Abstract: A boundary acoustic wave device has a small thickness, which is suitable for thin apparatuses, and can be manufactured at low cost. The boundary acoustic wave device includes a first IDT electrode disposed on a first surface of a substrate, a first insulating film covering the first IDT electrode, a second IDT electrode disposed on a second surface of the substrate, and a second insulating film covering the second IDT electrode. Either the substrate or the first and second insulating films have piezoelectric characteristics.

Abstract: A dielectric substance is laminated on one surface of a piezoelectric substance, and an IDT and reflectors are disposed as electrodes at a boundary between the piezoelectric substance and the dielectric substance, and the thickness of the electrodes is determined so that the acoustic velocity of the Stoneley wave is decreased less than that of a slow transverse wave propagating through the dielectric substance and that of a slow transverse wave propagating through the piezoelectric substance, thereby forming a boundary acoustic wave device.

Abstract: An elastic boundary wave apparatus that is capable of suppressing an undesired response due to a comb-shaped capacitor electrode includes a first medium; a second medium stacked on the first medium; and a plurality of electrodes arranged in the boundary between the first and second media, wherein a filter and/or a resonator, and an electrostatic capacitor that is electrically connected to the filter and/or the resonator are defined by the plurality of electrodes, the filter and/or the resonator each include an IDT electrode, and the electrostatic capacitor is defined by a comb-shaped capacitor electrode.

Abstract: In a method for producing a boundary acoustic wave device that includes a first medium, a second medium, and a third medium laminated in that order, and electrodes disposed at the interface between the first medium and the second medium, the method includes the steps of preparing a laminate including the first medium, the second medium, and the electrodes disposed at the interface between the first medium and the second medium, adjusting the thickness of the second medium after the step of preparing the laminate to regulate a frequency or the acoustic velocity of a surface acoustic wave, a pseudo-boundary acoustic wave, or a boundary acoustic wave, after the adjusting step, forming the third medium different from the second medium in terms of the acoustic velocity with which the boundary acoustic wave propagates therethrough and/or in terms of material.

Abstract: A boundary acoustic wave device includes a dielectric body disposed over one surface of a LiTaO3 piezoelectric body, and an electrode including an IDT and reflectors at the boundary between the piezoelectric body and the dielectric body. The thickness of the electrode is set so that the acoustic velocity of the SH boundary acoustic waves is less than the acoustic velocities of slow transverse waves propagating in the dielectric body and slow transverse waves propagating in the piezoelectric body.

Abstract: A surface acoustic wave device includes a LiNbO3 substrate with a Euler angle in an area defined by a rectangle having four corners with coordinates (1) (0°, 7°, 101°), (2) (0°, 23°, 79°), (3) (0°, 23°, 79°), and (4) (0°, 7°, 79°), for example, and an electrode film made of Au, wherein surface acoustic waves including a longitudinal wave component as a main component are propagated thereon. The surface acoustic wave device uses longitudinal surface acoustic waves having a phase speed greater than with the “slow transverse wave”, and has a great electromechanical coupling coefficient and small propagation loss, and is suitable for handling high-frequency signals.

Abstract: An elastic wave device includes at least one IDT electrode provided on a piezoelectric substrate. The at least one IDT electrode includes first and second electrode fingers arranged next to each other in a propagation direction of elastic wave. The side edges of at least the electrode finger of the first and second electrode fingers are provided with projections. The position of the projections in the longitudinal direction of the electrode fingers substantially corresponds with the position of a gap in the longitudinal direction of the electrode fingers, the gap being provided at the tip end of the electrode finger of the first and second electrode fingers.

Abstract: A boundary acoustic wave filter includes a first medium layer, a second medium layer laminated on the first medium layer, and IDT electrodes that are disposed at the boundary between the first and second medium layers and that define an electroacoustic transducer. In the boundary acoustic wave filter, the sound velocity of boundary acoustic waves, which is the product of the wavelength determined by the period of the electrodes and the frequency at least the lower end of the stopband disposed at the high-frequency side of the passband, is less than the sound velocity of slow transverse waves propagating through the first medium layer and the second medium layer.

Abstract: In a method for producing a boundary acoustic wave device that includes a first medium, a second medium, and a third medium laminated in that order, and electrodes disposed at the interface between the first medium and the second medium, the method includes the steps of preparing a laminate including the first medium, the second medium, and the electrodes disposed at the interface between the first medium and the second medium, adjusting the thickness of the second medium after the step of preparing the laminate to regulate a frequency or the acoustic velocity of a surface acoustic wave, a pseudo-boundary acoustic wave, or a boundary acoustic wave, after the adjusting step, forming the third medium different from the second medium in terms of the acoustic velocity with which the boundary acoustic wave propagates therethrough and/or in terms of material.

Abstract: In a method for producing a boundary acoustic wave device that includes a first medium, a second medium, and a third medium laminated in that order, and electrodes disposed at the interface between the first medium and the second medium, the method includes the steps of preparing a laminate including the first medium, the second medium, and the electrodes disposed at the interface between the first medium and the second medium, adjusting the thickness of the second medium after the step of preparing the laminate to regulate a frequency or the acoustic velocity of a surface acoustic wave, a pseudo-boundary acoustic wave, or a boundary acoustic wave, after the adjusting step, forming the third medium different from the second medium in terms of the acoustic velocity with which the boundary acoustic wave propagates therethrough and/or in terms of material.

Abstract: An elastic boundary wave device includes an IDT including laminated conductor layers disposed between a first medium and a second medium, wherein a plane that divides the IDT in half in the thickness direction defines an interface, the energy of an elastic boundary wave present on the side of the first medium of the interface is denoted as E1, and the energy of an elastic boundary wave present on the side of the second medium of the interface is denoted as E2, and wherein if the IDT included only a conductor having the highest density among the laminated conductor layers of the IDT, when the energy of an elastic boundary wave present on the side of the first medium of the interface is denoted as E1? and the energy of an elastic boundary wave present on the side of the second medium of the interface is denoted as E2?, the energies of an elastic boundary wave would satisfy the relationship of E1/E2<E1?/E2? so that the sonic velocity of an elastic boundary wave in the IDT including the laminated conductor lay

Abstract: A boundary acoustic wave device is provided in which an increase in the conductor resistance can be suppressed and a satisfactorily high electromechanical coupling coefficient K2 can be achieved even when the frequency is increased. The boundary acoustic wave device includes a first medium, a second medium, and an IDT provided therebetween. In the boundary acoustic wave device, a plane that separates the IDT into two equal parts in the thickness direction is defined as a boundary plane, the energy of boundary acoustic waves that is present at the first medium side of the boundary plane is represented by E1, and the energy that is present at the second medium side of the boundary plane is represented by E2.

Abstract: A surface acoustic wave device includes a LiNbO3 substrate with a Euler angle in an area defined by a rectangle having four corners with coordinates (1) (0°, 7°, 101°), (2) (0°, 23°, 79°), (3) (0°, 23°, 79°), and (4) (0°, 7°, 79°), for example, and an electrode film made of Au, wherein surface acoustic waves including a longitudinal wave component as a main component are propagated thereon. The surface acoustic wave device uses longitudinal surface acoustic waves having a phase speed greater than with the “slow transverse wave”, and has a great electromechanical coupling coefficient and small propagation loss, and is suitable for handling high-frequency signals.

Abstract: A boundary acoustic wave device includes a solid layer laminated onto a single crystal substrate, electrodes provided between the single crystal substrate and the solid layer, and boundary acoustic wave elements provided on the single crystal substrate having the same cut angle, wherein the propagation direction of one of the boundary acoustic wave elements is different from that of at least one of the other boundary acoustic wave elements. A compact and high-performance boundary acoustic wave device using a boundary acoustic wave is provided by increasing the steepness of a filter band and by forming filters or resonators with different fractional bandwidths on a single substrate.

Abstract: A boundary acoustic wave filter includes a first medium layer, a second medium layer laminated on the first medium layer, and IDT electrodes that are disposed at the boundary between the first and second medium layers and that define an electroacoustic transducer. In the boundary acoustic wave filter, the sound velocity of boundary acoustic waves, which is the product of the wavelength determined by the period of the electrodes and the frequency at least the lower end of the stopband disposed at the high-frequency side of the passband, is less than the sound velocity of slow transverse waves propagating through the first medium layer and the second medium layer.

Abstract: A surface acoustic wave device includes a LiNbO3 substrate with a Euler angle in an area defined by a rectangle having four comers with coordinates (1) (0°, 7°, 101°), (2) (0°, 23°, 79°), (3) (0°, 23°, 79°), and (4) (0°, 7°, 79°), for example, and an electrode film made of Au, wherein surface acoustic waves including a longitudinal wave component as a main component are propagated thereon. The surface acoustic wave device uses longitudinal surface acoustic waves having a phase speed greater than with the “slow transverse wave”, and has a great electromechanical coupling coefficient and small propagation loss, and is suitable for handling high-frequency signals.

Abstract: In a method for producing a boundary acoustic wave device that includes a first medium, a second medium, and a third medium laminated in that order, and electrodes disposed at the interface between the first medium and the second medium, the method includes the steps of preparing a laminate including the first medium, the second medium, and the electrodes disposed at the interface between the first medium and the second medium, adjusting the thickness of the second medium after the step of preparing the laminate to regulate a frequency or the acoustic velocity of a surface acoustic wave, a pseudo-boundary acoustic wave, or a boundary acoustic wave, after the adjusting step, forming the third medium different from the second medium in terms of the acoustic velocity with which the boundary acoustic wave propagates therethrough and/or in terms of material.

Abstract: A dielectric substance is laminated on one surface of a piezoelectric substance, and an IDT and reflectors are disposed as electrodes at a boundary between the piezoelectric substance and the dielectric substance, and the thickness of the electrodes is determined so that the acoustic velocity of the Stoneley wave is decreased less than that of a slow transverse wave propagating through the dielectric substance and that of a slow transverse wave propagating through the piezoelectric substance, thereby forming a boundary acoustic wave device.

Abstract: A boundary acoustic wave device includes a dielectric body disposed over one surface of a LiTaO3 piezoelectric body, and an electrode including an IDT and reflectors at the boundary between the piezoelectric body and the dielectric body. The thickness of the electrode is set so that the acoustic velocity of the SH boundary acoustic waves is less than the acoustic velocities of slow transverse waves propagating in the dielectric body and slow transverse waves propagating in the piezoelectric body.

Abstract: A boundary acoustic wave device includes a first boundary acoustic wave element, and a second boundary acoustic wave element disposed on the first boundary acoustic wave element. Each boundary acoustic wave element includes a first solid layer made of a piezoelectric material, a second solid layer made of one of a piezoelectric material and an insulating material, and disposed on the first solid layer, and a boundary acoustic wave exciting interdigital transducer arranged in the boundary between the first and second solid layers.