A diaphragm pump includes a piezoelectric member, a diaphragm having surfaces, and a supporting member. The piezoelectric member deforms when a voltage is applied. The diaphragm deforms in response to deformation of the piezoelectric member. The supporting member supports the diaphragm. A space is formed between the diaphragm and the supporting member. Fluid is made to flow by changing a volume of the space by deforming the diaphragm. The surfaces of the diaphragm face the space and include a first surface that deforms in response to deformation of the piezoelectric member and include a second surface not connected to the first surface. The diaphragm bonds to the supporting member with the second surface.

A liquid discharging head includes a channel member which has a plurality of individual channels, each of the plurality of individual channels having a pressure chamber communicating with a nozzle, and a piezoelectric actuator which is configured to make the liquid discharge from the nozzle by causing a change in a pressure on a liquid inside the pressure chamber. The piezoelectric actuator has a thin-film piezoelectric element, and when a Helmholtz natural frequency of the pressure chamber is let to be Fr (kHz) and a diameter of the nozzle is let to be D (μm), a relationship

D<−0.0313×Fr+25.62 (provided that, 100 kHz≤Fr)

is satisfied, and a viscosity of the liquid discharged from the nozzle is not higher than 5 mPa.Math.s.

when one position where a distance in the second direction to the partition wall located at a nearest position in the second direction is long is assumed as a first position, and the other position where the distance is short is assumed as a second position, both the piezoelectric body and the vibration plate are provided at the first position and the second position, and a thickness of the vibration plate at the second position is smaller than a thickness of the vibration plate at the first position.

A liquid discharge head comprising a substrate comprising a liquid feeding port and an energy generating element for liquid discharge, and a flow channel member comprising, on the substrate, a discharge port through which a liquid is discharged and a liquid flow channel communicating with both the liquid feeding port and the discharge port, wherein the flow channel member comprises a flow channel member (1) not comprising a surface in contact with the liquid and a flow channel member (2) comprising a surface in contact with the liquid, a film stress S.sub.1 and S.sub.2 of the flow channel members (1) and (2), respectively, satisfy S.sub.1<S.sub.2, a film thickness L.sub.1 and L.sub.2 of the flow channel member (1) and (2), respectively, in a direction perpendicular to the substrate, satisfy L.sub.1<L.sub.2, and satisfying 470 MPa.Math.μm<[L.sub.1×S.sub.1+(L.sub.2−L.sub.1)×S.sub.2]<1200 MPa.Math.μm.

A thin-film piezoelectric material substrate includes an insulator on Si substrate and a thin-film laminated part. The insulator on Si substrate has a substrate for deposition made of silicon and an insulating layer formed on a surface of the substrate for deposition. The thin-film laminated part is formed on a top surface of the insulating layer. The thin-film laminated part has a YZ seed layer including yttrium and zirconium, and formed on the top surface; a lower electrode film laminated on the YZ seed layer; a piezoelectric material film made of lead zirconate titanate, shown by general formula Pb(Zr.sub.xTi.sub.(1-x))O.sub.3, and formed on the lower electrode film; and an upper electrode film laminated on the piezoelectric material film.

A liquid ejection apparatus and method of manufacture are disclosed. One apparatus includes a pressure chamber, a diaphragm covering the pressure chamber, and a piezoelectric element having a piezoelectric component positioned opposing the pressure chamber. The apparatus further includes a first electrode disposed on a first side of the piezoelectric component toward the pressure chamber and a second electrode disposed on a second side of the piezoelectric component opposite the first side in an opposed region, the opposed region being a region opposed to the second electrode. The apparatus also includes a metal film disposed between the piezoelectric component and the diaphragm, the metal film being absent from at least a portion of the opposed region. The metal film and the first electrode are in electrical contact with each other. The first electrode is made of platinum and the metal film is made of a metal material other than platinum.

A liquid discharge head includes a drive base, a flexible wiring substrate, and a mask plate. The drive base includes an array of nozzles on a surface of the drive base, a plurality of actuators corresponding to the array of nozzles, and a plurality of electrodes on the surface of the drive base and electrically connected to the plurality of actuators. The flexible wiring substrate is electrically connected to the plurality of electrodes. The mask plate covers a portion of the surface of the drive base, the plurality of electrodes, and an end portion of the flexible wiring substrate. The mask plate includes a recess portion facing the drive base.

A liquid ejection head having a channel member which includes an ejection hole surface and a pressurization chamber surface opposite thereto. An actuator substrate overlaps the pressurization chamber surface. The channel member includes a plurality of ejection holes opening in the ejection hole surface, a plurality of pressurization chambers individually communicating with the plurality of ejection holes and arranged in plan view of the pressurization chamber surface, and a plurality of dummy pressurization chambers positioned outside of the predetermined region in plan view of the pressurization chamber surface. The actuator substrate includes a plurality of pressurization portions that individually pressurize the pressurization chambers, and a plurality of dummy pressurization portions that individually pressurize the dummy pressurization chambers. The dummy pressurization chambers communicate with each other via a plurality of communication paths. A closed space including the plurality of dummy pressurization chambers and the plurality of communication paths is hermetically closed.

A method for manufacturing a piezoelectric actuator is disclosed that includes forming a vibration plate, forming a plurality of electrodes on the vibration plate, forming a piezoelectric layer on the electrodes, and forming a common electrode on the piezoelectric layer.

A piezoelectric actuator is provided, including a vibration plate, a piezoelectric layer, a plurality of individual electrodes arranged in two arrays, first and second common electrodes which have first and second facing portions facing parts of the individual electrodes and first and second connecting portions connecting the first and second facing portions respectively, and first and second wiring portions which are arranged on the vibration plate and which are connected to the first and second common electrodes respectively via first and second connecting wirings, wherein one of the first connecting wirings connects the first connecting portion and one of the first wiring portion while striding over the second connecting portion.