Abstract: A surface elastic wave filter for processing a supplied signal into a signal with nonlinear-phase frequency characteristics has a piezoelectric substrate for propagating a surface elastic wave through a surface layer thereof and spaced input and output electrodes disposed on the surface layer for sending and receiving the surface elastic wave. Each of the input and output electrodes has a pair of common electrodes having comb-shaped interdigitating electrode fingers extending therebetween. The central electrode fingers of the input and output electrodes have central axes across the direction of propagation of the surface elastic wave. The distance along the direction of propagation between the central axes is varied in the direction substantially normal to the direction of propagation.

Abstract: In a SAW convolver having a multi-layer structure consisting of a piezoelectric layer, insulation layer and semiconductor layer and having at least one combshaped electrode fed with an input signal and a gate electrode for exerting a convolution output, an interface in the form of a jaggedness is formed between the insulation layer and the semiconductor layer to improve the convolution efficiency.

Abstract: A surface transverse wave resonator comprises a piezoelectric substrate having at least one surface, wherein said substrate includes a crystalline structure that permits the propagation of transverse waves. The resonator also comprises a transducing set of periodic perturbations which are positioned atop the substrate surface, wherein the transducing set converts electromagnetic energy from an external source into the transverse waves. The resonator further comprises a receiving set of periodic perturbations which are positioned atop the substrate surface remote of the transducing set of periodic perturbations, wherein the receiving set converts the transverse waves into resultant electromagnetic energy. Moreover, the resonator includes a central set of surface-trapping periodic perturbations for maintaining the transverse waves adjacent to the substrate surface, wherein the central set is positioned intermediate the transducing set and the receiving set.

Abstract: A surface acoustic wave convolver comprises:a piezoelectric substrate:plural input transducers formed on the substrate and adapted for respectively generating a surface acoustic wave corresponding to an input signal; andan output transducer for interferring thus generated surface acoustic wave and obtaining a convolution signal of the input signal from a surface wave generated by thus interfered surface acoustic wave, wherein the output transducer is formed by first and second output electrodes provided in parallel manner between the input transducers and having mutually different lengths along the propagating direction of the surface acoustic wave.

Abstract: A surface acoustic wave device is disclosed which performs frequency channelization in a relatively small volume. The invention utilizes a wide band incline step frequency transducer each step feeding an independent beam width compressor waveguide combination. The waveguides fan out with a wide radius of curvature to contain the wave in off pure mode axis propagation. The output of each waveguide then feeds an independent beam width expander and frequency selector interdigital transducer. The use of the waveguides as a tapping and narrow aperture transport mechanism minimizes defraction, allows the output transducers to be widely separated achieving isolation and permits a larger number of filters per substrate.

Abstract: A balance-to-unbalance matching network for a surface acoustic wave device is provided in the form of a transmission line wound around a toroidal coil and having a length shorter than 1/4 the wave length at the frequency of induced acoustic waves, to provide an inductance component to cancel the susceptance of the transducer. In one embodiment the lines are would and connected to the magnetically coupled to the core so that magnetic fields are produced in the same direction by means of currents flowing into the line sections.

Abstract: In a surface acoustic wave element comprising a semiconductor substrate, a piezoelectric layer formed thereon and at least one interdigital electrode disposed on the surface thereof, a semiconductor region having a conductivity type different from that of the semiconductor substrate is disposed on the outer side of the interdigital electrode just below the piezoelectric layer.

Abstract: A SAW slanted array correlator (SAC) comprises a piezoelectric substrate, input and an output interdigital transducer deposited on the piezoelectric substrate, a reflective array aligned with the transducers, and an acoustic absorbing film disposed on the substrate between the output transducer and the reflective array. The input and output transducer are slanted at equal and opposite appropriate angles to each other. The reflective array is disposed on the substrate at an angle the same as the angle of emplacement of the output transducer. The transducers comprise a number of interdigital electrodes with varying periodicity, the periodicity being the same for corresponding portions of the two transducers. The reflective array comprises a number of shorted electrodes having a periodicity corresponding to the periodicity of the output transducer. The acoustic absorbing film has a non-uniform width with selected portions having little or no width.

Abstract: A technique for adjusting the frequency of odd mode transverse waves propagating in a SAW device is described. A pair of localized regions of frequency determining trimming material are deposited onto selected portions of a surface wave propagating surface, to provide localized regions on said surface where the odd order transverse mode has energy maxima. These regions change the acoustic properties and hence the velocity characteristics of the surface wave propagating surface in said regions. The frequency of the odd mode transverse wave is changed accordingly and is preferably changed to match that of the fundamental transverse propagating wave. This decreases the insertion loss of the device at the fundamental frequency and eliminates the odd mode transverse wave propagation characteristic within the operating frequency range of the resonator.

Abstract: A surface acoustic wave (SAW) device is provided which includes a piezoelectric substrate, an input transducer formed on the substrate for launching acoustic surface waves along a propagation path on the substrate, an output transducer formed on the substrate across the propagation path from the input transducer for receiving acoustic surface waves generated by the input transducer, and at least one area of acoustic energy absorbing material, preferably polyimide, formed on the substrate between the edge of the substrate and a corresponding transducer. The acoustic absorber is patterned on the SAW device substrate while the device is still in wafer form using photolithographic processing techniques.

Abstract: A grating is positioned on a surface acoustic wave device on a first axis in-line with the delay line for substantially reducing the amount of energy reflected on that axis to the transmitter and receiver. The grating site on the first axis at a position between the delay line and one of the edges of the device. The grating is comprised of a parallel series of grating members each oriented so as to extend at a first angle relative to the first axis, the grating members being generally longitudinally bisected by that axis. An optimum value for the first angle is provided by a theoretical analysis, and experimental results are presented. On the experimental device, the grating is defined by a series of parallel grooves formed in the surface of the device; however, the grating may also be defined by a series of metallic strips mounted on the surface of the device.

Abstract: A SAW slanted array correlator (SAC) comprises a piezoelectric substrate, an input and an output interdigital transducer deposited on the piezoelectric substrate, and a reflective array aligned with the transducers. The input and output transducer are slanted at equal and opposite appropriate angles to each other. The reflective array is disposed on the substrate at an angle the same as the angle of emplacement of the output transducer. The transducers comprise a number of interdigital electrodes with varying periodicity, the periodicity being the same for corresponding portions of the two transducers. The reflective array comprises a number of shorted interdigital electrodes having a periodicity corresponding to the periodicity of the output transducer. The reflective array comprises portion of selected electrodes which are active, partially active or inactive.

Abstract: In order to obtain greater flexibility in the design of a linear-phase electrical filter comprising an acoustic surface wave device including a pair of apodized transducers intercoupled by means of a multi-strip coupler, for example to obtain more equal contributions by the two transducers to the gain versus frequency characteristic of the filter, the transducers are apodized differently but have mutually complementary non-linear phase characteristics. First a transfer characteristic corresponding to the collective contribution to the desired overall gain versus frequency characteristic of the filter, is derived in terms of the z-transform and the roots or the reciprocals of the roots of the resulting polynomial in z.sup.-1 are found. These roots or reciprocals are then divided into two groups so that at least one pair of non-identical roots or reciprocals which have equal ratios between their real and imaginary parts and the product of the moduli of which is equal to unity are included one in each group.

Abstract: In a three-transducer surface acoustic wave device, an apodized electrode member is interposed between two interdigital electrode members, each having first and second ends and comprising interdigital electrodes between the first and the second ends either with a uniform density distribution or with a density distribution varied according to a prescribed rule of selective withdrawal of the interdigital electrodes. The apodized electrode member has first and second extremities and is given substantially minimum-phase and maximum-phase impulse responses for surface acoustic waves which are propagated either into or out of the apodized electrode member through one and the other of the extremities. Alternatively, an interdigital electrode member is interposed between two apodized electrode members. Each of the interdigital and the apodized electrode members is of the type described above. One of the apodized electrode member should have a substantially minimum-phase impulse response.

Abstract: A SAW convolver is disclosed, in which an auxiliary electrode is disposed between the gate electrode and each of two input electrodes and self convolution is reduced by applying to the auxiliary electrodes such a bias voltage that the portion of the semiconductor layer below each auxiliary electrode is inverted.

Abstract: A surface-acoustic-wave convolver includes a refraction means provided between two input electrodes to refract surface acoustic waves travelling from the respective input electrodes so as to suppress self-convolutions.

Abstract: A method of manufacturing surface acoustic wave devices includes providing a dielectric substrate with a plurality of channels which open onto a substrate surface region and each of which accommodates a metallic electrode, the electrodes being recessed below the substrate surface region by an actual distance which at least equals a desired distance at which the electrodes have a minimum acoustic reflectivity, testing the performance of the device to ascertain at least the acoustic reflectivity of the electrodes, and etching at least the dielectric substrate, when it is ascertained during the testing that the acoustic electrode reflectivity is excessive, at least at the substrate surface region to a predetermined etching depth. The use of this method results in a device having reduced post-etching acoustic electrode reflectivity as a result of the thus obtained reduction in the difference between the actual and desired distances.

Abstract: A surface-acoustic-wave device includes a glassy layer provided on a piezoelectric layer and having periodic grooves (gratings) so as to be used as a reflector exhibiting an excellent reflection ratio.

Abstract: A surface elastic wave filter has a pair of electrodes on a surface of a piezoelectric body, and at least one of the electrodes is constructed as electrode fingers in the form of comb teeth which are progressively spread away from each other along a direction normal to the direction in which a surface elastic wave is propagated on the surface of the piezoelectric body. A grating or dot structure as a scattering reflector for scattering and reflecting a portion of the surface elastic wave is disposed in a desired position between the electrodes. Alternatively, some of electrode fingers of a surface elastic wave filter are dropped or removed, or divided voltages are applied to electrode fingers, or a scattering reflector is added to a filter with some of its electrode fingers removed or with divided voltages applied to electrode fingers. With such an arrangement, a filter having good selectivity and desired frequency characteristics can be achieved.

Abstract: A surface wave acoustic delay line is formed of a set of electrode assemblies disposed on the surface of a block of crystalline material propagative of a surface acoustic wave. In each of the assemblies, the electrodes are arranged in an interdigitated pattern. Reflected waves are cancelled by the construction of an additional electrode in each of an electrode assembly, the additional electrode extending only one-half the distance of the other electrodes and being spaced from an adjacent electrode by one-quarter wavelength. This introduces a 180.degree. phase shift between portions of relected waves which then cancel to remove the reflection. Also, in the case of closely spaced electrode assemblies, additional electrodes, equal in shape and size to the electrodes of the assemblies, are introduced between the assemblies in the form of a grid which propagates surface waves without reflection.

Abstract: A system for recognizing touch positions along a predetermined coordinate axis includes a surface wave propagating substrate on which is disposed at least one surface wave transducer. An array of surface wave reflective elements directs the surface wave from the transducer. The reflective elements are composed of a frit material.

Abstract: A surface acoustic wave resonator comprising at least two interdigital electro-acoustic transducers found between two sets of reflective gratings on a crystalline substrate. The period of the electrodes of the transducers is selected to be less than the period of the reflective gratings.

Abstract: A group-type unidirectional surface acoustic wave filter composed of sending electrodes, reflecting electrodes and meander electrodes constituted by interdigital electrodes, respectively. As a phase shifter of the filter, a capacitive element is used. The geometrical configuration of the meander electrode is determined in accordance with geometrical phase difference. The filter enjoys low insertion loss with a simplified structure.

Abstract: A SAW device includes aligned IDTs (inter-digital transducers) with a continuous pattern of fingers between their front edges. Each IDT may be symmetrical about its center, and includes front and back edge reflection suppressing regions of fingers of successively decreasing length, which serve to suppress surface acoustic wave reflections at the respective edges. Optional shield regions between the two front edge suppressing regions, and between the back edge suppressing regions and acoustic absorbers, include fingers of successively increasing length complementary to and adjacent the fingers of successively decreasing length of the reflection suppressing regions. The IDTs may be apodized or unapodized, and each IDT may include dummy fingers between its active region and each reflection suppressing region.

Abstract: The elastic surface wave device is comprised of an inter-digital transducer, a multi-strip coupler or a hone type acoustic beam width compresser, and an output terminal which are formed on a piezo electric substrate. The inter-digital transducer can produce an elastic surface wave signal which has a predetermined delay time, an electrode width equal to and u band width BW equal to ##EQU1## The hone type acoustic beam width compresser can produce the mixed effect of non-linearity by transferring maximum energy in accordance with the proportion of the input acoustic beam width l.sub.1 and the output acoustic beam width l.sub.2 to increase the acoustic power density. The multi-strip coupler can filter low band frequencies by spatially integrating the electrical displacement of the elastic surface wave according to the electrode length of the output side.

Abstract: In an acoustic surface wave multimode filter comprising a pair of acoustic surface wave resonators and a bus bar on a piezoelectric substrate with the bus bar shared by the resonators, the bus bar is rendered thicker than the resonators. Preferably, the bus bar should be about twice as thick as the resonators.

Abstract: A cantilever mount for a substrate lamina of a surface wave device wherein the substrate lamina 42 of the component is attached only at its one end 45 and is a wedge-shaped structure. The tapered end 46 of the substrate lamina 42 which is remote from the atachment location is mounted above the surface 41 of the base plate 41 which causes minimization of disturbing influences.

Abstract: A SAW dispersive delay device comprises a high-coupling piezoelectric substrate such as lithium niobate, an input and an output metallic transducer deposited on the piezoelectric substrate, and a pair of coextensive metallic reflective arrays deposited on the same substrate and respectively aligned with the transducers. The arrays comprise a number of "shorted" and "open" reflectors which are alternately interleaved. The reflectors are inclined substantially 45.degree. with respect to the aligned tranducer propagation direction. The periodicity of the reflectors varies along the length of each reflective array so that different frequencies are reflected at different locations along each array to thereby provide a different delay path. The periodicity variation is the same in the two arrays. The periodicity of these reflectors varys in a manner consistent with a prescribed dispersion characteristic.

Abstract: A surface acoustic wave generator includes a transducer array of a plurality of surface acoustic wave transducers having different center frequencies from each other, and a variable frequency oscillator for supplying an HF signal to drive the transducer array. A distributor distributes the HF signal supplied from the oscillator to each of the transducers of the transducer array, and a device provided between each of the transducers and the distributor prevents the HF signals reflected by the transducers from returning to the distributor.

Abstract: An optimum bias circuit for a convolver according to this invention searches automatically a bias voltage, which makes the convolution efficiency of a surface acoustic wave convolver highest and applies it to the gate electrode of the convolver.

Abstract: A system for recognizing touch positions along an axis on a surface associated with a touch control apparatus comprises a substrate having a surface capable of propagating surface acoustic waves and so characterized that a touch on that surface causes a perturbation of a surface wave passing through the region of touch. An input surface wave transducer coupled to the substrate surface launches a burst of surface waves on the surface. An output surface wave transducer coupled to the substrate detects received surface waves. Wave redirecting gratings derive wave components from the launched wave and redirect them across the substrate surface to the output transducer. The wave components are caused to traverse the axis along a progression of paths associated with different touch positions along the axis.

Abstract: This invention relates to a tactile sensor that is particularly suitable for use in robotics. The tactile sensor enables a robot, cybernetic device, or other appropriate automatic mechanism to sense an object, to measure the force of contact, and to determine the force necessary to seize the object. Acoustic surface waves propagated along the surface of an insulating plate within the sensor, and disrupted by contact with the sensor, are used to achieve this purpose.

Abstract: In a SAW device comprising a piezoelectric substrate and at least one set of metallic electrodes formed on the piezoelectric substrate, at least one set of the electrodes have a laminated structure comprised of a layer of an aluminum film added with an impurity at a concentration of 6 wt. % or less and another layer of a film of pure aluminum or aluminum added with an impurity at a concentration of 0.4 wt. % or less. The SAW device having the laminated structure of electrodes can handle high frequency electric signals of higher power and/or larger amplitudes.

Abstract: An improved manufacturing technique for producing a certain class of Surf Acoustic Wave (SAW) devices, namely those having input and output transducers in close proximity. A much higher manufacturing yield results from eliminating the cutting of a slot in the substrate between input and output transducers as formerly done. This frequently destructive step is replaced by ion-milling of a deep groove between the ports and backfilling with a metal of proper configuration to provide elecromagnetic shielding. The technique produces a new device that is at least equal to the prior art in rejection of unwanted couplings between input and output.

Abstract: A multichannel surface acoustic wave encoder/decoder having a common electrical input is designed so that the insertion losses of the channels differ despite the apparent design constraint of closely matched channel output impedances. The input transducing device or SAW transmitter is divided into individual transducers (or into subtransducers) having different numbers of finger overlaps, thus achieving different acoustic output levels which in turn result in different insertion losses for different channels. The finger spacing of the SAW transmitters can differ between the respective input transducers or subtransducers so as to optimize the center frequency of each channel.

Abstract: A surface acoustic wave resonator has two solid-type interdigital transducers and two grating reflectors arranged on a piezoelectric substrate or on a surface acoustic wave substrate which contains a piezoelectric material and the reflectors are arranged outside these transducers. If the electrode pitch of the interdigital transducers is suitably different from the pitch of grating of the reflectors, ripples caused by the triple transit echo at frequencies other than the peak frequency are deviated so as to lie outside the stop band of the reflectors, so that spurious responses are suppressed. In this case, the number of electrode pairs Ni of the interdigital transducers should satisfy a relation, Ni.gtoreq..pi./.epsilon., wherein .epsilon.

Abstract: A surface-wave resonator filter having at least two reflector structures and at least one interdigital transducer. At least a portion of one of the reflector structures has interruptions in the metallization strips thereof to define subsections of the metallization strip. Connecting metallizations are provided parallel to the wave propagation direction x between neighboring sub-sections of neighboring sub-divided metallization strips to electrically connect the neighboring sub-sections such that no two sub-sections of the same sub-divided metallization strip are electrically connected.

Abstract: A surface acoustic wave device includes a substrate which supports surface acoustic wave propagation having a predetermined surface acoustic wave velocity characteristic and a pair of interdigitated transducers coupled to said surface wave propagation surface. The pair of interdigitated transducers are spaced by a region of said surface wave propagation surface. To adjust the surface wave velocity characteristic of said surface wave device, a thin layer of a nonconducting elastic material, such as aluminum oxide or zinc sulfide is deposited onto a portion of the region disposed between the pair of interdigitated transducers, to change the surface wave velocity characteristic of the surface wave device.

Abstract: A surface acoustic wave device includes a semiconductor substrate, a piezoelectric film disposed on the semiconductor substrate, at least one pair of comb-shaped electrodes constituting an input transducer and an output transducer, a plurality of surface acoustic wave filters having different bands which include a plurality of metal electrodes, so disposed that each of them is located between the input and output comb-shaped electrodes of each of the surface, acoustic wave filters, a bias voltage applying arrangement for applying bias voltages to each of the metal electrodes; and a bias voltage regulating arrangement for regulating the bias voltages.

Abstract: An electronic article surveillance and identification system employing a transceiver (10,11) for broadcasting an interrogation signal into a zone to track the location and movement therein of inventory, merchandise, vehicles, animals, people and objects carrying passive (unpowered) transponder tags (12) adapted to receive the interrogation signal, process the signal in an encoded surface acoustic wave device (15) having a predetermined pattern of reflection groove or grating transducers (30-39, 40-72) and echo an encoded response signal to the transceiver.

Abstract: A reflective array surface acoustic wave signal compressor or expander (RAC) has a piezoelectric substrate (LiNbO.sub.3) upon which is deposited an input transducer and an output transducer and etched therein a reflective grating. The RAC grating comprises reflective elements which includes a plurality of grooves having either uniform depths and lengths and preselected widths or uniform depths, lengths and widths for producing a flat pass band or a desired frequency characteristic. Yields are increased owing to the simplified fabrication process and costs decreased owing to batch fabrication made possible by the resulting simplified fabrication-process.

Abstract: A surface acoustic wave resonator so constructed that multiple reflection of a surface acoustic wave in interdigital electrodes is suppressed, no sub-resonance caused by the multiple reflection occurs in the inductive areas, and the resonator effects a reliable excitation.

Abstract: A "passive interrogator label system" (PILS) is disclosed with passive, SAW transponders which are capable of receiving an interrogation signal, processing this signal and transmitting a reply signal that is derived from the interrogation signal and contains encoded information. The SAW transducers employed in the transponders are operated at their third harmonic and comprise split fingers which reduce SAW reflections. These transducers are also shaped to increase their bandwidth and to reduce their capacitance. The bus bars connecting the transducers are formed of double thickness to reduce ohmic resistance losses and these bus bars as well as the transponder phase delay pads have two levels of serrations on their edges to substantially cancel reflections. SAW reflectors in the transponder are provided with shorts between successive fingers to reduce ohmic resistance losses and to render them less susceptible to fabrication errors.

Abstract: A surface acoustic wave device comprising a device body and a multilayer printed board. The body has a piezoelectric substrate on which arrays of strip electrodes are formed. The body is covered with an insulating film except for locations where terminals are formed. The printed board is spaced a given distance from the body. The terminals of the printed board are connected via a solder layer with the terminals of the device body.

Abstract: An elastic surface wave element which prevents mixture of foreign substances to improve the reliability thereof and allows a peripheral circuit for driving the element to be integrated with the element to facilitate designing and assembly of the element. The elastic surface wave element comprises an element body and a multi-layered printed circuit board disposed one on the other with a predetermined gap left therebetween and having terminal sections connected to each other. The element further comprises a sound wave absorbing member which seals outer peripheries along which the element body and the multi-layered printed circuit board are joined together and thus seals airtight a face of the element on which electrodes are formed.

Abstract: A surface acoustic wave resonator device having a resonant cavity formed on a substrate between a transducer and its related grating that causes a symmetric frequency response with one major resonant frequency response and low spurious frequency responses, with no etched grooves or recessed electrodes, with a minimum electrode geometry of .lambda./4, with single level fabrication and uniform wave velocity throughout the structure and being frequency insensitive to electrode reflections.

Abstract: A surface acoustic wave device in which the two ports of an input transducer (2) provided on a piezoelectric substrate (1) are coupled to the two ports of an output transducer (3) via respective reflective multi-strip couplers (12, 13). In order to avoid the necessity of providing external tuned matching components to attain the low potential insertion loss of such a device, the number of electrodes and center-to-center distances of the electrodes of at least one of the transducers are chosen so that the impedance of that transducer is substantially real for a range of frequencies which contains the center-frequency of the device response characteristic as determined by the couplers.

Abstract: A surface acoustic wave device for measuring the mass flow rate of a gas includes a surface acoustic wave delay line formed of a piezoelectric substrate and having a temperature coefficient of delay on the order of 10.sup.-4 /.degree.C. The substrate has disposed thereon a transmitting and a receiving interdigital transducer, the transducers being configured to have an operating frequency in the range of from 10MHz to 1000MHz. That portion of the substrate located between the transducers defines a propagation region and has a medium deposited thereon for absorbing a portion of the acoustical and/or electrical energy flowing thereacross. This absorbed energy increases the temperature of the propagation region over that of the surrounding ambient.A mass flow of the gas across the sensor will decrease its temperature and result in an upward shift in the resonant frequency.

Abstract: Acoustic surface wave devices of a novel class characterized by the provision of coupling means comprising at least several spaced filamentary electrical conductors extending over a first region and a second region for causing acoustic surface waves propagated across the coupling means in the first region to interact with acoustic surface waves propagated across the coupling means in the second region, by means of alternating electric signals induced on the filamentary electric conductors. The regions to be coupled are preferably formed on piezoelectric material, but modified forms of the coupling means can be made operable with other materials and suitable biassing fields.

Abstract: A system for recognizing touch positions along an axis on a surface associated with a touch control apparatus comprises a substrate having a surface capable of propagating surface acoustic waves and so characterized that a touch on that surface causes a perturbation of a surface wave passing through the region of touch. An input surface wave transducer coupled to the substrate surface launches a burst of surface waves on the surface. An output surface wave transducer coupled to the substrate detects received surface waves. Wave redirecting gratings derive wave components from the launched wave and redirect them across the substrate surface to the output transducer. The wave components are caused to traverse the axis along a progression of paths associated with different touch positions along the axis.