Camera with flange back adjusting mechanism

A camera includes a flange back adjusting mechanism in which the operation of the flange back adjusting mechanism is not obstructed, and the flange back adjustment is easily performed. A flange back adjusting mechanism which moves and adjusts a CCD in the direction of the optical axis can be operated by an operation section which protrudes to the outside of a case portion through an operation window. The operation window is opened in a side wall face of a camera chassis separating rearward from a lens mount portion along the direction of the optical axis and on a peripheral wall of a case portion of the camera chassis.

The illustrated camera with a flange back adjusting mechanism is disclosed in JP-B-7-8021, and includes: a camera chassis 5 having a lens mount portion 3 to which a lens is to be mounted and a case portion 4 which is rearward continuous to thelens mount portion 3; a device holder 9 which is supported by the camera chassis 5 so as to be movable in the vicinity of the imaging position of the lens mounted to the lens mount portion 3 and along the optical axis 7 of the lens; a CCD (charge-coupleddevice) 11 serving as a solid state imaging device which is held on the optical axis of the lens by the device holder 9 and which converts an incident optical signal into an electric signal and outputs the electric signal; and a flange back adjustingmechanism 13 which moves and adjusts the position of the device holder 9 in the direction of the optical axis of the lens.

In this example, the lens mount portion 3 is formed separately from the case portion 4. The lens mount portion 3 has a substantially cylindrical shape, and includes a front escutcheon 3a which is formed integrally with the periphery of the mountportion. Four corners of the escutcheon 3a are fastened to a front face of the case portion 4 by screw members 15, whereby the mount is coupled and fixed to the case portion 4.

The device holder 9 has a rectangular recess 9a into which the CCD 11 is fitted. The periphery of the CCD 11 which is fitted into the recess 9a is pressed by a device pressing plate 17 which is screwed to a front face of the device holder 9 inorder to attain a state where the CCD is fixed to the device holder 9.

The device holder 9 is fixed to a chassis attaching bracket 19 by screw members 18. The bracket 19 is supported so as to be movable in the direction of the optical axis of the lens between a front wall 4a of the case portion 4 and the lens mountportion 3. The bracket 19 is urged toward the lens mount portion 3 by springs 21 which are inserted in a compressed state between the bracket and the front wall 4a of the case portion 4.

In the flange back adjusting mechanism 13, a stopper portion 23a which butts against a front end portion of the bracket 19 that is urged by the springs 21 in order to perform positioning of the bracket 19 in the direction of the optical axis, anda cam portion 23b which gives a displacement of the lens in the direction of the optical axis are disposed on a cam ring 23 which is fitted onto an outer periphery of the lens mount portion 3.

In order to attain the object, the camera with a flange back adjusting mechanism of the invention is a camera with a flange back adjusting mechanism including: a camera chassis having a lens mount portion; a device holder which is supported bythe camera chassis to be movable in a vicinity of an imaging position of a lens and in a direction of an optical axis; a solid state imaging device which is held by the device holder; and a flange back adjusting mechanism which moves and adjusts thedevice holder in the direction of the optical axis,

wherein the flange back adjusting mechanism includes: a cam ring which is supported to be rotatable about the optical axis in the camera chassis and in which a cam surface is disposed in a peripheral edge portion, a projection length of the camsurface in the direction of the optical axis being gradually changed in a circumferential direction; a positioning protrusion which protrudes from the device holder, a tip end of the protrusion butting against the cam surface; a holder urging springwhich urges the device holder toward the cam ring to maintain a state where the positioning protrusion butts against the cam surface; an operation window which is opened in a side wall face of the camera chassis, the side wall face extending along thedirection of the optical axis; and a ring driving mechanism which rotates the cam ring by an operation section that protrudes to an outside through the operation window.

According to the configuration, the operation section of the flange back adjusting mechanism for moving the device holder is placed on the side wall face of the camera chassis which is rearward separated from the lens mount portion. Even when aninterchangeable lens of a large aperture is mounted to the lens mount portion, therefore, the operation section does not hide in a valley portion behind the interchangeable lens.

In the camera with a flange back adjusting mechanism, preferably, the ring driving mechanism is configured to rotate a driving gear which meshes with the cam ring by the operation section, and includes an elastic member which applies to thedriving gear a load that blocks rotation of the driving gear when a rotation operating force is equal to or smaller than a reference.

According to the configuration, the load which is applied to the driving gear by the elastic member exerts a braking function which prevents rattling of the driving gear and the operation section due to backlash in a gear train used in the flange back adjusting mechanism, from occurring, thereby preventing an error due to rattling from being produced in transmission of the operating force.