WO2006070595A1

WO2006070595A1 - Piezoelectric ceramic actuator and portable device

Info

Publication number: WO2006070595A1
Application number: PCT/JP2005/022894
Authority: WO
Inventors: Yasuhiro Sasaki; Yasuharu Oonishi; Ukyou Mori; Yukio Murata
Original assignee: Nec Corporation
Priority date: 2004-12-28
Filing date: 2005-12-13
Publication date: 2006-07-06
Also published as: JPWO2006070595A1; TWI321895B; TW200631298A; JP4830858B2

Abstract

A reinforcing plate is placed on the entire surface of a piezoelectric ceramic element which oscillates upon application of a voltage, and then the piezoelectric ceramic element and the reinforcing plate are locally bonded at one or more positions. A stator is bonded to a part of the reinforcing plate corresponding to the bonded portion, and oscillation of the piezoelectric ceramic element is transmitted to the outside. Consequently, a structural defect such as cracking or chipping does not take place in the piezoelectric ceramic element even if it is subjected to falling impact, and a significant oscillation of the piezoelectric ceramic element can be ensured.

Description

Specification

Piezoelectric ceramic actuator and portable device

Technical field

TECHNICAL FIELD [0001] The present invention relates to a piezoelectric ceramic actuator suitable as a thin and highly reliable mechanical vibration source used in a portable device and a portable device equipped with the piezoelectric ceramic actuator.

Background art

Recently, small portable electronic devices such as mobile phones, notebook personal computers, and PDAs (Personal Data Assistant personal digital assistants) have come to be actively used. These devices are expanding their applications with the development of network systems and software, increasing the convenience for users. Along with this, the number of functional parts to be mounted is increasing. Examples include speakers, microphones, receivers, vibrators, cameras, liquid crystal displays, batteries, card memories, LSIs, and infrared communication modules.

[0003] In order to improve portability and convenience, the device is required to be small and thin. On the other hand, an increase in the number of functional components mounted impedes the downsizing of the device. In addition, the importance of mounting layout and space design that takes into account the prevention of component destruction due to contact between components and other components or the case when the device is dropped is increasing. The development of technology for manufacturing and mounting parts at low cost is indispensable for the further spread of portable devices.

[0004] Various movable parts are used in portable devices. Examples include acoustic elements, vibrators, camera zoom mechanisms, and liquid cooling pumps. Batteries are used as energy supply sources for portable devices, and they can be driven at a low voltage of about 3 to 5 V and are inexpensive. As a mechanical drive source, a DC motor called an electromagnetic type and magnetic force / mechanical conversion The mechanism is used. Since electromagnetic coils and permanent magnets are used, there are high technical barriers to maintain drive performance and reduce size. Electromagnetic noise generated by the electromagnetic drive source can also cause equipment malfunction. Therefore, a drive source using a piezoelectric ceramic that does not use electromagnetic action, has high electro-mechanical energy conversion efficiency, and is advantageous for thinning and miniaturization has attracted attention. [0005] This is because the piezoelectric ceramic element is displaced when a DC voltage is applied in spite of its small size, and the force to move the object is strong. In addition, when an AC voltage having a desired frequency is applied, the element vibrates at that frequency and can vibrate an object.

[0006] As described above, a piezoelectric ceramic element that can be thinned as a mechanical drive source has been proposed and put into practical use. For example, Non-Patent Document 1 and Non-Patent Document 2 describe bending elements using the piezoelectric transverse effect and details of their operation.

[0007] In addition, in mobile devices, a battery of 3 to 5 V output is used as an energy supply source. It is generally known that a piezoelectric ceramic element has a higher operating voltage than an electromagnetic type. As a means for solving this problem, there has been proposed a laminated piezoelectric ceramic vibrator that can be driven at a low voltage by alternately laminating piezoelectric ceramic thin plates and electrodes and increasing the electric field strength applied to the ceramic plate. The structure of this multilayer piezoelectric ceramic vibrator is shown in Non-Patent Document 3, for example.

[0008] A conventional piezoelectric ceramic actuator will be described with reference to FIGS. 21, 22 and 24. FIG. FIG. 21 shows a conventional piezoelectric ceramic element 110 (piezoelectric vibrator). In this conventional piezoelectric ceramic element 110, a pair of piezoelectric ceramic plates 111 and 112 subjected to polarization treatment are joined with a constant elastic body 113 disposed therebetween, and the piezoelectric ceramic plates 111 and 112 are joined to the piezoelectric ceramic plates 111 and 112. Are formed with electrodes. If a predetermined connection is made to the electrical terminals arranged above and below the constant elastic body 113, the piezoelectric ceramic plate 111 arranged on the upper side when the voltage is applied to the piezoelectric ceramic plates 111, 112 The piezoelectric ceramic plate 112 arranged below extends in the length direction and, as a result, bends in the thickness direction of the piezoelectric ceramic plates 111 and 112 (thickness direction of the piezoelectric ceramic element 110) as shown in FIG. exercise. When the direction of voltage application is changed, it bends in the opposite direction. Therefore, when a sine wave AC voltage is applied, the piezoelectric ceramic element 110 causes bending vibration in the thickness direction.

In order to transmit the vibration of the piezoelectric ceramic element 110 to the elastic body 115, as shown in FIG. 23, a stator 114 is provided between the piezoelectric ceramic element 110 and the elastic body 115, and the stator 114 The piezoelectric ceramic element 110 and the elastic body 115 may be mechanically joined via

[0010] Non-patent document 1: "Ultrasonic electronics vibration theory", pp. 104, edited by Yoshiro Tomikawa, Asakura Shop, 1998

Non-Patent Document 2: "Electromechanical vibrator as an electric circuit element and its application", pp. 192, pp. 212, Kenzo Nagai, Tadashi Masano, Corona, 1974

^^ Patent Contribution 3: Mechanical quality factor of multilayer piezoelectric ceramic trans du cers "(Jpn. J. Appl. Phys., Vol.40, Part 1, No.5B, pp.3549-3551, May2001)

Patent Document 1: JP 2004-254417

Patent Document 2: JP 2000-333480 A

Disclosure of the invention

Problems to be solved by the invention

[0011] However, when a piezoelectric ceramic element using the piezoelectric lateral effect that performs bending displacement operation is used for a portable device, there are the following practical problems.

[0012] Modern mobile devices must take measures to prevent destruction when the devices fall due to human failure during transportation, considering transportability. Piezoelectric ceramic elements, which are small, have a wide range of applicability, such as vibrators and acoustic elements, as small vibration sources for portable devices, but because of the brittleness of ceramics, they are prone to breakage due to impact force when dropped. was there. In the configuration of Fig. 23, the impact stress generated when the mobile device is dropped concentrates in the vicinity of the stator 114, structural defects such as cracking and chipping of the ceramic occur, and the vibration amount of the piezoelectric ceramic element is greatly reduced. There was a problem that it could not function as a vibration source.

In order to solve this problem, as shown in FIG. 24, it is considered that the reinforcing plate 116 is bonded to the entire surface of the piezoelectric ceramic element 110, with a strong impact force such as a metal plate having high rigidity. Be

[0014] However, since the piezoelectric ceramic element 110 is mechanically constrained by the joining of the reinforcing plate 116 and its expansion and contraction is suppressed by the joining of the reinforcing plate 116, the amount of vibration becomes small, and it is practically used. There is a problem that it cannot be provided.

[0015] Similarly, Patent Documents 1 and 2 disclose a piezoelectric actuator in which a reinforcing plate is laminated on a piezoelectric element. However, there are conflicting requirements for preventing damage to the piezoelectric element and ensuring a large amount of vibration. Can not be satisfied. [0016] The present invention has been made in view of the problems that may occur, and even when subjected to a drop impact force, structural defects such as cracking and chipping of the piezoelectric ceramic element do not occur, and the compressive force is piezoelectric. An object of the present invention is to provide a piezoelectric ceramic actuator capable of securing a large vibration amount as a vibration amount of the ceramic element and a portable device incorporating the piezoelectric ceramic actuator.

Means for solving the problem

The piezoelectric ceramic actuator according to the present invention includes a piezoelectric ceramic element that vibrates when a voltage is applied thereto, a reinforcing material that is superposed on the entire surface of the piezoelectric ceramic element, and the piezoelectric ceramic that is fixed to the reinforcing material. A stator for transmitting the vibration of the element to the outside, and the piezoelectric ceramic element and the reinforcing member are joined at one or more local sites.

In the piezoelectric ceramic actuator, the piezoelectric ceramic element has, for example, a pair of piezoelectric ceramic plates and a constant elastic body sandwiched between the piezoelectric ceramic plates. In this case, the reinforcing material is stacked on the entire surface of one piezoelectric ceramic plate, for example, and has the same or larger shape as the piezoelectric ceramic plate.

[0019] Further, it is preferable that the stator is disposed at a joint portion between the piezoelectric ceramic element and the reinforcing material. Furthermore, it is preferable that the piezoelectric ceramic element and the reinforcing material are bonded by an adhesive. Furthermore, by providing an organic resin base material coated with a bonding material between the piezoelectric ceramic element and the reinforcing material, the piezoelectric ceramic element and the reinforcing material can be bonded.

[0020] Another piezoelectric ceramic actuator according to the present invention includes a pair of piezoelectric ceramic elements that vibrate when a voltage is applied, and a reinforcing material disposed between the pair of piezoelectric ceramic elements and stacked on the entire surface thereof. And a stator that is fixed to one of the piezoelectric ceramic elements and transmits a signal of the piezoelectric ceramic element to the outside, and each of the piezoelectric ceramic elements and the reinforcing material is one or a plurality of local parts. It is characterized by being joined at various parts.

In this piezoelectric ceramic actuator, each of the piezoelectric ceramic elements has, for example, a pair of piezoelectric ceramic plates and a constant elastic body sandwiched between the piezoelectric ceramic plates. In this case, for example, the reinforcing material is stacked on the entire surface of one of the piezoelectric ceramic plates of both piezoelectric ceramic elements, and has the same or larger shape as the piezoelectric ceramic plate. Have.

[0022] Further, it is preferable that the stator is disposed at a joint portion between the piezoelectric ceramic element to which the stator is fixed and the reinforcing material. Furthermore, it is preferable that the piezoelectric ceramic element and the reinforcing material are joined by an adhesive. Furthermore, the piezoelectric ceramic element and the reinforcing material can be joined by providing an organic resin base material coated with a joining material between the piezoelectric ceramic element and the reinforcing material.

[0023] A portable device according to the present invention is characterized in that the piezoelectric ceramic actuator described above is used as a vibration source. In this case, the above-described piezoelectric ceramic actuator can be used as a vibration source, and a part of the housing can be vibrated to generate sound. The invention's effect

[0024] According to the present invention, since the piezoelectric ceramic element is joined to the reinforcing material at one or more local sites, when the piezoelectric ceramic element is incorporated into a portable device as a vibration source, the portable device is Even if impact stress is applied when dropped, the piezoelectric ceramic element can be destroyed. In this case, since the piezoelectric ceramic element and the reinforcing material are joined locally, a sufficiently large vibration amount can be obtained even if the reinforcing material is provided, and a mechanical vibration source having a large vibration amount can be obtained. Obtainable. In addition, since the reinforcing material is stacked on the entire surface of the piezoelectric ceramic element, it is possible to reliably suppress the impact force on the piezoelectric ceramic element, to prevent breakage due to the impact stress, and to obtain high reliability. Can do. In particular, if the reinforcing material is the same size as the piezoelectric ceramic element, in addition to preventing damage by covering one surface of the piezoelectric ceramic element with a reinforcing plate, useless protrusions protruding from the piezoelectric ceramic element, etc. It is possible to reduce the size of the device.

Brief Description of Drawings

FIG. 1 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a third embodiment of the present invention. FIG. 4 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a fourth embodiment of the present invention.

FIG. 5 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a fifth embodiment of the present invention.

FIG. 6 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a sixth embodiment of the present invention.

FIG. 7 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a seventh embodiment of the present invention.

FIG. 8] A perspective view showing a modification of the piezoelectric ceramic element of the present invention.

FIG. 9 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to an eighth embodiment of the present invention.

FIG. 10] A perspective view showing a method of assembling a piezoelectric ceramic actuator according to a ninth embodiment of the present invention.

[FIG. 11] (a) and (b) are views showing a state in which the actuator of the embodiment of the present invention is incorporated in a portable device.

12] A perspective view showing a piezoelectric ceramic element of Example 1 of the present invention.

[FIG. 13] (a) to (d) are views showing a reinforcing plate and a reinforcing plate-joining substrate of Example 1 of the present invention.

14] FIG. 14 is a perspective view showing a method for assembling the piezoelectric ceramic actuator according to the first embodiment of the present invention.

[FIG. 15] (a) and (b) are diagrams showing a method of attaching the actuator of the first embodiment to the casing.

16] A perspective view showing a piezoelectric ceramic actuator according to a second embodiment of the present invention.

[FIG. 17] (a) and (b) are diagrams showing a method of attaching the actuator of the second embodiment to the casing.

18] A perspective view showing a piezoelectric ceramic actuator according to a third embodiment of the present invention.

19] Similarly, it is a perspective view showing a piezoelectric ceramic actuator of Example 3 of the present invention.

[FIG. 20] (a) and (b) show the piezoelectric ceramic actuator of Example 4 of the present invention in a portable device. It is a figure which shows the state accommodated in.

FIG. 21 is a perspective view showing a conventional piezoelectric ceramic element.

FIG. 22 is a diagram showing the operation.

FIG. 23 is a perspective view showing a conventional piezoelectric ceramic actuator.

FIG. 24 is a perspective view showing a conventional piezoelectric ceramic actuator.

Explanation of symbols

1, 11, 21, 31, 41a, 41b, 61, 81: Piezoelectric ceramic element

2, 4, 82, 83: Piezoelectric ceramic plate

3, 84: Constant elastic body

5, 15, 25, 35a, 35b, 45, 62, 86: Reinforcing plate

6, 49, 64, 74, 88: Stator

7a, 7b, 7c: junction sites

17a, 17b, 17c, 27a, 27b, 27c, 37a, 37b, 37c, 38a, 38b, 38c, 47a, 47b, 4

7c, 48a, 48b, 48c, 63a, 63b, 63c, 87b, 87c, 87d: Base material for reinforcing plate bonding

51: Upper insulating layer

52, 54: Piezoelectric active layer

53: Intermediate insulating layer

55: Lower insulation layer

70: Pseudo enclosure

101: Mobile phone upper case

102: Antenna

103: Mobile phone lower case

104: Battery pack

105: Folding hinge

106, 107: Circuit board

108: LCD display

109: Piezoelectric ceramic element

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a method for assembling a piezoelectric ceramic actuator according to a first embodiment of the present invention. The piezoelectric ceramic element 1 is configured such that a constant elastic body 3 is sandwiched between a pair of piezoelectric ceramic plates 2 and 4, and a voltage is applied to electrodes (not shown) formed on the piezoelectric ceramic plates 2 and 4. As a result, the piezoelectric ceramic plates 2 and 4 are deformed so that either the piezoelectric ceramic plate 2 side or the piezoelectric ceramic plate 4 side is inward depending on the direction of the voltage. Therefore, by applying an AC voltage, the piezoelectric ceramic plates 2 and 4 are alternately deformed so as to be inward (bending motion), and the piezoelectric ceramic element 1 vibrates.

[0028] For the reinforcing plate 5, various materials such as a metal plate or a resin plate can be used. The reinforcing plate 5 is overlaid on the entire surface of the piezoelectric ceramic plate 4 of the piezoelectric ceramic element 1 and has the same force as or larger than the piezoelectric ceramic plate 4. The reinforcing plate 5 and the piezoelectric ceramic plate 4 are formed by applying an adhesive such as an organic adhesive to the three local portions 7a, 7b, and 7c of the reinforcing plate 5 and bringing them into close contact with each other. Joined at 7a to 7c. That is, in the present embodiment, the reinforcing plate 5 is not fixed to the entire surface of the piezoelectric ceramic plate 4, but the reinforcing plate 5 and the piezoelectric ceramic plate 4 are fixed at one or a plurality of local and mutually independent portions. . The size and number of the joining sites are arbitrary.

[0029] The stator 6 is bonded to the surface (back surface) of the reinforcing plate 5 where the piezoelectric ceramic plate 4 is not bonded. The joint portion of the stator 6 is a position that matches with any one of the joint portions 7 a to 7 c on the back surface of the reinforcing plate 5. That is, the attachment position of the stator 6 on the reinforcing plate 5 is a position corresponding to a portion (the portion 7b in the illustrated example) where the reinforcing plate 5 is joined to the piezoelectric ceramic plate 4. The stator 6 is used to transmit the vibration of the piezoelectric ceramic element 1 to the outside. For example, the piezoelectric ceramic element 1 is arranged so that the stator 6 comes into contact with the casing of the portable device.

Next, the operation of the piezoelectric ceramic actuator configured as described above will be described. In the present embodiment, since the reinforcing plate 5 overlaps the entire surface of the piezoelectric ceramic element 1, even if the portable device is dropped, the reinforcing plate 5 protects the piezoelectric ceramic element 1 and the impact load is applied to the piezoelectric ceramic element 1. Application to the element 1 can be prevented, and destruction of the piezoelectric ceramic element 1 can be prevented. The reinforcing plate 5 is made of the piezoelectric ceramic element 1 (piezoelectric ceramic). It is bonded to the cover plate 4) by bonding at three local parts 7a to 7c, and the reinforcing plate is not bonded and integrated on the entire surface of the piezoelectric ceramic element. The portion of the ceramic element 1 where the reinforcing plate 5 is not joined can be freely deformed. Therefore, the piezoelectric ceramic element 1 can vibrate greatly and becomes a vibration source with a large amount of vibration.

[0031] In this case, by using an adhesive for joining the piezoelectric ceramic element 1 and the reinforcing plate 5, it is possible to make the joint part flexible, so that the piezoelectric ceramic element 1 vibrates during vibration of the piezoelectric ceramic element 1. Element 1 can be easily deformed. In addition, there is a non-bonded portion between the joint portions provided locally, and there is a gap between the piezoelectric ceramic element 1 and the reinforcing plate 5 at this non-bonded portion. Since the friction or restraining force between the reinforcing plate 5 and the reinforcing plate 5 can be reduced, the piezoelectric ceramic element 1 can be easily deformed when the piezoelectric ceramic element 1 vibrates. For these reasons, the present embodiment can obtain a large bending vibration as a piezoelectric ceramic actuator.

[0032] Since there is a joint portion 7b between the piezoelectric ceramic element 1 and the reinforcing plate 5 at the position of the piezoelectric ceramic element 1 to which the stator 6 is fixed, the vibration of the piezoelectric ceramic element 1 is passed through the stator 6 It can be propagated with high efficiency to the external elastic body. On the other hand, if the stator 6 is provided at a portion where the piezoelectric ceramic element 1 and the reinforcing plate 5 are not joined, the mechanical coupling path is blocked by the reinforcing plate 5 and a propagation loss of vibration energy occurs. The impact vibration generated when the portable device is dropped propagates to the piezoelectric ceramic element 1 through the stator 6, and the piezoelectric ceramic element 1 is destroyed by the collision between the reinforcing plate 5 and the piezoelectric ceramic element 1 at the unjoined portion. Is likely to occur. If the stator 6 is provided in a portion where the piezoelectric ceramic element 1 and the reinforcing plate 5 are joined, the above-described problems at the time of impact can be prevented.

[0033] In FIG. 1, the piezoelectric ceramic element 1 and the reinforcing plate 5 are provided with three joining parts (parts 7a to 7c), but the joining part is one place or a plurality of two or more places. Moyo. This is because the impact destruction of the piezoelectric ceramic element 1 when the electronic device is dropped as described above occurs in the vicinity of the joint portion of the stator 6, and the joint portion of the stator 6 is reinforced by the reinforcing plate 5. If this is the case, the same effect can be obtained regardless of the number of joints between the piezoelectric ceramic element 1 and the reinforcing plate 5. Next, a second embodiment of the present invention will be described with reference to FIG. However, the stator is not shown in FIG. In the present embodiment, three substrates 17a, 17b, 17c made of organic resin such as polyethylene terephthalate, acrylic, polyimide, or silicon rubber are spaced between the piezoelectric ceramic element 11 and the reinforcing plate 17. Is placed. The base materials 17a to 17c are thin plate-like, and adhesives or adhesives are applied to the front and back surfaces thereof, and the base materials 17a to 17c are respectively connected to the piezoelectric ceramic element 11 by this adhesive or adhesive. It is joined to the reinforcing plate 17. Thereby, the piezoelectric ceramic element 11 and the reinforcing plate 15 are joined via the three base materials 17a to 17c.

In the present embodiment, since the organic resin base materials 17a to 17c have flexibility, the base materials 17a to 17c are easily deformed according to the bending vibration of the piezoelectric ceramic element 11. As a result, the mechanical restraint force between the piezoelectric ceramic element 11 and the reinforcing plate 15 is greatly relaxed, and the piezoelectric ceramic actuator can perform a large bending vibration. Further, by joining the piezoelectric ceramic element 11 and the reinforcing plate 15 with the organic resin base materials 17a to 17c, the piezoelectric ceramic actuator can be easily manufactured industrially.

FIG. 3 is a perspective view showing a third embodiment of the present invention. However, the stator is not shown in FIG. In this embodiment, five resin base materials 27a, 27b, 27c, 27d, and 27e for reinforcing plate bonding are arranged between the piezoelectric ceramic element 21 and the reinforcing plate 25 with an interval between them. The base materials 27a to 27e, the piezoelectric ceramic element 21 and the reinforcing plate 25 are joined together by an adhesive or an adhesive.

[0037] In the present embodiment, since the base materials 27a to 27e having a larger number of widths are provided than in the second embodiment, the reinforcing plate 25 follows the flexural vibration of the piezoelectric ceramic element 21 more flexibly. Therefore, vibration suppression of the piezoelectric ceramic element 21 due to the joining of the reinforcing plate 25 hardly occurs. In addition, even if some of the base materials 27a to 27e are peeled off due to secular changes in the joint portions of the base materials 27a to 27e, the joining force is maintained by the joint portions of the other base materials 27a to 27e. Therefore, the present embodiment has a practical form as in the second embodiment.

FIG. 4 is a perspective view showing a fourth embodiment of the present invention. However, the stator is not shown in FIG. In the present embodiment, the reinforcing plates 35a and 35b are provided on the front and back surfaces of the piezoelectric ceramic element 31, respectively, and the reinforcing plate bonding resin base materials 37a to 37c and 38a, respectively. Joined through ~ 38c.

[0039] In the present invention, since the piezoelectric ceramic element and the reinforcing plate are joined at a local portion, vibration restraint by the reinforcing plate of the piezoelectric ceramic element is small, so that the reinforcing plate 35a is as in the present embodiment. 35b is provided on both the front and back surfaces of the piezoelectric ceramic element 31 and has little effect on the vibration of the piezoelectric ceramic element 31.

[0040] In a mobile device, vibration generated at the time of a drop impact propagates from an elastic body such as a housing to a piezoelectric ceramic element through a stator. However, since the space in the housing of the mobile device is narrow, Parts such as electronic circuit boards may be placed on the elastic body and the other side. If the gap between these parts and the piezoelectric ceramic element is small, these parts and the piezoelectric ceramic element are directly connected. Colliding and causing destruction of the piezoelectric ceramic element. In such a case, this problem can be solved by providing the reinforcing plates 35a and 35b on the upper and lower surfaces of the piezoelectric ceramic element 31 as in this embodiment.

5 and 6 are perspective views showing a fifth embodiment of the present invention. In the present embodiment, one reinforcing plate 45 is joined between the two piezoelectric ceramic elements 41a and 41b. The reinforcing plate 45 has three reinforcing plate bonding substrates 47a, 47b, 47c and 48a, 48b, 48 on its front and back surfaces, and is applied to both the front and back surfaces of this substrate 47a, etc. Thus, the piezoelectric ceramic elements 41a and 41b are joined to the reinforcing plate 45 via the base material 47a and the like. Then, as shown in FIG. 6, a stator 49 is fixed at the center of the back surface of the piezoelectric ceramic element 41b, that is, at a position aligned with the central base materials 47b and 48b.

In the present embodiment, since the two piezoelectric ceramic elements 41a and 41b are provided, the excitation force of the piezoelectric ceramic element is doubled. Therefore, the amount of vibration of the elastic body that propagates vibration through the stator 49 can be doubled. At this time, in consideration of the electrical connection of each piezoelectric ceramic element, it is necessary to bend and vibrate in the same direction, that is, to vibrate in the same phase. If the bending vibration directions of the piezoelectric ceramic elements 41a and 41b are different from each other, the vibrations of the piezoelectric ceramic elements 41a and 41b in the stator 49 can cancel each other and propagate the vibration to an elastic body such as an electronic device casing. Nare ,. In addition, an excessive shearing force is generated at the joint between the piezoelectric ceramic elements 41a and 4 lb and the reinforcing plate 45 during vibration, and defects such as a peel-off of the joint occur, resulting in a decrease in reliability. Note that the joining position of the stator 49 is not limited to the center of the piezoelectric ceramic element, and as shown in FIG. 7, the stator 49 may be joined to a position aligned with the base materials 47a and 48a at the end portions. Good. In this case, the same effect as in FIG. 6 is obtained.

In the present invention, the members constituting the piezoelectric ceramic element that undergoes flexural vibration are not limited to specific ones. For example, in FIG. 1, the piezoelectric ceramic element is composed of piezoelectric ceramic plates 2, 4 and a constant elastic body 3. However, as shown in FIG. 8, in order to prevent aging of the ceramic due to humidity, piezoelectric active layers 52 and 54 are disposed between the upper insulating protective layer 51 and the lower insulating protective layer 55, and further, the piezoelectric A piezoelectric ceramic element having a structure in which an intermediate insulating layer 53 is disposed between the active layers 52 and 54 can also be used. In this case, the piezoelectric active layers 52 and 54 have been subjected to polarization treatment, and are expanded and contracted by applying a voltage to become a driving unit for element bending vibration. The intermediate insulating layer 53 electrically isolates the piezoelectric active layers 52 and 54 disposed above and below the intermediate insulating layer 53. This piezoelectric ceramic element is fired as a whole to form an integral structure. This piezoelectric ceramic element also achieves the same effect by joining the reinforcing plate as described above.

In addition, as shown in FIG. 9, in order to join the piezoelectric ceramic element 61 and the reinforcing plate 64, bonding is performed using adhesives or bonding base materials 63a, 63b, 63c at a plurality of sites. In this case, the size of the bonding part or the size of the bonding base materials 63a, 63b, 63c (especially the width in the bending direction) may be different from each other. In particular, when the stator 64 is joined to the center of the piezoelectric ceramic element 61, the bending vibration amount of the piezoelectric ceramic element 61 is small at the joining position of the stator 64. The width of has little effect on flexural vibration.

Further, as shown in FIG. 10, in order to join the piezoelectric ceramic element 71 and the reinforcing plate 72, a reinforcing plate joining base material 73 may be provided only at one place in the vicinity of the stator 74. Good. Even in this case, since the impact stress when the device is dropped concentrates in the vicinity of the stator 74, the function of preventing the destruction of the piezoelectric ceramic element 71 by the reinforcing plate 72 has the same reinforcing effect as the joining at a plurality of locations.

FIG. 11 (a) is a perspective view showing the appearance of the mobile device casing 70, and FIG. 11 (b) is a cross-sectional view taken along the line AA in FIG. 11 (a). In this portable device casing 70, a piezoelectric ceramic element 71 and a reinforcing plate 7 2 and the reinforcing plate bonding base material 73a, 73b, and 73c are housed in the piezoelectric ceramic actuator. The stator 74 of the piezoelectric ceramic actuator contacts the inner surface of the housing 70. It is provided to do. Note that the housing 70 is provided to hold electronic components such as an electronic circuit board and a liquid crystal display that constitute a portable device, such as a transparent plastic provided for protecting the liquid crystal display. Thus, an internal structure mechanically joined to a box-like structure appearing on the exterior of the device is also included.

As described above, when the piezoelectric ceramic actuator of the present invention is provided as a vibration source, when an AC electric field is applied to the piezoelectric actuator, the piezoelectric actuator causes flexural vibration and passes through the stator 74. Vibration propagates to the housing 70. Mechanical vibration is excited throughout the entire casing 70, and the air in contact with the casing 70 is oscillated to be radiated and used as a sounding body.

Example 1

[0049] Next, the results of tests conducted to demonstrate the effects of the present invention will be described. In order to explain the effect of the piezoelectric ceramic actuator of the present invention, a piezoelectric ceramic element 81 shown in FIG. 12 was produced. As a material for the piezoelectric ceramic plates 82 and 83, a lead zirconate titanate perovskite composite was used. For the production of piezoelectric ceramic plates 82 and 83, the green sheet method used for the production of ceramic capacitors and the like was applied.

[0050] The piezoelectric ceramic plates 82 and 83 had a length of 30 mm, a width of 5 mm, and a thickness of 0.2 mm, and were fired in the atmosphere at 1100 ° C for 2 hours. Ag electrodes were formed on both main surfaces of the piezoelectric ceramic plate and then polarized. A phosphor bronze plate having a length of 30 mm, a width of 5 mm, and a thickness of 0.12 mm was prepared as the constant elastic body 84 and bonded to the piezoelectric ceramic plates 82 and 83 with an epoxy adhesive. This constant elastic body 84 is used as an electrode and does not affect vibration, so it is not always necessary if the electrical connection is devised. Further, three electrical lead terminals 85a, 85b, and 85c were brought into contact with a constant elastic body 84 made of piezoelectric ceramic plates 82 and 83 and a phosphor bronze plate.

[0051] Next, as shown in FIG. 13 (a), as an example of the prior art, an adhesive coated on the entire surface 87a of the reinforcing plate 86 was prepared. Further, as an example of the present invention, as shown in FIG. 13 (b), an epoxy adhesive was applied to three independent parts 6b of width 6mm on the reinforcing plate 86, 13 As shown in (c), a reinforcing plate bonding base material 87c having a width of 6 mm and a thickness of 0.1 mm was bonded to three portions on the reinforcing plate 86 by applying an epoxy adhesive on both sides thereof. As shown in Fig. 13 (d), a reinforcing plate joining base material 87d with a width of 4mm and a thickness of 0.1mm was coated with epoxy adhesive on both sides. Prepared one joined to the part. At this time, one joining base material is arranged at the joining position of the stator. In this example, the thickness of the bonding base material used was set to 0.1 mm. However, the present invention limits the thickness of the base material, and when mounted on a portable device, the thickness of the piezoelectric ceramic actuator is limited. What is necessary is just to select suitably according to the thickness dimension which has a desired vibration characteristic.

Next, as shown in FIG. 14, a stator 88 having a length of 5 mm, a width of 5 mm, and a thickness of 1 mm is manufactured using ABS resin, and is placed in the center of the reinforcing plate 86 to obtain a piezoelectric ceramic element. 81, a joining base material 87c, etc., a reinforcing plate 86, and a stator 88 were joined. The role of the stator 88 is to propagate the vibration of the piezoelectric ceramic element to the elastic body. In this embodiment, ABS resin is used as the stator material, but the material of the stator is not limited.

Next, as shown in FIGS. 15 (a) and 15 (b), a simulated housing 90 having a length of 90 mm, a width of 45 mm, and a thickness of 20 mm, which simulates the housing of an electronic device, is Made of acrylic material. After that, the four types of reinforcing plates shown in Fig. 13 (a) to (d), the piezoelectric ceramic actuator with the piezoelectric ceramic element and the stator, and the center position of the bottom surface of the stator The inner surface of the 90 was joined at a position 20 mm from one end in the longitudinal direction and 22 mm from the left end in the width direction. In Fig. 15 (a), the broken line indicates the arrangement position of the piezoelectric ceramic actuator.

[0054] Then, by applying an AC sine wave voltage of lVrms and 500Hz to each piezoelectric ceramic element, the ceramic element is vibrated, and the effective vibration velocity amount at the center of the surface of the pseudo casing 90 transmitted is measured by the laser. Measurements were made using a vibration system. The vibration amount of the pseudo case when using a conventional piezoelectric ceramic element (Fig. 13 (a)) was taken as the reference 1, and the ratio of the measured values was taken as the normalized vibration speed. In addition, a drop test was performed in which the pseudo casing 90 was dropped on floor concrete with a height of 200 cm, and an impact force was applied to the outer surface of the piezoelectric ceramic element on the joining side in the pseudo casing 90. After that, an AC sine wave voltage of lVrms and 500 Hz is applied to the piezoelectric ceramic element to vibrate each piezoelectric ceramic element, and the effective vibration velocity amount at the center of the acrylic plate to be transmitted is determined by the laser vibration system. Measured using, and the amount of vibration when using a conventional element before dropping as reference 1 The effect of the present invention was evaluated using the measured value ratio as the normalized vibration speed. The results are shown in Table 1 below.

[0055] [Table 1]

[0056] As shown in Table 1, the piezoelectric ceramic actuator according to the embodiment of the present invention has a vibration amount of 2.5 times or more as compared with the conventional example of FIG. 13 (a). Has improved. In addition, the piezoelectric ceramic actuator of this embodiment does not change in characteristics before and after the drop test. Also in the appearance inspection after the drop test, chipping, cracking, and peeling of the joint portion of the piezoelectric ceramic element were not observed. Therefore, according to this example, it was proved that the present invention can prevent the impact destruction and can greatly improve the vibration amount.

Example 2

[0057] In this example, a piezoelectric ceramic element similar to the piezoelectric ceramic element described in Example 1 was used, except that a stainless steel plate was used as the reinforcing plate and the stator was fixed to the end of the reinforcing plate. . That is, a stainless steel plate having a length of 30 mm, a width of 5 mm, and a thickness of 0.2 mm was prepared as the reinforcing plate 86 in FIG. As a conventional example, an epoxy adhesive is applied to the entire surface of the reinforcing plate (Fig. 13 (a)), and an epoxy adhesive is applied to both sides of a 6mm wide and 0.1mm thick substrate to reinforce the base material. Two types of piezoceramic elements were fabricated, one bonded to three locations on the top surface of the plate (Fig. 13 (c)).

[0058] Next, a stator having a length of 5 mm, a width of 5 mm, and a thickness of 1 mm is manufactured using an ABS resin material, arranged at the end of the piezoelectric ceramic element, and each component is joined as shown in FIG. did.

Next, as shown in FIG. 17, a pseudo housing 90 of an electronic device having a length of 90 mm, a width of 45 mm, and a thickness of 20 mm was made of an acrylic material having a thickness of 2 mm. After that, two types of piezoelectric ceramic elements were joined to each other at a position of one end force in the longitudinal direction (bending direction) on the inner surface of the pseudo casing 90, 20 mm, and 10 mm from the left end in the width direction via the stator.

[0060] In order to quantify the effect of the present invention, each piezoelectric ceramic element has an alternating current of lVrms and 500 Hz. A sinusoidal voltage was applied to vibrate the ceramic element, and the effective vibration velocity at the center of the transmitted acrylic plate was measured using a laser vibration system. The vibration amount when using the conventional piezoelectric element shown in Fig. 13 (a) was taken as 1, and the measured value ratio was taken as the standard vibration speed. In addition, the pseudo casing 90 was dropped onto the floor concrete from a height of 200 cm, and an impact force was applied to the outer surface of the casing where the piezoelectric ceramic elements on the inner surface of the pseudo casing were joined. After that, an AC sine wave voltage of lVrms and 500Hz is applied to the piezoelectric ceramic element to vibrate the ceramic element, and the effective vibration velocity amount at the center of the acrylic plate transmitted is again measured using the laser vibration system. The piezoelectric ceramic element of the present invention was evaluated based on the measured vibration ratio when the piezoelectric element shown in FIG. 13 (a) was used as the reference 1 and the ratio of the measured values as the normalized vibration speed. The results are shown in Table 2 below.

[Table 2]

As a result, the amount of vibration is improved by a factor of 3.3 in the piezoelectric ceramics according to the present invention as compared with the conventional example shown in FIG. 13 (a). In addition, the actuator of the present invention has no change in characteristics before and after the drop test. An appearance inspection was conducted after the drop test, but no chipping, cracking, or peeling of the piezoelectric ceramic was observed. According to the present embodiment, it was proved that the present invention can prevent impact destruction and greatly improve the vibration amount.

Next, Embodiment 3 of the present invention will be described with reference to FIG. 18 and FIG. In this example, the piezoelectric ceramic element of Example 1 shown in FIG. 12 was used. Next, a stainless steel plate having a length of 30 mm, a width of 5 mm, and a thickness of 0.2 mm was prepared as the reinforcing plate 86. In the case of FIG. 18 (conventional example), an epoxy resin was applied to the entire surface 87a of both sides of the reinforcing plate 86, and a pair of piezoelectric ceramic elements 81 were bonded to the front and back surfaces of the reinforcing plate 86. The stator 88 was joined to the lower surface of the lower piezoelectric ceramic element 81. In the case of FIG. 19 (Example of the present invention), three bonding substrates 87c and 87c were bonded to the front and back surfaces of the reinforcing plate 86, respectively. The width of this substrate 87c is 6 mm, thickness is 0.1 mm. An epoxy adhesive was applied to both surfaces of the base material 87c and joined to the reinforcing plate 86. In addition, the piezoelectric ceramic elements with the number shown in Fig. 14 were also prepared.

[0064] The stator 88 was manufactured using an ABS resin material so as to have a length of 5 mm, a width of 5 mm, and a thickness of 1 mm. This stator 88 was placed in the center of the lower surface of the piezoelectric ceramic element 81, and the components were joined.

Next, as shown in FIG. 15, the above three types of piezoelectrics are placed inside a pseudo housing 90 (made of acrylic material having a length of 90 mm, a width of 45 mm, a thickness of 2 Omm, and a thickness of 2 mm) of an electronic device. The ceramic element was fixed via a stator 86. The joining position of the stator 86 on the inner surface of the pseudo housing 90 is a position of one end force of the pseudo housing 90, 20 mm, and 22 mm from the left end in the width direction.

[0066] Then, an AC sine wave voltage of lVrms and 500Hz is applied to each piezoelectric ceramic element to vibrate the ceramic element, and the effective vibration velocity amount at the center of the acrylic plate to be transmitted is determined by laser vibration. Measurement was performed using a system. At this time, in the actuator provided with the two piezoelectric ceramic elements of FIGS. 18 and 19, a voltage was applied to each piezoelectric ceramic element so that the vibrations were in the same direction (in phase). The vibration amount when using the piezoelectric ceramic actuator shown in Fig. 14 was set as 1, and the amount of change was set as the standard vibration speed. In addition, a 200cm high force was dropped onto the floor concrete, and the impact force was applied to the joint surface of the pseudo housing where the piezoelectric ceramic elements were joined. After that, an AC sine wave voltage of lVrms and 500Hz is applied to the piezoelectric ceramic element to vibrate the ceramic element, and the effective vibration velocity at the center of the transmitted acrylic plate is measured using a laser vibration system. The piezoelectric element of the present invention was evaluated using the vibration amount when the piezoelectric ceramic element of FIG. 14 before dropping was used as the reference 1 and the ratio of the measured values as the normalized vibration speed. The results are shown in Table 3 below.

[0067] [Table 3]

As shown in Table 3, when two piezoceramic elements are used as shown in Fig. 19, 2.2 times as much vibration as when one piezoceramic element as shown in Fig. 14 is used. Amount can get. This is because the excitation force doubled because two piezoelectric ceramic elements were used. However, even when two piezoelectric ceramic elements are used, when a reinforcing plate is bonded to the entire surface as shown in FIG. 18, the vibration amount is reduced to 0.1 compared to the case of FIG. . This indicates that the vibration force can be sufficiently exerted according to the number of piezoelectric ceramic elements to be used by the configuration of the present invention. There is no change in characteristics before and after the drop test. An appearance inspection was conducted after the drop test, but no chipping, cracking, or peeling of the joint was observed. Therefore, according to the present example, it was proved that the present invention can prevent impact destruction and can greatly improve the vibration amount.

Example 4

[0069] In Examples 1 to 3, the effect of the present invention is tested using a pseudo case imitating an electronic device. On the other hand, in this example, a mobile phone device was fabricated as a portable electronic device, and the effect of the present invention was tested.

FIG. 20 shows the structure of a mobile phone as an example of the electronic apparatus of the present invention. The upper housing 101 of the mobile phone is 90 mm long, 45 mm wide, 15 mm thick, and the lower housing 103 is 90 mm long, 45 mm wide, 15 mm thick. Made of acrylic material with a wall thickness of 2 mm. The upper casing 101 and the lower casing 103 are foldably connected by a hinge mechanism 105. An antenna 102 is attached to the upper housing 101. In the upper casing 101, a liquid crystal display 108, a circuit board 106, and a piezoelectric ceramic element 109 are accommodated. On the other hand, a circuit board 107 and a battery pack 104 are accommodated in the lower housing 103.

[0071] For this electronic device casing, the piezoelectric ceramic element provided with the reinforcing plate of Figs. 13 (a) to (d) described in Example 1 was used, and the length was 5mm and the width was 5mm. A lmm-thick stator was placed in the center of the piezoelectric ceramic element, and the parts were joined as shown in FIG.

[0072] Next, the center position of the stator is aligned with the position 20 mm from the lower end surface in the longitudinal direction of the casing, and the longitudinal force of the piezoelectric ceramic element is parallel to the width direction of the casing. Bonded to the housing with an adhesive. In addition, the connection location of the piezoelectric ceramic element of the present invention is not limited to a specific position of the electronic device casing, but may be provided on, for example, a liquid crystal display or a display protective material. [0073] Next, in order to quantify the effect of the present invention, an AC sine wave voltage of lVrms and 500Hz is applied to each piezoelectric ceramic element to vibrate the ceramic element and transmit the center of the acrylic plate to be transmitted. The amount of effective vibration velocity was measured using a laser vibration system. The vibration amount when using the conventional piezoelectric ceramic element in Fig. 13 (a) was set to 1, and the vibration speed ratio of the elastic body by each piezoelectric ceramic element was taken as the standard vibration speed.

[0074] In addition, the casing was dropped onto the floor concrete from a height of 200 cm, and an impact force was applied to the joint surface where the piezoelectric ceramic element of the casing was joined. Then, an AC sine wave voltage of lVrms and 500Hz is applied to the piezoelectric ceramic element to vibrate the ceramic element, and the amount of effective vibration velocity at the center of the transmitted tantalum plate is measured using a laser vibration system. The piezoelectric ceramic element of the present invention was evaluated with the vibration amount when using the conventional piezoelectric ceramic element of FIG. 13 (a) before dropping as the reference 1 and the measured value ratio as the normalized vibration speed. Furthermore, after the drop test, a microphone was placed at a distance of 10 cm from the outside of the housing where the piezoelectric element was placed, and an AC sine wave voltage of lVrms and 500 Hz was applied to each piezoelectric ceramic element in the same manner as the vibration velocity measurement described above. The sound pressure was measured. Then, the sound pressure when using the conventional piezoelectric ceramic element of FIG. 13 (a) is set to 1, and the ratio of the measured values is expressed as the normalized sound pressure. The results are shown in Table 4 below.

[0075] [Table 4]

[0076] As shown in Table 4, as compared with the conventional example of Fig. 13 (a), the piezoelectric ceramic element of the present invention has a vibration amount improved 2.3 times or more. Also, there is no change in characteristics before and after the drop test. In the appearance inspection after the drop test, no chipping, cracking, peeling of the joint, etc. were observed. According to this example, it was proved that the present invention can prevent impact destruction and can greatly improve the vibration amount. In addition, the same effect as the amount of vibration is recognized in the sound pressure, and the effect of the present invention is effective not only as a vibration source but also as a sound generating element, and the use method of the present invention is greatly expanded. Therefore, its industrial value is great. Industrial applicability

The present invention is useful as a mechanical vibration source having a thin shape and high reliability for portable equipment.

Claims

The scope of the claims

[1] A piezoelectric ceramic element that vibrates when a voltage is applied, a reinforcing material that is superimposed on the entire surface of the piezoelectric ceramic element, and a stator that is fixed to the reinforcing material and transmits the vibration of the piezoelectric ceramic element to the outside. The piezoelectric ceramic element and the reinforcing material are joined at one or more local sites.

2. The piezoelectric ceramic actuator according to claim 1, wherein the piezoelectric ceramic element has a pair of piezoelectric ceramic plates and a constant elastic body sandwiched between the piezoelectric ceramic plates.

3. The piezoelectric ceramic actuator according to claim 2, wherein the reinforcing material is stacked on the entire surface of one piezoelectric ceramic plate, and has the same or larger shape as the piezoelectric ceramic plate.

4. The piezoelectric ceramic actuator according to any one of claims 1 to 3, wherein the stator is disposed at a joint portion between the piezoelectric ceramic element and the reinforcing material. .

5. The piezoelectric ceramic actuator according to any one of claims 1 to 4, wherein the piezoelectric ceramic element and the reinforcing material are joined together by an adhesive.

[6] The piezoelectric ceramic element and the reinforcing material are bonded together by providing an organic resin base material coated with a bonding material between the piezoelectric ceramic element and the reinforcing material. The piezoelectric ceramic actuator according to any one of 1 to 5, wherein

[7] A pair of piezoelectric ceramic elements that vibrate when a voltage is applied, a reinforcing material disposed between the pair of piezoelectric ceramic elements and overlaid on the entire surface, and the piezoelectric ceramic element fixed to one of the piezoelectric ceramic elements A stator that transmits the signal of the element to the outside, and each of the piezoelectric ceramic elements and the reinforcing member are joined at one or more local sites. Piezoelectric ceramic actuator.

8. The piezoelectric ceramic actuator according to claim 7, wherein each piezoelectric ceramic element has a pair of piezoelectric ceramic plates and a constant elastic body sandwiched between the piezoelectric ceramic plates. .

[9] The reinforcing material is superimposed on the entire surface of one piezoelectric ceramic plate of both piezoelectric ceramic elements. 9. The piezoelectric ceramic actuator according to claim 8, wherein the piezoelectric ceramic plate has a shape equal to or larger than that of the piezoelectric ceramic plate.

10. The piezoelectric ceramic ceramic actuator according to any one of claims 7 to 9, wherein the stator is disposed at a joint portion between the piezoelectric ceramic element to which the stator is fixed and the reinforcing material. .

11. The piezoelectric ceramic actuator according to any one of claims 7 to 10, wherein the piezoelectric ceramic element and the reinforcing material are joined by an adhesive.

[12] The piezoelectric ceramic element and the reinforcing material are bonded by providing an organic resin base material coated with a bonding material between the piezoelectric ceramic element and the reinforcing material. The piezoelectric ceramic actuator according to any one of 7 to 11,

[13] A portable device comprising the piezoelectric ceramic actuator according to any one of claims 1 to 12 as a vibration source.

[14] A portable device characterized in that the piezoelectric ceramic actuator according to any one of claims 1 to 12 is used as a vibration source to generate a sound by vibrating a part of the housing.