Abstract:
A vibration reduction mechanism, comprising: a first moving member and a second moving member which move relatively at a time of image blur correction; a guide member which guides relative movements of the first moving member and the second moving member; a plurality of first engagement portions, aligned in a row, which engage the first moving member with the guide member by spherical or cylindrical surfaces and groove-shaped portions; and a plurality of second engagement portions, aligned in a row, which engage the second moving member with the guide member by spherical or cylindrical surfaces and groove-shaped portions, wherein a groove shape of at least either one of the plurality of the first engagement portions or the plurality of the second engagement portions is formed with an elongated hole shape extending along an alignment direction of the first engagement portions aligned in a row.

Description:
[0001]    The disclosure of the following priority applications is herein incorporated by reference: Japanese Patent Application No. 2006-279579 filed on Oct. 13, 2006. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a vibration reduction mechanism having a mechanism to correct blur of an optical system and an optical device using the vibration reduction mechanism. 
         [0004]    2. Description of Related Art 
         [0005]    There is known an optical device provided with a vibration reduction mechanism, in which a lens frame body is movable along a prescribed direction by sliding on a guide axis and rotates around the guide axis so that lens is supported to be movable along a direction perpendicular to the prescribed direction (for example, refer to Japanese Unexamined Patent Application Publication No. H10-3102). 
         [0006]    However, the above-mentioned vibration reduction mechanism has the disadvantage of including many constituent mechanical elements, thereby resulting in an insufficient regulation of the rotation of the lens frame body, due to errors and looseness between the constituent mechanical elements, which may be detrimental to the accuracy of the driving control of the vibration reduction mechanism. 
       SUMMARY OF THE INVENTION 
       [0007]    An object of the present invention is to provide a vibration reduction mechanism having a guide mechanism to guide a lens frame body, with a simple structure, and with high accuracy, and further to provide an optical device using the same. 
         [0008]    The present invention solves the above-mentioned problems in accordance with the following solving means. 
         [0009]    According to the first aspect of the present invention, a vibration reduction mechanism, comprises: a first moving member and a second moving member which move relatively at a time of blur correction; a guide member which guides relative movement of the first moving member and the second moving member; a plurality of first engagement portions, aligned in a row, which engage the first moving member and the guide member by spherical or cylindrical surfaces and groove-shaped portions; and a plurality of second engagement portions, aligned in a row, which engage the second moving member with the guide member by spherical or cylindrical surfaces and groove-shaped portions, wherein a groove shape of at least either one of the plurality of the first engagement portions or the plurality of the second engagement portions is formed with an elongated hole shape extending along an alignment direction of the first engagement portions aligned in a row. 
         [0010]    In the vibration reduction mechanism the spherical, cylindrical surface, or groove-shaped portions of the first engagement portion and the second engagement portion may be integrally formed with the guide member. 
         [0011]    The vibration reduction mechanism may further comprises one or more regulation portions between the first or second moving member and the guide member to regulate the relative movements along the alignment direction of the plurality of the first engagement portions aligned in a row. 
         [0012]    According to the second aspect of the present invention, an optical device, includes a vibration reduction mechanism, comprising: a first moving member and a second moving member which move relatively at a time of image blur correction; a guide member which guides relative movements of the first moving member and the second moving member; a plurality of first engagement portions, aligned in a row, which engage the first moving member with the guide member by spherical or cylindrical surfaces and groove-shaped portions; and a plurality of second engagement portions, aligned in a row, which engage the second moving member with the guide member by spherical or cylindrical surfaces and groove-shaped. 
         [0013]    In accordance with the present invention, there are provided, in the vibration reduction mechanism, the first and second engagement portions, both having groove-shaped portions to engage with the spherical or cylindrical-shaped portions of the following guide member, the above-mentioned first and second engagement portions being disposed both between the guide member and the first moving member and between the guide member and the second moving member. Therefore, the first and second moving members can be relatively moved by means of a simple structure along a two-axis direction, without any relative rotation, with a constant orientation, and with a precise accuracy. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a block diagram showing an embodiment of a camera as a whole in accordance with the present invention. 
           [0015]      FIG. 2  shows a lens barrel unit of the camera in accordance with the present invention. 
           [0016]      FIG. 3  shows a vibration reduction mechanism of the camera in accordance with the present invention. 
           [0017]      FIG. 4  is an A-A cross sectional view of the vibration reduction mechanism of the camera in accordance with the present invention. 
           [0018]      FIG. 5A  and  FIG. 5B  show a B-B cross sectional view of the vibration reduction mechanism of the camera in accordance with the present invention. 
           [0019]      FIG. 6  is a perspective view of a guide member of the vibration reduction mechanism in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    In the following, referring to the drawings, an embodiment of the present invention is described in more detail. 
         [0021]      FIG. 1  is a block diagram showing an embodiment of a camera as a whole in accordance with the present invention.  FIG. 2  shows a lens barrel unit of the camera.  FIG. 3  is a plain view showing a vibration reduction mechanism provided in a lens barrel unit.  FIG. 4  is an A-A cross sectional view of  FIG. 3 .  FIG. 5A  and  FIG. 5B  show a B-B cross sectional view of  FIG. 3 .  FIG. 6  is a perspective view of a guide member of the vibration reduction mechanism. For clarity, in  FIG. 2  through  FIG. 5B , the direction of light A 1  which incidents to the camera  10  from a subject is shown as X direction, while the direction of the light A 2  orthogonal to the light A 1  is shown as the Z direction. Further, the Y direction is orthogonal both to the X direction and Z direction. 
         [0022]    A camera  10  as shown in  FIG. 1  is a digital camera including: a control unit  11 ; a display unit  12 ; a memory unit  13 ; an operation unit  14 ; a gyro sensor  15 ; a lens barrel unit  20 ; and a vibration reduction mechanism unit  30 . 
         [0023]    The control unit  11  is a CPU to supervise and control each unit of the camera  10 , and further has a function to control the after-mentioned vibration reduction mechanism unit  30  in response to an output signal from a position detector  36  of the vibration reduction mechanism unit  30  and the gyro sensor  15 . 
         [0024]    The display unit  12  is, for example, a liquid crystal display to display the images photographed by the camera  10  and the operating information. 
         [0025]    The memory unit  13  is a memory to store the image data photographed by the camera  10  and the operation data in the camera  10  and so on. 
         [0026]    The operation unit  14  includes a plurality of operation buttons to set up the photographing operations and photographing conditions for the camera  10 , thereby executing operations such as an operation of an after-mentioned shutter diaphragm mechanism unit  29  (cf.  FIG. 2 ), and a zoom operation to drive a third lens unit  24  and a fifth lens unit  26  (cf.  FIG. 2 ). 
         [0027]    The gyro sensor  15  is a sensor to detect an angular velocity of the camera  10 . The gyro sensor  15  detects movement (blurring caused by hand) thereby correcting the image blur caused by hand shake by means of the vibration reduction mechanism unit  30 . The gyro sensor  15  includes two angular velocity sensors, each of which detects a pitching angular velocity (a rotation about the Y axis) and a yawing angular velocity (a rotation about the X axis). 
         [0028]    The lens barrel unit  20  as shown in  FIG. 1  and  FIG. 2  has: a first lens unit  21 ; a prism  22 ; a second lens unit  23 ; a third lens unit  24 ; a fourth lens unit  25 ; a fifth lens unit  26 ; a low pass filter  27 ; a CCD  28 ; a shutter diaphragm mechanism unit  29 ; and the vibration reduction mechanism unit  30 . 
         [0029]    The first lens unit  21  is an objective lens upon which the light from the subject is incident, and the first lens unit  21  is the lens which is the nearest to the subject among the lens units in the lens barrel unit  20 . 
         [0030]    The prism  22  is a rectangular prism to deflect by 90 degrees the incident light, whereby the light A 1  along the +X direction exits from the first lens unit  21  is totally reflected and is deflected by 90 degrees, and the light A 2  along the −Z direction exits toward the second lens unit  23 . 
         [0031]    The second lens unit  23  is disposed at a position upon which the light A 2  exiting from the prism  22  is incident. 
         [0032]    The third lens unit  24  is disposed at a position upon which the light A 2  exiting from the second lens unit  23  is incident. Further, the third lens unit  24  can be moved to any position along the Z direction by a driving mechanism (not shown). 
         [0033]    The forth lens unit  25  is disposed, in a movable frame  31  of the vibration reduction mechanism unit  30 , at a position upon which the light A 2  exiting from the third lens unit  24  is incident. 
         [0034]    The fifth lens unit  26  is disposed at a position upon which the light A 2  exiting from the forth lens unit  25  is incident. Further, the fifth lens unit  26 , similarly to the third lens unit  24 , can be moved to any positions along the Z direction by a driving mechanism (not shown). 
         [0035]    The low pass filter  27  is a filter to pass only a signal of a frequency less than or equal to a prescribed frequency, the low pass filter  27  being provided between the fifth lens unit  26  and the CCD  28  (cf.  FIG. 2 ), thereby preventing moire fringes of the image signal output from the CCD  28 . 
         [0036]    The CCD (Charge-Coupled Device)  28  is a solid state image pick-up device provided at the exit side of the fifth lens unit  26  which can output an electrical image signal based on the light from the subject focused on the image pick-up surface. 
         [0037]    The shutter diaphragm mechanism unit  29  is disposed at the incident side of the fourth lens unit  25  of the vibration reduction mechanism unit  30 . The shutter diaphragm mechanism unit  29  is provided with: a diaphragm portion to regulate a quantity of the subject light passing through the lens barrel unit  20 ; and a shutter unit to adjust the exposure time exposing the CCD  28  for the subject light. 
         [0038]    The vibration reduction mechanism unit  30  as shown in  FIG. 3  has: a movable frame (a first moving member)  31 ; a fixed frame (a second moving member)  32 ; a guide member  33 ; first engagement portions  33 - 1 ; second engagement portions  33 - 2 ; regulation portions  33 - 3 ; a support portion  34 ; voice coil motors (VCMs)  35 ; and position detectors  36 . The movable frame  31  holding the forth lens unit  25  is moved, by means of driving sources of the VCMs  35  as an actuator, in the plane (XY plane) orthogonal to the light A 2 , thereby reducing the image blur caused by the movement of the camera  10  (hand blurring). 
         [0039]    The movable frame  31  holds the fourth lens unit  25  at the center of the movable frame  31 , and is movable in the XY plane relative to the fixed frame  32 . Further, there are provided, in the movable frame  31 , on the surface opposite to the fixed frame  32 , two groove-shaped portions  33 - 1   a  having an elongated hole shape, each of which forms a part of the after-mentioned first engagement portions  33 - 1 . The two groove-shaped portions  33 - 1   a  are spaced at a sufficient distance. 
         [0040]    The fixed frame  32  is provided, at its center, with an opening for the light A 2  exiting from the fourth lens unit  25  to pass through and fixed with the lens barrel unit  20 . There are provided, in the fixed frame  32 , on the surface opposite to the movable frame  31 , two groove-shaped portions  33 - 2   a  having an elongated hole shape, each of which forms a part of the after-mentioned second engagement portions  33 - 2 . The two groove-shaped portions  33 - 2   a  are spaced at a sufficient distance. Further, there are provided, at the above-mentioned same surface of the fixed frame  32 , two concave portions  33 - 3   a , each of which forms a part of the after-mentioned regulation portions  33 - 3 . 
         [0041]    The guide member  33  as shown in  FIG. 4  through  FIG. 6  is a member elongating along the Y direction, and is disposed between the movable frame  31  and the fixed frame  32 . There are provided spherically-shaped portions  33 - 1   b  each of which forms a part of the after-mentioned first engagement portions  33 - 1 , at the two positions on a side (the upper side) of both edge of the guide member  33  opposite to the movable frame  31 . Similarly, there are provided spherically-shaped portions  33 - 2   b  each of which forms a part of the after-mentioned second engagement portions  33 - 2 , at the two positions on another side (the lower side) of guide member  33  opposite to the fixed frame  32 . Further, there are provided, at an edge of the guide member  33  facing to the fixed frame  32 , convex portions  33 - 3   b  each of which forms a part of the after-mentioned regulation portion  33 - 3 , at the two positions spaced by an equal distance from the center of the longitudinal direction (the Y direction). 
         [0042]    The first engagement portions  33 - 1  have: the groove-shaped portions  33 - 1   a ; and the spherically-shaped portions  33 - 1   b . The first engagement portions  33 - 1  form a mechanism to guide the movable frame  31  and the guide member  33  by engaging the groove-shaped portions  33 - 1   a  with the spherically-shaped portions  33 - 1   b . Therefore, both the groove-shaped portions  33 - 1   a  and the spherically-shaped portions  33 - 1   b  are disposed at the corresponding positions opposite to the movable frame  31  and the guide member  33 , respectively, so as to be engaged with each other. The groove-shaped portions  33 - 1   a  are elongated holes extending in the Y direction in the movable frame  31 . 
         [0043]    Similarly to the first engagement portions  33 - 1 , the second engagement portions  33 - 2  have: the groove-shaped portions  33 - 2   a ; and the spherically-shaped portions  33 - 2   b , thereby guiding the fixed frame  32  and the guide member  33  by engaging the groove-shaped portions  33 - 2   a  with the spherically-shaped portions  33 - 2   b . Therefore, the groove-shaped portions  33 - 2   a  and the spherically-shaped portions  33 - 2   b  are disposed at the corresponding positions opposite to the fixed frame  32  and the guide member  33 , respectively, so as to be engaged with each other. The groove-shaped portions  33 - 2   a  are elongated holes extending along the Y direction in the fixed frame  32 . 
         [0044]    The regulation portions  33 - 3  as shown in  FIG. 4  form a mechanism to regulate the guide member  33  so as not to move relatively to the fixed frame  32  along the Y direction. The regulation portions  33 - 3  having: the concave portions  33 - 3   a  provided on a surface of the fixed frame  32 ; and the convex portions  33 - 3   b  provided on a lower surface of the guide member  33 . The concave portions  33 - 3   a  and the convex portions  33 - 3   b  are disposed at the corresponding positions opposite to the fixed frame  32  and the guide member  33 , respectively, so as to be engaged with each other. 
         [0045]    The guide member  33  is integral moulded element, wherein the spherically-shaped portions  33 - 1   b , spherically-shaped portions  33 - 2   b  and the convex portions  33 - 3   b  are integrally moulded. Further, the first engagement portions  33 - 1  and the second engagement portions  33 - 2  are provided around the voice coil motors  35  which is the action point of the force, in order for the guide member  33  to efficiently work relative to the movable frame  31  and the fixed frame  32 . 
         [0046]    In accordance with the above-explained structure, the movable frame  31  as shown in  FIG. 5B  moves toward the X direction (as shown by the arrow B) relatively to the fixed frame  32  in such a manner that the guide member  33  inclines toward the X direction by means of both the first engagement portions  33 - 1  and the second engagement portion  33 - 2 . Further, as shown in  FIG. 4 , the movable frame  31  can move toward the Y direction (as shown by the arrow C) by means of the elongated hole groove-shaped portions  33 - 1   a  of the first engagement portions  33 - 1 . Further, as shown in  FIG. 3 , the two sets of the groove-shaped portions  33 - 1   a  and the spherically-shaped portions  33 - 1   b  are spaced at a sufficient distance, and similarly, the two sets of the groove-shaped portions  33 - 2   a  and the spherically-shaped portions  33 - 2   b  are separated at a sufficient distance. Therefore, the movable frame  31  moves, without rotating itself around the fixed frame  32 , and while holding it orientation constant. Further, the regulation portions  33 - 3  prevent the guide member  33  from independently moving between the movable frame  31  and the fixed frame  32 . 
         [0047]    The support portion  34 , as shown in  FIG. 5A , is a rolling mechanism provided with: a steel ball  34 - 1 ; a cup-shaped sphere receiving portion  34 - 2 ; and a flat portion  34 - 3 , whereby the steel ball  34 - 1  is held between the sphere receiving portion  34 - 2  provided at the fixed frame  32  and the flat portion  34 - 3  provided at the movable frame  31 . This mechanism makes the movable frame  31  movable in the XY plane, holding constant its position along the Z direction. 
         [0048]    Each of the voice coil motors  35  as shown in  FIG. 3  and  FIG. 5A  is a non-contact type electromagnetic actuator provided with: a magnet portion  35 - 1 ; and a coil portion  35 - 2 , thereby linearly driving the fourth lens unit  25  in response to driving instructions and capable of responding at a high speed. The voice coil motors  35  are disposed at the two positions in lines symmetrical about the X axis passing through the center OR of the fourth lens unit  25  in the movable frame  31 . The driving directions (the arrow C 1  and the arrow C 2 ) of the VCMs  35  are inclined by 45 degrees to the X direction, and the intersection point of the arrow C 1  and the arrow C 2  lies on the X axis passing through the center OR of the fourth lens unit  25 . 
         [0049]    The magnet portion  35 - 1  is a magnetic circuit having: a permanent magnet  35 - 1   a ; and a yoke  35 - 1   b.    
         [0050]    The coil portion  35 - 2  is a magnetic circuit having: a coil  35 - 2   a  as an armature winding wire; and a yoke  35 - 2   b.    
         [0051]    The position detectors  36  is provided with: a magnet portion  36 - 1 ; and a detection portion  36 - 2 , whereby, by detecting a magnetic field change between the magnet portion  36 - 1  and the detection portion  36 - 2 , the displacement by the movement of the movable frame  31  is detected. The position detectors  36  are disposed at the two positions in lines symmetrical about the X axis passing through the center OR of the fourth lens unit  25  of the movable frame  31 . The detecting directions (the arrow D 1  and the arrow D 2 ) of the position detectors  36  are inclined by 45 degrees to the X direction and the intersection point of each of the detecting directions (the arrow D 1  and the arrow D 2 ) lies on the X axis passing through the center OR of the fourth lens unit  25 . 
         [0052]    The magnet portion  36 - 1  is a magnetic circuit having: a permanent magnet  36 - 1   a ; and a yoke  36 - 1   b.    
         [0053]    The detection portion  36 - 2  is a magnetic circuit having: a Hall device  36 - 2   a ; and a yoke  36 - 2   b.    
         [0054]    Next, the operation of the camera  10  and the vibration reduction mechanism unit  30  are described. 
         [0055]    The camera  10  as shown in  FIG. 1  displays the subject image on the display unit  12  through the lens barrel unit  20  and takes the photographs of the subject by means of the operation unit  14 . The lens barrel unit  20  makes the subject light incident on the first lens unit  21 , deflects the subject light by 90 degrees by the prism  22 , and focuses the subject light on the CCD  28  through from the second lens  23  to the fifth lens unit  26 . When a user pushes the shutter button, the control unit  11  operates the vibration reduction mechanism  30 , whereby the image blur due to hand shake caused by the user and so on is corrected. 
         [0056]    The image blur correction unit  30  executes, based on the angular velocity data of the orientation change of the camera  10  detected by the gyro sensor  15 , and on the position data of the movable frame  31  relative to the fixed frame  32  detected by the position detector  36 , the control to correct the image blur caused by the hand shake of the camera  10 , and the optimal management of the relative position between the center portion of the fourth lens unit  25  and the light A 2 . In accordance with this mechanism, the photographs of the subject can be clearly taken without being affected by external disturbances such as camera shake on the camera  10 . 
         [0057]    As explained above, the camera  10  of the present invention has the following advantages. 
         [0058]    (1) The first engagement portions  33 - 1  and the second engagement portions  33 - 2  engaged with the sphere-shaped portions  33 - 1   b  and  33 - 2   b  and the elongated hole groove portions  33 - 1   a  and  33 - 2   a  are provided both between the guide member  33  and the movable frame  31  and between the guide member  33  and the fixed frame  32 . Therefore, the movable frame  31  and the fixed frame  32  can be relatively moved along the two axial directions (the XY direction), with a simple structure, without any relative rotation, with a constant orientation, and with high accuracy. 
         [0059]    (2) The spherically-shaped portions  33 - 1   b  and  33 - 2   b  of the first engagement portions  33 - 1  and the second engagement portions  33 - 2  are formed integrally with the guide member  33 . Therefore, any errors that may arise from these being separate parts are resolved, and the accuracy of the driving control of the vibration reduction mechanism unit  30  can be improved. Further, the manufacturing cost can be reduced, because the spherically-shaped portions  33 - 1   b  and  33 - 2   b  and the guide member  33  can be integrally moulded. 
         [0060]    (3) There are provided, between the fixed frame  32  and the guide member  33 , the regulation portions  33 - 3  to regulate the relative movements of the fixed frame  32  and the guide member  33 , along the Y direction. Therefore, the guide member  33  can be prevented from independently moving between the movable frame  31  and the fixed frame  32 , thereby improving the control characteristics and the accuracy of driving the vibration reduction mechanism unit  30 . 
       Modified Embodiments 
       [0061]    The present invention is not limited to the above-explained embodiment. Various modifications and changes can be made. 
         [0062]    (1) In the above-explained embodiment, the regulation portions  33 - 3  are provided between the fixed frame  32  and the movable frame  31 . However, the regulation portion  33 - 3  may be provided between the movable frame  31  and the guide member  33 . 
         [0063]    (2) In the above-explained embodiment the spherically-shaped portions  33 - 1   b  and  33 - 2   b  are employed for the first engagement portions  33 - 1  and the second engagement portions  33 - 2 , respectively. However, cylindrically-shaped portions may be employed instead, with the condition that the center line of the cylinder is directed along the Y direction. 
         [0064]    (3) In the above-explained embodiment, the spherically-shaped portions  33 - 1   b  and  33 - 2   b  are formed in the guide member  33 , while the groove-shaped portions  33 - 1   a  and  33 - 2   a , are formed in the movable frame  31  and in the fixed frame  32 ; however, the groove-shaped portions  33 - 1   a  and  33 - 2   a  may be formed, in the guide member  33 , while the spherically-shaped portions  33 - 1   b  and  33 - 2   b , respectively may be formed in the movable frame  31  and in the fixed frame  32 .