Abstract:
Disclosed herein is a light amount adjustment apparatus, including: a light amount adjustment member; a rotatable magnet formed in a disk shape; a driving arm configured to be pivoted by rotation of the magnet to operate the light amount adjustment member; a core having a pair of confronting portions positioned so as to sandwich the magnet from an outer circumference side and a connecting portion configured to connect end portions of the confronting portions to each other; a coil through which one of the portions of the core extends; and a base member having the core attached to the base member and supporting the magnet for rotation on the base member. The base member has a plurality of attaching projections provided at least at two places of the base member for attaching the core to the base member. The attaching projections have a small projection for fitting with the core.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present invention contains subject matter related to Japanese Patent Application JP 2007-009442 filed with the Japan Patent Office on Jan. 18, 2007, the entire contents of which being incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a light amount adjustment apparatus and an image pickup apparatus, and more particular to a light amount adjustment apparatus and an image pickup apparatus wherein a core of an electromagnet is attached to a base member. 
         [0004]    2. Description of the Related Art 
         [0005]    An image pickup apparatus of a video camera, a still camera or a light apparatus includes a light amount adjustment apparatus for adjusting the amount of light fetched through a lens group. 
         [0006]    In one of such light amount adjustment apparatus, shutter blades, a filter blade or the like serving as light amount adjustment members are supported for pivotal motion on a base member. The light amount adjustment members are pivoted by an electromagnet or actuator including a magnet, a coil and a core having a pair of confronting portions to adjust the light amount. One of light amount adjustment apparatus of the type described is disclosed, for example, in Japanese Patent Laid-Open No. 2004-95703 (hereinafter referred to as Patent Document 1). 
         [0007]    The electromagnet of the light amount adjustment apparatus disclosed in Patent Document 1 is attached to the base member in such a state that the paired confronting portions of the core are expanded by a positioning projection provided on the base member. 
       SUMMARY OF THE INVENTION 
       [0008]    However, in the light amount adjustment apparatus disclosed in Patent Document 1, since the electromagnet is attached to the base member in such a state that the paired confronting portions of the core are expanded by the positioning projection, there is the possibility that the core may be deformed plastically or excessively high restoring force may be generated in the core. Therefore, it is necessary to work the pertaining elements with a very high degree of accuracy in finishing in order to prevent play of the core with respect to the base member and keep the magnet and the core at appropriate positions relative to each other. 
         [0009]    Therefore, it is demanded to provide a light amount adjustment apparatus and an image pickup apparatus wherein play of a core with respect to a base member is prevented without raising the accuracy in finishing of pertaining elements. 
         [0010]    According to an embodiment of the present invention, there is provided a light amount adjustment apparatus including a light amount adjustment member configured to be operated in a predetermined direction to adjust the amount of light transmitted through a lens group, a rotatable magnet formed in a disk shape, a driving arm configured to be pivoted by rotation of the magnet to operate the light amount adjustment member, a core having a pair of confronting portions positioned so as to sandwich the magnet from an outer circumference side and a connecting portion configured to connect end portions of the confronting portions to each other, a coil through which one of the confronting portions of the core extends, and a base member having the core attached to the base member and supporting the magnet for rotation on the base member, the base member having a plurality of attaching projections provided at least at two places of the base member for attaching the core to the base member, the attaching projections having a small projection for fitting with the core. 
         [0011]    In the light amount adjustment apparatus, the core is attached to the base member in a state wherein it is force fitted between the attaching projections with the small protrusion of the attaching projections pressed against the core. 
         [0012]    With the light amount adjustment apparatus, play of the core with respect to the base member can be prevented without raising the working accuracy of pertaining elements relating to the attachment of the core to the base member. 
         [0013]    The light amount adjustment apparatus may be configured such that the core has a circular attached hole formed in the core, and one of the attaching projections which is inserted in the attached hole is formed in a substantially cylindrical shape and has at least two small protrusions in a spaced relationship from each other in a circumferential direction on an outer circumferential face of the attaching projections. With the light amount adjustment apparatus, stabilization of the attaching state of the core to the base member can be anticipated. 
         [0014]    The light amount adjustment apparatus may be configured such that the attaching projections include first and second sandwiching portions configured to sandwich the core between the first and second sandwiching portions, the first sandwiching portion having a small protrusion provided on the first sandwiching portion, the second sandwiching portion having a pressed portion formed on the second sandwiching portion such that the core is pressed in a face contacting relationship against the pressed portion. With the light amount adjustment apparatus, the core is attached to the base member in a state wherein it is held in face contact with the pressed face of the second sandwiching portion. Consequently, a stabilized attaching state of the core can be assured. 
         [0015]    The attaching projections may be provided in the proximity of the magnet. With the light amount adjustment apparatus, the positional accuracy between the magnet and the core is improved, and reliability of operation of the light amount adjustment member can be assured. 
         [0016]    The attaching projections may be provided at least at two positions on the opposite sides with respect to the coil in an axial direction. With the light amount adjustment apparatus, the distance between one and the other of the attaching projections is long, and consequently, stabilization of the attaching state of the core to the base member can be anticipated. 
         [0017]    According to another embodiment of the present invention, there is provided an image pickup apparatus including a lens barrel having a predetermined lens group disposed inside, an apparatus body configured to support the lens barrel, and a light amount adjustment apparatus incorporated in the lens barrel and configured to adjust the amount of light fetched through the lens group, the light amount adjustment apparatus having a light amount adjustment member configured to be operated in a predetermined direction to adjust the amount of light transmitted through a lens group, a rotatable magnet formed in a disk shape, a driving arm configured to be pivoted by rotation of the magnet to operate the light amount adjustment member, a core having a pair of confronting portions positioned so as to sandwich the magnet from an outer circumference side and a connecting portion configured to connect end portions of the confronting portions to each other, a coil through which one of the confronting portions of the core extends, and a base member having the core attached to the base member and supporting the magnet for rotation on the base member, the base member having a plurality of attaching projections provided at least at two places of the base member for attaching the core to the attaching projections, the attaching projections having a small projection for fitting with the core. 
         [0018]    In the image pickup apparatus, the core is attached to the base member in a state wherein it is force fitted between the attaching projections with the small protrusion of the attaching projections pressed against the core. 
         [0019]    With the image pickup apparatus, play of the core with respect to the base member can be prevented without raising the working accuracy of pertaining elements relating to the attachment of the core to the base member. 
         [0020]    The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a perspective view showing an image pickup apparatus to which the present invention is applied in a state wherein a lens barrel is accommodated in an apparatus body; 
           [0022]      FIG. 2  is a similar view but showing the image pickup apparatus in another state wherein the lens barrel is projected from the apparatus body; 
           [0023]      FIG. 3  is a perspective view of the image pickup apparatus in a state wherein it is viewed from the opposite side to that in  FIGS. 1 and 2 ; 
           [0024]      FIG. 4  is an explode perspective view of the lens barrel; 
           [0025]      FIG. 5  is an enlarged perspective view of the lens barrel; 
           [0026]      FIG. 6  is an enlarged cross sectional view of the lens barrel in a collapsed position; 
           [0027]      FIG. 7  is an enlarged perspective view showing an intermediate movable unit and a light amount adjustment apparatus of the lens barrel in a disassembled state; 
           [0028]      FIG. 8  is an enlarged perspective view of a second movable unit of the lens barrel; 
           [0029]      FIG. 9  is an exploded perspective view of the light amount adjustment apparatus; 
           [0030]      FIG. 10  is an enlarged perspective view of the light amount adjustment apparatus; 
           [0031]      FIG. 11  is an enlarged perspective view of a base member of the light amount adjustment apparatus; 
           [0032]      FIG. 12  is an enlarged front elevational view showing a first actuator and a second actuator of the light amount adjustment apparatus in a state attached to the base member; 
           [0033]      FIG. 13  is an enlarged exploded perspective view showing a cover plate and shutter blades of the light amount adjustment apparatus; 
           [0034]      FIG. 14  is an enlarged exploded perspective view of a filter blade of the light amount adjustment apparatus; and 
           [0035]      FIG. 15  is an enlarged perspective view of the filter blade. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    In the following, a preferred embodiment of the present invention is described in detail with reference to the accompanying drawings. 
         [0037]    In the embodiment described below, the present invention is applied to a still camera. It is to be noted that the application of the present invention is not limited to a still camera, but the present invention can be applied widely, for example, to video cameras and various image pickup apparatus incorporated in various other apparatus. 
         [0038]    In the following description, the directions such as forward, backward, upward, downward, leftward and rightward directions are represented as directions as viewed from an image pickup person upon image pickup of the still camera. Accordingly, the image pickup object side is represented as the front side while the image pickup person side is represented as the rear side. 
         [0039]    It is to be noted that the forward, backward, upward, downward, leftward and rightward directions used in the following description are determined for the convenience of description, but such directions can be applied suitably when the present invention is carried out. 
         [0040]    Referring first to  FIGS. 1 and 2 , the image pickup apparatus  1  shown includes an apparatus body  2  and a lens barrel  3  supported for movement in forward and backward directions, that is, in the opposite directions of an optical axis, on the apparatus body  2 . When the image pickup apparatus  1  is not used for image pickup or in a like case, the lens barrel  3  is accommodated in the apparatus body  2  as seen in  FIG. 1 , but when the image pickup apparatus  1  is used for image pickup or in some other case, the lens barrel  3  is projected forwardly from the apparatus body  2  as seen in FIG.  2 . Thus, in the present image pickup apparatus  1 , the lens barrel  3  is formed as a lens barrel of the collapsible type. 
         [0041]    Since the image pickup apparatus  1  includes the collapsible lens barrel  3 , both of miniaturization or reduced thickness in a non-image pickup state of the image pickup apparatus  1  and assurance of a good optical performance in an image pickup state. 
         [0042]    Referring to  FIGS. 1 to 3 , the apparatus body  2  has various elements disposed on the inner side and the outer side of a housing  4  of a horizontally elongated and flattened outer profile. 
         [0043]    A flash  5  and a finder window  6  are provided on the front face of the apparatus body  2 . A shutter button  7 , a mode changeover dial  8  and a power supply button  9  are provided on the top face of the apparatus body  2 . A battery cover  10  is provided on the right face of the apparatus body  2  such that it can be opened or closed to allow insertion and removal of a battery not shown into and from the apparatus body  2 . A finder  11 , a zoom switch  12 , a display screen  13 , operation buttons  14  and a terminal cover  15  are provided on the rear face of apparatus body  2 . A power supply terminal, input and output terminals and so forth not shown are provided on the inner side of the terminal cover  15 . 
         [0044]    Referring now to  FIGS. 4 to 6 , the lens barrel  3  includes a fixation member  16 , a fixation ring  17  secured to the fixation member  16 , and a cam cylinder  18  supported for rotation on the fixation ring  17 . The lens barrel  3  further includes a first movable unit  19  supported for movement in the forward and backward directions, that is, in the directions of the optical axis, on the cam cylinder  18 . 
         [0045]    The fixation member  16  includes a base plate portion  20  formed in a substantially plate form and directed in the forward and backward directions, and an attaching projection  21  projecting forwardly from a lower end portion of the base plate portion  20 . 
         [0046]    A guide rod  22  is attached to the base plate portion  20 . 
         [0047]    A focusing motor unit  23  is attached to the attaching projection  21 . A focusing movement unit  24  is moved in the forward and backward direction, that is, in the opposite directions of the optical axis, by the focusing motor unit  23 . The focusing movement unit  24  includes a holding arm  25 , and a focusing lens group  26  attached to the holding arm  25 . 
         [0048]    When the focusing motor unit  23  is driven, the focusing movement unit  24  is moved in a direction of the optical axis under the guidance of the guide rod  22 . 
         [0049]    An image pickup unit  27  is attached to a rear portion of the fixation member  16  as seen in  FIG. 4 . The image pickup unit  27  includes a holding frame member  28 , and an image pickup element  29  such as, for example, a CCD (Charge Coupled Device) unit, held by the holding frame member  28 . The image pickup unit  27  is attached at the holding frame member  28  thereof to the fixation member  16 . 
         [0050]    The fixation ring  17  is attached to the front of the fixation member  16  as seen in  FIGS. 4 and 5 . The fixation ring  17  has a cylindrical base portion  30  formed in a substantially cylindrical shape, a unit holding down portion  31  projecting from an lower end portion of the right end side of the cylindrical base portion  30 , and a case attaching portion  32  projecting from a lower end portion of the left end side of the cylindrical base portion  30 . 
         [0051]    A gear arrangement hole not shown is formed at a position of the cylindrical base portion  30  corresponding to the case attaching portion  32 . 
         [0052]    In a state wherein the fixation ring  17  is attached to the fixation member  16 , the guide rod  22  and the focusing motor unit  23  are held from forwardly by the unit holding down portion  31 . 
         [0053]    In the state wherein the fixation ring  17  is attached to the fixation member  16 , a transmission gear  33  elongated in the axial direction is supported for rotation between the case attaching portion  32  and the fixation member  16 . The transmission gear  33  is disposed in the gear arrangement hole formed in the cylindrical base portion  30 . 
         [0054]    A case body  34  is attached to the case attaching portion  32  of the fixation ring  17 . 
         [0055]    A motor  35  is attached in the case body  34  as seen in  FIG. 4 . A transmission gear group not shown is disposed in the case body  34  and held in meshing engagement with the transmission gear  33 . When the motor  35  rotates, the driving force thereof is transmitted to the transmission gear  33  through the transmission gear group. 
         [0056]    The case body  34  is attached to the fixation ring  17  and the fixation member  16  through an attaching leaf spring  36 . 
         [0057]    The cam cylinder  18  is supported for movement in the backward and forward directions and for rotation in a circumferential direction on the fixation ring  17  (referred to as  FIGS. 4 and 6 ). 
         [0058]    The cam cylinder  18  is substantially in a ring shape and has a rack gear  18   a  provided at part of an outer circumferential face at a rear end thereof. 
         [0059]    The cam cylinder  18  is supported for movement in the backward and forward directions and for rotation in a circumferential direction on the fixation ring  17 . 
         [0060]    In the state wherein the cam cylinder  18  is supported on the fixation ring  17 , the rack gear  18   a  meshes with the transmission gear  33  supported for rotation between the fixation member  16  and the fixation ring  17 . Accordingly, when the motor  35  held on the case body  34  rotates, the driving force thereof is transmitted to the rack gear  18   a  through the transmission gear set and the transmission gear  33  so that the cam cylinder  18  is rotated in a direction corresponding to the direction of rotation of the motor  35 . Consequently, the cam cylinder  18  is moved in the forward or backward direction while it rotates relative to the fixation ring  17 . 
         [0061]    A straightforward guide  37  is supported for movement in the backward and forward directions on the fixation ring  17 . The straightforward guide  37  is formed as a unitary member from an annular portion  38  and three guide projections  39  projecting forwardly from the annular portion  38 . 
         [0062]    The straightforward guide  37  is supported for movement in the forward and backward directions and for rotation relative to the cam cylinder  18  on the fixation ring  17 . 
         [0063]    An ornamental ring  40  is attached to a front half of the fixation ring  17  as seen in  FIGS. 4 and 6 . 
         [0064]    A second movable unit  41  is supported on the cam cylinder  18  as seen in  FIG. 6 . The second movable unit  41  includes an intermediate movable unit  42  and a light amount adjustment apparatus  43  attached to the intermediate movable unit  42  as seen in  FIG. 7 . 
         [0065]    The intermediate movable unit  42  includes several members supported on or attached to a base frame  44 . 
         [0066]    The base frame  44  includes a disk portion  45 , and a supported face portion  46  provided on an outer circumferential portion of the disk portion  45 . 
         [0067]    A transmission opening  45   a  is formed at a central portion of the disk portion  45  such that it extends forwardly and backwardly through the disk portion  45 . 
         [0068]    A first correcting movable frame  47  is supported for movement in the leftward and rightward directions on the front face side of the base frame  44 . A second correcting movable frame  48  is supported for movement in the upward and downward directions on the first correcting movable frame  47 . A lens group  48   a  is attached to the second correcting movable frame  48 . 
         [0069]    A circuit board  49  is attached to the front face of the second correcting movable frame  48 . 
         [0070]    As described hereinabove, the first correcting movable frame  47  is supported on the base frame  44  while the second correcting movable frame  48  is supported on the first correcting movable frame  47 , and in a state wherein the circuit board  49  is attached to the second correcting movable frame  48 , an outer core  50  is attached to the front face of the base frame  44  to construct the intermediate movable unit  42 . 
         [0071]    The light amount adjustment apparatus  43  is attached to the rear face side of the intermediate movable unit  42 , and the second movable unit  41  is formed from the intermediate movable unit  42  and the light amount adjustment apparatus  43  (as reference to  FIGS. 7 and 8 ). 
         [0072]    The second movable unit  41  is supported for movement in the forward and backward directions on the guide projections  39  of the straightforward guide  37  and supported for sliding movement on the cam cylinder  18 . Accordingly, the second movable unit  41  is moved in the forward direction or the backward direction, that is, in a direction of the optical axis, under the guidance of the straightforward guide  37  by rotation of the cam cylinder  18 . 
         [0073]    The light amount adjustment apparatus  43  is attached to the rear face side of the base frame  44  as seen in  FIGS. 7 and 8 . 
         [0074]    The light amount adjustment apparatus  43  includes a base member  51  and several members supported on or attached to the base member  51  as seen in  FIGS. 7 to 10 . 
         [0075]    The base member  51  is formed in a substantially ring shape and has a mounting recessed portion  53  opened forwardly at a portion thereof except an outer circumferential portion  52  on the front face side as seen in  FIG. 11 . The base member  51  is formed at a portion thereof, at which the mounting recessed portion  53  is formed, with a thickness smaller than that of the outer circumferential portion  52 . 
         [0076]    A large perforation  53   a  is formed in the mounting recessed portion  53 . A filter pivotal motion center shaft  53   b  and shutter pivotal motion center shafts  53   c  and  53   d  are provided at positions of the mounting recessed portion  53  around the perforation  53   a  such that they project forwardly. Arcuate fitting holes  53   e  and  53   f  are formed at the mounting recessed portion  53  such that they project forwardly and backwardly through the mounting recessed portion  53 . 
         [0077]    The filter pivotal motion center shaft  53   b  and the shutter pivotal motion center shafts  53   c  and  53   d  are positioned substantially on the opposite sides to each other across the perforation  53   a . The shutter pivotal motion center shafts  53   c  and  53   d  are positioned in a spaced relationship from each other in a circumferential direction, and the fitting hole  53   e  is positioned in the proximity of the filter pivotal motion center shaft  53   b  while the fitting hole  53   f  is positioned between the shutter pivotal motion center shafts  53   c  and  53   d.    
         [0078]    Two sets of attaching projections  51   a ,  51   b  and  51   c  are provided on the rear face of the base member  51  such that they project rearwardly. The attaching projections  51   a ,  51   b  and  51   c  in one set are used to attach a first actuator hereinafter described to the base member  51 , and the attaching projections  51   a ,  51   b  and  51   c  in the other set are used to attach a second actuator hereinafter described to the base member  51 . 
         [0079]    The attaching projection  51   a  is formed in a substantially cylindrical shape and has, for example three small protrusions  51   d  provided on an outer circumferential face thereof in a spaced relationship from each other in the circumferential direction. 
         [0080]    The attaching projection  51   b  and the attaching projection  51   c  are provided in an opposing relationship to each other. A small protrusion  51   e  is provided on a face of the attaching projection  51   b , which is positioned on the outer side, opposing to the attaching projection  51   c . The attaching projection  51   c  positioned on the inner side is formed at a face thereof opposing to the attaching projection  51   b  as a pushed face  51   f.    
         [0081]    A cover plate  54 , a first separator  55  and a second separator  56  are attached to the front face side of the base member  51  as seen in  FIGS. 9 and 10 . 
         [0082]    The cover plate  54  is formed, for example, from a metal material and has a covering portion  57  directed in the forward and backward directions, and attached projections  58  projecting rearwardly from outer circumferential portions of the straightforward guide  37 . 
         [0083]    A light passing hole  57   a  smaller than the perforation  53   a  of the base member  51  is formed at a central portion of the covering portion  57 . A pair of first sliding projections  57   b  and a pair of second sliding projections  57   c  are formed on the covering portion  57  so as to be swollen rearwardly by stamping as seen in  FIGS. 9 and 13 . 
         [0084]    Three shaft insertion holes  57   d ,  57   e  and  57   f  and two arcuate fitting holes  57   g  and  57   h  are formed at outer circumferential portions of the covering portion  57 . The shaft insertion hole  57   d  and the shaft insertion holes  57   e  and  57   f  are formed on the substantially opposite sides to each other across the light passing hole  57   a , and the shaft insertion holes  57   e  and  57   f  are positioned in a spaced relationship from each other in the circumferential direction. Further, the fitting hole  57   g  is positioned in the proximity of the shaft insertion hole  57   d , and the fitting hole  57   h  is positioned between the shaft insertion holes  57   e  and  57   f.    
         [0085]    Referring to  FIG. 9 , the first separator  55  has a transmission hole  55   a  formed at a central portion thereof with a size substantially equal to that of the light passing hole  57   a  of the cover plate  54 . Three shaft insertion holes  55   b ,  55   c  and  55   d  and arcuate fitting holes  55   e  and  55   f  are formed at outer circumferential portions of the first separator  55 . The shaft insertion hole  55   b  and the shaft insertion holes  55   c  and  55   d  are positioned on the substantially opposite sides to each other across the transmission hole  55   a , and the shaft insertion holes  55   c  and  55   d  are positioned in a spaced relationship from each other in the circumferential direction. Further, the fitting hole  55   e  is positioned in the proximity of the shaft insertion hole  55   b , and the fitting hole  55   f  is positioned between the shaft insertion holes  55   c  and  55   d.    
         [0086]    The second separator  56  has a transmission hole  56   a  formed at a central portion thereof with a size substantially equal to that of the light passing hole  57   a  of the cover plate  54 . Two shaft insertion holes  56   b  and  56   c  and two arcuate fitting holes  56   d  and  56   e  are formed at outer circumferential portions of the second separator  56 . The shaft insertion hole  56   b  and the shaft insertion hole  56   c  are positioned on the substantially opposite sides to each other across the transmission hole  56   a , and the fitting holes  56   d  and  56   e  are positioned in the proximity of the shaft insertion holes  56   b  and  56   c , respectively. 
         [0087]    A pair of shutter blades  59  and  60  and a filter blade  61  are supported for pivotal motion on the base member  51  as seen in  FIGS. 9 and 13 . The shutter blades  59  and  60  and the filter blade  61  function as light amount adjustment members for adjusting the amount of light to be fetched into the image pickup apparatus  1  through the perforation  53   a  of the base member  51 . 
         [0088]    The shutter blades  59  and  60  are each formed from a material in the form of a sheet and have shaft insertion holes  59   a  and  60   a  and action holes  59   b  and  60   b  formed at one end portion thereof. The action holes  59   b  and  60   b  are elongated in one direction. 
         [0089]    Referring to  FIGS. 14 and 15 , the filter blade  61  is from two sheet members  63  formed on the opposite faces of a dimming filter  62  and coupled in a laminated state to each other. Each of the sheet members  63  has a circular hole  63   a  formed therein. The circular hole  63   a  has a diameter greater than that of the transmission hole  55   a  of the first separator  55 . Accordingly, the filter blade  61  is exposed at the dimming filter  62  thereof at a position corresponding to the circular holes  63   a . The exposed portion of the filter blade  61  is provided as a control portion  62   a  which controls and adjusts the amount of light. The dimming filter  62  is formed from an ND (Neutral Density) filter. 
         [0090]    The filter blade  61  has formed at one end portion thereof a shaft insertion hole  61   a  and an action hole  61   b  which is elongated in one direction. 
         [0091]    The second separator  56  is disposed at the mounting recessed portion  53  of the base member  51 , and the filter pivotal motion center shaft  53   b  and the shutter pivotal motion center shaft  53   c  of the base member  51  are inserted in the shaft insertion holes  56   b  and  56   c  of the second separator  56 , respectively. The shutter pivotal motion center shaft  53   d  is positioned on the immediately outer side of the second separator  56 . 
         [0092]    The filter blade  61  is supported on the front face side of the second separator  56  as seen in  FIG. 9 . The filter pivotal motion center shaft  53   b  of the base member  51  is inserted in the shaft insertion hole  61   a  of the filter blade  61  such that the filter blade  61  is supported for pivotal motion around the filter pivotal motion center shaft  53   b  on the base member  51 . 
         [0093]    The filter blade  61  has such a three-member configuration that the sheet members  63  are coupled in a layered fashion to the opposite faces of the dimming filter  62  as described hereinabove such that otherwise possible damage to the dimming filter  62  upon pivotal motion of the dimming filter  62  between the first separator  55  and the second separator  56  can be prevented. 
         [0094]    In a state wherein the first separator  55  is attached to the base member  51 , the shutter blades  59  and  60  are supported for pivotal motion on the base member  51  as seen in  FIG. 13 . In particular, the shutter pivotal motion center shafts  53   c  and  53   d  of the base member  51  are inserted in the shaft insertion holes  59   a  and  60   a  of the shutter blades  59  and  60 , respectively. Consequently, the shutter blades  59  and  60  are supported in a partially overlapping relationship with each other for pivotal motion around the shutter pivotal motion center shafts  53   c  and  53   d  of the base member  51  on the base member  51 , respectively. 
         [0095]    In a state wherein the shutter blades  59  and  60  are supported on the base member  51 , the cover plate  54  is attached to the base member  51  as seen in  FIGS. 9 and 10 . The cover plate  54  is attached to the base member  51  with the attached projections  58  thereof engaged with the outer circumferential portion  52  of the base member  51 . Accordingly, the shutter blades  59  and  60  are disposed for pivotal motion between the cover plate  54  and the first separator  55 . 
         [0096]    A first actuator  64  and a second actuator  65  are attached to the rear face of the base member  51  as seen in  FIGS. 9 and 12 . 
         [0097]    The first actuator  64  has a core  66 , and a coil  67 , a magnet  68  and a driving arm  69  held on the core  66 . The driving arm  69  has a base portion  69   a , and an arm portion  69   b  projecting forwardly from the base portion  69   a . A driving pin  69   c  is provided at a free end portion of the arm portion  69   b.    
         [0098]    The core  66  has a pair of confronting portions  66   a  and  66   b  positioned so as to sandwich the magnet  68  therebetween from an outer circumference side, and a connecting portion  66   c  for connecting end portions of the confronting portions  66   a  and  66   b  to each other. The other end portions of the confronting portions  66   a  and  66   b  are formed arcuately along the outer circumferential face of the magnet  68 . 
         [0099]    The second actuator  65  has a core  70 , and a coil  71 , a magnet  72  and a driving arm  73  held on the core  70 . The driving arm  73  has a base portion  73   a , and an arm portion  73   b  projecting forwardly from the base portion  73   a . A driving pin  73   c  is provided at a free end portion of the arm portion  73   b.    
         [0100]    The core  70  has a pair of confronting portions  70   a  and  70   b  positioned so as to sandwich the magnet  72  from an outer circumference side, and a connecting portion  70   c  for interconnecting end portions of the confronting portions  70   a  and  70   b . End portions of the confronting portions  70   a  and  70   b  are shaped arcuately along the outer circumferential face of the magnet  68 . 
         [0101]    The connecting portions  66   c  and  70   c  of the cores  66  and  70  have circular attached holes  66   d  and  70   d  formed therein, respectively. 
         [0102]    The first actuator  64  and the second actuator  65  exert rotating force between the cores  66  and  70  and the magnets  68  and  72  in response to current flowing through the coils  67  and  71 , respectively. By the rotating force, the driving arms  69  and  73  are pivoted in a direction corresponding to the direction of the current flowing through the coils  67  and  71 , respectively. 
         [0103]    The first actuator  64  and the second actuator  65  are attached to positions of the base member  51  spaced away from each other in a circumferential direction while they are held from rearwardly by a holding plate  74  as seen in  FIGS. 7 to 9 . 
         [0104]    The first actuator  64  and the second actuator  65  are attached to the base member  51  by means of the attaching projections  51   a ,  51   b  and  51   c  as seen in  FIG. 12 . 
         [0105]    The first actuator  64  is attached to the base member  51  such that the attaching projection  51   a  is inserted in the attached hole  66   d  of the core  66  and a free end side portion of the confronting portion  66   a  of the core  66  is inserted and fitted between the attaching projections  51   b  and  51   c.    
         [0106]    In a state wherein the first actuator  64  is attached to the base member  51 , the attaching projection  51   a  is force fitted in the attached hole  66   d  with the small protrusions  51   d  interposed therebetween and the free end side portion of the confronting portion  66   a  of the core  66  is force fitted between the attaching projections  51   b  and  51   c  with the small protrusion  51   e  interposed therebetween while the core  66  is pressed in a face-contacting relationship against the pushed face  51   f  of the attaching projection  51   c . Accordingly, the first actuator  64  is secured to the base member  51 . 
         [0107]    Since the free end side portion of the confronting portion  66   a  of the core  66  is forced fitted between and sandwiched by the attaching projections  51   b  and  51   c , the attaching projections  51   b  and  51   c  function as first and second sandwiching portions, respectively. 
         [0108]    Also the second actuator  65  is attached to the base member  51  in a similar manner to the first actuator  64 . In particular, the attaching projection  51   a  is inserted and fitted in the attached hole  66   d  of the core  66 , and a free end side portion of the confronting portion  66   a  of the core  66  is inserted and fitted between the attaching projections  51   b  and  51   c  so to attach and secure the second actuator  65  to the base member  51 . 
         [0109]    As described above, in the image pickup apparatus  1 , since the attaching projections  51   a  and  51   b  having the small protrusions  51   d  and  51   e  are provided at two locations of the base member  51  to secure the first actuator  64  and the second actuator  65 , play of the first actuator  64  and the second actuator  65  with respect to the base member  51  can be prevented without the necessity to raise the working accuracy for various portions relating to attachment of the first actuator  64  and the second actuator  65  to the base member  51 . 
         [0110]    Further, since the circular attached holes  66   d  and  70   d  are formed in the cores  66  and  70 , respectively, and the three small protrusions  51   d  are provided in a spaced relationship from each other in a circumferential direction on the outer circumferential face of the attaching projection  51   a , stabilization of the attaching state of the first actuator  64  and the second actuator  65  to the base member  51  can be anticipated. 
         [0111]    Further, since the small protrusion  51   e  is provided on the attaching projection  51   b  and the pushed face  51   f  is formed on the attaching projection  51   c , the core  66  is attached to the base member  51  in a state wherein the free end side portion of the confronting portion  66   a  of the core  66  is held in face contact with the pushed face  51   f . Consequently, a stabilized attachment state of the first actuator  64  and the second actuator  65  can be assured. 
         [0112]    Furthermore, since the attaching projection  51   b  and the attaching projection  51   c  are positioned in the proximity of the magnets  68  and  72 , the positional accuracy between the circumferential faces of the magnets  68  and  72  and the opposing faces of the cores  66  and  70  is improved. Consequently, high reliability in operation of the first actuator  64  and the second actuator  65  can be assured. 
         [0113]    In addition, since the attaching projection  51   a  and the attaching projections  51   b  and  51   c  are positioned on the opposite sides to each other with respect to each of the coils  67  and  71 , the distance between the attaching projection  51   a  and the attaching projections  51   b  and  51   c  is so great that stabilization of the attaching state of the first actuator  64  and the second actuator  65  to the base member  51  can be anticipated. 
         [0114]    It is to be noted that, while the three small protrusions  51   d  are provided on the attaching projection  51   a  described above, the number of such small protrusions  51   d  provided on the attaching projection  51   a  is not limited to three but may be any number equal to or greater than two. 
         [0115]    Further, while the small protrusion  51   e  is provided on the attaching projection  51   b  and the pushed face  51   f  is formed on the attaching projection  51   c  as described above, conversely the pushed face may be formed on the attaching projection  51   b  while the small projection is provided on the attaching projection  51   c.    
         [0116]    In the state wherein the first actuator  64  and the second actuator  65  are attached to the base member  51 , the driving pin  69   c  of the driving arm  69  is fitted in order into the fitting hole  53   f  of the base member  51 , the shaft insertion hole  56   e  of the second separator  56 , the action holes  59   b  and  60   b  of the shutter blades  59  and  60 , the fitting hole  55   f  of the first separator  55  and the fitting hole  57   h  of the cover plate  54 . Meanwhile, the driving pin  73   c  of the driving arm  73  is fitted in order into the fitting hole  53   e  of the base member  51 , the fitting hole  56   d  of the second separator  56 , the action hole  61   b  of the filter blade  61 , the fitting hole  55   e  of the first separator  55  and the fitting hole  57   g  of the cover plate  54 . 
         [0117]    As regards driving of the shutter blades  59  and  60 , the shutter blades  59  and  60  are pivoted in the opposite directions to each other by pivotal motion of the driving arm  69  to open or close the perforation  53   a.    
         [0118]    As regards driving of the filter blade  61 , the filter blade  61  is pivoted by pivotal motion of the driving arm  73  to open or close the perforation  53   a.    
         [0119]    A wiring line plate  75  is attached to the rear face of the holding plate  74  as seen in  FIG. 4 . The wiring line plate  75  is connected to the coils  67  and  71  and has a function of supplying power to the coils  67  and  71 . 
         [0120]    The light amount adjustment apparatus  43  configured in such a manner as described above is attached to the intermediate movable unit  42  with the base member  51  thereof engaged with the base frame  44 , and the second movable unit  41  is formed from the intermediate movable unit  42  and the light amount adjustment apparatus  43 . 
         [0121]    The first movable unit  19  includes a movable frame  76  and a lens group  77  held on the movable frame  76  as seen in  FIGS. 4 and 6 . The lens group  77  is attached to a central portion of the movable frame  76  through a lens holder  78 . 
         [0122]    The first movable unit  19  is supported at the movable frame  76  thereof for sliding motion on the guide projections  39  of the straightforward guide  37  and supported for sliding motion on the cam cylinder  18 . Accordingly, the first movable unit  19  is moved in the forward or backward direction, that is, in a direction of the optical axis, under the guidance of the straightforward guide  37  by rotation of the cam cylinder  18 . 
         [0123]    A lens barrier  79  is attached to the front face side of the first movable unit  19  as seen in  FIGS. 4 and 6 . 
         [0124]    In a state wherein the lens barrier  79  is attached to the first movable unit  19 , an ornamental ring  80  is attached to the outer face side of the movable frame  76  and the lens barrier  79 . 
         [0125]    While a preferred embodiment of the present invention has been described using specific terms, such description is for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.