US2015146076A1PendingUtilityA1

Image Pickup Optical System and Image Pickup Apparatus Using the Same

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Assignee: OLYMPUS CORPPriority: Feb 25, 2009Filed: Jan 29, 2015Published: May 28, 2015
Est. expiryFeb 25, 2029(~2.6 yrs left)· nominal 20-yr term from priority
Inventors:Takuya Ohtsu
G02B 9/60G02B 13/0045G02B 13/16G02B 13/18
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Claims

Abstract

An image pickup optical system made of five lenses, includes in order from an object side, an aperture stop, a first lens L 1 having a positive refracting power, a second lens L 2 having a negative refracting power, a third lens L 3 having a positive refracting power, a fourth lens L 4 having a positive refracting power, and a fifth lens L 5 having a negative refracting power. Moreover, an image pickup apparatus includes this image pickup optical system.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . An image pickup apparatus, comprising:
 an image pickup optical system;   an electronic image pickup element having an image pickup surface to receive an image from the image pickup optical system; and   an auto-focus mechanism,   wherein   the image pickup optical system comprises in order from an object side along an optical axis of the image pickup optical system:   an aperture stop;   a first lens having a positive refracting power;   a second lens having a negative refracting power;   a third lens;   a fourth lens, wherein a surface on an object side is concave shaped; and   a fifth lens having a negative refracting power,   wherein   an air space is provided between the second lens and the third lens, and   at least one of surfaces of the fifth lens has an inflection point.   
     
     
         2 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expression:
   0.36< f 4/ f< 3.88   where,   f4 denotes a focal length of the fourth lens, and   f denotes a focal length of the overall image pickup optical system.   
     
     
         3 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expressions:
   −1.27< r 8/ f<− 0.25
     0.36< f 4/ f≦ 0.98   where,   f denotes a focal length of the overall image pickup optical system,   f4 denotes a focal length of the fourth lens, and   r8 denotes a paraxial radius of curvature of an object side surface of the fourth lens.   
     
     
         4 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expression:
   0.28< f 1/ f< 1.23   where,   f1 denotes a focal length of the first lens, and   f denotes a focal length of the overall image pickup optical system.   
     
     
         5 . The image pickup apparatus according to  claim 1 , wherein a surface on an image surface side of the second lens is concave shaped toward the image surface side. 
     
     
         6 . The image pickup apparatus according to  claim 1 , wherein a surface on an object side of the third lens is concave shaped. 
     
     
         7 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expression:
     vd 3<30.2   where,   vd3 denotes an Abbe's number for the third lens.   
     
     
         8 . The image pickup apparatus according to  claim 1 , wherein a surface on an object side of the fifth lens is concave shaped. 
     
     
         9 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expressions:
   0<|(SAG4 AS −SAG4 AA )/4 AR|< 0.147,and
     0<|(SAG4 BS −SAG4 BA )/4 BR|< 0.395
   where,   SAG4AS denotes a sag amount at a position which is 60% of an effective diameter when a surface on the object side of the fourth lens is let to be a spherical surface,   SAG4AA denotes a sag amount at a position which is 60% of an effective diameter of the surface on the object side of the fourth lens,   SAG4BS denotes a sag amount at a position which is 60% of an effective diameter when a surface on an image pickup surface side of the fourth lens is let to be a spherical surface,   SAG4BA denotes a sag amount at a position which is 60% of an effective diameter of the surface on the image pickup surface side of the fourth lens,   4AR denotes a paraxial radius of curvature of the surface on the object side of the fourth lens, and   4BR denotes a paraxial radius of curvature of the surface on the image pickup surface side of the fourth lens.   
     
     
         10 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expression:
   0.15< BF /TTL<0.22   where,   BF denotes a distance on the optical axis between image side surface and image pickup surface of the fifth lens,   TTL denotes a total length of the image pickup optical system.   
     
     
         11 . The image pickup apparatus according to  claim 1 , wherein the image pickup optical system satisfies the following conditional expression:
   0.15< BF /TTL<0.25   where,   BF denotes a distance on the optical axis between image side surface and image pickup surface of the fifth lens,   TTL denotes a total length of the image pickup optical system.   
     
     
         12 . The image pickup apparatus according to  claim 1 , wherein the air space between the second lens and the third lens works as an air lens having a biconvex shape. 
     
     
         13 . The image pickup apparatus according to  claim 1 , wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are formed of a resin. 
     
     
         14 . The image pickup apparatus according to  claim 1 , wherein the image pickup apparatus satisfies the following conditional expression:
   15°<α i< 30°
   where,   αi denotes an angle of incidence of principal light rays on an image pickup surface at a maximum image height.   
     
     
         15 . An information processing apparatus, comprising:
 an input section which operates the information processing apparatus;   a processing section which processes information at least from the input section;   an image pickup apparatus which obtains image information based on information from the processing section;   an image processing section which processes image information obtained by the image pickup apparatus; and   a display section which displays the processed image,   wherein   the image pickup apparatus includes an image pickup optical system, an electronic image pickup element having an image pickup surface to receive the image from the image pickup optical system, and an auto-focus mechanism,   the image pickup optical system comprising in order from an object side along an optical axis of the image pickup optical system:   an aperture stop;   a first lens having a positive refracting power;   a second lens having a negative refracting power;   a third lens;   a fourth lens, wherein a surface on an object side is concave shaped; and   a fifth lens having a negative refracting power,   wherein   an air space is provided between the second lens and the third lens, and   at least one of surfaces of the fifth lens has an inflection point.   
     
     
         16 . The information processing apparatus according to  claim 15 , wherein the image pickup optical system satisfies the following conditional expressions:
   −1.27< r 8/ f<− 0.25
     0.36< f 4/ f≦ 0.98   where,   f denotes a focal length of the overall image pickup optical system,   f4 denotes a focal length of the fourth lens, and   r8 denotes a paraxial radius of curvature of an object side surface of the fourth lens.   
     
     
         17 . The information processing apparatus according to  claim 15 , further comprising:
 a communication section which is able to communicate the image information obtained by the image pickup apparatus.   
     
     
         18 . The information processing apparatus according to  claim 15 , further comprising:
 a microphone section; and   an information recording section.   
     
     
         19 . The information processing apparatus according to  claim 15 , wherein a surface on an object side of the fifth lens is concave shaped. 
     
     
         20 . The information processing apparatus according to  claim 15 , wherein the information terminal is a portable electronic device. 
     
     
         21 . The image pickup apparatus according to  claim 1 , wherein the first lens has
 a convex object-side surface convex to an object side, and vertical surface which is perpendicular to the optical axis, and located around the convex object-side surface.   
     
     
         22 . The image pickup apparatus according to  claim 21 , wherein a total number of lenses in the image pickup optical system is five. 
     
     
         23 . The image pickup apparatus according to  claim 22 , wherein the fourth lens has a positive refracting power. 
     
     
         24 . The image pickup apparatus according to  claim 23 , wherein the fifth lens has a negative refracting power. 
     
     
         25 . The image pickup apparatus according to  claim 24 , wherein the third lens has an image-side surface convex to an image side. 
     
     
         26 . The image pickup apparatus according to  claim 25 , wherein the forth lens has an object-side surface concave to an object-side and an image-side surface convex to an image side.

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