CN113973256B

CN113973256B - Bone conduction loudspeaker and magnetic circuit assembly thereof

Info

Publication number: CN113973256B
Application number: CN202111170781.5A
Authority: CN
Inventors: 张磊; 廖风云; 齐心
Original assignee: Shenzhen Voxtech Co Ltd
Current assignee: Shenzhen Voxtech Co Ltd
Priority date: 2018-01-08
Filing date: 2018-09-11
Publication date: 2024-03-22
Anticipated expiration: 2038-09-11
Also published as: CN114025289B; CN114007171B; CN114025290A; CN108600920A; CN114025289A; CN114025290B; CN114007171A; CN113973256A; CN110022516B; CN114007172A; CN110022516A

Abstract

This application mainly relates to bone conduction speaker and magnetic circuit subassembly thereof, and magnetic circuit subassembly produces first full magnetic field, includes: a first magnetic element; the lower surface of the first magnetic conduction element is connected with the upper surface of the first magnetic element; the lower surface of the fifth magnetic element is connected with the upper surface of the first magnetic conduction element; the lower surface of the third magnetic conduction element is connected with the upper surface of the fifth magnetic element; the sixth magnetic element surrounds the fifth magnetic element and is connected with the fifth magnetic element and the third magnetic conductive element; the voice coil of the bone conduction loudspeaker is positioned on one side of the lower surface of the sixth magnetic element, which is away from the upper surface, the lower surface of the sixth magnetic element is arranged between the upper surface and the lower surface of the fifth magnetic element in the interval direction between the upper surface and the lower surface of the first magnetic element, and the included angle between the magnetization direction of the sixth magnetic element and the magnetization direction of the first magnetic element is between 45 degrees and 135 degrees, so that the magnetic field intensity of the first full magnetic field at the magnetic gap is improved.

Description

Bone conduction loudspeaker and magnetic circuit assembly thereof

The application is a divisional application of China patent application with the name of "a bone conduction speaker" which is filed by China patent office with the application number of 201811056052.5 on the date of 2018, 09 and 11.

The parent application claims priority from chinese application No.201810015581.4 filed on 1.08 in 2018, the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to bone conduction speakers, and more particularly to magnetic circuit assemblies in bone conduction speakers.

Background

The bone conduction speaker can convert the electric signal into a mechanical vibration signal and conduct the vibration signal into the cochlea through human tissues and bones, so that the user can hear the sound. Compared with an air conduction loudspeaker, the air conduction loudspeaker drives air to vibrate through the vibrating diaphragm to generate sound, and the bone conduction vibration loudspeaker needs to drive soft tissues and bones of a user to vibrate, so that the required mechanical power is high. Increasing the sensitivity of bone conduction speakers can result in higher efficiency in the conversion of electrical energy to mechanical energy and thus greater mechanical power output. Increasing sensitivity is more important for bone conduction speakers with higher power requirements.

Disclosure of Invention

The embodiment of the application provides a magnetic circuit assembly of bone conduction speaker, and magnetic circuit assembly produces first full magnetic field, and magnetic circuit assembly includes: a first magnetic element; the lower surface of the first magnetic conduction element is connected with the upper surface of the first magnetic element; the lower surface of the fifth magnetic element is connected with the upper surface of the first magnetic conduction element; the lower surface of the third magnetic conduction element is connected with the upper surface of the fifth magnetic element; a sixth magnetic element surrounding the fifth magnetic element and connected to the fifth magnetic element and the third magnetic conductive element; the voice coil of the bone conduction speaker is located at one side of the lower surface of the sixth magnetic element, which is away from the upper surface, and the lower surface of the sixth magnetic element is located between the upper surface and the lower surface of the fifth magnetic element in the interval direction between the upper surface and the lower surface of the first magnetic element, and an included angle between the magnetization direction of the sixth magnetic element and the magnetization direction of the first magnetic element is between 45 degrees and 135 degrees.

The application also provides a bone conduction speaker, bone conduction speaker includes: a vibration assembly including a voice coil and at least one vibration plate; and the magnetic circuit assembly described in the above embodiments.

The beneficial effects of this application are: the magnetic circuit assembly can improve the magnetic field intensity of the first full magnetic field at the magnetic gap.

Additional features of the present application will be set forth in part in the description which follows. Additional features will be set forth in part in the description which follows, and in part will become apparent to those having ordinary skill in the art upon examination of the following and the accompanying drawings or may be learned from production or operation of the embodiments. The features disclosed in this application may be implemented and realized in the practice or use of the various methods, instrumentalities and combinations of the specific embodiments described below.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not limit the application. Like reference symbols in the various drawings indicate like elements.

Fig. 1 is a block diagram of a bone conduction speaker according to some embodiments of the present application;

Fig. 2 is a schematic longitudinal section of a bone conduction speaker according to some embodiments of the present application;

FIG. 3A is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 3B is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 3C is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 3D is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 3E is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 3F is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 3G is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4A is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4B is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4C is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4D is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4E is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4F is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4G is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4H is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 4I is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 5A is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 5B is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 5C is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 5D is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 5E is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 5F is a schematic longitudinal cross-sectional view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 6A is a schematic cross-sectional view of a magnetic element according to some embodiments of the present application;

FIG. 6B is a schematic diagram of a magnetic element according to some embodiments of the present application;

FIG. 6C is a schematic diagram illustrating the magnetization direction of a magnetic element in a magnetic circuit assembly according to some embodiments of the present application;

FIG. 6D is a magnetic induction profile of a magnetic element in a magnetic assembly according to some embodiments of the present application;

FIG. 7A is a schematic diagram of a magnetic circuit assembly according to some embodiments of the present application;

7B-7E are graphs showing driving force coefficients at a voice coil versus parameters of the magnetic circuit assembly shown in FIG. 7A, according to some embodiments of the present application;

FIG. 8A is a schematic diagram of a magnetic circuit assembly according to some embodiments of the present application;

FIGS. 8B-8E are graphs showing driving force coefficients at a voice coil versus parameters of the magnetic circuit assembly shown in FIG. 8A, according to some embodiments of the present application;

FIG. 9A is a schematic diagram of a magnetic induction line distribution of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 9B is a plot of magnetic induction at a voice coil versus thickness of various components of the magnetic circuit assembly shown in FIG. 9A, according to some embodiments of the present application;

FIG. 10A is a schematic diagram of a magnetic induction line distribution of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 10B is a plot of magnetic induction at a voice coil versus thickness of various components of the magnetic circuit assembly shown in FIG. 10A, according to some embodiments of the present application;

FIG. 11A is a schematic diagram of a magnetic induction line distribution of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 11B is a plot of magnetic induction versus magnetic element thickness for the magnetic circuit assembly of FIGS. 9A, 10A and 11A according to some embodiments of the present application;

FIG. 11C is a plot of magnetic induction at a voice coil versus thickness of various components of the magnetic circuit assembly shown in FIG. 11A, according to some embodiments of the present application;

FIG. 12A is a schematic structural view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 12B is a graph of the inductive reactance of a voice coil versus the conductive element of the magnetic circuit assembly of FIG. 12A, according to some embodiments of the present application;

FIG. 13A is a schematic structural view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 13B is a graph of the inductive reactance of a voice coil versus the conductive element of the magnetic circuit assembly of FIG. 13A, according to some embodiments of the present application;

FIG. 14A is a schematic structural view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 14B is a graph of the inductive reactance of a voice coil versus the number of conductive elements in the magnetic circuit assembly shown in FIG. 14A, according to some embodiments of the present application;

FIG. 15A is a schematic structural view of a magnetic circuit assembly according to some embodiments of the present application;

FIG. 15B is a graph of amperage applied to a voice coil versus thickness of various components of the magnetic circuit assembly of FIG. 15A according to some embodiments of the present application;

fig. 16 is a schematic diagram of a bone conduction speaker according to some embodiments of the present application;

fig. 17 is a schematic diagram of a bone conduction speaker according to some embodiments of the present application;

fig. 18 is a schematic diagram of a bone conduction speaker according to some embodiments of the present application; and

fig. 19 is a schematic diagram of a bone conduction speaker according to some embodiments of the present application.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are used in the description of the embodiments will be briefly described below. It is apparent that the drawings in the following description are only some examples or embodiments of the present application, and it is obvious to those skilled in the art that the present application may be applied to other similar situations according to the drawings without inventive effort. It should be understood that these exemplary embodiments are presented merely to enable those skilled in the relevant art to better understand and practice the invention and are not intended to limit the scope of the invention in any way. Unless otherwise apparent from the context of the language or otherwise specified, like reference numerals in the figures refer to like structures or operations.

As used in this application and in the claims, the terms "a," "an," "the," and/or "the" are not specific to the singular, but may include the plural, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and they do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus. The term "based on" is based at least in part on. The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment". Related definitions of other terms will be given in the description below. Hereinafter, without loss of generality, in describing the bone conduction related art in the present invention, a description of "bone conduction speaker" or "bone conduction earphone" will be employed. The description is only one form of bone conduction application, and it will be appreciated by those of ordinary skill in the art that the "speaker" or "earpiece" may be replaced by other similar terms, such as "player", "hearing aid", etc. Indeed, various implementations of the invention may be readily applied to other non-speaker-like hearing devices. For example, it will be apparent to those skilled in the art that various modifications and changes in form and details of the specific manner and procedure of implementing the bone conduction speaker, and in particular the addition of ambient sound pick-up and processing functions to the bone conduction speaker, may be made without departing from the basic principles of the bone conduction speaker, thereby enabling the speaker to function as a hearing aid. For example, a microphone such as a microphone may pick up sound from the user/wearer's surroundings and, under certain algorithms, transmit the sound processed (or generated electrical signals) to the bone conduction speaker portion. That is, the bone conduction speaker can be modified to have a function of picking up environmental sound, and transmit the sound to the user/wearer through the bone conduction speaker portion after a certain signal processing, thereby realizing the function of the bone conduction hearing aid. By way of example, the algorithms described herein may include one or more combinations of noise cancellation, automatic gain control, acoustic feedback suppression, wide dynamic range compression, active environment recognition, active noise immunity, directional processing, tinnitus processing, multi-channel wide dynamic range compression, active howling suppression, volume control, and the like.

The application provides a bone conduction speaker of high sensitivity. In some embodiments, the bone conduction speaker may include a magnetic circuit assembly. The magnetic circuit assembly may generate a first full magnetic field. The magnetic circuit assembly may include a first magnetic element, a first magnetically permeable element, a second magnetically permeable element, and one or more second magnetic elements. The first magnetic element may generate a second magnetic field, the one or more second magnetic elements surrounding the first magnetic element and forming a magnetic gap with the first magnetic element, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. The second magnetic elements in the magnetic circuit assembly encircle the first magnetic elements, so that the volume and the weight of the magnetic circuit assembly are reduced, the efficiency of the bone conduction speaker is improved, and the service life of the bone conduction speaker is prolonged under the conditions of improving the magnetic field strength of a magnetic gap and improving the sensitivity of the bone conduction speaker.

The bone conduction speaker has the characteristics of small size, light weight, high efficiency, high sensitivity, long service life and the like, and is convenient to combine with the wearable intelligent device, so that the multifunctionalization of single device is realized, and the user experience is improved and optimized. The wearable smart devices include, but are not limited to, smart headphones, smart glasses, smart headbands, smart helmets, smart watches, smart gloves, smart shoes, smart cameras, smart video cameras, and the like. The bone conduction speaker may further be combined with smart materials, integrating bone conduction speakers in the manufacturing materials of the user's clothing, gloves, hats, shoes, etc. The bone conduction speaker can be further implanted into a human body, and can realize more personalized functions in cooperation with a human body implanted chip or an external processor.

Fig. 1 is a block diagram of a bone conduction speaker 100 according to some embodiments of the present application. As illustrated, bone conduction speaker 100 may include a magnetic circuit assembly 102, a vibration assembly 104, a support assembly 106, and a storage assembly 108.

The magnetic circuit assembly 102 may provide a magnetic field. The magnetic field may be used to convert a signal containing acoustic information into a vibration signal. In some embodiments, the sound information may include video, audio files having a particular data format, or data or files that may be converted to sound by a particular means. The signal containing the audio information may be from the memory component 108 of the bone conduction speaker 100 itself, or from a system other than the bone conduction speaker 100 for generating, storing, or transmitting information. The signal containing the acoustic information may include one or more combinations of electrical signals, optical signals, magnetic signals, mechanical signals, and the like. The signal containing the sound information may come from one signal source or a plurality of signal sources. The plurality of signal sources may or may not be correlated. In some embodiments, bone conduction speaker 100 may acquire the signal containing the acoustic information in a number of different ways, either wired or wireless, and may be real-time or delayed. For example, bone conduction speaker 100 may receive electrical signals containing audio information via wired or wireless means, or may obtain data directly from a storage medium (e.g., storage component 108) to generate an audio signal. As another example, a bone conduction hearing aid may include components with sound collection capabilities that convert mechanical vibrations of sound into electrical signals by picking up the sound in the environment, and then processing the signals with an amplifier to obtain electrical signals that meet specific requirements. In some embodiments, the wired connection may include a metallic cable, an optical cable, or a hybrid metallic and optical cable, such as, for example, a coaxial cable, a communications cable, a flex cable, a spiral cable, a nonmetallic sheath cable, a metallic sheath cable, a multi-core cable, a twisted pair cable, a ribbon cable, a shielded cable, a telecommunications cable, a twinax cable, parallel twinax wires, twisted pair wires, or the like. The above described examples are for convenience of illustration only, and the medium of the wired connection may be of other types, such as other transmission carriers of electrical or optical signals, etc.

The wireless connection may include radio communication, free space optical communication, acoustic communication, electromagnetic induction, and the like. Wherein the radio communications may include IEEE1002.11 series standards, IEEE1002.15 series standards (e.g., bluetooth technology, zigbee technology, etc.), first generation mobile communications technologies, second generation mobile communications technologies (e.g., FDMA, TDMA, SDMA, CDMA, SSMA, etc.), general packet radio service technologies, third generation mobile communications technologies (e.g., CDMA2000, WCDMA, TD-SCDMA, wiMAX, etc.), fourth generation mobile communications technologies (e.g., TD-LTE, FDD-LTE, etc.), satellite communications (e.g., GPS technology, etc.), near Field Communications (NFC), and other technologies operating in the ISM band (e.g., 2.4GHz, etc.); free space optical communications may include visible light, infrared signals, and the like; the acoustic communication may include acoustic waves, ultrasonic signals, etc.; electromagnetic induction may include near field communication techniques, and the like. The above described examples are for convenience of illustration only and the medium of the wireless connection may also be of other types, e.g. Z-wave technology, other charged civilian and military radio bands, etc. For example, as some application scenarios of the present technology, bone conduction speaker 100 may obtain signals containing sound information from other devices through bluetooth technology.

The vibration assembly 104 may generate mechanical vibrations. The generation of the vibrations is accompanied by energy conversion, and bone conduction speaker 100 may use specific magnetic circuit assembly 102 and vibration assembly 104 to effect conversion of signals containing acoustic information into mechanical vibrations. The process of conversion may involve the coexistence and conversion of a variety of different types of energy. For example, the electrical signal may be directly converted into mechanical vibrations by a transducer means, producing sound. For another example, sound information may be included in the optical signal and a particular transducer device may perform the conversion from the optical signal to a vibration signal. Other types of energy that may coexist and be converted during operation of the transducer include thermal energy, magnetic field energy, and the like. The energy conversion modes of the energy conversion device can comprise moving coil type, electrostatic type, piezoelectric type, moving iron type, pneumatic type, electromagnetic type and the like. The frequency response range and sound quality of bone conduction speaker 100 may be affected by vibration assembly 104. For example, in the moving coil transducer device, the vibration assembly 104 includes a wound columnar coil and a vibrator (e.g., a vibrating reed), and the columnar coil driven by the signal current drives the vibrator to vibrate in the magnetic field to generate sound, so that the stretching and shrinking of the material of the vibrator, the deformation, the size, the shape and the fixing manner of the wrinkles, the magnetic density of the permanent magnet, etc. have a great influence on the sound quality of the bone conduction speaker 100. The vibrating body in the vibrating assembly 104 may be a mirror symmetrical structure, a center symmetrical structure, or an asymmetrical structure; the vibration body can be provided with a discontinuous hole-shaped structure, so that the vibration body generates larger displacement, the bone conduction loudspeaker realizes higher sensitivity, and the output power of vibration and sound is improved; the vibrator may be a ring body structure, and a plurality of struts which are converged toward the center are arranged in the ring body, and the number of struts may be two or more.

The support assembly 106 may support the magnetic circuit assembly 102, the vibration assembly 104, and/or the storage assembly 108. The support assembly 106 may include one or more housings, one or more connectors. The one or more housings may form an accommodation space for accommodating the magnetic circuit assembly 102, the vibration assembly 104, and/or the storage assembly 108. The one or more connectors may connect the housing with the magnetic circuit assembly 102, the vibration assembly 104, and/or the storage assembly 108.

The storage component 108 can store signals containing audio information. In some embodiments, the storage component 108 may include one or more storage devices. The storage devices may include storage devices on storage systems such as direct attached storage (Direct Attached Storage), network attached storage (Network Attached Storage), and storage area networks (Storage Area Network). The storage devices may include various types of storage devices such as solid state storage devices (solid state drives, solid state hybrid drives, etc.), mechanical hard drives, USB flash memory, memory sticks, memory cards (e.g., CF, SD, etc.), other drives (e.g., CD, DVD, HD DVD, blu-ray, etc.), random Access Memory (RAM), and Read Only Memory (ROM). Wherein RAM may include a decimal counter, a selector, a delay line memory, a williams tube, a Dynamic Random Access Memory (DRAM), a Static Random Access Memory (SRAM), a thyristor random access memory (T-RAM), a zero capacitance random access memory (Z-RAM), and the like; ROM may include bubble memory, button wire memory, thin film memory plating line memory, magnetic core memory, magnetic drum memory, optical disk drive, hard disk magnetic tape, early NVRAM (nonvolatile memory), phase change memory, magnetoresistive RAM, ferroelectric RAM, nonvolatile SRAM flash memory, EEPROM, PROM, shielded heap read memory, floating gate RAM, nanometer RAM, racetrack memory, variable resistance memory, programmable metallization cell, etc. The above-mentioned storage devices/storage units are examples, and storage devices that can be used for the storage devices/storage units are not limited thereto.

The above description of bone conduction speaker structures is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the bone conduction speaker may be made without departing from this principle, but remain within the scope of the above description. For example, bone conduction speaker 100 may include one or more processors that may execute one or more sound signal processing algorithms. The sound signal processing algorithm may modify or enhance the sound signal. Such as noise reduction, acoustic feedback suppression, wide dynamic range compression, automatic gain control, active environment recognition, active noise immunity, directional processing, tinnitus processing, multi-channel wide dynamic range compression, active howling suppression, volume control, or the like, or any combination thereof, while remaining within the scope of the claimed invention. As another example, bone conduction speaker 100 may include one or more sensors, such as a temperature sensor, a humidity sensor, a speed sensor, a displacement sensor, and the like. The sensor may collect user information or environmental information.

Fig. 2 is a schematic longitudinal section of a bone conduction speaker 200 according to some embodiments of the present application. As shown, bone conduction speaker 200 may include a first magnetic element 202, a first magnetically permeable element 204, a second magnetically permeable element 206, a first diaphragm 208, a voice coil 210, a second diaphragm 212, and a vibration panel 214.

The magnetic element described in the present application refers to an element that can generate a magnetic field, such as a magnet or the like. The magnetic element may have a magnetization direction, which refers to a direction of a magnetic field inside the magnetic element. The first magnetic element 202 may include one or more magnets. In some embodiments, the magnets may include metal alloy magnets, ferrites, and the like. The metal alloy magnets may include neodymium iron boron, samarium cobalt, alnico, iron chromium cobalt, alfeb, iron carbon aluminum, or the like, or combinations thereof. The ferrite may include barium ferrite, steel ferrite, manganese ferrite, lithium manganese ferrite, or the like, or various combinations thereof.

The lower surface of the first magnetically permeable element 204 may be coupled to the upper surface of the first magnetic element 202. The second magnetically permeable element 206 may be coupled to the first magnetic element 202. It should be noted that the magnetizer referred to herein may also be referred to as a magnetic field concentrator or core. The magnetizer can adjust the distribution of a magnetic field (e.g., the magnetic field generated by the first magnetic element 202). The magnetic conductor may comprise an element machined from a soft magnetic material. In some embodiments, the soft magnetic material may include a metal material, a metal alloy, a metal oxide material, an amorphous metal material, or the like, such as iron, a ferrosilicon-based alloy, a ferroaluminum-based alloy, a nickel-iron-based alloy, a ferrocobalt-based alloy, a low carbon steel, a silicon steel sheet, ferrite, or the like. In some embodiments, the magnetic conductor may be machined by one or more combination of casting, plastic working, cutting, powder metallurgy, and the like. Casting may include sand casting, investment casting, pressure casting, centrifugal casting, and the like; plastic working may include one or more combinations of rolling, casting, forging, stamping, extruding, drawing, etc.; the cutting process may include turning, milling, planing, grinding, and the like. In some embodiments, the method of machining the magnetizer may include 3D printing, numerically controlled machine tools, and the like. The connection between the first magnetically permeable element 204, the second magnetically permeable element 206, and the first magnetic element 202 may include one or more of bonding, clamping, welding, riveting, bolting, etc. In some embodiments, the first magnetic element 202, the first magnetic conductive element 204, and the second magnetic conductive element 206 may be disposed in an axisymmetric configuration. The axisymmetric structure may be a ring structure, a column structure, or other structures having axisymmetry.

In some embodiments, a magnetic gap may be formed between the first magnetic element 202 and the second magnetic conductive element 206. Voice coil 210 may be disposed in the magnetic gap. The voice coil 210 may be connected to the first diaphragm 208. The first vibration plate 208 may be connected to the second vibration plate 212, and the second vibration plate 212 may be connected to the vibration panel 214. When a current is applied to the voice coil 210, the voice coil 210 is positioned in a magnetic field formed by the first magnetic element 202, the first magnetic conductive element 214 and the second magnetic conductive element 206, and is subjected to an ampere force, and the ampere force drives the voice coil 210 to vibrate, so that the vibration of the voice coil 210 drives the vibration of the first vibration plate 208, the second vibration plate 212 and the vibration panel 214. The vibration panel 214 transmits the vibrations through tissue and bone to the auditory nerve, thereby allowing the person to hear the sound. The vibration panel 214 may be in direct contact with the skin of the human body or may be in contact with the skin through a vibration transmission layer composed of a specific material.

In some embodiments, for bone conduction speakers with a single magnetic element, the magnetic induction lines through the voice coil are not uniform, diverging. Meanwhile, magnetic leakage can be formed in the magnetic circuit, namely more magnetic induction wires leak out of the magnetic gap and cannot pass through the voice coil, so that the magnetic induction intensity (or magnetic field intensity) at the position of the voice coil is reduced, and the sensitivity of the bone conduction loudspeaker is affected. Accordingly, bone conduction speaker 200 may further include at least one second magnetic element and/or at least one third magnetic conductive element (not shown). The at least one second magnetic element and/or the at least one third magnetic element may inhibit leakage of the magnetic induction lines, restrict the form of the magnetic induction lines passing through the voice coil, so that more magnetic induction lines pass through the voice coil as horizontally and densely as possible, and enhance magnetic induction (or magnetic field strength) at the position of the voice coil, thereby improving sensitivity of the bone conduction speaker 200 and further improving mechanical conversion efficiency of the bone conduction speaker 200 (i.e., efficiency of converting electric energy input into the bone conduction speaker 200 into mechanical energy of vibration of the voice coil). For further description of the at least one second magnetic element, see fig. 3A-3G, 4A-4I and/or 5A-5F.

The above description of the structure of bone conduction speaker 200 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the bone conduction speaker may be made without departing from this principle, but remain within the scope of the above description. For example, bone conduction speaker 200 may include a housing, a connector, and the like. The connector may connect the vibration panel 214 with the housing. For another example, bone conduction speaker 200 may include a second magnetic element that may be coupled to first magnetically permeable element 204. For another example, bone conduction speaker 200 may further include one or more annular magnetic elements that may be coupled to second magnetically permeable element 206.

Fig. 3A is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3100, according to some embodiments of the present application. As shown in fig. 3A, magnetic circuit assembly 3100 may include a first magnetic element 302, a first magnetically permeable element 304, a second magnetically permeable element 306, and a second magnetic element 308. In some embodiments, the first magnetic element 302 and/or the second magnetic element 308 may include any one or more of the magnets described herein. In some embodiments, the first magnetic element 302 may include a first magnet and the second magnetic element 308 may include a second magnet, which may be the same or different from the first magnet. The first magnetically permeable element 304 and/or the second magnetically permeable element 306 may comprise any one or more of the magnetically permeable materials described herein. The method of machining the first magnetically permeable element 304 and/or the second magnetically permeable element 306 may include any one or more of the methods described herein. In some embodiments, the first magnetic element 302 and/or the first magnetically permeable element 304 may be disposed in an axisymmetric configuration. For example, the first magnetic element 302 and/or the first magnetically permeable element 304 may be a cylinder, a cuboid, or a hollow ring (e.g., racetrack shaped in cross-section). In some embodiments, the first magnetic element 302 and the first magnetically permeable element 304 may be coaxial cylinders, containing the same or different diameters. In some embodiments, the second magnetically permeable element 306 may be a groove-type structure. The groove-type structure may comprise a U-shaped cross-section (as shown in fig. 3A). The second magnetically permeable element 306 may include a bottom plate and a side wall. In some embodiments, the base plate and the side walls may be integrally formed, for example, the side walls may be formed from the base plate extending in a direction perpendicular to the base plate. In some embodiments, the bottom panel may be connected to the side walls by any one or more of the connections described herein. The second magnetic element 308 may be configured in a ring or a sheet. Reference may be made to the descriptions elsewhere in the specification regarding the shape of the second magnetic element 308 (e.g., fig. 5A and 5B and their associated descriptions). In some embodiments, the second magnetic element 308 may be coaxial with the first magnetic element 302 and/or the first magnetically permeable element 304.

The upper surface of the first magnetic element 302 may be connected to the lower surface of the first magnetic element 304. The lower surface of the first magnetic element 302 may be connected to the bottom plate of the second magnetic element 306. The lower surface of the second magnetic element 308 is connected to the sidewall of the second magnetic element 306. The connection between the first magnetic element 302, the first magnetic element 304, the second magnetic element 306, and/or the second magnetic element 308 may include one or more combinations of bonding, clamping, welding, riveting, bolting, etc.

A magnetic gap is formed between the first magnetic element 302 and/or the first magnetically permeable element 304 and the inner ring of the second magnetic element 308. A voice coil 328 may be disposed in the magnetic gap. In some embodiments, the second magnetic element 308 and the voice coil 328 are at the same height relative to the bottom plate of the second magnetic element 306. In some embodiments, the first magnetic element 302, the first magnetically permeable element 304, the second magnetically permeable element 306, and the second magnetic element 308 may form a magnetic circuit. In some embodiments, magnetic circuit assembly 3100 may generate a first full magnetic field (which may also be referred to as a "total magnetic field of the magnetic circuit assembly"), and first magnetic element 302 may generate a second magnetic field. The first full magnetic field is formed by magnetic fields generated by all components (e.g., first magnetic element 302, first magnetic element 304, second magnetic element 306, and second magnetic element 308) in magnetic circuit assembly 3100. The magnetic field strength (which may also be referred to as magnetic induction or magnetic flux density) of the first full magnetic field within the magnetic gap is greater than the magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the second magnetic element 308 may generate a third magnetic field that may increase the magnetic field strength of the first full magnetic field at the magnetic gap. The third magnetic field increasing the magnetic field strength of the first full magnetic field as referred to herein means that the first full magnetic field is greater in the magnetic gap when the third magnetic field is present (i.e., the second magnetic element 308 is present) than when the third magnetic field is absent (i.e., the second magnetic element 308 is absent). In other embodiments in this specification, unless otherwise specified, the magnetic circuit assembly represents a structure including all magnetic elements and magnetically conductive elements, the first full magnetic field represents the magnetic field generated by the magnetic circuit assembly as a whole, and the second, third, … …, and nth magnetic fields represent the magnetic fields generated by the respective magnetic elements, respectively. In different embodiments, the magnetic elements that generate the second magnetic field (or third magnetic field, … …, nth magnetic field) may be the same or different.

In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the second magnetic element 308 is between 0 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the second magnetic element 308 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the second magnetic element 308 is equal to or greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 302 is vertically upward (as shown in the a direction) perpendicular to the lower or upper surface of the first magnetic element 302, and the magnetization direction of the second magnetic element 308 is directed from the inner ring to the outer ring of the second magnetic element 308 (as shown in the b direction, on the right side of the first magnetic element 302, the magnetization direction of the first magnetic element 302 is deflected 90 degrees in the clockwise direction).

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the second magnetic element 308 is no more than 90 degrees at the location of the second magnetic element 308. In some embodiments, the angle between the direction of the magnetic field generated by the first magnetic element 302 and the direction of magnetization of the second magnetic element 308 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, etc., at the location of the second magnetic element 308.

The second magnetic element 308 may increase the total magnetic flux in the magnetic gap of the magnetic circuit assembly 3100, and thus increase the magnetic induction in the magnetic gap, as compared to a single magnetic element magnetic circuit assembly. Under the action of the second magnetic element 308, the originally divergent magnetic induction lines converge toward the position of the magnetic gap, so as to further increase the magnetic induction intensity in the magnetic gap.

The above description of the structure of magnetic circuit assembly 3100 is merely a specific example and should not be considered the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 3100 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, magnetic circuit assembly 3100 may further include a magnetically permeable cover that may surround first magnetic element 302, first magnetically permeable element 304, second magnetically permeable element 306, and second magnetic element 308.

Fig. 3B is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3200, according to some embodiments of the present disclosure. As shown in fig. 3B, unlike magnetic circuit assembly 3100, magnetic circuit assembly 3200 may further include a third magnetic element 310.

The third magnetic element 310 has an upper surface connected to the second magnetic element 308 and a lower surface connected to a sidewall of the second magnetic element 306. A magnetic gap may be formed between the first magnetic element 302, the first magnetically permeable element 304, the second magnetic element 308, and/or the third magnetic element 310. A voice coil 328 may be disposed in the magnetic gap. In some embodiments, the first magnetic element 302, the first magnetic conductive element 304, the second magnetic conductive element 306, the second magnetic element 308, and the third magnetic element 310 may form a magnetic circuit. In some embodiments, the magnetization direction of the second magnetic element 308 may be as described in detail with reference to fig. 3A of the present application.

In some embodiments, magnetic circuit assembly 3200 may generate a first full magnetic field and first magnetic element 302 may generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the third magnetic element 310 may generate a third magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the third magnetic element 310 is between 0 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the third magnetic element 310 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the third magnetic element 310 is equal to or greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 302 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 302, and the magnetization direction of the third magnetic element 310 is directed from the upper surface of the third magnetic element 310 to the lower surface (as shown in the direction of c, on the right side of the first magnetic element 302, the magnetization direction of the first magnetic element 302 is deflected 180 degrees in a clockwise direction).

In some embodiments, at the location of the third magnetic element 310, the angle between the direction of the first full magnetic field and the magnetization direction of the third magnetic element 310 is no more than 90 degrees. In some embodiments, at the location of the third magnetic element 310, the angle between the direction of the magnetic field generated by the first magnetic element 302 and the direction of magnetization of the third magnetic element 310 may be less than or equal to 90 degrees, 0 degrees, 10 degrees, 20 degrees, etc.

Magnetic circuit assembly 3200 further adds third magnetic element 310 as compared to magnetic circuit assembly 3100. Third magnetic element 310 may further increase the total magnetic flux within the magnetic gap in magnetic circuit assembly 3200, thereby increasing the magnetic induction in the magnetic gap. Under the action of the third magnetic element 310, the magnetic induction line further converges toward the position of the magnetic gap, and the magnetic induction intensity in the magnetic gap is further increased.

The above description of the structure of magnetic circuit assembly 3200 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, having the benefit of the basic principles of the magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing magnetic circuit assembly 3200 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, magnetic circuit assembly 3200 may not include second magnetically permeable element 306. For another example, magnetic circuit assembly 3200 may further incorporate at least one magnetic element. In some embodiments, the lower surface of the further added magnetic element may be connected to the upper surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is opposite to the magnetization direction of the third magnetic element 312. In some embodiments, the further added magnetic element may connect the sidewalls of the first magnetic element 302 and the second magnetically permeable element 306. The magnetization direction of the further added magnetic element is opposite to the magnetization direction of the second magnetic element 308.

Fig. 3C is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3300, according to some embodiments of the present application. As shown in fig. 3C, unlike magnetic circuit assembly 3100, magnetic circuit assembly 3300 can further include fourth magnetic element 312.

The fourth magnetic element 312 may be attached to the sidewalls of the first magnetic element 302 and the second magnetic element 306 by one or more combinations of bonding, clamping, welding, riveting, bolting, etc. In some embodiments, the first magnetic element 302, the first magnetic conductive element 304, the second magnetic conductive element 306, the second magnetic element 308, and the fourth magnetic element 312 may form a magnetic gap. In some embodiments, the magnetization direction of the second magnetic element 308 may be as described in detail with reference to fig. 3A of the present application.

In some embodiments, magnetic circuit assembly 3300 may generate a first full magnetic field and first magnetic element 302 may generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the fourth magnetic element 312 may generate a fourth magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the fourth magnetic element 312 is between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the fourth magnetic element 312 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the fourth magnetic element 312 is no greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 302 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 302, and the magnetization direction of the fourth magnetic element 312 is directed from the outer ring of the fourth magnetic element 312 to the inner ring (as shown in the direction d, on the right side of the first magnetic element 302, the magnetization direction of the first magnetic element 302 is deflected 270 degrees in the clockwise direction).

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the fourth magnetic element 312 is no more than 90 degrees at the location of the fourth magnetic element 312. In some embodiments, at the location of the fourth magnetic element 312, the angle between the direction of the magnetic field generated by the first magnetic element 302 and the magnetization direction of the fourth magnetic element 312 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, etc.

The magnetic circuit assembly 3300 further adds fourth magnetic element 312 as compared to magnetic circuit assembly 3100. Fourth magnetic element 312 may further increase the total magnetic flux within the magnetic gap in magnetic circuit assembly 3300, thereby increasing the magnetic induction in the magnetic gap. Under the action of the fourth magnetic element 312, the magnetic induction line further converges toward the position of the magnetic gap, and the magnetic induction intensity in the magnetic gap is further increased.

The above description of the structure of the magnetic circuit assembly 3300 is merely a specific example and should not be considered the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 3300 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, magnetic circuit assembly 3300 may not include second magnetic element 308. For another example, magnetic circuit assembly 3300 may further incorporate at least one magnetic element. In some embodiments, the lower surface of the further added magnetic element may be connected to the upper surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is the same as the magnetization direction of the first magnetic element 302. In some embodiments, the upper surface of the further added magnetic element may be connected to the lower surface of the second magnetic element 308. The magnetization direction of the magnetic elements is opposite to the magnetization direction of the first magnetic element 302.

Fig. 3D is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3400, according to some embodiments of the present application. As shown in fig. 3D, unlike magnetic circuit assembly 3100, magnetic circuit assembly 3400 may further include a fifth magnetic element 314. Fifth magnetic element 314 may comprise any of the magnet materials described herein. In some embodiments, fifth magnetic element 314 may be disposed in an axisymmetric configuration. For example, the fifth magnetic element 314 may be a cylinder, a cuboid, or a hollow ring (e.g., racetrack shaped in cross-section). In some embodiments, the first magnetic element 302, the first magnetic conductive element 304, and/or the fifth magnetic element 314 may be coaxial cylinders containing the same or different diameters. The thickness of the fifth magnetic element 314 may be the same as or different from the thickness of the first magnetic element 302. The fifth magnetic element 314 may be coupled to the first magnetically permeable element 304.

In some embodiments, the angle between the magnetization direction of the fifth magnetic element 314 and the magnetization direction of the first magnetic element 302 is between 90 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the fifth magnetic element 314 and the magnetization direction of the first magnetic element 302 is between 150 degrees and 180 degrees. In some embodiments, the magnetization direction of the fifth magnetic element 314 is opposite to the magnetization direction of the first magnetic element 302 (as shown, the a-direction and the e-direction).

The magnetic circuit assembly 3400 further adds a fifth magnetic element 314 as compared to the magnetic circuit assembly 3100. The fifth magnetic element 314 can inhibit the magnetic leakage of the first magnetic element 302 in the magnetic circuit assembly 3400 in the magnetization direction, so that the magnetic field generated by the first magnetic element 302 can be more compressed into the magnetic gap, thereby improving the magnetic induction intensity in the magnetic gap.

The above description of the structure of the magnetic circuit assembly 3400 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 3400 may be made without departing from this principle, but such modifications and changes remain within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, the magnetic circuit assembly 3400 may not include the second magnetic element 308. For another example, the magnetic circuit assembly 3400 may further add at least one magnetic element. In some embodiments, the lower surface of the further added magnetic element may be connected to the upper surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is the same as the magnetization direction of the first magnetic element 302. In some embodiments, the upper surface of the further added magnetic element may be connected to the lower surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is opposite to the magnetization direction of the first magnetic element 302. In some embodiments, the further added magnetic element may connect the first magnetic element 302 and the second magnetic element 306, with the further added magnetic element having a magnetization direction opposite to the magnetization direction of the second magnetic element 308.

Fig. 3E is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3500 shown in accordance with some embodiments of the present application. As shown in fig. 3E, unlike magnetic circuit assembly 3400, magnetic circuit assembly 3500 may further include a third magnetically conductive element 316. In some embodiments, third magnetically permeable element 316 may comprise any one or more of the magnetically permeable materials described herein. The magnetically permeable materials included in the first magnetically permeable element 304, the second magnetically permeable element 306, and/or the third magnetically permeable element 316 may be the same or different. In some embodiments, the third magnetically permeable element 316 may be provided in a symmetrical configuration. For example, the third magnetically permeable element 316 may be a cylinder. In some embodiments, the first magnetic element 302, the first magnetic conductive element 304, the fifth magnetic conductive element 314, and/or the third magnetic conductive element 316 may be coaxial cylinders containing the same or different diameters. The third magnetically permeable element 316 may be coupled to the fifth magnetic element 314. In some embodiments, the third magnetically permeable element 316 may connect the fifth magnetic element 314 with the second magnetic element 308. The third magnetically permeable element 316, the second magnetically permeable element 306, and the second magnetic element 308 may form a cavity that may include the first magnetic element 302, the fifth magnetic element 314, and the first magnetically permeable element 304.

The magnetic circuit assembly 3500 further adds a third magnetic conductive element 316 as compared to the magnetic circuit assembly 3400. The third magnetic conductive element 316 can inhibit the magnetic leakage of the fifth magnetic element 314 in the magnetic circuit assembly 3500 in the magnetization direction, so that the magnetic field generated by the fifth magnetic element 314 can be more compressed into the magnetic gap, thereby improving the magnetic induction intensity in the magnetic gap.

The above description of the structure of magnetic circuit assembly 3500 is merely a specific example and should not be considered the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 3500 may be made without departing from this principle, while still remaining within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, magnetic circuit assembly 3500 may not include second magnetic element 308. For another example, magnetic circuit assembly 3500 may further incorporate at least one magnetic element. In some embodiments, the lower surface of the further added magnetic element may be connected to the upper surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is the same as the magnetization direction of the first magnetic element 302. In some embodiments, the upper surface of the further added magnetic element may be connected to the lower surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is opposite to the magnetization direction of the first magnetic element 302. In some embodiments, the further added magnetic element may connect the first magnetic element 302 and the second magnetic element 306, with the further added magnetic element having a magnetization direction opposite to the magnetization direction of the second magnetic element 308.

Fig. 3F is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3600, shown in accordance with some embodiments of the present application. As shown in fig. 3F, unlike magnetic circuit assembly 3100, magnetic circuit assembly 3600 can further include one or more conductive elements (e.g., first conductive element 318, second conductive element 320, and third conductive element 322).

The conductive elements may comprise metallic materials, metallic alloy materials, inorganic nonmetallic materials, or other conductive materials. The metal material may include gold, silver, copper, aluminum, etc.; the metal alloy material can comprise iron-based alloy, aluminum-based alloy material, copper-based alloy, zinc-based alloy and the like; the inorganic nonmetallic material may include graphite or the like. The conductive elements may be sheet-like, ring-like, mesh-like, etc. The first conductive element 318 may be disposed on an upper surface of the first magnetically permeable element 304. The second conductive element 320 may connect the first magnetic element 302 and the second magnetically permeable element 306. The third conductive element 322 may be connected to a sidewall of the first magnetic element 302. In some embodiments, the first magnetic conductive element 304 may protrude from the first magnetic element 302 to form a first recess, and the third conductive element 322 is disposed in the first recess. In some embodiments, the first conductive element 318, the second conductive element 320, and the third conductive element 322 may comprise the same or different conductive materials. The first conductive element 318, the second conductive element 320, and the third conductive element 322 may be coupled to the first magnetically permeable element 304, the second magnetically permeable element 306, and/or the first magnetic element 302, respectively, by any one or more of the coupling means described herein.

A magnetic gap is formed between the first magnetic element 302, the first magnetically permeable element 304, and the inner ring of the second magnetic element 308. A voice coil 328 may be disposed in the magnetic gap. The first magnetic element 302, the first magnetic conductive element 304, the second magnetic conductive element 306, and the second magnetic element 308 may form a magnetic circuit. In some embodiments, the conductive element may reduce the inductive reactance of the voice coil 328. For example, if the voice coil 328 is energized with a first alternating current, a first alternating induced magnetic field is generated in the vicinity of the voice coil 328. The first alternating induction magnetic field causes the voice coil 328 to generate inductive reactance under the action of the magnetic field in the magnetic loop, and impedes the movement of the voice coil 328. When conductive elements (e.g., first conductive element 318, second conductive element 320, and third conductive element 322) are disposed adjacent to voice coil 328, the conductive elements may induce a second alternating current under the first alternating induced magnetic field. The third alternating current in the conductive element may generate a second alternating induced magnetic field in the vicinity thereof, which is opposite to the first alternating induced magnetic field, and may weaken the first alternating induced magnetic field, thereby reducing the inductance of the voice coil 328, increasing the current in the voice coil, and improving the sensitivity of the bone conduction speaker.

The above description of the structure of the magnetic circuit assembly 3600 is merely a specific example and should not be considered the only viable embodiment. It will be apparent to those skilled in the art that various modifications and variations in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 3600 are possible without departing from this principle, and yet remain within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, the magnetic circuit assembly 3600 may not include the second magnetic element 308. For another example, magnetic circuit assembly 3500 may further incorporate at least one magnetic element. In some embodiments, the lower surface of the further added magnetic element may be connected to the upper surface of the second magnetic element 308. The magnetization direction of the further added magnetic element is the same as the magnetization direction of the first magnetic element 302.

Fig. 3G is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 3900, according to some embodiments of the present application. As shown in fig. 3G, unlike magnetic circuit assembly 3500, magnetic circuit assembly 3900 may further include third magnetic element 310, fourth magnetic element 312, fifth magnetic element 314, third magnetically permeable element 316, sixth magnetic element 324, and seventh magnetic element 326. The third, fourth, fifth, third and/or sixth magnetic elements 310, 312, 314, 316, 324, 326 may be provided as coaxial annular cylinders.

In some embodiments, an upper surface of the second magnetic element 308 is coupled to the seventh magnetic element 326 and a lower surface of the second magnetic element 308 may be coupled to the third magnetic element 310. The third magnetic element 310 may be coupled to the second magnetically permeable element 306. An upper surface of seventh magnetic element 326 may be coupled to third magnetic element 316. The fourth magnetic element 312 may connect the second magnetic element 306 and the first magnetic element 302. The sixth magnetic element 324 may connect the fifth magnetic element 314, the third magnetic element 316, and the seventh magnetic element 326. In some embodiments, the first magnetic element 302, the first magnetic element 304, the second magnetic element 306, the second magnetic element 308, the third magnetic element 310, the fourth magnetic element 312, the fifth magnetic element 314, the third magnetic element 316, the sixth magnetic element 324, and the seventh magnetic element 326 may form a magnetic circuit and a magnetic gap.

In some embodiments, the magnetization direction of the second magnetic element 308 may refer to the detailed description of fig. 3A of the present application, the magnetization direction of the third magnetic element 310 may refer to the detailed description of fig. 3B of the present application, and the magnetization direction of the fourth magnetic element 312 may refer to the detailed description of fig. 3C of the present application.

In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the sixth magnetic element 324 may be between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the sixth magnetic element 324 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the sixth magnetic element 324 is no greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 302 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 302, and the magnetization direction of the sixth magnetic element 324 is directed from the outer ring of the sixth magnetic element 324 to the inner ring (as shown in the direction of g, on the right side of the first magnetic element 302, the magnetization direction of the first magnetic element 302 is deflected 270 degrees in a clockwise direction). In some embodiments, the magnetization direction of the sixth magnetic element 324 may be the same as the magnetization direction of the fourth magnetic element 312 in the same vertical direction.

In some embodiments, the angle between the direction of the magnetic field generated by magnetic circuit assembly 3900 and the direction of magnetization of sixth magnetic element 324 is no more than 90 degrees at the location of sixth magnetic element 324. In some embodiments, the angle between the direction of the magnetic field generated by the first magnetic element 302 and the magnetization direction of the sixth magnetic element 324 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, etc., at the location of the sixth magnetic element 324.

In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the seventh magnetic element 326 may be between 0 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the seventh magnetic element 326 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 302 and the magnetization direction of the seventh magnetic element 326 is no greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 302 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 302, and the magnetization direction of the seventh magnetic element 326 is directed from the lower surface of the seventh magnetic element 326 to the upper surface (as shown in the direction f, on the right side of the first magnetic element 302, the magnetization direction of the first magnetic element 302 is deflected 360 degrees in a clockwise direction). In some embodiments, the magnetization direction of seventh magnetic element 326 may be opposite to the magnetization direction of third magnetic element 310.

In some embodiments, at seventh magnetic element 326, the angle between the direction of the magnetic field generated by magnetic circuit assembly 3900 and the direction of magnetization of seventh magnetic element 326 is no more than 90 degrees. In some embodiments, at the location of seventh magnetic element 326, the angle between the direction of the magnetic field generated by first magnetic element 302 and the direction of magnetization of seventh magnetic element 326 may be less than or equal to 90 degrees, 0 degrees, 10 degrees, 20 degrees, etc.

In the magnetic circuit assembly 3900, the third magnetic conductive element 316 can seal the magnetic circuit generated by the magnetic circuit assembly 3900, so that more magnetic induction lines are concentrated in the magnetic gap, thereby achieving the effects of inhibiting magnetic leakage, increasing the magnetic induction intensity at the magnetic gap, and improving the sensitivity of the bone conduction speaker. The above description of the structure of magnetic circuit assembly 3900 is merely a specific example and should not be considered the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing magnetic circuit assembly 3900 may be made without departing from this principle, but still remain within the scope of the foregoing description. For example, the second magnetically permeable element 306 may be a ring-shaped structure or a sheet-like structure. For another example, magnetic circuit assembly 3900 may not include second magnetic element 308. For another example, magnetic circuit assembly 3900 may further include at least one electrically conductive element that may connect first magnetic element 302, fifth magnetic element 314, first magnetically permeable element 304, second magnetically permeable element 306, and/or third magnetically permeable element 316. In some embodiments, magnetic circuit assembly 3900 may further add at least one conductive element that may connect at least one of second magnetic element 308, third magnetic element 310, fourth magnetic element 312, sixth magnetic element 324, and seventh magnetic element 326.

Fig. 4A is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 4100 according to some embodiments of the application. As shown in fig. 4A, the magnetic circuit assembly 4100 may include a first magnetic element 402, a first magnetically permeable element 404, a first full field altering element 406, and a second magnetic element 408. In some embodiments, the first magnetic element 402 and/or the second magnetic element 408 may include any one or more of the magnets described herein. The first magnetic element 402 may include a first magnet and the second magnetic element 408 may include a second magnet, which may be the same or different from the first magnet. The first magnetically permeable element 404 may comprise any one or more of the magnetically permeable materials described herein, such as low carbon steel, silicon steel sheet, ferrite, etc. In some embodiments, the first magnetic element 402 and/or the first magnetically permeable element 404 may be disposed in an axisymmetric configuration. The first magnetic element 402 and/or the first magnetically permeable element 404 may be a cylinder. In some embodiments, the first magnetic element 402 and the first magnetically permeable element 404 may be coaxial cylinders, containing the same or different diameters. In some embodiments, the first full magnetic field changing element 406 may be any one of a magnetic element or a magnetically permeable element. The first full magnetic field changing element 406 and/or the second magnetic element 408 may be configured as a ring or a sheet. The description of the first full magnetic field changing element 406 and the second magnetic element 408 may be found elsewhere in the specification (e.g., fig. 5A and 5B and their associated descriptions). In some embodiments, the second magnetic element 408 may be an annular cylinder coaxial with the first magnetic element 402, the first magnetically permeable element 404, and/or the first full field altering element 406, containing inner and/or outer rings of the same or different diameters. The method of machining the first magnetically permeable element 404 and/or the first full field altering element 406 may include any one or more of the methods described herein.

The upper surface of the first magnetic element 402 may be coupled to the lower surface of the first magnetic element 404 and the second magnetic element 408 may be coupled to the first magnetic element 402 and the first full field altering element 406. The connection between the first magnetic element 402, the first magnetically permeable element 404, the first full field altering element 406, and/or the second magnetic element 408 may be based on any one or more of the connection described herein. In some embodiments, the first magnetic element 402, the first magnetically permeable element 404, the first full magnetic field altering element 406, and/or the second magnetic element 408 may form a magnetic loop and a magnetic gap.

In some embodiments, the magnetic circuit assembly 4100 may generate a first full magnetic field and the first magnetic element 402 may generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the second magnetic element 408 may generate a third magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the second magnetic element 408 may be between 0 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the second magnetic element 408 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the second magnetic element 408 may be no greater than 90 degrees.

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the second magnetic element 408 is no more than 90 degrees at the location of the second magnetic element 408. In some embodiments, the angle between the direction of the magnetic field generated by the first magnetic element 402 and the direction of magnetization of the second magnetic element 408 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, etc., at the location of the second magnetic element 408. For another example, the magnetization direction of the first magnetic element 402 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 402, and the magnetization direction of the second magnetic element 408 is directed from the outer ring of the second magnetic element 408 toward the inner ring (as shown in the direction of c, on the right side of the first magnetic element 402, the magnetization direction of the first magnetic element 402 is deflected 270 degrees in the clockwise direction).

The first full magnetic field modifying element 406 in the magnetic circuit assembly 4100 may increase the total magnetic flux in the magnetic gap and thereby increase the magnetic induction in the magnetic gap as compared to a single magnetic element magnetic circuit assembly. Under the action of the first full magnetic field changing element 406, the originally divergent magnetic induction lines converge toward the position of the magnetic gap, and the magnetic induction intensity in the magnetic gap is further increased.

The above description of the structure of the magnetic circuit assembly 4100 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4100 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, magnetic circuit assembly 4100 may further include a magnetically permeable cover that may contain first magnetic element 402, first magnetically permeable element 404, first full field altering element 406, and second magnetic element 408.

Fig. 4B is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 4200, according to some embodiments of the present application. As shown in fig. 4B, unlike the magnetic circuit assembly 4100, the magnetic circuit assembly 4200 may further include a third magnetic element 410.

The lower surface of the third magnetic element 410 may be connected to the first full field altering element 406. The connection between the third magnetic element 410 and the first full field altering element 406 may be based on any one or more of the connections described herein. In some embodiments, a magnetic gap may be formed between the first magnetic element 402, the first magnetically permeable element 404, the first full magnetic field altering element 406, the second magnetic element 408, and/or the third magnetic element 410. In some embodiments, the magnetic circuit assembly 4200 may generate a first full magnetic field and the first magnetic element 402 may generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the third magnetic element 410 may generate a third magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the third magnetic element 410 may be between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the third magnetic element 410 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the third magnetic element 410 may be equal to or greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 402 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 402, and the magnetization direction of the third magnetic element 410 is directed from the inner ring of the third magnetic element 410 to the outer ring (as shown in the direction of b, on the right side of the first magnetic element 402, the magnetization direction of the first magnetic element 402 is deflected 90 degrees in a clockwise direction).

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the second magnetic element 408 is no more than 90 degrees at the location of the third magnetic element 410. In some embodiments, at the location of the third magnetic element 410, the angle between the direction of the magnetic field generated by the first magnetic element 402 and the direction of magnetization of the third magnetic element 410 may be less than or equal to 90 degrees, 0 degrees, 10 degrees, 20 degrees, etc.

The magnetic circuit assembly 4200 further adds the third magnetic element 410 as compared to the magnetic circuit assembly 4100. The third magnetic element 410 may further increase the total magnetic flux within the magnetic gap in the magnetic circuit assembly 4200, thereby increasing the magnetic induction in the magnetic gap. In addition, under the action of the third magnetic element 410, the magnetic induction line further converges toward the position of the magnetic gap, so as to increase the magnetic induction intensity in the magnetic gap.

The above description of the structure of the magnetic circuit assembly 4200 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4200 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the magnetic circuit assembly 4200 may further include a magnetically permeable cover that may contain the first magnetic element 402, the first magnetically permeable element 404, the first full field altering element 406, the second magnetic element 408, and the third magnetic element 410.

Fig. 4C is a schematic structural diagram of a magnetic circuit assembly 4300, according to some embodiments of the present application. As shown in fig. 4C, unlike the magnetic circuit assembly 4200, the magnetic circuit assembly 4300 may further include a fourth magnetic element 412.

The lower surface of the fourth magnetic element 412 may be connected to the upper surface of the first full magnetic field altering element 406 and the upper surface of the fourth magnetic element 412 may be connected to the lower surface of the second magnetic element 408. The manner of connection between the fourth magnetic element 412 and the first full field altering element 406 and the second magnetic element 408 may be based on any one or more of the manners described herein. In some embodiments, a magnetic gap may be formed between the first magnetic element 402, the first magnetically permeable element 404, the first full magnetic field altering element 406, the second magnetic element 408, the third magnetic element 410, and/or the fourth magnetic element 412. The magnetization directions of the second magnetic element 408 and the third magnetic element 410 may be referred to in the detailed description of the present application 4A and/or 4B, respectively.

In some embodiments, magnetic circuit assembly 4300 may generate a first full magnetic field and first magnetic element 402 may generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the fourth magnetic element 412 may generate a third magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the fourth magnetic element 412 may be between 0 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the fourth magnetic element 412 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the fourth magnetic element 412 may be equal to or greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 402 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 402, and the magnetization direction of the fourth magnetic element 412 is directed from the upper surface of the fourth magnetic element 412 to the lower surface (as shown in the direction d, on the right side of the first magnetic element 402, the magnetization direction of the first magnetic element 402 is deflected 180 degrees in a clockwise direction).

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the fourth magnetic element 412 is no more than 90 degrees at the location of the fourth magnetic element 412. In some embodiments, at the location of the fourth magnetic element 412, the angle between the direction of the magnetic field generated by the first magnetic element 402 and the direction of magnetization of the fourth magnetic element 412 may be less than or equal to 90 degrees, 0 degrees, 10 degrees, 20 degrees, etc.

The magnetic circuit assembly 4300 further adds a fourth magnetic element 412 as compared to the magnetic circuit assembly 4200. Fourth magnetic element 412 may further increase the total magnetic flux within the magnetic gap in magnetic circuit assembly 4300, thereby increasing the magnetic induction in the magnetic gap. In addition, under the action of the fourth magnetic element 412, the magnetic induction line further converges toward the position of the magnetic gap, so as to increase the magnetic induction intensity in the magnetic gap.

The above description of the structure of the magnetic circuit assembly 4300 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4300 may be made without departing from such principles, but remain within the scope of the description above. For example, the magnetic circuit assembly 4200 may further include one or more electrically conductive elements that may connect at least one of the first magnetic element 402, the first magnetically permeable element 404, the second magnetic element 408, the third magnetic element 410, and the fourth magnetic element 412.

Fig. 4D is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 4400, according to some embodiments of the present application. As shown in fig. 4D, unlike the magnetic circuit assembly 4300, the magnetic circuit assembly 4400 may further include a magnetically permeable cover 414.

The magnetic shield 414 may comprise any one or more of the magnetic conductive materials described herein, such as mild steel, silicon steel sheet, ferrite, etc. The magnetically permeable cover 414 may connect the first full magnetic field altering element 406, the second magnetic element 408, the third magnetic element 410, and the fourth magnetic element 412 by any one or more of the connections described herein. The processing method of the magnetic permeable cover 414 may include any of the processing methods described herein, such as one or more combinations of casting, plastic processing, cutting, powder metallurgy, and the like. In some embodiments, the magnetically permeable cover 414 may include a bottom plate and side walls that are annular in configuration. In some embodiments, the floor and side walls may be integrally formed. In some embodiments, the bottom panel may be connected to the side walls by any one or more of the connections described herein.

The magnetic circuit assembly 4400 further adds a magnetically permeable cover 414 as compared to the magnetic circuit assembly 4300. The magnetic shield 414 can inhibit magnetic leakage of the magnetic circuit assembly 4300, and effectively reduce the magnetic circuit length and magnetic resistance, so that more magnetic induction lines can pass through the magnetic gap, and the magnetic induction intensity in the magnetic gap is improved.

The above description of the structure of the magnetic circuit assembly 4400 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4400 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the magnetic circuit assembly 4400 may further include one or more electrically conductive elements that may connect at least one of the first magnetic element 402, the first magnetically permeable element 404, the second magnetic element 408, the third magnetic element 410, and the fourth magnetic element 412. For another example, the magnetic circuit assembly 4200 may further include a fifth magnetic element having a lower surface coupled to the upper surface of the first magnetically permeable element 404, the fifth magnetic element having a magnetization direction opposite to the magnetization direction of the first magnetic element 402.

Fig. 4E is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 4500, according to some embodiments of the present application. As shown in fig. 4E, unlike the magnetic circuit assembly 4200, the connection surface of the first full field varying element 406 and the second magnetic element 408 of the magnetic circuit assembly 4500 may be wedge-shaped in cross-section.

In comparison with the magnetic circuit assembly 4100, the connection surface of the first full magnetic field changing element 406 and the second magnetic element 408 of the magnetic circuit assembly 4500 is configured to have a wedge-shaped cross section, so that the magnetic induction line can be smoothly turned. At the same time, the wedge-shaped cross-section may facilitate assembly of the first full magnetic field changing element 406 and the second magnetic element 408 and may reduce the number of assembly components and reduce the weight of the bone conduction speaker.

The above description of the structure of the magnetic circuit assembly 4500 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4500 may be made without departing from such principles, but remain within the scope of the foregoing description. For example, magnetic circuit assembly 4500 may further include one or more conductive elements that may connect at least one of first magnetic element 402, first magnetically permeable element 404, second magnetic element 408, and third magnetic element 410. For another example, the magnetic circuit assembly 4500 may further include a fifth magnetic element, a lower surface of which is connected to an upper surface of the first magnetic conductive element 404, and a magnetization direction of which is opposite to a magnetization direction of the first magnetic element 402. In some embodiments, the magnetic circuit assembly 4500 may further comprise a magnetically permeable cover that may contain the first magnetic element 402, the first magnetically permeable element 404, the first full field altering element 406, the second magnetic element 408, and the third magnetic element 410.

Fig. 4F is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 4600, shown in accordance with some embodiments of the present application. As shown in fig. 4F, unlike the magnetic circuit assembly 4100, the magnetic circuit assembly 4600 may further include a fifth magnetic element 416. In some embodiments, the fifth magnetic element 416 may include one or more magnets. The magnets may comprise any one or more of the magnet materials described herein. In some embodiments, the fifth magnetic element 416 may include a first magnet and the first magnetic element 402 may include a second magnet, which may be the same or different magnet materials than the second magnet. In some embodiments, fifth magnetic element 416, first magnetic element 402, and first magnetically permeable element 404 may be disposed in an axisymmetric configuration, e.g., fifth magnetic element 416, first magnetic element 402, and first magnetically permeable element 404 may be cylindrical. In some embodiments, fifth magnetic element 416, first magnetic element 402, and first magnetically permeable element 404 may be coaxial cylinders, containing the same or different diameters, in some embodiments. For example, the first magnetically permeable element 404 may have a larger diameter than the first magnetic element 402 and/or the fifth magnetic element 416, and the sidewalls of the first magnetic element 402 and/or the fifth magnetic element 416 may form first and/or second recesses. In some embodiments, the ratio of the thickness of the second magnetic element 416 to the sum of the thicknesses of the first magnetic element 402, the second magnetic element 416, and the first magnetically permeable element 404 is in the range of 0.4-0.6. The ratio of the first magnetically permeable element 404 to the sum of the thicknesses of the first magnetic element 402, the second magnetic element 416, and the first magnetically permeable element 404 is in the range of 0.5-1.5.

In some embodiments, the included angle between the magnetization direction of the fifth magnetic element 416 and the magnetization direction of the first magnetic element 402 is between 150 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the fifth magnetic element 416 and the magnetization direction of the first magnetic element 402 is between 90 degrees and 180 degrees. For example, the magnetization direction of the fifth magnetic element 416 is opposite to the magnetization direction of the first magnetic element 402 (as shown, the a-direction and the e-direction).

The magnetic circuit assembly 4600 further adds a fifth magnetic element 416 as compared to the magnetic circuit assembly 4100. The fifth magnetic element 426 can inhibit the magnetic leakage of the first magnetic element 402 in the magnetic circuit assembly 4600 in the magnetization direction, so that the magnetic field generated by the first magnetic element 402 can be more compressed into the magnetic gap, thereby improving the magnetic induction intensity in the magnetic gap.

The above description of the structure of the magnetic circuit assembly 4600 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4600 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. In some embodiments, magnetic circuit assembly 4600 may further include one or more electrically conductive elements, which may connect at least one of first magnetic element 402, first magnetically permeable element 404, second magnetic element 408, and fifth magnetic element 416, e.g., the one or more electrically conductive elements may be disposed in the first recess and/or the second recess. In some embodiments, the magnetic circuit assembly 4600 may further add at least one magnetic element, which may be coupled to the first full field altering element 406. In some embodiments, magnetic circuit assembly 4600 may further include a magnetically permeable cover comprising first magnetic element 402, first magnetically permeable element 404, first full field altering element 406, second magnetic element 408, and fifth magnetic element 416.

Fig. 4G is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 4900 according to some embodiments of the present application. The magnetic circuit assembly 4900 may include a first magnetic element 402, a first magnetically permeable element 404, a first full magnetic field altering element 406, a second magnetic element 408, a third magnetic element 410, a fourth magnetic element 412, a fifth magnetic element 416, a sixth magnetic element 418, a seventh magnetic element 420, and a second annular element 422. The first magnetic element 402, the first magnetically permeable element 404, the first full magnetic field altering element 406, the second magnetic element 408, the third magnetic element 410, the fourth magnetic element 412, and the fifth magnetic element 416 may be referred to herein in the detailed description of fig. 4A, 4B, 4C, 4D, 4E, and/or 4F. In some embodiments, the first full magnetic field altering element 406 and/or the second annular element 422 may comprise an annular magnetic element or an annular magnetically permeable element. The annular magnetic element may comprise any one or more of the magnet materials described herein, and the annular magnetically permeable element may comprise any one or more of the magnetically permeable materials described herein.

In some embodiments, the sixth magnetic element 418 may connect the fifth magnetic element 416 and the second annular element 422, and the seventh magnetic element 420 may connect the third magnetic element 410 and the second annular element 422. In some embodiments, the first magnetic element 402, the fifth magnetic element 416, the second magnetic element 408, the third magnetic element 410, the fourth magnetic element 412, the sixth magnetic element 418, and/or the seventh magnetic element 420 may form a magnetic loop with the first magnetic permeable element 404, the first full magnetic field altering element 406, and the second annular element 422.

The magnetization direction of the second magnetic element 408 can be described in detail with reference to fig. 4A of the present application, and the magnetization directions of the third magnetic element 410, the fourth magnetic element 412, and the fifth magnetic element 416 can be described in detail with reference to fig. 4B, 4C, and 4F of the present application, respectively.

In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the sixth magnetic element 418 may be between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the sixth magnetic element 418 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the sixth magnetic element 418 is no greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 402 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 402, and the magnetization direction of the sixth magnetic element 418 is directed from the outer ring of the sixth magnetic element 418 toward the inner ring (as shown in the direction f, on the right side of the first magnetic element 402, the magnetization direction of the first magnetic element 402 is deflected 270 degrees in the clockwise direction). In some embodiments, the magnetization direction of the sixth magnetic element 418 may be the same as the magnetization direction of the second magnetic element 408 in the same vertical direction. In some embodiments, the magnetization direction of the first magnetic element 402 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 402, and the magnetization direction of the seventh magnetic element 420 is directed from the lower surface of the seventh magnetic element 420 to the upper surface (as shown in the direction of e, on the right side of the first magnetic element 402, the magnetization direction of the first magnetic element 402 is deflected 360 degrees in a clockwise direction). In some embodiments, the magnetization direction of the seventh magnetic element 420 may be the same as the magnetization direction of the third magnetic element 412.

In some embodiments, at the location of the sixth magnetic element 418, the angle between the direction of the magnetic field generated by the magnetic circuit assembly 4900 and the magnetization direction of the sixth magnetic element 418 is no more than 90 degrees. In some embodiments, the angle between the direction of the magnetic field generated by the first magnetic element 402 and the magnetization direction of the sixth magnetic element 418 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, etc., at the location of the sixth magnetic element 418.

In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the seventh magnetic element 420 may be between 0 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the seventh magnetic element 420 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 402 and the magnetization direction of the seventh magnetic element 420 is no more than 90 degrees.

In some embodiments, at the location of the seventh magnetic element 420, the angle between the direction of the magnetic field generated by the magnetic circuit assembly 4900 and the magnetization direction of the seventh magnetic element 420 is no more than 90 degrees. In some embodiments, at the location of the seventh magnetic element 420, the angle between the direction of the magnetic field generated by the first magnetic element 402 and the direction of magnetization of the seventh magnetic element 420 may be less than or equal to 90 degrees, 0 degrees, 10 degrees, 20 degrees, etc.

In some embodiments, the first full magnetic field changing element 406 may be a toroidal magnetic element. In this case, the magnetization direction of the first full magnetic field changing element 406 may be the same as the magnetization direction of the second magnetic element 408 or the fourth magnetic element 412. For example, on the right side of the first magnetic element 402, the magnetization direction of the first full field changing element 406 may be directed from the outer ring of the first full field changing element 406 to the inner ring. In some embodiments, the second annular element 422 may be an annular magnetic element. In this case, the magnetization direction of the second annular element 422 may be the same as the magnetization direction of the sixth magnetic element 418 or the seventh magnetic element 420. For example, on the right side of the first magnetic element 402, the magnetization direction of the second annular element 422 may be directed from the outer ring of the second annular element 422 to the inner ring.

In the magnetic circuit assembly 4900, the plurality of magnetic elements can improve the total magnetic flux, and different magnetic elements interact, so that leakage of magnetic induction lines can be restrained, the magnetic induction intensity at the magnetic gap is improved, and the sensitivity of the bone conduction speaker is improved.

The above description of the structure of the magnetic circuit assembly 4900 is merely a specific example and should not be construed as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 4900 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. In some embodiments, the magnetic circuit assembly 4900 may further include one or more electrically conductive elements that may connect at least one of the first magnetic element 402, the first magnetically permeable element 404, the second magnetic element 408, the third magnetic element 410, the fourth magnetic element 412, the fifth magnetic element 416, the sixth magnetic element 418, and the seventh magnetic element 420.

Fig. 4H is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 41000 according to some embodiments of the application. As shown in fig. 4H, unlike the magnetic circuit assembly 4900, the magnetic circuit assembly 41000 may further include a magnetically permeable cover 414.

The magnetic shield 414 may comprise any one or more of the magnetic conductive materials described herein, such as mild steel, silicon steel sheet, ferrite, etc. The magnetically permeable cover 414 may connect the first magnetic element 402, the first full field altering element 406, the second magnetic element 408, the third magnetic element 410, the fourth magnetic element 412, the fifth magnetic element 416, the sixth magnetic element 418, the seventh magnetic element 420, and the second annular element 422 by any one or more of the connections described herein. The processing method of the magnetic permeable cover 414 may include any of the processing methods described herein, such as one or more combinations of casting, plastic processing, cutting, powder metallurgy, and the like. In some embodiments, the magnetically permeable cover may include at least one bottom plate and a sidewall, the sidewall being of annular configuration. In some embodiments, the floor and side walls may be integrally formed. In some embodiments, the bottom panel may be connected to the side walls by any one or more of the connections described herein. For example, the magnetically permeable cover 414 may include a first bottom plate, a second bottom plate, and a side wall, where the first bottom plate and the side wall may be integrally formed, and the second bottom plate may be connected to the side wall by any one or more of the connection methods described herein.

In the magnetic circuit assembly 41000, the magnetic circuit generated by the magnetic circuit assembly 41000 can be closed by the magnetic conductive cover 414, so that more magnetic induction lines are concentrated in the magnetic gap in the magnetic circuit assembly 41000, and the effects of inhibiting magnetic leakage, increasing the magnetic induction intensity at the magnetic gap and improving the sensitivity of the bone conduction speaker are achieved.

The above description of the structure of the magnetic circuit assembly 41000 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 41000 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the magnetic circuit assembly 41000 may further include one or more electrically conductive elements that may connect at least one of the first magnetic element 402, the first magnetically permeable element 404, the second magnetic element 408, the third magnetic element 410, the fourth magnetic element 412, the fifth magnetic element 416, the sixth magnetic element 418, and the seventh magnetic element 420.

Fig. 4I is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 41100 according to some embodiments of the present application. As shown in fig. 4I, unlike the magnetic circuit assembly 4100, the magnetic circuit assembly 41100 can further include one or more conductive elements (e.g., a first conductive element 424, a second conductive element 426, and a third conductive element 428).

The description of the conductive elements is similar to conductive element 318, conductive element 320, and conductive element 322, and the relevant description thereof is not repeated here.

The above description of the structure of the magnetic circuit assembly 41100 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 41100 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the magnetic circuit assembly 41100 may further include at least one magnetic and/or magnetically permeable element.

Fig. 5A is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 5100 according to some embodiments of the present application. As shown in fig. 5A, the magnetic circuit assembly 5100 may include a first magnetic element 502, a first magnetically permeable element 504, a second magnetically permeable element 506, and a second magnetic element 508.

In some embodiments, the first magnetic element 502 and/or the second magnetic element 508 may include any one or more of the magnets described herein. In some embodiments, the first magnetic element 502 may include a first magnet and the second magnetic element 508 may include a second magnet, which may be the same or different from the first magnet. The first magnetically permeable element 504 and/or the second magnetically permeable element 506 may comprise any one or more of the magnetically permeable materials described herein. The method of machining the first magnetically permeable element 504 and/or the second magnetically permeable element 506 may include any one or more of the methods described herein. In some embodiments, the first magnetic element 502, the first magnetically permeable element 504, and/or the second magnetic element 508 may be disposed in an axisymmetric configuration. For example, first magnetic element 502, first magnetic element 504, and/or second magnetic element 508 may be cylindrical. In some embodiments, the first magnetic element 502, the first magnetically permeable element 504, and/or the second magnetic element 508 may be coaxial cylinders containing the same or different diameters. The thickness of the first magnetic element 502 may be greater than or equal to the thickness of the second magnetic element 508. In some embodiments, the second magnetically permeable element 506 may be a groove-type structure. The groove-type structure may comprise a U-shaped cross section (as shown in fig. 5A). The second magnetically permeable element 506 of the recess may include a bottom plate and a side wall. In some embodiments, the base plate and the side walls may be integrally formed, for example, the side walls may be formed from the base plate extending in a direction perpendicular to the base plate. In some embodiments, the bottom panel may be connected to the side walls by any one or more of the connections described herein. The second magnetic element 508 may be configured in a ring or a sheet. Reference may be made to the descriptions elsewhere in the specification regarding the shape of the second magnetic element 508 (e.g., fig. 6A and 6B and their associated descriptions). In some embodiments, the second magnetic element 508 may be coaxial with the first magnetic element 502 and/or the first magnetically permeable element 504.

The upper surface of the first magnetic element 502 may be connected to the lower surface of the first magnetic element 504. The lower surface of the first magnetic element 502 may be connected to the bottom plate of the second magnetic element 506. The lower surface of the second magnetic element 508 is connected to the upper surface of the first magnetic element 504. The connection between the first magnetic element 502, the first magnetic element 504, the second magnetic element 506, and/or the second magnetic element 508 may include one or more combinations of bonding, clamping, welding, riveting, bolting, and the like.

A magnetic gap is formed between the sidewalls of the first magnetic element 502, the first magnetic conductive element 504, and/or the second magnetic element 508, and the second magnetic conductive element 506. Voice coil 520 may be disposed in the magnetic gap. In some embodiments, first magnetic element 502, first magnetic element 504, second magnetic element 506, and second magnetic element 508 may form a magnetic circuit. In some embodiments, the magnetic circuit assembly 5100 may generate a first full magnetic field and the first magnetic element 502 may generate a second magnetic field. The first full magnetic field is formed by the magnetic fields generated by all components (e.g., first magnetic element 502, first magnetic element 504, second magnetic element 506, and second magnetic element 508) in the magnetic circuit assembly 5100. The magnetic field strength (which may also be referred to as magnetic induction or magnetic flux density) of the first full magnetic field within the magnetic gap is greater than the magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the second magnetic element 508 may generate a third magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the second magnetic element 508 and the magnetization direction of the first magnetic element 502 is between 90 degrees and 180 degrees. In some embodiments, the angle between the magnetization direction of the second magnetic element 508 and the magnetization direction of the first magnetic element 502 is between 150 degrees and 180 degrees. In some embodiments, the magnetization direction of the second magnetic element 508 is opposite to the magnetization direction of the first magnetic element 502 (as shown, the a-direction and the b-direction).

The magnetic circuit assembly 5100 adds a second magnetic element 508 as compared to a single magnetic element magnetic circuit assembly. The magnetization direction of the second magnetic element 508 is opposite to that of the first magnetic element 502, so that magnetic leakage of the first magnetic element 502 in the magnetization direction can be suppressed, and the magnetic field generated by the first magnetic element 502 can be more compressed into the magnetic gap, so that the magnetic induction intensity in the magnetic gap is improved.

The above description of the structure of the magnetic circuit assembly 5100 is only a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, after having appreciated the basic principles of the bone magnetic circuit assembly, that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 5100 may be made without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the second magnetically permeable element 506 may be a ring-shaped structure or a sheet-like structure. For another example, the magnetic circuit assembly 5100 may further include an electrically conductive element that may connect the first magnetic element 502, the first magnetically permeable element 504, the second magnetically permeable element 506, and the second magnetic element 508.

Fig. 5B is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 5200, according to some embodiments of the present application. As shown in fig. 5B, unlike the magnetic circuit assembly 5100, the magnetic circuit assembly 5200 may further include a third magnetic element 510.

The lower surface of the third magnetic element 510 is connected to the sidewall of the second magnetic element 506. A magnetic gap may be formed between the first magnetic element 502, the first magnetically permeable element 504, the second magnetic element 508, and/or the third magnetic element 510. Voice coil 520 may be disposed in the magnetic gap. In some embodiments, first magnetic element 502, first magnetic element 504, second magnetic element 506, second magnetic element 508, and third magnetic element 510 may form a magnetic circuit. In some embodiments, the magnetization direction of the second magnetic element 508 may be as described in detail with reference to fig. 3A of the present application.

In some embodiments, magnetic circuit assembly 5200 can generate a first full magnetic field and first magnetic element 502 can generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the third magnetic element 510 may generate a third magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the third magnetic element 510 is between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the third magnetic element 510 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the third magnetic element 510 is equal to or greater than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 502 is vertically upward (direction shown as a) perpendicular to the lower or upper surface of the first magnetic element 502, and the magnetization direction of the third magnetic element 510 is directed from the inner ring to the outer ring of the third magnetic element 510 (direction shown as c on the right side of the first magnetic element 502, the magnetization direction of the first magnetic element 502 is deflected 90 degrees in a clockwise direction).

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the third magnetic element 510 is no more than 90 degrees at the location of the third magnetic element 510. In some embodiments, at the location of the third magnetic element 510, the angle between the direction of the magnetic field generated by the first magnetic element 502 and the direction of magnetization of the third magnetic element 510 may be less than or equal to 90 degrees, 0 degrees, 10 degrees, 20 degrees, etc.

The magnetic circuit assembly 5200 further adds a third magnetic element 510 as compared to the magnetic circuit assembly 5100. Third magnetic element 510 may further increase the total magnetic flux within the magnetic gap in magnetic circuit assembly 5200, thereby increasing the magnetic induction in the magnetic gap. Under the action of the third magnetic element 510, the magnetic induction line further converges toward the position of the magnetic gap, and the magnetic induction intensity in the magnetic gap is further increased.

Fig. 5C is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 5300, according to some embodiments of the present application. As shown in fig. 5C, unlike the magnetic circuit assembly 5100, the magnetic circuit assembly 5300 may further include a fourth magnetic element 512.

The fourth magnetic element 512 may be attached to the sidewalls of the first magnetic element 502 and the second magnetic element 506 by one or more of bonding, clamping, welding, riveting, bolting, etc. In some embodiments, first magnetic element 502, first magnetic element 504, second magnetic element 506, second magnetic element 508, and fourth magnetic element 512 may form a magnetic gap. In some embodiments, the magnetization direction of the second magnetic element 508 may be as described in detail with reference to fig. 5A of the present application.

In some embodiments, magnetic circuit assembly 5200 can generate a first full magnetic field and first magnetic element 502 can generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, fourth magnetic element 512 may generate a fourth magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the fourth magnetic element 512 is between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the fourth magnetic element 512 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the fourth magnetic element 512 is no more than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 502 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 502, and the magnetization direction of the fourth magnetic element 512 is directed from the outer ring of the fourth magnetic element 512 to the inner ring (as shown in the direction of e, on the right side of the first magnetic element 502, the magnetization direction of the first magnetic element 502 is deflected 270 degrees in the clockwise direction).

In some embodiments, at the location of the fourth magnetic element 512, the angle between the direction of the first full magnetic field and the magnetization direction of the fourth magnetic element 512 is no more than 90 degrees. In some embodiments, at the location of the fourth magnetic element 512, the angle between the direction of the magnetic field generated by the first magnetic element 502 and the magnetization direction of the fourth magnetic element 512 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, etc.

The magnetic circuit assembly 5300 further adds a fourth magnetic element 512 as compared to the magnetic circuit assembly 5200. Fourth magnetic element 512 may further increase the total magnetic flux in the magnetic gap in magnetic circuit assembly 5300, thereby increasing the magnetic induction in the magnetic gap. Under the action of the fourth magnetic element 512, the magnetic induction line further converges toward the position of the magnetic gap, and the magnetic induction intensity in the magnetic gap is further increased.

Fig. 5D is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 5400, according to some embodiments of the present application. As shown in fig. 5D, unlike the magnetic circuit assembly 5200, the magnetic circuit assembly 5400 can further include a fifth magnetic element 514.

The lower surface of the third magnetic element 510 is connected to the fifth magnetic element 514, and the lower surface of the fifth magnetic element 514 is connected to the sidewall of the second magnetic conductive element 506. A magnetic gap may be formed between the first magnetic element 502, the first magnetically permeable element 504, the second magnetic element 508, and/or the third magnetic element 510. Voice coil 520 may be disposed in the magnetic gap. In some embodiments, the first magnetic element 502, the first magnetic conductive element 504, the second magnetic conductive element 506, the second magnetic element 508, the third magnetic element 510, and the fifth magnetic element 514 may form a magnetic circuit. In some embodiments, the magnetization direction of the second magnetic element 508 and the third magnetic element 510 may be described in detail with reference to fig. 5A and 5B of the present application.

In some embodiments, magnetic circuit assembly 5400 may generate a first full magnetic field and first magnetic element 502 may generate a second magnetic field, the magnetic field strength of the first full magnetic field within the magnetic gap being greater than the magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, the fifth magnetic element 514 may generate a fifth magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the fifth magnetic element 514 is between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the fifth magnetic element 514 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the fifth magnetic element 514 is equal to or greater than 90 degrees.

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the fifth magnetic element 514 is no more than 90 degrees at the location of the fifth magnetic element 514. In some embodiments, at the location of the fifth magnetic element 514, the angle between the direction of the magnetic field generated by the first magnetic element 502 and the magnetization direction of the fifth magnetic element 514 may be less than or equal to 90 degrees, such as 0 degrees, 10 degrees, 20 degrees, and so on. In some embodiments, the magnetization direction of the first magnetic element 502 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 502, and the magnetization direction of the fifth magnetic element 514 is directed from the upper surface of the fifth magnetic element 514 toward the lower surface (as shown in the direction d, on the right side of the first magnetic element 502, the magnetization direction of the first magnetic element 502 is deflected 180 degrees in a clockwise direction).

The magnetic circuit assembly 5400 further adds the fifth magnetic element 514 as compared to the magnetic circuit assembly 5200. Fifth magnetic element 514 may further increase the total magnetic flux within the magnetic gap in magnetic circuit assembly 5400, thereby increasing the magnetic induction in the magnetic gap. Under the action of the fourth magnetic element 514, the magnetic induction line further converges toward the position of the magnetic gap, and the magnetic induction intensity in the magnetic gap is further increased.

Fig. 5E is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 5500, according to some embodiments of the present application. As shown in fig. 5E, unlike magnetic circuit assembly 5300, magnetic circuit assembly 5500 may further include a sixth magnetic element 516.

The sixth magnetic element 516 may be coupled to the second magnetic element 508 and the sidewall of the second magnetic element 506 by one or more combinations of bonding, clamping, welding, riveting, bolting, etc. In some embodiments, first magnetic element 502, first magnetic element 504, second magnetic element 506, second magnetic element 508, fourth magnetic element 512, and sixth magnetic element 516 may form a magnetic gap. In some embodiments, the magnetization directions of the second magnetic element 508 and the fourth magnetic element 512 may be described in detail with reference to fig. 5A and 5C of the present application.

In some embodiments, magnetic circuit assembly 5500 may generate a first full magnetic field and first magnetic element 502 may generate a second magnetic field, the first full magnetic field having a magnetic field strength within the magnetic gap that is greater than a magnetic field strength of the second magnetic field within the magnetic gap. In some embodiments, sixth magnetic element 516 may generate a sixth magnetic field that may increase the magnetic field strength of the second magnetic field at the magnetic gap.

In some embodiments, the included angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the sixth magnetic element 516 is between 0 degrees and 180 degrees. In some embodiments, the included angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the sixth magnetic element 516 is between 45 degrees and 135 degrees. In some embodiments, the angle between the magnetization direction of the first magnetic element 502 and the magnetization direction of the sixth magnetic element 516 is no more than 90 degrees. In some embodiments, the magnetization direction of the first magnetic element 502 is vertically upward (as shown in the direction of fig. a) perpendicular to the lower or upper surface of the first magnetic element 502, and the magnetization direction of the sixth magnetic element 516 is directed from the outer ring of the sixth magnetic element 516 toward the inner ring (as shown in the direction f, on the right side of the first magnetic element 502, the magnetization direction of the first magnetic element 502 is deflected 270 degrees in the clockwise direction).

In some embodiments, the angle between the direction of the first full magnetic field and the magnetization direction of the sixth magnetic element 516 is no more than 90 degrees at the location of the sixth magnetic element 516. In some embodiments, at the location of the sixth magnetic element 516, the angle between the direction of the magnetic field generated by the first magnetic element 502 and the direction of magnetization of the sixth magnetic element 516 may be greater than 90 degrees, 110 degrees, 120 degrees, etc.

The magnetic circuit assembly 5500 further adds a fourth magnetic element 512 and a sixth magnetic element 516 as compared to the magnetic circuit assembly 5100. Fourth magnetic element 512 and sixth magnetic element 516 may increase the total magnetic flux in the magnetic gap of magnetic circuit assembly 5500, increasing the magnetic induction at the magnetic gap, and thus increasing the sensitivity of the bone conduction speaker.

Fig. 5F is a schematic longitudinal cross-sectional view of a magnetic circuit assembly 5600, according to some embodiments of the present application. As shown in fig. 5F, unlike the magnetic circuit assembly 5100, the magnetic circuit assembly 5600 may further include a third magnetically permeable element 518.

In some embodiments, third magnetically permeable element 518 may comprise any one or more of the magnetically permeable materials described herein. The magnetically permeable materials included in the first magnetically permeable element 504, the second magnetically permeable element 506, and/or the third magnetically permeable element 518 may be the same or different. In some embodiments, the third magnetically permeable element 5186 can be provided in a symmetrical configuration. For example, the third magnetically permeable element 518 may be a cylinder. In some embodiments, the first magnetic element 502, the first magnetic element 504, the second magnetic element 508, and/or the third magnetic element 518 may be coaxial cylinders containing the same or different diameters. A third magnetically permeable element 518 may be coupled to the second magnetic element 508. In some embodiments, third magnetically permeable element 518 may connect second magnetic element 5084 and second magnetically permeable element 506 such that third magnetically permeable element 518 and second magnetically permeable element 506 form a cavity that may contain first magnetic element 502, second magnetic element 508, and first magnetically permeable element 504.

The magnetic circuit assembly 5600 further adds a third magnetically permeable element 518 as compared to the magnetic circuit assembly 5100. The third magnetic conductive element 518 can inhibit magnetic leakage of the second magnetic element 508 in the magnetic circuit assembly 5600 in the magnetization direction, so that the magnetic field generated by the second magnetic element 508 can be more compressed into the magnetic gap, thereby improving the magnetic induction intensity in the magnetic gap.

Fig. 6A is a schematic cross-sectional view of a magnetic element structure, according to some embodiments of the present application. The magnetic element 600 may be adapted for use in any of the magnetic circuit assemblies of the present application (e.g., the magnetic circuit assemblies shown in fig. 3A-3G, fig. 4A-4I, or fig. 5A-5F). As shown, the magnetic element 600 may be annular. The magnetic element 600 may include an inner ring 602 and an outer ring 604. In some embodiments, the shape of the inner ring 602 and/or the outer ring 604 may be circular, elliptical, triangular, quadrilateral, or any other polygon.

Fig. 6B is a schematic diagram of a magnetic element structure, according to some embodiments of the present application. The magnetic element may be adapted for use in any of the magnetic circuit assemblies of the present application (e.g., the magnetic circuit assemblies shown in fig. 3A-3G, fig. 4A-4I, or fig. 5A-5F). As shown, the magnetic element may be comprised of a plurality of magnet arrangements. The two ends of any one of the magnets may be connected to the two ends of the adjacent magnets or may have a certain distance. The spacing between the plurality of magnets may be the same or different. In some embodiments, the magnetic element may be comprised of 2 or 3 plate-like magnets (e.g., magnets 608-2, 608-4, and 608-6) arranged equidistantly. The shape of the sheet-like magnet may be a sector, a quadrangle, or the like.

Fig. 6C is a schematic diagram illustrating the magnetization direction of a magnetic element in a magnetic circuit assembly according to some embodiments of the present application. As illustrated, the magnetic circuit assembly may include a first magnetic element 601, a second magnetic element 603, and a third magnetic element 605. The magnetization direction of the first magnetic element 601 may be directed from the lower surface of the first magnetic element 601 to the upper surface (i.e., in a direction out of the page perpendicular to the page). The second magnetic element 603 may be disposed around the first magnetic element 601. A magnetic gap may be formed between the inner ring of the second magnetic element 503 and the inner ring of the first magnetic element 601. The magnetization direction of the second magnetic element 603 may be directed from the inner ring to the outer ring of the second magnetic element 603. The inner ring of the third magnetic element 605 may be coupled to the outer ring of the first magnetic element 601 and the outer ring of the third magnetic element 605 may be coupled to the inner ring of the second magnetic element 603. The magnetization direction of the third magnetic element 605 may be directed from the outer ring of the third magnetic element 603 to the inner ring.

Fig. 6D is a schematic diagram of magnetic induction lines of a magnetic element in a magnetic circuit assembly according to some embodiments of the present application. As shown, a magnetic circuit assembly 600 (e.g., as shown in fig. 3A-3G, 4A-4I, or 5A-5F) may include a first magnetic element 602 and a second magnetic element 604. The magnetization direction of the first magnetic element 602 may be such that the lower surface of the first magnetic element 602 points toward the upper surface (as indicated by arrow a). The first magnetic element 602 may generate a second magnetic field, which may be represented by lines of magnetic induction (solid lines in the figure represent the distribution of the second magnetic field without the presence of the second magnetic element 604), the magnetic field direction of the second magnetic field at a point being tangential to the lines of magnetic induction at that point. The magnetization direction of the second magnetic element 604 may be such that the inner ring of the second magnetic element 604 points toward the outer ring (as indicated by arrow b). The second magnetic element 604 may generate a third magnetic field. The third magnetic field may also be represented by lines of magnetic induction (the dashed lines in the figure represent the distribution of the third magnetic field in the absence of the first magnetic element 602), the magnetic field direction of the third magnetic field at a point being the tangential direction of the point on the third lines of magnetic induction. The magnetic circuit assembly 600 may generate a first full magnetic field under the interaction of the second magnetic field and the third magnetic field. The magnetic field strength of the first full magnetic field at the voice coil 606 is greater than the magnetic field strength of the second magnetic field or the third magnetic field at the voice coil 606. As shown, the angle between the magnetic field direction of the second magnetic field at the voice coil 606 and the magnetization direction of the second magnetic element 604 is less than or equal to 90 degrees.

Fig. 7A is a schematic structural diagram of a magnetic circuit assembly 7000 according to some embodiments of the present application. As shown, magnetic circuit assembly 7000 may include first magnetic element 702, first magnetically permeable element 704, first annular magnetic element 706, and second annular magnetic element 708. The first toroidal magnetic element 706 may also be referred to as a first full magnetic field altering element (e.g., the first full magnetic field altering element 406 described in fig. 4A). The first magnetic element 702, the first magnetically permeable element 704, the first annular magnetic element 706, and the second annular magnetic element 708 may be described in detail with reference to fig. 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, and/or 4I of the present application. For example, the first annular magnetic element 706 may be integrally formed of magnetic material, or may be formed by splicing and combining a plurality of magnetic elements. The second annular magnetic element 708 may be formed by integrally molding a magnetic material, or may be formed by splicing and combining a plurality of magnetic elements. As another example, the second ring magnetic element 708 may connect the first magnetic element 702 and the first ring magnetic element 706. Further, the first ring magnetic element 706 is coupled to an upper surface of the second ring magnetic element 708, and an inner wall of the second ring magnetic element 708 is coupled to an outer wall of the first magnetic element 702.

The first magnetic element 702, the first magnetic conductive element 704, the first annular magnetic element 706, and the second annular magnetic element 708 may form a magnetic circuit and a magnetic gap. Voice coil 720 may be placed in the magnetic gap. Voice coil 720 may be circular or non-circular. The non-circular shape may include an oval, triangle, quadrilateral, pentagon, other polygon, or other irregular shape. When an alternating current is passed through the voice coil 720, the voice coil 720 in the magnetic gap vibrates under the action of the magnetic field in the magnetic circuit due to the ampere force, thereby converting the sound signal into a vibration signal, which is transmitted to the auditory nerve through the human tissue and bone by other components in the bone conduction headset (e.g., the vibration component 104 shown in fig. 1), thereby making the human hear the sound. The magnitude of the ampere force experienced by the voice coil can affect the vibration of the voice coil, thereby further affecting the sensitivity of the bone conduction headset. The magnitude of the ampere force applied to the voice coil is related to the magnetic induction intensity in the magnetic gap, and further, the magnetic induction intensity in the magnetic gap can be changed by adjusting the parameters of the magnetic circuit assembly.

Parameters of magnetic circuit assembly 7000 may include a thickness H of first magnetic element 702 (as shown in fig. 7A, i.e., a height H of first magnetic element 702), a thickness w of first annular magnetic element 706, a height H of second annular magnetic element 708, a magnetic circuit radius R, and so forth. In some embodiments, the magnetic circuit (i.e., magnetic circuit) radius R may refer to an average half-width of the magnetic circuit, i.e., equal to a distance between a central axis of the magnetic circuit assembly (shown in phantom in fig. 7A) and an outer wall of the first annular magnetic element 706. In some embodiments, the parameters of the magnetic circuit assembly 7000 may further include a ratio of the magnetic circuit radius R to the thickness H of the first magnetic element 702 (which may be expressed as R/H), a ratio of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R (which may be expressed as w/R), a ratio of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 (which may be expressed as H/H), and so forth. In some embodiments, the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 702 ranges from 2.0 to 4.0. For example, the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 702 may be 2.0, 2.4, 2.8, 3.2, 3.6, 4.0. The ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 may be no greater than 0.8, or no greater than 0.6, or no greater than 0.5, etc. For example, the ratio H/H of the height H of the second ring magnetic element 708 to the thickness H of the first magnetic element 702 may be equal to 0.4. The ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R may be in the range of 0.05-0.50, or 0.1-0.35, or 0.1-0.3, or 0.1-0.25, or 0.1-0.20, etc. For example, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R may be in the range of 0.16-0.18.

In some embodiments, the two parameters w/R and H/H may be optimized with the ratio of the thickness H of the first magnetic element 702 to the magnetic circuit radius R unchanged (i.e., R/H unchanged) such that the magnetic induction at the magnetic gap and the ampere force experienced by the voice coil are maximized, i.e., the driving force coefficient BL is maximized. For more description about the relationship between the parameters w/R and H/H and the driving force coefficient BL, reference may be made to the detailed description in fig. 7B. In some embodiments, the magnetic induction intensity at the magnetic gap and the ampere force suffered by the coil can be maximized, namely the driving force coefficient BL value can be maximized by setting different R/H and adjusting two parameters of w/R and H/H. For more description of the relationship between the parameter R/H, w/R, H/H and the driving force coefficient BL, reference may be made to the detailed description in FIGS. 7C-7E.

Fig. 7B is a plot of the driving force coefficient at voice coil 720 versus the magnetic circuit assembly parameters shown in fig. 7A, according to some embodiments of the present application. As shown in fig. 7B, when the ratio of the magnetic circuit radius R to the thickness H of the first magnetic element 702 is unchanged (i.e., R/H is unchanged), the driving force coefficient BL varies with the variation of the parameters w/R and H/H. In some embodiments, when the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R is unchanged, the greater the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702, the greater the driving force coefficient BL. Further, if the magnetic circuit size (i.e., the magnetic circuit radius R) is unchanged, the greater the height H of the second annular magnetic element 708, the greater the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 may be, and the greater the driving force coefficient BL. However, as the height h of the second annular magnetic element 708 increases, the distance between the second annular magnetic element 708 and the voice coil 720 becomes smaller, and the voice coil 720 and the second annular magnetic element 708 are easy to collide during vibration to generate sound breaking, thereby affecting the sound quality of the bone conduction earphone. As shown in fig. 7B, the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 may be no greater than 0.8, or no greater than 0.6, or no greater than 0.5, etc. For example, the ratio H/H of the height H of the second ring magnetic element 708 to the thickness H of the first magnetic element 702 may be equal to 0.4.

In some embodiments, when the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 is constant, the driving force coefficient BL may become larger and smaller as the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R increases. The ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R corresponding to the maximum driving force coefficient BL is within a certain range. For example, when the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 is 0.4, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R may be in the range of 0.08-0.25 if the driving force coefficient BL is maximized. When the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 is different, the range of the maximum driving force coefficient BL corresponding to the different ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R is changed. For example, when the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 is 0.72, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic path radius R may be in the range of 0.04-0.20. For a more description of the range of values of the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R at the maximum driving force coefficient BL, reference may be made to fig. 7C-7E.

Fig. 7C-7E are graphs showing driving force coefficients at voice coil 720 versus parameters of the magnetic circuit assembly shown in fig. 7A, according to some embodiments of the present application. As shown in fig. 7C-7E, the driving force coefficient BL of the voice coil 720 in the magnetic circuit assembly 7000 varies with the variations of the parameters R/H, w/R and H/H of the magnetic circuit assembly 7000. As shown in fig. 7C, when the ratio R/H of the magnetic radius R to the thickness H of the first magnetic element 702 is 2.0 and 2.4, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic radius R may be in the range of 0.05-0.20, or 0.05-0.15, or 0.05-0.25, or 0.1-0.18, etc. As shown in fig. 7D, when the ratio R/H of the magnetic path radius R to the thickness H of the first magnetic element 702 is 2.8 and 3.2, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic path radius R may be in the range of 0.05-0.25, or 0.1-0.20, or 0.05-0.30, or 0.10-0.25. As shown in fig. 7E, when the ratio R/H of the magnetic path radius R to the thickness H of the first magnetic element 702 is 3.6 and 4.0, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic path radius R may be in the range of 0.05-0.20, or 0.10-0.15, or 0.05-0.25, or 0.10-0.20.

Referring to fig. 7C-7E, when the ratio H/H of the height H of the second annular magnetic element 708 to the thickness H of the first magnetic element 702 is 0.4, the ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R may be in the range of 0.15-0.20, or 0.16-0.18, if the driving force coefficient BL is maximized.

Fig. 8A is a schematic structural diagram of a magnetic circuit assembly 8000 according to some embodiments of the present application. As shown, the magnetic circuit assembly 8000 may include a first magnetic element 802, a first magnetically permeable element 804, a first annular magnetic element 806, a second annular magnetic element 808, and a magnetically permeable cover 814. The first ring magnetic element 806 may also be referred to as a first full magnetic field altering element (e.g., the first full magnetic field altering element 406 described in fig. 4A). The first magnetic element 802, the first magnetically permeable element 804, the first annular magnetic element 806, the second annular magnetic element 808, and the magnetically permeable cover 804 may be described in detail with reference to fig. 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, and/or 4I herein. For example, the first annular magnetic element 806 may be integrally formed of magnetic material, or may be formed by splicing and combining a plurality of magnetic elements. The second annular magnetic element 808 may be formed by integrally molding a magnetic material, or may be formed by splicing and combining a plurality of magnetic elements. For another example, the magnetically permeable cover 814 surrounds the first magnetic element 802, the first annular magnetic element 806, and the second annular magnetic element 808. In some embodiments, the magnetically permeable cover 814 may include a bottom plate and side walls that are annular in configuration. In some embodiments, the floor and side walls may be integrally formed. The first magnetic element 802, the first magnetic conductive element 804, the first annular magnetic element 806, and the second annular magnetic element 808 may form a magnetic circuit and a magnetic gap. A voice coil 820 may be placed in the magnetic gap. Voice coil 820 may be circular or non-circular. The non-circular shape may include an oval, triangle, quadrilateral, pentagon, other polygon, or other irregular shape.

Parameters of the magnetic circuit assembly 8000 may include a thickness H of the first magnetic element 802 (as shown in fig. 8A, i.e., a height H of the first magnetic element 802), a thickness w of the first annular magnetic element 806, a height H of the second annular magnetic element 808, a magnetic circuit radius R, and so forth. In some embodiments, the magnetic circuit (i.e., magnetic circuit) radius R may be equal to the distance between the central axis of the magnetic circuit assembly 8000 (shown in phantom in fig. 8A) and the outer wall of the first annular magnetic element 806. In some embodiments, the parameters of the magnetic circuit assembly 8000 may also include a ratio of a magnetic circuit radius R to a thickness H of the first magnetic element 802 (which may be expressed as R/H), a ratio of a thickness w of the first annular magnetic element 806 to a magnetic circuit radius R (which may be expressed as w/R), a ratio of a height H of the second annular magnetic element 808 to a thickness H of the first magnetic element 802 (which may be expressed as H/H), and so forth. In some embodiments, the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 802 ranges from 2.0 to 4.0. For example, the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 802 may be 2.0, 2.4, 2.8, 3.2, 3.6, 4.0. The ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 may be no greater than 0.8, or no greater than 0.6, or no greater than 0.5, etc. For example, the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 702 may be equal to 0.4. The ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be in the range of 0.02-0.50, or 0.05-0.35, or 0.05-0.25, or 0.1-0.20, etc. For example, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be in the range of 0.16-0.18. In some embodiments, the two parameters w/R and H/H may be optimized with the thickness H of the first magnetic element 802 and the magnetic circuit radius R unchanged (i.e., R/H unchanged) such that the magnetic induction at the magnetic gap and the ampere force experienced by the coil are maximized, i.e., the driving force coefficient BL is maximized. Reference may be made to the detailed description in fig. 8B regarding the relationship between the parameters w/R and H/H and the driving force coefficient BL. In some embodiments, the two parameters w/R and H/H may be adjusted with varying R/H such that the magnetic induction at the magnetic gap and the ampere force experienced by the coil are maximized, i.e., the driving force coefficient BL is maximized. Reference is made to the detailed description in fig. 8C-8E regarding the relation between the parameter R/H, w/R, H/H and the driving force coefficient BL.

Fig. 8B is a plot of driving force coefficient at voice coil 820 versus parameters of the magnetic circuit assembly shown in fig. 8A, according to some embodiments of the present application. As shown in fig. 8B, when the ratio of the magnetic circuit radius R to the thickness H of the first magnetic element 802 is unchanged (i.e., R/H is unchanged), the driving force coefficient BL varies with the variation of the parameters w/R and H/H. In some embodiments, when the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R is unchanged, the greater the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802, the greater the driving force coefficient BL. Further, the greater the height H of the second annular magnetic element 808, the greater the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 702 may be, the greater the driving force coefficient BL. As shown in fig. 8B, the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 may be no greater than 0.8, or no greater than 0.6, or no greater than 0.5. For example, the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 may be equal to 0.4.

In some embodiments, when the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 is constant, the driving force coefficient BL varies with the variation of the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R. For example, when the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 is 0.4, the driving force coefficient BL decreases as the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R increases first. When the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 is different, the range of the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R, in which the maximum driving force coefficient BL is different, is changed. For example, when the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 is 0.4, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic path radius R is in the range of 0.02-0.22. When the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 is 0.72, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be in the range of 0.02-0.16 if the driving force coefficient BL is maximized.

As shown in connection with fig. 7B, when the parameters R/H, w/R, H/H of the magnetic circuit assemblies 8000 and 7000 are the same, the driving force coefficient BL of the voice coil in the magnetic circuit assembly 8000 with the magnetic shield is larger than the driving force coefficient BL in the magnetic circuit assembly 7000 without the magnetic shield, i.e., the ampere force received by the voice coil in the magnetic circuit assembly 8000 is larger than the ampere force received in the magnetic circuit assembly 7000. For example, as shown in fig. 7B and 8B, if w/R and H/H are about 0.21 and 0.4, respectively, the driving force coefficient BL of the voice coil in the magnetic circuit assembly 8000 is 2.817, and the driving force coefficient BL in the magnetic circuit assembly 7000 is 2.376.

Fig. 8C-8E are graphs showing driving force coefficients at voice coil 820 versus parameters of the magnetic circuit assembly shown in fig. 8A, according to some embodiments of the present application. As shown in fig. 8C-8E, the driving force coefficient BL of the voice coil 820 in the magnetic circuit assembly 8000 varies with the variations of the parameters R/H, w/R and H/H of the magnetic circuit assembly 8000. As shown in fig. 8C, when the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 802 is 2.0 and 2.4, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be in the range of either 0.02-0.15, or 0.05-0.15, or 0.02-0.20. As shown in fig. 8D, when the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 802 is 2.8 and 3.2, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be 0.01-0.20, or 0.05-0.15, or 0.02-0.25, or 0.10-0.15. As shown in fig. 8E, when the ratio R/H of the magnetic circuit radius R to the thickness H of the first magnetic element 802 is 3.6 and 4.0, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be in the range of 0.02-0.20, or 0.05-0.15, or 0.05-0.25, or 0.10-0.20.

Referring to fig. 8C-8E, when the ratio H/H of the height H of the second annular magnetic element 808 to the thickness H of the first magnetic element 802 is 0.4, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic circuit radius R may be in the range of 0.05-0.20 or 0.16-0.18 if the driving force coefficient BL is maximized. Comparing fig. 7C and 8C, fig. 7D and 8D, and fig. 7E and 8E, respectively, when the ratio R/H of the magnetic path radius R to the thickness H of the first magnetic element 802 is the same, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 806 in the magnetic assembly 8000 with the magnetic shield to the magnetic path radius R changes in a decreasing trend with respect to the magnetic assembly 7000. For example, when the ratio R/H of the magnetic path radius R to the thickness H of the first magnetic element 802 (or 702) is 2.0, if the driving force coefficient BL is maximized, the ratio w/R of the thickness w of the first annular magnetic element 806 to the magnetic path radius R in the magnetic assembly 8000 with the magnetic shield is in the range of 0.02-0.15. The ratio w/R of the thickness w of the first annular magnetic element 706 to the magnetic circuit radius R in the magnetic assembly 7000 without the magnetically permeable cover is in the range of 0.05-0.25.

Fig. 9A is a schematic diagram of a magnetic induction line distribution of a magnetic circuit assembly 900 according to some embodiments of the present application. As shown, the magnetic circuit assembly 900 may include a first magnetic element 902, a first magnetically permeable element 904, a second magnetically permeable element 906, and a second magnetic element 914. The first magnetic element 902, the first magnetic element 904, the second magnetic element 906, and the second magnetic element 914 may refer to the detailed description of the first magnetic element 302, the first magnetic element 304, the second magnetic element 306, and the second magnetic element 314 in fig. 3D of the present application. The magnetization direction of the first magnetic element 902 is opposite to that of the second magnetic element 914, and the magnetic induction lines generated by the first magnetic element 902 interact with the magnetic induction lines generated by the second magnetic element 914, so that the magnetic induction lines generated by the first magnetic element 902 and the magnetic induction lines generated by the second magnetic element 914 can pass through the voice coil 928 more perpendicularly, and leakage magnetic induction lines of the magnetization direction of the first magnetic element 902 at the voice coil 928 are reduced.

Fig. 9B is a plot of magnetic induction at a voice coil versus thickness of components in the magnetic circuit assembly 900 shown in fig. 9A, according to some embodiments of the present application. The abscissa is the ratio of the thickness (h2+h3+h5) of the first magnetic element 902 to the sum of the thickness (h 3) of the first magnetic element 902, the thickness (h 2) of the first magnetic conductive element 904, and the thickness (h 5) of the second magnetic element 914, hereinafter referred to as the first thickness ratio. The ordinate is the normalized magnetic induction at the voice coil 928, which may be the ratio of the actual magnetic induction at the voice coil 928 to the maximum magnetic induction at the magnetic circuit formed by the single magnetic circuit assembly. The single magnetic circuit assembly may refer to a magnetic circuit formed by the magnetic circuit assembly including only one magnetic element. For example, the single magnetic circuit assembly may include a first magnetic element, a first magnetically permeable element, and a second magnetically permeable element. The volume of the magnetic elements in the single magnetic circuit assembly is equal to the sum of the volumes of the magnetic elements in the multiple magnetic circuit assemblies (e.g., the first magnetic element 902 and the second magnetic element 914 in the magnetic circuit assembly 900) corresponding to the single magnetic circuit assembly. k is the ratio of the thickness (h 2) of the first magnetic conductive element 904 to the sum of the thicknesses (h2+h3+h5) of the first magnetic conductive element 902, the first magnetic conductive element 904, and the second magnetic conductive element 914, and is hereinafter referred to as a second thickness ratio (denoted by "k" in the figure). As shown in the figure, as the first thickness ratio gradually increases, the magnetic induction intensity at the voice coil 928 gradually increases and gradually decreases after reaching a certain value, that is, the magnetic induction intensity at the voice coil 928 has a maximum value, and the range of the first thickness ratio corresponding to the maximum value is between 0.4 and 0.6. The second thickness ratio corresponding to the maximum value is in the range of 0.26-0.34.

FIG. 10A is a schematic diagram of a magnetic induction line distribution of a magnetic group 1000 according to some embodiments of the present application. As shown, magnetic circuit assembly 1000 may include a first magnetic element 1002, a first magnetic conductive element 1004, a second magnetic conductive element 1006, a second magnetic conductive element 1014, and a third magnetic conductive element 1016. The first magnetic element 1002, the first magnetic element 1004, the second magnetic element 1006, the second magnetic element 1014, and the third magnetic element 1016 may be referred to in the detailed description of the first magnetic element 302, the first magnetic element 304, the second magnetic element 306, the second magnetic element 308, the second magnetic element 314, and the third magnetic element 316 in fig. 3E of the present application. Wherein the third magnetically permeable element 1016 is not connected to the second magnetically permeable element 1006. The magnetization direction of the first magnetic element 1002 is opposite to that of the second magnetic element 1014, and the magnetic induction lines generated by the first magnetic element 1002 interact with the magnetic induction lines generated by the second magnetic element 1014, so that the magnetic induction lines generated by the first magnetic element 1002 and the magnetic induction lines generated by the second magnetic element 1014 can pass through the voice coil 1028 more perpendicularly, and leakage magnetic induction lines of the first magnetic element 1002 at the voice coil 1028 are reduced. The third magnetically permeable plate 1016 further reduces the magnetic induction line of the leakage of the first magnetic element 1002 at the voice coil 1028.

Fig. 10B is a plot of magnetic induction at a voice coil versus thickness of components in a magnetic circuit assembly, according to some embodiments of the present application. The curve a corresponds to the magnetic circuit assembly 900 shown in fig. 9A, and the curve b corresponds to the magnetic circuit assembly 1000 shown in fig. 10A. The first thickness ratio is plotted on the abscissa and the normalized magnetic induction at voice coil 928 or 1028 is plotted on the ordinate, and reference is made to the detailed description of fig. 9B of the present application. Curve a is a variation curve of the magnetic induction intensity of the voice coil 928 in the magnetic circuit assembly 900 with respect to the first thickness ratio, and curve b is a variation curve of the magnetic induction intensity of the voice coil 1028 in the magnetic circuit assembly 1000 with respect to the first thickness ratio. As shown in fig. 10B, the magnetic circuit assembly 1000 provided with the third magnetic conductive element 1016 has a magnetic induction intensity at the voice coil 1028 significantly stronger than that at the voice coil 928 (e.g., the magnetic induction intensity corresponding to the curve B is higher than that corresponding to the curve a) in the case that the first thickness ratio is in the range of 0-0.55. In the case where the first thickness ratio ranges between 0.55-1, the magnetic induction at voice coil 1028 is significantly lower than the magnetic induction at voice coil 928 (e.g., curve b corresponds to a lower magnetic induction than curve a).

Fig. 11A is a schematic diagram illustrating a magnetic induction line distribution of a magnetic circuit assembly 1100 according to some embodiments of the present application. As shown, the magnetic circuit assembly 1100 may include a first magnetic element 1102, a first magnetic conductive element 1104, a second magnetic conductive element 1106, a second magnetic conductive element 1114, and a third magnetic conductive element 1116. The first magnetic element 1102, the first magnetic element 1104, the second magnetic element 1106, the second magnetic element 1114, and the third magnetic element 1116 may be referred to in the detailed description of the first magnetic element 302, the first magnetic element 304, the second magnetic element 306, the second magnetic element 308, the fifth magnetic element 314, and the third magnetic element 316 in fig. 3E of the present application. The third magnetically permeable element 1116 is connected to the second magnetically permeable element 1106. The magnetization direction of the first magnetic element 1102 is opposite to the magnetization direction of the second magnetic element 1114. The magnetic fields of the first magnetic element 1102 and the second magnetic element 1114 repel each other at the interface of the first magnetic element 1102 and the second magnetic element 1114 such that an otherwise divergent magnetic field (e.g., a magnetic field generated by only the first magnetic element 1102 or a magnetic field generated by only the second magnetic element 1114) may pass through the voice coil 1128 under the influence of the mutually repulsive magnetic field, thereby increasing the magnetic field strength at the voice coil 1128. The third magnetic conductive plate 1116 is connected with the second magnetic conductive element 1106, so that the magnetic fields of the second magnetic element 1114 and the first magnetic element 1102 are bound in the magnetic loop formed by the second magnetic conductive element 1106 and the third magnetic conductive element 1116, and the magnetic induction intensity at the voice coil 1128 is further increased.

Fig. 11B is a graph showing magnetic induction versus thickness of various elements of a magnetic circuit assembly according to some embodiments of the present application. The curve a corresponds to the magnetic circuit assembly 900 shown in fig. 9A, the curve b corresponds to the magnetic circuit assembly 1000 shown in fig. 10A, and the curve c corresponds to the magnetic circuit assembly 1100 shown in fig. 11A. The abscissa is the ratio of the thickness (h 3) of the first magnetic element (902, 1002, 1102) to the sum (h3+h5) of the thicknesses of the first magnetic element (902, 1002, 1102) and the second magnetic element (914, 1014, 1114), hereinafter referred to as the third thickness ratio. The ordinate is the normalized magnetic induction at the voice coil (928, 1028, 1128), which can be referred to in the detailed description of fig. 9B of the present application. Curve a is the magnetic induction of voice coil 928 versus the first thickness ratio, curve b is the magnetic induction of voice coil 1028 versus the first thickness ratio in magnetic circuit assembly 1000, and curve c is the magnetic induction of voice coil 1128 versus the first thickness ratio in magnetic circuit assembly 1100. As shown in fig. 11B, in the case of the magnetic circuit assemblies 1000 and 1100 including the third magnetic conductive element (e.g., the magnetic conductive element 1014, the magnetic conductive element 1114), the magnetic induction intensity at the corresponding voice coil (e.g., the voice coil 1028, the voice coil 1128) is stronger than the magnetic induction intensity at the voice coil 928 in the magnetic circuit assembly 900 without the third magnetic conductive element (e.g., the magnetic induction intensity corresponding to the curve B, the curve c is higher than the magnetic induction intensity corresponding to the curve a) when the first thickness ratio is smaller than 0.7. When the third magnetically permeable element is connected to the second magnetically permeable element (e.g., the third magnetically permeable element 1116 and the second magnetically permeable element 1106 in the magnetic circuit assembly 1100 are connected to each other), the magnetic induction at the voice coil 1128 is stronger than the magnetic induction at the voice coil 1028 (e.g., the magnetic induction corresponding to curve c is higher than the magnetic induction corresponding to curve b).

Fig. 11C is a plot of magnetic induction at a voice coil versus thickness of components in the magnetic circuit assembly 1100 shown in fig. 11A, according to some embodiments of the present application. The second thickness ratio (denoted by "h 2/(h2+h3+h5)" in the figure) is on the abscissa, and the normalized magnetic induction at the voice coil 1128 is on the ordinate, and reference is made to the detailed description in fig. 9B of the present application. As shown in fig. 11C, as the second thickness ratio gradually increases, the magnetic induction intensity at the voice coil 1128 gradually increases to a maximum value and then decreases. The range of the second thickness ratio corresponding to the maximum magnetic induction intensity is between 0.3 and 0.6.

Fig. 12A is a schematic structural diagram of a magnetic circuit assembly 1200 according to some embodiments of the present application. As shown, bone conduction speaker 1200 may include a first magnetic element 1202, a first magnetically permeable element 1204, a second magnetically permeable element 1206, and a first electrically conductive element 1208. The first magnetic element 1202, the first magnetically permeable element 1204, the second magnetically permeable element 1206, and the first electrically conductive element 1208 may be referred to in the relevant description herein. The first conductive element 1204 may protrude from the first magnetic element 1202 to form a first recess, and the first conductive element 1208 may be disposed in communication with the first recess and connect the first magnetic element 1202.

The first magnetic element 1202, the first magnetic conductive element 1204, and the second magnetic conductive element 1206 may form a magnetic gap. The voice coil 1210 may be placed in the magnetic gap. The cross-sectional shape of the voice coil 1210 may be circular or non-circular, such as oval, rectangular, square, pentagonal, other polygonal, or other irregular shape. In some embodiments, an alternating current may be passed through voice coil 1210, with the alternating current being directed inward, as shown, perpendicular to the page. In the magnetic circuit formed by the first magnetic element 1202, the first magnetic conductive element 1204, and the second magnetic conductive element 1206, the voice coil 1210 can generate an alternating induced magnetic field a (which may also be referred to as a "first alternating induced magnetic field") under the action of a magnetic field in the magnetic circuit, where the induced magnetic field a is in a counterclockwise direction (as shown by a). The alternating induced magnetic field a causes a reverse induced current to be generated in the voice coil 1210, thereby reducing the current in the voice coil 1210. The first conductive element 1208 may generate an alternating induced current under the alternating induced magnetic field a, which may generate an alternating induced magnetic field B (which may also be referred to as a "second alternating induced magnetic field") under the magnetic field in the magnetic loop. The direction of the induced magnetic field B is counterclockwise (as shown by B). Since the direction of the induced magnetic field a is opposite to that of the induced magnetic field B, the reverse induced current in the voice coil 1210 is reduced, that is, the inductance in the voice coil 1210 is reduced, and the current in the voice coil 1210 is increased.

The above description of the structure of the magnetic circuit assembly 1200 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 1200 may be made without departing from this principle, but remain within the scope of the foregoing description. For example, the first conductive element 1208 may be disposed adjacent to the voice coil 1210, such as an inner wall, an outer wall, an upper surface, and/or a lower surface of the voice coil 1210.

Fig. 12B is a graph illustrating the effect of a conductive element on inductive reactance in a voice coil in the magnetic circuit assembly 1200 shown in fig. 12A according to some embodiments of the present application. Wherein curve a corresponds to the magnetic circuit assembly 1200 without the first conductive element 1208, and curve b corresponds to the magnetic circuit assembly 1200 with the first conductive element 1208. The abscissa is the frequency of the alternating current in the voice coil 1210 and the ordinate is the inductive reactance in the voice coil 1210. As shown in fig. 12B, when the alternating current frequency increases to about 1200HZ, the inductance in the voice coil 1210 increases with the increase in the alternating current frequency, and in the case where the first conductive element 1208 is provided, the inductance in the voice coil is significantly lower than that in the voice coil when the first conductive element 1208 is not provided (e.g., the inductance corresponding to curve B is lower than that corresponding to curve a).

Fig. 13A is a schematic structural diagram of a magnetic circuit assembly 1300 according to some embodiments of the present application. As shown, the magnetic circuit assembly 1300 may include a first magnetic element 1302, a first magnetically permeable element 1304, a second magnetically permeable element 1306, and a first electrically conductive element 1318. The first magnetic element 1302, the first magnetically permeable element 1304, the second magnetically permeable element 1306, and the first electrically conductive element 1318 may be referred to in the relevant description herein. The first conductive element 1318 may be coupled to an upper surface of the first magnetically permeable element 1304. The shape of the first conductive element 1318 may be a sheet, ring, mesh, aperture plate, or the like.

The first magnetic element 1302, the first magnetically permeable element 1304, and the second magnetically permeable element 1306 may form a magnetic gap. A voice coil 1328 may be placed in the magnetic gap. The cross-sectional shape of the voice coil 1328 may be circular or non-circular. The non-circular shape may include an oval, triangle, quadrilateral, pentagon, other polygon, or other irregular shape.

The above description of the structure of the magnetic circuit assembly 1300 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 1300 may be made without departing from this principle, but such modifications and changes remain within the scope of the foregoing description. For example, the first conductive element 1318 may be disposed adjacent to the voice coil 1328, such as an inner wall, an outer wall, an upper surface, and/or a lower surface of the voice coil 1328.

Fig. 13B is a graph illustrating the effect of magnetically permeable elements on inductive reactance in a voice coil in the magnetic circuit assembly 1300 of fig. 13A according to some embodiments of the present application. The curve a corresponds to the magnetic circuit assembly 1300 without the first conductive element 1318, and the curve b corresponds to the magnetic circuit assembly 1300 with the first conductive element 1318. The abscissa is the frequency of the alternating current in the voice coil 1110 and the ordinate is the inductive reactance in the voice coil 1110. As shown in fig. 13B, when the alternating current frequency increases to about 1200HZ, the inductance in the voice coil 1110 increases with the increase in the alternating current frequency, and when the first conductive element 1318 is provided, the inductance in the voice coil 1110 is significantly lower than that when the first conductive element 1318 is not provided (e.g., the inductance corresponding to curve B is lower than that corresponding to curve a).

Fig. 14A is a schematic structural diagram of a magnetic circuit assembly 1400, according to some embodiments of the present application. As shown, magnetic circuit assembly 1400 may include a first magnetic element 1402, a first magnetically permeable element 1404, a second magnetically permeable element 1406, a first electrically conductive element 1418, a second electrically conductive element 1420, and a third electrically conductive element 1422. The first magnetic element 1402, the first magnetic conductive element 1404, the second magnetic conductive element 1406, the first conductive element 1418, the second conductive element 1420, and the third conductive element 1422 may be referred to in connection with the description of fig. 3F of the present application. The first magnetic element 1302, the first magnetically permeable element 1304, and the second magnetically permeable element 1306 may form a magnetic gap. A voice coil 1428 may be placed in the magnetic gap. The cross-sectional shape of the voice coil 1428 may be circular or non-circular. The non-circular shape may include an oval, triangle, quadrilateral, pentagon, other polygon, or other irregular shape.

The above description of the structure of the magnetic circuit assembly 1400 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 1400 may be made without departing from this principle, but such modifications and changes remain within the scope of the foregoing description. For example, the first conductive element 1418 may be disposed adjacent to the voice coil 1428, such as an inner wall, an outer wall, an upper surface, and/or a lower surface of the voice coil 1428.

Fig. 14B is a graph showing the effect of the number of conductive elements in the magnetic circuit assembly 1420 of fig. 14A on the inductive reactance in the voice coil, according to some embodiments of the present application. Curve m corresponds to a magnetic circuit assembly without a conductive element, curve n corresponds to a magnetic circuit assembly with one conductive element (such as magnetic circuit assembly 1200 shown in fig. 12A), and curve l corresponds to a magnetic circuit assembly with a plurality of conductive elements (such as magnetic circuit assembly 1400 shown in fig. 14A). The abscissa is the frequency of the alternating current in the voice coil, and the ordinate is the inductive reactance in the voice coil. As shown in fig. 14B, when the alternating current frequency increases to about 1200HZ, the inductance in the voice coil increases with the increase in the alternating current frequency, and in the case where one or more conductive elements are provided, the inductance in the voice coil is significantly lower than that in the voice coil when no conductive element is provided (e.g., the inductance corresponding to curves n and l is lower than that corresponding to curve m). In the case where a plurality of conductive elements are provided, the inductance in the voice coil is significantly lower than that in the case where one conductive element is provided (e.g., the inductance corresponding to curve l is lower than that corresponding to curve n).

Fig. 15A is a schematic structural diagram of a magnetic circuit assembly 1500, according to some embodiments of the present application. As shown, the magnetic circuit assembly 1500 may include a first magnetic element 1502, a first magnetically permeable element 1504, a first annular element 1506, a first annular magnetic element 1508, a second annular magnetic element 1510, a third annular magnetic element 1512, a magnetically permeable cover 1514, and a second magnetic element 1516. The first magnetic element 1502, the first magnetically permeable element 1504, the first annular element 1506, the first annular magnetic element 1508, the second annular magnetic element 1510, the third annular magnetic element 1512, the magnetically permeable cover 1514, and the second magnetic element 1516 may be described in detail herein with reference to fig. 4A, 4B, 4C, 4D, 4E, 4F, 4G, 4H, and/or 4I.

The first magnetic element 1502, the first magnetically permeable element 1504, the second magnetic element 1516, the second annular magnetic element 1510, and/or the third annular magnetic element 1512 may form a magnetic gap. A voice coil 1528 may be placed in the magnetic gap. Voice coil 1528 may be circular or non-circular. The non-circular shape may include an oval, triangle, quadrilateral, pentagon, other polygon, or other irregular shape.

The above description of the structure of the magnetic circuit assembly 1500 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the magnetic circuit assembly 1500 may be made without departing from this principle, but such modifications and changes remain within the scope of the foregoing description. For example, the magnetic circuit assembly 1500 may further include one or more conductive elements that may be disposed proximate to the voice coil 1528, such as an inner wall, an outer wall, an upper surface, and/or a lower surface of the voice coil 1528. In some embodiments, the conductive elements may connect the first magnetic element 1502, the second magnetic element 1516, the first annular magnetic element 1508, the second annular magnetic element 1510, and/or the third annular magnetic element 1512. For another example, the magnetic circuit assembly 1500 may further include a third magnetically permeable element coupled to the second magnetic element 1516.

Fig. 15B is a plot of amperage applied to a voice coil versus thickness of a magnetic element in the magnetic circuit assembly 1500 of fig. 15A, according to some embodiments of the present application. Wherein the abscissa is a first thickness ratio and the ordinate is a normalized ampere force received by the voice coil, which may refer to a ratio of an actual ampere force received by the voice coil to a maximum ampere force received in the single magnetic circuit assembly. The single magnetic circuit assembly may include one magnetic element, for example, the single magnetic circuit assembly may include a first magnetic element, a first magnetically permeable element, and a second magnetically permeable element. The volume of the first magnetic element in the single magnetic circuit assembly is the same as the sum of the volumes of the first magnetic element 1502 and the second magnetic element 1516 in the magnetic circuit assembly 1500. The first thickness ratio and the second thickness ratio may be described in detail with reference to fig. 9B of the present application. As shown in fig. 15B, for any second thickness ratio k, the ordinate value is greater than 1, i.e., the ampere force experienced by the voice coil 1528 in the magnetic circuit assembly 1500 is greater than the ampere force experienced by the voice coil in a single magnetic circuit assembly. As the second thickness ratio k remains the same, the ampere force experienced by the voice coil 1528 gradually decreases as the first thickness ratio increases. While the first thickness ratio remains the same, the ampere force experienced within the voice coil 1528 increases gradually as the second thickness ratio k decreases. When the first thickness ratio ranges from 0.1 to 0.3 or the second thickness ratio k ranges from 0.2 to 0.7, the ampere force applied to the voice coil 1528 is improved by 50% -60% compared to the ampere force applied to the voice coil in a single magnetic circuit assembly.

Fig. 16 is a schematic diagram of a bone conduction speaker 1600 according to some embodiments of the present application. As shown, bone conduction speaker 1600 may include first magnetic element 1602, first magnetic element 1604, second magnetic element 1606, second magnetic element 1608, voice coil 1610, third magnetic element 1612, support 1614, and connection 1616. First magnetic element 1602, first magnetic element 1604, second magnetic element 1606, second magnetic element 1608, voice coil 1610, and/or third magnetic element 1612 may be referred to in the relevant description of other figures herein.

The upper surface of the first magnetic element 1602 may be connected to the lower surface of the first magnetic element 1604. A lower surface of the second magnetic element 1608 may be coupled to an upper surface of the first magnetic element 1604. The second magnetically permeable element 1606 may include a first bottom plate and a first side wall. The lower surface of the first magnetic element 1602 may be connected to the upper surface of the first base plate. The sidewalls of second magnetic element 1606 form magnetic gaps with the sidewalls of first magnetic element 1602, first magnetic element 1604, and/or second magnetic element 1608. The support 1614 may include a second floor and a second sidewall. After the bracket 1614 is coupled to the voice coil 1610, the voice coil 1610 may be disposed in the magnetic gap. Voice coil 1610 may be attached to the second side wall. A side seam may be formed between the upper surface of the voice coil 1610 and the second chassis. When the voice coil 1610 is disposed in the magnetic gap, the third magnetic conductive element 1612 may pass through the side slot to connect the upper surface of the second magnetic conductive element 1608 and the first side wall of the second magnetic conductive element 1606, so that the third magnetic conductive element 1612 and the second magnetic conductive element 1606 form a closed cavity. The connection between the first magnetic element 1602, the first magnetic element 1604, the second magnetic element 1606, the second magnetic element 1608, the voice coil 1610, and/or the third magnetic element 1612 may be by any one or more of the connection means described herein. In some embodiments, one or more hole-like structures (e.g., pin holes, threaded holes, etc.) may be provided on the first magnetic element 1602, the first magnetic element 1604, the second magnetic element 1606, the second magnetic element 1608, the third magnetic element 1612, and/or the support 1614. The aperture-like structures may be disposed in a central, peripheral, or other location of the first magnetic element 1602, the first magnetic element 1604, the second magnetic element 1606, the second magnetic element 1608, the third magnetic element 1612, and/or the support 1614. A connector 1616 may extend through the aperture structure and connect the various elements. For example, the connector 1616 may be a pipe pin. The pin 1616 may be stamped and deformed through the bracket 1614 using a stamping head to secure the various components in the bone conduction speaker 1600.

The above description of the structure of bone conduction speaker 1600 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and details of the specific manner and steps of implementing the bone conduction speaker 1600 may be made without departing from this principle, but such modifications and changes remain within the scope of the foregoing description. For example, bone conduction speaker 1600 may include one or more conductive elements disposed on the inner side wall, outer wall, top, and/or bottom of voice coil 1610. For another example, bone conduction speaker 1600 may further include one or more annular magnetic elements that may be attached to an upper surface of a sidewall of second magnetic element 1606 or fixed in a magnetic gap.

Fig. 17 is a schematic diagram of a bone conduction speaker 1700 according to some embodiments of the present application. As shown, bone conduction speaker 1700 may include first magnetic element 1702, first magnetic element 1704, second magnetic element 1706, second magnetic element 1708, voice coil 1710, third magnetic element 1712, bracket 1714, connector 1716, bracket link 1718, and gasket 1720. The upper surface of the first magnetic element 1702 may be connected to the lower surface of the first magnetic conductive element 1706. The lower surface of the second magnetic element 1708 may be coupled to the upper surface of the first magnetic conductive element 1706. The second magnetically permeable element 1706 may include a first bottom plate and a first sidewall, and the first sidewall may be formed by the bottom plate extending along a direction perpendicular to the bottom plate. The lower surface of the first magnetic element 1702 may be connected to the upper surface of the bottom plate of the second magnetic element 1706. The sidewalls of the second magnetically permeable element 1706 form magnetic gaps with the sidewalls of the first magnetic element 1702, the first magnetically permeable element 1704, and/or the second magnetic element 1708. One or more rod-like structures may be provided around the support links 1718. Voice coil 1710 can be coupled to a carrier rod 1718. After the bracket link 1718 is coupled to the voice coil 1710, the voice coil 1710 may be disposed in the magnetic gap. The third magnetic conductive element 1712 may include a second bottom plate and a second side wall, where the second side wall may be formed by extending the second bottom plate, and the second side wall may be provided with one or more first hole structures, where the first hole structures correspond to the rod structures of the support links 1718, and the rod structures of the support links 1718 may penetrate through the first hole structures of the third magnetic conductive element 1712. After the voice coil 1710 is placed in the magnetic gap, the second side wall of the third magnetic conductive element 1712 may be connected to the rod-shaped structure of the support rod 1718 through the first hole-shaped structure, and the second bottom plate may be connected to the upper surface of the second magnetic element 1708. The connection between the first magnetic element 1702, the first magnetic conductive element 1704, the second magnetic conductive element 1706, the second magnetic conductive element 1708, the voice coil 1710, and/or the third magnetic conductive element 1712 may be by any one or several connection methods described herein. In some embodiments, the first magnetic element 1702, the first magnetic conductive element 1704, the second magnetic conductive element 1706, the second magnetic conductive element 1708, the third magnetic conductive element 1712, and/or the support 1714 may be provided with a second hole-like structure at a center, around, or other location. A connector 1716 may extend through the aperture structure and connect the various elements. For example, the connector 1716 may be a pipe pin. The pin 1716 may be punched and deformed through the frame 1714 using a punch to secure the first magnetic element 1702, the first magnetic conductive element 1704, the second magnetic conductive element 1706, the second magnetic conductive element 1708, and the third magnetic conductive element 1712. The bracket 1914 may be coupled to the bracket rail 1718, and the gasket 1920 may further couple the second side wall of the third magnetically permeable element 1712 and the first side wall of the second magnetically permeable element 1706 to further secure the second magnetically permeable element 1706 and the third magnetically permeable element 1712. In some embodiments, the gasket 1720 may be coupled to the housing 1714 by a vibrating plate.

The above description of the structure of bone conduction speaker 1700 is merely a specific example and should not be considered the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and details of the specific manner and steps of implementing bone conduction speaker 1700 may be made without departing from this principle, while still being within the scope of the foregoing description, after understanding the basic principles of the magnetic circuit assembly. For example, bone conduction speaker 1700 may include one or more conductive elements disposed on the inner side wall, outer wall, top, and/or bottom of voice coil 1710. For another example, bone conduction speaker 1700 may further include one or more annular magnetic elements that may be attached to an upper surface of a sidewall of second magnetically permeable element 1706 or fixed in a magnetic gap.

Fig. 18 is a schematic diagram of a bone conduction speaker 1800, according to some embodiments of the present application. As shown, bone conduction speaker 1800 may include a first magnetic element 1802, a first magnetically permeable element 1804, a second magnetically permeable element 1806, a gasket 1808, a voice coil 1810, a first vibrating plate 1812, a bracket 1814, a second vibrating plate 1816, and a vibrating panel 1818. The lower surface of the first magnetic element 1802 is connected to the inner wall of the second magnetic conductive element 1806. The upper surface of the first magnetic element 1802 is coupled to the upper surface of the first magnetic element 1804. The first magnetic element 1802, the first magnetic element 1804, and the second magnetic element 1806 may form a magnetic gap. A voice coil 1810 may be placed in the magnetic gap. In some embodiments, voice coil 1810 may be of circular or non-circular configuration, such as triangular, rectangular, square, oval, pentagonal, or other irregular shape. The voice coil 1810 is connected to a bracket 1814, the bracket 1814 is connected to a first vibrating plate 1812, and the first vibrating plate 1812 is connected to a second magnetic conductive element 1806 through a gasket 1808. The lower surface of the second vibration plate 1816 is connected to the bracket 1814, and the upper surface of the second vibration plate 1816 is connected to the vibration panel 1818. In some embodiments, the elements of the first magnetic element 1802, the first magnetically permeable element 1804, the second magnetically permeable element 1806, the gasket 1808, the voice coil 1810, the first vibration plate 1812, the bracket 1814, the second vibration plate 11016, and/or the vibration panel 1818 may be connected by any one or more of the connections described herein. For example, the first magnetic element 1802 may be coupled to the first magnetic element 1804 and/or the second magnetic element 1806 by welding. For another example, the first magnetic element 1802, the first magnetic element 1804, and/or the second magnetic element 1806 may be configured as a hole structure, and the first magnetic element 1802, the first magnetic element 1804, and/or the second magnetic element 1806 may be connected by a pin press. In some embodiments, the first and/or second vibration plates 1812 and 1816 may be provided as one or more coaxial torus bodies having a plurality of struts disposed therein that converge toward the center, with the convergence center coinciding with the center of the first and/or second vibration plates 1812 and 1816. The support rods are staggered.

The above description of the structure of bone conduction speaker 1800 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art that various modifications and changes in form and detail of the specific manner and steps of implementing the bone conduction speaker 1800 may be made without departing from this principle, while still being within the scope of the above description, after understanding the basic principles of the magnetic circuit assembly. For example, bone conduction speaker 1800 may include one or more conductive elements disposed on the inner side wall, outer wall, top, and/or bottom of voice coil 1810. For another example, bone conduction speaker 18000 may further include one or more annular magnetic elements that may be attached to an upper surface of a sidewall of second magnetic conductive element 1806 or fixed in a magnetic gap. In some embodiments, the bone conduction speaker may further include a second magnetic element and/or a third magnetically permeable element.

Fig. 19 is a schematic diagram of a bone conduction speaker 1900 according to some embodiments of the present application. As shown, bone conduction speaker 1900 may include a first magnetic element 1902, a first magnetically permeable element 1910, a second magnetic element 1904, a third magnetic element 1906, a second magnetically permeable element 1908, a gasket 1914, a voice coil 1912, a first vibrating plate 1916, a bracket 1918, a second vibrating plate 1920, and a vibrating panel 1922. The lower surface of the first magnetic element 1902 is coupled to the inner wall of the second magnetic element 1908. The upper surface of the first magnetic element 1902 is coupled to the lower surface of the first magnetic element 1910. The outer wall of the second magnetic element 1904 is connected to the inner wall of the second magnetic conductive element 1908. The third magnetic element 1906 is below the second magnetic element 1904, and meanwhile, the outer wall of the third magnetic element 1906 is connected with the inner wall of the second magnetic conductive element 1908; the inner sidewall of the third magnetic element 1906 is connected to the outer wall of the first magnetic element 1902; the lower surface of the third magnetic element 1906 is connected with the inner wall of the second magnetic conductive element 1908; magnetic gaps may be formed between the first magnetic element 1902, the first magnetically permeable element 1910, and the second magnetic element 1904, and the third magnetic element 1906. A voice coil 1912 may be placed in the magnetic gap. In some embodiments, voice coil 1912 may be racetrack shaped as shown in fig. 19, or may be of other geometric shapes, such as triangular, rectangular, square, oval, pentagonal, or other irregular shapes. The voice coil 1912 is connected to a bracket 1918, the bracket 1918 is connected to a first diaphragm 1916, and the first diaphragm 1916 is connected to the second magnetic conductive member 1908 through a gasket 1914. The lower surface of the second vibration plate 1920 is connected to the bracket 1918, and the upper surface of the second vibration plate 1920 is connected to the vibration panel 1922. In some embodiments, the second magnetic element 1904 may be comprised of multiple pieces of magnetic elements, which may be comprised of 4 pieces of magnetic elements 19041, 19042, 19043, 19044 as shown in fig. 19. The shape enclosed by the plurality of magnetic elements may be racetrack-shaped as shown in fig. 19, or may be other geometric shapes, such as triangular, rectangular, square, oval, pentagonal, or other irregular shapes. The third magnetic element 1906 may be comprised of multiple pieces of magnetic elements, which may be comprised of 4 pieces of magnetic elements 19061, 19062, 19063, 19064 as shown in fig. 19. The shape enclosed by the plurality of magnetic elements may be racetrack-shaped as shown in fig. 19, or may be other geometric shapes, such as triangular, rectangular, square, oval, pentagonal, or other irregular shapes. As described in other embodiments herein, the second magnetic element 1904 or the third magnetic element 1906 may be replaced with a plurality of interconnected magnetic elements having different magnetization directions that may increase the magnetic field strength at the magnetic gap in the bone conduction speaker 1900, thereby increasing the sensitivity of the bone conduction speaker 1900.

In some embodiments, the first magnetic element 1902, the first magnetically permeable element 1910, the second magnetic element 1904, the third magnetic element 1906, the second magnetically permeable element 1908, the gasket 1914, the voice coil 1912, the first vibrating plate 1916, the support 1918, the second vibrating plate 1920, and/or the vibrating panel 1922 may be connected by any one or more of the connections described herein. For example, the first magnetic element 1902, the second magnetic element 1904, and the third magnetic element 1906 may be adhesively coupled to the first magnetically permeable element 1910 and/or the second magnetically permeable element 1908. For another example, the washer 1914 may be coupled to the second magnetically permeable element 1908 by a back-off structure, and further, the washer 1914 may be coupled to the second magnetically permeable element 1908 and/or the second magnetic element 1904 by a back-off structure with adhesive. In some embodiments, the first vibration plate 1916 and/or the second vibration plate 1920 may be provided as one or more coaxial rings having a plurality of struts disposed therein that converge toward the center, with the convergence center coinciding with the center of the first vibration plate 1916 and/or the second vibration plate 1920. The support rods are staggered. The plurality of struts are straight bars or bent bars or part of the struts are straight bars, preferably the plurality of struts are bent bars. In some embodiments, the outer surface of the vibration panel 1922 may be planar or curved. For example, the outer surface of the vibration panel 1922 is a convex arcuate surface as shown in fig. 19.

The above description of the structure of bone conduction speaker 1900 is merely a specific example and should not be considered as the only viable embodiment. It will be apparent to those skilled in the art, having the basic principles of magnetic circuit assembly, that various modifications and changes in form and detail may be made to the specific manner and steps of implementing bone conduction speaker 1900 without departing from such principles, but such modifications and changes remain within the scope of the foregoing description. For example, the bone conduction speaker 1900 may include one or more conductive elements disposed on the inner side wall, outer wall, top, and/or bottom of the voice coil 1912. For another example, bone conduction speaker 1900 may further include one or more annular magnetic elements that may connect a lower surface of second magnetic element 1904 and an upper surface of third magnetic element 1906. In some embodiments, the bone conduction speaker may further include a fifth magnetic element and/or a third magnetically permeable element as described in other embodiments herein.

While the basic concepts have been described above, it will be apparent to those skilled in the art that the above disclosure is by way of example only and is not intended to be limiting. Although not explicitly described herein, various modifications, improvements, and adaptations of the present application may occur to one skilled in the art. Such modifications, improvements, and modifications are intended to be suggested within this application, and are therefore within the spirit and scope of the exemplary embodiments of this application.

Meanwhile, the present application uses specific words to describe embodiments of the present application. Reference to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic is associated with at least one embodiment of the present application. Thus, it should be emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various positions in this specification are not necessarily referring to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the present application may be combined as suitable.

Furthermore, those skilled in the art will appreciate that the various aspects of the invention are illustrated and described in terms of several patentable categories or circumstances, including any novel and useful procedures, machines, products, or materials, or any novel and useful modifications thereof. Accordingly, aspects of the present application may be performed entirely by hardware, entirely by software (including firmware, resident software, micro-code, etc.) or by a combination of hardware and software. The above hardware or software may be referred to as a "data block," module, "" engine, "" unit, "" component, "or" system. Furthermore, aspects of the present application may take the form of a computer product, comprising computer-readable program code, embodied in one or more computer-readable media.

Furthermore, the order in which the elements and sequences are processed, the use of numerical letters, or other designations are used herein is not intended to limit the order in which the processes and methods of the present application are performed unless explicitly recited in the claims. While certain presently useful inventive embodiments have been discussed in the foregoing disclosure, by way of various examples, it is to be understood that such details are merely illustrative and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover all modifications and equivalent arrangements included within the spirit and scope of the embodiments of the present application. For example, while the system components described above may be implemented by hardware devices, they may also be implemented solely by software solutions, such as installing the described system on an existing server or mobile device.

Likewise, it should be noted that in order to simplify the presentation disclosed herein and thereby aid in understanding one or more inventive embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof. This method of disclosure, however, is not intended to imply that more features than are presented in the claims are required for the subject application. Indeed, less than all of the features of a single embodiment disclosed above.

In some embodiments, numbers describing the components, number of attributes are used, it being understood that such numbers being used in the description of embodiments, in some examples, are modified with the modifier "about," "approximately," or "substantially," etc. Unless otherwise indicated, "about," "approximately," or "substantially" indicate that the number allows for a 20% variation. Accordingly, in some embodiments, numerical data used in the specification and claims is approximations that may vary depending upon the desired properties sought to be obtained by the individual embodiments. In some embodiments, the numerical data should take into account the specified significant digits and employ a method for preserving the general number of digits. Although the numerical ranges and data used in some embodiments of the present application to determine the breadth of their ranges are approximations, in particular embodiments, the settings of such numerical values are as precise as possible.

Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments of the present application. Other variations are also possible within the scope of this application. Thus, by way of example, and not limitation, alternative configurations of embodiments of the present application may be considered in keeping with the teachings of the present application. Accordingly, embodiments of the present application are not limited to only the embodiments explicitly described and depicted herein.

Claims

1. A magnetic circuit assembly of a bone conduction speaker, the magnetic circuit assembly generating a first full magnetic field, the magnetic circuit assembly comprising:

a first magnetic element;

the lower surface of the first magnetic conduction element is connected with the upper surface of the first magnetic element;

a fifth magnetic element, the lower surface of which is connected with the upper surface of the first magnetic conductive element;

the lower surface of the third magnetic conduction element is connected with the upper surface of the fifth magnetic element;

a sixth magnetic element surrounding the fifth magnetic element and connected to the fifth magnetic element and the third magnetic conductive element;

the voice coil of the bone conduction speaker is located on one side, away from the upper surface, of the lower surface of the sixth magnetic element, the voice coil is located above a plane where the lower surface of the first magnetic element is located, in the interval direction between the upper surface and the lower surface of the first magnetic element, the lower surface of the sixth magnetic element is located between the upper surface and the lower surface of the fifth magnetic element, and an included angle between the magnetization direction of the sixth magnetic element and the magnetization direction of the first magnetic element is between 45 degrees and 135 degrees; an included angle between the magnetization direction of the fifth magnetic element and the magnetization direction of the first magnetic element is between 90 degrees and 180 degrees.

2. The magnetic circuit assembly of claim 1, wherein the magnetization direction of the first magnetic element is vertically upward perpendicular to the lower or upper surface of the first magnetic element, and the magnetization direction of the sixth magnetic element is directed from the outer ring of the sixth magnetic element to the inner ring.

3. The magnetic circuit assembly of claim 1, wherein an angle between the magnetization direction of the fifth magnetic element and the magnetization direction of the first magnetic element is 180 degrees.

4. The magnetic circuit assembly of claim 1, wherein a ratio of a thickness of the first magnetic element to a sum of thicknesses of the first magnetic element, the fifth magnetic element, and the first magnetically permeable element ranges from 0.4 to 0.6.

5. The magnetic circuit assembly of claim 4, wherein the thickness of the fifth magnetic element is less than or equal to the thickness of the first magnetic element.

6. The magnetic circuit assembly of claim 1, further comprising a fourth magnetic element surrounding and coupled to the first magnetic element, the voice coil being positioned between the fourth magnetic element and a sixth magnetic element, the fourth magnetic element having a magnetization direction that is the same as the magnetization direction of the sixth magnetic element.

7. The magnetic circuit assembly of claim 6, further comprising a second magnetically permeable element, a second magnetic element, a third magnetic element, and a seventh magnetic element, the second magnetically permeable element comprising a bottom plate and a side wall, a lower surface of the first magnetic element being coupled to the bottom plate, the third magnetic element being coupled to an upper surface of the side wall, a lower surface of the second magnetic element being coupled to the third magnetic element, an upper surface of the second magnetic element being coupled to the seventh magnetic element, an upper surface of the seventh magnetic element being coupled to the third magnetically permeable element, the sixth magnetic element being coupled to the seventh magnetic element, the fourth magnetic element being coupled to the second magnetically permeable element, the third magnetic element and the seventh magnetic element being magnetized in opposite directions.

8. The magnetic circuit assembly of claim 7, wherein the lower surface of the second magnetic element is interposed between the upper and lower surfaces of the first magnetic element in a direction of separation of the upper and lower surfaces of the first magnetic element, the lower surface of the second magnetic element is interposed between the upper and lower surfaces of the fifth magnetic element, and an angle between the magnetization direction of the sixth magnetic element and the magnetization direction of the first magnetic element is between 45 degrees and 135 degrees.

9. A bone conduction speaker, the bone conduction speaker comprising:

a vibration assembly including a voice coil and at least one vibration plate; and

a magnetic circuit assembly as claimed in any one of claims 1 to 8.