Abstract:
A telescopic sight includes a zoom mechanism with which an angle of adjustment of sighting can be enlarged, such that sighting precision of the telescopic sight can be stably maintained, and with which zooming can be performed with a light touch. The telescopic sight includes a zoom ring, an annular gear, a circumferential gear, an intermediate gear and a transmission mechanism. The zoom ring is turnably provided at an outer periphery of a lens barrel of a telescopic sight. The annular gear is provided at an inner periphery face of the zoom ring. The circumferential gear is rotatably provided, concentrically with the annular gear, at an inner periphery of the lens barrel. The intermediate gear is interposed between the annular gear and the circumferential gear and transmit rotation of the annular gear to the circumferential gear.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a telescopic sight which includes a zoom mechanism which stably maintains a sighting alignment of the telescopic sight and which implements zooming with a light touch. 
         [0003]    2. Background Art 
         [0004]    Heretofore, in a zoom mechanism of a telescopic sight, in order to transmit turning of a zoom ring disposed at the outside of a lens barrel to a cam tube disposed inside the lens barrel, a groove aperture with a circular arc form has been formed in the lens barrel. This groove aperture is opened in the circular arc form through a broad angle about an optical axis of the telescopic sight (for example, an angle of around 300°). Moreover, this groove aperture is disposed between a zoom lens and an eyepiece lens, and arranged in a direction intersecting the optical axis. Hence, there has been a problem in that the strength at locations of the groove aperture is low when external forces, such as impacts and the like, act on the lens barrel. 
         [0005]    A telescopic sight for solving this previous problem is equipped with a zoom mechanism which does not require the broad-angle groove aperture. This sight has been proposed by the present inventor, as shown in  FIGS. 6 and 7  (see Japanese Publication No. JP 7281101). In such a telescopic sight  51 , a zoom ring  54  is mounted at a tubular body  53  which is joined to a lens barrel  52 , and the zoom ring  54  is made rotatable with respect to the lens barrel  52 . An annular gear  55  is provided at an inner periphery face of the zoom ring  54 , and a circumferential gear  58  is provided at an outer periphery face of a cam tube  56 , which is rotatably provided inside the lens barrel  52 . Meanwhile, an intermediate gear  57  is rotatably provided in a small hole  59  in the tubular body  53 . This intermediate gear  57  is interposed between the annular gear  55  and the circumferential gear  58 . Thus, turning of the zoom ring  54  is transmitted via the intermediate gear  57  to the cam tube  56 , so as to implement zooming of the telescopic sight  51 . 
       SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
       [0006]    The telescopic sight  51 , also described in Japanese Publication No. JP 7281101, includes an alignment adjustment mechanism  60 , which inclines the cam tube  56  to adjust alignment. Consequently, when the cam tube  56  is inclined at a time of alignment adjustment, meshing between the intermediate gear  57  and the circumferential gear  58  provided at the outer periphery face of the cam tube  56  is altered. Therefore, if an inclination angle of the cam tube  56  is set to be large, the meshing between the circumferential gear  58  and the intermediate gear  57  may become harsh or disengage, and it may not be possible to perform zooming with a light touch. Thus, there has been a problem in that making an alignment adjustment angle large is difficult. 
         [0007]    Accordingly, the present invention provides a telescopic sight including a zoom mechanism which both enables a large alignment adjustment angle, such that alignment precision of the telescopic sight can be stably maintained, and implements zooming with a light touch. 
       Means for Solving the Problem 
       [0008]    In order to solve the problem described above, the present invention provides a telescopic sight with a zoom mechanism including: a zoom ring which is rotatably disposed at an outer periphery of a lens barrel of the telescopic sight; an annular gear which is disposed at an inner periphery face of the zoom ring; a circumferential gear which is rotatably disposed, concentrically with the annular gear, at an inner periphery of the lens barrel; an intermediate gear which is interposed between the annular gear and the circumferential gear and provided so as to transmit rotation of the annular gear to the circumferential gear; and a transmission mechanism which transmits rotation of the circumferential gear to a cam tube which is rotatably disposed in the lens barrel. 
         [0009]    The present invention further provides that the transmission mechanism includes a groove portion provided at the cam tube and a protrusion portion provided at the circumferential gear, and the protrusion portion and the groove portion are displaceably engaged. Further still, the telescopic sight of the present invention provides an alignment adjustment mechanism which inclines the cam tube at least one of vertically and horizontally for alignment. Further yet, the present invention further provides a telescopic sight, wherein the alignment adjustment mechanism includes: an inner tube which is disposed so as to rotatably support the cam tube; a curved ring which is disposed at an outer periphery of the inner tube; and a curved ring support member which is disposed so as to support the curved ring to be inclinable in vertical and horizontal directions. 
         [0010]    According to a telescopic sight relating to the present invention, because the telescopic sight includes a zoom mechanism having a zoom ring which is rotatably disposed at an outer periphery of a lens barrel of the telescopic sight, an annular gear which is disposed at an inner periphery face of the zoom ring, a circumferential gear which is rotatably disposed, concentrically with the annular gear, at an inner periphery of the lens barrel, an intermediate gear which is interposed between the annular gear and the circumferential gear and provided so as to transmit rotation of the annular gear to the circumferential gear, and a transmission mechanism which transmits rotation of the circumferential gear to a cam tube which is rotatably disposed in the lens barrel, the annular gear and the circumferential gear are concentrically provided. As a result of this construction, the meshing between the annular gear and the intermediate gear and between the intermediate gear and the circumferential gear can be kept substantially constant. Thus, the zoom ring can be operated and the turning transmitted to the circumferential gear with a substantially constant torque. Furthermore, because turning of the circumferential gear is transmitted to the cam tube by the transmission mechanism, the cam tube can be consistently turned, and zooming can be implemented lightly and consistently. 
         [0011]    Further, with the present invention, when the transmission mechanism includes a groove portion provided at the cam tube and a protrusion portion provided at the circumferential gear, and the protrusion portion and the groove portion are displaceably engaged, even if the cam tube is greatly inclined for alignment adjustment, the groove portion provided at the cam tube and the protrusion portion provided at the circumferential gear are movably engaged. With such construction, turning of the circumferential gear is consistently transmitted to the cam tube and zooming can be implemented. 
         [0012]    Further, with the present invention, the alignment adjustment mechanism, which inclines the cam tube at least one of vertically and horizontally for adjusting alignment, provides alignment precision of the telescopic sight which is stably maintained. 
         [0013]    Further, with the present invention, when the alignment adjustment mechanism includes an inner tube which is disposed so as to rotatably support the cam tube, a curved ring which is disposed at an outer periphery of the inner tube, and a curved ring support member which is disposed so as to support the curved ring to be inclinable in vertical and horizontal directions, the cam tube is supported by the curved ring and the curved ring support member. The cam tube can be greatly inclined, and it is possible to broaden an alignment adjustment range from close range to long range. 
         [0014]    These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a partial vertical sectional side view showing the zoom mechanism of an embodiment of a telescopic sight of the present invention; 
           [0016]      FIG. 2  is a partial cutaway perspective cross-sectional view showing the principal components of the embodiment of the present invention; 
           [0017]      FIG. 3  is a partial cutaway perspective cross-sectional view showing details of the interior portions of the embodiment of the present invention; 
           [0018]      FIG. 4  is a partial cutaway cross-sectional perspective view showing the embodiment of the present invention; 
           [0019]      FIG. 5  is a cross-sectional view taken along line A-A of  FIG. 1 ; 
           [0020]      FIG. 6  is a partial vertical cross-sectional side view showing a zoom mechanism of an embodiment of a previous telescopic sight; and 
           [0021]      FIG. 7  is a cross-sectional view of the previous telescopic sight taken along line B-B of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0022]    The present invention will be described with reference to the embodiment shown in  FIGS. 1 to 5 . 
         [0023]    Reference numeral  1  in the drawings refers to a telescopic sight relating to the present invention. A zoom mechanism of the telescopic sight  1  is structured with a zoom ring  5 , an annular gear  5 A, a circumferential gear  6 , an intermediate gear  7  and a transmission mechanism  13 . The zoom ring  5  is rotatably provided at an outer periphery of a lens barrel  2 . The annular gear  5 A is provided at an inner periphery face of the zoom ring  5 . The circumferential gear  6  is rotatably provided at an inner periphery of the lens barrel  2 , concentrically with the annular gear  5 A. The intermediate gear  7  is interposed between the annular gear  5 A and the circumferential gear  6 , and is provided so as to transmit turning of the annular gear  5 A to the circumferential gear  6 . The transmission mechanism  13  transmits rotation of the circumferential gear  6 , which is rotatably provided inside the lens barrel  2 , to a cam tube  9 , which is rotatably provided inside the lens barrel  2 . 
         [0024]    As shown in  FIGS. 1 and 2 , the lens barrel  2  is structured by a lens barrel main body  2 A and a tube body  2 B, which is joined to the lens barrel main body  2 A. A substantially cruciform small hole  3  is formed in the tube body  2 B. An axis of the intermediate gear  7  is set in parallel with an optical axis N of the telescopic sight  1 , and the intermediate gear  7  is disposed transversely to the small hole  3 , to be capable of rotating. Tooth portions of the intermediate gear  7  are structured such that portions thereof protrude slightly from the outer peripheral face and inner peripheral face of the tube body  2 B. 
         [0025]    In the embodiment of the drawings, the zoom ring  5  is rotatably provided at the outer periphery of the lens barrel  2 . The annular gear  5 A is provided to threadingly engage with a thread portion of the inner periphery of the zoom ring  5 , and is fixed to the zoom ring  5  by a gear clasp  5 B. The annular gear  5 A meshes with the intermediate gear  7  disposed at the tube body  2 B, and is structured such that the intermediate gear  7  rotates when the zoom ring  5  is operated to turn. 
         [0026]    As shown in  FIGS. 1 and 2 , the circumferential gear  6  is structured by a gear portion  6 A and a sliding surface  6 B, which extends in the direction of optical axis N, and an inwardly extending protrusion portion  6 C, which protrudes to an inner periphery side. The sliding surface  6 B slides against a sliding surface  2 C, which is provided concentrically with the annular gear  5 A at the inner periphery of the tube body  2 B. The circumferential gear  6  is provided to be concentric with the annular gear  5 A and rotatable with respect to the tube body  2 B. The circumferential gear  6  meshes with the intermediate gear  7  disposed at the tube body  2 B, and is structured such that turning of the annular gear  5 A is transmitted via the intermediate gear  7  to the circumferential gear  6 . With this structure, the annular gear  5 A and the circumferential gear  6  can be turned in a constantly concentric state, and meshing of the annular gear  5 A with the intermediate gear  7  and of the intermediate gear  7  with the circumferential gear  6  can be kept substantially constant. 
         [0027]    As shown in  FIGS. 1 to 4  inside the lens barrel main body  2 A, the cam tube  9  is rotatably provided to cover an inner tube  8 , which is disposed inside the lens barrel main body  2 A. A groove portion  9 C is formed in the cam tube  9 , and the protrusion portion  6 C provided at the circumferential gear  6  displaceably engages with this groove portion  9 C, structuring the transmission mechanism  13  which transmits turning of the circumferential gear  6  to the cam tube  9 . With such a structure, even when the cam tube  9  is inclined for alignment adjustment, engagement of the protrusion portion  6 C with the groove portion  9 C is maintained, and turning of the circumferential gear  6  is transmitted to the cam tube  9 . 
         [0028]    Note that the transmission mechanism is not limited to the embodiment in the drawings. It is also possible to form a structure in which a protrusion portion is provided at the outer periphery of the cam tube  9 , a groove portion is provided at an inner periphery of the circumferential gear  6 , with the protrusion portion and groove portion displaceably engaged. 
         [0029]    As best seen in  FIG. 3  in a circumferential face of the cam tube  9 , two helical-form cam holes  9 A and  9 B are formed along angles which are quite sharply inclined with respect to the optical axis N. In the inner tube  8 , a guide hole  8 A is formed in parallel with the optical axis N and is provided to enable movement of zoom lenses  10 A and  10 B via support pieces  11 A and  11 B thereof. A screw  12 A of the support piece  11 A passes through a region at which the cam hole  9 A and the guide hole  8 A overlap, such that the zoom lens  10 A moves in accordance with movement of the overlapping portion of the cam hole  9 A and the guide hole  8 A when the cam tube  9  is turned. Similarly, a screw  12 B of the support piece  11 B passes through a portion at which the cam hole  9 B and the guide hole  8 A overlap. 
         [0030]    With the zoom mechanism of the structure described above, turning of the zoom ring  5  is transmitted to the circumferential gear  6  via the intermediate gear  7 , and turning of the circumferential gear  6  is transmitted to the cam tube  9  via the transmission mechanism  13 . Turning of the cam tube  9  is then converted, via the screws  12 A and  12 B and the support pieces  11 A and  11 B, to movement of the zoom lenses  10 A and  10 B in parallel with the optical axis N. Thus, zooming of the telescopic sight  1  is operated. In addition, because there is no limit on a turning angle of the zoom ring  5 , it is possible to form the cam holes  9 A and  9 B in the cam tube  9  at the angles which are sharply inclined with respect to the optical axis N, and it is possible to lightly turn the zoom ring  5  with a small torque. 
         [0031]    As shown in  FIGS. 1 ,  4  and  5 , an alignment adjustment mechanism  20  is provided substantially at the middle of the lens barrel main body  2 A. The alignment adjustment mechanism  20  is for, when the telescopic sight  1  is mounted at a gun barrel, alignment adjustments between a direction of the gun barrel and the optical axis N of the telescopic sight  1  for actual shooting conditions. 
         [0032]    In the embodiment of the drawings, the alignment adjustment mechanism  20  includes the inner tube  8  and an inner tube support mechanism  26 . The inner tube  8  is provided so as to rotatably support the cam tube  9 . The inner tube support mechanism  26  is structured by a curved ring  24 , which is provided near the end of and at an outer periphery of the inner tube  8 , and a curved ring support member  25 , which is provided at the tube body  2 B so as to support the curved ring  24  to be inclinable in up-down and left-right directions. The curved ring  24  is formed in the shape of a hollow sphere which has been truncated, with two parallel flat faces sandwiching the center of the sphere, and is provided at an end portion of the inner tube  8  at a side thereof at which an eyepiece section  4  is disposed. The curved ring support member  25  is structured by a partial ring  25 A, which is fixed to the tube body  2 B, and a holding portion  25 B, which is provided to threadingly engage with an inner periphery of the partial ring  25 A. Thus, the curved ring  24  is retained by the partial ring  25 A and the holding portion  25 B. The inner tube support mechanism  26  is preferably provided in a vicinity of the transmission mechanism  13 , such that displacements of the inner tube  8  at the transmission mechanism  13  can be made small. 
         [0033]    The alignment adjustment mechanism  20  is further structured by a horizontal alignment adjustment ring  21 , which adjusts a declination angle, and a vertical alignment adjustment ring  22 , which can adjust an elevation angle. A coil spring  23  is provided at a position opposing the horizontal alignment adjustment ring  21  and the vertical alignment adjustment ring  22  across the optical axis N. A support tube  16  with an intermediate lens  15  is joined to an end portion of the inner tube  8  at a side thereof at which an object lens  14  is disposed. The horizontal alignment adjustment ring  21  and the vertical alignment adjustment ring  22  can be rotated to push the support tube  16  for control, such that the inner tube  8  can be inclined to left or right (horizontally) and to up or down (vertically) about the inner tube support mechanism  26 . By inclination of the inner tube  8 , the zoom lenses  10 A and  10 B provided at the inner tube  8  and the cam tube  9  are inclined, and the alignment of the telescopic sight can be adjusted. 
         [0034]    It will become apparent to those skilled in the art that various modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.