Showing papers on "Interdigital transducer published in 1986"

Piezoelectric ultrasonic transducer with acoustic matching plate

Abstract: A monolithic array ultrasonic transducer has a plurality of transducer elements formed thereon by isolating metallized areas on a piezoelectric plate without cutting the piezoelectric plate apart for each transducer element, and an acoustic matching layer having a longitudinal wave velocity within ±25% of a longitudinal wave velocity of the piezoelectric plate and a thickness equal to one half of that of the piezoelectric plate. The acoustic matching layer suppresses the radiation to an object of a partial wave in a direction of 60° to a normal line to the plane of the piezoelectric plate.

Resonator using high coupling love wave type saw substrate

Abstract: PURPOSE: To obtain a small-sized resonator with a very small capacitance ratio by adding a heavy metal interdigital transducer electrode to a prescribed rotation Y-cut LiNbO 3 substrate surface and exciting and propagating a surface acoustic wave in a direction of the substrate CONSTITUTION: The resonator is constituted by adding an IDT (heavy metal interdigital transducer) electrode to the surface of a rotation Y-cut LiNbO 3 substrate and exciting and propagating a SAW (surface acoustic wave) in a direction X of the substrate As the rotation Y-cut LiNbO 3 substrate, the rotation Y-cut LiNbO 3 substrate is used, whose rotation angle is selected in a way that the electromechanical coupling coefficient as to the Love wave stimulated in the substrate is large and that of the SAW stimulated at the same time is small Moreover, as the IDT electrode, an electrode made of Au, Ag or Pt is used Then the frequency-temperature characteristic is improved by coating SiO 2 of a prescribed thickness onto the surface of the substrate COPYRIGHT: (C)1988,JPO&Japio

Piezoelectric transducer for transmitting or receiving ultrasonic waves

Abstract: A piezoelectric transducer in which a casing is mounted in a sealing manner on a base member for supporting two rod-shaped terminals, a piezoelectric element is bonded to the inner surface of said casing, and electrodes on the front and back surfaces of said piezoelectric element are electrically connected to said terminals. The transducer is supported at the position of a node of the free oscillation mode or the forced oscillation mode. The interior of the casing in the transducer is filled with nitrogen gas.

Dispersive interdigital transducer for arrangements operating with acoustic waves

Abstract: A dispersive transducer 100 which has non-equidistant distribution of the finger electrodes 6, 7, 16 and 17 according to band-width such that the finger electrodes 16 and 17 of the low frequency portion 11 of the transducer have a width c and spacing d1 (or d2) which are equal to the corresponding portions of the highest frequency part 13 of the transducer such that reflections are substantially reduced or eliminated.

Acoustic surface wave filter bank

Abstract: An acoustic surface wave filter bank consisting of a single or a plurality of piezoelectric substrates on which a plurality of acoustic surface wave filters each comprising an input interdigital transducer and an output interdigital transducer are fabricated, wherein center frequencies of adjacently located filters are not adjacent to center frequency of present filter so that leaked acoustic surface waves to the present filter from adjacently located filters are strongly attenuated.

Acoustic piezoelectric power transducer

Abstract: An acoustic piezoelectric power transducer of sandwich shape with supply conductors pressed into grooves in the electrically conductive metal inserts and/or the piezoelectric plates.

Internal reflection type unidirectional surface acoustic wave converter having floating electrode

Abstract: PURPOSE:To offer a surface acoustic wave unidirectional converter with simple manufacturing constitution of device and requiring no circuit to be outfitted such as a phase device and with low loss by employing such structure that the electrode width of the positive and negative electrode fingers of an interdigital transducer(IDT) are varied and an open-type floating electrode is inserted between them. CONSTITUTION:The converter is a unidirectional converter in which each electrode width is set at lambda/8, and each inter-electrode distance at lambda/4, and which is connected with positive electrode fingers 9, 10 and a short-circuit electrode finger 13, and the cycles of short-circuit type floating electrode fingers 11, 12, open-type floating electrode fingers 14, 15, and the negative electrode fingers 16, 17 are set as half cycles. At such a case, it is possible to obtain a satisfactory unidirectional converter with wide electrode width by employing an internal reflection type unidirectional converter with structure in which the short-circuit type floating electrode fingers 11, 13 between positive and negative electrodes are connected to short-circuit type floating electrode fingers 18, 19 between them, and having the floating electrode in which the values of the electrode width lambda/8 and the inter-electrode distance lambda/4 are set within a range of + or -80%.

General Two-Dimensional Planar Transducers and Blazed Array-Like Interdigital Transducer

Abstract: Previous work on W has been focused on one-dimensional features. new applications. dimensional planar piezo-electric transducers and an example of thea with application to spectrum analysis leads to precise closed-form expressions for wave fields, transducer and transfer admittances, and a general proot of transducer and transfer reciprocities mves. By introducing and generalizing the concept of reciprocal structure and Euald's construction, all-known in diffraction physics, we find the analysis of SClW very simple. As an example, the theory is applied to the blazed array-like interdigital transducer (BCIIDT) proposed by the authors. This two-diincnsional transducer produces SRO beams scanning with frequency, and can be used in spectrum awlysers and channelizers with great feasibility. Experiments are made with BFIIDT. The scanning angle, beam divergence angle and beam intensity are all in agreement with tb theory. Sone structures for analyser implementation are also discussed. It is expected that two-dimsional features uill find In this paper, we give a general theory for twoUse

Electrode structure of idt excitation energy confinement type piezoelectric device

Abstract: PURPOSE:To decrease spurious response by providing an IDT having a specific width or a region having no reflector to a gap between a transducer (IDT) electrode and a reflector arranged at both sides of the IDT along the progressing direction of a surface acoustic wave (SAW). CONSTITUTION:When a double mode SAW filter where spurious response appears remarkably is selected, a gap (l) is selected stepwise from 1/2lambda-7/24L, and each spurious response is checked, then both the spuriousness by the 3-dimensional smmetrical mode and of the unsymmetrical mode are almost lost with l=1/6L, and the adequancy of the theory is proved, but the spuriousness is decreased by nearly 10dB with l=1/12L or 3/12L, which shows the device is diffuciently in practical use. Thus, the IDT2 having a width of 1/12-3/12L of the inner gap of a reflector 3 or a region having no reflector 3 is provided to the gap between the electrode of the interdigital transducer (IRD)2 and the reflectors 3, 3 arranged at both sides of the IDT2.

Planar Ultrasonic Transducers Using LiTaO3Poled with Interdigital Electrodes

Abstract: It is demonstrated that an array of alternating polarity antiparallel domains can be formed along the surface of a LiTaO3 crystal by poling with interdigital electrodes on the surface. Combination of the domain array and the interdigital electrodes can be utilized for generation and reception of bulk waves propagating in the direction normal to the surface. The characteristics of such ultrasonic transducers are reported.

Leakage surface acoustic wave transducer

Abstract: PURPOSE:To improve the radiation of an ultrasonic wave into a liquid by provid ing a piezoelectric thin film so as to cover a reed screen electrode provided on one face of a dielectric substrate or a semiconductor substrate and bringing the piezoelectric thin film into contact with the liquid. CONSTITUTION:A protection film 22 (film thickness h2) made of SiO2 is provided on a ZnO thin film 10 of an interdigital transducer. The peak of a conversion efficiency eta calculated by using a product between the film thickness h2 and a frequency (f) as a parameter is increased as the fh2 increases once and then decreased, then it is possible to give a function of the protection film without losing the characteristic as the transducer by selecting a proper SiO2 film thick ness h2. Further, the conversion efficiency eta is given by a product between the imaginary part of the propagation speed and an electromechanical coupling factor k . Thus, an ultrasonic wave is radiated efficiently into a liquid.

Surface acoustic wave resonator

Abstract: PURPOSE: To reduce spuriousness which occurs above and below a desired resonance frequency by specifying the attenuation pole frequency of conductance frequency characteristic of an interdigital transducer. CONSTITUTION: An IDT 3 is composed of a couple of comb-shaped electrodes 2 and 2 formed on a piezoelectric substrate 1 of crystal, etc., and reflectors 4 and 4 equipped with many metallic strips are formed on both sides of the IDT 3. Then, the attenuation pole of the conductance of the IDT is so adjusted that a frequency at which a standing wave having a wave number one less than the wave number at a desired resonance frequency f 0 is almost equal to a frequency f 2 at which a standing wave with a wave number one larger than that at the resonance frequency f 0 . Consequently, the inductance values of the IDT at the frequencies f 1 and f 2 become extremely small and spuriousness at the frequencies f 1 and f 2 is suppressed specially effectively. COPYRIGHT: (C)1987,JPO&Japio

Ultrasonic optical modulating device

Abstract: PURPOSE:To obtain the ultrasonic optical modulating device which is easily constituted and assembled and superior in cost by imposing modulation by varying an input voltage or frequency supplied from an oscillator to an interdigital transducer. CONSTITUTION:When a light beam from an He-Ne laser 20 is entered into a liquid through a window 11, the light beam is diffracted by the sound field in the liquid to obtain a diffraction pattern shown by a reference number 26 in a figure. This diffraction pattern varies with the voltage or frequency of an electric signal applied to the intergidital transducer 13. In concrete, each peak value of the diffraction pattern varies as the input voltage is varied, and the diffraction angle theta of the diffraction pattern varies as the frequency is varied. For example, the output voltage of the oscillator 19 is varied as a modulating signal and variation in the intensity of diffracted light of specific degree in the diffraction pattern is detected electrically through a photodetecting element 22 and an amplifying circuit 24 to obtain a modulated signal corresponding to the variation in the output voltage of the oscillator 19 at an output terminal 25.

Narrowband multi-channel surface acoustic wave filter

Abstract: A multi-channel surface acoustic wave filter with narrow bandwidth is realized by using an output interdigital transducer composed of multiple electrode groups. The filter characteristics are related to the number of the electrode group and the apodization of the overlap length of the interdigital electrodes. A Z-Y propagating LiNbO3 SAW multi-channel filter around 495 MHz is demonstrated which is in good accordance with a simulated result.

Precise keasurement of saw velocity wit11 an interdigital transducer

Abstract: A method of measuring the acoustic properties of materials using an interdigita1 transducer (IDT) for nondestructive evaluation (NDE) is described. An IDT can efficiently radiate acoustic waves directly into a liquid so that it is used as the acoutic wave transducer in the NDE system. In this paper, a new method for the measuring of SAW velocity by using the IDT is described. The output voltage is measured as a function of the frequency of the acoustic wave in the NDE system using an IDT. The SAW velocity is obtained from the frequency dependence. Measurement are made for an anisotropic materials at frequencies from 15 to 25 I'IIJz. The experimental results obtained in this manner agreed well with the theoretical ones.

Dispersive interdigital transducer for devices operating with acoustical waves

Abstract: Dispersiver Wandler (100) mit seiner Bandbreite entsprechend nicht-aquidistanter Verteilung der Finger elektroden (6, 7, 16, 17), wobei die Fingerelektroden (16, 17) des niederfrequenteren Anteils (11) des Wandlers Breite c und Abstande d₁ (oder d ) haben, die gleich denjenigen des hochstfrequenten Anteils (13) des Wandlers sind. D₁ dispersive transducer (100) with its bandwidth in accordance with non-equidistant distribution of the electrode fingers (6, 7, 16, 17), said finger electrodes (16, 17) of the lower-frequency portion (11) of the transducer width c and spacing (or d ) have, which are identical to those of the highest frequency component (13) of the transducer.

Influence of film thickness on the performance of leaky surface acoustic wave transducers of ZnO on fused quartz

Abstract: A numerical analysis of leaky surface acoustic wave transducers consisting of a ZnO thin film on fused quartz is described in terms of the film thickness. The interdigital transducer (IDT) used for the structure operates effectively for the construction of a ZnO/IDT/fused quartz plate. The efficiency of radiation of the acoustic beam into water exhibits double peaks.