CN114067773A

CN114067773A - Piezoelectric electroacoustic device and electronic apparatus

Info

Publication number: CN114067773A
Application number: CN202010757438.XA
Authority: CN
Inventors: 刘石磊; 辜磊; 黎椿键
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-07-31
Filing date: 2020-07-31
Publication date: 2022-02-18
Anticipated expiration: 2040-07-31
Also published as: CN114067773B; WO2022022561A1

Abstract

The application provides a piezoelectric electroacoustic device, which comprises a piezoelectric plate, a transmission part and a hard vibrating plate; the piezoelectric piece and the hard vibrating plate are stacked and arranged at intervals, the piezoelectric piece comprises a vibrating area, and the area of the hard vibrating plate is larger than that of the vibrating area; the transmission part is arranged between the center of the vibration area and the hard vibration plate and is fixedly connected with the hard vibration plate; the vibration area is used for vibrating to cause the transmission part to vibrate, so that the transmission part drives the hard vibration plate to vibrate. The application also provides an electronic device which comprises the shell and the piezoelectric electroacoustic device. The shell is provided with a sound outlet hole communicated with the inside and the outside of the shell; the piezoelectric electroacoustic device is arranged in the shell and can generate sound through the sound outlet hole. The scheme of this application can promote piezoelectric type electroacoustic device's low frequency performance.

Description

Piezoelectric electroacoustic device and electronic apparatus

Technical Field

The application relates to the field of audio of terminal equipment, in particular to a piezoelectric electroacoustic device and electronic equipment.

Background

Piezoelectric speakers have been widely used in electronic devices such as mobile phones. When the piezoelectric loudspeaker works, the vibration film can vibrate, and then air is pushed to vibrate and sound. In the conventional piezoelectric speaker, only a local area of the diaphragm can vibrate, so that the amount of air that the diaphragm can push is insufficient, which results in poor low-frequency performance of the conventional piezoelectric speaker.

Disclosure of Invention

The application provides a piezoelectric type electroacoustic device and electronic equipment including this piezoelectric type electroacoustic device, and the air quantity that this piezoelectric type electroacoustic device can promote is great, and the low frequency performance is better.

In a first aspect, the present application provides a piezoelectric electroacoustic device comprising a piezoelectric plate, a transmission portion, and a hard vibrating plate; the piezoelectric piece and the hard vibrating plate are stacked and arranged at intervals, the piezoelectric piece comprises a vibrating area, and the area of the hard vibrating plate is larger than that of the vibrating area; the transmission part is arranged between the center of the vibration area and the hard vibration plate and is fixedly connected with the hard vibration plate; the vibration area is used for vibrating to cause the transmission part to vibrate, so that the transmission part drives the hard vibration plate to vibrate.

In the present application, the piezoelectric sheet may be spaced apart from and substantially parallel to the hard vibration plate. The piezoelectric sheet can vibrate when energized, and the region where vibration occurs is referred to as a vibration region. The vibration region may be a vibration region of the piezoelectric sheet in any order of vibration mode. The center of the vibration region may be a position where the vibration region generates the maximum vibration displacement, or may be a region within a certain range around the maximum vibration displacement position. The hard vibrating plate can have a large modulus and is not easy to deform. One end of the transmission part may be in direct contact with the center of the vibration region or not.

In the present application, the piezoelectric sheet serves as a driving member, and the transmission portion can transmit vibration to drive the hard vibrating plate to vibrate (the hard vibrating plate corresponds to a piston, and the vibration corresponds to the reciprocating movement of the piston). The hard vibrating plate can push air to vibrate when vibrating. Because the area of the hard vibration plate is larger, and the area of the vibration area is smaller, the vibration with the larger area of the hard vibration plate can be driven through the vibration with the smaller area of the piezoelectric plate, and then more air vibration is pushed, so that the low-frequency performance of the piezoelectric electroacoustic device is better.

In one implementation of the first aspect, the area of the rigid vibrating plate is greater than or equal to the area of the piezoelectric sheet. Since the vibration region of the piezoelectric sheet is a partial region of the piezoelectric sheet, the design of the present embodiment can ensure that the area of the hard vibration plate is always larger than the area of the vibration region of the piezoelectric sheet, so that the hard vibration plate can perform piston vibration.

In one implementation of the first aspect, at least a portion of the vibration region overlaps with the hard vibration plate. The surface of the hard vibrating plate facing the piezoelectric sheet is used as a projection surface, and the orthographic projection of the vibration area on the projection surface is totally fallen on the hard vibrating plate, namely the hard vibrating plate can completely cover the vibration area. Alternatively, a part of the orthographic projection of the vibration region on the projection plane falls on the rigid vibration plate, and the other part falls outside the rigid vibration plate, that is, the rigid vibration plate may be displaced from the vibration region. The size of transmission portion can be reduced in this implementation's design, ensures that the transmission is accurate reliable, guarantees that the stereoplasm vibration board can be done piston vibration steadily.

In one implementation form of the first aspect, the modulus of the hard vibrating plate is greater than or equal to 1 GPa. The hard vibrating plate is hard, is not easy to bend and deform, and can stably vibrate the piston.

In one implementation form of the first aspect, the material of the hard vibrating plate is any one of a composite material composed of polymethacrylimide foam and aluminum, a composite material composed of polymethacrylimide foam and aluminum alloy, a composite material composed of polymethacrylimide foam and carbon fiber, a composite material composed of polymethacrylimide foam and glass fiber, a composite material composed of balsa wood and aluminum alloy, foamed aluminum, and foamed aluminum alloy. The hard vibrating plate made of the materials is light and hard, and has enough structural strength and good vibrating performance.

In one implementation manner of the first aspect, the transmission portion is an integrated component, that is, the transmission portion may be an integrated component independent from the piezoelectric sheet and the hard vibration plate, and may be assembled between the piezoelectric sheet and the hard vibration plate. The design can realize the modularized manufacture of the piezoelectric electroacoustic device, and is convenient for debugging and maintenance.

In one implementation manner of the first aspect, the transmission portion is integrally connected to the hard vibration plate, that is, the transmission portion is integrally formed with the hard vibration plate. The design can reduce the assembly difficulty and improve the reliability of the piezoelectric electroacoustic device.

In one implementation of the first aspect, the transmission part comprises a support and at least two transmission rods; the support comprises a force application end and a linkage end, and the force application end of the support is positioned between the hard vibration plate and the linkage end of the support; the at least two transmission rods are arranged in a different surface way; the transmission rod is fixedly connected with the force application end of the support and is obliquely arranged with the hard vibration plate; the transmission rod comprises a fulcrum end and a transmission end, the fulcrum end of the transmission rod and the transmission end of the transmission rod are arranged on two sides of the force application end of the support, and the distance between the force application end of the support and the fulcrum end of the transmission rod is smaller than the distance between the force application end of the support and the transmission end of the transmission rod; the transmission end of the transmission rod is fixedly connected with the hard vibration plate; the vibration area is used for vibrating to cause the linkage end of the support and the force application end of the support to vibrate, so that the force application end of the support drives the transmission end of the transmission rod to rotate around the fulcrum end of the transmission rod, and the transmission end of the transmission rod drives the hard vibration plate to vibrate.

In this implementation, the transmission part is a mechanism capable of performing a mechanical movement. The support is used for supporting and directly driving the transmission rod. The support may be approximately a ring-shaped structure surrounding one circle, such as a circular ring, a square ring, a special-shaped ring, and the like. The support can also be in other structures, such as a plate shape, a column shape or a block shape. The force application end and the linkage end are two opposite parts of the support, and the linkage end is close to the vibration area and can vibrate along with the vibration area, so that the force application end can vibrate along with the vibration area. The transmission rod is a rod-shaped component. Any two transmission rods are not parallel or intersected and can be regarded as a non-coplanar straight line. The transmission rod is fixedly connected with the force application end of the support, and the position, fixedly connected with the force application end, on the transmission rod is positioned between the fulcrum end and the transmission end of the transmission rod. The transmission rod and the support can form a lever mechanism, wherein the transmission end of the transmission rod is driven to rotate around the fulcrum end when the force application end vibrates. The transmission end can drive the hard vibration plate to vibrate, so that the hard vibration plate is made to vibrate by the piston. Because the force application end is closer to the fulcrum end, and the transmission end is farther from the fulcrum end, the vibration displacement (basically equal to the displacement of the vibration area) of the transmission rod at the force application end is smaller, and the vibration displacement of the transmission end of the transmission rod is larger, namely the scheme of the implementation mode can amplify the smaller vibration displacement of the vibration area into the larger vibration displacement of the hard vibration plate. The displacement amplification effect can further increase the pushed air quantity, thereby improving the low-frequency performance of the piezoelectric electroacoustic device.

In one implementation of the first aspect, the drive rod is provided as a straight generatrix of the single-sheet hyperboloid. The transmission rods can be used as straight generatrices of the single-sheet hyperboloid, and when the number of the transmission rods is large, all the transmission rods can approximately form the single-sheet hyperboloid. The design of the single-page double curved surface can well realize the mechanism motion between the support and the transmission rod, the transmission is reliable, and the hard vibrating plate can be ensured to reliably vibrate as the piston.

In one implementation of the first aspect, the transmission portion includes a rotation shaft and a transmission arm; the rotating shaft is arranged between the hard vibrating plate and the piezoelectric sheet; the transmission arm is rotatably connected with the rotating shaft and comprises a linkage end and a transmission end, the linkage end of the transmission arm and the transmission end of the transmission arm are positioned on two sides of the rotating shaft, the distance between the linkage end of the transmission arm and the rotating shaft is smaller than the distance between the transmission end of the transmission arm and the rotating shaft, and the transmission end of the transmission arm is fixedly connected with the hard vibrating plate; the vibration area is used for vibrating to cause the linkage end of the transmission arm to vibrate, so that the transmission end of the transmission arm rotates around the rotating shaft, and the transmission end of the transmission arm drives the hard vibration plate to vibrate.

In this implementation, the transmission part is a lever mechanism capable of performing a mechanical movement. The rotating shaft is fixedly arranged. The linkage end of the transmission arm can vibrate along with the vibration of the vibration area, so that the transmission end of the transmission arm rotates around the rotating shaft, and the hard vibration plate is driven to vibrate. Because the linkage end is closer to the rotating shaft, and the transmission end is farther from the rotating shaft, the scheme of the implementation mode can amplify the smaller vibration displacement of the vibration area into the larger vibration displacement of the hard vibration plate. The displacement amplification effect can further increase the pushed air quantity, thereby improving the low-frequency performance of the piezoelectric electroacoustic device. Moreover, the lever mechanism has simple structure, easy manufacture and assembly and better product reliability.

In one implementation form of the first aspect, the transmission arm includes a connection arm, and the connection arm connects the linkage end and the transmission end; the connecting arm is rotationally connected with the rotating shaft; the linkage end and the transmission end are arranged at included angles with the connecting arm. In this implementation, the transmission arm is all buckled with linkage end, transmission end and is connected, and the angle between transmission arm and the linkage end is not limited to being the right angle, and the angle between transmission arm and the transmission end is not limited to being the right angle. The transmission arm has simple structure and reliable transmission.

In one implementation of the first aspect, the piezoelectric electroacoustic device comprises an isolation diaphragm and a gasket; the isolation film is made of elastic material; the isolation film and the hard vibration plate are stacked, and the isolation film is positioned on one side of the hard vibration plate, which is far away from the piezoelectric sheet; the gasket is positioned between the isolating film and the piezoelectric sheet, is connected with the periphery of the isolating film and the periphery of the piezoelectric sheet and encloses a closed cavity with the isolating film and the piezoelectric sheet; the hard vibrating plate and the transmission part are arranged in the cavity.

In this implementation, the barrier film may be substantially flat and planar. The release film may be made of an elastomeric material including, but not limited to, Polyurethane (PU), Thermoplastic Polyurethanes (TPU), rubber, silicone, polyethylene terephthalate (PET), Polyetherimide (PEI), and the like. The periphery of the hard vibration plate is retracted inside the periphery of the isolation film. The isolating membrane can be driven by the hard vibrating plate to vibrate along with the vibration of the hard vibrating plate. The isolation film made of the elastic material has a good sealing effect, can well isolate the front cavity and the rear cavity of the piezoelectric electroacoustic device, and can prevent air flow between the front cavity and the rear cavity, so that the acoustic short circuit phenomenon is avoided. The isolation film can also play a role of hanging the hard vibration plate, and provides elastic restoring force for the hard vibration plate, so that the hard vibration plate can stably vibrate. In addition, the isolation film beyond the boundary of the hard vibration plate is used for pulling the hard vibration plate, and the structure is easy to manufacture, so that the scheme of the implementation mode has high manufacturability and is easy to fall on the ground.

In one embodiment of the first aspect, the region of the diaphragm between the washer and the hard vibrating plate is curved and arched. The curved and arched part can be called as a corrugated rim, the corrugated rim can reduce the vibration obstruction of the hard vibrating plate, so that the hard vibrating plate can basically keep a flat state without bending deformation in the vibrating process, the hard vibrating plate can be guaranteed to do piston motion, and the acoustic effect of the piezoelectric electroacoustic device can be guaranteed. In addition, the corrugated rim can suspend the hard vibrating plate and provide elastic restoring force, so that the hard vibrating plate can be kept at a set position.

In one implementation manner of the first aspect, the piezoelectric electroacoustic device includes a gasket, where the gasket is made of an elastic material, the gasket is located between the hard vibrating plate and the piezoelectric sheet, and the gasket connects a peripheral edge of the hard vibrating plate and a peripheral edge of the piezoelectric sheet, and encloses a closed cavity with the hard vibrating plate and the piezoelectric sheet; the transmission part is arranged in the cavity.

In this implementation, the material of the gasket includes, but is not limited to, ethylene vinyl acetate copolymer (EVA), rubber, silicone, foam (which may be with glue), and the like. These elastic materials are elastic and relatively soft. The gasket may be thin, for example 0.2mm to 1mm thick. The gasket may be a frame surrounding the perimeter. The gasket can play the effect of supporting, fixed stereoplasm vibration board, can also seal the space between stereoplasm vibration board and the piezoelectric plate to avoid gas leakage (if there is gas leakage, the sound wave just can't be according to the conduction of design requirement, can influence the sound production). Due to the elastic property of the gasket, the gasket can also provide elastic restoring force for the hard vibration plate and ensure that the periphery of the hard vibration plate has enough freedom, so that the hard vibration plate can vibrate fully and reliably.

In one implementation of the first aspect, a piezoelectric electroacoustic device comprises a diaphragm and a washer; the vibrating diaphragm and the piezoelectric sheets are arranged in a stacked mode, the piezoelectric sheets are located on one side or two sides of the vibrating diaphragm, and the peripheries of the piezoelectric sheets are retracted to the peripheries of the vibrating diaphragm; the gasket is positioned between the hard vibrating plate and the piezoelectric sheet, is connected with the periphery of the hard vibrating plate and the periphery of the vibrating plate and encloses a closed cavity with the hard vibrating plate and the vibrating plate; the transmission part is arranged in the cavity.

In this implementation, the diaphragm and the piezoelectric plate may be stacked and substantially attached (the thickness directions of the two are substantially the same). The piezoelectric sheet can be located between the vibrating diaphragm and the hard vibrating plate, or located on one side of the vibrating diaphragm departing from the hard vibrating plate, or both sides of the vibrating diaphragm are provided with the piezoelectric sheets. The periphery of the piezoelectric sheet is retracted into the periphery of the vibrating diaphragm, so that the constraint on the edge of the piezoelectric sheet is reduced, the vibration obstruction of the piezoelectric sheet is reduced, the vibration displacement of the piezoelectric sheet can be increased, and the vibration displacement of the hard vibrating plate is increased. The method is favorable for improving the air volume which can be pushed by the piezoelectric electroacoustic device, thereby further enhancing the low-frequency performance and the integral tone quality performance of the piezoelectric electroacoustic device. The gasket can play the role of supporting and fixing the hard vibrating plate, and can also seal the gap between the hard vibrating plate and the piezoelectric sheet so as to avoid air leakage. The gasket can also provide elastic restoring force to the hard vibrating plate and ensure that the periphery of the hard vibrating plate has enough freedom, so that the hard vibrating plate can vibrate fully and reliably.

In one implementation of the first aspect, the region of the diaphragm between the washer and the piezoelectric plate is curved and arched. The curved and arched part can be called as a corrugated rim, the corrugated rim enables the vibration of the piezoelectric patch to be blocked and reduced, the vibration displacement of the piezoelectric patch can be increased, and then the vibration displacement of the hard vibration plate is increased, which is beneficial to improving the air quantity which can be pushed by the piezoelectric electroacoustic device, and further enhances the low-frequency performance and the integral tone quality performance of the piezoelectric electroacoustic device. In addition, the folded ring can suspend the piezoelectric sheet and provide elastic restoring force, so that the piezoelectric sheet can be kept at a set position.

In one implementation manner of the first aspect, the diaphragm is provided with a through hole, and the through hole is communicated with the cavity. The through hole can communicate the back cavity of the piezoelectric electroacoustic device with the cavity between the vibrating diaphragm and the hard vibrating plate, which is equivalent to enlarging the back cavity of the piezoelectric electroacoustic device, can increase the low-frequency resonance of the piezoelectric electroacoustic device and improve the low-frequency performance of the piezoelectric electroacoustic device.

In one implementation form of the first aspect, the piezoelectric electroacoustic device comprises an isolation diaphragm, a gasket, and a diaphragm; the isolation film is made of elastic material; the isolation film, the hard vibration plate and the vibration film are sequentially stacked; the gasket is positioned between the isolating membrane and the piezoelectric sheet, is connected with the periphery of the isolating membrane and the periphery of the vibrating membrane and encloses a closed cavity with the isolating membrane and the vibrating membrane; the piezoelectric sheet is positioned on one side or two sides of the vibrating diaphragm; the hard vibrating plate and the transmission part are arranged in the cavity.

The realization mode is provided with the isolation film and the vibrating diaphragm simultaneously, so that the front cavity and the rear cavity of the piezoelectric electroacoustic device can be well isolated, and the air flow between the front cavity and the rear cavity is isolated, thereby avoiding the acoustic short circuit phenomenon; the function of hanging the hard vibrating plate can be achieved, and the elastic restoring force is provided for the hard vibrating plate, so that the hard vibrating plate can stably vibrate; within the periphery that enables the periphery of piezoelectric patches shrink in the vibrating diaphragm, reduce the restraint that the edge of piezoelectric patches received, reduce the vibration hindrance of piezoelectric patches for the vibration displacement of piezoelectric patches can increase, and then make the vibration displacement of stereoplasm vibration version increase, and this is favorable to promoting the air quantity that piezoelectric type electroacoustic device can promote, thereby further strengthens piezoelectric type electroacoustic device's low frequency performance and whole tone quality performance.

In one implementation manner of the first aspect, the piezoelectric electroacoustic device comprises a rear shell, wherein the rear shell is arranged on one side of the piezoelectric plate, which is far away from the hard vibrating plate; the back shell is connected with the periphery of the piezoelectric sheet and encloses a back cavity of the piezoelectric electroacoustic device with the piezoelectric sheet. The piezoelectric electroacoustic device of the implementation mode is provided with the back shell, and the back cavity of the piezoelectric electroacoustic device is the inner space of the piezoelectric electroacoustic device. The piezoelectric electroacoustic device is modularized, is easy to assemble with a shell of electronic equipment, and has low possibility of being affected by assembly in working reliability.

In one implementation manner of the first aspect, the piezoelectric electroacoustic device comprises a rear shell, and the rear shell is arranged on one side of the vibrating diaphragm, which is far away from the hard vibrating plate; the back shell is connected with the periphery of the vibrating diaphragm and encloses a back cavity of the piezoelectric electroacoustic device with the vibrating diaphragm. The piezoelectric electroacoustic device of the implementation mode is provided with the back shell, and the back cavity of the piezoelectric electroacoustic device is the inner space of the piezoelectric electroacoustic device. The piezoelectric electroacoustic device is modularized, is easy to assemble with a shell of electronic equipment, and has low possibility of being affected by assembly in working reliability.

In one implementation manner of the first aspect, the piezoelectric electroacoustic device comprises a front shell, wherein the front shell is arranged on one side, away from the piezoelectric sheet, of the hard vibrating plate; the front shell is connected with the periphery of the hard vibrating plate and encloses a front cavity of the piezoelectric electroacoustic device with the hard vibrating plate. The piezoelectric electroacoustic device of the implementation mode is provided with a front shell, and a front cavity of the piezoelectric electroacoustic device is an inner space of the piezoelectric electroacoustic device. The piezoelectric electroacoustic device is modularized, is easy to assemble with a shell of electronic equipment, and has low possibility of being affected by assembly in working reliability.

In one implementation manner of the first aspect, the piezoelectric electroacoustic device comprises a front shell, wherein the front shell is arranged on one side, away from the hard vibrating plate, of the isolation membrane; the front shell is connected with the periphery of the isolation membrane and encloses a front cavity of the piezoelectric electroacoustic device with the isolation membrane. The piezoelectric electroacoustic device of the implementation mode is provided with a front shell, and a front cavity of the piezoelectric electroacoustic device is an inner space of the piezoelectric electroacoustic device. The piezoelectric electroacoustic device is modularized, is easy to assemble with a shell of electronic equipment, and has low possibility of being affected by assembly in working reliability.

In one implementation of the first aspect, the vibration region is a vibration region of the piezoelectric sheet in a first-order mode. The vibration displacement of the vibration area under the first-order mode is large, so that the air volume pushed by the piezoelectric electroacoustic device is increased, and the low-frequency performance of the piezoelectric electroacoustic device is improved.

In a second aspect, the present application provides an electronic device comprising a housing and a piezoelectric electroacoustic device; the shell is provided with a sound outlet hole communicated with the inside and the outside of the shell; the piezoelectric electroacoustic device is arranged in the shell and can generate sound through the sound outlet hole. In the present application, the housing may be a single component or an assembly of several components. The front cavity of the piezoelectric electroacoustic device can correspond to the sound outlet hole, and sound waves generated by the piezoelectric electroacoustic device can be transmitted to the sound outlet hole from the front cavity and transmitted to the outside through the sound outlet hole. Because the low-frequency performance of the piezoelectric electroacoustic device in the electronic equipment is better, the bass quality of the electronic equipment is better, and the user experience is better.

In a third aspect, the present application provides an electronic device, comprising a housing and a piezoelectric electroacoustic device; the shell is provided with sound outlet holes communicated with the inside and the outside of the shell, and the piezoelectric electroacoustic device is arranged in the shell and can generate sound through the sound outlet holes; the inner side of the shell is provided with a first sealing cover part, and the first sealing cover part is positioned on one side of the hard vibration plate, which is far away from the piezoelectric sheet; the first cover part is connected with the periphery of the hard vibrating plate or the isolating membrane and encloses a front cavity of the piezoelectric electroacoustic device with the hard vibrating plate or the isolating membrane.

In this application, the piezoelectric type electroacoustic device of electronic equipment does not have preceding shell itself, and the cooperation of first closing cap portion in piezoelectric type electroacoustic device and the casing utilizes first closing cap portion as the preceding shell of self to form the front chamber. For the piezoelectric electroacoustic device without the isolation membrane, the first sealing cover part is connected with the periphery of the hard vibrating plate and encloses a front cavity with the hard vibrating plate. For a piezoelectric electroacoustic device having an isolation diaphragm, a first cap portion is connected to a periphery of the isolation diaphragm and encloses a front cavity with the isolation diaphragm. By using the first cover part as the front shell of the piezoelectric electroacoustic device, the design and the manufacture of the piezoelectric electroacoustic device can be simpler, and the manufacturing cost of the device can be reduced. In addition, the piezoelectric electroacoustic device does not comprise a front shell, so that the thickness is small, and the electronic equipment is favorably thinned.

In a fourth aspect, the present application provides an electronic device, comprising a housing and a piezoelectric electroacoustic device; the shell is provided with sound outlet holes communicated with the inside and the outside of the shell, and the piezoelectric electroacoustic device is arranged in the shell and can generate sound through the sound outlet holes; the inner side of the shell is provided with a second sealing cover part, and the second sealing cover part is positioned on one side of the piezoelectric sheet, which is far away from the hard vibration plate; the second sealing cover part is connected with the periphery of the piezoelectric sheet or the vibrating diaphragm and encloses the piezoelectric sheet or the vibrating diaphragm to form a back cavity of the piezoelectric electroacoustic device.

In this application, the piezoelectric type electroacoustic device of electronic equipment does not have the backshell by itself, and the cooperation of second closing cap portion in piezoelectric type electroacoustic device and the casing utilizes the backshell of second closing cap portion as self to form the back chamber. For the piezoelectric electroacoustic device without the vibrating diaphragm, the second sealing cover part is connected with the periphery of the piezoelectric sheet and encloses a back cavity with the piezoelectric sheet. For the piezoelectric electroacoustic device with the vibrating diaphragm, the second cover sealing part is connected with the periphery of the vibrating diaphragm and encloses a back cavity with the vibrating diaphragm. By using the second cover portion as the rear shell of the piezoelectric electroacoustic device, the design and manufacture of the piezoelectric electroacoustic device can be simplified, and the manufacturing cost of the device can be reduced. In addition, the piezoelectric electroacoustic device does not comprise a rear shell, so that the thickness is small, and the electronic equipment is favorably thinned.

Drawings

Fig. 1 is a schematic assembly structure diagram of an electronic device according to a first embodiment;

FIG. 2 is an exploded schematic view of the electronic device of FIG. 1;

FIG. 3 is a schematic perspective view of a middle frame of the electronic device in FIG. 2 from another perspective;

FIG. 4 is a schematic view of a portion of the enlarged structure at C in FIG. 3;

FIG. 5 is a schematic view of a portion of the enlarged structure at B in FIG. 2;

FIG. 6 is a schematic diagram of an assembled piezoelectric electroacoustic device of the electronic device of FIG. 2;

FIG. 7 is a schematic diagram of a D-D cross-sectional structure of the piezoelectric electroacoustic device of FIG. 6;

FIG. 8 is a schematic diagram of an exploded structure of the piezoelectric electroacoustic device of FIG. 6;

FIG. 9 is a schematic top view of the vibration region of the piezoelectric plate of the piezoelectric electroacoustic device of FIG. 8 in the first-order mode;

FIG. 10 is a cross-sectional structural view of the vibrating region of the piezoelectric sheet of FIG. 9;

FIG. 11 is a schematic view of the assembly of the vibration region of the piezoelectric sheet and the transmission part in FIG. 10;

FIG. 12 is a schematic diagram showing the assembly relationship among the vibration region, the transmission part and the hard vibration plate of the piezoelectric plate in FIG. 11;

FIG. 13 is a schematic cross-sectional A-A diagram of the electronic device of FIG. 1;

FIG. 14 is an enlarged partial schematic view of FIG. 13 at E;

fig. 15 is a schematic view of an assembled structure of the piezoelectric electroacoustic device according to the second embodiment;

FIG. 16 is a schematic cross-sectional view of the piezoelectric electroacoustic device of FIG. 15;

fig. 17 is a schematic view showing an assembly relationship between the piezoelectric electroacoustic device and the casing of the electronic apparatus according to the second embodiment;

FIG. 18 is a schematic sectional view showing a piezoelectric electroacoustic device according to a third embodiment;

fig. 19 is a schematic view showing an assembled relationship between the piezoelectric electroacoustic device and the casing of the electronic apparatus in the third embodiment;

FIG. 20 is a schematic sectional view showing a piezoelectric electroacoustic device according to a fourth embodiment;

FIG. 21 is a schematic sectional view showing the piezoelectric electroacoustic device according to the fifth embodiment;

FIG. 22 is an exploded view of the piezoelectric electroacoustic device according to the fifth embodiment;

FIG. 23 is a schematic view showing an assembled relationship between the piezoelectric electroacoustic device of the fifth embodiment and a casing of an electronic apparatus;

FIG. 24 is a schematic sectional view showing the piezoelectric electroacoustic device of the sixth embodiment;

FIG. 25 is a schematic sectional view of a piezoelectric electroacoustic device according to a seventh embodiment;

FIG. 26 is a schematic sectional view of a piezoelectric electroacoustic device according to an eighth embodiment;

FIG. 27 is a schematic exploded view of a piezoelectric electroacoustic device according to the ninth embodiment;

FIG. 28 is a schematic view showing an assembled relationship between the piezoelectric electroacoustic device of the ninth embodiment and a casing of an electronic apparatus;

fig. 29 is an exploded view schematically illustrating a piezoelectric electroacoustic device according to a tenth embodiment;

FIG. 30 is a schematic sectional view of a piezoelectric electroacoustic device according to an eleventh embodiment;

FIG. 31 is an exploded view of a piezoelectric electroacoustic device according to an eleventh embodiment;

FIG. 32 is an exploded view of an electronic apparatus according to a twelfth embodiment;

FIG. 33 is a schematic view of an assembled structure of the piezoelectric electroacoustic device of the electronic apparatus of FIG. 32;

FIG. 34 is a schematic cross-sectional F-F view of the piezoelectric electroacoustic device of FIG. 33;

FIG. 35 is an exploded view of the piezoelectric electroacoustic device of FIG. 33;

FIG. 36 is a schematic view showing an assembled relationship between the piezoelectric electroacoustic device of the twelfth embodiment and a casing of an electronic apparatus;

FIG. 37 is a schematic perspective view of a middle frame in the thirteenth embodiment;

FIG. 38 is a schematic view showing an assembled structure of a piezoelectric electroacoustic device according to a thirteenth embodiment;

FIG. 39 is a schematic sectional view G-G of the piezoelectric electroacoustic device of FIG. 38;

FIG. 40 is a schematic exploded view of a piezoelectric electroacoustic device according to a thirteenth embodiment;

FIG. 41 is a schematic perspective view of the front housing of the piezoelectric electroacoustic device of FIG. 40;

FIG. 42 is a schematic view showing an assembled relationship between the piezoelectric electroacoustic device of the thirteenth embodiment and a casing of an electronic apparatus;

FIG. 43 is a schematic view showing an assembled structure of the piezoelectric electroacoustic device according to the fourteenth embodiment;

FIG. 44 is a schematic view of the cross-sectional H-H structure of the piezoelectric electroacoustic device of FIG. 43;

FIG. 45 is a schematic view of an exploded structure of the piezoelectric electroacoustic device of FIG. 43;

FIG. 46 is a schematic view showing an assembled relationship between the piezoelectric electroacoustic device of the fourteenth embodiment and a casing of an electronic apparatus;

FIG. 47 is a schematic view showing an assembled structure of the piezoelectric electroacoustic device according to the fourteenth embodiment;

FIG. 48 is a schematic sectional I-I diagram of the piezoelectric electroacoustic device of FIG. 47;

FIG. 49 is a schematic view of an exploded structure of the piezoelectric electroacoustic device of FIG. 47;

FIG. 50 is a schematic view of an assembled structure of a transmission portion of the piezoelectric electroacoustic device of FIG. 49;

FIG. 51 is a schematic view of the drive link of the drive section of FIG. 50 approximated as a straight generatrix of a single-sheet hyperboloid;

FIG. 52 is a diagram showing an assembly relationship of the transmission portion, the hard oscillating plate, the diaphragm, and the piezoelectric plate in the fourteenth embodiment;

FIG. 53(a) is a simplified schematic view showing a transmission section in a fourteenth embodiment in a balanced position;

FIG. 53(b) is a simplified schematic view showing a power transmitting portion in a vibration position in the fourteenth embodiment;

FIG. 53(c) is a simplified schematic view showing a power transmitting portion in another vibration position in the fourteenth embodiment;

FIG. 54 is a schematic view showing calculation of vibrational displacement of the drive rod in the fourteenth embodiment;

fig. 55 is an assembly structure diagram of the piezoelectric electroacoustic device according to the fifteenth embodiment;

FIG. 56 is an exploded view of the piezoelectric electroacoustic device of FIG. 55;

FIG. 57 is an exploded view of the piezoelectric electroacoustic device of FIG. 55;

FIG. 58 is a schematic view of the piezoelectric electroacoustic device of FIG. 57 in an assembled configuration of the transmission part;

fig. 59 shows a comparison of low-frequency performance curves of the piezoelectric electroacoustic device of the embodiment of the present application and the conventional piezoelectric electroacoustic device.

Detailed Description

The following embodiments of the present application provide an electronic device, which includes but is not limited to a mobile phone, a tablet computer, a notebook computer, an electronic reader, a wearable device (such as a wireless headset, a smart garment, a smart watch), and the like. The following description will be given taking the electronic device as a mobile phone as an example.

As shown in fig. 1 and 2, the electronic device 10 of the first embodiment may be a tablet phone. The bar phone is a phone with a folding screen (or called a foldable phone or a foldable phone), which can not be folded and unfolded and always keeps a flat shape. In other embodiments, the electronic device may also be a folding screen handset.

As shown in fig. 1 and 2, the electronic device 10 may include a display screen 11, a middle frame 12, a piezoelectric electroacoustic device 20, and a rear cover 13, where the middle frame 12 and the rear cover 13 both belong to a housing of the electronic device 10.

The display screen 11 may be a flat 2D screen, or may be a curved screen such as a 2.5D screen (the display screen 11 has a flat middle portion and curved surface portions connected to opposite sides of the middle portion) or a 3D screen (the middle portion is also made into a curved surface on the basis of the 2.5D screen). The display screen 11 may include a cover plate and a display panel, the cover plate being laminated with the display panel. The cover plate is used for protecting the display panel, and the display panel is used for displaying images. The display panel includes, but is not limited to, a liquid crystal display panel or an organic light emitting diode display panel. A touch unit can be integrated in the cover plate, namely the cover plate has a touch function; alternatively, the display panel may have a touch unit built therein, i.e., the display panel has both display and touch functions. The electronic device 10 in the first embodiment has a display 11, which is merely an example. In other embodiments, the electronic device may not have a display screen 11.

The middle frame 12 serves as a main structural bearing member of the electronic device 10, and is used for bearing the display screen 11 and the piezoelectric electroacoustic device 20. As shown in fig. 2, one side of the middle frame 12 may be formed with a mounting groove 12a, and the display screen 11 is mounted in the mounting groove 12 a. As shown in fig. 3, a mounting groove 12c may be formed on a side of the middle frame 12 facing away from the display screen 11, and the mounting groove 12c is used for accommodating the piezoelectric electroacoustic device 20.

As shown in fig. 3 and 4, a first capping portion 121 may be disposed in the mounting groove 12 c. The first capping portion 121 may include, for example, a first wall 121a, a second wall 121b, and a third wall 121C connected in sequence, and the first wall 121a, the second wall 121b, and the third wall 121C may enclose an approximately C-shaped open enclosure wall structure. The first wall 121a, the second wall 121b and the third wall 121c are all protruded from the bottom 12d of the mounting groove 12c, and the first wall 121a and the third wall 121c at both ends are connected to the side 12e of the mounting groove 12c (the side 12e surrounds the display 11, and the normal of the side 12e may be parallel to the display 11). The first cap portion 121 is used to connect with the piezoelectric electroacoustic device 20, and may serve as a front case of the piezoelectric electroacoustic device 20 (to be described later).

As shown in fig. 2 and 4, a sound outlet hole 12b may be formed in the middle frame 12, and the sound outlet hole 12b penetrates through a side surface 12e of the mounting groove 12c to communicate the mounting groove 12c with the outside. The sound outlet hole 12b may include a plurality of small holes distributed in an array, or may be a single large hole. In the latter case, a dust screen may be installed in the sound output hole 12 b. The second wall 121b may be opposite to the sound outlet 12b, and the first wall 121a and the third wall 121c may be respectively located at both sides of the sound outlet 12 b. The sound outlet hole 12b is for sound generated by the piezoelectric electroacoustic device 20 to be discharged (to be described later).

In the first embodiment, the sound outlet hole 12b is formed in the side surface 12e of the middle frame 12, which is merely an example. In other embodiments, the sound outlet hole 12b may be formed at other suitable positions according to the product requirement, for example, on the rear cover 13. The structure of the first cover 121 can also be adjusted according to the position of the sound outlet 12b, for example, when the sound outlet 12b is opened on the rear housing 12, the first cover 121 can keep a space with the side 12e of the mounting groove 12c and form a surrounding wall structure.

As shown in fig. 2, the rear cover 13 is mounted on the middle frame 12 on a side of the middle frame 12 facing away from the display screen 11. As shown in fig. 2 and 3, the rear cover 13 may close the mounting groove 12c, thereby enclosing the piezoelectric electroacoustic device 20 in the mounting groove 12 c. The structure of the rear cover 13 shown in fig. 2 is merely an illustration, and the embodiment of the present application is not limited thereto.

As shown in fig. 2 and 5, the inner surface 13a of the rear cover 13 facing the middle frame 12 may be provided with a second cover portion 131. The second capping portion 131 may form a closed enclosure structure around the circumference, for example, the second capping portion 131 in fig. 5 may include four walls 131a connected in series at the head, and the four walls 131a may approximately form a box. The second cover portion 131 is used to connect with the piezoelectric electroacoustic device 20, and may serve as a back case of the piezoelectric electroacoustic device 20 (to be described later). In other embodiments, the second capping portion 131 may form an open fence structure (similar to a C-shape).

As shown in fig. 6, 7 and 8 in conjunction, the piezoelectric electroacoustic device 20 may include a piezoelectric sheet 23, an actuator 24, a hard vibrating plate 21 and a washer 22. The piezoelectric electroacoustic device 20 may be a speaker or a receiver.

The piezoelectric sheet 23 may have a flat plate shape, such as a square plate shape. The material of the piezoelectric sheet 23 includes, but is not limited to, piezoelectric ceramics such as lead zirconate titanate, lithium niobate, and lithium tantalate, piezoelectric crystals such as quartz, and piezoelectric polymers such as polyvinylidene fluoride (PVDF). In terms of construction, the piezoelectric sheet 23 includes, but is not limited to, single, multi-layer co-polarization direction stack, multi-layer square polarization direction stack, and the like.

The piezoelectric electroacoustic device 20 may be electrically connected to audio circuitry in the electronic device 10. The audio circuit may include, for example, a codec, an intelligent power amplifier, etc., where the codec and the intelligent power amplifier process the signal and output the signal to the piezoelectric electroacoustic device 20 to sound the piezoelectric electroacoustic device 20. The piezoelectric sheet 23 has an electrode, and can receive a signal output by the audio circuit. The signal can drive the piezoelectric sheet to deform along the direction of the plane of the piezoelectric sheet. Since the piezoelectric sheet 23 can be fixed to the second cover portion 131 (to be described later), the piezoelectric sheet 23 is constrained by the second cover portion 131, so that deformation of the piezoelectric sheet 23 in the planar direction is converted into bending vibration substantially in the thickness direction of the piezoelectric sheet 23. The bending vibration pushes the air to vibrate, thereby producing sound. The piezoelectric sheet 23 can operate in different vibration modes according to different signals (e.g., signals of different frequencies). The vibration mode refers to the vibration characteristic of the structure, and is mainly characterized by the natural frequency. The natural frequency is related to the size and shape of the piezoelectric sheet 23, with larger sizes giving lower natural frequencies. The vibrational modes also include other characteristics, which may be modes corresponding to the natural frequencies. The mode shape, i.e., the form of vibration, may include a position where bending vibration is generated, a direction of the bending vibration, a vibration displacement (on the order of micrometers, e.g., between several tens micrometers and two-three hundred micrometers) of the bending vibration, and the like.

The natural frequency and the mode shape can be different according to different vibration modes. For example, the piezoelectric sheet 23 may have a first-order mode, a second-order mode, a third-order mode, and the like (the vibration modes of other orders than the first-order mode may be collectively referred to as the high-order mode), wherein the natural frequency of the first-order mode is the smallest, and may be, for example, 500Hz to 3000 Hz. In the embodiment of the present application, the region of bending vibration may be referred to as a vibration region. The center of the vibration region may be a position where the vibration region generates the maximum vibration displacement, or may be a region within a certain range (the range is determined as required) around the position where the maximum vibration displacement occurs. The vibration displacement of the vibration region of the first-order mode is large.

Fig. 9 and 10 show bending vibration of the piezoelectric sheet 23 in a first-order mode, and fig. 9 and 10 cut out only a partial region of the piezoelectric sheet 23 in order to clearly illustrate a vibration region. As shown in fig. 9 and 10, in the first-order mode, the vibration region 23a of the piezoelectric sheet 23 may be approximately a circular region centered on the geometric center 23c of the piezoelectric sheet 23, and the geometric center 23c is substantially the center of the vibration region 23 a. Fig. 10 illustrates a schematic view of the bending vibration of the vibration region 23a in one direction (e.g., upward in the view of fig. 10). As shown in fig. 10, the cross section of the vibration region 23a may have a contour shape of an approximately ellipsoid or a water droplet. The vibration displacement (the distance from the equilibrium position) may be different at each position in the vibration region 23a, for example, the vibration displacement L0 is maximum substantially at the geometric center 23c, the vibration displacement L1 is smaller at a position slightly distant from the geometric center 23c, and the vibration displacement L2 is smaller at a position more distant from the geometric center 23 c. The vibration displacement L0 is also the maximum vibration displacement of the piezoelectric sheet 23 in all vibration modes.

In the higher-order mode, the vibration region of the piezoelectric sheet 23 may be one or more, and the vibration directions of the respective vibration regions may not be completely the same at the same time. For example, in the second-order mode, the piezoelectric sheet 23 may have two vibration regions, and the vibration directions of the two vibration regions may be opposite at the same time. Or in the third-order mode, the piezoelectric sheet 23 may have four vibration regions, where the vibration directions of two vibration regions may be the same, the vibration directions of the other two vibration regions may be the same, and the vibration direction of the latter vibration region may be opposite to the vibration direction of the former vibration region. As described above, the maximum vibration displacement in each of the other vibration modes is smaller than the vibration displacement L0 in the first-order mode.

The transmission portion 24 may be approximately rod-shaped, column-shaped, block-shaped, etc., for example, the transmission portion 24 shown in fig. 8 is square block-shaped. As shown in fig. 11, one end (hereinafter referred to as a link end 242) of the transmission portion 24 is fixedly connected to the vibration region 23 a. The coupling end 242 overlaps the vibration region 23a, that is, the projection of the coupling end 242 in the thickness direction of the piezoelectric sheet 23 may partially or entirely fall within the vibration region 23a (i.e., the vibration region 23a when the piezoelectric sheet 23 is not vibrated). The linkage end 242 may be located near a center of the vibration region 23a (i.e., the geometric center 23c of the piezoelectric sheet 23), for example, the geometric center of the linkage end 242 may substantially coincide with the center of the circle.

In other embodiments, the linking end 242 may be connected to any vibration region of the piezoelectric sheet 23 in the higher-order mode, and the orthographic projection of the linking end 242 on the surface of the piezoelectric sheet 23 facing the hard vibration plate 21 at least partially overlaps the center of the vibration region.

As shown in fig. 11 and 8, an end of the transmission portion 24 opposite to the interlocking end 242 may be referred to as a transmission end 241, and the transmission end 241 is fixedly connected to the hard vibration plate 21. Thus, when the vibration region 23a vibrates, the coupling end 242 in turn vibrates the driving end 241, and the driving end 241 transmits the vibration to the hard vibration plate 21, so that the hard vibration plate 21 vibrates.

In the first embodiment, the transmission portion 24 may be an integrated component independent from the piezoelectric sheet 23 and the hard vibrating plate 21, and the transmission portion 24 may be assembled between the piezoelectric sheet 23 and the hard vibrating plate 21 and connected to the piezoelectric sheet 23 and the hard vibrating plate 21, respectively. The design can realize the modularized manufacture of the piezoelectric electroacoustic device 20, and is convenient for debugging and maintenance. In other embodiments, the transmission portion 24 may be integrated with the rigid vibration plate 21 or the piezoelectric plate 23. For example, the transmission portion 24 may be integrally connected to the rigid vibration plate 21, such transmission portion 24 may be a protrusion protruding from the surface of the rigid vibration plate 21, the protrusion may be integrally formed with the rigid vibration plate 21, and the top end (i.e., the linkage end 242) of the protrusion is connected to the piezoelectric sheet 23 by assembling. The integrated design can reduce the assembly difficulty and improve the reliability of the piezoelectric electroacoustic device 20.

In one embodiment, the material of the transmission portion 24 includes, but is not limited to, metal, nonmetal, and composite material. There may be only one transmission 24. In other embodiments, there may be at least two transmission portions 24, and each transmission portion 24 may be located in the vibration region 23a (for the first-order mode); or each transmission 24 may be located in a different vibration region (for higher order modes) and at the same time each transmission 24 has a substantially uniform vibration direction.

As shown in fig. 6, the hard vibration plate 21 may have a flat plate shape, for example, a square flat plate shape. The hard vibration plate 21 may have a large modulus and is not easily deformed. The modulus of the hard vibration plate 21 may be greater than or equal to 1GPa, such as 5GPa, 20GPa, or 30 GPa. The thickness of the hard diaphragm 21 may be, for example, 0.2mm to 1 mm.

The material of the hard diaphragm 21 may be, for example, a composite material of polymethacrylimide foam (PMI) and aluminum (or aluminum alloy), a composite material of PMI and carbon fiber, or a composite material of PMI and glass fiber. Wherein the PMI in the composite material may be sandwiched between two layers of aluminum or (or two layers of aluminum alloy), or may be sandwiched between two layers of carbon fiber, or may be sandwiched between two layers of glass fiber. Alternatively, the material of the hard vibration plate 21 may be, for example, a composite material of balsa wood and aluminum (or an aluminum alloy), and the balsa wood in the composite material may be sandwiched between two layers of aluminum (or two layers of aluminum alloy). Alternatively, the material of the hard vibration plate 21 may be, for example, foamed aluminum or foamed aluminum alloy. The hard vibration plate 21 made of the above materials is light and hard, and the hard vibration plate 21 has sufficient structural strength and good vibration performance. Of course, the material and internal configuration of the hard vibration plate 21 are not limited to those described above.

As shown in fig. 7, the hard vibration plate 21 and the piezoelectric sheet 23 are separated by a transmission portion 24. The hard vibration plate 21 and the piezoelectric sheet 23 are arranged in a spaced and stacked arrangement, and the "spaced and stacked" means that they are spaced apart from each other and may be substantially parallel to each other. The hard vibrating plate 21 may substantially overlap the piezoelectric sheet 23 in the thickness direction of the hard vibrating plate 21, and the areas of the two may be substantially equal. The area of the hard vibrating plate 21 and the area of the piezoelectric sheet 23 are both the areas of the surfaces perpendicular to the thickness direction. The same applies below.

In other embodiments, on the premise that the area of the hard vibration plate 21 is ensured to be larger than the area of the vibration region 23a, the hard vibration plate 21 may be arranged in a staggered manner with respect to the piezoelectric sheet 23, and the area size relationship between the two may not be limited, for example, the area of the hard vibration plate 21 may be larger than or equal to the area of the piezoelectric sheet 23.

In the first embodiment, the vibration region 23a is a partial region of the piezoelectric sheet 23, and the area of the hard vibration plate 21 is larger than that of the vibration region 23 a. For example, the area of the hard vibration plate 21 may be approximately twice the area of the vibration region 23 a. The hard vibration plate 21 may completely cover the vibration region 23 a. "completely covering" may include the following meanings: as shown in fig. 12, the front surface 21a of the hard vibrating plate 21 facing the piezoelectric sheet 23 is used as a projection surface, the orthographic projection of the vibrating area 23a on the projection surface is totally within the projection surface, and all boundaries of the orthographic projection surface are separated from corresponding boundaries of the projection surface. Alternatively, a part of the boundary of the orthogonal projection of the vibration region 23a on the projection plane coincides with the corresponding boundary of the projection plane, and another part of the boundary falls inside the projection plane, the other part of the boundary being spaced apart from the corresponding boundary of the projection plane.

In other embodiments, referring to fig. 12, when the linkage end 242 is connected to another vibration region (hereinafter referred to as another vibration region) of the piezoelectric sheet 23 in the higher-order mode, the hard vibration plate 21 may completely cover the vibration region, and the meaning of "completely cover" is the same as above.

Alternatively, in another embodiment, on the premise that the area of the hard vibration plate 21 is ensured to be larger than the area of the vibration region 23a or the area of the other vibration region, the hard vibration plate 21 may be displaced from the vibration region 23a or the other vibration region, where the displacement means that the two are partially overlapped in the thickness direction of the hard vibration plate 21, that is, the partial region of the vibration region 23a or the partial region of the other vibration region is overlapped with the hard vibration plate 21, or the whole of the vibration region 23a or the whole of the other vibration region is overlapped with the hard vibration plate 21.

In the present embodiment, the piezoelectric sheet 23 serves as a driving member, and the transmission portion 24 can transmit vibration to drive the hard vibration plate 21 to vibrate (the hard vibration plate 21 corresponds to a piston, and the vibration corresponds to the reciprocating movement of the piston). The hard vibration plate 21 can push air to vibrate when vibrating. Since the area of the hard vibration plate 21 is larger, and the areas of the vibration region 23a and other vibration regions are smaller, the vibration of the smaller area of the piezoelectric sheet 23 can drive the vibration of the larger area of the hard vibration plate 21, thereby pushing more air to vibrate. That is, the design of the embodiment of the present application makes the effective vibration area of the piezoelectric electroacoustic device 20 larger (for example, the effective vibration area of the piezoelectric electroacoustic device 20 may be substantially twice as large as that of a conventional piezoelectric electroacoustic device), so that the amount of air that the piezoelectric electroacoustic device 20 can push is increased.

Further, the larger the vibration displacement of the hard vibration plate 21, the larger the amount of air that can be pushed by the hard vibration plate 21. When the coupling end 242 is located substantially at the center of the vibration region 23a, the vibration displacement of the hard vibration plate 21 is large, and therefore the amount of air that can be pushed by the hard vibration plate 21 is also large.

As shown in fig. 7 and 8, the gasket 22 may be a frame, such as a square frame, that surrounds a circumference. The gasket 22 connects the hard vibrating plate 21 and the piezoelectric sheet 23. The gasket 22 may be located at the edges of the rigid vibrating plate 21 and the piezoelectric sheet 23, for example, substantially aligned with the edges of the rigid vibrating plate 21 and the piezoelectric sheet 23. The gasket 22, the hard vibrating plate 21 and the piezoelectric sheet 23 enclose a closed cavity 20a (see fig. 7).

The gasket 22 may be made of an elastic material such as ethylene vinyl acetate copolymer (EVA), rubber, silicone, foam (which may be rubberized), or the like. These elastic materials are elastic and relatively soft. The gasket 22 may be thin, for example, 0.2mm to 1mm thick.

As shown in fig. 7 and 8, the gasket 22 may serve to support and fix the hard vibrating plate 21, and may also seal the gap between the hard vibrating plate 21 and the piezoelectric plate 23 to prevent air leakage (if air leakage exists, sound waves may not be conducted according to design requirements, and sound production may be affected). The gasket 22 may also provide an elastic restoring force to the hard vibration plate 21 due to the elastic characteristic of the gasket 22, and ensure a sufficient degree of freedom of the peripheral edge of the hard vibration plate 21, enabling the hard vibration plate 21 to vibrate sufficiently and reliably.

Fig. 13 and 14 are sectional views illustrating an assembly relationship of the middle frame 12, the piezoelectric electroacoustic device 20 and the rear cover 13, in which fig. 13 is a sectional structural view a-a of the electronic apparatus in fig. 1, and fig. 14 is a partially enlarged structural view at E in fig. 13. As shown in fig. 14, the piezoelectric electroacoustic device 20 may be mounted between the first cover part 121 of the middle frame 12 and the second cover part 131 of the rear cover 13.

The hard vibrating plate 21 of the piezoelectric electroacoustic device 20 may be connected to the first cap section 121, and for example, fig. 14 shows the connection relationship of the hard vibrating plate 21 to the second wall 121b of the first cap section 121. In practice, the hard vibration plate 21 may be connected to each of the first wall 121a, the second wall 121b, and the third wall 121c of the first capping portion 121, and each of the first wall 121a, the second wall 121b, and the third wall 121c may be connected to an edge of the hard vibration plate 21. Including but not limited to adhesive, welding, snapping, etc. The hard vibrating plate 21 can abut against the side 12e of the middle frame 12. The hard vibration plate 21 is spaced from the bottom surface 12d of the mounting groove 12 c. The space may serve as a front cavity of the piezoelectric electroacoustic device 20, and thus the first cap portion 121 may serve as a front case of the piezoelectric electroacoustic device 20.

The piezoelectric sheet 23 of the piezoelectric electroacoustic device 20 may be connected to the second cover portion 131, for example, the connection relationship between the piezoelectric sheet 23 and one of the walls 131a of the second cover portion 131 is shown in fig. 14. In practice, the edge of the piezoelectric sheet 23 may be connected to each of the four walls 131a of the second cover portion 131. Including but not limited to adhesive, welding, snapping, etc. The electric plate 23 can abut against the side 12e of the middle frame 12. The piezoelectric sheet 23 is spaced from the inner surface 13a of the rear cover 13. The space may serve as a rear cavity of the piezoelectric electroacoustic device 20, and thus the second cover portion 131 may serve as a rear case of the piezoelectric electroacoustic device 20.

In the present embodiment, the piezoelectric electroacoustic device 20 may be staggered with respect to the sound hole 12 b. For example, as shown in fig. 14, the sound output hole 12b may be located between the hard diaphragm 21 and the bottom surface 12 d. Alternatively, in the vertical direction in the perspective of fig. 14, the upper surface of the hard vibrating plate 21 may be substantially flush with the lower side hole wall of the sound outlet hole 12 b. The above-described design enables the sound waves generated by the vibration of the hard vibrating plate 21 to be transmitted to the outside of the electronic device 10 through the sound outlet holes 12 b. The human ear receives the sound wave to form a hearing sense.

In the first embodiment, by designing the vibration structure of the piezoelectric sheet 23, the transmission portion 24 and the hard vibration plate 21, the originally small-area vibration of the piezoelectric sheet 23 can be amplified to the large-area vibration of the hard vibration plate 21, so that the effective vibration area of the piezoelectric electroacoustic device 20 is larger than that of a conventional piezoelectric electroacoustic device. With the increased effective vibration area, the amount of air that the piezoelectric electroacoustic device 20 can push is also increased (especially when the linkage end 242 is located substantially at the center of the vibration region 23a), which allows the piezoelectric electroacoustic device 20 to have higher low-frequency sensitivity and better low-frequency performance, so that the output sound contains more bass portions.

In addition, the high-frequency sensitivity of the conventional piezoelectric electroacoustic device is too high, but the low-frequency sensitivity is low, so that the frequency response of three frequency bands of high frequency, medium frequency and low frequency is unbalanced. Because the low-frequency sensitivity of the piezoelectric electroacoustic device 20 is improved, the problem of unbalanced frequency response can be reduced or overcome, so that the frequency response of the high-frequency, medium-frequency and low-frequency bands can be well balanced, and the piezoelectric electroacoustic device 20 has better overall tone quality performance.

In addition, by using the structures of the middle frame 12 and the rear cover 13 as the front shell and the rear shell of the piezoelectric electroacoustic device 20, the design and manufacture of the piezoelectric electroacoustic device 20 can be simplified, and the device manufacturing cost can be reduced. In addition, the piezoelectric electroacoustic device 20 does not include a front case and a rear case, and thus has a small thickness, which is advantageous for reducing the thickness of the electronic device 10.

Fig. 15 and 16 show the structure of the piezoelectric electroacoustic device 20 according to the second embodiment, wherein fig. 16 is a schematic cross-sectional structure diagram of the piezoelectric electroacoustic device 20 according to the second embodiment, and the cross section of the piezoelectric electroacoustic device 20 is the same as the cross section D-D in fig. 6, so that D-D is still used as a mark of the cross section in fig. 16. The same applies below.

As shown in fig. 15 and 16, in the second embodiment, the piezoelectric electroacoustic device 20 may further include an isolation diaphragm 25. The separator 25 may be substantially flat sheet-like, such as a square sheet. The separator 25 may be made of an elastic material, including but not limited to Polyurethane (PU), Thermoplastic Polyurethane (TPU), rubber, silicone, polyethylene terephthalate (PET), Polyetherimide (PEI), and the like. The elastic material has elasticity and is relatively soft.

As shown in fig. 15 and 16, the isolation diaphragm 25 and the piezoelectric sheet 23 are respectively located on opposite sides of the gasket 22, and the peripheral edge of the isolation diaphragm 25 is connected (e.g., bonded) to the gasket 22. The isolation film 25, the gasket 22 and the piezoelectric sheet 23 enclose a closed cavity 20 b. The difference between the second embodiment and the first embodiment is that the hard vibration plate 21 in the second embodiment is not connected to the surface of the gasket 22 away from the piezoelectric sheet 23, but is connected to (e.g., adhered to) the surface of the isolation film 25 facing the piezoelectric sheet 23. The hard vibrating plate 21 is located in the cavity 20b, and the boundaries of the hard vibrating plate 21 and the corresponding boundaries of the gasket 22 can be kept at intervals, that is, the periphery of the hard vibrating plate 21 is retracted inside the periphery of the isolation film 25. The distances from the boundaries of the respective sections of the hard vibration plate 21 to the corresponding boundaries of the isolation film 25 may be substantially uniform. The transmission 24 is also located within the cavity 20 b.

In other embodiments, the position of the hard vibrating plate 21 relative to the isolation film 25 may be designed as required on the premise of ensuring that the hard vibrating plate 21 is in the cavity 20 b.

The isolation diaphragm 25 is driven by the hard vibration plate 21 to generate a reciprocating bending deformation, i.e. a vibration, following the vibration of the hard vibration plate 21.

Fig. 17 is a partially cross-sectional view schematically showing an assembly position of the piezoelectric electroacoustic device 20 in the second embodiment in the electronic apparatus 10. The expression of fig. 17 refers to fig. 14, in fig. 17 the same partially enlarged position mark E as in fig. 14 is still used. This shows that the enlarged partial position of fig. 17 is the same as the enlarged partial position of fig. 14, except that the piezoelectric electroacoustic device 20 in fig. 17 is different in structure from the piezoelectric electroacoustic device 20 in fig. 14.

As shown in fig. 17, after the isolation diaphragm 25 is designed, the isolation diaphragm 25 replaces the position of the hard vibration plate 21 in the first embodiment. Namely: the isolation diaphragm 25 may be connected to the first cap section 121, for example, fig. 17 shows the connection relationship of the isolation diaphragm 25 to the second wall 121b of the first cap section 121. In practice, the separation film 25 may be connected to each of the first wall 121a, the second wall 121b, and the third wall 121c of the first cover 121, and each of the first wall 121a, the second wall 121b, and the third wall 121c may be connected to an edge of the separation film 25. Including but not limited to adhesive, welding, snapping, etc. The release film 25 may abut against the side 12e of the middle frame 12. The isolation diaphragm 25 maintains a space from the bottom surface 12d of the mounting groove 12c, which can serve as a front cavity of the piezoelectric electroacoustic device 20. The isolation diaphragm 25 may serve as a boundary between the front and rear cavities.

In the second embodiment, the sound emitting hole 12b may be located between the isolation film 25 and the bottom surface 12 d. Alternatively, in the vertical direction in the viewing angle of fig. 17, the upper surface of the isolation diaphragm 25 may be substantially flush with the lower side hole wall of the sound outlet hole 12 b. The above-described design enables the sound waves generated by the vibration of the isolation diaphragm 25 to be transmitted to the outside of the electronic device 10 through the sound outlet hole 12 b.

In the second embodiment, the isolation diaphragm 25 made of an elastic material has a good sealing effect, and can well isolate the front cavity and the rear cavity of the piezoelectric electroacoustic device 20, and block air flow between the front cavity and the rear cavity, thereby avoiding an acoustic short circuit phenomenon. The isolation film 25 also serves to suspend the hard vibration plate 21 and provides an elastic restoring force to the hard vibration plate 21, ensuring that the hard vibration plate 21 can stably vibrate.

Further, the isolation film 25 extending beyond the boundary of the hard vibration plate 21 is used to pull the hard vibration plate 21, which is easy to manufacture. In contrast, in the first embodiment, the washer 22 is used to pull the hard vibrating plate 21, which requires the washer 22 to have high elasticity. However, in the case where the thickness of the gasket 22 is limited, the gasket 22 is required to have good elasticity, which may cause difficulty in selecting the material for the gasket 22 and affect manufacturability. Therefore, the second embodiment has high manufacturability and is easy to fall on the ground.

As shown in fig. 18, based on the scheme of the first embodiment, the isolation film 25 in the third embodiment may include a first vibration part 251, a first fold ring 252 and a first connection part 253, wherein the first fold ring 252 connects the first vibration part 251 and the first connection part 253, the first connection part 253 surrounds the outer periphery of the first fold ring 252, and the first fold ring 252 surrounds the outer periphery of the first vibration part 251.

As shown in fig. 18, the first vibration part 251 may have a flat sheet shape, for example, a square sheet shape. The first vibration portion 251 is connected to the hard vibration plate 21 substantially in parallel. The boundary of the first vibration portion 251 may be substantially aligned with the boundary of the hard vibration plate 21, i.e., the first vibration portion 251 substantially overlaps the hard vibration plate 21. The first folding ring 252 is curved and arched in a direction away from the piezoelectric sheet 23, and the first folding ring 252 may be located between the hard vibrating plate 21 and the washer 22. The first connection portion 253 is connected to the gasket 22, and the first connection portion 253 may substantially overlap the gasket 22.

In the third embodiment, when the hard vibration plate 21 vibrates, the first corrugated rim 252 may deform accordingly. The arched shape of the first folding ring 252 reduces the vibration resistance of the hard vibration plate 21, so that the hard vibration plate 21 can be kept in a substantially flat state without being deformed by bending during vibration, that is, the hard vibration plate 21 can keep the piston motion, which is advantageous for ensuring the acoustic effect of the piezoelectric electroacoustic device 20. In addition, the first folding ring 252 can suspend the hard vibration plate 21 and provide elastic restoring force, so that the hard vibration plate can be maintained at a set position.

Fig. 19 can show the assembly relationship of the separator 25 and the middle frame 12 in the third embodiment. As shown in fig. 19, the first folded ring 252 is offset from the first cover 121 of the middle frame 12, and the first connection portion 253 is connected to the first cover 121. Thus, the first hinge ring 252 will not interfere with the first cover 121.

As shown in fig. 20, in the fourth embodiment, unlike the third embodiment, the first inflection ring 252 may be curved and arched in a direction approaching the piezoelectric sheet 23. This design enables the first hinge 252 to be accommodated within the space of the piezoelectric electroacoustic device 20 itself, making the piezoelectric electroacoustic device 20 of the fourth embodiment thinner.

As shown in fig. 21 and 22, in the fifth embodiment, based on the solution of the first embodiment, the piezoelectric electroacoustic device 20 may further include a diaphragm 26. The diaphragm 26 may be substantially in the form of a flat diaphragm, such as a square diaphragm. The diaphragm 26 may be made of a hard film material, such as a metal film material, such as magnesium aluminum alloy, copper, etc., or a PET film material, a carbon fiber film material, etc.

As shown in fig. 21 and 22, the diaphragm 26 and the hard vibration plate 21 are respectively located on opposite sides of the gasket 22, and the periphery of the diaphragm 26 is connected (e.g., bonded) to the gasket 22. The diaphragm 26, the gasket 22 and the hard vibration plate 21 may enclose a closed cavity 20 c. The fifth embodiment is different from the first embodiment in that the transmission portion 24 is connected between the hard vibration plate 21 and the diaphragm 26 in the fifth embodiment. The piezoelectric patch 23 is not attached to the gasket 22, but rather to the surface of the diaphragm 26 facing away from the gasket 22 (e.g., by bonding). The boundaries of the sections of the piezoelectric sheet 23 may be recessed within the corresponding boundaries of the diaphragm 26, i.e., the orthographic projection of the piezoelectric sheet 23 on the diaphragm 26 may completely fall within the boundaries of the diaphragm 26. The distance from each segment boundary of the piezoelectric sheet 23 to the corresponding boundary of the diaphragm 26 may be substantially uniform. The transmission portion 24 is located within the cavity 20 c.

In other embodiments, the position of the piezoelectric sheet 23 relative to the diaphragm 26 may be designed as required, provided that the orthographic projection of the piezoelectric sheet 23 on the diaphragm 26 is all located on the diaphragm 26.

Fig. 23 is a partially cross-sectional view showing an assembled position of the piezoelectric electroacoustic device 20 in the fifth embodiment in the electronic apparatus 10. The expression of fig. 23 refers to fig. 14, in fig. 23 the same partially enlarged position mark E as in fig. 14 is still used. This shows that the enlarged partial position of fig. 23 is the same as the enlarged partial position of fig. 14, except that the piezoelectric electroacoustic device 20 in fig. 23 is different in structure from the piezoelectric electroacoustic device 20 in fig. 14.

As shown in fig. 23, after the diaphragm 26 is designed, the diaphragm 26 replaces the piezoelectric plate 23 in the first embodiment. Namely: the diaphragm 26 may be connected to the second cover portion 131, for example, fig. 23 shows a connection relationship between the diaphragm 26 and one wall 131a of the second cover portion 131. In practice, the diaphragm 26 may be connected to all the walls 131a of the second cover portion 131, and all the walls 131a may be connected to the edge of the diaphragm 26. The attachment includes, but is not limited to, adhesive bonding. Diaphragm 26 may abut side 12e of bezel 12.

In the fifth embodiment, the edge of the piezoelectric sheet 23 is not fixed by the second cover portion 131, and the vibration resistance of the piezoelectric sheet 23 is reduced, so that the vibration displacement of the piezoelectric sheet 23 can be increased, and thus the vibration displacement of the hard vibration plate 21 can be increased. This is advantageous for increasing the amount of air that the piezoelectric electroacoustic device 20 can push, thereby further enhancing the low-frequency performance and the overall tone quality performance of the piezoelectric electroacoustic device 20.

The piezoelectric electroacoustic device 20 of example five does not include the isolation diaphragm 25, which is merely an example. In fact, the isolation diaphragm 25 and the diaphragm 26 are independent from each other and do not affect each other, and the piezoelectric electroacoustic device 20 may include both the isolation diaphragm 25 and the diaphragm 26 (described below), or only one of them.

As shown in fig. 24, in the sixth embodiment, unlike the fifth embodiment, the piezoelectric sheet 23 may be located between the diaphragm 26 and the hard vibration plate 21, and the piezoelectric sheet 23 and the surface of the diaphragm 26 facing the hard vibration plate 21 are connected, for example, the two are kept substantially consistent in the thickness direction and attached. The transmission portion 24 connects the hard vibration plate 21 and the piezoelectric sheet 23. The design of the sixth embodiment has not only the advantages of the design of the fifth embodiment, but also can utilize the internal space of the piezoelectric electroacoustic device 20 to accommodate the piezoelectric piece 23 without additionally occupying the structural space outside the piezoelectric electroacoustic device 20, so that the piezoelectric electroacoustic device 20 is thin.

As shown in fig. 25, in the seventh embodiment, based on the solution of the sixth embodiment, the piezoelectric electroacoustic device 20 may include two piezoelectric sheets 23 (which may be referred to as a first piezoelectric sheet and a second piezoelectric sheet, respectively), and the first piezoelectric sheet and the second piezoelectric sheet are respectively connected to two opposite sides of the diaphragm 26. The first piezoelectric sheet may be located between the hard vibration plate 21 and the diaphragm 26, and the first piezoelectric sheet may be substantially aligned with and attached to the diaphragm 26 in the thickness direction. The first piezoelectric patch and the second piezoelectric patch may be substantially identical in shape and area. The second piezoelectric sheet may substantially overlap the first piezoelectric sheet in the thickness direction of the diaphragm 26. In other embodiments, the shapes, areas and relative positions of the first piezoelectric sheet and the second piezoelectric sheet may be designed according to needs, and are not limited to the above.

As shown in fig. 25, the transmission portion 24 connects the hard vibrating plate 21 and the first piezoelectric sheet. The first piezoelectric sheet and the second piezoelectric sheet can drive the transmission part 24 to vibrate. The first piezoelectric sheet and the second piezoelectric sheet can provide a larger driving force to the transmission part 24, so that the vibration displacement of the hard vibration plate 21 is larger, which is beneficial to pushing more air vibration, and thus the low-frequency performance and the overall tone quality performance of the piezoelectric electroacoustic device 20 are improved. Meanwhile, in the seventh embodiment, the degrees of freedom of movement of the first piezoelectric sheet and the second piezoelectric sheet are both large, and the whole first piezoelectric sheet and the whole second piezoelectric sheet can vibrate. Due to the design, the effective vibration area of the piezoelectric electroacoustic device 20 in the seventh embodiment is large, so that the low-frequency performance and the overall tone quality of the piezoelectric electroacoustic device 20 are better.

As shown in fig. 26, in the eighth embodiment, based on the solution of the fifth embodiment, the diaphragm 26 may include a second connecting portion 261, a second fold ring 262, and a second vibrating portion 263. The second link 261 is connected to the second vibration part 263 by the second link 262, the second link 261 surrounds the outer circumference of the second link 262, and the second link 262 surrounds the outer circumference of the second vibration part 263.

The second vibration part 263 may have a flat sheet shape, for example, a square sheet shape. The boundary of the second vibrating portion 263 may be beyond the boundary of the piezoelectric sheet 23, or may be substantially flush with the boundary of the piezoelectric sheet 23. The second vibrating portion 263 is connected to the transmission portion 24. The second edge 262 may be spaced apart from the piezoelectric sheet 23 and may be curved and arched in a direction away from the rigid vibrating plate 21. The second connection portion 261 is connected to the gasket 22, and the second connection portion 261 may substantially overlap the gasket 22.

In the eighth embodiment, when the piezoelectric sheet 23 vibrates, the second corrugated rim 262 may deform accordingly. The arched shape of the second flange 262 reduces the vibration resistance of the piezoelectric plate 23, so that the vibration displacement of the piezoelectric plate 23 can be increased, and further the vibration displacement of the hard vibrating plate 21 is increased, which is beneficial to increasing the air volume that the piezoelectric electroacoustic device 20 can push, thereby further enhancing the low-frequency performance and the overall tone quality performance of the piezoelectric electroacoustic device 20. In addition, the second folding ring 262 can suspend the piezoelectric sheet 23 and provide elastic restoring force, so that the piezoelectric sheet can be maintained at a set position.

In other embodiments, unlike the eighth embodiment, the second corrugated rim 262 may be curved and arched in a direction approaching the hard vibration plate 21. That is, the two designs differ in that the curvature of the second collar 262 is arched in opposite directions.

As shown in fig. 27 and 28, in the ninth embodiment, based on the solution of the fifth embodiment, the diaphragm 26 may be provided with a plurality of through holes 26 a. The number of the through holes 26a is not limited, and may be twelve, for example. Each through hole 26a may be located at an edge of the diaphragm 26, and each section of the edge of the diaphragm 26 has the through holes 26a distributed therein. For example, in fig. 27, the four sides of the diaphragm 26 are distributed with through holes 26a, and all the through holes 26a may approximately form a closed annular array. The shape of each through hole 26a is not limited, and may be, for example, a circular hole or a square hole.

As shown in fig. 27 and 28, each through hole 26a communicates the rear cavity of the piezoelectric electroacoustic device 20 with the cavity between the diaphragm 26 and the hard diaphragm 21. I.e. each through hole 26a can communicate the side of the diaphragm 26 facing away from the cavity 20c with the cavity 20 c. Each through hole 26a may be completely staggered from the piezoelectric sheet 23, the second capping portion 131, and the gasket 22; alternatively, each through hole 26a may partially overlap with at least one of the piezoelectric sheet 23, the second capping portion 131, and the gasket 22. For example, the through hole 26a in fig. 28 may be enlarged or shifted to the right so that the through hole 26a partially overlaps the piezoelectric sheet 23, and the piezoelectric sheet 23 partially covers the through hole 26 a.

In the ninth embodiment, the through hole 26a is formed in the diaphragm 26, and the through hole 26a can communicate the rear cavity of the piezoelectric electroacoustic device 20 with the cavity 20c between the diaphragm 26 and the hard vibrating plate 21, which is equivalent to enlarging the rear cavity of the piezoelectric electroacoustic device 20, so that the low-frequency resonance of the piezoelectric electroacoustic device 20 can be increased, and the low-frequency performance of the piezoelectric electroacoustic device 20 can be improved.

As shown in fig. 29, in the tenth embodiment, unlike the ninth embodiment, the number of the through holes 26a may be small, for example, 4. All the through holes 26a may be distributed only at the corners, for example, four corners, of the diaphragm 26. The design of embodiment ten ensures the structural strength of the diaphragm 26.

In other embodiments, the number of the through holes 26a may be designed as required as long as the communication function is ensured. For example, the through holes 26a may be one, two, three, etc.

The diaphragm 26 of the ninth and tenth embodiments does not include the second bending ring 262, which is merely an example. In practice, when the diaphragm 26 includes the second bending ring 262, a through hole 262a may be formed on the second bending ring 262.

As shown in fig. 30 and 31, in the eleventh embodiment, unlike the second or fifth embodiment, the piezoelectric electroacoustic device 20 may include both the isolation diaphragm 25 and the diaphragm 26. The isolation film 25, the gasket 22 and the diaphragm 26 enclose a closed cavity 20d, and the hard vibration plate 21 and the transmission part 24 are located in the cavity 20 d. The transmission portion 24 connects the hard vibration plate 21 and the vibration film 26, and the piezoelectric sheet 23 may be located on a side of the vibration film 26 away from the transmission portion 24. In the eleventh embodiment, the structure, size, material, and positional relationship and connection relationship with other components of the isolation film 25 and the diaphragm 26 may be the same, and are not repeated here.

In the piezoelectric electroacoustic device 20 of the eleventh embodiment, since the entire hard diaphragm 21 and the entire piezoelectric plate 23 can vibrate, the effective vibration area of the piezoelectric electroacoustic device 20 is larger, and the low-frequency performance and the overall sound quality are better. Further, since the isolation film 25 is used, the acoustic short-circuit phenomenon is less likely to occur.

In other embodiments, based on the solution of the eleventh embodiment, the positions of the piezoelectric sheet 23 and the diaphragm 26 may be exchanged (as shown in fig. 24); piezoelectric sheets 23 may be attached to both opposite sides of the diaphragm 26 (as shown in fig. 25); the diaphragm 26 may include a second fold 262 (shown in fig. 26); the diaphragm 26 may be provided with a through hole 26a (as shown in fig. 27 and 29); the isolation diaphragm 25 may include a first fold 252 (shown in fig. 18 and 20). In the embodiment of the application, the above designs can be freely combined according to the needs.

The piezoelectric electroacoustic devices 20 in the above embodiments each have a front cavity formed by the bezel 12 of the electronic apparatus 10 and a rear cavity formed by the rear cover 13. In contrast, in the twelfth embodiment to be described below, the piezoelectric electroacoustic device 30 itself has a rear case 31, and the rear cavity of the piezoelectric electroacoustic device 30 is surrounded by the rear case 31. As will be described in detail below.

Referring to fig. 32 and 33, in a twelfth embodiment, unlike any of the above embodiments, the second cover 131 is not provided on the rear cover 13 of the electronic device 10, and the rear cover 13 does not participate in forming the rear cavity.

Fig. 33, 34, and 35 show a schematic structure of a piezoelectric electroacoustic device 30 according to a twelfth embodiment. As shown in fig. 33-35, the piezoelectric electroacoustic device 30 may further include a rear case 31. The piezoelectric electroacoustic device 30 can be regarded as adding a back case 31 to the piezoelectric electroacoustic device 20 of fig. 30. It is to be understood that this is merely an example, and that the back case 31 may be assembled with the piezoelectric electroacoustic device 20 of any of the above embodiments to obtain the piezoelectric electroacoustic device 30.

As shown in fig. 35, the rear case 31 may have a substantially groove-like structure, for example, a square groove structure. The rear shell 31 may include a bottom wall 311 and a plurality of side walls 312 (e.g., four), each side wall 312 is disposed at the periphery of the bottom wall 311 in a protruding manner, and all the side walls 312 are connected end to end in sequence to form a closed enclosure structure. The top end of each sidewall 312 is connected (e.g., bonded) to the periphery of the diaphragm 26, and a back cavity (which will be shown in fig. 36) is enclosed by the back shell 31 and the diaphragm 26. In other embodiments, each sidewall 312 of the back shell 31 may enclose an open enclosure structure (similar to a C-shape), in which case the back cavity enclosed by the back shell 31 and the diaphragm 26 is an open back cavity.

Fig. 36 is a partially cross-sectional view showing an assembled position of the piezoelectric electroacoustic device 30 in the twelfth embodiment in the electronic apparatus 10. The expression of fig. 36 refers to fig. 14, in fig. 36 the same partially enlarged position mark E as in fig. 14 is still used. This shows that the enlarged partial position of fig. 36 is the same as the enlarged partial position of fig. 14, except that the piezoelectric electroacoustic device 20 in fig. 36 is different in structure from the piezoelectric electroacoustic device 20 in fig. 14.

As shown in fig. 36, the rear case 31 may be mounted on the inner surface 13a of the rear cover 13, and the bottom wall 311 of the rear case 31 is connected (e.g., bonded or welded) to the inner surface 13 a. The assembly relationship among other parts of the piezoelectric electroacoustic device 30, such as the isolation diaphragm 25, the rigid vibrating plate 21, the gasket 22, the transmission portion 24, the diaphragm 26, and the piezoelectric sheet 23, can be the same as that of embodiment eleven (as shown in fig. 30), and will not be repeated here.

The piezoelectric electroacoustic device 30 of the twelfth embodiment is provided with the back case 31, and the piezoelectric electroacoustic device 30 is relatively modularized, and is easily assembled with the case of the electronic device 10, and the operational reliability is not easily affected by the assembly. Of course, the piezoelectric electroacoustic device 30 has better low-frequency performance and overall sound quality performance.

As shown in fig. 37, in the thirteenth embodiment, unlike any of the above-described embodiments, the first cover 121 is not provided on the middle frame 12 of the electronic device 10, and the middle frame 12 does not participate in forming the front cavity.

Fig. 38, 39 and 40 show a schematic structure of a piezoelectric electroacoustic device 40 according to a thirteenth embodiment. As shown in fig. 38-40, the piezoelectric electroacoustic device 40 may further include a front case 41. The piezoelectric electroacoustic device 40 can be regarded as adding a front case 41 to the piezoelectric electroacoustic device 20 of fig. 30. It is to be understood that this is merely an example, and that the front case 41 may be assembled with the piezoelectric electroacoustic device 20 of any of the above embodiments to obtain the piezoelectric electroacoustic device 40.

As shown in fig. 40 and 41, the front housing 41 may include a bottom wall 411 and a plurality of side walls 412 (e.g., three side walls 412), each side wall 412 is protruded from the periphery of the bottom wall 411, all the side walls 412 are connected in sequence to form an open enclosure structure (similar to a C shape), wherein one side of the bottom wall 411 is not provided with the side wall 41.

As shown in fig. 38 and 39, the top end of the sidewall 412 is connected (e.g., bonded) to the peripheral edge of the side of the isolation diaphragm 25 facing away from the gasket 22, so that the front shell 41 and the isolation diaphragm 25 enclose a front cavity (which will be shown in fig. 42). The front chamber has an outlet 40a for the sound waves in the front chamber to exit.

Fig. 42 is a partially cross-sectional view schematically showing an assembled position of the piezoelectric electroacoustic device 40 in the thirteenth embodiment in the electronic apparatus 10. The expression of fig. 42 refers to fig. 14, in fig. 42 the same partially enlarged position mark E as in fig. 14 is still used. This shows that the enlarged partial position of fig. 42 is the same as the enlarged partial position of fig. 14, except that the piezoelectric electroacoustic device 40 in fig. 42 is different in structure from the piezoelectric electroacoustic device 20 in fig. 14.

As shown in fig. 42, the front case 41 may be mounted on the bottom surface 12d of the middle frame 12, and the bottom wall 411 of the front case 41 is connected (e.g., bonded or welded) to the bottom surface 12 d. The outlet 40a of the front cavity of the piezoelectric electroacoustic device 20 may communicate with the sound outlet hole 12b so that the acoustic wave in the front cavity can propagate to the outside of the electronic apparatus 10 via the outlet 40a and the sound outlet hole 12 b. The assembly relationship among other components of the piezoelectric electroacoustic device 40, such as the isolation diaphragm 25, the rigid vibrating plate 21, the gasket 22, the transmission portion 24, the diaphragm 26, and the piezoelectric plate 23, can be the same as that of embodiment eleven (as shown in fig. 30), and will not be repeated here.

The piezoelectric electroacoustic device 40 of the thirteenth embodiment is provided with the front casing 41, and the piezoelectric electroacoustic device 40 is more modularized, and is easily assembled with the casing of the electronic device 10, and the operational reliability is not easily affected by the assembly. Of course, the piezoelectric electroacoustic device 40 has better low-frequency performance and overall sound quality performance.

As shown in fig. 43, 44, and 45, the piezoelectric electroacoustic device 50 in the fourteenth embodiment includes both the front case 41 and the rear case 31. It is considered that the piezoelectric electroacoustic device 50 is formed by adding the front case 41 to the piezoelectric electroacoustic device 30 or by adding the rear case 31 to the piezoelectric electroacoustic device 40. In the piezoelectric electroacoustic device 50, the assembling or positional relationship between the front case 41, the rear case 31, and other components such as the isolation diaphragm 25, the hard diaphragm 21, the gasket 22, the transmission portion 24, the diaphragm 26, and the piezoelectric plate 23 is the same as above, and will not be repeated here.

Fig. 46 is a partially cross-sectional view showing an assembled position of the piezoelectric electroacoustic device 50 in the fourteenth embodiment in the electronic apparatus 10. The expression of fig. 46 refers to fig. 14, in fig. 46 the same partially enlarged position mark E as in fig. 14 is still used. This shows that the enlarged partial position of fig. 46 is the same as the enlarged partial position of fig. 14, except that the piezoelectric electroacoustic device 50 in fig. 46 is different in structure from the piezoelectric electroacoustic device 20 in fig. 14.

As shown in fig. 46, in the fourteenth embodiment, the middle frame 12 of the electronic device does not have the first packaging part 121, the middle frame 12 does not participate in forming the front cavity, and the front case 41 and the isolation film 25 enclose the front cavity. The back cover 13 does not have the second packaging part 131, the back cover 13 does not participate in forming a back cavity, and the back shell 31 and the diaphragm 26 enclose the back cavity. The assembled relationship of the front case 41 and the middle frame 12, and the assembled relationship of the rear case 31 and the rear cover 13 are the same as those described above, and will not be repeated here.

The piezoelectric electroacoustic device 50 according to the fourteenth embodiment has the front casing 41 and the rear casing 31, and the piezoelectric electroacoustic device 50 has a compact structure and a high degree of modularization, is easily assembled with the casing of the electronic device 10, and is not easily affected by the assembly in terms of operational reliability. Of course, the piezoelectric electroacoustic device 50 has better low-frequency performance and overall sound quality.

In the piezoelectric electroacoustic devices of the above embodiments, the transmission part 24 can be regarded as a rigid body, and no mechanism moves therein. Unlike the above embodiments, the transmission part in the following embodiments may be a mechanism capable of mechanical movement.

Fig. 47, 48, and 49 show a schematic structure of a piezoelectric electroacoustic device 60 according to a fifteenth embodiment. As shown in fig. 47 to 49, the piezoelectric electroacoustic device 60 may include an isolation diaphragm 25, a hard diaphragm 21, a gasket 22, a transmission portion 61, a diaphragm 26, a piezoelectric sheet 23, and a rear case 31. The structure, positional relationship and assembling relationship of the above listed components except the transmission portion 61 are the same as those described above and will not be repeated here. The piezoelectric electroacoustic device 60 includes the rear case 31 without the front case 41, which is merely an example. In other embodiments, the piezoelectric electroacoustic device 60 may have the front housing 41 without the rear housing 31, or both the rear housing 31 and the front housing 41, or neither the front housing 41 nor the rear housing 31. In addition, the isolation diaphragm 25 and the diaphragm 26 in the piezoelectric electroacoustic device 60 may be disposed as required, but are not required.

As shown in fig. 50, the transmission part 61 may include a holder 611 and a plurality of transmission rods 612.

The support 611 may be approximately a ring-shaped structure surrounding a circle, such as a circular ring. Circumferential and axial directions may be defined for the seat 611. The circumferential direction is the surrounding direction of the annular structure, and the axial direction is the extending direction of the axis surrounded by the annular structure. The axis is not limited to a symmetry axis, and any straight line passing through the cavity of the annular structure and not intersecting the annular structure may be referred to as an axis. The axially opposite ends of the support 611 may be referred to as a force application end 611a and a link end 611b, respectively.

In other embodiments, the support 611 is not limited to a circular ring, but may be a square ring, a profiled ring, or the like. Alternatively, the support 611 may be an open frame structure that is not closed, such as an approximate V-shape, C-shape, etc.; alternatively, the support 611 is not a frame structure, but a plate-like, columnar, block-like member. In fact, the structure of the support 611 can be designed accordingly according to the embodiments of the present application, and the above description is only an example.

The drive rod 612 may be rod-shaped (having a length greater than the radial dimension), such as an approximately cylindrical rod. Both opposite end surfaces in the length direction of the transmission rod 612 may be inclined at an angle with respect to the axis of the transmission rod 612 (extending in the length direction of the transmission rod 612) rather than perpendicular to the axis so as to be connected to the hard vibration plate 21 and the diaphragm 26 (to be described later). The length of all of the drive links 612 can be substantially uniform. In other embodiments, the drive rod 612 is not limited to being a cylindrical rod, but may also be a prismatic rod (polygonal in cross-section), for example. The two opposing end surfaces along the length of the drive rod 612 may not necessarily be angled with respect to the axis of the drive rod 612, but may be substantially perpendicular to the axis. The lengths of all of the drive links 612 may not be all the same.

As shown in fig. 50, the drive rod 612 can include a fulcrum end 612a, a force receiving portion 612b, and a drive end 612 c. The fulcrum end 612a and the driving end 612c are opposite ends of the driving rod 612 in the length direction, respectively, and the force-receiving portion 612b is a portion located between the fulcrum end 612a and the driving end 612 c. The distance from the force-receiving portion 612b to the fulcrum end 612a (substantially equal to the distance from the force-applying end 611a to the fulcrum end 612a) is less than the distance from the force-receiving portion 612b to the transmission end 612c (substantially equal to the distance from the force-applying end 611a to the transmission end 612 c), i.e., the force-receiving portion 612b is closer to the fulcrum end 612a (i.e., the force-applying end 611a is closer to the fulcrum end 612a) than the transmission end 612 c. For example, the distance from the force-receiving portion 612b to the fulcrum end 612a is approximately one-half of the distance from the force-receiving portion 612b to the transmission end 612 c.

As shown in fig. 50, the force-receiving portion 612b is fixedly connected to the force-applying end 611a, for example, the transmission rod 612 can penetrate the surface at the force-applying end 611a, such that the force-receiving portion 612b is substantially embedded within the surface at the force-applying end 611 a. Alternatively, the force-receiving portion 612b may be completely exposed above the surface at the force-applying end 611a, and may be attached thereto by bonding, welding, or snapping. The driving rod 612 is not connected to the support 611 except for the force-receiving portion 612b, but is offset from the support 611.

The number of the transmission rods 612 can be designed as desired, and can be, for example, greater than or equal to two, such as two, three, four, five, ten, sixteen, etc. All the transmission rods 612 can be arranged out of plane with each other, that is, any two transmission rods 612 are neither parallel nor intersecting, and can be regarded as out-of-plane straight lines. Illustratively, there may be sixteen drive rods 612 in FIG. 50. As shown in fig. 50 and 51, each drive rod 612 can be approximated as a straight generatrix of a single-sheet hyperboloid, i.e., sixteen drive rods 612 can be approximated as a single-sheet hyperboloid. Of course, the arrangement of the approximate hyperboloids is merely an example, and the embodiments of the present application are not limited thereto.

Fig. 52 shows the assembly relationship between the transmission portion 61 and the hard vibration plate 21, the diaphragm 26, and the piezoelectric sheet 23.

As shown in fig. 52, the transmission portion 61 is located between the hard vibration plate 21 and the diaphragm 26. Wherein, the support 611 keeps a distance with the hard vibration plate 21, the support 611 can be installed on the vibration membrane 26, the axial direction of the support 611 can substantially coincide with the thickness direction of the vibration membrane 26, and the linking end 611b can be connected with the vibration membrane 26 (for example, bonding, welding, clamping, etc.). The linking end 611b may at least partially overlap with the vibration region of the piezoelectric sheet 23, for example, an orthogonal projection of the linking end 611b on the piezoelectric sheet 23 falls substantially within the vibration region 23a, and ideally, the linking end 611b is symmetrical about the center of the vibration region 23 a. In other embodiments, the linking end 611b may at least partially overlap with the vibration region of the piezoelectric sheet 23 in other vibration modes.

As shown in fig. 52, all the transmission rods 612 are connected between the hard vibration plate 21 and the diaphragm 26. Taking one of the transmission rods 612 as an example, the fulcrum end 612a of the transmission rod 612 is connected (e.g., bonded) to the diaphragm 26, and the transmission end 612c is connected (e.g., bonded) to the rigid vibration plate 21. The transmission rod 612 is inclined with respect to the hard vibration plate 21 and the vibration diaphragm 26, that is, the transmission rod 612 is not perpendicular to the hard vibration plate 21 and the vibration diaphragm 26. An end surface of the fulcrum end 612a (i.e., one of the two opposite end surfaces of the transmission rod 612 in the length direction mentioned above, the same applies hereinafter) may be attached to the surface of the diaphragm 26, and an end surface of the transmission end 612c is attached to the surface of the hard vibration plate 21. As described above, when both end surfaces can be inclined rather than perpendicular to the axis of the transmission rod 612, the end surfaces can be well attached to the surface of the hard vibration plate 21 and the surface of the vibration film 26, so that the transmission rod 612 can be reliably connected to the hard vibration plate 2 and the vibration film 26.

In the fifteenth embodiment, when the piezoelectric sheet 23 drives the diaphragm 26 to vibrate, the diaphragm 26 will drive the support 611 to vibrate, and the support 611 will apply a force to the force-receiving portion 612b of the transmission rod 612 through the force-applying end 611 a. This force will create a torque on the transfer rod 612, allowing the force-receiving portion 612b and the transfer end 612c to rotate about the fulcrum end 612 a. The transmission end 612c transmits the vibration to the hard vibration plate 21, and the hard vibration plate 21 vibrates. It can be seen that the transmission part 61 is essentially a lever mechanism, the transmission rod 612 acts as a lever, and the support 611 provides a lever force. It should be noted that the rotational angle of the drive rod 612 is extremely small.

Fig. 53(a) -53 (c) show the movement of the support 611 and the transmission rod 612. Fig. 53(a) shows that the support 611 and the two transmission rods 612 are in a balanced position when the diaphragm 26 is in a balanced state without vibration. Fig. 53(b) shows that when the diaphragm 26 vibrates in a bending manner in a certain direction (e.g., downward), the displacement of the support 611 reaches t1, the displacement of the force-receiving portion 612b is also substantially t1 (because the force-receiving portion 612b and the support 611 can be equivalent to a rigid body), and the included angle between the two transmission rods 612 and the diaphragm 26 is reduced. Fig. 53(c) shows that when the diaphragm 26 vibrates in bending in another direction (e.g., upward), the displacement of the support 611 reaches t2, the displacement of the force-receiving portion 612b is also substantially t2, and the included angle between the two transmission rods 612 and the diaphragm 26 increases. It should be noted that the rotational angle of the drive rod 612 is extremely small, such that t1 and t2 are extremely small, and t1 and t2 may be on the order of microns, such as tens of microns to hundreds of microns.

Fig. 54 is a diagram of the relationship between the displacement of the driving end 612c and the displacement of the force receiving portion 612b when the driving rod 612 is at different positions, wherein the driving rod 612 is rotated from the position of fig. 53(a) to the position of fig. 53 (c).

As shown in fig. 54, the transmission rod 612 can be rotated from an initial position to another position about the fulcrum end 612a by an angle a, wherein the angle a is extremely small. In the process, the force-receiving portion 612b and the transmission end 612c also rotate to the new position around the fulcrum end 612 a. A line m1 is drawn from the old position to the new position of the force-receiving portion 612b, the line m1 substantially coinciding with the circumferential trajectory of the force-receiving portion 612 b. A line m2 is drawn from the old position to the new position of the drive end 612c, the line m2 substantially coinciding with the circumferential path of the drive end 612 c. Since the distance from the force-receiving portion 612b to the fulcrum end 612a can be one-third of the overall length of the drive link 612, the length of the connecting line m2 is approximately equal to three times the length of the connecting line m1, according to the relevant principle of a similar triangle. It will be appreciated that the distance from the force-receiving portion 612b to the fulcrum end 612a can also be other values, and is not limited to one-third of the overall length of the drive rod 612. Accordingly, the length multiple relationship between the connecting line m2 and the connecting line m1 can be changed correspondingly.

The connecting line m1 is decomposed according to the parallelogram rule to obtain a line n1, wherein the extending direction of the line n1 is substantially perpendicular to the diaphragm 26, and the line n1 represents the vibration displacement of the force-receiving portion 612 b. It will be readily appreciated that when the angle a is extremely small, the length of the connecting line m1 differs extremely from the length of the line n1, and can be considered to be substantially equal. Similarly, the line m2 is decomposed according to the parallelogram rule to obtain a line n2, wherein the line n2 extends substantially perpendicular to the diaphragm 26, and the line n2 represents the vibration displacement of the driving end 612 c. It will be readily appreciated that when the angle a is extremely small, the length of the connecting line m2 differs extremely from the length of the line n2, and can be considered to be substantially equal.

From the above, the length of the line n2 may be approximately equal to three times the length of the line n1, i.e., the vibrational displacement of the driving end 612c may be approximately equal to three times the vibrational displacement of the force-receiving portion 612 b. Since the vibration displacement of the force-receiving portion 612b is substantially equal to the vibration displacement of the diaphragm 26 and the vibration displacement of the transmission end 612c is substantially equal to the vibration displacement of the hard vibration plate 21, the small vibration displacement of the diaphragm 26 can be amplified to the large vibration displacement of the hard vibration plate 21 by using the lever mechanism formed by the support 611 and the transmission rod 612.

In summary, in the fifteenth embodiment, the transmission portion 61 is designed, and the vibration displacement of the hard vibration plate 21 can be improved by the displacement amplification effect of the transmission portion 61. In addition, the design of the fifteenth embodiment also enables the piezoelectric electroacoustic device 60 to have a large effective vibration area. Therefore, under the dual design of improving the vibration displacement and increasing the effective vibration area, the amount of air that the piezoelectric electroacoustic device 60 can push is larger, and the low-frequency performance and the overall tone quality performance are better.

As shown in fig. 55, 56, 57, and 58, in the sixteenth embodiment, unlike the fifteenth embodiment described above, the transmission part 71 of the piezoelectric electroacoustic device 70 may include a rotating shaft 712 and a transmission arm 711.

The shaft 712 may be a cylindrical shaft. The shaft 712 may be made of metal or polymer. Opposite ends of the shaft 712 may be fixedly connected to the wall of the gasket 22, for example, opposite ends of the shaft 712 may be inserted into the wall of the gasket 22. In this design, the gasket 22 may be made of a rigid material, such as metal (e.g., aluminum alloy, steel alloy), hard plastic (polycarbonate, polycarbonate composite fiberglass), carbon fiber, and the like.

The rotation shaft 712 may be located between the hard vibration plate 21 and the diaphragm 26. In other embodiments, at least one end of the shaft 712 may penetrate through the wall of the gasket 22, and the end of the shaft 712 penetrating through the gasket 22 may be bent and fixedly connected to the rear shell 31 or the front shell 41. Even more, the end of the shaft 712 that extends through the gasket 22 may be fixedly connected to other structures of the electronic device 10 besides the piezoelectric electroacoustic device 70, such as the middle frame 12 or the rear cover 13.

As shown in fig. 58, the driving arm 711 may include a linking end 711a, a connecting arm 711b and a driving end 711c, which are sequentially bent and connected. The angle between the linking end 711a and the linking arm 711b, and the angle between the linking arm 711b and the driving end 711c can be designed as desired, for example, both can be approximately ninety degrees. The linking end 711a and the driving end 711c may be located at opposite sides of the connecting arm 711b, respectively. The connecting arm 711b is rotatably connected to the rotating shaft 712, for example, the rotating shaft 712 can pass through the connecting arm 711b, and the connecting arm 711b and the rotating shaft 712 form a rotating pair. The connecting position of the rotating shaft 712 on the connecting arm 711b may be closer to the linking end 711a but farther from the driving end 711 c. For example, the distance from the axis of the rotating shaft 712 to the center of the linking end 711a may be one third of the distance from the axis of the rotating shaft 712 to the center of the driving end 711 c.

As shown in fig. 58 and 56, the driving arm 711 may be located between the hard vibration plate 21 and the diaphragm 26. The linking end 711a may be connected to the diaphragm 26 (e.g., bonded, welded, or clamped), and may be located near the center of the vibrating area 23a of the piezoelectric sheet 23. Alternatively, the linking end 711a may at least partially overlap with a vibration region of the piezoelectric sheet 23 in the higher-order mode. The driving end 711c may be connected (e.g., bonded, welded, or snapped) to the rigid vibrating plate 21. Therefore, when the diaphragm 26 vibrates, the linking end 711a is driven to vibrate, and the driving end 711c and the hard vibrating plate 21 are driven to vibrate.

The driving arm 711 may be made of material with low density and less deformation, and the density of the driving arm 711 may be less than or equal to 3000kg/m³The modulus of the material of the drive arm 711 may be greater than or equal to 1 GPa. For example, the driving arm 711 may be made of metal such as aluminum or aluminum alloy, a fiber composite material such as carbon fiber or glass fiber, or a polymer such as polycarbonate.

The transmission part 71 in the sixteenth embodiment is substantially a lever mechanism, in which the rotation shaft 712 is used as a fulcrum, the diaphragm 26 provides power, and the distance from the rotation shaft 712 to the linkage end 711a and the distance from the rotation shaft 712 to the transmission end 711c are used as two moment arms respectively. According to the lever principle, since the distance from the rotation shaft 712 to the link end 711a is smaller than the distance from the rotation shaft 712 to the driving end 711c, the vibration displacement of the link end 711a is smaller than that of the driving end 711c at the time of vibration. Therefore, a small vibration displacement of the diaphragm 26 can be amplified to a large vibration displacement of the hard vibration plate 21 by using the lever mechanism constituted by the transmission arm 711 and the rotation shaft 712. For example, the vibration displacement of the hard vibration plate 21 may be approximately four times as large as that of the diaphragm 26.

It is easily understood that one or more transmission portions 71 may be provided. When there are a plurality of the transmission portions 71, the transmission portions are spaced apart from each other. The use of the plurality of transmission portions 71 enables driving at a plurality of positions of the hard vibration plate 21, and the hard vibration plate 21 can vibrate more smoothly.

Therefore, in the sixteenth embodiment, the transmission portion 71 is designed, and the vibration displacement of the hard vibration plate 21 can be improved by the displacement amplification effect of the transmission portion 71. Moreover, the transmission part 71 has a simpler mechanism design, is easy to manufacture and assemble, and has better product reliability. In addition, the design of the sixteenth embodiment also enables the piezoelectric electroacoustic device 70 to have a larger effective vibration area. Therefore, under the dual design of increasing the vibration displacement and increasing the effective vibration area, the amount of air that the piezoelectric electroacoustic device 70 can push is larger, and the low-frequency performance and the overall tone quality performance are better.

The scheme of the embodiment above this application, the low frequency performance that enables piezoelectric type electroacoustic device compares traditional piezoelectric type electroacoustic device and has great promotion. For example, fig. 59 shows a sound pressure level (ordinate) -frequency (abscissa) curve of the piezoelectric electroacoustic device 30 (shown in fig. 33 to 35) in the twelfth embodiment described above, and a sound pressure level-frequency curve of a conventional piezoelectric electroacoustic device. Wherein, the higher the sound pressure level, the better the low frequency performance. The comparison shows that: in the frequency band below 500Hz, the sound pressure level of the conventional piezoelectric electroacoustic device is about 70dB to 90dB, while the sound pressure level of the piezoelectric electroacoustic device 30 of example twelve is about 75dB to 100 dB. As can be seen, the low-frequency performance of the piezoelectric electroacoustic device 30 of the twelfth embodiment is greatly improved compared to the conventional piezoelectric electroacoustic device.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A piezoelectric electroacoustic device is characterized in that,

comprises a piezoelectric sheet, a transmission part and a hard vibration plate; the piezoelectric sheet and the hard vibration plate are stacked and arranged at intervals, the piezoelectric sheet comprises a vibration area, and the area of the hard vibration plate is larger than that of the vibration area; the transmission part is arranged between the center of the vibration area and the hard vibration plate and is fixedly connected with the hard vibration plate; the vibration area is used for vibrating to cause the transmission part to vibrate, so that the transmission part drives the hard vibration plate to vibrate.

2. The piezoelectric electroacoustic device of claim 1 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

the area of the hard vibration plate is larger than or equal to the area of the piezoelectric sheet.

3. The piezoelectric electroacoustic device of claim 1 or 2 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

at least a part of the vibration region overlaps the hard vibration plate.

4. The piezoelectric electroacoustic device as claimed in any of claims 1 to 3,

the modulus of the hard vibration plate is greater than or equal to 1 GPa.

5. The piezoelectric electroacoustic device of claim 4 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

the hard vibrating plate is made of any one of a composite material formed by polymethacrylimide foam and aluminum, a composite material formed by polymethacrylimide foam and aluminum alloy, a composite material formed by polymethacrylimide foam and carbon fiber, a composite material formed by polymethacrylimide foam and glass fiber, a composite material formed by balsa wood and aluminum alloy, foamed aluminum and foamed aluminum alloy.

6. The piezoelectric electroacoustic device as claimed in any of claims 1 to 5,

the transmission part is an integrated part.

7. The piezoelectric electroacoustic device as claimed in any of claims 1 to 5,

the transmission part is connected with the hard vibrating plate into a whole.

8. The piezoelectric electroacoustic device as claimed in any of claims 1 to 5,

the transmission part comprises a support and at least two transmission rods; the support comprises a force application end and a linkage end, and the force application end of the support is positioned between the hard vibration plate and the linkage end of the support; the at least two transmission rods are arranged in a different surface way; the transmission rod is fixedly connected with the force application end of the support and is obliquely arranged with the hard vibration plate; the transmission rod comprises a fulcrum end and a transmission end, the fulcrum end of the transmission rod and the transmission end of the transmission rod are arranged on two sides of the force application end of the support, and the distance between the force application end of the support and the fulcrum end of the transmission rod is smaller than the distance between the force application end of the support and the transmission end of the transmission rod; the transmission end of the transmission rod is fixedly connected with the hard vibration plate;

the vibration area is used for vibrating to cause the linkage end of the support and the force application end of the support to vibrate, so that the force application end of the support drives the transmission end of the transmission rod to rotate around the fulcrum end of the transmission rod, and the transmission end of the transmission rod drives the hard vibration plate to vibrate.

9. The piezoelectric electroacoustic device of claim 8 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

the transmission rod is set as a straight generatrix of the single-sheet hyperboloid.

10. The piezoelectric electroacoustic device as claimed in any of claims 1 to 5,

the transmission part comprises a rotating shaft and a transmission arm; the rotating shaft is arranged between the hard vibrating plate and the piezoelectric sheet; the transmission arm is rotatably connected with the rotating shaft and comprises a linkage end and a transmission end, the linkage end of the transmission arm and the transmission end of the transmission arm are positioned on two sides of the rotating shaft, the distance between the linkage end of the transmission arm and the rotating shaft is smaller than the distance between the transmission end of the transmission arm and the rotating shaft, and the transmission end of the transmission arm is fixedly connected with the hard vibration plate;

the vibration area is used for vibrating to cause the linkage end of the transmission arm to vibrate, so that the transmission end of the transmission arm rotates around the rotating shaft, and the transmission end of the transmission arm drives the hard vibration plate to vibrate.

11. The piezoelectric electroacoustic device of claim 10 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

the transmission arm comprises a connecting arm, and the connecting arm is connected with the linkage end and the transmission end; the connecting arm is rotationally connected with the rotating shaft; the linkage end reaches the transmission end all is the contained angle setting with the linking arm.

12. The piezoelectric electroacoustic device as claimed in any of claims 1 to 11,

the piezoelectric electroacoustic device comprises an isolating membrane and a gasket; the isolating membrane is made of elastic materials; the isolation film and the hard vibration plate are arranged in a laminated mode, and the isolation film is located on one side, away from the piezoelectric sheet, of the hard vibration plate; the gasket is positioned between the isolating membrane and the piezoelectric sheet, is connected with the periphery of the isolating membrane and the periphery of the piezoelectric sheet, and encloses a closed cavity with the isolating membrane and the piezoelectric sheet; the hard vibration plate and the transmission part are arranged in the cavity.

13. The piezoelectric electroacoustic device of claim 12 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

the region of the isolation film between the gasket and the hard vibration plate is in a curved arch shape.

14. The piezoelectric electroacoustic device as claimed in any of claims 1 to 11,

the piezoelectric electroacoustic device comprises a gasket, wherein the gasket is made of elastic material, is positioned between the hard vibrating plate and the piezoelectric sheet, is connected with the periphery of the hard vibrating plate and the periphery of the piezoelectric sheet, and encloses a closed cavity with the hard vibrating plate and the piezoelectric sheet; the transmission part is arranged in the cavity.

15. The piezoelectric electroacoustic device as claimed in any of claims 1 to 11,

the piezoelectric electroacoustic device comprises a vibrating diaphragm and a gasket; the vibrating diaphragm and the piezoelectric sheets are arranged in a stacked mode, the piezoelectric sheets are located on one side or two sides of the vibrating diaphragm, and the peripheries of the piezoelectric sheets are retracted to the peripheries of the vibrating diaphragm; the gasket is positioned between the hard vibrating plate and the piezoelectric sheet, is connected with the periphery of the hard vibrating plate and the periphery of the vibrating plate, and encloses a closed cavity with the hard vibrating plate and the vibrating plate; the transmission part is arranged in the cavity.

16. The piezoelectric electroacoustic device of claim 15 wherein the piezoelectric electroacoustic device further comprises a piezoelectric vibrator,

the area of the diaphragm between the gasket and the piezoelectric sheet is in a curved arch shape.

17. The piezoelectric electroacoustic device of claim 15 or 16 wherein the piezoelectric electroacoustic device further comprises a piezoelectric element,

the vibrating diaphragm is provided with a through hole which is communicated with the cavity.

18. The piezoelectric electroacoustic device as claimed in any of claims 1 to 11,

the piezoelectric electroacoustic device comprises an isolating membrane, a gasket and a vibrating membrane; the isolating membrane is made of elastic materials; the isolation film, the hard vibration plate and the vibration film are sequentially stacked; the gasket is positioned between the isolating membrane and the piezoelectric sheet, is connected with the periphery of the isolating membrane and the periphery of the vibrating membrane, and encloses a closed cavity with the isolating membrane and the vibrating membrane; the piezoelectric sheet is positioned on one side or two sides of the vibrating diaphragm; the hard vibrating plate and the transmission part are arranged in the cavity.

19. The piezoelectric electroacoustic device of any one of claims 1 to 14 wherein the piezoelectric electroacoustic device is a piezoelectric electroacoustic device,

the piezoelectric electroacoustic device comprises a rear shell, wherein the rear shell is arranged on one side of the piezoelectric sheet, which is far away from the hard vibrating plate; the rear shell is connected with the periphery of the piezoelectric sheet and encloses a rear cavity of the piezoelectric electroacoustic device with the piezoelectric sheet.

20. The piezoelectric electroacoustic device of any one of claims 15 to 18,

the piezoelectric electroacoustic device comprises a rear shell, and the rear shell is arranged on one side of the vibrating diaphragm, which is far away from the hard vibrating plate; the rear shell is connected with the periphery of the vibrating diaphragm and encloses a rear cavity of the piezoelectric electroacoustic device with the vibrating diaphragm.

21. The piezoelectric electroacoustic device of any one of claims 1 to 11 and 14 to 17 wherein the piezoelectric electroacoustic device is a piezoelectric electroacoustic device,

the piezoelectric electroacoustic device comprises a front shell, wherein the front shell is arranged on one side of the hard vibrating plate, which is far away from the piezoelectric plate; the front shell is connected with the periphery of the hard vibrating plate and encloses a front cavity of the piezoelectric electroacoustic device with the hard vibrating plate.

22. The piezoelectric electroacoustic device of any one of claims 12, 13, 18 and 19,

the piezoelectric electroacoustic device comprises a front shell, wherein the front shell is arranged on one side of the isolating membrane, which is far away from the hard vibrating plate; the front shell is connected with the periphery of the isolation membrane and encloses a front cavity of the piezoelectric electroacoustic device with the isolation membrane.

23. The piezoelectric electroacoustic device of any one of claims 1 to 22 wherein the piezoelectric electroacoustic device is a piezoelectric electroacoustic device,

the vibration region is a vibration region of the piezoelectric sheet in a first-order mode.

24. An electronic device, characterized in that,

comprising a housing and a piezoelectric electroacoustic device according to any of claims 1 to 23; the shell is provided with a sound outlet hole communicated with the inside and the outside of the shell; the piezoelectric electroacoustic device is arranged in the shell and can generate sound through the sound outlet hole.