Planar Diaphragm Research Articles

平面振膜换能器仿真方法研究

平面振膜换能器仿真方法研究

An Optical Fiber Fabry-Perot Microphone Based on Corrugated Silver Diaphragm

A corrugated silver diaphragm-based optical fiber microphone (OFM), formed by extrinsic Fabry–Perot interferometric structure, was proposed. The sensor’s sensitivity was improved by releasing diaphragm’s initial stress with the help of corrugations. A simple “gray-scale exposure” method was proposed to fabricate the corrugation. Experimental results indicated that the mechanical sensitivity of the fabricated corrugated diaphragm (CD) was 52 nm/Pa, which was twice that of the planar diaphragm under the same parameters. Other characteristics of the fabricated microphone were also tested in detail. The proposed CD-based OFM showed the advantages of high sensitivity, simplicity and low cost, which was expected to be applied in the field of weak acoustic sensing.

Fabrication of three-dimensional parylene HT diaphragms using D-RIE with a Si substrate

This work demonstrates the fabrication of parylene diaphragms with three-dimensional configurations using deep-reactive ion etching (D-RIE, or ion-coupled plasma etching using the Bosch process) and assessed the characteristics of the resulting products. Parylene HT, which has superior temperature resistance up to 350°C, was used due to the significant heat generated in the D-RIE process. Parylene was first deposited on a silicon substrate and a diaphragm configuration was etched on the backside of this substrate. In contrast to wet etching, D-RIE was able to fabricate any outline of diaphragms with fine projections, such that could be employed in a microelectromechanical system (MEMS). Planar diaphragms were produced to ascertain the heat resistance of the parylene, and diaphragms (5mm in diameter, 10μm thick) with corrugated rectangular grooves (30–50μm deep) were also fabricated. Scanning electron microscopy (SEM) identified some defects in the corners of grooves when employing a depth of 50μm. Such grooves were eventually fabricated without defects by converting the rectangular corners to rounded shapes and by depositing aluminum on the parylene layer. It was found to be necessary to carefully assess the thermal stress in the vicinities of corners, and that this stress was primarily affected by the groove depth. Surface roughness and mechanical properties of the parylene layers, including Young’s modulus and yield stress, were assessed after the D-RIE process.

Study of the effect on flow rate for planar type polymer-based diaphragm piezoelectric actuated valveless micropump for insulin delivery

Micro-electromechanical systems are electrically sensed and actuated mechanical devices that are in micrometre-sized overall dimensions. The microsize of the system enables it to be used in several critical applications including healthcare where the system performance can be precisely controlled. One such application is micropump for drug delivery. Micropumps can be either valve based or valveless. Valve-based micropumps have mechanical check valves to control and deliver drugs through flaps or membranes. In valveless micropumps, the control is made through a diffuser/nozzle arrangement which regulates the liquid flow rate. In this paper, a valveless insulin pump based on piezoelectric actuation made of polymer-based material as diaphragm in planar type is constructed and the dependency of flow rate with material properties and size is studied. The modelling of the pump is carried out using COMSOL Multiphysics by coupling fluid structure interaction (fsi) and piezoelectric (pzd) physics module. The transient response of the flow rate and pressure distribution was studied. The dependency of flow rate with applied voltage, frequency and aspect ratio of the diffuser/nozzle was characterised by various size of the piezo layer and diaphragm layer. The effect on flow rate with polymethylmethacrylate and polydimethylsiloxane with single layer and stacked double layer was characterised. Sinusoidal actuating voltage is applied on piezoelectric material and varied up to a maximum of 180 V, 100 Hz. The simulation result proved that the flow rate can be effectively controlled with the application of appropriate combination of external sinusoid voltage, frequency and aspect ratio of the diffuser/nozzle.

A new acoustic transducer with a pressure-deformed piezoelectric diaphragm

A new design for wide-band acoustic transducers is described. Radial tension is applied to a thin piezoelectric diaphragm with conductive electrodes on the upper and lower surface. One side of the diaphragm is pressurized, elastically deforming the diaphragm into a slightly curved shape. The in-plane static tension is modulated by applying a time-dependent voltage across the electrodes of the piezoelectric diaphragm. The tension modulation causes transverse displacement oscillations of the diaphragm. This actuation takes place in spite of the fact that the piezoelectric diaphragm does not contain a passive elastic layer, which is necessary for actuation by flexure in planar diaphragms. A theoretical quasi-static model using hexagonal symmetry for the piezoelectric material was developed to predict the electromechanical actuation mechanism, and the mode for optimal operation in non-resonant conditions. Piezoelectric diaphragms were fabricated from PVDF film of nominal thickness 40μm into circular diaphragms 1cm in diameter. For the pressure-deformed transducers fabricated from PVDF film, displacement amplitudes of 9–14.5nm/V were observed, and the maximum displacement amplitude took place at the applied tension and static pressure predicted by the model. Additional measurements with conventional flexure-type transducers containing a diaphragm consisting of a layer of PZT and a passive elastic material fabricated using MEMS processes were performed to compare with the transducers fabricated from PVDF film. The displacement amplitude per unit electric field measured for the transducers fabricated from PVDF film was comparable to those measured from conventional PZT flexure-type transducers, despite the fact that the piezoelectric coupling coefficient for PVDF was approximately 100 times smaller than that for PZT.

Loudspeaker Including Slotted Waveguide For Enhanced Directivity And Associated Methods

A loudspeaker may include a baffle, a planar diaphragm transducer carried by the baffle and having a front surface for radiating acoustic energy therefrom, and a slotted waveguide adjacent the front surface of the planar diaphragm transducer. The planar diaphragm transducer may be operable to a desired high frequency, and the slotted opening may have a width not substantially greater than a wavelength corresponding to the desired high frequency. For example, for a desired high frequency of about 20 KHz, the slotted opening may have a width not greater than about two-thirds of an inch. Accordingly, the loudspeaker including the slotted waveguide may provide nearly constant horizontal directivity over a large angle. In another embodiment, the loudspeaker may include a conical diaphragm transducer with a slotted waveguide adjacent its front surface.

Low-profile transducer

One embodiment of a low-profile transducer includes a at least one fin perpendicularly mounted on a planar diaphragm, with a voice coil mounted onto the fin. The voice coil may reside in a strong uniform magnetic field. The locations at which the diaphragm is connected to a frame may be coplanar with a center of mass of the diaphragm. The three-dimensional structure of diaphragm and fins may be formed using origami techniques.

Plane speaker having coil plate guide device

The present invention relates to a plate type speaker with a planar diaphragm. The plate type speaker of the present invention comprises a base frame; at least one magnetic body coupled to the base frame such that opposite polarities are provided at adjacent lateral positions and are spaced apart by a predetermined distance from each other; a diaphragm; at least one coil plate that is formed with a voice coil wound on either or both of sides thereof, and is inserted vertically into spaces between the opposite polarities of the magnetic body and connected to the diaphragm; and a coil plate guide means coupled to the coil plate for guiding the position and vibration direction of the coil plate such that the coil plate is spaced from the magnetic bodies and vibrates vertically. The use of the plate type speaker with the coil plate guide means according to the present invention allows the position of a coil plate to be guided so that the coil plate does not come into contact with a permanent magnet or upper and lower plates even though the coil plate vibrates vertically, thereby preventing output of abnormal sound due to interference of the coil plate with the internal parts.

Directional Sound Radiation System Using a Large Planar Diaphragm Incorporating Multiple Vibrators

In this paper, we propose a new system for controlling radiated sound directivity. The proposed system artificially induces a bending vibration on a planar diaphragm by vibrating it artificially using multiple vibrators. Because the bending vibration in this case is determined by not one but all of the accelerated vibrations, the vibration of the diaphragm can be controlled by modulating the accelerated vibration waveforms relatively for each frequency. As a consequence, the directivity of the radiated sound is also varied. To investigate the feasibility of this system, we constructed a prototype that has for a diaphragm a circular plate-one of the most typical shapes considered for discussing plate vibration-and three vibrators. The measurement data showed visually that with this system, surface vibration and sound directivity change depending on the phases of the accelerated vibrations.

Planar diaphragm loudspeaker and related methods

A planar diaphragm loudspeaker for use in a suspended ceiling grid and related methods of manufacturing are provided. The loudspeaker includes a rectangular, planar diaphragm of polymer material sized to fill an opening of the ceiling grid. The front surface of the diaphragm defines a three-dimensional, textured pattern formed by a secondary operation, such as, etching, perforating, and adhesion of granular or fiber material. The diaphragm may include an outer region about the periphery of the diaphragm having a density of at least 5 pcf and an inner region circumscribed by the outer region, thereby providing sufficient structural stiffness to the outside perimeter of the diaphragm and eliminating the need of an outer frame. The density of the inner region is at or below about 3 pcf throughout the inner region. Also, a shroud may secured to the diaphragm, in which the shroud and the diaphragm are securable in a first orientation for flush mounting or in a second orientation for tegular-drop mounting. The loudspeaker may also include a bracket rigidly attached to the diaphragm at two spaced locations in the outer region and extending across the inner region between the spaced locations.

Compact Dry Vacuum Pumps

Diaphragm vacuum pumps are increasingly being used as roughing pumps for wide-range turbo molecular pumps, gas analyzers and other laboratory applications. Numerically optimized planar diaphragm technology and electronic drive systems make these systems even more compact, powerful and reliable. Maintenance intervals beyond 40,000 hours of continuous operation - similar to the interval of turbo molecular pumps - seem now reachable with variable speed systems.

Planar diaphragm loudspeakers with non-uniform air resistive loading for low frequency modal control

A loudspeaker, and particularly, a woofer, including a flat diaphragm transducer having at least one stator plate for carrying magnetic elements in close proximity to a low stiffness diaphragm wherein a piston-like motion of the diaphragm is achieved by creating pressure zones adjacent the diaphragm to improve an acoustic coupling and increase acoustic output for a given size of diaphragm by the provision of non-uniformly spaced openings in the at least one stator plate which are selectively spaced to control low frequency diaphragm resonance modes.

Performance of Fabry–Perot microcavity structures with corrugated diaphragms

A Fabry–Perot microcavity structure with a corrugated diaphragm as a deflecting diaphragm has been fabricated successfully. The composite dielectric layers of movable top and stationary bottom diaphragm of Fabry–Perot microcavity are optimized to have proper mechanical stability and optical response. Deflection behavior and device characteristics of a corrugated diaphragm case are compared with those of a planar diaphragm case. Output signal degradation as a function of pressure, “signal averaging effect”, is reduced using corrugated top diaphragm structures over planar top diaphragm structures. This is achieved by improving the flatness of the deflecting diaphragm in the optically sampled area of the microcavity structures. However, the corrugated structure shows a static deflection of the diaphragm without applying pressure due to the localized internal stress generated by the asymmetry of the corrugation on the diaphragm, “zero-pressure offset effect”. The existence and the influence of these parasitic effects have been observed by both real-time measurement and analytical simulation of the diaphragm.

Planar diaphragm loudspeaker with counteractive weights

A planar-type loudspeaker (10) incorporating a substantially planar diaphragm (12) constructed from a pre-expanded cellular plastic material, such as polystyrene, in which one or more balancing weights are embedded in a resilient material within recesses formed in the rear surface (26) of the diaphragm (12). The resilient material enables the weights a degree of movement relative to the diaphragm (12), such that the weights can serve a counteractive function to help control the frequency response characteristic of the diaphragm (12).

A wideband monolithic RMS-DC converter using micromachined diaphragm structures

This paper reports a monolithic rms-dc converter for measuring wideband rms signals. Two identical thermoelements for thermal rms-dc conversion are formed using planar diaphragm structures and micromachined dielectric windows. Each thermoelement consists of two polysilicon heaters and a thin-film temperature sensor located on a window and operated at constant temperature using on-chip control feedback circuitry. The thermoelements achieve a thermal efficiency greater than 7/spl deg/C/mW with a thermal time constant less than 5 ms. The on-chip control circuitry is realized using a standard 3 /spl mu/m p-well CMOS process with minor modifications for process compatibility with the dielectric window formation. This converter measures rms signals over a full scale range of 1 Vrms, handles crest factors in excess of 5, exhibits a typical nonlinearity of less than 1%, and achieves a 3 dB bandwidth greater than 20 MHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evidence that the spectrin network and a nonosmotic force control the fusion product morphology in electrofused erythrocyte ghosts

The conversion of the membrane area in the "contact zones" shared by erythrocyte ghosts held in contact by dielectrophoresis into a fusion product by electrofusion was studied by both light and electron microscopy. Fusion products fell into two categories: (a) those with a freely expanding open lumen which ended in the "giant cell morphology" and with considerable internal vesicle membrane fragments, and (b) linear chains of polyghosts with long term stability but having planar diaphragms at the ghost-ghost junctions. Thin section electron microscopy showed each of these planar diaphragms to be a double membrane septum multiply-perforated with fusion pores. Heat and low ionic strength treatments known to denature or detach spectrin caused the stable planar diaphragms to dissolve, thereby quickly converting the polyghost chains to the giant cell morphology, thereby suggesting that spectrin restricts fusion zone diameter expansion if it is intact. Other indications suggest that the expansion of the open lumens appears to take place as a result of one or more membrane-specific forces with a nonosmotic origin but this tendency to expansion can be overcome if the spectrin network on only one side of a contact zone is intact.

Planar loudspeaker system

First Page

Planar diaphragm transducer with improved magnetic circuit

A planar diaphragm type magnetic transducer with magnetic circuit wherein the magnet strips on the soft iron plate and confronting the diaphragm are arranged in a sequence south, north, north, south, south, north, north, south, et seq. The magnet strips are spaced across the transducer and the metal plates on which the magnet strips lie are apertured to make the plates acoustically transparent. Conductors are grouped in runs on the diaphragm opposite alternate pairs of magnet strips which have magnetic poles of opposite polarity at their front faces.

Piston‐diaphragm speaker

A planar diaphragm type magnetic transducer with an acoustically transparent magnetic backing, and a diaphragm overlying and spaced from the magnetic backing, the magnetic backing having magnetized strips lying parallel to each other and adjacent magnetized strips having opposite polarities at their faces confronting the diaphragm, the diaphragm being stiff and resisting flexing and connected by a flexible surround at its periphery.

Electroacoustic planar transducer

An electro-acoustic transducer using thin, lightweight, planar diaphragms driven by strategically located, coil-driven, high-energy, permanent magnets. A framework maintains the diaphragms in substantially co-planar relationship a predetermined distance from and parallel to a rear support wall. The diaphragms include at least one hinged woofer diaphragm and a foam-supported tweeter diaphragm. The small, high energy movable permanent magnets are attached to the rear surface of each movable diaphragm. Cooperating with each movable magnet is a respective, stationary electromagnetic coil with a crossover network directing the incoming signal to the appropriate coils, thereby placing the magnets and attached diaphragms into cooperating fore and aft motion. The frontal acoustical waves produced by each woofer constructively interfere to augment low frequency response. The tweeter construction provides wide frontal dispersion of high frequency acoustical waves. Woofer backwaves are attenuated before emerging along the rear support wall and the tweeter backwave is vented into a rear isolative chamber.