JP2007318851A - Linear driver, lens driving device and camera shake arrester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a miniature linear driver for moving a moved body linearly through a simple arrangement, and to provide a lens driving device utilizing that linear driver and a camera shake arrester. <P>SOLUTION: The linear driver 7 comprises one piezoelectric unit 17a provided at one end 21a of a shaft member 21 and the other piezoelectric unit 17b provided at the other end 21b wherein each of the one and the other piezoelectric units 21a and 21b has one and the other piezoelectric elements 17a and 17b arranged oppositely, and a resilient body 19 held between the piezoelectric elements 17a and 17b, ends 21a and 21b of the shaft member 21 are secured to the resilient body 19, a power supply control section 27 applies pulse currents having reverse polarities and the same phase to the one and the other piezoelectric elements 17a and 17b and vibrates the resilient bodies 19 and 19 of the one and the other piezoelectric elements in the axial direction of the shaft member 21 thus moving the moved body 3 friction engaging with the side face of the shaft member 21 in the axial direction of the shaft member 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a linear driving device that linearly moves a moving object, a lens driving device that uses the moving object of the linear driving device as a lens holder, and a camera shake prevention device that uses the moving object of the linear driving device as an image sensor. .

  Patent Document 1 discloses a lens driving device that drives a lens holder in an optical axis direction by a linear motor including a magnet, a coil, and a yoke.

  Patent Document 2 discloses that positioning is performed by slightly deforming the end of the reflecting mirror by providing a piezoelectric element (piezoelectric element) at the end of the reflecting mirror and energizing the piezoelectric element.

Japanese Patent Laid-Open No. 2002-23037 JP 2000-121950 A

  However, in the technique of Patent Document 1, since a linear motor mechanism composed of a magnet, a coil, and the like is provided in the moving direction of the lens holder, there is a limit to downsizing the lens driving device.

  Patent Document 2 merely uses a piezo element to slightly deform the reflecting mirror, and the piezo element is limited to use within its movable range.

  On the other hand, there is a high demand for further miniaturization in linear drive devices used for lens driving and the like.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a small linear drive device that can move a moving object in a straight line with a simple configuration, a lens drive device using the linear drive device, and a camera shake prevention device for a camera.

  According to the first aspect of the present invention, the shaft member, one piezo unit provided at one end of the shaft member, the other piezo unit provided at the other end of the shaft member, and the side surface of the shaft member are frictionally engaged. Each of the piezo units has one and the other piezo elements disposed opposite to each other, and an elastic body sandwiched between the piezo elements, and the end of the shaft member. Is fixed to an elastic body, and the power supply control unit applies pulse currents of opposite polarity and the same phase to one and the other piezoelectric units, and each elastic body of the one and the other piezoelectric units is connected to the axis of the shaft member. The moving object that vibrates in the direction and frictionally engaged with the side surface of the shaft member is moved in the axial direction of the shaft member.

  According to a second aspect of the invention, in the first aspect of the invention, the elastic body is a conductive member, and when a relatively positive pulse current is applied to each piezo element with respect to the elastic body, the elastic body is moved in one direction. The body moves and moves to the other when a relatively negative pulse current is applied.

  The invention according to claim 3 is the invention according to claim 2, wherein the movable body has a spring member, and is frictionally engaged with the side surface of the shaft member by the elastic force of the spring member. To do.

  According to a fourth aspect of the present invention, the linear drive device according to any one of the first to third aspects of the present invention and a lens holder for holding a lens are provided, the movable body is a lens holder, and the shaft member is a lens. And a lens driving device that moves the lens held by the lens holder in the optical axis direction.

  The invention according to claim 5 includes the linear drive device according to any one of claims 1 to 3 and an image sensor disposed at the imaging position of the lens. The camera is a camera shake prevention device that is an image sensor and controls the position of the image sensor by driving a linear drive device in accordance with a change in the position of the image sensor.

  According to the first aspect of the present invention, when the power supply controller applies pulse currents having opposite polarities and opposite phases to the piezo units provided at both ends of the shaft member, in each piezo unit, one and the other piezo elements are Since the elastic body repeatedly expands and contracts relative to the elastic body, the elastic body sandwiched between one and the other piezoelectric elements vibrates between the one and the other piezoelectric elements, and one end of the shaft is fixed to the elastic body. Vibrates finely in the axial direction. The shaft member vibrates finely so that the side surface undulates by a pulse wave due to the vibration in the axial direction, and a moving body frictionally engaged with the side surface of the shaft member linearly moves the shaft member in the axial direction.

  Since the piezo units provided at both ends of the shaft member respectively vibrate the shaft members in the same direction, the pulse wave generated on the side surface of the shaft member becomes a pulse wave having an amplitude that is synergistically amplified by the piezo units provided at both ends, A large driving force (torque) can be obtained as compared with the case where the piezo unit is provided only at one end of the shaft member.

  Since a large driving force can be obtained in the present invention, the degree of freedom of the weight of the moving object is high and the applicable range of the moving object can be widened.

  When an experiment was conducted on the case where the piezo unit was provided only at one end of the shaft member, the object to be moved moved smoothly in the axial direction of the shaft member. This is because the vibration of the pulse wave generated on the side surface of the shaft member is very fine, so the non-contact area is small at the frictional engagement part with the moving object, and between the moving object and the shaft member during movement. It is considered that the frictional force acting on the surface of the moving object was reduced, and the moving object was able to move smoothly on the surface of the shaft member by being pushed by the pulse wave (traveling wave). Therefore, if the amplitude of the pulse wave generated on the side surface of the shaft member can be increased, a large driving force proportional to the amplitude can be obtained.

  According to the linear drive device of the present invention, since the configuration includes only a piezo element, an elastic body, a shaft member, and a movable body frictionally engaged with the shaft member, a magnet, a coil, or the like such as a linear motor mechanism is provided. It becomes unnecessary and can be made simple and extremely small.

  According to the second aspect of the present invention, the function and effect of the first aspect can be obtained, and the moving object can be moved in the axial direction of the shaft member only by changing the direction of the pulse current supplied to each piezo unit. Can be reciprocated.

  According to the third aspect of the invention, the effect of the second aspect is achieved and the moving body is pressed against the surface of the shaft member by the spring, so that the spring member responds to the pulse vibration on the surface of the shaft member. It is easy to resonate, and the contact area between the surface of the shaft member and the movable body during movement of the movable body is reduced, so that smoother movement can be achieved.

  According to the invention described in claim 4, it is possible to obtain a lens driving device that exhibits the operational effects described in any one of claims 1 to 3. In particular, by using the lens for driving a focus lens and a magnification lens, it is possible to provide a camera having a simpler and smaller autofocus and magnification function than conventional ones.

  According to the fifth aspect of the present invention, the camera shake prevention device for the camera that achieves the operational effects of any one of the first to third aspects can be simplified and reduced in size.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing the lens driving device according to the first embodiment cut along the AA position in FIG. 3, and FIG. 2 shows the lens driving device according to the first embodiment in FIG. FIG. 3 is a cross-sectional view showing the lens driving device according to the first embodiment cut at the position B, and FIG. 4 is a cross-sectional view showing the lens driving device taken along the line CC in FIG. It is sectional drawing which showed schematic structure, FIG. 5 is a figure of the linear drive device concerning 1st Embodiment, (a) is EE sectional drawing shown in (b), (b) is a front view. 6 is a waveform of the pulse current supplied to the piezo unit by the power supply control unit, (a) is a waveform diagram of the pulse current supplied to one piezo unit, and (b) is a pulse supplied to the other piezo unit. FIG. 7 is a waveform diagram of current, and FIG. 7 shows a state of a pulse wave generated on the side surface of the drive shaft (shaft member). It is a diagram for explaining.

  A lens driving device 1 according to the first embodiment is used for a digital camera 2 incorporated in a mobile phone, and is a lens driving device for an autofocus digital camera with an optical zoom.

  As shown in FIGS. 1 and 2, the lens driving device 1 includes a first lens holder (movable body) 3, a second lens holder (movable body) 5, and a first linear that drives the first lens holder 3. A driving device 7 and a second linear driving device 9 for driving the second lens holder 5 are provided.

  The first lens holder 3 holds an optical zoom lens 14 in the present embodiment, the second lens holder 5 holds a focus lens 16, and the optical zoom lens 14 and the focus lens 16 are optical axes. And the image sensor 11 is provided at the conjugation position on the optical axis. The image sensor 11 is provided with a camera shake preventing apparatus 10 according to the second embodiment of the present invention. The camera shake preventing apparatus 10 will be described later.

  Since the first linear drive device 7 and the second linear drive device 9 have substantially the same configuration, the first linear drive device 7 will be described, and the second linear drive device 9 has the same parts that have the same effects. The description of the part is abbreviate | omitted by attaching | subjecting a code | symbol.

  The first linear drive device 7 includes a drive shaft (shaft member) 21, one piezo unit 22 provided at one end of the drive shaft 21, and the other piezo unit 24 provided at the other end of the drive shaft 21. And a power supply control unit 27 (see FIG. 4).

  One piezo unit 22 is fixed to the base 15 of the housing 13, the other piezo unit 24 is fixed to the front wall 18 disposed opposite the base 15, and the drive shaft 21 is connected to the base 15 and the front wall 18. The first lens holder (movable body) 3 is frictionally engaged with the side surface of the drive shaft 21. The base 15 side is the optical zoom magnification side, and the front wall 18 side is the optical zoom telephoto side.

  The one and other piezo units 22 and 24 have one and the other piezo elements 17a and 17b arranged opposite to each other, and a vibrator (elastic body) 19 arranged between the piezo elements 17a and 17b. One end 21 a of the drive shaft 21 is fixed to the vibrator 19 of one piezo unit 22, and the other end 21 b is fixed to the vibrator 19 of the other piezo unit 24.

  The vibrator 19 is a copper plate, and as shown in FIG. 4, a power supply control unit 27 is connected to one and the other piezoelectric elements 17 a and 17 b of the piezoelectric units 22 and 24 and the vibrator 19. As shown in FIG. 6, the power supply control unit 27 applies pulse currents having opposite polarities and the same phase to the one and other piezoelectric units 22 and 24, and the vibrators 19 of the one and other piezoelectric units 22 and 24. Is moved in the axial direction of the shaft member 21, and the first lens holder (movable body) 3 that is frictionally engaged with the side surface of the shaft member 21 is moved in the axial direction of the shaft member 21.

  A pulse current having the same polarity and the same phase is applied to the piezo elements 17 a and 17 b constituting the piezo units 22 and 24, and the piezo elements 17 a and 17 b are relatively positive or negative with respect to the vibrator 19. The pulse current is applied.

  The first lens holder 3 has a friction engagement portion 31 with the drive shaft 21 at one end, and the friction engagement portion 31 is made of a spring member. As shown in FIG. It is sandwiched by force to give a frictional force.

  An engaging portion 33 with the auxiliary shaft 35 is provided at the other end of the first lens holder 3, and the engaging portion 33 is parallel to the drive shaft 21 between the base 15 of the housing 13 and the front wall 18. The movement of the first lens holder 3 is guided by engaging with the auxiliary shaft 35 erected.

  Next, operations and effects of the embodiment according to the present invention will be described.

  In the present embodiment, the first lens holder 3 is moved to change the magnification by optical zoom, and the second lens holder is simultaneously moved to adjust the focal position.

  When the first lens holder 3 is moved to the telephoto side (front side), in one piezo unit 22, the vibrator 19 is set to 0 volts and the piezo elements 17a and 17b are respectively shown in FIG. 6A. Apply a positive pulse current of the waveform. In the other piezo unit 24, as shown in FIG. 6 (b), a current having the same polarity and opposite polarity as that of the one piezo unit 22 is applied (the piezo elements 17a and 17b are set to 0 volt, relative to the vibrator 19). Negative pulse current).

  In one piezo unit 22, since a positive pulse current is applied to the piezo elements 17a and 17b, the piezo elements 17a and 17b repeatedly expand (expand the volume) and then return to the original state. A certain vibrator 19 vibrates. Due to the vibration of the vibrator 19, a traveling wave traveling in one direction with an amplitude S 1 is generated on the side surface of the drive shaft 21 shown in FIG. 7A as shown in FIG. 7B.

  In the other piezoelectric unit 24, a relatively negative pulse current is applied to the piezoelectric elements 17a and 17b in the same phase as the current applied to the one piezoelectric unit 22, so that the piezoelectric elements 17a and 17b are contracted (volume reduced). (Reduction) Next, returning to the original state is repeated, and the vibration of the vibrator 19 between the piezo elements 17a and 17b oscillates. On the side surface of the drive shaft 21, as shown in FIG. A traveling wave that travels is generated.

  As a result, on the side surface of the drive shaft 21 shown in FIG. 7A, as shown in FIG. 7D, the traveling waves in FIG. 7B and FIG. A traveling wave is generated which travels in one direction (forward) with an amplitude S3 having a magnitude obtained by adding the amplitudes S1 and S2.

  Therefore, according to the present embodiment, it is possible to obtain a traveling wave having a large amplitude by adding up the amplitudes of vibrations generated in one piezo unit 22 and the other piezo unit 24, and driving torque is applied only to one piezo unit. As compared with the case, it can be substantially doubled.

  In the present embodiment, smooth movement can be achieved when the voltage V shown in FIG. 6 is several tens of volts and the frequency H is several tens of KHz. In the experiment, when the voltage V in each of the piezo units 22 and 24 was 35 V and the frequency H was 56 KHz, a movement of 22 mm / sec could be obtained with a sliding torque of 60 g · f. In addition, when only one piezo unit 22 was provided on the drive shaft 21 and the other end of the drive shaft 21 was a free end, a comparative experiment was performed under the same conditions. The moving speed was 20 mm / second and the sliding torque was 35 g · f. It was.

  When the first lens holder 3 is moved to the enlargement side (rear side), the polarity of the voltage in each piezo unit 22, 24 is switched, and in one piezo unit 22, the vibrator 19 is connected to the piezo elements 17, 17. Is set to 0 volts, a relatively negative pulse current is applied to the vibrator 19. In the other piezoelectric unit 24, the vibrator 19 is set to 0 volts on the piezoelectric elements 17, 17 and the vibrator 19 is relatively placed. Apply a positive pulse current. Thereby, on the side surface of the drive shaft 21, a wavy vibration is generated in the direction opposite to the traveling wave of FIG. 7D with the amplitude shown in FIG. 7D, and the first lens holder 3 It moves toward the one end 21a (to the rear side).

  On the other hand, in the friction engagement portion 31, when the side surface of the frictionally engaging drive shaft 21 vibrates, the engagement surface of the friction engagement portion 31 made of a spring also vibrates in the same manner as the side surface of the drive shaft 21. Since the frictional contact area is reduced, it can move smoothly with a small frictional force during movement.

  Similarly to the first lens holder 3, the second lens holder 5 is driven by supplying a predetermined pulse current between the piezo elements 17, 17 and the vibrator 19 to move the second lens holder forward or backward. be able to.

  According to the present embodiment, the linear drive devices 7 and 9 for moving the first and second lens holders 3 and 5 are only one and the other piezoelectric elements 17a and 17b, the vibrator 19, and the drive shaft 21. Therefore, since a magnet, a yoke, a coil, and the like as in the conventional linear motor mechanism are unnecessary, it is simple and can be made extremely small.

  In particular, since one and the other piezo units 22 and 24 are provided at both ends of the drive shaft 21, there is no drive mechanism around the first and second lens holders 3 and 5, so the width of the lens in the aperture direction is reduced. can do.

  Further, since the first and second lens holders 3 and 5 are supported by the auxiliary shaft 35, the lens holders 3 and 5 can be moved stably.

  In the present embodiment, the pulse wave generated on the side surface of the drive shaft 21 becomes a pulse wave having an amplitude that is synergistically amplified by the piezo units 22 and 24 provided at both ends of the drive shaft 21. A large driving force (torque) can be obtained as compared with the case where only the piezo unit is provided.

  Other embodiments of the present invention will be described below. In the other embodiments described below, the same reference numerals are given to the portions having the same operational effects as those of the first embodiment described above. Therefore, the detailed description of that part is omitted.

  FIG. 8 shows a second embodiment. In the second embodiment, the first linear drive device 7 and the second linear drive device 9 are used as the camera shake prevention device 10 of the camera. That is, the image sensor 11 shown in FIG. 1 is slidably held in one direction (X direction) with respect to the support 43, and the support 43 has one and the other piezoelectric units 22 of the first linear drive device 7. , 24 are fixed, and the drive shaft 21 is disposed along the X direction along one side edge of the image sensor 11. In addition, one and the other piezoelectric units 22 and 24 of the second linear drive device 9 are fixed to the camera casing 13, and the drive shaft 21 is arranged in the Y direction along the other side edge of the image sensor 11. The support member 43 is moved in the Y direction.

  In the second embodiment, the power supply control unit 27 is similar to the first embodiment described above for the first and second linear drive devices 9 and 11 in accordance with the amount of position fluctuation of the image sensor 11 caused by camera shake. 6 is applied and driven to prevent image blur due to camera shake or the like.

  According to the second embodiment, since the linear drive devices 7 and 9 using the vibrations of the piezo units 22 and 24 are used in the shake preventing device 10 that has been conventionally driven and controlled by a motor, the shake preventing device 10 is used. It is possible to reduce the size with a simple configuration.

  In each of the first and second linear drive devices 7 and 9, a substantially double drive torque can be obtained at a predetermined voltage, so that the image sensor 11 can be driven quickly and position correction such as camera shake can be performed quickly. it can.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, in each of the piezo units 22 and 24, one and the other piezo elements 17a and 17b may be formed by laminating a plurality of sheets. By laminating a plurality of piezo elements in this manner, the amplitude of vibration generated on the side surface of the drive shaft (shaft member) can be further increased, so that a larger driving force can be obtained.

  In the above-described embodiment, the lens driving device and the camera shake prevention device mounted on the mobile phone have been described as examples. However, the camera may be used as a lens driving device for a digital still camera or a camera shake prevention device.

  The moving object is not limited to the lens holders 3 and 5 and the image sensor 11 described above, and the use thereof is not particularly limited as long as it moves linearly.

It is sectional drawing which cut | disconnects and shows the lens drive device concerning 1st Embodiment in the AA position of FIG. FIG. 4 is a cross-sectional view showing the lens driving device according to the first embodiment cut at a position BB in FIG. 3. It is sectional drawing which cut | disconnects and shows the lens drive device concerning 1st Embodiment in CC position of FIG. It is sectional drawing which showed schematic structure of the linear drive device. It is a figure of the linear drive device concerning a 1st embodiment, (a) is an EE sectional view shown in (b), and (b) is a front view. It is a waveform of the pulse current supplied to the piezo unit by the power supply control unit, (a) is a waveform diagram of the pulse current supplied to one piezo unit, (b) is a waveform diagram of the pulse current supplied to the other piezo unit. is there. It is a figure explaining the state of the pulse wave which generate | occur | produces in the side surface of a drive shaft (shaft member). It is a front view which shows the structure of the camera-shake prevention apparatus concerning 2nd Embodiment.

DESCRIPTION OF SYMBOLS 1 Lens drive device 3 1st lens holder (moving body)
5 Second lens holder (movable body)
7 first linear drive device 9 second linear drive device 10 camera shake prevention device 13 housing 17a one piezo element 17b other piezo element 19 vibrator (elastic body)
21 Drive shaft (shaft member)
21a One end 21b Other end 22 One piezo unit 24 The other piezo unit

Claims (5)

  A shaft member, one piezo unit provided at one end of the shaft member, the other piezo unit provided at the other end of the shaft member, a movable body frictionally engaged with a side surface of the shaft member, and a power control unit The one and the other piezo units each have one and the other piezo elements arranged opposite to each other, and an elastic body sandwiched between the piezo elements, and the end of the shaft member is fixed to the elastic body The power supply control unit applies pulse currents having opposite polarities and the same phase to one and the other piezo units to vibrate the elastic bodies of the one and the other piezo units in the axial direction of the shaft member. A linear drive device characterized by moving a moving body frictionally engaged with the shaft in the axial direction of the shaft member.   The elastic body is a conductive member. When a relatively positive pulse current is applied to each piezoelectric element relative to the elastic body, the moved body moves in one direction, and when a relatively negative pulse current is applied, it moves to the other. The linear drive device according to claim 1, wherein:   The linear drive device according to claim 2, wherein the movable body includes a spring member and is frictionally engaged with a side surface of the shaft member by an elastic force of the spring member.   A linear drive device according to any one of claims 1 to 3 and a lens holder that holds a lens are provided, the movable body is a lens holder, and the shaft member is provided along the optical axis of the lens. A lens driving device that moves the lens held by the lens holder in the optical axis direction. A linear drive device according to any one of claims 1 to 3 and an image sensor disposed at an image forming position of a lens, wherein the movable body of the linear drive device is an image sensor, and the position of the image sensor An apparatus for preventing camera shake, wherein the position of the image sensor is controlled by driving a linear driving device in accordance with fluctuation.

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