Image stabilization apparatus, imaging apparatus, and optical apparatus

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.

BACKGROUND OF THE INVENTION

1. Field of the Invention

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.

2. Description of the Related Art

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's shooting operations.

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.

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.

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.

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.

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

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.

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.

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.

DETAILED DESCRIPTION OF THE EMBODIMENTS

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.

According to aspects of the present invention, the following first to ninth exemplary embodiments are described below.

FIG. 32illustrates 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 arrows1042pand1042ywith respect to an optical axis41. A camera body1043includes a release button1043a, a mode dial1043b(including a main switch), and a retractable flash unit1043c.

FIG. 33illustrates 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 sensor1044converts an object image into an electric signal.

An image blur correction apparatus1053drives a correction lens1052in two directions indicated by arrows1058pand1058yand performs image blur correction in two directions indicated by arrows1042pand1042yillustrated inFIG. 32, as described below in more detail.

A shake detection unit (e.g., an angular speedometer or an angular accelerometer)1045pdetects a shake amount around an arrow1046p. Another shake detection unit1045ydetects a shake amount around an arrow1046p. A calculation unit1047pconverts an output of the shake detection unit1045pinto a drive target value to be supplied to the correction lens1052. Another calculation unit1047yconverts an output of the shake detection unit1045yinto a drive target value to be supplied to the correction lens1052.

FIG. 34is a block diagram illustrating details of the calculation units1047pand1047yillustrated inFIG. 33. As the calculation units1047pand1047yare similar to each other,FIG. 34illustrates an example circuit arrangement of the calculation unit1047p.

The calculation unit1047pincludes an amplification unit1048pfunctioning also as a DC cut filter, an amplification unit1049pfunctioning also as a low-pass filter, an analog-to-digital conversion unit (hereinafter, referred to as “A/D conversion unit”)1410p, a camera microcomputer1411, and a driving unit1420p, which are constituent elements surrounded by an alternate long and short dash line illustrated inFIG. 34. The camera microcomputer1411includes a storage unit1412p, a differential unit1413p, a DC cut filter1414p, an integration unit1415p, a sensitivity adjusting unit1416p, a storage unit1417p, a differential unit1418p, and a PWM duty conversion unit1419.

In the present invention, the shake detection unit1045pis 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.

The amplification unit1048p, 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 unit1045pand amplifies the received shake signal. The amplification unit1048phas 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.

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 unit1045p. Therefore, the time constant of the amplification unit1048pis 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 unit1048pare set to be able to cut signal components in the frequency range equal to and less than 10 Hz.

In this manner, the amplification unit (DC cut filter)1048phas 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)1048pcan prevent a shake angular velocity signal from deteriorating.

The amplification unit1049p, 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)1048paccording 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 microcomputer1411, the A/D conversion unit1410pcan reduce reading errors that may be caused by noises included in the shake angular velocity signal.

The A/D conversion unit1410psamples an output signal of the amplification unit (low-pass filter)1049p. The camera microcomputer1411receives an output signal of the A/D conversion unit1410p. The amplification unit (DC cut filter)1048pcuts the DC bias components. However, the shake angular velocity signal amplified by the amplification unit (low-pass filter)1049pmay include DC bias components. Therefore, the camera microcomputer1411cuts the DC bias components included in the output signal of the A/D conversion unit1410p.

For example, the storage unit1412pstores 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 unit1413pobtains a difference between a value stored in the storage unit1412pand the present shake angular velocity signal to cut the DC components.

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 filter1414pin the camera microcomputer1411completely cuts the DC components with a digital filter.

Similarly to the amplification unit1048pfunctioning also as an analog DC cut filter, the DC cut filter1414pcan 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.

More specifically, the DC cut filter1414phas 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 filter1414pdecreases the filter cut frequency to 5 Hz→1 Hz→0.5 Hz→0.2 Hz at the time intervals of 50 msec.

However, if a photographer presses a shutter release button by a half depth (i.e., turns on a switch sw1) 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.

Hence, in such a case, the DC cut filter1414pinterrupts 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 filter1414pcompletes 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.

More specifically, the DC cut filter1414pcontrols 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 filter1414pcompletes 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 microcomputer1411inhibits a shooting operation until the DC cut filter1414pcompletes the operation for changing the time constant to a final value.

The integration unit1415pstarts integrating the output signal of the DC cut filter1414pto convert the angular velocity signal into an angle signal. The sensitivity adjusting unit1416pappropriately amplifies the integrated angle signal according to the present camera focal length and object distance information. The sensitivity adjusting unit1416pconverts 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.

The camera microcomputer1411starts 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.

The storage unit1417pand the differential unit1418pcan prevent abrupt starting of the image blur correction operation. The storage unit1417pstores a camera shake angle signal of the integration unit1415pat timing when the shutter release button is half pressed. The differential unit1418pobtains a difference between the output signal of the integration unit1415pand the output signal of the storage unit1417p.

Accordingly, two signals entered to the differential unit1418pare 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 unit1418pbecomes zero. Then, the signal is output continuously starting from zero. The storage unit1417phas a role of setting, as an origin, an integration signal at the timing when the shutter release button is half pressed. Therefore, the storage unit1417pand the differential unit1418pcan prevent the image blur correction apparatus from abruptly starting its operation.

The PWM duty conversion unit1419preceives the target value signal from the differential unit1418p. 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 lens1052is 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.

Hence, the PWM duty conversion unit1419pchanges a coil driving duty according to the target value. For example, when the PWM has the frequency of 20 KHz, the PWM duty conversion unit1419psets the duty to zero if the target value received from the differential unit1418pis “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 unit1419psets 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).

The driving unit1420p(e.g., a conventional PWM driver) receives an output of the PWM duty conversion unit1419pand outputs a drive signal to be applied to the coil of the image blur correction apparatus for the image blur correction. The driving unit1420pis 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 sw1is turned on).

Although not illustrated in the block diagram of theFIG. 34, if the photographer fully presses the shutter release button (when a switch sw2is 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.

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 unit1417pstops storing the output signal of the sensitivity adjusting unit1416p(i.e., goes into a sampling state). Therefore, the differential unit1418preceives the same signal from the sensitivity adjusting unit1416pand the storage unit1417p. The output signal generated by the differential unit1418pbecomes zero. Therefore, the image blur correction apparatus receives no drive target value and performs no image blur correction.

The integration unit1415pcontinues integration operation until the main switch of the camera is turned off. If the shutter release button is again half pressed, the storage unit1417pnewly stores an integration output (holds the signal) If the photographer turns off the main switch, the shake detection unit1045pstops its operation and terminates the image stabilization sequence.

If the signal of the integration unit1415pbecomes larger than a predetermined value, the camera microcomputer1411determines that a panning operation of the camera has been performed and changes the time constant of the DC cut filter1414p. For example, the camera microcomputer1411discards 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.

In this case, the time constant change amount is controlled according to the output of the integration unit1415p. 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 filter1414p. 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 filter1414p. 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 filter1414p.

When the output of the integration unit1415pis a very large value (e.g., when a large angular velocity is generated due to the panning motion of the camera), the camera microcomputer1411resets the operation of the integration unit1415pto prevent saturation (overflow) in calculation. According to the circuit arrangement illustrated inFIG. 34, the amplification unit (DC cut filter)1048pand the amplification unit (low-pass filter)1049pare provided in the calculation unit1047p. However, the amplification unit1048pand the amplification unit1049pcan be provided in the shake detection unit1045p.

FIG. 1illustrates a front view of an image blur correction apparatus according to the first exemplary embodiment of the present invention.FIG. 2illustrates a cross-sectional view of the image blur correction apparatus taken along a line A1-A2illustrated inFIG. 1.FIG. 3illustrates a cross-sectional view of the image blur correction apparatus taken along a B-A2illustrated inFIG. 1.FIG. 4illustrates an enlarged view of a portion indicated by C illustrated inFIG. 3.

InFIGS. 1 to 4, two correction lenses10aand10bhave mutually opposite powers for image blur correction. The correction lens10ahas positive power and the correction lens10bhas negative power. A holding frame11aholds the correction lens10a. A holding frame11bholds the correction lens10b. The image blur correction apparatus further includes a base plate12.

The holding frame11a, as illustrated inFIG. 1, includes pins14ato14cdisposed at equal angular intervals of 120°. Ends of three extension springs15ato15care hooked around the pins14ato14c, respectively. The holding frame lib includes pins14dto14f(although only one pin14dis illustrated inFIGS. 2 and 3) disposed at equal angular intervals of 120°. Ends of the extension springs15dto15f(although only one extension spring15dis illustrated inFIGS. 2 and 3) are hooked around the pins14dto14f, respectively. The base plate12, as illustrated inFIG. 1, includes pins13ato13cprovided on its front surface and disposed at equal angular interval of 120°. The other ends of the extension springs15ato15care hooked around the pins13ato13c. The base plate12includes pins13dto13fdisposed at equal angular intervals of 120° on its reverse surface (although only one pin13dis illustrated inFIGS. 2 and 3).

The extension springs15ato15fare positioned respectively between the pins14ato14fprovided on the holding frames11aor11b, and the pins13ato13fprovided on the base plate12. The extension springs15ato15f, as illustrated inFIGS. 2 and 3, generate tensile force in the direction of an optical axis100(in the right-and-left direction inFIGS. 2 and 3).

Three balls16ato16c(although only one ball16ais illustrated inFIGS. 2 and 3) are sandwiched between the holding frame11aand the base plate12, as illustrated inFIGS. 1 to 3. Therefore, the holding frame11aand the base plate12are resiliently urged by an optical axis100direction component of the tensile force generated by the extension springs15ato15c. Similarly, balls16dto16f(although only one ball16dis illustrated inFIGS. 2 and 3) are sandwiched between the holding frame11band the base plate12. Therefore, the holding frame11band the base plate12are resiliently urged by an optical axis100direction component of the tensile force generated by the extension springs15dto15f.

The holding frames11aand11bcan move relative to the base plate12in the directions indicated by arrows111p,111y, and111rinFIG. 1. However, the movement of respective holding frames11aand11bin the optical axis100direction (i.e., the direction perpendicular to the drawing surface ofFIG. 1) is restricted. The extension springs15ato15fadd necessary and sufficient force to the holding frames11aand lib in radial directions as illustrated inFIG. 1. Therefore, the extension springs15ato15fprevent the holding frames11aand lib from rotating in the direction indicated by the arrow111r.

Movements in the directions indicated by the arrows111pand111yare mutually cancelled because initial tensile forces of respective extension springs15ato15fare equally distributed in radial directions. Therefore, the driving force required is determined based on only the spring constants of the extension springs15ato15f(regardless of their initial tensile forces). Accordingly, the movements in the directions indicated by the arrows111pand111ycan be realized with a relatively small amount of force.

As illustrated inFIG. 3and inFIG. 4(i.e., the enlarged view of the portion C ofFIG. 3), the holding frame11aand the holding frame11bare connected via a connecting member19athat includes a sliding rotational center portion (spherical portion)19a-asupported by the base plate12. The connecting member19aincludes spherical sliding portions19a-band19a-cprovided at both ends thereof. The holding frames11aand11bhave through-holes in which the sliding portions19a-band19a-care placed and can slide in the direction of the optical axis100. In the illustration ofFIG. 1according to the present exemplary embodiment, the connecting members19aand19bare disposed on the base plate12in a point-symmetric relationship with respect to the optical axis100, so that the connecting members19aand19bcause 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 members19aand19band their positions are changeable.

Therefore, for example, when the holding frame11ais driven in the direction indicated by an arrow114a(seeFIG. 4) on the plane perpendicular to the optical axis100, the sliding rotational center portion19a-ais pushed by the sliding portion19a-b. Therefore, the sliding rotational center portion19a-arotates in the direction indicated by an arrow112inFIG. 4. The sliding portion19a-cpushes the holding frame lib in the direction indicated by an arrow114b(seeFIG. 4). In this case, the sliding portions19a-band19a-ccan freely slide in the through-holes of the holding frames11aand11b.

Accordingly, even when a rotational motion around the sliding rotational center portion19a-ais performed, a moving component in the direction of the optical axis100can be absorbed without preventing the holding frames11aand lib from moving on the plane perpendicular to the optical axis100. The connecting member19aholds each of the correction lenses10aand10b(i.e., a pair of correction lenses having mutually opposite powers) on planes perpendicular to the optical axis so that the correction lenses10aand10bcan move in mutually opposite directions. Although not illustrated, the connecting member19bis similar to the connecting member19ain structure. Therefore, the connecting member19bholds each of the correction lenses10aand10bon the planes perpendicular to the optical axis so that the correction lenses10aand10bcan move in mutually opposite directions.

As illustrated inFIGS. 1 and 2, coils18aand18b(although only one coil18ais illustrated inFIG. 2) are fixed to arm portions of the holding frame11ain a confronting relationship with yokes110aand110b(although only one yoke110ais illustrated inFIG. 2) and permanent magnets17aand17bsuch as neodymium magnets (although only one permanent magnet17ais illustrated inFIG. 2) fixed to the holding frame11b. The permanent magnets17aand17bare magnetized in their thickness directions as illustrated inFIG. 2. The magnetic fluxes of the magnets17aand17bpenetrate the coils18aand18b, which are present on the opposed surfaces, in the direction parallel to the optical axis100(in the right-and-left direction inFIG. 2).

A driving mechanism of the above-described driving portion is described below. As described above, the coils18aand18b(part of a first lens unit) and the permanent magnets17aand17b(part of a second lens unit) cooperatively constitute the driving portion. The magnetic fluxes of respective permanent magnets17aand17bpenetrate the coils18aand18bperpendicularly. Therefore, if current flows through the coil18a, the holding frame11ais efficiently driven in the direction indicated by an arrow113ainFIG. 1. Similarly, if current flows through the coil18b, the holding frame11ais efficiently driven in the direction indicated by an arrow113binFIG. 1.

The drive amount by the driving portion is determined according to the balance relationship between the resilient force of the extension springs15a,15b,15c,15d,15e, and15f(i.e., forces derived from their spring constants) and the thrust force to be electromagnetically generated by the interaction between the coils18aand18band the permanent magnets17aand17b. In other words, the eccentric amount of the correction lens10a(image blur correction amount by the correction lens10a) can be controlled based on the amount of current flowing through the coils18aand18b.

FIG. 5is a block diagram illustrating a driving circuit that controls the driving of the correction lens10a. A pitch target value51pand a yaw target value51yare drive target values for image blur correction to be used to drive the lens unit in the arrow111pdirection (pitch direction) and the arrow111ydirection (yaw direction) illustrated inFIG. 1. The pitch target value51pand the yaw target value51ycorrespond to the differential unit1418pillustrated inFIG. 34.

A pitch driving force adjusting unit52pand a yaw driving force adjusting unit52yperform gain adjustment for the target values in the pitch and yaw directions according to the driving forces of respective driving directions. A coil18adriving circuit54a(which corresponds to the PWM duty conversion unit1419pand the driving portion1420pillustrated inFIG. 34) receives an output of the pitch driving force adjusting unit52pand generates current to be supplied to the coil18a. A coil18bdriving circuit54b(which corresponds to the PWM duty conversion unit1419pand the driving portion1420pillustrated inFIG. 34) receives the output of the pitch driving force adjusting unit52pvia an adding circuit53band generates current to be supplied to the coil18b. Namely, the current supplied to the coil18aand the current supplied to the coil18baccording to the signal of the pitch drive target value51pare in-phase and same amount.

The coil18bdriving circuit54b(which corresponds to the PWM duty conversion unit1419pand the driving portion1420pillustrated inFIG. 34) receives an output of the yaw driving force adjusting unit52yand generates current to be supplied to the coil18b. The coil18adriving circuit54a(which corresponds to the PWM duty conversion unit1419pand the driving portion1420pillustrated inFIG. 34) receives the output of the yaw driving force adjusting unit52yvia an inversion circuit53aand generates current to be supplied to the coil18b. Namely, the current supplied to the coil18aand the current supplied to the coil18baccording to the signal of the yaw drive target value51yare in reverse-phase to each other and same amount.

When the current supplied to the coil18aand the current supplied to the coil18bare in-phase and same amount, the coil18agenerates the driving force in the direction indicated by the arrow113aand the coil18bgenerates the driving force in the direction indicated by the arrow113b, as indicated inFIG. 6. Accordingly, the resultant force generates the driving force acting in the arrow113p(arrow111p) 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 coils18aand18bbecause two coils18aand18bare disposed in a 90-degree rotated state.

When the current supplied to the coil18aand the current supplied to the coil18bare out-of-phase and same amount, the coil18agenerates the driving force in the direction indicated by the arrow113aand the coil18bgenerates the driving force in the direction indicated by the arrow113b′ (which is opposite to the arrow113b), as indicated inFIG. 7. Accordingly, the resultant force generates the driving force acting in the arrow113y(arrow111y) 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 coils18aand18bbecause two coils18aand18bare disposed in a 90-degree rotated state.

The pitch driving force adjusting unit52pand the yaw driving force adjusting unit52yassociate the eccentric sensitivity of the optical system with shake correction amounts of the correction lenses10aand10b.

As described above, when current flows through the coils18aand18b, the first lens unit including the holding frame11aand the correction lens10ais driven in relationship with the directions of the magnetic fluxes generated by the permanent magnets17aand17b. At the same time, the second lens unit including the holding frame lib and the correction lens10bis 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 axis100. 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.

The connecting members19aand19bhave 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 axis100(on the plane perpendicular to the optical axis). InFIG. 3, if the correction lens10a(which is a convex lens) is driven in a direction “a”, the optical axis deflects upward inFIG. 3due to eccentricity thereof. If the correction lens10b(which is a concave lens), having a power opposite to that of the correction lens10a, is driven in a direction “b”, the optical axis deflects upward inFIG. 3due to eccentricity thereof. Therefore, a large deflection can be obtained by two correction lenses10aand10bthat are driven in mutually opposite directions. Therefore, the large image blur correction can be realized with a small drive amount.

In a case where respective lens units are simply supported by the extension springs15ato15fand the balls16ato16f, it is required that the first lens unit and the second lens unit are equivalent in weight to prevent the optical axis100from decentering due to the gravity. However, the presence of the connecting members19aand19bcan 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 portion19a-ato respective sliding portions19a-band19a-cprovided on the connecting member19ato have a ratio in length opposite to the ratio in weight between two lens units inFIG. 4.

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.

FIG. 8illustrates a front view of an image blur correction apparatus according to a second exemplary embodiment of the present invention.FIG. 9illustrates a cross-sectional view of the image blur correction apparatus taken along a line A3-A4illustrated inFIG. 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.

In the second exemplary embodiment, a supporting portion includes extension springs25aand25bsupporting the first lens unit and the balls26ato26fsandwiched between a base plate22and holding frames21aand21b. The holding frame21aincludes pins24aand24bdisposed at angular intervals of 180°, as illustrated inFIG. 8, around which ends of the extension springs25aand25bare hooked. The holding frame21bincludes pins24dand24edisposed at angular intervals of 180° (although only one pin24dis illustrated inFIG. 9), around which ends of extension springs25dand25e(although only one extension spring25dis illustrated inFIG. 9) are hooked. The base plate22includes pins23aand23bdisposed at angular intervals of 180°, as illustrated inFIG. 8, around which the other ends of the extension springs25aand25bare hooked. Although not illustrated inFIG. 8, the base plate22includes pins23dand23edisposed at angular intervals of 180° on its reverse surface (although only one pin23eis illustrated inFIG. 9.

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 inFIGS. 1 to 4although the most significant digit is replaced with “2.” For example, a correction lens20ais functionally equivalent to the correction lens10a. Directions indicated by arrows211p,211y, and211rare similar to the directions indicated by the arrows111p,111y, and111r, respectively.

In the second exemplary embodiment, the first lens unit includes a holding frame21aand the correction lens20a. The second lens unit includes a holding frame21band a correction lens20b. The first and second lens units are connected to each other with string members210aand210b(although only one string member210ais illustrated inFIG. 9) via roller members29aand29brotatably attached to the base plate22.

According to the example illustrated inFIG. 9, if the first lens unit moves in the direction indicated by an arrow212ainFIG. 9, the second lens unit is pulled in the direction indicated by an arrow212bby the string member210avia the roller member29a. In the present exemplary embodiment, the roller members29aand29bare line-symmetrically disposed with respect to the axis of the211pdirection so that the forces in the211ydirection are balanced.

With the above-described arrangement, the correction lenses20aand20b(a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis200.

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 lenses20aand20b. When the image blur correction is performed, the correction lenses20aand20bcan 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.

FIG. 10illustrates a front view of an image blur correction apparatus according to a third exemplary embodiment of the present invention.FIG. 11illustrates a cross-sectional view of the image blur correction apparatus taken along a line A5-A6illustrated inFIG. 10.FIGS. 12A and 12Billustrate enlarged views of a portion indicated by D inFIG. 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 inFIGS. 1 to 4although the most significant digit is replaced with “3.” For example, a correction lens30ais functionally equivalent to the correction lens10a. Directions indicated by arrows311p,311y, and311rare similar to the directions indicated by the arrows111p,111y, and111r, respectively.

In the third exemplary embodiment, the first lens unit includes a holding frame31aand the correction lens30a. The second lens unit includes a holding frame31band a correction lens30b. Two connecting members39aand39bconnect the first lens unit and the second lens unit.

FIGS. 12A and 12Billustrate details of the connecting member39a. AlthoughFIG. 10illustrates the connecting members39aand39bas if they are visibly, the connecting members39aand39bare sandwiched between two holding frames31aand31b.

The connecting member39aincludes an axial member39a-aattached to a base plate32, two sliding portions39a-band39a-choused in through-holes of the holding frames31aand31b, and, a coupling portion39a-d. The connecting member39acan rotate around the axial member39a-ain the direction indicated by an arrow312on the drawing surface ofFIG. 12B. The sliding portions39a-band39a-ccan freely slide in the through-holes of the holding frames31aand31b. Therefore, even when a rotational motion around the axial member39a-ais performed, a moving component in the direction of an optical axis300can be absorbed without preventing the holding frames31aand31bfrom moving on the plane perpendicular to the optical axis300.

The coupling portion39a-dcoupled with the axial member39a-acan slide in the direction perpendicular to the drawing surface ofFIG. 12B(see arrow313inFIG. 12A). Therefore, the coupling portion39a-dcan flexibly move relative to the movements of the holding frames31aand31b.

When the first lens unit is driven in the direction indicated by an arrow314aillustrated inFIG. 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 coil38aand a permanent magnet37aand its reaction force and is driven in the direction indicated by an arrow314binFIG. 11in association with the movement of the connecting member39a.

With this arrangement, the correction lenses30aand30b(a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis300. The movement of the connecting members39aprevents the first and the second lens units from rotating in the direction indicated by the arrow311r. Therefore, the first and second lens units can be shifted and driven adequately.

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 lenses30aand30b. When the image blur correction is performed, the correction lenses30aand30bcan 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.

FIG. 13illustrates a front view of an image blur correction apparatus according to a fourth exemplary embodiment of the present invention.FIG. 14illustrates a cross-sectional view of the image blur correction apparatus taken along a line A7-A8illustrated inFIG. 13.FIGS. 15A and 15Billustrate enlarged views of a portion indicated by E inFIG. 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 inFIGS. 1 to 4although the most significant digit is replaced with “4.” For example, a correction lens40ais functionally equivalent to the correction lens10a. Directions indicated by arrows411p,411y, and411rare similar to the directions indicated by the arrows111p,111y, and111r, respectively.

In the fourth exemplary embodiment, the first lens unit includes a holding frame41aand the correction lens40a. The second lens unit includes a holding frame41band a correction lens40b. Two connecting members49aand49bconnect the first and second lens units.

The connecting member49a(as a representative of two connecting members49aand49b) is described in more detail with reference toFIGS. 15A and 15B. AlthoughFIG. 13illustrates the connecting members49aand49bas if they are visibly, the connecting members49aand49bare sandwiched between two holding frames41aand41b.

The connecting member49aincludes an axial member49a-aattached to a base plate42and a pinion portion49a-bengaged with rack portions provided on the holding frames41aand41b. The connecting member49acan rotate around the axial member49a-ain the direction indicated by an arrow412on the drawing surface ofFIG. 15B. As the pinion portion49a-bcan slide in the direction perpendicular to the drawing surface (see arrow413inFIG. 15A), the pinion portion49a-bcan flexibly move relative to the movements of the holding frames41aand41b.

When the first lens unit is driven in the direction indicated by an arrow414ainFIG. 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 coil48aand a permanent magnet47aand its reaction force and is driven in the direction indicated by an arrow414binFIG. 14in association with the movement of the connecting member49a.

With this arrangement, the correction lenses40aand40b(a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis400. The movement of the connecting members49aprevents the first and the second lens units from rotating in the direction indicated by the arrow411r. Therefore, the first and second lens units can be shifted and driven adequately.

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 lenses40aand40b. When the image blur correction is performed, the correction lenses40aand40bcan 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.

FIG. 16illustrates a front view of an image blur correction apparatus according to a fifth exemplary embodiment of the present invention.FIG. 17illustrates a cross-sectional view of the image blur correction apparatus taken along a line A9-A10illustrated inFIG. 16.FIG. 18illustrates an enlarged view of a portion indicated by F inFIG. 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 inFIGS. 1 to 4although the most significant digit is replaced with “5.” For example, a correction lens50ais functionally equivalent to the correction lens10a. Directions indicated by arrows511p,511y, and511rare similar to the directions indicated by the arrows111p,111y, and111r, respectively.

In the fifth exemplary embodiment, the first lens unit includes a holding frame51aand the correction lens50a. The second lens unit includes a holding frame51band a correction lens50b. Three connecting members59a,59b, and59cconnect the first and second lens units.

The connecting member59b(as a representative of three connecting members59a,59b, and59c) is described in more detail with reference toFIG. 18. AlthoughFIG. 16illustrates the connecting members59a,59b, and59cas if they are visibly, the connecting members59a,59b, and59care sandwiched between two holding frames51aand51b.

The connecting member59bis a spherical member coupled with a spherical coupling portion provided on a base plate52and sandwiched between rubber members510band510eprovided on the holding frames51aand51b. A sufficient amount of frictional force, acting between the connecting member59band the rubber members510band510e, causes the holding frames51aand51bto move on the plane perpendicular to an optical axis500when the connecting member59brotates in the direction indicated by an arrow512on the drawing surface ofFIG. 18.

When the first lens unit is driven in the direction indicated by an arrow514ainFIG. 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 coil58aand a permanent magnet57aand its reaction force and is driven in the direction indicated by an arrow514bin association with the movement of the connecting member59b.

With this arrangement, the correction lenses50aand50b(a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis500.

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 lenses50aand50b. When the image blur correction is performed, the correction lenses50aand50bcan 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 members510band510eaccording 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.

FIG. 19illustrates a front view of an image blur correction apparatus according to a sixth exemplary embodiment of the present invention.FIG. 20illustrates a cross-sectional view of the image blur correction apparatus taken along a line A11-A12illustrated inFIG. 19.FIGS. 21A and 21Billustrate enlarged views of a portion indicated by G inFIG. 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 inFIGS. 1 to 4although the most significant digit is replaced with “6.” For example, a correction lens60ais functionally equivalent to the correction lens10a. Directions indicated by arrows611p,611y, and611rare similar to the directions indicated by the arrows111p,111y, and111r, respectively.

In the sixth exemplary embodiment, the first lens unit includes a holding frame61aand the correction lens60a. The second lens unit includes a holding frame61band a correction lens60b. Three connecting members69a,69b, and69cconnect the first and second lens units.

The connecting member69b(as a representative of three connecting members69a,69b, and69c) is described in more detail with reference toFIGS. 21A and 21B.

The connecting member69bincludes an axial member69b-aprovided on a base plate62, two sliding shafts69b-cand69b-dprovided on the holding frames61aand61b, and a rotary plate69b-b. The rotary plate69b-bcan rotate around the axial member69b-a.

The sliding shafts69b-cand69b-dprovided on respective holding frames61aand61bare coupled with elongated holes provided on the rotary plate69b-b(seeFIG. 21A). Therefore, if the holding frame61amoves forward in the direction perpendicular to the drawing surface, the rotary plate69b-brotates in the direction indicated by an arrow612(counterclockwise direction) inFIG. 21Aand causes the holding frame61bto move backward in the direction perpendicular to the drawing surface. In this case, the rotary plate69b-bcan freely slide relative to the sliding shafts69b-cand69b-dprovided on respective holding frames61aand61b. Therefore, even when a rotational motion around the axial member69b-ais performed, a moving component in the direction of an optical axis600can be absorbed without preventing the holding frames61aand61bfrom moving on the plane perpendicular to the optical axis600.

When the first lens unit is driven in the direction indicated by an arrow614ainFIG. 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 coil68aand a permanent magnet67aand its reaction force and is driven in the direction indicated by an arrow614bin association with the movement of the connecting member69a.

As illustrated inFIG. 19, the connecting members69a,69b, and69care slidable and disposed at equal angular intervals of 120° around the first and second lens units. The connecting members69a,69b, and69chave elongated holes along which the shafts can slide. The connecting members69a,69b, and69ccause the first lens unit including correction lens60aand the second lens unit including the correction lens60bto move in mutually opposite directions.

With this arrangement, the correction lenses60aand60b(a pair of correction lenses having opposite powers) can be driven in mutually opposite directions on the plane perpendicular to the optical axis600.

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 lenses60aand60b. When the image blur correction is performed, the correction lenses60aand60bcan 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.

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 members19aand19bfurther include the absorbing portions19a-band19a-cthat absorb the moving components in the optical axis direction, which are generated when the connecting members19aand19brotate 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 lenses10aand10bof opposite powers that are cooperatively driven so as to move in mutually opposite directions on the plane perpendicular to the optical axis100.

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.

For example, the correction lenses10aand10b(a pair of correction lenses) cause positional deviations in the same direction due to the weights of the extension springs15ato15c. However, as the correction lenses10aand10bhave opposite powers, image blur correction effects by the same amount of positional deviations can be mutually canceled. Therefore, the positional deviations of the correction lenses10aand10bcaused by their weights do not substantially influence the positional deviation of an image formed on an imaging plane.

Moreover, the mechanical structure for connecting the correction lenses10aand10bcan sufficiently reduce the magnitude of the positional deviation cased by themselves. The size of a required mechanism can be reduced because the correction lenses10aand10bare mutually driven on a plane.

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.

FIG. 22illustrates 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. 23illustrates a cross-sectional view of the image blur correction apparatus taken along a line A13-A14illustrated inFIG. 22.FIG. 24illustrates a cross-sectional view of the image blur correction apparatus taken along a line A13-H1illustrated inFIG. 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 inFIGS. 1 to 4although the most significant digit is replaced with “7.” For example, a correction lens70ais functionally equivalent to the correction lens10a. Directions indicated by arrows711p,711y, and711rare similar to the directions indicated by the arrows111p,111y, and111r, respectively.

InFIGS. 22 to 24, two correction lenses70aand70bhave mutually opposite powers for image blur correction. The correction lens70ahas positive power. The correction lens70bhas negative power. Two holding frames71aand71bhold the correction lenses70aand70b, respectively. The image blur correction apparatus further includes a base plate72.

The holding frame71aincludes three pins74ato74cdisposed at equal angular intervals of 120°, around which ends of extension springs75ato75care hooked. The holding frame71bincludes pins74dto74f(although only one extension spring74dis illustrated inFIG. 23) disposed at equal angular intervals of 120°, around which ends of the extension springs75dto75f(although only one extension spring75dis illustrated inFIG. 23) are hooked. The base plate72includes three pins73ato73cdisposed at equal angular intervals of 120°, around which the other ends of the extension springs75ato75care hooked. Although not illustrated inFIG. 22, the base plate72includes three pins73dto73fdisposed at equal angular intervals of 120° on its reverse surface (although only one pin73dis illustrated inFIG. 23).

The extension springs75ato75fare provided between the pins74ato74fof the holding frame71aand71band the pins73ato73fof the base plate72. The extension springs75ato75f, as illustrated inFIG. 23, generate a tensile force acting in the direction of an optical axis700(right-and-left direction inFIG. 23). As illustrated inFIG. 23, balls76ato76c(although only one ball76ais illustrated inFIG. 23) are sandwiched between the holding frame71aand the base plate72. The holding frame71aand the base plate72are resiliently urged by an optical axis direction component of the tensile force generated by the extension springs75ato75c.

The holding frames71aand71bcan move relative to the base plate72in the directions indicated by arrows711pand711yinFIG. 22. However, the movement of respective holding frames71aand71bin the optical axis700direction is restricted. The extension springs75ato75fadd necessary and sufficient force to the holding frames71aand71bin radial directions as illustrated inFIG. 22. Therefore, the extension springs75ato75fprevent the holding frames71aand71bfrom rotating in the direction indicated by the arrow711r.

When moving in the directions indicated by the arrows711pand711y, initial tensile forces of respective extension springs75ato75fare 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 springs75ato75f(regardless of their initial tensile forces). Accordingly, the movements in the directions indicated by the arrows711pand711ycan be realized with a relatively small amount of force.

A coil78ais fixed to an arm portion provided on the holding frame71ain a confronting relationship with a yoke710aand a permanent magnet (e.g., a neodymium magnet)77afixed to the holding frame71b, as illustrated inFIGS. 23 and 24. A coil78bis fixed to an arm portion provided on the holding frame71bin a confronting relationship with a yoke710band a permanent magnet (e.g., a neodymium magnet)77bfixed to the holding frame71a, as illustrated inFIG. 24.

The permanent magnets77aand77bare magnetized in their thickness directions as illustrated inFIGS. 23 and 24. The magnetic fluxes of respective permanent magnets77aand77bpenetrate the coils78aand78b, which are present on the opposed surfaces, in the direction parallel to the optical axis700(in the right-and-left direction inFIGS. 23 and 24).

The holding frame71aand the correction lens70aconstitute the first lens unit. The holding frame71band the correction lens70bconstitute the second lens unit. Further, the balls76ato76fand the extension springs75ato75fconstitute an elastic supporting portion. Moreover, the coil78aand the permanent magnet77b(which constitute part of the first lens unit) and the coil78band the permanent magnet77a(which constitute part of the second lens unit) cooperatively constitute the driving portion.

With this arrangement, if the correction lens70aand the correction lens70bare 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.

A driving mechanism of the above-described driving portion is described below.

The driving portion, as described above, includes the coil78aand the permanent magnet77b(which constitute part of the first lens unit) and the coil78band the permanent magnet77a(which constitute part of the second lens unit). The magnetic fluxes generated by the permanent magnets77aand77brespectively penetrate the coils78aand78bperpendicularly. Therefore, if current flows through the coil78a, as illustrated inFIG. 22, the holding frame71ais efficiently driven in the direction indicated by an arrow713a. Similarly, if current flows through the coil78b, the holding frame71ais efficiently driven in the direction indicated by an arrow713b.

The drive amount by the driving portion is determined according to the balance relationship between the resilient force of the extension springs75a,75b,75c,75d,75e, and75f(i.e., forces derived from their spring constants) and the thrust force to be electromagnetically generated by the interaction between the coils78aand78band the permanent magnets77aand77b. In other words, the eccentric amount of the correction lens70acan be controlled based on the amount of current flowing through the coils78aand78b.

The driving circuit illustrated inFIG. 5is also applicable to control the driving of the correction lens70a.

The pitch target value51pand the yaw target value51yare drive target values to be used to drive each lens unit (correction lens) in the arrow711pdirection (pitch direction) and the arrow711ydirection (yaw direction). The pitch target value51pand the yaw target value51ycorrespond to the differential unit1418pillustrated inFIG. 34. The pitch driving force adjusting unit52pand the yaw driving force adjusting unit52yperform gain adjustment for the target values in the pitch and yaw directions according to the driving forces of respective driving directions.

The coil78adriving circuit54a(which corresponds to the PWM duty conversion unit1419pand the driving portion1420pillustrated inFIG. 34) receives an output of the pitch driving force adjusting unit52pand generates current to be supplied to the coil78a. The coil78bdriving circuit54b(which corresponds to the PWM duty conversion unit1419pand the driving portion1420pillustrated inFIG. 34) receives the output of the pitch driving force adjusting unit52pvia the adding circuit53band generates current to be supplied to the coil78b. Namely, the current supplied to the coil78aand the current supplied to the coil78baccording to the signal of the pitch drive target value51pare in-phase and same amount.

When the current supplied to the coil78aand the current supplied to the coil78bare in-phase and same amount, the coil78agenerates the driving force in the direction indicated by the arrow113aand the coil78bgenerates the driving force in the direction indicated by the arrow113b, as indicated inFIG. 6. Accordingly, the resultant force generates the driving force (see arrow113p) acting in the arrow711pdirection (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 coils78aand78bbecause two coils78aand78bare disposed in a 90-degree rotated state.

When the current supplied to the coil78aand the current supplied to the coil78bare in reversed-phase and same amount, the coil78agenerates the driving force in the direction indicated by the arrow113aand the coil78bgenerates the driving force in the direction indicated by the arrow113b′ (which is opposite to the arrow113b), as indicated inFIG. 7. Accordingly, the resultant force generates the driving force (see arrow113y) acting in the arrow711ydirection (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 coils78aand78bbecause two coils78aand78bare disposed in a 90-degree rotated state.

The driving force adjusting units52pand52yassociate the eccentric sensitivity of the optical system with shake correction amounts of the correction lenses70aand70b.

As described above, when current flows through the coils78aand78b, the first lens unit including the holding frame71aand the correction lens70ais driven in relationship with the directions of the magnetic fluxes generated by the permanent magnets77aand77b. At the same time, the second lens unit including the holding frame71band the correction lens70bis 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 axis700. Namely, when the first lens unit is driven in the direction indicated by an arrow “714a” inFIG. 24, the second lens unit moves in the opposite direction indicated by an arrow “714b.” 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.

With the above-described arrangement, if the correction lens70a(which is a convex lens) is driven in a direction “714a” inFIG. 24, the optical axis deflects upward inFIG. 24due to eccentricity. If the correction lens10b(which is a concave lens), having a power opposite to that of the correction lens10a, is driven in a direction “714b”, the optical axis deflects upward inFIG. 24due to eccentricity. Therefore, a large deflection can be obtained by two correction lenses70aand70bthat are driven in mutually opposite directions. Therefore, the large image blur correction can be realized with a small drive amount.

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 lenses70aand70b. 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.

When the optical design is appropriate, deflection directions of the correction lenses70aand70b(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.

FIG. 25illustrates a front view of an image blur correction apparatus according to an eighth exemplary embodiment of the present invention.FIG. 26illustrates a cross-sectional view of the image blur correction apparatus taken along a line A15-A16illustrated inFIG. 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 inFIG. 22although the most significant digit is replaced with “8.” For example, a correction lens80ais functionally equivalent to the correction lens70a. Directions indicated by arrows811p,811y, and811rare similar to the directions indicated by the arrows711p,711y, and711r, respectively.

InFIGS. 25 and 26, correction lenses80aand80bhave mutually opposite powers for image blur correction. Two holding frames81aand81bhold the correction lenses80aand80b, respectively. The image blur correction apparatus according to the present exemplary embodiment further includes a base plate82. The eighth exemplary embodiment is preferably employed in a case where the correction lens80aand the correction lens80bare not equivalent in weight (more specifically, when the correction lens80ais heavier than the correction lens80b.

In the eighth exemplary embodiment, the holding frame81aand the correction lens80aconstitute the first lens unit. The holding frame81band the correction lens80b(which is lighter than the correction lens80a) constitute the second lens unit. Further, balls86ato86fand extension springs85ato85fconstitute the supporting portion.

In the eighth exemplary embodiment, as illustrated inFIG. 25, two coils88aand88bare provided as part of the first lens unit. Two permanent magnets87aand87b, heavier than the coils88aand88b, are provided as part of the second lens unit. Two coils88aand88band two permanent magnets87aand87bcooperatively constitute the driving portion.

With the above-described arrangement, the present exemplary embodiment can reduce the weight difference between the first lens unit including the correction lens80a(which is heavier than the correction lens80b) and the second lens unit including the permanent magnets87aand87b(which are heavier than the coils88aand88b). 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.

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 lenses80aand80b. 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.

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.

FIG. 27illustrates a front view of an image blur correction apparatus according to a ninth exemplary embodiment of the present invention.FIG. 28illustrates a cross-sectional view of the image blur correction apparatus taken along a line A17-A18illustrated inFIG. 27.FIG. 29illustrates a cross-sectional view of the image blur correction apparatus taken along a line A18-H2illustrated inFIG. 27.FIG. 30illustrates a cross-sectional view of the image blur correction apparatus taken along a line J-A18illustrated inFIG. 27.FIGS. 31A and 31Billustrate enlarged views of a portion indicated by K inFIG. 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 inFIG. 22although the most significant digit is replaced with “9.” For example, a correction lens90ais functionally equivalent to the correction lens70a. Directions indicated by arrows911p,911y, and911rare similar to the directions indicated by the arrows711p,711y, and711r, respectively.

InFIGS. 27 to 31, the correction lenses90aand90bhave mutually opposite powers for image blur correction. Two holding frames91aand91bhold the correction lenses90aand90b, respectively. The image blur correction apparatus according to the present exemplary embodiment further includes a base plate92.

In the ninth exemplary embodiment, the holding frame91aand the correction lens90aconstitute the first lens unit. The holding frame91band the correction lens90bconstitute the second lens unit. Further, balls96ato96fand the extension springs95ato95fconstitute the supporting portion. A coil98aserving as part of the first lens unit, a coil98bserving as part of the second lens unit, and permanent magnets97aand97bprovided on the base plate92in a confronting relationship with the coils98aand98bconstitute the driving portion.

With this arrangement, when the weight of the correction lens90ais substantially equal to the weight of the correction lens90b, the weight of the first lens unit can be equalized with the weight of the second lens unit.

As illustrated inFIGS. 30,31A, and31B, the holding frames91aand91bare connected via a connecting member99athat includes a spherical sliding rotation center portion99a-asupported by the base plate92. The connecting member99afurther includes two spherical sliding portions99a-band99a-cat both ends thereof. The sliding portions99a-band99a-ccan freely slide in through-holes of the holding frame91aand91bin the direction of an optical axis900. Another connecting member99bis similar to the connecting member99ain arrangement.

For example, when the holding frame91ais driven in the direction indicated by an arrow914a(seeFIG. 31B) on the plane perpendicular to the optical axis900, the sliding rotation center portion99a-ais pushed by the sliding portion99a-band rotates in the direction indicated by an arrow912. The other sliding portion99a-cpushes the holding frame91bin the direction indicated by an arrow914b.

In this case, the sliding portions99a-band99a-ccan freely slide in the through-holes of the holding frames91aand91b. Therefore, even when a rotational motion around the sliding rotation center portion99a-ais generated, a moving component in the optical axis direction can be absorbed without preventing the holding frames91aand91bfrom moving on the plane perpendicular to the optical axis900. The connecting members99aand99bhold the correction lenses90aand90b(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 axis900.

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 axis900according to the interaction between the coils98aand98b(part of the first and second lens units) and the permanent magnets97aand97bprovided on the base plate92.

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 lenses90aand90b. 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 present exemplary embodiment can reduce the entire weight of the driving portion because the magnets97aand97bare disposed on the base plate92. 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 lens90aand the second lens unit including the correction lens90b.

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.

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.

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.

The size of a required mechanism can be reduced when the correction lenses are mutually driven on a plane.

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.

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.