparatus according to  claim 1 , wherein |f 0 |>50 fx is satisfied, where f 0  represents a focal length of the cover and fx represents the focal length of each of the lens optical systems. 
     
     
         3 . The imaging apparatus according to  claim 1 , wherein optical axes of the lens optical systems are fixed to each other. 
     
     
         4 . The imaging apparatus according to  claim 1 , wherein the lens which is closest to the target object in each of the lens optical systems is a concave meniscus lens. 
     
     
         5 . The imaging apparatus according to  claim 1 , wherein
 the lens optical systems are arranged in a direction, and   a cross section of the cover that is perpendicular to the direction has an arch shape.   
     
     
         6 . The imaging apparatus according to  claim 1 , further comprising:
 a computation circuit, wherein   in operation, the computation circuit measures a distance to the target object based on a parallax of the target object in images obtained in the light detection cells of the imaging apparatus.   
     
     
         7 . The imaging apparatus according to  claim 1 , wherein the lens optical systems include more than four lens optical systems each of which has a different optical axis. 
     
     
         8 . The imaging apparatus according to  claim 1 , wherein in plan view, a center of the cover does not overlap the surface of the lens which is closest to the target object in each of the lens optical systems. 
     
     
         9 . The imaging apparatus according to  claim 1 , wherein each of the lens optical systems has an angle of view of 120 degrees or more in at least one direction. 
     
     
         10 . The imaging apparatus according to  claim 1 , wherein an angle between an optical axis of each of the lens optical systems and a normal to a tangent line at an end of an effective diameter of the cover across which light from the target object passes through is 75 degrees or less. 
     
     
         11 . A monitoring system for a vehicle comprising the imaging apparatus according to  claim 1 .