Abstract:
An image pickup apparatus with an AF sensor unit fixed thereto promptly with high precision by a parallax adjustment method. The image pickup apparatus with the AF sensor has a stationary cylinder. The stationary cylinder constitutes an image pickup lens barrel with a first axis and a second axis that are perpendicular to an optical axis of the lens barrel and are perpendicular to each other. An AF sensor holder is configured to hold said AF sensor. An AF sensor holder-mounting unit is mounted on the stationary cylinder through a first axis rotation-adjusting mechanism rotatably with respect to the first axis, and configured to support said AF sensor holder through a second axis rotation-adjusting mechanism rotatably with respect to the second axis. The first axis rotation-adjusting mechanism and the second axis rotation-adjusting mechanism are directed in the same direction at operation sides thereof, respectively.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image pickup apparatus with an AF sensor unit, and more particularly, to an image pickup apparatus with a man body having an AF sensor unit fixed thereto promptly with high precision by a parallax adjustment method. 
     2. Description of the Related Art 
     There has been developed an image pickup apparatus that has an AF sensor unit outside its image pickup optical system and is designed to measure the distance from a subject with the use of the AF sensor unit. 
     The AF sensor unit used in this manner may employ a passive AF method of performing measurement based on a triangular ranging principle, using two sets of optical systems each including a lens and a distance measuring image pickup element, for example. 
     Such an AF sensor unit needs to be fixed to an image pickup apparatus while being tilted at a predetermined angle in the optical axis direction of the image pickup lens such that the orientations of the two sets of optical systems correspond to the center of a subject image formed by picking up an image of the center of the subject located at a specific distance. Therefore, an AF sensor unit is normally mounted on the main body of an image pickup apparatus by performing a positioning and securing process with high precision, or by a so-called parallax adjustment method (see Japanese Laid-Open Patent Publication (Kokai) No. 2001-208536, for example). 
     A description will now be made of a method of mounting a conventional AF sensor unit on the main body of an image pickup apparatus by implementing a parallax adjustment method through an example case where an AF sensor unit of a passive AF type is fixed to a video camera, with reference to  FIGS. 4 and 5 . 
     In  FIGS. 4 and 5 , an AF sensor unit  1001  has built-in two sets of a lens and an AF sensor (AF-service image pickup elements). This AF sensor unit  1001  has a flexible board  1009  extending from the main body of the AF sensor unit  1001  for transmitting electric signals from the built-in AF sensor to a predetermined electric circuit ( FIG. 5 ). 
     A lens unit  1004  of the video camera has an AF sensor holder-mounting unit  1002  for retaining the AF sensor unit  1001  in a holding manner screwed thereto with an AF sensor holder-mounting unit-fixing screw  1003 . 
     This AF sensor unit  1001  has two adjustment holes  1010  therein. The AF sensor holder-mounting unit  1002  has a stopper boss  1008  protruding from a bottom portion thereof. The stopper boss  1008  is configured to be fitted into a concave portion (not shown) formed in the bottom portion of the AF sensor unit  1001 , and serve as a stopper part when the attitude of the AF sensor unit  1001  is adjusted. 
     This AF sensor unit  1001  is to be subjected to a parallax adjustment method, described later, of performing the movement in adjustment directions (X, Y)  1007  with the use of adjustment tool pins  1005 , each of which has a tapered end portion, protruding from a special-purpose adjustment tool. The AF sensor unit  1001  subjected to the parallax adjustment method is bonded and fixed to the AF sensor holder-mounting unit  1002  with a UV curing adhesive agent  1006  (at two spots). 
     A description will now be made of the parallax adjustment method for the AF sensor unit  1001 . 
     According to this parallax adjustment method, the AF sensor unit  1001  is first placed on the AF sensor holder-mounting unit  1002 . On this occasion, into the concave portion (not shown) formed on the bottom portion of the AF sensor unit  1001  is inserted the stopper boss  1008  of the AF sensor holder-mounting unit  1002 , which enables the AF sensor unit  1001  to be supported by a pivot bearing and is set in a position-variable state. 
     In this state, the adjustment tool pins  1005 , each of which has the tapered end portion, protruding from the special-purpose adjustment tool are inserted into the two adjustment holes  1010 , which allows a predetermined downward load to be applied to the AF sensor unit  1001 . 
     The adjustment tool pins  1005  are configured to pivotally move in the adjustment directions (X, Y)  1007  when a predetermined tab of the special-purpose adjustment tool (not shown) is rotatably moved. This operation enables the AF sensor unit  1001  to be pivotally moved about the stopper boss  1008  with its position adjusted. 
     Moreover, as a method of measuring the fixed angle with respect to the optical axis direction of the image pickup lens of the AF sensor unit  1001 , there is normally used an output waveform measurement method of measuring the waveform of the AF sensor output projected on the chart with a chart placed at a predetermined distance from the image pickup lens. 
     After the AF sensor unit  1001  has thus been positioned at a predetermined fixed angle with the use of the special-purpose adjustment tool, a UV curing adhesive agent  1006  is applied to the two spots shown in the drawing, and then the UV curing adhesive agent  1006  is cured by UV rays emitted onto the UV curing adhesive agent  1006  for a certain period of time, before the adjustment tool pins  1005  are pulled out. 
     As described above, the AF sensor unit  1001  is positioned and fixed to the AF sensor holder-mounting unit  1002  of the lens unit  1004  in a desired position. 
     By the above parallax adjustment method, however, the AF sensor unit  1001  together with the AF sensor holder-mounting unit  1002  unfavorably bends downward when the adjustment tool pins  1005  are inserted into the two adjustment holes  1010  with the predetermined downward load applied to the AF sensor unit  1001 . 
     Therefore, when the load of the adjustment tool pins  1005  is removed after the parallax adjustment (after the adjustment tool pins  1005  have been pulled out), the AF sensor holder-mounting unit  1002  and the like are elastically returned, thereby causing the AF sensor unit  1001  to move from the position determined by the parallax adjustment method, which provides an error. Also, the error caused by the movement from the position determined by the parallax adjustment makes it difficult to mount the AF sensor unit  1001  on the main body of the image pickup apparatus with high precision. 
     Also, the AF sensor unit  1001  is fixed at two spots with the UV curing adhesive agent  1006  after the parallax adjustment; accordingly, the AF sensor unit  1001  is affected by the adhesive curing stress, temperature changes, drops, and vibrations, thereby providing a deviation in the fixed position of the AF sensor unit  1001 . This makes it difficult to position and secure the AF sensor unit  1001  with high precision. 
     Further, the time consumed by processes of the parallax adjustment method disadvantageously becomes longer, because of the adhesion curing time for the UV curing adhesive agent  1006 . 
     SUMMARY OF THE INVENTION 
     The present invention provides an image pickup apparatus with an AF sensor unit fixed thereto promptly with high precision by a parallax adjustment method. 
     In an aspect of the present invention, there is provided an image pickup apparatus with an AF sensor unit, having a stationary cylinder constituting an image pickup lens barrel with a first axis and a second axis that are perpendicular to an optical axis of the lens barrel and are perpendicular to each other, the image pickup apparatus comprising: an AF sensor holder configured to hold the AF sensor; and an AF sensor holder-mounting unit mounted on the stationary cylinder through a first axis rotation-adjusting mechanism rotatably with respect to the first axis, and configured to support the AF sensor holder through a second axis rotation-adjusting mechanism rotatably with respect to the second axis, wherein the first axis rotation-adjusting mechanism and the second axis rotation-adjusting mechanism face in the same direction at operation sides thereof, respectively. 
     According to the invention, the AF sensor holder-mounting unit is mounted on the stationary cylinder constituting the image pickup lens barrel through the first axis rotation-adjusting mechanism rotatably with respect to the first axis, and supports the AF sensor holder holding the AF sensor through the second axis rotation-adjusting mechanism rotatably with respect to the second axis, and the first axis rotation-adjusting mechanism and the second axis rotation-adjusting mechanism face in the same direction at operation sides thereof, respectively. Accordingly, it is possible to provide an image pickup apparatus with a main body having an AF sensor unit fixed thereto promptly with high precision by a parallax adjustment method. 
     Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a principal part of an image pickup apparatus according to an embodiment of the present invention. 
         FIG. 2A  is a cross-sectional view of the principal part of the image pickup apparatus, taken along the line A-A′ in  FIG. 1 , and  FIG. 2B  is an enlarged cross-sectional view of the principal part shown in  FIG. 2A . 
         FIG. 3  is an exploded perspective view of the image pickup apparatus of  FIG. 1 . 
         FIG. 4  is a perspective view of a principal part of a conventional image pickup apparatus with an AF sensor unit mounted thereon. 
         FIG. 5  is a perspective view of the principal part of the conventional image pickup apparatus with the AF sensor unit detached therefrom. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present invention will now be described in detail with reference to  FIGS. 1-3   
       FIG. 1  is a perspective view of a principal part of an image pickup apparatus according to an embodiment of the present invention,  FIG. 2A  is a cross-sectional view of the principal part of the image pickup apparatus, taken along the line A-A′ in  FIG. 1 , and  FIG. 2B  is an enlarged cross-sectional view of the principal part shown in  FIG. 2A . 
     In  FIG. 1 , a video camera as the image pickup apparatus according to the embodiment of the present invention includes an image pickup lens unit  2  (a stationary cylinder constituting an image pickup lens barrel) with and an AF sensor unit  1  mounted on an AF sensor holder-mounting unit  8 . 
     In this AF sensor unit  1 , the AF sensor holder-mounting unit  8  has a spectacle lens  9  mounted on through a bonding and securing process ( FIG. 3 ). It should be noted that the spectacle lens  9  and the AF sensor holder-mounting unit  8  are manufactured with predetermined respective precisions, and hence can be assembled without any special positioning. 
     In  FIG. 3 , an AF sensor holder  12  is made of a box-like resin component, and an AF sensor  10  is mounted on the AF sensor holder-mounting unit  12  at a predetermined location through a bonding and securing process. In this case also, it is not necessary to perform any positioning either. 
     This AF sensor  10  is mounted on the flexible board  11 . It should be noted that the flexible board  11  with the AF sensor  10  is connected to a circuit board of the camera main body. 
     The AF sensor holder  12  having the AF sensor  10  mounted thereon as described above is mounted on the AF sensor holder-mounting unit  8  through a bonding and securing process via an AF sensor washer  13  for focus adjustment. 
     The mounting of the AF sensor  10  is adjusted by the above described waveform measurement method implemented for the AF sensor  10 . On this occasion, several kinds of focus adjustment AF sensor washers  13  having various thicknesses are prepared previously, and one of the AF sensor washers  13  that can achieve the sharpest focus is used. 
     A description will now be made of a process of securing the AF sensor unit  1  to the lens unit  2 . 
     First, the AF sensor unit  1  is mounted on an AF sensor unit-mounting seat  14 . 
     To this end, the AF sensor holder-mounting unit  8  is fastened to the AF sensor unit-mounting seat  14  by inserting a rotary shaft boss  14   c  of the AF sensor unit-mounting seat  14  to a shaft hole  8   b  of the AF sensor holder-mounting unit  8 , and threading a vertical axis rotation-fixing screw  6  into a screw hole  14   d , with the fixation screw  6  inserted through a washer  7 . In the following description, the vertical axis is equivalent to the “X-axis” in  FIG. 1 , and the “second axis”. 
     Further, with the AF sensor holder-mounting unit  8  being fastened to the AF sensor unit-mounting seat  14 , a vertical axis rotation-adjusting eccentric pin  3  is inserted into an elongated hole  8   a  disposed through a protruding piece extending from the AF sensor holder-mounting unit  8 , and a leading end portion of the vertical axis rotation-adjusting eccentric pin  3  is press-fitted into an insertion hole  14   e  disposed in the AF sensor unit-mounting seat  14 . 
     A rotation center axis of rotation of the vertical axis rotation-adjusting eccentric pin  3  and a rotation center axis of the AF sensor holder-mounting unit  8  are perpendicular to each other. Further, a head  3   a  of the vertical axis rotation-adjusting eccentric pin  3  is oval in cross-sectional shape, or more specifically, is ellipsoidal, as shown in  FIG. 3 . A shaft of the vertical axis rotation-adjusting eccentric pin  3  is fixed to the head  3   a  at one focal point of the ellipsoid. Therefore, rotational movement of the vertical axis rotation-adjusting eccentric pin  3  allows the side face portion on the curved surface of the head  3   a  to slide along a wall portion defining the elongated hole  8   a , which enables the AF sensor unit  1  to be stably positioned. In this manner, the head  3   a  and the elongated hole  8   a  constitute an eccentric cam mechanism as “the second axis rotation-adjusting mechanism”. 
     An operator rotatably moving the vertical axis rotation-adjusting eccentric pin  3  with a driver or the like causes the side face portion of the head  3   a  of the vertical axis rotation-adjusting eccentric pin  3  to push the wall portion defining the elongated hole  8   a  of the AF sensor holder-mounting unit  8 , and adjust a vertical axis rotation tilt θ 2  of the AF sensor unit  1 . 
     The vertical axis rotation-adjusting eccentric pin  3  and the insertion hole  14   e  are configured to be slightly press-fitted into each other. Once it is inserted into the insertion hole  14   e , the vertical axis rotation-adjusting eccentric pin  3  press-fitted into the insertion hole  14   e  in this manner is not easily pulled out of the insertion hole  14   e , but is held in the insertion hole  14   e  in a state where the eccentric pin  3  can be rotatably moved in the rotation direction with a small force. 
     A description will now be made of a process of mounting the AF sensor unit-mounting seat  14 , having the AF sensor unit  1  mounted thereon, on the image pickup lens unit  2 . 
     The AF sensor unit-mounting seat  14  is pivotably mounted on the lens unit  2  at an intermediate location on a side face of a first supporting plate portion  24  with a horizontal axis rotation-fixing screw  5  so as to rotatably move about the horizontal axis. In the following descriptions, the horizontal axis is equivalent to the “Y-axis” in  FIG. 1 , and the “first axis”. 
     As shown in  FIG. 3 , the AF sensor unit-mounting seat  14  is placed on a boss  2   b  protruding from an upper portion of the lens unit  2 , with the boss  2   b  being inserted to a fitting hole  14   b  disposed on the bottom portion of the AF sensor unit-mounting seat  14 . The horizontal axis rotation-fixing screw  5  inserted through a washer  7  is threadably secured into a screw hole  2   c  of the stationary cylinder of the lens unit  2  via the fitting hole  14   b . Further, a horizontal axis rotation-adjusting eccentric pin  4  is inserted into an elongated hole  14   a  disposed in the base end portion of the bottom portion of the AF sensor unit-mounting seat  14 , and is press-fitted into an insertion hole  2   a  disposed in the lens unit  2 . On this occasion, the horizontal axis rotation-adjusting eccentric pin  4  and the insertion hole  2   a  are configured to slightly press-fitted into each other. With this arrangement, once it is inserted into the insertion hole  2   a , the horizontal axis rotation-adjusting eccentric pin  4  is not easily pulled out of the insertion hole  2   a , but is held in the insertion hole  2   a  in a state where the eccentric pin  4  can be rotatably moved in the rotation direction with a small force. 
     A rotation center axis of the horizontal axis rotation-adjusting eccentric pin  4  and the rotation center axis of the AF sensor unit-mounting seat  14  are parallel to each other. Further, a head  4   a  of the horizontal axis rotation-adjusting eccentric pin  4  is oval in cross-sectional shape, or more specifically, is ellipsoidal, as shown in  FIG. 3 . A shaft of the horizontal axis rotation-adjusting eccentric pin  4  is fixed to the head  4   a  at one focal point of the ellipsoid. Therefore, rotational movement of the horizontal axis rotation-adjusting eccentric pin  4  allows the side face portion on the curved surface of the head  4   a  to slide along a wall portion defining the elongated hole  14   a , which enables the AF sensor unit  1  to be stably positioned. In this manner, the head  4   a  and the elongated hole  14   a  constitute an eccentric cam mechanism as “the first axis rotation-adjusting mechanism”. 
     An operator rotatably moving the horizontal axis rotation-adjusting eccentric pin  4  with a driver or the like causes the side face portion of the head  4   a  of the horizontal axis rotation-adjusting eccentric pin  4  to push the wall portion defining the elongated hole  14   a  of the AF sensor unit holder-mounting seat  14 , and adjust a horizontal axis rotation tilt θ 1  of the AF sensor unit  1 . 
     This image pickup apparatus includes the AF sensor unit-mounting seat  14  for adjusting the horizontal axis rotation and the AF sensor holder-mounting unit  8  for adjusting the vertical axis rotation, serving as the structure for adjusting the attitude of the pickup apparatus with respect to the horizontal axis rotation direction and the vertical axis rotation direction. 
     This AF sensor unit-mounting seat  14  includes the first supporting plate portion  24  with a substantially elongated plate-like shape for adjusting the horizontal axis rotation, and a second supporting plate portion  25  with a substantially rectangular plate-like shape extending orthogonally from one end of the first supporting plate portion  24 , which causes the AF sensor unit-mounting seat  14  as a whole to have a substantially L-like shape. 
     The first supporting plate portion  24  has the rotation supporting fitting hole  14   b  at a substantially center portion thereof in its longitudinal direction, and further has the elongated hole  14   a  disposed in the end portion on the opposite side of the second supporting plate portion  25 . 
     This first supporting plate portion  24  is supported so as to rotatably move in a very small angle with respect to the lens unit  2  by the horizontal axis rotation-fixing screw  5  pivotably fitted into the fitting hole  14   b.    
     The second supporting plate portion  25  of the AF sensor unit-mounting seat  14  has mounted thereon the AF sensor holder-mounting unit  8  for adjusting the vertical axis rotation. 
     The second supporting plate portion  25  has the rotary shaft boss  14   c  of a cylindrical large thickness shape protruding at a base end portion thereof (on a side of the first supporting plate portion  24 ). The rotary shaft boss  14   c  has the screw hole  14   d  disposed through its center portion along the rotation center axis. Further, the second supporting plate portion  25  has the insertion hole  14   e , to which the vertical axis rotation-adjusting eccentric pin  3  is to be inserted, disposed at the end face portion of the free end thereof. 
     The AF sensor holder-mounting unit  8  also includes a second side plate portion  28  mounted on the second supporting plate portion  25  of the AF sensor unit-mounting seat  14  and disposed so as to receive the AF sensor unit  1  while overlapping with the second supporting plate portion  25  in the AF sensor unit-mounting seat  14 , and a first side plate portion  29  orthogonally extending from one end portion of the second side plate portion  28  and facing the end face of the free end of the second supporting plate portion  25 . 
     The second side plate portion  28  of the AF sensor holder-mounting unit  8  has the shaft hole  8   b  disposed on the end portion thereof on an opposite side of the first side plate portion  29 . 
     With the rotary shaft boss  14   c  rotatably inserted into this shaft hole  8   b , the vertical axis rotation-fixing screw  6  is threaded into the screw hole  14   d  through the washer  7 , and then the first side plate portion  28  rotatably supported on the AF sensor unit-mounting seat  14  about the rotation center axis of the boss  14   c . With this arrangement, the AF sensor holder-mounting unit  8  is supported on the second supporting plate portion  25  of the AF sensor unit-mounting seat  14 , so as to rotatably move in a very small angle about the rotary shaft boss  14   c.    
     The above-mentioned elongated hole  8   a  is disposed on the second side plate portion  29  of the AF sensor holder-mounting unit  8 . 
     A description will now be made of the parallax adjustment method implemented for the AF sensor unit  1  in the above-mentioned structure. 
     According to this parallax adjustment method, the operator first rotatably moves the horizontal axis rotation-adjusting eccentric pin  4  to adjust the horizontal axis rotation tilt  81  of the AF sensor unit  1 . 
     The operator then rotatably moves the vertical axis rotation-adjusting eccentric pin  3  to adjust the vertical axis rotation tilt  82  of the AF sensor unit  1 . 
     Lastly, the operator applies a screw locking adhesive agent to respective head portions of the vertical axis rotation-adjusting eccentric pin  3 , the horizontal axis rotation-adjusting eccentric pin  4 , the horizontal axis rotation-fixing screw  5 , and the vertical axis rotation-fixing screw  6  to prevent the rotation deviation due to the dropping caused by vibrations. 
     As described above, the AF sensor unit  1  is mounted on the lens unit  2  with the attitude adjusted with respect to the horizontal axis rotation direction and the vertical axis rotation direction. 
     According to this embodiment, rotatably moving the horizontal axis rotation-adjusting eccentric pin  4  enables the AF sensor unit  1  including the AF sensor unit-mounting seat  14  and the AF sensor holder-mounting unit  8  to be rotatably moved to adjust the horizontal axis rotation tilt θ 1 . 
     Also, according to this embodiment, rotatably moving the vertical axis rotation-adjusting eccentric pin  3  enables the AF sensor unit  1  including the AF sensor holder-mounting unit  8  to be rotatably moved to adjust the vertical axis rotation tilt θ 2 . 
     According to this embodiment, after the AF sensor unit  1  has been positioned, the AF sensor unit  1  moves neither in the vertical axis rotation direction nor in the horizontal axis rotation direction, so long as the vertical axis rotation-adjusting eccentric pin  3  or the horizontal axis rotation-adjusting eccentric pin  4  is rotatably moved. This eliminates the need for waiting for curing of the screw locking adhesive agent after the application of the adhesive agent, thereby preventing the manufacturing time from increasing. 
     According to this embodiment, the vertical axis rotation-adjusting eccentric pin  3 , the horizontal axis rotation-adjusting eccentric pin  4 , the horizontal axis rotation-fixing screw  5 , and the vertical axis rotation-fixing screw  6  have the respective rotation center axes on the same plane (the A-A′ cross-sectional plane), as shown in  FIG. 2A . This miniaturizes the parallax adjustment mechanism, and also reduces a work space for adjustment tools such as a driver used for the vertical axis rotation adjustment and the horizontal axis rotation adjustment of the AF sensor unit  1 . 
     According to this embodiment, the vertical axis rotation adjustment and the horizontal axis rotation adjustment of the AF sensor unit  1  can be realized by rotatably moving the vertical axis rotation-adjusting eccentric pin  3  and the horizontal axis rotation-adjusting eccentric pin  4 , which eliminates the adhesive curing stress, compared with a case in which the bonding is carried out with the use of an adhesive agent, and reduces the positional deviation of the AF sensor unit  1  due to temperature changes, dropping, or vibrations, and also shortens the time for UV radiation bonding in the assembling process. 
     According to this embodiment, the load added to the time of adjustment is imposed on the mounting seat and the stationary cylinder of the AF sensor unit  1  having high rigidity, thereby reducing the deflection at the time of adjustment, which enables the AF sensor unit  1  to be positioned with high precision. This prevents a positional deviation of the AF sensor unit  1  more effectively, compared with a fixing method using a UV curing adhesive material. 
     According to this embodiment, the vertical axis rotation-adjusting eccentric pin  3  and the horizontal axis rotation-adjusting eccentric pin  4  are identical in rotation direction with each other, which enables the adjustment process to be performed with a driver or the like operated in one direction, and enables the holes for adjustment and the cover allocation to be limited to one direction to thereby enable the cover covering this portion to be allocated in a simple manner. 
     According to this embodiment, the rotation centers of the horizontal axis rotation adjustment and the vertical axis rotation adjustment are disposed closer to the AF sensor, and the eccentric pins are disposed outside the rotation center axes of the horizontal axis rotation adjustment and the vertical axis rotation adjustment, which allows the vicinity of the AF sensor that is a heavy object to be secured, and hence makes it difficult to cause the positional deviation by an external force applied due to vibrations or dropping. Further, with this arrangement, it is possible to set the distances between the rotation center axes of the horizontal axis rotation adjustment and the vertical axis rotation adjustment to the rotation center axes of the eccentric pins so as to correspond to the adjustment sensitivity. That is, it is possible to optimize the adjustment sensitivity for rotatably moving the eccentric pins by adjusting the distances between the rotation center axes of the eccentric pins and the rotation center axes of the AF sensor unit and the AF sensor unit-mounting seat, without an excessive increase in size, and furthermore, it is possible to prevent the interference between adjustment tools such as a driver at the time of assembling. Also, a curved section of the head of each of the eccentric pins enables the AF sensor unit to be smoothly adjusted in cooperation with the rotational operations of the eccentric pins without any problem, even when the rotation center axes of the eccentric pins are perpendicular to the rotation center axis of the AF sensor unit. 
     In this embodiment, it should be noted that the AF sensor unit-mounting unit  14  is mounted on the stationary cylinder rotatably with respect to the horizontal axis (the first axis, or the Y-axis), and the AF sensor holder-mounting unit  8  is mounted on the AF sensor unit-mounting unit  14  rotatably with respect to the vertical axis (the second axis, or the X-axis); however, the AF sensor unit-mounting unit  14  may be mounted on the stationary cylinder rotatably with respect to the vertical axis (the second axis, or the X-axis), and the AF sensor holder-mounting unit  8  may be mounted on the AF sensor unit-mounting unit  14  rotatably with respect to the horizontal axis (the first axis, or the Y-axis). 
     Also, according to this embodiment, the side faces of the respective heads of the vertical axis rotation-adjusting eccentric pin  3  and the horizontal axis rotation-adjusting eccentric pin  4  are curved; however, the side faces of the respective heads of the vertical axis rotation-adjusting eccentric pin  3  and the horizontal axis rotation-adjusting eccentric pin  4  may be flat, and further the wall portions defining the elongated holes of the AF sensor holder-mounting unit and slidably contacting the respective heads may be curved. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions. 
     This application claims the benefit of Japanese Application No. 2009-290967, filed Dec. 22, 2009, which is hereby incorporated by reference herein in its entirety.