Abstract: An acceleration sensor in which a difference in resonance characteristics between two resonators can be easily adjusted even when casing components are already attached to an acceleration-sensor element includes a bimorph acceleration-sensor element having first and second resonators attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end or both longitudinal ends of the acceleration-sensor element is/are fixed such that the first and second resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. Opposite sides of the acceleration-sensor element with respect to the application direction of acceleration are respectively covered with a pair of casing components.

Abstract: A low-cost breakable inertial threshold sensor using mainly micro-machining silicon technology constructed on a silicon-wafer or on some other brittle material according to the MEMS process. The sensor comprises a first body portion, a second body portion, and detecting means for giving an indication if the second body portion has damaged the detecting means. The status of the sensor can be read in various ways. In one embodiment the status is remotely readable.

Abstract: A single crystal unimorph based accelerometer has a housing base portion with a base portion bottom surface that includes two separate metallization areas. One of the two separate metallization areas is electrical active. The other is a ground electrical connection. A housing top portion is coupled to the housing base portion. A piezoelectric single crystal is positioned between the housing base portion and the housing top portion. The piezoelectric single crystal has a metal shim that forms a unimorph bonded with a metal loaded electrical conductive epoxy, and forms an electrical connection at a top electroding surface of the piezoelectric single crystal. The piezoelectric single crystal includes a cantilevered free portion that extends to the housing base portion At least a portion of the top electroding surface of the piezoelectric single crystal provides for tuning of capacitance and is an active electrical connection for the unimorph.

Abstract: A single crystal based leveraged shear mode accelerometer includes a housing base portion with a base portion bottom surface that includes two base metallization areas. A housing top portion is coupled to the housing base portion. A subassembly includes a piezoelectric single crystal positioned between the housing base portion and the housing top portion. The piezoelectric single crystal is held vertical by the base portion and a shear plate bonded with a metal loaded electrical conductive epoxy. The base portion and the shear plate both have machined edges in a vertical direction. These machined edges pointing against an electrically insulating plate and form an active electrical connection at a top surface of the piezoelectric single crystal, and an electrical ground connection at a bottom surface of the piezoelectric single crystal. The subassembly is held to a mass construct with micromachined screws to the base portion, forming an accelerometer assembly in tension.

Abstract: A piezoelectric-vibrator series circuit including two series-connected piezoelectric vibrators to which stresses induced by a dynamic quantity are applied in opposite directions is used, and a Colpitts oscillator circuit is defined by the piezoelectric-vibrator series circuit and an amplifier circuit/load impedance circuit. A phase-difference-to-voltage converter circuit is provided to convert a phase difference between an output voltage of the oscillator circuit and a voltage at a piezoelectric-vibrator series node of the piezoelectric-vibrator series circuit into a voltage signal.

Abstract: An integral connectorless hermetically sealed high-temperature piezoelectric sensor housing and cable assembly includes signal conditioning/processing circuitry having a charge amplifier-differential amplifier combination with integral trim capacitor and/or a voltage divider network in at least one signal processing path to provide the ability to custom adjust input impedances and balance common-mode signals to compensate for inequalities caused by inherent parasitic capacitances and specific structural constraints of the sensor assembly.

Abstract: An acceleration sensor includes a mass and a supporting member linked by a flexible beam. A strain detector having low-resistance areas at both ends is formed near a boundary between the beam and the mass or between the beam and the supporting member. A dielectric film formed on the supporting member and the beam has multiple contact holes disposed over each low-resistance area. Wiring formed on the dielectric film is connected to the low-resistance areas through the contact holes. The provision of multiple contact holes for each low-resistance area extends the life of the acceleration sensor by preventing sensor failure due to the separation or other failure of any single contact.

Abstract: An acceleration sensor includes a weight and a vibrator that supports the weight at its center of gravity. When acceleration is applied to the weight, stress equivalent to the applied acceleration is generated in the vibrator. As the vibrator is arranged to support the weight at its center of gravity, a characteristic relationship is observed between the acceleration, such as angular acceleration or translational acceleration, and the size of electric charges and the polarity. By taking advantage of this relationship, different types of acceleration can be easily detected.

Abstract: An acceleration sensor includes a weight; a base portion, a beam; and a piezo resistance element. The weight is arranged to displace upon receiving acceleration. The base portion is disposed around the weight apart from the weight. The beam has one end portion connected to the weight and the other end portion connected to the base portion. The beam also has a thick layer portion and a thin layer portion having a thickness smaller than that of the thick layer portion. The piezo resistance element is disposed over the thick layer portion and the thin layer portion.

Abstract: An angular rate sensor including: a silicon-on-insulator (SOI) substrate having a substrate, an oxide layer formed above the substrate, and a semiconductor layer formed above the oxide layer; a tuning-fork type vibrating portion obtained by processing the semiconductor layer and the oxide layer and formed of the semiconductor layer; a driving portion which generates flexural vibration of the vibrating portion; and a detecting portion which detects an angular rate applied to the vibrating portion.

Abstract: An acceleration sensor chip has a frame portion having a frame body portion and protruding portions. The acceleration sensor chip also includes a mobile structure having a central weight portion supported movably by four beam portions. The mobile structure also has four rectangular parallelepiped-form protruding weight portions The acceleration sensor chip also includes a plurality of stoppers extending above the protruding weight portions.

Abstract: A piezoelectric accelerometer comprising a housing with two complementary parts (2005, 2006) in which a metal mass (2002) and an abutting piezoelectric element (2003) movably mounted in place are sandwiched between two conductive contact elements (2001, 2004), wherein the metal mass (2002) is in intimate contact with the piezoelectric element (2003) and the two conductive contact elements (2001, 2004) act as the electric terminals for connecting the accelerometer to any external electronic circuit for further processing.

Abstract: The inventive device comprises a piezo element, embodied in the form of a square based rectangular parallelopiped fixed to a substrate. A piezo module matrix is embodied in a given shape. A conductive layer is made of a conductive glue. The edges of said rectangular parallelopiped are devoid of said conductive layer which is embodied in the form of a rectangle on each side face. For each side face, a charge is picked-up at one point which is located in the area of one of angular points of the conductive rectangle of the side face. The substrate is embodied such that it is conductive. The square base is fixed to the substrate by use of a conductive glue which is also used for the conductive layer.

Abstract: An activity monitor is provided that corrects for the effects of motion external to the entity being monitored. For example, the activity monitor can overcome the effects of vehicular travel.

Abstract: A compact, highly sensitive acceleration sensor that is not affected by factors other than acceleration, such as a change in temperature, includes a bimorph acceleration-sensor element including first and second resonators and attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end or both longitudinal ends of the acceleration-sensor element is/are fixed such that the resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. The acceleration-sensor element is bendable about a central bending plane N1 in response to the acceleration, the central bending plane N1 being positioned at a central portion of the base plate with respect to the application direction of acceleration.

Abstract: The vibration-type piezoelectric acceleration sensor element includes a frame; and a diaphragm, support, and retentive part, provided in the frame. The diaphragm includes a bottom electrode layer, a piezoelectric thin-film layer formed on the bottom electrode layer, and a top electrode layer formed on the piezoelectric thin-film layer. A first end of the diaphragm is connected to the frame. The support retains a second end of the diaphragm. The retentive part retains the support so that the support is reciprocable only in a direction through the first end and the second end of the diaphragm.

Abstract: A compact, high-sensitivity acceleration sensor that is prevented from being affected by factors other than acceleration, such as a change in temperature, has a bimorph acceleration-sensor element including first and second resonators attached to opposite sides of a base plate with respect to a direction in which acceleration is applied. One longitudinal end of the acceleration-sensor element is fixed such that the first and second resonators bend in the same direction in response to the acceleration. Changes in frequency or changes in impedance in the first and second resonators caused by the bending of the acceleration-sensor element are differentially detected in order to detect the acceleration. The acceleration-sensor element is bendable about a central bending plane in response to the acceleration, the central bending plane being positioned at a central portion of the base plate with respect to the application direction of acceleration.

Abstract: A physical quantity sensor is constituted using a plurality of piezoelectric sensors each having first and second semiconductor layers realizing resistances and terminals, and a conductive weight portion in relation to an opening of an insulating film that partially exposes the main surface of a substrate. Both the semiconductor layers are elongated from the periphery of the opening on the insulating film inwardly into the opening so as to three-dimensionally support the conductive weight portion in a floating manner, thus realizing three-dimensional displacement. A capacitance electrode layer is arranged in the bottom of the opening on the main surface of the substrate so as to establish capacitance with the conductive weight portion. The displacement of the conductive weight portion is detected based on resistance variations and capacitance variations. Thus, it is possible to detect physical quantity such as acceleration, vibration, and inclination with a reduced chip size.

Abstract: A sensor, sensory array, and associated method for measuring a pressure are provided. The sensor includes a piezoelectric sensory device that is disposed on an electrically insulative substrate that can be adhered to a member for measuring the pressure on the member. The piezoelectric sensory device defines first and second contact surfaces and is adapted to provide an electric potential between the surfaces that corresponds to a pressure on the piezoelectric sensory device. Conductive terminals are in electrical communication with the piezoelectric sensory device and therefore also provide the electric potential indicative of the pressure on the surface of the test member. An electrically insulative sheet is disposed opposite the piezoelectric sensory device from the substrate. An electronic monitoring device can be electrically connected to the piezoelectric sensory device via the terminals and configured to monitor the electric potential provided by the piezoelectric sensory device.

Abstract: A piezoelectric vibrator 2 that generates an electric charge according to a stress and a weight 1 provided on the piezoelectric vibrator 2 are included. The piezoelectric vibrator 2 has multiple pairs of sensing electrodes 3a and 3b, and 4a and 4b, and the sensing electrodes 3a and 3b, and 4a and 4b are respectively connected in parallel so that capacitances Cd1 and Cd2 made of the sensing electrodes may be connected in parallel. It is thus possible to double the charge sensitivity with keeping the voltage sensitivity.

Abstract: The present invention is directed to an acoustic vector sensor, also called particle velocity sensor. <111> direction poled, shear mode, relaxor single crystals are used as the sensing elements. In addition, these crystal plates are cut at a special orientation such that they provide zero or minimum responses in the transverse directions, but have a maximum piezoelectric response in sensing direction. The piezoelectric sensor contains a proof mass, a base, and an aforementioned relaxor crystal. Three of the sensors are mounted orthogonally with a rigid case, and they are designated to sense the acoustic particle velocity in three designated directions, say X, Y, and Z. To solve the adverse lateral constraint problem (also known as clamping effect) associated with the relaxor crystal; reduced bonding area between the proof mass and the relaxor crystal are introduced.

Abstract: A lithographic projection apparatus comprising at least one of a radiation system and a projection system having at least one of a reflective and a refractive optical member, wherein the optical member is supported by at least one piezoelectric actuator for positioning the optical member. The piezoelectric actuator comprises three parallel plates stacked on top of one another with piezoelectric stacks between the plates.

Abstract: An accelerometer has a cantilever beam supported at one end and having an opposite free end with a longitudinal direction between the supported end and the free end, the beam being formed of a piezoelectric layer and a supporting layer. An inertial, sensing mass is mounted at the free end of the beam, and is located eccentrically relative to the longitudinal direction of the beam. The accelerometer has a primary direction of sensitivity to acceleration forces, and a secondary direction of sensitivity, which is orthogonal to the primary direction and in which the sensitivity is negligible. The secondary direction forms an angle relative to the longitudinal direction of the beam such that a line coinciding with a force proceeding through the center of gravity of the inertial mass, and which is directed in the secondary direction, also intersects the beam.

Abstract: The present invention provides a method for making high-frequency piezoelectric resonators so that constants of the resonator can be measured precisely. A cavity is formed at a central section of an AT-cut crystal substrate. Two grooves are formed at predetermined distances from the left and right of the cavity, and two more grooves are formed at predetermined distances outward from these two grooves. Two more grooves perpendicular to the first set of grooves are formed. A pair of main electrodes and a pair of secondary electrodes shorted to ground and surrounding the main electrodes are disposed at roughly the center of the crystal substrate. One main electrode and one secondary electrode are used as inputs and the other main electrode and secondary electrode are used as outputs, with these two terminal pairs being used to measure and adjust a frequency.

Abstract: An apparatus in one example includes a compliant component for supporting an electrical interface component that serves to electrically and mechanically couple a die with a separate layer. In one example, the compliant component, upon relative movement between the die and the separate layer, serves to promote a decrease in stress in one or more of the die and the separate layer. The apparatus in another example includes a compliant component for supporting an electrical interface component that serves to create an electrical connection between a die and a separate layer. The compliant component, upon relative movement between the die and the separate layer, serves to promote maintenance of the electrical connection.

Abstract: The present invention provides a solid-state rotational rate sensor device formed by a thin-film for generating an electrical voltage output proportional to the rate of rotational motion. The precision thin-film piezoelectric elements are configured and arranged on a semi-rigid structure to detect rotation (such as pitch, roll, and yaw) while rejecting spurious noise created by vibration, thermal gradients, and electro-magnetic interference.

Abstract: An acceleration sensor comprises a fixed case member and a cover assembly collectively defining a closed space in which the oscillation plate and the piezoelectric element received therein. The oscillation plate and the piezoelectric element are oscillatably supported by a supporting portion formed on the central bottom portion of the fixed case member.

Abstract: FBAR device includes a membrane supporting layer between a substrate and a membrane layer, surrounding an air gap region. The membrane supporting layer support the membrane layer to obtain a robust structure. The substrate has a first area and a second area surrounding the first area. The membrane supporting layer is formed on the second area of the substrate so as to form the air gap on the first area of the substrate. The membrane layer is formed on the membrane supporting layer and the air gap. A first electrode is formed on a portion of the membrane layer. A piezoelectric layer is formed on a portion of the first electrode. A second electrode is formed on a portion of the piezoelectric layer.

Abstract: An acceleration sensor which has a vibrator, a weight portion that is connected to the vibrator, and supported at a position different from the center of gravity of the vibrator plus its own structure, and a detecting section which detects the amount of characteristic corresponding to an angular moment that is exerted in the vibrator upon application of an acceleration in one direction to the vibrator and the weight portion. When an acceleration in one direction is applied to the vibrator and the weight portion connected thereto, an angular moment is exerted in the vibrator due to the difference between the supporting point of the weight portion and the center of gravity of the vibrator plus the weight portion, and the amount of characteristic corresponding to the angular moment is detected by the detecting section so that the acceleration of a linear motion is detected.

Abstract: In an acceleration sensor including a vibrator subject to a sliding vibration and a weight section connected to the vibrator and supported at a position different from the position of the center of gravity of an assembly of the vibrator and weight section, for detecting an angular moment about the support point, which is produced at the weight section by application of acceleration, as sliding vibration with the vibrator, the acceleration sensor includes a rectangular substrate having a plurality of electrodes electrically connected to the vibrator, a formation pattern of the plurality of electrodes is symmetrical about an axis parallel to at least one side of the substrate, and the plurality of electrodes have substantially equal thickness. Since the formation pattern of the electrodes on the substrate is symmetrical and the respective electrodes have substantially equal thickness, the vibrator that is bonded to this substrate does not incline and the detection sensitivity does not vary.

Abstract: An acceleration sensor for detecting an acceleration caused by an object oscillated in an oscillation direction, comprises a sensor casing having a center axis that is positioned in coaxial alignment with the oscillation direction to receive the acceleration, an oscillation plate and a piezoelectric element. The sensor casing has first and second circular inner surfaces opposing to and spaced apart along the center axis from each other at a first space distance, and a third cylindrical inner surface connected at one end with the first inner surface and at the other end with the second inner surface to define a cylindrical closed space. The oscillation plate is accommodated in the closed space of the sensor casing and has a central portion securely supported by the sensor casing and a peripheral portion integrally formed with the central portion and extending radially outwardly of the central portion.

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

Abstract: An acceleration sensor includes a piezoelectric element and a support member for supporting the piezoelectric element at both longitudinal ends thereof. The piezoelectric element includes a laminate having a plurality of piezoelectric layers. An intermediate piezoelectric layer is a dummy layer which generates no charge when acceleration is applied thereto. Each of the two outer piezoelectric layers includes four longitudinally aligned regions separated at two borders and one central border where stress is inverted when the acceleration is applied. The two outer piezoelectric layers are polarized in the direction of thickness of the piezoelectric element such that cells adjacent to each other in the longitudinal direction of the piezoelectric elements have opposite polarization directions and such that cells aligned with each other in the direction of thickness have the same polarization.

Abstract: An acceleration sensor includes a piezoelectric element and a support member for supporting the piezoelectric element at both longitudinal ends thereof. The piezoelectric element includes a laminate of at least two piezoelectric layers. Each of the at least two piezoelectric layers includes three longitudinally aligned regions separated at two borders where stress is inverted in the longitudinal direction of the piezoelectric element when acceleration is applied. Cells, each formed of a respective region, are polarized in the same direction of thickness in each of the two external piezoelectric layers. Electrodes are arranged so that the three cells in the one piezoelectric layer are serially connected, the three cells in the other piezoelectric layer are serially connected, and then the three serially connected cells in the one piezoelectric layer and the three serially connected cells in the other piezoelectric layer are connected in parallel.

Abstract: An acceleration sensor for detecting an acceleration caused by an object oscillated in an oscillation direction, comprises a sensor casing having a center axis that is positioned in coaxial alignment with the oscillation direction to receive the acceleration, an oscillation plate and a piezoelectric element. The sensor casing has first and second circular inner surfaces opposing to and spaced apart along the center axis from each other at a first space distance, and a third cylindrical inner surface connected at one end with the first inner surface and at the other end with the second inner surface to define a cylindrical closed space. The oscillation plate is accommodated in the closed space of the sensor casing and has a central portion securely supported by the sensor casing and a peripheral portion integrally formed with the central portion and extending radially outwardly of the central portion.

Abstract: A high-frequency oscillation circuit incorporates a crystal resonator having a natural oscillation frequency in a high-frequency area within a closed circuit including one or more logic elements. Therefore, this circuit copes with an oscillation frequency of 1 MHz to 2 GHz or more in basic oscillation frequency of a crystal resonator and it oscillates with stability at the basic oscillation frequency of the crystal resonator.

Abstract: An acceleration sensor includes a piezoelectric single-plate having a weight part and a detection part. The piezoelectric single-plate is, for example, an X-cut plate of LiNbO3.

Abstract: Providing a small-sized acceleration sensor including a vibrator formed of a piezoelectric single crystal, and a weight section connected to the vibrator and supported at a position different from the position of the center of gravity of an assembly of the vibrator and weight section. Two divided electrodes used for detecting an electrical signal are formed on the vibrator and connected to two wiring patterns of the weight section which also functions as a signal detecting substrate, with an anisotropic conductive adhesive. When an acceleration in one direction is applied, an angular moment exerted in the weight section is detected as sliding vibration by the vibrator, and an electrical signal corresponding to the acceleration is output from the electrodes through the wiring patterns.

Abstract: An acceleration sensor includes a first resonator and a second resonator which resonate at independent frequencies and each of which includes a piezoelectric body and electrodes arranged on both main surfaces thereof, and a first base plate and a second base plate. A first unimorph type acceleration detection element includes the first resonator bonded to one surface of the first base plate, and a second unimorph type acceleration detection element includes the second resonator bonded to one surface of the second base plate. Each of the first and second unimorph type acceleration detection elements is fixed at one longitudinal end thereof or opposed longitudinal ends thereof such that the first resonator and the second resonator are diametrically opposed to each other or are arranged to face each other to allow the first resonator and the second resonator to independently deflect in response to the application of acceleration.

Abstract: An acceleration sensor comprises a fixed case member and a cover assembly collectively defining a closed space in which the oscillation plate and the piezoelectric element received therein. The oscillation plate and the piezoelectric element are oscillatably supported by a supporting portion formed on the central bottom portion of the fixed case member.

Abstract: The object of the present invention is to improve the sensitivity of a vibrator having at least one bending vibration arm vibrating along a specified plane in bending mode, and a base portion provided at one end of the arm. A vibrator 20A has at least one bending vibration arms 14, 15 vibrating along a specified plane in bending mode, base portions 1 and 22 provided at one ends of the arms 14 and 15, respectively, and weight portions 9, 12 provided at the other ends of the arms 14 and 15, respectively. Grooves 5 and 6 are formed on one main face 33 and the other main face 34 substantially parallel with the specified plane of the bending vibration arms 14 and 15, respectively.

Abstract: An acceleration sensor for detecting an acceleration caused by an object oscillated in an oscillation direction, comprises a sensor casing having a center axis that is positioned in coaxial alignment with the oscillation direction to receive the acceleration, an oscillation plate and a piezoelectric element. The sensor casing has first and second circular inner surfaces opposing to and spaced apart along the center axis from each other at a first space distance, and a third cylindrical inner surface connected at one end with the first inner surface and at the other end with the second inner surface to define a cylindrical closed space.

Abstract: An acceleration sensor includes a sensing element and a pair of supporting members for supporting the sensing element at one end in the longitudinal direction thereof. The sensing element includes four laminated piezoelectric layers, and electrodes are provided at the center in the thickness direction of the sensing element, between a pair of first layers and a pair of second layers, and on the outer surfaces of the pair of second layers. Cells formed by the first and second layers at each side of the center in the thickness direction are electrically connected in parallel. The pair of first layers preferably have substantially the same thickness and the pair of second layers preferably have substantially the same thickness, and the ratio of the thickness T1 of each first layer to the total thickness T2 of each first and second layer is about 62% to about 76%.

Abstract: An inertial positioning device comprising: a base plate (10); a top plate (20) for mounting an element to be rotated; a rotation member (16) having a column (18) on which the top plate is mounted in frictional engagement for slip-stick rotational motion; and a pair of piezoelectric actuators (12) each secured to the base plate at one end and to lateral extensions (17) of the rotation member at their other ends. Simultaneous actuation of the piezoelectric actuators rotates the column of the rotation member about its axis. When a suitable asymmetric drive signal is supplied to the piezoelectric actuators, the top plate is rotated by slip-stick motion. The device is compact, has a good load capacity for an inertial motor and is operable in extreme environments such as liquid helium temperatures, high vacuum and high magnetic fields.

Abstract: A method for manufacturing a flexural plate wave sensor includes the steps of depositing an etch-stop layer over a substrate, depositing a membrane layer over the etch stop layer, depositing a piezoelectric layer over the membrane layer, forming a first transducer on the piezoelectric layer and forming a second transducer on the piezoelectric layer, spaced from the first transducer. The method further includes the steps of etching a cavity through the substrate, the cavity having substantially parallel interior walls, removing the portion of the etch stop layer between the cavity and the membrane layer to expose a portion of the membrane layer, and depositing an absorptive coating on the exposed portion of the membrane layer.

Abstract: An accelerometer comprises a housing including a mass-supporting frame and a mass supported on the frame by a pair of outer spring member aligned along a first axis. The mass may comprise an outer mass connected to the pair of outer spring members and an inner mass connected to the outer mass by a number of inner spring members, the inner spring members aligned along one or more axes, which form a plane which the axis of the outer spring members also may be aligned. Also provided is means for detecting rotation of the mass and translation of the inner mass.

Abstract: The present invention is directed to a sensing structure comprising four components: a central block proof mass, a continuous belt-shaped membrane (or one having another suitable shape), a piezoelectric sensing layer placed on top of the membrane, and a fixed mounting frame. Electrodes are attached to the top and the underside of the piezoelectric sensing layer. The structure results in an axisymmetric stress distribution.

Abstract: A piezoelectric sensor includes a carrier, a piezoelectric measurement sensing element arranged on the carrier, a covering layer covering the measurement sensing element and an electronic evaluation unit. The measurement sensing element is formed by a piezoelectric layer. The carrier has a first contact layer electrically connected to the piezoelectric layer and the covering layer has a second contact layer electrically connected to the piezoelectric layer. The electronic evaluation unit is able to determine a mechanical loading of the piezoelectric layer by evaluating the difference of electrical potential between the first contact layer and the second contact layer.

Abstract: A tuning fork vibrator includes a long plate-shaped vibration unit having a first principal surface and a second principal surface, a base disposed at one end of the second principal surface of the vibration unit in the longitudinal direction, and a slit for dividing the vibration unit into two legs defining a tuning fork along the longitudinal direction symmetrically in the width direction of the vibration unit. The slit is formed so as to include a portion of the base in the vicinity to the vibration unit.

Abstract: An acceleration sensor comprises a fixed case member and a cover assembly collectively defining a closed space in which the oscillation plate and the piezoelectric element received therein. The oscillation plate and the piezoelectric element are oscillatably supported by a supporting portion formed on the central bottom portion of the fixed case member.