Abstract:
There is provided a light adjusting apparatus which is to be used for a small-size image pickup equipment which is easy to assemble. 
     The light adjusting apparatus includes two substrates (an upper substrate and a lower substrate), out of which, one has an aperture, a spacing portion which regulates a distance between the two substrates, at least one incident-light adjusting unit which has a shaft member which becomes a center of rotation, and which is turned in a plane perpendicular to an optical axial direction, between the substrates, and at least one driving unit which drives the incident-light adjusting unit. Incident light which passes through the aperture is adjusted by turning the incident-light adjusting unit alternately, to the aperture and to a retracted position which is retracted from the aperture, by the driving unit. The light adjusting apparatus includes a notch which receives the shaft member, formed in the substrate, and a retaining portion which prevents the incident-light adjusting unit from dropping.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a light adjusting apparatus. 
         [0003]    2. Description of the Related Art 
         [0004]    Various types of light adjusting apparatus have hitherto been used. As one of the types of such apparatuses, a plug-in type light adjusting apparatus in which, a single or a plurality of optical elements is displaced mutually in and outside an optical path by an electromagnetic driving source or some other type of driving source, and optical characteristics of incident light which passes through the optical path are changed, is available. In recent years, with an achievement of a high-quality image of a portable equipment having an image pickup function and a small-size image pickup equipment such as a micro video scope, with regard to optical elements such as a lens, an aperture, and an optical filter, an application of a focusing lens, a variable aperture, and a variable special characteristic filter instead of a conventional fixed focusing lens, a fixed aperture stop, and a fixed special characteristic filter has been sought strongly. As the abovementioned light adjusting apparatus to be used in such small-size image pickup equipment, such plug-in type light adjusting apparatus which is suitable for small-sizing has been gathering attention because of its simple structure. 
         [0005]    As an example of such plug-in type light adjusting apparatus suitable for small-sizing, a light adjusting apparatus disclosed in Japanese Patent Application Laid-open Publication No. Hei 10-20360 is available. This light adjusting apparatus includes a rotor which is polarized to bipolarity. A diaphragm plate is fixed to the rotor via a shaft. The rotor is inserted through a rotating hole into a coil which has been formed to be ring-shaped, and is fixed to be freely rotatable, by a shaft receiver made of a circular cylindrical shaped protruding portion which is formed in an upper cover and a lower cover. 
       SUMMARY OF THE INVENTION 
       [0006]    As it has been described above, in the conventional light adjusting apparatus described in Japanese Patent Application Laid-open Publication No. Hei 10-20360, the shaft which becomes a rotating shaft of the diaphragm plate is fixed to be rotated freely by inserting into the shaft receiver which is made of the circular cylindrical shaped protruding portion formed in the upper cover and the lower cover. Therefore, as a process of assembling the light adjusting apparatus, the upper cover and the lower cover have to be joined with the shaft positioned in the shaft receiver. In an apparatus in which, the small-sizing has been sought, due to the positioning of the shaft; a degree of difficulty of assembling becomes high. 
         [0007]    In Japanese Patent Application Laid-open Publication No. Hei 10-20360, as the shaft receiver, the circular cylindrical shaped protruding portion has been formed in the upper cover and the lower cover. Apart from this type, a structure in which, a hole for the shaft receiver is formed in the upper cover and the lower cover is common. Even in a case in which, the shaft receiver is a hole, a problem similar to the abovementioned problem arises. 
         [0008]    The present invention has been made in view of the abovementioned circumstances, and an object of the present invention is to change a mounting arrangement of a rotating shaft of the diaphragm plate, and to provide a light adjusting apparatus which is easy to assemble and which can be used in a small-size image pickup equipment. 
         [0009]    To solve the abovementioned problems and to achieve the object, according to the present invention, there is provided a light adjusting apparatus including 
         [0010]    two substrates, out of which, at least one has an aperture, 
         [0011]    a spacing portion which regulates a distance between the two substrates, 
         [0012]    at least one incident-light adjusting unit which has a shaft member which becomes a center of rotation, and which is turned (pivoted) in a plane perpendicular to an optical axial direction, between the substrates, and 
         [0013]    at least one driving unit which drives the incident-light adjusting unit, and 
         [0014]    incident light which passes through the aperture is adjusted by turning the incident-light adjusting unit alternately to the aperture and to a retracted position which is retracted from the aperture, by the driving unit, and 
         [0015]    the light adjusting apparatus includes 
         [0016]    a notch which receives the shaft member, formed in the substrate, and 
         [0017]    a retaining portion which prevents the incident-light adjusting unit from dropping. 
         [0018]    Moreover, according to a preferable aspect of the present invention, it is desirable that the two substrates and the spacing member are made of a single member which is made by a single stacking process and/or a molding process. 
         [0019]    Furthermore, according to a preferable aspect of the present invention, it is desirable that the notch and the shaft member are in contact at least at two points. 
         [0020]    According to a preferable aspect of the present invention, it is desirable that a part of the retaining portion and a part of the notch which receives the shaft member form a circular arc shape. 
         [0021]    Moreover, according to a preferable aspect of the present invention, it is desirable that the retaining portion makes a contact at least at one point of the shaft member or the incident-light adjusting unit. 
         [0022]    Furthermore, according to a preferable aspect of the present invention, it is desirable that the retaining member is made of a separate member which differs from the two substrates and the spacing portion. 
         [0023]    According to a preferable aspect of the present invention, it is desirable that a projection and a recess are provided to the two substrates and the retaining portion respectively, and the two substrates and the retaining portion are joined. 
         [0024]    Moreover, according to a preferable aspect of the present invention, it is desirable that the spacing portion and the retaining portion are joined by sticking the retaining portion to the spacing portion. 
         [0025]    Furthermore, according to a preferable aspect of the present invention, it is desirable that a stage equivalent to a thickness of the retaining portion is formed on the spacing portion. 
         [0026]    According to a preferable aspect of the present invention, it is desirable that the retaining portion is the same member as the substrate and the spacing portion. 
         [0027]    Moreover, according to a preferable aspect of the present invention, it is desirable that the retaining portion is made of a protruding portion which is formed on a side surface of the notch which receives the rotating shaft. 
         [0028]    Furthermore, according to a preferable aspect of the present invention, it is desirable that the incident-light adjusting units are provided in plurality. 
         [0029]    According to a preferable aspect of the present invention, it is desirable that all incident-light adjusting units are held by a single retaining portion. 
         [0030]    Moreover, according to a preferable aspect of the present invention, it is desirable that the upper substrate is formed to have a diameter smaller than a diameter of the lower substrate, roughly by an amount of width of the retaining portion. 
         [0031]    Furthermore, according to a preferable aspect of the present invention, it is desirable that an aperture having a diameter different from a diameter of the aperture formed in the substrate is formed in the incident-light adjusting unit. 
         [0032]    According to a preferable aspect of the present invention, it is desirable that an optical lens is formed in the incident-light adjusting unit. 
         [0033]    Moreover, according to a preferable aspect of the present invention, it is desirable that an optical filter is formed in the incident-light adjusting unit. 
         [0034]    Furthermore, according to a preferable aspect of the present invention, it is desirable that the driving unit includes a magnet which is joined to the incident-light adjusting unit, and a coil in which, a coil wire is wound around a core material. 
         [0035]    The light adjusting apparatus according to the present invention shows an effect that since the light adjusting apparatus is assembled by providing a notch which receives the shaft member, to the substrate, assembling becomes easy. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  is an exploded perspective view of a variable aperture according to a first embodiment of the present invention; 
           [0037]      FIG. 2  is a top view of the first embodiment; 
           [0038]      FIG. 3  is a diagram showing a structure according to a modified embodiment of the first embodiment; 
           [0039]      FIG. 4  is a diagram showing a structure of a shaft receiving member according to a second embodiment of the present invention; 
           [0040]      FIG. 5  is a diagram showing a structure of a shaft receiving member according to a third embodiment of the present invention; 
           [0041]      FIG. 6  is a diagram showing a structure of a shaft receiving member according to a modified embodiment of the third embodiment; 
           [0042]      FIG. 7A ,  FIG. 7B , and  FIG. 7C  are diagrams, each showing a shaft member and a notch for receiving shaft of a light adjusting apparatus according to a fourth embodiment of the present invention; 
           [0043]      FIG. 8A ,  FIG. 8B ,  FIG. 8C , and  FIG. 8D  are diagrams, each showing a shaft receiving member and a shaft member or a diaphragm plate of the light adjusting apparatus according to the fourth embodiment; 
           [0044]      FIG. 9  is an exploded perspective view of a light adjusting apparatus of with a variable aperture according to a fifth embodiment of the present invention; and 
           [0045]      FIG. 10  is a top view of the light adjusting apparatus of with the variable aperture according to the fifth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0046]    Exemplary embodiments of a light adjusting apparatus according to the present invention will be described below in detail by referring to the accompanying diagrams. However, the present invention is not restricted to the embodiments described below. 
       First Embodiment 
       [0047]    A light adjusting apparatus according to a first embodiment of the present invention is a variable aperture which regulates an amount of light which passes through an aperture, by displacing a diaphragm plate in which the aperture is formed to a position in an optical path and a position away from the optical path alternately. Moreover, an arrangement is let to be such that the diaphragm plate is driven by using an electromagnetic actuator. 
         [0048]      FIG. 1  is an exploded perspective view of the variable aperture in the light adjusting apparatus according to the first embodiment.  FIG. 2  shows a top view excluding a coil, in the variable aperture shown in  FIG. 1 . 
         [0049]    As shown in  FIG. 1  and  FIG. 2 , the variable aperture according to the first embodiment includes a lower substrate  100 , a diaphragm plate  200  to which a shaft member  202  is joined, an upper substrate  300 , a spacing member  400 , a shaft receiving member  500 , and a coil  600 . In all the embodiments which follow, the diaphragm plate  200  corresponds to an incident-light adjusting unit, the spacing member  400  corresponds to a spacing portion, the shaft member  202  and the coil  600  correspond to a driving unit, and the shaft receiving ember  500  corresponds to a retaining portion. 
         [0050]    A first aperture  101 , a positioning portion  105 , and a notch  102  for receiving shaft are formed in the lower substrate  100 . A second aperture  201  is formed in the diaphragm plate  200 , and the shaft member  202  made of a circular cylindrical shaped magnet is joined to the diaphragm plate  200 . A third aperture  301  and a notch  302  for receiving shaft are formed in the upper substrate  300 . Shaft receiving portions  501  and  502 , and a window  504  are formed in the shaft receiving member  500 . The coil  600  is a structure in which, a coil wire  601  is wound around a core material  602 . 
         [0051]    Details of each structural member will be described below. 
         [0052]    The first aperture  101  and the notch  102  for receiving shaft are formed in the lower substrate  100 , and the third aperture  301  and the notch  302  for receiving shaft are formed in the upper substrate  300 . Centers of the first aperture  101  and the third aperture  301  are let to be an optical axis, and the optical axis is an optical path through which, incident light passes. The first aperture  101  and the third aperture  301  are formed such that a diameter of the first aperture  101  and a diameter of the third aperture  301  are let to be same or different. The diameter of the aperture is a diameter of an open aperture in the variable aperture. When the diameter of the first aperture  101  and the diameter of the third aperture  301  are different, the smaller diameter of the aperture becomes the diameter of the open aperture. 
         [0053]    The notch  102  for receiving shaft is cut from an outer peripheral portion of the lower substrate  100  toward the centers of the first aperture  101 , and the notch  302  for receiving shaft is cut from an outer peripheral portion of the upper substrate  300  toward the third aperture  301 . A deepest portion of the notch is formed to be circular-arc shaped having a diameter almost same as a diameter of the shaft member  202 . Moreover, the positioning portion  105  is formed in the lower substrate  100 . 
         [0054]    The spacing member  400  is a member which regulates a distance between the lower substrate  100  and the upper substrate  300 , and relative positions of the lower substrate  100  and the upper substrate  300 . Furthermore, the spacing member  400  is discontinuous near the notch  102  for receiving shaft formed in the lower substrate  100  and the notch  302  for receiving shaft formed in the upper substrate  300 . A stage portion  401  in a direction toward center is provided at an end portion of the spacing member  400 . 
         [0055]    The shaft receiving portions  501  and  502  having a circular arc shape of a diameter almost same as the diameter of the shaft member  202  are formed at a substantially central portion of the shaft receiving member  500 . As shown in  FIG. 2 , two end-portions of the shaft receiving member  500  are joined to the stage portion  401  of the spacing member  400  by an adhesive. In this joined state, an area of a circular arc shaped portion of the notch  102  for receiving shaft, a circular arc shaped portion of the notch  302  for receiving shaft, and a circular arc shaped portion of the shaft receiving portions  501  and  502  has a substantially circular shape with a diameter almost same as the diameter of the shaft member  202 . 
         [0056]    In such manner, by joining the two end-portions of the shaft receiving member  500  and the stage portion  401  of the spacing member  400 , the variable aperture is formed without an outer shape of the variable aperture being protruded. Moreover, the window  504  is formed at the substantially central portion of the shaft receiving member  500 . The window  504  has been formed for preventing interference with the diaphragm plate  200 , and by adopting such structure, it is possible reduce further external dimensions of the variable aperture. 
         [0057]    The second aperture  201  which is smaller than the first aperture  101  formed in the lower substrate  100  and the third aperture  301  formed in the upper substrate  300 , is formed in the diaphragm plate  200 . Moreover, the shaft member  202  made of the circular cylindrical shaped magnet is joined to the diaphragm plate  200  by a method such as press fitting . The shaft member  202  is fitted into substantially circular shaped area which is formed by the notch  102  for receiving shaft formed in the lower substrate  100  and the notch  302  for receiving shaft formed in the upper substrate  300 , and the shaft receiving portions  502  and  501  which are formed in the shaft receiving members  500 . The diaphragm plate  200  is pivotably installed with the shaft member  202  as an axis of rotation. An area in which the diaphragm plate  200  moves, in an optical axial direction, is regulated by the lower substrate  100  and the upper substrate  300 , and an area in which the diaphragm plate  200  moves, in a direction of rotation is regulated by the positioning portion  105  and the spacing member  400 . 
         [0058]    The diaphragm plate  200  is formed (arranged) such that, at a position at which the diaphragm plate  200  makes a contact with the positioning portion  105 , the center of the second aperture  201  coincides with the optical axis. 
         [0059]    The coil  600  includes the core material  602  made of a magnetic material such as permalloy and silicon steel around which the coil wire  601  is wound, and two end-portions of the core material  602  are formed (arranged) to be facing the shaft member  202  which has been joined to the diaphragm plate  200 . 
         [0060]    As a method for forming each member, the lower substrate  100 , the upper substrate  300 , and the spacing member  400  may be formed by a machining process such as pressing a thin sheet made of a non-magnetic substance such as phosphor bronze, beryllium copper, and a resin material, and joining by an adhesive, or may be formed as an integrated member by a metal MEMS technology or an injection molding technology which includes a series of staking (laminating) processes by plating and etching. 
         [0061]    Next, an operation of the variable aperture according to the first embodiment will be described below. 
         [0062]    The shaft member  202  which is joined to the diaphragm plate  200  is made of the circular cylindrical shaped magnet, and is magnetized such that an S-polarity and an N-polarity are in the optical axial direction from the center of the second aperture  201  formed in the diaphragm plate  200  toward the shaft member  202 . On the other hand, the coil  600  includes the coil wire  601  wound around the core material  602  made of a magnetic material such as permalloy and silicon steel, and by an electric current which flows through the coil wire  601 , two end-portions of the core material  602  are magnetized to the S-polarity and the N-polarity. By forces of magnetic attraction and repulsion which are generated between a magnetic field generated by the coil  600  and a magnetic field of the shaft member  202 , a rotational force is generated in the shaft member  202 , and the diaphragm plate  200  is turned (is pivoted) with the shaft member  202  as a center of rotation. It is possible to control a direction of rotation by controlling a direction of the electric current which flows through the coil wire  601 . 
         [0063]    Here, a case in which, a rotational force in a counterclockwise direction in the diagram is exerted to the diaphragm plate  200  will be taken into consideration. The diaphragm plate  200  stops at a position where it has made a contact with the positioning portion  105 . The diaphragm plate  200  closes the first aperture  101  and the third aperture  301 . By the center of the second aperture  202  formed in the diaphragm plate  200  coinciding with the optical axis, the second aperture  201  becomes the diameter of the optical path through which the incident light passes. 
         [0064]    Moreover, a case in which, a rotational force in a clockwise direction in the diagram is exerted to the diaphragm plate  200  will be taken into consideration. The diaphragm plate  200  stops at a position where it has made a contact with the spacing member  400 . The diaphragm plate  200  is retracted from the first aperture  101  and the third aperture  301 , and the first aperture  101  and the third aperture  301  become the aperture diameter. 
         [0065]    In such manner, it is possible to control in two stages, the diameter of the optical path through which the incident light passes. 
         [0066]    Next, an effect of the variable aperture according to the first embodiment will be described below. As a process of assembling the variable aperture of the first embodiment, firstly, a mechanism member which includes the lower substrate  100 , the upper substrate  300 , and the spacing member  400  is formed. Thereafter, the diaphragm plate  200  is inserted between the lower substrate  100  and the upper substrate  300 , through the discontinuous portion of the spacing member  400 , and the shaft member  202  is fitted into the notch  102  for receiving shaft and the notch  302  for receiving shaft. Finally, the shaft receiving member  500  is joined. 
         [0067]    In such manner, since the variable aperture is assembled by fitting into the notch  102  for receiving shaft and the notch  302  for receiving shaft finally, there is no need any more of joining the lower substrate  100  and the upper substrate  300  in a state of the shaft member  202  and the shaft receiving hole being positioned, and it is possible to carry out the assembling easily. 
         [0068]    Moreover, as it has hitherto been done, in a structure in which the shaft member  202  is to be inserted into the shaft receiving hole, it is not possible to adopt a molding technique in which, the lower substrate  100 , the upper substrate  300 , and the spacing member  400  are molded integrally by using the metal MEMS technology or the injection molding technology. By letting the structure to be the structure according to the abovementioned proposal, it is possible to introduce such method of molding. 
         [0069]    Furthermore, in a case of molding integrally the lower substrate  100 , the upper substrate  300 , and the spacing member  400  by using the metal MEMS technology or the injection molding technology, it is possible to have a high accuracy of relative positions of the notch  102  for receiving shaft which is formed in the lower substrate  100  and the notch  302  for receiving shaft which is formed in the upper substrate  300 . 
         [0070]    According to the method which has hitherto been used, when there is a shift in relative positions of receiving shaft of an upper cover and a lower cover due to an assembling tolerance, there has been a problem that the rotation of the shaft is obstructed. Therefore, it was necessary to position the upper substrate and the lower substrate with a high accuracy. Whereas, according to the first embodiment, it is also possible to reduce defective rotation of the shaft member  202  which is due to such shift in the assembling tolerance. 
         [0071]    Moreover, in the first embodiment, by making an arrangement such that the shaft receiving member  500  for preventing dropping of the shaft member  202  is let to be a separate member, and the diaphragm plate  200  is inserted from behind, it is also possible to select a method for molding the shaft receiving member  500  and the diaphragm plate  200  which is different from a method for the main body, a degree of freedom for molding becomes higher. 
         [0072]      FIG. 3  is a diagram showing a structure according to a modified embodiment of the first embodiment. In the modified embodiment of the first embodiment, a structure which includes three diaphragm plates will be described. As shown in  FIG. 3 , three notches  102   a,    102   b,  and  102   c  for receiving shaft are formed in a lower substrate  100  (the notch  102   b  for receiving shaft is not shown in the diagram) and three notches  302   a,    302   b , and  302   c  for receiving shaft are formed in an upper substrate  300 , and by inserting shaft members  202   a,    202   b,  and  202   c  which are joined to diaphragm plates (not shown in the diagram) in the respective notches  102   a,    302   a,    102   b,    302   b,  and  102   c  and  302   d , the structure is let to have three diaphragm plates. 
         [0073]    In such manner, by using the plurality of diaphragm plates, it is possible to apply also to a multi-stage diaphragm which realizes a plurality of different aperture diameters. 
         [0074]    Moreover, by replacing the diaphragm plate of the modified embodiment of the first embodiment by an optical lens, it is also possible to use as an optical lens detaching (detachable) apparatus. 
         [0075]    Furthermore, by replacing the diaphragm plate of the modified embodiment of the first embodiment by an optical filter, it is also possible to use as an optical filter detaching (detachable) apparatus which changes a transmission-light amount or a pass wavelength band. 
       Second Embodiment 
       [0076]    Next, a light adjusting apparatus according to a second embodiment of the present invention will be described below. Same reference numerals are assigned to members (portions) which are same as in the first embodiment and the modified embodiment of the first embodiment, and repetitive description will be omitted. 
         [0077]      FIG. 4  shows a perspective view of a shaft receiving member  500  and a part of an upper substrate  300  and a part of a lower substrate  100  of a variable aperture according to the second embodiment. 
         [0078]    As shown in  FIG. 4 , in the variable aperture according to the second embodiment, unlike in the first embodiment, projections for joining  503   a,    503   b,    503   d,  and  503   e  (projections for joining  503   d  and  503   e  are not shown in the diagram) are formed in the shaft receiving member  500 . Moreover, projection receiving holes  103   a  and  103   b  are formed in the lower substrate  100  and projection receiving holes  303   a  and  303   b  are formed in the upper substrate  300 . 
         [0079]    The projections for joining  503   a,    503   b,    503   d,  and  503   e  and the projection receiving holes  303   a,    303   b,    103   a,  and  103   b  are formed at positions such that the projections for joining  503   a,    503   b,    503   d,  and  503   e  fit in the projection receiving holes  303   a,    303   b,    103   a,  and  103   b  respectively at the time of joining the shaft receiving member  500 . By fitting the projections for joining  503   a,    503   b,    503   d,  and  503   e  into the projection receiving holes  303   a,    303   b,    103   a,  and  103   b  respectively, the shaft receiving member  500 , and the lower substrate  100  and the upper substrate  300  are joined. 
         [0080]    According to the second embodiment, since the shaft receiving member  500  is assembled only by fitting upon forming the projections for joining on the shaft receiving member, and forming the projection receiving holes in the upper substrate and the lower substrate, there is no need to stick at the time of joining, and it is possible to carry out assembling more easily. 
         [0081]    It is needless to mention that the projections for joining  503   a,    503   b,    503   d,  and  503   e  may be formed on the upper substrate  300  and the lower substrate  100  respectively, and the projection receiving holes  303   a,    303   b,    103   a,  and  103   b  maybe formed in the shaft receiving member  500 . 
       Third Embodiment 
       [0082]    Next, a third embodiment of the present invention will be described below by referring to  FIG. 5 . Same reference numerals are assigned to members which are same as in the first embodiment, the modified embodiment of the first embodiment, and the second embodiment, and repetitive description will be omitted. 
         [0083]      FIG. 5  shows a perspective view in which a part of an upper substrate and a part of a lower substrate of a variable aperture according to the third embodiment are shown. As shown in  FIG. 5 , the variable aperture according to the third embodiment differs from the variable apertures according to the first embodiment and the second embodiment at a point that protruding portions  104   a  and  104   b  are formed on a lower substrate  100 , and protruding portions  304   a  and  304   b  are formed on an upper substrate  300 , instead of forming on the shaft receiving portion  500 . 
         [0084]    An outer peripheral portion side of the lower substrate  100  which is on an outer side of a portion of the lower substrate  100  on which the protruding portions  104   a  and  104   b  are formed, and an outer peripheral portion side of the upper substrate  300  which is on an outer side of a portion of the upper substrate  300  on which the protruding portions  304   a  and  304   b  are formed are formed to be curved so that a shaft member  202  can be inserted. Moreover, a central side of the lower substrate  100 , which is more toward the center than the portion on which the protruding portions  104   a  and  104   b  are formed, and a central side of the upper substrate  300 , which is more toward the center than the portion on which the protruding portions  304   a  and  304   b  are formed are formed to be substantially circular shaped so that the shaft member  202  is turnable. Moreover, for carrying out the insertion of the shaft member  202  easily, a slit  700  may be provided on both sides of the notch  102  for receiving shaft in the lower substrate  100  and the notch  302  for receiving shaft in the upper substrate  300  as shown in  FIG. 6 . In such manner, by providing the protruding portions  104   a  and  104   b  at positions of the notch  102  for receiving shaft of the lower substrate  100 , and the protruding portions  304   a  and  304   b  at positions of the notch  302  for receiving shaft of the upper substrate  300 , it is possible to prevent dropping of the shaft member  202  without providing the shaft receiving member  500  separately, and to hold the shaft member  202  turnably. Consequently, it is possible to carry out assembling more easily. 
       Fourth Embodiment 
       [0085]    A fourth embodiment of the present invention will be described below by using  FIG. 7A ,  FIG. 7B , and  FIG. 7C  and  FIG. 8A ,  FIG. 8B , and  FIG. 8C . 
         [0086]      FIG. 7A ,  FIG. 7B , and  FIG. 7C  are diagrams, each showing a shaft member and a notch for receiving shaft of a light adjusting apparatus according to the fourth embodiment of the present invention. 
         [0087]    A notch  102  for receiving shaft becomes a guide which regulates rotation of a shaft member  202  functionally. Therefore, the notch  102  for receiving shaft is required to have at least two contact points with respect to the shaft member  202 . In this case, the contact point does not mean a point where the notch  102  for receiving shaft and the shaft member  202  come in contact at an arbitrary moment, but means a point where the notch  102  for receiving shaft and the shaft member  202  come in contact functionally. 
         [0088]    For instance, by forming the notch  102  for receiving shaft on a circular arc as shown in  FIG. 7A , the notch  102  for receiving shaft and the shaft member  202  have infinite number of contact points. Similarly, by forming the notch  102  receiving shaft as shown in  FIG. 7B , the notch  102  for receiving shaft and the shaft member  202  have three contact points. Moreover, by forming the notch  102  for receiving shaft as shown in  FIG. 7C , the notch  102  for receiving shaft and the shaft member  202  have two contact points. 
         [0089]      FIG. 8A ,  FIG. 8B ,  FIG. 8C , and  FIG. 8D  are diagrams, each showing a shaft receiving member and a shaft member or a diaphragm plate of the light adjusting apparatus according to the fourth embodiment. 
         [0090]    A shaft receiving member  500  prevents falling of a diaphragm plate  200  functionally, as well as regulates rotation of a shaft member  202  and the diaphragm plate, together with a notch  102  for receiving shaft. Therefore, the shaft receiving member  500  is required to have at least one contact point with the shaft member  202  or the diaphragm plate  200 . 
         [0091]    The contact point in this case, does not mean a point where the shaft receiving member  500  and the shaft member  202  or the diaphragm plate  200  come in contact at an arbitrary movement, but means a point where the shaft receiving member  500  and the shaft member  202  or the diaphragm plate  200  come in contact functionally. 
         [0092]    For instance, by forming protruding portions  304   a  and  304   b,  which become a shaft receiving member  500 , on a side surface of the notch  102  for receiving shaft as shown in  FIG. 8A , the shaft receiving member  500  and the shaft member  202  have two contact points. Similarly, by forming a shaft receiving member  500  as shown in  FIG. 8B , the shaft receiving member  500  and the shaft member  202  have infinite number of contact points. By forming a shaft receiving member  500  as shown in  FIG. 8C , the shaft receiving member  500  and the shaft member  202  have one contact point. Moreover, by forming a location at which, a diaphragm plate  200  makes a contact with a shaft receiving member  500 , to be circular arc shaped having a center same as a center of a shaft member  202 , and by forming the shaft receiving member  500  as shown in  FIG. 8D , the shaft receiving member  500  and the diaphragm plate  200  have one contact point. 
         [0093]    As it has been described above, by making an arrangement such that the notch  102  for receiving shaft has at least two contact points with the shaft member  202 , and the shaft receiving member  500  has at least one contact point with the shaft member  202  or the diaphragm plate  200 , the notch  102  for receiving shaft and the shaft receiving member  500  have at least three contact points with the shaft member  202  or the diaphragm plate  200 , and rotation of the shaft member  202  or the diaphragm plate  200  is regulated. 
       Additional Fifth Embodiment 
       [0094]    A fifth embodiment of the present invention will be described below by using  FIG. 9  and  FIG. 10 . 
         [0095]      FIG. 9  shows an exploded perspective view of a light adjusting apparatus according to the fifth embodiment.  FIG. 10  shows a top view of the light adjusting apparatus according to the fifth embodiment. 
         [0096]    As shown in  FIG. 9  and  FIG. 10 , the light adjusting apparatus according to the fifth embodiment has an upper substrate  300  and a spacing member  400  formed to have a diameter smaller than an outer diameter of a lower substrate  100 , on the lower substrate  100 . A periphery of each of portions where shaft members  202   a,    202   b,  and  202   c  of diaphragm plates  200   a ,  200   b,  and  200   c  are joined is formed to be circular arc shaped having a center same as a center of the shaft members  202   a,    202   b , and  202   c.    
         [0097]    Moreover, a shaft receiving member  500  has shaft receiving portions  501   a,    501   b,  and  501   c  coupled together, forming a ring shape. An inner diameter of the shaft receiving member  500  is substantially same as an outer diameter of the spacing member  400  and the upper substrate  300 . Moreover, an outer diameter of the shaft receiving member  500  is substantially same as an outer diameter of the lower substrate  100 . A thickness of the shaft receiving member  500  is substantially same as a total thickness of the spacing member  400  and the upper substrate  300 . 
         [0098]    Here, after the lower substrate  100 , the spacing member  400 , and the upper substrate  300  are joined or formed integrally, diaphragm blades  200   a,    200   b,  and  200   c  are inserted between the upper substrate  300  and the lower substrate  100 . Moreover, the shaft members  202   a,    202   b,  and  202   c  are fitted into a notches  202   a  and  302   a  for receiving shaft, notches  202   b  and  302   b  for receiving shaft, and notches  202   c  and  302   c  for receiving shaft respectively, which are formed in the upper substrate  300  and the lower substrate  100 . 
         [0099]    Thereafter, the shaft member  500  formed to be ring-shaped is joined. At the time of joining the shaft member  500 , the circular arc portions of the diaphragm plates  200   a,    200   b,  and  200   c  at a periphery where the shaft members  202   a,    202   b,  and  202   c  are joined make a contact with the shaft receiving portions  501   a ,  501   b,  and  501   c.    
         [0100]    In the embodiments described above, an arrangement is made such that the diaphragm blades and the shaft receiving members (retaining portions) correspond by a relation of one-to-one. Whereas, in the fifth embodiment, even in a case of a plurality of diaphragm blades, an arrangement can be made with one retaining portion. 
         [0101]    In such manner, by forming the light adjusting apparatus as in the fifth embodiment, even in a case of having the plurality of diaphragm blades, it is possible to prevent dropping of the diaphragm blades by a single shaft receiving member. Accordingly, it is possible to carry out assembling easily. 
         [0102]    As it has been described above, the light adjusting apparatus according to the present invention is useful for a light adjusting apparatus which adjusts incident light passing through an aperture, and particularly is suitable for a light adjusting apparatus in which, small-sizing is sought.