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217results about How to "Improve low frequency performance" patented technology

Graphene aerogel and preparation method and application thereof

The invention discloses a graphene aerogel and a preparation method and an application thereof, wherein the aerogel is prepared from the following method: (1) pre-reduction treatment: adding a reducing agent to a graphene oxide solution, mixing, carrying out ultrasonic dispersion, and carrying out pre-reduction treatment, to obtain a semi-reduction graphene hydrogel; (2) final reduction treatment:adding a reducing agent, carrying out ultrasonic treatment, and then carrying out final reduction treatment, to obtain a graphene hydrogel; and (3) acid / alkali soaking: placing the graphene hydrogelin an acid or alkali aqueous solution, soaking, washing the hydrogel to be neutral, sucking out the excess liquid, and carrying out freeze drying, to obtain the graphene aerogel. The graphene aerogelis applied to electromagnetic wave absorption materials. The graphene aerogel obtained by the method has small density and good integrality, and has a certain mechanical strength and resillency; the prepared wave absorbing material has good electromagnetic wave absorption performance, and the wave absorbing performance can be adjusted; and the method has the advantages of simple process, short production cycle, low cost and good benefits, and is suitable for industrialized production.
Owner:苏州涤致良特种防护装备科技有限公司

Thin broadband sound-absorbing structure of composite multi-layer mechanical impedance plates

The invention provides a thin broadband sound-absorbing structure. The structure comprises a sound-absorbing material, a support and at least two layers of mechanical impedance plates, wherein the sound-absorbing material is installed on the inner side of one end of the support, a supporting plate is arranged on the inner wall of the other end of the support, each of the mechanical impedance plates consists of a back plate and sticky elastic rings at two ends of the back plate, adjacent back plates are not in contact, sticky elastic rings are stuck to the supporting plate through an adhesive, the sticky elastic rings, the support inner wall and the back plates are attached tightly, a hollow is formed among the sound-absorbing material and the mechanical impedance plates, and the back plate on the outermost side is recessed towards the support end face by certain distance. Mechanical impedance is coupled to a traditional sound-absorbing material and a cavity resonance absorption mechanism, a novel thin broadband sound-absorbing mechanism is formed, the structure thickness is not increased basically based on the acoustic performance, the middle/high-frequency sound absorption performance is good, the low-frequency sound absorption effect is improved greatly and the sound-absorbing structure of which the thickness is thin and the sound-absorbing frequency band is wide is produced.
Owner:JIANGSU UNIV

Piezoelectric speaker based on piezoelectric cantilever beam

The invention discloses a piezoelectric speaker based on a piezoelectric cantilever beam, belonging to the technical filed of piezoelectricity. The piezoelectric speaker is structured by bonding an upper layer piezoelectric ceramic piece and a lower layer piezoelectric ceramic piece of opposite polarization directions at both sides of a middle layer fiber sheet, thereby forming a piezoelectric cantilever beam; one end of the piezoelectric cantilever beam is fixed with an external frame so as to form a fixed end from which electrodes are led out; the movable end of the piezoelectric cantilever beam is connected with a vibration sheet by a link block with a damp function; and the vibration sheet is bonded to the external frame through a vibration film. The vibration sheet can serve as the main medium for driving air around the speaker and also the counter weight of the speaker, can reduce the first-order resonance frequency of the speaker effectively, and improve the effect of low pitch replay. The piezoelectric speaker provided by the invention has the characteristics of low resonance frequency, simple vibration mode and large vibration range and the like, and has the advantages of good low pitch performance, stable sound pressure output and high sound output and the like compared with a conventional surface mount type piezoelectric speaker.
Owner:TSINGHUA UNIV +1

Loudspeaker box

The invention provides a loudspeaker box comprising a main cone frame, a first upper cover covered on a top end of the main cone frame and enclosed to form an accommodation space together with the main cone frame, and a sound production monomer accommodated in the accommodation space, wherein the sound production monomer and the first upper cover are enclosed to form a front cavity together, the sound production monomer and the main cone frame are enclosed to form a back cavity together, the loudspeaker box further comprises an extension part extending from the main cone frame toward a direction away from the accommodation space, a trunk bulkhead extending from the top end toward the bottom end of the main cone frame and a ventilating isolation part; a first sound absorption cavity filled with a sound production material is arranged in the extension part; the trunk bulkhead is located in the back cavity and is enclosed to form a second sound absorption cavity for accommodating the sound production material together with the main cone frame; the first sound absorption cavity communicates with the second sound absorption cavity, and the second sound absorption cavity communicates with the back cavity; and the ventilating isolation part is covered on one end of the second sound absorption cavity away from the first upper cover so as to prevent the sound production material from entering the back cavity. Compared with the prior art, the loudspeaker provided by the invention has the advantages of simple structure, and good low audio performance, and especially low frequency performance.
Owner:AAC TECH PTE LTD

Loudspeaker cabinet

The invention provides a loudspeaker cabinet. The loudspeaker cabinet includes a bottom cover, a top cover, a side plate, a sounding monomer, a cyclic convex wall and a ventilating separator, whereinthe side plate connects the bottom cover and the top cover, so as to form accommodation space through enclosure, together with the bottom cover and the top cover; a front cavity is formed through enclosure of the sounding monomer, the top cover and the side plate together; a back cavity is formed through enclosure of the sounding monomer, the bottom cover and the slide plate together; the convex wall is extended to the direction, far away from the outer wall of the side plate, from the inner wall of the side plate in a convex manner; the ventilating separator is fixedly supported at one side,close to the top cover, of the convex wall, and separates the back cavity into a first back cavity and a second back cavity, together with the convex wall, and the first back cavity and the second back cavity are mutually communicated in air; the sounding monomer is arranged in the first back cavity; acoustic-absorbing particles are filled in the second back cavity; and the ventilating separator packages the acoustic-absorbing particles in the second back cavity. Compared with the related technologies, the loudspeaker cabinet has better low frequency acoustic performance.
Owner:AAC TECH PTE LTD

Miniature loudspeaker module structure with adaptive pressure balancing function

The invention belongs to the technical field of loudspeakers, and particularly relates to a miniature loudspeaker module structure with an adaptive pressure balancing function. The module structure comprises a body of a module. A loudspeaker or sounding component, a front sound cavity and a rear sound cavity are arranged in the body, sounding holes are arranged on a front cavity wall, which corresponds to a vibrating diaphragm of the loudspeaker or sounding component, of the front sound cavity, and a foam or dustproof screen is arranged between the front cavity wall and the loudspeaker or sounding component. An opening is arranged on a wall of the rear sound cavity, a hollow pipeline used as a leakage pipeline of the loudspeaker module is led out at the opening, the aperture of the hollow pipeline is identical to that of the opening, and the hollow pipeline is used as an air pressure balancing channel; the hollow pipeline and the opening are sealed with each other without a gap; and a coefficient of the proportion of the sectional area of the hollow pipeline to the length of the hollow pipeline is not larger than 0.01. The miniature loudspeaker module structure has the advantages that problems that internal air pressure and the external air pressure are unbalanced due to deficiency of leakage holes of an existing loudspeaker module and an individual loudspeaker is damaged are solved owing to the design of the leakage pipeline of the loudspeaker module, low-frequency effects of the small closed sound cavities of the loudspeaker module are further improved, and the sound quality of the loudspeaker module is optimized.
Owner:JIAXING KEYSOUND ELECTRONICS CO LTD +1

Loudspeaker box

The invention discloses a loudspeaker box comprising a lower cover, an upper cover and a sound generating monomer. The sound generating monomer and the upper cover form a front cavity through enclosing. The sound generating monomer, the lower cover and the upper cover form a rear cavity together through enclosing. The loudspeaker box also comprises a ventilating isolation component and clamp walls. The ventilating isolation component is fixedly clamped between the clamp walls, and the ventilating isolation component and the clamp walls divide the rear cavity into a first rear cavity and a second rear cavity which are mutually communicated together. The sound generating monomer is arranged in the first rear cavity. The second rear cavity is filled with sound absorbing particles. The ventilating isolation component packages the sound absorbing particles in the second rear cavity. The ventilating isolation component comprises a framework, screen cloth which is combined on the framework and elastomers which are arranged at the periphery of the framework. The elastomers are inserted in the clamp walls. The upper cover, the lower cover and the clamp walls extrude the elastomers to form sealing. Compared with the loudspeaker boxes in the prior art, the loudspeaker box has better low frequency acoustic performance and great sealing performance.
Owner:AAC TECH PTE LTD

Explosion-proof broadband wave absorption composite material and preparation method thereof

The invention provides an explosion-proof broadband wave absorption composite material and a preparation method thereof, and belongs to the technical field of multifunctional materials. The preparation method of the explosion-proof broadband wave absorption composite material comprises the following steps: preparing explosion-proof skin by utilizing quartz fiber and unsaturated resin, preparing anelectrical loss wave absorption piece, preparing a magnetic loss wave absorption piece, preparing a broadband interlayer wave absorption material, and sequentially adhering the broadband interlayer wave absorption material and the explosion-proof skin to a reflecting base plate. The explosion-proof broadband wave absorption composite material prepared by the invention is of a laminated structure,and comprises the reflecting base plate, the broadband interlayer wave absorption material and the explosion-proof skin which are in contact in sequence. According to the preparation method providedby the invention, the technical obstacle that a wave absorption material and an explosion-proof material are difficult in combination is overcome, and the preparation method is simple and is easy in industrial implementation; the prepared explosion-proof broadband wave absorption composite material simultaneously has an explosion-proof function and a broadband wave absorption function and has thecharacteristics of good low-frequency performance, broad absorption band, low surface density and excellent environment performance, the explosion-proof function of a product is solved, and the broadband wave absorption function is also integrated.
Owner:AEROSPACE SCI & IND WUHAN MAGNETISM ELECTRON

Antenna used for terminal and terminal provided with antenna

The invention discloses an antenna used for a terminal and the terminal provided with the antenna. The antenna comprises a main metal frame, a first corner metal frame and a second corner metal frame, wherein the main metal frame is a main radiation body of the antenna; one end of the main metal frame is connected to a mainboard of the terminal by a feeder end; the first corner metal frame is arranged on one side, close to the feeder end, of the main metal frame; a first gap is defined between one end of the first corner metal frame and the main metal frame; the other end of the first corner metal frame is connected to the mainboard; the second corner metal frame is arranged on one side, far away from the feeder end, of the main metal frame; a second gap is defined between one end of the second corner metal frame and the main metal frame; and a third gap is defined between the other end of the second corner metal frame and the mainboard. According to the antenna used for the terminal, the third gap is arranged on the second corner metal frame to disconnect the second corner metal frame and the mainboard, so that an adverse effect of the second corner metal frame on the main metal frame can be effectively improved; the efficiency of the main metal frame is increased; and the low-frequency performance of the main metal frame is enhanced.
Owner:GUANGDONG OPPO MOBILE TELECOMM CORP LTD

Data collecting and alarming device of wireless anti-collision pier monitoring and alarming system

ActiveCN105809882AMeet the requirements of vibration monitoringNo distractionTransmission systemsAlarmsCommunication interfaceProgrammable logic device
The invention discloses a data collecting and alarming device of a wireless anti-collision pier monitoring and alarming system.The device comprises an analog signal filtering and signal processing module, a data latch module, a programmable logic module, a main control module, a level conversion module and a data communication interface module; the analog signal filtering and signal processing module comprises three channels, and the input ends of the channels are connected with a south-north sensor, an east-west sensor and a vertical sensor respectively.According to the data collecting and alarming device, the design method that the three channels conduct data collecting and signal processing synchronously is adopted for the characteristics of low-frequency signal collecting and bridge anti-collision pier structure testing, the three channels are independently designed, the main control module ensures complete synchronization of the three channels through a synchronous starting analog-digital conversion signal generated through massive programmable logic device decoding, the problems that in traditional data collecting, more channels are needed, and a large error is generated in synchronous collecting are solved, therefore, completely synchronous collection of the three channels is achieved, and the vibration monitoring requirement of an anti-collision pier is met.
Owner:DALIAN UNIV
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