A liquid discharge head includes a base plate, a cavity plate located on the base plate and including a cavity, and a piezoelectric actuator substrate located on the cavity plate. The cavity plate includes: a first groove located inside a contact region with the piezoelectric actuator substrate and configured to release an adhesive for bonding the cavity plate and the piezoelectric actuator substrate; and a second groove located in a manner to surround the contact region with the piezoelectric actuator substrate and configured to release the adhesive. The base plate includes a third groove configured to open the first groove to the atmosphere. The third groove is configured to communicate between the first groove and the outside through a first hole communicating with the first groove and a second hole located outside the contact region of the cavity plate and the piezoelectric actuator substrate.

A bonded substrate includes: a first substrate; and a second substrate having a bonding surface bonded to the first substrate, wherein the second substrate includes a recess having a bottom surface recessed from a surface opposite to the bonding surface, and a difference between the maximum height and the minimum height of the bottom surface from the surface opposite to the bonding surface of the recess is less than 10 .Math.m.

A channel member includes a first substrate in which a channel is formed from a first surface, and a second substrate having a second surface facing the first surface, wherein the first substrate and the second substrate are bonded to each other with an adhesive between the first surface and the second surface, wherein the channel has a polygonal shape when viewed from a direction orthogonal to the first surface, wherein the channel includes a first portion on the first surface side and a second portion that communicates with the first portion, wherein an aperture area of the second portion is larger than an aperture area of the first portion when viewed from the direction orthogonal to the first surface, and wherein the adhesive is present on a step surface between the first portion and the second portion and at vertices of the polygonal shape.

A flow path member includes a first substrate, a second substrate, bonding adhesive, and recessed portions. The first substrate has a first surface formed with an opening of a flow path. The second substrate has a second surface facing the first surface. The bonding adhesive bonds the first and second surfaces together. The recessed portions are formed in at least one of the first surface of the first substrate and the second surface of the second substrate. Each recessed portion is a hole configured to take up excess bonding adhesive and, as a non-through hole, does not extend through the entire thickness of a substrate. Each of the recessed portions extends into the first substrate or the second substrate as a rectangular column or an elliptical column and, when a shape of each recessed portion is viewed from the direction orthogonal to the first surface, the shape is approximately isotropic.

A piezoelectric device includes a piezoelectric body, a vibration plate that vibrates when the piezoelectric body is driven, a first electrode positioned between the piezoelectric body and the vibration plate, and a second electrode positioned to be separated from the first electrode by the piezoelectric body. The piezoelectric body has an active portion that is a part sandwiched between the first electrode and the second electrode in a first direction along a thickness direction of the piezoelectric body, and a change width of a dC/dV value, which represents a change in capacitance with respect to a change in a voltage applied along a second direction orthogonal to the first direction, from one end of the active portion on a side of the first electrode to the other end of the active portion on a side of the second electrode in the first direction is 10% or less.

An inkjet print head includes a plurality of droplet jetting devices. The plurality of droplet jetting devices is formed of a nozzle layer defining, for each of the plurality of droplet jetting devices, a nozzle, a membrane layer carrying, on a membrane, a restrictor layer and an actuator for generating pressure waves in a liquid in a pressure chamber that is connected to the nozzle. The actuator is positioned in an actuator chamber in the restrictor layer, and a distribution layer defining a supply line for supplying the liquid to the pressure chamber. The restrictor layer includes an inlet restrictor having a cross-section and an outlet restrictor positioned on opposites sides of the actuator and having a cross-section that is different from the cross-section of the inlet restrictor.

A liquid discharge head includes: a nozzle plate having: a nozzle from which a liquid is to be discharged in a liquid discharge direction; and a nozzle face having the nozzle, the nozzle face directed in the liquid discharge direction; a nozzle protector configured to cover a portion of the nozzle face other than the nozzle; and a channel substrate including: a bonding part bonded to the nozzle protector with an adhesive; and a recess in a transverse portion of the bonding part extending in a transverse direction of the liquid discharge head, the recess filled with the adhesive.

A fluid ejection assembly may include a fluid ejection die comprising a back face and a front face through which fluid is ejected. The fluid ejection die may further include a fan-out fluid passages converging towards the back face of the fluid ejection die, the fan-out fluid passages comprising a first fan-out fluid passage and a second fan-out fluid passage and a recirculation channel extending within a polymeric material from the first fan-out fluid passage to the second fan-out fluid passage adjacent the back face of the fluid ejection die.

A liquid discharge head configured to discharge a liquid, the liquid discharge head includes a thin film member including a first layer, a second layer bonded with the first layer, and a through hole penetrating through the first layer and the second layer. The through hole includes the first opening in the first layer and the second opening in the second layer.

A head chip, a liquid jet head, a liquid jet recording device, and a method of manufacturing a head chip each capable of ensuring the tolerance of the displacement between nozzle holes and communication holes while ensuring the bonding area between an actuator plate and an intermediate plate are provided. The head chip according to an aspect of the present disclosure includes an actuator plate, a nozzle plate disposed so as to be opposed to the actuator plate, and an intermediate plate disposed between the actuator plate and the nozzle plate. The communication holes each include a groove part having a lower-side opening part opening toward the nozzle hole, and a penetrating part having an upper-side opening part opening toward an ejection channel. A dimension in the X direction in the upper-side opening part is larger than a dimension in the X direction in the upper-side opening part, and a dimension in the X direction in the upper-side opening part is no larger than a dimension in the X direction of the channel opening part opening on a channel opening surface of the ejection channel.