Electronic camera

Abstract

A photographic lens system for forming an object image is placed in the lens barrel of an electronic camera. In a camera body, a beam splitter for forming branched optical paths and an image sensing element for photoelectrically converting the formed object image are arranged. An optical filter attached to a filter cap is inserted between the beam splitter and the image sensing element. The filter cap intimately contacts with the perimeter of the exit surface of the beam splitter and the perimeter of the image sensing surface of the image sensing element, thereby forming closed spaces, between the optical filter and the beam splitter and between the optical filter and the image sensing element, which allow incident light to pass through.

What is claimed is:  
     
         1 . An electronic camera comprising: 
 a photographic lens configure to form an object image;    an image sensing element configured to photoelectrically convert the formed object image;    a light guiding device configured to guide incident light from an object, which is incident from the photographic lens, to a first optical path to the image sensing element and a second optical path different from the first optical path;    an optical filter disposed between the light guiding device and the image sensing element; and    a filter holding member made of an elastic material to hold the optical filter, the filter holding member comprising a first portion that surrounds and holds an outer-diameter portion of the optical filter, and a second portion that forms a closed space between the optical filter and the light guiding device, and the second portion being connected to the first portion and intimately contacting with that surface of the light guiding device, which faces the optical filter, so as to surround the first optical path.    
     
     
         2 . The camera according to  claim 1 , wherein the optical filter and the light guiding device are assembled against an elasticity of the filter holding member, thereby allowing the second portion of the filter holding member to intimately contact with the light guiding device.  
     
     
         3 . The camera according to  claim 1 , wherein the filter holding member further comprises a third portion that forms a closed space between the optical filter and the image sensing element, the third portion being connected to the first portion and intimately contacting with that surface of the light guiding device, which faces the optical filter, so as to surround the first optical path.  
     
     
         4 . The camera according to  claim 3 , wherein the filter holding member comprises first and second members split in the longitudinal direction of the optical axis, the second and third portions are arranged in the first and second members, respectively, and the first and second members intimately contact with each other.  
     
     
         5 . The camera according to  claim 1 , wherein the light guiding device comprises a light splitting device configured to split the incident light to the first and second optical paths.  
     
     
         6 . The camera according to  claim 5 , wherein the light splitting device comprises a beam splitter.  
     
     
         7 . The camera according to  claim 1 , further comprising: 
 an optical member disposed on the second optical path in the vicinity of the light guiding device; and    an elastic member configured to form a closed space between the optical member and the light guiding device, the elastic member intimately contacting with opposite surfaces of the optical member and the light guiding device and surrounding a space between the opposite surfaces so as to surround the second optical path.    
     
     
         8 . An electronic camera comprising: 
 a photographic lens configure to form an object image;    an image sensing element configured to photoelectrically convert the formed object image;    a light guiding device configured to guide incident light from an object, which is incident from the photographic lens, to a first optical path to the image sensing element and a second optical path different from the first optical path;    an optical member disposed on the second optical path in the vicinity of the light guiding device; and    an elastic member configured to form a closed space between the optical member and the light guiding device, the elastic member intimately contacting with opposite surfaces of the optical member and the light guiding device and surrounding a space between the opposite surfaces so as to surround the second optical path.    
     
     
         9 . The camera according to  claim 8 , wherein the optical member and the light guiding device are assembled against an elasticity of the elastic member, thereby allowing the elastic member to intimately contact with the optical member and the light guiding device.  
     
     
         10 . The camera according to  claim 8 , wherein the second optical path comprises an optical path to an optical finder unit configured to form an image for visual check of an object image.  
     
     
         11 . An electronic camera comprising: 
 a photographic lens configure to form an object image;    an image sensing element configured to photoelectrically convert the formed object image;    an optical filter disposed between the photographic lens and the image sensing element;    a focal-plane shutter disposed between the photographic lens and the optical filter to mechanically interrupt incident light to the image sensing element; and    a holding frame configured to surround the image sensing element and the optical filter and to form a closed space between the image sensing element and the optical filter.    
     
     
         12 . The camera according to  claim 11 , further comprising a light guiding device disposed between the photographic lens and the optical filter to guide incident light from an object, which is incident from the photographic lens, to a first optical path to the image sensing element and a second optical path different from the first optical path.  
     
     
         13 . The camera according to  claim 12 , wherein the light guiding device comprises a light splitting device configured to split the incident light to the first and second optical paths.  
     
     
         14 . The camera according to  claim 13 , wherein the light splitting device comprises a beam splitter.  
     
     
         15 . The camera according to  claim 12 , wherein the light guiding device comprises an optical path switching device configured to switch first and second states in which the incident light is output to the first and second optical paths, respectively.  
     
     
         16 . The camera according to  claim 15 , wherein the optical path switching device comprises a movable mirror.  
     
     
         17 . The camera according to  claim 11 , further comprising: 
 a stop device configured to limit the amount of light beam incident on the image sensing element;    a stop controller configured to form a set value of the aperture area of the stop device;    a shutter controller configured to form a set value of the shutter speed of the focal-plane shutter; and    an exposure controller configured to operate the focal-plane shutter in different modes in accordance with the set value of the aperture area of the stop, even when the set value of the shutter speed remains the same, thereby obtaining a predetermined exposure time.    
     
     
         18 . An electronic camera comprising: 
 a photographic lens configure to form an object image;    an image sensing element configured to photoelectrically convert the formed object image;    an optical filter disposed between the photographic lens and the image sensing element;    a light guiding device disposed between the photographic lens and the optical filter to guide incident light from an object, which is incident from the photographic lens, to a first optical path to the image sensing element and a second optical path different from the first optical path;    a focal-plane shutter disposed between the photographic lens and the light guiding device to mechanically interrupt incident light to the image sensing element; and    a holding frame configured to surround the image sensing element and the optical filter and to form a closed space between the image sensing element and the optical filter.    
     
     
         19 . The camera according to  claim 18 , further comprising: 
 a stop device configured to limit the amount of light beam incident on the image sensing element;    a stop controller configured to form a set value of the aperture area of the stop device;    a shutter controller configured to form a set value of the shutter speed of the focal-plane shutter; and    an exposure controller configured to operate the focal-plane shutter in different modes in accordance with the set value of the aperture area of the stop, even when the set value of the shutter speed remains the same, thereby obtaining a predetermined exposure time.    
     
     
         20 . The camera according to  claim 18 , wherein the light guiding device comprises a light splitting device configured to split the incident light to the first and second optical paths.  
     
     
         21 . The camera according to  claim 18 , wherein the light guiding device comprises an optical path switching device configured to switch first and second states in which the incident light is output to the first and second optical paths, respectively.