JP2005303937A - Supporting structure of piezoelectric bimorph element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently derive the vibration quantity of a center when a piezoelectric bimorph element is supported at two points. <P>SOLUTION: The piezoelectric bimorph element 10 is supported at two points on a fixing member 21 using a double-sided adhesive tape 22 with low elasticity. Also, the center having the maximum vibration quantity of the element 10 is connected to a member 30 to be vibrated via a coupling member 32 having high rigidity. Since the supporting member 22 has low elasticity, the expansion or bending of the element 10 is not restricted by the supporting member 22. Also, since the supporting member 22 is thin, the displacement of the element 10 is not absorbed by the supporting member 22. Since the element 10 is coupled with the member 30 via the coupling member 32 having high rigidity, a panel 31 is well vibrated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a support structure for a piezoelectric bimorph element that vibrates a vibrating body such as a panel.

  An apparatus that vibrates a body to be vibrated using a piezoelectric bimorph element includes a panel speaker that vibrates a panel using a piezoelectric bimorph element (see, for example, Patent Document 1).

  As shown in FIG. 12, the piezoelectric bimorph element 10 is obtained by fixing two piezoelectric elements 11 and 12 with an arbitrary elastic plate 13 interposed therebetween. When a signal is applied to the piezoelectric bimorph element 10, one piezoelectric element is The piezoelectric bimorph element 10 is bent when the other piezoelectric element is contracted, and the bending vibration is used.

  As a method for fixing the piezoelectric bimorph element 10, as shown in FIG. 13, one side of the element 10 is fixed by support members 15, 15 and vibration is generated on the other side, or as shown in FIG. 14, the piezoelectric bimorph element 10. There is a device in which the vicinity of both ends is supported by a support member 17 and vibration is generated at the center of the element.

The support system of FIG. 13 can generate a large vibration on the free end side, but since it is cantilevered, it is easily deformed when a load 16 is applied to the displacement generating portion of the piezoelectric bimorph element 10. Specifically, it is used to vibrate lightweight objects. On the other hand, in the case of the supporting method of FIG. 14, the piezoelectric bimorph element 10 is supported at two points, and the deformation with respect to the load on the displacement generating portion is smaller than that of the method of FIG. This is almost the same as the load application direction, and is suitable for supporting a certain weight part and vibrating. On the other hand, in the case of the support method of FIG. 14, the vibration amount of the displacement generating portion is smaller than that of the support method of FIG.
Japanese National Patent Publication No. 11-512256

  As described above, when an arbitrary heavy object 16 is vibrated by the piezoelectric bimorph element 10, it is preferable to use a two-point support system as shown in FIG. 14, but in that case, how to secure the vibration amount is ensured. It becomes a problem. In the case of the two-point support system as shown in FIG. 14, it is necessary to fix the fixing member with a certain degree of rigidity. For example, as shown in FIG. 15 (A), when the structure is such that the element is simply on the arbitrary protrusion 18, the piezoelectric bimorph element 10 easily moves, and the piezoelectric bimorph element 10 or the vibrating body ( 10 + 16) is disengaged from the protrusion 18 (FIG. 15B).

  On the other hand, when the piezoelectric bimorph element 10 is firmly fixed to the support member 19 as shown in FIG. 16, the vibration amount of the piezoelectric bimorph element 10 decreases. The cause is considered as follows. As described above, the piezoelectric bimorph element 10 generates a predetermined displacement at the center of the element by deformation as shown in FIG. 17, but the length L of the piezoelectric bimorph element 10 on the support member 19 side is set to L ′ and L ″. In addition to expansion and contraction, bending a and b occur in the support member 19 portion, and the restraining force of the support portion increases, thereby preventing the bending displacement, thereby reducing the vibration amount of the element.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a support structure for a piezoelectric bimorph element that can efficiently obtain a vibration amount at the center when the piezoelectric bimorph element is supported at two points. To do.

  The invention of claim 1 is a support structure of a piezoelectric bimorph element that is installed on an arbitrary fixing member and vibrates a member to be vibrated, and between the upper surface side of the fixing member and the lower surfaces on both ends of the piezoelectric bimorph element, A double-sided adhesive tape-like support member having flexibility and low elasticity and coated with an adhesive material on both sides is provided to support two points of the bimorph element, and the center portion of the upper surface of the piezoelectric bimorph element and the member to be vibrated are It is connected with the connection member, It is characterized by the above-mentioned.

  According to the first aspect of the present invention, the piezoelectric bimorph element is supported at two points by a double-sided adhesive tape-like support member having flexibility and low elasticity and coated with an adhesive material on both sides. Thus, the vibration amount can be maximized without being restricted by the movement of the piezoelectric bimorph element, and the displacement and movement of the piezoelectric bimorph element with respect to the fixing member can be suppressed. Furthermore, due to the cushioning property of the support member of the piezoelectric bimorph element, it is possible to absorb an impact from the outside and prevent the member to be vibrated and the piezoelectric bimorph element from being destroyed. Furthermore, it is possible to suppress the vibration generated in the piezoelectric bimorph element from leaking to the fixed member side.

According to a second aspect of the present invention, in the structure for supporting a piezoelectric bimorph element according to the first aspect, the supporting member has a tensile elastic modulus of 1.1 × 10 ⁹ N / mm ² or less and a thickness of 1 mm or less. It is characterized by that.

In the second aspect, since the tensile elastic modulus of the support member is 1.1 × 10 ⁹ N / mm ² or less and the thickness is limited to 1 mm or less, the effect of the invention of the first aspect can be obtained with certainty. .

  According to a third aspect of the present invention, there is provided the structure for supporting a piezoelectric bimorph element according to the first or second aspect, wherein the support member has a larger adhesion area to the fixed member side than an adhesion area to the piezoelectric bimorph element side. It arrange | positions so that it may become.

  According to the third aspect of the present invention, since the adhesion area to the fixing member side of the support member is increased with respect to the adhesion area to the piezoelectric bimorph element side of the support member, the restraining force on the piezoelectric bimorph element is suppressed, and Adhesive strength can be secured.

  According to a fourth aspect of the present invention, in the piezoelectric bimorph element support structure according to any one of the first to third aspects, the rigidity of the coupling member is increased with respect to the support member.

  According to the fourth aspect of the present invention, since the rigidity of the connecting member is increased relative to the support member, the vibration of the piezoelectric bimorph element is effectively transmitted to the member to be vibrated.

According to the present invention, it is possible to efficiently obtain the vibration amount of the central portion of the bimorph element supported at two points, and it is also possible to reduce external force and impact force on the piezoelectric bimorph by the flexibility of the support member. It becomes.

  Further, by using the present invention for a touch panel, for example, it is possible to obtain a good vibration generating mechanism for adding a switch feeling to the touch panel.

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows a support structure of a piezoelectric bimorph element. In the present invention, both ends of the piezoelectric bimorph element 10 are supported by the fixing portion 21 using a double-sided adhesive plastic tape having a low elastic modulus and a predetermined adhesive force as the support 22 of the piezoelectric bimorph element 10 as shown in FIG. (2 point support). Then, the upper surface of the central portion where the amplitude of the piezoelectric bimorph element 10 is maximized is connected to the lower surface of the vibrating body 30 using a connecting member 32 having a high elastic modulus.

  In this support structure of the piezoelectric bimorph element, the piezoelectric bimorph element is supported at two points by using a double-sided adhesive plastic tape having low elasticity as the support member 22, so that the expansion and contraction generated at the support portion of the piezoelectric bimorph element is caused by the support member 22. Since it is not restrained, the vibration amount can be maximized. Further, since the support member 22 is a tape and is thin, it is possible to suppress the vibration generated in the piezoelectric bimorph element from leaking to the fixed member side. Accordingly, the vibration of the piezoelectric bimorph element 10 can be vibrated through the connecting member 32 having a high elastic modulus without being restrained or suppressed by the support member 22.

  FIG. 2 shows a panel vibration device according to the example. As shown in the figure, the piezoelectric bimorph element 10 installed on the fixing member 21 is supported by the fixing member 21 at two points via a low-elasticity support member 22. The panel 31 that is vibrated by the piezoelectric bimorph element 10 has a lower surface central portion at one end thereof connected to a central portion of the upper surface of the piezoelectric bimorph element 10 via a highly rigid connecting member 32.

The piezoelectric bimorph element 10 is composed of piezoelectric elements 11 and 12 and an elastic plate 13 sandwiched between them. The piezoelectric elements 11 and 12 are preferably made of lead zirconate titanate (common name: PZT) having a large amount of generated displacement / applied voltage. For material composition, it is possible to change its properties due dopants, as the d31 constant commonly known as a constant indicating the performance of a displacement / voltage, 100 to 400 (× 10 ^{- 12} m / V) is obtained. Electrodes are formed on both surfaces of the piezoelectric bimorph element 10, and the electrode surfaces are insulated from each other. The electrode is formed by, for example, a plating method, a sputtering method, a vapor deposition method, printing or baking, and Ni, Ag, Au, Cu, or the like is used as an electrode material.

  In addition, the piezoelectric bimorph element 10 may have a structure in which the piezoelectric elements 11 and 12 are laminated as shown in FIG. 3 for the purpose of improving the displacement / voltage. For the elastic plate 13 of the piezoelectric bimorph element 10, a metal material having conductivity such as a stainless alloy type or a nickel alloy type is mainly used, but a non-conductive material may be used.

Hereinafter, the support member 22 of the piezoelectric bimorph element 10 will be described in detail. As shown in FIG. 2, the support member 22 is adhered by a predetermined area in the vicinity of both ends in the longitudinal direction of the piezoelectric bimorph element 10, and the support member 22 is also adhered on the fixing member 21 side. Suitable as the support member 22 is a material having a low elastic modulus lower than that of a general plastic material. Specifically, the elastic modulus of polypropylene, which is a low elastic modulus material, is 1.1 × 10. flexible material than ⁹ N / mm ^2, for example, foamed polyurethane, foamed acrylic, foamed polyethylene, foamed butyl rubber, or double-sided adhesive tape which is based on a flexible material having a cushioning property, such as silicon-based materials are suitable.

  For example, the tape No5713 made by Nitto Denko Corporation is a double-sided adhesive tape based on a special foamed polyurethane, and the tape thickness is 0.33 mm. The tape has a flexibility and thickness suitable as the support member 22 in the present invention. It is a tape that I have. When the thickness of the support member 22 increases, there is a problem that the displacement of the piezoelectric bimorph element 10 is easily absorbed, and the thickness of the support member is set to about 1 mm or less.

  As shown in FIG. 2, the support member 22 has a larger adhesion area to the fixing member 21 than an adhesion area to the piezoelectric bimorph element 10. FIG. 4 shows details of this support portion. The adhesion area to the piezoelectric bimorph element 10 is W1 × L1, while the adhesion area to the fixing member 21 is W2 × L2. For the same adhesive material, the adhesive force is approximately proportional to the area, and in the case of FIG. 4, the adhesive force for the piezoelectric bimorph element <the adhesive force for the fixed member.

  As described above, in order to secure the displacement amount of the piezoelectric bimorph element 10, it is necessary to suppress the restraining force by the support member 22 to some extent, while the fixing member 21 side has a predetermined amount from the viewpoint of reliability. It is necessary to ensure adhesive strength. By using the supporting method as shown in FIG. 4, it becomes easy to secure the adhesive strength to the fixing member 21 while suppressing the binding force to the piezoelectric bimorph element 10. L1, L2, and W2 need to be appropriately determined depending on the dimensional constraints of the parts to be mounted.

  In order to prevent the piezoelectric bimorph element 10 from being destroyed by an external force, it is also possible to insert a stopper material 23 having a predetermined thickness under the piezoelectric bimorph element 10 as shown in FIG. The thickness of the stopper member 23 is determined by (support thickness) − (piezoelectric bimorph maximum vibration width / 2) − (predetermined margin).

  When a predetermined external force (impact) is applied to the piezoelectric bimorph element 10, the piezoelectric bimorph 10 is absorbed to some extent by the deformation of the support member 22, but if this limit is exceeded, the piezoelectric bimorph element 10 has a lower part. The stopper 23 can suppress bending deformation due to an external force of the piezoelectric bimorph element 10. As the material of the stopper member 23, a low-elasticity flexible material is suitable, and the above-mentioned foamed material, rubber-based material, and other plastic materials are appropriately used. In addition, it is naturally possible to make this as a protrusion in the shape on the fixing member 21 side.

  For the connecting member 32 that connects the piezoelectric bimorph element 10 and the panel 31, a material that has a higher elastic modulus than the support member 22 of the piezoelectric bimorph element 10 is selected. This is for efficiently transmitting the vibration generated in the piezoelectric bimorph element 10 to the panel 31. The bending portion of the piezoelectric bimorph element 10 is also bent and restrained by the support member 22, and the amount of generated vibration tends to decrease. However, vibration transmission loss also becomes a problem. It is necessary to decide.

  (Confirmation of the effect of the invention) In order to confirm the effect of the present invention, an experiment as shown in FIG. 6 was conducted. In the piezoelectric bimorph element 10 used in the experiment, laminated piezoelectric elements 11 and 12 in which seven piezoelectric layers each having a thickness of 50 μm are stacked sandwich a stainless alloy plate having a thickness of about 0.1 mm as an elastic plate 13. The laminated piezoelectric bimorph element has a width W1 of about 5 mm, a length Lo of about 30 mm, and a thickness of about 0.9 mm. Moreover, the support member 22 used 2 types, the support member 22 (A) using the (A) material shown in FIG. 7, and the support member 22 (B) using the (B) material. (A) Material is No5713 material (thickness 0.33) made by Nitto Denko Corporation using the above-mentioned foamed polyethylene as a material, and the support member 22 (B) is a PET film 22a having a thickness of 0.1 mm. A double-sided adhesive tape 22b (No. 7642 manufactured by Teraoka Seisakusho Co., Ltd.) having a thickness of 0.1 mm is bonded to both sides. The size and arrangement of the support members 22 (A) and 22 (B) are both the same as in FIG.

  The same piezoelectric bimorph element 10 is disposed on the fixing member 21 via the support members 22 (A) and 22 (B), and a weight of 168 g is provided at the center of the upper surface of the piezoelectric bimorph element 10 via the connecting member 32 made of the No5713 material. 33 was connected, a predetermined signal (20 Vpp-10 Hz) was applied to the piezoelectric bimorph element 10, and the vibration amount at the center of the weight 33 was measured by the vibration amount measuring device 41.

As a result, the vibration amount at the center of the weight 33 is about 18 μmpp for the support member 22 (B) relative to about 38 μmpp for the support member 22 (A), and the support member 22 (A) made of the flexible (A) material is reduced. It was confirmed that the vibration amplitude can be increased by using it. Table 1 and FIG. 8 show the vibration amount (amplitude) at each frequency of the (A) material and (B) material. (A) Regarding the material, the increase in the frequency with the increase in frequency is due to the fact that it is close to the resonance frequency.

  Next, in the experimental method shown in FIG. 6, the vibration amount when the support member 22 (A) material is used and the connecting member 32 is the (A) material and the (B) material was compared. The connecting member 32 at this time is 5 mm wide × 5 mm long.

  The results of this comparison are shown in Table 2 and FIG. As a result, it is desirable to use the (B) material having a higher elastic modulus than the flexible (A) material for the connecting member 32 between the piezoelectric bimorph and the vibrating body, and the vibration amount is about 10% with respect to the (A) material. It was found that it is possible to increase

  From the above experimental results, as a method for supporting and connecting the two-point support type piezoelectric bimorph element, it is possible to use a material having high flexibility for the supporting member and to select a material having higher elasticity than the supporting member for the connecting member. This is desirable.

  (Application Example) An application example of the present invention to an electronic device having a touch panel will be described with reference to FIGS. In this electronic device 50, four icons 53a to 53d are displayed on the image display unit 52, and the touch panel 55 is supported by touch panel support members 56 provided at the four corners of the support frame 54 of the image display unit. Has been. The four piezoelectric bimorph elements 10 are supported at two points by the flexible support member 22 of the material (A) in the space between the touch panel 55 and the portion of the support frame 54 where the touch panel support member 56 is not provided. The central portion of each piezoelectric bimorph element 10 and the touch panel 52 are connected by the connecting member 32 made of the material (B) having a high elastic modulus. In addition, the electronic device 50 is provided with control means 57 that outputs a predetermined signal to each piezoelectric bimorph element 10 by inputting a coordinate value output from the touch panel 55 when the touch panel 55 is pressed with a finger.

  Since the electronic device 50 is configured as described above, a predetermined signal is output from the control means 57 to the piezoelectric bimorph element 10 when a part of the touch panel 55 on which the icons 53a to 53d are displayed is touched with a finger. The piezoelectric bimorph element 10 vibrates. The piezoelectric bimorph element 10 is supported at two points by a flexible support member 22, and the piezoelectric bimorph element 10 and the touch panel 55 are connected by a connecting member 32 having a high elastic modulus. A good switch feeling is obtained on the touched finger.

The front view which shows the support structure of the piezoelectric bimorph element concerning embodiment of this invention. The perspective view which shows the panel vibration apparatus which concerns on the Example of this invention. 1 is a schematic cross-sectional view of a laminated piezoelectric bimorph element. It is detail explanatory drawing of a piezoelectric bimorph element support structure, (A) is a front view, (B) is a top view. It is explanatory drawing of the piezoelectric bimorph element support structure which provided the stopper for element breakage prevention, (A) is a front view which shows the state without external force, (B) is a front view when an external force acts. It is a schematic explanatory drawing of the experiment for confirming the effect of invention, (A) is a top view, (B) The front view. It is explanatory drawing of a supporting member, (A) is a side view of (A) material, (B) is a side view of (B) material. The comparison graph of the vibration amount of the piezoelectric bimorph element center part supported by the different support member. The comparison graph of the vibration amount of the piezoelectric bimorph element center part connected by the different connection member. The disassembled perspective view of the electronic device which concerns on an application example. AA sectional drawing of FIG. (A) is a schematic perspective view of a piezoelectric bimorph element. (B) is explanatory drawing of expansion-contraction of a piezoelectric bimorph element, (C) is explanatory drawing of the bending displacement of a piezoelectric bimorph element. (A) Explanatory drawing of the displacement of the free end of the piezoelectric bimorph element supported by the cantilever, (B) Displacement explanatory drawing when there is a load at the free end of the element. (A) An explanatory view of the displacement of a piezoelectric bimorph element supported at two points, (B) is an explanatory view of a displacement in a state where a load is applied to the central portion of the element. (A) is a front view of a vibration generator supported at two points with a piezoelectric bimorph element placed on a protrusion. (B) is explanatory drawing of the state which the element shifted | deviated from the support position. The front view which shows the two-point restraint support state of a piezoelectric bimorph element. Detailed explanatory drawing of the deformation | transformation state of a piezoelectric bimorph element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Piezoelectric bimorph element 11, 12 ... Piezoelectric element, 13 ... Elastic plate, 21 ... Fixing member, 22 ... Support member, 23 ... Stopper, 30 ... Vibrated body, 31 ... Panel, 32 ... Connection member, 33 ... Weight: 41 ... Vibration amount measuring device, 50 ... Electronic device, 51 ... Main body, 52 ... Image display unit, 53a to 53d ... Icon, 54 ... Support frame for image display unit, 55 ... Touch panel, 56 ... Support member for touch panel, 57: Control means.

Claims (4)

A support structure of a piezoelectric bimorph element that is installed on an arbitrary fixing member and vibrates a member to be vibrated,
Between the upper surface side of the fixing member and the lower surfaces of both ends of the piezoelectric bimorph element, a double-sided adhesive tape-like support member having flexibility and low elasticity and coated with an adhesive material on both sides is provided, so that two bimorph elements are provided. Point-supported,
A support structure for a piezoelectric bimorph element, wherein a central portion of an upper surface of the piezoelectric bimorph element and the member to be vibrated are connected by a connecting member. In the support structure structure of the piezoelectric bimorph element according to claim 1,
The support structure for a piezoelectric bimorph element, wherein the support member has a tensile modulus of 1.1 × 10 ⁹ N / mm ² or less and a thickness of 1 mm or less. In the support structure structure of the piezoelectric bimorph element according to claim 1 or 2,
The support structure of a piezoelectric bimorph element, wherein the support member is arranged so that an adhesion area to the fixed member side is larger than an adhesion area to the piezoelectric bimorph element side. In the support structure of the piezoelectric bimorph element according to claim 1,
A structure for supporting a piezoelectric bimorph element, wherein the rigidity of the connecting member is higher than that of the supporting member.

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