JP6923476B2 - Piezoelectric vibrating device and electronic equipment equipped with it - Google Patents

Description

The present invention relates to a piezoelectric vibration device and an electronic device including the piezoelectric vibration device.

Conventionally, a small-sized, low-current drive piezoelectric vibration device using a piezoelectric element as an exciter has been known. Such a piezoelectric vibrating device is applied to an acoustic generator such as a panel speaker (see, for example, Patent Document 1).

International Publication No. 2013-171918

In recent years, there has been a demand for further improvement in sound pressure in sound generators in line with movements such as the establishment of new standards.

The present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric vibration device having improved vibration amplitude and an electronic device having improved sound pressure.

The piezoelectric vibrating device of the present disclosure is connected to a diaphragm, a long plate-shaped piezoelectric element having one main surface attached to the diaphragm and having a plurality of surface electrodes on the other main surface, and the piezoelectric element. It has a pair of lead wires. Then, one of the lead wires of the pair of lead wires is soldered to one end of the other main surface of the piezoelectric element in the longitudinal direction, and extends outward from the one end in the longitudinal direction. .. Further, the other lead wire of the pair of lead wires is soldered to the other end portion of the other main surface of the piezoelectric element in the longitudinal direction, and the other lead wire is joined to the outside in the longitudinal direction from the other end portion. It is extending.

According to the present disclosure, the amplitude of vibration of the piezoelectric vibration device can be improved. In particular, when a piezoelectric vibrating device is used as an acoustic generator, its sound pressure can be improved.

It is a schematic plan view which shows an example of embodiment of the piezoelectric vibration apparatus. It is a schematic perspective view of the piezoelectric vibration device shown in FIG. It is the schematic cross-sectional view cut by the line III-III of the piezoelectric vibrating apparatus shown in FIG. It is the schematic cross-sectional view cut along the IV-IV line of the piezoelectric vibration apparatus shown in FIG. It is the schematic cross-sectional view which shows the other example of embodiment of a piezoelectric vibrating apparatus. It is a schematic plan view which shows another example of embodiment of a piezoelectric vibration apparatus. It is a block diagram which shows an example of embodiment of an electronic device.

Hereinafter, embodiments of the piezoelectric vibration device will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below.

The piezoelectric vibrating device 1 shown in FIGS. 1 to 4 includes a diaphragm 11 and a long plate-shaped piezoelectric element 12 having one main surface attached to the diaphragm 11 and a plurality of surface electrodes 123 on the other main surface. , A pair of lead wires 13 connected to the piezoelectric element 12 are provided.

The diaphragm 11 constituting the piezoelectric vibrating device 1 is, for example, a rectangular thin plate. As the diaphragm 11, a material having high rigidity and elasticity such as acrylic resin or glass can be used. The thickness of the diaphragm 11 is set to, for example, 0.3 mm to 1.5 mm.

One main surface (lower surface) of the piezoelectric element 12 is attached to the diaphragm 11. The piezoelectric element 12 has a long plate shape having a longitudinal direction.

The piezoelectric element 12 includes a laminate 120 in which the piezoelectric layer 121 and the internal electrode layer 122 are laminated, a surface electrode 123 provided on the upper surface of the laminate 120, and a laminate 120, as shown in FIGS. 3 and 4. A so-called laminated type having a side electrode 124 provided on the side surface of the above can be used.

The laminated body 120 has a laminated structure in which a plurality of piezoelectric layer 121 and internal electrode layer 122 are laminated in a direction perpendicular to, for example, the diaphragm 11. By applying an electric signal to the piezoelectric element 12 mounted on the diaphragm 11, the piezoelectric element 12 is flexed and vibrated to vibrate the diaphragm 11.

For example, in the case of a laminated piezoelectric element 12 used by being attached to a part of a housing of a mobile terminal or a display, the length of the laminated body 120 in the longitudinal direction is, for example, 18 mm to 28 mm. The width of the laminated body 120 is, for example, 1 mm to 6 mm. The thickness of the laminate 120 is, for example, 0.2 mm to 2.0 mm.

The piezoelectric layer 121 constituting the laminate 120 is formed of ceramics having piezoelectric properties, and examples of such ceramics include perovskite-type oxides made of _{lead zirconate titanate (PbZrO 3-} PbTIO _3). Lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ) and the like can be used. The thickness of one layer of the piezoelectric layer 31 is set to, for example, 0.01 to 0.1 mm in order to drive at a low voltage. Further, in order to obtain a large bending vibration, it is possible to have a piezoelectric d31 constant of 200 pm / V or more.

The internal electrode layer 122 constituting the laminated body 120 is formed by simultaneous firing with, for example, the ceramics forming the piezoelectric layer 121. The internal electrode layers 122 are alternately drawn out to a pair of facing side surfaces. As the forming material, for example, a conductor containing silver or a silver-palladium alloy as a main component, or a conductor containing copper, platinum, or the like can be used, but a ceramic component or a glass component may be contained therein.

At least two surface electrodes 123 are provided on the other main surface (upper surface) of the piezoelectric element 12. Further, a side electrode 124 is provided on the side surface of the laminated body 120. The side electrode 124 electrically connects the internal electrode layer 122 and the surface electrode 123.

The surface electrode 123 and the side electrode 124 can be formed, for example, by applying a silver glass-containing conductive paste and baking the paste.

The piezoelectric element 12 is not limited to the laminated type, and may be a so-called single plate type having a single-layer piezoelectric body and a surface electrode provided on the surface of the piezoelectric body.

Then, one of the pair of lead wires 13 is connected to one of the plurality of surface electrodes 123, and one of the pair of lead wires 13 is connected to the other one of the plurality of surface electrodes 123. It is electrically connected to an external circuit (external power supply).

Here, one of the lead wires 131 of the pair of lead wires 13 is soldered to one end of the other main surface of the piezoelectric element 12 in the longitudinal direction, and the lead wire 131 is joined to the outside in the longitudinal direction from the one end. It is extending. On the other hand, the other lead wire 132 of the pair of lead wires 13 is soldered to the other end of the other main surface of the piezoelectric element 12 in the longitudinal direction, and the other lead wire 132 faces outward in the longitudinal direction from the other end. It extends. That is, one lead wire 131 and the other lead wire 132 extend from different ends of the other main surface of the piezoelectric element 12 toward the opposite side.

By providing the joints of the lead wires 13 at one end and the other end of the piezoelectric element 12, the joints of the lead wires 13 that dampen the bending vibration are made smaller than those provided in one place in a large area and dispersed. Therefore, the loss of vibration energy can be suppressed.

Further, since the lead wires 13 are joined by solder instead of conductive resin, the rigidity of both ends of the piezoelectric element 12 is increased, and the bending vibration of the piezoelectric element 12 is transmitted by the diaphragm 11.

Further, since the pair of lead wires 13 extend from both ends toward the outside in the longitudinal direction on opposite sides, they are arranged so as not to interfere with the bending vibration of the piezoelectric element 12. Therefore, the amplitude of vibration of the piezoelectric vibration device 1 can be improved. In particular, when the piezoelectric vibrating device 1 is used as an acoustic generator, its sound pressure can be improved.

Both ends of the other main surface (upper surface) of the piezoelectric element 12 mean a region at the most end when the piezoelectric element 12 is divided into five equal parts or more along the longitudinal direction.

Here, as shown in FIGS. 3 and 4, specifically, the piezoelectric element 12 is drawn out to the piezoelectric layer 121 and the end face of one end in the longitudinal direction, and from the end face to the other end of the one end. It has a first internal electrode layer 1221 extending toward one end and a second internal electrode layer 1222 drawn out to the end face of the other end in the longitudinal direction and extending from the end face of the other end toward one end, and is piezoelectric. A laminated body 120 in which the first internal electrode layer 1221 and the second internal electrode layer 1222 are alternately laminated via the body layer 121 is included.

At this time, the first solder joint portion 141 at one end of the other main surface of the piezoelectric element 12 in the longitudinal direction overlaps the position that does not overlap with the second internal electrode layer 1222 when viewed in a plane from the stacking direction. The second solder joint 142 at the other end of the other main surface of the piezoelectric element 12 in the longitudinal direction overlaps with the first internal electrode layer 1221 when viewed in a plane from the stacking direction. It may straddle the position where it does not become and the position where it overlaps.

According to this configuration, the first solder joint portion 141 and the second solder joint portion 142 are pressed so as to press the end portion of the active region where the first internal electrode layer 1221 and the second internal electrode layer 1222 overlap in the stacking direction. The vibration energy is easily transmitted due to the partial mass load effect, and the bending vibration of the piezoelectric element 12 is transmitted by the diaphragm 11. Therefore, when the piezoelectric vibrating device 1 is used as an acoustic generator, its sound pressure can be further improved.

Further, by providing a part of the first solder joint portion 141 and the second solder joint portion 142 at a position (inert region) that does not overlap with both the first internal electrode layer 1221 and the second internal electrode layer 1222. The joint strength between the solder and the surface electrode 13 and the solder and the lead wire 13 can be ensured, and the peeling of the lead wire 13 or the first solder joint portion 141 and the second solder joint portion 142 can be suppressed.

Further, as shown in FIG. 5, when viewed in a plan view from the stacking direction, the length along the longitudinal direction of the first solder joint portion 141 and the length along the longitudinal direction of the second solder joint portion 142 are different. May be good. For example, when the length of the first solder joint 141 along the longitudinal direction is 0.5 to 2 mm, the length of the first solder joint 141 along the longitudinal direction and the length of the second solder joint 142 along the longitudinal direction The difference from the soldering length can be, for example, 0.5 to 1.5 mm. In FIG. 5, the length of the first solder joint portion 141 along the longitudinal direction is made longer than the length of the second solder joint portion 142 along the longitudinal direction.

According to this configuration, the vibration restraint region due to the solder can be made different between the one end side and the other end side of the piezoelectric element 12, and the symmetry of vibration can be lowered. As a result, spurious can be generated in the resonance region, the division of the peak dip region in the frequency-sound pressure characteristic can be induced, and the peak dip difference can be reduced. Therefore, when the piezoelectric vibrating device 1 is used as an acoustic generator, the sound pressure can be improved, and in addition, the sound quality can be improved.

Here, as shown in FIG. 6, the length of the first solder joint portion 141 along the longitudinal direction is longer than the length of the second solder joint portion 142 along the longitudinal direction, and the piezoelectric shape is formed in the longitudinal direction. The distance from the end face of one end of the element 12 to the outer circumference of the vibrating plate 11 may be longer than the distance from the end face of the other end of the piezoelectric element 12 to the outer circumference of the vibrating plate 11. For example, when the distance from the end face of one end of the piezoelectric element 12 in the longitudinal direction to the outer circumference of the diaphragm 11 is 0.5 to 2 mm, from the end face of the other end of the piezoelectric element 12 along the longitudinal direction. The distance to the outer circumference of the diaphragm 11 can be shortened by, for example, 0.5 to 5 mm.

According to this configuration, the symmetry of the composite vibrating body including the piezoelectric element 12 and the diaphragm 11 can be reduced. As a result, spurious can be generated in the resonance region of the composite vibrator, the division of the peak dip region in the frequency-sound pressure characteristic can be induced, and the peak dip difference can be further reduced. Further, the long first solder joint 141 is closer to the center of the length from one end to the other end of the diaphragm 11 along the longitudinal direction of the piezoelectric element 12 than the short second solder joint 142. By being located closer to the center, the vibration energy is transmitted toward the center of the diaphragm 11 and contributes to the improvement of sound pressure. Therefore, when the piezoelectric vibrating device 1 is used as an acoustic generator, the sound pressure can be improved, and in addition, the sound quality can be improved.

The diaphragm 11 may be a part of a housing (case) such as a mobile terminal or a display, for example. Further, the peripheral edge of the diaphragm 11 may be fixed by a frame-shaped support made of, for example, a metal such as stainless steel or a resin.

Next, a method of manufacturing the piezoelectric vibration device 1 will be described.
First, a ceramic green sheet to be the piezoelectric layer 121 is produced. Specifically, a ceramic slurry is prepared by mixing a calcined powder of piezoelectric ceramics, a binder made of an organic polymer such as acrylic or butyral, and a plasticizer. Then, a ceramic green sheet is produced using this ceramic slurry by using a tape molding method such as a doctor blade method or a calendar roll method. The piezoelectric ceramic may be any one having piezoelectric properties, and for example, _{a perovskite-type oxide made of lead titanate (PbZrO 3-} PbTIO ₃ ) or the like can be used. Further, as the plasticizer, dibutyl phthalate (DBP), dioctyl phthalate (DOP) and the like can be used.

Next, a conductive paste to be the internal electrode layer 122 is produced. Specifically, a conductive paste is prepared by adding and mixing a binder and a plasticizer to the powder of a silver-palladium alloy. This conductive paste is applied onto the ceramic green sheet in the pattern of the internal electrode layer 122 by a screen printing method. Further, a plurality of ceramic green sheets on which this conductive paste is printed are laminated, debindered at a predetermined temperature, fired at a temperature of 900 to 1200 ° C., and then fired at a predetermined temperature using a surface grinding machine or the like. By performing a grinding process so as to have a shape, a laminated body 120 including the piezoelectric layer 121 and the internal electrode layer 122 which are alternately laminated is produced.

The laminate 120 is not limited to the one produced by the above-mentioned production method, and any production method as long as the laminate 120 formed by laminating a plurality of piezoelectric layer 121 and internal electrode layer 122 can be produced. May be made by.

After that, a silver glass-containing conductive paste prepared by adding a binder, a plasticizer, and a solvent to a mixture of conductive particles containing silver as a main component and glass was applied to the main surface of the laminate in the pattern of the surface electrode 123. After printing by a screen printing method or the like, printing on the side surface of the laminate 120 with the pattern of the side electrode 124 and drying, the surface electrode 123 and the side electrode 124 are formed by baking at a temperature of 650 to 750 ° C. Then, the piezoelectric element 12 is manufactured.

Next, a thin plate-shaped diaphragm 11 is prepared. Then, the piezoelectric element 12 is joined onto the diaphragm 11 using an adhesive or an adhesive tape.

Then, the lead wire 13 can be bonded to the surface electrode 123 by bringing the lead wire 13 into contact with the surface electrode 123 of the piezoelectric element 12 and soldering the lead wire 13 to the surface electrode 123 using a soldering iron. At this time, in order to adjust the lengths of the first solder joint portion 141 and the second solder joint portion 142 along the longitudinal direction, the amount of solder may be different.

The piezoelectric vibration device 1 can be manufactured by the above method.

Next, an embodiment of the electronic device will be described.

As shown in FIG. 7, the electronic device 10 of the present disclosure includes the above-mentioned piezoelectric vibrating device, an electronic circuit 5 connected to the piezoelectric vibrating device, and a housing 6 accommodating the piezoelectric vibrating device and the electronic circuit 5. , The piezoelectric vibrating device is characterized in that it generates sound. Note that FIG. 7 shows only the components necessary for explanation, and the description of general components is omitted. Although the piezoelectric vibrating device is not shown in FIG. 7, a part of the housing 6 or the display becomes a diaphragm 11, and the combination of this and the piezoelectric element 12 becomes a piezoelectric vibrating device (acoustic generator).

The electronic device 10 includes an electronic circuit 5. The electronic circuit 5 includes, for example, a controller 51, a transmission / reception unit 52, a key input unit 53, and a microphone input unit 54. The electronic circuit 5 is connected to the piezoelectric element 12 and has a function of outputting an audio signal to the piezoelectric element 12.

The controller 51 is a control unit of the electronic device 10. The transmission / reception unit 52 transmits / receives data via the antenna 62 based on the control of the controller 51. The key input unit 53 is an input device of the electronic device 10 and accepts a key input operation by an operator. The microphone input unit 54 is also an input device of the electronic device 10, and receives a voice input operation or the like by an operator. The display unit is a display output device of the electronic device 10, and outputs display information based on the control of the controller.

The piezoelectric element 12 operates as an acoustic output device in the electronic device 10. The piezoelectric element 12 is connected to the controller 51 of the electronic circuit 5, vibrates in response to the application of the voltage controlled by the controller 51, and emits sound.

Further, the electronic device 10 includes a display unit 61 and an antenna 62. The display unit 61 has a display having a function of displaying image information. For example, known displays such as liquid crystal displays, plasma displays, and organic EL displays can be preferably used. The display may have an input device such as a touch panel. Further, the cover of the display may be a diaphragm 11, which may have an input device such as a touch panel. Further, the entire display or a part of the display may function as the diaphragm 11.

The electronic device 10 includes a housing 6 that houses or comprises each of these devices. In the figure, each device including the controller 51 is housed or a component in one housing 6. It represents a state, but does not limit this form.

Although the description has been made here assuming that the electronic device 10 is a mobile terminal, the type of the electronic device 10 is not limited, and the electronic device 10 may be applied to various consumer devices having a function of emitting sound. For example, flat-screen TVs and car audio devices may of course be used in various products such as vacuum cleaners, washing machines, refrigerators, microwave ovens, and the like, which have a function of emitting sound.

Since such an electronic device 10 includes a piezoelectric vibration device having an improved vibration amplitude, it is possible to realize an electronic device having high sound pressure and high sound quality.

1 Piezoelectric vibrating device 11 Vibrating plate 12 Piezoelectric element 121 Piezoelectric layer 122 Internal electrode layer 1221 First internal electrode layer 1222 Second internal electrode layer 123 Surface electrode 124 Side electrode 13 Lead wire 141 First solder joint 142 Second Solder joint 10 Electronic equipment 5 Electronic circuit 51 Controller 52 Transmission / reception unit 53 Key input unit 54 Microphone input unit 6 Housing 61 Display unit 62 Antenna

Claims (5)

It is provided with a vibrating plate, a long plate-shaped piezoelectric element having one main surface attached to the vibrating plate and having a plurality of surface electrodes on the other main surface, and a pair of lead wires connected to the piezoelectric element. One of the lead wires of the pair of lead wires is soldered to one end of the other main surface of the piezoelectric element in the longitudinal direction, and extends outward from the one end in the longitudinal direction. , The other lead wire of the pair of lead wires is joined with solder to the other end portion of the other main surface of the piezoelectric element in the longitudinal direction, and extends outward from the other end portion in the longitudinal direction. A piezoelectric vibrating device characterized by being The piezoelectric element has a piezoelectric layer, a first internal electrode layer that is drawn out to the end surface of one end portion in the longitudinal direction and extends from the end surface of the one end portion toward the other end portion, and the other end portion in the longitudinal direction. It has a second internal electrode layer which is drawn out to the end face of the above and extends from the end face of the other end toward the one end, and the first internal electrode layer and the second inside are provided through the piezoelectric layer. The first solder joint portion at one end in the longitudinal direction of the other main surface of the piezoelectric element includes a laminate in which electrode layers are alternately laminated, and is second when viewed in a plane from the lamination direction. The second solder joint at the other end of the other main surface of the piezoelectric element in the longitudinal direction is seen through the plane from the stacking direction. The piezoelectric vibration device according to claim 1, wherein the piezoelectric vibrating device straddles a position that does not overlap with the first internal electrode layer and a position that overlaps with the first internal electrode layer. When viewed in a plan view from the stacking direction, the length of the first solder joint at one end in the longitudinal direction of the other main surface of the piezoelectric element along the longitudinal direction and the other main surface of the piezoelectric element. The piezoelectric vibration device according to claim 1 or 2, wherein the length of the second solder joint at the other end in the longitudinal direction is different from that along the longitudinal direction. The length of the first solder joint along the longitudinal direction is longer than the length of the second solder joint along the longitudinal direction, and the one end portion of the piezoelectric element in the direction along the longitudinal direction. The piezoelectric vibrating device according to claim 3, wherein the distance from the end face to the outer periphery of the vibrating plate is longer than the distance from the end face of the other end of the piezoelectric element to the outer periphery of the vibrating plate. The piezoelectric vibrating device according to any one of claims 1 to 4, an electronic circuit connected to the piezoelectric vibrating device, and a housing for accommodating the piezoelectric vibrating device and the electronic circuit are provided. An electronic device characterized in that a piezoelectric vibrating device generates sound.

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