Abstract: A device has a substrate, a piezo polymer layer arranged adjacent the substrate, a first electrode in contact with a first side of the layer, and a second electrode arranged adjacent the first electrode, such that when the piezo layer flexes, the first and second electrodes are arranged to detect one of a change in voltage or resistance, wherein at least one of the piezo polymer layer or the electrodes are deposited by printing. A method including depositing a spacer layer onto a substrate, depositing a piezo polymer layer onto the substrate, patterning an array of first electrodes in contact with the piezo polymer layer, and patterning an array of second electrodes adjacent the array of first electrodes, wherein depositing includes one of printing and laminating and pattering includes one of printing and etching.

Abstract: Provided is a micro stage comprising: a body having a vertically perforated through-hole passing through a central portion thereof; a bobbin including a tip portion with an electron emission tip embedded in the center thereof, and passing through the through-hole of the body to be moved in the through-hole along a first axis perpendicular to a vertical direction; a first piezoelectric element disposed on the body and lengthened when a voltage is applied thereto to push the bobbin in one direction along the first axis; a second piezoelectric element disposed on the body and lengthened when a voltage is applied thereto to push the bobbin in the other direction along the first axis; and an upper cover that is coupled to an upper portion of the body and has a through-hole, through which the bobbin passes and communicates with the through-hole of the body, wherein the bobbin can be positioned as desired along the first axis by adjusting the voltages applied to the first piezoelectric element and the second piezoel

Abstract: A pressure sensor includes a sensor which is arranged to couple to a process pressure. A quartz crystal is coupled to the sensor and is configured to measure pressure of fluid in the sensor body. An output from the quartz crystal is related to pressure applied to the sensor body by the process pressure.

Abstract: A piezoelectric actuator with piezoelectric elements, fastened between an actuator head and an actuator foot, and with a plastic sleeve surrounding at least the piezoelectric elements is proposed, which is set in a clamping ring on the actuator head and/or the actuator foot of the piezoelectric actuator. The respective clamping ring may be a metal part or a plastic part, which is equipped with clamping lugs suitable for setting the plastic sleeve and is thrust, pressed, or shrunk onto the respective actuator head and/or actuator foot of the steel piezoelectric actuator.

Abstract: A touch panel includes a transparent base board, a mesh-shaped sensor portion formed on the base board and made of piezoelectric materials, a mesh-shaped black matrix formed on the sensor portion; and a pixel portion formed on portions of the base board exposed from the sensor portion and the black matrix for displaying images. When the base board is touched, the sensor portion transforms the pressure on the base board into piezoelectric signals for inputting operating instruction.

Abstract: The design and refinement of a tethered hovering platform into a feasible working system is presented. To determine a starting point for the design, a detailed historical search was conducted to find the history and the current state of such technology. Real world current needs are analyzed to produce a mission specification and to drive the preliminary vehicle design. Analysis of environmental conditions and decisions about an initial payload package are made in conjunction with motor and propeller sizing. Initial concept testing to discover feasibility and operational issues was performed; from this, instability issues were discovered. Analyzing these instability issues using known rotorcraft and momentum effects, in conjunction with flight testing, yields possible solutions to the problem. The use of constrained layer dampers as a means of passive stabilization is addressed and suggested as the preferred solution. Testing of passive constrained layer damping verifies the stability of the solution.

Abstract: An integrated sensory actuator (10) which uses an electroactive polymer is provided. The sensory actuator is comprised of an actuating member (12) made of an ionic polymer-metal composite; a sensing member (14) made of a piezoelectric material; and an insulating member (16) interposed between the actuating member and the sensing member. The sensory actuator may further include a compensation circuit adapted to receive a sensed signal from the sensing member and an actuation signal from the actuating member and compensate the sensed signal for feedthrough coupling between the actuating member and the sensing member.

Abstract: A micromechanical element includes a movable functional element, a first retaining element, a second retaining element, a third retaining element, and a fourth retaining element. The first retaining element and the functional element are connected at a first junction, the second retaining element and the functional element are connected at a second junction, the third retaining element and the functional element are connected at a third junction, and the fourth retaining element and the functional element are connected at a fourth junction. In addition, the first retaining element and the second retaining element each include a piezoelectric driving element, the driving element of the first retaining element and the driving element of the second retaining element being configured to move the functional element in accordance with electric excitation.

Abstract: An ultrasonic sensor according to the present invention is used, for example, for detecting an obstacle positioned in front of an automotive vehicle. The ultrasonic sensor includes an piezoelectric element connected to an acoustic matching member and a processing circuit, all contained in a casing. Ultrasonic waves reflected on an object are received by the acoustic matching member and converted into electrical signals in the piezoelectric element. The electrical signals are processed in the processing circuit to thereby detect a distance to the object and/or positions of the object. A surface of the acoustic matching member connected to the piezoelectric element is made larger than the piezoelectric element to form an overhang area on a conductive layer formed on the acoustic matching member. In this manner, electrical connection in the ultrasonic sensor is easily made, and detection sensitivity of the ultrasonic sensor is enhanced.

Abstract: A micro mechanical backscatter sensor includes a receiver for receiving a modulated electromagnetic signal, a capacitive element operatively connected to the receiver, the capacitive element being arranged such that a voltage is generated across the capacitor in response to the frequency of the received signal, and a resonator operatively connected to the capacitive element such that electrostatic forces that are induced by the voltage generated cause the resonator to vibrate at a resonance frequency, the resonator being arranged such that an applied external force alters the resonance frequency of vibration.

Abstract: A multi-layer structure for sensing impacts in real-time having an inner layer of polyvinylidene fluoride having piezoelectric properties disposed between and joined with two outer layers of an electrical signal conductor.

Abstract: There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a MEMS device, and technique of fabricating or manufacturing a MEMS device, having mechanical structures encapsulated in a chamber prior to final packaging. An embodiment further includes location of a piezoelectric material as part of a semiconductor sensing structure. The semiconductor sensing structure, in conjunction with the piezoelectric material, can be used as a sensing device to provide an output signal associated with a sensed event.

Abstract: A piezoelectric bimorph cantilever is used for determining physical parameters in a gaseous or liquid environment. The sensor works as a driven and damped oscillator. Contrary to common cantilever sensor systems, the piezoelectric film of the bimorph cantilever acts as both a sensor and an actuator. Using at least two resonance mode of the bimorph cantilever, at least two physical parameters can be measured simultaneously in a gas or a liquid. An optimized piezoelectric cantilever and a method to produce the cantilever are also described.

Abstract: The present invention provides electroactive polymers, transducers and devices that maintain pre-strain in one or more portions of an electroactive polymer. Electroactive polymers described herein may include a pre-strained portion and a stiffened portion configured to maintain pre-strain in the pre-strained portion. One fabrication technique applies pre-strain to a partially cured electroactive polymer. The partially cured polymer is then further cured to stiffen and maintain the pre-strain. In another fabrication technique, a support layer is coupled to the polymer that maintains pre-strain in a portion of an electroactive polymer. Another embodiment of the invention cures a polymer precursor to maintain pre-strain in an electroactive polymer.

Abstract: Today, electromechanical actuator systems are used in a variety of applications, of which some are more safety critical than others. Likewise, they are used in a wide range of applications where the safety of persons often to a higher or lesser extent depends on that the actuators remains safe both during normal use and in the fault conditions, which may occur. By an actuator comprising a DC motor (2) equipped with a worm drive and a spindle (4), the typical wearing components are the bearing, which carries the spindle (4), the spindle nut (5) and the worm wheel (9) in the worm drive. Common to the described defect situations is that they in the time leading up to the occurrence of the defect will show a decrease in the ratio of efficiency. Whether it is the spindle bearing, the worm drive, the spindle nut (5) or for that matter the motor, which is getting worn, the proportion between the current which the motor absorbs and the force the actuator performs will change.

Abstract: A sensor apparatus and method for detecting an environmental factor is shown that includes an acoustic device that has a characteristic resonant vibrational frequency and mode pattern when exposed to a source of acoustic energy and, further, when exposed to an environmental factor, produces a different resonant vibrational frequency and/or mode pattern when exposed to the same source of acoustic energy.

Abstract: A device for sample tissue disruption and/or cell lysis comprising: a piezoelectric material; and at least a second material in contact with the piezoelectric material; and wherein the second material has an uneven surface on an opposite side to that in contact with the piezoelectric material. The device may be made by assembling at least three layers and membranes for the valves and pumps. The piezoelectric material is actuated by an external voltage source to generate cavitation, which disrupts tissue and/or lyses cells, in particular by a modulated alternative external voltage. The invention further provides a method of disrupting tissue and/or lysing cells in a device. Also provided is a piezoelectric device comprising a piezoelectric material in contact with a second material, and wherein the second material has an uneven surface on an opposite side to that in contact with the piezoelectric material.

Abstract: Embodiments include strain sensor devices for detecting movement, morphological changes or other physical parameters within a patient's body tissue. Some embodiments are directed specifically to measuring parameters within a patient's heart and may also be configured to communicate with an implantable stimulation device and associated external programming device.

Abstract: Piezomagnetic, magneto-strictive, or electro-strictive material particles may also be distributed throughout the structural material of the structural member, which serve to amplify and otherwise enhance the signals from the piezoelectric material particles. The piezoelectric, electro-strictive, magneto-strictive, and/or piezomagnetic material particles may allow the structural member to exhibit an electrical and/or magnetic response to forces on the structural member, such as accelerations. This may allow the structural member to function as a force sensor or an accelerometer. Signals induced by such external forces or accelerations may be taken from the conductive pickups and used for various operations, for example, for arming a warhead of a missile or for triggering passenger safety features such as air bags in automobiles.

Abstract: A method is disclosed for testing bonded part integrity of bonded structures with increased sensitivity and in a nondestructive manner. The method includes the steps of: mixing a piezoelectric material or an electrically conductive material with an adhesive agent, curing the adhesive agent in between bonding target objects, electrically connecting the bonding target objects to one another, causing an electric current to flow through the bonding target objects to measure a quantity of electric charges flowing between the bonding target objects, and determining existence of bonding damage between the bonding target objects and the adhesive agent based on the quantity of electric charges and predicting a remaining life span of the bonded structures based on a data indicating a correlation between the quantity of electric charges and a predetermined fatigue life.

Abstract: A capacitive membrane is used as a digital sensor. Membranes act as binary devices, such as being in a collapsed or non-collapsed state. By providing drum heads (membranes and associated gaps) with different response characteristics, the drum heads of an element digitally indicate the amplitude of the acoustic force by which of the drum heads are triggered or change states. The digital transducer may be used for different types of sensors, such as a CMUT, an air pressure, a temperature, a humidity, a chemical or biological stimulus or other sensor.

Abstract: Subject matter disclosed herein may relate to energy harvesting piezoelectric modules as may be used, for example, in power supplies for tire pressure monitoring systems.

Abstract: There is provided a substrate supporting vibration structure which is a vibration structure for supporting a substrate. The substrate supporting vibration structure includes a spacer member, fixed between a first substrate and a second substrate, having at least one form selected from a pillar form and a long strip form; and a piezoelectric element, formed at a predetermined position between the first substrate and the second substrate or at a predetermined position of the long strip-form portion of the spacer member, having a vibration supporting portion and a vibration applying portion. In the structure, the vibration supporting portion and vibration applying portion of the piezoelectric element are disposed in the thicknesswise direction of the first and second substrates stacked.

Abstract: A strain sensor for measuring strain in a surface of an object includes an insulating flexible substrate, a first conductive contact, a second conductive contact and a piezoelectric nanowire. The insulating flexible substrate is coupled to the object. The first conductive contact and the second conductive contact are mounted on the insulating substrate. The piezoelectric nanowire is electrically coupled to the first conductive contact and the second conductive contact. The piezoelectric nanowire is subject to strain when the surface of the object is subject to strain, thereby creating a voltage differential therebetween. A trigger sensor includes a substrate, a piezoelectric nanowire and a conductive contact. The piezoelectric nanowire extends from the substrate. The conductive contact is disposed in relation to the piezoelectric nanowire so that a voltage differential between the substrate and the conductive contact when the substrate moves with the predetermined acceleration.

Abstract: A device (D) is dedicated to fixing a first piece of equipment (E1) relative to a second piece of equipment (E2). The device has (i) a structure having a rigid central body (CC) prolonged by two approximately identical terminal bodies (CT1, CT2) each having a neck defining a flexible intermediate part (PD1, PD2) that is symmetric relative to a symmetry element, prolonged by a rigid internal part (PI1, PI2) that is symmetric relative to the symmetry element and joined to one of the ends of the central body (CC), and by a rigid external part (PE1, PE2) that is symmetric relative to a symmetry element, spaced from the internal part, and intended to be joined to the first (E1) or second (E2) piece of equipment. The device has (ii) at least two piezoelectric transducers (T11-T22) with each responsible for converting either an axial dimensional change into a measurement current representing the amplitude of the change, or a control current into a corresponding axial dimensional change.

Abstract: A piezoelectric composite device including: a feeding electrode; a common electrode; a signal detecting electrode; a first piezoelectric element joined between the feeding electrode and the common electrode; and a second piezoelectric element joined between the common electrode and the signal detecting electrode; a predetermined voltage being supplied between the feeding electrode and the common electrode; and a force detection signal based on an external force being extracted from the detecting electrode.

Abstract: A tactile input/output device and a driving method thereof are provided. The device includes at least one input end, at least one output end, and a controller. The input end includes a plurality of input cells arranged at regular intervals. The output end includes a plurality of output cells arranged at regular intervals. The controller senses an input signal of the input end and controls the output end to generate a corresponding output signal. The input end and the output end are installed to form one array with being separated. The input cell and the output cell are arranged so that they do not overlap with each other.

Abstract: A piezoelectric buzzer includes a vibrating layer capable of withstanding temperatures in excess of 260° C. for at least five minutes while still maintaining its ability to vibrate and produce a buzzing sound at a level of at least 80 dB, and a high temperature piezoelectric material having a Curie temperature in excess of 260° C. and one or more of the following properties: a planar coupling coefficient (kp) of at least about 0.5; a longitudinal coupling coefficient (k33) of at least about 1500; and a mechanical quality factor (Qm) of at least about 2000. The piezo material may have a combination of these properties such that the product (kp2)(k33)(Qm) is at least about 1.5×106. The piezoelectric material may have a base formula of PbxSr(1-x)(Mn1/3Sb2/3)(1-y)(ZrzTi1-z)yO3 with x ranging from 0.95 to 0.99, y ranging from 0.92 to 0.97, and z ranging from 0.45 to 0.55, and may further include dopants in the amounts of about 0.4% CeO2, about 1% CuO, and about 4% Nb2O5.

Abstract: A piezoelectric measuring element (9) consists of at least two piezoelectric crystals (1) showing a transversal effect for the measurement of axially acting forces and/or pressures as well as to a pressure or force sensor comprising said element. The crystals (1) with transversal effect having an opposite polarization (4) to each other are attached to each other by means of a lateral electrode (12). In this manner, if n crystals (1) are attached to each other, a single multi-layer measuring element (9) is obtained with a stability under load which is n-times that of an individual crystal. Preferably, the electrodes extend alternately into the two force-absorbing end faces (3) of the crystals. Such measuring elements can be fabricated from wafers (15) in a cost-effective manner. A compact multi-layer measuring element prepared in this way can be easily mounted in a sensor, particularly a force or pressure sensor, without the risk of inclination.

Abstract: A system and method for measuring absolute pressure applied to a piezoelectric element by measuring a transition time of a voltage pulse applied to a piezoelectric element. The transition time (such as the rise time and/or fall time of the voltage pulse) is affected by the capacitance of the piezoelectric element, which in turn is affected by the amount of pressure currently being applied to the piezoelectric element. The system may also provide haptic feedback via the same piezoelectric element.

Abstract: A system for preloading piezoelectric actuators includes a fixture, a preloading mechanism configured to apply a mechanical force to a piezoelectric element supported by the fixture, and a sensor configured to sense an electrical property induced by the mechanical force in an electrical circuit having the piezoelectric element therein. A control device is coupled with the sensor and configured to generate a signal based on the sensed electrical property. A method of setting or testing preload includes applying a mechanical force to a piezoelectric element, and correlating an electrical property induced by the mechanical force with a magnitude of the mechanical force. Closed loop control allows preload to be set highly accurately.

Abstract: In a polymer actuator provided with a first polymer structural member having a conductive property, an electrolyte retention layer electrically connected to the first polymer structural member, and a second polymer structural member electrically connected to the first polymer structural member through the electrolyte retention layer interposed therebetween and having a conductive property, and by applying a potential difference between the first polymer structural member and the second polymer structural member, the first polymer structural member and the second polymer structural member are allowed to expand and contract, by displacement of the second polymer structural member, the potential difference between the first polymer structural member and the second polymer structural member is changed.

Abstract: A multi-layer strain-amplification device includes at least one first amplifying layer unit and a second amplifying layer unit positioned about the at least one first amplifying layer unit. A strain of the at least one first amplifying layer unit is amplified by the second amplifying layer unit.

Abstract: The invention describes a sensor comprising an element package 2 including piezoelectric elements with an upper area 6 and a lower area 7. A preload sleeve 3 surrounds the said upper area 6 of the said element package 2, while an insulation sleeve 1 sits between the upper area 6 of the said element package 2 and the said preload sleeve 3. An outer housing 4 partially or fully surrounds the said preload sleeve 3 and the lower area 7 of the said element package 2. An insulation part 5 sits between the said lower area 7 of the element package 2 and the said outer housing 4, whereas the said upper area 6 of the said element package 2, the said insulation sleeve 1 and the said preload sleeve 3 have conical shapes and have conforming surfaces. Due to the conical size of the insulation sleeve 1, the load during a shock measurement is distributed on a larger surface area resulting in a reduced compression of the said insulation sleeve. Thereby, the maximum range of the sensor is increased.

Abstract: A system for generating electrical power supply signals includes at least one heat engine having a chamber that undergoes heating/cooling cycle and corresponding pressure variations. At least one piezoelectric transducer is deformed in response to the pressure variations of the heat engine. A power converter transforms the electric signals generated in response to deformation of the piezoelectric transducer(s) to a desired electrical power supply signal. The heat engine preferably uses a geothermal source of cold and an ambient source of hot or vice-versa. Hydrogen can be used as a working fluid, and metal hydride material can be used for absorbing and desorbing hydrogen during the cycle of heating and cooling of the heat engine. A phase change material can also be used. The power converter preferably includes an electromechanical battery with a flywheel storing rotational energy and possibly an electrostatic motor that adds rotational energy to the flywheel.

Abstract: A MEMS structure having a temperature-compensated resonating member is described. The MEMS structure comprises a stress inverter member coupled with a substrate. A resonating member is housed in the stress inverter member and is suspended above the substrate. The MEMS stress inverter member is used to alter the thermal coefficient of frequency of the resonating member by inducing a stress on the resonating member in response to a change in temperature.

Abstract: Piezoelectric transducers and associated methods are disclosed. In one embodiment, a piezoelectric transducer includes a support member, a piezoelectric element attached to the support member, and a pressurized chamber at one side of the piezoelectric element. The piezoelectric element comprises a flexible film, and the pressurized chamber contains a fluid that applies a static pressure to a side of the piezoelectric element.

Abstract: A multifunction sensor system for an electrical machine includes a piezoelectric vibration sensor a resistive temperature and partial discharge sensor which may optionally be integral with the piezoelectric vibration sensor; and packaging enclosing the vibration, the resistive temperature, and the partial discharge sensors.

Abstract: A plurality of exchangeable, different piezoelectric pressure sensors (4) comprise integrated SAW elements (60) as identification units whose identification data can be read by an interrogation unit (3) via a common connection cable (61). The analysis unit (2) for the measurement signals and the interrogation unit (3) for the identification data can be connected by a common coupling unit (5) to the connection cable (61). The coupling unit (5) has a coupling capacity (6) which connects with high frequency the interrogation unit (3) to the signal line of the connection cable (61), as well as a coupling inductance (7) which connects with low frequency the load amplifier (1) of the analysis unit (2) to the connection cable (61), thus neatly separating the useful signal from the identification signal and keeping a high-impedance measurement chain from the sensor (4) to the input of the load amplifier (1). An SFSCW radar can further be used to improve interrogation of the identification data.

Abstract: The invention relates to an input device comprising a first conductive layer, a second conductive layer, and a piezoelectric material layer arranged in between the first conductive layer and the second conductive layer.

Abstract: A triple beam resonator (10) is provided with three beams or tines (12, 14, 16) aligned in parallel alongside each other and joined at a decoupling zone (18) at each end, which is in turn connected to the surrounding material. The central beam (14) is twice the width of the two outer beams (12, 16). The resonating element has a length of 15.5 mm, a thickness of 0.25 mm and beam widths of 2 mm and 1 mm. The distance between the beams is 0.5 mm. Finite element analysis predicts the modal behavior with stress distribution and eigenfrequencies of the resonator (10). Thick-film PZT elements (20, 22) were printed on separate regions at each end of the central beam (14), where maximum stresses exist as the resonator (10) operates in its favored mode of vibration. The PZT element (20) at one end drives the vibrations, while the PZT element (22) at the other end detects them.

Abstract: A movement detector which is rotatably installed on a base member includes a rotating member which has a body portion, and a connecting portion which rotatably connects the body portion to the base member, a piezoelectric layer which is formed on the connecting portion, and a plurality of electrodes which are provided on the piezoelectric layer, to be arranged in a direction of a rotation axis of the body portion, and which detect a voltage generated in the piezoelectric layer corresponding to a deformation of the connecting portion when the body portion has displaced with respect to the base member. Since the piezoelectric layer and the plurality of electrodes are provided to the connecting portion which rotatably connects the body portion to the base member, it is possible to detect a plurality of types of movements of the body portion by the piezoelectric layer and the plurality of electrodes.

Abstract: The invention relates to a component for installation in force or pressure sensors, in particular in a glow plug. The component comprises a disc-type or punched-disc type measuring element consisting of a piezoelectric material, punched-disc type or disc-type electrodes that lie on either side of the measuring element. The electrodes have contact points for contacting conductors. The component comprises in addition a respective transmission body or several transmission bodies that are located outside the electrodes, on either side of the latter. The measuring element, electrodes and transmission bodies are held together mechanically by an external, electrically insulating film.

Abstract: The present invention relates to a new piezoelectric quartz level sensor mainly applied in the attitude stabilized and control system of the aircraft, robot, vehicle, ship, oil drilling platform, construction, industrial automation equipment, radar, and satellite, comprising a sensitive element, signal processing circuit, base, outer case and socket. The piezoelectric quartz level sensor transfers the deflection angle of the object to the force exerted on two symmetrical mounted round piezoelectric quartz wafers, and then utilizing the prominent force sensitivity of the piezoelectric quartz, the level attitude parameter of an objected can be detected through the frequency variation due to the force exerted on the two piezoelectric quartz wafers. Therefore, the present invention can satisfy the demand of high stability and resolution, low non-linear degree, quick start time, wide measuring range and operating temperature, good ability to resist shock, and digital output.

Abstract: A force generator is configured for attachment to a structure in order to controllably introduce vibrational forces into the structure in order to influence the vibration thereof. The force generator encompasses a flexural arm that is fastenable at least at one end to the structure; and an inertial mass that is coupled to the flexural arm remotely from the fastening end of the flexural arm; the flexural arm being equipped with at least one electromagnetic transducer, and a driving system being provided for the transducer, which system is set up such that by driving the transducer, it warps the flexural arm with the inertial mass and the transducer, and thereby displaces the inertial mass, in such a way that vibrational forces of variable amplitude, phase, and frequency are introducible into the structure.

Abstract: A high temperature pressure transducer includes an extended tubular member having an opening from a front to a back surface. The tubular member is preferably fabricated from a metal. At the front end of the tubular member is a ceramic sensor face or tip which basically is a ceramic disk having a curved front surface and having an extending stem and which is inserted into the front opening of the tubular member. The column is of a given length and terminates in a back end. The back end has a predetermined portion which consists of two flat surfaces each on opposite sides. The back end containing the flat surfaces is thinner than the thickness of the column. On these flat surfaces are positioned suitable semiconductor piezoresistors. When a force is applied to the ceramic sensor face, it is transmitted axially through the tube or column where it is received by the sensors positioned on the flats. The sensors produce an output indicative of the force applied.

Abstract: A drive unit includes a guide, a stage which is movable relative to the guide, an ultrasonic actuator for moving the movable body and a control unit for controlling the ultrasonic actuator. The ultrasonic actuator includes a driver element in contact with the stage and is fixed to the guide. A surface of the stage in contact with the driver element is an undulating surface. The control unit detects the position of the stage based on a change in contact pressure on the driver element due to the undulating surface.

Abstract: A knock sensor includes: a base including an annular flange portion and a cylindrical portion, an annular piezoelectric element fitted onto the cylindrical portion, electrode portions oppositely formed on front and rear surfaces of the annular piezoelectric element, first and second terminal plates in contact with the electrode portions, an annular weight, a first insulating sheet interposed between the first terminal plate and the flange portion, a second insulating sheet interposed between the second terminal plate and the weight. The electrode portions include annular partial electrodes each having a width narrower than a radial width of the piezoelectric element. The annular partial electrode has a thickness d satisfying: L/d<80 where L is a radial dimension of outer circumferences of the front and rear surfaces where the electrode portions are not arranged.

Abstract: A piezoelectric composite device including: a feeding electrode; a common electrode; a signal detecting electrode; a first piezoelectric element joined between the feeding electrode and the common electrode; and a second piezoelectric element joined between the common electrode and the signal detecting electrode; a predetermined voltage being supplied between the feeding electrode and the common electrode; and a force detection signal based on an external force being extracted from the detecting electrode.

Abstract: An entrapment detecting system includes a detection portion provided at an opening/closing apparatus for detecting an acceleration thereof on the basis of an output from a piezoelectric sensor for outputting a voltage corresponding to the acceleration and a control portion for judging whether or not an object is entrapped by the opening/closing apparatus on the basis of a detected result of the detection portion. The detection portion includes a current control portion connected to the control portion in series as a closed circuit whereby electricity is supplied from the control portion to the current control portion. The current control portion changes a consumed current of the detection portion on the basis of the output from the piezoelectric sensor. The control portion judges whether or not the object is entrapped on the basis of the consumed current of the detection portion changed by the current control portion.