Canon Kabushiki Kaisha

Koichi Egara

Norihiro Mochizuki

Tadashi Eguchi

Akira Torisawa

Takahiro Hachisu

Akihiro Koyama

Kenji Nakamura

Akane Yokota

Kazuo Yoshinaga

Takeshi Miyazaki

Koichi Sato

Hideaki Mitsutake

Yomishi Toshida

Takashi Kai

Norihiro Mochuzuki

A surface acoustic wave converter for converting an electric signal into a surface acoustic wave includes an interdigital transducer provided on a piezoelectric substrate. The interdigital transducer has first and second electrode groups each having one or more electrode fingers to which a first signal is almost simultaneously inputted. The surface acoustic wave converters includes first input unit for inputting the first signal to the one or more electrode fingers of the first electrode group, and second input unit for inputting the first signal to the one or more electrode fingers of the second electrode group when at least one of surface acoustic waves excited by the first signal in the one or more electrode fingers of the first electrode group reaches one of the one or more electrode fingers of the second electrode group.

Surface acoustic wave converter with improved frequency characteristics,

In a surface acoustic wave apparatus, a surface acoustic wave element for obtaining a convolution signal is housed in a recess of a substrate. Since the surface acoustic wave element is housed in the recess of the substrate in this surface acoustic wave apparatus, the apparatus can be compactified. This effect of compactification is remarkable, because the surface acoustic wave element has an output electrode for obtaining the convolution signal and thus originally has a big element size. When a laminate substrate is used as the substrate, a configuration for effectively using surfaces of respective layers may be arranged in such a manner that output wiring of the convolution signal is separately formed in the layers. This further enhances the effect of compactification. There are further disclosed a spread spectrum signal receiver using the above surface acoustic wave apparatus for receiving a spread spectrum signal, and a spread spectrum communication system using the spread spectrum signal receiver.

Compact surface acoustic wave apparatus, spread spectrum signal receiver

A matched filter has an input IDT and an output IDT, and also has a device for preventing propagating surface acoustic waves from diverging. By preventing the divergence of surface acoustic waves, signals obtained in units of electrode finger pairs of the output IDT are uniformed. Furthermore, this application also discloses the following arrangement. That is, an arrangement for converging surface acoustic waves is adopted, and the width of surface acoustic waves input to the output IDT is set to be larger than at least the crossing width of electrode fingers, nearest to the input IDT, of those of the output IDT, so that some surface acoustic waves propagate along non-crossing portions of the electrode fingers, on the input IDT side, of those of the output IDT. With this arrangement, the influence of the crossing portions of the electrode fingers, closer to the input IDT, on the surface acoustic waves input to the crossing portions of the electrode fingers, farther from the input IDT, can be relaxed.

Matched filter with improved synchronous characteristics, and reception

A surface acoustic wave device includes a piezoelectric substrate, first and second input transducers formed on the substrate and adapted for respectively generating surface acoustic waves corresponding to input signals, the first and second input transducers each having a shape to focus the surface acoustic waves generated thereby, an output transducer formed between the first and second input transducers on the substrate and adapted for obtaining a convolution -signal of the surface acoustic waves generated by the first and second input transducers, and conductive films, one formed between the first input transducer and the output transducer and another between the second input transducer and the output transducer on the substrate. A communication system includes a transmitter for transmitting a signal modulated according to information, a circuit for receiving the modulated signal transmitted from the transmitter, a circuit for generating a reference signal, a surface acoustic wave device, as described above, for outputting a convolution signal of the modulated signal and the reference signal, and a demodulating circuit for restoring the information, using the convolution signal output from the surface acoustic wave device.

Surface acoustic wave device and communication system using it

A surface acoustic wave device includes a piezoelectric substrate, a wave guide path provided on the piezoelectric substrate and an interdigital transducer for exciting a surface acoustic wave. The interdigital transducer is provided with plural portions of mutually different pitches of the electrode finger, respectively corresponding to different frequencies. The portions are parallelly arranged along a direction perpendicular to the propagation direction of the surface acoustic wave. The surface acoustic wave generated by the interdigital transducer is entered in concentrated manner into the wave guide path.

Efficient surface acoustic wave device capable of excitation in plural

A surface acoustic wave device includes a substrate having piezoelectricity, at least two input electrodes, provided on the substrate, for exciting first and second surface acoustic waves, and an output electrode for taking a convolution signal of the two surface acoustic waves out. The substrate has a roughness configuration on a back face thereof and a maximum depth of the roughness configuration is not less than a wavelength of bulk waves of convolution output taken out of the output electrode.

Surface acoustic wave device improved in convolution efficiency,

A correlator includes a reference signal generating device for generating a reference signal with period T, n-convolvers each having an action time of T/n where n is an integer of at least 2, into each of which an information signal and a reference signal are input and each of which outputs a convolution signal of the information signal and the reference signal, a delay device for delaying an information signal input into a k-th convolver among the n convolvers for a time of (k-1)T/n where k=1, 2, . . . , n and for delaying a reference signal input into the k-th convolver for a time of (n-k)T/n, and an adder for adding convolution signals respectively output from the n convolvers. A receiver includes such a correlator for outputting a correlation signal of a received information signal and a reference signal, and a decoding circuit for decoding data from the correlation signal output from the correlator. A communication system includes a transmitter for transmitting an information signal, and a receiver for receiving the information signal transmitted from the transmitter and having the correlator.

Correlator and communication system using it

A surface acoustic wave element is provided with a piezoelectic substrate, a first input transducer, a second input transducer and an output device such as output electrode. The piezoelectric substrate has a first and a second surfaces which are mutually faced. The first input transducer is formed on the first surface of the substrate to generate a first surface acoustic wave which propagates in a predetermined direction. The second transducer is formed on the first surface of the substrate to generate a second surface acoustic wave which propagates in a direction opposite to the predetermined direction. The output device is formed on the first surface of the substrate to extract a signal produced by an interaction of the first and second surface acoustic waves. At least part of the second surface of the substrate is caused to be inclined in a direction perpendicular to the predetermined direction with respect to the first surface.

Surface acoustic wave element and communication system using the same

A surface acoustic wave device comprises a piezoelectric substrate, a plurality of input transducers, formed on the substrate, for generating surface acoustic waves corresponding to input signals, a plurality of waveguides which are juxtaposed on a region of said substrate where the surface acoustic waves generated by said input transducers overlap each other, and in which signals are generated due to an interaction of the surface acoustic waves, the waveguides generating surface acoustic waves corresponding to the signals due to the interaction, and an output transducer for receiving the surface acoustic waves generated from the waveguides, converting the signals due to the interaction into electrical signals, and extracting the electrical signals, the output transducer being constituted by a plurality of portions, juxtaposed in a widthwise direction of the surface acoustic waves generated from the waveguides, for receiving some components of the surface acoustic waves generated from the waveguides, and outputting signals, the portions being connected to each other, so that electric fields of electrical signals output from said portions are synthesized in the same direction.

Surface acoustic wave device provided with output transducer split into

A surface acoustic wave device comprises a substrate, a plurality of input transducers formed on the substrate for generating first and second surface acoustic waves propagating in opposite directions to each other, and a plurality of waveguides arranged in a direction orthogonal to the propagating direction of the first and second surface acoustic waves on a region where the first and second surface acoustic waves overlap. Each waveguide producing a third surface acoustic wave propagating in a direction where the waveguides are arranged, with the interaction between the first and second surface acoustic waves, and on at least two of the waveguides, third surface acoustic waves reflected at respective side edges cancel each other, and an output transducer converts the third surface acoustic waves propagating from the waveguides into an electrical signal.

Surface acoustic wave device with reflected wave at side edges on

An elastic surface wave convolve comprises a piezoelectric substrate, a plurality of input transducers formed on said substrate for generating elastic surface waves corresponding to respective input signals, a plurality of waveguides provided side by side on a region of the substrate where elastic surface waves radiated from the input transducers overlap, wherein a convolution signal of input signals is produced due to parametric mixing effect of elastic surface waves in respective waveguides, these waveguides generating an elastic surface wave corresponding to the convolution signal, and an output transducer for receiving the elastic surface wave radiated from the waveguides and taking out an electrical signal by conversion of the convolution signal, wherein the width of elastic surface wave radiated from the waveguides is narrower immediately before reception with the output transducer than immediately after radiation from the waveguides.

Elastic surface wave convolva having wave width converting means and

A nonlinear optical material is provided by mixing a polymer liquid crystal having a chiral center and a nonlinear optical compound. The polymer liquid crystal may be a ferroelectric polymer liquid crystal. The nonlinear optical material is preferably in the form of a solid solution. A nonlinear optical device is formed by orienting the nonlinear optical material to provide an optical member.

Nonlinear optical material and nonlinear optical device

A surface acoustic wave convolver comprises a piezoelectric substrate, a plurality of input transducers formed on the substrate and adapted to respectively generate surface acoustic waves in response to input signals, and a plurality of wave guide paths parallelly provided on the substrate in a superposing area of the surface acoustic wave generated by the input transducers to each generate a convolution signal of the input signals by non-linear interaction of the surface acoustic waves therein. The convolution signals generated in neighboring wave guide paths are mutually different by 180.degree. in phase, and the wave guide paths are adapted to generate surface acoustic waves corresponding to the convolution signals and an output transducer receives the surface acoustic waves generated by the wave guide paths and converts the convolution signals into an output electrical signal.

Surface acoustic wave convolver with plural wave guide paths for

In a surface acoustic wave elastic convolver capable of showing sufficiently high convolution efficiency with a simple structure, the convolver comprises a piezo-electric substrate, plural input transducers formed on the substrate for respectively generating surface acoustic waves corresponding to input signals, an output transducer for obtaining a convolution signal of the input signals, from a surface acoustic wave generated by non-linear interaction, of the surface acoustic waves generated by those input transducers, and a dielectric film of a non-linear effect larger than that of the substrate, formed on the substrate in at least an area where the output transducer is formed.

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Tokyo, Japan

Koichi Egara