Abstract:
A light adjusting device includes a base plate having an aperture; at least one light adjusting member configured to adjust the amount of light passing through the aperture; and at least one electromagnetic driving source configured to rotate the light adjusting member. The light adjusting member is provided with a rotating shaft member having magnetism. The light passing through the aperture is adjusted by rotating the rotating shaft member by using the electromagnetic driving source. The electromagnetic driving source includes a yoke and a winding coil wound on the yoke. The electromagnetic driving source is disposed on the base plate such that both front end sections of the yoke face toward the rotating shaft member in an area near and including a constraining point.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2009-088974 filed on Apr. 1, 2009; the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a light adjusting device. 
         [0004]    2. Description of the Related Art 
         [0005]    In recent years, with higher performance of small optical devices such as mobile equipment with imaging functions and a micro-videoscope, the shift in demand from conventional fixed-focus lens and fixed-aperture diaphragm to focusing lens and adjustable aperture has been growing in optical elements such as lenses and diaphragms. Naturally, smaller optical elements, better power savings, and more stable operation are anticipated. 
         [0006]    Japanese Patent Application Laid-open No. 2002-303914 discloses a conventional electromagnetically driven shutter  900 . In the conventional electromagnetically driven shutter  900 , as shown in  FIG. 15 , a coil  950  is disposed on the circumference of a base plate  930  (shutter plate) in the thickness direction of the base plate  930 . With this configuration, the volume of a yoke member  960  (coil core) can be made larger leading to achievement of a stable driving force. Moreover, miniaturization is possible because the configuration of the coil  950  is simple and the number of parts is small, and the assembly is simple. Incidentally,  FIG. 15  is a perspective view of the configuration of the conventional electromagnetically driven shutter. 
         [0007]    However, in the electromagnetically driven shutter  900  disclosed in the Japanese Patent Application Laid-open No. 2002-303914, because the coil  950  is installed on the base plate  930 , the yoke member  960  separates from the base plate  930  by an amount equivalent to the thickness of the wound coil wire. For this reason, the front ends of the yoke member  960  face a magnet  940  (rotor), which is a rotating shaft, at a position distant from the base plate  930 . The larger is the distance of the position of the front ends of the yoke member  960  facing the magnet  940  from the base plate  930 , the greater is the flutter of movable members, and the more difficult is to achieve stable driving. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention has been made in view of the above discussion. It is an object of the present invention to suppress flutter of a movable member that moves with the rotation of a rotating shaft member and to stabilize operation while achieving higher yoke volume of a coil disposed on a base plate. 
         [0009]    To solve the above problems and to achieve the above objects, a light adjusting device according to an aspect of the present invention includes a base plate having an aperture; at least one light adjusting member configured to adjust the amount of light passing through the aperture; and at least one electromagnetic driving source configured to rotate the light adjusting member. The light adjusting member is provided with a rotating shaft member having magnetism. The light passing through the aperture is adjusted by rotating the rotating shaft member by using the electromagnetic driving source to rotate the light adjusting member from a first static position retracted from the aperture to a second static position overlapping the aperture. The electromagnetic driving source includes a yoke and a winding coil wound on the yoke. The electromagnetic driving source is disposed on the base plate such that both front end sections of the yoke face toward the rotating shaft member in an area near and including a constraining point that defines the position of the rotating shaft member, regardless of the number of turns of the winding coil. 
         [0010]    In the light adjusting device according to another aspect of the present invention, it is preferable that both the front end sections of the yoke are bent in a direction of an optical axis to face toward the rotating shaft member near the constraining point. 
         [0011]    In the light adjusting device according to still another aspect of the present invention, it is preferable that both the front end sections of the yoke are bent in the vertical direction toward the base plate and substantially parallel to the rotating shaft member to face toward the rotating shaft member near the constraining point. 
         [0012]    In the light adjusting device according to still another aspect of the present invention, it is preferable that the front end sections of the yoke are further bent toward the side of the rotating shaft member after bending them in a direction of an optical axis to face toward the rotating shaft member near the constraining point. 
         [0013]    In the light adjusting device according to still another aspect of the present invention, it is preferable that at least the front end section of the yoke whereupon the winding coil has not been wound is thicker than a section whereupon the winding coil has been wound in a thickness direction of the base plate. 
         [0014]    In the light adjusting device according to still another aspect of the present invention, it is preferable that each of the front end sections of the yoke is laminated by at least one plate member. 
         [0015]    In the light adjusting device according to still another aspect of the present invention, it is preferable that the base plate has a notch such that the winding coil of the electromagnetic driving source can be set in the notch. 
         [0016]    In the light adjusting device according to still another aspect of the present invention, it is preferable that a plurality of light adjusting members are provided and each of the light adjusting members has an aperture of different diameter. 
         [0017]    In the light adjusting device according to still another aspect of the present invention, it is preferable that a plurality of light adjusting members are provided and each of the light adjusting members is provided with an optical lens having different optical characteristics. 
         [0018]    In the light adjusting device according to still another aspect of the present invention, it is preferable that a plurality of light adjusting members are provided and each of the light adjusting members is provided with an optical filter having different optical characteristics. 
         [0019]    The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is an exploded perspective view of the configuration of a light adjusting device according to a first embodiment; 
           [0021]      FIG. 2  is a perspective view of the configuration of the light adjusting device according to the first embodiment in the assembled condition; 
           [0022]      FIG. 3  is a side view of the configuration of a light adjusting device according to a comparative example; 
           [0023]      FIG. 4  is a side view of the configuration of the light adjusting device according to the first embodiment; 
           [0024]      FIG. 5  is a perspective view of the state of an optical aperture of a light adjusting member in a first static position; 
           [0025]      FIG. 6  is a perspective view of the state of the optical aperture of the light adjusting member in a second static position; 
           [0026]      FIG. 7  is an exploded perspective view of the configuration of a light adjusting device according to a second embodiment; 
           [0027]      FIG. 8  is a perspective view of the configuration of the light adjusting device according to the second embodiment in the assembled condition; 
           [0028]      FIG. 9  is an exploded perspective view of the configuration of a light adjusting device according to a third embodiment; 
           [0029]      FIG. 10  is a perspective view of the configuration of the light adjusting device according to the third embodiment in the assembled condition; 
           [0030]      FIG. 11  is an exploded perspective view of the configuration of a light adjusting device according to a fourth embodiment; 
           [0031]      FIG. 12  is a perspective view of the configuration of the light adjusting device according to the fourth embodiment in the assembled condition; 
           [0032]      FIG. 13  is an exploded perspective view of the configuration of a light adjusting device according to a fifth embodiment; 
           [0033]      FIG. 14  is a perspective view of the configuration of the light adjusting device according to the fifth embodiment in the assembled condition; and 
           [0034]      FIG. 15  is a perspective view of the configuration of a conventional electromagnetically driven shutter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    Exemplary embodiments of a light adjusting device according to the present invention are explained below with reference to accompanying diagrams. The present invention shall not be construed as being restricted by the embodiments explained below. 
       First Embodiment 
       [0036]    A light adjusting device  100  according to a first embodiment is explained below with reference to  FIGS. 1 to 6 .  FIG. 1  is an exploded perspective view of the configuration of the light adjusting device  100  according to the first embodiment.  FIG. 2  is a perspective view of the configuration of the light adjusting device  100  in an assembled condition. 
         [0037]    The light adjusting device  100  includes a base plate  101  with an optical aperture  102  formed therein, a base plate  111  with an optical aperture  112  formed therein, a plate-shaped light adjusting member  121  with an optical aperture  122  formed therein, two restricting parts  131  and  132  that restrict the movement of the light adjusting member  121 , and an electromagnetic driving source  141  for moving the light adjusting member  121 . The base plate  101  and the base plate  111  are circular plates with the same outer diameter. The optical aperture  102  is provided at the center of the base plate  101  and the optical aperture  112  is provided at the center of the base plate  111 . An aperture diameter of the optical aperture  122  is smaller than that of the optical aperture  102  and the optical aperture  112 . 
         [0038]    A rotating shaft hole  103  is formed in the base plate  101  and a rotating shaft hole  113  is formed in the base plate  111 . The rotating shaft holes  103  and  113  are formed in such a manner that they mutually coincide at a position when the base plates  101  and  111  are stacked and the optical aperture  102  and the optical aperture  112  are aligned. The light adjusting member  121  is disposed between the base plates  101  and  111 . A rotating shaft member  123  having magnetism is provided in the light adjusting member  121 . The rotating shaft member  123  protrudes out from both sides of the light adjusting member  121 . One end of the rotating shaft member  123  is rotatably inserted in the rotating shaft hole  103  while the other end is rotatably inserted in the rotating shaft hole  113 . 
         [0039]    Moreover, a spacer (not shown) is disposed between the base plate  101  and the base plate  111  to form a space in which the light adjusting member  121  can move rotationally. 
         [0040]    The electromagnetic driving source  141  includes a plate-shaped yoke member  142  (yoke) and two winding coils (winding coil)  143   a  and  143   b . The electromagnetic driving source  141  is disposed on the base plate  101 . The winding coils  143   a  and  143   b  are wound at both end sections of the yoke member  142  such that both front end sections  144   a  and  144   b  of the yoke member  142  are exposed. Both the front end sections  144   a  and  144   b  of the yoke member  142  are bent toward the side of the base plate  101  such that each front end section faces the rotating shaft member  123 . 
         [0041]    Next, both the front end sections  144   a  and  144   b  of the yoke member  142  are explained with reference to  FIGS. 3 and 4 .  FIG. 3  is a side view of the configuration of a light adjusting device according to a comparative example.  FIG. 4  is a side view of the configuration of the light adjusting device  100  according to the first embodiment. The members that have the same or similar configuration or the same or similar function in the comparative example shown in  FIG. 3  and the light adjusting device  100  shown in  FIG. 4  have been given like reference numerals. 
         [0042]    In the comparative example shown in  FIG. 3 , the electromagnetic driving source  141  is disposed on the base plate  101  without bending a front end section  154   b  of the yoke member  142 . In this configuration, the front end section  154   b  of the yoke member  142  faces the rotating shaft member  123  at a position that is distant from the light adjusting member  121  by an amount equivalent to the thickness of the winding coil  143   b . Accordingly, the thicker is the winding coil  143   b , the farther is the distance of the front end section  154   b  of the yoke member  142  from the light adjusting member  121 , and the more likely is the possibility of occurrence of instability in driving the light adjusting member  121 . 
         [0043]    In contrast, in the light adjusting device  100  according to the first embodiment shown in  FIG. 4 , the front end section  144   b  of the yoke member  142  is bent toward the side of the light adjusting member  121 , that is, toward the base plate  101 . With this configuration, the front end section  144   b  of the yoke member  142  faces the rotating shaft member  123  closer to the light adjusting member  121 . Such a configuration is similarly provided at the other front end section  144   a.    
         [0044]    Both the front end sections  144   a  and  144   b  of the yoke member  142  are bent so as to face toward the rotating shaft member  123  near the constraining point that defines the position of the rotating shaft member  123 . From the view point that the position of the rotating shaft member  123  is defined by restricting the deflection of the rotating shaft member  123  in the diametric direction of the base plate  101 , the constraining point is the circular area drawn by the rotating shaft hole  103  on the upper surface of the base plate  101 . 
         [0045]    “Near the constraining point” may be considered as the range, for instance, between the lower surface of a core of the winding coils  143   a  and  143   b , and the lowermost surface of the winding coils  143   a  and  143   b  formed by winding coils on the core. With this configuration, by varying the bending direction of both the front end sections  144   a  and  144   b  depending on the thickness of the coil, both the front end sections  144   a  and  144   b  can each be made to face toward the rotating shaft member  123  near the constraining point regardless of the number of turns of the winding coils  143   a  and  143   b.    
         [0046]    Attention is drawn to the fact that “near the constraining point” may be considered as the area nearest to the constraining point in the rotating shaft member. 
         [0047]    Next, the operation of the light adjusting device  100  is explained with reference to  FIG. 5  and  FIG. 6 .  FIG. 5  is a perspective view of a situation where the light adjusting member  121  is in a first static position state.  FIG. 6  is a perspective view of a situation where the light adjusting member  121  in a second static position state. The base plate  101  and the electromagnetic driving source  141  are not shown in  FIGS. 5 and 6 . 
         [0048]    When the electromagnetic driving source  141  rotationally drives the rotating shaft member  123 , the light adjusting member  121  rotates with the central axis of the rotating shaft member  123  as the center of rotation. More specifically, the rotating shaft member  123  is rotated such that the light adjusting member  121  moves from the first static position to the second static position and vice-versa by the magnetic force generated in both the front end sections  144   a  and  144   b  of the yoke member  142  by supplying an electric current to the electromagnetic driving source  141 . 
         [0049]    As shown in  FIG. 5 , when the light adjusting member  121  is rotated so that it comes in contact with the restricting part  132 , the optical aperture  122  of the light adjusting member  121  is at the first static position retracted from both the optical apertures  112  and  102 . In this situation, the optical aperture of the light adjusting device  100  is equivalent to the optical aperture  102  of the base plate  101 . 
         [0050]    On the other hand, as shown in  FIG. 6 , when the light adjusting member  121  is rotated so that it comes into contact with the restricting part  131 , the optical aperture  122  of the light adjusting member  121  is at the second static position, which coincides with both the optical apertures  112  and  102 . In this situation, the optical aperture of the light adjusting device  100  is equivalent to the optical aperture  122  of the light adjusting member  121 . 
         [0051]    As explained above, in the light adjusting device  100  according to the first embodiment, as shown in  FIG. 4 , both the front end sections  144   a  and  144   b  of the yoke member  142  in the electromagnetic driving source  141  are bent toward the side of the light adjusting member  121 . 
         [0052]    Generally, when the electromagnetic driving source  141  is disposed directly on the base plate  101 , the thickness of the winding coils  143   a  and  143   b  increases along with the increase in the number of turns of the coil. The yoke member  142  separates further from the upper surface of the plate-shaped light adjusting member  121  as the number of turns of the coil increases. This is also accompanied by further separation of both the front end sections  144   a  and  144   b  of the yoke member  142  from the light adjusting member  121 . The result is that when the magnetic force generated in both the front end sections  144   a  and  144   b  of the yoke member  142  acts on the rotating shaft member  123  at a position distant from the light adjusting member  121 , rotational deflection of the rotating shaft member  123  occurs, and the flutter of the light adjusting member  121  increases. As a result, stable operation of the light adjusting member  121  is difficult to achieve. 
         [0053]    To address this issue, as shown in  FIG. 4 , both the front end sections  144   a  and  144   b  of the yoke member  142  of the light adjusting device  100  are bent toward the side of the light adjusting member  121  so as to face toward the rotating shaft member  123  near the constraining point. As a result, the flutter of the light adjusting member  121  is suppressed and stable operation is possible regardless of the number of turns in the winding coils  143   a  and  143   b.    
         [0054]    The light adjusting member  121  can be replaced by an optical lens whereby the light adjusting member  121  can be used as an optical lens desorption device. Moreover, the light adjusting member  121  can be provided in plurality and each of the light adjusting members  121  can be provided with an optical lens having different optical characteristics. 
         [0055]    The light adjusting member  121  can be replaced by an optical filter whereby light adjusting member  121  can be used as an optical filter desorption device that is able to change the transmitted light intensity or the transmitted wavelength band. Moreover, the light adjusting member  121  can be provided in plurality and each of the light adjusting members  121  can be provided with an optical filter having different filter characteristics. 
       Second Embodiment 
       [0056]    A light adjusting device  200  according to a second embodiment is explained below with reference to  FIGS. 7 and 8 .  FIG. 7  is an exploded perspective view of the configuration of the light adjusting device  200 .  FIG. 8  is a perspective view of the configuration of the light adjusting device  200  in an assembled state. Structural elements in  FIGS. 7 and 8  having the same or similar configuration or the same or similar function as the elements in the light adjusting device  100  according to the first embodiment are assigned the same reference numbers and their explanations are omitted. 
         [0057]    An electromagnetic driving source  241  of the second embodiment includes a yoke member  242  (yoke) and winding coils  243   a  and  243   b . The shapes of two front end sections  244   a  and  244   b  of the yoke member  242  in the electromagnetic driving source  241  of the second embodiment differ from the shapes of both the front end sections  144   a  and  144   b  of the first embodiment. 
         [0058]    Specifically, both the front end sections  244   a  and  244   b  are bent toward the side of the light adjusting member  121  so as to make the front ends extending from the winding coils  243   a  and  243   b  substantially parallel to the rotating shaft member  123 , and are subsequently bent perpendicular toward the side of the rotating shaft member  123 . In other words, both the front end sections  244   a  and  244   b  of the yoke member  242  are first bent along the direction of the optical axis (vertical direction in  FIGS. 7 and 8 ) of the light adjusting device  200 , and subsequently bent so as to be substantially parallel with the light adjusting member  121  and the base plate  101 . 
         [0059]    The result is that front ends  245   a  and  245   b  of both the front end sections  244   a  and  244   b  each face toward the rotating shaft member  123  near the base plate  101 , and near the light adjusting member  121 , as shown in  FIGS. 7 and 8 . That is, both the front end sections  244   a  and  244   b  each face toward the rotating shaft member  123  near the constraining point that defines the position of the rotating shaft member  123 . 
         [0060]    In this way, both the front end sections  244   a  and  244   b  of the yoke member  242  are bent such that both the front end sections  244   a  and  244   b  of the yoke member  242  can each face toward the rotating shaft member  123  near the light adjusting member  121 . With this configuration, the magnetic force generated in both the front end sections  244   a  and  244   b  acts near the light adjusting member  121 , and therefore, the rotational deflection of the rotating shaft member  123  can be suppressed. As a result, the flutter during operation of the light adjusting member  121  is suppressed and stable operation is possible regardless of the number of turns in the winding coils  243   a  and  243   b.    
         [0061]    Other configurations, operations, and advantages are similar to those in the first embodiment. 
       Third Embodiment 
       [0062]    A light adjusting device  300  according to a third embodiment is explained below with reference to  FIGS. 9 and 10 .  FIG. 9  is an exploded perspective view of the configuration of the light adjusting device  300 .  FIG. 10  is a perspective view of the configuration of the light adjusting device  300  in an assembled state. Structural elements in  FIGS. 9 and 10  having the same or similar configuration or the same or similar function as the elements in the light adjusting device  100  according to the first embodiment are assigned the same reference numbers and their explanations are omitted. 
         [0063]    An electromagnetic driving source  341  according to the third embodiment includes a yoke member  342  (yoke) and winding coils  343   a  and  343   b . The shapes of two front end sections  344   a  and  344   b  of the yoke member  342  in the electromagnetic driving source  341  of the third embodiment differ from the shapes of both the front end sections  144   a  and  144   b  of the first embodiment. 
         [0064]    Specifically, both the front end sections  344   a  and  344   b  are bent toward the side of the light adjusting member  121  so as to make the front ends extending from the winding coils  343   a  and  343   b  substantially parallel to the rotating shaft member  123 . In other words, both the front end sections  344   a  and  344   b  of the yoke member  342  are bent along the direction of the optical axis (vertical direction in  FIGS. 9 and 10 ) of the light adjusting device  300 . 
         [0065]    With this configuration, as shown in  FIGS. 9 and 10 , front ends  345   a  and  345   b  of both the front end sections  344   a  and  344   b  each face toward the rotating shaft member  123  near the base plate  101  and near the light adjusting member  121  so as to partially surround the rotating shaft member  123  protruding upward from base plate  101 . Accordingly, both the front end sections  344   a  and  344   b  of the yoke member  342  each face toward the rotating shaft member  123  near the constraining point that defines the position of the rotating shaft member  123 . 
         [0066]    In this way, in the third embodiment, both the front end sections  344   a  and  344   b  of the yoke member  342  are bent toward the side of the light adjusting member  121 , similar to the first and second embodiments, such that both the front end sections  344   a  and  344   b  of the yoke member  342  face toward the rotating shaft member  123  near the light adjusting member  121 . With this configuration, the magnetic force generated in both the front end sections  344   a  and  344   b  acts near the light adjusting member  121 , and therefore, the rotational deflection of the rotating shaft member  123  can be suppressed. As a result, the flutter during operation of the light adjusting member  121  is suppressed and stable operation is possible regardless of the number of turns in the winding coils  343   a  and  343   b.    
         [0067]    Furthermore, in the light adjusting device  300  of the third embodiment, because both the front end sections  344   a  and  344   b  of the yoke member  342  face toward the rotating shaft member  123  so as to partially surround it, the magnetic force generated in both the front end sections  344   a  and  344   b  of the yoke member  342  act uniformly on the rotating shaft member  123 . 
         [0068]    Other configurations, operations, and advantages are similar to those in the first embodiment. 
       Fourth Embodiment 
       [0069]    A light adjusting device  400  according to a fourth embodiment is explained below with reference to  FIGS. 11 and 12 .  FIG. 11  is an exploded perspective view of the configuration of the light adjusting device  400 .  FIG. 12  is a perspective view of the configuration of the light adjusting device  400  in an assembled state. Structural elements in  FIGS. 11 and 12  having the same or similar configuration or the same or similar function as the elements in the light adjusting device  100  according to the first embodiment are assigned the same reference numbers and their explanations are omitted. 
         [0070]    An electromagnetic driving source  441  of the fourth embodiment includes a yoke member  442  (yoke) and winding coils  443   a  and  443   b . Laminate members  445   a  and  445   b  are each laminated on the lower surface of front end sections  444   a  and  444   b  of the yoke member  442  in the electromagnetic driving source  441  of the fourth embodiment so that thickness in the optical axis direction (vertical direction in  FIGS. 11 and 12 ) of the light adjusting device  400  is increased. As a result, the front end sections of yoke member  442  each face toward the rotating shaft member  123  near the base plate  101  and near the light adjusting member  121  so as to partially surround the rotating shaft member  123  protruding from the base plate  101 . 
         [0071]    The laminate members  445   a  and  445   b  should preferably be made of magnetic material. 
         [0072]    In this way, by increasing the thickness of the front end sections of the yoke member  442  on the side of the light adjusting member  121 , the front end sections of the yoke member  442  are made to face toward the rotating shaft member  123  near the light adjusting member  121 . The result is that the front end sections of the yoke member  442  face toward the rotating shaft member  123  near the light adjusting member  121 , and the magnetic force generated in the front end sections  444   a  and  444   b , and the laminate members  445   a  and  445   b , act near the light adjusting member  121 ; therefore, the rotational deflection of the rotating shaft member  123  can be suppressed. By virtue of this configuration, the flutter in the light adjusting member  121  can be suppressed and stable operation is possible regardless of the number of turns in the winding coils  443   a  and  443   b.    
         [0073]    Because the front end sections  444   a  and  444   b , and the laminate members  445   a  and  445   b  of the yoke member  442  in the fourth embodiment face each other so as to partially surround the rotating shaft member  123 , the magnetic force generated in the front end sections  444   a  and  444   b , and the laminate members  445   a  and  445   b  of the yoke member  442 , operates uniformly on the rotating shaft member  123 . 
         [0074]    Although the laminate members  445   a  and  445   b  are laminated on the front end sections  444   a  and  444   b  of the yoke member  442  in the light adjusting device  400  of the fourth embodiment, some other configuration can be employed. For example, instead of laminating the laminate members  445   a  and  445   b  on the front end sections  444   a  and  444   b , the front end section of the yoke member  142  can be made thicker on the side of the light adjusting member  121 . 
         [0075]    Other configurations, operations, and advantages are similar to those in the first embodiment. 
       Fifth Embodiment 
       [0076]    A light adjusting device  500  according to a fifth embodiment is explained below with reference to  FIGS. 13 and 14 .  FIG. 13  is an exploded perspective view of the configuration of the light adjusting device  500 .  FIG. 14  is a perspective view of the configuration of the light adjusting device  500  in an assembled state. Structural elements in  FIGS. 13 and 14  having the same or similar configuration or the same or similar function as the elements in the light adjusting device  100  according to the first embodiment are assigned the same reference numbers and their explanations are omitted. 
         [0077]    An electromagnetic driving source  541  of the fifth embodiment includes a yoke member  542  (yoke) and winding coils  543   a  and  543   b . The winding coils  543   a  and  543   b  are wound on both end sections of the yoke member  542 , such that both front end sections  544   a  and  544   b  of the yoke member  542  are exposed. 
         [0078]    An optical aperture  502  and a rotating shaft hole  503  are provided in a base plate  501  similar to the base plate  101  of the first embodiment. Moreover, as shown in  FIGS. 13 and 14 , notches (holes)  504   a  and  504   b  are provided in the base plate  501  at positions corresponding to the winding coils  543   a  and  543   b  respectively. 
         [0079]    As shown in  FIG. 14 , when placing the electromagnetic driving source  541  on the base plate  501 , the winding coils  543   a  and  543   b  are inserted into the notches (holes)  504   a  and  504   b  in the base plate  501 . The result is that both the front end sections  544   a  and  544   b  of the yoke member  542  face toward the rotating shaft member  123  near the light adjusting member  121 . 
         [0080]    In this way, both the front end sections  544   a  and  544   b  of the yoke member  542  can be made to face toward the rotating shaft member  123  near the light adjusting member  121  without bending or increasing the thickness of the front end sections of the yoke member  542  in the light adjusting device  500  of the fifth embodiment. Accordingly, because the magnetic force generated in both the front end sections  544   a  and  544   b  act near the light adjusting member  121 , the rotational deflection of the rotating shaft member  123  can be suppressed. As a result, the flutter during operation of the light adjusting member  121  can be reduced and stable operation is possible regardless of the number of turns in the winding coils  543   a  and  543   b.    
         [0081]    Other configurations, operations, and advantages are similar to those in the first embodiment. 
         [0082]    As explained above, the light adjusting device according to the present invention is useful as a light adjusting device that attains stable driving of the light adjusting member while increasing the yoke volume of the coil. 
         [0083]    The light adjusting device according to the present invention has an advantage that flutter in the light adjusting member can be suppressed and stable operation can be attained. This advantage is achieved by disposing the front end sections of the yoke to face toward the rotating shaft, which functions as a magnet, near the constraining point, while achieving higher yoke volume of a coil disposed on the base plate. 
         [0084]    Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.