JP2008292902A - Image shake correction apparatus and imaging apparatus - Google Patents

Abstract

An object of the present invention is to provide an image blur correction apparatus capable of obtaining a high image blur correction performance in a wide band with a simple configuration.
A holding member that holds correction means for correcting image blur, elastic means that elastically supports a movable member with respect to a fixed member, and drive means that changes a relative position of the holding member with respect to the fixed member. And a damping means 66 disposed between the holding member and the fixing member, a shake detecting means 51 for detecting the shake, and a computing means 54 for processing a signal from the shake detecting means and outputting it to the driving means. The arithmetic means is provided with phase compensation means 62 having a maximum value of phase compensation at a frequency higher than the resonance frequency determined by the elastic means and the movable member.
[Selection] Figure 7

Description

  The present invention relates to an image blur correction apparatus and an imaging apparatus that perform image blur correction.

  In recent years, cameras have become more sophisticated, and as a part of the enhancement, there are many imaging devices equipped with an image blur correction device that corrects image blur due to a shake such as so-called camera shake. As described in Japanese Patent Application Laid-Open No. 2004-133620, an image shake correction apparatus detects image shake such as camera shake based on a gyro signal, and performs image shake correction by moving a part of the optical system in a plane orthogonal to the optical axis. Many configurations are used.

As a desirable characteristic of the mechanism constituting the image shake correction apparatus,
1) Friction is small and tracking of the target is good. 2) The frequency characteristic is easy for the designer to operate. Various mechanisms for realizing these have already been proposed.

  For example, the mechanism disclosed in Patent Document 2 is characterized by the provision of a lens driving device, and elastic means and viscosity means for restricting displacement of the movable part. By adopting the above-described configuration, a mechanism capable of so-called open control and improved frequency characteristics can be obtained.

The feature of the mechanism disclosed in Patent Document 3 is that it is possible to simplify the structure and suppress unnecessary resonance by attaching the viscoelastic body coaxially with the structure supporting the movable barrel. is there.
JP 60-143330 A JP-A-8-184870 JP 2002-139759 A

  According to Patent Document 2, viscous resistance can be obtained by a mechanical or electrical method. However, there is a problem that the structure tends to be complicated by the mechanical method and the friction increases, and according to the electric method, it is easy to be affected by the variation of the controlled object, and when trying to improve the image blur correction capability. There is a problem that the control system tends to become unstable.

  According to Patent Document 3, an appropriate viscous resistance can be obtained. However, if the control system is not set appropriately, there is a problem that excellent characteristics cannot be fully utilized due to the presence of a viscoelastic body.

(Object of invention)
An object of the present invention is to provide an image blur correction apparatus and an imaging apparatus that can obtain high image blur correction performance in a wide band with a simple configuration.

  In order to achieve the above object, the present invention provides a holding member that holds correction means for image blur correction, elastic means that elastically supports the movable member with respect to the fixed member, and the holding member. A driving means for changing a relative position with respect to the fixed member, an attenuating means arranged between the holding member and the fixed member, a shake detecting means for detecting shake, and a signal from the shake detecting means are processed. In the image blur correction apparatus having the calculating means for outputting to the driving means, the phase compensation means has a maximum value of phase compensation at a frequency higher than a resonance frequency determined by the elastic means and the movable member. An image blur correction apparatus including the above means is provided.

  Similarly, in order to achieve the above object, the present invention is an imaging apparatus including the shake correction apparatus of the present invention.

  According to the present invention, it is possible to provide an image blur correction apparatus or an imaging apparatus that can obtain high image blur correction performance in a wide band with a simple configuration.

  The best mode for carrying out the present invention is as shown in Example 1 and Example 2 below.

  An image pickup apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram illustrating an imaging apparatus. In FIG. 1, reference numeral 1 denotes an imaging apparatus, 2 denotes an imaging lens, and 3 denotes a shake correction unit that drives a correction lens 12 described later. 4 denotes an optical axis of the imaging lens 2, 5 denotes a lens barrel, 6 denotes an imaging device, 7 denotes a memory, 8 denotes a shake sensor for detecting shake such as camera shake, and 9 denotes a focus lens (not shown) included in the imaging lens 2. It is a focus lens driving circuit for driving. Reference numeral 10 denotes a power source, 11 a release button, 12 a correction lens, 13 a so-called quick return mirror, and 14 a finder optical system. Note that an image shake correction apparatus is configured by the shake correction unit 3, the shake sensor 8, and the like.

  The imaging device 1 forms a subject image in the vicinity of the imaging device 6 using the imaging lens 2 and a focus adjustment unit (not shown). Further, information on the subject is obtained from the image sensor 6 in synchronization with the operation of the release button 11 by the user and recorded in the memory 7.

  Next, image shake correction using the correction lens 12 driven by the shake correction unit 3 will be described. The shake correction unit 3 can appropriately drive the correction lens 12. When camera shake occurs during exposure or the like, the shake correction unit 3 operates the correction lens 12 with a drive signal for image shake correction generated based on a signal from the shake sensor 8. As a result, image blur on the image sensor 6 is reduced, and image degradation due to camera shake can be corrected.

  FIG. 2 is a diagram illustrating an electrical configuration of the imaging apparatus 1. The imaging device 1 has an imaging system, an image processing system, a recording / reproducing system, and a control system. The imaging system includes an imaging lens 2 and an imaging element 6, and the image processing system includes an A / D converter 20 and an image processing unit 21. The recording / playback system includes a recording processing unit 23 and a memory 24, and the control system includes a camera system control unit 25, an AF sensor 26, an AE sensor 27, an operation detection unit 29, a shake sensor 8, and a shake signal processing unit. A built-in lens system control unit 30 is included.

  The imaging system is an optical processing system that forms an image of light from a subject on the imaging surface of the imaging device 6 via the imaging lens 2, and an appropriate amount of light using a diaphragm (not shown) based on a signal from the AE sensor 27. The subject light is exposed to the image sensor 6. The image processing unit 21 included in the image processing system processes the image signal from the image sensor 6 via the A / D converter 20, and increases the resolution by a white balance circuit, a gamma correction circuit, and an interpolation operation. It has an interpolation calculation circuit and the like. A recording processing unit 23 included in the recording / reproducing system outputs an image signal to the memory 24 and generates and stores an image to be output to the display unit 22. Further, the recording processing unit 23 compresses images and moving images using a predetermined method.

  The control system controls the imaging system, the image processing system, and the recording / reproducing system in response to a detection signal from the operation detection unit 29 that detects the operation of the release button 11 and the like. The camera system control unit 25 included in this control system generates and outputs a timing signal at the time of shooting. The AF sensor 26 detects the focus state of the imaging apparatus 1. The AE sensor 27 detects the luminance of the subject. The shake sensor 8 detects shake such as hand shake. The lens system control unit 30 controls the focus lens drive circuit 9 and the shake correction unit 3 in accordance with the signal from the camera system control unit 25.

  The control system controls the imaging system, the image processing system, and the recording / reproducing system in response to external operations. For example, the pressing of the release button 11 is detected to control the driving of the image sensor 6, the operation of the image processing unit 21, the compression processing of the recording processing unit 23, and the like. Further, the display unit 22 controls the state of each segment of the information display device that displays information on an optical finder, a liquid crystal monitor, or the like.

  The camera system control unit 25 is connected to the AF sensor 26 and the AE sensor 27, and appropriately controls the lens, the diaphragm and the like via the lens system control circuit 30 based on signals from these. The lens system control circuit 30 is connected to the shake sensor 8 and drives the shake correction unit 3 based on a signal from the shake sensor 8 in a mode in which image shake correction is performed.

  Here, image blur correction will be described. By moving the correction lens 12 included in the imaging lens 2 within a plane orthogonal to the optical axis 4, the position of the image on the imaging element 6 can be changed. Alternatively, the correction lens 12 may be tilted with respect to the optical axis 4 to obtain a prism effect and change the position of the image on the image sensor 6. At this time, drive control of the correction lens 12 is appropriately performed according to the output of the shake sensor 8.

  Next, the shake correction unit 3 will be described with reference to FIGS.

  FIG. 3 is an exploded perspective view of the shake correction unit 3. In FIG. 3, 31 is a base plate that is a fixed member, 36 is a movable barrel that is a movable member that holds the correction lens 12, and 32 a, 32 b, and 32 c are sandwiched between the base plate 31 and the movable barrel 36. Sphere. 33a and 33b are coils, 34a and 34b are magnets, 35a, 35b and 35c are elastic bodies, 37 is a magnet suction plate, 38a and 38b are suction plate fixing spirals, 39 is a movable lens barrel holding plate, and 40 is an FPC (flexible print). Substrate), 41a, 41b are FPC fixing spirals.

  As can be seen from FIG. 3, the shake correction unit 3 according to the first embodiment can be deployed on one side with respect to the base plate 31 and can be easily assembled. Therefore, productivity can be improved and cost reduction can be expected.

  FIG. 4 is a diagram showing details of the shake correction unit 3. Specifically, FIG. 4A is a front view seen from the optical axis direction, FIG. 4B is a cross-sectional view taken along the line BB of FIG. 4A, and FIG. It is sectional drawing in CC cross section.

  As shown in FIG. 4A, the movable lens barrel 36 is elastically supported by the plurality of elastic bodies 35 a, 35 b, and 35 c with respect to the base plate 31. In the first embodiment, three elastic bodies 35a, 35b, and 35c are arranged radially from the center of the optical axis at intervals of 120 degrees. By adopting such a symmetrical arrangement, it is possible to suppress excitation of unnecessary resonance due to generation of moment. Further, as shown in FIGS. 4B and 4C, the elastic bodies 35a, 35b, and 35c are attached so as to be appropriately inclined in the optical axis direction, and are provided between the base plate 31 and the movable lens barrel 36. The spheres 32a to 32c are held.

  The relative movement of the base plate 31 and the movable lens barrel 36 will be described with reference to FIGS. 3 and 4B. The base plate 31 and the movable lens barrel 36 hold the balls 32a to 32c, and perform relative motion via the balls 32a to 32c. For this reason, relative motion can be performed only under the influence of very small friction called rolling friction. Since the friction is small, it can respond appropriately even to a very small input. In addition, by manufacturing the guide surfaces by the balls 32a to 32c with appropriate accuracy, even when the base plate 31 and the movable lens barrel 36 move relative to each other, the movable lens barrel 36 is not required to tilt or move in the optical axis direction. Will not occur.

  The actuator provided in the shake correction unit 3 will be described with reference to FIGS. As shown in FIG. 4C, coils 33a and 33b are fixed to the base plate 31, and magnets 34a and 34b are fixed to the movable lens barrel 36, so-called moving magnet type actuators, that is, driving means. Is configured.

  5A and 5B are schematic views of the actuator. FIG. 5A is a view of only the magnet 34a and the coil 33a viewed from the optical axis direction, and FIG. 5B is a cross-sectional view when the magnet 34a is cut near the center. Show. The relative positional relationship between the magnet 34b and the coil 34b is the same.

  In FIG. 5, 43 is a magnetization boundary. Further, 42a, 42b, and 42c shown in FIG. 5B schematically represent typical magnetic lines of force near the magnets 34a and 34b and the coils 33a and 33b. As shown in FIG. 5A, the magnet 34a is magnetized in two regions 34a1 and 34a2 across the magnetization boundary 43. The magnetization boundary 43 is a direction orthogonal to the direction of the force generated by the actuator. There is a magnetization boundary in the vertical direction of FIG. 5A, and the magnet 34a and the movable lens barrel 36 are driven in the left-right direction. The coil 33a has an oval shape when viewed from the optical axis direction, and the two longitudinal portions 33a1 and 33a2 are arranged so as to face the two regions 34a1 and 34a2 of the magnet.

  On the surface of the magnet 34a opposite to the coil 33a, a magnet attracting plate 37 that also serves as a yoke is disposed as shown in FIG. The magnet attracting plate 37 is preferably a soft magnetic material, and allows a large amount of magnetic flux to pass therethrough, thereby reducing the permeance (easy to leak) of the magnetic circuit. As a result, lines of magnetic force are generated relatively linearly from the magnet 34a toward the coil 33a. In the first embodiment, the magnet attracting plate 37 is fixed to the movable lens barrel 36. Therefore, when the thickness is increased, the weight of the movable portion is also increased. Therefore, it is preferable to determine the magnet attracting plate 37 to be in the vicinity of the saturated magnetic flux in consideration of the outer shape of the magnet attracting plate 37, the saturation magnetic flux density, the shape of the magnet, the surface magnetic flux density, and the like. When the coil 33a is energized in this state, a current flows in the opposite direction to 33a1 and 33a2 in the direction perpendicular to the paper surface of FIG. Driving force is generated by the Fleming's left hand rule. As described with reference to FIG. 4A, since the movable lens barrel 36 is elastically supported, the base plate 31 and the movable lens barrel 36 are moved to a position where the resultant force of the elastic bodies 35a, 35b, 35c and the driving force are balanced. Relative motion occurs.

  Next, the attachment of the damping means for obtaining an appropriate viscous resistance will be described with reference to FIG. 6A is a front view of the shake correction unit 3 viewed from the optical axis direction, FIG. 6B is a cross-sectional view taken along the line DD in FIG. 6A, and FIG. 6C is FIG. It is a detailed view of the damping means mounting portion surrounded by a circle.

  In FIG. 6, 44a and 44b are attenuation means attaching parts, 45 is attenuation means, and 46 is an ultraviolet irradiation direction. As shown in FIG. 6B, the suction plate fixing spirals 38 a and 38 b are spirally fastened to the movable lens barrel 36, and then toward the hole provided in the base plate 31 at least in the direction of the optical axis with the base plate 31. It extends to overlap. It is desirable that a plurality of attenuation means mounting portions 44a and 44b are provided symmetrically with respect to the optical axis. In the first embodiment, as shown in FIG. 6B, two are provided at positions symmetrical with respect to the optical axis 4. By providing symmetrically with respect to the optical axis 4, no moment is generated in the movable lens barrel 36 by the force received from the attenuation means 45 when the base plate 31 and the movable lens barrel 36 perform relative motion.

  FIG. 6C is a detailed view of the attenuation means attachment portion 44a. With respect to the cylindrical hole 31b provided in the base plate 31, the suction plate fixing spiral 38a fixed to the movable barrel 36 is arranged so as to be substantially concentric, and the damping means 45 is formed in a donut shape in the gap. Is provided. Although various viscoelastic bodies can be used for the attenuating means 45, in the first embodiment, an ultraviolet curable silicone gel excellent in assembling property and environmental resistance is used. Since the hole 31b provided in the base plate 31 opens downward, the gel before curing is applied from the direction of the arrow 46, and then cured by irradiating with ultraviolet rays.

  As shown in FIG. 6, let a be the allowable interval of mechanical overrun constituted by the protrusion 31 a provided on the base plate 31 and the protrusion 36 a provided on the movable lens barrel 36. Further, the distance between the suction plate fixing spiral 38a and the inner wall of the hole 31b where the damping means 45 shown in FIG. It is preferable that the damping means 45 is used in a range in which no major deformation occurs and permanent deformation does not occur (= a range in which the elastic coefficient changes linearly). Therefore, it is desirable to provide so as to satisfy “a <b”. In order not to leave permanent deformation, it is more preferable that the range is “a <0.5b”.

  FIG. 7 shows a block diagram of a control system of the shake correction unit 3. 51 is a gyro sensor corresponding to the shake sensor 8, 52 is a low-pass filter (hereinafter LPF), 53 is an analog / digital converter (hereinafter A / D converter), and 54 is in the lens system control unit 30 of FIG. It is an equivalent microcomputer. 55 denotes an integrator, 56 denotes a high-pass filter (hereinafter, HPF), and 57 denotes a shake signal processing unit. 58 is a determination condition output unit, which sets an appropriate determination condition so that the shake correction unit 3 does not move against the user's intention when the user performs an intentional panning operation or is fixed to a tripod. Output. 59 is a target position processing unit, 60 is a conversion coefficient output unit, 61 is an information output unit that outputs zoom information, distance information, and release operation information. Reference numeral 62 denotes a filter, 63 denotes a follow-up control unit, 64 denotes an information output unit such as an offset / driving sensitivity, and 65 denotes a digital / analog converter (hereinafter referred to as D / A converter). Reference numeral 66 denotes a driver unit corresponding to the moving magnet type actuator (driving means) provided in the shake correction unit 3. The control system of the correction lens 12 is an open control system shown in FIG.

  In many cases, the image pickup apparatus 1 including an image shake correction apparatus that performs image shake correction uses a gyro sensor 51 as the shake sensor 8 due to restrictions on the size and accuracy of the apparatus. In the example shown in FIG. 7, the signal from the gyro sensor 51 is taken into the microcomputer 54 via the A / D converter 53 after high frequency noise is removed via the appropriate LPF 52.

  In the microcomputer 54, the angular velocity signal is converted into an angle signal by integration by the integrator 55. An HPF 56 having an appropriate time constant is used to reduce the influence of drift of the gyro sensor 51 and the like. In the shake signal processing unit 57, a signal to be controlled is determined from an obtained angle signal under an appropriate determination condition so that the shake correction unit 3 from the determination condition output unit 58 does not move against the user's intention. Extract.

  The target position processing unit 59 outputs the angle signal based on the outputs of the information output unit 61 and the conversion coefficient output unit 60, that is, based on the zoom information, the focus information 61, etc., and further based on the predetermined conversion coefficient. This is converted into a displacement signal of the correction lens 12 or the like. As the filter 62, a filter having frequency characteristics that can appropriately suppress camera shake as the entire system in consideration of the frequency characteristics of the shake correction unit 3, the gyro sensor 51, and the like is used. Details of the filter 62 will be described later. The follow-up control unit 63 converts the output of the filter 62 into a control signal for the shake correction unit 3 based on information from the information output unit 64 such as drive sensitivity and offset of the shake correction unit 3.

  The signals that have been processed in the microcomputer 54 are output to the driver unit 66 via the D / A converter 65, and the shake correction unit 3 is driven. That is, the movable lens barrel 36 that holds the correction lens 12 changes its position relative to the base plate 31 that is a fixed member (moves in a plane orthogonal to the optical axis), and image blur due to camera shake or the like is corrected. Is called.

  By appropriately setting the coefficients of the above-described units, the shake of the subject image on the image sensor 6 can be reduced even when hand shake occurs.

  FIG. 8 shows a block diagram in which only the main part is modeled by simplifying FIG. The input in FIG. 8 is the target lens position output through the target position processing unit 59 in FIG. 7, and the output is the actual position of the correction lens 12 output through the filter 62 and the tracking control unit 63. .

  In order to simplify the following description, the frequency characteristic (transfer function) of the filter 62 is F (s), the frequency characteristic (transfer function) of the shake correction unit 3 is G (s), the driver gain, and the gain for adjusting the drive sensitivity. Is K. Note that s in F (s) and G (s) is a Laplace operator.

  Here, a vibration suppression rate is defined as an index indicating the performance of camera shake. The suppression rate is defined as the norm of the value obtained by normalizing the difference between input and output. Assuming that the input is X (s), it is apparent from FIG.

定義から明らかなように、上記の抑振率は小さいほど、高い像振れ抑制性能を示す。

As is clear from the definition, the smaller the above-described suppression rate, the higher the image blur suppression performance.

  Next, the frequency characteristic F (s) of the filter 62 and the frequency characteristic G (s) of the shake correction unit 3 which are the main parts of the first embodiment will be described with reference to FIGS.

  FIGS. 9A and 9B are frequency characteristics G (s) of the shake correction unit 3 described with reference to FIGS. Although the shake correction unit 3, specifically, the correction lens 12 can be driven in two axial directions, the characteristics shown in FIG. 9 are expressed in a Bode diagram with and without the attenuation means 45 in one axial direction. ing. Since the main part of the shake correction unit 3 has a line-symmetric structure, the characteristics of the other axis not shown in FIG. 9 have similar characteristics. In the following, in order to simplify the description, the description is limited to only one axis direction. In FIG. 9, the Bode diagram gain is normalized and expressed so that the gain at a sufficiently low frequency is 1.

  In the example of FIG. 9, there is a main resonance at a position of slightly above 30 Hz, and a sub-resonance near 45 Hz. The sub-resonance is generated by so-called rolling that the movable lens barrel 36 shown in FIGS. 3 to 6 rotates around the optical axis. In the first embodiment, the influence of the main resonance and the sub-resonance is reduced by appropriately interposing the attenuation means 45. Thereby, unnecessary resonance is not excited by the operation of the shutter of the imaging apparatus 1 or the like.

  FIGS. 10A and 10B show frequency characteristics of the filter 62 according to the first embodiment and the conventional filter. As shown in FIG. 9, since the frequency characteristic of the shake correction unit 3 is a so-called second-order lag system, the phase is delayed as the resonance frequency is approached, and the phase is finally inverted by 180 degrees. Conventionally, a phase advance filter has been used in order to reduce this influence and reduce the suppression rate shown in Equation 1 above.

  The conventional filter shown in FIG. 10 is an example. In the phase advance filter, the gain in the high band is raised compared to the low band. However, in the conventional filter, a filter that greatly increases the gain in order to eliminate the influence of unnecessary mechanical resonance such as sub-resonance in the high band is not appropriate. In order to obtain the improvement effect of the suppression rate by the filter under such constraints, a phase advance filter has been used in which the peak of phase compensation is near the resonance frequency or slightly lower than the resonance frequency. .

  On the other hand, in the first embodiment, since the attenuation means 45 is provided, the influence of unnecessary mechanical resonance such as sub-resonance can be ignored. Therefore, a more aggressive filter can be used than before. Specifically, a first-order phase lead filter having a phase compensation peak (maximum value) at a frequency higher than the resonance frequency as shown in FIG. 10 is a suitable example. The reason why the primary phase advance filter is used is that the calculation is simple and appropriate control can be performed even when a cheaper microcomputer is used. By effectively utilizing the “side” portion of the phase compensation amount (Phase in FIG. 10A), it is possible to perform appropriate phase compensation over a wide range.

  FIG. 11 shows the suppression rate when the filter 62 according to the first embodiment is used, when the conventional filter is used, and when there is no filter. It can be seen that by using the filter 62 according to the first embodiment, the suppression rate can be improved in a wide frequency range.

  According to the first embodiment, the filter 62 that is the phase compensation means having the maximum value of phase compensation at a frequency higher than the resonance frequency determined by the elastic bodies 35a to 35c and the movable lens barrel 36 is obtained by the computing means. A configuration is provided in a certain microcomputer 54. Specifically, a filter 62 that performs first-order phase lead compensation is provided.

  By providing the filter 62 as described above in the microcomputer 54, it is possible to obtain high image blur correction performance in a wide band with a simple filter configuration.

  With reference to FIGS. 12 to 22, an image pickup apparatus including an image shake correction apparatus according to the second embodiment of the present invention will be described. The configuration of the imaging apparatus is the same as that shown in FIGS. 1 and 2 described in the first embodiment, and a description thereof will be omitted.

  A shake correction unit 300 for image shake correction, which is a main part of the second embodiment, will be described with reference to FIGS. FIG. 12 is an exploded perspective view of the shake correction unit 300 according to the second embodiment. Components having the same functions as those of the shake correction unit 3 according to the first embodiment are denoted by the same reference numerals.

  In FIG. 12, reference numeral 101 denotes a magnet suction plate that also serves as a yoke. Unlike the magnet suction plate of the first embodiment, an appropriate hole is provided. As is clear from FIG. 12, the mechanism of the second embodiment can be deployed on one side with respect to the base plate 31 and can be easily assembled. Therefore, productivity can be improved and cost reduction can be expected.

  FIG. 13 is a plan view of the shake correction unit 300. Specifically, FIG. 13A is a front view seen from the optical axis direction, FIG. 13B is a cross-sectional view taken along line BB in FIG. 13A, and FIG. 13C is a cross-sectional view taken along line CC in FIG. A sectional view, FIG. 13 (d) is a detailed view of a circled portion of FIG. 13 (c).

  As shown in FIG. 13, the movable part is supported by the same method as in the first embodiment. That is, the movable lens barrel 36 is elastically supported by the plurality of elastic bodies 35 a to 35 c with respect to the base plate 31. In the second embodiment, three elastic bodies 35a to 35c are arranged radially from the optical axis 4 at intervals of 120 degrees. By adopting such a symmetrical arrangement, it is possible to suppress excitation of unnecessary resonance due to generation of moment. In addition, the elastic bodies 35a to 35c are attached so as to be appropriately inclined in the optical axis direction, and hold the balls 32a, 32b, 32c (see also FIG. 12) provided between the base plate 31 and the movable lens barrel 36. Yes.

  The configuration of the guide surface of the movable part of the shake correction unit 300 is the same as that shown in FIG.

  The actuator, that is, the driving unit of the shake correction unit 300 will be described with reference to FIGS. 13B, 14, and 15. The actuator has substantially the same structure as that shown in FIG. 4C of the first embodiment, and the base plate 31 and the movable lens barrel 36 are energized by energizing the coils 33a and 33b constituting a part of the actuator. Relative motion occurs between them. The difference is that the sensor 102 is provided on the opposite side of the coils 33a and 33b with respect to the magnets 34a and 34b. Since the second embodiment is a so-called moving magnet type actuator, a Hall element is used as the sensor 102. The sensor 102 is fixed to the base plate 31 via the FPC 40, and detects the position of the movable lens barrel 36 by a change in magnetic flux density. Further, by arranging the Hall element as the sensor 102 as described above, the driving magnets 34a and 34b are also used as position detecting magnets.

  14A and 14B are schematic views of an actuator. FIG. 14A is a view of a magnet, a coil, and a sensor viewed from the optical axis direction, and FIG. 14B is a cross-sectional view when the magnet is cut near the center. Yes.

  In FIG. 14, reference numeral 110 denotes a magnetic sensitive part of the sensor 102. In the magnetic circuit shown in FIG. 14, the magnetic fluxes 42a, 42b, and 42c flow as shown by the arrows. In the state of FIG. 14B, since the magnetic sensing part 110 is located immediately above the magnetization boundary 43, the magnetic field at this point is substantially equal to zero. When relative movement occurs between the base plate 31 and the movable lens barrel 36, the magnetizing boundary 43 moves together with the movable lens barrel 36 as viewed from the sensor 102 fixed to the base plate 31. Indicates a non-zero value.

  FIG. 15 shows a result obtained experimentally. In FIG. 15, the amount of movement 0 means a state in which the magnetic sensing part 110 is located immediately above the magnetization boundary 43 shown in FIG. As can be seen from FIG. 15, in a certain range, the movement amount and the magnetic field strength have a linear relationship, and in this range, the position can be detected by the linear relationship.

  Next, attachment of the damping means 104 will be described with reference to FIGS. 13 (c) and 13 (d). 13C and 13D, reference numerals 103a and 103b denote attenuating means mounting portions, 104 denotes an attenuating means, 105a denotes an ultraviolet transmitting plate, and 106 denotes an ultraviolet irradiation direction. As shown in FIG. 13C, two attenuation means attaching portions 103a and 103b are provided symmetrically with respect to the optical axis 4 as in the first embodiment. After the suction plate fixing spirals 38a and 38b are spirally fastened to the movable lens barrel 36, the suction plate fixing spirals 38a and 38b overlap at least the base plate 31 in the optical axis direction and do not penetrate through the holes 31b provided in the base plate 31. It is extended. After the ultraviolet transmissive plate 105a is attached to the base plate 31, the attenuating means 104 is injected, and then the movable lens barrel 36 is incorporated. Finally, the attenuation means 104 can be cured by irradiating ultraviolet rays from the direction 106. The viscoelastic body used as the attenuating means 104 is assumed to be that shown in the first embodiment.

  FIG. 16 shows a block diagram of a control system of the shake correction unit 300. The parts having the same functions as those in FIG. 16, 300 is a shake correction unit, 67 is a position detection sensor (corresponding to the sensor 102 in FIG. 14) for detecting the position of the correction lens 12, and 68 is an A / D converter. The control system of the correction lens 12 is a feedback control system as shown in FIG.

  Also in the second embodiment shown in FIG. 16, the signal processing up to the output of the target position processing unit 59 is performed in the same manner as in the first embodiment. However, in the second embodiment, a so-called feedback system is configured, and the displacement of the shake correction unit 300 is monitored by an appropriate position detection sensor 67 such as a Hall element. Then, this position detection signal is taken into the microcomputer 54 via the A / D converter 68, subjected to appropriate processing by the filter 62, and fed back to the follow-up control unit 63. The sampling frequency of the feedback system is appropriately set in consideration of the control band. In general, a control system for correcting camera shake requires a sampling frequency of about several kHz because the frequency to be controlled is up to about 100 Hz.

  FIG. 17 shows a block diagram in which only the main part is modeled by simplifying FIG. The input in FIG. 17 is the target lens position output through the target position processing unit 59 in FIG. 16, and the output is the actual correction lens output through the filter 62, the tracking control unit 63, and the shake correction unit 300. 12 positions. In order to simplify the following explanation, the frequency characteristic (transfer function) of the filter is F (s), the frequency characteristic (transfer function) of the shake correction unit 300 is G (s), and the driver gain and the gain for adjusting the drive sensitivity are set. K, and the gain of the position detection sensor 67 is K ′.

  Here, when considering the transfer function of the closed loop system of FIG.

実施例１で定義した抑振率は、以下の数３となる。

The vibration suppression rate defined in the first embodiment is expressed by the following formula 3.

数３の抑振率を小さくするためには、Ｇ’（Ｓ）を広い帯域で１に近づければよく、これはフィードバック制御では交叉周波数を高く設定できれば実現可能となる。

In order to reduce the suppression rate of Equation 3, G ′ (S) may be brought close to 1 in a wide band, and this can be realized in feedback control if the crossover frequency can be set high.

  The frequency characteristic F (s) of the filter 62 and the frequency characteristic G (s) of the shake correction unit 300, which are the main parts of the second embodiment, will be described with reference to FIGS.

  18A and 18B are frequency characteristics G (s) of the shake correction unit 300 according to the second embodiment described with reference to FIGS. Although the shake correction unit 300 can be driven in two axial directions, the characteristics shown in FIG. 18 represent the case where the attenuation means 45 is not provided in one axial direction in a Bode diagram. In the mechanism shown in the second embodiment, since the main part of the shake correction unit 300 has a line-symmetric structure, the characteristics of the other axis not shown in FIG. 18 have similar characteristics. In the following, in order to simplify the description, the description is limited to only one axis direction. In FIG. 18, the Bode diagram gain is normalized and expressed so that the gain at a sufficiently low frequency is 1.

  In the example of FIG. 18, there is a main resonance at a position of slightly above 30 Hz, and a sub-resonance near 300 Hz. The sub-resonance is generated by the occurrence of pitching that is inclined with respect to a plane perpendicular to the rolling optical axis in which the movable lens barrel 38 of the mechanism shown in FIGS. 12 to 15 rotates around the optical axis.

  FIGS. 19A and 19B show frequency characteristics of the filter 62 according to the second embodiment and the conventional filter. As shown in FIG. 18, since the frequency characteristic of the shake correction unit 300 is a so-called second-order lag system, the phase is delayed as the resonance frequency is approached, and the phase is finally inverted by 180 degrees. Conventionally, a phase advance filter has been used in order to reduce this influence and reduce the suppression rate shown in Equation (3). The conventional filter shown in FIG. 19 is an example. In the phase advance filter, the gain in the high band is raised compared to the low band.

  The feedback servo design will be described with reference to FIGS. 18 (a) and 18 (b). In a shake correction unit that does not include attenuation means as in the prior art, it is necessary to design the servo in consideration of the phase margin and gain margin. For example, in the conventional filter shown in FIG. 18, when a gain increase of about 5 dB is performed with respect to the state of FIG. 18, the crossover frequency is around 65 Hz, the phase margin is about 30 deg, and the gain margin around 300 Hz is kept about 8 dB. As a result, the servo system is kept stable.

  On the other hand, in the filter 62 according to the second embodiment, when a gain increase of about 5 dB is performed, the crossover frequency is about 80 Hz and the phase margin is about 45 degrees, but the gain margin near 300 Hz is about 2 dB. Servo system is not stable. Therefore, the closed loop gain cannot be sufficiently increased, and as a result, the vibration suppression rate cannot be increased. FIG. 20 shows an example of the damping rate when the servo is designed within a range where the servo system does not become unstable. With only the filter according to the second embodiment, the control band cannot be improved significantly over the conventional filter. As described above, in the shake correction unit in which the appropriate attenuation means 45 is not interposed, the filter 62 according to the second embodiment alone is not necessarily appropriate.

  On the other hand, in the second embodiment, since the attenuation means 45 is provided, the influence of unnecessary mechanical resonance such as sub-resonance can be reduced, so that a more aggressive filter than before can be used. Specifically, a first-order phase lead filter having a phase compensation peak at a frequency higher than the resonance frequency as shown in FIG. 19 is a suitable example. The reason why the first-order phase advance filter is used is that appropriate control can be performed even when a simpler and cheaper microcomputer is used. By effectively utilizing the “side” portion of the phase compensation amount (Phase in FIG. 19A), it is possible to perform appropriate phase compensation over a wide range.

  FIG. 21 shows the frequency characteristic G (s) of the shake correction unit when the attenuation means 45 is provided.

  Although the mechanism is the same as that shown in FIG. 18 except that the attenuation means 45 is interposed, unnecessary resonance peaks in the vicinity of 300 Hz are sufficiently suppressed. With the frequency characteristics shown in FIG. 21, the crossover frequency can be increased as compared with the conventional filter. Specifically, in the conventional filter, the limit of stability is that the crossover frequency is about 70 Hz from the phase margin, but the filter 62 according to the second embodiment has a phase margin and gain even if the crossover frequency is about 120 Hz. There is no problem with both margins. As a result, the filter 62 according to the second embodiment can obtain a high suppression rate in a wider band. FIG. 22 shows an example of the vibration suppression rate when the servo is designed within a range where the servo system does not become unstable.

  According to the second embodiment, the filter 62, which is a phase compensation means having a maximum value of phase compensation at a frequency higher than the resonance frequency determined by the elastic bodies 35a to 35c and the movable lens barrel 36, is calculated by the computing means. A configuration is provided in a certain microcomputer 54. Specifically, a filter 62 that performs first-order phase lead compensation is provided in the feedback control system.

  By using the filter 62 as described above, it is possible to obtain high camera shake correction performance in a wide band with a simple filter configuration.

(Correspondence between the present invention and the embodiment)
The correction lens 12 is a correction means for correcting image blur of the present invention, the movable lens barrel 36 is fixed to the holding member of the present invention, and the base plate 31 is fixed to support the holding member so as to be movable in a plane perpendicular to the optical axis. It corresponds to each member. Further, the elastic bodies 35a to 35c are elastic means for elastically supporting the movable member with respect to the fixed member, and the coils 33a and 33b and the magnets 34a and 34b change the relative position of the holding member with respect to the fixed member. It corresponds to the driving means. Further, the damping means 45 and 104 are the damping means disposed between the holding member and the fixing member, the shake sensor 8 and the gyro sensor 51 are the shake detection means of the present invention, and the CPU 54 receives the signal from the shake detection means. It corresponds to the calculation means which processes and outputs to a drive means, respectively. Further, the filter 62 corresponds to a phase compensation means having a maximum value of phase compensation at a frequency higher than the resonance frequency determined by the elastic member and the movable member.

  The present invention is not limited to an image shake correction apparatus using the correction lens 12 but can be applied to an apparatus that performs image shake correction by moving an imaging element in a plane perpendicular to the optical axis.

1 is a configuration diagram illustrating an imaging apparatus according to Embodiment 1 of the present invention. 1 is a block diagram illustrating an electrical configuration of an imaging apparatus according to Embodiment 1 of the present invention. It is a disassembled perspective view of the shake correction unit concerning Example 1 of the present invention. 2A and 2B are a plan view and a cross-sectional view of a shake correction unit according to Embodiment 1 of the present invention. It is explanatory drawing of the drive means of the shake correction unit concerning Example 1 of this invention. It is attachment explanatory drawing of the attenuation | damping means of the shake correction unit concerning Example 1 of this invention. FIG. 3 is a block diagram illustrating a control system for image blur correction according to the first exemplary embodiment of the present invention. It is a block diagram which simplifies and shows the principal part of FIG. It is a figure which shows the frequency characteristic of the shake correction unit concerning Example 1 of this invention. It is a figure which shows the frequency characteristic of the filter concerning Example 1 of this invention. It is a figure explaining the vibration suppression rate of the shake correction unit concerning Example 1 of the present invention. It is a disassembled perspective view of the shake correction unit concerning Example 2 of the present invention. It is the top view and sectional drawing of a shake correction unit concerning Example 2 of the present invention. It is explanatory drawing of the drive means of the shake correction unit concerning Example 2 of this invention. It is a distribution map of the magnetic field around the sensor magnetic sensitive part concerning Example 2 of this invention. It is a block diagram which shows the control system of the image blur correction concerning Example 2 of this invention. FIG. 17 is a block diagram schematically showing a main part of FIG. 16. It is a figure which shows the frequency characteristic of the shake correction unit when there is no attenuation means concerning Example 2 of this invention. It is a figure which shows the frequency characteristic of the filter concerning Example 2 of this invention. It is a figure which shows the suppression rate of a shake correction unit when there is no attenuation means concerning Example 2 of this invention. It is a figure which shows the frequency characteristic of the shake correction unit in case there exists an attenuation means concerning Example 2 of this invention. It is a figure which shows the suppression rate of a shake correction unit in case there exists an attenuation means concerning Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Imaging lens 3 Shake correction unit 6 Imaging element 8 Shake sensor 12 Correction lens 25 Camera system control part 30 Lens system control part 31 Base board 32a, 32b, 32c Sphere 33a, 33b Coil 34a, 34b Magnet 35a, 35b, 35c Elastic body 36 Movable lens barrel 45 Attenuating means 51 Gyro sensor 54 Microcomputer 57 Vibration signal processing section 59 Target position processing section 67 Position detection sensor 102 Sensor 104 Attenuating section 110 Magnetic sensing section 300 Shaking correction unit

Claims (6)

A holding member that holds correction means for image blur correction;
A fixing member that movably supports the holding member in a plane perpendicular to the optical axis;
Elastic means for elastically supporting the movable member with respect to the fixed member;
Driving means for changing a relative position of the holding member with respect to the fixing member;
Damping means disposed between the holding member and the fixing member;
Shake detection means for detecting shake;
In an image blur correction apparatus having a calculation unit that processes a signal from the shake detection unit and outputs the processed signal to the drive unit,
An image blur correction apparatus characterized in that the arithmetic means comprises phase compensation means having a maximum value of phase compensation at a frequency higher than a resonance frequency determined by the elastic means and the movable member.   2. The image blur correction apparatus according to claim 1, wherein the phase compensation unit is a first-order phase advance compensation unit.   3. The image blur correction apparatus according to claim 1, wherein the control system of the correction unit is an open control system.   3. The image blur correction apparatus according to claim 1, wherein the control system of the correction unit is a feedback control system. A position detecting means for detecting the position of the correcting means;
5. The image blur correction apparatus according to claim 4, wherein the phase compensation unit compensates the phase of the signal from the position detection unit.   An image pickup apparatus comprising the image shake correction apparatus according to claim 1.

Images