Vibration actuators, optical instruments, and drive devices

Abstract

To increase the rigidity of a connecting mechanism of a vibration type actuator without increasing its size and to suppress the collapse of a movable part.SOLUTION: A vibration type actuator 1 has a configuration in which a movable guide member 115 connected to a vibration body 111 is movable in a driving direction D1 with respect to a fixed guide member 123 connected to a friction member 121, and a connecting member 131 connecting the movable guide member 115 and the object to be driven is urged on the movable guide member 115 in the driving direction D1 by a pressing member 132. A direction of a first moment M1 to which the movable guide member 115 is subjected due to acceleration of the movable guide member 115 and a direction of a second moment to which the movable guide member 115 is subjected due to a frictional force generated in a contacting part between a contacting surface 115b of the movable guide member 115 and a contacting body 131a of the connecting member 131 are reversed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a vibration type actuator, an optical device provided with the vibration type actuator, and a driving device.

Background Art

[0002] A vibration type actuator is known that relatively moves a vibrating body and a driven body by exciting a predetermined vibration in the vibrating body to cause an elliptical motion at the tip of a protrusion provided on the vibrating body while the tip of the protrusion is in contact with the driven body. Such a vibration type actuator has characteristics such as being capable of quiet driving, obtaining a holding force when not energized, and being capable of corresponding to both translational driving and rotational driving. Therefore, for example, it is used for driving an optical member such as a lens in a lens barrel of a camera.

[0003] When driving an optical member using a vibration type actuator in a lens barrel, it is always required to drive the optical member at high speed and perform positioning in the optical axis direction with high accuracy. In response to such requirements, Patent Document 1 discloses a driving device in which a movable part of a vibration type actuator and an optical member are each guided to be movable in the driving direction by individual guide mechanisms, and a connecting member rotatably held by the optical member is biased to the movable part of the vibration type actuator.

[0004] In the driving device described in Patent Document 1, the minute position variation between the movable part of the vibration type actuator and the optical member is absorbed by the rotation of the connecting member, so that the movable part of the vibration type actuator and the optical member are connected without play (rattling). Thereby, even when the vibration type actuator is driven at high speed, the optical member connected to the movable part can be positioned with high accuracy.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] When driving a large optical component with a vibrating actuator, a large force acts on the coupling mechanism connecting the vibrating actuator and the optical component due to the gravity and inertia of the optical component, thus requiring a highly rigid coupling mechanism. Furthermore, in coupling mechanisms that use a rotating component, such as the drive device described in Patent Document 1, it is not easy to increase rigidity while avoiding increasing the size of the rotating component and the coupling mechanism.

[0007] One possible solution to this problem is a configuration in which the movable part of the vibratory actuator and the optical element are connected without the use of a rotating member. For example, the movable part and the optical element are brought into direct contact in the driving direction and connected without play by biasing them in the driving direction. In such a configuration, minute positional fluctuations that occur between the movable part of the vibratory actuator and the optical element in a direction perpendicular to the driving direction are absorbed by the sliding of their contact points.

[0008] However, when the movable part of the vibrating actuator and the contact point of the optical element slide against each other, frictional force due to the sliding acts on both the movable part of the vibrating actuator and the optical element, and this frictional force may cause the movable part of the vibrating actuator to tilt. Tilting of the movable part refers to the tilt of the movable part's posture (angle) relative to the fixed part from the ideal state (angle) in the direction of movement of the movable part. If tilting occurs in the movable part of a vibrating actuator, play will occur relative to the fixed part, and the driving accuracy of the optical element will decrease.

[0009] The present invention aims to provide a vibration-type actuator that can increase rigidity without increasing the size of the coupling mechanism, while also suppressing the tilting of the movable part. [Means for solving the problem]

[0010] The vibration actuator according to the present invention comprises a vibrating body, a driven body in contact with the vibrating body, a pressurizing member that pressurizes the vibrating body against the driven body with a predetermined pressure, a fixed guide member that holds one of the vibrating body and the driven body, a movable guide member that holds the other of the vibrating body and the driven body and is arranged to move in a predetermined driving direction by the driving force generated by the vibrating body, a connecting member that connects the movable guide member and the object to be driven, and a biasing member that biases the connecting member against the movable guide member in the driving direction, wherein at least a portion of the pressurizing force is used as a guiding force to bias the movable guide member and the fixed guide member, and one of the movable guide member and the connecting member is The arrangement of the contact surface and the contact body, and the distance from the center of the resultant force of the guide biasing force to the contact portion, are defined such that the direction of the first moment received by the movable guide member due to the acceleration of the movable guide member based on the thrust transmitted from the vibrating body and the direction of the second moment received by the movable guide member due to the frictional force generated at the contact portion are in opposite directions. When viewed from a direction perpendicular to the driving direction and the pressing direction of the applied force, if the point of application of the thrust transmitted from the vibrating body to the movable guide member is defined as the first point, the point where the contact surface and the contact body come into contact is defined as the second point, the distance between the resultant center of the guide biasing force in the driving direction and the second point is defined as L1, and the distance between the first point and the second point in the pressing direction is defined as L2, then the relationship 0.66 × L2 ≤ L1 ≤ 5 × L2 is satisfied. It is characterized by the following: [Effects of the Invention]

[0011] According to the present invention, it is possible to realize a vibration-type actuator that can increase rigidity without increasing the size of the connecting mechanism, and can also suppress the tilting of the movable part. [Brief explanation of the drawing]

[0012] [Figure 1] This is a diagram showing the configuration of a vibrating actuator according to an embodiment. [Figure 2] This is an exploded perspective view of a vibratory actuator. [Figure 3]This diagram shows a perspective view and a front view of the vibrating actuator, a perspective view of the coupling mechanism, and a diagram illustrating the forces acting on the movable parts. [Figure 4] This is a cross-sectional view showing the structure of a vibrating actuator. [Figure 5] This is a cross-sectional view showing the schematic configuration of the imaging device and a perspective view showing the schematic configuration of the lens drive device. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0014] Figure 1 shows the configuration of a vibratory actuator 1 according to an embodiment. More specifically, Figure 1(a) is a top view of the vibratory actuator 1, Figure 1(b) is a side view of the vibratory actuator 1 (viewed from the driving direction D1), and Figure 1(c) is a cross-sectional view taken along arrow AA in Figure 1(a). Figure 2 is an exploded perspective view of the vibratory actuator 1, and the viewing direction of the vibratory actuator 1 differs between Figure 2(a) and Figure 2(b).

[0015] As shown in Figure 1, for the sake of explanation, a three-dimensional Cartesian coordinate system consisting of the drive direction D1, the pressurizing direction D2, and the width direction D3 is defined for the vibrating actuator 1. Details of each direction will be described later.

[0016] The vibration actuator 1 comprises a fixed part 12, a movable part 11 positioned to be movable in the driving direction D1 relative to the fixed part 12, and a connecting mechanism 13 that connects the movable part 11 to an object to be driven (not shown).

[0017] The movable part 11 includes a vibrating body 111 that generates a driving force when a voltage is applied, a holding mechanism for the vibrating body 111, and a pressurizing mechanism that pressurizes the vibrating body 111 against the friction member 121 with a predetermined pressing force F1. The fixed part 12 includes a friction member 121 that is in frictional contact with the vibrating body 111, and a holding mechanism for the friction member 121.

[0018] The holding mechanism of the vibrating body 111 includes a vibrating body holding frame 112, a connection plate 113, a movable frame 114, and a movable guide member 115. The pressing mechanism for pressing the vibrating body 111 against the friction member 121 includes a pressing member 116, a pressing plate 117, and a buffer member 118. The holding mechanism of the friction member 121 includes a fixed frame 122 and a fixed guide member 123.

[0019] Note that the driving direction D1 shown in FIG. 1 is the moving direction (driving direction) of the movable part 11. The pressing direction D2 is the direction in which the pressing force F1 for pressing the vibrating body 111 against the friction member 121 acts, and is the thickness direction of the vibration type actuator 1. The width direction D3 is defined as the width direction of the vibration type actuator 1.

[0020] The vibrating body 111 is a structure in which a piezoelectric element 111a is adhered (joined) to an elastic member 111b having two protrusions 111c. The piezoelectric element 111a is a plate material made of piezoelectric ceramics such as PZT (lead zirconate titanate), the elastic member 111b is a metal sheet, and the protrusion 111c is an embossed shape portion formed on the elastic member 111b by drawing. By applying a predetermined AC voltage to the piezoelectric element 111a, an elliptical motion can be generated at the tip of the protrusion 111c. Since such a method of exciting the vibrating body 111 is well-known, a detailed description thereof is omitted. Also, the number of protrusions provided on the vibrating body 111 is not limited to two, and may be one.

[0021] The vibrating body holding frame 112 is a resin-made frame that holds the vibrating body 111 by directly adhering the vibrating body 111 thereto. The connection plate 113 is a thin metal plate, and the movable frame 114 is a resin-made frame. The connection plate 113 has high rigidity in the planar direction and low rigidity in the bending direction. Therefore, by connecting the vibrating body holding frame 112 and the movable frame 114 with the connection plate 113, the vibrating body 111 and the vibrating body holding frame 112 can move (displace) in the pressing direction D2 with respect to the movable frame 114 and are held without play in the driving direction D1. The movable guide member 115 is a metal sheet metal and has a guide groove 115a extending in the driving direction D1, a contact surface 115b formed by bending and substantially orthogonal to the driving direction D1, and a hook 115c. The movable frame 114 and the movable guide member 115 are integrated (coupled) by screw fastening.

[0022] The friction member 121 is a metal beam (rectangular rod-shaped body (plate-shaped rectangular parallelepiped)) and is a driven body that contacts the protrusion 111c of the vibrating body 111 at the sliding surface 121a and receives a frictional driving force (thrust) from the vibrating body 111. The fixed guide member 123 is a metal sheet metal and has a guide groove 123a extending in the driving direction D1 and a guide surface 123b (plane). The friction member 121 and the fixed guide member 123 are integrated (coupled) to the fixed frame 122 by screw fastening. The fixed frame 122 is fixed to a housing (not shown) of an electronic device or the like equipped with the vibration type actuator 1.

[0023] A tension coil spring is used as the pressurizing member 116. The pressurizing plate 117 is made of metal sheet metal and has a hook 117a. The pressurizing member 116 is elastically deformed by having one end hooked onto the hook 115c of the movable guide member 115 and the other end hooked onto the hook 117a of the pressurizing plate 117, thereby generating an applied pressure F1 that pressurizes the vibrating body 111 against the friction member 121. The buffer member 118 is a structure in which felt 118b is bonded to a resin plate 118a. The applied pressure F1 of the pressurizing member 116 is transmitted to the vibrating body 111 via the pressurizing plate 117 and the buffer member 118. Since the vibrating body 111 and the vibrating body holding frame 112 are held so as to be movable in the pressurizing direction D2, the applied pressure F1 is not hindered by the holding mechanism of the vibrating body 111. In this way, the projection 111c of the vibrating body 111 is pressed against the sliding surface 121a of the friction member 121 by the applied force F1.

[0024] In the movable guide member 115, the guide groove 115a is positioned to face the guide groove 123a and guide surface 123b of the fixed guide member 123 in the pressurizing direction D2. Rolling balls 14 are arranged between the guide groove 115a and the guide groove 123a and guide surface 123b.

[0025] The pressing force F1 of the pressurizing member 116 acts as opposing forces on the hook 117a of the pressurizing plate 117 and the hook 115c of the movable guide member 115. Therefore, the force acting on the hook 115c of the movable guide member 115 (hereinafter referred to as "guide biasing force F2") is used to bias the movable guide member 115 of the movable part 11 in the pressurizing direction D2 relative to the fixed guide member 123 of the fixed part 12. As a result, the rolling ball 14 is held between the movable guide member 115 and the fixed guide member 123 by the guide biasing force F2.

[0026] The rolling balls 14, which are sandwiched between the guide grooves 123a and 123b and the guide groove 115a, roll, thereby holding the movable guide member 115 so that it can move in the driving direction D1 relative to the fixed guide member 123. Furthermore, as long as the rolling balls 14 are sandwiched between the movable guide member 115 and the fixed guide member 123 with sufficient guiding force F2, the movable guide member 115 cannot move in any direction other than the driving direction D1, nor can it rotate in any direction. In this way, the movable part 11 is held so that it can move only in the driving direction D1 relative to the fixed part 12.

[0027] The materials and structures exemplified above for each component of the vibration actuator 1 are merely examples; other materials and structures may be selected as long as they have equivalent functionality and can constitute the vibration actuator 1.

[0028] Next, the coupling mechanism between the vibrating actuator 1 and the object to be driven will be described. Figure 3(a) is a perspective view of the vibrating actuator 1. Figure 3(b) is a perspective view of the coupling mechanism 13. Figure 3(c) is a front view of the vibrating actuator 1 (viewed from the width direction D3). Figure 3(d) is a diagram illustrating some of the forces acting on the movable part 11.

[0029] The connecting mechanism 13 that connects the vibrating actuator 1 to the object to be driven (not shown) includes a connecting member 131 and a biasing member 132. For example, the connecting member 131 is a resin structure, and the biasing member 132 is a compression coil spring.

[0030] The movable guide member 115 has a contact surface 115b (see Figure 2 as appropriate) that is substantially perpendicular to the drive direction D1, and the connecting member 131 has a spherical contact body 131a that contacts the contact surface 115b. Furthermore, as shown in Figure 3(c), the contact surface 115b and the contact body 131a come into contact at a contact position at a predetermined distance L1 from the center of the resultant force C1 of the guide biasing force F2 in the drive direction D1. As a result, the contact body 131a is biased in the drive direction D1 relative to the contact surface 115b by the biasing force F3 from the biasing member 132. The connecting member 131 is fixed to the object to be driven (not shown) with screws or the like. When the vibrating actuator 1 is driven, the connecting member 131 moves in the drive direction D1 integrally with the movable part 11. At this time, the object to be driven connected to the connecting member 131 is guided by a guide mechanism (not shown) so that it can move only in a direction substantially parallel to the driving direction D1. The object to be driven and the connecting member 131 are movable only in the driving direction D1 and are held so that they cannot rotate in any direction.

[0031] In this way, the connecting mechanism 13 connects the movable part 11 of the vibrating actuator 1 and the object to be driven without any play. The connecting member 131 is movable in a direction perpendicular to the driving direction D1 by the sliding of the contact body 131a against the contact surface 115b. Therefore, even if there is a small positional fluctuation between the movable part 11 and the object to be driven in a direction perpendicular to the driving direction D1, the positional fluctuation can be absorbed.

[0032] In the vibrating actuator 1, the vibrating body 111 is pressed against the friction member 121 by the pressing force F1 generated by the pressurizing member 116, while the movable guide member 115 is biased against the fixed guide member 123 by using the reaction force F1 as a guide biasing force F2. As a result, the movable part 11 is held so as to be movable only in the driving direction D1 without falling relative to the fixed part 12. In addition, the movable guide member 115 and the connecting member 131 are connected with a biasing force F3 in the driving direction D1, and positional fluctuations in the in-plane direction perpendicular to the driving direction D1 between the movable part 11 and the object to be driven are absorbed by the sliding of the contact surface 115b and the contact body 131a. With this configuration, the vibrating actuator 1 achieves high rigidity without increasing the size of the connecting mechanism 13.

[0033] However, under certain conditions, the movable part 11 may tip over relative to the fixed part 12, and countermeasures against this problem are necessary. Before explaining the countermeasures to prevent the movable part 11 from tipping over relative to the fixed part 12, we will explain under what conditions the movable part 11 is likely to tip over relative to the fixed part 12.

[0034] As explained, the contact body 131a slides against the contact surface 115b. When the contact body 131a slides on the contact surface 115b, a frictional force F4 acts on the contact surface 115b. This frictional force F4 can occur in any direction within the plane perpendicular to the driving direction D1. The frictional forces F4a, F4b, F4c, and F4d shown in Figure 3(b) are examples, and a resultant frictional force F4 can occur, having frictional forces in predetermined directions as components.

[0035] Figure 3(d) shows the relationship between the friction force F4a, the applied pressure F1, and the guiding force F2 when the friction force F4 is F4a as shown in Figure 3(b). Since the friction force F4a is generated in the opposite direction to the guiding force F2, when the friction force F4a is generated, the guiding force F2 decreases as a result. Also, the magnitude of the friction force F4 is proportional to the contact force F5 between the contact surface 115b and the contact body 131a. For example, when the movable part 11 is accelerated in the direction indicated by arrow V1 in Figure 3(c), the contact surface 115b is pressed strongly against the contact body 131a, and the contact force F5 increases. Conversely, when the movable part 11 is accelerated in the direction indicated by arrow V2 in Figure 3(c), the contact surface 115b tries to move away from the contact body 131a, so the contact force F5 decreases. In other words, when the movable part 11 accelerates in a direction that increases the contact force F5 between the contact surface 115b and the contact body 131a, the frictional force F4 increases.

[0036] Thus, when the frictional force F4 acts in a direction that reduces the guiding force F2 as shown in Figure 3(d), and the movable part 11 is accelerated in a direction that increases the contact force F5, the frictional force F4 significantly reduces the guiding force F2, making the movable part 11 more prone to tipping over. Furthermore, as will be described later, multiple moments act on the movable part 11, and when the movable part 11 receives a moment in a predetermined direction while the guiding force F2 is reduced, there is a risk that the movable part 11 will tip over.

[0037] The features of the vibration-type actuator 1 used to address this problem are described in detail below. Figure 4(a) is a cross-sectional view of the vibration-type actuator 1, and is an enlarged view of the area within the dashed line shown in Figure 1(c). Figures 4(b) and (c) are cross-sectional views of the vibration-type actuator 1, and are partially enlarged views of Figure 3(b). Although the cutting positions showing the cross-sections differ between Figure 4(a) and Figures 4(b) and (c), all are views of the vibration-type actuator 1 from the width direction D3.

[0038] Under conditions where the movable part 11 is prone to tipping over, there are two moments that attempt to tip over the movable guide member 115 of the movable part 11. One is the first moment M1 that the movable guide member 115 receives due to acceleration, as shown in Figure 4(b). The other is the second moment M2 that the movable guide member 115 receives due to frictional force F4, as shown in Figure 4(c).

[0039] First, let's explain the first moment M1. When the movable part 11 accelerates in the direction of arrow V1 shown in Figure 4(a), the vibrating body 111 generates a thrust F6 at the tip of the projection 111c. The thrust F6 is transmitted to the movable frame 114 via the vibrating body holding frame 112 and the connecting plate 113. In Figures 4(a) and (b), point P0 represents the point of contact between the connecting plate 113 and the vibrating body holding frame 112, and point P1 represents the point of contact (first point) between the connecting plate 113 and the movable frame 114. The thrust F6 is transmitted from point P0 to point P1 on the connecting plate 113, and at point P1 acts on the movable frame 114 and the movable guide member 115 as thrust F6' (Figure 4(b)). As mentioned above, the connecting plate 113 is a thin metal plate and transmits only the thrust F6'. Therefore, the point of application of the thrust F6' transmitted from the vibrating body 111 to the movable frame 114 and the movable guide member 115 is point P1.

[0040] Furthermore, at point P2 (the second point) where the contact surface 115b and the contact body 131a come into contact, a driving load F7 from the contact body 131a acts on the contact surface 115b. The driving load F7 includes the inertial force and sliding load of the object being driven, and the magnitude of the driving load F7 is equal to the thrust F6' due to the balance of forces. Then, a first moment M1 acts on the movable frame 114 and the movable guide member 115 due to the axial misalignment of the thrust F6' and the driving load F7. If the distance between points P1 and P2 in the pressurizing direction D1 is 'L2', the magnitude of the first moment M1 is expressed by the following equation 1.

[0041]

number

[0042] Next, the second moment M2 will be explained. As shown in Figure 4(c), in the driving direction D1, the contact surface 115b and the contact body 131a are positioned at a distance L1 from the resultant force center C1 of the guiding force F2. Therefore, a second moment M2, represented by the following equation 2, acts on the movable frame 114 and the movable guide member 115. The direction and magnitude of the second moment M2 can be adjusted by adjusting the direction and magnitude of the distance L1.

[0043]

number

[0044] The contact surface 115b and the contact body 131a are biased in the driving direction D1 at a position L1 away from the center of the resultant force C1 of the guiding force F2 in the driving direction D1. This makes it possible to intentionally generate a second moment M2 on the movable guide member 115 due to the frictional force F4 acting on the contact surface 115b. Furthermore, by making the direction of the second moment M2 opposite to the direction of the first moment M1 on the movable guide member 115 due to acceleration, the first moment M1 can be canceled out or reduced.

[0045] In other words, the vibration actuator 1, as described above, increases the rigidity of the connecting mechanism 13, and under the aforementioned conditions where the movable part 11 is prone to tipping, cancels out the two moments that would cause the movable guide member 115 to tip over, thereby suppressing the tipping of the movable part 11. In other words, the effect of suppressing the tipping of the movable part 11 by generating the first moment M1 and the second moment M2 in opposite directions is particularly pronounced under driving conditions where the frictional force F4 significantly reduces the guiding force F2. Such driving conditions are when the frictional force F4 acts in a direction that cancels out the guiding force F2 (see Figure 3(d)) and when the movable part 11 accelerates in the direction of arrow V1 where the contact force F5 increases (see Figure 3(c)).

[0046] In the vibration actuator 1, the movable part 11 is held so as not to rotate in any direction, the connecting member 131 is connected to an optical member (object to be driven) not shown, and the optical member is held so as not to rotate in any direction by a guide mechanism not shown. The effect of suppressing the tilting of the movable part 11 by frictional force F4 can also be obtained in configurations in which the movable part 11 and the connecting member 131 include rotatable members and are connected via rotatable members, not limited to these configuration conditions. However, in this case, if the connecting mechanism 13 is to be made more rigid, it becomes difficult to avoid increasing the size of the rotating parts and their holding mechanisms. In other words, when the movable part 11 and the connecting member 131 include rotatable members, in order to suppress the tilting of the movable part 11 using frictional force F4 while making the connecting mechanism 13 more rigid, it is desirable that the movable part 11 and the connecting member 131 be held so as not to rotate in any direction.

[0047] In the vibrating actuator 1, the movable guide member 115 of the movable part 11 is provided with a guide groove 115a extending in the driving direction D1. The fixed guide member 123 of the fixed part 12 is provided with a guide groove 123a and a guide surface 123b extending in the driving direction D1 at a position opposite to the guide groove 115a in the pressurizing direction D2. Rolling balls 14 are arranged between the guide groove 115a and the guide groove 123a and guide surface 123b, and the rolling balls 14 are held between the movable guide member 115 and the fixed guide member 123 by a guide biasing force F2. In this way, the pressurizing mechanism of the vibrating body 111 is used to bias the guide mechanism, and a configuration is realized in which the movable part 11 can move smoothly only in the driving direction D1 by the rolling of the rolling balls 14.

[0048] On the other hand, during the operation of the vibrating actuator 1, the position of the rolling balls 14 in the driving direction D1 fluctuates, and it is not easy to make the guiding force F2 greater than or equal to the applied force F1 of the vibrating body. Therefore, the structure of the vibrating actuator 1 cannot be said to be a structure that is prone to the tilting of the movable part 11. In other words, in a vibrating actuator 1 with a configuration in which the movable part 11 is prone to tilting, the effect of suppressing the tilting of the movable part 11 by the frictional force F4 can be obtained more significantly.

[0049] Next, we will describe a configuration that more effectively suppresses the tilting of the movable part 11 by making the magnitudes of the first moment M1 and the second moment M2 approximately equal and canceling each other out. In the vibration-type actuator 1, as described above, the configuration is such that the second moment M2 received by the movable guide member 115 due to the frictional force F4 and the first moment M1 received by the movable guide member 115 due to acceleration are generated in opposite directions and canceled out.

[0050] The conditions for making the magnitudes of the first moment M1 and the second moment M2 approximately equal are as follows. That is, the contact force F5 between the contact surface 115b and the contact body 131a (Figure 4(c)) is the resultant force of the biasing force F3 generated by the biasing member 132 and the driving load F7, and is therefore expressed by the following equation 3. Furthermore, the biasing force F3 is generally set to a value obtained by multiplying the driving load F7 by a safety factor of 1 or more, because the biasing force F3 continues to bias the contact surface 115b and the contact body 131a even if the driving load F7 is generated in the opposite direction of the arrow V1 (Figure 4(c)). Here, if the safety factor is between 1 and 2, the following equation 4 holds. Then, from the following equations 3 and 4, the magnitude range of the contact force F5 is expressed by the following equation 5. Here, the friction force F4 is the value obtained by multiplying the contact force F5 by the friction coefficient μ. Since the coefficient of friction μ generally takes values ​​between 0.1 and 0.5, the frictional force F4 can take values ​​within the range expressed by equation 6 below, according to equation 5 below. Furthermore, according to equation 2 above and equation 6 below, the magnitude of the second moment M2 that the movable guide member 115 receives due to the frictional force F4 can take values ​​within the range expressed by equation 7 below.

[0051]

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[0052] To make the magnitudes of the first moment M1 and the second moment M2 approximately equal, it is preferable to set the magnitude of the first moment M1 within the range of Equation 8, as shown in Equation 7 above. Substituting Equation 1 above into Equation 8 below, the relationship in Equation 9 below holds between distances L1 and L2. Therefore, in order to cancel out (as much as possible cancel out) the first moment M1 and the second moment M2 acting on the movable guide member 115, it is desirable that distances L1 and L2 satisfy the relationship in Equation 10 below.

[0053]

number

[0054] In the vibration-type actuator 1, the movable part 11 has a vibrating body 111 and the fixed part 12 has a friction member 121. However, the effects of the present invention can also be obtained in a vibration-type actuator where the movable part 11 has a friction member and the fixed part 12 has a vibrating body. Furthermore, in the vibration-type actuator 1, the movable guide member 115 of the movable part 11 has a contact surface 115b and the connecting member 131 has a contact body 131a. However, the effects of the present invention can also be obtained in a configuration where the movable part 11 has a contact part and the connecting member 131 has a contact surface.

[0055] Furthermore, in the vibrating actuator 1, the point of application of the thrust F6' transmitted from the vibrating body 111 to the movable frame 114 and the movable guide member 115 is point P1, which is the bonding point between the connecting plate 113 and the movable frame 114. However, the point of application of the thrust F6 transmitted from the vibrating body 111 to the movable guide member 115 does not necessarily have to be the bonding point between the connecting plate 113 and the movable frame 114. In other words, the point of application of the thrust F6 is defined as the point where the thrust F6 of the vibrating body 111 is transmitted to the movable guide member 115 without generating a moment. Therefore, for example, when the thrust F6 is transmitted through multiple paths, the point of application of the thrust F6 is the point where the resultant force of the thrusts transmitted from multiple paths acts, and this point may be a hypothetical point.

[0056] Next, an imaging device will be described as an example of an optical instrument that drives an optical component using a vibration-type actuator 1. Figure 5(a) is a cross-sectional view showing the schematic configuration of an imaging device consisting of an imaging device body 22 and a lens barrel 21. Figure 5(b) is a perspective view showing the schematic configuration of a lens drive device incorporated into the lens barrel 21.

[0057] An image sensor 22a is located inside the imaging device body 22. The imaging device body 22 also includes a mount 221 to which the lens barrel 21 is attached and detached. The mount 221 has a bayonet section that allows the lens barrel 21 to be attached and detached from the imaging device body 22.

[0058] The lens barrel 21 has a fixed barrel 211 that contacts the flange portion of the mount 221 when attached to the mount 221. The lens barrel 21 also has a front barrel 212 and a rear barrel 213 that are fixed to the fixed barrel 211, with the front barrel 212 holding lens G1 and the rear barrel 213 holding lens G3. Furthermore, a lens G2 and a lens holding frame 214 that holds lens G2 are arranged inside the lens barrel 21. The lens holding frame 214 is held so as to be movable in the drive direction D1 by guide bars 215 (guide members) held by the front barrel 212 and the rear barrel 213.

[0059] The vibrating actuator 1 is fixed to the rear lens barrel 213 with screws (not shown) or the like. The movable guide member 115, which constitutes the movable part 11 of the vibrating actuator 1, is in contact with the connecting member 131. The contact surface 115b of the movable guide member 115 and the connecting member 131 are biased in the driving direction D1 as described above. The connecting member 131 is connected to the lens holding frame 214 by screw fastening.

[0060] Therefore, when the vibrating actuator 1 is driven, the driving force of the vibrating actuator 1 is transmitted to the lens holding frame 214 via the movable guide member 115 and the connecting member 131, and the lens holding frame 214 is guided in the driving direction D1 by the guide bar 215 and moves linearly.

[0061] In this configuration, the movable guide member 115 of the vibration actuator 1 is guided by the fixed guide member 123, and the lens holding frame 214 is guided by the guide bar 215. Therefore, when the vibration actuator 1 is driven, a small positional fluctuation occurs between the movable part 11 and the lens holding frame 214 in a direction perpendicular to the driving direction D1, but this positional fluctuation is absorbed by the sliding of the movable guide member 115 and the connecting member 131.

[0062] In the lens barrel 21, by using the vibration actuator 1 and the connecting mechanism 13, the rigidity of the connecting mechanism 13 can be increased while suppressing the tilting of the movable part 11. As a result, even if the lens G2 has a large mass, it becomes possible to drive the lens G2 with high precision.

[0063] Although the present invention has been described in detail above based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various forms that do not depart from the gist of the invention are also included in the present invention. For example, the shape and material of each component constituting the vibrating actuator 1 are not limited to those described above, as long as the effects of the present invention are obtained. Also, in the above embodiments, the vibrating body 111 is configured to move in the driving direction D1 relative to the friction member 121, but the friction member 121 may be configured to move in the driving direction D1 relative to the vibrating body 111. In other words, one of the vibrating body 111 and the member connected thereto and the friction member 121 and the member connected thereto can be made into a movable part, and the other into a fixed part. It goes without saying that the connecting member 131 is connected to the movable member. Furthermore, although an example in which the object to be driven is the lens of a lens barrel has been described, the present invention can be applied to any drive device that drives the object to be driven in a straight line. For example, the present invention can be applied to imaging devices in which the object to be driven is an image sensor, display devices such as head-mounted displays in which the object to be driven is a diopter adjustment lens or display panel, and microscopes in which the object to be driven is a stage. [Explanation of Symbols]

[0064] 1. Vibration-type actuator 14 Rolling ball 21 Lens barrel 111 Vibrating Body 115 Movable guide member 115a Guide groove 115b Contact surface 116 Pressurizing member 121 Friction member 123 Fixed guide member 123a Guide groove 123b Guide surface 131 Connecting member 131a Contact body 132 Biasing member 215 Guide Bar

Claims

1. A vibrating body and A driven body that comes into contact with the vibrating body, A pressurizing member that applies pressure to the driven object with a predetermined pressure to the vibrating body, A fixed guide member that holds either the vibrating body or the driven body, A movable guide member is provided which holds the vibrating body and the other of the driven body, and which is arranged to be movable in a predetermined driving direction by the driving force generated by the vibrating body, A connecting member that connects the movable guide member and the object to be driven, The system includes a biasing member that biases the connecting member relative to the movable guide member in the aforementioned driving direction, A vibratory actuator in which at least a portion of the applied pressure is used as a guiding force to bias the movable guide member and the fixed guide member, The movable guide member and the connecting member each have a contact surface that is substantially perpendicular to the driving direction on one side, and a contact body that contacts the contact surface on the other side. The contact surface and the contact body are in contact with the biasing force of the biasing member at a position separated by a predetermined distance from the center of the resultant force of the guide biasing force in the driving direction, In a driving condition where the frictional force generated at the contact portion between the contact body and the contact surface cancels out the guide biasing force, the arrangement of the contact surface and the contact body, and the distance from the center of the resultant force of the guide biasing force to the contact portion are defined such that the direction of the first moment received by the movable guide member due to the acceleration of the movable guide member based on the thrust transmitted from the vibrating body and the direction of the second moment received by the movable guide member due to the frictional force generated at the contact portion are in opposite directions. A vibrating actuator characterized in that, when viewed from a direction perpendicular to the driving direction and the pressurizing direction of the applied force, the point of application of the thrust transmitted from the vibrating body to the movable guide member is defined as the first point, the point where the contact surface and the contact body come into contact is defined as the second point, the distance between the resultant center of the guide biasing force in the driving direction and the second point is defined as L1, and the distance between the first point and the second point in the pressurizing direction is defined as L2, the relationship 0.66 × L2 ≤ L1 ≤ 5 × L2 is satisfied.

2. The vibration actuator according to claim 1, characterized in that the driving conditions are such that a frictional force acts on the contact portion to counteract the guiding force acting on the movable guide member, and the direction of the first moment and the direction of the second moment are in opposite directions.

3. The vibration actuator according to claim 2, characterized in that the driving condition is such that when the movable guide member is accelerated in a direction that increases the contact force between the contact surface and the contact body, the direction of the first moment and the direction of the second moment are in opposite directions.

4. The vibration actuator according to any one of claims 1 to 3, characterized in that the movable guide member and the connecting member are both provided with a holding means for holding them so that they cannot be rotated in any direction.

5. The movable guide member has a first guide portion consisting of a groove extending in the driving direction, The fixed guide member has a second guide portion consisting of a groove or plane extending in the driving direction at a position facing the first guide portion in the direction of pressure application of the applied force, The vibration actuator according to any one of claims 1 to 4, characterized in that rolling balls are arranged between the first guide portion and the second guide portion, the rolling balls are held between the first guide portion and the second guide portion by the guide biasing force, the movable guide member is held so as to be movable only in the driving direction relative to the fixed guide member, and the opposite directions of the first moment and the second moment are maintained under driving conditions.

6. The vibration-type actuator according to any one of claims 1 to 5, characterized in that the contact body is spherical.

7. A vibrating actuator according to any one of claims 1 to 6, The optical member connected to the aforementioned connecting member, An optical device characterized by comprising a guide member that guides the optical element in the driving direction of the vibrating actuator.

8. A vibrating actuator according to any one of claims 1 to 6, A drive device characterized by comprising the aforementioned connecting member and a drive target object connected thereto.

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