Showing papers on "Transducer published in 2010"

Noncontact Tactile Display Based on Radiation Pressure of Airborne Ultrasound

Abstract: This paper describes a tactile display which provides unrestricted tactile feedback in air without any mechanical contact. It controls ultrasound and produces a stress field in a 3D space. The principle is based on a nonlinear phenomenon of ultrasound: Acoustic radiation pressure. The fabricated prototype consists of 324 airborne ultrasound transducers, and the phase and intensity of each transducer are controlled individually to generate a focal point. The DC output force at the focal point is 16 mN and the diameter of the focal point is 20 mm. The prototype produces vibrations up to 1 kHz. An interaction system including the prototype is also introduced, which enables users to see and touch virtual objects.

Measuring the local pressure amplitude in microchannel acoustophoresis

Abstract: A new method is reported on how to measure the local pressure amplitude and the Q factor of ultrasound resonances in microfluidic chips designed for acoustophoresis of particle suspensions. The method relies on tracking individual polystyrene tracer microbeads in straight water-filled silicon/glass microchannels. The system is actuated by a PZT piezo transducer attached beneath the chip and driven by an applied ac voltage near its eigenfrequency of 2 MHz. For a given frequency a number of particle tracks are recorded by a CCD camera and fitted to a theoretical expression for the acoustophoretic motion of the microbeads. From the curve fits we obtain the acoustic energy density, and hence the pressure amplitude as well as the acoustophoretic force. By plotting the obtained energy densities as a function of applied frequency, we obtain Lorentzian line shapes, from which the resonance frequency and the Q factor for each resonance peak are derived. Typical measurements yield acoustic energy densities of the order of 10 J/m3, pressure amplitudes of 0.2 MPa, and Q factors around 500. The observed half wavelength of the transverse acoustic pressure wave is equal within 2% to the measured width w = 377 μm of the channel.

Method and apparatus for energy harvest from ambient sources

Abstract: An energy harvesting system includes a plurality of transducers. The transducers are configured to generate direct current (DC) voltages from a plurality of ambient energy sources. A sensor control circuit has a plurality of sensors configured to detect the DC signals from the plurality of transducers. A DC-to-DC converter is configured to supply an output voltage. A plurality of switches, each switch coupled between the DC-to-DC converter and a corresponding transducer of the plurality of transducers. The sensor control circuit enables one switch of the plurality of switches and disables the other switches of the plurality of switches based on a priority criterion.

Electronic devices with improved audio

Abstract: An electronic device having an enclosure including an upper panel and a bottom panel operably connected to the upper panel. A transducer is operably connected to the enclosure and the transducer is configured to mechanically vibrate the enclosure. The transducer includes an electromagnet, a magnet in communication with the electromagnet and a bracket substantially surrounding the electromagnet and the magnet, the bracket substantially secures the transducer to the bottom panel.

Pulsed waveguide sensing device and method for measuring a parameter

Abstract: At least one embodiment is directed to a sensor for measuring a parameter. A signal path of the system comprises an amplifier ( 612 ), a sensor element, and an amplifier ( 620 ). The sensor element comprises a transducer ( 4 ), a waveguide ( 5 ), and a transducer ( 30 ). A parameter such as force or pressure applied to the sensor element can change the length of waveguide ( 5 ). A pulsed energy wave is emitted by the transducer ( 4 ) into the waveguide ( 5 ) at a first location. The transducer ( 30 ) is responsive pulsed energy waves at a second location of the waveguide ( 5 ). The transit time of each pulsed energy wave is measured. The transit time corresponds to the pressure or force applied to the sensor element.

Method and system for optically coupling a laser with a transducer in an energy assisted magnetic recording disk drive

Abstract: A method and system for providing an energy assisted magnetic recording (EAMR) head are described. The EAMR head includes a laser, a slider, and an EAMR transducer. The laser has a main emitter and at least one alignment emitter. The slider includes at least one alignment waveguide, at least one output device, and an air-bearing surface (ABS). The alignment waveguide(s) are aligned with the alignment emitter(s). The EAMR transducer is coupled with the slider and includes a waveguide aligned with main emitter. The waveguide is for directing energy from the main emitter toward the ABS.

Method for providing an electronic lapping guide corresponding to a near-field transducer of an energy assisted magnetic recording transducer

Abstract: A method fabricates a transducer having an air-bearing surface (ABS). The method includes providing at least one near-field transducer (NFT) film and providing an electronic lapping guide (ELG) film substantially coplanar with a portion of the at least one NFT film. The method also includes defining a disk portion of an NFT from the portion of the at least one NFT film and at least one ELG from the ELG film. The disk portion corresponds to a critical dimension of the NFT from an ABS location. The method also includes lapping the at least one transducer. The lapping is terminated based on a signal from the ELG.

Method and system for providing an energy assisted magnetic recording writer having an integrated NFT, heat sink, and pole

Abstract: A method and system for providing an energy assisted magnetic recording (EAMR) transducer coupled with a laser are described. The laser provides energy. The EAMR transducer has an air-bearing surface (ABS) configured to reside in proximity to a media during use. The EAMR transducer includes a near field transducer (NFT) proximate to the ABS for focusing the energy onto the region of the media. The method and system include providing a heat sink having a bottom thermally coupled with the NFT and a top surface at an angle with respect to the ABS. The angle is greater than zero and less than ninety degrees. The method and system also include providing a write pole and at least one coil. The write pole is configured to write to a region of the media. The write pole has a bottom surface thermally coupled with the top surface of the heat sink. The at least one coil is for energizing 24.

Method and system for providing separate write and optical modules in an energy assisted magnetic recording disk drive

Abstract: An energy assisted magnetic recording (EAMR) transducer coupled with a laser is described. The EAMR transducer has an air-bearing surface (ABS) residing near a media during use. The EAMR transducer includes optical and writer modules. The optical module includes a waveguide and a near field transducer (NFT). The waveguide directs the energy from the laser toward the ABS. The NFT focuses the energy onto the media. The optical and writer modules are physically separate such that no portion of the waveguide is interleaved with a magnetic portion of the writer module. The writer module includes a write pole and coil(s). The write pole includes a pole-tip portion for providing a magnetic field to the media and a yoke. The pole-tip portion has an ABS-facing surface, a sloped surface, and a NFT-facing surface therebetween. The sloped surface is at least twenty-five and not more than sixty-five degrees from the NFT-facing surface.

Method and system for providing an energy assisted magnetic recording disk drive having improved heat dissipation

Abstract: An energy assisted magnetic recording (EAMR) transducer coupled with a laser is described. The EAMR transducer has an air-bearing surface (ABS) residing near a media during use. The laser provides energy. The transducer includes a waveguide, a near field transducer (NFT) proximate to the ABS, a write pole and at least one coil. The waveguide directs the energy from the laser toward the ABS. The NFT is optically coupled with the waveguide and focuses the energy onto a region of the media. The write pole writes to the region of the media. The write pole has a magnetic portion and a nonmagnetic liner. The magnetic portion has a plurality of sides and a pole thermal conductivity. The nonmagnetic liner is adjacent to at least the sides of the magnetic portion, and has a liner thermal conductivity greater than the pole thermal conductivity. The coil(s) are for energizing the write pole.

Simple piezoelectric-actuated mirror with 180 kHz servo bandwidth.

Abstract: We present a high bandwidth piezoelectric-actuated mirror for length stabilization of an optical cavity. The actuator displays a transfer function with a flat amplitude response and greater than 135 masculine phase margin up to 200 kHz, allowing a 180 kHz unity gain frequency to be achieved in a closed servo loop. To the best of our knowledge, this actuator has achieved the largest servo bandwidth for a piezoelectric transducer (PZT). The actuator should be very useful in a wide variety of applications requiring precision control of optical lengths, including laser frequency stabilization, optical interferometers, and optical communications.

Method and system for enhancing optical efficiency for an EAMR head

Abstract: A method and system for providing an EAMR transducer and a waveguide used therein are described. The EAMR transducer is coupled with a laser that provides energy. The EAMR transducer also has an ABS that resides in proximity to a media during use. The EAMR transducer includes a waveguide, a write pole to write to a region of the media, coil(s) for energizing the write pole, and a near field transducer (NFT) proximate to the ABS for focusing the energy onto the media. The waveguide includes a mode shift compensator, first and second cladding layers, and a core between the cladding layers. The core directs energy from the laser toward the ABS and has a core index of refraction. The core is also between the mode shift compensator and the NFT. The mode shift compensator has a mode shift compensator index of refraction less than the core index of refraction.

Imaging Pauli repulsion in scanning tunneling microscopy.

Abstract: A scanning tunneling microscope (STM) has been equipped with a nanoscale force sensor and signal transducer composed of a single ${\mathrm{D}}_{2}$ molecule that is confined in the STM junction. The uncalibrated sensor is used to obtain ultrahigh geometric image resolution of a complex organic molecule adsorbed on a noble metal surface. By means of conductance-distance spectroscopy and corresponding density functional calculations the mechanism of the sensor and transducer is identified. It probes the short-range Pauli repulsion and converts this signal into variations of the junction conductance.

Energy-assisted magnetic recording head having waveguide capable of providing small beam spots

Abstract: A method and system for providing an EAMR transducer is described. The EAMR transducer has an ABS and is coupled with a laser. The EAMR transducer includes a write pole, coil(s), and an energy delivery device. The write pole magnetically writes to the media. The coil(s) energize the write pole. The energy delivery device is optically coupled with the laser and includes a top distal from the ABS, a bottom proximate to the ABS, a first side, and a second side opposite to the first side. The first side has a first apex angle from a normal to the ABS and is reflective. The second side has a second apex angle from the normal and is reflective. The first and second apex angles are each at least three and not more than twenty-five degrees. The first and second sides converge such that the top is wider than the bottom.

Energy assisted magnetic recording head having a reflector for improving efficiency of the light beam

Abstract: A method and system for providing an EAMR transducer is described. The EAMR transducer is coupled with a laser for providing energy and has an ABS that resides near a media during use. The EAMR transducer includes a write pole, coil(s) that energize the pole, a near field transducer (NFT) proximate to the ABS, a waveguide, and a reflector. The write pole has a back gap region and writes to a region of the media. The NFT focuses the energy onto the media. The waveguide directs the energy from the laser toward the NFT at an incident angle with respect to the ABS. A first portion of the energy reflects off of the ABS at a reflected angle. The reflector receives the first portion of the energy from the ABS and reflects a second portion of the energy toward the ABS. The NFT resides between the waveguide and the reflector.

Method for providing a perpendicular magnetic recording transducer using a low energy mill

Abstract: A method for fabricating magnetic transducer is described. The method includes providing a main pole having a bottom and a top wider than the bottom. The method further includes performing a high energy ion mill at an angle from a normal to the to of the main pole and at a first energy. The high energy ion mill removes a portion of the top of the main pole and exposes a top bevel surface for the main pole. The method also includes performing a low energy ion mill at second energy and a glancing angle from the top bevel surface. The glancing angle is not more than fifteen degrees. The second energy is less than the first energy. The method and system also include depositing a nonmagnetic gap.

Method and system for an energy assisted magnetic recording head having a suspension-mounted laser

Abstract: An energy assisted magnetic recording (EAMR) disk drive comprises a suspension and a slider having a back side, a laser-facing surface, and an air-bearing surface (ABS) opposite the back side. The slider is mounted to the suspension on the back side. The disk drive further comprises an EAMR transducer coupled with the slider, a portion of the EAMR transducer residing in proximity to the ABS and on the laser-facing surface of the slider. The disk drive further comprises a laser coupled with the suspension and having a light emitting surface facing the laser-facing surface of the slider. The laser has an optic axis substantially parallel to the suspension. The laser provides energy substantially along the optic axis and is optically coupled with the EAMR transducer via free space. The EAMR transducer receives the energy from the laser and writes to the media using the energy.

Impact damage detection in composite laminates using nonlinear acoustics

Abstract: The paper demonstrates the application of nonlinear acoustics for impact damage detection in composite laminates. A composite plate is monitored for damage resulting from a low-velocity impact. The plate is instrumented with bonded low-profile piezoceramic transducers. A high-frequency acoustic wave is introduced to one transducer and picked up by a different transducer. A low-frequency flexural modal excitation is introduced to the plate at the same time using an electromagnetic shaker. The damage induced by impact is exhibited in a power spectrum of the acoustic response by a pattern of sidebands around the main acoustic harmonic. The results show that the amplitude of sidebands is related to the severity of damage. The study investigates also the effect of boundary conditions on the results.

A magnetoelectric energy harvester and management circuit for wireless sensor network

Abstract: This paper presents an electromagnetic energy harvesting scheme by using a composite magnetoelectric (ME) transducer and a power management circuit. In the transducer, the vibrating wave induced from the magnetostrictive Terfenol-D plate in dynamic magnetic field is converged by using an ultrasonic horn. Consequently more vibrating energy can be converted into electricity by the piezoelectric element. A switching capacitor network for storing electricity is developed. The output of the transducer charges the storage capacitors in parallel until the voltage across the capacitors arrives at the threshold, and then the capacitors are automatically switched to being in series. More capacitors can be employed in the capacitor network to further raise the output voltage in discharging. For the weak magnetic field environment, an active magnetic generator and a magnetic coil antenna under ground are used for producing an ac magnetic field of 0.2–1 Oe at a distance of 25–50 m. In combination with the supply management circuit, the electromagnetic energy harvester with a rather weak power output (about 20 μW) under an ac magnetic field of 1 Oe can supply power for wireless sensor nodes with power consumption of 75 mW at a duration of 620 ms.

High-resolution, high-contrast ultrasound imaging using a prototype dual-frequency transducer: In vitro and in vivo studies

Abstract: With recent advances in animal models of disease, there has been great interest in capabilities for highresolution contrast-enhanced ultrasound imaging. Microbubble contrast agents are unique in that they scatter broadband ultrasound energy because of their nonlinear behavior. For optimal response, it is desirable to excite the microbubbles near their resonant frequency. To date, this has been challenging with high-frequency imaging systems because most contrast agents are resonant at frequencies in the order of several megahertz. Our team has developed a unique dual-frequency confocal transducer which enables low-frequency excitation of bubbles near their resonance with one element, and detection of their emitted high-frequency content with the second element. Using this imaging approach, we have attained an average 12.3 dB improvement in contrast-to-tissue ratios over fundamental mode imaging, with spatial resolution near that of the high-frequency element. Because this detection method does not rely on signal decorrelation, it is not susceptible to corruption by tissue motion. This probe demonstrates contrast imaging capability with significant tissue suppression, enabling high-resolution contrast-enhanced images of microvascular blood flow. Additionally, this probe can readily produce radiation force on flowing contrast agents, which may be beneficial for targeted imaging or therapy.

High temperature ultrasonic transducer up to 1000 °C using lithium niobate single crystal

Abstract: Structural health monitoring (SHM) techniques are needed to maintain the reliability of aging power plants. The high temperature transducers are necessary to realize SHM under the working condition of power plants. In this paper, a high temperature transducer was developed using lithium niobate (LiNbO3) single crystal, which is well known as a high Curie temperature piezoelectric material. The LiNbO3 was bonded onto a stainless steel substrate. The transducer was heated in an electric furnace while measuring the bottom echoes from the substrate. We confirmed that the high temperature transducer could work up to 1000 °C.

Novel auto-correction method in a fiber-optic distributed-temperature sensor using reflected anti-Stokes Raman scattering

Abstract: A novel method for auto-correction of fiber optic distributed temperature sensor using anti-Stokes Raman back-scattering and its reflected signal is presented. This method processes two parts of measured signal. One part is the normal back scattered anti-Stokes signal and the other part is the reflected signal which eliminate not only the effect of local losses due to the micro-bending or damages on fiber but also the differential attenuation. Because the beams of the same wavelength are used to cancel out the local variance in transmission medium there is no differential attenuation inherently. The auto correction concept was verified by the bending experiment on different bending points.

Ultrasonic transducer for use in a fluid medium

Abstract: An ultrasonic transducer for use in a fluid medium is proposed. The ultrasonic transducer includes at least one transducer core which has at least one acoustic/electric transducer element, in particular a piezoelectric transducer element. The ultrasonic transducer furthermore includes at least one housing, at least one housing opening being at least partially sealed against the fluid medium with the aid of a sealing film which is connected to the transducer core. The sealing film has at least one expansion deformation which is configured to permit a relative movement between the transducer core and the housing.

Rotational intravascular ultrasound probe with an active spinning element

Abstract: An intravascular ultrasound probe is disclosed, incorporating features for utilizing an advanced transducer technology on a rotating transducer shaft. In particular, the probe accommodates the transmission of the multitude of signals across the boundary between the rotary and stationary components of the probe required to support an advanced transducer technology. These advanced transducer technologies offer the potential for increased bandwidth, improved beam profiles, better signal to noise ratio, reduced manufacturing costs, advanced tissue characterization algorithms, and other desirable features. Furthermore, the inclusion of electronic components on the spinning side of the probe can be highly advantageous in terms of preserving maximum signal to noise ratio and signal fidelity, along with other performance benefits.

Active noise reduction system

Abstract: A system for actively reducing noise at a listening point, includes an earphone housing, a transmitting transducer, a receiving transducer and a controller. The transmitting transducer converts a first electric signal into a first acoustic signal, and radiates the first acoustic signal along a first acoustic path having a first transfer characteristic and along a second acoustic path having a second transfer characteristic. The receiving transducer converts the first acoustic signal and ambient noise into a second electrical signal. The controller compensates for the ambient noise by providing a noise reducing electrical signal to the transmitting transducer. The noise reducing electrical signal is derived from a filtered electrical signal that is provided by filtering the second electrical signal with a third transfer characteristic. The second and the third transfer characteristics together model the first transfer characteristic.

Modeling the Effects of Electromechanical Coupling on Energy Storage Through Piezoelectric Energy Harvesting

Abstract: This paper focuses on comparing the effects of varying degrees of electromechanical coupling in piezoelectric power harvesting systems on the dynamics of charging a storage capacitor. In order to gain an understanding of the behavior of these dynamics, a transducer whose vibrational dynamics are impacted very little by electrical energy extraction is compared to a transducer that displays strong electromechanical coupling. Both transducers are cantilevered piezoelectric beams undergoing base excitation whose harvested electrical energy is used to charge a storage capacitor. The transient dynamics of the coupled system are studied in detail with an emphasis on their charging power curves and the time to charge the storage capacitor to a specified voltage. An analytic model for the system is derived that takes into consideration the reduction in vibration amplitude of the beam caused by the removal of electrical energy. Although this model makes the typical assumption that the beam is vibrating at its open-circuit resonance, it is shown to predict the charging behavior of the system accurately when compared to experimental results and a complete, nonlinear simulation without this simplification. Finally, the simplifications and discrepancies created by several types of modeling assumptions for a highly coupled energy harvesting system are discussed.

Downscan imaging sonar

Abstract: A downscan imaging sonar utilizes a linear transducer element to provide improved images of the sea floor and other objects in the water column beneath a vessel. A transducer array may include a plurality of transducer elements and each one of the plurality of transducer elements may include a substantially rectangular shape configured to produce a sonar beam having a beamwidth in a direction parallel to longitudinal length of the transducer elements that is significantly less than a beamwidth of the sonar beam in a direction perpendicular to the longitudinal length of the transducer elements. The plurality of transducer elements may be positioned such that longitudinal lengths of at least two of the plurality of transducer elements are parallel to each other. The plurality of transducer elements may also include at least a first linear transducer element, a second linear transducer element and a third linear transducer element.

Hearing system and method for operating a hearing system

Abstract: A hearing system (1) capable of assisting a user of the hearing system (1) to find a location where satisfactory hearing performance is achievable is described. The hearing system (1) comprises at least one hearing device (11, 12) with an input transducer (20), an output transducer (40), and a processing unit (30) operatively connected to the input transducer (20) as well as to the output transducer (40). The hearing system (1) further comprises a first means (50) for determining from a signal of the input transducer (20) at least one parameter (60) representative of a current acoustic environment at a current location, and a second means (40, 200, 201) for indicating to a user of the hearing system (1) a degree of suitability of the current location to achieve satisfactory hearing performance based on the at least one parameter (60).