Abstract: An electroacoustic transducer 400 is described. The electroacoustic transducer 400 comprises an active element 410. The electroacoustic transducer 400 comprises an acoustic coupling layer 430 arranged to acoustically couple, in use, the active element 410 to a transmission medium. The electroacoustic transducer 400 further comprises a cavity 420 arranged between the active element 410 and the acoustic coupling layer 430 to receive a fluid. In this way, acoustic coupling of the electroacoustic transducer 400 and the transmission medium is improved.

Abstract: An acoustic vector sensor (“AVS”) includes one or more sensitive elements arranged in an orthogonal configuration to provide high-sensitivity directional performance. The one more sensitive elements may be seismometers arranged in a pendulum-type configuration. The AVS further includes a hydrophone.

Abstract: A compact omnidirectional antenna for dipping sonar comprises multiple elementary transmission rings formed around a longitudinal axis of the antenna and multiple hydrophones distributed around the longitudinal axis, the antenna intended to be dipped in water, the hydrophones separate from the elementary transmission rings, the hydrophones and the elementary transmission rings fixed in the antenna. The elementary transmission rings and the hydrophones are interlinked along one and the same height (H) measured along the longitudinal axis.

Abstract: An in-well type acoustic telemetry system includes an elongate tubular housing, an elongate transmitter in the tubular housing, and a receiver in the tubular housing. The transmitter is adapted to generate an output acoustic signal by linearly fluctuating along a transmitter axis in response to an electrical signal. The receiver is adapted to generate a second electrical signal by linearly fluctuating along a receiver axis that is parallel to or coincides with the transmitter axis.

Abstract: An acoustic transceiver assembly including a housing, an oscillator, and at least one membrane. The housing has at least one inner wall defining a cavity. The housing also has a first end and a second end defining an axis of the acoustic transceiver assembly. The oscillator is provided in the cavity. The oscillator is provided with a transducer element, and a backing mass acoustically coupled to the transducer element. The at least one membrane extends outward from the backing mass to support at least the backing mass within the cavity. The at least one membrane is flexible in an axial direction parallel to the axis of the acoustic transceiver assembly to permit the backing mass to oscillate in the axial direction, and rigid in a transverse direction to restrict lateral movement of the backing mass relative to the housing.

Abstract: A compression assembly (5) forms an airborne sound sensor for detecting sound pressure level. The airborne sound sensor includes a piezo electric transducer (11) compressed against a top element (9) and a lower element (12) so as to compress the transducer (11) across a first face and a distal second sensing face.

Abstract: A device for generating mechanical oscillations is provided. The device has a first mass, a second mass, and a piezoelectric excitation system mechanically coupling the first mass and the second mass to one another, with the piezoelectric excitation system having a stiffness. The piezoelectric excitation system is designed such that its stiffness is settable.

Abstract: A Stoneley wave is generated in a borehole in a saturated porous earth formation. Measurements are made of the velocity of motion of the formation and the fluid in the formation. The difference in the velocities is indicative of formation permeability. An additional measurement of the electric field at the borehole wall enables determination of the electroacoustic constant.

Abstract: An explosion-proof system for generating acoustic energy. An exemplary embodiment of the system includes a main housing defining an open housing space and an opening. A cover structure is configured for removable attachment to the main housing structure to cover the opening and provide an explosion-proof housing structure. The cover structure includes an integral head mass. An acoustic energy emitting assembly includes the head mass, and an excitation assembly disposed within the explosion-proof housing structure. An electronic circuit is disposed within the explosion-proof housing structure to generate a drive signal for driving the excitation assembly to cause the acoustic energy emitting assembly to resonate and generate acoustic energy. In one embodiment the acoustic energy is a beam of ultrasonic energy useful for testing ultrasonic gas detectors. A method is also described for testing ultrasonic gas leak detectors using an ultrasonic source.

Abstract: An acoustic wave transducer includes at least one electroacoustic motor, a horn having an inner wall and an outer wall, a counterweight, and a hollow housing having an inner wall and an outer wall and at least one acoustic opening. The electroacoustic motor is connected to the horn and to the counterweight along an axis, and the electroacoustic motor is capable of exciting the horn at about at least one resonance frequency. The housing is connected to the counterweight and surrounds the motor and the horn, the outer wall of the horn being arranged opposite an acoustic opening of the housing, and the space between the inner wall of the housing and the inner wall of the horn defines a cavity that contains a fluid. The transducer includes acoustic attenuation elements connected to the outer wall of the housing in order to attenuate the emission and/or reception acoustic waves at the frequency at least in a direction transverse to the emission/reception axis.

Abstract: An electro-mechanical transducer is disclosed, which provides a wideband response by activating successive multiple resonant frequencies in a way which provides additive output between the resonant frequencies with reduced cancellation below the first resonance and means for controlling the response by reducing the voltage drive. A multiply resonant wideband high output transducer is disclosed.

Abstract: An apparatus for producing a holding or transmission frame (12, 20) for an electrostrictive actuator, in particular, a stacked piezoactuator (5) includes the following steps: a) a winding spindle (52), corresponding to the shape of the inner periphery of the frame (12, 20), is wound with several layers of a unidirectional prepreg for forming a laminate body; b) the laminate body is hardened; c) the hardened laminate body in the frame is cut by sections parallel to the direction of winding. An electrostrictive drive (100) includes an electrostrictive actuator (5) in which the length varies during actuation, and a transmission frame (12) that surrounds the actuator, is connected to the actuator for initiating the variation in length of the actuator and for amplifying the actuator, the transmission frame (12) being made of a prepreg that is wound in the laminate body and hardened.

Abstract: An embodiment of the invention is directed to a hybrid geometry type acoustic transducer. A hybrid geometry type acoustic transducer as embodied herein leverages different type transducer physical configurations. More specifically, embodiments of the hybrid transducer combine specific features of traditional Tonpilz resonators and PZT-composite transducers to exploit the beneficial characteristics of both. The outward construction of an embodied hybrid transducer mimics a Tonpilz resonator incorporating a headmass and a tailmass sandwiching a piezoelectric active material. However, rather than using a conventional ceramic ring stack or plate form of active material, a layer of diced or “pillared” active material is provided between the headmass and the tailmass with no filler material other than a gas, such as air, for example, or others, or a vacuum environment.

Abstract: A sonar transducer has a head mass at a distal end thereof, a tail mass at a proximal end thereof, a driver in physical contact with the head mass and the tail mass, and a flextensional body incorporating and extending proximally from the head mass. The flextensional body has relatively thin walls or diaphragms with concave surfaces. The sonar transducer may have a fundamental mode having a relatively low resonant frequency, involving substantially only a bending motion of the diaphragms. A second resonant mode, at a frequency higher than the frequency associated with the fundamental mode, involves both a bending motion of the diaphragms and a membrane or breathing motion of the flextensional body, including the head mass. A third, relatively high frequency resonant mode, involves exclusively or substantially exclusively longitudinal motion of the head mass.

Abstract: A Tonpilz transducer which includes a first stack of piezoceramic elements with a first plurality of electrodes connected to form a first pair of external connections. There is also a second stack of piezoceramic elements with a second plurality of electrodes connected to form a second pair of external connections, and the first and second stacks of piezoceramic elements have opposed polarizations.

Abstract: An electromechanical device for generating elastic waves in a material medium such as the subsoil in a frequency range where the wavelengths of the waves generated are great in view of the dimensions of the device, and method of implementation. The device comprises one or more vibrators which are buried in the medium, associated with a control system. Each vibrator comprises at least one inertia mass (1), several plates (2, 3) providing mechanical coupling with the medium, electromechanical transducers (4, 5) connecting inertia masses (1) to plates (2, 3). A control system (7) applies to the various transducers (4, 5) respective control signals so that the resulting elastic wavefield generated in the medium by the device is preferentially oriented in one or more directions.

Abstract: An electro-mechanical transducer is disclosed, which provides a wideband response by activating successive multiple resonant frequencies in a way which provides additive output between the resonant frequencies. A three mode wideband high output transducer is also disclosed along with an electro-mechanical feedback system which provides a smoothed response as well as array control under multiple element usage.

Abstract: An electro-mechanical transducer is disclosed, which provides a wideband response by activating successive multiple resonant frequencies in a way which provides additive output between the resonant frequencies. A three mode wideband high output transducer is also disclosed along with an electro-mechanical feedback system which provides a smoothed response as well as array control under multiple element usage.

Abstract: A longitudinal vibrator assembly comprising at least one piezoceramic, magnetostrictive or electrostrictive transducer (130) having a coaxial housing (200a, 200b or 200c) comprised of at least one slotted or complete cylindrical flexural member vibrating in a circumferential or radial direction and excited by a solid state transduction material.

Abstract: A longitudinal vibrator assembly comprising at least one piezoceramic, magnetostrictive or electrostrictive transducer (130) having a coaxial housing (200a, 200b or 200c) comprised of at least one slotted or complete cylindrical flexural member vibrating in a circumferential or radial direction and excited by a solid state transduction material.

Abstract: An electro-mechanical transducer, which provides amplified piston motion from an orthogonal drive direction wherein the electro-mechanical drive additionally provides the inertial reactive mass for the moving mass of the piston. The piston motion is amplified by lever arms, which are typically attached to a piezoelectric or electrostrictive drive system. The arrangement allows a compact, high output transducer design.

Abstract: The present invention generally provides an apparatus and method for improving the process of purging a liquid delivery system used in integrated circuit manufacturing. The liquid delivery system comprises ultrasonic transducers mounted to various components of a liquid delivery system. The transducers may be mounted on housings, isolation valves, fuel injectors, pump assemblies, fluid lines, and/or liquid flow meters. The ultrasonic transducers launch ultrasonic energy that enhance the removal of processing liquids and particulate material from components of the system. The present invention provides for a purge process where a purge fluid, preferably a liquid solvent, is flowed into the liquid delivery system and ultrasonic energy is launched into the purge fluid to enhance dissolution of residual processing liquids and particulate matter in the liquid delivery system, including from cracks and crevices in valves and other complex mechanical devices before being pumped from the liquid delivery system.

Abstract: A generally cylindrical hydrophone configuration provides compensation for longitudinal accelerations by placing four identical solid piezoelectric transducer elements along its axis with each transducer element being bonded to a head member, two of which are located generally centrally of the cylindrical housing and fastened thereto and two of which are located near the outside edges of the housing and having slight clearance therewith. Flexible polyurethane boots are clamped to the ends of the housing. The volumes between the centrally disposed and outer transducer head members and between the outer head members and the boots are filled with methyl silicon fluid. Each head member is electrically connected to one side of the electrical output, and the junction between the transducer members is connected to the opposite side, both sides being wired to an electrical contact plate located between the two centrally disposed transducer head members, this volume being filled with electrical potting material.

Abstract: There is provided an acoustic source especially for use in seismic studies at sea. The acoustic source has a longitudinal axis and sound emitting surfaces adapted to be put into sound emitting movements towards and away from each other by use of a drive unit. The sound emitting surfaces comprise two curved plate members having upper and lower ends essentially symmetrically positioned in relation to the longitudinal axis of the acoustic source, and forming a convex cross section with their respective upper and lower edges converging towards each other. The upper and lower edges of the sound emitting surfaces, respectively, are connected to each other with two corresponding side elements, the side elements each being connected to at least one hinge stretching along at least a part of the length of the source.

Abstract: Acoustic source, especially for use in seismic studies at sea, with sound emitting surfaces adapted to be put into sound emitting movements toward and away from each other by use of a drive unit in a known manner, in which the sound emitting surfaces comprise two curved plate members essentially symmetrically positioned in relation to the longitudinal axis of the source, forming a convex cross section with their respective upper and lower edges converging towards each other, and the respective upper and lower edges of the sound emitting surfaces are flexibly connected to two corresponding side elements positioned between them, and that the source comprises a rigid frame for supporting the drive unit, comprising at least two rigid slide rods stretching through the side elements, and that rigid covers are mounted on the slide rods, covering at least the whole side elements, thus forming rigid, covering surfaces with a constant distance between the covers.

Abstract: The invention relates to the field of sonar antennas, in particular those intended to be installed on an underwater vehicle in order to constitute a mounted head of the vehicle. Specifically, the invention relates to a sonar antenna having at least two identical transducers that exhibit sensitivity peaks at at least two frequencies .nu., and .nu..sub.2, wherein the head mass dimension of the transducers is between 0.35 and 0.65 times the wavelength .lambda..sub.2 corresponding to the higher of the frequencies .nu..sub.1 and .nu..sub.2.

Abstract: A state switched acoustic has a stiffness element having a zero potential energy state and a plurality of controllable stiffness states. A mass is coupled to the stiffness element so that the stiffness element and the mass are capable of resonating at a resonant frequency. A system changes the stiffness state of the stiffness element from a first stiffness state to a second stiffness state while the mass is in motion and stiffness element is in a zero potential energy state so as to change the resonant frequency of the transducer. In a method of changing resonant frequency of a mechanical system, a parameter of the system is dynamically changed while the system is in an energy state that will allow changing the resonance parameter without disrupting the resonance of the system.

Abstract: A sonar array uses multiple acoustically transparent layers. One layer is a lanar array of acoustic sensors that is substantially acoustically transparent. Another layer is an acoustically transparent wiring assembly that provides electrical connection to each acoustic sensor. A third acoustically transparent layer is a planar array of signal processing circuits coupled to the wiring assembly for processing electrical signals generated by the acoustic sensors. Each signal processing circuit resides within an area that is in geometric correspondence with a respective one acoustic sensor. Each signal processing circuit can include a preamplifier, an analog-to-digital converter and a digital multiplexer.

Abstract: The invention relates to a piezoelectric transducer particularly for use in transit time measurements. The object of the invention is to provide a piezoelectric transducer which ensures an in-phase two-dimensional pulse emission which, independent of the selection of a definite excitation frequency, substantially closely follows the electric excitation at a low time deformation of the pulse owing to transient and dying-out operations and which permits to obtain sufficiently high sound levels at low amplitudes of the excitation voltage.

Abstract: A sonar transducer displaying improved reliability and operating characteristics by employing multiple ceramic stacks, novel support structure and an improved gaseous environment.

Abstract: This invention relates to an ultrasonic generator apparatus for generating and transmitting enhanced ultrasonic wave energy of a predetermined frequency to a liquid confined in a container which contains a resonance enhancing disc. Such electroacoustic transducer apparatus or generators are utilized in ultrasonic cleaning equipment. The apparatus are mounted to the side or the underside of the liquid container or mounted in a sealed enclosure which is immersed in a liquid in a container made of metal, plastic or glass. Generators are used in single or plurality of to energize the liquid with sonic energy which in turn transformed into cavitations. In the present invention, the insertion of a resonance enhancing disc between the base of the generator and the piezo electric material provides an increase in intensity of the resonant frequency signals, diminishing periodical shift in frequency and stabilizing piezo electric material temperature.

Abstract: An electroacoustic transducer, which has a lead frame previously formed into a predetermined shape, an outer case formed integrally with the lead frame and a drive section including a coil arranged inside the outer case, comprises an opening formed in the outer case; lands formed by exposing a part of the lead frame through an outer surface of the outer case; and the coil having coil terminals led out of the outer case through the opening and connected to the lands.

Abstract: A sound or ultrasound sensor is provided for transmitting and/or receiving sound or ultrasound, which is mechanically robust and chemically resistant and which has an adjustable emission characteristic, for example having a preferably small beam angle, having an emitting element (3) which has a flat front surface (34), and having a transducer element (1), the transducer element (1) causing the front surface (34) to oscillate on the basis of an excitation frequency, such that the entire front surface (34) carries out virtually in-phase deflections with virtually equal amplitude parallel to the normal to the front surface (34), and in which sensor concentric webs (32) are arranged on the front surface, there being a concentric gap (33) in each case between two adjacent webs (32), and a disk (5) sealing the sound or ultrasound sensor flush at the front, which disk is firmly connected to the webs (32) and has segments which are not connected to the webs (32) and are used as membranes (51).

Abstract: The invention is directed to the class of submersible electro-acoustic transducers such as double "Tonpilz" transducers, wherein it is desirable to reduce the resonant frequency of the transducers while maintaining a given output power emitted by the transducers. The transducer according to the invention includes at least one horn solid with the end of a motor pillar, a hollow rigid box surrounding the horn and delimiting with the horn a cavity. The cavity communicates via a port with an external fluid, and has determined dimensions and external volume. The transducer further includes a passive radiator made of a material denser than the external fluid. The radiator obturates the port and hangs at a periphery of the port by an elastic material.

Abstract: The invention relates to directional electro-acoustic transducers compris a sealed shell consisting of two portions.A transducer according to the invention comprises one or more electro-acoustic drivers (1) composed for example of a stack of piezoelectric plates (1a, 1b, . . . 1n) located inside a sealed shell. This shell comprises a first portion (3A) symmetrical as to a plane (PP') fitted with two flanges at its ends, these flanges being coupled mechanically and acoustically by means of a rod (7) and two bolts (8) With each driver (1). The shell includes a second portion (3b) which is complementary to the first portion and which is acoustically uncoupled from the first portion and from the drivers.An application of the invention is the construction of low-frequency transmitter of acoustic waves in the water in a given direction.

Abstract: The invention relates to a dual frequency sonar transducer assembly which may be operated at low and/or high frequencies in a sonar array. The assembly comprises a low frequency unit of tonpilz design including a low frequency driver, a low frequency tail mass and a composite head mass, the composite head mass acting as a single low frequency water driving piston and comprising a plurality of high frequency units forming individual high frequency water driving pistons. The high frequency units are also of tonpilz design, with independent drivers, independent head masses, and a common tail mass. The use of a common tail mass simplifies the design without compromising high frequency operation. The design leads to more efficient operation at both frequencies by minimizing the head mass to tail mass ratios.

Abstract: The invention relates to electro-acoustic transducers comprising a flexible nd sealed transmitting shell referred to as flextensional transducers. A transducer according to the invention comprises one or more electro-acoustic drivers, e.g., a stack of piezoelectric plates 1a, 1b . . . 1n, located inside a flexible and sealed shell. Each piezo-electric driver comprises, at both its ends, a counter-mass coupled mechanically and acoustically with the stack and the ends of the shell by means of an axial threaded rod and two nuts screwed on the ends of the rod. The mass of the two counter-masses and the dimensions of the stack are determined so that the fundamental frequency of the axial oscillations of this mechanical assembly will be close to the natural frequency of the bending oscillations of the shell. An application of the invention is the construction of sonar transmitters.

Abstract: An underwater sonar projector includes a one piece hollow shell of elliptical cross section having a number of transducer stacks positioned within the shell and compressively prestressed by the shell to vibrate along the major axis thereof which causes the broad surfaces between the small radius ends to vibrate in and out. To resist large external shocks the shell is made somewhat heavier than usual, a center support member or beam is placed along the minor axis of the shell and an adjustable support rod is carried in the beam which is adjusted to a length just sufficient to clear the vibrating surfaces of the projector in normal operation but which functions to limit the inward movement of the shell if exposed to an explosion. The transducer stacks include a number of columns of piezoelectric disks on each side of the support beam which are bonded together, each stack having a tail member fastened to said center support beam and a head member between the disks and the end of the shell.

Abstract: A vibration isolator for a torpedo transducer, comprising a unitary metallic member having an axis, a central aperture extending axially to receive the transducer, a first plurality of pairs of transverse slots extending into the member in opposite directions to terminate short of the center of the member, and a second plurality of pairs of transverse slots extending into the member in opposite directions orthogonal to the first named directions, to terminate short of the center of the member, the pairs being spaced axially and alternately along the member.

Abstract: A transducer includes at least one cylindrical driving assembly and at least one headmass coupled to an end of the cylindrical driving assembly. The headmass has an external ring that surrounds a core. The core is made from a core material that is less dense than the material from which the external ring is made. The headmass is dimensioned to occupy a predetermined volume so as to transmit waves within a predetermined frequency range. As a result, the transducer provides higher power waves, yet occupies the same volume as the transducers of the prior art.

Abstract: An ultrasonic transducer employed for both transmitting ultrasonic acoustic energy into an immersion medium and for detecting acoustic energy reflected from an object under examination is provided, the transducer having a hybrid transmitter and receiver in which a ceramic piezoelectric material is used to construct a first piezoelectric element for transmitting the acoustic energy, and a polymer piezoelectric material is used to fabricate a second piezoelectric element for receiving the reflected acoustic energy. The hybrid ultrasonic transducer provides improved performance over prior transducers using only a single ceramic piezoelectric element, in that the good transmitting properties of the ceramic are preserved, while the better receiving properties of the polymer piezoelectric are used to improve the sensitivity of the transducer. The polymer piezoelectric has the further advantage of providing a closer match of acoustic impedance to the immersion fluid used in the evaluation of objects.

Abstract: A dual frequency, polymer hydrophone, array for a submersible vehicle is closed. A mid-frequency transducer array is employed in the forward end of a submersible vehicle. Between the mid-frequency array and a nose portion of the submersible vehicle is a single or multiple board piezoelectric polymer array employed to implement a secondary, high-frequency transducer array. Amplifying and signal conditioning units are mounted adjacent or on one metallic electrode layer or formed integrally thereon to minimize signal lead loss. The piezoelectric polymer material is chosen to have a density coefficient and sound velocity substantially equivalent to an acoustic window in the nose portion of the submersible vehicle and to be substantially transparent to the mid-frequency array. Minimal degradation of the mid-frequency received or transmitted signals occurs due to the transparency of the high-frequency array.

Abstract: The invention relates to processes and electro-acoustic transducers for transmitting low-frequency acoustic waves in a liquid. An electro-acoustic transducer according to the invention is a transducer of the double-tonpilz type, comprising two electro-acoustic drivers (1a, 1b) in line on both sides with a central counter-mass (2) and between two horns (3a, 3b). This mechanical assembly is located in a rigid box (4) which is fitted with side holes (5) and which delimits a cavity (7) housing elastic tubes (6) closed at their both ends and filled with gas so that the Helmholtz resonant frequency of the cavity (7) is close and preferably lower than the fundamental frequency of the axial vibrations of the vibrating assembly. An application of the invention is the construction of low-frequency transmitting transducers of the double-tonpilz type with a wide pass-band.

Abstract: A low frequency torsional transducer for the generation and/or reception of shear waves in a substantially solid medium. The transducer includes a spool like radiating structure to which are fixedly attached spaced piezoelectric elements. The elements undergo shear movement upon being electrically excited or upon receiving shear waves. This shear movement causes the opposite ends of the radiating structure to move torsionally. The torsional movement causes radiation of shear waves which can be detected by a sensor and used to determine the degree of support for shear wave propagation in the media.

Abstract: New electroacoustic unit for efficient generation of high sonic and ultrasonic intensities in gas media and in interphases (gas-solid, gas-liquid.) Said unit is comprised of an electromechanical transducer system of which the radiating element is a plate (3) having a discontinuous profile and an electronic device for the controlled generation of the electric power signal. The unit is capable of generating acoustic fields of very high intensity with a predetermined configuration. Particularly it is capable of generating with a same transducer system two distinct configurations of the acoustic field. Prototypes for generating directional and focused fields have been developed.

Abstract: A sonar transducer includes an electro-mechanical transducer coupled to a front mass and a back mass. Annular rings space a compliant diaphragm from the front mass, the diaphragm being in communication with the liquid to which the sonar transducer is exposed. The compliance of the diaphragm is selected to tune the sonar transducer to eliminate reactive components of the impedance of the combined sonar transducer and liquid medium load, and to maximize the radiation resistance of the system.

Abstract: A solid-state tunable transducer has been developed by incorporating an elastically nonlinear material, silicone rubber, into an electroacoustic transducer made from piezoelectric ceramics. The resonant frequency and mechanical Q of the transducer are tuned mechanically by applying a uniaxial compressive stress to the composite. The resonant frequency is tuned electrically by placing a piezoelectric actuator into the composite and varying the magnitude of the d.c. bias.

Abstract: A transducer for use in surface ship applications includes a prestress element for providing additional compressive force to an electromechanical driver disposed within the transducer. The transducer includes a shell having inner portions, an electromechanical driver having end portions coupled to inner portions of the shell, and a block prestress element disposed between one of the end portions of the driver and the inner portions of the shell. The block prestress element is fabricated from a shape memory alloy which can be deformed within a first temperature range and reverts back to its original shape when exposed to a temperature above the first temperature range. This characteristic provides for the generation of additional stresses which may be desired for providing protection to the electromechanical driver from unwanted tensile forces.

Abstract: A seismic source for downhole use is disclosed which is formed by an outer tubular member having weighted ends which carries within a coaxially mounted tubularly shaped piezoelectric element. The piezoelectric element is cyclically driven to produce a standing wave having a frequency in the range of 0.25 to 5 kHz and a narrow bandwidth in the range of 5-50 Hz.

Abstract: An electroacoustic transducer, which has a lead frame previously formed into a predetermined shape, an outer case formed integrally with the lead frame and a drive section including a coil arranged inside the outer case, comprises an opening formed in the outer case; lands formed by exposing a part of the lead frame through an outer surface of the outer case; and the coil having coil terminals led out of the outer case through the opening and connected to the lands.