Patent Publication Number: US-2003223743-A1

Title: Camera body

Description:
INCORPORATION BY REFERENCE  
     [0001] The disclosure of the following priority application is herein incorporated by reference: Japanese Patent Application No. 2002-005302 filed Jan. 11, 2002 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to a camera body.  
       [0004] 2. Description of the Related Art  
       [0005] The frame structure assumed in a camera in the related art includes two primary structural components, i.e., a front body and a rear body. In the case of a single lens reflex camera, the front body having a bayonet mount at which an interchangeable lens is mounted, a main mirror, a prism box and the like provided therein fulfills a function of securing a photographic optical path. At the rear body, a film cartridge chamber in which a film cartridge is loaded, a spool chamber into which the film drawn out from the film cartridge is taken up, an aperture that defines the photographic image plane and the like are provided. By docking the front body and the rear body, the camera frame structure is achieved. FIGS. 8 and 9 illustrate docking modes adopted in cameras in the related art.  
       [0006]FIG. 8 is a perspective of a first prior art example. A rear body  410  in FIG. 8 includes an aperture  411  that defines the photographic image plane, a film cartridge chamber  412  and a spool chamber  413 . The rear body  410  is placed in contact with a front body  420  to be explained next at the film cartridge chamber-side docking surfaces  414  and  415  and spool chamber-side docking surfaces  416  and  417 , and is docked (joined) with the front body  420 .  
       [0007] The front body  420  includes a bayonet mount mounting surface  421 . The front body  420  is docked with the rear body  410  at film cartridge chamber-side docking portions  422 ˜ 422   a  and spool chamber-side docking portions  423  and  424 .  
       [0008]FIG. 9 is a perspective of a second prior art example. At a rear body  430  in FIG. 9, an aperture  431  that defines the photographic image plane, a film cartridge chamber  432  and a spool chamber  433  are provided. The rear body  430  is docked with a front body  450  which is to be explained next at film cartridge chamber-side surfaces  434  and  435 , spool chamber-side docking surfaces  436  and  437 , upper docking surfaces  438  and  439  above the aperture and lower docking surfaces  440  and  441  below the aperture.  
       [0009] The front body  450  is docked with the rear body  430  at a bayonet mount mounting surface  451 , film cartridge chamber-side docking portions  452  and  453 , spool chamber-side docking portions  454  and  455 , rear docking portions  456  and  457  at the rear of the prism box storage portion and lower docking portions  458  and  459  below the bayonet mount mounting surface.  
       [0010] In addition to the four docking locations in the example presented in FIG. 8, the rear body  430  in FIG. 9 includes two docking surfaces above and near the aperture and two docking surfaces below the aperture and to the front of the film cartridge chamber and the spool chamber, whereas the front body  450  in FIG. 9 includes two docking surfaces located to the rear of the prism box storage portion and two docking surfaces located on the back side of the portion below the bayonet mount mounting surface.  
       [0011] In recent years, a camera is manufactured by forming the front body and the rear body with plastic molds while implementing individual and precise management of the measurement of the front body from the bayonet mount mounting surfaces to the rear body docking surfaces along the optical axis and the measurement of the rear body from the film rail surfaces to the front body docking surfaces along the optical axis. As a result, the measurement from the lens mount surfaces to the film rail taken after the front body and the rear body are docked with each other achieves a high degree of dimensional accuracy without requiring any adjustment.  
       [0012] However, desired dimensions often cannot be achieved with accuracy with regard to the distance between the film rail surface to the docking surfaces in the structure illustrated in FIG. 8 due to deformations of the film cartridge chamber and the spool chamber at the rear body occurring during the molding process.  
       [0013] In addition, desired dimensions often cannot be achieved with accuracy with regard to the distance from the bayonet mount mounting surface to the upper docking surfaces at the rear in the structure shown in FIG. 9 due to a deformation of the prism box storage portion at the front body which also occurs during the molding process. Also, it is more difficult to achieve consistency in the structure shown in FIG. 9, since the upper docking surfaces at the rear of the front body and the docking surfaces at the back portion below the bayonet mount mounting surface are formed by using different molds, i.e., the upper docking surfaces at the rear of the front body are formed with a mold that is extracted toward the rear and the docking surface at the back lower portion of the bayonet mount mounting surface is formed by using a mold that is extracted downward.  
       SUMMARY OF THE INVENTION  
       [0014] The present invention provides a camera body that makes it possible to reduce the extent of the dimensional inconsistency attributable to the process through which the front body and the rear body are molded and to achieve dimensional accuracy in the camera body achieved by docking the front body and the rear body.  
       [0015] A camera body according to the present invention comprises: a first body having a photographic lens mounting portion at which a photographic lens can be mounted; and a second body having a reference surface to be used to position a photographic recording medium, and the first body is mounted at a surface substantially matching the reference surface at the second body.  
       [0016] In this camera body, it is preferred that: the first body includes a plurality of mounting surfaces, at which the first body is joined with the first body, substantially in a single surface; and the second body includes a plurality of mounting surfaces, at which the second body is joined with the second body, in the surface substantially matching the reference surface. In this case, it is preferred that the plurality of mounting surfaces at the first body are fastened to the plurality of mounting surfaces at the second body with fastening parts. Furthermore, it is preferred that: the photographic recording medium is film; the reference surface is equivalent to a film rail surface; and the plurality of mounting surfaces at the second body are provided around an opening formed in the film rail surface. Yet furthermore, it is preferred that: the first body and the second body are formed through plastic molding; and the plurality of mounting surfaces at the first body are formed by using a single mold.  
       [0017] In the above camera body, it is preferred that the first body is formed in a box shape.  
       [0018] Also, it is preferred that the first body and the second body are formed through plastic molding.  
       [0019] Also, it is preferred that: the photographic recording medium is film; and the reference surface is equivalent to a film rail surface. In this case, it is preferred that: there is further provided a shutter unit provided between the first body and the second body; and the film rail surface is formed of metal.  
       [0020] Also, it is preferred that: the photographic recording medium is an image-capturing element; and the reference surface is equivalent to a surface at which the image-capturing element is mounted.  
       [0021] Also, it is preferred that a bayonet mount is mounted at the photographic lens mounting portion of the first body.  
       [0022] Also, it is preferred that a shutter unit provided between the first body and the second body. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0023]FIG. 1 is a perspective of a camera body achieved in an embodiment of the present invention;  
     [0024]FIG. 2 is a perspective of the camera body achieved in the embodiment of the present invention;  
     [0025]FIG. 3 is a front view of the camera body achieved in the embodiment of the present invention;  
     [0026]FIG. 4 is a rear view of the camera body achieved in the embodiment of the present invention;  
     [0027]FIG. 5 is a rear view of the camera body achieved in the embodiment of the present invention;  
     [0028]FIG. 6 illustrates how the present invention may be adopted in a digital camera;  
     [0029]FIG. 7 presents an example in which the present invention is adopted in another digital camera;  
     [0030]FIG. 8 is a perspective of an example of a camera body in the related art; and  
     [0031]FIG. 9 is a perspective of an example of a camera body in the related art. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0032] The following is an explanation of the embodiments of the present invention given in reference to the drawings.  
     [0033]FIG. 1 is a perspective of a camera body achieved in an embodiment of the present invention. The camera in FIG. 1 is a single lens reflex camera that uses silver halide film and allows the use of interchangeable photographic lenses.  
     [0034] At a rear body  110  in FIG. 1, an aperture  111 , a film cartridge chamber  112  and a spool chamber  113  are provided. The rear body  110  is docked (joined) with a front body  120  to be explained next, at aperture upper-side docking surfaces  114  and  115  located above the aperture and aperture lower-side docking surfaces  116  and  117  (the docking surface  117  is not shown in FIG. 1), located below the aperture. The aperture upper-side docking surfaces  114  and  115  and the aperture lower-side docking surfaces  116  and  117  are provided around the aperture  111 .  
     [0035] At the front body  120 , a mirror box  121  in which a main mirror is stored and bayonet mount mounting surfaces  122 ˜ 126  (the bayonet mount mounting surface at the lower left is not shown) are provided. The front body  120  is docked with the rear body  110  at aperture upper-side docking surfaces  127  and  128  and aperture lower-side docking surfaces  129  and  130  (the docking surface  130  is not shown in FIG. 1). The front body  120  and the rear body  110  are docked to each other by attaching the rear body  110  onto the front body  120  from the rear side along the optical axis with docking screws  161 ˜ 164 .  
     [0036] The front body  120  and the rear body are formed through plastic molding.  
     [0037] A bayonet mount  140  is mounted onto the bayonet mount mounting surfaces  122 ˜ 126  (the bayonet mount mounting surface at the lower left is not shown) with bayonet mount mounting screws  151 ˜ 156 . The bayonet mount mounting screws  151 ˜ 156  are respectively inserted through bayonet mount mounting holes  141 ˜ 146  from the front side along the optical axis to attach the bayonet mount  140  to the front body  120 .  
     [0038]FIG. 2 presents a schematic perspective that clearly illustrates the state described above. The front body  120 , which includes a bayonet mount mounting surface  131 , a penta-mirror (pentaprism) storage portion  132  and the mirror box  121 , assumes a box structure, as shown in FIG. 2, so as not to become deformed readily during the molding process.  
     [0039] The six bayonet mount mounting surfaces  122 ˜ 126  (one of them is not shown), which are located at a single flat surface  131  at the front side along the optical axis are formed with a mold that is extracted toward the front. The four body docking surfaces  127 ˜ 130 , which are formed at a single flat surface  133  at the rear side along the optical axis to dock with the rear body, are formed with a mold that is extracted toward the rear. The aperture upper-side docking surfaces  114  and  115  and the aperture lower-side docking surfaces  116  and  117  at the rear body  110  are formed at a single flat surface  118  by using a single mold.  
     [0040] By forming mounting surfaces (docking surfaces) at a given flat surface with a single mold, as described above, the extent of dimensional inconsistency can be reduced.  
     [0041]FIG. 3 is a front view of the rear body  110  viewed from the front side along the optical axis. It clearly shows the docking surfaces  114  and  115  above the aperture and the docking surfaces  116  and  117  below the aperture.  
     [0042]FIG. 4 is a rear view of the front body  120  viewed from the rear side along the optical axis. It clearly shows the docking surfaces  127  and  128  above the aperture and the docking surfaces  129  and  130  below the aperture.  
     [0043]FIG. 5 is a rear view of the front body  120  mounted with a focal plane shutter, viewed from the rear side along the optical axis. A shutter  170  is mounted at the front body  120  with screws  171  and  172 . The docking surfaces  127 ˜ 130  are located further outside relative to the shutter  170 . If it is necessary to fine-adjust the dimensions from the bayonet mount surface to the film rail surface for docking the front body  120  and the rear body  110 , the front body  120  and the rear body  110  should be docked with each other by inserting dimensional adjustment washers at the four docking surfaces. Alternatively, they may be docked with each other by ensuring that the four docking surfaces have a uniform height, placing a thin plate having a hole larger than the aperture behind the shutter and clamping the plate at the docking surfaces. In addition, by forming the film rail, which is used as a reference surface of the rear body  110 , with a metal that is harder than plastic, a higher degree of dimensional accuracy can be achieved. A higher degree of dimensional accuracy can also be achieved by providing a highly rigid shutter unit at the contact surface where the front body  120  and the rear body  110  come into contact with each other.  
     [0044] In the camera achieved in the embodiment as described above, dimensional inconsistency at the front body and the rear body is minimized and a high degree of dimensional accuracy is achieved along the optical axis from the bayonet mount mounting surface to the film rail surface when the front body and rear body are docked with each other.  
     [0045] It is to be noted that while an explanation is given above in reference to the embodiment on an example in which the present invention is adopted in a single lens reflex camera that uses silver halide film, the present invention is not limited to this example. For instance, the present invention may be adopted in a single lens reflex digital camera (electronic camera) that employs an image-capturing element such as a CCD. FIG. 6 illustrates how the present invention may be adopted in a digital camera and corresponds to FIG. 2 explained earlier. An image-capturing element  119  is mounted at a reference surface  118  which corresponds to the film rail surface mentioned earlier. This structure makes it possible to achieve a high degree of dimensional accuracy along the optical axis from the bayonet mount mounting surface to the image-capturing surface at the image-capturing element  119  when the front and rear bodies are docked with each other.  
     [0046]FIG. 7 illustrates how the present invention may be adopted in another digital camera and corresponds to FIG. 2 explained earlier. An image-capturing element  119  is mounted at an image-capturing element mounting reference surface  182  at an image-capturing element mounting frame  181 . The image-capturing element mounting reference surface  182  includes docking surfaces  183 ˜ 186  which are equivalent to the aperture upper-side docking surfaces  114  and  115  and the aperture lower-side docking surfaces  116  and  117 . The front body  120  includes the aperture upper-side docking surfaces  127  and  128  and the aperture lower-side docking surfaces  129  and  130  as does the front body  120  explained earlier. The front body  120  and the image-capturing element mounting frame  181  are docked with each other over the aperture upper-side docking surfaces  127  and  128 , the aperture lower-side docking surfaces  129  and  130  and the docking surfaces  183 ˜ 186 . Reference numeral  187  indicates a rear cover. The rear cover  187  and the image-capturing element mounting frame  181  do not need to be locked to each other, as long as a high degree of dimensional accuracy along the optical axis from the bayonet mount mounting surface to the image-capturing surface at the image-capturing element  119  is achieved when the front body  120  and the image-capturing element mounting frame  181  are docked with each other. The image-capturing element mounting frame  181  may assume any shape as long as a stable flat surface is assured as the image-capturing mounting reference surface  182  and the image-capturing element  119  can be firmly fixed to the image-capturing element mounting reference surface  182 .  
     [0047] The above described embodiments are examples, and the various modifications can be made without departing from the spirit and scope of the invention.