Lead-free piezoelectric ceramic buzzer

Abstract

The invention discloses a lead-free piezoelectric ceramic buzzer which comprises a bottom shell, an upper cover is arranged on the upper portion of the bottom shell, a piezoelectric plate is arranged in an inner cavity between the bottom shell and the upper cover, the bottom of the piezoelectric plate is placed on an inner boss of the bottom shell, the edge of the upper cover is placed in an inner wall groove in the upper end of the bottom shell, and a small inner groove is formed in the upper end of the inner wall groove. A small inner groove is formed in the inner wall groove, a small boss is arranged at the top of the upper cover edge and placed in the small inner groove, an outer fillet is arranged on the upper edge of the inner wall groove, an inner fillet is arranged on the outer edge of the small inner groove, a copper substrate is arranged at the bottom of the piezoelectric plate, a piezoelectric ceramic layer is arranged on the upper portion of the piezoelectric plate, and the piezoelectric ceramic layer is made of lead-free materials.

Description

Technical Field

[0001] The present invention relates to the field of electronic components, especially to the field of buzzers used in electrical appliances. Background Art

[0002] The piezoelectric buzzer used in electrical appliances is a common type of electronic component, which can play a role of emitting warning sounds when applied to products. In the previous structure, the piezoelectric buzzer is divided into three main components: a bottom shell, an upper cover and a piezoelectric sheet. When the upper cover is installed into the groove on the wall of the bottom shell, due to the elasticity of the plastic, when the upper cover is subjected to external forces, it may pop out from the groove of the bottom shell. At the same time, for the piezoelectric sheet of the conventional piezoelectric buzzer, a copper substrate is added with a ceramic layer, and then a silver layer or a graphene layer is added on the ceramic layer to achieve the purpose of conduction. If the ceramic layer is a lead-containing material, it will be adverse to environmental protection and cause serious environmental pollution. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a lead-free piezoelectric ceramic buzzer, which includes a bottom shell, an upper cover is arranged on the upper part of the bottom shell, and a piezoelectric sheet is arranged in the inner cavity between the bottom shell and the upper cover. The bottom of the piezoelectric sheet is placed on the inner convex platform of the bottom shell, and a circular through hole is arranged at the center of the inner convex platform, which is beneficial to the sound to be transmitted from the hole. The edge of the upper cover is placed in the inner wall groove at the upper end of the bottom shell. A small inner groove is arranged at the upper end of the inner wall groove, and a small convex platform is arranged at the top of the edge of the upper cover. The small convex platform is placed in the small inner groove, which can prevent the upper cover from disengaging from the inner wall groove of the bottom shell and play a dual anti-disengagement effect.

[0004] Further, an outer chamfered corner is arranged at the upper edge of the inner wall groove.

[0005] Further, an inner chamfered corner is arranged at the outer edge of the small inner groove.

[0006] Preferably, the bottom of the piezoelectric sheet is a copper substrate, and the upper part is a piezoelectric ceramic layer. A silver layer or a graphene layer is arranged at the top of the piezoelectric ceramic layer.

[0007] Preferably, the material of the piezoelectric ceramic layer is lead-free type. The main systems of the lead-free piezoelectric ceramic include the following:

[0008] A. Barium titanate-based lead-free piezoelectric ceramic

[0009] B. BNT-based lead-free piezoelectric ceramic

[0010] C. Bismuth layer-structured piezoelectric ceramic

[0011] D. Niobate-based lead-free piezoelectric ceramic

[0012] Applying the above invention solution to change the piezoelectric ceramic layer on the piezoelectric sheet in the piezoelectric ceramic buzzer from lead-containing to lead-free will enhance the environmental protection level and avoid lead pollution. At the same time, adding small convex platforms to the upper cover and snapping the small convex platforms into the small inner grooves in the inner wall grooves of the bottom shell can further prevent the possibility of the upper cover coming off, improve the reliability of the product, optimize the product structure, and significantly improve the quality assurance and lifespan of the product. Brief Description of the Drawings

[0013] The following will further elaborate in detail in conjunction with the drawings and the implementation manners of the invention.

[0014] Figure 1 A cross-sectional view of the present invention is shown.

[0015] Figure 2 A three-dimensional schematic diagram of the assembled present invention is shown.

[0016] Figure 3 An enlarged schematic diagram of a partial position of the present invention is shown. Detailed Description of the Specific Embodiment

[0017] As Figures 1 - 3 shown, the specific content of the invention will be described in detail below with an embodiment: A lead-free piezoelectric ceramic buzzer, which includes a bottom shell 2, an upper cover 1 is arranged on the upper part of the bottom shell 2, a piezoelectric sheet 3 is arranged in the inner cavity between the bottom shell 2 and the upper cover 1, the bottom of the piezoelectric sheet 3 is placed on the inner convex platform 25 of the bottom shell 2, a circular through hole is arranged at the center of the inner convex platform 25, which is beneficial for the sound to be transmitted through the hole, the edge of the upper cover is placed in the inner wall groove 21 at the upper end of the bottom shell, a small inner groove 22 is arranged at the upper end of the inner wall groove 21, a small convex platform 121 is arranged at the top of the edge of the upper cover, and the small convex platform 121 is placed in the small inner groove 22, which can prevent the upper cover 1 from coming out of the inner wall groove 21 of the bottom shell 2 and play a dual anti-disengagement effect.

[0018] In the embodiment of the present invention, an outer chamfered fillet 24 is arranged on the upper edge of the inner wall groove 21. Setting this fillet can effectively decompose the die stress and reduce the resistance when the upper cover 1 is pressed into the small inner groove 22 on the inner wall groove 21 by mechanical force, enabling the small convex platform 121 to smoothly enter the small inner groove 22 without being damaged.

[0019] In the embodiment of the present invention, an inner chamfered fillet 23 is arranged on the outer edge of the small inner groove 22. Setting this fillet can effectively reduce the resistance when the upper cover 1 is pressed into the inner wall groove 21 of the bottom shell by mechanical force, enabling the upper cover 1 to smoothly enter the inner wall groove 21 without being damaged.

[0020] In the embodiment of the present invention, preferably, the bottom of the piezoelectric sheet is a copper-based sheet 31, and the upper part is a piezoelectric ceramic layer 32. A silver layer or a graphene layer is arranged on the top of the piezoelectric ceramic layer 32.

[0021] In an embodiment of the present invention, preferably, the material of the piezoelectric ceramic layer 32 is lead-free. The main systems of lead-free piezoelectric ceramics include the following:

[0022] A. Barium titanate-based lead-free piezoelectric ceramics

[0023] B. BNT-based lead-free piezoelectric ceramics

[0024] C. Bismuth layer-structured piezoelectric ceramics

[0025] D. Niobate-based lead-free piezoelectric ceramics

[0026] Although traditional piezoelectric ceramics have many outstanding advantageous properties, their disadvantage is that their main component, lead oxide PbO (with a content of more than 60-70%), is a toxic substance that is prone to volatilization. The sintering temperature is generally above 1200°C, which often causes deviation in the stoichiometry of lead zirconate titanate PZT ceramics, and it is difficult to stably control the performance. This is likely to cause environmental pollution and seriously endanger the health of humans and other organisms.

[0027] The purpose of developing the above lead-free ceramics is that researchers are committed to obtaining piezoelectric ceramics that not only have satisfactory use performance but also good environmental compatibility. It is required that the material system itself does not contain substances that may have a harmful impact on the ecological environment and does not produce substances that may be harmful to the environment during the preparation, use, and post-use processes.

[0028] In an embodiment of the present invention, the piezoelectric ceramic layer 32 in the piezoelectric sheet 3 is adhered tightly to the copper-based sheet 31 with glue. The upper cover 1 is provided with two pin feet 11. The pin feet 11 are divided into positive and negative poles. One end of the pin feet 11 extends out of the upper cover body 12 by a certain length, and the other end is bent to form an elastic contact with different pole positions of the piezoelectric sheet 3. When powered on, under the action of the current, the piezoelectric sheet 3 vibrates and emits sound. The relevant descriptions of the basic structure and function of the above piezoelectric buzzer are prior art that has been published and will not be elaborated here.

[0029] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A lead-free piezoelectric ceramic buzzer, which comprises a bottom shell, an upper cover is arranged on the upper part of the bottom shell, a piezoelectric sheet is arranged in the inner cavity between the bottom shell and the upper cover, the bottom of the piezoelectric sheet is placed on the inner convex platform of the bottom shell, and the edge of the upper cover is placed in the inner wall groove at the upper end of the bottom shell, and is characterized in that, A small inner groove is provided at the upper end of the inner wall groove, and a small convex platform is provided at the top of the edge of the upper cover. The small convex platform is placed in the small inner groove.

2. The lead-free piezoelectric ceramic buzzer according to claim 1, wherein: An outer chamfered corner is provided at the upper edge of the inner wall groove.

3. The lead-free piezoelectric ceramic buzzer according to claim 1, characterized in that: An inner chamfered corner is provided at the outer edge of the small inner groove.

4. The lead-free piezoelectric ceramic buzzer according to claim 1, characterized in that: A circular through-hole is provided at the center of the inner convex platform.

5. A lead-free piezoelectric ceramic buzzer according to claim 1, characterized in that: The bottom of the piezoelectric sheet is a copper substrate, and the upper part is a piezoelectric ceramic layer. A silver layer or a graphene layer is provided at the top of the piezoelectric ceramic layer.

6. The lead-free piezoelectric ceramic buzzer according to claim 5, wherein: The material of the piezoelectric ceramic layer is lead-free type.

Images