735 results about "Electret" patented technology

The present invention relates to a preamplifier suitable for use with Electret Condenser Microphones such as used within telecommunication equipment. More particularly the invention relates to a preamplifier specially suited for the demands to such a preamplifier within telecommunication equipment: low input capacitance, gain and a combined terminal for output and supply voltage, thus making the preamplifier suitable for two terminal microphone assemblies. These features are obtained with a two stage amplifier with a first stage optimised for low input capacitance and the second stage being able to provide gain. The preamplifier may be implemented using an ASIC, thus making the preamplifier suitable for applications with very limited space available, such as for integration within microphone assemblies.

A preamplifier having extremely high input impedance amplifies the electrical signal output from an electret condenser microphone (ECM) without suffering from the effects of a DC leakage current at the input. The preamplifier circuit includes a pair of cross-coupled PN junction diodes setting the input impedance, a PMOS device, and a load resistor configured similarly to a conventional preamplifier. A capacitor is placed between the input and the cross-coupled diodes such that a DC path no longer exists to bias the cross-coupled diodes. Therefore, leakage currents are prevented from upsetting the DC operating point of the preamplifier and biasing the cross-coupled diodes. Consequently, small signal gain distortion, excessive demodulation products and increased noise can be avoided.

A microphone includes a separate end cover with a sound port. A diaphragm is directly attached to the end cover. The backplate is positioned within the housing against a ridge near an end of the housing. A spacer is positioned against the backplate. The diaphragm engages the spacer when the end cover, with its attached diaphragm, is installed in the housing. The backplate of the microphone has an integral connecting wire that is made of the same material as the backplate. The integral connecting wire may have an inherent spring force to provide a pressure contact with the accompanying electrical components. The integral connecting wire electrically couples the backplate to the electronic components within the housing and transmits the raw audio signal corresponding to movement of the diaphragm. The housing may have first and second ridges on which the printed circuit board and the electret assembly are mounted, respectively.

An electret accelerometer is provided in which a diaphragm, an electret, a back plate and an electronic circuit are placed in a closed casing.

The invention relates to a method for preparing a melt-blown polypropylene electret filter material. The method comprises the following steps of: 1) modification of polypropylene: melting the raw material, polypropylene, and mixing the melt with an additive to obtain modified polypropylene; 2) melt-blown preparation process: a) in a molten state, feeding the modified polypropylene melt into a spinneret plate by using a metering pump; b) extruding the modified polypropylene melt from a spinneret orifice; and c) blowing the melt extruded out from the spinneret orifice into ultrafine fibers by using high-speed hot air to make the fibers fly to a condenser net curtain to form a fiber net through cooling and bonding; and 3), preparation process of an electret: passing the fiber net obtained in step (2) through an electrode of a corona discharge device and obtaining the electret through the discharging of the electrode. The melt-blown electret high-efficiency filter material obtained by the method has the advantages of very high electret charge stability, excellent filtering efficiency, very low pressure loss, long service life and optimal economic benefit.

Embodiments of the invention provide microphone assemblies which are resistant to moisture. One embodiment provides a microphone assembly comprising a housing, a diaphragm disposed in the housing and a backplate disposed in the housing. The housing includes a sound inlet port for the entry of sound waves. The backplate includes a surface and an electret portion having an embedded permanent charge. The diaphragm is configured to vibrate in response to sound waves entering the housing. The vibrations of the diaphragm interact with the electret portion to produce an electrical signal associated with the sound waves entering the housing. A hydrophobic coating can be applied to one or both of the backplate and diaphragm surfaces so as to reduce condensation and/or wetting of the backplate. This minimizes neutralization of an electric field of the backplate surface from condensation preserving the field and the function of the microphone in humid environments.

A system and method for generating power. The system has a first electrode member comprising a first region and a second electrode member comprising a second region. Preferably, the second electrode member is coupled to the first electrode member. An electret is coupled between the first electrode member and the second electrode member. The system has a spatial region provided between the first region of the first electrode member and the second region of the second electrode member. A volume of fluid (e.g., liquid, liquid and solids, gas and liquid, solids and gases) is provided between the first region and the second region and is adapted to move between the first region and the second region to cause a change in an electric field characteristic within a portion of the spatial region by the movement of at least a portion of the fluid within the portion of the spatial region to generate a change in voltage potential between the first electrode and the second electrode.

This invention mainly provides a SMT-type structure of the minimized and low-power silicon-based electret condenser microphone. Primarily integrates with the electret, silicon-based, MEMS and microphone techniques to implement the minimized and low-power silicon-based electret condenser microphone. The Silicon-based bi-diaphragm of the composite diaphragm-chip was coated with the low-dielectric macromolecule material to allow the microphone acquires the sufficient electrical charges. Moreover, the impedance matching element of the microphone that MOSFET was implemented by the MEMS technology. Conclusively, this silicon-based electret condenser microphone gains several achievements as the smallest volume, a lower bias voltage, a SMT-type structure, a lower residue stress and a lower assembly cost.

In order to automate a microphone assembly process including a dust-proof treatment, an object of the present invention is to provide a dust-proof microphone having a configuration suitable for automated assembly.

According to the present invention, a microphone has a plate-like or film-like dust-proof section that is disposed in a conductive housing (capsule) having a sound aperture and covers the sound aperture. The dust-proof section has a plurality of pores at least in a region corresponding to the sound aperture, and the dust-proof section further has a nonporous region. In the case of an electret condenser microphone, from the viewpoint of performance of the microphone, the dust-proof section is conductive. In addition, taking into account a soldering in a reflow furnace, the dust-proof section is heat-resistant. Each pore is desirably designed taking into account the environment for the usage of the microphone. However, if it is supposed that the microphone is used near one's mouth, each pore has an area of 0.01 mm² or less. In addition, to enhance the dust-proof effect, the pores may be subjected to a water-repellent treatment.

The invention provides a composite anti-microbial air filtration material. An electrets fabric layer, an electrostatic spinning fiber membrane layer, chitosan and nano TiO2 photocatalyst are combined, thus PM2.5 is effectively removed, and meanwhile, the filtration material has anti-microbial, disinfection and odor removal functions; further, the filtration material is applied to the filtering material fields of window cloths and screen window to replace natural air instead of diffusion air; meanwhile, the filtration material is applied to fields of air-conditioners, air purifiers and masks, thus comprehensive purification of indoor air and breathing air of people is realized. In addition, the invention further provides a preparation method and application of the composite anti-microbial air filtration material.

A wafer having heterostructure therein is formed using a substrate with recesses formed within a dielectric layer. A magnetized magnetic layer or a polarized electret material is formed at the bottom of each recess. The magnetized magnetic layer or a polarized electret material provides a predetermined magnetic or electrical field pattern. A plurality of heterostructures is formed from on an epitaxial wafer wherein each heterostructure has formed thereon a non-magnetized magnetic layer that is attracted to the magnetized magnetic layer formed at the bottom of each recess or dielectric layer that is attracted to the polarized electret material formed at the bottom of each recess. The plurality of heterostructures is etched from the epitaxial wafer to form a plurality of heterostructure pills. The plurality of heterostructure pills is slurried over the surface of the dielectric layer so that individual heterostructure pills can fall into a recess and be retained therein due to the strong short-range magnetic or electrical attractive force between the magnetized magnetic layer in the recess and the non-magnetized magnetic layer on the heterostructure pill or between the polarized electret material in the recess and the dielectric on the heterostructure pill. Any excess heterostructure pills that are not retained in a recess formed within the dielectric layer are removed and an overcoat is applied to form a substantial planar surface.

An electret condenser microphone includes: a substrate 13 in which an opening 25 is formed; an electret condenser 50 connected to one face of the substrate 13 so as to close the opening 25 and having an acoustic hole 12 and a cavity 2; a drive circuit element 15 connected to the one face of the substrate 13; and a case 17 mounted over the substrate 13 so as to cover the electret condenser 50 and the drive circuit element 15. Electric contact is established at a joint part between the electret condenser 50 and the substrate 13. The acoustic hole 12 communicates with an external space through the opening 25. The cavity 2 and an internal region of the case 17 serve as a back air chamber for the electret condenser 50.

A biodegradable, cellulose-based collecting sheet that can be used in either a wet state or a dry state. The collecting sheet may be a double recreped cellulose substrate reinforced with a binder, such as a latex binder. Alternatively, or in addition to the binder, the collecting sheet may be coated with a dielectric material and electret treated to establish a charge on the dielectric material. Additionally, the collecting sheet may be embossed to provide more interstices and greater surface area to enhance the pick-up ability of the collecting sheet. The invention further includes a method of forming such a collecting sheet.

The invention relates to an electret polypropylene melt-spray nonwoven cloth and its making method, the components in weight percent: polypropylene 95-97%, and tourmaline 3-5% with average particle size not greater than 0.5mum; its making method: (1) uniformly mixing and fusing the tourmaline particles and the polypropylene slices to make particles; the assistants of making the tourmaline particles in weight percent: coupling agent 3-10%; dispersant 2-5% and chemical inhibitor 0.01-0.1%; (2) uniformly mixing, fusing and extruding the particles with the polypropylene slices, stretching under the high-speed hot air flow to make the product. The product has better adaptability to high temperature and high humidity environment, can be used in filtering liquid; the making method has the characters of simple technique, no special devices, easy industrialized implementation, etc.

A flexible electret transducer assembly including an electrical backplate and a membrane made of an electret material is disclosed. A plurality of spacers is formed on a surface of the electrical backplate in a longitudinal or latitudinal direction, and the spacers are used for supporting a vibrating room of the membrane. A working area of the membrane is formed between adjacent spacers, and in each of the working area, the space between the electrical backplate and the membrane is smaller than that in a conventional electrostatic speaker. The spacers between the electrical backplate and the membrane are mass produced through a stamping process. Thereby, an accurate space between the electrical backplate and the membrane can be maintained and accordingly the audio quality can be improved. In addition, a speaker including the flexible electret transducer assembly and a method for fabricating the flexible electret transducer assembly are also disclosed.

A ultrasonic transducer of the invention comprises: a transducer cell including a first electrode and a second electrode disposed separated from the first electrode by an air gap portion; and an electret for applying a potential difference between the first electrode and the second electrode. The electret is disposed in a region where at least a part thereof does not overlap with the transducer cell when viewed from a transmitting direction of ultrasonic waves.

The present invention discloses a friction nanometer generator, a generating set and a power generation method. The generator comprises a first frictional layer, an electrode layer attached to the lower surface of the first frictional layer and a second frictional layer, at least parts of the surfaces of the first and second frictional layers can be contacted and separated under the effects of external forces, at the same time, the electrode layer and a first equipotential source output the electric signals. The friction nanometer generator of the present invention only has one electrode layer, and has the characteristics of low cost, high efficiency, simple structure, etc. In an optimized scheme, an electret is used as a frictional layer, thereby improving the output efficiency of the electric signals substantially, and realizing the situation for the first time that the single small-size contact and separation type friction nanometer generator lightens the LED lamps.

An electret condenser 2 includes a fixed electrode 6, a vibrating electrode 5, an electretized silicon oxide film 7 formed between the electrodes, and silicon nitride films 8 and 9 formed so as to cover the silicon oxide film 7. The silicon oxide film 7 covered with the silicon nitride films 8 and 9 is formed on the vibrating electrode 5.

An automatic stop valve formed in a container of a medical fluid administration system includes an electrical field that attracts the float and valve seat together to shut off flow from the exit port of the container when the fluid within the container is reduced to a predetermined level. One or both of the float and valve seat creates an electric field that attracts the other, which is made of a non-magnetic dielectric, into engagement. In one embodiment, the valve seat is formed of an electret that creates the electric field attracting the float to it to stop flow. In another embodiment, the float comprises an electret that attracts the float to the dielectric valve seat. In yet another embodiment, both the float and valve seat include electrets of opposite polarity that attract each other into engagement. The lack of magnetic and metallic materials makes the shut off valve suitable for use in an MRI environment.

The invention belongs to the technical field of high-polymer materials, and particularly relates to a polypropylene (PP) electret master batch material, a method for preparing the same and applicationof the polypropylene electret master batch material. The PP electret master batch material is mainly prepared from components including, by weight, 50-100 parts of polypropylene, 8-50 parts of electret agents, 0-3 parts of compatibilizers, 0.05-0.35 part of antioxidants and 0-3 parts of anti-aging agents. The components are molten and granulated to obtain the polypropylene electret master batch material. The polypropylene electret master batch material, the method and the application have the advantages that resin and auxiliaries are uniformly mixed with one another in melt blending modes, accordingly, obvious electret effects can be realized by melt-blow non-woven materials produced from the polypropylene electret master batch material prepared by the aid of the method, the melt-blow non-woven materials are high in filter efficiency and low in filter resistance, and the like.

The invention discloses a dielectric filtration material charged regeneration device and method. The method comprises putting an electret or other dielectric filter material finished products as barrier mediums in a voltage alternative electric field so that dielectric barrier discharge is formed, or putting the electret or other dielectric filter material finished products in a corona field under high direct voltage so that corona-dielectric barrier discharge is formed. Through discharge, electrostatic electret charging and/or electrostatic charging is realized so that filter or finished product performances are improved, and the cleaned filter material or product is re-charged and is subjected to disinfection. The dielectric filtration material charged regeneration device comprises a filter material, a positive electrode plate, a negative electrode plate, an AC or DC high voltage generator and a power supply. Through the device and method, filter material or finished product performances are improved, the cleaned filter material or product is re-charged and the disposable product can be recycled. The method has simple processes, is convenient for operation, reduces material and resource wasting and realizes filter material recycle.