Abstract:
A cam plate is disposed horizontally and movably to a horizontal direction inside a camera body. The cam plate includes a plate portion for moving variator lenses of a zoom finder device in cooperation with a zoom lens to vary a viewable field angle of a zoom finder device, and a rack gear formed integrally with the plate portion. The rack gear is engaged with an intermediate gear. A first flat gear being concentric with the intermediate gear is engaged with a second flat gear. Two flash rack gears are engaged with the first and second flat gears with putting them between the flash rack gears. These flash rack gears are formed in a frame holding a flash projector. When the zoom lens moves, the cam plate moves horizontally to vary the viewable field angle of the zoom finder device, and simultaneously the rack gear rotates the first and second flat gears. These first and second flat gears move the flash projector through the flash rack gears in order to vary an illuminating angle of a flashlight.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a zoom interlocking mechanism which varies a viewable field angle of a zoom finder device and an illuminating angle of a flashlight in cooperation with a zoom lens assembly.  
           [0003]    2. Background Arts  
           [0004]    A camera with a zoom lens assembly usually has a zoom finder device. In the zoom finder device, variator lenses move simultaneously with zooming of the zoom lens assembly in order to vary a viewable field angle of the zoom finder device. Also is known a zoom flash device which varies an illuminating angle of a flashlight in cooperation with the zooming of the zoom lens assembly, in order to make efficient use of the flashlight even when the zooming changes photographic field angle.  
           [0005]    A zoom interlocking mechanism, which is disclosed in Japanese Laid-Open Patent Application No. 10-186480 (corresponding to U.S. Pat. No. 6,072,954), is provided with an arc-shaped gear and a cam disposed along a periphery of a movable lens barrel rotated with zooming. With the arc-shaped gear is engaged a drive gear for rotating the movable lens barrel and a gear train for moving a flash projector in a zoom flash device back and forth. There is provided a pair of flat gears engaged with each other in a basic portion of the flash projector. Both outer sides of the flat gears are engaged with a pair of rack gears formed in inner walls of a frame of the flash projector. One of the flat gears is engaged with an output gear of the gear train. Rotation of the movable lens barrel transmitted through the gear train rotates the pair flat gears in opposite directions each other, so that the flash projector is moved back and forth in an optical axis direction through the pair rack gears. Also the cam in the movable lens barrel moves variator lenses in a zoom finder device. Thus, an illuminating angle of the zoom flash device and a viewable field angle of the zoom finder device are changed at the same time in cooperation with the rotation of the lens barrel.  
           [0006]    In the above zoom interlocking mechanism a gear train having a lot of gears is provided between the periphery of the movable lens barrel and the flash projector. Therefore, the zoom interlocking mechanism makes a camera high cost and large size because of an installation space for the gear train. There is a disadvantage in that the interlocking mechanism cannot be applied to a compact and low cost camera.  
         SUMMARY OF THE INVENTION  
         [0007]    An object of the present invention is to provide a zoom interlocking mechanism at low cost which has a simple structure so as to be disposed in small space.  
           [0008]    To achieve the above and other objects, a zoom interlocking mechanism according to the present invention comprises a zoom lens assembly having a zoom lens optical system which moves back and forth in an optical axis direction for varying a focal length thereof system; a zoom finder device holding plural variator lenses which are movable in the optical axis direction; a flash projector installed movably in the optical axis direction; and a cam plate which is disposed horizontally inside a camera, and movable in a direction of perpendicular to the optical axis and horizontal to the camera.  
           [0009]    The cam plate comprises a rectangular plate portion and a rack gear formed integrally with the plate portion. A groove used for interlock with a lens barrel is formed in one surface of the plate portion, and grooves used for interlock with the variator lenses for changing a viewable field angle of the zoom finder device are formed in the other surface. The rack gear extends to a moving direction of the cam plate, and has the same thickness as the plate portion. The rack gear rotates plural flat gears. These flat gears are engaged with other rack gears formed in the flash projector so as to vary a position of the flash projector.  
           [0010]    According to the present invention, it is possible to compose the zoom interlocking mechanism in the simple structure which varies the viewable field angle of the zoom finder device and an illuminating angle of a flashlight in cooperation with zooming. Moreover, because the cam plate can be formed in a thickness of approximately 1 mm, it is possible to dispose the zoom interlocking mechanism in small space. The present invention will help miniaturization of the camera. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The above and other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiment when read in association with the accompanying drawings, which are given by way of illustration only and thus are not limiting the present invention. In the drawings, same reference numerals designate like or corresponding parts throughout the several views, and wherein:  
         [0012]    [0012]FIG. 1A is a front perspective view of a camera showing a condition in which a zoom lens assembly is protruded;  
         [0013]    [0013]FIG. 1B is a front perspective view of a camera showing a condition in which a zoom lens assembly is collapsed;  
         [0014]    [0014]FIG. 2 is an exploded perspective view showing substantial portions of the present invention;  
         [0015]    [0015]FIG. 3 is an explanatory drawing showing a physical relationship between a rack gear of a cam plate and flash rack gears in the most telephoto position;  
         [0016]    [0016]FIG. 4 is a similar drawing to FIG. 3 in the widest-angle position;  
         [0017]    [0017]FIG. 5 is a front view of a flash projector; and  
         [0018]    [0018]FIG. 6 is a perspective view showing main portions of the flash projector. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0019]    Referring to FIG. 1A and 1B, a camera  2  comprises a camera body  3  and a zoom lens assembly  5  (hereinafter referred to as a zoom lens). The camera body  3  has a main body  11  (refer to FIG. 2), and a front cover  4   a  and a rear cover  4   b  which are attached on the main body  11 . To the rear cover  4   b  a lid (not-illustrated) for loading a photo film (not-illustrated) is hinged. There are provided a zoom finder device  6 , a zoom flash device  7 , and a range finding window  8  in an upper side of the camera body  3 . Also in the camera body  3 , there are provided a seesaw-type zoom switch lever  9   a,  a power switch  9   b,  and a release button  10 .  
         [0020]    The zoom lens  5  has a first, second and third movable lens barrels  5   a  to  5   c  and a zoom lens optical system  5   d.  A screw axis and a guide bar (Neither illustrated) extending to an optical axis L direction (refer to FIG. 2) penetrate the first movable lens barrel  5   a.  When the power switch  9   b  is turned on, a zoom motor (not-illustrated) rotates in normal direction so as to rotate the screw axis. The screw axis moves the first to third movable lens barrels  5   a  to  5   c  from a collapsed position shown in FIG. 1B to a widest-angle position which protrudes a little from the camera body  3 . When pressing the zoom switch lever  9   a  to a telephoto side, the zoom motor further rotates in the normal direction so as to protrude the first to third movable lens barrels  5   a  to  5   c  along the optical axis L to the most telephoto position shown in FIG. 1A. When pressing the zoom switch lever  9   a  to a wide-angle side, the zoom motor rotates in the reverse direction so as to retract the first to third movable lens barrels  5   a  to  5   c  to the widest-angle position. When the power switch  9   b  is turned off, the first to third movable lens barrels  5   a  to  5   c  retract to the collapsed position shown in FIG. 1B.  
         [0021]    A gear fixed to an end of the screw axis is engaged with a helicoid gear provided in a periphery of the second movable lens barrel  5   b.  The second movable lens barrel  5   b  is helicoid-connected to the first movable lens barrel  5   a.  The zoom motor rotates the screw axis, the first movable lens barrel  5   a  goes straight along the optical axis L without rotation following a guide of the guide bar. On the other hand, the second movable lens barrel  5   b  advances from the first movable lens barrel  5   a  with rotation.  
         [0022]    The third movable lens barrel  5   c  is connected to the second movable lens barrel  5   b  through a cam mechanism. The third movable lens barrel  5   c  is also connected to an anti-rotation member which extends from the first movable lens barrel  5   a.  When the zoom motor rotates the second movable lens barrel  5   b,  the third movable lens barrel  5   c  advances along the optical axis L from the second movable lens barrel  5   b  without rotation.  
         [0023]    The zoom lens optical system  5   d  is fitted into the third movable lens barrel  5   c.  The zoom lens optical system  5   d  is composed of a front group and a rear group which move together so as to zoom in and out. The zoom lens  5  is a step zoom, and zooms and focuses alternatively during the rotation of the zoom motor. In focusing, the rear group moves relatively to the front group.  
         [0024]    Referring to FIG. 2, a cylindrical opening  12  is formed in the middle of the main body  11  of a camera. In a rear side of the main body  11 , is formed an exposure aperture  13  which decides an exposure field on the photo film disposed behind. The first movable lens barrel  5   a  is movably contained in the opening  12 .  
         [0025]    There is a slit  17  formed in parallel with the optical axis L in an upper side of the main body  11 . Through the slit  17 , an engaging claw  18   a  protrudes to engage with a part of a periphery of the first movable lens barrel  5   a.  On the other hand, on the top of the engaging claw  18   a  a protrusion  18   b  is formed. The protrusion  18   b  is movably fitted into a cam groove  20   a  (refer to FIG. 2) formed in a rear side of a rectangular cam plate  20 .  
         [0026]    The cam plate  20  moves horizontally, namely in a horizontal direction β which is perpendicular to the optical axis direction α, with a guide of a pair of guide ribs  11   a  and  11   b.  The cam plate  20  has a thickness of approximately 1 mm. The groove  20   a,  as shown in FIG. 2, is formed oblique against the optical axis direction α, so that when the first movable lens barrel  5   a  moves in the optical axis direction α the cam plate  20  moves in the horizontal direction β through the connecting member  18 .  
         [0027]    Two cam grooves  20   b  and  20   c  are formed in a front surface of the cam plate  20 . Into the cam grooves  20   b  and  20   c,  two variator lenses  23  and  24  of the zoom finder device  6  are fitted respectively. The zoom finder device  6  comprises an objective lens  25 , prisms  26  and  27 , an eyepiece lens (not-illustrated), and the like besides the variator lenses  23  and  24 . When the cam plate  20  moves in the horizontal direction β and the variator lenses  23  and  24  move along the cam grooves  20   b  and  20   c  respectively, a viewable field angle of the zoom finder device  6  is varied in response to a focal length of the zoom lens  5 .  
         [0028]    In this way the cam groove  20   a  used for interlock with the first movable lens barrel  5   a  is formed in the rear surface of the cam plate  20 , and the cam grooves  20   b  and  20   c  used for interlock with the variator lenses  23  and  24  of the zoom finder device  6  are formed in the front surface, and furthermore the cam plate  20  moves in the horizontal direction β. Therefore, since space of the vertical direction required for interlock between the first movable lens barrel  5   a  and the zoom finder device  6  is just the thickness of the cam plate  20  (approximately 1 mm), it is possible to contribute to miniaturization of the camera  2 .  
         [0029]    The zoom finder device  6  and a passive-type automatic focus unit  29  constitute a finder unit  28  which is installed on the upper side of the main body  11 . In the automatic focus unit  29 , AF light receiving windows  30  and  31  are provided behind the range finding window  8 .  
         [0030]    Referring to FIG. 3, is integrally formed a rack gear  33  having the same thickness as the cam plate  20  and extending to the horizontal direction β from around the middle of one shorter side of the cam plate  20 . The rack gear  33  is engaged with a flat gear  36  which moves a flash projector  35  (refer to FIG. 2 and  6 ) of the zoom flash device  7  back and forth in the optical axis direction α.  
         [0031]    Referring to the FIG. 5, a flat gear  37  having a smaller diameter than the flat gear  36  is formed on the flat gear  36 . The gears  36  and  37  are movably fitted to an axis  39 , and a gear  38  is movably fitted to another axis  40 . The gears  37  and  38  are engaged each other. Also the gears  37  and  38  are engaged with flash rack gears  44  and  45  formed in inner walls of a movable frame  43  of the flash projector  35 , respectively. When the rack gear  33  moves in the horizontal direction β, the movable frame  43  moves back and forth in the optical axis direction α. Thus, a distance between the flash projector  35  and an optical panel, e.g. a Fresnel lens  47 , varies, so that an illuminating angle of a flashlight varies between the most telephoto position shown in FIG. 3 and the widest-angle position shown in FIG. 4. As is well known, the Fresnel lens  47  having a Fresnel surface in its rear side regulates the illuminating angle of the flashlight.  
         [0032]    The axis  39  and  40  are perpendicularly provided to a flash basic portion  41  on which the flash projector  35  is movably fitted. The basic portion  41  is attached to a top of a film winding chamber  11   c  formed in the main body  11  with engagement of a claw. In the gear  36  a part of a cutoff is formed so as not to touch the cam plate  20 .  
         [0033]    Referring to FIG. 6, there are provided ridges  43   a  and  43   b  in outer walls of the movable frame  43 . In both sides of the flash basic portion  41 , guide rails  41   a  and  41   b  for guiding the ridges  43   a  and  43   b  respectively are formed. Thus, the frame  43  is movably fitted onto the flash basic portion  41  along the guide rails  41   a  and  41   b  in the optical axis direction α.  
         [0034]    The flash projector  35  comprises a flash discharge tube  51  for emitting the flashlight, a flashlight reflector  52  for reflecting the flashlight forward, and the movable frame  43  holding the flash discharge tube  51  and the flashlight reflector  52 . The zoom flash device  7  comprises the flash projector  35  and a flash substrate (not-illustrated) on which a flash circuit is formed. The zoom flash device  7  starts charging electricity in turning on the power switch  9   b,  and emits the flashlight automatically along with actuation of a shutter in case of photography in a dark place.  
         [0035]    Now operation of the present invention will be described below. When the power switch lever  9   b  is turned on, the zoom lens  5  moves from the collapsed position shown in FIG. 1B to the widest-angle position. In operating the zoom switch lever  9   a  to the telephoto side, the movable lens barrels  5   a  to  5   d  advance forward along the optical axis L, so that the focal length and also magnification of the zoom finder device  6  vary.  
         [0036]    At the time, the connecting member  18  engaged with the first movable lens barrel  5   a  moves backward in the main body  11  together with the first movable lens barrel  5   a.  The protrusion  18   b  presses an inner wall of the cam groove  20   a  to move the cam plate  20  away from the flash projector  35  in the horizontal direction β (leftward in FIG. 3).  
         [0037]    Operating the zoom switch lever  9   a  to the side, the first to third movable lens barrels  5   a  to  5   c  are retracted from a telephoto position. Accordingly, the magnification of the zoom finder device  6  becomes low.  
         [0038]    The cam grooves  20   b  and  20   c  formed in the front surface of the cam plate  20  move the variator lenses  23  and  24  to their respective positions corresponding to the focal length of the zoom lens  5 , so that the viewable field angle of the zoom finder device  6  is varied. At the same time, the rack gear  33  of the cam plate  22  rotates the gear  36  in a counterclockwise direction. The gear  37  formed integrally with the gear  36  rotates counterclockwise, so the gear  38  engaged with the gear  37  rotates in a clockwise direction. Because the gears  37  and  38  are engaged with the flash rack gears  44  and  45  of the movable frame  43 , as shown in FIG. 4, the movable frame  43  moves toward the Fresnel lens  47  in order to widen the illuminating angle of the flashlight of the zoom flash device  7 .  
         [0039]    When the zoom switch lever  9   a  is operated from the wide-angle side to the telephoto side, on the other hand, the first movable lens barrel  5   a  protrudes forward and the cam plate  20  moves in a direction of the flash projector  35 . Therefore, the magnification of the zoom finder device  6  becomes high, and also the flash projector  35  moves away from the Fresnel lens  47  so that the illuminating angle of the flashlight of the zoom flash device  7  becomes narrow.  
         [0040]    In the above embodiment, the thickness of the cam plate  20  is approximately 1 mm, but the present invention is not limited to it. The thickness of the cam plate  20  maybe thicker or thinner.  
         [0041]    Although the present invention has been described with respect to the preferred embodiment, the present invention is not to be limited to the above embodiment but, on the contrary, various modifications will be possible to those skilled in the art without departing from the scope of claims appended hereto.