CN211350089U - Piezoelectric ceramic buzzer using potassium-sodium niobate leadless piezoelectric technology - Google Patents

Abstract

The utility model discloses a piezoelectric ceramic buzzer piece adopting potassium-sodium niobate leadless piezoelectric technology. The utility model discloses a piezoceramics buzzing piece is including the substrate that has electrically conductive attribute to and a slice or two positive and negative surfaces are attached to the potassium sodium niobate base leadless piezoceramics piece that has the electrode layer respectively, the leadless piezoceramics piece of base bonds each other through the adhesive with electrically conductive substrate, the electrode layer of the non-bonding face of leadless piezoceramics piece is the disconnect-type ring structure that a concentric circle constitutes. The utility model discloses a disconnect-type ring structure of electrode layer realizes such as the frequency conversion, falls to make an uproar, adjusts the sound pressure ratio and optimizes the physical characteristic of piezoceramics piece, reduces the failure rate of buzzing piece.

Description

Piezoelectric ceramic buzzer using potassium-sodium niobate leadless piezoelectric technology

Technical Field

The utility model relates to a piezoceramics buzzing piece has especially related to a potassium-sodium niobate (KNN) base leadless piezoceramics buzzing piece, belongs to piezoelectric element technical field.

Background

A piezoelectric buzzer is an electroacoustic transducer. The existing piezoelectric buzzer sheet is structured by adhering a piezoelectric ceramic sheet on a metal substrate (generally a copper sheet, a stainless steel sheet or a nickel alloy sheet). When a high-frequency alternating current signal is loaded on the electrode on the buzzer and the electrode on the metal substrate, the piezoelectric ceramic piece generates corresponding deformation due to the piezoelectric effect, and drives the metal substrate to vibrate to generate sound. However, when the buzzer is used, due to high-frequency vibration, the rubber layer between the metal substrate and the piezoelectric ceramic piece is easy to lose efficacy due to the rise of temperature under the high-temperature environment, so that the metal substrate and the piezoelectric ceramic piece are separated, and the buzzer cannot be normally used under the high-temperature environment. Many ways to solve the problem are provided, for example, in patent CN201820730605, X, the nickel-iron alloy sheet, the high-temperature resistant glue, and the insulating groove added on the metal substrate are used to control the failure of the glue layer, so as to prevent the metal substrate from separating from the piezoelectric ceramic. The adhesive layer is most prone to failure, and is also the place where the piezoelectric ceramic plate and the metal substrate are separated at the earliest, and is often the edge of the buzzer, because the edge has the largest vibration amplitude or is uneven in physical structure as a support belt.

Due to the frequency response characteristic of the piezoelectric buzzer, the sound pressure effect is optimal only at a certain frequency point, and the sound effect conversion is relatively poor at other frequency points, namely the sound effect is low. For example, in patent CN201820162932, X, a hollow circular truncated cone structure is formed at the center of the ceramic electrode of the buzzer to improve the common voice effect of the piezoelectric buzzer. For example, CN 201821534707.0 achieves the purpose of changing frequency by adding a frequency converter.

The sound pressure ratio of the piezoelectric buzzer is mainly related to the electromechanical coupling coefficient of the piezoelectric material, which is the maximum value that the buzzer can reach, so the sound pressure ratio is often adjusted by an external structure, for example, CN201520696937.7 adjusts the sound pressure ratio by adding a multi-stage resistor, CN 201910444055.4 adjusts the sound pressure ratio by a sound hole of the outer shell and a rotor thereon. But the process is complicated and the cost is greatly increased.

Still some piezoelectricity buzzing pieces are because the installation is inaccurate, and noise problem, accurate sound problem etc. appear in the defect in buzzing piece self technology even.

At present, lead zirconate titanate (PZT) ceramic materials are still used for piezoelectric buzzer devices. However, not only is the lead-containing material currently harmful, but as PZT elements are manufactured, the corresponding toxic waste of lead will increase, causing inevitable harm to future human beings and the entire ecological environment. This crisis has increasingly called for the arrival of lead-free materials.

Disclosure of Invention

The technical problem to be solved in the present invention is to use leadless piezoelectric ceramics to make the piezoelectric buzzer piece with satisfactory performance, and to realize the frequency conversion of the device, reduce the noise, adjust the sound pressure ratio and optimize the physical characteristics of the piezoelectric ceramic piece, and reduce the failure rate of the buzzer piece.

The utility model adopts the technical proposal that:

in order to achieve the above object, the present invention provides a piezoelectric buzzer using potassium-sodium niobate (KNN) -based leadless piezoelectric ceramic technology. The piezoelectric ceramic buzzer comprises a substrate with a conductive property and one or two potassium-sodium niobate-based lead-free piezoelectric ceramic pieces, wherein electrode layers are respectively attached to the positive and negative surfaces of the one or two potassium-sodium niobate-based lead-free piezoelectric ceramic pieces, the KNN-based lead-free piezoelectric ceramic pieces are mutually bonded with the conductive substrate through an adhesive, and the electrode layers on the non-bonding surfaces of the KNN-based lead-free piezoelectric ceramic pieces are of a separated ring structure formed by concentric circles.

Furthermore, the electromechanical coupling coefficient of the KNN-based lead-free piezoelectric ceramic piece is between 0.5 and 0.7.

As one of the preferable schemes, the center of the separated ring structure is a circle.

As another preferred solution, the outermost ring of the split ring structure is connected to the conductive substrate.

The method for manufacturing the piezoelectric ceramic buzzer piece comprises the following steps:

step A, coating a full electrode on one surface of the piezoelectric ceramic piece;

step B, coating a separated circular ring structure electrode with a preferred scheme on the other surface of the piezoelectric ceramic sheet;

and C, polarizing the piezoelectric ceramic piece, wherein the full electrode surface is connected with one pole of a high-voltage power supply, one surface of the separated circular ring structure is pasted with a copper foil, and the copper foil is tightly pasted on the separated circular ring structure by using a soft medium and is connected with the other pole of the high-voltage power supply.

D, coating a layer of adhesive on the full electrode surface of the piezoelectric ceramic piece, horizontally placing the surface with the adhesive upwards, covering the conductive substrate on the conductive substrate, and applying proper pressure to ensure that the substrate and the piezoelectric ceramic piece below the substrate form a stable whole;

step E, curing the adhesive;

step F, leading out wires from bonding pads of all rings in the separated ring structure of the piezoelectric ceramic buzzer;

and G, in the separated circular ring structure of the piezoelectric ceramic buzzer, the outermost ring of the circular ring is connected with the conductive substrate and is connected with one pole of the input power supply, and the innermost ring of the circular ring is circularly connected with the other pole of the input power supply.

And step H, in the separated circular ring structure of the piezoelectric ceramic buzzer, the conductive substrate or the innermost circular electrode except the outermost circular ring and the innermost circular electrode can be randomly connected or even can be vacant according to requirements.

According to the manufacturing method of the piezoelectric ceramic buzzer piece, the number of the piezoelectric ceramic pieces is two, the steps of the piezoelectric ceramic pieces are consistent with those of the piezoelectric ceramic pieces when one piezoelectric ceramic piece is used, and the steps are repeated when the second piezoelectric ceramic piece is pasted. Only the separated circular ring structure needs the patterns on the two piezoelectric ceramic sheets to be kept consistent, and the wires led out from the bonding pads of all the circular rings are also connected with each other consistently.

Drawings

FIG. 1 shows the bonding pads of the rings in the split ring for the lead-out wires;

FIG. 2 is a top view of the split ring;

FIG. 3 is a side view of a piece of piezoceramic wafer;

FIG. 4 is a top view of the full electrode face of the piezoceramic wafer;

fig. 5 is a schematic view of the overall structure of a piezoelectric ceramic buzzer piece in which the piezoelectric ceramic is one piece.

The following description is made with reference to the accompanying drawings:

1 is an electrode surface with a separated circular ring structure on one surface of the piezoelectric ceramic;

2 is a piezoelectric ceramic piece;

3 is an electrode surface with a full electrode structure on the other surface of the piezoelectric ceramic;

4 is an adhesive layer;

5 is a conductive substrate;

10 is one of the preferable schemes, the center of the separated circular ring structure is circular;

11. 12 is an independent ring in the separated rings;

13 is the outermost ring in the separated ring structure;

100 is a circular lead-out pad in a separated circular ring structure;

110. 120 is the lead-out pad of the independent ring in the separate ring;

130 is a leading-out bonding pad of the outermost ring in the separated ring structure;

and 500 are lead-out pads on the conductive substrate.

Detailed Description

The invention will be described in further detail with reference to the following drawings and specific embodiments: this embodiment is merely one basic embodiment of the invention, and not all embodiments.

The utility model provides a piezoelectric ceramic buzzer piece, is including the substrate 5 that has electrically conductive attribute to and a positive anti-surface KNN base leadless piezoelectric ceramic piece 2 that has the electrode layer respectively attached to of a slice, KNN base leadless piezoelectric ceramic piece 2 bonds each other through adhesion agent 4 with electrically conductive substrate 5, the electrode layer of the non-bonding face of KNN base leadless piezoelectric ceramic piece 2 is the disconnect-type ring structure 1 that a concentric circle constitutes, the bonding face electrode layer of KNN base leadless piezoelectric ceramic piece 2 is full electrode structure 3. The piezoelectric ceramic buzzer piece can be manufactured by the following method:

a, coating a full electrode 3 on one surface of a KNN-based lead-free piezoelectric ceramic piece 2;

and step B, coating the other surface of the KNN-based lead-free piezoelectric ceramic sheet 2 with a separated circular ring structure electrode 1 with a preferred scheme. The schematic diagram of the electrode 1 is shown in fig. 2, wherein 10 is a circular surface, and the bonding pad led out of the circular surface is 100, wherein 10 can use circular surfaces with different diameters, and the width of 11 or 12, the distance between the two, and the like can be adjusted so as to better adjust the frequency or sound pressure ratio, and in the embodiment, the two are equidistant and the same width;

and step C, carrying out high-voltage polarization on the KNN-based piezoelectric ceramic piece 2, wherein the full electrode surface 3 is connected with one pole of a high-voltage power supply, the surface of the separated circular ring structure 1 is pasted with copper foil with the size consistent with that of the piezoelectric ceramic piece 2, the whole copper foil is tightly pasted on the separated circular ring structure by using a soft medium, and then the copper foil is connected with the other pole of the high-voltage power supply for polarization, wherein the polarization can be high-temperature oil polarization or air high-temperature polarization.

D, coating a layer of adhesive 4 on the full electrode surface 3 of the KNN-based piezoelectric ceramic piece 2, horizontally placing the surface with the adhesive upwards, covering the conductive substrate 5 on the surface, and applying proper pressure to ensure that the conductive substrate 5 and the piezoelectric ceramic piece 2 below the conductive substrate form a stable whole;

step E, solidifying the adhesive of the adhesive layer 4;

step F, welding wires from the welding pads 100, 110, 120 and 130 in the separated ring structure 1 of the KNN-based piezoelectric ceramic piece 2, and leading out corresponding wires;

step G, welding wires from the bonding pad 500 in the conductive substrate 5, and leading out corresponding wires;

and step H, connecting the lead led out from the bonding pad 130 and the lead led out from the bonding pad 500 to one pole of the input voltage, and connecting the lead led out from the bonding pad 100 to the other pole of the input voltage.

The connection between the 130 and 500 positions is to make the edge of the piezoelectric ceramic plate 2 in an equipotential state, even if the vibration of other parts of the piezoelectric ceramic plate 2 is transmitted to the edge, the equipotential is known by the inverse piezoelectric effect, so that the vibration energy is rapidly reduced, noise is avoided, and noise is effectively reduced; in addition, the vibration energy at the edge is reduced, the problem of unstable supporting framework caused by uneven physical contact of the edge support is effectively solved, and the problem of separation of the piezoelectric ceramic piece 2 and the conductive substrate 5 caused by cracking of the adhesive layer 4 at the edge is also effectively avoided.

Step I, in actual assembly, wires led out from the bonding pads 110 and 120 can be connected with wires led out from the position 100 according to requirements, the frequency is reduced, the sound pressure ratio is changed, even the wires are only connected with the positions 110 and 100, the position 120 can be in no load, the wires can be connected with the position 500, and flexible frequency adjustment and sound pressure ratio adjustment can be achieved.

Claims (6)

1. The piezoelectric ceramic buzzer adopting the potassium-sodium niobate leadless piezoelectric technology comprises a conductive substrate with conductive property and one or two potassium-sodium niobate-based leadless piezoelectric ceramic pieces, wherein electrode layers are respectively attached to the positive and negative surfaces of the conductive substrate or the two positive and negative surfaces of the conductive substrate, the potassium-sodium niobate-based leadless piezoelectric ceramic pieces are mutually bonded with the conductive substrate through an adhesive, and the electrode layer of the non-bonding surface of the potassium-sodium niobate-based leadless piezoelectric ceramic pieces is of a separated ring structure formed by concentric circles, and the piezoelectric ceramic buzzer is characterized in that: the split ring structure has at least one split ring.

2. The piezoelectric ceramic buzzer piece adopting the potassium-sodium niobate leadless piezoelectric technology of claim 1, characterized in that: the separated circular ring structures are arranged in the same electrode layer surface and can be mutually conducted through the extraction electrodes.

3. The piezoelectric ceramic buzzer piece adopting the potassium-sodium niobate leadless piezoelectric technology of claim 2, characterized in that: the leading-out electrodes of the separated circular ring structure are all arranged on the same side of the piezoelectric ceramic piece.

4. The piezoelectric ceramic buzzer piece adopting the potassium-sodium niobate leadless piezoelectric technology of claim 1, characterized in that: the center of the separated circular ring structure can be circular or circular.

5. The piezoelectric ceramic buzzer piece adopting the potassium-sodium niobate leadless piezoelectric technology of claim 1, characterized in that: potassium sodium niobate based leadless piezoelectric ceramics are adopted as core driving elements.

6. The piezoelectric ceramic buzzer piece adopting the potassium-sodium niobate leadless piezoelectric technology of claim 1, characterized in that: the conductive substrate can be a nickel alloy sheet, a stainless steel sheet, a copper sheet and a carbon fiber conductive substrate.

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