Abstract: A low cost, compact, high performance flow sensor that can be made small in size even for use in a large flow rate and a mass flow controller using the same are provided. The flow sensor includes a bypass passage, a sensor passage, and a bridge circuit including heat-generating resistance wires that constitute a part of the bridge circuit and are wound around the sensor passage. The flow sensor determines a total flow rate of a fluid that flows in a branched manner through the bypass passage and the sensor passage at a predetermined flow ratio. The total flow rate is determined by detecting, as an unbalance of the bridge circuit, heat transfer caused by the fluid flowing through the sensor passage and is outputted as a sensor output of the flow sensor. In the flow sensor, the bypass passage includes a plurality of fine flow passages each having a cross-section defined by a substantially linear edge and a curve in contact with the substantially linear edge.

Abstract: A piezoelectric element includes a piezoelectric substrate formed of a piezoelectric material and a pair of electrodes formed on a first principal plane and a second principal plane of the piezoelectric substrate, wherein thickness shear vibration occurs, and the vibration direction of the thickness shear vibration is nonparallel to the side walls of the piezoelectric substrate.

Abstract: A method for producing an acceleration sensor comprising an electromechanical transducer having a piezoelectric element includes providing at least two piezoelectric substrates where each has two opposing main surfaces. The piezoelectric element is formed by directly connecting one of the main surfaces of one of the at least two piezoelectric substrates with an opposing one of the main surfaces of another one of the at least two piezoelectric substrates. Supporters are provided to support the electromechanical transducer and are directly connected to the at least two piezoelectric substrates composing the piezoelectric element. Electrodes that extend continuously from the unconnected main surfaces of the at least two piezoelectric substrates composing the piezoelectric element to surfaces of the supporters are then formed.

Abstract: A small acceleration sensor which is highly sensitive over a large frequency region and which varies little in characteristics such as sensitivity. A piezoelectric element is formed by connecting two main faces of rectangular LiNbO3 piezoelectric substrates, in which the polarization axes are directed oppositely. Supporters comprising LiNbO3 are directly connected to one end of the piezoelectric element. Electrodes of chromium-gold being 0.2 &mgr;m thick are successively connected to the two main faces of the piezoelectric element and to the supporters, thus to produce a cantilever structure bimorph electromechanical transducer.

Abstract: A liquid jetting apparatus has a concave casing having an opened flat face, and a piezoelectric drive element for at least partly sealing the opened flat face to form a liquid reservoir to store a liquid, such as ink. The reservoir has a liquid injection port for injecting a liquid and a liquid jet port for jetting the stored liquid. The piezoelectric drive element is directly bonded to the open flat face.

Abstract: A wafer with a reversed domain is prepared for two piezoelectric single crystal plates and of about the same thickness by using direct bonding without any adhesive. Driving electrodes are formed on two principal planes of the wafer with a reversed domain to provide a piezoelectric resonator. A piezoelectric resonator having the structure with a reversed polarization and using odd-order vibration modes vibrating with a fundamental wave has a wavelength of a thickness thereof and suppresses scattering of the thickness of the domains with a reversed polarization. In the direct bonding, the axes of the spontaneous polarization of the two piezoelectric single crystal plates are reverse to each other and crystalline axes other than the axes of polarization are shifted intentionally by an angle other than zero. Thus, spurious modes are suppressed in a simple way.

Abstract: A small accelaration sensor which is highly sensitive over a large frequency region and which varies little in characteristics such as sensitivity. A piezoelectric element is formed by connecting two main faces of retangular LiNbO.sub.3 piezoelectric substrates, in which the polarization axes are directed oppositely. Supporters comprising LiNbO.sub.3 directly connected to one end of the piezoelectric element. Eletrodes of chromium-gold being 0.2 .mu.m are thick are successively connected to the two main faces of the piozoelectric element and to the supporters, thus to produce a cantilever structure bimorph electromechanical transducer.

Abstract: A surface acoustic wave device is manufactured by directly or indirectly bonding a lid to a substrate having a surface acoustic wave element to seal the element under the lid. The lid is made of at least one material selected from the group comprising lithium niobate, lithium tantalete, lithium borate, glass and quartz. The substrate is made of at least one material selected from the group comprising quartz, lithium niobate, lithium tantalete and lithium borate.

Abstract: Rectangular piezoelectric substrates each of which has main surfaces opposed to each other, measures 50 .mu.m thick by 1 mm wide by 8 mm long, and is made of lithium niobate (LiNbO.sub.3), are directly bonded on the main surfaces so that their axes of polarization are set in directions reverse to each other, thereby composing a piezoelectric element. Electrodes which are 0.2 .mu.m thick and made of chromium-nickel are formed on the two main surfaces of the piezoelectric element opposed to each other, thereby resulting in a precision displacement control actuator of a bimorph type mechanical-electrical converter element. This configuration makes it possible to provide a compact precision displacement control actuator which has a large displacement and extremely small variations of characteristics such as displacement and resonance frequency.

Abstract: A wafer with a reversed domain is prepared for two piezoelectric single crystal plates 11 and 12 having about the same thickness as each other by using direct bonding without any adhesive. Then, driving electrodes 13 are formed on two principal planes of the wafer with a reversed domain to provide a piezoelectric resonator. A piezoelectric resonator having the structure with a reverses polarization and using odd-order vibration modes vibrating with a fundamental wave has a wavelength of a thickness thereof suppresses scattering of the thickness of the domains with a reversed polarization. In the direct bonding, the axes of the spontaneous polarization of the two piezoelectric single crystal plates are reverse to each other and crystalline axes other than the axes of polarization are shifted intentionally by an angle other than zero. Thus, spurious modes are suppressed in a simple way.

Abstract: An electronic component of the present invention includes a first substrate, a second substrate, a first conductive layer constituting a terminal electrode on a first surface of the first substrate, and a first insulating layer formed on the first conductive layer, wherein the first insulating layer and the second substrate are directly bonded to each other by at least one bond selected from the group consisting of a hydrogen bond and a covalent bond.

Abstract: An electronic component includes a first substrate and a second substrate. A first conductive layer constituting a terminal electrode is formed on a first surface of the first substrate. A first insulating layer is formed on the first conductive layer. The first insulating layer and the second substrate are directly bonded to each other by at least one bond selected from the group consisting of a hydrogen bond and a covalent bond.