PATENT ABSTRACT
An image stabilization apparatus includes a first lens unit, a second lens unit, a supporting unit configured to support the first lens unit and the second lens unit, a driving unit configured to drive at least one of the first lens unit and the second lens unit in the direction perpendicular to an optical axis, a shake detection unit configured to detect a shake added to the image stabilization apparatus, a shake correction unit configured to supply a drive signal to the driving unit to correct the detected shake, and a connecting unit configured to mechanically connect the first lens unit and the second lens unit, wherein the connecting unit is configured to enable the first lens unit and the second lens unit to move in mutually opposite directions on a plane perpendicular to the optical axis.

PATENT DESCRIPTION
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an image stabilization apparatus that improves image blur caused by a camera shake, and also relates to an imaging apparatus or an optical apparatus that includes the image stabilization apparatus. 
         [0003]    2. Description of the Related Art 
         [0004]    Recent cameras can automatically perform essential image capturing processing (e.g., exposure determination and focus adjustment) in shooting operations to prevent even unskilled users from failing in shooting operations. An imaging system is configured to correct image blur that may be caused by a camera shake. Thus, there is almost nothing about the factors that may induce any errors in user&#39;s shooting operations. 
         [0005]    An example system capable of correcting image blur caused by a camera shake is simply described below. The camera shake in a shooting operation is vibration in the frequency range from 1 Hz to 10 Hz. To capture an image free from image blur even when such a camera shake occurs when a shutter release button is pressed, it is necessary to detect a camera shake and move a lens to be used for image stabilization (hereinafter, referred to as “correction lens”) according to the detection value. Therefore, to capture an image free from image blur even when a camera shake occurs, it is necessary to accurately detect a camera shake (vibration) and correct a change of the optical axis caused by the camera shake. 
         [0006]    Detection of the camera shake can be realized by a shake detection unit installed on a camera. In principle, the shake detection unit detects acceleration, angular acceleration, angular velocity, or angular displacement and performs processing for calculating an output for image stabilization (hereinafter, referred to as “image blur correction”). The camera system performs image blur correction based on the detected shake information to drive the correction lens that can move the photographic optical axis. 
         [0007]    As discussed in Japanese Patent Application Laid-Open No. 2-162320 or in Japanese Patent Application Laid-Open No. 11-167074, a conventional camera shake correction apparatus uses a pair of lenses having opposite powers and balances these lenses. 
         [0008]    However, according to Japanese Patent Application Laid-Open No. 2-162320, a link mechanism (a beam structure) extends in an optical axis direction to hold the lenses of opposite powers in a balanced state. Therefore, the body size of the camera shake correction apparatus is relatively large. As the correction lenses are supported by beam members rotatably around the beam members, camera shake correction may cause a positional deviation in the optical axis direction and may deteriorate the accuracy in the focus direction. 
         [0009]    According to Japanese Patent Application Laid-Open No. 11-167074, two image blur correction apparatuses are prepared for correcting each image blur of two axes and therefore the apparatus body cannot be downsized. 
       SUMMARY OF THE INVENTION 
       [0010]    Exemplary embodiments of the present invention are directed to a compact and power-saving image blur correction apparatus capable of reducing a positional deviation of an image formed on an image plane, which may be caused by the weight of first and second correction lenses, and are also directed to an imaging apparatus or an optical apparatus that includes the image blur correction apparatus. 
         [0011]    According to an aspect of the present invention, an image stabilization apparatus includes a first lens unit including a first correction lens, a second lens unit including a second correction lens that has a power opposite to that of the first correction lens, a supporting unit configured to support the first lens unit and the second lens unit aligned in an optical axis direction so that the first lens unit and the second lens unit can independently move in a direction perpendicular to the optical axis, a driving unit configured to drive at least one of the first lens unit and the second lens unit in the direction perpendicular to the optical axis, a shake detection unit configured to detect a shake added to the image stabilization apparatus, a shake correction unit configured to supply a drive signal to the driving unit to correct the shake based on an output of the shake detection unit, and a connecting unit configured to mechanically connect the first lens unit and the second lens unit, wherein the connecting unit is configured to enable the first lens unit and the second lens unit to move in mutually opposite directions on a plane perpendicular to the optical axis when the first lens unit and the second lens unit are driven by the driving unit. 
         [0012]    Exemplary embodiment of the present invention can sufficiently reduce a positional deviation of an image on an image plane caused by weights of the first and second correction lenses and can realize an image blur correction apparatus, an imaging apparatus, or an optical apparatus, which is compact in size and consumes a small amount of electric power. 
         [0013]    Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments and features of the invention and, together with the description, serve to explain at least some of the principles of the invention. 
           [0015]      FIG. 1  illustrates a front view of an image blur correction apparatus equipped in the digital camera according to a first exemplary embodiment of the present invention. 
           [0016]      FIG. 2  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 1 -A 2  illustrated in  FIG. 1 . 
           [0017]      FIG. 3  illustrates a cross-sectional view of the image blur correction apparatus taken along a line B-A 2  illustrated in  FIG. 1 . 
           [0018]      FIG. 4  illustrates an enlarged view of a portion indicated by C in  FIG. 3 . 
           [0019]      FIG. 5  is a block diagram illustrating a driving circuit system for lens unit according to the first exemplary embodiment of the present invention. 
           [0020]      FIG. 6  illustrates a drive balance of the image blur correction apparatus in a pitch direction according to the first exemplary embodiment of the present invention. 
           [0021]      FIG. 7  illustrates a drive balance of the image blur correction apparatus in a yaw direction according to the first exemplary embodiment of the present invention. 
           [0022]      FIG. 8  illustrates a front view of an image blur correction apparatus equipped in a digital camera according to a second exemplary embodiment of the present invention. 
           [0023]      FIG. 9  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 3 -A 4  illustrated in  FIG. 8 . 
           [0024]      FIG. 10  illustrates a front view of an image blur correction apparatus equipped in a digital camera according to a third exemplary embodiment of the present invention. 
           [0025]      FIG. 11  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 5 -A 6  illustrated in  FIG. 10 . 
           [0026]      FIGS. 12A and 12B  illustrate enlarged views of a portion indicated by D in  FIG. 11 . 
           [0027]      FIG. 13  illustrates a front view of an image blur correction apparatus equipped in a digital camera according to a fourth exemplary embodiment of the present invention. 
           [0028]      FIG. 14  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 7 -A 8  illustrated in  FIG. 13 . 
           [0029]      FIGS. 15A and 15B  illustrate enlarged views of a portion indicated by E in  FIG. 14 . 
           [0030]      FIG. 16  illustrates a front view of an image blur correction apparatus equipped in a digital camera according to a fifth exemplary embodiment of the present invention. 
           [0031]      FIG. 17  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 9 -A 10  illustrated in  FIG. 16 . 
           [0032]      FIG. 18  illustrates an enlarged view of a portion indicated by F in  FIG. 17 . 
           [0033]      FIG. 19  illustrates a front view of an image blur correction apparatus equipped in a digital camera according to a sixth exemplary embodiment of the present invention. 
           [0034]      FIG. 20  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 11 -A 12  illustrated in  FIG. 19 . 
           [0035]      FIGS. 21A and 21B  illustrate enlarged views of a portion indicated by G in  FIG. 20 . 
           [0036]      FIG. 22  illustrates a plan view of an image blur correction apparatus according to a seventh exemplary embodiment of the present invention. 
           [0037]      FIG. 23  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 13 -A 14  of  FIG. 22 . 
           [0038]      FIG. 24  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 13 -H 1  illustrated in  FIG. 22 . 
           [0039]      FIG. 25  illustrates a plan view of an image blur correction apparatus according to an eighth exemplary embodiment of the present invention. 
           [0040]      FIG. 26  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 15 -A 6  illustrated in  FIG. 25 . 
           [0041]      FIG. 27  illustrates a plan view of an image blur correction apparatus according to a ninth exemplary embodiment of the present invention. 
           [0042]      FIG. 28  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 17 -A 18  illustrated in  FIG. 27 . 
           [0043]      FIG. 29  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 18 -H 2  illustrated in  FIG. 27 . 
           [0044]      FIG. 30  illustrates a cross-sectional view of the image blur correction apparatus taken along a line J-A 18  illustrated in  FIG. 27 . 
           [0045]      FIGS. 31A and 31B  illustrate enlarged views of a portion indicated by K in  FIG. 30 . 
           [0046]      FIG. 32  illustrates an appearance of an imaging apparatus according to the present invention. 
           [0047]      FIG. 33  illustrates a perspective view of an image blur correction apparatus equipped in an imaging apparatus according to the present invention. 
           [0048]      FIG. 34  is a block diagram illustrating a circuit arrangement of a shake correction system for an imaging apparatus according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0049]    The following description of exemplary embodiments is illustrative in nature and is in no way intended to limit the invention, its application, or uses. It is noted that throughout the specification, similar reference numerals and letters refer to similar items in the following figures, and thus once an item is described in one figure, it may not be discussed for following figures. Exemplary embodiments will be described in detail below with reference to the drawings. 
         [0050]    According to aspects of the present invention, the following first to ninth exemplary embodiments are described below. 
         [0051]      FIG. 32  illustrates an appearance of a digital compact camera that has an image blur correction function according to the present invention. The digital compact camera performs image blur correction when the camera is subjected to vertical and horizontal shakes indicated by arrows  1042   p  and  1042   y  with respect to an optical axis  41 . A camera body  1043  includes a release button  1043   a , a mode dial  1043   b  (including a main switch), and a retractable flash unit  1043   c.    
         [0052]      FIG. 33  illustrates a perspective view of an example mechanism of the image blur correction apparatus equipped in the digital compact camera according to the present exemplary embodiment. An image sensor  1044  converts an object image into an electric signal. 
         [0053]    An image blur correction apparatus  1053  drives a correction lens  1052  in two directions indicated by arrows  1058   p  and  1058   y  and performs image blur correction in two directions indicated by arrows  1042   p  and  1042   y  illustrated in  FIG. 32 , as described below in more detail. 
         [0054]    A shake detection unit (e.g., an angular speedometer or an angular accelerometer)  1045   p  detects a shake amount around an arrow  1046   p . Another shake detection unit  1045   y  detects a shake amount around an arrow  1046   p . A calculation unit  1047   p  converts an output of the shake detection unit  1045   p  into a drive target value to be supplied to the correction lens  1052 . Another calculation unit  1047   y  converts an output of the shake detection unit  1045   y  into a drive target value to be supplied to the correction lens  1052 . 
         [0055]      FIG. 34  is a block diagram illustrating details of the calculation units  1047   p  and  1047   y  illustrated in  FIG. 33 . As the calculation units  1047   p  and  1047   y  are similar to each other,  FIG. 34  illustrates an example circuit arrangement of the calculation unit  1047   p.    
         [0056]    The calculation unit  1047   p  includes an amplification unit  1048   p  functioning also as a DC cut filter, an amplification unit  1049   p  functioning also as a low-pass filter, an analog-to-digital conversion unit (hereinafter, referred to as “A/D conversion unit”)  1410   p , a camera microcomputer  1411 , and a driving unit  1420   p , which are constituent elements surrounded by an alternate long and short dash line illustrated in  FIG. 34 . The camera microcomputer  1411  includes a storage unit  1412   p , a differential unit  1413   p , a DC cut filter  1414   p , an integration unit  1415   p , a sensitivity adjusting unit  1416   p , a storage unit  1417   p , a differential unit  1418   p , and a PWM duty conversion unit  1419 . 
         [0057]    In the present invention, the shake detection unit  1045   p  is a vibration gyro that can detect a camera shake angular velocity. The vibration gyro starts its operation in response to turning-on of the main switch of the camera and starts detecting a shake angular velocity applied on the camera. 
         [0058]    The amplification unit  1048   p , which is an analog circuit that can function as a DC cut filter, removes DC bias components from a shake signal received from the shake detection unit  1045   p  and amplifies the received shake signal. The amplification unit  1048   p  has frequency characteristics capable of cutting signal components in the frequency range equal to and less than 0.1 Hz while leaving signal components in a camera shake frequency band of 1 to 10 Hz that may be applied to the camera. 
         [0059]    However, when the characteristics capable of cutting the signal components equal to and less than 0.1 Hz is used, it takes approximately 10 seconds to completely cut the DC components after the shake signal is input from the shake detection unit  1045   p . Therefore, the time constant of the amplification unit  1048   p  is set to a smaller value for a short duration of approximately 0.1 second after the main switch of the camera is turned on. For example, the characteristics of the amplification unit  1048   p  are set to be able to cut signal components in the frequency range equal to and less than 10 Hz. 
         [0060]    In this manner, the amplification unit (DC cut filter)  1048   p  has the characteristics capable of cutting DC components in a short period of time of approximately 0.1 second and, then, increasing the time constant to cut signal components in the frequency range equal to and less than 0.1 Hz. As a result, the amplification unit (DC cut filter)  1048   p  can prevent a shake angular velocity signal from deteriorating. 
         [0061]    The amplification unit  1049   p , which is an analog circuit that can function as a low-pass filter, appropriately amplifies an output signal of the amplification unit (DC cut filter)  1048   p  according to an A/D resolution to cut high-frequency noises included in the shake angular velocity signal. Therefore, in a sampling operation of the shake angular velocity signal to be entered to the camera microcomputer  1411 , the A/D conversion unit  1410   p  can reduce reading errors that may be caused by noises included in the shake angular velocity signal. 
         [0062]    The A/D conversion unit  1410   p  samples an output signal of the amplification unit (low-pass filter)  1049   p . The camera microcomputer  1411  receives an output signal of the A/D conversion unit  1410   p . The amplification unit (DC cut filter)  1048   p  cuts the DC bias components. However, the shake angular velocity signal amplified by the amplification unit (low-pass filter)  1049   p  may include DC bias components. Therefore, the camera microcomputer  1411  cuts the DC bias components included in the output signal of the A/D conversion unit  1410   p.    
         [0063]    For example, the storage unit  1412   p  stores a sampling value of the shake angular velocity signal when the time duration of 0.2 seconds has elapsed after the camera main switch is turned on. The differential unit  1413   p  obtains a difference between a value stored in the storage unit  1412   p  and the present shake angular velocity signal to cut the DC components. 
         [0064]    However, the above-described operation for cutting the DC components is rough (because the shake angular velocity signal sampled when the time duration of 0.2 seconds has elapsed after the camera main switch is turned on includes not only the DC components but also actual camera shake components). Therefore, the DC cut filter  1414   p  in the camera microcomputer  1411  completely cuts the DC components with a digital filter. 
         [0065]    Similarly to the amplification unit  1048   p  functioning also as an analog DC cut filter, the DC cut filter  1414   p  can change its time constant and gradually increase the time constant when the time duration of 0.4 seconds (=0.2 sec+0.2 sec) has elapsed after the camera main switch is turned on. 
         [0066]    More specifically, the DC cut filter  1414   p  has filtering characteristics capable of cutting signal components in the frequency range equal to and less than 10 Hz when the time duration of 0.2 seconds has elapsed after the main switch is turned on. The DC cut filter  1414   p  decreases the filter cut frequency to 5 Hz→1 Hz→0.5 Hz→0.2 Hz at the time intervals of 50 msec. 
         [0067]    However, if a photographer presses a shutter release button by a half depth (i.e., turns on a switch sw 1 ) for a light-metering/range-finding operation during the above-described operation, the photographer may immediately start a shooting operation and it is not desired to take a long time to change the time constant. 
         [0068]    Hence, in such a case, the DC cut filter  1414   p  interrupts the operation for changing the time constant according to shooting conditions. For example, if a light-metering result reveals that the shutter speed becomes 1/60 and the photographic focal length is 150 mm, higher accuracy in image stabilization is not required and therefore the DC cut filter  1414   p  completes the time constant change operation when it attains the characteristics capable of cutting signal components in the frequency range equal to and less than 0.5 Hz. 
         [0069]    More specifically, the DC cut filter  1414   p  controls a change amount of the time constant based on a product of the shutter speed and the photographic focal length. Thus, the time for changing the time constant can be reduced and the shutter timing can be prioritized. Needless to say, if the shutter speed is higher or when the focal length is shorter, the DC cut filter  1414   p  completes the time constant change operation when it attains the characteristics capable of cutting signal components in the frequency range equal to and less than 1 Hz. If the shutter speed is lower and the focal length is longer, the camera microcomputer  1411  inhibits a shooting operation until the DC cut filter  1414   p  completes the operation for changing the time constant to a final value. 
         [0070]    The integration unit  1415   p  starts integrating the output signal of the DC cut filter  1414   p  to convert the angular velocity signal into an angle signal. The sensitivity adjusting unit  1416   p  appropriately amplifies the integrated angle signal according to the present camera focal length and object distance information. The sensitivity adjusting unit  1416   p  converts the amplified signal so that a driven portion of the camera shake correction apparatus can be driven by an appropriate amount according to a camera shake angle. The above-described correction is generally required when an eccentric amount of the optical axis relative to a moving amount of the driven portion changes in response to a change of an imaging optical system during a zooming/focusing operation. 
         [0071]    The camera microcomputer  1411  starts driving a mechanism portion of the image blur correction apparatus (hereinafter, simply referred to as “image blur correction apparatus”) when the shutter release button is half pressed. At this moment, it is desired to prevent the image blur correction apparatus from abruptly starting its operation for the image blur correction. 
         [0072]    The storage unit  1417   p  and the differential unit  1418   p  can prevent abrupt starting of the image blur correction operation. The storage unit  1417   p  stores a camera shake angle signal of the integration unit  1415   p  at timing when the shutter release button is half pressed. The differential unit  1418   p  obtains a difference between the output signal of the integration unit  1415   p  and the output signal of the storage unit  1417   p.    
         [0073]    Accordingly, two signals entered to the differential unit  1418   p  are equal with each other at the timing when the shutter release button is half pressed. An output signal (drive target value) generated by the differential unit  1418   p  becomes zero. Then, the signal is output continuously starting from zero. The storage unit  1417   p  has a role of setting, as an origin, an integration signal at the timing when the shutter release button is half pressed. Therefore, the storage unit  1417   p  and the differential unit  1418   p  can prevent the image blur correction apparatus from abruptly starting its operation. 
         [0074]    The PWM duty conversion unit  1419   p  receives the target value signal from the differential unit  1418   p . When the voltage or current applied to the coils of the image blur correction apparatus is a value corresponding to the camera shake angle, the correction lens  1052  is driven according to the camera shake angle. The PWM drive is preferably usable to reduce the amount of electric power consumed in the image blur correction apparatus and to save the electric power to be supplied to the transistors driving the coils. 
         [0075]    Hence, the PWM duty conversion unit  1419   p  changes a coil driving duty according to the target value. For example, when the PWM has the frequency of 20 KHz, the PWM duty conversion unit  1419   p  sets the duty to zero if the target value received from the differential unit  1418   p  is “2048” and sets the duty to 100 if the target value is “4096.” If the target value is larger than “2048” and less than “4096”, the PWM duty conversion unit  1419   p  sets the duty to an intermediate value, which is appropriately determined according to the target value. To finely determine the duty to accurately perform the image blur correction, it is desired to consider not only the target value but also the present camera shooting conditions (e.g., temperature, camera orientation, and residual battery capacity). 
         [0076]    The driving unit  1420   p  (e.g., a conventional PWM driver) receives an output of the PWM duty conversion unit  1419   p  and outputs a drive signal to be applied to the coil of the image blur correction apparatus for the image blur correction. The driving unit  1420   p  is activated at timing when the time duration of 0.2 seconds has elapsed after the shutter release button is half pressed (i.e. when the switch sw 1  is turned on). 
         [0077]    Although not illustrated in the block diagram of the  FIG. 34 , if the photographer fully presses the shutter release button (when a switch sw 2  is turned on) to cause the camera to start exposure processing, the image blur correction is continuously performed. Accordingly, the present exemplary embodiment can prevent the camera shake from deteriorating the quality of a captured image. 
         [0078]    The image blur correction by the image blur correction apparatus continues as long as the photographer keeps the shutter release button in a half pressed state. If the photographer releases the button from the half pressed state, the storage unit  1417   p  stops storing the output signal of the sensitivity adjusting unit  1416   p  (i.e., goes into a sampling state). Therefore, the differential unit  1418   p  receives the same signal from the sensitivity adjusting unit  1416   p  and the storage unit  1417   p . The output signal generated by the differential unit  1418   p  becomes zero. Therefore, the image blur correction apparatus receives no drive target value and performs no image blur correction. 
         [0079]    The integration unit  1415   p  continues integration operation until the main switch of the camera is turned off. If the shutter release button is again half pressed, the storage unit  1417   p  newly stores an integration output (holds the signal) If the photographer turns off the main switch, the shake detection unit  1045   p  stops its operation and terminates the image stabilization sequence. 
         [0080]    If the signal of the integration unit  1415   p  becomes larger than a predetermined value, the camera microcomputer  1411  determines that a panning operation of the camera has been performed and changes the time constant of the DC cut filter  1414   p . For example, the camera microcomputer  1411  discards the characteristics capable of cutting signal components in the frequency range equal to and less than 0.2 Hz and newly sets the characteristics capable of cutting signal components in the frequency range equal to and less than 1 Hz. Accordingly, the time constant value returns to the original value within a predetermined time. 
         [0081]    In this case, the time constant change amount is controlled according to the output of the integration unit  1415   p . More specifically, if the output exceeds a first threshold, the characteristics capable of cutting signal components in the frequency range equal to and less than 0.5 Hz is set for the DC cut filter  1414   p . If the output exceeds a second threshold, the characteristics capable of cutting signal components in the frequency range equal to and less than 1 Hz is set for the DC cut filter  1414   p . If the output exceeds a third threshold, the characteristics capable of cutting signal components in the frequency range equal to and less than 5 Hz is set for the DC cut filter  1414   p.    
         [0082]    When the output of the integration unit  1415   p  is a very large value (e.g., when a large angular velocity is generated due to the panning motion of the camera), the camera microcomputer  1411  resets the operation of the integration unit  1415   p  to prevent saturation (overflow) in calculation. According to the circuit arrangement illustrated in  FIG. 34 , the amplification unit (DC cut filter)  1048   p  and the amplification unit (low-pass filter)  1049   p  are provided in the calculation unit  1047   p . However, the amplification unit  1048   p  and the amplification unit  1049   p  can be provided in the shake detection unit  1045   p.    
         [0083]      FIG. 1  illustrates a front view of an image blur correction apparatus according to the first exemplary embodiment of the present invention.  FIG. 2  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 1 -A 2  illustrated in  FIG. 1 .  FIG. 3  illustrates a cross-sectional view of the image blur correction apparatus taken along a B-A 2  illustrated in  FIG. 1 .  FIG. 4  illustrates an enlarged view of a portion indicated by C illustrated in  FIG. 3 . 
         [0084]    In  FIGS. 1 to 4 , two correction lenses  10   a  and  10   b  have mutually opposite powers for image blur correction. The correction lens  10   a  has positive power and the correction lens  10   b  has negative power. A holding frame  11   a  holds the correction lens  10   a . A holding frame  11   b  holds the correction lens  10   b . The image blur correction apparatus further includes a base plate  12 . 
         [0085]    The holding frame  11   a , as illustrated in  FIG. 1 , includes pins  14   a  to  14   c  disposed at equal angular intervals of 120°. Ends of three extension springs  15   a  to  15   c  are hooked around the pins  14   a  to  14   c , respectively. The holding frame lib includes pins  14   d  to  14   f  (although only one pin  14   d  is illustrated in  FIGS. 2 and 3 ) disposed at equal angular intervals of 120°. Ends of the extension springs  15   d  to  15   f  (although only one extension spring  15   d  is illustrated in  FIGS. 2 and 3 ) are hooked around the pins  14   d  to  14   f , respectively. The base plate  12 , as illustrated in  FIG. 1 , includes pins  13   a  to  13   c  provided on its front surface and disposed at equal angular interval of 120°. The other ends of the extension springs  15   a  to  15   c  are hooked around the pins  13   a  to  13   c . The base plate  12  includes pins  13   d  to  13   f  disposed at equal angular intervals of 120° on its reverse surface (although only one pin  13   d  is illustrated in  FIGS. 2 and 3 ). 
         [0086]    The extension springs  15   a  to  15   f  are positioned respectively between the pins  14   a  to  14   f  provided on the holding frames  11   a  or  11   b , and the pins  13   a  to  13   f  provided on the base plate  12 . The extension springs  15   a  to  15   f , as illustrated in  FIGS. 2 and 3 , generate tensile force in the direction of an optical axis  100  (in the right-and-left direction in  FIGS. 2 and 3 ). 
         [0087]    Three balls  16   a  to  16   c  (although only one ball  16   a  is illustrated in  FIGS. 2 and 3 ) are sandwiched between the holding frame  11   a  and the base plate  12 , as illustrated in  FIGS. 1 to 3 . Therefore, the holding frame  11   a  and the base plate  12  are resiliently urged by an optical axis  100  direction component of the tensile force generated by the extension springs  15   a  to  15   c . Similarly, balls  16   d  to  16   f  (although only one ball  16   d  is illustrated in  FIGS. 2 and 3 ) are sandwiched between the holding frame  11   b  and the base plate  12 . Therefore, the holding frame  11   b  and the base plate  12  are resiliently urged by an optical axis  100  direction component of the tensile force generated by the extension springs  15   d  to  15   f.    
         [0088]    The holding frames  11   a  and  11   b  can move relative to the base plate  12  in the directions indicated by arrows  111   p ,  111   y , and  111   r  in  FIG. 1 . However, the movement of respective holding frames  11   a  and  11   b  in the optical axis  100  direction (i.e., the direction perpendicular to the drawing surface of  FIG. 1 ) is restricted. The extension springs  15   a  to  15   f  add necessary and sufficient force to the holding frames  11   a  and lib in radial directions as illustrated in  FIG. 1 . Therefore, the extension springs  15   a  to  15   f  prevent the holding frames  11   a  and lib from rotating in the direction indicated by the arrow  111   r.    
         [0089]    Movements in the directions indicated by the arrows  111   p  and  111   y  are mutually cancelled because initial tensile forces of respective extension springs  15   a  to  15   f  are equally distributed in radial directions. Therefore, the driving force required is determined based on only the spring constants of the extension springs  15   a  to  15   f  (regardless of their initial tensile forces). Accordingly, the movements in the directions indicated by the arrows  111   p  and  111   y  can be realized with a relatively small amount of force. 
         [0090]    As illustrated in  FIG. 3  and in  FIG. 4  (i.e., the enlarged view of the portion C of  FIG. 3 ), the holding frame  11   a  and the holding frame  11   b  are connected via a connecting member  19   a  that includes a sliding rotational center portion (spherical portion)  19   a - a  supported by the base plate  12 . The connecting member  19   a  includes spherical sliding portions  19   a - b  and  19   a - c  provided at both ends thereof. The holding frames  11   a  and  11   b  have through-holes in which the sliding portions  19   a - b  and  19   a - c  are placed and can slide in the direction of the optical axis  100 . In the illustration of  FIG. 1  according to the present exemplary embodiment, the connecting members  19   a  and  19   b  are disposed on the base plate  12  in a point-symmetric relationship with respect to the optical axis  100 , so that the connecting members  19   a  and  19   b  cause similar motions according to the movements of a first lens unit member and a second lens unit member. However, if the similar effects can be obtained, the total number of the connecting members  19   a  and  19   b  and their positions are changeable. 
         [0091]    Therefore, for example, when the holding frame  11   a  is driven in the direction indicated by an arrow  114   a  (see  FIG. 4 ) on the plane perpendicular to the optical axis  100 , the sliding rotational center portion  19   a - a  is pushed by the sliding portion  19   a - b . Therefore, the sliding rotational center portion  19   a - a  rotates in the direction indicated by an arrow  112  in  FIG. 4 . The sliding portion  19   a - c  pushes the holding frame lib in the direction indicated by an arrow  114   b  (see  FIG. 4 ). In this case, the sliding portions  19   a - b  and  19   a - c  can freely slide in the through-holes of the holding frames  11   a  and  11   b.    
         [0092]    Accordingly, even when a rotational motion around the sliding rotational center portion  19   a - a  is performed, a moving component in the direction of the optical axis  100  can be absorbed without preventing the holding frames  11   a  and lib from moving on the plane perpendicular to the optical axis  100 . The connecting member  19   a  holds each of the correction lenses  10   a  and  10   b  (i.e., a pair of correction lenses having mutually opposite powers) on planes perpendicular to the optical axis so that the correction lenses  10   a  and  10   b  can move in mutually opposite directions. Although not illustrated, the connecting member  19   b  is similar to the connecting member  19   a  in structure. Therefore, the connecting member  19   b  holds each of the correction lenses  10   a  and  10   b  on the planes perpendicular to the optical axis so that the correction lenses  10   a  and  10   b  can move in mutually opposite directions. 
         [0093]    As illustrated in  FIGS. 1 and 2 , coils  18   a  and  18   b  (although only one coil  18   a  is illustrated in  FIG. 2 ) are fixed to arm portions of the holding frame  11   a  in a confronting relationship with yokes  110   a  and  110   b  (although only one yoke  110   a  is illustrated in  FIG. 2 ) and permanent magnets  17   a  and  17   b  such as neodymium magnets (although only one permanent magnet  17   a  is illustrated in  FIG. 2 ) fixed to the holding frame  11   b . The permanent magnets  17   a  and  17   b  are magnetized in their thickness directions as illustrated in  FIG. 2 . The magnetic fluxes of the magnets  17   a  and  17   b  penetrate the coils  18   a  and  18   b , which are present on the opposed surfaces, in the direction parallel to the optical axis  100  (in the right-and-left direction in  FIG. 2 ). 
         [0094]    A driving mechanism of the above-described driving portion is described below. As described above, the coils  18   a  and  18   b  (part of a first lens unit) and the permanent magnets  17   a  and  17   b  (part of a second lens unit) cooperatively constitute the driving portion. The magnetic fluxes of respective permanent magnets  17   a  and  17   b  penetrate the coils  18   a  and  18   b  perpendicularly. Therefore, if current flows through the coil  18   a , the holding frame  11   a  is efficiently driven in the direction indicated by an arrow  113   a  in  FIG. 1 . Similarly, if current flows through the coil  18   b , the holding frame  11   a  is efficiently driven in the direction indicated by an arrow  113   b  in  FIG. 1 . 
         [0095]    The drive amount by the driving portion is determined according to the balance relationship between the resilient force of the extension springs  15   a ,  15   b ,  15   c ,  15   d ,  15   e , and  15   f  (i.e., forces derived from their spring constants) and the thrust force to be electromagnetically generated by the interaction between the coils  18   a  and  18   b  and the permanent magnets  17   a  and  17   b . In other words, the eccentric amount of the correction lens  10   a  (image blur correction amount by the correction lens  10   a ) can be controlled based on the amount of current flowing through the coils  18   a  and  18   b.    
         [0096]      FIG. 5  is a block diagram illustrating a driving circuit that controls the driving of the correction lens  10   a . A pitch target value  51   p  and a yaw target value  51   y  are drive target values for image blur correction to be used to drive the lens unit in the arrow  111   p  direction (pitch direction) and the arrow  111   y  direction (yaw direction) illustrated in  FIG. 1 . The pitch target value  51   p  and the yaw target value  51   y  correspond to the differential unit  1418   p  illustrated in  FIG. 34 . 
         [0097]    A pitch driving force adjusting unit  52   p  and a yaw driving force adjusting unit  52   y  perform gain adjustment for the target values in the pitch and yaw directions according to the driving forces of respective driving directions. A coil  18   a  driving circuit  54   a  (which corresponds to the PWM duty conversion unit  1419   p  and the driving portion  1420   p  illustrated in  FIG. 34 ) receives an output of the pitch driving force adjusting unit  52   p  and generates current to be supplied to the coil  18   a . A coil  18   b  driving circuit  54   b  (which corresponds to the PWM duty conversion unit  1419   p  and the driving portion  1420   p  illustrated in  FIG. 34 ) receives the output of the pitch driving force adjusting unit  52   p  via an adding circuit  53   b  and generates current to be supplied to the coil  18   b . Namely, the current supplied to the coil  18   a  and the current supplied to the coil  18   b  according to the signal of the pitch drive target value  51   p  are in-phase and same amount. 
         [0098]    The coil  18   b  driving circuit  54   b  (which corresponds to the PWM duty conversion unit  1419   p  and the driving portion  1420   p  illustrated in  FIG. 34 ) receives an output of the yaw driving force adjusting unit  52   y  and generates current to be supplied to the coil  18   b . The coil  18   a  driving circuit  54   a  (which corresponds to the PWM duty conversion unit  1419   p  and the driving portion  1420   p  illustrated in  FIG. 34 ) receives the output of the yaw driving force adjusting unit  52   y  via an inversion circuit  53   a  and generates current to be supplied to the coil  18   b . Namely, the current supplied to the coil  18   a  and the current supplied to the coil  18   b  according to the signal of the yaw drive target value  51   y  are in reverse-phase to each other and same amount. 
         [0099]    When the current supplied to the coil  18   a  and the current supplied to the coil  18   b  are in-phase and same amount, the coil  18   a  generates the driving force in the direction indicated by the arrow  113   a  and the coil  18   b  generates the driving force in the direction indicated by the arrow  113   b , as indicated in  FIG. 6 . Accordingly, the resultant force generates the driving force acting in the arrow  113   p  (arrow  111   p ) direction (pitch direction). The driving force generated in this case is the composite driving force resulting from 1/√{square root over (2)} of respective driving forces generated by the coils  18   a  and  18   b  because two coils  18   a  and  18   b  are disposed in a 90-degree rotated state. 
         [0100]    When the current supplied to the coil  18   a  and the current supplied to the coil  18   b  are out-of-phase and same amount, the coil  18   a  generates the driving force in the direction indicated by the arrow  113   a  and the coil  18   b  generates the driving force in the direction indicated by the arrow  113   b ′ (which is opposite to the arrow  113   b ), as indicated in  FIG. 7 . Accordingly, the resultant force generates the driving force acting in the arrow  113   y  (arrow  111   y ) direction (yaw direction). The driving force generated in this case is the composite driving force resulting from 1/√{square root over (2)} of respective driving forces generated by the coils  18   a  and  18   b  because two coils  18   a  and  18   b  are disposed in a 90-degree rotated state. 
         [0101]    The pitch driving force adjusting unit  52   p  and the yaw driving force adjusting unit  52   y  associate the eccentric sensitivity of the optical system with shake correction amounts of the correction lenses  10   a  and  10   b.    
         [0102]    As described above, when current flows through the coils  18   a  and  18   b , the first lens unit including the holding frame  11   a  and the correction lens  10   a  is driven in relationship with the directions of the magnetic fluxes generated by the permanent magnets  17   a  and  17   b . At the same time, the second lens unit including the holding frame lib and the correction lens  10   b  is subjected to a reaction force and is driven in a direction opposite to the moving direction of the first lens unit on the plane perpendicular to optical axis  100 . In this case, it is necessary that an elastic portion of the first lens unit and an elastic portion of the second lens unit have similar spring constants. 
         [0103]    The connecting members  19   a  and  19   b  have a role of assisting the first lens unit and the second lens unit that are driven in opposite directions on the plane perpendicular to the optical axis  100  (on the plane perpendicular to the optical axis). In  FIG. 3 , if the correction lens  10   a  (which is a convex lens) is driven in a direction “a”, the optical axis deflects upward in  FIG. 3  due to eccentricity thereof. If the correction lens  10   b  (which is a concave lens), having a power opposite to that of the correction lens  10   a , is driven in a direction “b”, the optical axis deflects upward in  FIG. 3  due to eccentricity thereof. Therefore, a large deflection can be obtained by two correction lenses  10   a  and  10   b  that are driven in mutually opposite directions. Therefore, the large image blur correction can be realized with a small drive amount. 
         [0104]    In a case where respective lens units are simply supported by the extension springs  15   a  to  15   f  and the balls  16   a  to  16   f , it is required that the first lens unit and the second lens unit are equivalent in weight to prevent the optical axis  100  from decentering due to the gravity. However, the presence of the connecting members  19   a  and  19   b  can reduce the problem of eccentricity caused by the weights of respective lens units. Even if the first and second lens units are greatly different in weight, such a problem can be solved by setting two arms extending from the sliding rotational center portion  19   a - a  to respective sliding portions  19   a - b  and  19   a - c  provided on the connecting member  19   a  to have a ratio in length opposite to the ratio in weight between two lens units in  FIG. 4 . 
         [0105]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane by the positional deviation of the correction lens and can realize an image blur correction apparatus that is compact in size and consumes a small amount of electric power. 
         [0106]      FIG. 8  illustrates a front view of an image blur correction apparatus according to a second exemplary embodiment of the present invention.  FIG. 9  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 3 -A 4  illustrated in  FIG. 8 . Compared to the above-described first exemplary embodiment, the second exemplary embodiment uses a different structure for connecting the first and second lens units. 
         [0107]    In the second exemplary embodiment, a supporting portion includes extension springs  25   a  and  25   b  supporting the first lens unit and the balls  26   a  to  26   f  sandwiched between a base plate  22  and holding frames  21   a  and  21   b . The holding frame  21   a  includes pins  24   a  and  24   b  disposed at angular intervals of 180°, as illustrated in  FIG. 8 , around which ends of the extension springs  25   a  and  25   b  are hooked. The holding frame  21   b  includes pins  24   d  and  24   e  disposed at angular intervals of 180° (although only one pin  24   d  is illustrated in  FIG. 9 ), around which ends of extension springs  25   d  and  25   e  (although only one extension spring  25   d  is illustrated in  FIG. 9 ) are hooked. The base plate  22  includes pins  23   a  and  23   b  disposed at angular intervals of 180°, as illustrated in  FIG. 8 , around which the other ends of the extension springs  25   a  and  25   b  are hooked. Although not illustrated in  FIG. 8 , the base plate  22  includes pins  23   d  and  23   e  disposed at angular intervals of 180° on its reverse surface (although only one pin  23   e  is illustrated in  FIG. 9 . 
         [0108]    The second exemplary embodiment is similar to the first exemplary embodiment in the rest of the arrangement. Constituent members of the second exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIGS. 1 to 4  although the most significant digit is replaced with “2.” For example, a correction lens  20   a  is functionally equivalent to the correction lens  10   a . Directions indicated by arrows  211   p ,  211   y , and  211   r  are similar to the directions indicated by the arrows  111   p ,  111   y , and  111   r , respectively. 
         [0109]    In the second exemplary embodiment, the first lens unit includes a holding frame  21   a  and the correction lens  20   a . The second lens unit includes a holding frame  21   b  and a correction lens  20   b . The first and second lens units are connected to each other with string members  210   a  and  210   b  (although only one string member  210   a  is illustrated in  FIG. 9 ) via roller members  29   a  and  29   b  rotatably attached to the base plate  22 . 
         [0110]    According to the example illustrated in  FIG. 9 , if the first lens unit moves in the direction indicated by an arrow  212   a  in  FIG. 9 , the second lens unit is pulled in the direction indicated by an arrow  212   b  by the string member  210   a  via the roller member  29   a . In the present exemplary embodiment, the roller members  29   a  and  29   b  are line-symmetrically disposed with respect to the axis of the  211   p  direction so that the forces in the  211   y  direction are balanced. 
         [0111]    With the above-described arrangement, the correction lenses  20   a  and  20   b  (a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis  200 . 
         [0112]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  20   a  and  20   b . When the image blur correction is performed, the correction lenses  20   a  and  20   b  can be driven with a small amount of driving force. Therefore, the present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0113]      FIG. 10  illustrates a front view of an image blur correction apparatus according to a third exemplary embodiment of the present invention.  FIG. 11  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 5 -A 6  illustrated in  FIG. 10 .  FIGS. 12A and 12B  illustrate enlarged views of a portion indicated by D in  FIG. 11 . Compared to the above-described first exemplary embodiment, the third exemplary embodiment uses a different structure for connecting the first and second lens units. Constituent members of the third exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIGS. 1 to 4  although the most significant digit is replaced with “3.” For example, a correction lens  30   a  is functionally equivalent to the correction lens  10   a . Directions indicated by arrows  311   p ,  311   y , and  311   r  are similar to the directions indicated by the arrows  111   p ,  111   y , and  111   r , respectively. 
         [0114]    In the third exemplary embodiment, the first lens unit includes a holding frame  31   a  and the correction lens  30   a . The second lens unit includes a holding frame  31   b  and a correction lens  30   b . Two connecting members  39   a  and  39   b  connect the first lens unit and the second lens unit. 
         [0115]      FIGS. 12A and 12B  illustrate details of the connecting member  39   a . Although  FIG. 10  illustrates the connecting members  39   a  and  39   b  as if they are visibly, the connecting members  39   a  and  39   b  are sandwiched between two holding frames  31   a  and  31   b.    
         [0116]    The connecting member  39   a  includes an axial member  39   a - a  attached to a base plate  32 , two sliding portions  39   a - b  and  39   a - c  housed in through-holes of the holding frames  31   a  and  31   b , and, a coupling portion  39   a - d . The connecting member  39   a  can rotate around the axial member  39   a - a  in the direction indicated by an arrow  312  on the drawing surface of  FIG. 12B . The sliding portions  39   a - b  and  39   a - c  can freely slide in the through-holes of the holding frames  31   a  and  31   b . Therefore, even when a rotational motion around the axial member  39   a - a  is performed, a moving component in the direction of an optical axis  300  can be absorbed without preventing the holding frames  31   a  and  31   b  from moving on the plane perpendicular to the optical axis  300 . 
         [0117]    The coupling portion  39   a - d  coupled with the axial member  39   a - a  can slide in the direction perpendicular to the drawing surface of  FIG. 12B  (see arrow  313  in  FIG. 12A ). Therefore, the coupling portion  39   a - d  can flexibly move relative to the movements of the holding frames  31   a  and  31   b.    
         [0118]    When the first lens unit is driven in the direction indicated by an arrow  314   a  illustrated in  FIG. 11 , similar to the above-described first exemplary embodiment, the second lens unit is subjected to the thrust force electromagnetically generated by the interaction between a coil  38   a  and a permanent magnet  37   a  and its reaction force and is driven in the direction indicated by an arrow  314   b  in  FIG. 11  in association with the movement of the connecting member  39   a.    
         [0119]    With this arrangement, the correction lenses  30   a  and  30   b  (a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis  300 . The movement of the connecting members  39   a  prevents the first and the second lens units from rotating in the direction indicated by the arrow  311   r . Therefore, the first and second lens units can be shifted and driven adequately. 
         [0120]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  30   a  and  30   b . When the image blur correction is performed, the correction lenses  30   a  and  30   b  can be driven with a small amount of driving force. Therefore, the present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0121]      FIG. 13  illustrates a front view of an image blur correction apparatus according to a fourth exemplary embodiment of the present invention.  FIG. 14  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 7 -A 8  illustrated in  FIG. 13 .  FIGS. 15A and 15B  illustrate enlarged views of a portion indicated by E in  FIG. 14 . Compared to the above-described first exemplary embodiment, the fourth exemplary embodiment uses a different structure for connecting the first and second lens units. Constituent members of the fourth exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIGS. 1 to 4  although the most significant digit is replaced with “4.” For example, a correction lens  40   a  is functionally equivalent to the correction lens  10   a . Directions indicated by arrows  411   p ,  411   y , and  411   r  are similar to the directions indicated by the arrows  111   p ,  111   y , and  111   r , respectively. 
         [0122]    In the fourth exemplary embodiment, the first lens unit includes a holding frame  41   a  and the correction lens  40   a . The second lens unit includes a holding frame  41   b  and a correction lens  40   b . Two connecting members  49   a  and  49   b  connect the first and second lens units. 
         [0123]    The connecting member  49   a  (as a representative of two connecting members  49   a  and  49   b ) is described in more detail with reference to  FIGS. 15A and 15B . Although  FIG. 13  illustrates the connecting members  49   a  and  49   b  as if they are visibly, the connecting members  49   a  and  49   b  are sandwiched between two holding frames  41   a  and  41   b.    
         [0124]    The connecting member  49   a  includes an axial member  49   a - a  attached to a base plate  42  and a pinion portion  49   a - b  engaged with rack portions provided on the holding frames  41   a  and  41   b . The connecting member  49   a  can rotate around the axial member  49   a - a  in the direction indicated by an arrow  412  on the drawing surface of  FIG. 15B . As the pinion portion  49   a - b  can slide in the direction perpendicular to the drawing surface (see arrow  413  in  FIGS. 15A ), the pinion portion  49   a - b  can flexibly move relative to the movements of the holding frames  41   a  and  41   b.    
         [0125]    When the first lens unit is driven in the direction indicated by an arrow  414   a  in  FIG. 14 , similar to the above-described first exemplary embodiment, the second lens unit is subjected to the thrust force electromagnetically generated by the interaction between a coil  48   a  and a permanent magnet  47   a  and its reaction force and is driven in the direction indicated by an arrow  414   b  in  FIG. 14  in association with the movement of the connecting member  49   a.    
         [0126]    With this arrangement, the correction lenses  40   a  and  40   b  (a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis  400 . The movement of the connecting members  49   a  prevents the first and the second lens units from rotating in the direction indicated by the arrow  411   r . Therefore, the first and second lens units can be shifted and driven adequately. 
         [0127]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  40   a  and  40   b . When the image blur correction is performed, the correction lenses  40   a  and  40   b  can be driven with a small amount of driving force. Therefore, the present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0128]      FIG. 16  illustrates a front view of an image blur correction apparatus according to a fifth exemplary embodiment of the present invention.  FIG. 17  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 9 -A 10  illustrated in  FIG. 16 .  FIG. 18  illustrates an enlarged view of a portion indicated by F in  FIG. 17 . Compared to the above-described first exemplary embodiment, the fifth exemplary embodiment uses a different structure for connecting the first and second lens units. Constituent members of the fifth exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIGS. 1 to 4  although the most significant digit is replaced with “5.” For example, a correction lens  50   a  is functionally equivalent to the correction lens  10   a . Directions indicated by arrows  511   p ,  511   y , and  511   r  are similar to the directions indicated by the arrows  111   p ,  111   y , and  111   r , respectively. 
         [0129]    In the fifth exemplary embodiment, the first lens unit includes a holding frame  51   a  and the correction lens  50   a . The second lens unit includes a holding frame  51   b  and a correction lens  50   b . Three connecting members  59   a ,  59   b , and  59   c  connect the first and second lens units. 
         [0130]    The connecting member  59   b  (as a representative of three connecting members  59   a ,  59   b , and  59   c ) is described in more detail with reference to  FIG. 18 . Although  FIG. 16  illustrates the connecting members  59   a ,  59   b , and  59   c  as if they are visibly, the connecting members  59   a ,  59   b , and  59   c  are sandwiched between two holding frames  51   a  and  51   b.    
         [0131]    The connecting member  59   b  is a spherical member coupled with a spherical coupling portion provided on a base plate  52  and sandwiched between rubber members  510   b  and  510   e  provided on the holding frames  51   a  and  51   b . A sufficient amount of frictional force, acting between the connecting member  59   b  and the rubber members  510   b  and  510   e , causes the holding frames  51   a  and  51   b  to move on the plane perpendicular to an optical axis  500  when the connecting member  59   b  rotates in the direction indicated by an arrow  512  on the drawing surface of  FIG. 18 . 
         [0132]    When the first lens unit is driven in the direction indicated by an arrow  514   a  in  FIG. 17 , similar to the above-described first exemplary embodiment, the second lens unit is subjected to the thrust force to be electromagnetically generated by the interaction between a coil  58   a  and a permanent magnet  57   a  and its reaction force and is driven in the direction indicated by an arrow  514   b  in association with the movement of the connecting member  59   b.    
         [0133]    With this arrangement, the correction lenses  50   a  and  50   b  (a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis  500 . 
         [0134]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  50   a  and  50   b . When the image blur correction is performed, the correction lenses  50   a  and  50   b  can be driven with a small amount of driving force. Therefore, the present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. The rubber members  510   b  and  510   e  according to the present exemplary embodiment can be replaced with any other member that can generate a sufficient amount of frictional force between the connecting member and the first and second lens units. Alternatively, the first and second lens units can be partly processed so as to generate the frictional force. 
         [0135]      FIG. 19  illustrates a front view of an image blur correction apparatus according to a sixth exemplary embodiment of the present invention.  FIG. 20  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 11 -A 12  illustrated in  FIG. 19 .  FIGS. 21A and 21B  illustrate enlarged views of a portion indicated by G in  FIG. 20 . Compared to the above-described first exemplary embodiment, the sixth exemplary embodiment uses a different structure for connecting the first and second lens units. Constituent members of the sixth exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIGS. 1 to 4  although the most significant digit is replaced with “6.” For example, a correction lens  60   a  is functionally equivalent to the correction lens  10   a . Directions indicated by arrows  611   p ,  611   y , and  611   r  are similar to the directions indicated by the arrows  111   p ,  111   y , and  111   r , respectively. 
         [0136]    In the sixth exemplary embodiment, the first lens unit includes a holding frame  61   a  and the correction lens  60   a . The second lens unit includes a holding frame  61   b  and a correction lens  60   b . Three connecting members  69   a ,  69   b , and  69   c  connect the first and second lens units. 
         [0137]    The connecting member  69   b  (as a representative of three connecting members  69   a ,  69   b , and  69   c ) is described in more detail with reference to  FIGS. 21A and 21B . 
         [0138]    The connecting member  69   b  includes an axial member  69   b - a  provided on a base plate  62 , two sliding shafts  69   b - c  and  69   b - d  provided on the holding frames  61   a  and  61   b , and a rotary plate  69   b - b . The rotary plate  69   b - b  can rotate around the axial member  69   b - a.    
         [0139]    The sliding shafts  69   b - c  and  69   b - d  provided on respective holding frames  61   a  and  61   b  are coupled with elongated holes provided on the rotary plate  69   b - b  (see  FIG. 21A ). Therefore, if the holding frame  61   a  moves forward in the direction perpendicular to the drawing surface, the rotary plate  69   b - b  rotates in the direction indicated by an arrow  612  (counterclockwise direction) in  FIG. 21A  and causes the holding frame  61   b  to move backward in the direction perpendicular to the drawing surface. In this case, the rotary plate  69   b - b  can freely slide relative to the sliding shafts  69   b - c  and  69   b - d  provided on respective holding frames  61   a  and  61   b . Therefore, even when a rotational motion around the axial member  69   b - a  is performed, a moving component in the direction of an optical axis  600  can be absorbed without preventing the holding frames  61   a  and  61   b  from moving on the plane perpendicular to the optical axis  600 . 
         [0140]    When the first lens unit is driven in the direction indicated by an arrow  614   a  in  FIG. 20 , similar to the above-described first exemplary embodiment, the second lens unit is subjected to the thrust force electromagnetically generated by the interaction between a coil  68   a  and a permanent magnet  67   a  and its reaction force and is driven in the direction indicated by an arrow  614   b  in association with the movement of the connecting member  69   a.    
         [0141]    As illustrated in  FIG. 19 , the connecting members  69   a ,  69   b , and  69   c  are slidable and disposed at equal angular intervals of 120° around the first and second lens units. The connecting members  69   a ,  69   b , and  69   c  have elongated holes along which the shafts can slide. The connecting members  69   a ,  69   b , and  69   c  cause the first lens unit including correction lens  60   a  and the second lens unit including the correction lens  60   b  to move in mutually opposite directions. 
         [0142]    With this arrangement, the correction lenses  60   a  and  60   b  (a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis  600 . 
         [0143]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  60   a  and  60   b . When the image blur correction is performed, the correction lenses  60   a  and  60   b  can be driven with a small amount of driving force. Therefore, the present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0144]    According to the above-described first to sixth exemplary embodiments, the first lens unit and the second lens unit are connected by a connecting portion so that the first and second lens units can move in mutually opposite directions on the plane perpendicular to the optical axis. For example, according the first exemplary embodiment, the connecting members  19   a  and  19   b  further include the absorbing portions  19   a - b  and  19   a - c  that absorb the moving components in the optical axis direction, which are generated when the connecting members  19   a  and  19   b  rotate relative to the first lens unit and the second lens unit. Accordingly, the present exemplary embodiment can realize the image blur correction with two correction lenses  10   a  and  10   b  of opposite powers that are cooperatively driven so as to move in mutually opposite directions on the plane perpendicular to the optical axis  100 . 
         [0145]    More specifically, to ensure the movements of a pair of correction lenses of opposite powers in mutually opposite directions on the plane perpendicular to the optical axis, two correction lenses are mechanically connected in each of the above-described exemplary embodiments. Thus, compared to the case where only one correction lens is driven, the image blur correction amount is doubled. In other words, the present exemplary embodiments require only a half drive amount to obtain a comparable blur correction amount. 
         [0146]    For example, the correction lenses  10   a  and  10   b  (a pair of correction lenses) cause positional deviations in the same direction due to the weights of the extension springs  15   a  to  15   c . However, as the correction lenses  10   a  and  10   b  have opposite powers, image blur correction effects by the same amount of positional deviations can be mutually canceled. Therefore, the positional deviations of the correction lenses  10   a  and  10   b  caused by their weights do not substantially influence the positional deviation of an image formed on an imaging plane. 
         [0147]    Moreover, the mechanical structure for connecting the correction lenses  10   a  and  10   b  can sufficiently reduce the magnitude of the positional deviation cased by themselves. The size of a required mechanism can be reduced because the correction lenses  10   a  and  10   b  are mutually driven on a plane. 
         [0148]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses. The present exemplary embodiment can realize an image blur correction apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0149]      FIG. 22  illustrates a front view of an image blur correction apparatus to be equipped in a digital camera (imaging apparatus) according to a seventh exemplary embodiment of the present invention.  FIG. 23  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 13 -A 14  illustrated in  FIG. 22 .  FIG. 24  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 13 -H 1  illustrated in  FIG. 22 . Constituent members of the seventh exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIGS. 1 to 4  although the most significant digit is replaced with “7.” For example, a correction lens  70   a  is functionally equivalent to the correction lens  10   a . Directions indicated by arrows  711   p ,  711   y , and  711   r  are similar to the directions indicated by the arrows  111   p ,  111   y , and  111   r , respectively. 
         [0150]    In  FIGS. 22 to 24 , two correction lenses  70   a  and  70   b  have mutually opposite powers for image blur correction. The correction lens  70   a  has positive power. The correction lens  70   b  has negative power. Two holding frames  71   a  and  71   b  hold the correction lenses  70   a  and  70   b , respectively. The image blur correction apparatus further includes a base plate  72 . 
         [0151]    The holding frame  71   a  includes three pins  74   a  to  74   c  disposed at equal angular intervals of 120°, around which ends of extension springs  75   a  to  75   c  are hooked. The holding frame  71   b  includes pins  74   d  to  74   f  (although only one extension spring  74   d  is illustrated in  FIG. 23 ) disposed at equal angular intervals of 120°, around which ends of the extension springs  75   d  to  75   f  (although only one extension spring  75   d  is illustrated in  FIG. 23 ) are hooked. The base plate  72  includes three pins  73   a  to  73   c  disposed at equal angular intervals of 120°, around which the other ends of the extension springs  75   a  to  75   c  are hooked. Although not illustrated in  FIG. 22 , the base plate  72  includes three pins  73   d  to  73   f  disposed at equal angular intervals of 120° on its reverse surface (although only one pin  73   d  is illustrated in  FIG. 23 ). 
         [0152]    The extension springs  75   a  to  75   f  are provided between the pins  74   a  to  74   f  of the holding frame  71   a  and  71   b  and the pins  73   a  to  73   f  of the base plate  72 . The extension springs  75   a  to  75   f , as illustrated in  FIG. 23 , generate a tensile force acting in the direction of an optical axis  700  (right-and-left direction in  FIG. 23 ). As illustrated in  FIG. 23 , balls  76   a  to  76   c  (although only one ball  76   a  is illustrated in  FIG. 23 ) are sandwiched between the holding frame  71   a  and the base plate  72 . The holding frame  71   a  and the base plate  72  are resiliently urged by an optical axis direction component of the tensile force generated by the extension springs  75   a  to  75   c.    
         [0153]    The holding frames  71   a  and  71   b  can move relative to the base plate  72  in the directions indicated by arrows  711   p  and  711   y  in  FIG. 22 . However, the movement of respective holding frames  71   a  and  71   b  in the optical axis  700  direction is restricted. The extension springs  75   a  to  75   f  add necessary and sufficient force to the holding frames  71   a  and  71   b  in radial directions as illustrated in  FIG. 22 . Therefore, the extension springs  75   a  to  75   f  prevent the holding frames  71   a  and  71   b  from rotating in the direction indicated by the arrow  711   r.    
         [0154]    When moving in the directions indicated by the arrows  711   p  and  711   y , initial tensile forces of respective extension springs  75   a  to  75   f  are mutually cancelled because they are equally distributed in radial directions. Therefore, the driving force required is determined based on only the spring constants of the extension springs  75   a  to  75   f  (regardless of their initial tensile forces). Accordingly, the movements in the directions indicated by the arrows  711   p  and  711   y  can be realized with a relatively small amount of force. 
         [0155]    A coil  78   a  is fixed to an arm portion provided on the holding frame  71   a  in a confronting relationship with a yoke  710   a  and a permanent magnet (e.g., a neodymium magnet)  77   a  fixed to the holding frame  71   b , as illustrated in  FIGS. 23 and 24 . A coil  78   b  is fixed to an arm portion provided on the holding frame  71   b  in a confronting relationship with a yoke  710   b  and a permanent magnet (e.g., a neodymium magnet)  77   b  fixed to the holding frame  71   a , as illustrated in  FIG. 24 . 
         [0156]    The permanent magnets  77   a  and  77   b  are magnetized in their thickness directions as illustrated in  FIGS. 23 and 24 . The magnetic fluxes of respective permanent magnets  77   a  and  77   b  penetrate the coils  78   a  and  78   b , which are present on the opposed surfaces, in the direction parallel to the optical axis  700  (in the right-and-left direction in  FIGS. 23 and 24 ). 
         [0157]    The holding frame  71   a  and the correction lens  70   a  constitute the first lens unit. The holding frame  71   b  and the correction lens  70   b  constitute the second lens unit. Further, the balls  76   a  to  76   f  and the extension springs  75   a  to  75   f  constitute an elastic supporting portion. Moreover, the coil  78   a  and the permanent magnet  77   b  (which constitute part of the first lens unit) and the coil  78   b  and the permanent magnet  77   a  (which constitute part of the second lens unit) cooperatively constitute the driving portion. 
         [0158]    With this arrangement, if the correction lens  70   a  and the correction lens  70   b  are substantially equivalent in weight, the first lens unit and the second lens unit are equivalent in weight. The positional deviation caused by the weight of the first lens unit can be equalized with the positional deviation caused by the weight of the second lens unit. 
         [0159]    A driving mechanism of the above-described driving portion is described below. 
         [0160]    The driving portion, as described above, includes the coil  78   a  and the permanent magnet  77   b  (which constitute part of the first lens unit) and the coil  78   b  and the permanent magnet  77   a  (which constitute part of the second lens unit). The magnetic fluxes generated by the permanent magnets  77   a  and  77   b  respectively penetrate the coils  78   a  and  78   b  perpendicularly. Therefore, if current flows through the coil  78   a , as illustrated in  FIG. 22 , the holding frame  71   a  is efficiently driven in the direction indicated by an arrow  713   a . Similarly, if current flows through the coil  78   b , the holding frame  71   a  is efficiently driven in the direction indicated by an arrow  713   b.    
         [0161]    The drive amount by the driving portion is determined according to the balance relationship between the resilient force of the extension springs  75   a ,  75   b ,  75   c ,  75   d ,  75   e , and  75   f  (i.e., forces derived from their spring constants) and the thrust force to be electromagnetically generated by the interaction between the coils  78   a  and  78   b  and the permanent magnets  77   a  and  77   b . In other words, the eccentric amount of the correction lens  70   a  can be controlled based on the amount of current flowing through the coils  78   a  and  78   b.    
         [0162]    The driving circuit illustrated in  FIG. 5  is also applicable to control the driving of the correction lens  70   a.    
         [0163]    The pitch target value  51   p  and the yaw target value  51   y  are drive target values to be used to drive each lens unit (correction lens) in the arrow  711   p  direction (pitch direction) and the arrow  711   y  direction (yaw direction). The pitch target value  51   p  and the yaw target value  51   y  correspond to the differential unit  1418   p  illustrated in  FIG. 34 . The pitch driving force adjusting unit  52   p  and the yaw driving force adjusting unit  52   y  perform gain adjustment for the target values in the pitch and yaw directions according to the driving forces of respective driving directions. 
         [0164]    The coil  78   a  driving circuit  54   a  (which corresponds to the PWM duty conversion unit  1419   p  and the driving portion  1420   p  illustrated in  FIG. 34 ) receives an output of the pitch driving force adjusting unit  52   p  and generates current to be supplied to the coil  78   a . The coil  78   b  driving circuit  54   b  (which corresponds to the PWM duty conversion unit  1419   p  and the driving portion  1420   p  illustrated in  FIG. 34 ) receives the output of the pitch driving force adjusting unit  52   p  via the adding circuit  53   b  and generates current to be supplied to the coil  78   b . Namely, the current supplied to the coil  78   a  and the current supplied to the coil  78   b  according to the signal of the pitch drive target value  51   p  are in-phase and same amount. 
         [0165]    When the current supplied to the coil  78   a  and the current supplied to the coil  78   b  are in-phase and same amount, the coil  78   a  generates the driving force in the direction indicated by the arrow  113   a  and the coil  78   b  generates the driving force in the direction indicated by the arrow  113   b , as indicated in  FIG. 6 . Accordingly, the resultant force generates the driving force (see arrow  113   p ) acting in the arrow  711   p  direction (pitch direction). The driving force generated in this case is the composite driving force resulting from 1/√{square root over (2)} of respective driving forces generated by the coils  78   a  and  78   b  because two coils  78   a  and  78   b  are disposed in a 90-degree rotated state. 
         [0166]    When the current supplied to the coil  78   a  and the current supplied to the coil  78   b  are in reversed-phase and same amount, the coil  78   a  generates the driving force in the direction indicated by the arrow  113   a  and the coil  78   b  generates the driving force in the direction indicated by the arrow  113   b ′ (which is opposite to the arrow  113   b ), as indicated in  FIG. 7 . Accordingly, the resultant force generates the driving force (see arrow  113   y ) acting in the arrow  711   y  direction (yaw direction). The driving force generated in this case is the composite driving force resulting from 1/√{square root over (2)} of respective driving forces generated by the coils  78   a  and  78   b  because two coils  78   a  and  78   b  are disposed in a 90-degree rotated state. 
         [0167]    The driving force adjusting units  52   p  and  52   y  associate the eccentric sensitivity of the optical system with shake correction amounts of the correction lenses  70   a  and  70   b.    
         [0168]    As described above, when current flows through the coils  78   a  and  78   b , the first lens unit including the holding frame  71   a  and the correction lens  70   a  is driven in relationship with the directions of the magnetic fluxes generated by the permanent magnets  77   a  and  77   b . At the same time, the second lens unit including the holding frame  71   b  and the correction lens  70   b  is subjected to its reaction force and is driven in a direction opposite to the moving direction of the first lens unit on the plane perpendicular to optical axis  700 . Namely, when the first lens unit is driven in the direction indicated by an arrow “ 714   a ” in  FIG. 24 , the second lens unit moves in the opposite direction indicated by an arrow “ 714   b .” In this case, it is necessary that an elastic portion of the first lens unit and an elastic portion of the second lens unit have similar spring constants. 
         [0169]    With the above-described arrangement, if the correction lens  70   a  (which is a convex lens) is driven in a direction “ 714   a ” in  FIG. 24 , the optical axis deflects upward in  FIG. 24  due to eccentricity. If the correction lens  10   b  (which is a concave lens), having a power opposite to that of the correction lens  10   a , is driven in a direction “ 714   b ”, the optical axis deflects upward in  FIG. 24  due to eccentricity. Therefore, a large deflection can be obtained by two correction lenses  70   a  and  70   b  that are driven in mutually opposite directions. Therefore, the large image blur correction can be realized with a small drive amount. 
         [0170]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  70   a  and  70   b . In other words, the present exemplary embodiment can perform ideal image blur correction. The present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0171]    When the optical design is appropriate, deflection directions of the correction lenses  70   a  and  70   b  (i.e., a pair of correction lenses whose powers are equivalent in absolute value and opposite in direction) can be cancelled when the correction lenses deviate due to the gravity. Therefore, the present exemplary embodiment can eliminate the problem of deviation in image formation that may occur in an image blur correction apparatus including only one correction lens. 
         [0172]      FIG. 25  illustrates a front view of an image blur correction apparatus according to an eighth exemplary embodiment of the present invention.  FIG. 26  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 15 -A 16  illustrated in  FIG. 25 . Constituent members of the eighth exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIG. 22  although the most significant digit is replaced with “8.” For example, a correction lens  80   a  is functionally equivalent to the correction lens  70   a . Directions indicated by arrows  811   p ,  811   y , and  811   r  are similar to the directions indicated by the arrows  711   p ,  711   y , and  711   r , respectively. 
         [0173]    In  FIGS. 25 and 26 , correction lenses  80   a  and  80   b  have mutually opposite powers for image blur correction. Two holding frames  81   a  and  81   b  hold the correction lenses  80   a  and  80   b , respectively. The image blur correction apparatus according to the present exemplary embodiment further includes a base plate  82 . The eighth exemplary embodiment is preferably employed in a case where the correction lens  80   a  and the correction lens  80   b  are not equivalent in weight (more specifically, when the correction lens  80   a  is heavier than the correction lens  80   b.    
         [0174]    In the eighth exemplary embodiment, the holding frame  81   a  and the correction lens  80   a  constitute the first lens unit. The holding frame  81   b  and the correction lens  80   b  (which is lighter than the correction lens  80   a ) constitute the second lens unit. Further, balls  86   a  to  86   f  and extension springs  85   a  to  85   f  constitute the supporting portion. 
         [0175]    In the eighth exemplary embodiment, as illustrated in  FIG. 25 , two coils  88   a  and  88   b  are provided as part of the first lens unit. Two permanent magnets  87   a  and  87   b , heavier than the coils  88   a  and  88   b , are provided as part of the second lens unit. Two coils  88   a  and  88   b  and two permanent magnets  87   a  and  87   b  cooperatively constitute the driving portion. 
         [0176]    With the above-described arrangement, the present exemplary embodiment can reduce the weight difference between the first lens unit including the correction lens  80   a  (which is heavier than the correction lens  80   b ) and the second lens unit including the permanent magnets  87   a  and  87   b  (which are heavier than the coils  88   a  and  88   b ). Accordingly, the positional deviation caused by the weight of the first lens unit can be equalized with the positional deviation caused by the weight of the second lens unit. 
         [0177]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  80   a  and  80   b . In other words, the present exemplary embodiment can perform ideal image blur correction. The present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0178]    The mechanism of the driving portion and the arrangement of the supporting portion in the present exemplary embodiment are similar to those described in the first exemplary embodiment and are not described again. 
         [0179]      FIG. 27  illustrates a front view of an image blur correction apparatus according to a ninth exemplary embodiment of the present invention.  FIG. 28  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 17 -A 18  illustrated in  FIG. 27 .  FIG. 29  illustrates a cross-sectional view of the image blur correction apparatus taken along a line A 18 -H 2  illustrated in  FIG. 27 .  FIG. 30  illustrates a cross-sectional view of the image blur correction apparatus taken along a line J-A 18  illustrated in  FIG. 27 .  FIGS. 31A and 31B  illustrate enlarged views of a portion indicated by K in  FIG. 30 . Constituent members of the ninth exemplary embodiment functionally similar to those described in the first exemplary embodiment are denoted by similar reference numerals described in  FIG. 22  although the most significant digit is replaced with “9.” For example, a correction lens  90   a  is functionally equivalent to the correction lens  70   a . Directions indicated by arrows  911   p ,  911   y , and  911   r  are similar to the directions indicated by the arrows  711   p ,  711   y , and  711   r , respectively. 
         [0180]    In  FIGS. 27 to 31 , the correction lenses  90   a  and  90   b  have mutually opposite powers for image blur correction. Two holding frames  91   a  and  91   b  hold the correction lenses  90   a  and  90   b , respectively. The image blur correction apparatus according to the present exemplary embodiment further includes a base plate  92 . 
         [0181]    In the ninth exemplary embodiment, the holding frame  91   a  and the correction lens  90   a  constitute the first lens unit. The holding frame  91   b  and the correction lens  90   b  constitute the second lens unit. Further, balls  96   a  to  96   f  and the extension springs  95   a  to  95   f  constitute the supporting portion. A coil  98   a  serving as part of the first lens unit, a coil  98   b  serving as part of the second lens unit, and permanent magnets  97   a  and  97   b  provided on the base plate  92  in a confronting relationship with the coils  98   a  and  98   b  constitute the driving portion. 
         [0182]    With this arrangement, when the weight of the correction lens  90   a  is substantially equal to the weight of the correction lens  90   b , the weight of the first lens unit can be equalized with the weight of the second lens unit. 
         [0183]    As illustrated in  FIGS. 30 ,  31 A, and  31 B, the holding frames  91   a  and  91   b  are connected via a connecting member  99   a  that includes a spherical sliding rotation center portion  99   a - a  supported by the base plate  92 . The connecting member  99   a  further includes two spherical sliding portions  99   a - b  and  99   a - c  at both ends thereof. The sliding portions  99   a - b  and  99   a - c  can freely slide in through-holes of the holding frame  91   a  and  91   b  in the direction of an optical axis  900 . Another connecting member  99   b  is similar to the connecting member  99   a  in arrangement. 
         [0184]    For example, when the holding frame  91   a  is driven in the direction indicated by an arrow  914   a  (see  FIG. 31B ) on the plane perpendicular to the optical axis  900 , the sliding rotation center portion  99   a - a  is pushed by the sliding portion  99   a - b  and rotates in the direction indicated by an arrow  912 . The other sliding portion  99   a - c  pushes the holding frame  91   b  in the direction indicated by an arrow  914   b.    
         [0185]    In this case, the sliding portions  99   a - b  and  99   a - c  can freely slide in the through-holes of the holding frames  91   a  and  91   b . Therefore, even when a rotational motion around the sliding rotation center portion  99   a - a  is generated, a moving component in the optical axis direction can be absorbed without preventing the holding frames  91   a  and  91   b  from moving on the plane perpendicular to the optical axis  900 . The connecting members  99   a  and  99   b  hold the correction lenses  90   a  and  90   b  (a pair of correction lenses having mutually opposite powers) so as to be movable in mutually opposite directions on the plane perpendicular to the optical axis  900 . 
         [0186]    Similar to the seventh exemplary embodiment, the driving portion causes the first and second lens units to move on the plane perpendicular to the optical axis  900  according to the interaction between the coils  98   a  and  98   b  (part of the first and second lens units) and the permanent magnets  97   a  and  97   b  provided on the base plate  92 . 
         [0187]    With the above-described arrangement, the present exemplary embodiment can sufficiently reduce a deviation of an image to be formed on an imaging plane corresponding to the positional deviation caused by weights of the correction lenses  90   a  and  90   b . The present exemplary embodiment can provide an image blur correction apparatus and an imaging apparatus that are compact in size and consume a small amount of electric power for the image blur correction. 
         [0188]    The present exemplary embodiment can reduce the entire weight of the driving portion because the magnets  97   a  and  97   b  are disposed on the base plate  92 . The present exemplary embodiment can maintain the weight balance of two lens units because a coil movable in one direction is included in each of the first lens unit including the correction lens  90   a  and the second lens unit including the correction lens  90   b.    
         [0189]    According to the above-described seventh to ninth exemplary embodiments, the image blur correction can be realized by moving a pair of correction lenses of opposite powers in mutually opposite directions on the plane perpendicular to the optical axis. To surely cause a pair of correction lenses of opposite powers to move in mutually opposite directions on the plane perpendicular to the optical axis, two lens units each including a correction lens and a holding frame are equivalent in weight as apparent in respective exemplary embodiments. 
         [0190]    Thus, compared to the case where only one correction lens is driven, the image blur correction amount is doubled. In other words, the present exemplary embodiments require only a half drive amount to obtain a comparable blur correction amount. 
         [0191]    For example, a pair of correction lenses causes positional deviations in the same direction due to the weights of the extension springs. However, as the correction lenses have opposite powers, image blur correction effects by the same amount of positional deviations can be mutually canceled. Therefore, the positional deviations of the correction lenses caused by their weights do not substantially influence the positional deviation of an image formed on an imaging plane. Moreover, as the weights of two correction lenses or lens units are substantially similar as described above, the positional deviations caused by their weights can be reduced. 
         [0192]    The size of a required mechanism can be reduced when the correction lenses are mutually driven on a plane. 
         [0193]    In the above-described exemplary embodiments, each lens unit can move in a direction perpendicular to the optical axis. However, it does not necessarily need to move perpendicular to the optical axis so long as it does not deteriorate the performance of the image blur correction apparatus so badly. The example described in the above-described exemplary embodiments is the image blur correction apparatus equipped in a digital camera. However, application of the present invention is not limited to the digital camera. Another exemplary embodiment of the present invention may be embodied as a compact and stable unit applicable to any other imaging apparatus, such as a digital video camera, a monitoring camera, or a web camera. The present invention is further applicable to a portable terminal, such as a binocular or a portable telephone, and is also usable for aberration correction in a polarizing apparatus or an optical axis rotating apparatus incorporated in a stepper or other optical apparatus. 
         [0194]    While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications, equivalent structures, and functions. 
         [0195]    This application claims priority from Japanese Patent Applications No. 2008-107317 filed Apr. 16, 2008 and NO. 2008-107318 filed Apr. 16, 2008, which are hereby incorporated by reference herein in their entirety.