Abstract:
There is provided an image-shake correcting device having a correcting optical unit, which is capable of performing image shake correction with high accuracy using a simple construction and without reducing the degree of freedom of layout and without the need to increase the size of the device. At least one magnet member is provided in the correcting optical unit. At least one coil member is arranged away from the magnet member in a direction of the optical axis of the optical unit. A first magnetic member is arranged away from the magnet member in the direction of the optical axis. A second magnetic member is arranged away from the magnet member in the direction of the optical axis and at a side of the magnetic member remote from the first magnetic member. Energization of the coil member causes the correcting optical unit to be driven in a direction intersecting with the optical axis to correct image shakes.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image-shake correcting device having correcting means for correcting image shakes. 
     2. Description of the Related Art 
     Modern cameras automatically perform all important operations for photographing such as exposure determination and focusing, so that even unskilled camera operators are unlikely to make mistakes in photographing. 
     Further, image stabilizing systems have recently been studied, which prevent a photograph from being influenced by shakes of a camera, thereby substantially eliminating factors that induce the photographer&#39;s mistakes in photographing. 
     Here, an image stabilizing system for cameras will be described. 
     Unwanted shakes of a camera during photographing are vibrations typically having a frequency of 1 to 10 Hz. A basic concept of obtaining photographs free from image shakes even if the camera shakes at the time of shutter release is that vibrations of the camera resulting from shakes thereof are detected, and a correcting lens is displaced based on the detected vibration value. Therefore, to take photographs having no image shakes or image blurs even with shakes of the camera, first, vibrations of the camera must be accurately detected, and secondly, changes in the optical axis due to shakes of the camera must be corrected. 
     A basic system for detecting vibrations or shakes of a camera is realized by a shake detecting device installed in the camera, which is comprised of a shake sensor for detecting acceleration, angular acceleration, angular velocity, angular displacement, or the like, and an arithmetic section that arithmetically processes an output from the shake sensor, for camera-shake correction. Based on the detected information, correcting means that decenters the photographic optical axis is driven to suppress image shakes. 
     FIG. 8 is a schematic perspective view generally showing a camera equipped with a conventional image stabilizing system. This image stabilizing system has a function of performing shake correction for vertical and horizontal shakes of the camera as shown by arrows  42   p  and  42   y , respectively, with respect to an optical axis  41 . 
     In the camera  43 , reference numerals  43   a ,  43   b ,  43   c , and  43   d  denote a release button, a mode dial (including a main switch), a retractable flash unit, and a finder window, respectively. 
     FIG. 9 is a perspective view showing the internal construction of the camera in FIG.  8 . In FIG. 9, reference numerals  44 ,  51 , and  52  denote a camera main body, correcting means, and a correcting lens, respectively. Reference numeral  53  denotes a support frame that freely drives the correcting lens  52  in directions  58   p  and  58   y , shown in the figure, to execute shake corrections in the directions shown by the arrows  42   p  and  42   y  in FIG.  8 . The correcting lens  52  will be described later in detail. Reference numerals  45   p  and  45   y  denote shake detecting devices such as an angular velocity meter and an angular acceleration meter which detect shakes of the camera in directions  46   p  and  46   y.    
     Outputs from the shake detecting devices  45   p  and  45   y  are converted into a drive target value for the correcting means via arithmetic devices  47   p  and  47   y , described later. The drive target value is input to coils provided in the correcting means  51  for shake corrections. Reference numerals  54 ,  56   p  and  56   y , and  510   p  and  510   y  denote a base plate, permanent magnets, and the coils, respectively. 
     FIG. 10 is a block diagram showing the details of the arithmetic devices  47   p  and  47   y  in FIG.  9 . The arithmetic devices  47   p  and  47   y  are constructed similarly to each other, and therefore in FIG. 10, only the arithmetic device  47   p  is shown and will be described. 
     The arithmetic device  47   p  is shown enclosed by one-dot chain lines and comprised of a DC cut filter  48   p , a low-pass filter  49   p , an analog-to-digital conversion circuit (hereafter simply referred to as the “A/D conversion circuit”)  410   p , and a drive device  419   p , as well as a camera microcomputer  411  which is enclosed by broken lines. The camera microcomputer  411  is comprised of a storage circuit  412   p , a differential circuit  413   p , a DC cut filter  414   p , an integrating circuit  415   p , a storage circuit  416   p , a differential circuit  417   p , and a PWM (Pulse Width Modulation) duty changing circuit  418   p.    
     In the illustrated example, the shake detecting device  45   p  is comprised of a laser gyro that detects the angular velocity of shakes of the camera  43 . The laser gyro is driven in synchronism with turning-on of the main switch of the camera to start detecting the angular velocity of shakes of the camera  43 . 
     An output signal from the shake detecting device  45   p  is subjected to cutting-off of DC bias components superimposed on the signal by the DC cut filter  48   p  composed of an analog circuit. The DC cut filter  48   p  has such a frequency characteristic that frequencies of 0.1 Hz and less are cut off, and thus does not affect the frequency band of shakes of the camera, which typically ranges from 1 to 10 Hz. However, a problem with the characteristic that frequencies of 0.1 Hz and less are cut off is that about 10 seconds elapse after a shake signal has been input from the shake detecting device  45   p  and before the DC components are completely cut off. Thus, a smaller time constant is used for the DC cut filter  48   p  (the characteristic is set such that for example, frequencies of 10 Hz and less are cut off) before, for example, 0.11 seconds elapse after the main switch of the camera is turned on, so that the DC components are cut off in a short time such as 0.1 seconds, and then the time constant is increased (the characteristic is set such that the frequencies of 0.1 Hz and less are cut off), thereby preventing the DC cut filter  48   p  from degrading a shake angular velocity signal from the shake detecting device  45   p.    
     An output signal from the DC cut filter  48   p  is amplified by the low pass filter  49   p  composed of an analog circuit, at an amplification ratio according to the resolution of the A/D conversion circuit  410   p , while high frequency noise components superposed on the shake angular velocity signal are cut off. This cutting-off of high frequency noise components is carried out to prevent the A/D conversion circuit  410   p  from erroneously sampling the shake angular velocity signal input to the camera microcomputer  411 . Further, an output signal from the low pass filter  49   p  is sampled by the A/D conversion circuit  410   p  and the resulting digital signal is delivered to the camera microcomputer  411 . 
     As noted above, the DC bias components are cut off by the DC cut filter  48   p . However, the subsequent amplification by the low pass filter  49   p  causes DC bias components to be again superposed on the shake angular velocity signal. Therefore, the DC bias components must be cut off again in the camera microcomputer  411 . 
     Thus, for example, the DC components are cut off by storing, in the storage circuit  412 P, a shake angular velocity signal which is sampled 0.2 seconds after turning-on of the main switch of the camera  43 , and determining a difference between the previously stored value and the newly stored shake angular velocity signal by means of the differential circuit  413   p . This operation can only roughly cut off the DC components because the shake angular velocity signal stored 0.2 seconds after turning-on of the main switch of the camera  43  contains not only DC components but also actual shake components. Therefore, in a subsequent stage, DC components not removed by the differential circuit  413   p  are completely cut off by the DC cut filter  414   p  composed of a digital filter. The time constant of the digital filter  414   p  can be varied as is the case with the analog DC cut filter  48   p . Specifically, the time constant is progressively increased over 0.2 seconds after the lapse of 0.2 seconds have elapsed after turning-on of the main switch of the camera  43 . More specifically, the filter characteristic of the DC cut filter  414   p  is preset such that frequencies of 10 Hz and less are cut off when 0.2 seconds have elapsed after turning-on of the main switch, and subsequently the cutoff frequency of the filter is gradually reduced to 5, 1, 0.5, and 0.2 Hz every 50 msec. 
     However, if during the above-described operation, the photographer half-depresses the release button  43   a  (turns on a switch S 1 ) to perform a photometric operation or a distance measuring operation, he is likely to immediately carry out photographing. In such a case, it is not desirable to change the time constant over a considerable time. Therefore, in such a case, the change of the time constant is interrupted depending upon the photographing conditions. For example, if the results of the photometric operation indicate that the shutter speed should be {fraction (1/60)}, and the focal distance is 150 mm, then high shake-correcting precision is not required, so that the change of the time constant for the DC cut filter  414   p  is stopped when the time constant is changed to such a characteristic as to cut off frequencies of 0.5 Hz and less (the amount of change of the time constant is controlled according to the product of the shutter speed and the shooting focal distance). This reduces the time required to change the time constant, thus giving priority to the shutter chance. Of course, it may be so designed that with a higher shutter speed or a shorter focal distance, the change of the time constant of the DC cut filter  414   p  is stopped when the time constant is changed to such a characteristic as to cut off frequencies of 1 Hz and less, whereas with a lower shutter speed or a longer focal distance, shooting is inhibited until the change of the time constant to the set greatest value is completed. 
     The integrating circuit  415   p  starts integrating output signals from the DC cut filter  414   p  in response to half depression of the camera release button  43   a  (turning-on of the switch S 1 ), to convert the angular velocity signal into an angular signal. However, so long as the change of the time constant of the DC cut filter  414   p  has not been completed yet, the integrating circuit  415   p  does not perform the integration operation until the change of the time constant is completed, as described previously. Although not shown in FIG. 10, the integrated angular signal is amplified at an amplification ratio according to the current focal distance and object distance information and converted so as to drive the correcting means  51  by an appropriate amount according to the angle of shakes. This correction is required because a zoom focusing operation causes a change in the photographic optical system and hence a change in the amount of eccentricity of the optical axis with respect to the amount by which the correcting means  51  is driven. 
     When the release button  43   a  is fully depressed (a switch S 2  is turned on), the correcting means  51  starts to be driven in accordance with the shake angular signal. However, at this time, care must be taken such that the correction means  51  does not suddenly start a shake correcting operation. The storage circuit  416   p  and the differential circuit  417  are provided for this purpose. The storage circuit  416   p  stores the shake angular signal from the integrating circuit  415   p  in synchronism with the full depression of the release button  43   a  (turning-on of the switch S 2 ). The differential circuit  417   p  determines a difference between the signal from the integrating circuit  415   p  and a signal from the storage circuit  416   p . Thus, when the switch S 2  is turned on, the two signals input to the differential circuit  417   p  are equal to each other, and a drive target value signal supplied to the correcting means  51  from the differential circuit  417   p  is zero. However, the output from the differential circuit  417   p  subsequently consecutively increases from zero. That is, the storage circuit  416   p  plays a role in setting the integration signal as the origin when the switch S 2  is turned on. This prevents the correcting means  51  from suddenly starting to be driven. 
     The target value signal from the differential circuit  417   p  is input to the PWM duty changing circuit  418   p . When voltage or current corresponding to the angle of shakes is applied to the coil  510   p  (see FIG. 9) provided in the correcting means  51 , the correcting lens  52  is driven correspondingly to the angle of shakes. PWM driving is preferably used to save power consumed to drive the correcting means  51  and a drive transistor for the coil. 
     Thus, the PWM duty changing circuit  418   p  changes the coil drive duty according to the target value. For example, in the case of PWM using a frequency of 20 KHz, the duty is set to “0” when the target value from the differential circuit  417   p  is “2,048” and to “100” when the target value is “4,096”. Then, the range between the duty of “0” and the duty of “100” is divided at equal intervals so that the duty is determined according to the target value. The duty determination precisely controlled based not only on the target value but also on the current photographing conditions for the camera  43  including temperature, the position of the camera, and the state of the power supply, so as to achieve precise shake corrections. 
     An output from the PWM duty changing circuit  418   p  is input to the drive device  419   p , which may be a known device such as a PWM driver, and an output from the drive device  419   p  is applied to the coil  510   p  (see FIG. 9) provided in the correcting means  51  to carry out shake corrections. The drive device  419   p  is turned on in synchronism with turning-on of the switch S 2  and is turned off once the exposure to the film is completed. Further, even after the exposure has been completed, the integrating circuit  415   p  continues the integration operation so long as the release button  43   a  is half-depressed (the switch S 1  is on). Then, when the switch S 2  is then turned on, the storage circuit  416   p  again stores a new integration output. 
     When the half depression of the release button  43   a  is stopped, the integrating circuit  415   p  stops integrating outputs from the DC cut filter  414   p  and is reset. The term “reset”, as used herein, refers to an operation of erasing all integrated information. 
     When the main switch is turned off, the shake detecting device  45   p  is turned off to complete one image stablization sequence. 
     Further, when the output signal from the integrating circuit  415   p  becomes larger than a predetermined value, then it is determined that the camera  43  has performed a panning operation, and the time constant of the DC cut filter  414   p  is changed. For example, the time constant is changed so that the characteristic that frequencies of 0.2 Hz and less are cut off is changed to one that frequencies of 1 Hz and less are cut off, and is then returned to its original value over a predetermined time period. Specifically, when the output signal exceeds a first threshold, the characteristic of the DC cut filter  414   p  is set so as to cut off frequencies of 0.5 Hz and less. When the output signal exceeds a second threshold, the characteristic of the DC cut filter  414   p  is set so as to cut off frequencies of 1 Hz and less. If the output signal exceeds a third threshold, the characteristic of the DC cut filter  414   p  is set so as to cut off frequencies of 5 Hz and less. 
     Further, when the output from the integrating circuit  415   p  becomes very large, the integrating circuit  415   p  is reset to prevent arithmetic overflow. 
     In FIG. 10, the DC cut filter  414   p  starts operating 0.2 seconds after the main switch has been turned on. However, the present invention is not limited to this, but the DC cut filter  414   p  may be set to start operating when the release button  43   a  is half-depressed. In this case, the integrating circuit  415   p  is started to operate when the change of the time constant of the DC cut filter is completed. 
     Further, as described above, the integrating circuit  415   p  also starts operating when the release button  43   a  is half-depressed (the switch S 1  is turned on), but may do so when the button  43   a  is fully depressed (the switch S 2  is turned on). In this case, the storage device  416   p  and the differential circuit  417   p  are not required. 
     In FIG. 10, the arithmetic device  47  is provided therein with the DC cut filter  48   p  and the low pass filter  49   p , but it goes without saying that these components may be provided in the shake detecting device  45   p.    
     FIGS. 11 to  13  show the details of the correcting means  51  in FIG.  9 . Specifically, FIG. 11 is a front view of the correcting means  51  in FIG. 9, FIG. 12A is a side view of the correcting means  51  as viewed from the direction of an arrow B in FIG. 11, FIG. 12B is a sectional view taken along line A—A in FIG. 11, and FIG. 13 is a perspective view of the correcting means  51  in FIG.  9 . 
     In FIG. 11, the correcting lens  52  is fixed to the support frame  53 . The correcting lens  52  is comprised of two lenses  52   a  and  52   b  (FIG. 12B) fixed to the support frame  53 , and a lens  52   c  fixed to the base plate  54 , to constitute a group of photographic optical systems. 
     A yoke  55  made of a ferromagnetic material is mounted on the support frame  53 . Mounted on the yoke  55  are the permanent magnets  56   p  and  56   y  made of neodymium or the like, which are attracted to a rear side surface of the yoke  55  as viewed in the figures, as indicated by hidden lines. Further, three pins  53   a  radially extend from the support frame  53  and are fitted in elongated holes  54   a  formed in side walls  54   b  axially projected from the base plate  54 . 
     As shown in FIGS. 12A and 13, the pairs of the elongated holes  54   a  and the pins  53   a  fitted therein serve to prevent back-lash in the direction of the photographic optical axis of the correcting lens  52  (indicated by the optical axis  57  in FIG.  12 A). However, since the elongated holes  54   a  are elongated in a direction orthogonal to the direction of the optical axis  57 , the pairs of the elongated holes  54   a  and the pins  53   a  restrict movement of the support frame  53  relative to the base plate  54  in the direction of the optical axis  57 , while allowing free movement of the support frame  5   a  in a plane orthogonal to the optical axis  57 , as shown by arrows  58   p ,  58   y , and  58   r . However, a tension spring  59  is engaged between each hook  53   b  on the support frame  53  and a corresponding hook  54   c  on the base plate  54 , as shown in FIG. 11, thereby elastically restricting the movement of the support frame  53  in each of the directions  58   p ,  58   y , and  58   r.    
     The coils  510   p  and  510   y  are mounted on the base plate  54  in opposed relation to the respective permanent magnets  56   p  and  56   y , as partially shown by hidden lines. The yoke  55 , the permanent magnet  56   p , and the coil  510   p  are arranged as shown in FIG. 12B, and the permanent magnet  56   y  and the coil  510   y  are similarly arranged. When current is caused to flow through the coil  510   p , the support frame  53  is driven in the direction of the arrow  58   p . When current is caused to flow through the coil  510   y , the support frame  53  is driven in the direction of the arrow  58   y.    
     The amount of driving of the support frame  53  is determined by the balance in each direction between the spring constant of the tension spring  59  and thrust resulting from the coaction between the coils  510   p  or  510   y  and the permanent magnets  56   p  or  56   y . That is, the amount of eccentricity of the correcting lens  53  can be controlled by the amount of current flowing through the coils  510   p  and  510   y.    
     Recent compact cameras have been significantly miniaturized, and correspondingly both the length and diameter of taking lens barrels in which taking lenses are fitted have been substantially reduced. 
     Under these circumstances, to install the above-described image stabilizing system into a camera, it is desirable to further reduce the size of the correcting means  51 , described above with reference to FIGS. 11 to  13 . 
     However, it can be anticipated that the reduction of the size of the correcting means  51  will necessitate arranging peripheral mechanisms such as the shutter, lens driving device, or lens barrier, which are magnetic members, at locations closer to the correcting means  51 . In particular, if the magnetic members are located closer to the permanent magnets provided in the correcting means  51 , the correcting lens, which is moved in unison with the permanent magnets, can show low responsiveness, i.e. lacks accuracy in its movement to degrade the image stabilization performance. The best way to prevent this is to contrive an improved layout of the camera, but the pursuit of the size reduction might bring about worse situations which cannot be avoided simply by improvement of the layout. 
     SUMMARY OF THE INVENTION 
     It is a first object of the present invention to provide an image-shake correcting device which is capable of performing image shake correction with high accuracy using a simple construction and without reducing the degree of freedom of layout and without the need to increase the size of the device, by arranging a second magnetic member that cancels the effects of the magnetic force of a first magnetic member located close to permanent magnets provided in correcting means for correcting image shakes. 
     It is a second object of the present invention to provide an image-shake correcting device, which employs elastic members that apply elasticity to a correcting lens in a direction in which the correcting lens is driven, and arranges the elastic member at substantially the same location as a support member that supports the correcting lens, and provides support shafts that support the support member with a function of adjusting the elastic force of the elastic members, thereby reducing the space occupied by the elastic members and hence permitting the device to be designed compact in size at low costs without lowering image-shake correcting accuracy, as well as enabling a device or apparatus in which the present device is mounted to be designed compact in size. 
     To attain the first object, a first aspect of the present invention provides an image-shake correcting device comprising a correcting optical unit having an optical axis, at least one magnet member provided in the correcting optical unit, at least one coil member arranged away from the magnet member in a direction of the optical axis, a first magnetic member arranged away from the magnet member in the direction of the optical axis, and a second magnetic member arranged away from the magnet member in the direction of the optical axis and at a side of the magnetic member remote from the first magnetic member, and wherein energization of the coil member causes the correcting optical unit to be driven in a direction intersecting with the optical axis to correct image shakes. 
     Preferably, an electromagnetic attractive force exerted between the magnet member and the first magnetic member is substantially equal to an electromagnetic attractive force exerted between the magnet member and the second magnetic member. 
     Preferably, the first magnetic member comprises a position detecting element having a metal terminal. 
     More preferably, the position detecting element is a photo interrupter. 
     Preferably, the second magnetic member comprises an iron-based metal plate. 
     In a preferred form of the first aspect, the image-shake correcting device comprises a support member that supports the correcting optical unit in a manner permitting same to move in the direction intersecting with the optical axis, and at least one support shaft provided on the support member and projected therefrom in the direction intersecting with the optical axis, and wherein the correcting optical unit has a fitting portion in which the support shaft is fitted, the correcting optical unit being driven in the direction intersecting with the optical axis in response to sliding of the support shaft in the fitting portion. 
     Preferably, the support shaft is adjustable in position relative to the support member in a direction of the optical axis. 
     More preferably, the image-shake correcting device comprises an urging member provided on the support shaft, for urging the correcting optical unit in the direction of the optical axis. 
     According to the first aspect of the present invention, image shakes can be accurately corrected using a simple construction and without reducing the degree of freedom of layout and without the need to increase the size of the device, by arranging the second magnetic member that cancels the effects of the magnetic force of the first magnetic member located close to the permanent magnet provided in the correcting means. 
     To attain the second object, a second aspect of the present invention provides an image-shake correcting device comprising a correcting optical unit having an optical axis and at least one fitting portion, a support member that supports the correcting optical unit in a manner permitting same to move in a direction intersecting with the optical axis, and a driving unit that drives the correcting optical unit relative to the support member in the direction intersecting with the optical axis, at least one support shaft provided on the support member, the support shaft being fitted in the fitting portion and projected from the support member in the direction intersecting with the optical axis, the support shaft being mounted on the support member in a manner being adjustable in position in a projecting direction thereof relative to the support member, at least one urging member provided on the support shaft, for urging the correcting optical unit in the projecting direction thereof, wherein an urging force of the urging member can be adjusted by adjusting a position of the support shaft, and wherein a driving force of the driving unit drives the correcting optical unit to cause sliding of the correcting optical unit on the support shaft to correct image shakes. 
     Preferably, the urging member comprises a compression coil spring fitted on the support shaft. 
     Preferably, the support shaft is threadedly coupled with the support member. 
     According to the second aspect of the present invention, the support member that supports the correcting lens and the elastic member (urging member) that applies elasticity to the correcting lens in a direction in which the correcting lens is driven are arranged at substantially the same location, and the support shafts that support the support member are each provided with the function of adjusting the elastic force of the elastic member. This construction serves to reduce the space occupied by the elastic member and and hence permit the device to be designed compact in size at low costs without lowering image-shake correcting accuracy, as well as enable a device or apparatus in which the present device is mounted to be designed compact in size. 
     The above and other objects, features, and advantages of the invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a lens barrel section of a camera provided with an image-shake correcting device according to an embodiment of the present invention; 
     FIG. 2 is a perspective view of the image-shake correcting device in FIG. 1; 
     FIG. 3 is a sectional view showing the construction of essential parts of a lens barrel in FIG. 2; 
     FIGS. 4A and 4B are views useful in explaining how a support frame for a correcting lens in FIG. 2 is supported, in which: 
     FIG. 4A is a fragmentary sectional view of the support frame; and 
     FIG. 4B is a fragmentary enlarged view of the support frame; 
     FIG. 5 is a perspective view of an image-shake correcting device according to a second embodiment of the present invention; 
     FIGS. 6A to  6 C are views showing the construction of essential parts of the image-shake correcting device in FIG. 5, in which: 
     FIG. 6A is a fragmentary sectional view showing a support frame and a compression coil spring; 
     FIG. 6B is a fragmentary sectional view showing the support frame; and 
     FIG. 6C is a fragmentary enlarged view showing the support frame; 
     FIG. 7 is a fragmentary sectional view showing the construction of essential parts of an image-shake correcting device according to a third embodiment of the present invention; 
     FIG. 8 is a perspective view showing the entire appearance of a camera having a conventional image stabilizing system mounted therein; 
     FIG. 9 is a perspective view showing the internal construction of the camera in FIG. 8; 
     FIG. 10 is a block diagram showing the details of arithmetic devices  47   p  and  47   y  in FIG. 9; 
     FIG. 11 is a front view of correcting means in FIG. 9; 
     FIGS. 12A and 12B are views showing the correcting means  51  in FIG. 11, in which: 
     FIG. 12A is a side view as viewed from the direction of an arrow B in FIG. 11; and 
     FIG. 12B is a sectional view taken along line A—A in FIG. 11; and 
     FIG. 13 is a perspective view of the correcting means  51  in FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described with reference to the drawings showing preferred embodiments thereof. 
     FIG. 1 is an exploded perspective view of a lens barrel section of a camera provided with an image-shake correcting device according to an embodiment of the present invention. FIG. 2 is a perspective view of the image-shake correcting device in FIG.  1 . FIG. 3 is a sectional view showing the construction of essential parts of the lens barrel in FIG.  2 . FIGS. 4A and 4B are views useful in explaining how a support frame for a correcting lens in FIG. 2 is supported, in which FIG. 4A is a fragmentary sectional view of the support frame, and FIG. 4B is a fragmentary enlarged view of the support frame. In FIG. 2, for the convenience of explanation, a base plate  54 , shown in FIG. 1, is omitted. 
     The construction of these figures is different from the prior art described before with reference to FIG. 13 in that a compression coil spring  59  (see FIG. 4A) is arranged coaxially with a support shaft  50  projecting from a support frame  53  in a direction intersecting with an optical axis  57 . The construction of these figures is also different from the prior art in that the support shafts  60  and the compression coil springs  59  are arranged in a fashion radially extending from the optical axis  57  at three circumferential locations; the support frame  53  and the support shafts  60  can slide relative to each other in a plane substantially orthogonal to the photographic optical axis; and a counter plate, described later, is provided as a second magnetic member. 
     As shown in FIG. 4A, one end of each compression coil spring  59  is fitted on a spring seat portion  53   b  of the support frame  53 , while the other end thereof is fitted on a spring seat portion  60   a  of the corresponding support shaft  60 . As the compression coil spring  59  is compressed, the inner diameter thereof is increased. The inner diameter of each compression coil spring  59  and the outer diameters of the seat portions  53   a  and  60   a  are set such that even when the compression coil spring  59  is compressed to the maximum extent after the support frame  53  slides on the support shaft  60  to increase the inner diameters of the ends of the compression coil spring  59  at the spring seat portions  53   b  and  60   a  of the support frame  53  and the support shaft  60 , the compression coil spring  59  remains fitted on the spring seat portions  53   b  and  60   a , without causing back-lash between the spring seat portion  53   b  and the compression coil spring  59  and between the spring seat portion  60   a  and the compression coil spring  59 . 
     This is because while the support frame  53  is being driven, if the relationship between the inner diameter of the compression coil spring  59  and the outer diameters of the spring seat portions  53   a  and  60   a  gets out of its proper relationship so that the compression coil spring  59  and the spring seat portions  53   a  and  60   a  are brought out of their fitted state into a shaky state, then the driving condition of the support frame  53  immediately changes to reduce image shake correcting accuracy. 
     The support shaft  60  is inserted into the coil spring  59  while being rotated through a threaded portion  54   c  formed in a side wall portion  54   b  of the base plate  54 . Further, the support shaft  60  has a sliding portion  60   d  inserted into an elongated hole  53   a  (see FIG. 4B) in the support frame  53 . The sliding portion  60   d  of the support shaft  60  and the elongated hole  53   a  in the support frame  53  are sized such that the former can be snugly fitted in the latter. The support shaft  60  and the support frame  53  can move relative to each other. 
     The support frame  53  is elastically supported on the base plate  54  by the three compression coil springs  59 . Thus, the position of the support frame  53  is restricted in the direction of the photographic optical axis (the direction shown by the optical axis  57  in FIG. 12A) with respect to the base plate  54  by the sliding portion  60   d  of the support shaft  60  and the elongated hole  53   a  in the support frame  53 . Further, the compression coil springs  59  cause the support frame  53  to be elastically supported on the base plate  54  in the directions of arrows  58   p ,  58   y , and  58   r  (see FIG.  11 ). Thus, the support frame  53  can move freely in a plane that is orthogonal to the photographic optical axis without becoming shaky in the direction of the photographic optical axis with respect to the base plate  54 . 
     Permanent magnets  56   ya  and  56   p  and a correcting lens  52  are mounted on the support frame  53  (see FIG.  2 ). When current flows through coils  510   p  and  510   y , the permanent magnets  56   ya  and  56   p  and the correcting lens  52  move in unison with the support frame  53  in a plane perpendicular to the photographic optical axis, to carry out image shake corrections. 
     In FIG. 1, a shutter plate  62  is attached to the base plate  54  by screws and serves to prevent the support frame  53  from becoming shaky in the direction of the photographic optical axis. Further, shutter blades  65  and  66  can slide on the shutter plate  62 . A photo interrupter (first magnetic member)  67  is provided as means for detecting the positions of the shutter blades  65  and  66 , and in the present embodiment, the photo interrupter  67  serves as a position detecting element and is comprised of a metal terminal made of a magnetic material which is insert-molded in a resin member. As the photo interrupters  67  of this type, those comprised of metal terminals made of magnetic materials which are currently available on the market are the mainstream for the production line rationalization. The photo interrupter  67  detects edges of a plurality of rectangular slits  65   a  formed in the shutter blade and outputs a signal for controlling the driving of the shutter. A drive pin  64 , which is made of a magnet, drives the two shutter blades  65  and  66 . The drive pin  64  is rotatively driven by a shutter coil, not shown, when the latter is electrically energized. 
     A damper plate  61 , which is comprised of a non-magnetic metal plate, suppresses high-frequency movement of the camera due to disturbances such as shakes caused by movement of a motor car in which the photographer is riding, in response to eddy current generated in the damper plate  61  by relative motion of the permanent magnets  56   p  and  56   y , thereby preventing the device from being damaged. The damper plate  61  also plays a role in positioning the coils  510   p  and  510   y  in the direction of the photographic optical axis. Correcting means (correcting optical unit) is constituted by the permanent magnets  56   p  and  56   y , the support frame  53 , the correcting lens  52 , and others, and serves to stabilize the gaps between the permanent magnet  56   p  and the coil  510   p  and between the permanent magnet  56   y  and the coil  510   y , thereby achieving accurate image shake corrections. 
     The shutter, which is comprised of the shutter plate  62 , shutter blades  65  and  66 , and photo interrupter  67 , and the correction means are juxtaposed in the direction of the photographic optical axis so that the photo interrupter  67  as the first magnetic member and the permanent magnet  56  ( 56   p  and  56   y ) forming part of the correcting means are located in proximity to each other in the direction of the photographic optical axis. Consequently, an electromagnetic attractive force F′ is generated between the permanent magnet  56  and the photo interrupter  67  to hinder movement of the correcting means, thereby degrading the image stablization performance. 
     To eliminate this inconvenience, the counter plate  65  as the second magnetic member, which is comprised of an iron-based metal plate, is arranged opposite the photo interrupter  67  via the permanent magnet  56 , that is, on a side of the coil  510  ( 510   p  or  510   y ) which is closer to the base plate  54 , so as to exert an electromagnetic attractive force F that has substantially the same intensity as the electromagnetic attractive force F′ generated between the photo interrupter  67  as the first magnetic member and the permanent magnet  56  (see FIG.  3 ). 
     With the counter plate  63 , the electromagnetic attractive force F′ exerted between the permanent magnet  56  and the photo interrupter  67  as the first magnetic member located in an area covered by the magnetic force of the permanent magnet  56  as a movable part can be offset by the electromagnetic attractive force F exerted between the counter plate  63  and the permanent electrode  56 . This enables the correcting means to be arranged without taking into consideration the presence of the first magnetic member. 
     In the present embodiment, it is assumed that the electromagnetic attractive force F exerted between the counter plate  63  and the permanent magnet  56  is adjusted by varying the thickness of the counter plate  63 . However, the electromagnetic attractive force may be adjusted by the following other methods, for example: 
     1) varying the distance between the counter plate  63  and the permanent magnet  56 , 
     2) varying the area of a part of the counter plate  63  that faces the permanent magnet  56 , or 
     3) changing the material for the counter plate  63 . 
     According to the above-described first embodiment, the image-shake correction device is comprised of the movable permanent magnet  56  forming part of the correcting means, the fixed coil  51  located away from the permanent magnet  56  in the direction of the photographic optical axis, the photo interrupter  67  as the first magnetic member located away from the permanent magnet  56  in the direction of the photographic optical axis, and the counter plate  63  as the second magnetic member located away from the permanent magnet  56  in the direction of the photographic optical axis and at a side of the permanent magnet  56  remote from the photo interrupter  67 , and the photo interrupter  67 , permanent magnet  56 , coil  510 , and counter plate  63  are arranged in this order so as to make the electromagnetic attractive force F′ exerted between the photo interrupter  67  and the permanent magnet  56  substantially equal to the electromagnetic attractive force F exerted between the counter plate  63  and the permanent magnet  56 . 
     As a result, the adverse effects of the photo interrupter  67  as the first magnetic member upon the correcting means that carries out image shake corrections can be offset, thereby increasing the degree of freedom of layout and providing a small-sized lens barrel having a simple construction and an accurate image shake correcting function. 
     Although in the above-described first embodiment, the present invention is applied to a lens barrel containing a shutter and correcting means, the present invention is not limited to this but is applicable to other optical apparatuses having magnetic members and correcting means as well as to small-sized cameras. 
     FIG. 5 is a perspective view of an image-shake correcting device according to a second embodiment of the present invention. FIGS. 6A to  6 C are views showing the construction of essential parts of the image-shake correcting device in FIG.  5 . 
     The second embodiment is different from the prior art described before with reference to FIG. 12 in that compression coil springs  71  are arranged coaxially with corresponding support shafts  72 , and a support frame  73  and each support shaft  72  slide relative to each other in a plane substantially orthogonal to the optical axis. Further, the present embodiment is distinguished from the first embodiment in that the elastic force of each compression coil spring  71  can be adjusted by moving the corresponding support shaft  72  in its axial direction. 
     One end of the compression coil spring  71  is fitted on a spring seat portion  73   b  of the support frame  73 , while the other end thereof is fitted on a spring seat portion  72   a  of the corresponding support shaft  72 . As the compression coil spring  71  is compressed, the inner diameter thereof is increased. However, the inner diameter of each compression coil spring  71  and the outer diameters of the seat portions  73   a  and  72   a  are set such that even when the compression coil spring  71  is compressed to the maximum extent after the support frame  73  slides on the support shaft  72  to increase the inner diameters of the ends of the compression coil spring  71  at the spring seat portions  73   b  and  72   a  of the support frame  73  and the support shaft  72 , the compression coil spring  71  remains fitted on the spring seat portions  73   b  and  72   a , without causing back-lash between the spring seat portion  73   b  and the compression coil spring  71  and between the spring seat portion  72   a  and the compression coil spring  71 . 
     This is because while the support frame  73  is being driven, if the relationship between the inner diameter of the compression coil spring  71  and the outer diameters of the spring seat portions  73   a  and  72   a  gets out of its proper relationship so that the compression coil spring  71  and the spring seat portions  73   a  and  72   a  are brought out of their fitted state into a shaky state, then the driving condition of the support frame  73  immediately changes to reduce image shake correcting accuracy. 
     The support shaft  72  is inserted into the compression coil spring  71  while being rotated through a threaded portion  74   c  formed in a side wall portion  74   b  of a base plate  74 . Further, the support shaft  72  has a sliding portion  72   d  (FIG. 6B) inserted into an elongated hole  73   a  (FIG. 6C) in the support frame  73 . The sliding portion  72   d  of the support shaft  72  and the elongated hole  73   a  in the support frame  73  are sized such that the former can be snugly fitted in the latter. The support shaft  72  and the support frame  73  can move relative to each other. The support frame  73  is elastically supported on the base plate  74  by the three compression coil springs  71  in a manner being movable in a spring force acting direction  71   a.    
     Thus, the position of the support frame  73  is restricted in the direction of the optical axis  57  (see FIG. 12A) with respect to the base plate  74  by the sliding portion  72   d  of the support shaft  72  and the elongated hole  73   a  in the support frame  73 . Further, the compression coil springs  71  cause the support frame  73  to be elastically supported on the base plate  74  in the directions of the arrows  58   p ,  58   y , and  58   r  (see FIG.  11 ). Thus, the support frame  73  can move freely in a plane that is orthogonal to the optical axis  57  without becoming shaky in the direction of the optical axis  57  with respect to the base plate  74 . 
     The support shaft  72  is provided with a threaded portion  72   b . When the threaded portion  72   b  is screwed into the threaded portion  74   c  formed in the side wall portion  74   b  of the base plate  74 , the position of the compression coil spring  71  changes to cause a corresponding change in the position of the support frame  73 , thereby allowing the position of the support frame  73  to be adjusted with respect to the base plate  74 , i.e. allowing the optical axis of the correcting lens to be adjusted with respect to the photographic optical axis. 
     If an attempt is made to reduce the size of the image-shake correcting device while maintaining a required moving stroke of the device, most of the moving stroke is used for a change in the position of the support frame  73  relative to the base plate  74  due to tolerances of the compression coil spring  71 , whereby a proper shake correction stroke cannot be secured during shake corrections. Therefore, the support shafts  72  are moved forward and backward in the axial direction to adjust the position of the support frame  73 . 
     According to the above-described second embodiment, the image-shake correcting device is comprised of the support frame  73  provided in the taking lens barrel to hold the correcting lens for shake corrections, the support shafts  72  provided in the base plate  74  to support the support frame  73  in a manner allowing the same to slide in a plane that is substantially orthogonal to the optical axis  57  of the taking lens barrel, the compression coil springs  71  that elastically supports the support frame  73  on the taking lens barrel, and a drive device that drives the support frame  73  in a sliding direction, and each of the compression coil springs  71  and the corresponding support shaft  72  are arranged substantially coaxially with each other, and the support shaft  72  is mounted on the base plate  74  in a manner being movable in the axial direction of the support shaft  72 . As a result, the image-shake correcting device can be designed compact in size without lowering the shake correcting accuracy. 
     FIG. 7 is a view showing the construction of essential parts of an image-shake correcting device according to a third embodiment of the present invention. The third embodiment is obtained by partially changing the construction of FIGS. 6A to  6 C, described above. Specifically, the present embodiment is different from the construction of FIGS. 6A to  6 C in that the support shafts  72  are press-fitted in the base plate  74  instead of being threaded fitted. The other parts of the construction of the present embodiment are the same as those of the above-described second embodiment. 
     With this construction, a plate fitting portion  72   c  of each support shaft  72  is press-fitted into a support shaft fitting portion  74   d  of the side wall portion  74   b  of the base plate  74 . By moving the support shafts  72  in an axial direction  31  thereof to change the positions of the compression coil springs  71 , the position of the support frame  73  is adjusted. Since the support shafts  72  are press-fitted in the base plate  74 , it is no longer necessary to fix the support shafts  72  and the base plate  74  by an adhesive or the like after the position adjustment. 
     By thus press-fitting the plate fitting portion  72   c  of each support shaft  72  into the support shaft fitting portion  74   d  of the side wall portion  74   b  of the base plate  74 , the shake-correcting device can be more efficiently assembled, and the costs of parts can be reduced. 
     According to the above-described third embodiment, the support frame  73  that supports the correcting lens and the compression coil springs  71  that apply elasticity to the correcting lens in the correcting lens driving direction are arranged at substantially the same location as shown in FIGS. 5 to  7  to thereby reduce the space occupied by members such as the compression coil springs  71 . This can provide a small-sized and inexpensive image-shake correcting device that can be driven with high accuracy. Further, the support shafts  72  that support the support frame  73  have the function of adjusting the elastic force of the compression coil springs  71 , which is imparted by the threaded portions  72   b  and  74   c , the plate fitting portion  72   c , and the support shaft fitting portion  74   d . This prevents the shake correcting accuracy from being degraded due to failure to ensure an appropriate shake correction stroke during shake corrections. Moreover, the components of a device or apparatus (in this example, a taking lens barrel) in which the present shake-correcting device is mounted can be arranged in the above-mentioned reduced space, thereby enabling the device or apparatus to be designed compact in size.