A laminated patch piezoelectric buzzer

Abstract

The application discloses a laminated patch piezoelectric buzzer and relates to the field of electroacoustic devices, which comprises a shell, a metal sheet, a first ceramic sheet with a first electrode and a second electrode arranged on opposite surfaces, the first electrode facing the metal sheet and being electrically connected with the metal sheet, a second ceramic sheet laminated on the first ceramic sheet, the second ceramic sheet having a third electrode and a fourth electrode arranged on opposite surfaces, the third electrode facing the second electrode and being electrically connected with the second electrode, and part of the second electrode being exposed without being covered by the second ceramic sheet, a metal spring needle comprising a first spring needle and a second spring needle, the first spring needle being connected with the fourth electrode, and the second spring needle being connected with the exposed area of the second electrode, and the fourth electrode and the metal sheet being electrically connected through an electrical connection structure to realize conduction, so that the first ceramic sheet and the second ceramic sheet are electrically connected in parallel. The application does not need to additionally arrange an additional connecting piece, simplifies the electrical connection structure, reduces assembly procedures and material cost, and improves reliability and service life.

Description

Technical Field

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

[0002] Stacked chip piezoelectric buzzers are made by stacking two piezoelectric ceramic plates on a metal substrate and using the inverse piezoelectric effect to drive the metal plates to vibrate and produce sound. Because they can achieve high sound pressure output in a small volume, they are widely used in portable electronic devices, smart homes and automotive electronics. In order to make the two ceramic plates work together, they are often connected in parallel to reduce driving impedance and improve sensitivity, which is especially suitable for low voltage power supply scenarios.

[0003] However, existing parallel-connected multilayer piezoelectric buzzer structures have some shortcomings in achieving electrical parallel connection: First, to achieve parallel connection between the two ceramic plates, additional conductive connectors, such as conductive adhesive, flexible wires, or metal clips, are usually required inside the housing to connect the top electrode of the upper ceramic plate to the bottom electrode of the lower ceramic plate or the metal clip connected to the lower ceramic plate. These additional components not only increase assembly steps and material costs, but also, under long-term vibration environments, the connectors are prone to fatigue fracture or increased contact resistance, leading to decreased product reliability; Second, in conventional multilayer structures, the two ceramic... The intermediate electrode between the plates is completely covered by the upper ceramic plate and cannot directly contact the external circuit. To bring out this electrode, complex wiring is often required inside the housing, which occupies the limited space inside the housing and increases the difficulty of assembly and positioning as well as the risk of short circuits. Furthermore, in some existing parallel solutions, three or more spring pins are used to connect the metal plate, the intermediate electrode and the top electrode respectively, resulting in more openings in the housing and a decrease in sealing and dustproof performance. Other designs reduce the number of spring pins, but require the connection to be achieved by welding jumpers inside the housing, which increases the complexity of production and the possibility of electrical failure. Therefore, improvements are needed. Summary of the Invention

[0004] The purpose of this application is to provide a laminated patch piezoelectric buzzer.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: a multilayer patch piezoelectric buzzer, comprising: a housing; a metal sheet disposed within the housing; a first ceramic sheet disposed on the metal sheet, having a first electrode and a second electrode disposed on opposite surfaces, the first electrode facing the metal sheet and electrically connected thereto; a second ceramic sheet stacked on the first ceramic sheet, having a third electrode and a fourth electrode disposed on opposite surfaces, the third electrode facing the second electrode and electrically connected thereto, and a portion of the second electrode being exposed and not covered by the second ceramic sheet; and a metal spring needle, comprising a first spring needle and a second spring needle, both the first spring needle and the second spring needle being mounted on the housing, the first spring needle being connected to the fourth electrode, and the second spring needle being connected to the exposed area of ​​the second electrode; the fourth electrode and the metal sheet are electrically connected through an electrical connection structure, so that the first ceramic sheet and the second ceramic sheet are electrically connected in parallel.

[0006] As a preferred embodiment, the electrical connection structure is the first spring pin, which has a first contact portion and a second contact portion. The first contact portion abuts against the fourth electrode, and the second contact portion abuts against the metal sheet, so that the fourth electrode and the metal sheet are directly connected through the first spring pin. The first ceramic sheet and the second ceramic sheet are electrically connected in parallel after the first spring pin is assembled.

[0007] Further preferably, both the first contact portion and the second contact portion are formed by bending the first spring pin and are located on the same side of the first spring pin. The bending angle of the first contact portion is greater than that of the second contact portion, and the length of the first contact portion is shorter than that of the second contact portion, so that the free ends of the first contact portion and the free ends of the second contact portion are located at different positions in the height direction of the first spring pin. The free end of the first contact portion abuts against the fourth electrode, and the free end of the second contact portion abuts against the metal sheet.

[0008] Further preferably, both the first contact portion and the second contact portion are formed by bending the first spring pin and are located on both sides of the first spring pin respectively. The bending angle of the first contact portion is greater than that of the second contact portion, and the length of the first contact portion is shorter than that of the second contact portion, so that the free ends of the first contact portion and the free ends of the second contact portion are located at different positions in the height direction of the first spring pin. The free end of the first contact portion abuts against the fourth electrode, and the free end of the second contact portion abuts against the metal sheet.

[0009] As a preferred embodiment, the electrical connection structure is a side conductive connection portion, which is disposed on the side of the first ceramic sheet and the second ceramic sheet, and is electrically connected to the fourth electrode and the first electrode respectively, thereby enabling the fourth electrode and the metal sheet to be pre-connected through the side conductive connection portion, and forming an electrical parallel connection between the first ceramic sheet and the second ceramic sheet.

[0010] Further preferably, the first spring pin has a first contact portion formed by bending the first spring pin, and the second spring pin has a third contact portion formed by bending the second spring pin; the length of the first contact portion is equal to the length of the third contact portion, and the bending angle of the first contact portion is smaller than the bending angle of the third contact portion, so that the free ends of the first contact portion and the free ends of the third contact portion are respectively located at different positions in the height direction, the free end of the first contact portion abuts against the fourth electrode, and the free end of the third contact portion abuts against the second electrode.

[0011] As a preferred embodiment, the housing includes a base and a cover. The cover has two mounting slots, and the first spring pin and the second spring pin are respectively assembled into the two mounting slots. The inner sidewall of the cover also has a stepped surface and several slots. The base has a groove, several supporting protrusions, and several locking blocks. The supporting protrusions are distributed around the outer periphery of the groove. The metal sheet is placed on the supporting protrusions. When the cover and the base are assembled together, each locking block engages with the corresponding slot. At the same time, the stepped surface abuts against the edge of the metal sheet and, together with the supporting protrusions, forms a limiting clamp on the metal sheet, thereby fixing the metal sheet inside the housing.

[0012] Further preferably, each of the mounting slots is provided with two insertion holes, and the first spring pin and the second spring pin are each provided with a pin portion and two mounting portions. The two mounting portions are respectively located on both sides of the pin portion and are respectively inserted into the two corresponding insertion holes and bent, thereby forming a fixed abutment with the inner side of the cover. The pin portion is exposed on the outer side of the cover for connection with external circuits.

[0013] In a further preferred embodiment, a spring needle cavity is formed between the cover and the metal sheet, and a first sound outlet is provided on the cover. The first sound outlet is located on the side of the cover and communicates with the spring needle cavity. When the piezoelectric buzzer is working, the metal sheet vibrates and produces sound, and the sound is transmitted from the side of the piezoelectric buzzer through the first sound outlet.

[0014] Further preferably, the base is provided with a second sound outlet, which is located at the bottom or side of the groove and communicates with the groove; when the piezoelectric buzzer is working, the metal sheet vibrates and produces sound, which is transmitted through the second sound outlet.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application achieves conduction by setting an electrical connection structure between the fourth electrode and the metal sheet, so that the first ceramic sheet and the second ceramic sheet are electrically connected in parallel. There is no need to set additional connecting parts such as conductive glue, flexible wire or metal clip in the housing, which greatly simplifies the internal electrical connection structure, reduces assembly process and material cost, and avoids the problem of fatigue fracture of connecting parts or increased contact resistance under long-term vibration environment, which significantly improves the working reliability and service life of the product.

[0016] (2) By exposing a portion of the second electrode without it being covered by the second ceramic sheet, and by directly connecting the second spring pin to the exposed portion, the intermediate electrode between the first ceramic sheet and the second ceramic sheet can be easily led out without the need for complex wiring inside the housing. This saves internal space, reduces assembly and positioning difficulty, and effectively eliminates the risk of short circuits caused by dense internal wiring.

[0017] (3) This application only requires two metal spring pins, the first spring pin and the second spring pin, to simultaneously realize the lead-out of the fourth electrode and the lead-out of the intermediate electrode, and to simultaneously complete the parallel connection of the two ceramic plates by means of the electrical connection structure between the fourth electrode and the metal plate. Compared with the prior art, which requires three or more spring pins or welding jumpers, this application reduces the number of openings in the housing, which is conducive to improving the sealing and dustproof performance of the housing. At the same time, it eliminates the welding jumper process inside the housing, reduces the production complexity and electrical fault points, and makes the overall structure more compact and easier to assemble, which is suitable for mass production. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural diagram of Embodiment 1 of the present invention.

[0019] Figure 2 This is an exploded three-dimensional structural view of Embodiment 1 of the present invention.

[0020] Figure 3 This is a three-dimensional structural diagram of the metal spring pin connection state in Embodiment 1 of the present invention.

[0021] Figure 4 This is a three-dimensional structural diagram of the first spring needle in Embodiment 1 of the present invention.

[0022] Figure 5 This is a three-dimensional structural schematic diagram of Embodiment 2 of the present invention.

[0023] Figure 6 This is a three-dimensional structural schematic diagram from another perspective of Embodiment 2 of the present invention.

[0024] Figure 7 This is an exploded view of the three-dimensional structure of Embodiment 2 of the present invention.

[0025] Figure 8 This is a three-dimensional structural diagram of the metal spring pin connection state in Embodiment 2 of the present invention.

[0026] Figure 9 This is a three-dimensional structural diagram of the first spring needle in Embodiment 2 of the present invention.

[0027] Figure 10 This is a three-dimensional structural diagram of the metal spring pin connection state in Embodiment 3 of the present invention.

[0028] Figure 11 This is a schematic diagram of the inner structure of the cover body of the present invention.

[0029] In the figure: 1. Metal sheet; 2. First ceramic sheet; 21. Second electrode; 3. Second ceramic sheet; 31. Fourth electrode; 4. Metal spring pin; 41. First spring pin; 411. First contact part; 412. Second contact part; 42. Second spring pin; 421. Third contact part; 43. Pin part; 44. Mounting part; 5. Side conductive connection part; 6. Base; 61. Groove; 62. Supporting protrusion; 63. Locking block; 64. Second sound outlet hole; 7. Cover; 71. Mounting groove; 711. Insertion hole; 72. Stepped surface; 73. Locking groove; 74. First sound outlet hole. Detailed Implementation

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] A preferred embodiment of this application, such as Figures 1 to 11 As shown, a multilayer patch piezoelectric buzzer includes: The housing includes a base 6 and a cover 7. The cover 7 has two mounting grooves 71. The inner side wall of the cover 7 also has a stepped surface 72 and several slots 73. The base 6 has a groove 61, several supporting protrusions 62 and several locking blocks 63. The supporting protrusions 62 are distributed around the outer periphery of the groove 61. When the cover 7 and the base 6 are assembled together, each locking block 63 engages with the corresponding slot 73.

[0035] This embodiment provides a split shell structure, which enables screwless quick assembly through the snap-fit ​​connection between the base 6 and the cover 7, simplifying the assembly process. In addition, a support protrusion 62 is provided on the base 6. The support protrusion 62 protrudes from the plane of the base 6 and is distributed on the outer periphery of the groove 61 to support the metal sheet 1, reducing the contact area between the metal sheet 1 and the base 6 and reducing vibration energy loss. The groove 61 on the base 6 is used to avoid the vibration space of the metal sheet 1 and avoid vibration interference. In addition, the stepped surface 72 and the support protrusion 62 together form an upper and lower limiting clamp to ensure that the metal sheet 1 does not shift during vibration.

[0036] In specific implementation, both the base 6 and the cover 7 can be injection molded parts. In terms of specific design, as shown in the attached figure, they can be designed as square, or other shapes can be designed according to actual needs. In this embodiment, the number of the card blocks 63 and card slots 73 is set to four, evenly distributed on the four sides, and the number of the supporting protrusions 62 is also set to four, evenly distributed around the grooves 61. Of course, the specific number, shape and distribution can be adjusted by those skilled in the art according to actual needs.

[0037] Metal sheet 1 is disposed inside the housing and placed on several support protrusions 62. At the same time, the stepped surface 72 abuts against the edge of the metal sheet 1 and together with each support protrusion 62 forms a limiting clamp on the metal sheet 1, thereby fixing the metal sheet 1 inside the housing.

[0038] In this embodiment, the metal sheet 1 can be firmly fixed without screws or adhesives, simplifying the assembly process. Furthermore, the stepped surface 72 only abuts against the edge of the metal sheet 1, without affecting the free vibration of the central area.

[0039] In practical implementation, the shape and size of the metal sheet 1 need to be adapted to the corresponding shape and size inside the housing. In this embodiment, since the internal shape of the housing is square, the metal sheet 1 is also set to be square, and its size is larger than that of the first ceramic sheet 2 and the second ceramic sheet 3. This facilitates the connection of the metal spring pin 4, such as... Figure 3 , Figure 8 and Figure 10 As shown, the length and width of the metal sheet 1 are both larger than those of the first ceramic sheet 2 and the second ceramic sheet 3. Therefore, after the two ceramic sheets and the metal sheet 1 are stacked together to form a piezoelectric stack, there is an area around the metal sheet 1 that is not covered by the ceramic sheets. The metal spring needle 4 can be connected from the same side of the piezoelectric stack, which simplifies the connection structure and saves space for additional wiring.

[0040] A first ceramic sheet 2 is disposed on a metal sheet 1 and has a first electrode and a second electrode 21 disposed on opposite surfaces. The first electrode faces the metal sheet 1 and is electrically connected to it.

[0041] The second ceramic sheet 3 is stacked on the first ceramic sheet 2 and has a third electrode and a fourth electrode 31 disposed on opposite surfaces. The third electrode faces the second electrode 21 and is electrically connected to it, and a portion of the second electrode 21 is not covered by the second ceramic sheet 3 and is exposed.

[0042] With the above configuration, the first electrode is in direct contact with the metal sheet 1, and the third electrode is in direct contact with the second electrode 21 through a stacked connection, without the need for additional wires, resulting in a simple structure. At the same time, the area of ​​the first ceramic sheet 2 is larger than that of the second ceramic sheet 3, naturally forming a stepped structure, and making part of the second electrode 21 exposed, providing a direct contact area for the second spring pin 42, without the need for additional lead-out electrodes.

[0043] In practice, each electrode can be a carbon electrode or a silver electrode. Carbon paste or silver paste is coated on the surface of the corresponding ceramic sheet, and then formed by sintering or other processes. It should be noted that an edge needs to be left when coating, that is, a certain gap needs to be left at the edge of the ceramic sheet.

[0044] Metal spring pin 4 includes a first spring pin 41 and a second spring pin 42. Both the first spring pin 41 and the second spring pin 42 are mounted on the housing. The first spring pin 41 is connected to the fourth electrode 31, and the second spring pin 42 is connected to the exposed area of ​​the second electrode 21.

[0045] In this embodiment, the first spring pin 41 and the second spring pin 42 are respectively assembled in two mounting slots 71. Each mounting slot 71 is provided with two insertion holes 711. The first spring pin 41 and the second spring pin 42 are each provided with a lead portion 43 and two mounting portions 44. The two mounting portions 44 are located on both sides of the lead portion 43 and are respectively inserted into the corresponding two insertion holes 711 and bent, thereby forming a fixed contact with the inner side of the cover 7. The lead portion 43 is exposed on the outer side of the cover 7 for connection with external circuits.

[0046] In this embodiment, two metal spring pins 4 are used to achieve electrical connection with the corresponding electrodes. To ensure the stable installation of the metal spring pins 4 and the convenience of assembly, the mounting part 44 of the metal spring pin 4 is inserted into the corresponding socket 711 and bent to fix it. The two mounting parts 44 are respectively set on both sides of the pin part 43. After the spring pin is fixed, the force is symmetrical and stable and reliable. After the mounting part 44 is bent, it forms a fixed abutment with the inner side of the cover 7 to prevent the spring pin from loosening or falling off during vibration. In addition, the insertion and bending are easy to implement in the assembly process and the process is simple and efficient.

[0047] It should be noted that the piezoelectric stack is not conductive through the above structure. Therefore, in this embodiment, the fourth electrode 31 and the metal sheet 1 are connected by an electrical connection structure so that the first ceramic sheet 2 and the second ceramic sheet 3 are electrically connected in parallel.

[0048] In some embodiments, the electrical connection structure is a first spring pin 41, which has a first contact portion 411 and a second contact portion 412. The first contact portion 411 abuts against the fourth electrode 31, and the second contact portion 412 abuts against the metal sheet 1, so that the fourth electrode 31 and the metal sheet 1 are directly connected through the first spring pin 41. The first ceramic sheet 2 and the second ceramic sheet 3 are electrically connected in parallel after being assembled with the first spring pin 41.

[0049] The above scheme provides a first specific implementation of the electrical connection structure. It can be understood that in the above scheme, the first ceramic plate 2 and the second ceramic plate 3 do not need to be pre-connected in parallel. They are naturally connected in parallel when the two metal spring pins 4 are assembled, saving a special parallel connection process. In the above scheme, only the first contact part 411 and the second contact part 412 need to be set on the first spring pin 41 and connected to the fourth electrode 31 and the metal plate 1 respectively. The connection is formed by the first spring pin 41 itself, without changing the structure of the two ceramic plates. With this setting, the first spring pin 41 serves as both a spring pin and a conductive connector, reducing additional conductive components, and the structure is simple and highly reliable.

[0050] In one more specific embodiment, such as Figures 1 to 4As shown, both the first contact portion 411 and the second contact portion 412 are formed by bending the first spring pin 41 and are located on the same side of the first spring pin 41. The bending angle of the first contact portion 411 is greater than that of the second contact portion 412, and the length of the first contact portion 411 is shorter than that of the second contact portion 412, so that the free end of the first contact portion 411 and the free end of the second contact portion 412 are located at different positions in the height direction of the first spring pin 41. The free end of the first contact portion 411 abuts against the fourth electrode 31, and the free end of the second contact portion 412 abuts against the metal sheet 1.

[0051] In the above-described specific structure, the two contact parts are bent on the same side, resulting in a compact overall structure suitable for situations where the internal space of the housing is limited. Furthermore, through the combination of differences in bending angle and length, the free ends of the two contact parts are positioned at different locations, enabling them to contact corresponding electrodes and metal sheets 1 at different heights and distances.

[0052] It should be noted that the free ends of the two contact parts can only contact the corresponding fourth electrode 31 or metal sheet 1, and cannot contact the second electrode 21 to avoid short circuit.

[0053] In another, more specific embodiment two, such as Figures 5 to 9 As shown, both the first contact portion 411 and the second contact portion 412 are formed by bending the first spring pin 41 and are located on both sides of the first spring pin 41. The bending angle of the first contact portion 411 is greater than that of the second contact portion 412, and the length of the first contact portion 411 is shorter than that of the second contact portion 412, so that the free end of the first contact portion 411 and the free end of the second contact portion 412 are located at different positions in the height direction of the first spring pin 41. The free end of the first contact portion 411 abuts against the fourth electrode 31, and the free end of the second contact portion 412 abuts against the metal sheet 1.

[0054] In the specific structure described above, the two contact parts are bent to both sides, and the lateral distance between the contact points is relatively large, which is suitable for situations where there is ample space around the spring needle; the bending to both sides avoids the stress between the two contact parts from affecting each other, and each contact part is elastically independent.

[0055] The above-mentioned scheme of achieving parallel connection of two ceramic plates through the first spring pin 41 has obvious advantages, namely, that there is no need to realize the parallel connection of the two ceramic plates in advance, and the parallel structure can be automatically realized by simply assembling the first spring pin 41 and the second spring pin 42. However, the disadvantage is that the structures of the first spring pin 41 and the second spring pin 42 are completely different and cannot be interchanged, which will increase the cost of the metal spring pin 4 and the assembly difficulty.

[0056] In other embodiments, such as Embodiment 3, refer to Figure 10As shown, the electrical connection structure is a side conductive connection part 5, which is disposed on the side of the first ceramic sheet 2 and the second ceramic sheet 3, and is electrically connected to the fourth electrode 31 and the first electrode respectively, so that the fourth electrode 31 and the metal sheet 1 are pre-connected through the side conductive connection part 5, and the first ceramic sheet 2 and the second ceramic sheet 3 are electrically connected in parallel.

[0057] The above scheme provides a second specific implementation of the electrical connection structure. It can be understood that the fourth electrode 31 and the metal sheet 1 are pre-connected through the side conductive connection part 5. The two ceramic sheets are already connected in parallel before assembly, and are not affected by the structure and assembly accuracy of the metal spring pin 4. Therefore, the structures of the first spring pin 41 and the second spring pin 42 can be completely identical, and the two can be interchanged, reducing costs. In addition, the side conductive connection part 5 is located on the side of the two ceramic sheets, which does not occupy the thickness direction space, making it convenient for the product to be thin.

[0058] In specific implementation, the side conductive connection part 5 can be a conductive coating applied to the sides of the first ceramic sheet 2 and the second ceramic sheet 3. The conductive coating is a silver paste sintered layer that extends along the side of the ceramic sheet, with its upper end connected to the fourth electrode 31 and its lower end connected to the first electrode. Alternatively, in some embodiments, the side conductive connection part 5 can also be an independently set conductive sheet or conductive spring sheet, which is fixed to the sides of the two ceramic sheets by welding or bonding.

[0059] More specifically, the first spring pin 41 has a first contact portion 411, which is formed by bending the first spring pin 41; the second spring pin 42 has a third contact portion 421, which is formed by bending the second spring pin 42; the length of the first contact portion 411 is equal to the length of the third contact portion 421; the bending angle of the first contact portion 411 is smaller than the bending angle of the third contact portion 421, so that the free ends of the first contact portion 411 and the free ends of the third contact portion 421 are at different positions in the height direction; the free end of the first contact portion 411 abuts against the fourth electrode 31; and the free end of the third contact portion 421 abuts against the second electrode 21.

[0060] The above-mentioned scheme of achieving parallel connection of two ceramic plates through the side conductive connection part 5 has obvious advantages. Since the two ceramic plates are pre-connected in parallel, the structures of the first spring pin 41 and the second spring pin 42 can be set to be exactly the same, which can be universally interchanged, reducing the cost and assembly difficulty of the metal spring pin 4. However, the disadvantage is also clear: the two ceramic plates need to be electrically connected in parallel in advance.

[0061] The two specific implementation schemes described above can be selected by those skilled in the art based on the actual situation.

[0062] In a specific sound-emitting structure of this embodiment, a spring needle cavity is formed between the cover 7 and the metal sheet 1. A first sound outlet 74 is provided on the cover 7. The first sound outlet 74 is located on the side of the cover 7 and communicates with the spring needle cavity. When the piezoelectric buzzer is working, the metal sheet 1 vibrates and produces sound. The sound is transmitted from the side of the piezoelectric buzzer through the first sound outlet 74.

[0063] In the above solution, the first sound outlet 74 is located on the side of the cover 7, which does not occupy the thickness space and helps to reduce the overall thickness of the buzzer. In addition, the first sound outlet 74 is connected to the spring needle cavity, which also serves as the sound outlet cavity. There is no need to set up a separate sound cavity. The structure is compact and suitable for application scenarios with limited thickness space, such as ultra-thin wearable devices.

[0064] Another specific sound-emitting structure in this embodiment is provided on the base 6 with a second sound-emitting hole 64. The second sound-emitting hole 64 is located at the bottom or side of the groove 61 and is connected to the groove 61. When the piezoelectric buzzer is working, the metal sheet 1 vibrates and produces sound, and the sound is transmitted through the second sound-emitting hole 64.

[0065] In the above scheme, the second sound outlet 64 is connected to the groove 61, and the groove 61 is used as the sound outlet cavity, so there is no need to set up an additional independent sound outlet cavity; of course, in some other embodiments, the first sound outlet 74 and the second sound outlet 64 can be set up at the same time to realize dual-cavity sound production.

[0066] 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 multilayer patch piezoelectric buzzer, characterized in that, include: case; A metal sheet, the metal sheet being disposed within the housing; A first ceramic sheet is disposed on the metal sheet and has a first electrode and a second electrode disposed on opposite surfaces, the first electrode facing the metal sheet and electrically connected thereto; The second ceramic sheet is stacked on the first ceramic sheet and has a third electrode and a fourth electrode disposed on opposite surfaces. The third electrode faces the second electrode and is electrically connected to it, and a portion of the second electrode is not covered by the second ceramic sheet and is exposed. A metal spring needle, comprising a first spring needle and a second spring needle, both the first spring needle and the second spring needle being mounted on the housing, the first spring needle being connected to the fourth electrode, and the second spring needle being connected to the exposed area of ​​the second electrode. The fourth electrode is electrically connected to the metal sheet, thereby enabling the first ceramic sheet and the second ceramic sheet to be electrically connected in parallel.

2. The laminated patch piezoelectric buzzer as described in claim 1, characterized in that, The electrical connection structure is the first spring pin, which has a first contact portion and a second contact portion. The first contact portion abuts against the fourth electrode, and the second contact portion abuts against the metal sheet, so that the fourth electrode and the metal sheet are directly connected through the first spring pin. The first ceramic sheet and the second ceramic sheet are electrically connected in parallel after the first spring pin is assembled.

3. A laminated patch piezoelectric buzzer as described in claim 2, characterized in that, Both the first contact portion and the second contact portion are formed by bending the first spring pin and are located on the same side of the first spring pin. The bending angle of the first contact portion is greater than that of the second contact portion, and the length of the first contact portion is shorter than that of the second contact portion, so that the free ends of the first contact portion and the free ends of the second contact portion are located at different positions in the height direction of the first spring pin. The free end of the first contact portion abuts against the fourth electrode, and the free end of the second contact portion abuts against the metal sheet.

4. A laminated patch piezoelectric buzzer as described in claim 2, characterized in that, Both the first contact portion and the second contact portion are formed by bending the first spring pin and are located on both sides of the first spring pin respectively. The bending angle of the first contact portion is greater than that of the second contact portion, and the length of the first contact portion is shorter than that of the second contact portion, so that the free ends of the first contact portion and the free ends of the second contact portion are located at different positions in the height direction of the first spring pin respectively. The free end of the first contact portion abuts against the fourth electrode, and the free end of the second contact portion abuts against the metal sheet.

5. A laminated patch piezoelectric buzzer as described in claim 1, characterized in that, The electrical connection structure is a side conductive connection part, which is disposed on the side of the first ceramic sheet and the second ceramic sheet, and is electrically connected to the fourth electrode and the first electrode respectively, so that the fourth electrode and the metal sheet are pre-connected through the side conductive connection part, and the first ceramic sheet and the second ceramic sheet are electrically connected in parallel.

6. A laminated patch piezoelectric buzzer as described in claim 5, characterized in that, The first spring pin has a first contact portion formed by bending the first spring pin, and the second spring pin has a third contact portion formed by bending the second spring pin; the length of the first contact portion is equal to the length of the third contact portion, and the bending angle of the first contact portion is smaller than the bending angle of the third contact portion, so that the free ends of the first contact portion and the free ends of the third contact portion are respectively located at different positions in the height direction, the free end of the first contact portion abuts against the fourth electrode, and the free end of the third contact portion abuts against the second electrode.

7. A laminated patch piezoelectric buzzer as described in claim 1, characterized in that, The housing includes a base and a cover. The cover has two mounting slots, and the first spring pin and the second spring pin are respectively assembled into the two mounting slots. The inner side wall of the cover also has a stepped surface and several slots. The base has a groove, several support protrusions and several locking blocks. Several support protrusions are distributed on the outer periphery of the groove. The metal sheet is placed on several support protrusions. When the cover and the base are assembled together, each locking block engages with the corresponding slot. At the same time, the stepped surface abuts against the edge of the metal sheet and together with each support protrusion, it limits and clamps the metal sheet, thereby fixing the metal sheet inside the housing.

8. A laminated patch piezoelectric buzzer as described in claim 7, characterized in that, Each of the mounting slots is provided with two insertion holes. The first spring pin and the second spring pin are each provided with a pin portion and two mounting portions. The two mounting portions are located on both sides of the pin portion and are respectively inserted into the two corresponding insertion holes and bent, thereby forming a fixed abutment with the inner side of the cover. The pin portion is exposed on the outer side of the cover for connection with external circuits.

9. A laminated patch piezoelectric buzzer as described in claim 7, characterized in that, A spring needle cavity is formed between the cover and the metal sheet. A first sound outlet is provided on the cover. The first sound outlet is located on the side of the cover and communicates with the spring needle cavity. When the piezoelectric buzzer is working, the metal sheet vibrates and produces sound. The sound is transmitted from the side of the piezoelectric buzzer through the first sound outlet.

10. A laminated patch piezoelectric buzzer as described in claim 7 or 9, characterized in that, The base is provided with a second sound outlet, which is located at the bottom or side of the groove and communicates with the groove; when the piezoelectric buzzer is working, the metal sheet vibrates and produces sound, which is transmitted through the second sound outlet.

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