JP2009011072A - Drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a drive device capable of stably driving a lens barrel without adjusting the position of an oscillation body to the lens barrel. <P>SOLUTION: This drive device includes an elastic member 2 which oscillates in an arc form and a drive source which oscillates the elastic member 2. The elastic member 2 has a friction member 3 which can be brought into contact with a driven body, and the friction member 3 moves in an arc form trace to drive the lens barrel 4 in accordance with the arc form oscillation of the elastic member 2. When curvature radius of the arc form friction member 3 is taken as r and radius of the arc form trace of a contact part is taken as driving radius D, the curvature radius r and the driving radius D satisfy the condition of 0.5≤r/D≤1.5, therefore, it is possible to stably drive the lens barrel 4 even when the elastic member 2 is mounted to be slant to the lens barrel 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive device provided with a drive mechanism for driving a driven body.

  Conventionally, a driving device for driving a driven body using an electromechanical conversion element (piezoelectric element) has been proposed. Such a driving device is used for driving a lens in an optical device such as a photographing lens of a camera.

Regarding a conventional driving device, for example, Patent Document 1 includes a vibrating body having a pair of excitation parts (piezoelectric elements) and a contact part that comes into contact with a driven body, and the vibrating body alternately and repeatedly applies voltage to the pair of excitation parts. A driving device is disclosed in which a bending displacement is applied by applying and a driven body is driven through a contact portion by the bending displacement. In the drive device disclosed in the cited document 1, the contact portion has a substantially semicircular shape so that the contact portion can stably come into frictional contact with the driven body.
Japanese Patent Laying-Open No. 2005-102368 (published on April 14, 2005)

  However, in the conventional driving device disclosed in Patent Document 1, when the vibrating body is attached to the driven body with an inclination, the force by which the contact portion of the vibrating body pushes the driven body changes due to the inclination. End up. For this reason, in the conventional drive device, the problem that a to-be-driven body cannot be driven stably arises.

  The above-described problem relating to the conventional drive device will be specifically described with reference to FIGS. 15 and 16. FIG. 15 is an explanatory diagram for explaining a problem of a conventional driving device, and shows a state in which a vibrating body is ideally attached to a driven body. FIG. 16 is an explanatory diagram for explaining a problem of a conventional drive device, and shows a state in which a vibrating body is attached to be inclined with respect to a driven body.

  As shown in FIG. 15, when the vibrating body 21 is ideally attached to the driving direction of the lens barrel (driven body) 4, the friction member (contact portion) 3 is caused by the bending displacement of the vibrating body 21. It is driven by drawing a locus indicated by a broken line, and comes into contact with the lens barrel 4. That is, the driving locus of the friction member 3 passes through the contact portion 4a of the friction member 3 in the lens barrel 4 and is symmetric with respect to the perpendicular L0 perpendicular to the contact surface with the friction member 3. The contact of the friction member 3 causes the same force to act on the lens barrel 4 in the direction along the contact surface with the friction member 3 indicated by a solid line. Thereby, the lens barrel 4 is driven with the same displacement in both directions of the A side and the B side shown in FIG.

  On the other hand, as shown in FIG. 16, when the vibrating body 21 is attached to be inclined with respect to the driving direction of the lens barrel 4, the friction member 3 draws a locus indicated by a broken line due to the bending displacement of the vibrating body 21. To contact the lens barrel 4. That is, the driving locus of the friction member 3 is asymmetric with respect to the perpendicular L0. Then, due to the contact of the friction member 3, a force acts on the lens barrel 4 in a direction intersecting the contact surface with the friction member 3 indicated by a solid line. Therefore, when the lens barrel 4 is driven in the A side direction, the friction member 3 is driven while pressing the lens barrel 4. On the other hand, when the lens barrel 4 is driven in the direction of the B side, the friction member 3 is driven away from the lens barrel 4. For this reason, in the drive device shown in FIG. 16, the friction member 3 and the lens barrel 4 are driven in the case where the lens barrel 4 is driven in the A side direction and in the case where the lens barrel 4 is driven in the B side direction. The contact state will vary greatly.

  Therefore, as shown in FIG. 16, when the vibrating body 21 is attached to be inclined with respect to the lens barrel 4, the contact state between the friction member 3 and the lens barrel 4 changes depending on the direction in which the lens barrel 4 is driven. As a result, the lens barrel 4 cannot be stably driven.

  Therefore, in order to drive the lens barrel 4 stably, it is necessary to adjust the position of the vibrating body 21 so as to be substantially parallel to the driving direction of the lens barrel 4 when the drive device is assembled. Therefore, in the conventional driving device, the number of assembling steps of the driving device is excessively increased by the position adjustment of the vibrating body 21, leading to an increase in the cost of the driving device.

  The present invention has been made in view of the above problems, and its purpose is to easily adjust the position of the vibrating body with respect to the lens barrel, and even if the vibrating body is tilted and attached to the lens barrel, An object of the present invention is to realize a driving apparatus capable of stably driving a lens barrel.

In order to solve the above-described problem, a drive device according to the present invention includes a vibrating body that vibrates in an arc shape and a drive source that vibrates the vibrating body, and the vibrating body can contact the driven body. A driving device having a contact portion, wherein the contact portion is configured to drive a driven body while drawing an arc-shaped trajectory with the arc-shaped vibration of the vibrating body;
The contact portion has a circular shape, and when the radius of curvature of the circular shape is r and the radius of the arc-shaped locus of the contact portion is a drive radius D, the curvature radius r and the drive radius D satisfy the following conditions: 0.5 ≦ r / D ≦ 1.5
It is characterized by satisfying.

  The drive device according to the present invention includes a vibrating body that vibrates in an arc shape and a drive source that vibrates the vibrating body, and the vibrating body includes a contact portion that can contact the driven body, and the contact portion However, along with the arc-shaped vibration of the vibrating body, the driven body is driven by drawing an arc-shaped locus.

  In such a driving apparatus, when the vibrating body is attached to the driven body at an inclination, the contact state between the contact portion and the driven body changes depending on the direction in which the driven body is driven, and the driven body is driven. There is a problem that the body cannot be driven stably.

  Therefore, as a result of intensive studies, the present inventors have made the shape of the contact portion circular, and the ratio of the radius of curvature r of this circular shape to the radius (drive radius) D of the arcuate locus of the contact portion is set to 0. It has been found that by setting within the range of 5 ≦ r / D ≦ 1.5, the amount of change in the position of the side surface during driving of the driven body can be minimized and stable driving of the driven body can be realized.

Therefore, according to the driving device of the present invention, the curvature radius r and the driving radius D satisfy the following condition 0.5 ≦ r / D ≦ 1.5.
By satisfying the configuration, even if the vibrating body is mounted at an angle of 0.4 ° with respect to the driven body, the amount of change in the position of the side surface during driving of the driven body is minimized and the driven body is stabilized. Can be driven automatically.

In the driving apparatus according to the present invention, the curvature radius r and the driving radius D satisfy the following condition 0.9 ≦ r / D ≦ 1.1.
It is preferable to satisfy.

  With the above configuration, even if the vibrating body is mounted at an angle of 2.5 ° with respect to the driven body, the amount of change in the position of the side surface during driving of the driven body is minimized and the driven body is driven stably. It becomes possible to make it.

In the driving apparatus according to the present invention, the radius of curvature r and the driving radius D satisfy the following condition: r = D
It is preferable to satisfy.

  With the above configuration, no matter what angle the vibrating body is attached to the driven body, the amount of change in the position of the side surface during driving of the driven body is minimized, and the driven body is stably It becomes possible to drive.

  In the drive device according to the present invention, it is preferable that the contact portion is constituted by a friction member that frictionally engages the driven body.

  According to the above configuration, the contact portion is configured by the friction member that frictionally engages with the driven body. Therefore, the friction member has a friction coefficient that is optimal for driving the driven body. By selecting the material, the driven body can be driven stably.

  In the drive device according to the present invention, the vibrating body includes a vibration base material that vibrates by the drive source and the friction member, and the friction member has a spherical or cylindrical shape and is bonded to the vibration base material. It is preferable that

  According to the above configuration, the friction member is bonded to the vibration base material, and the shape thereof is a sphere or a columnar shape, so the ratio r / D = 0.5 between the curvature radius r and the drive radius D is obtained. . Therefore, even if the vibrating body is mounted with an inclination of 0.4 ° with respect to the driven body, the amount of change in the position of the side surface during driving of the driven body is minimized and the driven body is driven stably. Is possible.

  In the drive device according to the present invention, it is preferable that the vibration base material is formed with a recess capable of accommodating the friction member.

  According to the above configuration, the friction member is housed and bonded to the hollow portion of the vibration base material, and the shape thereof is a sphere or a columnar shape. Therefore, the ratio r / D between the curvature radius r and the drive radius D is set to It can be set to 0.5 or more. Therefore, even if the vibrating body is attached with an inclination of 0.4 ° or more with respect to the driven body, the positional change amount of the side surface during driving of the driven body is minimized, and the driven body is driven stably. It becomes possible.

In the drive device according to the present invention, as described above, the contact portion has a circular shape, the radius of curvature of the circular shape is r, and the radius of the arc-shaped locus of the contact portion is the drive radius D. The radius of curvature r and the driving radius D satisfy the following conditions: 0.5 ≦ r / D ≦ 1.5
It is the composition which satisfies.

  Therefore, even if the vibrating body is inclined with respect to the driven body, the amount of change in the position of the side surface during driving of the driven body can be minimized and the driven body can be driven stably. .

[First Embodiment]
The present invention relates to a driving device used for driving a lens in an optical device such as a photographing lens of a camera, for example.

  An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing a configuration of a driving device (hereinafter referred to as the present driving device) of the present embodiment. The driving device shown in FIG. 1 shows an optimal embodiment applied to a focus adjustment mechanism of a small camera module.

  First, as shown in FIG. 1, the driving device includes a bending displacement member 1 </ b> A / 1 </ b> B, an elastic member (vibrating base material, vibrating body) 2, a friction member (vibrating body, contact portion) 3, a lens barrel ( Driven body) 4, guide shaft 5, camera module housing 6, and drive circuits (control means) 7A and 7B.

  In the present drive device, the elastic member 2 connects the bending displacement member 1A and the bending displacement member 1B. The elastic member 2 is connected to a friction member 3 that frictionally engages the lens barrel 4.

  The “drive direction changing member (vibrating body)” refers to a member composed of the elastic member 2 and the friction member 3. In this drive device, the elastic member 2 and the friction member 3 are shown as separate members. However, in the present invention, the drive direction changing member is not limited to the configuration in which the elastic member 2 and the friction member 3 are separate members.

  The bending displacement members 1A and 1B are bimorph piezoelectric elements having a three-layer structure in which two piezoelectric material layers 22X and 22Y are pressure-bonded with a shim interposed therebetween. As shown in FIG. 1, one end of the bending displacement members 1 </ b> A and 1 </ b> B (extension of shim material in the present embodiment) is fixed to the camera module housing 6 by adhesion or fitting. The other end is connected to the elastic member 2.

  The elastic member 2 is made of a material having a relatively low elastic modulus such as metal or resin. In the present drive device, the lens barrel 4 is moved in the optical axis direction when the friction member 3 comes into contact (friction engagement) with the lens barrel 4. Therefore, the material of the friction member 3 includes metal, resin, carbon and the like, and is selected according to a desired coefficient of friction with the lens barrel 4.

  Further, the drive device is provided with a guide shaft 5 for guiding the movement of the lens barrel 4 in the optical axis direction. The lens barrel 4 is provided with a hole through which the guide shaft 5 is inserted. The guide shaft 5 is a rod-like body extending in the optical axis direction, and is fixed to the bottom (or ceiling) of the camera module housing 6. Further, the guide shaft 5 has a role of supporting the lens barrel 4 so that the lens barrel 4 is positioned at a position where the friction member 3 and the lens barrel 4 are in contact (friction engagement). In the present drive device, the lens barrel 4 is moved along the guide shaft 5 in the optical axis direction by frictional engagement between the friction member 3 and the lens barrel 4. In the present driving device, the lens barrel 4 is not limited to one that is formed integrally with the hole through which the guide shaft 5 is inserted. The hole member including the hole portion may be separately bonded to the lens barrel. Further, the lens barrel 4 may have a configuration in which a friction adjustment member for obtaining a desired friction coefficient is connected (or attached) to a friction engagement portion with the friction member 3. That is, here, the lens barrel including the configuration including the hole member or the friction adjusting member is referred to as a lens barrel.

  The bending displacement members 1A and 1B are connected to the drive circuits 7A and 7B, respectively. The drive circuit 7A excites the bending displacement of the bending displacement member 1A by applying a voltage or the like to the bending displacement member 1A. The drive circuit 7B excites the bending displacement of the bending displacement member 1B by applying a voltage or the like to the bending displacement member 1B. The drive circuits 7A and 7B are controlled by an upper control circuit (not shown), and output a voltage corresponding to a drive waveform described later to the bending displacement members 1A and 1B. The “control means” refers to a device provided with the drive circuits 7A and 7B and a higher-level control circuit.

  Note that the electrical control of the bending displacement of the bending displacement members 1A and 1B by the control means is not limited to the voltage control. For example, when a bimetal or a shape memory alloy is used as the bending displacement members 1A and 1B and the bending displacement is excited by heat, the electrical control of the bending displacement of the bending displacement members 1A and 1B is control by increasing or decreasing the current. . In this case, the temperature of the bending displacement members 1A and 1B is controlled by controlling the heat generated by a part of the bending displacement members 1A and 1B by increasing and decreasing the current flowing through the bending displacement members 1A and 1B. Alternatively, a heat generating means for generating heat by supplying a current composed of a heating wire such as a nichrome wire or a Kanthal wire is provided close to the bending displacement members 1A and 1B, and by increasing or decreasing the current flowing to the heat generating means The temperature of the bending displacement members 1A and 1B is controlled by controlling the heat generated by the heat generating means. In addition, for example, when a magnetostrictive element is used as the bending displacement member 1A or 1B and the bending displacement is excited by a magnetic field, a magnetic field generating means for generating a magnetic field by passing an electric current such as an electromagnet is provided to control increase / decrease of the current. Thus, the magnetic field applied to the bending displacement members 1A and 1B is controlled.

  Although not shown in FIG. 1, an optical component such as a lens is fitted in the lens barrel 4, and an imaging element such as a CCD is disposed at the bottom of the lens barrel 4.

  In the present driving device, the lens barrel 4 is driven along the guide shaft 5 by a driving mechanism including the bending displacement members 1 </ b> A and 1 </ b> B, the elastic member 2, and the friction member 3. As a result, the optical component fitted in the lens barrel 4 is driven in the optical axis direction, and focus adjustment is performed. In the present embodiment, the driven body moving direction in which the lens barrel 4 moves is treated as a synonym for the optical axis direction. In this specification, the direction in which the optical component fitted in the lens barrel 4 forms an object (the direction of a straight line connecting the lens barrel 4 and the object) is referred to as an “optical axis direction”.

  Next, the bending displacement members 1A and 1B in which the bending displacement is excited by electrical control will be described. As an example of the bending displacement members 1A and 1B, for example, a piezoelectric element having a bimorph structure shown in FIGS. FIG. 2 shows a configuration of a piezoelectric element having a bimorph structure, FIG. 2 (a) is a side view, and FIG. 2 (b) is a diagram showing a bending displacement of the piezoelectric element.

  The piezoelectric element shown in FIGS. 2A and 2B includes two piezoelectric material layers 22X and 22Y generally made of ceramics and the like, and a shim material (vibrating plate) 21 made of metal, and two piezoelectric elements. The material layers 22X and 22Y have a three-layer structure in which the shim material 21 is sandwiched between them. The two electrodes 20X and 20Y sandwich the three-layer structure. The two electrodes 20X and 20Y are connected to a control means (not shown). Then, one end of the shim material 21 is fixedly supported (“fixed point” indicated by a black triangle mark in FIGS. 2A and 2B). 2A and 2B, the stacking direction of the three-layer structure including the piezoelectric material layers 22X and 22Y and the shim material 21 is the thickness direction. Further, in the thickness direction, the piezoelectric material layer 22X side is the X side, and the piezoelectric material layer 22Y side is the Y side.

  In the piezoelectric elements shown in FIGS. 2A and 2B, when a voltage is applied from the control means to the electrodes 20X and 20Y, the piezoelectric elements are bent and displaced in the thickness direction.

  For example, the piezoelectric material layer 22X shrinks when the voltage between the electrode 20X and the shim material 21 becomes positive, and expands when the voltage between the electrode 20X and the shim material 21 becomes negative. Is polarized. Further, the piezoelectric material layer 22Y expands when the voltage between the electrode 20Y and the shim material 21 becomes positive, and contracts when the voltage between the electrode 20Y and the shim material 21 becomes negative. Is polarized.

  A case where the control means applies a voltage to the piezoelectric material layers 22X and 22Y polarized as described above will be described. As shown in FIG. 2 (c), the control means applies a positive voltage between the electrodes 20X and 20Y and the shim material 21 (between the arrows in FIG. 2 (c)). Yes. And the part shown by the black triangle mark in the shim material 21 is being fixed. In this case, as shown in the figure, the piezoelectric element is bent and displaced in the thickness direction X side. On the other hand, although not shown, when the control means applies a negative voltage between the arrows, the piezoelectric element is bent and displaced in the thickness direction Y side.

  As described above, the piezoelectric element shown in FIGS. 2A and 2B is bent and displaced by voltage application by the control means. The bending displacement member in the driving device of the present invention is not limited to the piezoelectric element shown in FIGS. 2A and 2B, and has a structure capable of controlling the bending displacement by electrical control. If it is. For example, as the bending displacement member, a monomorph structure piezoelectric element composed of one piezoelectric material layer and a shim material can be cited. The monomorph structure piezoelectric element can be flexibly displaced by electrical control with the same operation concept as the bimorph structure piezoelectric element.

  As described above, the bending displacement member in the drive device of the present invention refers to a member that is bent and displaced by electrical control such as application of voltage, and of course, its structure and dimensions and shape such as thickness, length, and width. Is not limited to.

  Hereinafter, in order to simplify the description, a bending displacement member whose bending displacement is excited by electrical control is simply referred to as a “bending displacement member”.

  Further, in this specification, when the bending displacement member is disposed in the driving device, the moving direction of the driven body is referred to as the driven body moving direction or the width direction (of the bending displacement member), and the bending displacement member is bent. Direction to be bent is referred to as a bending direction or a thickness direction (of the bending displacement member), and a direction perpendicular to the driven body movement direction (the width direction) and orthogonal to the bending direction (thickness direction) is the length direction (of the bending displacement member) Call it. This is not affected by the size of the bending displacement member or the position of the fixing portion of the bending displacement member.

  A camera module housing 6 shown in FIG. 1 is a member that accommodates the bending displacement members 1A and 1B, the elastic member 2, the friction member 3, the lens barrel 4, and the guide shaft 5. In the present drive device, the camera module housing 6 has a rectangular parallelepiped shape and includes side walls 6a to 6d. As shown in FIG. 3, the bending displacement members 1 </ b> A and 1 </ b> B are disposed along the side walls 6 c and 6 d of the camera module housing 6. In addition, the bending displacement members 1A and 1B include any one point on the bending displacement member 1A (for example, point S shown in FIG. 3) and any one point on the bending displacement member 1B (for example, shown in FIG. 3). Are arranged so that there is at least one straight line passing through the lens barrel 4 (for example, a straight line connecting the S point and the T point). Further, the elastic member 2 and the friction member 3 are arranged at a corner portion formed by the bending displacement members 1A and 1B.

  As described above, in the present driving device, the bending displacement members 1A and 1B are arranged along the side wall of the camera module housing 6, and the elastic member 2 and the friction member 3 are arranged at the corner portion having a spatial margin. The space in the camera module housing 6 can be effectively used for the arrangement of the drive mechanism, and the drive device can be downsized.

  In this drive device, the bending displacement members 1A and 1B, the elastic member 2, and the friction member 3 are arranged so that the lens barrel 4 is driven in a direction perpendicular to the bending displacement direction of the bending displacement members 1A and 1B. Hereinafter, the positional relationship between the bending displacement members 1A and 1B, the elastic member 2, and the friction member 3 and the principle of driving operation of the lens barrel 4 in the present driving device will be described.

(Position relationship)
FIG. 3A is a side view showing the positional relationship among the bending displacement members 1A and 1B, the elastic member 2, and the friction member 3 in the present driving device. FIG. 3B is a plan view showing the configuration of the present driving device. In FIG. 3A, a point where the bending displacement member 1A and the elastic member 2 are connected is a connection point A (indicated by X in the drawing), and a point where the bending displacement member 1B and the elastic member 2 are connected is shown. The connecting point B (shown by X in the figure) is shown. A line passing through the centers of the bending displacement members 1A and 1B and parallel to the length direction is defined as a virtual line (first straight line) L1. The imaginary line L1 passes through the friction member 3. Further, it can be said that the imaginary line L1 is a straight line that is in a plane including the connection point A and the connection point B and extends in a direction perpendicular to the drive direction of the driven body.

  As shown in FIG. 3A, both the bending displacement members 1A and 1B are arranged side by side on the virtual line L1. In other words, a line passing through the center of the bending displacement member 1A and parallel to the length direction overlaps with a line passing through the center of the bending displacement member 1B and parallel to the length direction by the same virtual line L1. It is such an arrangement.

  Further, the connection point A and the connection point B are arranged such that a virtual line AB connecting these two points intersects the virtual line L1. Further, as shown in the figure, the connection point A is arranged on the upper side with respect to the virtual line L1. On the other hand, the connection point B is arranged below the virtual line L1.

  Further, the friction member 3 is arranged on an imaginary line AB connecting the connection point A and the connection point B. That is, when the contact portion of the friction member 3 with the lens barrel 4 passes through an arbitrary point of the virtual line AB and a straight line perpendicular to the plane including the connection points A and B is defined as the second straight line L1 ′. The second straight line L1 ′ is arranged so as to pass through.

  Further, as shown in FIG. 3B, the bending displacement member 1A is displaced in the direction of the arrow referred to as the bending displacement direction A, so that the connecting point A of the elastic member 2 is referred to as the elastic member displacement direction A. A displacement vector is excited in the direction of the arrow indicated. Further, since the bending displacement member 1B is displaced in the direction of the arrow referred to as the bending displacement direction B, a displacement vector is excited at the connection point B of the elastic member 2 in the direction of the arrow referred to as the elastic member displacement direction B ( That is, a displacement vector is excited in the direction perpendicular to the paper surface at the connection points A and B in FIG. In addition, although the displacement vector is excited in directions other than the above at the connection points A and B, since the relationship with the drive is small, the description is omitted.

  Hereinafter, the driving voltage waveform by the control means including the driving circuits 7A and 7B and the principle of the optical axis direction driving operation of the lens barrel 4 based on the driving voltage waveform in this driving device will be described.

(Operating principle)
An operation example in which the tip of the friction member 3 (the portion that frictionally engages the lens barrel 4) is driven in an arc and the lens barrel 4 is driven in the optical axis direction will be described. FIG. 4 is a graph showing drive voltage waveforms applied to the two bending displacement members 1A and 1B. FIGS. 5A and 5B are explanatory diagrams for explaining the arc driving of the tip of the friction member 3 based on the driving voltage waveform shown in FIG. FIG. 5 is a diagram seen from the direction of the arrow V in FIG.

  In FIG. 4, the drive voltage waveform applied to the bending displacement member 1A is waveform A, and the driving voltage waveform applied to the bending displacement member 1B is waveform B. The drive voltage waveforms of waveforms A and B are output from drive circuits 7A and 7B, respectively. As shown in the figure, the waveform A and the waveform B are sawtooth drive voltage waveforms, and are signal waveforms that are relatively 180 degrees out of phase. Here, the states of the connection points A and B corresponding to the time points (i) to (v) of the waveforms A and B shown in FIG. 4 are shown in FIGS.

  As shown in FIGS. 5A and 5B, when the waveforms A and B are driven, the positions of the connection points A and B change from (i) to (v). That is, the connection points A and B are in the state (i) of FIG. 5 (a) at the time (i) in FIG. 4, and (ii) in FIG. 5 (a) at the time (ii) in FIG. 4 (iii) at the time of FIG. 4 (iii) in the state of (iii) of FIG. 5 (a), (b), and (iv) of FIG. 5 (b) at the time of (iv) of FIG. In this state, the state of (v) in FIG. 5 (b) is reached at the time of (v) in FIG. As the connecting points A and B shift to the states (i) to (v) shown in FIGS. 5 (a) and 5 (b) and are displaced, the tip of the friction member 3 becomes a circular arc as shown in the figure. Will be driven.

  At this time, the tip of the friction member 3 is circularly driven by the sawtooth drive voltage waveform shown in FIG. 4, so that a difference occurs between the angular velocity in the driving direction and the angular velocity in the reverse driving direction (that is, (i) to While the angular velocity transitioning to the state (iii) is relatively slow, the angular velocity transitioning to the states (iii) to (v) is relatively high.

  In addition, by appropriately setting the driving voltage waveform, the tip of the friction member 3 can be made to have a difference between the angular acceleration in the driving direction and the angular acceleration in the reverse driving direction. That is, the angular acceleration that transitions to the states (i) to (iii) (driving direction) is relatively slow, while the angular acceleration that transitions to the states (iii) to (v) (reverse driving direction) is relatively The drive voltage waveform can be set so as to be faster. Therefore, by adjusting the friction coefficient of the friction member 3 and the like, the force applied to the contact between the friction member 3 and the lens barrel 4 exceeds the static friction force between the friction member 3 and the lens barrel 4 in the driving direction. It is possible to prevent the tip of the friction member 3 from sliding on the lens barrel 4. On the other hand, in the reverse drive direction, the force applied to the contact between the friction member 3 and the lens barrel 4 exceeds the static friction force between the friction member 3 and the lens barrel 4, so that the tip of the friction member 3 slides on the lens barrel 4. Can be. As a result, a difference occurs between the driving force in the driving direction and the driving force in the reverse driving direction, and the lens barrel 4 is driven in the driving direction.

  Further, it is possible to adjust the friction coefficient and the like so that the tip of the friction member 3 slides on the lens barrel 4 in both the driving direction and the reverse driving direction. In this case, the driving force in the driving direction and the driving force in the reverse driving direction are determined by the dynamic friction force and become the same force. However, the drive voltage waveform shown in FIG. 14 sets the displacement time in the drive direction to be long and the displacement time in the reverse drive direction to be short. Therefore, the time during which the dynamic frictional force in the drive direction is applied is reverse driven. It becomes longer than the time when the dynamic frictional force of the direction is acting. Therefore, as a result, the lens barrel 4 is driven in the driving direction.

  In addition, the elastic member is connected so that the virtual line connecting the center of the connection point A and the center of the connection point B intersects the virtual line parallel to the length direction as described above (ideally orthogonally). Therefore, the tip of the friction member can be rotationally driven or driven in a circular arc (straight line) in the optical axis direction by the displacement of the bending displacement members 1A and 1B. Then, the connecting portion of the two bending displacement members 1A and 1B is bent at a corner (ideally 90 degrees), and the lens barrel is placed in a virtual sector space region formed by the two bending displacement members. 4 is disposed, and the bending displacement members 1A and 1B are disposed on the wall surface of the housing 6, whereby the drive device can be reduced in size and height. At this time, it is not necessary to completely follow the wall surface of the housing 6, and it goes without saying that it may be appropriately arranged according to the empty space in the module housing 6.

In the present drive device, the contact portion (friction engagement portion) of the friction member 3 with the lens barrel 4 is circular, and the circular curvature radius r and the drive radius D of the friction member 3 satisfy the following conditions. 0.5 ≦ r / D ≦ 1.5
It is characterized by satisfying.

  Since the curvature radius r and the drive radius D are set as in the above condition, the lens barrel 4 can be used even when the elastic member 2 as a vibrating body is attached to the lens barrel 4 at an inclination. Can be driven stably. Hereinafter, the above conditions for stable driving of the lens barrel 4 will be described in more detail.

(Conditions for stabilizing driving of the lens barrel 4)
FIG. 6 is a schematic diagram schematically showing the vibration of the elastic member 2 and the locus of the contact portion 3a of the friction member 3 that vibrates with the elastic member 2. As shown in FIG. In addition, in FIG. 6, the locus | trajectory of the contact part 3a of the friction member 3 is shown as 2L (broken line). A position 4b (solid line) indicates the position of the side surface of the lens barrel 4 when the elastic member 2 is ideally attached. Further, D is a distance between the side surface of the lens barrel 4 at the position 4b and the center O of the arc locus 2L. As shown in FIG. 6, D is the radius of the arc locus 2L, and is hereinafter referred to as a drive radius.

  A position 4 b ′ (thin line) in FIG. 6 indicates the position of the side surface of the lens barrel 4 when the elastic member 2 is attached to the lens barrel 4 at an angle θ. Further, the angle θ ′ indicates an angle at which the friction member 3 is driven in a circular arc by vibration of the elastic member 2 when the elastic member 2 is attached at the attachment angle θ. A position 4 b ″ (thin line) indicates the position of the side surface of the lens barrel 4 when the friction member 3 is arc-driven at an angle θ ′. Note that the contact locations 4a, 4a ', and 4a "indicate contact locations with the contact portion 3a when the side surface of the lens barrel 4 is at the positions 4b, 4b', and 4b", respectively. r indicates the radius of curvature of the contact portion 3 a of the friction member 3.

  As shown in FIG. 6, the side surface of the lens barrel 4 is changed by the circular movement of the friction member 3 by the vibration of the elastic member 2. For example, consider a case where the elastic member 2 is attached at the attachment angle θ, and the friction member 3 is driven in an arc by an angle θ ′ due to vibration of the elastic member 2. In this case, the side surface of the lens barrel 4 changes from the position 4 b ′ to the position 4 b ″.

Here, when the reference line T is a line that passes through the center O of the arc locus 2L and is parallel to the side surface of the lens barrel 4, the position 4b ′ is expressed by the following equation (1) as a position from the reference line T. Can be expressed as
(D−r) × cos θ + r (1)
Similarly, the position 4b ″ can be expressed as the following formula (2).
(D−r) × cos (θ + θ ′) + r (2)
Therefore, when the elastic member 2 is attached at the attachment angle θ, and the friction member 3 is driven by an arc θ ′ by the vibration of the elastic member 2, the position change amount on the side surface of the lens barrel 4 is expressed by the following equation (3). It can be expressed as
{(D−r) × cos θ + r} − {(D−r) × cos (θ + θ ′) + r} (3)
The position change amount can be used as an index indicating a contact state between the contact portion 3a of the friction member 3 and the side surface of the lens barrel 4. That is, the smaller the position change amount, the smaller the change in the contact state between the contact portion 3a of the friction member 3 and the side surface of the lens barrel 4, and the lens barrel 4 can be driven stably.

  FIG. 7 is a graph showing the relationship between the ratio r / D between the driving radius D of the friction member 3 and the curvature radius r of the contact portion 3a and the position change amount. In FIG. 7, the ratio r when the attachment angle θ of the elastic member 2 with respect to the side surface of the lens barrel 4 is changed to 0 °, 0.4 °, 1 °, 1.5 °, 2 °, and 2.5 °. The relationship between / D and the position change amount is shown. In the graph of FIG. 7, the angle θ ′ at which the friction member 3 is driven in a circular arc by the vibration of the elastic member 2 is ± 1 °.

  As shown in FIG. 7, when the ratio r / D = 1, the amount of change in position is 0 regardless of the angle at which the attachment angle θ is changed. The position change amount increases as the ratio r / D becomes a value farther from 1. Further, as the attachment angle θ is increased, the position change amount is increased.

  From the relationship between the ratio r / D and the position change amount shown in FIG. 7, the position change amount can be obtained uniquely when the mounting angle θ and the ratio r / D are set. Therefore, if the range of the position change amount of the side surface of the lens barrel 4 capable of stably driving the lens barrel 4 is obtained, the ratio r / D corresponding to the mounting angle θ can be appropriately set based on this range. become.

(Range of position change amount capable of stably driving the lens barrel 4)
The inventor of the present application pays attention to the above points and experimented to what extent the amount of change in position can stably drive the lens barrel 4. The driving mechanism of the lens barrel 4 used in this experiment is shown in FIGS. 8 (a) and 8 (b).

  The driving mechanism of the lens barrel 4 used in the experiment is similar to the driving mechanism using the bending displacement members 1A and 1B, the elastic member 2, and the friction member 3 shown in FIGS. 3 (a) and 3 (b). . However, as shown in FIG. 8B, the drive mechanism used in the experiment has a configuration in which the bending displacement members 21A and 21B and the elastic member 2 are arranged on the same plane. A friction member 3 is provided on the elastic member 2 so as to be in contact with the lens barrel 4. Even with the drive mechanism shown in FIGS. 8A and 8B, the lens barrel 4 can be driven in the drive direction (perpendicular to the paper surface of FIG. 8).

  In the experiment, the ends of the bending displacement members 21A and 21B shown in FIG. 8 were fixed at the position 31, and the lens barrel 4 was driven according to the driving principle described above. Then, the driving stability of the lens barrel 4 was examined by measuring the speed of the lens barrel 4 during driving and observing the change. The experimental conditions were as follows: the radius of curvature r of the contact portion 3a of the friction member 3 is 0.3 mm, the drive radius D of the friction member 3 is 5.6 mm (ratio r / D = 0.05), and the mounting angle θ = 0 °. It is.

  FIG. 9 shows the result of measuring the speed of the lens barrel 4 driven by the drive mechanism shown in FIG. In FIG. 9, the vertical axis represents the speed (speed (mm / s)) of the lens barrel 4, and the horizontal axis represents the frequency (Frequency (kHz)) of the drive voltage waveform. In the experiment, the speed (Speed (Fwd)) of the lens barrel 4 when driven forward in the driving direction and the speed (Speed (Rev)) of the lens barrel 4 when driven backward in the driving direction were measured. .

  As shown in FIG. 9, under the experimental conditions of the ratio r / D = 0.05 and the mounting angle θ = 0 °, the lens barrel 4 is driven stably with little speed change in its driving direction. I understand that. Further, referring to the graph of FIG. 7, it can be seen that when the ratio r / D = 0.05 and the mounting angle θ = 0 °, the positional change amount is 0.72 μm. That is, in this drive device, it can be seen that if the amount of change in the position of the side surface of the lens barrel 4 is suppressed to 0.72 μm, the driving stability of the lens barrel 4 is not impaired. Furthermore, in other words, the upper limit of the range of the position change amount that can stably drive the lens barrel 4 is 0.72 μm.

  The ratio r / D that satisfies the positional change amount ≦ 0.72 μm will be described with reference to the graph of FIG.

According to the graph of FIG. 7, when the mounting angle θ = 0.4 ° and the ratio r / D = 0.5, the position change amount is 0.69 μm, which is smaller than 0.72 μm. Similarly, when the mounting angle θ = 0.4 ° and the ratio r / D = 1.5, the position change amount is 0.69 μm, which is smaller than 0.72 μm. Therefore, in this drive device, the radius of curvature r and the drive radius D satisfy the following condition 0.5 ≦ r / D ≦ 1.5.
If the above condition is satisfied, the amount of change in the position of the side surface of the lens barrel 4 can be suppressed to a value smaller than 0.72 μm even when the mounting angle θ is 0.4 °. Thereby, stable driving of the lens barrel 4 can be realized. That is, if the condition of 0.5 ≦ r / D ≦ 1.5 is satisfied, the mounting angle θ = 0.4 ° is allowed for stable driving of the lens barrel 4. Therefore, in the present driving device, it is possible to stably drive the lens barrel even when the vibrating body including the elastic member and the friction member is attached with an inclination of 0.4 ° with respect to the lens barrel.

Furthermore, according to the graph of FIG. 7, when the mounting angle θ = 2.5 ° and the ratio r / D = 0.9, the position change amount is 0.46 μm, which is smaller than 0.72 μm. Similarly, when the mounting angle θ = 2.5 ° and the ratio r / D = 1.1, the position change amount is 0.46 μm, which is smaller than 0.72 μm. Therefore, in the present driving device, the curvature radius r and the driving radius D satisfy the following condition 0.9 ≦ r / D ≦ 1.1.
If the angle is satisfied, even if the attachment angle θ is 2.5 °, the amount of change in the position of the side surface of the lens barrel 4 can be suppressed to a value smaller than 0.72 μm. That is, if the condition of 0.9 ≦ r / D ≦ 1.1 is satisfied, the mounting angle θ is allowed to be 2.5 ° for the stable driving of the lens barrel 4.

  Further, if the radius of curvature r of the friction member 3 is made equal to the drive radius D of the friction member 3 (ratio D / D = 1), the amount of change in position is always zero even when the mounting angle θ is increased. Therefore, it is not necessary to adjust the attachment of the vibrating body composed of the elastic member and the friction member to the lens barrel, and the assembly efficiency of the drive device is improved.

(Friction member shape for stabilizing drive)
As for the shape of the friction member 3 in this drive device, the contact portion (friction engagement portion) with the lens barrel 4 is circular, and the circular curvature radius r and the drive radius D of the friction member 3 are: The following conditions 0.5 ≦ r / D ≦ 1.5
If it is the shape which satisfy | fills, it will not specifically limit. Hereinafter, an example of the shape of the friction member 3 for stabilizing and driving the lens barrel 4 will be described. 10 to 14 are diagrams showing an example of the shape of the friction member 3 in the present driving device. 10 to 14, the portions where the elastic member 2 vibrates are indicated by ◯ marks. The center of the arc driving locus of the friction member 3 caused by the vibration of the circled portion of the elastic member 2 is indicated by ●. 10 to 14 show only the elastic member 2, a part of the lens barrel 4, and the friction member 3 in order to simplify the description.

  First, the shape of the friction member 3 shown in FIG. 10 is configured to come into contact with the entire portion facing the lens barrel 4. The radius of curvature r of the friction member 3 and the drive radius D of the friction member 3 are designed to be the same. That is, the ratio r / D = 1 of the curvature radius r and the drive radius D is obtained. Thereby, when assembling the driving device, even if the elastic member 2 and the lens barrel 4 are attached to be inclined, the friction member 3 always contacts with the lens barrel 4 in the same state. Therefore, even when the elastic member 2 and the lens barrel 4 are attached to be inclined, the lens barrel 4 can be stably driven. That is, according to the configuration shown in FIG. 10, it is not necessary to adjust the positions of the elastic member 2 and the lens barrel 4, and the assembly of the drive device is facilitated.

  Here, the shape of the contact portion of the friction member 3 (or the portion of the friction member 3 facing the lens barrel 4) is circular. The “circular shape” is an arbitrary cross-sectional shape formed when the friction member 3 is cut along a plane perpendicular to the side surface of the lens barrel 4 and parallel to the driving direction (for example, a plane parallel to the paper surface of FIG. 10). The at least one cross-sectional shape is a circle or a shape including a circle.

  For example, in the configuration shown in FIG. 10, the shape of the friction member 3 is a semicircular shape. The shape of the friction member 3 may be a hemispherical shape. Thereby, for example, even when the elastic member 2 is attached to the lens barrel 4 in a direction perpendicular to the plane of FIG. 10 (direction perpendicular to the driving direction), the friction member 3 is always in the same state as the lens barrel 4. Contact. Therefore, the lens barrel 4 can be driven more stably.

  The shape of the friction member 3 in the present driving device is not particularly limited as long as the contact portion with the lens barrel 4 has a circular shape satisfying the above condition 0.5 ≦ r / D ≦ 1.5. That is, the shape of the portion other than the contact portion with the lens barrel 4 in the friction member 3 is not particularly limited.

  FIG. 11 is a diagram showing another example of the shape of the friction member 3 in the present driving device. The shape of the friction member 3 shown in FIG. 11 is designed so that the radius of curvature r and the driving radius D are the same, and only the contact portion 3a with the lens barrel 4 is circular. The shape of the entire friction member 3 is a shell-shaped shape.

  FIG. 12 is a view showing still another example of the shape of the friction member 3 in the present driving device. The shape of the friction member 3 shown in FIG. 12 is designed so that the radius of curvature r and the drive radius D are the same as in the configuration of FIG. However, the shape of the friction member 3 shown in FIG. 12 is different from the configuration of FIG. 11 in the shape of the portion other than the contact portion with the lens barrel 4.

  As shown in FIG. 12, the friction member 3 is formed with the inclined surface 3b so that the width H in the driving direction of the lens barrel 4 gradually decreases from the center of the arc driving locus (marked with ●) toward the contact portion 3a. Has been. By forming the inclined surface 3b in this way, a wide contact portion between the friction member 3 and the elastic member 2 can be secured. For this reason, the adhesion area of the friction member 3 and the elastic member 2 increases, and it becomes possible to fix the friction member 3 to the elastic member 2 more firmly.

  FIG. 13 is a diagram showing still another example of the shape of the friction member 3 in the present driving device. As shown in FIG. 13, the shape of the friction member 3 may be a spherical body or a cylindrical body. In this case, the spherical body or the cylindrical body (friction member 3) is bonded to the elastic member 2 with the adhesive 3. The spherical or cylindrical body has a diameter equal to the driving radius D. By doing so, the radius of the spherical or cylindrical body becomes equal to the radius of curvature r of the contact portion 3a with the lens barrel 4, and the ratio r / D = 0.5. Therefore, the shape of the friction member 3 shown in FIG. 13 can realize stable driving of the lens barrel 4 even when the attachment angle θ is 0.4 °. That is, the mounting angle θ = 0.4 ° can be allowed for stable driving of the lens barrel 4. Furthermore, the friction member 3 can be firmly fixed to the elastic member 2 by appropriately setting the amount of the adhesive 30.

  FIG. 14 is a view showing still another example of the shape of the friction member 3 in the present driving device. The shape of the friction member 3 shown in FIG. 14 is a spherical body or a cylindrical body as in the configuration of FIG. However, the configuration shown in FIG. 12 is different from the configuration shown in FIG. 13 in that the elastic member 2 is formed with a recess 2a capable of accommodating a spherical body or a cylindrical body (friction member 3).

  As shown in FIG. 14, the spherical body or cylindrical body (friction member 3) is accommodated in the recess 2a so that the driving radius D and the curvature radius r are equal. Thereby, the contact area of the elastic member 2 and the friction member 3 can be increased rather than the structure of FIG. Therefore, the friction member 3 can be fixed to the elastic member 2 more firmly. Further, in the configuration shown in FIG. 14, since the ratio r / D = 1, the alignment of the friction member 3 with respect to the elastic member 2 is facilitated.

  The dimension of the recess 2a may be any dimension that can accommodate a spherical body or a cylindrical body so that the driving radius D and the radius of curvature r are equal. The spherical body or the cylindrical body (friction member 3) and the elastic member 2 may be used. It can set suitably according to the quantity of the adhesive agent used for fixation.

  In the above-described embodiment, the example in which the friction member 3 and the elastic member 2 are made of different materials has been described. However, the friction member 3 and the elastic member 2 may be integrated. That is, the elastic member 2 may be integrally formed with the same shape as the friction member 3. By integrally forming in this way, the labor of bonding the friction member 3 and the elastic member 2 can be saved, and the cost can be reduced.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  Since this driving device can realize stable driving of the driven body, it can be applied to the use of driving a lens in an optical device such as a photographing lens of a camera.

It is a perspective view which shows the structure of the drive device of one Embodiment of this invention. The structure of the piezoelectric element of a bimorph structure is shown, (a) is a side view, (b) is a figure which shows the mode of the bending displacement of a piezoelectric element. (A) is the side view which showed the positional relationship of the bending displacement member, the elastic member, and the friction member in this drive device, (b) is the top view which showed the structure of the drive device. It is a graph which shows the drive voltage waveform applied to two bending displacement members. (A) * (b) is explanatory drawing for demonstrating circular arc drive of the front-end | tip part of a friction member based on the drive voltage waveform shown by FIG. It is the schematic diagram which showed typically the locus | trajectory of the contact part of the friction member which vibrates with it, and the vibration of an elastic member. It is a graph which shows ratio r / D of the drive radius D of a friction member, and the curvature radius r of a contact part, and the relationship of a positional change amount. (A) and (b) schematically show the driving mechanism of the lens barrel used in the experiment for verifying how much the position change amount can be driven stably. It is a schematic diagram. It is a graph which shows the result of having measured the speed of the lens-barrel 4 driven by the drive mechanism shown by FIG. It is the figure which showed an example of the shape of the friction member in the drive device of one Embodiment of this invention. It is the figure which showed the other example of the shape of the friction member in the drive device of one Embodiment of this invention. It is the figure which showed the further another example of the shape of the friction member in the drive device of one Embodiment of this invention. It is the figure which showed the further another example of the shape of the friction member in the drive device of one Embodiment of this invention. It is the figure which showed the further another example of the shape of the friction member in the drive device of one Embodiment of this invention. It is explanatory drawing for demonstrating the problem of the conventional drive device, and shows the state by which the vibrating body was ideally attached with respect to the to-be-driven body. It is explanatory drawing for demonstrating the problem of the conventional drive device, and shows the state by which the vibrating body was attached with inclination with respect to the to-be-driven body.

Explanation of symbols

1A bending displacement member (first bending displacement member, drive source)
1B bending displacement member (second bending displacement member, drive source)
2 Elastic member (vibrating substrate, vibrating body)
2a hollow part 3 friction member (vibrating body, contact part)
3a Contact part 4 Lens barrel (driven body)
5 Guide shaft 6 Camera module housing (housing)
7A drive circuit (first drive circuit)
7B Drive circuit (second drive circuit)
D Drive radius r Curvature radius

Claims (6)

A vibrating body that vibrates in an arc shape;
A drive source for vibrating the vibrator,
The vibrating body has a contact portion that can contact the driven body,
The contact portion is a drive device configured to drive a driven body while drawing an arc-shaped trajectory with the arc-shaped vibration of the vibrating body,
The contact portion has a circular shape,
When the radius of curvature of the circular shape is r and the radius of the arcuate locus of the contact portion is the driving radius D,
The radius of curvature r and the driving radius D satisfy the following conditions: 0.5 ≦ r / D ≦ 1.5
The drive device characterized by satisfy | filling. The curvature radius r and the driving radius D satisfy the following condition 0.9 ≦ r / D ≦ 1.1.
The drive device according to claim 1, wherein: The radius of curvature r and the driving radius D satisfy the following condition r = D
The drive device according to claim 1, wherein:   The drive device according to any one of claims 1 to 3, wherein the contact portion is formed of a friction member that frictionally engages with the driven body. The vibrating body includes a vibration base material that vibrates by the drive source and the friction member.
The drive device according to claim 4, wherein the friction member has a spherical or cylindrical shape and is bonded to the vibration base material.   The driving device according to claim 5, wherein the vibration base is formed with a recess capable of accommodating the friction member.

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