Patent ID: 12245011

DETAILED DESCRIPTION

Description will be made on technical solutions in the embodiments of the application below in combination with drawings in the embodiments of the application. It is apparent that the described embodiments are merely a part rather than all of the embodiments of the application. All the other embodiments obtained based on any embodiment of the application by those skilled in the art without creative efforts shall fall into the scope of protection of the application.

Referring toFIG.1, according to an embodiment of the present invention, provided is an active noise reduction acoustic unit. The active noise reduction acoustic unit includes a casing and a baseplate11. The baseplate11is arranged in the casing, and the baseplate11separates the casing into a first accommodating cavity14and a second accommodating cavity16. The first accommodating cavity14and the second accommodating cavity16are in communication with each other, the second accommodating cavity16is provided therein with a feedback microphone, and the feedback microphone is configured to pick up noise signals. The first accommodating cavity14is provided therein with a moving iron speaker which can vibrate and produce sound according to the noise signals.

The active noise reduction acoustic unit provided by the embodiment of the present disclosure can perform active noise reduction. A principle of actively reducing the noise by utilizing the active noise reduction acoustic unit is as follows: the feedback microphone picks up a surrounding noise signal, a signal with same amplitude and opposite phase is output to the moving iron speaker after the noise signal is backward processed by a noise reduction circuit, and a phase-inverted noise signal output by the moving iron speaker counteracts and neutralizes a noise signal directly entering ears of a user, so as to achieve noise reduction. A moving iron speaker can be either used for sound hearing or used for generating an inverted noise in active noise reduction. In an acoustic unit with the active noise reduction function in the prior art, the feedback microphone and the speaker are two completely independent units, such an arrangement occupies a large space and is inconvenient to install. According to the active noise reduction acoustic unit provided by the embodiment of the present disclosure, the baseplate11thereof is a shared component which separates the casing into a first accommodating cavity14and a second accommodating cavity16, wherein the first accommodating cavity14is used for carrying the moving iron speaker and the second accommodating cavity16is used for carrying the feedback microphone. That is, the moving iron speaker and the feedback microphone are assembled and integrated into one acoustic unit, thereby effectively reducing the size. Further, functions of the moving iron speaker and the feedback microphone can be tested uniformly when the unit is tested after the active noise reduction acoustic unit is assembled thereto, thereby effectively saving the testing time, improving the testing consistence and facilitating subsequent ANC debugging.

In an embodiment, the casing includes a first casing12and a second casing13, the first casing12and the baseplate11enclose the first accommodating cavity14, and the second casing13and the baseplate11enclose the second accommodating cavity16. The baseplate11and the first casing12are integrally formed, and the baseplate11and the second casing13are welded or bonded together. That is, the baseplate11and the first casing12are of one integrated structure, and the second casing13and the baseplate11are fixed together by way of welding or bonding. In this way, the sealing between the moving iron speaker and the feedback microphone is very effective.

In an embodiment, the moving iron speaker includes a voice coil151, magnets152, an iron sheet153, a vibrating diaphragm154and a connecting bar155. There are two oppositely arranged magnets152with a gap therebetween; the iron sheet153penetrates through the voice coil151and is inserted into the gap between the two magnets152; and the connecting bar155has one end thereof fixed to the iron sheet153and the other end thereof fixed to the vibrating diaphragm154. A working principle of the moving iron speaker is as follows: the voice coil151is electrified to generate a magnetic field and magnetize the iron sheet153; the magnetic field of the iron sheet153varies as a function of the electrical signal, the iron sheet153vibrates due to an interaction between the magnetic field of the iron sheet153and the magnetic fields of the magnets152; and the vibration is propagated to the vibrating diaphragm154via the connecting bar155, such that the vibrating diaphragm154vibrates to produce sound. In an embodiment, a side portion of the first casing12is provided with a sound outlet156in a position close to the vibrating diaphragm154. The sound generated by vibration of the vibrating diaphragm154is propagated out via the sound outlet156.

In an embodiment, the feedback microphone includes a capacitance acoustoelectric conversion component171and a signal processing component172, and the capacitance acoustoelectric conversion component171and the signal processing component172are in electrical connection, and both are arranged on the baseplate11. For example, the capacitance acoustoelectric conversion component171and the signal processing component172can be fixed to the baseplate11by way of bonding or pasting. Of course, the capacitance acoustoelectric conversion component171and the signal processing component172can also be electrically connected with the baseplate11in a way known to those skilled in the art, which is not described in detail herein.

In an embodiment, the baseplate11is provided with a sound hole173in a position corresponding to the capacitance acoustoelectric conversion component171, and the sound hole173is in communication with the first accommodating cavity14. An external noise air flow enters the capacitance acoustoelectric conversion component171via the sound hole173to generate a sound signal, and the sound signal converted into an electrical signal by the capacitance acoustoelectric conversion component171is transmitted to the signal processing component172to be processed. After the signal processed by the signal processing component172is backward processed by the noise reduction circuit, a signal with same amplitude and opposite phase is output to the moving iron speaker.

In an embodiment, the capacitance acoustoelectric conversion component171is an MEMS and the signal processing component172is an ASIC chip. In an embodiment, using the micro-electrical mechanical technologies, the MEMS is formed with a vibrating diaphragm and a back electrode plate, and the sound hole173is in communication with a back cavity in the MEMS. In particular, the external noise air flow enters the back cavity of the MEMS via the sound hole173, and then triggers the vibrating diaphragm arranged on the MEMS to vibrate, such that a capacitance value between the vibrating diaphragm and the back electrode plate changes. In the case that the voltage remains unchanged, a changing current is generated, and thus conversion from the sound signal to the electrical signal is accomplished, while the electrical signal is transmitted to the ASIC chip to be processed.

In an embodiment, the baseplate11is a PCB. For example, the baseplate11can be a PCB of a laminated structure, and the PCB of the laminated structure is provided with a first PCB copper clad layer, a PCB baseplate layer and a second PCB copper clad layer sequentially from inside to outside of the second accommodating cavity16. Of course, the baseplate11can also be a PCB of other structures according to practical needs.

In an embodiment, the second casing13is of a metal material. Specifically, for example, the second casing13can have a copper casing as the middle layer, while an inner and an outer surface layer of the copper casing are subjected to gold plating treatment. The second casing13thus made has an excellent electromagnetic shielding performance, preventing the capacitance acoustoelectric conversion component171and the signal processing component172therein from external electromagnetic interferences.

In an embodiment, a solder mask can be arranged between the capacitance acoustoelectric conversion component171and the baseplate11and between the signal processing component172and the baseplate11. Specifically, the solder mask is a printing ink layer. Of course, the solder mask can also be an insulating resin material. When the second casing13is fixed together with the baseplate11by way of welding, providing the solder mask can prevent electrical conduction of the capacitance acoustoelectric conversion component171and the signal processing component172with soldering tin from occurring.

According to another embodiment of the present disclosure, provided is a sound-producing unit which can be a Bluetooth earphone. Referring toFIG.2andFIG.3, the sound-producing unit includes an outer casing2and the active noise reduction acoustic unit1arranged in the outer casing2, wherein the outer casing2is provided therein with a sound cavity21and a sound outlet tube22in communication with each other, and an end of the sound outlet tube22far away from the sound cavity21is provided with a sound outlet opening221. Referring toFIG.2, the active noise reduction acoustic unit1is located in the sound outlet tube22and the sound outlet156of the active noise reduction acoustic unit1is provided facing the sound outlet opening; alternatively, referring toFIG.3, the active noise reduction acoustic unit1is located in the sound cavity21, the sound outlet156of the active noise reduction acoustic unit1is provided facing the sound outlet opening, and a side surface of the active noise reduction acoustic unit1provided with the sound outlet156is located in a position where the sound cavity21and the sound outlet tube22meet.

In the prior art, the feedback microphone and the speaker are two independent components. There are three major forms for arranging the feedback microphone in the sound-producing unit: The first is to arrange the feedback microphone in the front sound cavity of the sound-producing unit, in that case, the speaker needs to be moved backward properly. The second is to arrange the feedback microphone in the sound outlet tube, and the sound outlet area of the speaker will be traded off; as such, high-frequency frequency response of the speaker degrades. The third is to arrange the feedback microphone in the back sound cavity, and the feedback microphone is in communication with the front sound cavity via a sound inlet tube; in that case, a bracket is needed to fix the speaker and the feedback microphone, thereby putting a high demand on sealing tightness of the feedback microphone.

In the sound-producing unit provided in the embodiment of the present disclosure, as the moving iron speaker and the feedback microphone are assembled and integrated to one integral active noise reduction acoustic unit, the space in the sound-producing unit can be saved when the active noise reduction acoustic unit is assembled to the sound-producing unit, which is more suitable for a small earphone that is compact in space. Furthermore, it facilitates sealing no matter whether the active noise reduction acoustic unit is arranged in the sound outlet tube22or the sound cavity21, and the sound outlet area of the moving iron speaker will not be traded off completely, such that the high-frequency frequency response of the moving iron speaker will not be influenced.

The embodiments in the description are described in a parallel or sequential way. Each embodiment focuses on what distinguishes it from other embodiments. The same or similar parts of the embodiments can be of reference to each other. The device disclosed by the embodiments is described in a simple way because it corresponds to the method disclosed by the embodiments, where the related part can be referred to description of the method.

Those skilled in the art further can understand that units and arithmetic steps in the examples described in the embodiments disclosed herein can be implemented by way of electronic hardware, computer software or a combination thereof. In order to clearly describe the interchangeability of hardware and software, components and steps of the examples have been generally described in the above description according to functions. Execution of these functions by way of hardware or software is decided in dependence on a specific application and a design constraint condition of the technical solution. Those skilled in the art can implement the described functions for each specific application by using different methods, but such implementations shall not be considered as going beyond the scope of the application.

Steps of the method or algorithm described in combination with embodiments disclosed herein can be implemented by way of a software module executed by hardware and process directly or combination thereof. The software module can be disposed in a random access memory (RAM), an internal memory, a read-only memory (ROM), an electrical programmable ROM, an electrical erasable programmable ROM, a register, a hard disc, a movable disc, a CD-ROM or any other forms of storage media known in the technical field.

It should be further noted that relationship terms herein such as “first” and “second” are merely used for differentiating one body or operation from another body or operation rather than requiring or hinting any actual relationship or sequence among the bodies or operations. Further, the terms “include”, “comprise” or any other variants thereof are intended to cover non-exclusive inclusions, such that a process, method, article or apparatus including a series of elements including not only include these elements but also other elements which are not literally included or further include inherent constituents of the process, method, article or apparatus. Unless limited otherwise, elements defined by the term “including a/an . . . ” does not exclude the existence of the same elements in the process, method, article or apparatus already including the elements.