Vibration actuator, electronic device, optical device, and manufacturing method for vibration actuator

Abstract

A vibration actuator according to the present invention is characterized by comprising: a vibrating body that includes an electro-mechanical energy conversion element and an elastic body provided with a plate and protrusions that protrude in the same direction out-of-plane from the plate section; a contact body that contacts the protrusions of the vibrating body and moves relative to the vibrating body; a foam member that contacts the vibrating body; and a biasing member that biases the vibrating body toward the contact body via the foam member, wherein the foam member includes a siloxane bond (Si–O–Si) comprising silicon and oxygen, and within the silicon included in the foam member, the ratio NQ / ND of the number NQ of Q units to the number ND of D units is at least 0.09.

Description

Vibration actuator, electronic device, optical device, and method for manufacturing vibration actuator

[0001] The present invention relates to a vibration actuator, an electronic device, an optical device, and a method for manufacturing a vibration actuator.

[0002] A vibration actuator has a vibrating body made of an electromechanical 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. The vibration actuator is used as a vibration wave motor that moves the contact body relative to the vibrating body by utilizing friction generated by the driving force of vibrations excited in the vibrating body.

[0003] This figure shows an outline of the structure and driving principle of a vibration wave motor, a type of vibration actuator. A vibration wave motor has a vibrating body and a contact body that is in pressurized contact with the vibrating body by a biasing member. In this case, it is desirable for the biasing member to have high rigidity when in contact with the vibrating body so that it can apply uniform pressure to the vibrating body. However, if a highly rigid member comes into contact with the vibrating body, it will inhibit the vibration of the vibrating body, causing a deterioration in the driving characteristics of the motor. Therefore, a structure is known in which a member that does not inhibit vibration is placed between the biasing member and the vibrating body as a vibration-damping member.

[0004] Patent Document 1 lists sponge, polystyrene foam, and felt as materials for supporting the vibrator, and discloses that wool felt is particularly excellent among them. Note that Patent Document 2 uses a material for the support of the vibrator that does not impede vibration, and is considered to have the same function as a vibration damping material.

[0005] Patent document 2 also describes a vibration actuator in which a foamed material is placed between a vibrating body and a biasing member, and by selecting the average circular equivalent diameter of the cells of the foamed material, stable and sufficient output can be obtained over a long period of time.

[0006] JP 3-289371 A JP 2022-83146 A

[0007] Here, in a vibration type actuator using a foam member, the driving characteristics may be degraded compared to when a felt is used.

[0008] The present invention has been made to address the above-mentioned problems and provides a vibration actuator that has stable driving characteristics over a long period of time and has improved driving characteristics.The present invention also provides electronic devices and optical devices that use a vibration actuator that has stable driving characteristics over a long period of time and has improved driving characteristics.The present invention also provides a method for manufacturing a vibration actuator that has stable driving characteristics over a long period of time and has improved driving characteristics.

[0009] The vibration actuator of the present invention includes a vibrating body having an electromechanical energy conversion element and an elastic body provided with a plate portion and protrusions protruding in the same direction outside the surface of the plate portion, a contacting body that contacts the protrusions of the vibrating body and moves relatively to the vibrating body, a foamed member that contacts the vibrating body, and a biasing member that biases the vibrating body to the contacting body via the foamed member, the foamed member containing a siloxane bond (Si—O—Si) consisting of silicon and oxygen, and the number N of silicon atoms in the foamed member is Q units. Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ is 0.09 or more.

[0010] According to the present invention, it is possible to provide a vibration actuator having stable driving characteristics over a long period of time and having improved driving characteristics. Also, according to the present invention, it is possible to provide electronic devices and optical devices that use a vibration actuator having stable driving characteristics over a long period of time and having improved driving characteristics. Also, it is possible to provide a method for manufacturing a vibration actuator having stable driving characteristics over a long period of time and having improved driving characteristics.

[0011] FIG. 1 is a diagram illustrating a schematic structure of a vibration actuator of the present invention using a circular piezoelectric material or a rectangular piezoelectric material. FIG. 2 is a diagram illustrating a schematic structure of a vibration actuator of the present invention using a circular piezoelectric material or a rectangular piezoelectric material. FIG. 3 is a diagram illustrating a schematic structure of a vibration actuator of the present invention using a circular piezoelectric material or a rectangular piezoelectric material. FIG. 4 is a diagram illustrating a schematic structure of a vibration actuator of the present invention using a circular piezoelectric material or a rectangular piezoelectric material. FIG. 5 is a diagram illustrating a schematic structure of a vibration actuator of the present invention using a circular piezoelectric material or a rectangular piezoelectric material. FIG. 6 is a diagram illustrating a schematic structure of a vibration actuator of the present invention using a circular piezoelectric material or a rectangular piezoelectric material. FIG. 7 is a diagram illustrating two vibration modes generated by a vibrator of the present invention comprising a rectangular piezoelectric material. FIG. 8 is a diagram illustrating two vibration modes generated by a vibrator of the present invention comprising a rectangular piezoelectric material. A schematic cross-sectional view of a foamed member of the present invention. A schematic side view of a foamed member of the present invention. A schematic side view of a foamed member of the present invention. A diagram illustrating structural units constituting the skeletal structure of a molecule containing a siloxane bond. A diagram illustrating structural units constituting the skeletal structure of a molecule containing a siloxane bond. 1 is a diagram illustrating the structural units that constitute the skeleton structure of a molecule containing a siloxane bond, obtained by solid-state NMR of the foamed material of the present invention. ２９ 1 is a Si-DD-MAS NMR spectrum obtained by solid-state NMR of the foamed material of the present invention. ２９6A and 6B. FIG. 6B is a Si-DD-MAS NMR spectrum. FIG. 6A is a diagram showing molecular structures assigned to each peak of FIG. 6A and 6B. FIG. 6B is a diagram showing molecular structures assigned to each peak of FIG. 6A and 6B. FIG. 6B is a diagram showing molecular structures assigned to each peak of FIG. 6A and 6B. FIG. 6B is a diagram showing molecular structures assigned to each peak of FIG. 6A and 6B. FIG. 6B is a diagram showing molecular structures assigned to each peak of FIG. 6A and 6B. FIG. 6B is a diagram explaining the schematic structure of an optical device of the present invention. FIG. 6C is a diagram showing the driving characteristics of a vibration actuator of an embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described.

[0013] The present inventors discovered that vibration actuators using foamed materials have poorer drive characteristics than actuators using felt. After further investigation, the present inventors discovered that optimizing the chemical structure of the foamed material makes it possible to obtain vibration actuators that have stable drive characteristics over a long period of time and have improved drive characteristics.

[0014] The vibration type actuator of the present invention has a vibrating body, a contact body, a foam member, and a biasing member. In the vibration type actuator of the present invention, the foam member contains a siloxane bond (Si—O—Si), and the number N of Q units is Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ When the foamed material contains a large number of Q units, the effect of stabilizing the siloxane structure is obtained, and a vibration actuator whose driving characteristics are not likely to deteriorate even when used for a long period of time can be obtained.

[0015] Figures 1A to 1F and 2A and 2B show examples of the schematic structure of a vibration actuator of the present invention. Figures 1A and 1D are side views showing a schematic diagram of the vibration actuator, Figures 1B and 1E are perspective views, and Figures 1C and 1F are rear views. Figure 2A is a diagram explaining Mode A of the vibration mode, and Figure 2B is a diagram explaining Mode B.

[0016] 1A to 1F and 2A and 2B use a vibrating body with a circular plate portion and a vibrating body with a rectangular plate portion, respectively. The vibrating actuator 100 of the present invention includes an electromechanical energy conversion element 120 made of an electrode 101 and a piezoelectric material 102. It also includes an elastic body 103 having a plate portion 108 and protrusions 106 that protrude in the same direction outside the surface of the plate portion, and these are arranged in this order to form a vibrating body 110.

[0017] The vibration actuator 100 further includes a contact body 104 that contacts the protrusion 106. In addition, the vibration actuator 100 includes a biasing member 121 for bringing the vibrating body 110 into pressurized contact with (biasing) the contact body 104, and a foam member 122 provided between the vibrating body 110 and the biasing member 121.

[0018] When the vibrating body 110 is driven, the vibrating body 110 and the contact body 104 move relatively. The contact body 104 may be any member that is movable relatively to the vibrating body 110, and is not limited to being in direct contact with the vibrator 110, but may be in indirect contact with the vibrating body 110 via another member. The surface of the electromechanical energy conversion element 120 is urged toward the contact body 104 by the urging member 121 via the foam member 122.

[0019] (Piezoelectric material) The shape of the piezoelectric material 102 does not matter, but if the shape of the plate portion is annular, it is preferable that the piezoelectric material is also annular, and if the shape of the plate portion is rectangular, it is preferable that the piezoelectric material is also rectangular.

[0020] The form of the piezoelectric material 102 is not limited, but may be, for example, a piezoelectric material (sintered body) without crystal orientation, crystal-oriented ceramics, a piezoelectric single crystal, etc. The shape that the piezoelectric material can take is not limited, but for example, a layered piezoelectric material may be used to form a laminate of electrodes and piezoelectric material, or a single plate of piezoelectric material may be used. From the viewpoint of the cost of the piezoelectric material, a single plate is superior. In order to drive a vibration type actuator, the piezoelectric material is subjected to a polarization treatment. When the frequency of the AC electric field applied to the polarization-treated piezoelectric material approaches the resonant frequency of the piezoelectric material, the piezoelectric material vibrates greatly due to the resonance phenomenon.

[0021] From the viewpoint of environmental load, the lead content of the piezoelectric material used in the electromechanical energy conversion element is preferably 1000 ppm or less.

[0022] (Electrodes) When a circular piezoelectric material is used, electrodes 101 divided in the circumferential direction are provided on the piezoelectric material to form a circular piezoelectric element. The electrodes 101 consist of a driving phase electrode 101e and a non-driving phase electrode 101f. The circumferential length of the driving phase electrode is 1 / 2 the wavelength λ of the vibration wave generated in the circumferential direction of the circular piezoelectric element when an alternating voltage is applied to the driving phase electrode. The circumferential length of the non-driving phase electrode (ground electrode, monitor electrode) is 1 / 4 of the wavelength λ. The number of driving phase electrodes and non-driving phase electrodes varies depending on the number of traveling waves excited in the circular piezoelectric material. The piezoelectric material corresponding to each driving phase electrode is polarized with a voltage of a different polarity from adjacent regions.

[0023] The driving phase electrodes are separated by an odd number of non-driving phase electrodes. After polarization processing, a first electrode 101a and a second electrode 101b are provided to short-circuit each of the two driving phase electrode groups separated by the non-driving phase electrodes. The first electrode 101a and the second electrode 101b are used to drive a vibration-type actuator using a circular annular piezoelectric material.

[0024] When a rectangular piezoelectric material is used, a rectangular electrode 101 is provided. The electrode 101 is made up of a first electrode 101a and a second electrode 101b. The first electrode 101a and the second electrode 101b are used for polarization processing of the rectangular piezoelectric material and for driving a vibration type actuator using the rectangular piezoelectric material.

[0025] The electrodes are made of a metal film with a thickness of approximately 0.3 to 10 μm. There are no particular restrictions on the material, but silver, gold, or platinum electrodes are generally used. There are no restrictions on the method for manufacturing the electrodes, and they can be formed by screen printing, sputtering, vacuum deposition, or other methods. In order to produce an electromechanical energy conversion element with a lead content of 1000 ppm or less, it is necessary to use a paste or target with a lead content of less than 1000 ppm when forming the electrodes.

[0026] (Elastic Body) The elastic body 103 is preferably made of metal from the viewpoint of its properties as an elastic body and its workability. Examples of metals that can be used for the elastic body 103 include aluminum, brass, and stainless steel. Among stainless steels, martensitic stainless steel is preferred, and SUS420J2 is most preferred. The elastic body has protrusions 106 that come into contact with the contact body. To further improve the wear resistance of the protrusions, the elastic body is subjected to quenching, plating, or nitriding.

[0027] It is preferable that the plate portion of the elastic body is rectangular. By making the plate portion of the elastic body rectangular, the manufacturing process of the electromechanical energy conversion element becomes easier, and it is possible to manufacture a small electromechanical energy conversion element. As a result, it becomes possible to manufacture a small vibration type actuator.

[0028] 1A, the foam member 122 is provided on the surface of the electromechanical energy conversion element 120 opposite to the surface on which the elastic body 103 is provided. The foam member 122 uniformly presses the vibrating body 110 against the contact body 104 and is also required to function as a vibration damping member. Its function as a vibration damping member is to damp vibrations from adjacent members by absorbing them or the like, and the foam member 122 may be provided separately as long as the drive characteristics are not reduced.

[0029] Fig. 3 shows a horizontal cross-sectional view (XY plane) of a foamed material of the present invention. Fig. 4A and Fig. 4B show side views of a foamed material of the present invention in the vertical direction (Z direction). Fig. 4A shows a side view of a foamed material without a skin layer on its surface, and Fig. 4B shows a side view of a foamed material with a skin layer on its surface.

[0030] The foam member 122 contains a siloxane bond (Si—O—Si) consisting of silicon and oxygen, and the number N of silicon units Q contained in the foam member Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ The foamed material is characterized in that its glass transition temperature is 0.09 or more. By including a siloxane bond (Si—O—Si) consisting of silicon and oxygen in the foamed material, the glass transition temperature of the foamed material can be made lower than −30°C, which is the operating temperature range, and the foamed material can maintain physical properties equivalent to those at room temperature even at low temperatures.

[0031] The number N of silicon Q units contained in the foamed material Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ A value of 0.09 or greater can improve the driving efficiency of the vibration actuator. Here, the silicon Q units and D units refer to units that constitute the skeletal structure of a molecule containing a siloxane bond. As shown in Figures 5A to 5D, in Figure 5A, a monofunctional unit with three organic substituents is called an M unit; in Figure 5B, a difunctional unit with two organic substituents is called a D unit; in Figure 5C, a trifunctional unit with one organic substituent is called a T unit; and in Figure 5D, a tetrafunctional unit with no organic substituents is called a Q unit. The M units refer to both ends of the skeletal structure. Furthermore, the D units exhibit flexibility in the skeletal structure, while the T units and Q units exhibit rigidity in the skeletal structure.

[0032] In the foamed material, the number N of silicon Q units contained in the foamed material Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ When the ratio N is 0.09 or more, the vibration damping member is suitable and the driving efficiency of the vibration actuator can be improved. Ｑ / N Ｄ If the value is less than 0.09, the foamed member will have high flexibility, and the biasing member will not apply pressure to the vibrator uniformly, which may result in large variations in characteristics or a decrease in drive efficiency, which is undesirable.

[0033] Although T units may be present to harden the skeletal structure, it is preferable that the ratio of Q units is greater than that of T units in order to maintain the structural hardness of the skeletal structure and make it stable over a long period of time. On the other hand, if the skeletal structure is too hard, it will inhibit the vibration of the vibrating body, which will cause deterioration of the driving characteristics of the motor and the generation of abnormal noise. Preferably, the number N of Q units of silicon contained in the foamed material is Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ is 0.5 or less, and more preferably 0.29 or less.

[0034] The constituent units of the silicon compound contained in the foamed material can be identified by molecular structure analysis using solid-state nuclear magnetic resonance (hereinafter referred to as solid-state NMR), and the proportion of the constituent units can be calculated. The NMR method is a method for measuring the excitation energy of nuclear spins, and in the case of silicon compounds, ２９ By observing the Si nuclei, it is possible to obtain information about the molecular structure.

[0035] There are two methods for measuring silicon compounds by solid-state NMR: the DD (Dipolar Decoupling) method and the CP (Cross Polarization) method. The CP method is used to measure the crystallinity and neighboring １ The detection sensitivity varies greatly depending on the presence of H. Therefore, the integral ratio of the measurement signal cannot accurately reflect the ratio of each component. On the other hand, the DD method has lower sensitivity than the CP method and requires a long measurement time, but by optimizing the measurement time, the ratio of each component can be calculated from the integral ratio of the measurement signal. The DD method must be used to calculate the structural units of the silicon compound contained in the foamed material of the present invention.

[0036] FIG. 6A shows the results of solid-state NMR of the foam member in the vibration actuator of the present invention. ２９ An example of a Si-DD-MAS NMR spectrum is shown in Figure 6B, which is an enlarged view of the area enclosed by the dotted line in Figure 6A. The horizontal axis of the NMR spectrum is called the chemical shift value δ (ppm), which is the deviation from the reference resonance frequency divided by the reference frequency, and indicates a value specific to each structure.

[0037] For example, the structure of Q4 in Figure 6B can be identified from the presence of a peak in the NMR spectrum at -110 ppm. The SSB in Figures 6A and 6B stands for spinning side band, which is a ghost signal detected due to the anisotropy of the molecular structure. The molecular structures assigned to each peak in Figures 6A and 6B are shown in Figures 7A to 7H. Although various molecular structures can be assigned depending on the element bonded to the central Si and the type of molecule, in the present invention, the ratios are calculated by classifying them into four types: M unit, D unit, T unit, and Q unit. In other words, in the molecular structures in Figures 7A to 7H, M0 and M0 Ｈ in M units, D2 and D2 Ｈ The peak area intensity is calculated using D unit, T1 and T2 in T unit, and Q3 and Q4 in Q unit.

[0038] In the NMR spectrum, the peak of the M unit can be confirmed in the range of 20 ppm to 0 ppm, the peak of the D unit can be confirmed in the range of 0 ppm to -45 ppm, the peak of the T unit can be confirmed in the range of -45 ppm to -85 ppm, and the peak of the D unit can be confirmed in the range of -85 ppm to -120 ppm.

[0039] The constituent units of silicon Q units and D units represent crosslinking points, and their ratio represents the crosslinking point density. In the foamed material production process, the crosslinking point density and the average circle-equivalent diameter of the bubbles can be changed by controlling the heating temperature and time during heat curing or curing by crosslinking reaction due to mixing of two-component raw materials. A foamed material containing a silicone resin and having an average circle-equivalent diameter of bubbles greater than 120 μm can be produced at a density of 600 g / cm. ２ More than 700g / cm ２ A foamed material was obtained by heat treatment at a temperature of 60° C. to 80° C. under the following pressure: Heat treatment under pressure is considered to stabilize the structure of the foamed material and is therefore preferable.

[0040] The foamed material is preferably a sponge containing silicone rubber. Similar effects can also be obtained by substituting some of the methyl groups of the silicone rubber with vinyl groups or phenyl groups. Silicone sponges are preferred because they exhibit less volume change in the thickness direction under pressure than felt, resulting in excellent long-term stability. For example, felt can be used at room temperature with a pressure of 600 g / cm. ２ More than 700g / cm ２ When held under the following pressure for 500 hours, the thickness is compressed to about 50% and does not return to its original thickness even when the pressure is released. On the other hand, silicone sponge returns to almost its original thickness when the pressure is released, so the volume change is small.

[0041] The foamed material is characterized in that the average equivalent circular diameter of the bubbles contained therein is greater than 120 μm. The average equivalent circular diameter of the bubbles contained in foamed material 122 is preferably greater than 120 μm. The presence of bubbles in the foamed material allows the foamed material to have spring properties, and the foamed material can uniformly pressurize vibrating body 110 against contact body 104 and function as a vibration damping member.

[0042] The average equivalent circular diameter is preferably calculated from the cross-sectional shape of the foamed member. When the average equivalent circular diameter of the bubbles in the cross section of the foamed member is greater than 120 μm, it is possible to uniformly pressurize the vibrating body while maintaining the driving characteristics of the motor without inhibiting the vibration of the vibrating body.

[0043] The average circular equivalent diameter of the foamed member 122 can be determined by methods such as image processing of cross-sectional images obtained by cross-sectional observation. Cross-sectional observation can be performed by exposing the cross section by cutting the sample or the like and observing it with an optical microscope or laser microscope. Another method is to obtain a non-destructive tomographic image using X-ray CT scanning. Furthermore, if the shape of the bubbles can be confirmed, the surface in contact with the electromechanical energy conversion element 120 may be treated as the cross-sectional shape. Image processing software can be used, whether it is optimized for a microscope or commercially available. Because bubbles of various sizes exist, it is preferable to observe many bubbles when calculating the average circular equivalent diameter. Specifically, it is preferable to calculate the average circular equivalent diameter from 50 or more bubbles.

[0044] The foamed material of the present invention may have columnar cells as shown in Figure 4B, or may have a skin layer on the surface of the foamed material. As shown in Figure 4B, when a skin layer is present on the surface, the cells cannot be accurately confirmed from the surface, so it is preferable to expose the cross section by cutting. The obtained cross-sectional photograph can be processed to calculate the average equivalent circle diameter.

[0045] It is preferable that the cells in the foamed material are mainly composed of closed cells. Closed cells refer to cells that are not connected between the front and back of the foamed material. Closed cells are difficult for gases and liquids to pass through. For this reason, closed cells are preferable for the foamed material to have spring properties. On the other hand, open cells have the characteristic that the cells are connected, which makes it easy for air to enter and exit and makes it prone to collapse when pressure is applied. This is undesirable because it has poor spring properties, which may prevent the vibrator from being pressurized uniformly and reduce the vibration damping function. It is preferable that the number of closed cells is greater than the number of interconnected cells, i.e., the number of closed cells accounts for 50% or more of the total number of cells contained in the foamed material. In this case, it can be counted from a cross-sectional photograph containing 50 or more cells.

[0046] It is more preferable that the average circular equivalent diameter of the bubbles in the foamed material is 200 μm or more. In order to achieve stable operation within the operating temperature range of the vibration actuator (for example, -30°C to 60°C), it is effective to use a piezoelectric material with a phase transition temperature of -10°C or less for the vibration actuator. In other words, it is effective to use a piezoelectric material whose piezoelectric properties at -10°C are greater than those at room temperature for the vibration actuator. In this case, by making the average circular equivalent diameter of the bubbles 200 μm or more, it is possible to maintain the effect as a vibration damping member in low temperature ranges and improve drive efficiency. It is more preferable that the average circular equivalent diameter of the bubbles is 300 μm or more.

[0047] The average equivalent circular diameter of the foamed member is preferably smaller than 1 / 2 of the thickness t of the foamed member. This allows the foamed member to apply uniform pressure to the vibrating body and function as a vibration damping member. More preferably, the foamed member should have an average equivalent circular diameter smaller than 1 / 3 of the thickness t.

[0048] (Contact Body) From the viewpoint of rigidity, the contact body 104 is preferably made of stainless steel. Among stainless steels, martensitic stainless steel is preferred, with SUS420J2 being most preferred. The contact body 104 must have excellent wear resistance because it is in frictional contact with the elastic body 103, and its surface is subjected to nitriding or anodizing. A frictional force due to pressurized contact acts between the protrusion 106 and the contact body 104. The vibration generated by the electromechanical energy conversion element 120 causes the tip of the protrusion 106 to vibrate elliptically, generating a driving force (thrust) that drives the contact body 104. The contact body is generally called a slider or rotor.

[0049] The term "contact body" refers to a member that comes into contact with the vibrating body and moves relative to the vibrating body due to vibrations generated in the vibrating body. The contact between the contact body and the vibrating body is not limited to direct contact where no other member is interposed between them. The contact between the contact body and the vibrating body may also be indirect contact where another member is interposed between the contact body and the vibrating body, as long as the contact body moves relative to the vibrating body due to vibrations generated in the vibrating body. The "other member" is not limited to a member independent of the contact body and the vibrating body (for example, a high-friction material made of a sintered body). The "other member" may also be a surface-treated portion formed on the contact body or the vibrating body by plating, nitriding, or the like.

[0050] (Piezoelectric Vibrator) In an annular piezoelectric element, the piezoelectric material in contact with adjacent drive phase electrodes is polarized with opposite polarities. Therefore, when an electric field of the same polarity is applied to the drive phase electrode 101e, the expansion and contraction polarity in that region of the piezoelectric material alternates at a pitch of λ / 2. When an alternating voltage is applied to the first electrode 101a, a first standing wave with a wavelength λ is generated around the entire circumference of the vibrator. When an alternating voltage is applied to the second electrode 101b, a second standing wave is similarly generated, but the wave position is rotated by λ / 4 in the circumferential direction relative to the first standing wave. On the other hand, when two types of alternating voltages with the same frequency and a temporal phase difference of π / 2 are applied to the first and second electrodes, the following traveling wave is generated. That is, as a result of the combination of the first and second standing waves, a traveling wave (wave number n along the annulus, wavelength λ) of bending vibration (vibration with amplitude perpendicular to the surface of the vibrator) that propagates in the circumferential direction around the entire circumference of the vibrator is generated.

[0051] When a traveling wave of bending vibration (hereinafter simply referred to as "bending vibration wave") is generated, each point on the surface of the diaphragm that constitutes the vibrator moves elliptically, and the moving body in contact with this surface rotates due to the circumferential friction force (driving force) from the diaphragm. The direction of rotation can be reversed by switching the positive and negative phase difference of the AC voltage applied to the first and second electrodes. The rotation speed can also be controlled by the frequency and amplitude of the AC voltage applied to the first and second electrodes.

[0052] 2A and 2B illustrate two vibration modes generated by a vibrator of the present invention having a rectangular piezoelectric material. The rectangular piezoelectric material is provided with a first electrode 101a and a second electrode 101b, each of which has a first region and a second region.

[0053] Mode A: When both the first region and the second region expand or contract, a first bending vibration mode (mode A) occurs. Mode A is most strongly excited when the phase difference between the alternating voltages VA and VB applied to the first electrode 101a and the second electrode 101b is 0° and the frequency is near the resonant frequency of mode A. Mode A is a first-order out-of-plane vibration mode in which two nodes (where the amplitude is minimum) appear approximately parallel to the long sides of the vibrator 110. The two protrusions 106 protruding in the same direction from the elastic body are positioned near the antinodes (where the amplitude is maximum) of mode A. Therefore, the tip surfaces of the protrusions 106 reciprocate in the Z direction due to vibration mode A.

[0054] Mode B When the first region expands and contracts, the second region contracts and expands, respectively, generating a second bending vibration mode (mode B). Mode B is most strongly excited when the phase difference between the alternating voltages VA and VB applied to the first electrode 101a and the second electrode 101b is 180° and the frequency is near the resonant frequency of mode B. Mode B is a second-order out-of-plane vibration mode in which three nodes appear approximately parallel to the short sides of the vibrator 110. The protrusion 106 of the elastic body is positioned near the node position of mode B. Therefore, the tip surface of the protrusion 106 reciprocates in the X direction due to mode B.

[0055] In the vibration actuator 100, when the phase difference between the alternating voltages VA and VB is 0 to ±180°, mode A and mode B are excited simultaneously, and elliptical vibration is excited in the protrusion 106 of the elastic body. A vibration actuator that uses a rectangular piezoelectric material and is driven by mode A and mode B is preferred because it can be easily miniaturized.

[0056] It is more preferable that there are two protrusions protruding out of the plane of the plate in the same direction, since this facilitates miniaturization of a vibration-type actuator that uses rectangular piezoelectric materials and is driven in Mode A and Mode B, as shown in Figures 2A and 2B.

[0057] In order to prevent vibration inhibition due to deformation of the foam member caused by pressurization, it is preferable that the area of ​​the contact portion between the foam member and the electromechanical energy conversion element is smaller than the area of ​​the planar portion of the electromechanical energy conversion element including the above-mentioned portion. Furthermore, it is preferable that the foam member is smaller than the electromechanical energy conversion element. This is expected to prevent problems such as the foam member deforming and wrapping around the side of the foam member and the piezoelectric element, which is the electromechanical energy conversion element, inhibiting vibration of the piezoelectric element, or interfering with surrounding components, inhibiting vibration. Furthermore, it is preferable that the foam member is smaller than the elastomer. If the foam member is larger than the elastomer, it may deform and interfere with surrounding components, inhibiting vibration. Therefore, by making the foam member smaller than the elastomer, it is expected to prevent problems such as vibration inhibition.

[0058] (Composition of Piezoelectric Material) The composition of the piezoelectric material 102 is not particularly limited as long as it can be used as a vibration type actuator.

[0059] Generally, lead zirconate titanate (PZT)-based materials are used for piezoelectric materials. However, in light of the recent concern over the environmental impact of lead, it is more preferable to use a piezoelectric material that uses a lead-free perovskite metal oxide (lead content less than 1000 ppm). The lead content can be measured, for example, by ICP atomic emission spectroscopy.

[0060] It is more preferable that the piezoelectric material does not contain lead, that is, the main component of the lead-free piezoelectric material is a barium titanate-based material.

[0061] The piezoelectric material is preferably made of a barium titanate-based material, from the viewpoint of having a high piezoelectric constant and being relatively easy to manufacture. Here, the barium titanate-based material is barium titanate (BaTiO ３ ), barium calcium titanate ((Ba,Ca)TiO ３ ), barium zirconate titanate (Ba(Ti,Zr)O ３ ), barium calcium zirconate titanate ((Ba,Ca)(Ti,Zr)O ３ ), and sodium niobate-barium titanate (NaNbO ３ -BaTiO ３ Examples of compositions include bismuth sodium titanate-barium titanate, and bismuth potassium titanate-barium titanate. These compositions are used as the main component of a material. A "main component" refers to a material whose weight fraction is greater than 10%.

[0062] Furthermore, piezoelectric materials containing these compositions as the main component or in combination can be used in the vibration actuator 100 of the present invention.

[0063] The following material is more preferable from the viewpoint of excellent temperature dependency of piezoelectric characteristics within the operating temperature range and achieving both the piezoelectric constant and mechanical quality factor of the piezoelectric material: barium calcium titanate zirconate ((Ba,Ca)(Ti,Zr)O ３ ), sodium niobate-barium titanate (NaNbO ３ -BaTiO ３ ) as the main component.

[0064] It is preferable that the main component of the piezoelectric material is barium calcium zirconate titanate (hereinafter referred to as BCTZ). When BCTZ is the main component, the piezoelectric properties of BCTZ can be adjusted according to the application by adjusting the amount of Ca and Zr. In addition, the amount of expensive niobium used can be reduced.

[0065] The piezoelectric material is preferably a piezoelectric material containing an oxide having a perovskite structure containing Ba, Ca, Ti, and Zr, and Mn, wherein x, which is the molar ratio of Ca to the sum of Ba and Ca, is 0.02≦x≦0.30, y, which is the molar ratio of Zr to the sum of Ti and Zr, is 0.020≦y≦0.095 and y≦x, α, which is the ratio of the molar amounts of Ba and Ca to the molar amounts of Ti and Zr, is 0.9955≦α≦1.01, and the content of Mn per 100 parts by weight of the oxide is preferably 0.02 parts by weight or more and 1.0 part by weight or less in terms of metal.

[0066] Such a piezoelectric material can be expressed by the following general formula (1): (Ba １－ｘ Ca ｘ ) α (Ti １－ｙ Zr ｙ ) O ３ (1) However, it is preferable that the main component is a perovskite metal oxide expressed by 0.986≦α≦1.100, 0.02≦x≦0.30, and 0.02≦y≦0.095, and that the content of metal components other than the main component contained in the piezoelectric material is 1 part by weight or less in terms of metal per 100 parts by weight of the metal oxide.

[0067] In particular, it is preferable that the metal oxide contains Mn, and the Mn content is 0.02 to 0.40 parts by weight in terms of metal per 100 parts by weight of the metal oxide. When Mn is contained within this range, the insulating properties and mechanical quality factor Qm are improved. Here, the mechanical quality factor Qm is a coefficient that represents the elastic loss due to vibration when evaluating a piezoelectric material as a vibrator, and the magnitude of the mechanical quality factor is observed as the sharpness of the resonance curve in impedance measurement. In other words, it is a constant that represents the sharpness of the resonance of the vibrator. When the mechanical quality factor Qm is large, the amount of strain of the piezoelectric material increases near the resonance frequency, allowing the piezoelectric material to vibrate more effectively.

[0068] The metal oxide represented by general formula (1) means that the metal elements located at the A site of the perovskite structure are Ba and Ca, and the metal elements located at the B site are Ti and Zr. However, some of the Ba and Ca may be located at the B site. Similarly, some of the Ti and Zr may be located at the A site.

[0069] In general formula (1), the molar ratio of the B-site element to the O element is 1:3. However, even if the molar ratio is slightly different, it is still included in the scope of the present invention as long as the metal oxide has a perovskite structure as the main phase.

[0070] Whether a metal oxide has a perovskite structure can be determined by structural analysis using, for example, X-ray diffraction or electron beam diffraction.

[0071] In general formula (1), x, which represents the molar ratio of Ca at the A site, is in the range of 0.02≦x≦0.30. Replacing a portion of the Ba in perovskite-type barium titanate with Ca within this range shifts the phase transition temperature between orthorhombic and tetragonal crystals to a lower temperature, thereby enabling stable piezoelectric vibration within the operating temperature range of the vibration actuator. However, if x is greater than 0.30, the piezoelectric constant of the piezoelectric material may be insufficient, potentially resulting in insufficient performance of the vibration actuator. On the other hand, if x is less than 0.02, the dielectric loss (tan δ) may increase. Increased dielectric loss may increase heat generation when applying voltage to the piezoelectric material to drive the vibration actuator, reducing motor drive efficiency and increasing power consumption.

[0072] In general formula (1), y, which represents the molar ratio of Zr in the B site, is in the range of 0.02≦y≦0.1. If y is greater than 0.1, Td becomes low, less than 80° C., and the temperature range in which the vibration actuator can be used becomes less than 80° C., which is not preferable.

[0073] In this specification, Td refers to the lowest temperature at which the piezoelectric constant of a piezoelectric material, when heated from room temperature to Td one week after polarization treatment and then cooled back to room temperature, decreases by more than 10% compared to the piezoelectric constant before heating.

[0074] In general formula (1), α, which represents the ratio of the molar amounts of Ba and Ca at the A site to the molar amounts of Ti and Zr at the B site, is preferably in the range of 0.9955≦α≦1.010. If α is smaller than 0.9955, abnormal grain growth is likely to occur in the crystal grains constituting the piezoelectric material, resulting in a decrease in the mechanical strength of the piezoelectric material. On the other hand, if α is larger than 1.010, the piezoelectric material does not become highly densified and its insulation becomes significantly brittle.

[0075] The means for measuring the composition of the piezoelectric material is not particularly limited. Examples of the means include X-ray fluorescence analysis, ICP atomic emission spectroscopy, and atomic absorption spectroscopy. Any of the measuring means can be used to calculate the weight ratio and composition ratio of each element contained in the piezoelectric material.

[0076] The metal equivalent indicating the Mn content is calculated by calculating the content of each metal, Ba, Ca, Ti, Zr, and Mn, measured from the piezoelectric material by X-ray fluorescence analysis (XRF), ICP atomic emission spectroscopy, atomic absorption spectroscopy, etc. From the content, the elements constituting the metal oxide represented by general formula (1) are converted into oxides, and the value is calculated as the ratio of the weight of Mn to the total weight of 100.

[0077] If the Mn content is less than 0.02 parts by weight, the effect of the polarization treatment required to drive the vibration actuator may be insufficient. On the other hand, if the Mn content is greater than 0.40 parts by weight, the piezoelectric properties of the piezoelectric material may be insufficient, or hexagonal crystal structure crystals without piezoelectric properties may be formed. Mn is not limited to metallic Mn, and may be contained in the piezoelectric material as an Mn component, regardless of the form of inclusion. For example, Mn may be solid-solved in the B site or contained in the grain boundary. A more preferable form of inclusion is solid-solubilized in the B site from the viewpoint of insulation properties and ease of sintering.

[0078] The piezoelectric material preferably contains 0.042 parts by weight or more and 0.850 parts by weight or less of Bi in terms of metal.

[0079] The piezoelectric material may contain 0.85 parts by weight or less of Bi, calculated as metal, per 100 parts by weight of the metal oxide represented by the general formula (1). The Bi content relative to the metal oxide can be measured, for example, by ICP atomic emission spectroscopy. Bi may be present at the grain boundaries of the ceramic piezoelectric material or may be solid-solved in the perovskite structure of (Ba, Ca)(Ti, Zr)O3. The presence of Bi at the grain boundaries reduces interparticle friction and increases the mechanical quality factor. On the other hand, when Bi is incorporated into a solid solution that forms a perovskite structure, the phase transition temperature is lowered, thereby reducing the temperature dependence of the piezoelectric constant and further improving the mechanical quality factor. When Bi is incorporated into the solid solution, it is preferable that it is located in the A site, as this improves the charge balance with Mn.

[0080] The piezoelectric material may contain components (hereinafter referred to as minor components) other than the elements contained in general formula (1) and Mn and Bi, provided that the properties are not affected. The total amount of the minor components is preferably less than 1.2 parts by weight per 100 parts by weight of the metal oxide expressed by general formula (1). If the minor components exceed 1.2 parts by weight, the piezoelectric and insulating properties of the piezoelectric material may be degraded. Lead-free piezoelectric materials have a high Young's modulus and therefore tend to have a higher resonance frequency than lead-based piezoelectric materials. A higher resonance frequency increases the number of vibrations of the vibrator, making it more sensitive to changes in the vibration-damping member disposed between the biasing member and the vibrating body. Therefore, for vibration-type actuators using lead-free piezoelectric materials, it is preferable to use a foamed material that has excellent long-term stability and is less susceptible to change.

[0081] It is more preferable that the phase transition temperature is −10° C. or lower, since this provides excellent temperature dependency of the piezoelectric characteristics within the operating temperature range of the vibration type actuator (for example, −30° C. to 60° C.).

[0082] The piezoelectric material of the present invention undergoes a successive phase transition from tetragonal to orthorhombic as the temperature is decreased from room temperature. The phase transition temperature referred to in this specification refers to this phase transition. The phase transition temperature is calculated by measuring the dielectric constant while changing the temperature and determining the temperature at which the value obtained by differentiating the dielectric constant with respect to the sample temperature is maximized. The crystal system can be evaluated by X-ray diffraction, electron diffraction, Raman scattering, or the like. Near the phase transition temperature, the dielectric constant and electromechanical coupling coefficient reach their maximum values, and the Young's modulus reaches its minimum. The piezoelectric constant is a function of these three parameters and exhibits a maximum value or an inflection point near the phase transition temperature.

[0083] (Method for manufacturing a vibration actuator) The vibration actuator of the present invention is manufactured by the following manufacturing method. First, a foam material containing silicone rubber and having bubbles with an average equivalent circular diameter of more than 120 μm is subjected to a pressure and heat treatment to obtain a foam member. Next, an elastic body and an electromechanical energy conversion element are brought into contact to obtain a vibrating body, and a contact body is prepared. Finally, the vibrating body is biased against the contact body via the foam member to obtain a vibration actuator. The pressure and heat treatment is performed at a pressure of 600 g / cm. ２ More than 700g / cm ２ The foamed material is maintained at a temperature of 60°C or higher and 80°C or lower under pressure as follows:

[0084] (Electronic Device) The electronic device of the present invention is characterized by comprising the vibration actuator of the present invention, a member connected to the contact body of the vibration actuator, and a member position detection means (e.g., an encoder). The electronic device detects the position of the member and operates the vibration actuator until the member reaches a target position, thereby enabling precise control of the position of the member.

[0085] (Optical Device) The optical device of the present invention is characterized by comprising the electronic device of the present invention and at least one of an optical element and an imaging element. FIG. 8 is a schematic diagram showing one embodiment of the optical device (focus lens portion of a lens barrel device) of the present invention. In FIG. 8, a vibrating body 110 having a rectangular piezoelectric material is in pressure contact with a contact body (slider) 104, as in FIG. 1D. A power supply member 507 is connected to the surface having the first and second regions. When a desired voltage is applied to the vibrating body 110 via the power supply member 507 by a voltage input means (not shown), an elliptical motion occurs in the protrusion of the elastic body (not shown). The holding member 501 is joined to the vibrating body 110 and is configured to prevent unnecessary vibrations. The moving housing 502 is fixed to the holding member 501 with screws 503 and is integral with the vibrating body 110. These components form the electronic device of the present invention. By attaching the moving housing 502 to the guide member 504, the electronic device of the present invention can move linearly in both directions (forward and reverse) along the guide member 504.

[0086] Next, we will explain the lens 506 (optical member) that serves as the focus lens of the lens barrel device. The lens 506 is fixed to a lens holding member 505 and has an optical axis (not shown) parallel to the movement direction of the vibration actuator. Like the vibration actuator, the lens holding member 505 performs focus positioning (focusing operation) by moving linearly on two guide members 504, which will be described later. The two guide members 504 are members that engage the movable housing 502 and the lens holding member 505, enabling the movable housing 502 and the lens holding member 505 to move linearly. With this configuration, the movable housing 502 and the lens holding member 505 can move linearly on the guide members 504.

[0087] The connecting member 510 is a member that transmits the driving force generated by the vibration actuator to the lens holding member 505, and is fitted and attached to the lens holding member 505. This allows the lens holding member 505 to move smoothly in both directions along the two guide members 504 together with the movable housing 502.

[0088] Further, a sensor 508 is provided to detect the position of the lens holding member 505 on the guide member 504 by reading position information from a scale 509 attached to the side surface of the lens holding member 505. As described above, the focus lens unit of the lens barrel device is configured by incorporating the above-mentioned components.

[0089] In the above, a lens barrel device for a single-lens reflex camera has been described as an example of an optical device, but the present invention can be applied to a variety of optical devices equipped with a vibration actuator, regardless of the type of camera, such as a compact camera in which the lens and camera body are integrated, or an electronic still camera.

[0090] Another configuration of the vibration type actuator may be one in which multiple vibrators are in contact with one common contact body, and the contact body moves relative to the multiple vibrators due to vibration of the multiple vibrators.

[0091] Furthermore, the vibration actuator of the present invention can be applied to medical or engineering fields. Specifically, a wire-driven actuator can be configured that includes an elongated member, a wire that is inserted through the elongated member and fixed to a part of the elongated member, and the vibration actuator described above that drives the wire, and that bends the elongated member when the wire is driven.

[0092] EXAMPLES Next, the vibration actuator and vibrator of the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

[0093] Example 1 Metal oxide powder was fired at 1340° C. to obtain a piezoelectric material shown in manufacturing composition 1 in Table 2.

[0094] Production composition 1 is a composition represented by general formula (1), and the values ​​of x, y, and α shown in Table 2 correspond to the respective values ​​in general formula (1) described above.

[0095] The obtained piezoelectric material was ground and polished to a substantially uniform thickness of 0.5 mm, and then machined into a ring shape with an outer diameter of 62 mm and an inner diameter of 54 mm. The driving phase electrode 101e and non-driving phase electrode 101f shown in FIG. 1C were formed on one side of the shaped piezoelectric material 102. The electrodes were formed by applying silver paste to the piezoelectric material 102 by screen printing, followed by drying and baking.

[0096] Next, adhesive was applied to the elastic body 103 made of SUS420J2, and it was pressure-bonded to the piezoelectric material 102 on which the electrodes were formed. The annular piezoelectric material and the annular elastic body were positioned using a positioning jig so that the centers of their circles were aligned. Next, heat treatment was performed to harden the adhesive. The piezoelectric material with the pressure-bonded elastic body was heated to a temperature T1 of 160°C and held for 180 seconds, then cooled to room temperature, and the pressure was released to obtain a vibrator. Next, an FPC coated with ACP was thermocompression-bonded to the electrodes on the piezoelectric material. The thermocompression bonding conditions were a temperature T2 of 140°C and a holding time of 20 seconds.

[0097] The elastic SUS420J2 was then grounded, and voltages of opposite polarities were alternately applied to adjacent driving phase electrodes 101e to perform polarization. In the polarization process, multiple external electrodes connected to a power source were brought into contact with the driving phase electrodes 101e and the driven phase electrodes 101f used as sensors. The sample was then heated to T3 = 100°C, and an electric field equivalent to 2 kV / mm was applied for 30 minutes. The sample was then cooled to 40°C over 40 minutes with the electric field still applied, after which the voltage application was terminated.

[0098] Thereafter, the first electrode 101a and the second electrode 101b were printed and dried to obtain a vibrator. In the drying process, the temperature of the piezoelectric material was kept below 80°C to prevent depolarization of the piezoelectric material. The obtained vibrator was brought into pressure contact with a contact body (rotor) made of SUS420J2 to produce a vibration type actuator. The type of foamed material containing a siloxane bond (Si-O-Si) consisting of silicon and oxygen, which was placed between the electro-mechanical energy conversion element and the biasing member, is shown in Example 1 of Table 1. The number N of Q units of silicon contained in the foamed material Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ was 0.23.

[0099] (Example 2) A piezoelectric material having manufacturing composition 1 was obtained in the same manner as in Example 1. The obtained piezoelectric material was ground and polished to a substantially uniform thickness of 0.35 mm, and then processed into a rectangle measuring 8.9 mm x 5.7 mm. The first to third electrodes shown in FIG. 3 were formed on both sides of the shaped piezoelectric material in the same manner as in Example 1.

[0100] Next, an adhesive was applied to an elastic body made of SUS420J2, and it was pressure-bonded to a rectangular piezoelectric material with electrodes formed on it. The elastic body used had a rectangular portion measuring 9.1 x 5.8 mm, which was larger than the piezoelectric material, and the thickness of the elastic body was between 0.25 and 0.30 mm. The rectangular piezoelectric material and the elastic body were positioned using a positioning jig so that the centers of their rectangular portions were aligned and the sides of the rectangular portions were parallel. In the pressure-bonded state, the piezoelectric material was heated to a temperature T1 = 160°C and held for 180 seconds, then cooled to room temperature, and the pressure was released to obtain a vibrator.

[0101] Next, the FPC coated with ACP and the piezoelectric material were pressure-bonded for 20 seconds using a soldering iron at a temperature T2 of 140° C., thereby thermocompression-bonding the FPC to the electrodes provided on the piezoelectric material.

[0102] The piezoelectric material was then subjected to a polarization process. During the polarization process, the elastic body was grounded, and external electrodes connected to a power source were contacted with the first and second electrodes, respectively. While the first and second electrodes were already connected to an FPC, they were not entirely covered by the FPC, and the external electrodes used for polarization contacted the exposed portions. After heating to T3 = 100°C, an electric field equivalent to 2 kV / mm was applied for 30 minutes. The material was then cooled to 40°C over 40 minutes with the electric field still applied, after which the voltage application was terminated. The vibrator obtained through the above process was pressed into contact with a contact body (slider) made of SUS420J2 stainless steel to produce a vibration actuator. The type of foam material containing a siloxane bond (Si-O-Si) consisting of silicon and oxygen, which was placed between the electromechanical energy conversion element and the biasing member, is shown in Example 2 of Table 1.

[0103]

[0104] (Examples 3 to 6) Vibration actuators Examples 3 to 6 were produced in the same manner as Example 2, except that the type of foam member containing a siloxane bond (Si—O—Si) consisting of silicon and oxygen, which was placed between the electromechanical energy conversion element and the biasing member, was shown in Table 1.

[0105] Comparative Example 1 A vibration type actuator was produced in the same manner as in Example 1, except that felt was placed between the electromechanical energy conversion element and the biasing member.

[0106] Comparative Example 2 A vibration actuator was produced in the same manner as in Example 2, except that felt was placed between the electromechanical energy conversion element and the biasing member.

[0107] (Method for Evaluating Vibration Actuators) A drive test was performed on the vibration actuators of each example and comparative example by applying an alternating voltage of 130 Vpp to the first and second electrodes, with a phase difference of -90° and 90° between the voltages on the first and second electrodes.

[0108] When the frequency of the AC voltage is swept from a frequency higher than the resonant frequency of vibration mode A and vibration mode B toward the resonant frequency, the contact body is driven in a direction according to the phase difference of the AC voltage and stops after reaching maximum speed. For convenience, the directions of travel when the phase difference is -90° and 90° are called the reverse direction and forward direction, respectively. The maximum speed of the vibrator and the frequency at which the maximum speed was reached were measured using a sensor. The power (rated power) at a rated speed lower than the maximum speed was calculated from the current flowing through the drive circuit. Figure 9 shows an example of the measurement results of speed and power versus frequency. Measurements of the maximum speed and rated power were conducted in an ambient atmosphere at 20°C, and the average values ​​for the reverse direction and forward direction were calculated.

[0109] The change in maximum speed and the change in rated power of Example 1 were calculated relative to the maximum speed of the vibration actuator fabricated in Comparative Example 1. Similarly, the change in maximum speed and the change in rated power of Examples 3 to 6 were calculated relative to the maximum speed of the vibration actuator fabricated in Comparative Example 2. The results are shown in Table 1.

[0110] In comparison with the vibration type actuators of Comparative Examples 1 and 2, which used felt, the maximum speed increased and the rated power decreased in Examples 1 and 2, which used foam material A containing a siloxane bond (Si—O—Si) consisting of silicon and oxygen.

[0111] As shown in Example 3, it was also confirmed that the maximum speed increased and the rated power decreased at each temperature in the foam material B.

[0112] In the foam material C and foam material D shown in Examples 4 and 5, the maximum speed was equivalent to that of the comparative example, but the rated power was lower.

[0113] In the foam member E shown in Example 6, the maximum speed and rated power were equivalent to those of the felt of Comparative Example 2.

[0114] (Example 7) The vibration actuator produced in Example 2 was mechanically connected to an optical member to produce the optical device shown in Figure 8. By controlling the AC voltage applied to the piezoelectric material based on position information provided to an encoder consisting of a sensor and a scale, it was possible to precisely drive the vibration actuator and the optical member connected to the vibration actuator to the target position. In this optical device, an optical lens was connected to the vibration actuator, and it was confirmed that it had an autofocus function.

[0115] The above has been described using manufacturing composition 1 as an example, but it has been confirmed that the driving characteristics of the vibration actuator of the present invention are equal to or better than those of felt, as in Example 2, even when manufacturing compositions 2 to 46 or lead zirconate titanate (PZT) are used.

[0116] As described above, a foam member is provided between the biasing member and the vibrating body, and the number N of Q units of silicon contained in the foam member is Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ It has been found that it is preferable that the value of the resistance be 0.09 or more. By configuring in this way, it is possible to provide a vibration type actuator that is stable over a long period of time and has improved drive characteristics.

[0117]

[0118] The disclosure of this embodiment includes the following configurations and methods.

[0119] (Configuration 1) A vibrating body having an electromechanical energy conversion element and an elastic body provided with a plate portion and a protrusion portion protruding in the same direction outside the surface of the plate portion; a contact portion that contacts the protrusion portion of the vibrating body and moves relatively to the vibrating body; a foam member that contacts the vibrating body; and a biasing member that biases the vibrating body to the contact portion via the foam member, wherein the foam member contains a siloxane bond (Si—O—Si) consisting of silicon and oxygen, and the number N of Q units of silicon contained in the foam member Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ A vibration type actuator characterized in that:

[0120] (Configuration 2) The vibration type actuator according to configuration 1, wherein the foam member is a sponge containing silicone rubber.

[0121] (Configuration 3) The vibration actuator according to configuration 1 or 2, wherein the foamed member has bubbles with an average equivalent circle diameter of greater than 120 μm.

[0122] (Configuration 4) The vibration actuator according to any one of configurations 1 to 3, wherein the electromechanical energy conversion element includes a piezoelectric material and an electrode, and the piezoelectric material has a lead content of 1000 ppm or less.

[0123] (Configuration 5) The vibration type actuator according to any one of configurations 1 to 4, wherein the plate portion is rectangular.

[0124] (Configuration 6) The vibration type actuator according to any one of configurations 1 to 5, wherein the elastic body has two protrusions.

[0125] (Configuration 7) The vibration type actuator according to any one of configurations 1 to 6, wherein the foam member is smaller than the electromechanical energy conversion element.

[0126] (Configuration 8) The vibration type actuator according to any one of configurations 1 to 7, wherein the foam member is smaller than the elastic body.

[0127] (Configuration 9) The vibration type actuator according to any one of configurations 1 to 8, wherein the main component of the electromechanical energy conversion element is a barium titanate-based material.

[0128] (Configuration 10) The vibration type actuator according to any one of configurations 1 to 9, wherein the main component of the electromechanical energy conversion element is barium calcium titanate zirconate.

[0129] (Configuration 11) An electronic device comprising: a member; and the vibration type actuator according to any one of configurations 1 to 10 provided on the member.

[0130] (Configuration 12) An optical device comprising: at least one of an optical element and an imaging element; and the vibration type actuator according to any one of configurations 1 to 11 provided in the at least one of the optical element and the imaging element.

[0131] (Method 1) A method for manufacturing a vibration type actuator, comprising the steps of: performing a pressure heat treatment on a foam material containing silicone rubber and having bubbles with an average equivalent circular diameter of greater than 120 μm, to obtain a foamed member; bringing an elastic body and an electromechanical energy conversion element into contact with each other to obtain a vibrating body; preparing a contact body; and biasing the vibrating body against the contact body via the foamed member to obtain a vibration type actuator.

[0132] (Method 2) The pressure and heat treatment is carried out at 600 g / cm ２ More than 700g / cm ２ 2. A method for producing a vibration actuator according to method 1, comprising the step of: maintaining the foam material at a temperature of 60° C. or higher and 80° C. or lower under the following pressure.

[0133] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0134] This application claims priority based on Japanese Patent Application No. 2023-096027, filed on June 12, 2023, the entire contents of which are incorporated herein by reference.

[0135] 100 Vibration type actuator 101 Electrode 101a First electrode 101b Second electrode 101c Third electrode 101d Fourth electrode 101e Drive phase electrode 101f Non-drive phase electrode 102 Piezoelectric material 103 Elastic body 104 Contact body 106 Projection portion 107 Support portion 108 Plate portion 110 Vibration body 120 Electrical-mechanical energy conversion element 121 Biasing member 122 Foam member 133 Air bubbles 134 Skin layer 501 Holding member 502 Movable housing 503 Screw 504 Guide member 505 Lens holding member 506 Lens 507 Power supply member 508 Sensor 509 Scale 510 Connecting member

Claims

1. A vibration body having an electromechanical energy conversion element and an elastic body with a plate portion and a protrusion portion protruding in the same direction outside the surface of the plate portion, a contact portion that contacts the protrusion portion of the vibration body and moves relatively to the vibration body, a foam member that contacts the vibration body, and a biasing member that biases the vibration body to the contact portion via the foam member, the foam member containing a siloxane bond (Si-O-Si) consisting of silicon and oxygen, and the number N of silicon contained in the foam member in units of Q is Ｑ Number of D units N Ｄ Ratio to N Ｑ / N Ｄ A vibration actuator, characterized in that:

2. The vibration actuator according to claim 1, wherein the foam member is a sponge containing silicone rubber.

3. The vibration actuator according to claim 1 or 2, characterized in that the average equivalent circular diameter of the bubbles in the foamed material is greater than 120 μm.

4. The vibration actuator according to claim 1 or 2, characterized in that the electromechanical energy conversion element comprises a piezoelectric material and an electrode, and the lead content of the piezoelectric material is 1000 ppm or less.

5. A vibration actuator according to claim 1 or 2, wherein the plate portion is rectangular.

6. The vibration type actuator according to claim 1 or 2, wherein the elastic body has two protrusions.

7. The vibration actuator according to claim 1 or 2, wherein the foam member is smaller than the electromechanical energy conversion element.

8. The vibration actuator according to claim 1 or 2, wherein the foam member is smaller than the elastic body.

9. The vibration actuator according to claim 1 or 2, characterized in that the main component of said electromechanical energy conversion element is a barium titanate system.

10. The vibration actuator according to claim 1 or 2, characterized in that the main component of said electromechanical energy conversion element is barium calcium titanate zirconate.

11. An electronic device comprising: a member; and the vibration actuator according to claim 1 or 2 provided on the member.

12. An optical device comprising at least one of an optical element and an imaging element, and a vibration actuator according to claim 1 or 2 provided on at least one of the optical element and the imaging element.

13. A method for manufacturing a vibration type actuator, comprising the steps of: performing a pressurized heat treatment on a foamed material containing silicone rubber and having bubbles with an average equivalent circular diameter of greater than 120 μm to obtain a foamed member; obtaining a vibrating body by contacting an elastomer and an electromechanical energy conversion element; preparing a contact body; and obtaining a vibration type actuator by biasing the vibrating body against the contact body via the foamed member.

14. The pressure and heat treatment is performed at 600 g / cm ２ More than 700g / cm ２ 14. The method for producing a vibration actuator according to claim 13, further comprising the step of: holding the foaming material at a temperature of 60° C. or more and 80° C. or less under the following pressure.

Images