Abstract: One aspect relates to an electrical bushing for use in a housing of an implantable medical device. The electrical bushing includes at least one electrically insulating base body and at least one electrical conducting element. The conducting element is set-up to establish, through the base body, at least one electrically conductive connection between an internal space of the housing and an external space. The conducting element is hermetically sealed with respect to the base body. The at least one conducting element includes at least one cermet. The cermet has a metal fraction in a range from 30% by volume to 60% by volume.

Abstract: An apparatus including a diaphragm, where the diaphragm includes a membrane having electrically conductive material; a drive configured to move the diaphragm; and a connector configured to connect the membrane to a ground.

Abstract: A catheter is provided for medical ultrasound imaging that can be effectively used in combination with other imaging modalities to detect medical structures of interest as well as the catheter. Markers are added to the catheter with precision, which provides a means to merge the images from different modalities. Using a template, apertures for marker placement are formed in the catheter after creating the catheter housing. The ultrasound array may be used for accurate positioning of the template. Alternatively or additionally, a rigid insert with markers connects with the array. The insert holds the markers in place and may reduce artifacts in ultrasound scanning due to flexing of the array.

Abstract: Disclosed herein, among other things, are systems and methods for solderless assembly for hearing assistance devices. One aspect of the present subject matter includes a method of manufacturing a hearing assistance device. According to various embodiments, the method includes providing a molded interconnect device (MID) housing and inserting a flexible circuit module having conductive surface traces into the MID housing. One or more hearing assistance electronic modules are connected to the MID housing using direct compression without the use of wires or solder, according to various embodiments. In one embodiment, the MID housing includes a laser-direct structuring (LDS) housing.

Abstract: Methods for manufacturing multiple bottom port, surface mount microphones, each containing a micro-electro-mechanical system (MEMS) microphone die, are disclosed. Each surface mount microphone features a substrate with metal pads for surface mounting the package to a device's printed circuit board and for making electrical connections between the microphone package and the device's circuit board. The surface mount microphones are manufactured from panels of substrates, sidewall spacers, and lids. Each MEMS microphone die is substrate-mounted and acoustically coupled to the acoustic port disposed in the substrate. The panels are joined together, and each individual substrate, sidewall spacer, and lid cooperate to form an acoustic chamber for its respective MEMS microphone die. The joined panels are then singulated to form individual MEMS microphones.

Abstract: Arrays of resonator sensors include an active wafer array comprising a plurality of active wafers, a first end cap array coupled to a first side of the active wafer array, and a second end cap array coupled to a second side of the active wafer array. Thickness shear mode resonator sensors may include an active wafer coupled to a first end cap and a second end cap. Methods of forming a plurality of resonator sensors include forming a plurality of active wafer locations and separating the active wafer locations to form a plurality of discrete resonator sensors. Thickness shear mode resonator sensors may be produced by such methods.

Abstract: A mono-body set of headphones having a fixed length of headband between ear pads is provided. Although the distance between the ear pads is fixed, the fit of the headphones can be adjusted to the head of the user by coupling or decoupling a removable/insertable headphone pad. More particularly, a pad is provided that can be mated with, or removed from, the headband of the headphones, thus raising or lowering the lower surface of the headband relative to the crown of the user's head, in order to change the position of the ear pads relative to the user's ears. The mono-body headphones are, preferably, flexible and durable, permitting the headphones to be straightened, twisted or bent without breaking.

Abstract: An ultrasonic device includes a substrate, an acoustic adjustment layer, an acoustic lens and a structural member. The substrate has an element array including a plurality of thin film ultrasonic transducer elements arranged in an array form. The acoustic adjustment layer covers the element array. The acoustic lens is arranged above the acoustic adjustment layer. The structural member is in contact with the acoustic lens and fixed to the substrate. The structural member has a modulus of rigidity greater than a modulus of rigidity of the acoustic lens.

Abstract: In an actuator (50), a bobbin (511) to which a voice coil (513) is attached is disposed within a magnetic path space formed by a magnetic path forming section (52). A connecting shaft (514) is coupled to the bobbin (511), and a connection end portion (516A) at a distal end of the connecting shaft is connected to a sound board of a musical instrument. The length of the shaft (514) can be adjusted. When the actuator (50) is attached to the sound board, the length of the shaft (514) is adjusted and the connection end portion (516A) is connected to the sound board while a position of the voice coil (513) within the magnetic path space is maintained in a predetermined reference mounting position, in a state in which the magnetic path forming unit (52) is supported in a predetermined position by a support unit (55).

Abstract: An ultrasonic sensor includes a housing having a peripheral side wall and a base surface, i.e., it is configured as essentially pot-shaped. The base surface is configured as a diaphragm. A transducer element, which is configured as a piezoelectric element, for example, and is used for generating and detecting ultrasonic oscillations, is situated on the base surface. At least one mass element is situated on the base surface so that the resistance of the mass element against an oscillation of the diaphragm increases with rising oscillation frequency.

Abstract: A device, including an implantable microphone, including a chamber in which media corresponding to at least one of a liquid or a fluid resistant to compression is located such that vibrations originating external to the microphone are effectively transmitted through the media.

Abstract: A surface mount package for a micro-electro-mechanical system (MEMS) microphone die is disclosed. The surface mount package features a substrate with metal pads for surface mounting the package to a device's printed circuit board and for making electrical connections between the microphone package and the device's circuit board. The surface mount microphone package has a sidewall spacer and a lid, and the MEMS microphone die is substrate-mounted and acoustically coupled to the acoustic port in the substrate. The substrate, the sidewall spacer, and the lid are joined together to form the MEMS microphone, and the substrate, the sidewall spacer, and the lid cooperate to form an acoustic chamber for the substrate-mounted MEMS microphone die.

Abstract: A top-port, surface mount package for a micro-electro-mechanical system (MEMS) microphone die is disclosed. The surface mount package features a substrate with metal pads for surface mounting the package to a device's printed circuit board and for making electrical connections between the microphone package and the device's circuit board. The surface mount microphone package has a sidewall spacer and a lid with an acoustic port, and the MEMS microphone die is lid-mounted and acoustically coupled to the acoustic port. The substrate, the sidewall spacer, and the lid are joined together to form the MEMS microphone, and the substrate, the sidewall spacer, and the lid cooperate to form an acoustic chamber for the lid-mounted MEMS microphone die.

Abstract: Provided is a method for manufacturing a surface acoustic wave apparatus that can reduce degradation of electric characteristics and also reduce the number of manufacturing processes. The method for manufacturing a surface acoustic wave apparatus includes the steps of: forming an IDT electrode on an upper surface of a piezoelectric substrate, forming a frame member surrounding a formation area in which the IDT electrode is formed on the piezoelectric substrate, and mounting a film-shaped lid member on the upper surface of the frame member so as to be joined to the frame member so that a protective cover, used for covering the formation area and for providing a tightly-closed space between it and the formation area, is formed.

Abstract: A method of fabricating a custom-fit in-ear-monitor (IEM) is provided that utilizes a pre-tuned, single piece driver module to simplify fabrication and reduce cost while insuring that the performance of the IEM consistently meets the acoustic goals set for the device. During fabrication the driver module, the drivers coupled to the module's driver ports, and the crossover circuit are installed in a custom-fit IEM shell such that the module's acoustic output is aligned with the output surface of the IEM shell. After installing the device components within the IEM shell, the shell is sealed.

Abstract: A method for manufacturing an electronic component includes a first step of preparing a piezoelectric body with a flat surface, a second step of implanting ions into the piezoelectric body such that an ion-implanted layer is formed in the piezoelectric body, a third step of forming sacrificial layers on the flat surface of the piezoelectric body, a fourth step of forming an insulating body over the flat surface of the piezoelectric body and the sacrificial layers to form a piezoelectric structure, a fifth step of dividing the piezoelectric body at the ion-implanted layer to form a piezoelectric laminar structure in which a piezoelectric film separated from the piezoelectric body is bonded to the insulating body, a sixth step of forming electrodes on portions of a division surface of the piezoelectric film, and a seventh step of removing the sacrificial layers from the piezoelectric laminar structure.

Abstract: Provided is an ultrasonic device including: an ultrasonic element array substrate having a plurality of ultrasonic elements configured to perform at least one of transmission and reception of ultrasound; an acoustic lens configured to focus the ultrasound; an acoustic matching unit formed using resin, the acoustic matching unit being arranged between the ultrasonic element array substrate and the acoustic lens; and a plurality of spherical spacing members arranged between the ultrasonic element array substrate and the acoustic lens so as to be in contact with the ultrasonic element array substrate and the acoustic lens.

Abstract: An open modular speaker assembly is configured to be inserted into a mobile wireless device and includes a frame, a magnetic assembly that is disposed within the frame and a membrane assembly disposed within the frame and in proximity to the magnetic assembly. Actuation of the magnetic assembly by an electric current causes a movement of the magnetic assembly causing a resultant movement of the membrane assembly. A first portion of the mobile wireless device and the membrane assembly form a front volume where the resultant movement of the membrane assembly produces sound in the front volume, and such that a second portion of the mobile wireless device and the membrane assembly form a back volume that is separated from the front volume by the membrane assembly. Air is displaced or exchanged between the front volume and the back volume.

Abstract: A method of making a resonating beam accelerometer (RBA). In an example process, a proof mass device and resonators are created from a quartz material. A direct bond is formed between the proof mass and the resonators by applying a predefined amount of pressure at a predefined temperature for a predefined amount of time. One or more damping plates are created from a quartz material. A direct bond is formed between the damping plates and the proof mass device. The proof mass device is created by applying a predefined amount of pressure at pressure at temperature to two bases, two proof mass portions, and a flexure. The proof mass bases are on opposite sides of the flexure. The proof mass portions are on opposite sides of the flexure. A gap is present between the proof mass bases and the proof mass portions.

Abstract: A method of manufacturing a microphone assembly having an ear set function includes assembling a mike cell unit; obtaining a region for connection with the mike cell unit on a PCB, mounting only a conductive member in the region, and mounting other remaining components outside the region; adhering the mike cell unit to a corresponding region of the PCB; and sealing an adhering portion between the mike cell unit and the PCB. Assembling the mike cell unit includes inserting a mike cell case having a sound hole and a curing portion into a diaphragm assembly; stacking a spacer on the diaphragm assembly; inserting a back electrode plate into an insulating ring base; mounting the insulating ring base on the spacer; mounting a metal ring base on the insulating ring base; and curing or clamping a curing portion of the mike cell case.

Abstract: The present invention relates to a surface mount package for a micro-electro-mechanical system (MEMS) microphone die and methods for manufacturing the surface mount package. The surface mount package uses a limited number of components that simplifies manufacturing and lowers costs. The surface mount package features a substrate that performs functions for which multiple components were traditionally required, including providing an interior surface on which the MEMS microphone die is mechanically attached, providing an interior surface for making electrical connections between the MEMS microphone die and the package, and providing an exterior surface for surface mounting the microphone package to a device's printed circuit board and for making electrical connections between the microphone package and the device's circuit board. The microphone package has a substrate with metal pads on its top and bottom surfaces, a sidewall spacer, and a lid.

Abstract: A battery powered wireless audio speaker comprising a passive radiator is disclosed. The perimeter portion of the passive radiator is sandwiched between the speaker chassis and the retention gasket that resides between an external overlying perforated cover to firmly secure the passive radiator. The construction is capable of being well suited to enhance and improve integrity to the seal between the passive radiator and the speaker chassis in strenuous environment conditions such as when a speaker is submerged in water.

Abstract: In an electrodynamic acoustic transducer which uses a surface potential of an electret dielectric film as a polarization voltage, prevention of partial suctional adhesion of a diaphragm caused by variation in surface potential across the electret dielectric film is ensured in a simple way. In an electrodynamic acoustic transducer including a diaphragm and a fixed pole which are arranged with a predetermined interval so as to face each other, a facing surface of either one of the diaphragm and the fixed pole having an electret dielectric film, a surface of the electret dielectric film is divided into a plurality of segment regions, and a predetermined surface potential is given to each of the segment regions by a polarization processing unit.

Abstract: A method for assembling an ultrasonic surgical device includes the steps of rotatably freely connecting an ultrasonic waveguide to an ultrasonic surgical handle body, the ultrasonic waveguide having a proximal coupling end, substantially simultaneously removably coupling an ultrasonic-driving-wave-signal generating circuit to the ultrasonic surgical handle body and removably inserting an ultrasonic-movement-producing distal end of a cordless, rotatably free ultrasonic transducer into the ultrasonic surgical handle body opposite the proximal coupling end of the ultrasonic waveguide, and rotating the ultrasonic waveguide with respect to the ultrasonic transducer to fixedly couple the ultrasonic waveguide to the ultrasonic-movement-producing distal end of the ultrasonic transducer.

Abstract: A Microelectromechanical System (MEMS) microphone includes a printed circuit board, a MEMS die, and an integrated circuit. The MEMS die is disposed on a top surface of the printed circuit board. The integrated circuit is disposed at least partially within the printed circuit board and produces at least one output signal. The output signals of the integrated circuit are routed directly into at least one conductor to access pads at the printed circuit board and the access pads are disposed on a bottom surface of the printed circuit board that is opposite the top surface.

Abstract: A method for manufacturing piezoelectric resonator devices according to the present invention includes the following steps: a wafer forming step of preparing a thick-walled wafer 30 integrally formed with multiple lower lid members 3; a bonding step of bonding crystal resonator plates 2 to one main surface 31 of the wafer 30 via a bonding material 5 and bonding upper lid members 4 on the crystal resonator plates via a bonding material 5; a thinning step of thinning the wafer 30 from the other main surface 37 of the wafer; an external terminal forming step of forming external terminals on the other main surface of the thinned wafer; and a dividing step of cutting the wafer between each adjacent pair of crystal resonators so that multiple crystal resonators are obtained.

Abstract: The present disclosure relates to a connection member for connecting a headset plug with an electronic device, a headset jack of the electronic device and the electronic device. The connection member comprises a pin, wherein the pin communicates with a terminal positioned near an end portion of the headset plug when the connection member is connected with the headset plug. The connection member disclosed in the present disclosure can reduce the length of the headset to be inserted into the headset jack, and reduce the depth of the headset jack, thereby saving space in the electronic device configured with the headset jack.

Abstract: Methods and systems may provide for a system having a flexible substrate, an ultrasonic transducer array coupled to the flexible substrate and a processor coupled to the ultrasonic transducer array. The processor may identify a fingerprint based on a signal from the ultrasonic transducer array. The system may also include an external component having a curved profile, wherein the ultrasonic transducer array is embedded in the external component and includes a read surface that conforms to the curved profile. In one example, the external component includes a button having a function that is separate from identification of the fingerprint.

Abstract: The disclosure provides an earphone and a fabrication method thereof. The earphone includes: an earphone wire, wherein the earphone wire includes flexible wire parts and hard wire parts which are arranged alternately. The technical scheme provided in the disclosure solves the problem existing in the related technologies that earphone wires entwine easily and cannot be untangled readily and therefore effectively avoids the entwining of earphone wires and improves user experience.

Abstract: A joint speaker surround and gasket. The speaker surround of the joint speaker surround and gasket is formed of a surround material and has an inner edge defining a speaker cone aperture shaped to match a speaker cone and an outer edge portion shaped to match a housing. The gasket of the joint speaker surround and gasket is formed of a gasket material. The gasket is integrally bonded to the outer edge portion of the speaker surround.

Abstract: A method to align an optical device optically with an interference device is disclosed. The method includes steps of: selecting one of arm waveguides, biasing rest of arm waveguides to cause optical absorption thereat, and aligning the optical device optically with the selected arm waveguide.

Abstract: A method for forming an acoustical stack for an ultrasound probe comprises partly dicing a single crystal piezoelectric material to form single crystal pieces that are partly separated by a plurality of kerfs. The single crystal piezoelectric material comprises a carrier layer. The kerfs are filled with a kerf filling material to form a single crystal composite and the carrier layer is removed. At least one matching layer is attached to the single crystal composite, and dicing within the kerfs is accomplished to form separate acoustical stacks from the single crystal composite.

Abstract: An ear-fitting headphone restraint system includes an attachment assembly configured to be coupled to a portion of a stem of an ear-fitting headphone. The ear-fitting headphone is configured to be positioned against an ear canal of an ear. The system also includes a brace assembly coupled to the attachment assembly and configured to restrain the ear-fitting headphone against the ear canal by creating compression forces. The compression forces include a first compression force between the ear-fitting headphone and the ear canal. The compression forces further include a second compression force between a concha of the ear and the brace assembly. A first side of the brace assembly is configured to be positioned on a portion of the concha, and the attachment assembly is operable to transmit the first compression force and the second compression force between the brace assembly and the ear-fitting headphone.

Abstract: Provided is an assembling method for a micro-loudspeaker assembly. The method comprises the steps of: (a) preparing a chuck ring material plate and a vibrating diaphragm material plate, and stamping a number of chuck ring inner holes in the chuck ring material plate; (b) coating an adhesive on the upper surface of the chuck ring material plate stamped with the chuck ring inner holes; (c) bonding the vibrating diaphragm material plate to the upper surface of the chuck ring material plate coated with an adhesive; (d) downwards stamping the part of the vibrating diaphragm material plate corresponding to the chuck ring inner holes into the central part of a vibrating diaphragm; and (e) stamping to form the outer edge of the assembly around the chuck ring inner holes, and removing the assembly from the material plate.

Abstract: A flat panel speaker system is provided. The system includes, a modified panel having a front surface and a rear surface, wherein the modified panel acts as a diaphragm for the flat panel speaker system; a supporting member coupled to the rear surface of the modified panel; and a detachable driver operationally coupled to the supporting member.

Abstract: An energy converter includes a permanent magnet and a diaphragm. The permanent magnet is fixed to a predetermined area. The diaphragm is disposed on the permanent magnet and has a coil formed of a conductor pattern.

Abstract: Disclosed herein, among other things, are systems and methods for improved circuit design for hearing assistance devices. One aspect of the present subject matter includes a hearing assistance device configured to compensate for hearing losses of a user. The hearing assistance device includes a flexible circuit substrate and an integrated circuit die embedded within the flexible circuit substrate. The integrated circuit die includes a digital signal processor (DSP) die, in an embodiment. In various embodiments, the DSP die includes a DSP configured to provide processing for the hearing assistance device.

Abstract: A system and methods for providing a wireless earplug system are described. An earplug includes a wireless receiver/transmitter, a battery, a speaker, a sound canal and an on/off switch. The system also includes a controller including a wireless receiver/transmitter used to transmit wireless signals to the earplug. The earplug receives the wireless signals from the controller and plays audio sounds through the speaker and into the user's ear canal, thus enabling the user to hear the transmitted audio signals while ambient noises are blocked. The controller is also used to control the parameters of the time, duration and type of audio sounds.

Abstract: A probe capable of reducing positional displacement of an acoustic lens from a capacitive transducer is provided. The probe includes a transducer having elements and extraction electrodes of the elements, flexible wiring boards having wiring electrically connected to the extraction electrodes, and an acoustic lens having stepped portions which is provided on the elements. The acoustic lens is butted against end portions of the flexible wiring boards at the stepped portions and fixed.

Abstract: Disclosed is an ultrasonic probe comprising: CMUT cells (13) that mutually convert ultrasonic waves and electrical signals; a semiconductor substrate (15) that has a plurality of the CMUT cells (13) formed on the surface thereof; an acoustic lens (3) that is provided on the front face side of the CMUT cells (13); and a backing layer (5) that is provided on the rear face side of the semiconductor substrate (15). The backing layer (5) is formed by a first backing layer (27) that makes contact with the semiconductor substrate, and a second backing layer (29) that is provided on the rear face side of the backing layer (27). The acoustic impedance of the backing layer (27) is set based on the sheet thickness of the semiconductor substrate (15). The backing layer (29) is formed by attenuating material capable of attenuating ultrasonic waves transmitted through the backing layer (27).

Abstract: Micro-Electro-Mechanical System (MEMS) structures, methods of manufacture and design structures are provided. The method of forming a MEMS structure includes forming a wiring layer on a substrate comprising actuator electrodes and a contact electrode. The method further includes forming a MEMS beam above the wiring layer. The method further includes forming at least one spring attached to at least one end of the MEMS beam. The method further includes forming an array of mini-bumps between the wiring layer and the MEMS beam.

Abstract: A method for manufacturing a composite piezoelectric substrate in which a piezoelectric substrate and a supporting substrate are prepared, ions are implanted in the piezoelectric substrate to form a defective layer at a predetermined depth in the piezoelectric substrate, impurities that are adhered to a surface of the piezoelectric substrate or a surface of the supporting substrate are removed to expose the constituent atoms thereof and to activate the surfaces, the supporting substrate is bonded to the piezoelectric substrate to form a bonded substrate body, the bonded substrate body is separated at the defective layer so that a separation layer between the surface of the piezoelectric substrate and the defective layer is separated from the piezoelectric substrate and bonded to the supporting substrate to form a composite piezoelectric substrate, and the surface of the separation layer of the composite piezoelectric substrate is smoothed.

Abstract: An electromagnetic vibration device includes a vibration plate device, a voice coil assembly, a magnetic loop system, and a peripheral basin frame. One end of the peripheral basin frame is coupled to the vibration plate device, and the other end thereof is coupled to the magnetic lop system. The peripheral basin frame includes a plurality of connecting frames, wherein every two connecting frames are connected by a connecting member to form an integral peripheral basin frame. The size of the peripheral basin frame is adjusted by the distance between the connection frames or relative increase of the number of the connection frames, so that the size of the peripheral basin frame is adjustable to match with the vibration plate device of the electromagnetic vibration device. Only a mold is required to manufacture the connecting frame to form the peripheral basin frame for different sizes of electromagnetic vibration device.

Abstract: A method of manufacturing a sensor network is described which includes stretching a silicon substrate over a desired area, and generating a plurality of nodes fabricated on the stretchable silicon substrate. The nodes include at least one of an energy harvesting and storage element, a communication device, a sensing device, and a processor. The nodes are interconnected via interconnecting conductors formed in the substrate.

Abstract: The invention relates to a voice coil support (21) for a coil transducer motor structure (10) having a first surface (26) towards one end and a second surface (22) towards the other end along an axis of displacement Z, the voice coil support being adapted to receive at least one coil (22H, 22L) wound therearound an outer surface (27) arranged in use for displacing the voice coil support (21) along its axis of displacement Z, as a current is driven through the coils (22H, 22L) when the voice coil support (21) is placed in a magnetic field, characterized in that the voice coil support (21) comprises a material adapted to prevent airflow communication between at least the first surface (26) and the second surface (22).

Abstract: A method for manufacturing a switching element which has enough resistance to repeat switching operations and which can be miniaturized and have low power consumption, and a display device including the switching element are provided. The switching element includes a first electrode to which a constant potential is applied, a second electrode adjacent to the first electrode, and a third electrode over the first electrode with a spacer layer formed of a piezoelectric material interposed therebetween and provided across the second electrode such that there is a gap between the second electrode and the third electrode. A potential which is different from or approximately the same as a potential of the first electrode is applied to the third electrode to expand and contract the spacer layer, so that a contact state or a noncontact state between the second electrode and the third electrode can be selected.

Abstract: Techniques described herein generally relate to generating an audio signal with a speaker. In some examples, a speaker device is described that includes a membrane and a shutter. The membrane can be configured to oscillate along a first directional path and at a first frequency effective to generate an ultrasonic acoustic signal. The shutter can be positioned about the membrane and configured to modulate the ultrasonic acoustic signal such that an audio signal can be generated.

Abstract: An ultrasonic probe that can be relatively easily manufactured and has a desired ultrasonic radiation surface. The ultrasonic probe includes: plural supporting materials, each having a principal surface on which plural signal wires are formed, the plural supporting materials arranged such that the principal surfaces are oriented in different directions from one another; plural groups of ultrasonic transducers, plural ultrasonic transducers in each group having plural electrodes formed on side surfaces, the plural electrodes respectively joined to the plural signal wires formed on the principal surface of the respective one of the plural supporting materials.

Abstract: An interactive card or the like employs a piezoelectric charge generator (piezo-strip) for temporarily driving an indicator. The piezo-strip may be displaced (bent) in order to generate charge to drive the indicator. Printed electronic processes are utilized to produce the indicator and/or the piezoelectric charge generator. An indicator is formed on a substrate by way of a printed electronics process. A displaceable region of piezoelectric material associated with the said substrate is formed by way of a printed electronics process. Electrical interconnections are formed on said substrate by way of a printed electronics process. The electrical interconnections connecting said indicator and said first region of piezoelectric material such that displacement of said first region of piezoelectric material generates a voltage therein that is provided to said indicator in order to actuate said indicator and thereby indicate the displacement of said first region of piezoelectric material.

Abstract: An ultrasonic probe configured to be connected to an apparatus main body of an ultrasonic diagnostic apparatus that is configured to perform an ultrasonic procedure on a subject is provided. The ultrasonic probe includes a transducer configured to transmit an ultrasonic wave to the subject and receive an ultrasonic echo reflected from the subject, an inductor connected in parallel with the transducer, and a current limiter connected to the inductor and configured to limit a current flowing through the inductor to a predetermined current level or lower.