Loudspeaker

Abstract

The utility model provides a loudspeaker which comprises two sound production units which are arranged in an overlapped mode and are respectively a first sound production unit and a second sound production unit, each sound production unit comprises a vibrating diaphragm, and the vibrating diaphragm comprises an elastic film and a conductive layer which are arranged in an overlapped mode; the first supporting piece and the second supporting piece are arranged on the two sides of the vibrating diaphragm respectively, and the peripheral edge of the vibrating diaphragm is fixedly connected with the two supporting pieces respectively; the first back polar plate is arranged on one side, far away from the vibrating diaphragm, of the first supporting piece, and the second back polar plate is arranged on one side, far away from the vibrating diaphragm, of the second supporting piece; each back polar plate comprises a conductive polar plate and an electret material layer which are combined into a whole; the two electret material layers of each sound production unit are respectively stored with different charges, and the conductive layers of the two sound production units are respectively used for inputting alternating current audio electric signals. The loudspeaker provided by the utility model has the advantages of simple structure, high sensitivity, low distortion and the like.

Description

Technical Field

[0001] The present application relates to the technical field of sound-generating devices, and in particular to a loudspeaker. Background Art

[0002] Speakers are electronic products that convert electrical signals into sound signals and are widely used in various electronic products such as mobile phones, headphones, televisions, computers, etc. Compared with dynamic electromagnetic speakers, electrostatic speakers rely on the attraction or repulsion of the diaphragm by the electric field force to drive the diaphragm to vibrate and produce sound. Electrostatic speakers do not require complex structures such as electromagnets and coils, and have a thin and light structure. They also have excellent performance in frequency response and transient response.

[0003] Existing electrostatic speakers often require a DC bias to be applied to the diaphragm. Since the electric field force on the diaphragm is proportional to the magnitude of the DC bias voltage, the DC voltage applied to the diaphragm needs to reach hundreds to thousands of volts, and an additional matching amplifier is required, which increases the complexity of the speaker system structure and the difficulty of manufacturing, and also leads to a significant increase in costs. In addition, due to the defects in the structural design of existing electrostatic speakers, the diaphragm driving force often changes nonlinearly as the position of the diaphragm changes during vibration, resulting in distortion of the speaker product, which greatly reduces its sound quality. Summary of the invention

[0004] Based on this, the present application provides a speaker to improve at least one of the problems existing in the prior art, such as the complex structure of the speaker system and the high product distortion.

[0005] To achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0006] The embodiment of the present application provides a speaker, including two superimposed sound-emitting units, namely a first sound-emitting unit and a second sound-emitting unit, each of which includes:

[0007] A diaphragm, the diaphragm comprising an elastic film and a conductive layer that are stacked;

[0008] Two support members, a first support member and a second support member are respectively arranged on both sides of the diaphragm, and the diaphragm is fixedly connected to the two support members at the peripheral edges thereof;

[0009] Two back plates, the first back plate is arranged on a side of the first support member away from the diaphragm, and the second back plate is arranged on a side of the second support member away from the diaphragm; each of the back plates comprises a conductive electrode plate and an electret material layer combined into one body;

[0010] The two electret material layers of each sound-emitting unit respectively store charges of different types, and the conductive layers of the two sound-emitting units are respectively used to input AC audio electrical signals.

[0011] In one of the embodiments, the two second back polar plates are arranged close to each other, each of the back polar plates is provided with a plurality of through holes, and the through holes of the two second back polar plates are opened correspondingly.

[0012] In one of the embodiments, in each of the sound-emitting units, the two electret material layers are respectively arranged toward a side close to the diaphragm.

[0013] In one embodiment, the first support member and the second support member are respectively circumferentially closed frame structures; a first mounting groove recessed inwardly is provided on a side surface of the first support member close to the first back polar plate, and the first back polar plate is installed in the first mounting groove; a second mounting groove recessed inwardly is provided on a side surface of the second support member close to the second back polar plate, and the second back polar plate is installed in the second mounting groove.

[0014] In one embodiment, the electret material layers of the two first back plates store the same kind of charge, the electret material layers of the two second back plates store the same kind of charge, and the two conductive layers are respectively used to input AC audio electrical signals of equal magnitude and opposite phases.

[0015] In one embodiment, the electret material layers of the two first back plates store negative charges.

[0016] In one embodiment, the conductive layer is arranged close to the first support member or the second support member. When the conductive layer is arranged close to the first support member, a conductive portion is provided on the surface of the first support member close to the diaphragm, and a conductive pin is provided on the conductive portion, and the conductive pin is protruding from the outer frame of the first support member; when the conductive layer is arranged close to the second support member, a conductive portion is provided on the surface of the second support member close to the diaphragm, and a conductive pin is provided on the conductive portion, and the conductive pin is protruding from the outer frame of the second support member.

[0017] In one of the embodiments, in each of the sound-emitting units, the distances between the two back plates and the diaphragm are equal, and the distance between the back plates and the diaphragm ranges from 0.05 mm to 3 mm.

[0018] In one embodiment, the thickness of the back plate is in the range of 0.05 mm to 3 mm, and the thickness of the electret material layer is in the range of 1 μm to 100 μm.

[0019] In one embodiment, the elastic film includes a PPS film, a PET film or a TPEE film, the thickness of the elastic film is no more than 10 μm, and the material of the conductive layer includes one of nickel, carbon powder or graphene.

[0020] The present application has at least the following beneficial effects: the speaker of the embodiment of the present application includes two superimposed sound-emitting units, each of which can operate independently, that is, when one of the sound-emitting units fails, the other sound-emitting unit can still work normally and emit sound. The superimposed arrangement of the two sound-emitting units can effectively increase the output sound pressure of the speaker and enhance the sound effect. The two back plates are respectively provided with electret material layers, and the two electret material layers respectively store heterogeneous charges, which can form an electric field force for driving the diaphragm, without the need for an external DC bias, making the overall structure of the speaker more concise, reducing the manufacturing difficulty and manufacturing cost, and the two back plates form a push-pull force structure on both sides of the diaphragm, which can effectively reduce the nonlinear distortion generated during the vibration of the diaphragm, thereby improving the output sound quality of the speaker. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the overall structure of the speaker according to an embodiment of the present application.

[0022] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of a loudspeaker.

[0023] Figure 3 for Figure 1 Schematic diagram of the exploded structure of the speaker.

[0024] Figure 4 This is a schematic diagram of the structure of two second back pole plates after assembly according to an embodiment of the present application.

[0025] Figure 5 This is a schematic diagram of the cross-sectional structure of the second back pole plate and the second support member after assembly according to an embodiment of the present application.

[0026] Figure 6 It is a schematic diagram of the cross-sectional structure of the second back pole plate, the second support member and the diaphragm after assembly according to an embodiment of the present application.

[0027] Figure 7 This is a schematic diagram of the cross-sectional structure of the speaker of an embodiment of the present application before the first back pole plate is installed.

[0028] Figure 8 Schematic diagram of the working principle of the preferred embodiment of the present application (where - indicates that the AC audio signal on the diaphragm of the first sound unit is negative at that moment, + indicates that the AC audio signal on the diaphragm of the second sound unit is positive at that moment, It means that negative charge is stored in the electret material layer. It means that there is positive charge stored in the electret material layer. Indicates the force direction of the diaphragm).

[0029] Fig. 9 This is a schematic structural diagram of the second supporting member of an embodiment of the present application.

[0030] The meanings of the symbols in the accompanying drawings are as follows:

[0031] 10. First sound unit; 20. Second sound unit;

[0032] 1. First back plate; 11. Conductive plate; 12. Electret material layer; 13. Through hole; 2. First support member; 21. First mounting groove; 3. Diaphragm; 31. Elastic membrane; 32. Conductive layer; 4. Second support member; 41. Conductive pin; 42. Conductive portion; 43. Second mounting groove; 5. Second back plate. DETAILED DESCRIPTION

[0033] The technical solution of the present application is further elaborated in detail below in conjunction with the accompanying drawings and specific embodiments of the specification.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit the implementation of this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0035] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating positions or positional relationships, are based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In the description of the present application, unless otherwise specified, "multiple" means two or more.

[0036] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] See also Figure 1 and Figure 2 The speaker of the embodiment of the present application includes two superimposed sound-emitting units, the two sound-emitting units are respectively a first sound-emitting unit 10 and a second sound-emitting unit 20, and each sound-emitting unit includes: a diaphragm 3, two supporting members and two back plates.

[0038] like Figure 3 As shown, the diaphragm 3 includes an elastic film 31 and a conductive layer 32 which are stacked. The two support members are respectively a first support member 2 and a second support member 4. The two support members are respectively arranged on both sides of the diaphragm 3, and the outer peripheral edges of the diaphragm 3 are respectively fixedly connected to the two support members, that is, the two support members are arranged around the peripheral part of the diaphragm 3, and the middle part is a hollow structure, which is used to form a vibration space for the diaphragm 3 to reciprocate. The two back pole plates are respectively a first back pole plate 1 and a second back pole plate 5. The first back pole plate 1 is arranged on the side of the first support member 2 away from the diaphragm 3, and the second back pole plate 5 is arranged on the side of the second support member 4 away from the diaphragm 3. Each back pole plate includes a conductive electrode plate 11 and an electret material layer 12 which are combined into one. The two electret material layers 12 of each sound unit respectively store heterogeneous charges, and the conductive layers 32 of the two sound units are respectively used to input AC audio electrical signals.

[0039] In some embodiments, a plurality of peaks (not shown) may be provided on the surface of the conductive layer 32 of the diaphragm 3, and the height of the peaks is not greater than 0.5 mm. The peaks may be manufactured, for example, by placing the substrate of the elastic membrane 31 on a breathable steel mold with tiny holes on the surface, and subjecting it to high temperature and high pressure treatment, so that an elastic membrane 31 with many irregular fine peaks on the surface is obtained, and then the elastic membrane 31 is flattened, a tension is applied to it by a clamp and fixed, and placed in a vacuum furnace for vacuum plating a conductive layer 32, and the conductive layer 32 will also have many irregular fine peaks to form peaks. When an AC audio signal is applied to this conductive layer 32, according to the characteristics of the electrostatic field being enhanced at the edge of the conductor, these irregular fine peaks will strengthen the average electrostatic field strength applied to the diaphragm 3, thereby increasing the driving electric field force on the diaphragm 3, and further increasing the output sound pressure of the electrostatic speaker. The peak portion can also be manufactured in the following manner, for example, the base material of the elastic film 31 can be kept unchanged, and the conductive layer 32 attached to the surface thereof can be roughened to produce many irregular and fine peaks on the conductive layer 32, so that the peak portion with the same effect can also be obtained. The specific manufacturing method of the peak portion is not limited.

[0040] Specifically, Figure 4As shown, when the two sound-emitting units are stacked, the two second back plates 5 can be arranged close to each other, that is, the two second back plates 5 are fixedly connected, and the two first back plates 1 are located near the outer ends of the speaker. A certain number of through holes 13 are respectively provided on each back plate, and the through holes 13 can play a role in adjusting air compliance and sound damping. The through holes 13 of the two second back plates 5 are opened correspondingly.

[0041] like Figure 3 , Figure 5 and Fig. 9 As shown, the first support member 2 and the second support member 4 in this embodiment are respectively a circumferentially closed frame structure, for example, a frame structure with a rectangular cross section. The first support member 2 is provided with a first mounting groove 21 recessed inwardly on one side surface close to the first back plate 1, and the first back plate 1 is installed in the first mounting groove 21; Figure 7 As shown, a second mounting groove 43 is provided on one side of the second support member 4 close to the second back plate 5, and the second back plate 5 is mounted in the second mounting groove 43. The two second mounting grooves 43 of the two second support members 4 enclose the two second back plates 5 therein.

[0042] Specifically, in the actual manufacturing process, grooves can be machined on both surfaces of the first support member 2 and the second support member 4, that is, the overall structure of the first support member 2 and the second support member 4 is the same. Taking the first support member 2 as an example, a first mounting groove 21 is provided on one side surface, and a second mounting groove 43 is provided on the other side surface. According to the size requirements of the first back pole plate 1 and the second back pole plate 5, the sizes of the first mounting groove 21 and the second mounting groove 43 can be the same or different. The two support members have the same outer dimensions, which is conducive to mass production and manufacturing. When in use, there is no need to distinguish whether it is the first support member 2 or the second support member 4, which improves the convenience of production and assembly.

[0043] The electret material layers 12 of the two back plates in each sound unit are respectively arranged on the side surface of the back plate close to the corresponding diaphragm 3, so that the charge stored in the electret material layer 12 is closer to the diaphragm 3, and when an AC audio signal is input to the diaphragm 3, a higher electric field force can be formed on the diaphragm 3. In this embodiment, the electret material layer 12 can store charge by high-voltage polarization.

[0044] For each sound-emitting unit, as long as the charges stored in the two electret material layers 12 are of opposite charges, an electric field force for driving the corresponding diaphragm 3 can be formed, and an AC audio signal is applied to the diaphragm 3, and the sound-emitting unit can make a sound. In order to make the sound effect of the entire speaker better, the two first back plates 1 located at the two ends of the outer side of the speaker can store the same charge, and the two second back plates 5 located in the middle can store the same charge, and the charges stored in the first back plate 1 and the second back plate 5 are opposite. Furthermore, AC audio signals of equal magnitude and opposite phases can be input to the conductive layers 32 of the two diaphragms 3 respectively. In this way, the diaphragms 3 of the two sound-emitting units are in a synchronous motion state and move in the same direction at the same time, so that the electric field force is larger and less distorted. Symmetrical electrostatic field forces are formed on both sides of the two diaphragms 3, making the electric field force stronger, and as the displacement of the diaphragm 3 changes, the electric field force always maintains symmetrical driving, so that the driving force of the speaker always remains linear, thereby reducing the problem of non-linear driving electric field force caused by the displacement change of the diaphragm 3, and reducing the distortion of the speaker product. Furthermore, negative charges can be stored on the two first back plates 1, and positive charges can be stored on the two second back plates 5. In this way, the second back plates 5 storing positive charges can be completely enclosed in the second support member 4. Since there is usually a certain amount of negative charge in the air, if the negative charge in the air is in contact with the positive charge of the back plate for a long time, a certain neutralization reaction will occur, which will reduce the number of positive charges stored in the electret material layer 12, which will reduce the stability of the electric field force. Therefore, the present application sandwiches the two second back pole plates 5 polarized with positive charge in the closed cavity formed between the two second support members 4 to prevent the two second back pole plates 5 storing positive charge from contacting the outside air. In this way, the positive charge can be stored more stably for a longer period of time, which greatly increases the long-term working stability of the product and solves the problem that the positive charge cannot be stored and used for a long time that has always existed in the industry.

[0045] Taking the first sound unit 10 as an example, the working principle of the sound unit is explained. For example, at a certain moment, when a negative transient electrical signal is applied to the diaphragm 3 of the first sound unit 10, it will be subject to the downward repulsive force (in the direction shown in the figure) of the first back plate 1 of the sound unit, and at the same time, it will also be subject to the downward attractive force of the second back plate 5 of the sound unit. This push-pull force mode is called PUSH-PULL. For this PUSH-PULL driving structure, the force F of the diaphragm 3 is 总 =F 排斥 +F 吸引 When the diaphragm 3 of the first sound unit 10 moves downward, the repulsive force F of the first back plate 1 will decrease by △f, and the attractive force of the second back plate 5 will increase by △f accordingly, so that the total electrostatic force F acting on the diaphragm 3 is 总 =(F 排斥 -△f)+(F 吸引+△f)=F 排斥 +F 吸引 It can be seen that the driving force on the diaphragm 3 remains unchanged, that is, the speaker will not produce nonlinear changes in the driving force due to changes in the vibration position of the diaphragm 3. Therefore, the distortion of the speaker product is greatly reduced, theoretically approaching zero, and the product performance and sound quality are greatly improved, which can achieve HIFI sound quality effects. The force conditions of the second sound unit 20 are the same as those of the first sound unit 10, which will not be repeated.

[0046] When positive charges are stored on the second backpolar plate 5 and negative charges are stored on the first backpolar plate 1 , corresponding protective measures may be added to the outer sides of the two first backpolar plates 1 , such as providing a sealed protective film, to reduce the chance of positive charges on the backpolar plates contacting the air.

[0047] The conductive layer 32 of the diaphragm 3 of each sound-emitting unit can be arranged close to the first support member 2 or the second support member 4. When the conductive layer 32 is arranged close to the first support member 2, a conductive portion 42 is arranged on the surface of the first support member 2 close to the diaphragm 3, and a conductive pin 41 is arranged on the conductive portion 42, and the conductive pin 41 is arranged protruding from the outer frame of the first support member 2; when the conductive layer 32 is arranged close to the second support member 4, a conductive portion 42 is arranged on the surface of the second support member 4 close to the diaphragm 3, and a conductive pin 41 is arranged on the conductive portion 42, and the conductive pin 41 is arranged protruding from the outer frame of the second support member 4. The conductive pin 41 is used to access the external AC audio voltage and input it to the corresponding diaphragm 3 through the conductive portion 42.

[0048] In order to make the overall structure of the entire speaker symmetrical, the first sound unit 10 and the second sound unit 20 can be set to have exactly the same structure and size specifications, and the size specifications of the two supporting members in each sound unit are also exactly the same, and the distance between the two back plates and the diaphragm 3 in each sound unit is equal.

[0049] In this embodiment, the thickness of the back plate ranges from 0.05 mm to 3 mm, preferably from 0.1 mm to 0.3 mm; the thickness of the electret material layer 12 ranges from 1 μm to 100 μm, preferably from 20 μm to 50 μm. Components in this thickness range are easier to process and can store more charge, making the electric field driving force greater.

[0050] The distance between the back plate (the first back plate 1 or the second back plate 5) and the diaphragm 3 ranges from 0.05mm to 3mm, preferably from 0.1mm to 1mm. The distance between the diaphragm 3 and the back plate is determined by the local structural thickness of the support, which is also the vibration space of the diaphragm 3. The smaller the distance between the diaphragm 3 and the back plate, the higher the sound pressure output by the product, but the diaphragm 3 is easily adsorbed to the back plate and causes poor performance; on the contrary, the greater the distance between the diaphragm 3 and the back plate, the smaller the sound pressure output by the product, but it is not easy to absorb the film at this time. Therefore, a support pad (not shown) structure can also be added to the speaker to prevent film absorption while increasing the sound pressure output of the product. The support pads can be respectively arranged between the first back plate 1 and the corresponding diaphragm 3 (the diaphragm 3 of the same sound-emitting unit as the first back plate 1 and the second back plate 5), and between the second back plate 5 and the corresponding diaphragm 3. The number of support pads can be multiple and discretely distributed along the surface of the diaphragm 3. The support pad can be fixedly connected to the back plate (the first back plate 1 or the second back plate 5) at one end and fixedly connected to the diaphragm 3 at the other end, or only fixedly connected to the back plate at one end. The support pad can be a soft rubber pad, a silicone pad, etc. The height of the support pad is the same as the spacing between the diaphragm 3 and the back plate.

[0051] Specifically, the speaker of this embodiment can be manufactured and assembled in the following manner (the speaker structure is described by taking the two first back pole plates 1 polarized to positive charges and the two second back pole plates 5 polarized to negative charges as an example):

[0052] A high voltage of -11KV is used to perform negative high voltage polarization on the two first back pole plates 1, so that stable negative charges are stored in the electret material layer 12 of the two first back pole plates 1. A high voltage of +11KV is used to perform positive high voltage polarization on the two second back pole plates 5, so that stable positive charges are stored in the electret material layer 12 of the two second back pole plates 5.

[0053] The two second back plates 5 polarized to positive charge are attached together, and the through holes 13 are aligned, and the electret material layer 12 is arranged toward the outside (close to the side of the diaphragm 3). Figure 4As shown. The electret material layer 12 is usually made of PTFE (polytetrafluoroethylene) or PEP (fluorinated ethylene propylene copolymer, perfluoroethylene propylene copolymer) and other electret materials. The conductive electrode plate 11 is usually made of conductive materials, such as stainless steel metal sheets, or nickel-plated copper sheets and other conductive materials, or other materials that have undergone surface conductive treatment. The thickness of the back plate in this embodiment is usually between 0.05mm and 3mm, wherein the thickness of the electret material layer 12 is between 1μm and 100μm, the thickness of the back plate in this embodiment is preferably between 0.1mm and 0.3mm, and the thickness of the electret material layer 12 is preferably between 20μm and 50μm. The back plate products within the above thickness range are easy to process, store more charge, and have a greater electric field driving force. In some embodiments, a damping net can also be set between the two second back plates 5, and the damping net is set between the two conductive plates 11. The damping net is used to block the through holes 13 on the back plate to adjust the air compliance and acoustic damping. The material of the damping mesh can be metal, preferably a stainless steel metal mesh, the thickness of the damping mesh ranges from 0.03 mm to 3 mm, and the mesh number of the damping mesh ranges from 100 mesh to 1000 mesh. By selecting damping meshes of different thicknesses and mesh numbers, the vibration damping of the diaphragm 3 can be adjusted, so that the diaphragm 3 is easy to vibrate and will not over-vibrate when vibrating, so as to achieve the effect of adjusting the frequency response curve of the sound pressure output of the product (cutting valleys and filling peaks to make the frequency response curve flatter) without affecting the sound pressure output, thereby achieving the expected design result.

[0054] like Figure 5 and Fig. 9 As shown, the two assembled second back plates 5 are placed into the second mounting groove 43 of one of the second support members 4. Then, the second mounting groove 43 of the other second support member 4 is buckled downward on the two placed second back plates 5, so that the outer contours of the two second support members 4 are aligned. In this embodiment, the outer surfaces of the two second support members 4 are respectively provided with conductive portions 42, and the outer edges of the conductive portions 42 are provided with conductive pins 41.

[0055] When two support members have the same appearance structure, when setting the conductive portion 42, any one of the support members can be selected for setting. During assembly, one of the support members provided with the conductive portion 42 can also be selected as the first support member 2 or the second support member 4 according to the placement direction of the conductive layer 32 of the diaphragm 3. For example, during assembly, if the conductive layer 32 is arranged toward the first support member 2, the support member provided with the conductive portion 42 is used as the first support member 2, and the two first support members 2 are installed on the outside of the two diaphragms 3, and the conductive portion 42 is in contact with the conductive layer 32; if the conductive layer 32 is arranged toward the second support member 4 during assembly, the support member provided with the conductive portion 42 is used as the second support member 4, and the two second support members 4 are installed between the two diaphragms 3, and the conductive portion 42 is in contact with the conductive layer 32.

[0056] The second support member 4 has a certain mechanical structural strength. In this embodiment, FR-4 epoxy glass cloth board (i.e., the substrate of PCB printed circuit board) with copper clad laminate is used. That is, except for the conductive part 42 of the second support member 4, which is made of copper clad laminate material, the rest are epoxy glass cloth board. Of course, other non-metallic or metallic materials that meet the above requirements can also be used. The material can be formed into the required shape after mechanical processing, and the components can be connected by screws and other connectors.

[0057] The elastic film 31 of the diaphragm 3 can be a thin film with a certain elasticity. The smaller the thickness, the better the product performance. In this embodiment, a 2μm thick PPS (polyphenylene sulfide) film is used, and other films with a thickness of less than 10μm such as PPS, PET (polyethylene terephthalate) or TPEE (polyester rubber) can also be used. The elastic film 31 is unfolded and flattened, and the elastic film 31 is fixed by a clamp, and the elastic film 31 has a certain tension. The elastic film 31 with set tension is placed in a vacuum furnace for vacuum plating to form a conductive layer 32 on its surface. The material of the conductive layer 32 can be nickel, for example. The conductive layer 32 can also be formed on the surface of the elastic film 31 by surface coating or other methods, such as coating carbon powder or graphene.

[0058] Place one diaphragm 3 with its conductive layer 32 facing downward on the upper surface of the conductive portion 42 of the second support member 4 located above (in the direction shown in the figure) to ensure good electrical contact between the two. Place the other diaphragm 3 with its conductive layer 32 facing upward on the lower surface of the conductive portion 42 of the second support member 4 located below to ensure good electrical contact between the two. The conductive pin 41 is a part of the conductive portion 42. When two external AC audio signals of opposite phases and equal magnitude are respectively added to the two conductive pins 41, they are output to the conductive layers 32 of the two diaphragms 3 through the two conductive pins 41. The cross-sectional view of the product with two diaphragms 3 placed is shown in FIG. Figure 6 shown.

[0059] like Figure 7 As shown, a first support member 2 is arranged on the upper surface of the diaphragm 3 of the first sound-emitting unit 10, and a first mounting groove 21 is arranged on the upper surface of the first support member 2, and a first back pole plate 1 (the electret material layer 12 is arranged downward) is installed in the first mounting groove 21; another first support member 2 is arranged on the lower surface of the diaphragm 3 of the second sound-emitting unit 20, and a first mounting groove 21 is arranged on the lower surface of the first support member 2, and another first back pole plate 1 (the electret material layer 12 is arranged upward) is installed in the first mounting groove 21.

[0060] Finally, the components are connected and fixed by screws and nuts, so that the various layers of the product are seamlessly combined together to form a complete speaker product. Its cross-section is shown in the figure below. Figure 2shown.

[0061] The working principle of the speaker product of this embodiment is as follows:

[0062] The speaker of this embodiment is provided with four back plates and two diaphragms 3. The electret material layers 12 of the four back plates have been polarized, so a certain amount of electrostatic charge Q is stored in the electret material layer 12. The electret material layers 12 of different polarities are arranged according to the above embodiment (two first back plates 1 store negative charge, and two second back plates 5 store positive charge), which will provide polarization bias electrostatic voltage to generate two electrostatic fields respectively.

[0063] The surfaces of the upper and lower diaphragms 3 are both coated with conductive materials (conductive layers 32) and are placed at a certain distance from each other. There is a certain distance between the upper and lower diaphragms 3 and the back plate, and preferably the same distance, that is, the distance between the diaphragm 3 and the back plate is the same. When two external AC audio signals with opposite phases are respectively added to the two conductive pins 41, they are respectively output to the conductive layers 32 of the two diaphragms 3 through the two conductive parts 42. Assuming that at a certain moment, the electric field polarity of the two AC audio signals with opposite phases is negative on the upper side and positive on the lower side, such as Figure 8 As shown, at this moment, the electric field polarity of the upper diaphragm 3 (first sound-emitting unit 10) is negative, and it is subjected to the PUSH-PULL force of the upper set of back plates (first back plate 1 and second back plate 5) and produces downward movement; the electric field polarity on the lower diaphragm 3 is positive, and it is subjected to the PUSH-PULL force of the lower set of back plates and also produces downward movement. If the polarity of the electric field applied to the two membranes is reversed, such as positive on the top and negative on the bottom, the upper diaphragm 3 moves upward, and the lower diaphragm 3 also moves upward. In this way, the upper and lower diaphragms 3 will vibrate back and forth under the action of the AC audio signal, thereby pushing the air on both sides to produce sound.

[0064] The speaker of this embodiment is provided with four back plates and two diaphragms. The four back plates are polarized and store different charges as needed, and the two diaphragms are respectively connected to electrical signals of opposite polarity (180 degrees phase difference). In this way, a PUSH-PULL structure is formed between the upper diaphragm and the two upper back plates, and a PUSH-PULL structure is formed between the lower diaphragm and the two lower back plates. The two diaphragms have symmetrical charges on both sides to form an electrostatic field force, which is larger, and is always driven symmetrically with the displacement change of the diaphragm. In this way, the driving force of the system always remains linear, reducing the problem of non-linear driving electric field force caused by the change of diaphragm displacement, greatly reducing the distortion of the product, and theoretically tending to zero, greatly improving the product performance and sound quality, and achieving HIFI sound quality effects.

[0065] At the same time, the product structure clamps the two second back plates polarized with positive charges in a closed cavity formed by two diaphragms and two second supporting members, avoiding the two second back plates storing positive charges from contacting the outside air, and preventing the positive charges from contacting moisture or negative charges in the air and causing the number of positive charges to decrease, so that the positive charges can be stored more stably for a longer period of time, greatly increasing the long-term working stability and reliability of the product, and solving the problem of long-term storage and use of positive charges that has long been unresolved in the industry.

[0066] The two diaphragms are respectively connected to electrical signals of opposite polarity (180 degrees phase difference) to form a dynamic electric field, which further enhances the electric field force acting on the diaphragms and further improves the output sound pressure of the speaker.

[0067] The thickness of the back plate and the diaphragm of the embodiment of the present application is very thin, and the distance between the diaphragm and the back plate is also very small. Compared with the thickness of the traditional speaker of about 5cm to 10cm, it is an ultra-thin design, which can meet the application scenarios with ultra-thin product size requirements, such as the roof of the car. At the same time, the weight of this speaker is very light, which can meet the application scenarios with lightweight requirements, such as new energy vehicles.

[0068] The speaker product of the present application has a simple structure, a thin and light design, a simple manufacturing process, and does not require rare metal raw materials such as rare earths. It has low cost, high product stability, and excellent performance. It is a low-distortion, high-performance electrostatic speaker product. And compared with traditional ordinary electrostatic speakers that require a DC bias voltage to drive, the present application uses the voltage generated by the electrostatic charge of the electret material layer to replace the external DC bias voltage, reducing the complexity of the drive system and the complexity of the product design. At the same time, the setting of four back plates plus two diaphragms in the present application not only doubles the voltage generated by the electrostatic charge of the electret, but also makes the driving force on the two diaphragms more symmetrical, which is an important means to improve the output sensitivity and frequency curve of the speaker, and reduce distortion.

[0069] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0070] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A loudspeaker, characterized in that: It includes two superimposed sound-emitting units, namely a first sound-emitting unit and a second sound-emitting unit, each of which includes: A diaphragm, the diaphragm comprising an elastic film and a conductive layer that are stacked; Two supporting members, a first supporting member and a second supporting member are respectively arranged on both sides of the diaphragm, and the outer peripheral edges of the diaphragm are respectively fixedly connected to the two supporting members; Two back plates, the first back plate is arranged on a side of the first support member away from the diaphragm, and the second back plate is arranged on a side of the second support member away from the diaphragm; each of the back plates comprises a conductive electrode plate and an electret material layer combined into one body; The two electret material layers of each sound-emitting unit respectively store charges of different types, and the conductive layers of the two sound-emitting units are respectively used to input AC audio electrical signals.

2. The loudspeaker according to claim 1, characterized in that The second back plates of the two sound-generating units are arranged close to each other, each of the back plates is provided with a plurality of through holes, and the through holes of the two second back plates are opened correspondingly.

3. The loudspeaker according to claim 1, characterized in that In each of the sound-emitting units, the two electret material layers are respectively arranged toward a side close to the diaphragm.

4. The loudspeaker according to claim 2, characterized in that The first support member and the second support member are respectively circumferentially closed frame structures; a first mounting groove recessed inwardly is provided on a surface of one side of the first support member close to the first back polar plate, and the first back polar plate is installed in the first mounting groove; a second mounting groove recessed inwardly is provided on a surface of one side of the second support member close to the second back polar plate, and the second back polar plate is installed in the second mounting groove.

5. The loudspeaker according to claim 4, characterized in that The electret material layers of the two first back plates store the same kind of charges, the electret material layers of the two second back plates store the same kind of charges, and the two conductive layers are respectively used to input AC audio electrical signals of equal magnitude and opposite phases.

6. The loudspeaker according to claim 5, characterized in that The electret material layers of the two first back plates store negative charges.

7. The loudspeaker according to claim 4, characterized in that The conductive layer is arranged close to the first support member or the second support member. When the conductive layer is arranged close to the first support member, a conductive portion is provided on the surface of the first support member close to the diaphragm, and a conductive pin is provided on the conductive portion, and the conductive pin is protruded from the outer frame of the first support member; when the conductive layer is arranged close to the second support member, a conductive portion is provided on the surface of the second support member close to the diaphragm, and a conductive pin is provided on the conductive portion, and the conductive pin is protruded from the outer frame of the second support member.

8. The loudspeaker according to claim 1, wherein: In each of the sound-emitting units, the distances between the two back plates and the diaphragm are equal, and the distance between the back plates and the diaphragm ranges from 0.05 mm to 3 mm.

9. The loudspeaker according to claim 1, characterized in that The thickness of the back plate ranges from 0.05 mm to 3 mm, and the thickness of the electret material layer ranges from 1 μm to 100 μm.

10. The loudspeaker according to claim 1, characterized in that The elastic film includes a PPS film, a PET film or a TPEE film, the thickness of the elastic film is not greater than 10 μm, and the material of the conductive layer includes one of nickel, carbon powder or graphene.

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