JP5425335B2 - Image shake correction apparatus and imaging apparatus including the same - Google Patents

Description

  The present invention relates to an image blur correction apparatus that drives a lens for image blur correction and an imaging apparatus including the image blur correction apparatus.

  In recent years, the functions of cameras have been enhanced, and as a part of the enhancement of functions, there are many cameras equipped with an image shake correction device that corrects image shake caused by shake such as so-called camera shake. As described in Japanese Patent Application Laid-Open No. 2004-133867, the image shake correction apparatus performs shake detection such as camera shake based on a gyro signal, and performs image shake correction by moving a part of the optical system in a direction orthogonal to the optical axis. Many things are used.

Desirable characteristics of the image blur correction mechanism include:
1) Friction is small and tracking to the target is good. 2) It is easy for the designer to design the frequency characteristics. 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 such a mechanism, a mechanism capable of so-called open control and improved frequency characteristics can be obtained.

  A feature of the mechanism disclosed in Patent Document 3 is that a plurality of balls are sandwiched between a holding member that holds a correction lens and a fixing member and pressed by an elastic body. By setting it as such a mechanism, a holding member can be driven by rolling friction and a frictional force can be reduced. Further, since the resonance frequency is determined by the ratio of the weight of the correction lens and the holding member and the elastic coefficient of the elastic body, the target resonance frequency can be easily obtained. As a result, it is possible to obtain good controllability and appropriately respond to small vibrations.

  Patent Document 4 discloses a technique in which an attenuation unit is interposed in an actuator used for an optical disk pickup. The feature of the mechanism disclosed in Patent Document 4 is that an appropriate portion is filled with a gel damping material as a damping means. As a result, the frequency characteristics of the apparatus can be improved while improving workability.

JP 60-143330 A JP-A-8-184870 JP 2001-290184 A JP-A-2-232824

  According to Patent Document 2, viscous resistance can be obtained by a mechanical or electrical method. However, the mechanical method has a problem that the structure tends to be complicated and the friction increases. In addition, according to the electrical method, there are problems such that the control system is easily affected by variations in the control target and the control system is complicated.

  According to Patent Document 3, it can be driven with very small friction and can follow small hand movements. However, there is a problem that since there is no appropriate viscous resistance, the influence of the main resonance and the sub-resonance is large, and it is easily affected by the disturbance.

  According to Patent Document 4 described above, a structure having an appropriate viscous resistance can be easily obtained. However, there is a problem that an appropriate structure cannot always be obtained when used in an image blur correction apparatus.

(Object of invention)
SUMMARY OF THE INVENTION An object of the present invention is to provide an image blur correction device capable of changing the relative position of a holding member with respect to a fixed member with an appropriate viscosity attenuation with a simple structure, and an imaging device including the same.

  In order to achieve the above object, the present invention provides an image blur correction device that corrects image blur by deflecting an optical axis, and includes a base member and a correction member for correcting image blur, A holding member movable in a direction non-parallel to the optical axis with respect to the base member, and one of the base member and the holding member is formed with a hole portion whose one side is blocked by an ultraviolet ray transmitting member. A shaft portion that is inserted into the hole portion from the side that is not blocked by the ultraviolet light transmitting member is formed on the other of the base member or the holding member, and is formed in a gap between the shaft portion and the hole portion. Is characterized in that it is filled with a viscoelastic body made of a material that is cured by irradiation with ultraviolet rays.

  According to the present invention, it is possible to provide an image blur correction device that can change the relative position of the holding member with respect to the fixed member with an appropriate viscosity attenuation with a simple structure, and an imaging device including the image blur correction device.

It is a block diagram which shows the principal part of the imaging device which concerns on each Example of this invention. FIG. 2 is a block diagram illustrating an electrical configuration of the imaging apparatus in FIG. 1. It is a disassembled perspective view of the lens drive device concerning Example 1 of the present invention. It is the front view and sectional drawing which show the structure of the lens drive device which concerns on Example 1 of this invention. It is the top view and side view which show the actuator with which the lens drive device which concerns on Example 1 of this invention is equipped. It is the front view and sectional drawing for demonstrating attachment of the attenuation | damping means with which the lens drive device which concerns on Example 1 of this invention is equipped. It is a figure which shows the frequency characteristic of the viscoelastic body which concerns on Example 1 of this invention. It is an analysis model of the lens drive device concerning Example 1 of the present invention. It is a figure which shows an example of the various characteristics in Example 1 of this invention. It is a frequency response diagram of the analysis model of the lens drive device concerning Example 1 of the present invention. It is a block diagram of the experimental apparatus of the lens drive device which concerns on Example 1 of this invention. It is a frequency response diagram of the lens drive device concerning Example 1 of the present invention. It is a frequency response diagram of crosstalk of the lens drive device concerning Example 1 of the present invention. It is a block diagram which shows the signal processing system for control of the lens drive device which concerns on Example 1 of this invention. FIG. 14 is a frequency response diagram of a lens position controller provided in the signal processing system of FIG. 13. FIG. 3 is a frequency response diagram when a phase compensator is applied to the image shake correction apparatus according to the first embodiment of the present invention. It is a figure which shows the example of the amplitude of camera shake which concerns on Example 1 of this invention. It is a disassembled perspective view of the lens drive device which concerns on Example 2 of this invention. It is the front view and sectional drawing of a lens drive device concerning Example 2 of the present invention. It is the front view and side view which show the actuator with which the lens drive device which concerns on Example 2 of this invention is equipped. It is a distribution map of the magnetic field which concerns on Example 2 of this invention. FIG. 6 is a block diagram illustrating a control signal processing system of an image shake correction apparatus according to Embodiment 2 of the present invention. It is a block diagram which shows feedback control in the lens drive device which concerns on Example 2 of this invention. It is a frequency response diagram in feedback control in Example 2 of the present invention. FIG. 6 is a frequency response diagram of a phase lead compensator provided in an image shake correction apparatus according to Embodiment 2 of the present invention. It is a frequency response diagram in feedback control in Example 2 of the present invention. FIG. 6 is a frequency response diagram of a phase lead compensator provided in an image shake correction apparatus according to Embodiment 2 of the present invention. It is a frequency response diagram of the disturbance in feedback control in Example 2 of the present invention. It is a disassembled perspective view which shows the lens drive device which concerns on Example 3 of this invention. It is the front view and sectional drawing which show the lens drive device which concerns on Example 3 of this invention. It is the front view and side view which show the actuator with which the lens drive device which concerns on Example 3 of this invention is equipped. It is the front view and sectional drawing which show the lens drive device which concerns on Example 3 of this invention. It is a disassembled perspective view which shows the lens drive device which concerns on Example 4 of this invention. It is the front view and sectional drawing which show the lens drive device which concerns on Example 4 of this invention. It is a figure which shows a motion of a parallel link mechanism in the lens drive device which concerns on Example 3 of this invention. It is the front view and side view which show the actuator of the lens drive device which concerns on Example 4 of this invention. It is the front view and sectional drawing which show the lens drive device which concerns on Example 4 of this invention. It is a figure which shows the example of the speed of camera shake in Example 4 of this invention.

  The best mode for carrying out the present invention is as described in Examples 1 to 4 below.

Example 1
An imaging apparatus according to Embodiment 1 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 device, 2 denotes an imaging lens, and 3 denotes a lens driving device that drives a correction lens 12 described later. 4 is an optical axis of the imaging lens 2, 5 is a lens barrel, 6 is an imaging element, 7 is a memory, 8 is a shake sensor for detecting shake such as camera shake, 9 is a focus lens (not shown) included in the imaging lens 2, etc. Is a focus lens driving circuit for driving. Further, 10 is a power source, 11 is a release button, 12 is a correction lens, 13 is a so-called quick return mirror, and 14 is a finder optical system. Note that an image shake correction device is configured by the lens driving device 3 and the shake sensor 8.

  The imaging apparatus 1 forms an image in the vicinity of the imaging element 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 is recorded in the memory 7.

  Image blur correction using the correction lens 12 driven by the lens driving device 3 will be described. The lens driving device 3 can appropriately drive the correction lens 12. When camera shake occurs during exposure or the like, the lens driving device 3 operates the correction lens 12 by a drive signal for image blur 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 block 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 circuit 21. The recording / reproducing system includes a recording processing circuit 23 and a memory 24. The control system includes a camera system control circuit 25, an AF sensor 26, an AE sensor 27, a shake sensor 8, an operation detection circuit 29, and a lens system control circuit 30.

  The image pickup system is an optical processing system that forms an image of light from an object on the image pickup surface of the image pickup device 6 via the image pickup lens 2 and is appropriately used by using a diaphragm (not shown) based on a signal from the AE sensor 27. A large amount of object light is exposed to the image sensor 6. An image processing circuit 21 included in the image processing system is a signal processing circuit that processes an image signal of the number of pixels received from the image sensor 6 via the A / D converter 20, and includes a white balance circuit, a gamma correction circuit, and an interpolation. It has an interpolation calculation circuit that performs high resolution by calculation. A recording processing circuit 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. The recording processing circuit 23 compresses images and moving images by a predetermined method.

  The control system controls each part in response to a detection signal from the operation detection circuit 29 that detects the operation of the release button 11 and the like. A camera system control circuit 25 included in the control system generates and outputs a timing signal at the time of imaging. 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 circuit 30 controls the focus lens driving circuit 9 and the lens driving device 3 in accordance with a signal from the camera system control circuit 25.

  The control system controls the imaging system, the image processing system, and the recording / reproducing system in response to external operations. For example, pressing of the release button 11 is detected to control driving of the image sensor 6, operation of the image processing circuit 21, compression processing of the recording processing circuit 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.

  An AF sensor 26 and an AE sensor 27 are connected to the camera system control circuit 25, and a focus lens, a diaphragm, and the like are appropriately controlled via the lens system control circuit 30 based on these signals. In addition, the camera system control circuit 25 is connected to a shake sensor 8, and drives the lens driving device 3 based on a signal from the shake sensor 8 in a mode in which image shake correction is performed.

  Image blur correction by changing the image scanning range will be described. In accordance with a signal from the camera system control circuit 25, the scanning range of the A / D converter 20 can be changed. When camera shake occurs during exposure or the like, the scanning range is appropriately changed based on a signal from the shake sensor 8. This makes it possible to obtain an image that appears to be stationary even if the subject image is displaced on the image sensor 6. As a result, image blur provided to the image processing circuit 21 is reduced, and image degradation due to camera shake or the like can be corrected.

  In the case where both the image blur correction function by changing the image scanning range and the image blur correction function by driving the correction lens 12 are provided, when each shake correction function is driven simultaneously, the correction operation becomes excessive and the input The resulting image has a shake in the opposite direction to the shake. According to Japanese Patent Application Laid-Open No. 2004-260688, the shake correction unit that is driven is switched according to the characteristics of the input signal to appropriately operate. In the first embodiment, image blur correction associated with a change in the image scanning range is appropriately performed with a simple configuration while sufficiently performing the blur correction function of the correction lens 12.

  Next, the lens driving device 3 that is a main part of the first embodiment will be described with reference to FIGS. 3 to 16.

  FIG. 3 is an exploded perspective view of the lens driving device 3. In FIG. 3, 31 is a base plate, 36 is a movable lens barrel, and 32 a, 32 b, and 32 c are spheres held between the base plate 31 and the movable lens barrel 36. 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 is clear from FIG. 3, the lens driving device 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 lens driving device 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 in FIG. 4A, and FIG. 4C is a cross-sectional view taken along the line C- in FIG. It is C sectional drawing.

  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 becomes possible to suppress excitation of unnecessary resonance due to generation of moment. The elastic bodies 35a, 35b, and 35c are attached so as to be appropriately inclined in the optical axis direction (see FIG. 4C), and the balls 32a, 32b, and 32c provided between the base plate 31 and the movable lens barrel 36. Is gripping. A method for determining the elastic coefficients of the elastic bodies 35a, 35b, and 35c will be described later.

  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 spheres 32a, 32b, and 32c, and perform relative motion via the spheres 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. Further, by producing the guide surfaces by the balls 32a to 32c with appropriate accuracy, even when the base plate 31 and the movable lens barrel 36 are moved relative to each other, there is no need to tilt the movable lens barrel 36 or to the optical axis direction. There is no movement.

  The actuator provided in the lens driving device 3 will be described with reference to FIG. 4C and FIG. As shown in FIG. 4 (c), coils 33a and 33b are fixed to the base plate 31, and magnets 34a and 34b are fixed to the movable lens barrel 36. These constitute a so-called moving magnet type actuator. doing. 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, reference numeral 43 denotes a magnetization boundary. Further, 42a, 42b, and 42c shown in FIG. 5B schematically represent typical lines of magnetic force in the vicinity of the magnet 34a and the coil 33a. As shown in FIG. 5, 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 is arranged so that the two longitudinal portions 33a1 and 33a2 face the two regions 34a1 and 34a2 of the magnet 34a.

  As shown in FIG. 5B, a magnet attracting plate 37 is disposed on the surface of the magnet 34a opposite to the coil 33a. 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, magnetic lines of force 42a and 42b are linearly generated 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, current flows in the opposite directions in the longitudinal portions 33a1 and 33a2 in the direction perpendicular to the paper surface of FIG. 5B, and a driving force is generated according to Fleming's left-hand rule. As described with reference to FIG. 4A, the movable lens barrel 36 is elastically supported, so that the resultant force between the elastic bodies 35a, 35b, and 35c and the driving force are balanced between the base plate 31 and the movable lens barrel 36. Relative motion occurs.

  Next, with reference to FIG. 6, a description will be given of attachment of an attenuating means that makes it possible to obtain an appropriate viscous resistance with low friction so that a frequency characteristic suitable for image blur correction can be obtained. 6A is a front view of the lens driving device 3 viewed from the optical axis direction, FIG. 6B is a sectional view taken along the line DD in FIG. 6A, and FIG. 6C is a circle in FIG. 6B. It is detail drawing of the attenuation | damping means attachment part enclosed by.

  In FIG. 6, 44a and 44b are attenuation means attaching parts, 45 is attenuation means, and 46 is an arrow indicating the 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 attaching portions 44a and 44b be provided on the optical axis target. 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 attaching portion 44a. With respect to the cylindrical hole provided in the base plate 31, the suction plate fixing spiral 38a serving as a columnar shaft fixed to the movable barrel 36 is arranged so as to be substantially concentric, and a donut shape is formed in the gap. Attenuating means 45 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 there is an open part on one side of the unit, it is cured by irradiating ultraviolet rays from the direction of arrow 46 after applying the gel before curing. Desirable characteristics of the viscoelastic body used as the attenuating means 45 will be described later.

As shown in FIG. 6, the distance between the mechanical overrun prevention means constituted by the protrusion provided on the base plate 31 and the protrusion provided on the movable lens barrel 36 is a, and the damping means 45 shown in FIG. The distance between the movable barrel 36 where the attenuation means 45 shown in c) is provided and the base plate 31 serving as the fixed barrel is b. 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). for that reason,
a <b (1)
It is desirable to provide so as to satisfy. In order not to leave a permanent deformation, a <0.5b (2)
If it is the range, it is more suitable.

  Next, characteristics of the viscoelastic body as the damping means 45 suitable for the first embodiment will be described with reference to FIG. The viscoelastic body generally changes its characteristics depending on the input frequency, as shown in FIG. As is well known, in a viscoelastic body, an increase in frequency exhibits the same physical properties as a decrease in temperature. That is, as shown in FIG. 7, with the transition region 51b interposed therebetween, rubber properties are exhibited in the low frequency region 51a (hereinafter referred to as rubber region), and glass properties are exhibited in the high frequency region 51c (hereinafter referred to as glass region). . The rubber region is soft, and the glass region has a Young's modulus about 100 to 1000 times that of the rubber region.

Here, the transition region 51b will be described. In FIG. 7, f1 and f2 indicate a frequency that is sufficiently lower and sufficiently higher than the control frequency for camera shake correction. Considering a practical shutter speed of about 1 s to 1/4000 s and a practical focal length of 10 mm to 400 mm (35 mm equivalent) when shooting with the imaging device held by hand, the target control frequency band is 0. It is often set to about 3 Hz to 100 Hz. Here, f1 = 0.001 Hz as a sufficiently low frequency with respect to the control frequency, and f2 = 100000 Hz as a sufficiently high frequency with respect to the control frequency. G1 represents the complex elastic modulus at f1, and G2 represents the complex elastic modulus at f2. G3 and G4 are defined as follows using G1 and G2.
G3 = G1 + 0.1 (G2-G1) (3)
G4 = G1 + 0.9 (G2-G1) (4)
That is, G3 and G4 represent points where the complex elastic modulus has changed by 10% from the end of the width of the change in which the complex elastic modulus changes substantially. The region between G3 and G4 is defined as a transition region (51b) in this embodiment.

  Generally, tan δ which is the ratio of the real part to the imaginary part in the complex elastic modulus is increased in the transition region 51b between the rubber region and the glass region. tan δ indicates the hysteresis of the stress-strain diagram of the viscoelastic body, and a larger value can convert kinetic energy into thermal energy more efficiently. Therefore, as described above, a material having a control frequency band of 0.3 Hz to 100 Hz included in the transition region and a large tan δ is preferable. In recent years, many materials as described above have been developed, and various products are provided in addition to general butyl rubber. As an example, it can be said that a suitable viscoelastic material is, for example, inner and outer rubber-made honeynite, Miyasaka rubber-made Miya freak, three-bonded TB3168, or the like.

  Next, the design of the drive system will be described with reference to FIG. FIG. 8 is a model diagram in which the movement of the drive system in the first embodiment in the first embodiment is modeled. FIG. 8A shows a model when there is no attenuation means, and FIG. 8B shows a model when the attenuation means is interposed.

The lens driving device 3 of the first embodiment has three elastic bodies 35a, 35b, and 35c. However, when a specific movement direction is considered, the resultant force of a plurality of elastic bodies is a virtual spring, Think of it as a dash pod. As shown in FIG. 8A, it can be expressed as a spring mass point system with one degree of freedom. The displacement x with respect to the force F at this time is expressed by the following equation.
F = m (d2x / dt2) + c (dx / dt) + kx (5)

At this time, as described with reference to FIG. 4, the structure is configured to receive only a small amount of friction, so that the viscous resistance is generally small and the value of c is small. As a result, the resonance is strongly observed. That is, it can be said that the mechanism can respond appropriately to an input with a small amplitude, but is easily affected by a disturbance. Here, the damping ratio ζ is defined by the following equation.
ζ = c / (2√ (mk)) (6)

  Using the damping ratio ζ, it is possible to grasp the resonance peak state and transient response of the spring mass system. The controllability is good when the damping ratio ζ is about 0.3 near the resonance frequency, but the damping ratio ζ is only about 0.1 with a mechanism using only a generally used coil spring and no damping means. For this reason, a mechanism that does not include a damping means is easily affected by resonance and does not necessarily have good controllability.

FIG. 8B is a system in which damping means is interposed, and is a model diagram in which the resultant force of the damping means 45 is regarded as a virtual spring and dash pod, similar to the elastic bodies 35a, 35b, and 35c. is there. Reference numerals k1 and c1 denote springs and dash pods by elastic bodies, and k2 and c2 denote springs and dash pods by damping means. The displacement x with respect to the force F in FIG. 8B is F = m (d2x / dt2) + (c1 + c2) (dx / dt) + (k1 + k2) x (7)
It is expressed by the following formula.

When a suitable viscoelastic body as described in FIG. 7 is used as the damping means 45, tan δ shows a relatively large value in the control band. Some suitable materials can be obtained on the order of 1.0. Since a large tan δ is obtained in this way, sufficient attenuation can be obtained even if k2 is a small value. That is, attenuation can be appropriately imparted without reducing the sensitivity of the actuator. The attenuation ratio ζ at this time is expressed by the following equation.
ζ = (c1 + c2) / (2√ (m (k1 + k2))) (8)

  FIG. 10 shows frequency response diagrams based on the calculation results when the attenuating means 45 is interposed and not inserted under the conditions shown in FIG.

  FIG. 9 shows an example of a mechanism suitable for an upper limit of control frequency of about 30 Hz. In this model, the movable part mass is 3 g. In addition, the resonance frequency may be set to a frequency higher than the control frequency in consideration of the control frequency, but here it is set to 60 Hz. In order to increase the control frequency by so-called open control, it is desirable to further increase the resonance frequency. As for the elastic coefficient of the elastic body, as shown in FIG. 9, the elastic coefficient k1 by the elastic body and the elastic coefficient k2 by the damping means are determined in consideration of the mass of the movable part, the control frequency, and the damping ratio of the entire system. In FIG. 9, the system is designed to obtain 0.3 as the system damping ratio. Generally, if the elastic coefficient k2 by the damping means is increased, the damping ratio of the system increases. However, if the elastic coefficient by the elastic body decreases, the fluctuation due to its own weight or disturbance increases. The

  As can be seen from FIG. 10, the resonance peak appears prominently without the attenuation means, and is easily affected by disturbance. On the other hand, in the state where the attenuating means is provided, the resonance is sufficiently suppressed and hardly affected by disturbance. Further, the attenuation ratio in the state where the attenuation means is provided is about 0.3, and an appropriate value is obtained. When the attenuation ratio is about 0.3 as shown in FIG. 9, the gain increase due to resonance is small and the phase delay is relatively small. It is desirable to appropriately determine the ratio of the elastic coefficient between the damping means and the elastic body so that the damping ratio is about 0.3 in consideration of controllability. By changing the complex elastic coefficient and shape of the damping means, the elastic coefficient of the damping means can be set to a desired value.

  Next, experimental data and effects of the first embodiment will be described with reference to FIGS. 11 to 13. FIG. 11 is a diagram showing an outline of the experimental apparatus. A signal from the FFT analyzer 404 is applied to the coil via the motor driver 403 to drive the lens driving device 3. The response of the lens driving device 3 was measured by a laser displacement meter 401 and input to the FFT analyzer 404 via the laser displacement meter amplifier 402 to obtain a frequency response.

  FIG. 12 shows experimental data of the frequency response with and without the attenuation means. In the experiment of FIG. 12, a movable part and an elastic body were prepared so that the mass of the movable part was about 5 g and the resonance frequency was about 40 Hz. As an attenuating means, TB3168 manufactured by ThreeBond was used by appropriately curing with ultraviolet rays. The magnet was magnetized by dividing a neodymium magnet into two regions, and a soft magnetic material was used for the magnet adsorption plate. The coil used was a fusible polyurethane copper wire. By energizing the coil, a driving force proportional to the current is generated, and the coil moves to a position that balances with the resultant force of the elastic body. At this time, a positional relationship in which the resultant force of the elastic body and the driving force do not generate a moment is desirable, but a moment is generated due to the influence of an assembly error or the like, and a rotational motion (hereinafter, rolling) around the optical axis is excited. The resonance peak 52 near 40 Hz when there is no attenuation means in FIG. 12 is resonance in the driving force direction, and the resonance peak 53 near 80 Hz is unnecessary resonance generated by rolling. As can be seen from FIG. 12, the resonance peaks 52 and 53 are high due to the mechanism of low friction and low viscous resistance. On the other hand, when there is an attenuation means, no resonance peak is observed even in the vicinity of 60 Hz where the phase is delayed by 90 degrees. For this reason, it is possible to control stably. Although fluctuations in gain and phase are observed from around the frequency exceeding 10 Hz, this effect can be mitigated by a phase compensator described later.

  FIG. 13 shows experimentally acquired leakage of motion (hereinafter, crosstalk) in the other axial direction when driven in one axial direction. Crosstalk is acceptable to some extent because it is corrected based on sensor output in the case of feedback control, but it must be kept small in so-called open control. The cause of crosstalk is due to an assembly error of the elastic body and the driving means, and it is not easy to completely eliminate the crosstalk. In addition, when rolling is excited, a large amount of crosstalk is observed. As shown in FIG. 13, by providing the attenuating means at an appropriate position, it is possible to suppress rolling and to reduce crosstalk. For example, it is preferable to provide a damping means at a location where a large speed is generated when rolling. In the first embodiment, the attenuation means is disposed at a position relatively distant from the optical axis. Since the crosstalk can be reduced, the first embodiment is particularly useful in an apparatus that performs open control.

  Next, suitable control of the lens driving device 3 shown in the first embodiment will be described with reference to FIGS.

  FIG. 14 is a block diagram of a signal processing system that generates a control signal for the lens driving device 3. In FIG. 14, 61 is an angular velocity sensor, 62 is a low-pass filter (hereinafter referred to as LPF), and 63 is a CPU. Reference numeral 64 denotes an A / D converter, 65 denotes an integrator, 66 denotes a high-pass filter (hereinafter referred to as HPF), and 67 denotes a memory in which information on the imaging apparatus is recorded. 68 is a lens position converter for calculating the position of the lens, and 69 is a lens position controller. Reference numeral 70 denotes a motor driver, and 3 denotes a lens driving device.

  As shown in FIG. 14, an angular velocity sensor is often used as the shake sensor 8 that detects image shake such as camera shake. In the first embodiment, the following explanation will be given by taking the angular velocity sensor 61 as an example. The angular velocity sensor 61 detects, for example, an angular velocity due to camera shake, and outputs a signal proportional to the angular velocity. The LPF 62 is provided for cutting noise and cuts high frequency noise of the angular velocity sensor 61. The CPU 63 performs calculations for control necessary for image blur correction, and includes an A / D converter 64, an integrator 65, an HPF 66, a memory 67, a lens position converter 68, and a lens position controller 69 therein. I have. The function of each part is described below.

  The A / D converter 64 digitally converts the signal that has passed through the LPF 62 at an appropriate sampling period. The sampling period is preferably about 100 times the control band. For example, in the lens driving device 3 that performs control up to 50 Hz, a sampling period of about 5000 Hz is preferable because the influence of sampling can be ignored. The integrator 65 integrates the angular velocity signal and obtains an angle due to camera shake. The HPF 66 is a filter that removes the low frequency fluctuation of the angular velocity sensor 61. The filter time constant is appropriately set in consideration of the low frequency fluctuation and the control band. Further, the HPF 66 can acquire information on photographing conditions such as zoom information from the memory 67 and appropriately change the time constant of the filter. The lens position converter 68 calculates the amount of movement of the lens driving device 3 (specifically, the correction lens 12) with respect to the input shake from information such as zoom and focus obtained from the memory 67. The lens position controller 69 performs appropriate phase compensation in consideration of the frequency characteristics of the lens driving device 3 and the like. The lens position controller 69 outputs the result to the motor driver 70, and the lens driving device 3 is driven.

  FIG. 15 shows an example of a phase compensator provided in the lens position controller 69. FIG. 15 shows a first-order phase advance filter, and the calculation load on the CPU 63 is small. Therefore, even a CPU having a relatively low cost and a low calculation capability can be applied. If the CPU capacity is not sufficient, the lens position controller 69 can be simply configured by a resistor and a capacitor outside the CPU. When there is a margin in CPU capacity, it is possible to obtain controllability higher than that shown in the first embodiment by configuring a higher-order phase filter.

  FIG. 16 is a frequency response diagram of the lens driving device 3 before and after applying the phase compensator shown in FIG. By applying the phase compensator, it can be seen that the flat portion of the gain and phase continues to a high frequency band. This indicates that even when so-called open control is performed, the mechanism can follow high-frequency camera shake.

  FIG. 17 shows a typical camera shake amplitude in the frequency domain. The vertical axis represents the power spectrum, which corresponds to the camera shake amplitude and is described in logarithm. The vertical axis represents 10 times on one scale. As can be seen from FIG. 17, the hand shake amplitude decreases as the frequency increases. It can be seen that the effect of the high frequency is relatively small for low frequency camera shake. On the other hand, considering that it is only necessary to suppress camera shake during the time delimited by the shutter speed when shooting still images and the frame rate when shooting movies, the influence of low-frequency vibrations is also relatively small. Become. As an example, FIG. 17 shows the camera shake amplitude when it is cut off at 1/30 seconds. At this time, a range in which the amplitude increases may be set as the control band. The shutter speed and the frame rate may be set to suitable values according to the specifications of the imaging device. FIG. 17 shows a case where about 0.3 Hz to 20 Hz is defined as the control band.

  As shown in FIG. 17, the mechanism of the first embodiment sets the control band at a frequency of 100 Hz or less. In the objective lens actuator of an optical disk, the control band reaches several kHz. In such an actuator that requires a response at a very high frequency, a region close to the glass region 51c of the viscoelastic body shown in FIG. 7 must be used, and the viscoelastic body becomes a load. For this reason, the method of interposing directly between a movable part and a fixed part is difficult to take. On the other hand, in the first embodiment, since the control band is a low frequency band of 100 Hz or less and the band is also narrow, the transition region of the viscoelastic body shown in FIG. 7 can be used.

Next, the relationship between the amount of movement of the movable lens barrel in the control state and the attenuation means will be described. In the open control described above, there is a case where the drive range is electrically limited due to the current limitation. Let c be the amount of movement of the movable lens barrel in the controlled state. The damping means 45 is preferably used in a range where no major deformation occurs and permanent deformation does not occur (= a range where the elastic modulus changes linearly). Therefore, b> c (9)
It is desirable to provide so as to satisfy. In addition, b is an interval shown in FIG. In order to leave no permanent deformation, 0.5b> c (10)
If it is the range, it is more suitable.

As explained above, according to the first embodiment of the present invention,
1) Appropriate damping can be added to the mechanism of small friction 2) Easy assembly and low cost 3) The lens driving device 3 having an effect that appropriate control performance can be obtained even with open driving Can be obtained.

(Example 2)
A second embodiment according to the present invention will be described with reference to FIGS. Since the functions of each part of the imaging apparatus shown in FIGS. 1 and 2 are described in detail in the first embodiment, they are omitted here.

  With reference to FIGS. 18 to 28, the lens driving device 3 which is a main part according to the second embodiment of the present invention will be described. FIG. 18 is an exploded perspective view of the lens driving device 3. In FIG. 18, components having the same functions as those of the lens driving device 3 of Example 1 are assigned the same numbers. 101 is a magnet attracting plate, and unlike the magnet attracting plate 37 of the first embodiment, an appropriate hole is provided. As is clear from FIG. 18, 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. 19 is a configuration diagram of the lens driving device 3. Specifically, FIG. 19A is a front view seen from the optical axis direction, FIG. 19B is a cross-sectional view taken along line BB in FIG. 19A, and FIG. 19C is a cross-sectional view taken along line CC in FIG. A sectional view, FIG. 19 (d) is a partial detail view of FIG. 19 (c).

  As shown in FIG. 19, 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, 35 b, 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 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, 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, and 32c provided between the base plate 31 and the movable lens barrel 36. A method for determining the elastic coefficients of the elastic bodies 35a to 35c will be described later.

  The guide surface configuration of the movable lens barrel 36 in the lens driving device 3 has the same structure as that shown in FIG.

  The actuator which is the drive part of the lens drive device 3 is demonstrated using FIG.19 (b), FIG. 20, FIG. The actuator has substantially the same structure as that shown in FIG. That is, relative movement occurs between the base plate 31 and the movable lens barrel 36 by energizing the coils 33a and 33b, which are one of the components of the actuator. The difference is that the sensor 102 is provided on the non-facing surface side of the magnets 34a and 34b with respect to the coils 33a and 33b. 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 sensor 102 as described above, the driving magnet 34a is also used as a position detecting magnet.

  20A and 20B are schematic views of the actuator. FIG. 20A is a view of the magnet 34a, the coil 33a, and the sensor 102 seen from the optical axis direction, and FIG. 20B is a cross-section when the magnet 34a is cut near the center. The figure is shown.

  In FIG. 20, reference numeral 110 denotes a magnetic sensing part of the sensor. In the magnetic circuit shown in FIG. 20, the magnetic lines of force 42a, 42b, and 42c flow as shown by the arrows shown in FIG. In the state of FIG. 20B, 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. 21 shows a result obtained experimentally. In FIG. 21, the movement amount 0 means a state in which the magnetic sensing part 110 shown in FIG. 20B is located immediately above the magnetization boundary 43. As can be seen from FIG. 21, in a certain range, the movement amount and the strength of the magnetic field have a linear relationship, and in this range, the position can be detected linearly.

  The attachment of the attenuating means will be described with reference to FIGS. 19 (c) and 19 (d). In FIGS. 19C and 19D, reference numerals 103a and 103b denote attenuating means mounting portions, 104 attenuating means, 105a an ultraviolet ray transmitting plate, and 106 an arrow indicating an ultraviolet irradiation direction. As shown in FIG. 19C, 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 are extended toward the hole provided in the base plate 31 so as to overlap at least the base plate 31 in the optical axis direction and not penetrate therethrough. Exist. After the ultraviolet transmissive plate 105a is attached to the base plate 31, the attenuation means 104 is injected, and then the movable lens barrel 36 is incorporated. Finally, the attenuation means 104 is cured by irradiating ultraviolet rays from the direction of the arrow 106. The viscoelastic body used as the attenuating means 104 is assumed to be that shown in the first embodiment.

  A suitable control of the lens driving device 3 shown in the second embodiment will be described with reference to FIGS.

  FIG. 22 is a block diagram of a signal processing system that generates a control signal for the lens driving device 3. 22 that have the same functions as those in FIG. 14 of the first embodiment are denoted by the same reference numerals. Reference numeral 111 denotes a lens position detection sensor, and 112 denotes an A / D converter.

  As shown in FIG. 22, the input of the lens position controller 69 is obtained by appropriately processing the signal of the angular velocity sensor 61 by the CPU 63 as in the first embodiment. In the second embodiment, the lens position controller 69 performs so-called feedback control, and in addition to the signal from the lens position converter 68, the lens position information obtained via the lens position sensor 111 and the A / D converter 112. Is used to control the correction lens.

  A block diagram of the feedback control is shown in FIG. In FIG. 23, the target lens position indicates the target position given from the lens position converter 68. Further, it is assumed that the sampling rate of the A / D converter 112 is sampling at a frequency sufficiently higher than the control band. That is, there is no phase delay due to sampling, and in FIG. 23, there is no problem even if it is handled as a continuous quantity. Actually, a lens driving device used for image blur correction does not require a response at a high frequency, and can be assumed as described above.

23, the transfer function of the lens position controller 69 is G2 (s), the driver gain of the motor driver 70 is Gd, the transfer function of the actuator 113 of the lens driving device 3 is G1 (s), and the lens position sensor 111 Let the gain be Gs. Then, the open loop characteristic Open (s) is
Open (s) = GdG1 (s) G2 (s) (11)
It is represented by

Furthermore, the closed loop characteristic Gclose (s) is
Gclose (s) = (GdGsG1 (s) G2 (s)) / (1 + GdGsG1 (s) G2 (s)) (12)
It is expressed. The frequency response diagrams at this time are shown in FIGS.

  FIG. 24 shows an open loop characteristic (shown as Open) and a closed loop characteristic (shown as Close) with no damping means interposed. In the second embodiment, in order to simplify the control system, the lens position controller 69 is composed of a primary phase lead compensator.

  FIG. 25 is a frequency response diagram of the phase lead compensator applied to FIG. Even when the phase lead compensator as shown in FIG. 25 is applied, it is difficult to sufficiently increase the crossover frequency in view of the phase margin. In the example of FIG. 24, the crossover frequency is in the vicinity of 60 Hz, and the phase margin is about 30 deg. Although it is desired to lower the band where the phase advance compensator advances the phase, it is difficult because unnecessary resonance is in the vicinity of 80 Hz. For this reason, it is difficult to increase the crossover frequency without increasing the low frequency sensitivity. If the crossover frequency is increased, the phase margin becomes insufficient and the control system causes an oscillation phenomenon. Since the crossover frequency cannot be increased sufficiently, even in the closed-loop characteristic, the phase is greatly generated from the low frequency. As a result, there is a possibility that sufficient performance cannot be obtained when a lens driving device is provided as an image shake correction device of the imaging device.

  FIG. 26 shows an open loop characteristic (shown as Open) and a closed loop characteristic (shown as Close) with an attenuation means interposed. FIG. 27 is a frequency response diagram of the phase lead compensator applied to FIG. When the phase lead compensator as shown in FIG. 27 is applied, the crossover frequency can be set in the vicinity of 100 Hz. Further, the phase margin is about 45 degrees, and a very stable control system can be configured. Further, since the crossover frequency can be set high, the phase delay can be suppressed to a relatively high frequency. In the second embodiment, an appropriate open loop characteristic is designed in consideration of the closed loop characteristic. That is, the elastic coefficient of the elastic body that supports the movable lens barrel 36 may be appropriately set so as to obtain a desired resonance frequency with open loop characteristics.

  As is clear from comparison between FIG. 24 and FIG. 26, the above-described desirable characteristics can be obtained even in an apparatus that performs feedback control by appropriately providing the attenuating means 104.

Furthermore, the effect when a disturbance acts will be described with reference to FIGS. When the transfer function Gnoise (s) from the disturbance to the actual lens position in the block diagram of FIG. 23 is obtained, it can be expressed as follows.
Gnoise (s) = (GdG1 (s)) / (1 + GdGsG1 (s) G2 (s)) (13)

  This frequency response diagram is shown in FIG. As is apparent from FIG. 28, it can be seen that the presence of the attenuating means 104 has a smaller gain at the actual lens position with respect to disturbance and is less susceptible to influence.

As explained above, according to the second embodiment of the present invention,
1) Appropriate damping can be added to a small friction mechanism 2) Easy assembly and low cost 3) Stable controllability and phase delay suppression even with feedback drive The drive device 3 can be obtained.

(Example 3)
A third embodiment according to the present invention will be described with reference to FIGS. Since the functions of each part of the imaging apparatus shown in FIGS. 1 and 2 are described in detail in the first embodiment, they are omitted here.

  With reference to FIGS. 29 to 32, the lens driving device 3 which is a main part according to the third embodiment of the present invention will be described. FIG. 29 is an exploded perspective view of the lens driving device 3.

  In FIG. 29, the same number is attached | subjected about what has the same function as the lens drive device 3 of Example 1. In FIG. 201a, 201b and 201c are sliding shafts, 202 is a lock ring, 203 is a lock ring drive motor, 204 is a rotation prevention bar, 205 is a fixed yoke, and 206 is a positioning pin. 207a, 207b, 208, 212a, 212b, 214 are screws, 209a, 209b are LEDs, 210 is a counter yoke, 211 is a light shielding plate, 213 is a relay FPC, and 215 is a photo interrupter.

  The coils 33 a and 33 b and the LEDs 209 a and 209 b are fixed to the movable lens barrel 36 and move integrally with the movable lens barrel 36. The relay FPC 213 is fixed to the base plate 31 by screws 214, and supplies power to the LEDs 209a and 209b, the photo interrupter 215, and the coils 33a and 33b via elastic portions on the relay FPC 213.

  FIG. 30 is a plan view of the lens driving device 3. 30A is a front view seen from the optical axis direction, FIG. 30B is a cross-sectional view taken along the line BB in FIG. 30A, and FIG. 30C is a cross-sectional view taken along the line CC in FIG. is there.

  29 and 30B, the sliding shafts 201a, 201b, and 201c are fitted in fitting holes provided on the base plate 31 and elongated holes provided on the movable lens barrel 36. And is fixed to the base plate 31. By using three sliding shafts and a long hole, the guide is guided in a plane perpendicular to the optical axis. The lock ring 202 is driven via a gear 216 attached to the lock ring drive motor 203. By rotating the lock ring 202, the contact and non-contact of the lock ring 202 and the movable lens barrel 36 can be changed. When the movable barrel 36 is driven, the lock ring 202 and the movable barrel 36 are brought into a non-contact state so that the movable barrel 36 can be driven by an actuator described later. On the other hand, when the power is turned off, the movement of the movable lens barrel 36 is restricted with respect to the base plate 31 by bringing the lock ring 202 and the movable lens barrel 36 into contact with each other. The movement of the lock ring 202 can be detected by the photo interrupter 215. Further, the anti-rotation bar 204 has an L-shape, and is arranged so as to constrain the rotational motion while providing a suitable contact point so that translational motion in a plane perpendicular to the optical axis is free. ing.

  The actuator of the lens driving device 3 will be described with reference to FIG. As shown in FIG. 29C, the coil fixing yoke 205, the opposing yoke 210, and the magnets 34a1 and 34a2 are fixed to the base plate 31, and the coil 33a is fixed to the movable lens barrel 36. And what is called a moving coil type | mold actuator is comprised.

  FIG. 31 is a schematic diagram of the actuator. FIG. 31A is a view of only the magnets 34a1 and 34a2 and the coil 33a seen from the optical axis direction, and FIG. 31B is a view when the magnets 34a1 and 34a2 are cut near the center. FIG. As shown in FIG. 31A, the two magnets 34a1 and 34a2 are magnetized in opposite directions. In FIG. 31B, reference numerals 42a, 42b, 42c, and 42d schematically represent typical magnetic lines of force near the magnets 34a1 and 34a1 and the coil 33a. The coil 33a has an oval shape when viewed from the optical axis direction, and is arranged so that the two longitudinal portions 33a1 and 33a2 face the two magnets 34a1 and 34a2.

  As shown in FIG. 31B, there is a fixed yoke 205 on the surface of the magnets 34a1 and 34a2 opposite to the coil 33a. The fixed yoke 205 is preferably a soft magnetic material, and as shown in FIG. 31B, a large amount of magnetic flux is transmitted to lower the permeance of the magnetic circuit. Furthermore, a counter yoke 210 exists on the non-facing surface side of the coil 33a with respect to the magnets 34a1 and 34a, forming a so-called closed magnetic path. As a result, magnetic lines of force 42a and 42b are linearly generated from the magnet 34a toward the coil 33a. Since the fixed yoke 205 and the counter yoke 210 are fixed to the base plate 31, the thickness can be set appropriately so that the magnetic flux is not saturated without worrying about the weight. When the coil 33a is energized in this state, a current flows in the opposite direction to the longitudinal portions 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. 30B, the movable lens barrel 36 is guided in a plane perpendicular to the optical axis, and thus moves in this plane. Position detection is performed by a lens position sensor described later, and so-called feedback control is performed, so that the lens can be moved to an arbitrary position.

  FIG. 32 is a plan view of the lens driving device 3. 32A is a front view seen from the optical axis direction, FIG. 32B is a cross-sectional view taken along the line BB in FIG. 32A, and FIG. 32C is a cross-sectional view taken along the line CC in FIG. FIG. 32 (d) is a partial detail view of FIG. 32 (c).

  The lens position sensor will be described with reference to FIG. As shown in FIG. 32B, the lens position sensor is a one-dimensional PSD (semiconductor position detection) fixed to the base plate 31 via an LED (infrared light emitting diode) 209a fixed to the movable lens barrel 36 and the FPC 40. Instrument) 217a. Here, in order to simplify the description, detection in one-axis direction will be described. However, it is possible to detect the position in two-axis direction by using another set of LED and one-dimensional PSD or using two-dimensional PSD. The LED 209a is supplied with power via the relay FPC 213, and light emission is started when image blur correction is performed. The one-dimensional PSD 217a is mounted on the FPC 40 and is supplied with power when image blur correction is performed in the same manner as the LED 209a. When the movable lens barrel 36 moves relative to the base plate 31, the light amount distribution on the one-dimensional PSD 217a changes, so that the position of the movable lens barrel 36 can be detected. By performing feedback control similar to that in the second embodiment based on this signal, the lens position can be controlled to a target position and image blur correction can be performed.

  The attachment of the damping means will be described with reference to FIGS. 32 (c) and 32 (d). 32 (c) and 32 (d), reference numeral 218 denotes an attenuation means mounting portion, and 219 denotes an attenuation means. FIG. 32 (d) is a partial detail view in which the damping means mounting portion of FIG. 32 (c) is enlarged.

  As described with reference to FIG. 30B, the sliding shaft 201 a is fitted in a long hole on the movable lens barrel 36. In the third embodiment, the attenuation means 219 is filled in the gap portion of the long hole. 32 (c) and 32 (d), only the location of the sliding shaft 201a is shown, but the sliding means 201b and 201c (not shown) are similarly filled with the attenuation means 219 in the gap portion of the elongated hole. Appropriate attenuation can be obtained as in the first and second embodiments. In the third embodiment, the attenuating means and the driving means exist on substantially the same plane. That is, the center of the sliding shaft 201a, which is the center of the attenuating means 219, and the center of the coils 33a, 33b, which are the thrust centers of the drive unit, exist on substantially the same plane perpendicular to the optical axis. With such an arrangement, the movable barrel 36 does not perform unnecessary yawing and pitching operations due to the force received from the attenuation means 219.

As explained above, according to the third embodiment of the present invention,
1) Appropriate attenuation can be added 2) Unnecessary yawing and pitching operations can be suppressed 3) The lens driving device 3 having the effect of suppressing stable controllability and phase delay even with feedback driving is obtained. Can do.

Example 4
A fourth embodiment according to the present invention will be described with reference to FIGS. Since the functions of each part of the imaging apparatus shown in FIGS. 1 and 2 are described in detail in the first embodiment, they are omitted here.

  With reference to FIGS. 33 to 37, the lens driving device 3 which is a main part according to the fourth embodiment of the present invention will be described.

  FIG. 33 is an exploded perspective view of the lens driving device 3. In FIG. 33, components having the same functions as those of the image blur correction device of Embodiment 1 are denoted by the same reference numerals. 301a, 301b, 301c, 301d are elastic wires, 302a, 302b are fixed yokes, 303a, 303b, 303c, 303d, 307a, 307b, 308a, 308b are screws. Reference numeral 304 denotes a fixed PCB, reference numeral 305 denotes a movable PCB, and reference numerals 306a and 306b denote fixed pins.

  The fixed yokes 302a and 302b are fixed to the base plate 31 by screws 303a, 303b, 303c and 303d. The fixed PCB 304 is fixed to the base plate 31 by screws 307a and 307b, and the movable PCB 305 is fixed to the movable barrel 36 by screws 308a and 308, respectively. The magnets 334a and 334b are attracted to the fixed yoke 302a, and the magnets 334c and 334d are secured to the base plate 31 by being attracted to the fixed yoke 302b.

  FIG. 34 is a plan view of the lens driving device 3. 34 (a) is a front view seen from the optical axis direction, FIG. 34 (b) is a sectional view taken along line BB in FIG. 34 (a), and FIG. 34 (c) is a sectional view taken along line CC in FIG. It is.

  The main components of the lens driving device 3 according to the fourth embodiment will be described with reference to FIGS. 33, 34 (b), and 35. The movable lens barrel 36 is elastically supported by the base plate 31 via four elastic wires 301a, 301b, 301c, and 301d. The elastic wires 301a, 301b, 301c, and 301d are fixed to the fixed PCB 304 and the movable PCB 305 by soldering. The movable lens barrel 36 is supported as an elastic body and also serves as a power supply line to the coils 33a and 33b. As materials suitable for such applications, phosphor bronze wires, beryllium copper wires, and the like are known. By providing four wires with the same length substantially parallel to the optical axis, the movable barrel 36 moves approximately the same as the parallel link mechanism.

FIG. 35 schematically shows the movement of the parallel link mechanism. In FIG. 35, 309a and 309b are links that model the elastic wires 301a, 301b, 301c, and 301d. The elastic wires 301a, 301b, 301c, and 301d generate displacement by bending, but in FIG. 35, the displacement due to bending deformation is expressed by rotation of the link, and the link 309 is considered as a rigid body because there is no other deformation. As shown in FIG. 35, by forming the parallel link mechanism, the movable lens barrel 36 can be guided perpendicularly to the optical axis without causing an inclination. In the parallel link mechanism, movement in the optical axis direction occurs. For example, assuming that the movable range is x and the length of the wire is l, the fluctuation in the optical axis direction is expressed by the following equation.
l (1-cos (tan-1 (x / l))) (14)

  For example, if the movable range is set to ± 0.3 mm and the length of the wire is set to about 10 mm, the fluctuation in the optical axis direction is 5 μm or less, which is an allowable range. That is, it can guide without tilting in a plane substantially perpendicular to the optical axis.

  The actuator of the lens driving device 3 will be described with reference to FIG. 34 (c) and FIG. As shown in FIG. 34C, the coil fixing yoke 302 and the magnets 334c and 334d are fixed to the base plate 31, and the coil 33b is fixed to the movable barrel 36. And what is called a moving coil type | mold actuator is comprised.

  FIG. 36 is a schematic diagram of the actuator. FIG. 36A is a view of only the magnets 334c and 334d and the coil 33a viewed from the optical axis direction, and FIG. 36B is a view when the magnets 334c and 334d are cut near the center. FIG. In FIG. 36A, reference numeral 43 denotes a magnetization boundary. In FIG. 36B, reference numerals 42a, 42b, 42c, and 42d schematically represent typical magnetic lines of force near the magnets 334c and 334d and the coil 33a. As shown in FIG. 36A, the magnet 334d is magnetized in two regions 334d1 and 334d2 with the magnetization boundary 43 interposed therebetween. The same applies to the magnet 334c. The coil 33a has an oval shape when viewed from the optical axis direction, and is disposed so that the two longitudinal portions 33a1 and 33a2 face, for example, the two regions 334d1 and 334d2 of the magnet 334d.

  On the surface of the magnet 334c opposite to the coil 33a, there is a fixed yoke 302b as shown in FIG. The fixed yoke 302b is preferably a soft magnetic material, and transmits a large amount of magnetic flux to lower the permeance of the magnetic circuit. Further, the fixed yoke 302b is also provided on the surface of the magnet 334d opposite to the coil 33a. The magnet 334c and the magnet 334d are arranged to be attracted to each other. As a result, magnetic lines of force 42a and 42b are linearly generated from the magnet 334a toward the coil 33a. In the fourth embodiment, the fixed yoke 302b is fixed to the base plate 31, so that the weight of the movable portion does not change even if the thickness is increased. Accordingly, the thickness of the fixed yoke 302b can be appropriately determined so that the fixed yoke 302b is not saturated in consideration of 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 the longitudinal portions 33a1 and 33a2 in the direction perpendicular to the paper surface of FIG. 36B, and a driving force is generated according to the Fleming left-hand rule. As described with reference to FIG. 34, the movable lens barrel 36 is elastically supported, so that the relative force between the base plate 31 and the movable lens barrel 36 is such that the resultant force of the elastic wires 301a, 301b, 301c, 301d and the driving force are balanced. Movement occurs. Since the relationship between the resultant force of the elastic wires 301a, 301b, 301c, and 301d and the current for generating the driving force is proportional, the mechanism shown in the fourth embodiment can be controlled by so-called open control.

  The attachment of the attenuation means will be described with reference to FIG. 37A is a front view seen from the optical axis direction, FIG. 37B is a cross-sectional view taken along the line BB of FIG. 37A, and FIG. 37C is a detailed view of FIG. 37B. In FIG. 37, 310a and 310b are damping means mounting portions, and 311 is a damping means.

  As shown in FIG. 37 (b), the fixed pins 306a and 306b are spirally fastened to the base plate 31 and then over the movable lens barrel 36 at least in the optical axis direction toward the hole provided in the movable lens barrel 36. It extends to wrap.

  FIG. 37 (c) is a detailed view of the damping means mounting portion 310a. A cylindrical fixing pin 306a is arranged so as to be substantially concentric when fixed to the base plate 31 with respect to a cylindrical hole provided in the movable lens barrel 36, and a damping means 311 is formed in a donut shape in the gap. Is provided. As the attenuating means 311, the viscoelastic body exemplified in Example 1 is suitable. Thus, by interposing the attenuation means 311, the same effect as in the first embodiment can be obtained. In the fourth embodiment, the fixing pins 306a and 306b are used to facilitate the assembly. However, the fixing pins 306a and 306b may be manufactured as a structure on the base plate 31 by changing the shape. Is possible.

  In the fourth embodiment, the attenuating means 311 and the drive unit are on substantially the same plane. That is, the center of the attenuating means 311 and the centers of the coils 33a and 33b, which are the thrust centers of the drive unit, exist on substantially the same plane perpendicular to the optical axis. With this arrangement, the movable barrel 36 does not perform unnecessary yawing and pitching operations due to the force received from the attenuation means 311.

  FIG. 38 shows a typical camera shake speed in the frequency domain. The vertical axis represents the speed required for the mechanism for camera shake correction, and corresponds to the angular speed of camera shake. The vertical axis is shown in logarithm. The vertical axis represents 10 times on one scale. As shown in FIG. 17, it can be seen that the camera shake amplitude decreases as the frequency increases. For this reason, as for the speed due to camera shake, the same speed is input even if the frequency changes as shown in FIG. When the user operates the imaging apparatus to determine the composition, a speed that is not too large is not input as the speed of camera shake.

  Therefore, as shown in FIG. 38, the mechanism of the fourth embodiment regulates the control speed to 0.02 m / s. The moving coil type actuator as in the fourth embodiment has a merit that the control speed can be limited. However, for example, when a stepping motor is used as a drive source, there is a merit that the possibility of step-out is reduced.

As explained above, according to the fourth embodiment of the present invention,
1) Appropriate attenuation can be added 2) Unnecessary yawing and pitching operations can be suppressed 3) The lens driving device 3 having an effect that appropriate control performance can be obtained even with open drive can be obtained.

  The effects in each of the above embodiments will be listed together below.

1) The lens driving device 3 can be moved in a plane substantially perpendicular to the optical axis of a fixed barrel such as a base plate 31 that holds the imaging lens 2 that forms the subject image and the correction lens 12 included in the imaging lens 2. The movable lens barrel 36 to be held and an actuator (Examples 1 to 3) for changing the relative position of the movable lens barrel 36 with respect to the fixed lens barrel in the frequency domain in a band of 100 Hz or less, or the movable lens barrel Attenuating means 45, 104, 219, 311 between an actuator (Embodiment 4) for changing the relative position of 36 with respect to the fixed barrel at a speed of 0.02 m / s or less, and the movable barrel 36 and the fixed barrel. It is the structure which intervened.
According to the above configuration, the lens driving device 3 having a simple structure, a small friction, an appropriate viscous resistance, and a frequency characteristic suitable for image blur correction due to camera shake or the like can be obtained.

2) The lens driving device 3 further includes a plurality of spheres 32a to 32c sandwiched between the movable lens barrel 36 and the fixed lens barrel, and elastic bodies 35a to urge the movable lens barrel 36 toward the fixed lens barrel. 35c. Alternatively / further, it is provided with a plurality of elastic wires 301 that extend substantially parallel to the optical axis of the imaging lens 2 and are fixed to the movable lens barrel 36 and the fixed lens barrel.
According to said structure, it can be set as the lens drive device 3 which can respond to small shake with little friction further.

3) In the lens driving device 3, the attenuation means and the actuator are arranged on substantially the same plane substantially perpendicular to the optical axis. A plurality of attenuation means are provided in line symmetry or point symmetry with respect to the optical axis. In addition, when the attenuation means is projected onto a plane perpendicular to the optical axis, it is substantially circular. Attenuating means is provided between a cylindrical hole provided on the movable lens barrel 36 and a cylindrical hole or cylindrical shaft provided on the fixed lens barrel. A cylindrical hole provided on the movable lens barrel 36 is a hole that does not penetrate.
According to said structure, it can be set as the lens drive device 3 which reduced the influence of unnecessary resonance.

4) As shown in FIG. 6, the distance between the abutment portion of the movable lens barrel 36 and the fixed lens barrel for preventing overrun of the movable lens barrel 36 is a, and the movable mirror at the place where the attenuating means is provided. When the distance between the tube 36 and the fixed barrel is b, a <b is satisfied. Specifically, the distance between the abutment portion between the movable lens barrel 36 and the fixed lens barrel for preventing the overrun of the movable lens barrel 36 is a, and the movable lens barrel and the fixed lens barrel at the place where the attenuation means is provided. When the interval of b is b, a <0.5b is satisfied. Alternatively, when the distance between the movable barrel 36 and the fixed barrel provided with the attenuating means is b and the amount of movement of the movable barrel 36 in the controlled state is c, b> c is satisfied. . Specifically, when the distance between the movable lens barrel 36 and the fixed lens barrel where the attenuation means is provided is b, and the movement amount of the movable lens barrel in the control state is c, 0.5b> c is satisfied. ing.
According to said structure, it can be set as the lens drive device 3 which can prevent the plastic deformation of the attenuation | damping means which obtains viscous resistance.

5) A part or all of the attenuating means is in contact with the movable lens barrel 36 or the fixed lens barrel via a member that can transmit ultraviolet rays.
According to said structure, it can be set as the lens drive device 3 which can aim at the improvement of workability | operativity.

6) The attenuating means is composed of a gel mainly composed of silicone, an elastomer, or butyl rubber.
According to said structure, it can be set as the lens drive device 3 which comprises the attenuation means which consists of a suitable material.

7) The actuator included in the lens driving device 3 has an open control configuration.
According to said structure, it can be set as the lens drive device 3 with the frequency characteristic suitable for image blur correction with a simple structure.

  As is apparent from the above, when the lens driving device 3 having any one of the above configurations is used, the image blur correcting device and the imaging device 1 having good image blur correcting performance and good disturbance resistance performance can be obtained. It becomes possible.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Imaging lens 3 Lens drive device 6 Imaging element 8 Shake sensor 12 Correction lens 21 Image processing circuit 25 Camera system control circuit 30 Lens system control circuit 31 Base plate 32a, 32b, 32c Sphere 33a, 33b Coil 34a, 34b Magnet 35a, 35b, 35c Elastic body 36 Movable lens barrel 37 Magnet adsorption plate 44a, 44b Attenuating means mounting portion 45 Attenuating means 61 Angular velocity sensor 68 Lens position converter 69 Lens position controller 70 Motor driver 101 Magnet adsorption plate 102 Sensor 103 Attenuating means Mounting portion 104 Attenuating means 111 Lens position sensor 209 LED
210 Opposing yoke 215 Photo interrupter 217 PSD
218 Damping means mounting portion 219 Damping means 301 Elastic wire 302 Fixed yoke 310 Damping means mounting portion 311 Damping means

Claims (6)

An image blur correction device that corrects image blur by deflecting an optical axis,
A base member;
A holding member that holds a correction member for correcting image blur and is movable in a direction non-parallel to the optical axis with respect to the base member,
One of the base member and the holding member is formed with a hole that is closed on one side with an ultraviolet transmitting member,
The other of the base member or the holding member is formed with a shaft portion that is inserted into the hole portion from the side that is not blocked by the ultraviolet light transmitting member,
An image blur correction apparatus, wherein a gap between the shaft portion and the hole portion is filled with a viscoelastic body made of a material that is cured by irradiation with ultraviolet rays.   2. The shaft portion is inserted into the hole so as not to contact the ultraviolet transmitting member, and the viscoelastic body is filled between the shaft portion and the ultraviolet transmitting member. The image blur correction device described in 1.   The image blur correction apparatus according to claim 1, wherein the viscoelastic body is an ultraviolet curable silicone gel having a transition region in a band of 0.3 Hz to 100 Hz in a cured state.   The distance a by which the holding member can move with respect to the base member and the gap b between the shaft portion and the hole portion satisfy a relationship of a <b. 2. An image blur correction apparatus according to item 1.   An optical apparatus comprising the image blur correction device according to any one of claims 1 to 4.   An image pickup apparatus comprising the image blur correction apparatus according to claim 1.

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