JP2007258556A - Multilayered piezoelectric actuator device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered piezoelectric actuator device which is miniaturized without affecting the movement distance of a sliding member, and is hardly broken by obtaining strength in a fixture between a multilayered piezoelectric actuator element and a driving member. <P>SOLUTION: The multilayered piezoelectric actuator device includes: the multilayered piezoelectric actuator element 5, the driving member 7, and the sliding member 8. The sliding surface of the driving member 7, where the sliding member 8 is slid, is arranged between two surfaces which respectively include both the end surfaces of the multilayered piezoelectric actuator element 5. An elastic member 10 is filled in a gap formed between the multilayered piezoelectric actuator element 5 and the driving member 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated piezoelectric actuator device suitable for a small linear actuator using a laminated piezoelectric actuator element.

  Piezoelectric elements made of so-called piezoelectric ceramic materials such as lead zirconate titanate are used in a wide range of fields as electro-mechanical conversion elements. Piezoelectric elements can be obtained by pressing a raw material powder of a piezoelectric ceramic material into a sintered body through a firing process, and a general piezoelectric element obtained by processing a sintered powder from a raw material powder of the same piezoelectric ceramic material. There is a multilayer piezoelectric element obtained by forming a thin film by a film formation process, and further through a printing / lamination / firing process.

  In particular, the latter laminated piezoelectric element is widely used as an actuator because it can obtain a large displacement and a large generating force even if it is small. A laminated piezoelectric element used as this actuator is called a laminated piezoelectric actuator element, and an actuator device using this is called a laminated piezoelectric actuator device.

  In recent years, with the miniaturization of electronic devices and devices, the demand for miniaturization of actuator devices has become stronger. For example, an actuator device for moving a lens is used in a camera lens module mounted on a mobile phone. Conventionally, an electromagnetic motor has been used for this type of actuator device.

  However, there is a limit to further miniaturizing the electromagnetic motor when mounted on a mobile phone. Therefore, there has been proposed an actuator device in place of an electromagnetic motor that uses a piezoelectric element that can convert electric energy into driving force, has high conversion efficiency, is small and light, and has a large generated force.

  FIG. 1 is a cross-sectional view of a conventional multilayer piezoelectric actuator device. A laminated piezoelectric actuator device 101 shown in FIG. 1 includes a laminated piezoelectric actuator element 105 having one end face fixed to a fixing member 106, a driving member 107 fixed to the other end face of the laminated piezoelectric actuator element 105, and a driving member. And a sliding member 108 having a surface 107 as a sliding surface. In this multilayer piezoelectric actuator device 101, the sliding member 108 moves in the direction A and the direction B indicated by the arrows due to the displacement and driving force generated by the multilayer piezoelectric actuator element 105. Therefore, the movement of the sliding member 108 is used as an actuator. Can be used. Such a multilayer piezoelectric actuator device is disclosed in Patent Document 1 or Patent Document 2.

JP 2003-69100 A JP 2006-5998 A

  As described above, the conventional multilayer piezoelectric actuator device has a structure in which the driving member is bonded to the end portion that generates the displacement of the multilayer piezoelectric actuator element, and the sliding member moves on the driving member. As shown in FIG. 1, the length 110 of the operation portion of the multilayer piezoelectric actuator device 101 is a length 110 that is the sum of the length 104 of the multilayer piezoelectric actuator element 105 and the length 109 of the drive member 107. For this reason, there is a problem that the total length of the piezoelectric actuator device becomes long and cannot be miniaturized.

  Further, since the conventional multilayer piezoelectric actuator device has a structure in which the driving member is fixed to the end face of the multilayer piezoelectric actuator element with an adhesive, the strength of the fixing portion cannot be obtained, and the multilayer piezoelectric actuator element is caused by an external impact. There is a problem that the drive member is separated and the function of the device is lost.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art. Specifically, it is an object of the present invention to provide a multilayer piezoelectric actuator device that can be reduced in size without impairing the moving distance of the sliding member, can obtain the strength of the fixing portion between the multilayer piezoelectric actuator element and the drive member, and is not easily damaged. And

  The present invention employs the following means in order to solve the above problems. That is, according to the present invention, a laminated piezoelectric actuator device, a driving member, and a sliding member constitute a laminated piezoelectric actuator device, and the sliding surface of the driving member on which the sliding member slides is formed on the laminated piezoelectric actuator element. The gist of the present invention is to dispose an elastic member in a gap formed by the laminated piezoelectric actuator element and the drive member, between the two surfaces including the both end surfaces.

  According to the present invention, a column having a first end surface and a second end surface that expands and contracts in the stacking direction and is orthogonal to the stacking direction and includes the first end surface, the second end surface, and a side surface. A laminated piezoelectric actuator element forming a body, a fixed portion and an extending portion, wherein the fixed portion is at least partially fixed to the first end surface, and the extending portion has the first end surface A driving member extending in a space sandwiched between a surface including the second end surface and a sliding member sliding on the surface of the extending portion of the driving member. A multilayer piezoelectric actuator device characterized by the above can be obtained.

  The multilayer piezoelectric actuator device according to the present invention uses a multilayer piezoelectric actuator element obtained by making a slurry from a raw material powder of a piezoelectric ceramic material, making it into a thin film by a film forming process, and further through a printing, laminating and firing process. The laminated piezoelectric actuator element comprises a laminated body in which piezoelectric ceramic layers and internal electrode layers are alternately laminated in a thickness direction, and the internal electrode is disposed on two side surfaces parallel to and opposite to the lamination direction. Are alternately taken out and connected by external electrodes provided on the respective side surfaces.

  By applying an electric field between the two external electrodes provided on the side surface, the piezoelectric ceramic layer sandwiched between the opposing internal electrode layers is distorted in the stacking direction, and the total distortion of each piezoelectric ceramic layer is Obtained as displacement.

  In the present invention, the multilayer piezoelectric actuator element has a pillar body composed of two end surfaces and a side surface of a first end surface and a second end surface orthogonal to the stacking direction, and the second end surface is a fixing member. And a fixing portion of the driving member is fixed to the first end face. The driving member has an extending portion, and a sliding member having a surface of the extending portion as a sliding surface is disposed. The structure of the driving member is a space formed by a virtual surface including a second end surface fixed to the fixing member of the multilayer piezoelectric actuator element and a virtual surface including a first end surface to which the driving member is fixed. In such a structure, the extending portion is disposed in

  In the multilayer piezoelectric actuator device according to the present invention, the sliding surface on which the sliding member slides does not extend in the longitudinal direction from the first surface portion to which the driving member of the multilayer piezoelectric actuator element is fixed. It is arrange | positioned in the direction which goes to the 2nd surface part. Therefore, the length of the operation part of the multilayer piezoelectric actuator device according to the present invention is not the total length of the multilayer piezoelectric actuator element and the length of the driving member, but the length of the multilayer piezoelectric actuator element. A small stacked piezoelectric actuator device in which only a small length of the portion for fixing the driving member is added is obtained.

  According to the present invention, it is possible to obtain a multilayer piezoelectric actuator device in which the fixed portion and the extending portion form a bottomed cylindrical body. In the multilayer piezoelectric actuator device according to the present invention, for example, the drive member is composed of a short side and a long side, the cross section is L-shaped, and the short side is fixed to the first end surface of the multilayer piezoelectric actuator element. However, a sliding surface may be provided on the long side. The drive member has a long side extending at both ends of the short side so that the cross section has a U-shape, and a laminated piezoelectric actuator element is disposed between the two long sides. The first end face may be fixed on the short side and a sliding face may be provided on the long side. Furthermore, it is better that the driving member is a bottomed cylindrical body, the laminated piezoelectric actuator element is inserted into the hollow portion of the cylindrical body, and the first end face of the laminated piezoelectric actuator element is fixed to the inner bottom surface. In addition, what is necessary is just to select suitably the shape of the bottom part of a cylinder according to use conditions, such as circular, an ellipse, and a polygon.

  According to the present invention, the laminated piezoelectric actuator is characterized in that the space formed by the side surface of the laminated piezoelectric actuator element and the surface of the extending portion of the driving member is filled with an insulating elastic member. An actuator device is obtained.

  Further, according to the present invention, an insulating silicone resin, urethane resin, rubber, or the like having a space formed by the surface of the multilayer piezoelectric actuator element and the surface of the extending portion of the driving member fixed to the multilayer piezoelectric actuator element By filling the elastic member having the insulating property, the strength of the fixing portion between the multilayer piezoelectric actuator element and the drive member can be increased without impairing the displacement generated by the multilayer piezoelectric actuator element or the generated force. .

  According to the present invention, it is possible to obtain a multilayer piezoelectric actuator device in which the second end surface forms a fixed end fixed to a fixing member. In the multilayer piezoelectric actuator device according to the present invention, in the multilayer piezoelectric actuator element, the second end face opposite to the first end face to which the fixing portion of the driving member is fixed is used as a fixed end for fixing to the fixing member. Thus, a stacked piezoelectric actuator device having a large moving distance of the sliding member is obtained.

  As described above, according to the present invention, the multilayer piezoelectric actuator device can be downsized without impairing the moving distance of the sliding member, the strength of the fixing portion between the multilayer piezoelectric actuator element and the driving member is obtained, and the damage is less likely to occur. Provision is possible.

  The multilayer piezoelectric actuator device according to the present invention includes a multilayer piezoelectric actuator element, a driving member, and a sliding member, and the sliding surface of the surface of the driving member on which the sliding member slides is the surface of the multilayer piezoelectric actuator element. It is disposed between two virtual surfaces including both end surfaces, and an elastic member is filled in the gap formed by the laminated piezoelectric actuator element and the drive member.

  Hereinafter, a specific example will be given and an embodiment of a multilayer piezoelectric actuator device according to the present invention will be described in detail with reference to the drawings.

Example 1
FIG. 2 is a perspective view of the multilayer piezoelectric actuator element according to the embodiment. The laminated piezoelectric actuator element 5 used in this example is a laminated body in which piezoelectric ceramic layers 1 and internal electrode layers 2 are alternately laminated. In this laminate, a raw material powder of a piezoelectric ceramic material is made into a slurry to obtain a thinned green sheet by a film forming process, and then a green sheet to be a piezoelectric ceramic layer 1 and an internal electrode layer 2 on which an electrode paste is printed. The green sheets alternately stacked are cut into a predetermined size and fired.

  On the two side surfaces that are parallel to and opposite to the stacking direction of the stacked body, every other portion where the internal electrode layer 2 is exposed on the surface is insulated by a glass insulating layer 3. Further, the internal electrode layer 2 is insulated by the insulating layer 3 at a portion where only one of the two side surfaces is exposed per layer. Further, external electrodes 4 for connecting the internal electrode layer 2 not provided with the insulating layer 3 were formed on the two side surfaces.

  The one end face of the multilayer piezoelectric actuator element 5 shown in FIG. 2 is a free end 11 as a first end face, and the other end face is a fixed end 12 as a second end face. In the vicinity of the free end portion 11 and the fixed end portion 12, a portion where only the piezoelectric ceramic layer 1 is laminated without the internal electrode layer 2 is provided. This secures the strength of fixing when fixing the fixed end 12 or fixing another member to the free end 11, and the influence of the protruding adhesive used for fixing the internal electrode layer And an inactive portion for preventing the piezoelectric ceramic layer between the internal electrode layers from receiving.

  FIG. 3 is a cross-sectional view of the multilayer piezoelectric actuator device according to the embodiment. In this embodiment, the fixed end 12 of the multilayer piezoelectric actuator element 5 is fixed to the fixing member 6 with an adhesive, and the driving member 7 is fixed to the free end 11 with an adhesive. As shown in FIG. 3, the drive member 7 has a cylindrical shape with a bottom having a U-shaped cross section in the longitudinal direction. In addition, the cross section in the plane perpendicular to the longitudinal direction is a square shape (not shown). The laminated piezoelectric actuator element 5 is inserted into the cylinder while maintaining a certain gap from the inner wall of the cylinder, and the free end 11 is fixed to the inner bottom surface with an adhesive.

  A sliding member 8 having the surface of the driving member 7 as a sliding surface is disposed on the surface of the driving member 7. The sliding member 8 is held by a frictional force with the sliding surface. When the multilayer piezoelectric actuator element 5 is expanded and contracted by an electric signal input from the outside, the driving member 7 is simultaneously displaced according to the expansion and contraction amount of the multilayer piezoelectric actuator element 5. At this time, when the displacement is slow, the sliding member 8 makes the same displacement while being held by the driving member 7 due to the frictional force with the sliding surface. When the displacement is steep, the driving member 7 is displaced by swinging the frictional force, so that the sliding member 8 is not displaced and remains in place. By controlling the expansion / contraction speed of the multilayer piezoelectric actuator element 5 in this way, the sliding member 8 can move in the direction A or the direction B indicated by the arrow in FIG.

  In this embodiment, the range in which the sliding member 8 moves is the distance indicated by the length 9 on the surface of the driving member 7. Therefore, the total length of the multilayer piezoelectric actuator device is a length obtained by adding the thickness 22 of the fixed portion of the driving member 7 to the total length 21 of the multilayer piezoelectric actuator element 5, and is smaller than the conventional example shown in FIG. .

(Example 2)
FIG. 4 is a cross-sectional view of the multilayer piezoelectric actuator device according to the embodiment. In this example, in the multilayered piezoelectric actuator device manufactured in Example 1, the gap between the multilayered piezoelectric actuator element 5 and the inner wall of the driving member 7 was filled with silicone resin as the elastic member 10. The elastic member 10 does not hinder expansion and contraction of the multilayer piezoelectric actuator element 5 and also mitigates vibrations and shocks from the outside to prevent direct transmission to the multilayer piezoelectric actuator element 5. Compared to the piezoelectric actuator device, the fixing strength between the laminated piezoelectric actuator element 5 and the driving member 7 can be further improved.

  Table 1 shows the result of evaluating the fixing strength of the multilayer piezoelectric actuator element 5 and the drive member 7 in the multilayer piezoelectric actuator device according to the conventional product and the first and second embodiments shown in FIG. In the evaluation, the driving member 7 was pulled with a spring perpendicularly to the fixed surface with the multilayer piezoelectric actuator element 5, and the tensile force when the fixed state was broken was measured.

  As can be seen from the results in Table 1, the laminated piezoelectric actuator device according to Example 2 is a laminated piezoelectric actuator that is formed by filling the gap between the laminated piezoelectric actuator element and the U-shaped driving member with an elastic member. It was found that the adhesive strength between the element and the driving member is increased as compared with the conventional product.

  According to the present invention, the end face of the multilayer piezoelectric actuator element is fixed to the fixing member, and the U-shaped driving member is fixed to the opposite end face with the adhesive, thereby moving the sliding member. While the distance is the same as the conventional product, the shape can be reduced.

  Also, by filling the gap between the multilayer piezoelectric actuator element and the inner wall of the drive member with an elastic member, the adhesive strength between the multilayer piezoelectric actuator element and the drive member of the multilayer piezoelectric actuator device can be increased.

  As described above, according to the present invention, the multilayer piezoelectric actuator device can be downsized without impairing the moving distance of the sliding member, the strength of the fixing portion between the multilayer piezoelectric actuator element and the driving member is obtained, and the damage is less likely to occur. Provision is possible.

  The multilayer piezoelectric actuator device according to the present invention can be used as an actuator for driving and positioning of precision instruments such as cameras and measuring instruments.

Sectional drawing of the conventional lamination type piezoelectric actuator apparatus. The perspective view of the lamination type piezoelectric actuator element by an Example. Sectional drawing of the multilayer piezoelectric actuator apparatus by an Example. Sectional drawing of the multilayer piezoelectric actuator apparatus by an Example.

Explanation of symbols

1 Piezoelectric Ceramics Layer 2 Internal Electrode Layer 3 Insulating Layer 4 External Electrode
5 Laminated piezoelectric actuator elements 6, 106 Fixed members 7, 107 Drive members 8, 108 Sliding members 9, 104, 109, 110 Length 10 Elastic member 11 Free end 12 Fixed end 21 Total length 22 Thickness 101 Laminated Piezoelectric actuator device 105 Stacked piezoelectric actuator elements A, B direction

Claims (4)

  A stacked piezoelectric element that has a first end surface and a second end surface that extend and contract in the stacking direction and that are orthogonal to the stacking direction, and forms a columnar body including the first end surface, the second end surface, and a side surface. An actuator element; a fixed portion; and an extended portion, wherein the fixed portion is at least partially fixed to the first end surface, and the extended portion includes the surface including the first end surface and the second end surface. A laminated member characterized by comprising: a driving member extending in a space sandwiched between surfaces including the end face; and a sliding member sliding on the surface of the extending portion of the driving member. Piezoelectric actuator device.   The stacked piezoelectric actuator device according to claim 1, wherein the fixed portion and the extending portion form a bottomed cylindrical body.   3. The elastic member having an insulating property is filled in a space formed by a side surface of the multilayer piezoelectric actuator element and a surface of the extending portion of the driving member. A multilayer piezoelectric actuator device according to claim 1.   4. The stacked piezoelectric actuator device according to claim 1, wherein the second end surface forms a fixed end fixed to a fixing member. 5.

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