Abstract: A surface acoustic wave device includes a Y-cut, X-propagation LiTaO3 substrate, at least one interdigital transducer provided on the LiTaO3 substrate and made of Al or a metal containing Al as a major component, and an SiO2 film provided on the surface of the LiTaO3 substrate so as to cover the interdigital transducer, wherein the thickness Hs of the SiO2 film normalized by the wavelength ? of a surface acoustic wave and the cut angle ? of the LiTaO3 substrate are set to be in any one of the ranges represented by formulae (1) to (8): in the case of 0.00<Hs?0.05, 30°<?<36°??(1) in the case of 0.05<Hs?0.10, 29°<?<36°??(2) in the case of 0.10<Hs?0.15, 28°<?<36°??(3) in the case of 0.15<Hs?0.20, 27°<?<36°??(4) in the case of 0.20<Hs?0.25, 26°<?<36°??(5) in the case of 0.25<Hs?0.30, 25°<?<35°??(6) in the case of 0.30<Hs?0.35, 23°<?<34°??(7) in the case of 0.35<Hs?0.

Abstract: An edge reflection surface acoustic wave filter includes IDTs disposed on a top surface of a piezoelectric substrate, and surface acoustic waves of the Shear Horizontal type are reflected between opposite edges. At least one outermost electrode finger in the direction of propagation of surface acoustic waves on the side of at least one of the edges is removed. Accordingly, desired filter characteristics can readily be achieved without causing variations in filter characteristics, spurious components at frequencies lower than the passband are minimized, and selectivity is greatly improved.

Abstract: A method for adjusting a frequency characteristic of an edge reflection type surface acoustic wave device includes the step of obtaining a frequency characteristic of an edge reflection type surface acoustic wave device having a piezoelectric substrate. The edge reflection type surface acoustic wave device has a pair of edges of the piezoelectric substrate which define a predetermined distance therebetween. Then, the piezoelectric substrate is cut at at least one of a pair of positions which define a distance that is shorter than the predetermined distance when a final frequency characteristic of the edge reflection type surface acoustic wave device is to be higher than the obtained frequency characteristic. The piezoelectric substrate is cut at at least one of a pair of positions which define a distance that is longer than the predetermined distance when a final frequency characteristic of the edge reflection type surface acoustic wave device is to be lower than the obtained frequency characteristic.

Abstract: An end-surface reflection type surface acoustic wave filter is capable of increasing an attenuation amount outside a pass band while insertion loss characteristics are not seriously deteriorated. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. In addition, IDTs which are provided between the grooves for defining the longitudinally coupled resonator type surface acoustic wave filter, reflection end-surfaces disposed on side surfaces of the first and the second grooves at the IDT sides, and one of a resin-coating layer and a protective layer made of SiO2, are provided on the top surface of the piezoelectric substrate.

Abstract: An end-surface reflection type surface acoustic wave filter is capable of increasing an attenuation amount outside a pass band while insertion loss characteristics are not seriously deteriorated. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. In addition, IDTs which are provided between the grooves for defining the longitudinally coupled resonator type surface acoustic wave filter, reflection end-surfaces disposed on side surfaces of the first and the second grooves at the IDT sides, and one of a resin-coating layer and a protective layer made of SiO2, are provided on the top surface of the piezoelectric substrate.

Abstract: A longitudinally coupled resonator-type surface acoustic wave device includes interdigital transducers including a plurality of electrode fingers disposed along the propagation direction of a surface acoustic wave on a surface acoustic wave device. An electrically discontinuous portion is provided in a central portion, in the finger overlap direction, in adjacent electrode fingers in adjacent interdigital transducers, and at least one floating electrode is disposed in the finger overlap direction in the electrically discontinuous portion.

Abstract: An end-surface reflection type surface acoustic wave filter is capable of increasing an attenuation amount outside a pass band while insertion loss characteristics are not seriously deteriorated. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. In addition, IDTs which are provided between the grooves for defining the longitudinally coupled resonator type surface acoustic wave filter, reflection end-surfaces disposed on side surfaces of the first and the second grooves at the IDT sides, and one of a resin-coating layer and a protective layer made of SiO2, are provided on the top surface of the piezoelectric substrate.

Abstract: A surface acoustic wave device includes a piezoelectric substrate having a pair of substrate edges and an upper surface therebetween. The piezoelectric substrate has at least one inner edge which is in contact with a main region and extends from the upper surface toward a bottom surface of the piezoelectric substrate inside one of the substrate edges. An interdigital transducer is provided on the main region of the piezoelectric substrate such that a SH type surface acoustic wave excited by the interdigital transducer and having a wavelength of &lgr; is reflected by the at least one inner edge. A distance L between the at least one inner edge and the corresponding one of the substrate edges is substantially equal to about 8&lgr; or less.

Abstract: A surface acoustic wave device includes a Y-cut, X-propagation LiTaO3 substrate, at least one interdigital transducer provided on the LiTaO3 substrate and made of Al or a metal containing Al as a major component, and an SiO2 film provided on the surface of the LiTaO3 substrate so as to cover the interdigital transducer, wherein the thickness Hs of the SiO2 film normalized by the wavelength &lgr; of a surface acoustic wave and the cut angle &thgr; of the LiTaO3 substrate are set to be in any one of the ranges represented by formulae (1) to (8):

Abstract: A SAW apparatus includes a plurality of IDTs disposed on a piezoelectric substrate, and an edge-reflection-type SAW device in which surface acoustic waves are reflected by the edge surfaces of the piezoelectric substrate. The SAW device is housed in a package. On the top of a first main surface of the piezoelectric substrate, first and second pyroelectric charge cancellation electrodes are disposed in the vicinity of the edges defined by the main surface and the side surfaces. The first and second pyroelectric charge cancellation electrodes are electrically connected to the electrodes on the package which are electrically connected to each other within the package, respectively. Therefore, the adverse effects of pyroelectric charge which is generated due to a rapid change in temperature is minimized.

Abstract: A method of manufacturing an edge reflection type surface acoustic wave device includes the step of preparing a surface acoustic wave mother substrate having a plurality of interdigital transducers formed on one main surface thereof. A cut groove is formed in the substrate by cutting the surface acoustic wave mother substrate beginning from the one main surface side thereof. This step of forming a cut groove is repeated so as to produce a plurality of cut grooves so that the first reflection edge of the respective surface acoustic wave devices are sequentially formed. Next, similarly, cut grooves are sequentially formed on the surface acoustic wave mother substrate from the one main-face side thereof so as not to reach the other main surface thereof, whereby the second reflection edges of the respective surface acoustic wave devices are sequentially formed.

Abstract: A SAW apparatus includes a plurality of IDTs disposed on a piezoelectric substrate, and an edge-reflection-type SAW device in which surface acoustic waves are reflected by the edge surfaces of the piezoelectric substrate. The SAW device is housed in a package. On the top of a first main surface of the piezoelectric substrate, first and second pyroelectric charge cancellation electrodes are disposed in the vicinity of the edges defined by the main surface and the side surfaces. The first and second pyroelectric charge cancellation electrodes are electrically connected to the electrodes on the package which are electrically connected to each other within the package, respectively. Therefore, the adverse effects of pyroelectric charge which is generated due to a rapid change in temperature is minimized.

Abstract: An edge reflection type surface acoustic wave filter includes a piezoelectric substrate having two opposing edges and at least one interdigital transducer. The interdigital transducer includes split electrodes of paired electrode fingers arranged on the piezoelectric substrate such that a shear horizontal (SH-type) surface acoustic wave is excited on the piezoelectric substrate and is reflected between the two opposing edges. Each of the edges is preferably located at a distance of at least about &lgr;/2−5&lgr;/128 from a center of the paired equipotential electrode fingers, located at the respective outermost portions, in the surface acoustic wave propagation direction, of the interdigital transducer and less than about &lgr;/2 from the center of the paired equipotential electrode fingers, where &lgr; is a wavelength of the SH-type surface acoustic wave excited on the piezoelectric substrate.

Abstract: An end-surface reflection type surface acoustic wave filter is capable of increasing an attenuation amount outside a pass band while insertion loss characteristics are not seriously deteriorated. The filter is a longitudinally coupled resonator type surface acoustic wave filter using an SH type surface acoustic wave, which has first and second grooves formed in a piezoelectric substrate at the top surface thereof so as to be substantially parallel to each other and spaced from each other by a predetermined distance. In addition, IDTs which are provided between the grooves for defining the longitudinally coupled resonator type surface acoustic wave filter, reflection end-surfaces disposed on side surfaces of the first and the second grooves at the IDT sides, and one of a resin-coating layer and a protective layer made of SiO2, are provided on the top surface of the piezoelectric substrate.

Abstract: An edge-reflection surface acoustic wave filter includes IDTs disposed on a top surface of a piezoelectric substrate, and surface acoustic waves of the Shear Horizontal type are reflected between opposite edges. At least one outermost electrode finger in the direction of propagation of surface acoustic waves on the side of at least one of the edges is removed. Accordingly, desired filter characteristics can readily be achieved without causing variations in filter characteristics, spurious components at frequencies lower than the passband are minimized, and selectivity is greatly improved.

Abstract: A method for adjusting a frequency characteristic of an edge reflection type surface acoustic wave device includes the step of obtaining a frequency characteristic of an edge reflection type surface acoustic wave device having a piezoelectric substrate. The edge reflection type surface acoustic wave device has a pair of edges of the piezoelectric substrate which define a predetermined distance therebetween. Then, the piezoelectric substrate is cut at at least one of a pair of positions which define a distance that is shorter than the predetermined distance when a final frequency characteristic of the edge reflection type surface acoustic wave device is to be higher than the obtained frequency characteristic. The piezoelectric substrate is cut at at least one of a pair of positions which define a distance that is longer than the predetermined distance when a final frequency characteristic of the edge reflection type surface acoustic wave device is to be lower than the obtained frequency characteristic.

Abstract: An edge reflection type surface acoustic wave device utilizes a Shear Horizontal type surface acoustic wave and includes a surface acoustic wave substrate, and at least two interdigital transducers provided on one main surface of the surface acoustic wave substrate. First and second grooves are formed on the opposite ends in the surface acoustic wave propagation direction of the area where the interdigital transducer is provided. The first and second grooves extend from the one main surface of the surface acoustic wave substrate toward the other main surface thereof without reaching the other main surface. The grooves extend substantially perpendicularly to the surface acoustic wave propagation direction so as to define first and second edges for reflecting the surface acoustic wave. The first and second edges are defined by the inner sideively. walls of the first and second grooves, respectively.

Abstract: An edge reflection type surface acoustic wave device includes a surface acoustic wave substrate having an opposing pair of edges and at least one interdigital transducer located on the surface acoustic wave substrate. A Shear Horizontal type surface acoustic wave is generated by the interdigital transducer and reflected between the opposing pair of edges. The interdigital transducer is divided into a plurality of sub-IDT portions along a surface acoustic wave-propagating direction. Electrode fingers of the interdigital transducer which are closest to each other between adjacent sub-IDT portions are at the same potential so as not to be excited between the adjacent sub-IDT portions.

Abstract: An edge reflection type surface acoustic wave device includes a surface acoustic wave substrate made of a piezoelectric single crystal and having first and second opposite edges, and at least one interdigital transducer disposed on the surface acoustic wave substrate. The surface acoustic wave device is constructed such that a Shear Horizontal type surface acoustic wave is reflected between the first and second opposite edges. The surface acoustic wave substrate is made of an ion-implanted piezoelectric single crystal substrate.

Abstract: An edge reflection type longitudinally coupled SAW resonator filter includes a surface acoustic wave substrate having a first end surface and a second end surface which are arranged at opposite ends of the substrate. A plurality of edge reflection, longitudinally coupled resonator filter units are arranged on the surface acoustic wave substrate such that a surface acoustic wave is reflected between the first end surface and the second end surface of the surface acoustic wave substrate. A connecting conductive portion is arranged to electrically connect the plurality of the longitudinally coupled resonator filter units. Each of the longitudinally coupled resonator filter units has a plurality of interdigital transducers aligned in a surface acoustic wave propagating direction. The number of pairs of electrode fingers in the plurality of the longitudinally coupled resonator filter units is equal.