JP2006081998A - Piezoelectric vibration element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric vibration element that can fully prevent a piezoelectric vibrator from breaking and that does not increase the number of components. <P>SOLUTION: A deformation suppressing layer 19 is formed on both sides of a vibrating part 5b that is not supported by the holder 3 of the piezoelectric vibrator 5. The deformation suppressing layer 19 does not substantially affect the vibration of the piezoelectric vibrator 5 during the operation. However, it is constituted to suppress occurrence of deformation that damages the piezoelectric vibrator 5, when a large impact is applied from the outside to such an extent that a part of the piezoelectric vibrator 5 is shaken to come into contact with width regulating means 9, 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric vibration element used for a piezoelectric sound generator or the like.

Japanese Patent Application Laid-Open No. 11-94871 discloses a piezoelectric vibration element used for an acceleration sensor. This piezoelectric vibration element includes a piezoelectric vibration body in which a piezoelectric element is bonded to a vibration plate, and a support body that supports one end of the piezoelectric vibration body. In this type of piezoelectric vibration element, there is a problem that when the piezoelectric vibrating body vibrates more than necessary due to a drop of a device on which the element is mounted, the piezoelectric vibrating body is greatly bent and the piezoelectric element is damaged. . In view of this, in this piezoelectric vibration element, vibration width restricting means for restricting the vibration width of the piezoelectric vibration body is arranged on both sides of the vibration direction of the piezoelectric vibration body. When the piezoelectric vibrating body vibrates more than necessary, the vibration width regulating means comes into contact with a part of the piezoelectric vibrating body and regulates the vibration width of the piezoelectric vibrating body.
JP-A-11-94871

  However, even if such a deflection width restricting means is disposed on both sides of the vibration direction of the piezoelectric vibrating body, the piezoelectric element cannot be sufficiently prevented from being damaged.

  An object of the present invention is to provide a piezoelectric vibration element that can sufficiently prevent damage to a piezoelectric vibrating body.

  Another object of the present invention is to provide a piezoelectric vibration element that facilitates the assembly of the piezoelectric vibration element to a device and does not increase the number of components.

  The piezoelectric vibration element of the present invention includes a piezoelectric vibration body in which one or more piezoelectric elements are bonded to a vibration plate, and a support body that supports the piezoelectric vibration body so as to vibrate. The piezoelectric vibration element is used in a state in which a swing width restricting unit that restricts the swing width of the piezoelectric vibrating body is arranged on both sides of the vibration direction of the piezoelectric vibrating body. In the present invention, the deformation suppressing layer is formed on the vibration portion that is not supported by the support of the piezoelectric vibration member. This deformation suppression layer does not significantly affect the vibration of the piezoelectric vibrating body during operation, but when a large impact is applied from the outside so that a part of the piezoelectric vibrating body is in contact with the swing width regulating means. In addition, the piezoelectric vibrator is formed so as to suppress deformation that damages the piezoelectric vibrator.

  The inventor of the present application, in the case where the swing width restricting means is arranged, when a considerably large impact is applied from the outside, after the tip of the piezoelectric vibrating body comes into contact with the swing width restricting means, the portion on the support side from the tip However, it has been found that the deformation continues in the direction in which the deflection width restricting means is arranged, and the deformation causes the piezoelectric vibrating body to be damaged. Therefore, the inventor of the present application has formed a deformation suppression layer on the vibrating portion of the piezoelectric vibrating body in order to suppress such deformation from occurring in the piezoelectric vibrating body. This deformation suppression layer is effective to substantially reinforce the mechanical strength of the piezoelectric vibrator or a part of the piezoelectric vibrator when the deformation is further continued after the tip of the piezoelectric vibrator comes into contact with the deflection regulating means. Demonstrate the effect of increasing the rigidity. Therefore, according to the present invention, it is possible to prevent the piezoelectric vibrating body from being damaged even when a large impact exceeding the impact dealt with by the swing width regulating means is applied when the swing width regulating means is arranged. In particular, according to the present invention, it is possible to sufficiently prevent the piezoelectric vibrator from being damaged without increasing the number of parts.

  The piezoelectric vibration element of the present invention can also be applied to a so-called cantilever piezoelectric vibration element in which one end of the piezoelectric vibration body in the longitudinal direction is supported by a support so as to vibrate. The present invention can also be applied to a so-called double-sided piezoelectric vibration element in which the center portion is supported by a support so as to vibrate. When using a long and narrow piezoelectric vibrator with piezoelectric elements bonded to the front and back surfaces of the diaphragm, and supporting the central part in the longitudinal direction of the piezoelectric vibrator so that it can vibrate by the support, the central part of the piezoelectric vibrator A deformation suppression layer is formed on the pair of vibrating portions located on both sides of the plate.

  The deformation suppression layer can be formed from an electrically insulating material having elasticity or flexibility. When the deformation suppression layer is formed of such a material, a necessary deformation suppression effect can be easily obtained by appropriately changing the thickness and pattern of the deformation suppression layer.

  The deformation suppression layer can be formed on at least one of the front surface and the back surface of the vibration part. In order to prevent the normal operation from being affected as much as possible, it is preferable to form the deformation suppression layer in a balanced manner on both the front and back surfaces of the vibration part. Specifically, the deformation suppression layer is formed at a position adjacent to the fixed end or a position near the fixed end at an intermediate position between the fixed end and the free end located on the support side of the vibration part. preferable.

  Although it depends on the structure of the piezoelectric vibrator, the distance from the fixed end to the deformation suppression layer is 4 to 15% of the longitudinal dimension of the vibration part, and the distance from the free end to the deformation suppression layer is the vibration part. It is preferable to make it 30 to 50% of the dimension in the longitudinal direction.

  Further, the deformation suppressing layer is preferably formed at an intermediate position so as to suppress the vibration width of the vibrating portion located within 5 mm from the fixed end to 0.5 mm or less. In this case, the piezoelectric vibrator is practically prevented from being damaged. Within this range, the piezoelectric vibrating body can be prevented from being damaged by the deformation suppressing layer having the minimum size.

  The deformation suppression layer can be formed by various methods. For example, the synthetic resin paste can be formed by printing on at least one of the front and back surfaces of the vibration part. In addition, the synthetic resin sheet can be formed by sticking on at least one of the front surface and the back surface of the vibration part. In this way, the deformation suppressing layer can be easily formed when mass-producing the piezoelectric vibration element.

  According to the present invention, in the case where the deflection width regulating means is arranged, the piezoelectric vibrating body can be sufficiently prevented from being damaged even when a large impact is applied that exceeds the impact dealt with by the deflection width regulating means. Benefits are gained. In particular, according to the present invention, it is possible to prevent the piezoelectric vibrator from being damaged without increasing the number of parts.

  The best mode for carrying out the present invention will be described below with reference to the drawings. 1 and 2 are a front view and a plan view of a piezoelectric sounding device that constitutes a piezoelectric vibration element according to an embodiment of the present invention. In FIG. 1, some thickness dimensions are exaggerated for easy understanding. Further, in FIG. 2, the piezoelectric sounder is drawn with the upper wall 9 described later removed. The piezoelectric sounder 1 of this example includes a support body 3 and a piezoelectric vibrating body 5 supported by the support body 3. An upper wall 9 and a lower wall 11 are arranged on both sides in the vibration direction of the piezoelectric vibrating body 5. In this example, the upper wall 9 and the lower wall 11 constitute a swing width regulating means for regulating the swing width of the piezoelectric vibrating body 5. The support 3 has a rectangular parallelepiped shape made of polybutylene terephthalate (PBT) or the like, and is disposed on the lower wall 11. A notch 3a extending parallel to the direction in which the lower wall 11 extends is formed above the support 3.

  The piezoelectric vibrating body 5 includes a diaphragm 13, a first piezoelectric element 15, and a second piezoelectric element 17. That is, in this example, a bimorph type piezoelectric element is employed in which the piezoelectric elements 15 and 17 are joined to both of the diaphragm 13. The diaphragm 13 has an elongated rectangular plate shape having a front surface 13a and a back surface 13b, and is formed of a metal plate made of iron-nickel alloy, brass or the like. The first piezoelectric element 15 is a laminated piezoelectric element having a structure in which a plurality of piezoelectric ceramic layers and electrode layers are alternately laminated so as to have a first electrode 15a on the front surface and a second electrode 15b on the back surface. . In the first piezoelectric element 15, the second electrode 15 b is joined to the surface 13 a of the diaphragm 13 so as to be electrically conductive so as to leave the outer peripheral surface portion 13 c of the surface 13 a of the diaphragm 13. Similarly to the first piezoelectric element 15, the second piezoelectric element 17 has a plurality of piezoelectric ceramic layers and electrode layers alternately laminated so that the first electrode 17a is provided on the front surface and the second electrode 17b is provided on the back surface. A laminated piezoelectric element having the above structure. In the second piezoelectric element 17, the second electrode 17 b is joined to the back surface 13 b of the vibration plate 13 so as to be electrically conductive so as to leave the back surface outer peripheral surface portion 13 d of the back surface 13 b of the vibration plate 13. The longitudinal center portion 5 a of the piezoelectric vibrating body 5 is fitted and fixed in the cut portion 3 a of the support 3. Thereby, in a state where the longitudinal center portion 5a of the piezoelectric vibrating body 5 is supported by the support body 3, the pair of vibration portions 5b and 5b that are not supported by the support body 3 vibrate in the vertical direction. In this example, laminated piezoelectric elements are used as the first and second piezoelectric elements 15 and 17, but a single-layered piezoelectric element can also be used.

  A deformation suppressing layer 19 is formed on a part of each of the surfaces of the pair of vibrating portions 5b and 5b. That is, four deformation suppression layers 19 are formed. The deformation suppressing layer 19 is made of a synthetic resin of an elastic or flexible electric insulating material made of silicon rubber, urethane rubber or the like, and substantially affects the vibration of the piezoelectric vibrating body 5 during operation. However, the piezoelectric vibrator 5 is prevented from being deformed so as to damage the piezoelectric vibrator 5. In this example, the deformation suppression layer 19 was formed in a thickness dimension of 0.02 to 0.3 mm by a printing pattern. The deformation suppression layer 19 is an intermediate portion between the pair of vibrating portions 5b and 5b, the fixed end portion 5c on the support side, the free end portion 5d, and the end portions 5e and 5f in the width direction at predetermined intervals. It is formed at a position adjacent to the fixed end 5c at the position. The distance L2 from the fixed end 5c to the end of the deformation suppression layer 19 is 4 to 15% of the longitudinal distance L1 of the vibration part 5b, and the distance L3 from the free end 5d to the end of the deformation suppression layer 19 Is preferably 30 to 50% of the distance L1 in the longitudinal direction of the vibrating portion 5b. These deformation suppression layers 19 can also be formed by attaching a synthetic resin sheet with an adhesive.

  In the piezoelectric sounder 1 of this example, when the piezoelectric vibrating body 5 vibrates more than necessary due to a large impact applied from the outside, the top end of the piezoelectric vibrating body 5 comes into contact with the upper wall 9 or the lower wall 11 and the piezoelectric vibration is generated. The swing width of the body 5 is regulated. However, when the impact is large, the deformation of the vibrating portion continues even after the tip of the piezoelectric vibrating body 5 contacts the upper wall 9 or the lower wall 11. That is, after the tip, the deformation continues so that the vibration portion near the fixed end portion 5 c comes into contact with the upper wall 9 or the lower wall 11. The greater the impact applied from the outside, the wider the range of this deformation approaches the fixed end 5c. However, in the present invention, the deformation suppressing layer 19 exerts an effect of suppressing the deformation of the vibrating portion adjacent to the fixed end portion 5c, so that the piezoelectric vibrating body 5 can be prevented from being damaged.

Next, using a piezoelectric vibration element that does not form a deformation suppression layer, weights are applied to various distances from the fixed end, and the amount of displacement of the piezoelectric vibrator and the damage state of the piezoelectric vibrator at the position where each weight is applied. I investigated the relationship. Table 1 shows the measurement results.

  In Table 1, X is the distance from the fixed end to which the weight is applied, Y is the vibration width of the piezoelectric vibrator at the position to which the weight is applied, and the numerical values in the table are the five piezoelectric vibrations used in the test. This is the number of broken piezoelectric vibrators in the body. From Table 1, it can be seen that if the vibration width of the portion located within 5 mm from the fixed end is 0.5 mm or less, the piezoelectric vibrator can be prevented from being damaged.

  Hereinafter, the configuration of the piezoelectric vibration element which is the premise of the present invention invented by the inventors in the course of carrying out the present invention will be described. FIG. 3 is a front view of a piezoelectric sounder constituting the piezoelectric vibration element of the first reference example which is a premise of the present invention. In the piezoelectric sounder of the present reference example, a deformation suppressing spacer 119 is provided on each of the upper wall 109 and the lower wall 111. The deformation suppressing spacers 119 are formed on both surfaces of the pair of vibrating portions 105b of the piezoelectric vibrating body 105 with a gap therebetween. Further, the deformation suppressing spacer 119 is disposed corresponding to the intermediate position of the vibration portion 105b spaced from the fixed end portion 105c and the free end portion 105d of the pair of vibration portions 105b on the support body 103 side by a predetermined distance. ing.

  In the piezoelectric sounder 101 of this reference example, when the piezoelectric vibrating body 105 vibrates more than necessary due to a large impact applied from the outside, the top end of the piezoelectric vibrating body 105 comes into contact with the upper wall 109 or the lower wall 111 at the beginning. The swing width of the vibrating body 105 is regulated. However, when the impact is large, the deformation of the vibrating portion continues even after the tip of the piezoelectric vibrating body 105 contacts the upper wall 109 or the lower wall 111. The greater the impact applied from the outside, the wider the range of this deformation approaches the fixed end 105c. However, in this reference example, since the piezoelectric vibrating body 105 comes into contact with the deformation suppressing spacer 119 and exhibits an effect of suppressing deformation of the vibrating portion adjacent to the fixed end portion 105c, the piezoelectric vibrating body 105 is damaged. Can be prevented.

  FIG. 4 is a front view of a piezoelectric sounder constituting a piezoelectric vibration element of a second reference example which is a premise of the present invention. In the piezoelectric sounder of this reference example, a deformation suppressing spacer 219 is provided on each of the lower walls 211. The deformation suppressing spacer 219 has a U-shaped cross section, and a part of the pair of vibration portions 205b is disposed in the U-shaped hollow portion 219a of the deformation suppressing spacer 219. The deformation suppressing spacer 219 is disposed corresponding to an intermediate position of the vibration portion 205b spaced from the fixed end portion 205c and the free end portion 205d of the pair of vibration portions 205b on the support 203 side by a predetermined distance. .

  FIG. 5 is a front view of a piezoelectric sounder constituting a piezoelectric vibration element of a third reference example as a premise of the present invention. In the piezoelectric sounding device of this reference example, four support spacers 319 are integrally provided on the support 303. Specifically, the deformation suppressing spacer 319 is formed on both surfaces in the vicinity of the fixed end portion 305c of the pair of vibrating portions 305b with a gap therebetween.

  FIG. 6 is a front view of a piezoelectric sounder constituting a piezoelectric vibration element of a fourth reference example which is a premise of the present invention. Four elastic bodies 419 are provided on the support 403 of the piezoelectric sounder of this reference example. The elastic body 419 is formed on the support body 403 by insert molding, and comes into contact with both surfaces near the fixed end 405c of the pair of vibration portions 405b of the piezoelectric vibration body 405 to suppress deformation of the piezoelectric vibration body 405.

  Hereinafter, other configurations of the invention described in this specification will be additionally described.

(1)
An elongated piezoelectric vibrator formed by bonding piezoelectric elements to the front and back surfaces of the diaphragm, and
A support that supports the longitudinally central portion of the piezoelectric vibrator so as to vibrate;
A piezoelectric vibration element that is used in a state in which vibration width regulating means for regulating the vibration width of the piezoelectric vibration body is disposed on both sides of the vibration direction of the piezoelectric vibration body,
On both sides of the vibrating portion of the piezoelectric vibrating body that is not supported by the support body, vibration of the piezoelectric vibrating body during operation is not substantially affected, but a part of the piezoelectric vibrating body has the deflection width. A deformation-suppressing spacer is arranged to suppress deformation that damages the piezoelectric vibrator when the impact is so great that it comes into contact with the regulating means. A piezoelectric vibration element characterized by the above.

(2)
The piezoelectric vibration element according to (1), wherein the deformation suppression spacer is provided in the deflection width regulating means.

(3)
The deformation suppressing spacer has a U-shaped cross section,
A part of said pair of vibration parts is arrange | positioned in the said U-shaped hollow part, The piezoelectric type vibration element as described in said (1) characterized by the above-mentioned.

(4)
An elongated piezoelectric vibrator formed by bonding piezoelectric elements to the front and back surfaces of the diaphragm, and
A support that supports the longitudinally central portion of the piezoelectric vibrator so as to vibrate;
A piezoelectric vibration element that is used in a state in which vibration width regulating means for regulating the vibration width of the piezoelectric vibration body is disposed on both sides of the vibration direction of the piezoelectric vibration body,
On both sides of the vibrating portion of the piezoelectric vibrating body that is not supported by the support body, vibration of the piezoelectric vibrating body during operation is not substantially affected, but a part of the piezoelectric vibrating body has the deflection width. When a large impact is applied from the outside so as to come into contact with the regulating means, a deformation suppressing spacer is arranged to suppress the deformation that damages the piezoelectric vibrating body from occurring in the piezoelectric vibrating body,
The piezoelectric vibration element, wherein the deformation suppressing spacer is integrally provided on the support.

(5)
An elongated piezoelectric vibrator formed by bonding piezoelectric elements to the front and back surfaces of the diaphragm, and
A support that supports the longitudinally central portion of the piezoelectric vibrator so as to vibrate;
A piezoelectric vibration element that is used in a state in which vibration width regulating means for regulating the vibration width of the piezoelectric vibration body is disposed on both sides of the vibration direction of the piezoelectric vibration body,
On both sides of the vibrating portion of the piezoelectric vibrating body that is not supported by the support body, vibration of the piezoelectric vibrating body during operation is not substantially affected, but a part of the piezoelectric vibrating body has the deflection width. When a large impact is applied from the outside so as to come into contact with the regulating means, a deformation suppressing spacer is arranged to suppress the deformation that damages the piezoelectric vibrating body from occurring in the piezoelectric vibrating body,
The deformation suppressing spacer is made of an elastic body that is insert-molded on the support body.

It is a front view of the piezoelectric sounding device which comprises the piezoelectric type vibration element of embodiment of this invention. It is a top view of the piezoelectric sounder which comprises the piezoelectric type vibration element of embodiment of this invention. It is a front view of the piezoelectric sounding device which comprises the piezoelectric type vibration element of the 1st reference example used as the premise of this invention. It is a front view of the piezoelectric sounder which comprises the piezoelectric type vibration element of the 2nd reference example used as the premise of this invention. It is a front view of the piezoelectric sounding device which comprises the piezoelectric type vibration element of the 3rd reference example used as the premise of this invention. It is a front view of the piezoelectric sounding device which comprises the piezoelectric type vibration element of the 4th reference example used as the premise of this invention.

Explanation of symbols

1 Piezoelectric sounder (piezoelectric vibration element)
DESCRIPTION OF SYMBOLS 3 Support body 5 Piezoelectric vibrator 5a Longitudinal center part 5b Vibrating part 9,11 Swing width control means 13 Diaphragm 15 First piezoelectric element 17 Second piezoelectric element 19 Deformation suppression layer

Claims (9)

A piezoelectric vibrating body in which one or more piezoelectric elements are bonded to a diaphragm;
A support for supporting the piezoelectric vibrator so as to vibrate;
A piezoelectric vibration element that is used in a state in which vibration width regulating means for regulating the vibration width of the piezoelectric vibration body is disposed on both sides of the vibration direction of the piezoelectric vibration body,
The vibration portion of the piezoelectric vibrating body that is not supported by the support body does not substantially affect the vibration of the piezoelectric vibrating body during operation, but a part of the piezoelectric vibrating body is the deflection width regulating means. A deformation suppression layer is formed to suppress deformation that damages the piezoelectric vibrating body when a large impact is applied from the outside so as to come into contact with the piezoelectric vibrating body. Piezoelectric vibration element.   The piezoelectric vibration element according to claim 1, wherein the deformation suppressing layer is formed of an electrically insulating material having elasticity or flexibility. An elongated piezoelectric vibrator formed by bonding piezoelectric elements to the front and back surfaces of the diaphragm, and
A support that supports the longitudinally central portion of the piezoelectric vibrator so as to vibrate;
A piezoelectric vibration element that is used in a state in which vibration width regulating means for regulating the vibration width of the piezoelectric vibration body is disposed on both sides of the vibration direction of the piezoelectric vibration body,
A pair of vibration portions not supported by the support body of the piezoelectric vibration body is provided with a deformation suppression layer made of an elastic material or a flexible material,
The deformation suppressing layer does not substantially affect the vibration of the piezoelectric vibrating body during operation, but the impact is so large that a part of the piezoelectric vibrating body is in contact with the deflection width regulating means. A piezoelectric vibration element configured to suppress deformation of the piezoelectric vibrating body when the piezoelectric vibrating body is damaged when the piezoelectric vibrating body is applied to the piezoelectric vibrating body.   4. The piezoelectric vibration element according to claim 1, wherein the deformation suppression layer is formed on at least one of a front surface and a back surface of the vibration portion.   5. The piezoelectric mold according to claim 4, wherein the deformation suppression layer is formed at a position adjacent to the fixed end portion at an intermediate position between a fixed end portion and a free end portion located on the support side of the vibration portion. Vibration element. The distance from the fixed end portion to the deformation suppressing layer is 4 to 15% of the longitudinal dimension of the vibrating portion,
The piezoelectric vibration element according to claim 5, wherein a distance from the free end portion to the deformation suppression layer is 30 to 50% of a dimension in the longitudinal direction of the vibration portion.   The piezoelectric vibration according to claim 5, wherein the deformation suppression layer is formed at the intermediate position so as to suppress a vibration width of the vibration portion located within 5 mm from the fixed end to 0.5 mm or less. element.   The piezoelectric vibration element according to claim 1, wherein the deformation suppression layer is formed by printing a synthetic resin paste on at least one of the front surface and the back surface of the vibration portion.   The piezoelectric vibration element according to claim 1, wherein the deformation suppressing layer is formed by attaching a synthetic resin sheet on at least one of the front surface and the back surface of the vibration portion.

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