A piezoelectric stack and a piezoelectric buzzer

Abstract

The application discloses a piezoelectric stack and a piezoelectric buzzer, relates to the technical field of piezoelectric stacks, and discloses a piezoelectric stack comprising a solid piezoelectric sheet and at least one annular piezoelectric sheet, wherein the solid piezoelectric sheet and the annular piezoelectric sheet are coaxially connected in layers, and the piezoelectric stack is provided with an inner circuit end and an outer circuit end which are spatially isolated from each other; the inner circuit end comprises a second electrode arranged on the lower side of the solid piezoelectric sheet and a third electrode arranged on the upper side of the annular piezoelectric sheet and extending to the inner ring face of the annular piezoelectric sheet, and the second electrode and the third electrode are in communication with each other; and the outer circuit end comprises a first electrode arranged on the upper side of the solid piezoelectric sheet and extending to the outer ring face of the solid piezoelectric sheet and a fourth electrode arranged on the lower side of the annular piezoelectric sheet and extending to the outer ring face of the annular piezoelectric sheet, and the first electrode and the fourth electrode are in communication with each other. The piezoelectric buzzer comprises the piezoelectric stack and a metal sheet, wherein the metal sheet is fixedly connected to the end of the piezoelectric stack, and when in operation, the piezoelectric stack generates vibration and transmits the vibration to the metal sheet, so as to drive the metal sheet to vibrate and produce sound.

Description

Technical Field

[0001] This application relates to the field of piezoelectric stack technology, and in particular discloses a piezoelectric stack and a piezoelectric buzzer. Background Technology

[0002] A piezoelectric buzzer is an electroacoustic device that converts electrical signals into mechanical vibrations to produce sound. It is widely used in consumer electronics, automotive electronics, medical equipment, and industrial control. Its core driving element is a piezoelectric vibrator, which is usually made of a piezoelectric ceramic sheet bonded to a metal substrate. When an alternating electric field is applied to the piezoelectric ceramic sheet, it will deform due to the inverse piezoelectric effect, thereby driving the metal substrate to vibrate and produce sound.

[0003] To achieve higher output sound pressure or better acoustic performance, a single piezoelectric ceramic sheet often lacks sufficient driving force. Therefore, the industry often uses multiple piezoelectric ceramic sheets stacked together and connected in parallel to form a piezoelectric stack, aiming to obtain a larger displacement or output force under the same voltage. Currently, traditional solid stacks can usually only produce single, overall axial extension and contraction vibrations, which are difficult to achieve richer acoustic performance when used in piezoelectric buzzers.

[0004] Meanwhile, traditional piezoelectric stacks typically employ a planar electrode structure, where electrodes are only arranged on the upper and lower surfaces of the piezoelectric sheet. When achieving multi-layer stacking and electrical interconnection, this structure often requires the introduction of complex internal wires or external circuits for connection. This not only increases the difficulty of the process and manufacturing cost but may also lead to reduced overall reliability of the stack, internal stress concentration, and problems such as response lag or signal crosstalk under high-frequency dynamic conditions. In addition, the planar electrode design limits the flexibility of electrode lead-out, which limits the stack in terms of structural compactness, diversified connection methods, and configuration of different polarization directions. Therefore, improvements are needed. Utility Model Content

[0005] The purpose of this application is to provide a piezoelectric stack.

[0006] Another objective of this application is to provide a piezoelectric buzzer.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: a piezoelectric stack, comprising a solid piezoelectric sheet and at least one annular piezoelectric sheet, wherein the solid piezoelectric sheet and the annular piezoelectric sheet are coaxially stacked and connected, and the piezoelectric stack is configured with an inner circuit terminal and an outer circuit terminal that are spatially isolated from each other; the inner circuit terminal includes a second electrode disposed on the lower side of the solid piezoelectric sheet and a third electrode disposed on the upper side of the annular piezoelectric sheet and extending to its inner annular surface, wherein the second electrode and the third electrode are interconnected; the outer circuit terminal includes a first electrode disposed on the upper side of the solid piezoelectric sheet and extending to its outer annular surface and a fourth electrode disposed on the lower side of the annular piezoelectric sheet and extending to its outer annular surface, wherein the first electrode and the fourth electrode are interconnected.

[0008] Preferably, the projection of the third electrode coverage area in the axial direction falls within the coverage area of ​​the second electrode.

[0009] Further preferably, the solid piezoelectric sheet includes a first substrate, the second electrode has the same shape as the first substrate, and its outer edge dimension is smaller than that of the first substrate, thereby forming a first circumferential insulating ring between the outer edge of the second electrode and the outer edge of the first substrate.

[0010] More preferably, the annular piezoelectric sheet includes a second substrate, the second substrate having a through hole in the middle, and the third electrode being an annular electrode with the same outer edge size as the second electrode, thereby forming a second circumferential insulating ring between the outer edge of the third electrode and the outer edge of the second substrate.

[0011] Further preferably, the fourth electrode is a ring electrode, the inner edge of which has the same shape as the through hole, and the inner edge of which is larger than the through hole, thereby forming an inner circumferential insulating ring between the inner edge of the fourth electrode and the through hole.

[0012] More preferably, the outer edge shape and size of the second substrate are the same as those of the first substrate.

[0013] As a preferred embodiment, the annular piezoelectric sheet is adapted to be stacked sequentially in opposite directions along the axial direction.

[0014] A piezoelectric buzzer includes the aforementioned piezoelectric stack and a metal sheet. The metal sheet is fixedly connected to the end of the piezoelectric stack. During operation, the piezoelectric stack vibrates and transmits the vibration to the metal sheet, thereby driving the metal sheet to vibrate and produce sound.

[0015] Preferably, the diameter of the metal sheet is larger than the outer diameter of the piezoelectric stack.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application connects the second electrode of the solid piezoelectric sheet and the third electrode of the ring piezoelectric sheet to form an internal circuit terminal, and connects the first electrode of the solid piezoelectric sheet and the fourth electrode of the ring piezoelectric sheet to form an external circuit terminal. This fundamentally eliminates the traditional stacking connection method that relies on complex internal wires or external jumpers. This electrode layout enables the internal and external circuits to achieve natural spatial isolation within the stack, greatly simplifies the process, reduces manufacturing costs, and completely eliminates the signal crosstalk and high-frequency response lag problems caused by complex leads.

[0017] (2) The electrode layout structure in this application is compact and does not require additional space for the lead wire, which is conducive to the miniaturization of the stack. At the same time, the simplified internal connection reduces potential mechanical failure points, effectively improves the internal stress distribution, and significantly enhances the structural integrity and reliability of the stack under long-term dynamic operation.

[0018] (3) The mutually isolated internal circuit terminals and external circuit terminals constitute two independent electrical input channels, which allows for differentiated driving of the solid region and the ring region, such as applying in-phase or out-of-phase voltages. This design breaks through the limitation that traditional planar electrode stacks can only drive as a whole, and can actively excite richer vibration modes, such as the combination of overall stretching vibration and bending vibration, providing more design freedom for optimizing acoustic performance. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the three-dimensional structure of the piezoelectric stack of this utility model.

[0020] Figure 2 This is an exploded view of the three-dimensional structure of the piezoelectric stack of this utility model. The left column of the figure is a top view and the right column is a bottom view.

[0021] Figure 3 This is a three-dimensional structural diagram of the piezoelectric buzzer of this utility model.

[0022] Figure 4 This is an exploded view of the three-dimensional structure of the piezoelectric buzzer of this utility model. The left column of the figure is a top view and the right column is a bottom view.

[0023] In the figure: 1. Solid piezoelectric sheet; 11. First substrate; 12. First electrode; 13. Second electrode; 2. Ring piezoelectric sheet; 21. Second substrate; 22. Third electrode; 23. Fourth electrode; 24. Through hole; 3. Metal sheet. Detailed Implementation

[0024] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0025] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0026] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0027] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0028] A preferred embodiment of this application, such as Figures 1 to 2 As shown, a piezoelectric stack includes a solid piezoelectric sheet 1 and at least one annular piezoelectric sheet 2. The solid piezoelectric sheet 1 and the annular piezoelectric sheet 2 are coaxially stacked and connected. The piezoelectric stack is configured with an inner circuit terminal and an outer circuit terminal that are spatially isolated from each other. The inner circuit terminal includes a second electrode 13 disposed on the lower side of the solid piezoelectric sheet 1 and a third electrode 22 disposed on the upper side of the annular piezoelectric sheet 2 and extending to its inner annular surface. The second electrode 13 and the third electrode 22 are interconnected. The outer circuit terminal includes a first electrode 12 disposed on the upper side of the solid piezoelectric sheet 1 and extending to its outer annular surface and a fourth electrode 23 disposed on the lower side of the annular piezoelectric sheet 2 and extending to its outer annular surface. The first electrode 12 and the fourth electrode 23 are interconnected.

[0029] This application establishes an internal circuit by interconnecting the second electrode 13 of the solid piezoelectric sheet 1 with the third electrode 22 of the annular piezoelectric sheet 2, and an external circuit by interconnecting the first electrode 12 of the solid piezoelectric sheet 1 with the fourth electrode 23 of the annular piezoelectric sheet 2. This fundamentally eliminates the traditional stacked connection method that relies on complex internal wires or external jumpers. This electrode layout achieves natural spatial isolation between the internal and external circuits within the stack, greatly simplifying the process, reducing manufacturing costs, and completely eliminating signal crosstalk and high-frequency response lag caused by complex leads. Furthermore, the electrode layout is compact, eliminating the need for additional lead wires. The space allows for miniaturization of the stack, and the streamlined internal connections reduce potential mechanical failure points, effectively improving internal stress distribution and significantly enhancing the structural integrity and reliability of the stack under long-term dynamic operation. The mutually isolated internal and external circuit terminals form two independent electrical input channels, which allows for differentiated driving of the solid and annular regions, such as applying in-phase or out-of-phase voltages. This design breaks through the limitation of traditional planar electrode stacks, which can only be driven as a whole, and can actively excite richer vibration modes, such as the combination of overall stretching vibration and bending vibration, providing more design freedom for optimizing acoustic performance.

[0030] In this embodiment, the axial projection of the area covered by the third electrode 22 falls within the area covered by the second electrode 13. During the piezoelectric stacking, the upper second electrode 13 must achieve a reliable electrical connection with the lower third electrode 22. This projection relationship ensures that the electrical connection areas of the two can be fitted within any alignment tolerance range, avoiding poor contact or open circuit caused by misalignment, and ensuring the reliability of the internal circuit. At the same time, this setting provides an easy-to-operate alignment reference for piezoelectric stacking assembly, reduces the alignment accuracy requirements in the production process, thereby improving production efficiency and yield.

[0031] Furthermore, the solid piezoelectric sheet 1 includes a first substrate 11, which can be a symmetrical regular shape such as a circle or a square. The shape of the second electrode 13 is the same as that of the first substrate 11, and its outer edge dimension is smaller than that of the first substrate 11, thereby forming a first peripheral insulating ring between the outer edge of the second electrode 13 and the outer edge of the first substrate 11. This first peripheral insulating ring establishes a physical isolation zone between the inner circuit end and the outer circuit end on the outer periphery of the solid piezoelectric sheet 1, which can effectively avoid short circuits between the inner circuit end and the outer circuit end, and significantly improve the long-term working reliability of the product.

[0032] Furthermore, the annular piezoelectric sheet 2 includes a second substrate 21, the outer edge shape of which is the same as that of the first substrate 11. A through hole 24 is provided in the middle of the second substrate 21. The third electrode 22 is an annular electrode, and its outer edge size is the same as that of the second electrode 13, thereby forming a second outer circumferential insulating ring between the outer edge of the third electrode 22 and the outer edge of the second substrate 21. This makes the second outer circumferential insulating ring on the upper side of the annular piezoelectric sheet 2 perfectly aligned with the first outer circumferential insulating ring on the lower side of the solid piezoelectric sheet 1 in the axial direction. Through the synergistic effect with the first outer circumferential insulating ring, a continuous insulating channel that runs through the stacked axis is constructed, achieving comprehensive and consistent radial isolation.

[0033] Furthermore, the fourth electrode 23 is a ring electrode, the inner edge of which has the same shape as the through hole 24, and its inner edge size is larger than that of the through hole 24, thereby forming an inner circumferential insulating ring between the inner edge of the fourth electrode 23 and the through hole 24. This design establishes physical isolation between the outer circuit end and the inner circuit end around the through hole 24 of the ring piezoelectric sheet 2, and works in conjunction with the aforementioned outer circumferential insulating ring to achieve double radial insulation protection for the inner circuit end and the outer circuit end, further ensuring the safe operation of the equipment.

[0034] In this embodiment, the outer edge shape and size of the second substrate 21 are the same as those of the first substrate 11, ensuring that all piezoelectric sheets have the same external contour, so that the stacked sheets are subjected to uniform stress during lamination, the structure is stable, and stress concentration caused by different shapes is avoided. At the same time, in the production process, this design can also simplify the production process, reduce mold costs and material management complexity, and facilitate alignment during stacking.

[0035] The annular piezoelectric sheet 2 is suitable for being stacked in opposite directions along the axial direction. In another embodiment, multiple annular piezoelectric sheets 2 can be stacked in opposite directions once, and a larger output force and response speed can be obtained by parallel driving. At the same time, this stacking scheme completely eliminates the complex wire connection process between layers, and the internal structure of the stack is extremely simple. Circuit conduction is achieved by relying on the conduction of corresponding electrodes.

[0036] Another preferred embodiment of this application, such as Figures 3 to 4 As shown, a piezoelectric buzzer includes the aforementioned piezoelectric stack and a metal sheet 3. The metal sheet 3 is fixedly connected to the end of the piezoelectric stack. During operation, the piezoelectric stack vibrates and transmits the vibration to the metal sheet 3, thereby driving the metal sheet 3 to vibrate and produce sound. The diameter of the metal sheet 3 is larger than the outer diameter of the piezoelectric stack.

[0037] The loudness of a sound is directly related to the area of ​​air pushed by the vibrating body. A larger diameter of the metal plate 3 means a larger effective vibration area, which can push more volume of air, thus significantly improving the sound production efficiency of the buzzer and the radiation intensity of mid-to-low frequency sound, making the sound louder and travel farther. When the diameter of the metal plate 3 is larger than the outer diameter of the piezoelectric stack, its vibration is no longer a simple up-and-down piston movement. Driven by the piezoelectric stack, a phase difference will be generated between the central region of the metal plate 3 and the suspended edge region, thereby exciting a highly efficient bending vibration mode. The amplitude of bending vibration is usually much larger than that of pure piston vibration, which can convert more mechanical energy into sound energy and can excite richer harmonics, making the sound less monotonous. In specific designs, it can broaden the effective frequency response and improve the sound quality.

[0038] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A piezoelectric stack, characterized in that, The device includes a solid piezoelectric sheet and at least one annular piezoelectric sheet, the solid piezoelectric sheet and the annular piezoelectric sheet being coaxially stacked and connected. The piezoelectric stack is configured with an inner circuit terminal and an outer circuit terminal that are spatially isolated from each other. The inner circuit terminal includes a second electrode disposed on the lower side of the solid piezoelectric sheet and a third electrode disposed on the upper side of the annular piezoelectric sheet and extending to its inner annular surface, the second electrode and the third electrode being interconnected. The outer circuit terminal includes a first electrode disposed on the upper side of the solid piezoelectric sheet and extending to its outer annular surface and a fourth electrode disposed on the lower side of the annular piezoelectric sheet and extending to its outer annular surface, the first electrode and the fourth electrode being interconnected.

2. The piezoelectric stack as described in claim 1, characterized in that, The axial projection of the area covered by the third electrode falls within the area covered by the second electrode.

3. The piezoelectric stack as described in claim 2, characterized in that, The solid piezoelectric sheet includes a first substrate, and the shape of the second electrode is the same as that of the first substrate, but its outer edge dimension is smaller than that of the first substrate, thereby forming a first peripheral insulating ring between the outer edge of the second electrode and the outer edge of the first substrate.

4. A piezoelectric stack as described in claim 3, characterized in that, The annular piezoelectric sheet includes a second substrate with a through hole in the middle. The third electrode is an annular electrode with the same outer edge size as the second electrode, thereby forming a second circumferential insulating ring between the outer edge of the third electrode and the outer edge of the second substrate.

5. A piezoelectric stack as described in claim 4, characterized in that, The fourth electrode is a ring electrode, the inner edge of which has the same shape as the through hole, and its inner edge size is larger than that of the through hole, thereby forming an inner circumferential insulating ring between the inner edge of the fourth electrode and the through hole.

6. A piezoelectric stack as described in claim 4, characterized in that, The outer edge shape and size of the second substrate are the same as those of the first substrate.

7. A piezoelectric stack as described in claim 1, characterized in that, The annular piezoelectric sheet is suitable for being stacked sequentially in opposite directions along the axial direction.

8. A piezoelectric buzzer, characterized in that, It includes a metal sheet and a piezoelectric stack as described in any one of claims 1 to 7, wherein the metal sheet is fixedly connected to the end of the piezoelectric stack, and during operation, the piezoelectric stack generates vibration and transmits it to the metal sheet, thereby driving the metal sheet to vibrate and produce sound.

9. A piezoelectric buzzer as described in claim 8, characterized in that, The diameter of the metal sheet is larger than the outer diameter of the piezoelectric stack.

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