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EP-4485790-B1 - VIBRATION-TYPE ACTUATOR AND ELECTRONIC APPARATUS

EP4485790B1EP 4485790 B1EP4485790 B1EP 4485790B1EP-4485790-B1

Inventors

  • SHIMADA, AKIRA

Dates

Publication Date
20260513
Application Date
20240625

Claims (9)

  1. A vibration-type actuator (2) comprising: a vibration body including an electro-mechanical energy conversion element (4) and an elastic body (3) which are bonded to each other via an adhesive (13); and a contact body (9) in contact with the elastic body, wherein the vibration body and the contact body are configured to be relatively moved by vibrations of the vibration body, wherein the elastic body includes: a flat plate portion (3b) that is bonded to the electro-mechanical energy conversion element via the adhesive; and a protrusion (3a) that is continuous to the flat plate portion and that protrudes from the flat plate portion, characterized by the vibration-type actuator further comprising: as part of the adhesive, between the electro-mechanical energy conversion element and the flat plate portion, a first adhesive layer (13a); and a second adhesive layer (13b) that is adjacent to the first adhesive layer, a thickness of the second adhesive layer being larger than a thickness of the first adhesive layer and increasing toward the protrusion, or a third adhesive layer (13c) that is adjacent to the first adhesive layer and that is between the first adhesive layer and an edge portion of the electro-mechanical energy conversion element, a thickness of the third adhesive layer increasing toward the edge portion and being 10 µm or less, and a length (L3) of the third adhesive layer being between 100 µm and 400 µm.
  2. The vibration-type actuator according to claim 1, wherein the thickness of the first adhesive layer is 3 µm or less, and the thickness of the second adhesive layer is between 3 µm and 10 µm.
  3. The vibration-type actuator according to claim 1 or 2, wherein a curved portion of the elastic body, comprising a curved surface different from a linear surface of the flat plate portion that is adjacent to the second adhesive layer, is formed at a root of the protrusion, and wherein a length (L2) in a radial direction of the protrusion on the second adhesive layer in a section from an end portion of the first adhesive layer adjacent to the second adhesive layer to a point where the curved portion abuts the flat plate portion is between 100 µm and 400 µm.
  4. The vibration-type actuator according to any one of claims 1 to 3, further comprising an adhesive pool that is adjacent to the second adhesive layer not on the first adhesive layer side.
  5. The vibration-type actuator according to any one of the preceding claim, wherein the elastic body is made of martensite stainless steel, and a surface of the elastic body on the electro-mechanical energy conversion element side is a surface formed through quenching after rolling.
  6. The vibration-type actuator according to claim 5, wherein a surface roughness Ra of the surface is between 0.025 µm and 0.2 µm.
  7. The vibration-type actuator according to any one of the preceding claims, wherein a difference between a maximum value and minimum value of a thickness of the flat plate portion is 10 µm or less.
  8. An optical apparatus comprising: the vibration-type actuator according to any one of claims 1 to 7; and at least one of an optical element and an image pickup element configured to be driven by the vibration-type actuator.
  9. An electronic apparatus comprising: a member; and the vibration-type actuator according to any one of claims 1 to 7, the vibration-type actuator being configured to drive the member.

Description

TECHNICAL FIELD The present disclosure relates to a vibration-type actuator and an electronic apparatus including the vibration-type actuator. BACKGROUND Description of the Related Art Japanese Patent No. 5930595 discusses a vibration wave motor using, as a vibration generation source, an electro-mechanical energy conversion element, such as a piezoelectric element. The vibration wave motor includes a vibrator and a contact body. The vibrator includes a plate-type elastic body and a piezoelectric element fixed to the reverse side of the elastic body. The elastic body has an upper surface provided with two protrusions arranged on it. The contact body is in pressure contact with the protrusions. In this vibration wave motor, a predetermined alternating voltage is applied to the electro-mechanical energy conversion element. This excites two bending vibrations (standing waves) to generate an elliptic, or circular, motion at the ends of the protrusions (e.g., including a contact surface of each protrusion that is arranged in pressure contact with the contact portion). The motion occurs in a plane which includes directions which connect the two protrusions (e.g., a direction which intersects both protrusions), and a protruding direction of the protrusion. The contact body that is in pressure contact with the protrusions then receives frictional drive force (thrust force) from the two projections, which makes it possible to relatively move the vibrator and the contact body in a direction that connects the two protrusions. On the other hand, actuators, such a vibration wave motor, have been demanded to be smaller in size and drive larger objects in order to downsize electronic apparatuses, which means high-power densification in actuators. A known vibration-type actuator is described in JP2014217143A. With the trend toward the high-power densification in vibration wave motors, there is a concern that an adhesive that is generally used to bond a piezoelectric element and an elastic body can be peeled due to higher stress applied to the vibrator. SUMMARY In view of such an issue, the present disclosure is directed to providing a vibration wave motor with high output power and adhesion reliability and an electronic apparatus including the vibration wave motor. According to a first aspect of the present disclosure, there is provided a vibration-type actuator comprising: a vibration body including an electro-mechanical energy conversion element and an elastic body which are bonded to each other via an adhesive; and a contact body in contact with the elastic body, wherein the vibration body and the contact body are configured to be relatively moved by vibrations of the vibration body, wherein the elastic body includes: a flat plate portion that is bonded to the electro-mechanical energy conversion element via the adhesive; and a protrusion that is continuous to the flat plate portion and that protrudes from the flat plate portion, the vibration-type actuator further comprising: as part of the adhesive, between the electro-mechanical energy conversion element and the flat plate portion, a first adhesive layer; and a second adhesive layer that is adjacent to the first adhesive layer, a thickness of the second adhesive layer being larger than a thickness of the first adhesive layer and increasing toward the protrusion, or a third adhesive layer that is adjacent to the first adhesive layer and that is between the first adhesive layer and an edge portion of the electro-mechanical energy conversion element, a thickness of the third adhesive layer increasing toward the edge portion and being 10 µm or less, and a length of the third adhesive layer being between 100 µm and 400 µm. According to a second aspect, there is provided an optical apparatus comprising: the vibration-type actuator according to the first aspect; and at least one of an optical element and an image pickup element configured to be driven by the vibration-type actuator. According to a third aspect there is provided an electronic apparatus comprising: a member; and the vibration-type actuator according to the first aspect. The vibration-type actuator being configured to drive the member. Optional features will now be set out. These are applicable singly or in any combination with any aspect of the disclosure. The thickness of the second adhesive layer may be between 3 µm and 10 µm. A curved portion of the elastic body comprising a curved surface different from a linear surface of the flat plate portion that is adjacent to the second adhesive layer may be formed at a root of the protrusion. A length in a radial direction of the protrusion on the second adhesive layer in a section from an end portion of the first adhesive layer adjacent to the second adhesive layer to a point where the curved portion abuts the flat plate portion may be between 100 µm and 400 µm. The vibration-type actuator may further comprise an adhesive pool that is adjacent to the second adhesi