Showing papers on "Piezoelectric sensor published in 1988"
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08 Sep 1988TL;DR: In this paper, the principal axes of polyvinylidene fluroride (PVDF) laminate are skewed with respect to one another to induce bending and torsional motions.
Abstract: Laminates of polyvinylidene fluroride (PVDF) are employed as piezoelectric sensors and actuators which can sense and/or generate complex motions that include bending, stretching, and twisting components. The laminates can be attached directly to a mechanical structure whose motions are to be sensed and/or controlled. By skewing the principal axes of each of the lamina in the laminate with respect to one another, the laminate is responsive not only to bending motions, but to torsional motions as well. Surface electrodes are disposed on the top and bottom sides of each of the lamina to either sense voltage generated by the lamina in response to motion imparted thereto, or supply voltage to the lamina to induce motion therein. The shape of the surface electrode patterns can be varied to control the particular components of motion to which each of the lamina is responsive (e.g., bending modes). The polarization profile in each of the lamina can also be varied for this purpose. Mechanical oscillators and dampers can be constructed using the laminates.
98 citations
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02 Oct 1988TL;DR: In this paper, a finite element technique for modeling the vibrational behavior of arbitrarily shaped piezoelectric transducers immersed in an acoustic fluid is presented, and the elastic and electrical responses of the piezoclectric structure are computed by pieziolectric finite elements, and wave propagation in the ambient acoustic medium is computed by acoustic finite elements.
Abstract: A finite element technique for modeling the vibrational behavior of arbitrarily shaped piezoelectric transducers immersed in an acoustic fluid is presented. The elastic and electrical responses of the piezoelectric structure are computed by piezoelectric finite elements, and the wave propagation in the ambient acoustic medium is computed by acoustic finite elements. The acoustic feedback of the surrounding acoustic fluid to the piezoelectric solid is considered. This method makes it possible to analyze piezoelectric devices with respect to their mechanical strains and stresses, electrical fields and displacements, and various integral properties, such as the electric input impedance and the electromechanical coupling coefficient. The application of this method to ultrasonic transducers, especially those used in array antennas, is reported. >
76 citations
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29 Mar 1988TL;DR: In this paper, a collision detection system for a vehicle comprising an acceleration sensor and a signal processing circuit coupled to a piezoelectric sensor is presented, where the acceleration sensor is mounted on a pendulum such that when the vehicle accelerates or decelerates, the pendulum moves relative to the vehicle thereby distorting the sensor, whereby the sensor produces an output as a function of the distortion.
Abstract: A collision detection system for a vehicle comprising an acceleration sensor for sensing the acceleration and deceleration of the vehicle wherein the acceleration sensor is a piezoelectric sensor; signal processing circuit coupled to the piezoelectric sensor for generating a first output when the vehicle deceleration is greater than a predetermined amount. A diagnostic pulse generator is coupled to the piezoelectric sensor for applying a diagnostic pulse to the piezoelectric sensor for distorting the piezoelectric sensor, thereby causing the piezoelectric sensor to generate an electrical output. The electrical output is applied to the signal processing circuit wherein the signal processing circuit produces a second output in response thereto. The piezoelectric sensor is mounted on a pendulum such that when the vehicle accelerates or decelerates, the pendulum moves relative to the vehicle thereby distorting the piezoelectric sensor whereby the piezoelectric sensor produces an output as a function of the distortion. The piezoelectric sensor includes an electrode which is divided into a plurality of electrode segments. At least one of the electrode segments is an output electrode for providing an electrical signal as a function of the distortion of the piezoelectric sensor and at least one of the electrode segments is an input electrode for receiving an electrical signal and distorting the piezoelectric sensor in response thereto.
55 citations
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08 Feb 1988TL;DR: In this article, a piezoelectric actuator control apparatus consisting of a capacitor connected in series with an actuator that has electrodes, and a control device that controls the voltage applied to the capacitor such that the voltage of the capacitor will reach a predetermined value, is described.
Abstract: Disclosed herein are a piezoelectric actuator control apparatus comprising a capacitor connected in series with a piezoelectric actuator that has electrodes, and a control device that controls the voltage applied to the piezoelectric actuator such that the voltage of the capacitor will reach a predetermined value, as well as a piezoelectric actuator control apparatus comprising an integrating circuit connected to one electrode of a piezoelectric actuator that has electrodes, and a control device that controls the voltage of the other electrode of the piezoelectric actuator such that the output of the integration circuit will assume a predetermined magnitude.
42 citations
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TL;DR: In this article, a small portion of a piezoelectric sensor is used to form the feedback capacitor of the amplifier, which has the same effect on the sensor and on the capacitor.
Abstract: To compensate for the effect of external parameters on piezoelectric sensors connected to a charge amplifier, a small portion of this sensor is used to form the feedback capacitor of the amplifier. These parameters then have the same effect on the sensor and on the capacitor, thus making it possible to provide compensation to hydrophones made of piezoelectric polymer material.
26 citations
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04 Nov 1988TL;DR: In this paper, the shape of the piezoelectric body has been chosen in such a way that only the directional component which is parallel to a given body axis (h) of the PBE can cause a change in the length of the glass fiber by means of an inverse piezelectric effect, which is measured interferometrically.
Abstract: A fibre-optic sensor for measuring a particular directional component of an electric field comprises a piezoelectric body (4) and a glass fiber (5a) which is rigidly connected to the piezoelectric body (4) in a given length section. A crystal class and a crystallographic orientation of the piezoelectric body (4) is selected in such a manner that only the directional component which is parallel to a given body axis (h) of the piezoelectric body (4) causes a change in a length of the glass fiber (a) by means of an inverse piezoelectric effect. The change in length is measured interferometrically. In a preferred embodiment, the piezoelectric body has the shape of a disk, of a plate or of a hollow cylinder.
24 citations
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TL;DR: In this article, the authors describe the principle and design of an AC high-voltage sensor, which accurately detects the mechanical strain of a piezoelectric transducer on which a foil strain gage is cemented.
Abstract: The authors describe the principle and design of an AC high-voltage sensor. When an electric stress is applied, this sensor accurately detects the mechanical strain of a piezoelectric transducer on which a foil strain gage is cemented. Two types of these sensors were designed, and a high-voltage measuring system using them was manufactured for trial. To confirm the frequency response of the trial sensors, an impedance of the trial piezoelectric transducer was performed using a YHP impedance analyzer, and the response-confirmation test of its vibration mode was carried out at the same time. Theoretical and experimental analyses are discussed in terms of the relation between the strain on the piezoelectric transducer and the applied sinusoidal AC voltage. It was ascertained that the strain was directly proportional to the voltage measured, and it was found that the measured percentage errors were less than +or-2% for voltages up to 26000 V/sub p-p/. >
17 citations
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20 May 1988
TL;DR: In this paper, a parallel connection of the piezoelectric elements of the bimorphic membrane of bimodal construction is proposed, by means of which an influence of differences of the electrical characteristics such as, for example, temperature-dependent characteristics of the Piezoeel elements, electrostatic capacitance differences and insulation resistance differences are suppressed.
Abstract: A piezoelectric sensor having parallel connection of the piezoelectric elements of the piezoelectric membrane of bimorphic construction, by means of which an influence of differences of the electrical characteristics such as, for example, temperature-dependent characteristics of the piezoelectric elements, electrostatic capacitance differences and insulation resistance differences are suppressed, so that, by means of the parallel connection of the piezoelectric elements, the level of the disturbance components which depends on a temperature fluctuation is reduced to half the level which occurs in a traditional sensor in which the piezoelectric elements are connected in series.
12 citations
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11 citations
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08 Dec 1988
TL;DR: In this paper, an ultrasonic ice presence detector with a transducer and a piezoelectric sensor coupled to one end of an acoustic delay line in the form of a rod is presented.
Abstract: An ultrasonic ice presence detector includes a transmit/receive piezoelectric sensor (10) coupled to one end of an acoustic delay line in the form of a rod (20) with the other end (26) of the rod co-aligned with the surface of an aerofoil (18). The transducer is excited by an electrical pulse to transmit an ultrasonic pulse along the rod to the sensing surface (26) as a function of the acoustic impedance at the sensing surface/air interface. When ice accumulates on the sensing surface, the acoustic impedance at the interface is altered to change the magnitude of the reflected energy. An acoustic discontinuity (30) of known characteristics is provided in the acoustic delay line (20) so that the magnitude of a first reflected pulse of known characteristics is sensed by the transducer and compared with the magnitude of a second, following pulse representative of the acoustic impedance at the sensing surface (26), thereby enabling self-calibration of the system during each cycle so that sensing is independent of various error sources in the system.
9 citations
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30 Mar 1988
TL;DR: In this article, the authors proposed a digital temperature compensating circuit for a voltage control piezoelectric oscillator with a temperature detector and a memory circuit to improve the frequency temperature characteristic and increase stability.
Abstract: PURPOSE: To drastically improve a frequency temperature characteristic and to increase stability by providing a piezoelectric oscillator having a voltage control function in a constant temperature bath type piezoelectric oscillator and digital-temperature- compensating a voltage control piezoelectric oscillator with a digital temperature compensating circuit CONSTITUTION: A piezoelectric oscillator 9 having a voltage control function is connected to a piezoelectric oscillator 1 housed in an heat insulated container 6, a constant temperature bath type piezoelectric oscillator 7' is composed, and further, a digital temperature compensating circuit 15 composed of a temperature detector 11, an analog- digital converter 12 and a memory circuit 13 and a digital-analog converter 14 is connected to a voltage control terminal 10 of the piezoelectric oscillator 9 and a constant temperature bath type piezoelectric oscillator 16 is composed The ambient temperature of the constant temperature bath type piezoelectric oscillator 7' is detected by the temperature detector 11 and the detecting output is supplied through the analog digital converter 12 to a memory circuit 13 A temperature compensating digital code corresponding to the digital code of the converter 12 is stored in the memory circuit 12 beforehand and the frequency temperature characteristic of the constant temperature bath type piezoelectric oscillator 7' is digital-temperature-compensated COPYRIGHT: (C)1989,JPO&Japio
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08 Apr 1988
TL;DR: In this paper, the effect of external parameters on piezoelectric sensors connected to a charge amplifier is compensated by using a small portion of this sensor for forming the capacitor (22) against the feedback amplifier (310).
Abstract: L'invention concerne la compensation de l'effet des parametres exterieurs sur les capteurs piezoelectriques connectes a un amplificateur de charge. The invention relates to the compensation of the effect of external parameters on piezoelectric sensors connected to a charge amplifier. Elle consiste a utiliser une petite portion (36) de ce capteur (300) pour former le condensateur (22) de contre-reaction de l'amplificateur (310). It consists of using a small portion (36) of this sensor (300) for forming the capacitor (22) against the feedback amplifier (310). L'effet de ces parametres est alors le meme sur le capteur et sur le condensateur. The effect of these parameters is the same on the sensor and on the capacitor. Elle permet de compenser les hydrophones en materiau polymere piezoelectrique. It compensates the hydrophones piezoelectric polymer material.
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29 Jul 1988
TL;DR: In this article, a piezoelectric exciter 1 is mounted on a metal part 2 at the end of a block drum 012 for a printing machine and an output from this exciter is supplied to an indicator 9 through an amplifier 7 and a filter 8.
Abstract: PURPOSE:To measure with high accuracy and high efficiency by providing an ultrasonic transmitter and an ultrasonic receiver respectively on the contact part of two adjacent objects. CONSTITUTION:A piezoelectric exciter 1 is mounted on a metal part 2 at the end of a block drum 012 for a printing machine. The ultrasonic wave 4 is generated by this piezoelectric exciter 1 furnished with an input from a signal generator 3. The ultrasonic wave 4 generated from the piezoelectric exciter 1 is received by a piezoelectric sensor 5 which is mounted on the metal part 6 at the end of a press drum 013. An output from this piezoelectric sensor 5 is supplied to an indicator 9 through an amplifier 7 and a filter 8. A contact load between the press drums 012 and 013 can be estimated by an indication on the indicator 9.
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TL;DR: In this article, an accelerometer for blast monitoring comprises at least one piezoelectric transducer having a picolectric membrane attached along the edge thereof to the sidewall of a suitable container and mounted for free movement in such container for generating a high impedance electrical output signal upon deformation of the pico-lectric membrance by vibration during a blast.
Abstract: An accelerometer for blast monitoring comprises at least one piezoelectric transducer having a piezoelectric membrane attached along the edge thereof to the sidewall of a suitable container and mounted for free movement in such container for generating a high impedance electrical output signal upon deformation of the piezoelectric membrance by vibration during a blast, a high to low impedance converter connected to the piezoelectric membrane for converting the high output impedance of the piezoelectric membrane into a low impedance signal for transmission through long cables to recording equipment, and means for encapsulating the piezoelectric transducer and converter into epoxy or other solid material to minimize response of the transducer to surrounding acoustic signals.
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23 Aug 1988TL;DR: In this paper, the authors proposed to use piezoelectric ceramics and an organic substance in a complex PZT system to make smaller density, make smaller acoustic impedance and to make a value closer to the acoustic impedance of water and organism.
Abstract: PURPOSE: To make smaller density, to make smaller acoustic impedance and to make a value closer to the acoustic impedance of water and organism by providing piezoelectric ceramics and an organic substance in a complex piezoelectric vibrator to be used for supersonic probe and forming a hole. CONSTITUTION: One piece of piezoelectric plate of a PZT system of a desired thickness is cut into a mesh shape, divided and the multiple pieces of pillar shaped piezoelectric ceramics 1 are two-dimensionally arranged. The both end surfaces of the pillar-shaped piezoelectric ceramics 1 are sandwiched by the film-shaped epoxy resin of self-adhesion type being organic high polymer material, this film-shaped epoxy resin 2 of the self-adhesion type is heated under pressurized condition, adheres to the pillarshaped piezoelectric ceramics 1 and hardened. Since this film-shaped epoxy resin 2 of the self-adhesion type is a type to adhere with softening, it does not flow into the gap part of the pillar- shaped piezoelectric ceramics 1 and fixes the piezoelectric ceramics. Thus, the gap part of the pillar-shaped piezoelectric ceramics 1 is kept in the condition of a hole 3. An electric pole 4 is vaperdeposited on the external surface of the epoxy resin or galvanized. COPYRIGHT: (C)1990,JPO&Japio
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22 Sep 1988
TL;DR: In this paper, a device is specified for triggering an explosive charge by means of electrical current, which device is used, for example, for inflating a crush protection airbag arranged in a vehicle.
Abstract: A device is specified for triggering an explosive charge (10) by means of electrical current, which device is used, for example, for inflating a crush-protection airbag arranged in a vehicle. A piezoelectric sensor cable (4) is used as a voltage source, against which sensor cable (4) a weight (8) acts in the event of the vehicle striking obstructions. The weight (8) is arranged such that it can move freely in the driving motion direction of the vehicle (arrow 9).
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01 Jan 1988TL;DR: In this article, the surface photovoltage is reported to be one of the factors that gives contributions to the piezoelectric signal in image-acoustic detection.
Abstract: Photoacoustic detection by a piezoelectric sensor often gives results different from those obtained by other methods such as gas-microphone detection. Elastic waves induced by sample bending’, or the existence of defects or some other phase in the sample, which influences the propagation of the acoustic wave, etc., are all possible explanations. Here I report another cause, the surface photovoltage, that gives contributions to piezoelectric signal.
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27 Oct 1988
TL;DR: In this article, the authors used a piezoelectric sensor for counting mass produced articles such as tablets, pills, suppositories, cereals, screws or nails in free fall on an incline.
Abstract: The electrical counting of mass produced articles such as tablets, pills, suppositories, cereals, screws or nails is effected by dropping them in free fall on an incline (1) in which a circular recess (2) is covered by an elastic plastic foil (4) with a piezoelectric sensor (5) bonded to the underside. The signal produced by the impact on the sensor is picked up on the terminals (6, 7) and used as a counting pulse. Alternatively this sensor can be replaced by a loudspeaker diaphragm. ADVANTAGE - Thisis very simple and records even the fall of almost simultaneously dropping articles.
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14 Dec 1988TL;DR: In this paper, a tubular piezoelectric sensor of the type comprising at least one sensitive element is arranged against the outer surface of the tubular support, and the entire remaining volume is filled with liquid.
Abstract: Tubular piezoelectric sensor of the type comprising at least one sensitive element (1) arranged against the outer surface of a tubular support (5). A substance (6), the acoustic impedance of which differs greatly from that of the material forming the tubular support (5), is arranged inside the latter, and the entire remaining volume is filled with liquid. Strands of glass fibres or open-cell foams, for example, are employed. The liquid can, for example, be that which fills a seismic flute (8), in which case the tubular support is left open. It can also be closed at its two ends by means of sealing capsules enclosed in a protective sheath (7). The dimensions of the support and the material of which it is made are selected so as to optimise the sensitivity of the piezoelectric sensor. The invention is used for producing, for example, hydrophones resistant to hydrostatic pressure.
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25 Apr 1988
TL;DR: In this paper, a tuning fork type crystal piece is put in the container to constitute a tuning force type piezoelectric sensor, whose output is inputted to a computing element 20 through lead lines 15a and 15b and an oscillator 19.
Abstract: PURPOSE:To prevent a piezoelectric body from being broken and to contrive to improve detection accuracy by putting a tuning fork type crystal piece in a container and detecting an external force from variation in vibration characteristics due to the acoustic leak energy of a tuning force type vibrator. CONSTITUTION:The tuning force type crystal piece is put in the container to constitute a tuning force type piezoelectric sensor 18, whose output is inputted to a computing element 20 through lead lines 15a and 15b and an oscillator 19. When the external force F is applied to the sensor 18, the sensor 18 varies in the acoustic coupling strength of the outer peripheral part of its base 10 according to the external force F and then the acoustic leak energy increases, so that the quantity of variation from a reference frequency when the external force F is zero increases. This variation quantity is computed by the computing element 20 to find the external force value, which is displayed as a digital value on a display device 21. Therefore, the tuning fork type crystal piece is in the container and never touches the external force F directly, so the tuning fork type crystal piece is prevented from being broken and decreasing in detection accuracy owing to fine dust.
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22 Aug 1988
TL;DR: In this article, a method and at the same time a device for measuring pressures and forces acting on bodies of any shape are disclosed, where a piezoelectric film is used which is provided on both sides with a metal coating.
Abstract: A method and at the same time a device for measuring pressures and forces acting on bodies of any shape are disclosed. A piezoelectric film is used which is provided on both sides with a metal coating. The piezoelectric film is bonded onto the body and a change in charge of the piezoelectric film is evaluated in an evaluation unit and used as a measure of the force or pressure acting on the body. On one side of the piezoelectric film (2) the metal coating (5) is partially removed, forming individual sensors (3, 4). Each individual sensor (3, 4) is coupled to the evaluation unit (10) via an electrical connection (8, 9). The other side of the piezoelectric film (2) with the continuous metal coating (5) serves as an electronic shield and is connected to earth (7). The change in charge of each individual sensor (3, 4) serves as a measure for the local force or the local pressure. … …
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TL;DR: In this article, a study was made of the deformation of a rod-type piezoelectric sensor subjected to preliminary static compression and subsequent vibrational loading by means of electrical harmonic excitation.
Abstract: 1.
The finite elements method was used to develop an algorithm for calculating the natural frequencies and modes and the stress-strain state of piezoelectric sensors in an axisymmetric formulation.
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A study was made of the deformation of a rod-type piezoelectric sensor subjected to preliminary static compression and subsequent vibrational loading by means of electrical harmonic excitation.
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It was shown that the stress distribution in the piezoelements is nonuniform due to design features of the sensor.
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It was established that an increase in the stiffness of the intermediate disk between the piezoceramic column and the radial cover plate of the sensor lowers the tensile hoop stresses in the adjacent piezoelement by 15–20%.