JP6779660B2 - Vibration wave motor and drive device using vibration wave motor - Google Patents

Description

The present invention relates to an oscillator of a vibration wave motor for linear drive having an elastic body in a plate shape, and to a drive device using the above-mentioned vibration wave motor.

Conventionally, ultrasonic motors characterized by small size, light weight, high speed, and silent drive have been adopted for lens barrels and the like of imaging devices. For example, an ultrasonic motor for linear driving is disclosed in Patent Document 1. The ultrasonic motor disclosed in Patent Document 1 enables operation in a wide speed range by controlling the phase difference of the AC voltage applied to the two phases of the piezoelectric element. Further, Patent Document 2 discloses a vibration wave driving device in consideration of the rigidity of the vibrating body.

JP-A-2015-35947 (see FIGS. 8 to 12) Japanese Unexamined Patent Publication No. 2006-115559 (see FIG. 6)

In recent years, there has been an increasing demand for miniaturization of electronic devices equipped with ultrasonic motors, particularly miniaturization of lens drive devices. In order to reduce the size of the entire lens driving device as shown in FIG. 12B of Patent Document 1, it is necessary to shorten the length L5 of the diaphragm in the traveling direction of the ultrasonic motor. However, if the entire diaphragm is reduced in similarity, the area of the piezoelectric element becomes smaller and the deformation due to the piezoelectric effect decreases, so that the vibration amplitude decreases. Further, as the overall dimensions of the piezoelectric element and the diaphragm become smaller, the resonance frequency becomes higher, so that the vibration amplitude is further reduced. As a result, the propulsive force of the ultrasonic motor is reduced. Therefore, there is a limit to shortening the length L5 of the diaphragm in the traveling direction of the ultrasonic motor.

Therefore, the present invention has been made in view of the above-mentioned problems, and the dimension in the traveling direction of the vibration wave motor (ultrasonic motor) is shortened without impairing the propulsive force, and the vibration wave motor is used to reduce the size. It is an object of the present invention to provide a smart drive device.

To solve the problems described above, the vibration wave motor of the present invention, a diaphragm having a substantially rectangular outer shape, and a piezoelectric element which vibrates affixed to the vibration plate, the vibration wave motor with the diaphragm, said has a region which is not covered with the piezoelectric element inside the rectangular area to cover the piezoelectric element of the piezoelectric element in the pasted plane, the diaphragm is covered with the piezoelectric element The unbroken region has a notch, and the vibrating plate or the piezoelectric element is provided with a protrusion. The protrusion undergoes elliptical motion due to vibrations of different phases of the piezoelectric element, and the notch is formed. The substantially rectangular outer shape has a first notched region on one of the two opposing sides and a second notched region on the other, and the first notched region and the second notch region in the diaphragm. The region between the notch region and the region is characterized by including the vibration node of the diaphragm .

According to the present invention, the dimension of the vibration wave motor in the traveling direction can be shortened without impairing the propulsive force, and by using this vibration wave motor, the size of the drive device can be reduced.

It is a detailed view of the oscillator 10 of the vibration wave motor of the 1st Embodiment. It is a figure explaining the convex envelope of the oscillator 10 of the vibration wave motor of 1st Embodiment. It is a figure which shows the natural vibration mode of the vibration wave motor of 1st Embodiment. It is a figure which shows the characteristic of the resonance frequency of the vibration wave motor of 1st Embodiment. It is a figure which shows the state of the vibration of the vibration wave motor of 1st Embodiment. It is a figure which shows the state of the vibration of the vibration wave motor of 1st Embodiment. It is a figure which shows the vibration behavior of the ultrasonic motor of the conventional form. It is a figure which shows the linear drive device 100 which used the vibration wave motor of 1st Embodiment. It is a figure which shows the lens driving apparatus 200 which used the vibration wave motor of 1st Embodiment. It is a figure which shows the modification of the oscillator 10 of the vibration wave motor of 1st Embodiment. It is a detailed view of the oscillator 20 of the vibration wave motor of the 2nd Embodiment. It is a detailed view of the oscillator 30 of the vibration wave motor of the third embodiment. It is a detailed view of the oscillator 40 of the vibration wave motor of the 4th embodiment. It is a detailed view of the oscillator 50 of the vibration wave motor of the fifth embodiment. It is an enlarged view of the diaphragm 51 of the vibration wave motor of the fifth embodiment.

(First Embodiment)
Hereinafter, the first embodiment for carrying out the present invention will be described. 1A and 1B are views for explaining the vibrator 10 of the vibration wave (ultrasonic) motor of the first embodiment, FIG. 1A is a plan view, FIG. 1B is a front view, and FIG. 1 (c) and 1 (d) are side views, and FIG. 1 (e) is a bottom view. The diaphragm 1 has a substantially rectangular outer shape, and has one protrusion 1a on a flat surface portion. The protrusion 1a may be integrally molded with the diaphragm 1 by drawing or the like, or may be fixed to the diaphragm 1 as a separate component by adhesion or the like.

Piezoelectric elements 2A and 2B that generate vibrations of frequencies in the ultrasonic region (ultrasonic vibration) are attached to the surface opposite to the flat surface portion of the diaphragm 1 provided with the protrusions 1a. In No. 10, the diaphragm 1, the piezoelectric elements 2A and 2B, and the protrusion 1a are integrated. In the piezoelectric elements 2A and 2B, two regions of regions 2Aa and 2Bb are polarized in the same direction, of which region 2Aa is assigned to the A phase and region 2Bb is assigned to the B phase. The unpolarized regions 2Ac and 2Bc are electrodes used as grounds conducted from the entire surface electrodes of the back surfaces 2Ad and 2Bd of the piezoelectric elements 2A and 2B via the side surfaces. The positions of the regions 2Ac and 2Bc are arbitrary as long as they can conduct from the full surface electrodes of the back surfaces 2Ad and 2Bd of the piezoelectric elements 2A and 2B via the side surfaces.

The diaphragm 1 is provided with notches 1b1 and 1b2, which will be described later, along a straight line L. Further, within the range of the region W described later, in the range indicated by the dotted line in the vicinity of the cutout portions 1b1 and 1b2, the holding member 4 (not shown) described later that moves in synchronization with the diaphragm 1 On the other hand, connecting portions 1c1 and 1c2 that are directly or indirectly connected are provided. The connecting portions 1c1 and 1c2 can have shapes such as protrusions and recesses. As the connecting method, not only the connecting method but also the method of bonding by bonding, welding, or pressing by a spring or the like is also possible.

Here, the convex envelope will be described with reference to FIG. The convex envelope of the finite point set A is the smallest convex set including the finite point set A. Further, the convex set means a set in which a line segment connecting arbitrary two points of the set is included in the set. For example, as shown in FIG. 2A, the finite point set A is a convex set because the point set A includes a line segment connecting any two points X and Y. As shown in FIG. 2B, the finite point set B is not a convex set because the point Z on the line segment connecting the two points X and Y is not included in the point set B. The convex envelopes of the point set C, the point set D, the point set E, and the point set F as shown in FIGS. 2 (c), (d), (e), and (f) are all dotted lines connecting the vertices x1 to x4. It becomes a quadrangle indicated by S. Therefore, in FIG. 1, the convex envelope of the entire region covered by the piezoelectric elements 2A and 2B is a rectangular region (rectangle connecting the vertices x1 to x4) including the piezoelectric elements 2A and 2B.

Next, with respect to the vibrator 10 of the vibration wave motor of the present embodiment, two features related to the structure of the vibrator 10 will be described with reference to FIG. 1A. First, the first feature relating to the structure of the vibrator 10 is that the piezoelectric elements 2A and 2B of the diaphragm 1 are attached to the inside of the convex entourage of the entire region covered by the piezoelectric elements 2A and 2B in the plane. It is to have a region W (a region surrounded by a two-point chain line in the figure) not covered by the piezoelectric elements 2A and 2B. Therefore, since the region W has a structure of only the diaphragm 1, the flexural rigidity and the torsional rigidity in the region W are lower than those in the other regions. Further, the region W is substantially axisymmetric with respect to the straight line L parallel to the direction D1 parallel to one side of the diaphragm 1. Here, the flexural rigidity and the torsional rigidity mean the degree of difficulty in dimensional change with respect to the bending and torsional forces.

The second feature relating to the structure of the vibrator 10 is that the vibrating plate 1 has notches 1b1 and 1b2 along a straight line L passing through the region W and parallel to the direction D1 parallel to one side of the vibrating plate 1. Is. Therefore, the flexural rigidity and the torsional rigidity of the region W are further reduced. Further, the cutout portions 1b1 and 1b2 are substantially line-symmetric with respect to a straight line L parallel to the direction D1 parallel to one side of the diaphragm 1. The effect of reducing the flexural rigidity and the torsional rigidity due to the first feature related to the structure of the vibrator 10 and the second feature related to the structure will be described later.

Then, the ultrasonic vibration is generated by applying the AC voltage whose phase difference is freely changed to the A phase and the B phase by the feeding means Pa and Pb, which is the same as the conventional mode. It is also conventional that the resonance frequencies of the secondary natural vibration mode of torsional vibration and the primary natural vibration mode of bending vibration are matched or brought close to each other at a lower frequency to obtain a large ultrasonic vibration due to the resonance phenomenon. Similar to form. Further, by applying an AC voltage having a frequency close to the resonance frequency, a large ultrasonic vibration can be obtained by the resonance phenomenon, which is the same as the conventional embodiment. The vibrator 10 of the vibration wave motor of the present invention has a configuration including a diaphragm 1, piezoelectric elements 2A and 2B, protrusions 1a, and feeding means Pa and Pb.

Next, the secondary natural vibration mode of torsional vibration and the primary natural vibration mode of bending vibration generated by the vibrator 10 of the present embodiment will be described in detail. FIG. 3A shows a plan view of the vibrator 10 in which the polarization regions of the piezoelectric elements 2A and 2B, the power feeding means Pa, Pb, and the like are omitted. FIG. 3B shows a front view of the oscillator 10. FIG. 3C shows a conceptual diagram of the secondary natural vibration mode of the torsional vibration in the direction D1 parallel to one side of the diaphragm 1 as viewed from the direction of the arrow d1. FIG. 3D shows a perspective view showing vibration in a secondary natural vibration mode of torsional vibration. FIG. 3E shows a conceptual diagram of the secondary natural vibration mode of the torsional vibration in the direction D2 parallel to one side of the diaphragm 1 as viewed from the direction of the arrow d2. FIG. 3F shows a conceptual diagram of the primary natural vibration mode of bending vibration in the direction D1 parallel to one side of the diaphragm 1 as viewed from the direction of arrow d1. FIG. 3 (g) shows a perspective view showing the vibration of the primary natural vibration mode of the bending vibration. In addition, in FIGS. 3C, 3E, and 3F, the description of the protrusion 1a and the piezoelectric elements 2A and 2B is omitted.

In the generation of the secondary natural vibration mode of the torsional vibration as shown in FIGS. 3 (c) and 3 (d), the torsion center axis Ma1 (first) observed in the direction of the arrow d2 of FIG. 3 (e). Section) occurs and is shown as a alternate long and short dash line in FIG. 3 (a). On the other hand, the second node Mb1 is generated in the direction orthogonal to the torsion center axis Ma1 observed in the direction of arrow d1 in FIG. 3C, and is shown as a broken line in FIG. 3A. Further, in the generation of the primary natural vibration mode of bending vibration as shown in FIGS. 3 (f) and 3 (g), node Na1 and antinode Na2 observed in the direction of arrow d1 are generated, and FIG. It is shown as a alternate long and short dash line in (a). The amount of deformation of the diaphragm 1 is small in the vicinity of these vibration nodes but large in the vicinity of the vibration antinodes.

Here, the region where the connecting portions 1c1 and 1c2 are provided is on the torsion center axis Ma1 (first section) of the secondary natural vibration mode of the torsional vibration, referring to FIG. 3A. Above the second node Mb1 and the node Na1 in the primary natural vibration mode of the bending vibration. As described above, since the connecting portions 1c1 and 1c2 are provided in the region where the amount of deformation is small in the vibration of the diaphragm 1 and the piezoelectric elements 2A and 2B, the vibration of the diaphragm 1 is less likely to be hindered. The connecting portions 1c1 and 1c2 are not limited to the positions shown in FIG. 3A as long as they are in the vicinity of these vibration nodes. Further, since the connecting portions 1c1 and 1c2 need only be provided in a region where the amount of deformation of the diaphragm 1 is relatively small, the positions of the connecting portions 1c1 and 1c2 are not limited to the positions of these vibration nodes.

Hereinafter, the vibrator 10 of the vibration wave motor of the present embodiment will be described with three features related to vibration. The first feature relating to vibration will be described below with reference to FIGS. 3 (a) to 3 (g). One of the natural vibration modes that coincides with or has adjacent resonance frequencies in the secondary natural vibration mode of the torsional vibration in direction D1 is the torsional central axis of the secondary natural vibration mode of the torsional vibration. This is a primary natural vibration mode of bending vibration in the direction D1 parallel to Ma1. This feature is the dimensions of the directions D1 and D2 of the diaphragm 1, the dimensions of the region W, the dimensions of the notches 1b1 and 1b2, the thickness of the diaphragm 1 and the piezoelectric elements 2A and 2B, and the diaphragm 1 and the piezoelectric element 2A. This can be achieved by setting each design value such as the rigidity of 2B to an appropriate value. It should be noted that the appropriate combination of these design values is not one, and various combinations can be set.

As shown in FIGS. 3A, 3B, and 3E, the second characteristic of vibration is that the protrusion 1a has a torsion center axis Ma1 (from the second section Mb1 of the secondary natural vibration mode of torsional vibration). It is provided near the first section). In the example of FIG. 3A, the protrusion 1a coincides with the twist central axis Ma1 (first node), and is the optimum form provided at the position farthest from the second node Mb1.

As shown in FIGS. 3A and 3B, the third feature related to vibration is that the protrusion 1a changes from the node Na1 to the antinode Na2 among the nodes Na1 and the antinode Na2 in the primary natural vibration mode of bending vibration. It is provided at a close position. In the example of FIG. 3A, the protrusion 1a coincides with the belly Na2 and is the optimum form provided at the position farthest from the node Na1.

FIG. 4 shows the first embodiment together with a comparative example. FIG. 4A is a comparative example in which the dimension of the direction D1 is reduced in order to reduce the size of the vibrator of the vibration wave motor as compared with the conventional vibrator. However, in this comparative example, the flat portion of the diaphragm is almost entirely covered by the piezoelectric element 2. FIG. 4B is a comparative example in which the above-mentioned region W is provided for the configuration of the piezoelectric element 2 of FIG. 4A, that is, an example in which the first feature relating to the structure is reflected. FIG. 4C shows the diaphragm 1 of FIG. 1 which is the first embodiment, and in addition to the first feature relating to the structure, a straight line L passing through the region W and parallel to the direction D1 of the diaphragm 1 is formed. This is an example in which a structure having notches 1b1 and 1b2 of the diaphragm 1 along the same, that is, the second feature of the structure is reflected. 4 (a1), (b1), and (c1) are all plan views.

4 (a2), (b2), and (c2) are conceptual diagrams showing a secondary natural vibration mode of torsional vibration in the direction D1 of the diaphragm, and FIGS. 4 (a3), (b3), and (c3). ) Is a conceptual diagram showing a primary natural vibration mode of bending vibration in the direction D1 of the diaphragm. 4 (a4), (b4), and (c4) are perspective views showing a secondary natural vibration mode of torsional vibration, and FIGS. 4 (a5), (b5), and (c5) are bending vibrations. It is a perspective view which showed the 1st order natural vibration mode. The amount of deformation of the diaphragm is exaggerated. In the form shown in FIG. 4C and the like, the natural vibration mode in which the resonance frequency of the secondary natural vibration mode of the torsional vibration in the direction D1 of the vibrating plate matches or is adjacent to the natural vibration mode is the direction of the vibrating plate. It has the first characteristic related to vibration, which is the first natural vibration mode of the bending vibration of D1. This is because each design value is set to an appropriate value. Usually, the resonance frequency of the secondary natural vibration mode of the torsional vibration in the direction D1 of the vibrating plate is higher than the resonance frequency of the primary natural vibration mode of the bending vibration in the direction D1. This is because the rigidity of the former is high when the torsional rigidity and the bending rigidity in the direction D1 are compared. As described above, the flexural rigidity and the torsional rigidity mean the degree of difficulty in dimensional change with respect to the bending and torsional forces.

Comparing the torsional rigidity of the diaphragm direction D1 and the flexural rigidity of the diaphragm 1 direction D1 in the comparative example of FIG. 4A and the comparative example of FIG. 4B, both rigiditys are shown in FIG. The comparative example of 4 (b) is lower than the comparative example of FIG. 4 (a). This is because the comparative example of FIG. 4B has a region W which is the first feature related to the structure. Therefore, the resonance frequency of the comparative example of FIG. 4 (b) is lower than that of the comparative example of FIG. 4 (a). Generally, if the sizes of the vibrating bodies are the same, the oscillator having a lower resonance frequency has a larger vibration amplitude. Therefore, if vibration can be performed at a lower frequency, almost the same vibration amplitude can be obtained even if the vibrator of the vibration wave motor is miniaturized. Therefore, it is advantageous for the miniaturization of the vibration wave motor to vibrate at a lower frequency with respect to the two resonance frequencies used for driving.

Next, comparing the torsional rigidity of the direction D1 of the diaphragm 1 between the comparative example of FIG. 4 (b) and the first embodiment of FIG. 4 (c), the first embodiment of FIG. 4 (c) is compared. Is lower than that of the comparative example of FIG. 4 (b). Further, when comparing the resonance frequencies of the secondary natural vibration modes of the torsional vibration in the direction D1 of the diaphragm 1, the first embodiment of FIG. 4 (c) is lower than the comparative example of FIG. 4 (b) ( See later in FIGS. 4 (b6) and 4 (c6)). Considering this, the first embodiment of FIG. 4 (c) has notches 1b1 and 1b2, which are the second features related to the structure, and in FIG. 4 (b4), stress due to torsional deformation is obtained. This is because the portion P where the stress is concentrated is notched in FIG. 4 (c4).

Further, comparing the resonance frequencies of the first-order natural vibration modes of the bending vibration in the direction D1 of the diaphragm 1 between the comparative example of FIG. 4 (b) and the first embodiment of FIG. 4 (c), FIG. The first embodiment of FIG. 4 (c) is higher than the comparative example of (b) (see later, FIGS. 4 (b6) and (c6)). Considering this, in the comparative example of FIG. 4B, the dimension corresponding to the total length of the beam in the primary natural vibration mode of the bending vibration in the direction D1 of the diaphragm is one perfect side. On the other hand, in the first embodiment of FIG. 4C, since a part is cut out by the cutout portions 1b1 and 1b2, the dimension corresponding to the total length of the beam is substantially shortened.

FIG. 4 (b6) shows a comparative example of FIG. 4 (b), and FIG. 4 (c6) shows the distribution of the resonance frequency in the first embodiment of FIG. 4 (c). Resonance frequency. FIG. 4 (b6) shows a comparative example, the secondary resonance frequency fb2 of the torsional vibration of FIG. 4 (b4) and the primary resonance frequency fb1 of the bending vibration of FIG. 4 (b5), respectively. .. 4 (c6) shows the secondary resonance frequency fc2 of the torsional vibration of FIG. 4 (c4) and the primary resonance frequency fc1 of the bending vibration of FIG. 4 (c5), which are the first embodiments, respectively. Has been done. By realizing the configuration of the present invention, the secondary resonance frequency fb2 of the torsional vibration of the comparative example is lowered to the secondary resonance frequency fc2 of the torsional vibration of the first embodiment. On the other hand, the primary resonance frequency fb1 of the bending vibration of the comparative example rises to the primary resonance frequency fc1 of the bending vibration of the first embodiment. As a result, in the first embodiment of FIG. 4 (c), the secondary resonance frequency fc2 of the torsional vibration and the primary resonance frequency fc1 of the bending vibration are brought closer to each other with respect to the comparative example of FIG. 4 (b). be able to.

Generally, when a vibrating body having adjacent resonance frequencies is driven at a frequency in the vicinity of the resonance frequency, the vibration amplitude of the vibrating body becomes large. Therefore, if the two resonance frequencies used for driving can be vibrated at frequencies closer to each other by satisfying the second characteristic related to the structure, almost the same vibration amplitude can be obtained even if the vibration wave motor is miniaturized. Can be done. As a result, it is advantageous for miniaturization of the vibration wave motor.

FIG. 5A shows a voltage waveform when the phase of the B phase is delayed by about + 90 ° with respect to the A phase with respect to the AC voltage applied to the piezoelectric elements 2A and 2B. 5 (b) is a plan view corresponding to FIG. 1 (a), FIG. 5 (c) is a front view corresponding to FIG. 1 (b), and FIG. 5 (d) is FIG. In the cross-sectional view taken along the cross-sectional line (d)-(d) of (c), the change in vibration P1-P4 corresponding to the change in time to time T1-T4 is shown. The description of the piezoelectric elements 2A and 2B is omitted. Further, with respect to the change in the electrical AC voltage at the time T1-T4 shown in FIG. 5 (a), the change in mechanical vibration P1-P4 shown in FIGS. 5 (c) and 5 (d) is predetermined. It changes with the mechanical response delay time of. Also, the amplitude of vibration is exaggerated.

After a predetermined mechanical response delay time from when voltages of the same sign are applied to the A phase and the B phase (time T2, T4), the A phase and the B phase expand and contract in the same manner, and the first order of bending vibration occurs. The amplitude of the natural vibration mode is maximized (see (i) in FIG. 5 (d)). On the contrary, after a predetermined mechanical response delay time from when a voltage having a different sign is applied to the A phase and the B phase (time T1, T3), the A phase and the B phase expand and contract in opposite directions, and the torsional vibration occurs. The amplitude of the secondary natural vibration mode is maximized (see (ii) in FIG. 5 (d)). As a result, a circular motion as shown in the figure is generated at the tip of the protrusion 1a, so that a propulsive force can be obtained in the direction of arrow X. Further, when the phase of the B phase is advanced by about + 90 ° with respect to the A phase and an AC voltage is applied, a circular motion in the opposite direction to that of FIG. 5 is generated, so that a propulsive force in the opposite direction can be obtained.

FIG. 6A shows a voltage waveform of the AC voltage applied to the piezoelectric elements 2A and 2B when the phase of the B phase is substantially not delayed with respect to the A phase. 6 (b) is a plan view corresponding to FIG. 1 (a), FIG. 6 (c) is a front view corresponding to FIG. 1 (b), and FIG. 6 (d) is FIG. In the cross-sectional view taken along the cross-sectional line (d)-(d) of (c), the change in vibration P5-P8 corresponding to the change in time to time T5-T8 is shown. Compared with the case shown in FIG. 5 (a), since there is almost no time when the voltage of different sign is applied to the A phase and the B phase, the amplitude of the secondary natural vibration mode of the torsional vibration is very small. (See (ii) in FIG. 6 (d)). As a result, a vertically long elliptical motion as shown in the figure is generated at the tip of the protrusion 1a, so that a propulsive force can be obtained in the direction of arrow X, and the propulsive force can move the vibrator at a very low speed. ..

Hereinafter, the effect of the present invention will be discussed by comparing the vibrator 10 of the vibration wave motor of the first embodiment and the vibrator of the vibration wave motor of the conventional embodiment with FIGS. 5 and 7. The vibrator of the conventional vibration wave motor shown in FIG. 7B travels in the direction of arrow X, which is a direction parallel to the long side L5, whereas the vibrator 10 of the first embodiment is conventional. It travels in a direction parallel to one side (in the direction of arrow X in FIG. 5), which is shorter than the direction parallel to the long side L5, which is the traveling direction of Therefore, the dimension of the vibration wave motor in the traveling direction can be shortened. Further, the piezoelectric elements 2A and 2B of the first embodiment have a smaller area than the piezoelectric elements of the conventional vibration wave motor. However, the oscillator 10 of the first embodiment has two resonance frequencies used for driving lower and closer to each other by satisfying the first feature related to the above-mentioned structure and the second feature related to the structure. The frequency can satisfy the first characteristic of vibration. Therefore, since a vibration amplitude close to that of the conventional vibration wave motor ((ii) in FIG. 5D) can be obtained, a propulsive force equivalent to that of the conventional vibration wave motor can be obtained. As a result, it is possible to travel along a shorter side than the conventional form without significantly impairing the propulsive force. Therefore, the dimension of the vibration wave motor in the traveling direction is shortened, and by using this vibration wave motor, the size of the drive device can be reduced. Can be achieved. In the first embodiment, an example in which the secondary natural vibration mode of torsional vibration and the primary natural vibration mode of bending vibration are combined is shown, but if the above characteristics are satisfied, the higher order is obtained. The same effect can be obtained by combining the natural vibration modes of.

FIG. 8 (a) shows a schematic view of the linear drive device 100 using the vibration wave motor of the present invention as viewed from the traveling direction of the vibration wave motor, and FIG. 8 (b) shows FIG. 8 (b). The cross-sectional view in the cross-sectional line (b)-(b) of a) is shown. The friction member 3 comes into contact with the protrusion 1a of the diaphragm 1, and the vibrator 10 moves relative to each other due to the ultrasonic vibration of the diaphragm 1. The vibrating plate 1 can move relative to the friction member 3 in a direction orthogonal to the torsional central axis Ma1 of the substantially rectangular surface of the vibrating plate 1. The holding member 4 is connected to the connecting portions 1c1 and 1c2 of the diaphragm 1 at the ends 4d1 and 4d2 of the support portion 4a to support the diaphragm 1. Then, in the shaft portion 4b, a roller 101 that rotates and slides on the back surface of the friction member 3 is rotatably supported. That is, the holding member 4 is a member that moves in synchronization with the diaphragm 1. The lower end of the pressure spring 102 acts on the piezoelectric elements 2A and 2B, and the upper end acts on the holding member 4 at the receiving portion 4c. The drive transmission unit 103 is a member that connects the holding member 4 and the driven body described later.

The protrusion 1a is pressed against the friction member 3 by the pressing force of the pressure spring 102, and the holding member 4 is moved in the X direction of FIG. 8B by the driving force due to the circular motion as shown by the arrows shown in FIGS. Get propulsion. The roller 101 is provided to reduce the sliding resistance during driving, and may be a mechanism such as a rolling ball. Further, if sliding resistance is allowed, sliding may be performed directly by sliding friction. With such a configuration, in the linear drive device 100 of FIG. 8, the vibrator 10 of the vibration wave motor is driven in the direction D2 orthogonal to the torsion center axis Ma1 of the substantially rectangular surface of the diaphragm 1.

As described above, the vibrator 10 of the vibration wave motor of the first embodiment has a lower two resonance frequencies used for driving by satisfying the first feature related to the structure and the second feature related to the structure. And the frequencies are closer to each other. As a result, the size of the vibration wave motor in the traveling direction is shortened without impairing the propulsive force, and by using this vibration wave motor, it is possible to achieve miniaturization of the linear drive device.

FIG. 9 (a) shows a front view of the lens drive unit of the lens drive device 200 equipped with the linear drive device 100 using the vibration wave motor of the present invention in the optical axis direction, and FIG. 9 (b) shows. , (C) show a side view in which a part of the frame body 201 is removed. Note that FIG. 9C is a lens driving device 200 that is further miniaturized with respect to FIG. 9B. The frame body 201 fixes the friction member 3. The lens 202 is held in the lens holder 203. The lens holder 203 is supported by the guide shaft 204 and the guide shaft 205, and is further guided in the optical axis direction (arrow X direction). In the linear drive device 100 in FIG. 9B, the description of members other than the diaphragm 1 and the friction member 3 is omitted.

The diaphragm 1 moves along the friction member 3 fixed to the frame body 201, and the holding member 4 moves in synchronization with this movement. The lens holder 203 is a driven body connected to the holding member 4 by the drive transmission unit 103, and moves in synchronization with the holding member 4. The lens holder 203 can be moved to the distance L1 by moving the holding member 4 by a considerable distance in the X direction in accordance with a movement command from a microcomputer (not shown). With such a configuration, in the lens driving device 200 of FIG. 9, the driving direction of the vibration wave motor is the direction D2 orthogonal to the torsion center axis Ma1 of the substantially rectangular surface of the diaphragm 1.

As described above, the lens drive device 200 can be downsized by using the vibration wave motor of the first embodiment. In the first embodiment, the example in which the diaphragm 1 moves along the fixed friction member 3 has been described, but even if the friction member 3 moves along the fixed diaphragm 1. , It is possible to realize miniaturization, and the same effect is achieved.

A modified example of the first embodiment of the present invention is shown in FIG. In FIGS. 10 (a1) to 10 (c1), the piezoelectric elements 2A and 2B included in the vibrators 11 to 13 of the vibration wave motor are the piezoelectric elements divided into two, and are the same as those in the first embodiment. .. In FIGS. 10 (d1) and 10 (e1), the piezoelectric elements 14A and 15A included in the vibrators 14 and 15 of the vibration wave motor are integrated piezoelectric elements. The vibrators 11 to 15 of the vibration wave motor all have the above-mentioned region W, and the vibrators 11 to 14 of the vibration wave motor are provided with notches in the vicinity of each region W. In the vibrator 15 of the vibration wave motor, the region W is provided in a substantially rectangular shape in the central portion of the diaphragm 15-1, and the cutout portions 15b1 and 15b2 are not provided in the vicinity of the region W. .. Further, each region W is substantially axisymmetric with respect to a straight line L parallel to the direction D1 parallel to one side of each diaphragm. Further, each notch portion is substantially symmetrical with respect to a straight line L parallel to the direction D1 parallel to one side of each diaphragm.

The features of the above-mentioned modification will be described below. One notch portion 11b1 included in the vibrator 11 of the vibration wave motor is provided in the diaphragm 11-1, and has a relatively horizontally long shape. The notch portions 12b1 and 12b2 of the vibrator 12 are provided one on each side of the diaphragm 12-1 and on the same axis. The notch portions 13b1 and 13b2 of the vibrator 13 are provided on the left and right sides of the diaphragm 13-1 and on different axes. The notches 14b1 and 14b2 of the vibrator 14 are provided on the left and right sides of the diaphragm 14-1 and on the same axis, and the integrated piezoelectric element 14A is provided on the diaphragm 14-1. It has a shape confined in the D1 direction to form the region W. The notches 15b1 and 15b2 of the vibrator 15 are provided on the left and right sides of the diaphragm 15-1 on the same axis, and the integrated piezoelectric element 15A has a region W in the center thereof. It has the shape of a substantially rectangular opening for forming.

As shown in FIGS. 10 (a2) to 10 (e2), for all the diaphragms, the convex entourage of the entire region covered by the piezoelectric element in the plane to which the piezoelectric element is attached (the rectangle shown by the dotted line S in the figure). A region W (two-dot chain line region in the figure) that is not covered with the piezoelectric element is provided inside the. Further, a notch portion of the diaphragm is provided along a straight line L (one-dot chain line in the figure) passing through the region W and parallel to one side of the diaphragm. Therefore, all modifications have a first feature relating to the structure and a second feature relating to the structure. As a result, the two resonance frequencies used for driving can satisfy the first characteristic relating to the above-mentioned vibration at frequencies smaller and closer to each other, and are equivalent to the vibration wave motor of the first embodiment. The effect is obtained. Although the piezoelectric element is divided into two, the piezoelectric element is not limited to two, and it is possible to have two or more piezoelectric elements.

(Second embodiment)
Hereinafter, a second embodiment for carrying out the present invention will be described. 11 (a) to 11 (h) are diagrams showing the vibrator 20 of the vibration wave motor of the second embodiment, and the differences from the first embodiment will be described below. The piezoelectric elements 22A and 22B are attached to the surface of the diaphragm 21 opposite to the protrusion 21a, and ultrasonically vibrate by applying an AC voltage. In the piezoelectric elements 22A and 22B, two regions of 22Aa and 22Bb are polarized in the same direction, and 22Aa is assigned to the A phase and 22Bb is assigned to the B phase. Unlike the first embodiment, there are no unpolarized regions and no folded electrodes. Therefore, the diaphragm 21 itself is grounded via the surfaces 22Ad and 22Bd to which the piezoelectric elements 22A and 22B and the diaphragm 21 are attached. As a result, ultrasonic vibration can be generated by applying an AC voltage whose phase is freely changed to the A phase and the B phase by the feeding means Pa and Pb via the diaphragm 21. The other two features related to the structure, the three features related to vibration, and the like are the same as those in the first embodiment.

Even with such a configuration, as in the first embodiment, the dimensions of the vibrator 20 of the vibration wave motor in the traveling direction are shortened without impairing the propulsive force, and the vibrator 20 of the vibration wave motor is used. Thereby, the miniaturization of the lens driving device can be achieved. The modified examples of the embodiment are the same as those of the first embodiment.

(Third embodiment)
Hereinafter, a third embodiment for carrying out the present invention will be described. 12 (a) to 12 (h) are diagrams showing the vibrator 30 of the vibration wave motor of the third embodiment, and the differences from the first embodiment will be described below. The range shown by the dotted line is the connecting portions 31c1, 31c2, 31c3, and 31c4 that are directly or indirectly connected to the above-mentioned holding member 4 (not shown) that moves in synchronization with the diaphragm 31. .. It is conceivable that the connecting portions 31c1 to 31c4 are not only simply connected but also pressurized by a spring or the like. Unlike the first embodiment, the connecting portions 31c1 to 31c4 are provided at the edge portion of the diaphragm 31.

The portions where the connecting portions 31c1 to 31c4 are provided are in the vicinity of the second section Mb1 of the secondary natural vibration mode of torsional vibration and the section Na1 of the primary natural vibration mode of bending vibration. As described above, since the connecting portions 31c1 to 31c4 are provided in the portions where the amount of deformation is small in the vibration between the diaphragm 31 and the piezoelectric elements 32A and 32B, the vibration of the diaphragm 31 is less likely to be hindered. The connecting portions 31c1 to 31c4 are limited to the positions shown in FIG. 12 as long as they are in the vicinity of the second section Mb1 of the secondary natural vibration mode of torsional vibration and the section Na1 of the primary natural vibration mode of bending vibration. Will not be done. Further, since the connecting portions 31c1 to 31c4 need only be provided at the portion where the amount of deformation is small in the vibration of the diaphragm 31 and the piezoelectric elements 32A and 32B, the position of the connecting portion 31c1 to 31c4 is not limited to the position of the vibration node. In addition, two features related to the structure, three features related to vibration, and the like are the same as those in the first embodiment.

Even with such a configuration, as in the first embodiment, the dimensions of the vibrator 30 of the vibration wave motor in the traveling direction are shortened without impairing the propulsive force, and the vibrator 30 of the vibration wave motor is used. Thereby, the miniaturization of the lens driving device can be achieved. The modified examples of the embodiment are the same as those of the first embodiment.

(Fourth Embodiment)
Hereinafter, a fourth embodiment for carrying out the present invention will be described. 13 (a) to 13 (h) are diagrams showing the vibrator 40 of the vibration wave motor of the fourth embodiment, and the differences from the first embodiment will be described below. The piezoelectric element 42 is attached to the diaphragm 41 and ultrasonically vibrates by applying an AC voltage. In the piezoelectric element 42, two regions 42a and 42b are polarized in the same direction, of which 42a is assigned to the A phase and 42b is assigned to the B phase. The unpolarized region 42c is an electrode used as a ground conducted from the entire surface electrode of the back surface 42d of the piezoelectric element 42 via the side surface. One protrusion 421a is adhered to the piezoelectric element 42. Further, two regions W not covered by the piezoelectric element are provided. In addition, two features related to the structure, three features related to vibration, and the like are the same as those in the first embodiment.

Even with such a configuration, as in the first embodiment, the dimension of the vibration wave motor in the traveling direction is shortened without impairing the propulsive force, and by using this vibration wave motor, the lens driving device is made smaller. Can be achieved. The modified examples of the embodiment are the same as those of the first embodiment.

(Fifth Embodiment)
Hereinafter, a fifth embodiment for carrying out the present invention will be described. 14 (a) to 14 (h) are views showing the vibrator 50 of the vibration wave motor of the fifth embodiment, and FIG. 15 is an enlarged view of the diaphragm 51 of the vibration wave motor of the fifth embodiment. 14 (e) is an enlarged view. The range shown by the dotted line is the connecting portions 51c1 and 51c2 that are directly or indirectly connected to the above-mentioned holding member 4 (not shown) that moves in synchronization with the diaphragm 51. It is the same as the embodiment of. Hereinafter, only the differences from the first embodiment will be described.

As shown in FIG. 15, notches 51b1 and 51b2 are provided on the diaphragm 51 so as to face each other. Since the notch portion 51b2 has the same characteristics as the notch portion 51b1, the characteristics of the notch portion 51b1 will be described in detail below. In the direction D1 orthogonal to the direction D2 parallel to one side of the diaphragm 51 provided with the notch 51b1, the notch 51b1 has a shape having two tops. Between the two tops of the notch 51b1, a central vicinity portion having a dimension C5 shorter than the dimension S5 from one side to the two tops of the diaphragm 51 provided with the notch 51b1 is formed. The same applies to the notch portion 51b2.

When the dimension of the direction D1 of the notch portion 51b1 is large, the portion where the stress is concentrated due to the torsional deformation is largely notched, so that the resonance frequency fc2 of the secondary natural vibration mode of the torsional vibration is lowered. As described in the embodiment. Further, as the dimension of the direction D1 of the notch portion 51b1 becomes larger, the dimension corresponding to the total length of the beam becomes substantially shorter, so that the resonance frequency fc1 of the primary natural vibration mode of bending vibration rises. As described in one embodiment. As a result, these two resonance frequencies can be brought close to each other, which is an advantage for miniaturization of the vibration wave motor.

If the dimension of the direction D1 of the notch portion 51b1 is simply increased, the ends 4d1 and 4d2 of the support portion 4a of the holding member 4 illustrated in the first embodiment are connected to the connecting portions 51c1 and 51c2 of the vibrating plate 51. The following two problems may occur when fixing. The first problem is that when the cutout portion 51b1 reaches the vibration node, the connecting portions 51c1 and 51c2 cannot be provided in the vibration node, and the connecting portions 51c1 and 51c2 are provided in the region having the amount of vibration deformation. This means that the vibration of the diaphragm 51 is hindered. The second problem is that when fixing the ends 4d1 and 4d2 of the support portion 4a of the holding member 4 to the connecting portions 51c1 and 51c2 of the diaphragm 51, considering the protrusions 51a, it is sufficient to fix them by welding or adhesion. It is not possible to secure a large area.

However, in the present embodiment, the shape of the notch portion 51b1 in the direction D1 orthogonal to the direction D2 parallel to one side of the diaphragm 51 cut out by the notch portion 51b1 is the shape of the two tops of the notch portion 51b1. The shape of the dimension C5 near the center is shorter than that of the dimension S5. As a result, since the dimensions S5 of the two tops of the notch portion 51b1 are long, it is possible to obtain the effect of lowering the resonance frequency fc2 of the secondary natural vibration mode of the torsional vibration. At this time, even if the dimension C5 near the center is short, this portion is on the torsion center axis Ma1 (first node) of the secondary natural vibration mode of the torsional vibration and does not vibrate. The effect of the second-order natural vibration mode on the resonance frequency fc2 is small. Further, since the dimension C5 of the notch portion 51b1 near the center is short, the connecting portions 51c1 and 51c2 can be provided in the vibration node, and even if the protrusion 51a is taken into consideration, it can be fixed by welding or adhesion. A sufficient area can be secured. In addition, two features related to the structure, three features related to vibration, and the like are the same as those in the first embodiment.

Even with such a configuration, as in the first embodiment, the size of the vibrator 50 of the vibration wave motor in the traveling direction is shortened without impairing the propulsive force, and the vibrator 50 of the vibration wave motor is used. Thereby, the miniaturization of the lens driving device can be achieved. The modified examples of the embodiment are the same as those of the first embodiment.

The present invention can be used in electronic devices that are required to be compact, lightweight, and have a wide drive speed range, particularly a lens drive device and the like.

1 Diaphragm 1a, 421a Protrusion 1b1, 1b2 Notch 1c1, 1c2 Connecting part 2A, 2B Piezoelectric element 3 Friction member 4 Holding member W region L Straight line Ma1 Torsion center axis (first section)
Mb1 Second section

Claims (14)

A diaphragm with a substantially rectangular outer shape and
A piezoelectric element that is attached to the diaphragm and vibrates,
In a vibration wave motor with
The diaphragm has a region not covered with the piezoelectric element inside a rectangular region including the piezoelectric element in a plane to which the piezoelectric element is attached.
The diaphragm has a notch in the region not covered by the piezoelectric element.
The diaphragm or the piezoelectric element is provided with protrusions, and the protrusions perform elliptical motion due to vibrations having different phases of the piezoelectric elements.
The notch portion has a first notch region on one of the two opposing sides in the substantially rectangular outer shape and a second notch region on the other, and the first notch in the diaphragm. A vibration wave motor, wherein the region between the notched region and the second notched region includes a vibration node of the diaphragm. The notch portion passes through the region and is along a straight line parallel to any side of the outer shape of the diaphragm, and the region is substantially axisymmetric with respect to the straight line. Item 2. The vibration wave motor according to item 1. The notch portion passes through the region and is along a straight line parallel to any side of the outer shape of the diaphragm, and the notch portion is substantially line-symmetrical with respect to the straight line. , The vibration wave motor according to claim 1 or 2. The vibration wave motor according to any one of claims 1 to 3, wherein the vibration wave motor has two or more of the piezoelectric elements. Regarding the natural vibration mode of the vibration wave motor in which the diaphragm, the piezoelectric element, and the protrusion are integrally formed.
One of the natural vibration modes that matches the resonance frequency of the natural vibration mode of the torsional vibration or has adjacent resonance frequencies is the natural vibration of the bending vibration in the direction parallel to the torsion center axis of the natural vibration mode of the torsional vibration. Vibration mode,
Of the first node which is the torsion center axis and the second node in the direction orthogonal to the torsion center axis in the natural vibration mode of the torsion vibration, the position is closer to the first node than the second node. ,
The vibration according to any one of claims 1 to 4, wherein the protrusion is provided at a position closer to the belly than the node of the natural vibration mode of the bending vibration. Wave motor. The natural vibration mode of the torsional vibration is a secondary natural vibration mode of the torsional vibration.
The vibration wave motor according to claim 5, wherein the natural vibration mode of the bending vibration is a primary natural vibration mode of the bending vibration. The vibration wave motor according to any one of claims 1 to 6, wherein the protrusion is provided on a substantially rectangular surface of the diaphragm. The feature is that a connecting portion that is directly or indirectly connected to the holding member that moves in synchronization with the diaphragm is provided in a region of the diaphragm that is not covered by the piezoelectric element. The vibration wave motor according to any one of claims 1 to 7. 8. Claim 8 is characterized in that a connecting portion that is directly or indirectly connected to the holding member that moves in synchronization with the diaphragm is provided in the notch portion of the diaphragm. The vibration wave motor described in. Claims 1 to 9 are characterized in that the notch portion has a shape having two tops in a direction orthogonal to a direction parallel to one side of the diaphragm provided with the notch portion. The vibration wave motor according to any one of the above items. The claim is characterized in that a connecting portion that is directly or indirectly connected to the holding member that moves in synchronization with the diaphragm is provided in the vicinity of the center of the notch portion. 10. The vibration wave motor according to 10. The vibration wave motor according to any one of claims 1 to 11, wherein the diaphragm moves along a fixed friction member. The vibration wave motor according to any one of claims 1 to 12, wherein the vibration wave motor is an ultrasonic motor in which the vibration is ultrasonically vibrated. A drive device according to any one of claims 1 to 13, wherein the vibration wave motor is used.

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