JP7516222B2 - Vibration Actuator - Google Patents

Description

The present invention relates to a so-called vibration actuator that frictionally drives a driven body by pressurizing it against a vibrating body, and in particular to pressure support of the vibrating body of a vibration actuator.

A vibration actuator has a vibrating body composed of an electro-mechanical energy conversion element such as a piezoelectric element and an elastic body, and a contact body that comes into pressure contact with the vibrating body. A vibration actuator is used as a vibration wave motor that moves the contact body relative to the vibration body by utilizing friction generated by the driving force of vibration excited in the vibrating body. One type of vibration actuator is a circular vibration wave motor. A circular vibration wave motor has a lens attached to its hollow section and is used to move the lens for the autofocus or zoom function of a camera, or as a drive source for panning and tilting by passing wiring through the hollow section.

The structure and driving principle of a circular vibration wave motor, which is a type of vibration actuator, are outlined below. A circular vibration wave motor has a circular vibrating body and a circular contact body that is in pressure contact with the vibrating body by a pressure member. In order for the pressure member to uniformly pressurize the vibrating body, it is desirable for the rigidity of the pressure member to be increased when in contact with the vibrating body. However, if a highly rigid member comes into contact with the vibrating body, there is a risk that the vibration of the vibrating body will be hindered. Therefore, a structure is known in which a member that does not hinder vibration is placed between the pressure member and the vibrating body as a vibration damping member or the like.

For example, Patent Document 1 lists sponge, polystyrene foam, and felt as possible materials for the support of the vibrating body, and states that wool felt is particularly excellent among them. The support of the vibrating body in Patent Document 1 is made of a material that does not impede vibration, and has the same function as a vibration damping material.

Patent Document 2 also describes an example in which a foamable resin made of silicone rubber or the like is used as a vibration isolating member, although it is not annular. Patent Document 2 also has a vibration isolating member disposed between the vibrator and the pressure member, and the concept is similar.

However, according to the inventor's research, it was found that it is difficult to generate sufficient output with a vibration actuator that has a sponge or foam material between the vibrator and the pressure member, as described in the patent document. In addition, if felt is used, there is a risk that the output will decrease due to aging, such as the felt being crushed.

Japanese Patent Application Publication No. 3-289371 JP2015-146718Publication

In response to the above problems, the present invention aims to provide a vibration actuator that provides stable and sufficient output over a long period of time in a configuration in which a foam member is placed between a vibrating body and a pressure member.

The vibration actuator of the present invention comprises: a vibrator having an elastic body and an electromechanical energy conversion element;
a contact body that is in contact with the vibrating body and moves relatively to the vibrating body;
A pressure member that applies pressure to the vibration body;
a foam member provided between the pressure member and the vibration body,
The foamed material is characterized in that the cells have an average equivalent circle diameter of 70 μm or more and 105 μm or less .

According to the present invention, the contact area between the foamed material and the vibrating body can be reduced and the spring properties of the foamed material can be effectively utilized, so that sufficient output can be obtained without the foamed material impeding the vibration of the vibrating body. In addition, by appropriately selecting the average circular equivalent diameter of the cells of the foamed material, it is possible to suppress the collapse of the foamed material and maintain good characteristics for a long period of time.

1 is a cross-sectional view of a vibration actuator according to a first embodiment of the present invention. 3A and 3B are diagrams showing a fixed state of a vibrating body of the vibration actuator in the first embodiment of the present invention. 1A to 1C are diagrams illustrating a configuration in which a foam member is sandwiched between a vibrating body and a pressure member in a vibration actuator according to a first embodiment of the present invention. 1 is a graph comparing outputs as a result of examining foamed members according to the present invention. 1 is a table showing properties of a foam material according to the present invention. 1 is a graph comparing maximum speed values as a result of a study of foamed members according to the present invention. 1A is a graph showing the relationship between the density of each sample and the input power, and FIG. 1B is a graph showing the relationship between the average equivalent circular diameter of each sample and the input power. FIG. 2 is a schematic diagram illustrating a foam member according to the present invention. 4A to 4C are diagrams illustrating deformation of a foam member according to the present invention when pressure is applied thereto. 10(a) and (b) are side views of the foam member of the present invention. 1 is a cross-sectional view of a vibration actuator according to a second embodiment of the present invention, viewed from a direction perpendicular to the driving direction. FIG. 11 is an exploded view illustrating the configuration of a vibration actuator according to a second embodiment of the present invention. FIG. 13 is a diagram of a pan head device according to a third embodiment of the present invention. FIG. 13 is a diagram of a camera according to a fourth embodiment of the present invention. 10 illustrates a vibrating body according to a second embodiment of the present invention. 10A to 10C are diagrams illustrating vibration of a vibrating body in a second embodiment of the present invention.

[First embodiment]
1 is a cross-sectional view of a rotary vibration actuator according to a first embodiment of the present invention. The center line L1 is the axis of rotation of the rotary vibration actuator. A piezoelectric element 3, which is an electromechanical energy conversion element, is attached to the surface of the elastic body 2 opposite the surface that contacts the contact body 5, thereby constituting a vibrating body 1. The direction vector of the polarization axis of the piezoelectric material that constitutes this piezoelectric element may be configured to intersect with a foam member described below.

The contact body 5 is composed of a main body portion 5b and a contact portion 5a, which are joined by bonding, welding, or the like. In this embodiment, the main body portion 5b is made of a metal with excellent workability, such as brass. The contact portion 5a is made of hardened stainless steel, and has a thickness that gives it spring properties. This allows for stable contact with the vibrating body 1.

The vibrating body 1 is pressurized by a plurality of biasing members 11 against the contact body 5. Between the biasing members 11 and the vibrating body 1, a pressure receiving member 10 is provided to evenly transmit the biasing forces of the plurality of biasing members 11, and the biasing members 11 and the pressure receiving member 10 together constitute the pressure member 9. A foam member 8 is provided between the pressure member 9 and the vibrating body 1, which prevents the vibration excited by the vibrating body 1 from being transmitted to the pressure member and suppresses the generation of abnormal noise. Materials suitable for the foam member will be described later. In this embodiment, a coil spring is used as the biasing member 11, but a wave washer, a leaf spring, or the like may also be used as the biasing member.

The output unit 7 is fastened to the shaft 15 by a screw 18 so that it can rotate integrally with the shaft 15. The output unit 7 and the moving body 5 are connected by a rubber member 6 such as butyl rubber. Instead of the rubber member 6, it may be fixed by means of adhesion, screw fastening, or other means. The shaft 15 is supported by the support part 13 via two rotary bearings 17 so that it can rotate relatively. The outer ring sides of the two rotary bearings 17 are positioned in the direction of the rotation axis L1 by a protrusion 13a provided on the inner circumference side of the support part 13. The inner ring side of the rotary bearing 17 is positioned in the direction of the rotation axis L1 relative to the support part 13 by a slip-out prevention member 16. In this embodiment, a deep groove ball bearing is used as the rotary bearing 17, but other types of bearings such as a plain bearing or a thrust bearing may also be used.

Figure 2 is a perspective view showing the state in which the support 13 supports the vibrating body 1. The elastic body 2 has a number of protrusions 2a separated by a number of grooves 2b. The vibrating body 1 excites traveling wave vibration by applying an alternating current by an electrode (not shown), causing the protrusions 2a to undergo elliptical motion, and relatively rotates the contact body 5 (not shown), which is the driven body in pressure contact with the protrusions 2a. The elastic body 2 is made of a metal material such as stainless steel in a circular ring shape. In addition, the tip surface of the protrusions 2a is subjected to a hardening treatment such as nitriding or plating containing hard particles to increase durability (wear resistance).

In FIG. 2, multiple protrusions 19a on the positioning member 19 are inserted into grooves 2b on the elastic body 2. The positioning member 19 is fixed to the support 13 so that the elastic body 2 is positioned between the support 13 and the positioning member 19 in the Z-axis direction. This prevents the vibration body 1 from moving relative to the support 13 in the θ direction.

Figure 3 is a diagram for explaining the incorporation of the pressure mechanism of the vibration actuator in this embodiment. As shown in Figure 3, multiple protrusions 10a provided on the pressure receiving member 10 are inserted into the inner periphery of multiple biasing members 11. Furthermore, the multiple biasing members 11 are inserted into multiple holes 13a provided in the support portion 13, thereby positioning the biasing members 11 and the pressure receiving member 13 in the θ direction. Then, a foam member 8 is sandwiched between the pressure receiving member 10 and the vibrating body 1. The moving body 4 shown in Figure 1 (not shown) is fixed to the shaft 15, thereby bringing the vibrating body 1 and the contact body 5 into a state of pressure contact.

The characteristics of the foamed material 8 and the optimal foamed material will be described. In conventional vibration actuators, especially in annular vibration actuators, felt has been used as the material sandwiched between the vibrator 1 and the pressure member 9. The inventors focused on the output (speed and torque) of the vibration actuator characteristics when several types of foamed materials were incorporated into the same vibration actuator and compared them. A suitable material for the foamed material is one whose main component is a polymer with a siloxane bond (Si-O-Si) skeleton made of silicon and oxygen and a methyl group bonded to the skeleton. The foamed material may also be a sponge containing silicone rubber. Alternatively, the foamed material may be a sponge containing ethylene propylene diene rubber (EPDM) or a sponge containing acrylonitrile butadiene rubber (NBR).

The results of this study are shown in Figures 4 to 7. Figure 4 is a graph showing the relationship between the cell (air bubble) size of the foamed material and the maximum output (torque). In the study by the inventors, rubber sponge was selected as the foamed material, and several samples with different hardness and density were compared. Figure 5 is a table summarizing the characteristics of these samples, including cell size as well as differences in hardness and density. Figure 6 compares the maximum speed when each sample is driven with a constant load. Figure 7(a) is a graph showing the relationship between the density of each sample and the input power, and Figure 7(b) is a graph showing the relationship between the average circular equivalent diameter of each sample and the input power.

Here, the definition of the cell size of the foamed material will be explained. Figure 8 is a schematic diagram showing the state of the foamed material of the present invention observed under magnification with a microscope or the like. As shown in Figure 8, there are many cells 8a in the foamed material 8. The foamed material 8 is, for example, a rubber sponge, which is made by mixing a foaming agent into rubber and foaming it. In this embodiment, the pores generated by foaming are referred to as cells. In Figure 8, the cells 8a are generated by foaming, but are not spherical but have an indefinite shape. Therefore, the average circle equivalent diameter on a plane is calculated as an index of cell size. That is, image processing is performed on an image such as the schematic diagram shown in Figure 8 to calculate the cross-sectional area and number of each cell. The diameter when the calculated cross-sectional area of each cell is converted into a circle is calculated, and the average value of the diameters of each cell is defined as the average circle equivalent diameter in this embodiment. The average circle equivalent diameter calculated here is in an uncompressed state, and is in a compressed state when actually used.

As shown in FIG. 4, the maximum torque of silicone D and silicone E, in which the average equivalent circle diameter of the cells of the foamed material is less than 20 μm, did not reach the target torque. The average equivalent circle diameter in the range of 25 μm to 120 μm exceeded the target value and sufficient torque was obtained. The average equivalent circle diameter of the cells of the more preferable foamed material is in the range of 25 μm to 110 μm, and in particular, the average equivalent circle diameter in the range of 70 μm to 105 μm has the largest torque and is the most desirable characteristic. Note that this average equivalent circle diameter was calculated by the inventors from the results of observing the cross section using a microscope or the like. Therefore, it is easily affected by the brightness of the image when observing, and when the cells and the surface are separated by image processing for the observation results, a part of the cell may be included in the surface, or a part of the surface may be included in the cell, resulting in an error in the results. Therefore, the average value of the results obtained at two or more multiple sites, or the results of multiple measurements, is adopted as the average equivalent circle diameter of the cells of the foamed material.

Among the materials shown in Figure 4, silicone A, which has a larger bubble diameter, has a lower output torque, and it is thought that there are factors other than the average equivalent circle diameter that affect the improvement of output torque. However, those with an average equivalent circle diameter in the range of 25 μm to 120 μm were able to obtain sufficient output torque.

The results of comparing hardness and density are shown in Figure 5. In Figure 5, for example, when the hardness is indicated as 7±5, this means that the hardness was measured multiple times or at multiple locations, and the average value was 7, with the multiple measurement results each falling within the range of ±5.

As shown in Figure 5, Silicone A has a higher hardness than Silicone B and Silicone C, and is therefore more likely to inhibit the vibration of the vibrating body, which is thought to make it difficult to produce output. Also, a comparison of Silicone B and Silicone C in the graph shown in Figure 6 reveals that the maximum speed also decreases when the hardness is low. In the inventor's investigation, Silicone B with an Asker C hardness of 8±5 had the highest maximum speed, so a hardness of 8±5 was desirable. More preferably, the hardness of the foamed member is an average Asker C hardness of 7 or more and 10 or less.

In addition, there is also an index called porosity for evaluating the cells of the rubber sponge sample that was measured. Here, porosity represents the proportion of cells in the contact surface between the rubber sponge and the vibrator. When calculating the porosity, the surface is observed using a microscope or the like, and the proportion of cells in the observed surface is calculated, and the cell size does not affect the porosity. In the samples examined by the inventors, the porosity was the same for all samples, ranging from 66% to 80%, and no particular correlation was observed.

The porosity is generally a cross-sectional view of the cells contained in a foamed material, and is a two-dimensional representation of the proportion of cells contained, but it is thought to be the same value even when considering the occupancy rate in three dimensions. The density of a foamed material is the apparent density, and since the outer shape of the foamed material includes the cells, the density of the foamed material changes depending on the volume occupied by the cells, that is, the occupancy rate, and does not change with the cell size. In other words, for the same material, the higher the occupancy rate, the lower the density. In general, with rubber, it is possible to change the hardness by adding various compounding agents to the rubber material depending on the application, but the density also changes at that time. In other words, with foamed materials such as rubber sponge, the apparent density of the foamed material changes depending on the density of the material before foaming, that is, the hardness of the material and the occupancy rate of the cells, so it is difficult to distinguish the characteristics of the foamed material using only the apparent density as an indicator.

Next, the difference between silicone B and silicone E will be described from the viewpoint of the effect of cell size. As shown in Figure 5, silicone B and silicone E have the same hardness and density, but as shown in Figures 4 and 6, there is a difference in output torque and maximum speed. This is largely due to the effect of cell size, and is thought to be the difference between a foamed member containing a small number of large cells and a foamed member containing a large number of small cells. Below, we will explain this difference. Figure 9 is a schematic diagram showing the deformation around the cell when a surface load F is applied to the foamed member, and shows the cell 8 from the side. In Figure 9, the schematic diagram is drawn with the surface as flat, but in reality, there are small irregularities. The solid line represents the state before deformation, and the dashed line represents the state after deformation, and the amount of sinking of the surface is ΔT. As shown in Figure 9, the shape of the cell 8a visible in the surface layer sinks as it is with almost no change. Then, the cell 8b on the inside side deforms in the compression direction, and the cell 8b acts like a spring. Figure 9 shows the cells 8a and 8b near the surface, but in reality, many cells 8b exist inside and are compressed and deformed. At this time, if the hardness of the rubber sponge is about the same, the amount of compression of the cell increases in proportion to the cell size, resulting in a large displacement ΔT. In other words, when the cell size is small, the spring effect is small, hindering vibration. Therefore, the output is small for Silicone E and Silicone F, which have small cell sizes.

As explained above, the cells of the foam member 8 deform like springs, allowing the pressure force of the pressure member 9 to be transmitted to the vibrating body 1 without impeding the vibration of the vibrating body 1. At this time, the amount of deformation of the cells increases in proportion to the cell size, and the larger the cell size, the less likely it is to impede the vibration of the vibrating body 1. Therefore, in the studies conducted by the inventors, sufficient torque was obtained when cell sizes of approximately 25 μm to 100 μm were used.

The power measured for each sample was also compared. FIG. 7(a) is a graph showing the relationship between the density and the input power of each sample, and FIG. 7(b) is a graph showing the average circle equivalent diameter and the input power of each sample. As shown in FIG. 7(a), there are samples with the same density but with a larger input power, and a sample with a density of about 0.15 g/cm ³ has a larger input power than a sample with a density of just under 0.3 g/cm ³ , and no correlation is observed between density and input power. In contrast, in FIG. 7(b), the input power tends to be smaller for samples with a larger average circle equivalent diameter, so it can be said that the input power is smaller for samples with a larger average circle equivalent diameter.

Here, the definition of the thickness of the foamed member will be explained. FIG. 10(a) is a schematic diagram of a part of the foamed member 8 of this embodiment seen from the side. Many of the rubber sponges, which are the foamed members 8 observed in this embodiment, had cell holes 8a on the surface as shown in FIG. 10(a). In such foamed members 8, the thickness T of the foamed member 8 is taken as the distance from the contact surface 8b with the vibrator to the contact surface 8c with the pressure receiving member. A thickness gauge is generally used to measure the thickness, but since pressure is applied during measurement, there is a risk of deformation in soft foamed members 8. Therefore, a microgauge, calipers, or the like is used to measure the thickness when the foamed member 8 is pinched with a force that does not deform it. For example, the thickness is measured every 90° on the annular foamed member 8, and the average value of four points is calculated. The average of six or eight points may be used instead of four points. Alternatively, the thickness may be measured by observing from the thickness direction using a stereo microscope or the like, or the thickness may be measured using a non-contact measuring device such as a laser displacement meter. If a non-contact measuring device is used, the rubber sponge does not deform, so the measurement accuracy is high.

If the foamed member is smaller than 1 mm, the vibrating body 1 may be affected by the pressure receiving member 10, and vibration may be hindered. If the foamed member 8 is thick, it becomes necessary to take into account the amount of deformation of the foamed member 8, making it difficult to properly manage the pressure acting between the vibrating body 1 and the contact body 5 with the biasing member 11. There is also the problem that the vibration actuator becomes large. For this reason, it is desirable for the thickness of the foamed member 8 to be 1 mm or more and 2 mm or less.

Figure 10(b) is a schematic diagram of a part of a foam member 81 having another form of the foam member 8 considered in this embodiment, seen from the side. In Figure 10(b), the foam member 81 is divided into three layers: a foam layer 81b in which cells 81b exist, and layers 81c and 81d in which cells are not provided. The layers 81c and 81d are skin layers. At this time, if the skin layer 81c is thick, the contact surface 81e with the contact body acts as a highly hard elastic body and inhibits the vibration of the vibrating body 1, so in order to incorporate it into a vibration type actuator and not inhibit the vibration, it is necessary to limit the thickness of the skin layer 81c. The thicknesses T2 and T3 of the skin layer are defined as the distance between the surface layer 81e of the foam member 81 and a tangent line passing through multiple cells 81a and approximately parallel to the surface layer 81e. In the study, it was possible to use samples with a skin layer of 60 μm or less without inhibiting the vibration. The thickness T3 of the skin layer 81d on the contact surface 81f side with the pressure receiving member does not affect the vibration of the vibrating body, so it can be greater than 60 μm without any problem, and may be, for example, about 1/4 the thickness T of the foam member 81. If the foam member 81 is mainly made of rubber, such as a rubber sponge, the skin layer 81d is unfoamed rubber and has elasticity, so it is not affected by the pressure receiving member 10, and the thickness of the foam member 81 can be 1 mm or more and 2 mm or less.

As explained above, by appropriately controlling the cell size of the foam material, it is possible to realize a vibration actuator that can obtain sufficient output without the foam material impeding the vibration of the vibration actuator. Furthermore, by controlling the hardness, it is possible to select a more effective foam material.

[Second embodiment]
11 is a cross-sectional view of the linear vibration actuator in this embodiment as viewed in a direction perpendicular to its drive direction and pressure direction, where the drive direction of the vibration actuator is taken as the X-axis and the pressure direction is taken as the Z-axis.

Here, we will explain the driving principle of the linear vibration actuator in this embodiment. In FIG. 15, the vibrating body 101 is composed of a vibration plate 104 and a protrusion 106, and a piezoelectric element 105, which is an electromechanical energy conversion element, is attached to it.

Here, we will briefly explain the basic driving configuration of the vibrator. Figure 16 shows two bending vibration modes of the piezoelectric vibrator. The vibration mode in Figure 16(a) shows one of the two bending vibration modes (referred to as mode A). This mode A is a secondary bending motion in the long side direction (arrow X direction) of the rectangular vibrator 101, and has three nodes parallel to the short side direction (arrow Y direction).

Here, the protrusion 106 is positioned near a node in the A-mode vibration, and reciprocates in the direction of the arrow X (= the direction parallel to the surface to which the electromechanical energy conversion element is bonded) due to the A-mode vibration.

The vibration mode shown in FIG. 16(b) represents the other of the two bending vibration modes (called mode B). This mode B is a primary bending vibration in the short side direction (arrow Y direction) of the rectangular vibrating body 106, and has two nodes parallel to the long side direction (arrow X direction).

Here, the nodes in mode A and mode B are approximately perpendicular to each other in the XY plane.

In addition, the protrusion 106 is positioned near the position that becomes the antinode in the B-mode vibration, and reciprocates in the direction of the arrow Z (= the direction perpendicular to the surface to which the electromechanical energy conversion element is joined) due to the B-mode vibration.

By generating the above-mentioned A-mode and B-mode vibrations with a predetermined phase difference, an elliptical motion is generated at the tip of the protrusion 106, providing a driving force in the direction of the arrow X in FIG. 15 (= the direction parallel to the surface to which the electromechanical energy conversion element is bonded).

In FIG. 11, 52 is an elastic body, and 53 is a piezoelectric element which is an electrical-mechanical energy conversion element. Two protrusions 52a are provided on one surface of the elastic body 52, and a piezoelectric element 53 is bonded to the surface of the elastic body 52 opposite the surface on which the protrusions 52a are provided, thereby forming a vibrating body 51. The elastic body 52 is formed of a metal material such as hardened stainless steel. The protrusions 52a may be formed integrally with the elastic body 52a, or a separate member may be attached by means of welding or the like. The vibrating body 51 is supported by a vibrating body support member 62.

55 is a contact body, 56 is a contact body support part that supports the contact body 55, and the contact body 55 and the contact body support part 56 are joined together to form the moving member 54. The contact body 55 is made of stainless steel, and the contact surface with the vibrating body 51 is subjected to an effective treatment such as nitriding or plating containing hard particles to increase durability (wear resistance). The contact body support part is made of a metal material such as stainless steel or aluminum. In this embodiment, the moving member 54 is made of two parts, the contact body 55 and the contact body support part 56, but it does not necessarily have to be two parts, and in this embodiment, the group of components that move relative to the vibrating body is called the moving member.

60 is a bamboo-shoot-shaped coil spring that serves as a biasing member. 57 is a foam member, 59 is a pressure transmission member that transmits the pressure of the coil spring 60 to the vibrating body 51, and 61 is the exterior of the vibration actuator. The coil spring 60 and the pressure transmission member 59 together form the pressure member 58. The shape of the coil spring does not have to be bamboo-shoot shaped, and it can be cylindrical. Also, instead of a coil spring, a leaf spring, spring washer, or the like can be used.

As in the first embodiment, in this embodiment, it is desirable that the average circle equivalent diameter of the cells of the foam member 57 is 20 μm to 100 μm. The thickness and hardness are also the same as in the first embodiment.

Figure 13 is a projection diagram showing the disassembled state of the vibration actuator in this embodiment. The coil spring 60 is positioned at a predetermined position in the X-axis direction by being inserted into a hole 61b provided in the exterior part 61. The pressure transmission member is positioned at a predetermined position in the X-axis direction relative to the coil spring 60 and exterior part 61 by inserting a pin provided in the pressure transmission member 59 into the inner diameter side of the coil spring 60.

Then, the rectangular foam member 57 is sandwiched between the pressure transmission member 59 and the vibrating body 51, and the pin 61a on the exterior part 61 is inserted into the hole on the vibrating body support member 62 to sandwich the foam member 57 between the vibrating body 51 and the pressure transmission member 59. This positions the vibrating body support member 62 and the vibrating body 51 at a predetermined position in the X-axis direction.

The contact body support part 56 is provided with multiple grooves 56a, 56b, 56c. However, 56c is provided in a position that is not visible in the figure. Then, the exterior covers 63 and 64 are attached to the exterior part 61 so that the multiple grooves 56a, 56b, 56c and the grooves 63a, 64a of the exterior cover sandwich the multiple balls 68. It is preferable that the balls have a high hardness, and although ceramic balls are used in this embodiment, this is not limited to this. As a result, the vibrating body 51 is in pressurized contact with the moving body 54, and furthermore, the moving body 54 can move in the X-axis direction while being stable in the Z-axis direction.

In this embodiment, the function of the foam member 57 is the same as in the first embodiment, and by selecting a foam member with an appropriate cell size, it is possible to provide a linear vibration actuator with sufficient output.

[Third Example]
As a third embodiment, the configuration of a pan head device (rotating device) will be described as an example of a device including at least two vibration type actuators of the present invention.

Figure 13(a) is a front view of the pan head device 200 in this embodiment, and Figure 13(b) is a side view of the pan head device 200 in this embodiment.

The camera platform 200 has a head unit 210, a base unit 220, an L-angle 230, and an imaging device 240. Two vibration actuators of the present invention are arranged inside the head unit 210.

The output section of the vibration actuator 280 for panning is connected to the base member 220, and the rotational drive of the vibration actuator 280 pans the head section 210 relative to the base section 220.

The output section of the tilt vibration actuator 270 is connected to the L-angle 230, and the rotational drive of the vibration actuator 270 tilts the L-angle 230 relative to the head section 210.

The imaging device 240 attached to the L-angle 230 is a camera for taking moving and still images, and is capable of panning and tilting by driving two vibration actuators while taking pictures.

As described above, the vibration actuator of the present invention can be used as a driving source for a camera platform device.

[Fourth embodiment]
As a fourth embodiment, a configuration for driving a camera lens will be described as an example of an optical device equipped with a vibration actuator of the present invention.

Figure 14 shows a camera equipped with the lens in this embodiment.

The camera body 310 is equipped with a detachable lens barrel 320. A vibration actuator 300 is provided inside the lens barrel 320, and the focus lens or zoom lens 330 is moved by linear drive of the vibration actuator 300.

As described above, the vibration actuator of the present invention can be used as a driving source for a lens.

The present invention can be used in vibration actuators such as ultrasonic motors. It can also be used as an optical device that includes the above vibration actuator in its driving section, and as an electronic device that includes a substrate and the above vibration actuator.

LIST OF SYMBOLS 1 Vibrating body 2 Elastic body 3 Electrical-mechanical energy conversion element 4 Moving body 5 Contact body 6 Rubber member 7 Output section 8 Foam member 9 Pressurizing member 10 Pressure receiving member 11 Pressurizing member 12 Exterior section 13 Support section 16 Anti-dislodgement member 17 Rotary bearing 19 Position stopper member 51 Vibrating body 52 Elastic body 53 Electrical-mechanical energy conversion element 54 Moving member 55 Contact body 56 Contact body support section 57 Foam member 58 Pressurizing member 59 Pressure transmission member 60 Pressurizing member 61 Exterior section 62 Vibrating body support section 63 Exterior cover 64 Exterior cover 68 Ball 101 Vibrating body 104 Vibration plate 105 Electrical-mechanical energy conversion element 106 Projection section 200 Pan head device 210 Head section 220 Base portion 230 L angle 240 Imaging device 270 Vibration type actuator 280 Vibration type actuator 300 Vibration type actuator 310 Camera 320 Lens barrel 330 Lens

Claims (14)

A vibrating body including an elastic body and an electromechanical energy conversion element;
a contact body that is in contact with the vibrating body and moves relatively to the vibrating body;
A pressure member that applies pressure to the vibration body;
a foam member provided between the pressure member and the vibration body,
The foamed material has a cell average equivalent circle diameter of 70 μm or more and 105 μm or less . The vibration actuator according to claim 1, wherein the surface layer of the foamed material at the contact surface with the vibrating body is a skin layer having a thickness of 60 μm or less. 3. The vibration actuator according to claim 1, wherein the foamed member has an average Asker C hardness of 7 or more and 10 or less. 4. The vibration actuator according to claim 1, wherein the foam member has a thickness of 1 mm or more and 2 mm or less . 5. The vibration actuator according to claim 1, wherein the foam member has a surface that applies pressure to both the antinode and the node of vibration generated in the vibrating body. 6. The vibration actuator according to claim 1, wherein the electromechanical energy conversion element is a piezoelectric element, and a directional vector of a polarization axis of a piezoelectric material constituting the piezoelectric element intersects with the foam member. 7. The vibration actuator according to claim 1, wherein the vibrating body is annular, and the vibration generated in the vibrating body is a traveling wave vibration that progresses in a circular shape. A vibration actuator according to any one of claims 1 to 6, wherein the vibrating body is rectangular, and the vibrations generated in the vibrating body are two different bending vibrations. 9. A vibration actuator according to claim 1, wherein the foam material is mainly composed of a polymer having a skeleton of a siloxane bond (Si-O-Si) consisting of silicon and oxygen, and a methyl group bonded to the skeleton. 9. The vibration actuator according to claim 1, wherein the foam member is a sponge containing silicone rubber. 9. The vibration actuator according to claim 1, wherein the foam member is a sponge containing ethylene propylene diene rubber (EPDM). 9. The vibration actuator according to claim 1, wherein the foam member is a sponge containing acrylonitrile butadiene rubber (NBR). An optical device comprising a vibration actuator according to claim 1 in a drive section. An electronic device comprising: a substrate; and the vibration actuator according to claim 1 on the substrate.

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