Abstract: An acceleration sensor includes a piezoelectric element and support frames for supporting the ends of the piezoelectric element in the longitudinal direction. The piezoelectric element is formed by stacking an even number of piezoelectric layers greater than or equal to four layers. Electrodes are provided in between the layers and on the front and back faces of the piezoelectric element. The interlayer electrodes including a segmented electrode and lead electrodes are alternately stacked with the piezoelectric layers therebetween. The interlayer electrode in the middle in the thickness direction is a segmented electrode. The piezoelectric layers are polarized in the thickness direction so that charge having the same polarity is extracted from the electrodes when the acceleration is applied. Also, the center portion and both end portions of each piezoelectric layer are polarized in opposite directions.

Abstract: An acceleration sensor includes a piezoelectric element and support frames for supporting the ends of the piezoelectric element in the longitudinal direction. The piezoelectric element is formed by stacking an even number of piezoelectric layers greater than or equal to four layers. Electrodes are provided in between the layers and on the front and back faces of the piezoelectric element. The interlayer electrodes including a segmented electrode and lead electrodes are alternately stacked with the piezoelectric layers therebetween. The interlayer electrode in the middle in the thickness direction is a segmented electrode. The piezoelectric layers are polarized in the thickness direction so that charge having the same polarity is extracted from the electrodes when the acceleration is applied. Also, the center portion and both end portions of each piezoelectric layer are polarized in opposite directions.

Abstract: The present invention provides a solid-state acceleration sensor device formed by thin films for generating an electrical voltage output proportional to acceleration motion. The precision thin-film piezoelectric elements are configured and arranged on a semi-rigid structure to detect acceleration while rejecting spurious noise created by package strain, thermal gradients, and electromagnetic interference.

Abstract: The seismic mass (4) of an accelerometer that comprises at least one electromechanical transducer is stabilized in the direction perpendicular to the sensible axis by at least one laterally stabilizing element (8) arranged between the electromechanical transducer (9) and a structural element (7). This stabilization eliminates or at least drastically reduces any distortions of the measurement results provoked by transversal accelerations.

Abstract: A beam-type sensor capable of measuring displacement or acceleration includes a thin, flexible sheet of piezoresponsive material defining broad sides and a proximal end. In order to optimize boundary conditions, the proximal end of the sheet is supported by a clamp that provides a “clean” transition between support and no-support. Electrical connections to conductors associated with the broad sides are integrated into the clamp. In one embodiment, two sheets of piezoelectric material are connected electrically in parallel. In another embodiment, two sheets of piezoelectric material are connected electrically in series.

Abstract: The present invention comprises a microelectromechanical positioner to achieve substantially translational positioning of a platform without rotational motion, thereby maintaining a constant angular orientation of the platform during movement. A linkage mechanism of the positioner can comprise parallelogram linkages to constrain the rotational motion of the platform. Such linkages further can comprise flexural hinges or other turning joints at the linkage pivots to eliminate the need for rubbing surfaces. A plurality of the linkage mechanisms can be used to enable translational motion of the platform with two degrees of freedom. A variety of means can be used to actuate the positioner. Independent actuation of the anchor links of the linkage mechanisms with rotary electrostatic actuators can be used to provide controlled translational movement of the platform.

Abstract: A transducer for emitting and picking up mechanical vibrations includes a center body (4) suspended in a piezo-electric and elastic suspension structure (3) in a surrounding framework (2). The suspension structure (3) is formed in sectors, and has separate signal wires for each respective sector (5) so that vibrations can be emitted and received at the same time with different sectors (5). In addition, the center body (4) can be equipped with piezo-elements of its own.

Abstract: The present invention provides a sensor that can be operated at high temperatures. The sensor comprises a first electrode, a second electrode, and an aluminum nitride film which lies between the first and second electrode. The sensor can be used to measure pressure, acceleration, or force at high temperatures.

Abstract: A vibrating gyroscope includes: a vibrator having an driving electrode and two detecting electrodes; a first drive circuit for applying a first drive signal to the driving electrode; a second drive circuit for applying a second drive signal having an inverted phase of the drive signal, or an inverted phase of a detection signal detected from the two detecting electrodes, to the detecting electrodes; and a detection circuit for detecting the detected signal in correspondence with the rotational angular velocity from the two detecting electrodes.

Abstract: An integral bimorph angular rate sensor is formed by directly bonding two tuning fork members in the thickness direction to enhance the detecting sensitivity of the angular velocity sensor. The individual tuning fork members are formed from a single crystalline piezoelectric material such as quartz and are bonded in the crystal axis direction as to establish a piezoelectric phenomenon wherein the piezoelectric materials of the bonded tuning fork members have inverse polarities in their width or thickness directions.

Abstract: An acceleration sensor having a well controlled dispersion in the detection characteristics and improved detection characteristics in the low frequency detection comprises a first piezoelectric plate (11), a second piezoelectric plate (12) bonded to the first piezoelectric plate (11) by direct bonding, a first external electrode (13) provided on the main surface of the first piezoelectric plate (11) and a second external electrode (14) provided on the main surface of the second piezoelectric plate (12). The first piezoelectric plate (11) and the second piezoelectric plate (12) are bonded together with their polarization axes reversed to each other. Appearance of the acceleration sensor resembles to a letter “L” in the cross section; thickness of the supporting section (15) is greater than that of the rest part (free vibration section).

Abstract: A gyroscope comprising: a proof mass; a frame supporting the proof mass; a connection arrangement connecting the proof mass and the frame, the connection arrangement having a first stiffness in a first direction and a second stiffness in a second direction substantially perpendicular to the first direction, one of the stiffness being significantly greater than the other stiffness; and a pair of elements adapted to sense relatively motion therebetween in either the first or the second direction.

Abstract: A piezoelectric generator comprises a centrifugal force sampling mechanism being carried around a central axis. The direction of the centrifugal forces, do to rotational control, acting on the sampling mechanism is reversed periodically to alternately apply and relieve distortion on two adjacent piezoelectric elements. The slug shaped piezoelectric elements produce high voltage charges while undergoing little change in shape or length in response to high-energy impulses.

Abstract: A vibrating rate gyro structure machined in a plate of material and comprising a fixed part, a resonator, and a mechanical system connecting the resonator to the fixed part. The mechanical system comprises a first mobile mass part connected to one end of the resonator, a second mobile mass part (4) connected to the resonator and situated in the vicinity of the other end of the resonator, two flexible arms situated on both sides of the resonator and each connecting the first mobile mass part to the second mobile mass part, and two other flexible arms situated on both sides of the resonator and connecting the second mobile mass part to the fixed part.

Abstract: A rotational accelerometer using piezoelectric material, preferably quartz, in a shear orientation. Piezoplates and conducting seismic masses, each having bores therethrough, are bolted to posts that are symmetrically mounted to a body in such a manner that the bolt passes through the piezoplates but does not make contact. The accelerometer can be assembled as a single-axis accelerometer by mounting a pair of posts symmetrically about the body along the measured axis; additionally, the accelerometer may be assembled as a double or triple axis accelerometer by symmetrically mounting additional pairs of posts to the body. The total weight of the seismic masses and the crystals of the shear-type accelerometer halves should be equal. The invention sets forth a novel rotational accelerometer that reduces or eliminates the need for signal-processing electronics.

Abstract: A small-sized, high detection sensitivity and high performance acceleration sensor having directional or non-directional sensitivity is disclosed. The acceleration sensor is provided with a vibrator having uni-directional polarization and a weight connected to the vibrator. The weight is supported at the position different from the center of gravity of the total body of the vibrator and the weight itself. The vibrator is disposed so that its direction of polarization axis is either consistent or inconsistent with an axis of the torsion of the vibrator.

Abstract: An acceleration sensor having a well controlled dispersion in the detection, characteristics and improved detection characteristics in the low frequency detection comprises a first piezoelectric plate (11), a second piezoelectric plate (12) bonded to the first piezoelectric plate (11) by direct bonding, a first external electrode (13) provided on the main surface of the first piezoelectric plate (11) and a second external electrode (14) provided on the main surface of the second piezoelectric plate (12). The first piezoelectric plate (11) and the second piezoelectric plate (12) are bonded together with their polarization axes reversed to each other. Appearance of the acceleration sensor resembles to a letter “L” in the cross section; thickness of the supporting section (15) is greater than that of the rest part (free vibration section).

Abstract: An oscillation gyro (1) including a stainless steel base member (4) which is a quadratic prism, wherein the base member (4) has through holes (10, 7) extending in the directions crossing at right angles at the upper and lower portions thereof respectively, and further includes slide plates (8, 9) constituting a parallel plate portion (2) and slide plates (10, 11) constituting a parallel plate portion (3). Preferably, a titanium film (13) is formed by sputtering on each of the outer side surfaces of the parallel plate portions (2, 3), and a thin PZT film (14) is formed on the entire outer surface of the titanium film (13). Pairs of electrode films (15, 16) of aluminum are formed on the respective thin PZT films (14) up and down. The respective electrode films (15, 16) have a thickness of several um and the same area. Pads (15b, 16b) are formed at the lower ends of the base member (4) serving as fixed ends, and are connected to extension portions (15a, 16a) extending from the electrode film (15).

Abstract: An electrically driven signal unit is adapted for one-step assembly or injection molding with a device housing to vibrate, flex, beep or emit audio signals, or to sense and provide tactile feedback or control. The signal unit is a package with one or more active areas each containing a layer of ferroelectric or piezoelectric material, connected by inactive areas which may position, align and conduct electricity to the active areas. The active areas may be coupled over a region to transmit compressional, shear or flexural wave energy into the housing, or may contact at discrete regions while bending or displacing elsewhere to create inertial disturbances or impulses which are coupled to create a tactile vibration of the housing. The unit may be assembled such that the housing, the sheet or discrete areas thereof form a bender to provide tactile or sub-auditory signals to the user, or may be dimensioned, attached and actuated to produce audio vibration in the combined structure and constitute a speaker.

Abstract: A vibrator of a vibratory gyroscope comprises a main arm having a base part and at least one bending-vibration piece extending from the base part in a direction crossing the longitudinal direction of the base part and a fixing part for fixing one end of the base part, and the base part and the bending-vibration piece are formed so as to extend substantially in a specified plane. Preferably, at the opposite side to one end of the base part, a projection projecting from the bending-vibration piece is provided, or at least a pair of resonant arms resonating with vibration of the base part, said pair of resonant arms projecting from the fixing part are provided. Thanks to this, it has been possible to detect a turning angular rate in a sufficiently high accuracy without providing a projection which has a certain weight and extends from the vibrator toward the axis of turning even in case of arranging the vibrator so that the vibration arm of the vibrator extends perpendicularly to the axis of turning.

Abstract: A curved piezoelectric device is attached to a plate to vibrate the plate. Mass-loading is applied to at least one free end of the piezoelectric device to increase output.

Abstract: A wing type ultrasonic transducer is free from a reduction in the output power and has one ultrasonic generator. This ultrasonic generator has piezoelectric ceramic materials with two countermasses respectively coupled to the outside ends of the piezoelectric ceramic materials. A rod-like resonator is coaxially coupled to the outside end of each of the countermasses and is used to emit ultrasonic waves to a liquid in a radial direction. An immersible housing covers the ultrasonic generator so as to accomplish a water tightness of the ultrasonic generator. The rod-like resonator may be a solid resonator or hollow resonator. In addition, the rod-like resonator is integral times as long as a half-wavelength (&lgr;/2) at an operating resonant frequency.

Abstract: An apparatus and method for determining the rate of angular rotation of a moving body and, in particular, for alignment of the dither motion and the Coriolis acceleration sensing direction in a sensor adapted to be formed, i.e. micromachined, from a silicon substrate.

Abstract: A vibrating gyroscope includes two planar vibrating plates arranged to oppose each other. The two vibrating plates vibrate under buckling vibration mode and a second-order bending vibration mode which is degenerated with or close to the buckling vibration mode. The vibrating gyroscope detects Coriolis force by detecting displacements in amplitude balance of the second-order bending vibration modes generated when an angular rotation velocity around an axis parallel to surfaces of the vibrating plates is applied.

Abstract: A sensor including a center post extending along the sensing axis of the sensor, a piezoelectric sensing element concentrically engaging the center post, and a preload element preloading the piezoelectric element radially outward to the axis. The center post includes a recess along the axis and the first preload element is in the recess and preloads the piezoelectric element radially outward. The sensor may include a mass concentrically engaging the piezoelectric element. The sensor senses acceleration, force or pressure.

Abstract: An apparatus and method for determining the rate of angular rotation of a moving body and, in particular, for alignment of the dither motion and the Coriolis acceleration sensing direction in a sensor adapted to be formed, i.e. micromachined, from a silicon substrate.

Abstract: An acceleration sensor has a piezoelectric element which includes a piezoelectric member layer in which a plurality of piezoelectric members are stacked and electrodes which are disposed in major opposed surfaces of the piezoelectric member layer; and a support member for supporting the piezoelectric element, wherein some piezoelectric members of the piezoelectric member layer are polarized. The electrodes are disposed in both surfaces of the polarized piezoelectric members. Capacitors which are formed by the polarized piezoelectric members and the electrodes in both surfaces of the polarized piezoelectric members are connected parallel to each other.

Abstract: The invention relates to a sensor for measuring acceleration and sound pressure, the sensor comprising a first pressure sensitive film (2) for measuring pressure (P) and second pressure sensitive film (5) having a mass (6) disposed thereon for measuring acceleration (A). The films are arranged concentrically in the same plane, so that pressure and acceleration are measured at the same point, thereby avoiding a phase difference between the two measurements.

Abstract: An oscillatory gyroscope having an improved detecting sensitivity. The oscillatory gyroscope includes an elastic metal body in the form of a rectangular column having first to fourth surfaces. The elastic metal body includes a distal portion having a distal through hole extending from the second surface to the fourth surface and a proximal portion having a second through hole extending from the first surface to the third surface. Two first ferroelectric substance films are provided on the first and third surfaces in the distal portion. Two second ferroelectric substance films are provided over the second and fourth surfaces in the proximal portion. First and second electrodes are provided on each of the first ferroelectric substance films, and third and fourth electrodes are provided on the respective second ferroelectric substance films. Voltages of reverse polarities are applied to the first and second electrodes.

Abstract: To suppress dispersion of detection sensitivity due to a change in ambient temperature in a vibration type angular velocity detecting apparatus.

Abstract: A vibrating gyroscope includes a vibrator constructed by bonding a first piezoelectric substrate polarized in the thickness direction and a second piezoelectric substrate polarized in the same direction as the first piezoelectric substrate, through an intermediate electrode. The vibrator includes two first strip electrodes, provided on one main face of the first piezoelectric substrate in the longitudinal direction of the first piezoelectric substrate so as to be spaced from each other, and a second strip electrode provided substantially on the whole of the second strip electrode. The vibrator includes an electrode film formed on the whole of one end-face thereof by a sputtering method.

Abstract: A resonant piezoelectric alerting device (400) includes a motional mass (130) and a piezoelectric actuator (100) which is constrained to an actuator mount (132) at a first end and coupled to the motional mass (130) at a second end, the piezoelectric actuator and the motional mass in combination producing a resonant system having a predetermined frequency of operation. The piezoelectric actuator 9100) is responsive to a control signal (108, 110) generated at the predetermined frequency generates an alternating out-of-plane movement(812, 814) of said motional mass (130) which is transformed into tacile energy to provide a tactile alert about the resonant frequency (608). The out-of-plane movement (812, 814) of the motional mass (130) is also transformed into acoustic energy to provide an audible alert in response to a control signal generated above the predetermined frequency (608).

Abstract: A nondirectional impact sensor capable of detecting impacts in any direction with only a single sensor. The impact sensor includes a board, a sensor for detecting deformation of the board, a mass and a connector. The connector is secured to a central portion of the board and the mass is disposed on a normal line which traverses the central portion of the board.

Abstract: A piezoelectric sensor has a piezoelectric element having a specific axis of sensitivity and a package for the piezoelectric element. The package has a rectangular parrallelopiped configuration with opposite longitudinal end surfaces having a height-to-width ratio of about 1:1. External lead electrodes are formed to cover at least the longitudinal end surfaces. A method and apparatus for detecting if the sensor is disposed in the proper posture is also disclosed.

Abstract: The present invention is a seismic accelerometer to measure and record low frequencies and large dynamic measurement ranges. The accelerometer comprises at least one directional piezoelectric sensing element and an integrated circuit. Each directional piezoelectric sensing element senses inertial forces applied to the accelerometer from a particular direction, X, Y or Z, and generates a force voltage signal in response to the inertial forces applied to the accelerometer. The sensitivity of each directional piezoelectric sensing element is in direct proportion to the sensitivity of the integrated circuit and the mass of a first mass. The integrated circuit system receives the force voltage signal from each directional piezoelectric sensing element and generates an output signal for each direction.

Abstract: A shock sensor sensitive to linear shocks along two axes and to rotational shocks in a given plane and comprised of two piezoelectric sensors and an integrated circuit is disclosed. The first piezoelectric sensor is polarized in a direction that is angularly offset from a plane in which the shock sensor lies and produces a first response to shocks having components along a first and a second orthogonal axis that define a plane perpendicular to the plane in which the shock sensor lies. The second piezoelectric sensor is polarized in a direction that is angularly offset from the plane in which the sensor lies and that is angularly offset 180.degree. from the first direction. The second piezoelectric sensor produces a second response to shocks having components along the first and second orthogonal axis. The integrated circuit is responsive to the first and second responses and produces a signal indicating a linear shock and a signal indicating a rotational shock by combining the first and second responses.

Abstract: A vibrating gyroscope includes a columnar vibrator, a driver and a detector. The columnar vibrator includes first and second piezoelectric substrates polarized in mutually opposite directions along the thickness directions thereof and stacked with each other. Two divided electrodes are formed on one main surface of the first piezoelectric substrate and spaced in the direction perpendicular to the longitudinal direction of the first piezoelectric substrate, and a common electrode is formed on one main surface of the second piezoelectric substrate. The driver drives the vibrator in the thickness direction of the first and second piezoelectric substrates and is connected between the divided electrodes and the common electrode. The detector detects a displacement caused by bending vibration of the vibrator, and is connected to the divided electrodes.

Abstract: An acceleration sensor includes a circuit substrate and an acceleration detection element. The acceleration detection element is mounted on the circuit substrate and formed by using a piezoelectric body and is constructed so as to detect an acceleration which acts in a shearing direction. An electrode formed on the circuit substrate and an electrode on the bottom surface of the acceleration detection element are bonded together via a conductive bonding material so that they do not have direct contact with each other.

Abstract: The invention relates to an electromechanical positioning unit formed as an inertial drive to position objects with atomic scale positioning precision and with displacement ranges up to centimeters. The positioning unit contains at least one preferably tube shaped piezo electric actuator for transmitting electrically controllable inertial driving motions to a slider. The object of the invention is a slider consisting of at least one part of relatively high mass (mass unit) and of at least one flexible deformable part (flexible unit) allowing the frictional forces to be adjustable by bending the flexible parts and the mass part providing high loading capacity of the positioning unit. By combining these two parts it is possible to position heavy objects and to exert forces necessary to drive tools.

Abstract: A vibratory gyroscope including an elongated vibrator having a central (neutral) axis (Y-axis), a drive unit for deforming the first direction such that the vibrator vibrates in a first (X) direction, an added mass attached to the vibrator at a position offset from the central axis in a second (Z) direction, and a detector formed on the vibrator. Rotation of the vibratory gyroscope about the second (Z) direction during vibration in the second direction causes Coriolis force to acting on the added mass in a direction parallel to the central axis. Because the added mass is offset from the central axis, a resulting vibration in the second (Z) direction is produced, which is detected by the detector. With this arrangement, the central axis of the vibrator is placed in parallel with the surface of rotation of the rotating system. Thus, rotations about two or three axes in each direction can be detected in such a manner that noise generation is prevented.

Abstract: In a vibration sensing device for sensing a knocking vibration of an engine, a piezoelectric element is connected to an output terminal through a resilient conductive member. The resilient conductive member has a fixed base part, a sliding part at a position opposite to the fixed base part, and an intermediate V-shaped part resiliently contacting the piezoelectric element. When the sliding part moves slidingly in response to vibration of the piezoelectric element, the sliding friction force which exerts on the sliding part increases the spring constant of the resilient conductive member to be larger than the stationary spring constant of the same by hysteresis characteristics, thereby reducing damage to the piezoelectric element and enhancing reliability of the electric connection.

Abstract: An actuator which includes an electromechanical converting element having a first connection portion and a second connection portion, an inertia member connected to the first connection portion of the electromechanical converting element, and a moving member connected to the second connection portion of the electromechanical converting element. A drive signal control unit produces a drive signal having an asymmetric voltage waveform. The asymmetric voltage waveform has a voltage level increasing portion in which the voltage level of the asymmetric voltage waveform is increasing. The drive signal control unit controls the voltage level of the asymmetric voltage waveform during the voltage level increasing portion of the asymmetric voltage waveform, and applies the drive signal to the electromechanical converting element to generate an inertia force in the inertia member and cause the moving member to move.

Abstract: A monolithic piezoelectric accelerometer of the longitudinal type having a ass element, a piezoelectric accelerometer sensor element and electrodes interconnecting the mass and sensor elements, in which the mass and sensor elements are formed as a monolithic structure. Included is the method for making the monolithic piezoelectric accelerometer.

Abstract: A motion activated and light sensitive multi-purpose safety light, having a housing for supporting: a motion sensor; a light emitting diode which serves as both a light source and a light detector; an electronic circuit which further comprises; a motion sensor amplifier to condition the motion signal received from the motion sensor, a driver for illuminating the light emitting diode in a flashing manner, a timer enabling the operation of the driver and a photo-amplifier providing amplification of the input signal received from the light emitting diode. A user-selected control components for providing parameters relating to the conditioning and the flash rate. A printed circuit board providing an area to mount the electrical components and electric circuit and a system power source.

Abstract: The present invention is related to an angular velocity sensor, and intends to improve the detection characteristic through a precise measuring of an angular velocity signal. For this objective, the invented angular velocity sensor comprises U-shape first and second piezoelectric elements(4),(5) bonded together sandwiching a detection electrode(6), wherein in at least one of the tuning fork arms(4a),(5a) the first and second piezoelectric elements(4),(5) are polarized in a direction of thickness along which the piezoelectric elements are bonded together. Driving electrodes(7),(12) and (8),(11) provided in diagonal arrangement on the tuning fork arm are supplied with driving signals inverse-phased to each other. In such a structure, the driving signals cancel to each other at the vicinity of detection electrode; as a result, the driving signals never mix with a detection signal to be detected by the detection electrode(6). Thus, the capability of detecting an angular velocity signal is improved.

Abstract: A vibration detecting sensor includes a pair of piezo-electric elements electrically connected together using a plate member, which eliminates the influences of temperature change to the surroundings by using a temperature compensating piezo-electric element, and prevents external noises from entering the device. Therefore, vibrations are detected efficiently.

Abstract: A mechanical shock sensor including a diaphragm suspended about its edge to an elevated pedestal and a pattern of piezoelectric material attached to the diaphragm surface. A proof mass is attached beneath the diaphragm surface and centered along a vertical axis passing through the diaphragm and the concentric piezoelectric materials. Electrical conductors are attached to the first and second concentric electrically conductive layers on piezoelectric material and are connected to a circuit capable of responding to the piezoelectric signals developed thereby.

Abstract: A piezo-electricity generation device without an external power supply unit includes a rectifying means which rectifies an AC voltage generated by the vibration of at least one piezo-electric plate. An accumulating means accumulates an electric charge outputted through the rectifying means. A voltage setting means provides a prespecified voltage. A transmission means transmits substantially all of the electric charge accumulated in the accumulating means to a signal output means when the output voltage of the accumulating means exceeds the prespecified voltage set by the voltage setting means. A timing setting means may also or alternatively be provided for setting a prespecified timing such that the transmission means transmits substantially all of the electric charge stored in the accumulating means at the prespecified timing set by said timing setting means.

Abstract: A vibrator is formed on a silicon substrate to become a base by the silicon-processing procedure and a thin film of a piezoelectric material is formed on the substrate by a method matching with the silicon-processing procedure. When an ac field of a frequency near the resonance frequency of the transverse vibration of the vibrator is applied to the thin film of the piezoelectric material, the piezoelectric reverse effect excites characteristic vibration in the vibrator. If a rotational motion is generated along the axis of the beam in that state, the Coriolis' force is generated in a direction perpendicular to both the axial direction and the vibration direction of the beam. This force deforms the beam in that direction. Detecting inductive charges produced in another piezoelectric thin film fixed on the vibrator because of the piezoelectric normal effect due to the deformation, the rotational, angular velocity can be obtained.

Abstract: A transducer includes an elongated piezoelectric sensor having only a single integrated mass of piezoelectric material and a pair of relatively longer opposite edges and a pair of relatively narrower opposite edges. The transducer also includes a sensor support. The support imposes less constraint on one of the pairs of edges than on the other pair. Two piezoelectric sensors are supported back-to-back. Each of the sensors is held on opposite edges by a pair of opposite ledges, while two other opposite edges of the sensors are less constrained. The maximum displacement of the two less constrained edges of each sensor are limited by another pair of opposite ledges which are tapered or spaced away from the sensor when the sensor is in its normal position.